X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/6808e0f19ec9a9544241e26cf1e3179eb86bbd00..6d8e1b63fda70bb4153034870cc8b68f9011d0e1:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 4147ee205..eafd56fba 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -45,14 +45,16 @@ . Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.93" +.set previousversion "4.95" .include ./local_params .set ACL "access control lists (ACLs)" .set I "    " +.set drivernamemax "64" + .macro copyyear -2020 +2022 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -95,6 +97,21 @@ .itable none 0 0 2 $1 left $2 left .endmacro + +. --- A macro for a "tainted" marker, done as a one-element table +.macro tmark +.itable none 0 0 1 10pt left +.row &'Tainted'& +.endtable +.endmacro +. --- A macro for a tainted variable, adding a taint-marker +. --- and including the .vitem and .vindex +.macro tvar +.vitem $1 +.vindex $1 +.tmark +.endmacro + . --- A macro that generates .row, but puts &I; at the start of the first . --- argument, thus indenting it. Assume a minimum of two arguments, and . --- allow up to four arguments, which is as many as we'll ever need. @@ -161,6 +178,13 @@ .macro index .echo "** Don't use .index; use .cindex or .oindex or .vindex" .endmacro + + +. use this for a concept-index entry for a header line +.macro chindex +.cindex "&'$1'& header line" +.cindex "header lines" $1 +.endmacro . //////////////////////////////////////////////////////////////////////////// @@ -184,7 +208,7 @@ .copyyear - University of Cambridge + The Exim Maintainers .literal off @@ -193,6 +217,8 @@ . This chunk of literal XML implements index entries of the form "x, see y" and . "x, see also y". However, the DocBook DTD doesn't allow entries . at the top level, so we have to put the .chapter directive first. + +. These do not turn up in the HTML output, unfortunately. The PDF does get them. . ///////////////////////////////////////////////////////////////////////////// .chapter "Introduction" "CHID1" @@ -318,6 +344,10 @@ zero, binary binary zero + + headers + header lines + .literal off @@ -743,17 +773,17 @@ the Exim documentation, &"spool"& is always used in the first sense. .chapter "Incorporated code" "CHID2" .cindex "incorporated code" .cindex "regular expressions" "library" -.cindex "PCRE" +.cindex "PCRE2" .cindex "OpenDMARC" A number of pieces of external code are included in the Exim distribution. .ilist Regular expressions are supported in the main Exim program and in the -Exim monitor using the freely-distributable PCRE library, copyright -© University of Cambridge. The source to PCRE is no longer shipped with -Exim, so you will need to use the version of PCRE shipped with your system, +Exim monitor using the freely-distributable PCRE2 library, copyright +© University of Cambridge. The source to PCRE2 is not longer shipped with +Exim, so you will need to use the version of PCRE2 shipped with your system, or obtain and install the full version of the library from -&url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre). +&url(https://github.com/PhilipHazel/pcre2/releases). .next .cindex "cdb" "acknowledgment" Support for the cdb (Constant DataBase) lookup method is provided by code @@ -1394,9 +1424,21 @@ Again, cutthrough delivery counts as a verification. .next Individual routers can be explicitly skipped when running the routers to check an address given in the SMTP EXPN command (see the &%expn%& option). + .next If the &%domains%& option is set, the domain of the address must be in the set of domains that it defines. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using router domains option" +A match verifies the variable &$domain$& (which carries tainted data) +and assigns an untainted value to the &$domain_data$& variable. +Such an untainted value is often needed in the transport. +For specifics of the matching operation and the resulting untainted value, +refer to section &<>&. + +When an untainted value is wanted, use this option +rather than the generic &%condition%& option. + .next .vindex "&$local_part_prefix$&" .vindex "&$local_part_prefix_v$&" @@ -1405,15 +1447,24 @@ of domains that it defines. .vindex "&$local_part_suffix_v$&" .cindex affix "router precondition" If the &%local_parts%& option is set, the local part of the address must be in -the set of local parts that it defines. If &%local_part_prefix%& or +the set of local parts that it defines. +A match verifies the variable &$local_part$& (which carries tainted data) +and assigns an untainted value to the &$local_part_data$& variable. +Such an untainted value is often needed in the transport. +For specifics of the matching operation and the resulting untainted value, +refer to section &<>&. + +When an untainted value is wanted, use this option +rather than the generic &%condition%& option. + +If &%local_part_prefix%& or &%local_part_suffix%& is in use, the prefix or suffix is removed from the local part before this check. If you want to do precondition tests on local parts that include affixes, you can do so by using a &%condition%& option (see below) -.new that uses the variables &$local_part$&, &$local_part_prefix$&, &$local_part_prefix_v$&, &$local_part_suffix$& and &$local_part_suffix_v$& as necessary. -.wen + .next .vindex "&$local_user_uid$&" .vindex "&$local_user_gid$&" @@ -1423,23 +1474,35 @@ an account on the local host. If this check succeeds, the uid and gid of the local user are placed in &$local_user_uid$& and &$local_user_gid$& and the user's home directory is placed in &$home$&; these values can be used in the remaining preconditions. + .next If the &%router_home_directory%& option is set, it is expanded at this point, because it overrides the value of &$home$&. If this expansion were left till later, the value of &$home$& as set by &%check_local_user%& would be used in subsequent tests. Having two different values of &$home$& in the same router could lead to confusion. + .next If the &%senders%& option is set, the envelope sender address must be in the set of addresses that it defines. + .next If the &%require_files%& option is set, the existence or non-existence of specified files is tested. + .next .cindex "customizing" "precondition" If the &%condition%& option is set, it is evaluated and tested. This option uses an expanded string to allow you to set up your own custom preconditions. Expanded strings are described in chapter &<>&. + +Note that while using +this option for address matching technically works, +it does not set any de-tainted values. +Such values are often needed, either for router-specific options or +for transport options. +Using the &%domains%& and &%local_parts%& options is usually the most +convenient way to obtain them. .endlist @@ -1690,20 +1753,20 @@ overridden if necessary. A C99-capable compiler will be required for the build. -.section "PCRE library" "SECTpcre" -.cindex "PCRE library" -Exim no longer has an embedded PCRE library as the vast majority of -modern systems include PCRE as a system library, although you may need to -install the PCRE package or the PCRE development package for your operating -system. If your system has a normal PCRE installation the Exim build +.section "PCRE2 library" "SECTpcre" +.cindex "PCRE2 library" +Exim no longer has an embedded regular-expression library as the vast majority of +modern systems include PCRE2 as a system library, although you may need to +install the PCRE2 package or the PCRE2 development package for your operating +system. If your system has a normal PCRE2 installation the Exim build process will need no further configuration. If the library or the -headers are in an unusual location you will need to either set the PCRE_LIBS +headers are in an unusual location you will need to either set the PCRE2_LIBS and INCLUDE directives appropriately, -or set PCRE_CONFIG=yes to use the installed &(pcre-config)& command. +or set PCRE2_CONFIG=yes to use the installed &(pcre-config)& command. If your operating system has no -PCRE support then you will need to obtain and build the current PCRE -from &url(ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/). -More information on PCRE is available at &url(https://www.pcre.org/). +PCRE2 support then you will need to obtain and build the current PCRE2 +from &url(https://github.com/PhilipHazel/pcre2/releases). +More information on PCRE2 is available at &url(https://www.pcre.org/). .section "DBM libraries" "SECTdb" .cindex "DBM libraries" "discussion of" @@ -1756,9 +1819,13 @@ the traditional &'ndbm'& interface. .next To complicate things further, there are several very different versions of the Berkeley DB package. Version 1.85 was stable for a very long time, releases -2.&'x'& and 3.&'x'& were current for a while, but the latest versions when Exim last revamped support were numbered 4.&'x'&. -Maintenance of some of the earlier releases has ceased. All versions of -Berkeley DB could be obtained from +2.&'x'& and 3.&'x'& were current for a while, +.new +but the latest versions when Exim last revamped support were numbered 5.&'x'&. +Maintenance of some of the earlier releases has ceased, +and Exim no longer supports versions before 3.&'x'&. +.wen +All versions of Berkeley DB could be obtained from &url(http://www.sleepycat.com/), which is now a redirect to their new owner's page with far newer versions listed. It is probably wise to plan to move your storage configurations away from @@ -1782,6 +1849,9 @@ USE_DB=yes .endd Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An error is diagnosed if you set more than one of these. +.new +You can set USE_NDBM if needed to override an operating system default. +.wen At the lowest level, the build-time configuration sets none of these options, thereby assuming an interface of type (1). However, some operating system @@ -1796,7 +1866,11 @@ in one of these lines: .code DBMLIB = -ldb DBMLIB = -ltdb +DBMLIB = -lgdbm -lgdbm_compat .endd +.new +The last of those was for a Linux having GDBM provide emulated NDBM facilities. +.wen Settings like that will work if the DBM library is installed in the standard place. Sometimes it is not, and the library's header file may also not be in the default path. You may need to set INCLUDE to specify where the header @@ -2532,6 +2606,25 @@ use of Exim's filtering capabilities, you should make the document entitled +.section "Running the daemon" SECTdaemonLaunch +The most common command line for launching the Exim daemon looks like +.code +exim -bd -q5m +.endd +This starts a daemon which +.ilist +listens for incoming smtp connections, launching handler processes for +each new one +.next +starts a queue-runner process every five minutes, to inspect queued messages +and run delivery attempts on any that have arrived at their retry time +.endlist +Should a queue run take longer than the time between queue-runner starts, +they will run in parallel. +Numbers of jobs of the various types are subject to policy controls +defined in the configuration. + + .section "Upgrading Exim" "SECID36" .cindex "upgrading Exim" If you are already running Exim on your host, building and installing a new @@ -2645,10 +2738,8 @@ Exim through the local interface (see the &%-bm%& and &%-f%& options below). See the &%untrusted_set_sender%& option for a way of permitting non-trusted users to set envelope senders. -.cindex "&'From:'& header line" -.cindex "&'Sender:'& header line" -.cindex "header lines" "From:" -.cindex "header lines" "Sender:" +.chindex From: +.chindex Sender: For a trusted user, there is never any check on the contents of the &'From:'& header line, and a &'Sender:'& line is never added. Furthermore, any existing &'Sender:'& line in incoming local (non-TCP/IP) messages is not removed. @@ -3617,41 +3708,41 @@ of debugging data, respectively. For example, &%-d+filter%& adds filter debugging, whereas &%-d-all+filter%& selects only filter debugging. Note that no spaces are allowed in the debug setting. The available debugging categories are: -.display -&`acl `& ACL interpretation -&`auth `& authenticators -&`deliver `& general delivery logic -&`dns `& DNS lookups (see also resolver) -&`dnsbl `& DNS black list (aka RBL) code -&`exec `& arguments for &[execv()]& calls -&`expand `& detailed debugging for string expansions -&`filter `& filter handling -&`hints_lookup `& hints data lookups -&`host_lookup `& all types of name-to-IP address handling -&`ident `& ident lookup -&`interface `& lists of local interfaces -&`lists `& matching things in lists -&`load `& system load checks -&`local_scan `& can be used by &[local_scan()]& (see chapter &&& - &<>&) -&`lookup `& general lookup code and all lookups -&`memory `& memory handling -&`noutf8 `& modifier: avoid UTF-8 line-drawing -&`pid `& modifier: add pid to debug output lines -&`process_info `& setting info for the process log -&`queue_run `& queue runs -&`receive `& general message reception logic -&`resolver `& turn on the DNS resolver's debugging output -&`retry `& retry handling -&`rewrite `& address rewriting -&`route `& address routing -&`timestamp `& modifier: add timestamp to debug output lines -&`tls `& TLS logic -&`transport `& transports -&`uid `& changes of uid/gid and looking up uid/gid -&`verify `& address verification logic -&`all `& almost all of the above (see below), and also &%-v%& -.endd +.itable none 0 0 2 1pt left 1pt left +.irow acl "ACL interpretation" +.irow auth "authenticators" +.irow deliver "general delivery logic" +.irow dns "DNS lookups (see also resolver)" +.irow dnsbl "DNS black list (aka RBL) code" +.irow exec "arguments for &[execv()]& calls" +.irow expand "detailed debugging for string expansions" +.irow filter "filter handling" +.irow hints_lookup "hints data lookups" +.irow host_lookup "all types of name-to-IP address handling" +.irow ident "ident lookup" +.irow interface "lists of local interfaces" +.irow lists "matching things in lists" +.irow load "system load checks" +.irow local_scan "can be used by &[local_scan()]& (see chapter &&& + &<>&)" +.irow lookup "general lookup code and all lookups" +.irow memory "memory handling" +.irow noutf8 "modifier: avoid UTF-8 line-drawing" +.irow pid "modifier: add pid to debug output lines" +.irow process_info "setting info for the process log" +.irow queue_run "queue runs" +.irow receive "general message reception logic" +.irow resolver "turn on the DNS resolver's debugging output" +.irow retry "retry handling" +.irow rewrite "address rewriting"" +.irow route "address routing" +.irow timestamp "modifier: add timestamp to debug output lines" +.irow tls "TLS logic" +.irow transport "transports" +.irow uid "changes of uid/gid and looking up uid/gid" +.irow verify "address verification logic" +.irow all "almost all of the above (see below), and also &%-v%&" +.endtable The &`all`& option excludes &`memory`& when used as &`+all`&, but includes it for &`-all`&. The reason for this is that &`+all`& is something that people tend to use when generating debug output for Exim maintainers. If &`+memory`& @@ -3799,9 +3890,11 @@ headers.) .cindex "Solaris" "&'mail'& command" .cindex "dot" "in incoming non-SMTP message" This option, which has the same effect as &%-oi%&, specifies that a dot on a -line by itself should not terminate an incoming, non-SMTP message. I can find -no documentation for this option in Solaris 2.4 Sendmail, but the &'mailx'& -command in Solaris 2.4 uses it. See also &%-ti%&. +line by itself should not terminate an incoming, non-SMTP message. +Solaris 2.4 (SunOS 5.4) Sendmail has a similar &%-i%& processing option +&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf), +p. 1M-529), and therefore a &%-oi%& command line option, which both are used +by its &'mailx'& command. .vitem &%-L%&&~<&'tag'&> .oindex "&%-L%&" @@ -3847,7 +3940,9 @@ id, and the remaining ones must be email addresses. However, if the message is active (in the middle of a delivery attempt), it is not altered. This option can be used only by an admin user. -.vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&~<&'sequence&~number'&>&&& +.vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&&& + &~<&'host&~IP'&>&&& + &~<&'sequence&~number'&>&&& &~<&'message&~id'&>" .oindex "&%-MC%&" .cindex "SMTP" "passed connection" @@ -3871,13 +3966,11 @@ This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the remote host supports the ESMTP &_DSN_& extension. -.new .vitem &%-MCd%& .oindex "&%-MCd%&" This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-d%& option to pass on an information string on the purpose of the process. -.wen .vitem &%-MCG%&&~<&'queue&~name'&> .oindex "&%-MCG%&" @@ -3891,12 +3984,27 @@ This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that a remote host supports the ESMTP &_CHUNKING_& extension. +.vitem &%-MCL%& +.oindex "&%-MCL%&" +This option is not intended for use by external callers. It is used internally +by Exim in conjunction with the &%-MC%& option. It signifies that the server to +which Exim is connected advertised limits on numbers of mails, recipients or +recipient domains. +The limits are given by the following three arguments. + .vitem &%-MCP%& .oindex "&%-MCP%&" This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option. It signifies that the server to which Exim is connected supports pipelining. +.vitem &%-MCp%& +.oindex "&%-MCp%&" +This option is not intended for use by external callers. It is used internally +by Exim in conjunction with the &%-MC%& option. It signifies that the connection +t a remote server is via a SOCKS proxy, using addresses and ports given by +the following four arguments. + .vitem &%-MCQ%&&~<&'process&~id'&>&~<&'pipe&~fd'&> .oindex "&%-MCQ%&" This option is not intended for use by external callers. It is used internally @@ -3906,6 +4014,11 @@ together with the file descriptor number of an open pipe. Closure of the pipe signals the final completion of the sequence of processes that are passing messages through the same SMTP connection. +.vitem &%-MCq%&&~<&'recipient&~address'&>&~<&'size'&> +.oindex "&%-MCq%&" +This option is not intended for use by external callers. It is used internally +by Exim to implement quota checking for local users. + .vitem &%-MCS%& .oindex "&%-MCS%&" This option is not intended for use by external callers. It is used internally @@ -3919,6 +4032,16 @@ This option is not intended for use by external callers. It is used internally by Exim in conjunction with the &%-MC%& option, and passes on the fact that the host to which Exim is connected supports TLS encryption. +.vitem &%-MCr%&&~<&'SNI'&> &&& + &%-MCs%&&~<&'SNI'&> +.oindex "&%-MCs%&" +.oindex "&%-MCr%&" +These options are not intended for use by external callers. It is used internally +by Exim in conjunction with the &%-MCt%& option, and passes on the fact that +a TLS Server Name Indication was sent as part of the channel establishment. +The argument gives the SNI string. +The "r" variant indicates a DANE-verified connection. + .vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&> .oindex "&%-MCt%&" This option is not intended for use by external callers. It is used internally @@ -4083,8 +4206,9 @@ the standard output. This option can be used only by an admin user. .vitem &%-m%& .oindex "&%-m%&" -This is apparently a synonym for &%-om%& that is accepted by Sendmail, so Exim -treats it that way too. +This is a synonym for &%-om%& that is accepted by Sendmail +(&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf) +p. 1M-258), so Exim treats it that way too. .vitem &%-N%& .oindex "&%-N%&" @@ -4397,7 +4521,6 @@ written. When &%-oX%& is used with &%-bd%&, or when &%-q%& with a time is used without &%-bd%&, this is the only way of causing Exim to write a pid file, because in those cases, the normal pid file is not used. -.new .vitem &%-oPX%& .oindex "&%-oPX%&" .cindex "pid (process id)" "of daemon" @@ -4406,7 +4529,6 @@ This option is not intended for general use. The daemon uses it when terminating due to a SIGTEM, possibly in combination with &%-oP%&&~<&'path'&>. It causes the pid file to be removed. -.wen .vitem &%-or%&&~<&'time'&> .oindex "&%-or%&" @@ -4440,6 +4562,25 @@ of the syntax, and how it interacts with configuration file options, are given in chapter &<>&. When &%-oX%& is used to start a daemon, no pid file is written unless &%-oP%& is also present to specify a pid filename. +.vitem &%-oY%& +.oindex &%-oY%& +.cindex "daemon notifier socket" +This option controls the creation of an inter-process communications endpoint +by the Exim daemon. +It is only relevant when the &%-bd%& (start listening daemon) option is also +given. +Normally the daemon creates this socket, unless a &%-oX%& and &*no*& &%-oP%& +option is also present. +If this option is given then the socket will not be created. This could be +required if the system is running multiple daemons. + +The socket is currently used for +.ilist +fast ramp-up of queue runner processes +.next +obtaining a current queue size +.endlist + .vitem &%-pd%& .oindex "&%-pd%&" .cindex "Perl" "starting the interpreter" @@ -4518,14 +4659,17 @@ appear in the correct order. Each flag is described in a separate item below. .cindex "queue" "routing" .cindex "routing" "whole queue before delivery" .cindex "first pass routing" +.cindex "queue runner" "two phase" An option starting with &%-qq%& requests a two-stage queue run. In the first stage, the queue is scanned as if the &%queue_smtp_domains%& option matched every domain. Addresses are routed, local deliveries happen, but no remote transports are run. -.new Performance will be best if the &%queue_run_in_order%& option is false. -.wen +If that is so and the &%queue_fast_ramp%& option is true then +in the first phase of the run, +once a threshold number of messages are routed for a given host, +a delivery process is forked in parallel with the rest of the scan. .cindex "hints database" "remembering routing" The hints database that remembers which messages are waiting for specific hosts @@ -4705,9 +4849,9 @@ recognized when Exim is run normally. It allows for the setting up of explicit .vitem &%-t%& .oindex "&%-t%&" .cindex "recipient" "extracting from header lines" -.cindex "&'Bcc:'& header line" -.cindex "&'Cc:'& header line" -.cindex "&'To:'& header line" +.chindex Bcc: +.chindex Cc: +.chindex To: When Exim is receiving a locally-generated, non-SMTP message on its standard input, the &%-t%& option causes the recipients of the message to be obtained from the &'To:'&, &'Cc:'&, and &'Bcc:'& header lines in the message instead of @@ -5399,8 +5543,8 @@ local_interfaces = 127.0.0.1 : ::::1 contains two IP addresses, the IPv4 address 127.0.0.1 and the IPv6 address ::1. &*Note*&: Although leading and trailing white space is ignored in individual -list items, it is not ignored when parsing the list. The space after the first -colon in the example above is necessary. If it were not there, the list would +list items, it is not ignored when parsing the list. The spaces around the first +colon in the example above are necessary. If they were not there, the list would be interpreted as the two items 127.0.0.1:: and 1. .section "Changing list separators" "SECTlistsepchange" @@ -5859,7 +6003,7 @@ Libraries you use may depend on specific environment settings. This imposes a security risk (e.g. PATH). There are two lists: &%keep_environment%& for the variables to import as they are, and &%add_environment%& for variables we want to set to a fixed value. -Note that TZ is handled separately, by the $%timezone%$ runtime +Note that TZ is handled separately, by the &%timezone%& runtime option and by the TIMEZONE_DEFAULT buildtime option. .code # keep_environment = ^LDAP @@ -6334,9 +6478,9 @@ smarthost_smtp: # request with your smarthost provider to get things fixed: hosts_require_tls = * tls_verify_hosts = * - # As long as tls_verify_hosts is enabled, this won't matter, but if you - # have to comment it out then this will at least log whether you succeed - # or not: + # As long as tls_verify_hosts is enabled, this this will have no effect, + # but if you have to comment it out then this will at least log whether + # you succeed or not: tls_try_verify_hosts = * # # The SNI name should match the name which we'll expect to verify; @@ -6391,13 +6535,11 @@ local_delivery: This &(appendfile)& transport is used for local delivery to user mailboxes in traditional BSD mailbox format. -.new We prefer to avoid using &$local_part$& directly to define the mailbox filename, as it is provided by a potential bad actor. Instead we use &$local_part_data$&, the result of looking up &$local_part$& in the user database (done by using &%check_local_user%& in the the router). -.wen By default &(appendfile)& runs under the uid and gid of the local user, which requires the sticky bit to be set on the &_/var/mail_& @@ -6531,9 +6673,9 @@ Chapter &<>& covers both. .chapter "Regular expressions" "CHAPregexp" .cindex "regular expressions" "library" -.cindex "PCRE" +.cindex "PCRE2" Exim supports the use of regular expressions in many of its options. It -uses the PCRE regular expression library; this provides regular expression +uses the PCRE2 regular expression library; this provides regular expression matching that is compatible with Perl 5. The syntax and semantics of regular expressions is discussed in online Perl manpages, in @@ -6545,10 +6687,10 @@ O'Reilly (see &url(http://www.oreilly.com/catalog/regex2/)). . --- to the old URL for now. 2018-09-07. The documentation for the syntax and semantics of the regular expressions that -are supported by PCRE is included in the PCRE distribution, and no further -description is included here. The PCRE functions are called from Exim using -the default option settings (that is, with no PCRE options set), except that -the PCRE_CASELESS option is set when the matching is required to be +are supported by PCRE2 is included in the PCRE2 distribution, and no further +description is included here. The PCRE2 functions are called from Exim using +the default option settings (that is, with no PCRE2 options set), except that +the PCRE2_CASELESS option is set when the matching is required to be case-insensitive. In most cases, when a regular expression is required in an Exim configuration, @@ -6604,14 +6746,15 @@ cause parts of the string to be replaced by data that is obtained from the lookup. Lookups of this type are conditional expansion items. Different results can be defined for the cases of lookup success and failure. See chapter &<>&, where string expansions are described in detail. -The key for the lookup is specified as part of the string expansion. +The key for the lookup is &*specified*& as part of the string expansion. .next Lists of domains, hosts, and email addresses can contain lookup requests as a way of avoiding excessively long linear lists. In this case, the data that is returned by the lookup is often (but not always) discarded; whether the lookup succeeds or fails is what really counts. These kinds of list are described in chapter &<>&. -The key for the lookup is given by the context in which the list is expanded. +The key for the lookup is &*implicit*&, +given by the context in which the list is expanded. .endlist String expansions, lists, and lookups interact with each other in such a way @@ -6631,6 +6774,9 @@ domains = ${lookup{$sender_host_address}lsearch{/some/file}} domains = lsearch;/some/file .endd The first uses a string expansion, the result of which must be a domain list. +.new +The key for an expansion-style lookup must be given explicitly. +.wen No strings have been specified for a successful or a failing lookup; the defaults in this case are the looked-up data and an empty string, respectively. The expansion takes place before the string is processed as a list, and the @@ -6642,11 +6788,13 @@ file that is searched could contain lines like this: When the lookup succeeds, the result of the expansion is a list of domains (and possibly other types of item that are allowed in domain lists). .cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using a lookup expansion"" The result of the expansion is not tainted. In the second example, the lookup is a single item in a domain list. It causes Exim to use a lookup to see if the domain that is being processed can be found -in the file. The file could contains lines like this: +in the file. +The file could contains lines like this: .code domain1: domain2: @@ -6654,6 +6802,12 @@ domain2: Any data that follows the keys is not relevant when checking that the domain matches the list item. +.new +The key for a list-style lookup is implicit, from the lookup context, if +the lookup is a single-key type (see below). +For query-style lookup types the key must be given explicitly. +.wen + It is possible, though no doubt confusing, to use both kinds of lookup at once. Consider a file containing lines like this: .code @@ -6663,12 +6817,15 @@ If the value of &$sender_host_address$& is 192.168.5.6, expansion of the first &%domains%& setting above generates the second setting, which therefore causes a second lookup to occur. -.new The lookup type may optionally be followed by a comma and a comma-separated list of options. Each option is a &"name=value"& pair. -Whether an option is meaningful depands on the lookup type. -.wen +Whether an option is meaningful depends on the lookup type. + +All lookups support the option &"cache=no_rd"&. +If this is given then the cache that Exim manages for lookup results +is not checked before doing the lookup. +The result of the lookup is still written to the cache. The rest of this chapter describes the different lookup types that are available. Any of them can be used in any part of the configuration where a @@ -6684,22 +6841,27 @@ Two different types of data lookup are implemented: The &'single-key'& type requires the specification of a file in which to look, and a single key to search for. The key must be a non-empty string for the lookup to succeed. The lookup type determines how the file is searched. -.new .cindex "tainted data" "single-key lookups" -The file string may not be tainted +The file string may not be tainted. .cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using a single-key lookup" All single-key lookups support the option &"ret=key"&. If this is given and the lookup (either underlying implementation or cached value) returns data, the result is replaced with a non-tainted version of the lookup key. -.wen .next .cindex "query-style lookup" "definition of" The &'query-style'& type accepts a generalized database query. No particular key value is assumed by Exim for query-style lookups. You can use whichever Exim variables you need to construct the database query. +.cindex "tainted data" "quoting for lookups" +.new +If tainted data is used in the query then it should be quuted by +using the &*${quote_*&<&'lookup-type'&>&*:*&<&'string'&>&*}*& expansion operator +appropriate for the lookup. +.wen .endlist The code for each lookup type is in a separate source file that is included in @@ -6787,15 +6949,12 @@ by default, but has an option to omit them (see section &<>&). .cindex "lookup" "dsearch" .cindex "dsearch lookup type" &(dsearch)&: The given file must be an -.new absolute -.wen directory path; this is searched for an entry whose name is the key by calling the &[lstat()]& function. The key may not contain any forward slash characters. If &[lstat()]& succeeds then so does the lookup. -.new .cindex "tainted data" "dsearch result" The result is regarded as untainted. @@ -6819,7 +6978,6 @@ ${lookup {passwd} dsearch,filter=file {/etc}} .endd The default matching is for any entry type, including directories and symlinks. -.wen An example of how this lookup can be used to support virtual domains is given in section @@ -6855,6 +7013,11 @@ the implicit key is the host's IP address rather than its name (see section &*Warning 3*&: Do not use an IPv4-mapped IPv6 address for a key; use the IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this notation before executing the lookup.) + +One option is supported, "ret=full", to request the return of the entire line +rather than omitting the key portion. +Note however that the key portion will have been de-quoted. + .next .cindex lookup json .cindex json "lookup type" @@ -6872,6 +7035,27 @@ The final resulting element can be a simple JSON type or a JSON object or array; for the latter two a string-representation of the JSON is returned. For elements of type string, the returned value is de-quoted. + + +.next +.cindex LMDB +.cindex lookup lmdb +.cindex database lmdb +&(lmdb)&: The given file is an LMDB database. +LMDB is a memory-mapped key-value store, +with API modeled loosely on that of BerkeleyDB. +See &url(https://symas.com/products/lightning-memory-mapped-database/) +for the feature set and operation modes. + +Exim provides read-only access via the LMDB C library. +The library can be obtained from &url(https://github.com/LMDB/lmdb) +or your operating system package repository. +To enable LMDB support in Exim set LOOKUP_LMDB=yes in &_Local/Makefile_&. + +You will need to separately create the LMDB database file, +possibly using the &"mdb_load"& utility. + + .next .cindex "linear search" .cindex "lookup" "lsearch" @@ -7068,11 +7252,7 @@ passed to a Redis database. See section &<>&. .cindex "sqlite lookup type" .cindex "lookup" "sqlite" &(sqlite)&: The format of the query is -new -an optional filename -.wen -followed by an SQL statement -that is passed to an SQLite database. See section &<>&. +an SQL statement that is passed to an SQLite database. See section &<>&. .next &(testdb)&: This is a lookup type that is used for testing Exim. It is @@ -7275,6 +7455,10 @@ lookups. However, because (apart from the daemon) Exim operates as a collection of independent, short-lived processes, this caching applies only within a single Exim process. There is no inter-process lookup caching facility. +If an option &"cache=no_rd"& is used on the lookup then +the cache is only written to, cached data is not used for the operation +and a real lookup is done. + For single-key lookups, Exim keeps the relevant files open in case there is another lookup that needs them. In some types of configuration this can lead to many files being kept open for messages with many recipients. To avoid hitting @@ -7742,16 +7926,16 @@ be preceded by any number of <&'name'&>=<&'value'&> settings, separated by spaces. If a value contains spaces it must be enclosed in double quotes, and when double quotes are used, backslash is interpreted in the usual way inside them. The following names are recognized: -.display -&`DEREFERENCE`& set the dereferencing parameter -&`NETTIME `& set a timeout for a network operation -&`USER `& set the DN, for authenticating the LDAP bind -&`PASS `& set the password, likewise -&`REFERRALS `& set the referrals parameter -&`SERVERS `& set alternate server list for this query only -&`SIZE `& set the limit for the number of entries returned -&`TIME `& set the maximum waiting time for a query -.endd +.itable none 0 0 2 1pt left 1pt left +.irow DEREFERENCE "set the dereferencing parameter" +.irow NETTIME "set a timeout for a network operation" +.irow USER "set the DN, for authenticating the LDAP bind" +.irow PASS "set the password, likewise" +.irow REFERRALS "set the referrals parameter" +.irow SERVERS "set alternate server list for this query only" +.irow SIZE "set the limit for the number of entries returned" +.irow TIME "set the maximum waiting time for a query" +.endtable The value of the DEREFERENCE parameter must be one of the words &"never"&, &"searching"&, &"finding"&, or &"always"&. The value of the REFERRALS parameter must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP @@ -8033,14 +8217,12 @@ The &%quote_redis%& expansion operator escapes whitespace and backslash characters with a backslash. .section "Specifying the server in the query" "SECTspeserque" -.new For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase), it is possible to specify a list of servers with an individual query. This is done by appending a comma-separated option to the query type: .display -.endd &`,servers=`&&'server1:server2:server3:...'& -.wen +.endd Each item in the list may take one of two forms: .olist If it contains no slashes it is assumed to be just a host name. The appropriate @@ -8074,8 +8256,7 @@ option, you can still update it by a query of this form: ${lookup pgsql,servers=master/db/name/pw {UPDATE ...} } .endd -.new -An older syntax places the servers speciification before the qury, +An older syntax places the servers specification before the query, semicolon separated: .code ${lookup mysql{servers=master; UPDATE ...} } @@ -8083,7 +8264,6 @@ ${lookup mysql{servers=master; UPDATE ...} } The new version avoids potential issues with tainted arguments in the query, for explicit expansion. &*Note*&: server specifications in list-style lookups are still problematic. -.wen .section "Special MySQL features" "SECID73" @@ -8135,21 +8315,26 @@ SQLite is different to the other SQL lookups because a filename is required in addition to the SQL query. An SQLite database is a single file, and there is no daemon as in the other SQL databases. -.new .oindex &%sqlite_dbfile%& -The preferred way of specifying the file is by using the -&%sqlite_dbfile%& option, set to -an absolute path. -.wen +There are two ways of +specifying the file. +The first is is by using the &%sqlite_dbfile%& main option. +The second, which allows separate files for each query, +is to use an option appended, comma-separated, to the &"sqlite"& +lookup type word. The option is the word &"file"&, then an equals, +then the filename. +The filename in this case cannot contain whitespace or open-brace charachters. + A deprecated method is available, prefixing the query with the filename separated by white space. -This means that the path name cannot contain white space. +This means that .cindex "tainted data" "sqlite file" -It also means that the query cannot use any tainted values, as that taints +the query cannot use any tainted values, as that taints the entire query including the filename - resulting in a refusal to open the file. -.new +In all the above cases the filename must be an absolute path. + Here is a lookup expansion example: .code sqlite_dbfile = /some/thing/sqlitedb @@ -8161,7 +8346,6 @@ In a list, the syntax is similar. For example: domainlist relay_to_domains = sqlite;\ select * from relays where ip='$sender_host_address'; .endd -.wen The only character affected by the &%quote_sqlite%& operator is a single quote, which it doubles. @@ -8351,7 +8535,6 @@ in the previous section. You could also use the &(wildlsearch)& or -.new .section "Results of list checking" SECTlistresults The primary result of doing a list check is a truth value. In some contexts additional information is stored @@ -8365,6 +8548,7 @@ A &%local_parts%& router option or &%local_parts%& ACL condition will store a result in the &$local_part_data$& variable. .vitem domains A &%domains%& router option or &%domains%& ACL condition +will store a result in the &$domain_data$& variable. .vitem senders A &%senders%& router option or &%senders%& ACL condition will store a result in the &$sender_data$& variable. @@ -8375,7 +8559,6 @@ will store a result in the &$recipient_data$& variable. The detail of the additional information depends on the type of match and is given below as the &*value*& information. -.wen @@ -8438,7 +8621,6 @@ domainlist dom2 = !a.b : *.b where &'x.y'& does not match. It's best to avoid negation altogether in referenced lists if you can. -.new .cindex "hiding named list values" .cindex "named lists" "hiding value of" Some named list definitions may contain sensitive data, for example, passwords for @@ -8448,7 +8630,6 @@ word &"hide"&. For example: .code hide domainlist filter_for_domains = ldap;PASS=secret ldap::/// ... .endd -.wen Named lists may have a performance advantage. When Exim is routing an @@ -8543,9 +8724,7 @@ as set by the &%primary_hostname%& option (or defaulted). This makes it possible to use the same configuration file on several different hosts that differ only in their names. -.new The value for a match will be the primary host name. -.wen .next @@ -8560,9 +8739,7 @@ control which of a host's several IP addresses are treated as local. In today's Internet, the use of domain literals is controversial; see the &%allow_domain_literals%& main option. -.new The value for a match will be the string &`@[]`&. -.wen .next @@ -8613,9 +8790,7 @@ involved, it is easiest to change the delimiter for the main list as well: domains = >&) to specify that it is not to be expanded (unless you really do want to build a regular expression by expansion, of course). -.new The value for a match will be the list element string (starting with the circumflex). Additionally, &$0$& will be set to the string matching the regular expression, and &$1$& (onwards) to any submatches identified by parentheses. -.wen @@ -8679,8 +8850,14 @@ or a &%domains%& condition in an ACL statement, the value is preserved in the &$domain_data$& variable and can be referred to in other router options or other statements in the same ACL. .cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using ACL domains condition" The value will be untainted. +&*Note*&: If the data result of the lookup (as opposed to the key) +is empty, then this empty value is stored in &$domain_data$&. +The option to return the key for the lookup, as the value, +may be what is wanted. + .next Any of the single-key lookup type names may be preceded by @@ -8715,16 +8892,15 @@ whether or not the query succeeds. However, when a lookup is used for the &%domains%& option on a router, the value is preserved in the &$domain_data$& variable and can be referred to in other options. .cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using router domains option" The value will be untainted. .next -.new If the pattern starts with the name of a lookup type of either kind (single-key or query-style) it may be followed by a comma and options, The options are lookup-type specific and consist of a comma-separated list. -Each item starts with a tag and and equals "=". -.wen +Each item starts with a tag and and equals "=" sign. .next .cindex "domain list" "matching literal domain name" @@ -8735,8 +8911,13 @@ The value for a match will be the list element string. .cindex "tainted data" "de-tainting" Note that this is commonly untainted (depending on the way the list was created). +Specifically, explicit text in the configuration file in not tainted. This is a useful way of obtaining an untainted equivalent to the domain, for later operations. + +However if the list (including one-element lists) +is created by expanding a variable containing tainted data, +it is tainted and so will the match value be. .endlist @@ -8838,9 +9019,13 @@ accept hosts = @[] .endd .next .cindex "CIDR notation" -If the pattern is an IP address followed by a slash and a mask length (for -example 10.11.42.0/24), it is matched against the IP address of the subject -host under the given mask. This allows, an entire network of hosts to be +If the pattern is an IP address followed by a slash and a mask length, for +example +.code +10.11.42.0/24 +.endd +, it is matched against the IP address of the subject +host under the given mask. This allows an entire network of hosts to be included (or excluded) by a single item. The mask uses CIDR notation; it specifies the number of address bits that must match, starting from the most significant end of the address. @@ -9409,6 +9594,9 @@ become case-sensitive after &"+caseful"& has been seen. .section "Local part lists" "SECTlocparlis" .cindex "list" "local part list" .cindex "local part" "list" +These behave in the same way as domain and host lists, with the following +changes: + Case-sensitivity in local part lists is handled in the same way as for address lists, as just described. The &"+caseful"& item can be used if required. In a setting of the &%local_parts%& option in a router with &%caseful_local_part%& @@ -9453,9 +9641,19 @@ the data type. ACL rules always expand strings. A couple of expansion conditions do not expand some of the brace-delimited branches, for security reasons, .cindex "tainted data" expansion +.cindex "tainted data" definition .cindex expansion "tainted data" and expansion of data deriving from the sender (&"tainted data"&) -is not permitted. +is not permitted (including acessing a file using a tainted name). + +Common ways of obtaining untainted equivalents of variables with +tainted values +.cindex "tainted data" "de-tainting" +come down to using the tainted value as a lookup key in a trusted database. +This database could be the filesystem structure, +or the password file, +or accessed via a DBMS. +Specific methods are indexed under &"de-tainting"&. @@ -9602,7 +9800,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&" .cindex authentication "results header" -.cindex headers "authentication-results:" +.chindex Authentication-Results: .cindex authentication "expansion item" This item returns a string suitable for insertion as an &'Authentication-Results:'& @@ -10012,7 +10210,7 @@ They are visible in DKIM, PRDR and DATA ACLs. Header lines that are added in a RCPT ACL (for example) are saved until the message's incoming header lines are available, at which point they are added. -When any of the above ACLs ar +When any of the above ACLs are running, however, header lines added by earlier ACLs are visible. Upper case and lower case letters are synonymous in header names. If the @@ -10033,11 +10231,9 @@ newline at the very end. For the &%header%& and &%bheader%& expansion, for those headers that contain lists of addresses, a comma is also inserted at the junctions between headers. This does not happen for the &%rheader%& expansion. -.new -.cindex "tainted data" +.cindex "tainted data" "message headers" When the headers are from an incoming message, the result of expanding any of these variables is tainted. -.wen .vitem &*${hmac{*&<&'hashname'&>&*}{*&<&'secret'&>&*}{*&<&'string'&>&*}}*& @@ -10170,12 +10366,19 @@ extracted is used. You can use &`fail`& instead of {<&'string3'&>} as in a string extract. -.vitem "&*${lookup{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& - {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" -This is the first of one of two different types of lookup item, which are both -described in the next item. +.vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*& +.cindex quoting "for list" +.cindex list quoting +This item doubles any occurrence of the separator character +in the given string. +An empty string is replaced with a single space. +This converts the string into a safe form for use as a list element, +in a list using the given separator. + -.vitem "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&& +.vitem "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& + {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" &&& + "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&& {*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" .cindex "expansion" "lookup in" .cindex "file" "lookups" @@ -10281,10 +10484,11 @@ additional arguments need be given; the maximum number permitted, including the name of the subroutine, is nine. The return value of the subroutine is inserted into the expanded string, unless -the return value is &%undef%&. In that case, the expansion fails in the same -way as an explicit &"fail"& on a lookup item. The return value is a scalar. -Whatever you return is evaluated in a scalar context. For example, if you -return the name of a Perl vector, the return value is the size of the vector, +the return value is &%undef%&. In that case, the entire expansion is +forced to fail, in the same way as an explicit &"fail"& on a lookup item +does (see section &<>&). Whatever you return is evaluated +in a scalar context, thus the return value is a scalar. For example, if you +return a Perl vector, the return value is the size of the vector, not its contents. If the subroutine exits by calling Perl's &%die%& function, the expansion fails @@ -10334,7 +10538,7 @@ For more discussion and an example, see section &<>&. .cindex "expansion" "inserting an entire file" .cindex "file" "inserting into expansion" .cindex "&%readfile%& expansion item" -The filename and end-of-line string are first expanded separately. The file is +The filename and end-of-line (eol) string are first expanded separately. The file is then read, and its contents replace the entire item. All newline characters in the file are replaced by the end-of-line string if it is present. Otherwise, newlines are left in the string. @@ -10371,7 +10575,7 @@ ${readsocket{inet:[::1]:1234}{request string}} Only a single host name may be given, but if looking it up yields more than one IP address, they are each tried in turn until a connection is made. For both kinds of socket, Exim makes a connection, writes the request string -unless it is an empty string; and no terminating NUL is ever sent) +(unless it is an empty string; no terminating NUL is ever sent) and reads from the socket until an end-of-file is read. A timeout of 5 seconds is applied. Additional, optional arguments extend what can be done. Firstly, you can vary the timeout. For example: @@ -10387,7 +10591,6 @@ Example: ${readsocket{/socket/name}{request string}{3s:shutdown=no}} .endd -.new The following option names are recognised: .ilist &*cache*& @@ -10407,9 +10610,8 @@ sending the request. Values are &"yes"& (the default) or &"no"& &*tls*& Controls the use of TLS on the connection. Values are &"yes"& or &"no"& (the default). -If it is enabled, a shutdown as descripbed above is never done. +If it is enabled, a shutdown as described above is never done. .endlist -.wen A fourth argument allows you to change any newlines that are in the data @@ -10480,16 +10682,32 @@ expansion items. This item inserts &"raw"& header lines. It is described with the &%header%& expansion item in section &<>& above. -.vitem "&*${run{*&<&'command'&>&*&~*&<&'args'&>&*}{*&<&'string1'&>&*}&&& +.vitem "&*${run <&'options'&> {*&<&'command&~arg&~list'&>&*}{*&<&'string1'&>&*}&&& {*&<&'string2'&>&*}}*&" .cindex "expansion" "running a command" .cindex "&%run%& expansion item" -The command and its arguments are first expanded as one string. The string is -split apart into individual arguments by spaces, and then the command is run +This item runs an external command, as a subprocess. +.new +One option is supported after the word &'run'&, comma-separated. + +If the option &'preexpand'& is not used, +the command string is split into individual arguments by spaces +and then each argument is expanded. +Then the command is run in a separate process, but under the same uid and gid. As in other command executions from Exim, a shell is not used by default. If the command requires a shell, you must explicitly code it. +The command name may not be tainted, but the remaining arguments can be. + +&*Note*&: if tainted arguments are used, they are supplied by a +potential attacker; +a careful assessment for security vulnerabilities should be done. +If the option &'preexpand'& is used, +.wen +the command and its arguments are first expanded as one string. The result is +split apart into individual arguments by spaces, and then the command is run +as above. Since the arguments are split by spaces, when there is a variable expansion which has an empty result, it will cause the situation that the argument will simply be omitted when the program is actually executed by Exim. If the @@ -10500,6 +10718,9 @@ in a string containing quotes, because it would interfere with the quotes around the command arguments. A possible guard against this is to wrap the variable in the &%sg%& operator to change any quote marks to some other character. +.new +Neither the command nor any argument may be tainted. +.wen The standard input for the command exists, but is empty. The standard output and standard error are set to the same file descriptor. @@ -10611,16 +10832,22 @@ ${sort {${lookup dnsdb{>:,,mx=example.com}}} {<} {${listextract{1}{<,$item}}}} will sort an MX lookup into priority order. -.vitem &*${substr{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*& + +.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*& +SRS encoding. See SECT &<>& for details. + + + +.vitem &*${substr{*&<&'start'&>&*}{*&<&'len'&>&*}{*&<&'subject'&>&*}}*& .cindex "&%substr%& expansion item" .cindex "substring extraction" .cindex "expansion" "substring extraction" The three strings are expanded; the first two must yield numbers. Call them <&'n'&> and <&'m'&>. If you are using fixed values for these numbers, that is, -if <&'string1'&> and <&'string2'&> do not change when they are expanded, you +if <&'start'&> and <&'len'&> do not change when they are expanded, you can use the simpler operator notation that avoids some of the braces: .code -${substr__:} +${substr__:} .endd The second number is optional (in both notations). If it is absent in the simpler format, the preceding underscore must also be @@ -10831,7 +11058,7 @@ is controlled by the &%print_topbitchars%& option. .vitem &*${escape8bit:*&<&'string'&>&*}*& .cindex "expansion" "escaping 8-bit characters" .cindex "&%escape8bit%& expansion item" -If the string contains and characters with the most significant bit set, +If the string contains any characters with the most significant bit set, they are converted to escape sequences starting with a backslash. Backslashes and DEL characters are also converted. @@ -11027,6 +11254,8 @@ If the optional type is given it must be one of "a", "d", "h" or "l" and selects address-, domain-, host- or localpart- lists to search among respectively. Otherwise all types are searched in an undefined order and the first matching list is returned. +&*Note*&: Neither string-expansion of lists referenced by named-list syntax elements, +nor expansion of lookup elements, is done by the &%listnamed%& operator. .vitem &*${local_part:*&<&'string'&>&*}*& @@ -11038,7 +11267,8 @@ empty. The parsing correctly handles SMTPUTF8 Unicode in the string. -.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& +.vitem &*${mask:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& &&& + &*${mask_n:*&<&'IP&~address'&>&*/*&<&'bit&~count'&>&*}*& .cindex "masked IP address" .cindex "IP address" "masking" .cindex "CIDR notation" @@ -11052,8 +11282,14 @@ the result back to text, with mask appended. For example, .code ${mask:10.111.131.206/28} .endd -returns the string &"10.111.131.192/28"&. Since this operation is expected to -be mostly used for looking up masked addresses in files, the result for an IPv6 +returns the string &"10.111.131.192/28"&. + +Since this operation is expected to +be mostly used for looking up masked addresses in files, the +.new +normal +.wen +result for an IPv6 address uses dots to separate components instead of colons, because colon terminates a key string in lsearch files. So, for example, .code @@ -11063,6 +11299,10 @@ returns the string .code 3ffe.ffff.836f.0a00.000a.0800.2000.0000/99 .endd +.new +If the optional form &*mask_n*& is used, IPv6 address result are instead +returned in normailsed form, using colons and with zero-compression. +.wen Letters in IPv6 addresses are always output in lower case. @@ -11294,7 +11534,7 @@ Now deprecated, a synonym for the &%base64%& expansion operator. .cindex "expansion" "string length" .cindex "string" "length in expansion" .cindex "&%strlen%& expansion item" -The item is replace by the length of the expanded string, expressed as a +The item is replaced by the length of the expanded string, expressed as a decimal number. &*Note*&: Do not confuse &%strlen%& with &%length%&. All measurement is done in bytes and is not UTF-8 aware. @@ -11394,14 +11634,14 @@ condition. .cindex "expansion" "numeric comparison" There are a number of symbolic operators for doing numeric comparisons. They are: -.display -&`= `& equal -&`== `& equal -&`> `& greater -&`>= `& greater or equal -&`< `& less -&`<= `& less or equal -.endd +.itable none 0 0 2 1pt left 1pt left +.irow "= " "equal" +.irow "== " "equal" +.irow "> " "greater" +.irow ">= " "greater or equal" +.irow "< " "less" +.irow "<= " "less or equal" +.endtable For example: .code ${if >{$message_size}{10M} ... @@ -11589,6 +11829,10 @@ condition is true if the named file (or directory) exists. The existence test is done by calling the &[stat()]& function. The use of the &%exists%& test in users' filter files may be locked out by the system administrator. +&*Note:*& Testing a path using this condition is not a sufficient way of +de-tainting it. +Consider using a dsearch lookup. + .vitem &*first_delivery*& .cindex "delivery" "first" .cindex "first delivery" @@ -11673,6 +11917,11 @@ includes the case of letters, whereas for &%gti%& the comparison is case-independent. Case and collation order are defined per the system C locale. + +.vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*& +SRS decode. See SECT &<>& for details. + + .vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& &*inlisti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "string" "comparison" @@ -11691,6 +11940,20 @@ ${if inlisti{Needle}{fOo:NeeDLE:bAr}} ${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}} .endd +.new +The variable &$value$& will be set for a successful match and can be +used in the success clause of an &%if%& expansion item using the condition. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using an inlist expansion condition" +It will have the same taint status as the list; expansions such as +.code +${if inlist {$h_mycode:} {0 : 1 : 42} {$value}} +.endd +can be used for de-tainting. +Any previous &$value$& is restored after the if. +.wen + + .vitem &*isip&~{*&<&'string'&>&*}*& &&& &*isip4&~{*&<&'string'&>&*}*& &&& &*isip6&~{*&<&'string'&>&*}*& @@ -11887,6 +12150,19 @@ item can be used, as in all address lists, to cause subsequent items to have their local parts matched casefully. Domains are always matched caselessly. +.new +The variable &$value$& will be set for a successful match and can be +used in the success clause of an &%if%& expansion item using the condition. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using a match_local_part expansion condition" +It will have the same taint status as the list; expansions such as +.code +${if match_local_part {$local_part} {alice : bill : charlotte : dave} {$value}} +.endd +can be used for de-tainting. +Any previous &$value$& is restored after the if. +.wen + Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. @@ -11903,8 +12179,9 @@ matched using &%match_ip%&. .cindex "&%pam%& expansion condition" &'Pluggable Authentication Modules'& (&url(https://mirrors.edge.kernel.org/pub/linux/libs/pam/)) are a facility that is -available in the latest releases of Solaris and in some GNU/Linux -distributions. The Exim support, which is intended for use in conjunction with +available in Solaris +and in some GNU/Linux distributions. +The Exim support, which is intended for use in conjunction with the SMTP AUTH command, is available only if Exim is compiled with .code SUPPORT_PAM=yes @@ -11922,15 +12199,12 @@ request, for a password, so the data consists of just two strings. There can be problems if any of the strings are permitted to contain colon characters. In the usual way, these have to be doubled to avoid being taken as -separators. If the data is being inserted from a variable, the &%sg%& expansion -item can be used to double any existing colons. For example, the configuration +separators. +The &%listquote%& expansion item can be used for this. +For example, the configuration of a LOGIN authenticator might contain this setting: .code -server_condition = ${if pam{$auth1:${sg{$auth2}{:}{::}}}} -.endd -For a PLAIN authenticator you could use: -.code -server_condition = ${if pam{$auth2:${sg{$auth3}{:}{::}}}} +server_condition = ${if pam{$auth1:${listquote{:}{$auth2}}}} .endd In some operating systems, PAM authentication can be done only from a process running as root. Since Exim is running as the Exim user when receiving @@ -12084,6 +12358,16 @@ parsed but not evaluated. This section contains an alphabetical list of all the expansion variables. Some of them are available only when Exim is compiled with specific options such as support for TLS or the content scanning extension. +.new +.cindex "tainted data" +Variables marked as &'tainted'& are likely to carry data supplied by +a potential attacker. +Variables without such marking may also, depending on how their +values are created. +Such variables should not be further expanded, +used as filenames +or used as command-line arguments for external commands. +.wen .vlist .vitem "&$0$&, &$1$&, etc" @@ -12098,6 +12382,9 @@ variables may also be set externally by some other matching process which precedes the expansion of the string. For example, the commands available in Exim filter files include an &%if%& command with its own regular expression matching condition. +.new +If the subject string was tainted then any captured substring will also be. +.wen .vitem "&$acl_arg1$&, &$acl_arg2$&, etc" Within an acl condition, expansion condition or expansion item @@ -12132,8 +12419,8 @@ this variable has the number of arguments. .vitem &$acl_verify_message$& .vindex "&$acl_verify_message$&" After an address verification has failed, this variable contains the failure -message. It retains its value for use in subsequent modifiers. The message can -be preserved by coding like this: +message. It retains its value for use in subsequent modifiers of the verb. +The message can be preserved by coding like this: .code warn !verify = sender set acl_m0 = $acl_verify_message @@ -12141,6 +12428,7 @@ warn !verify = sender You can use &$acl_verify_message$& during the expansion of the &%message%& or &%log_message%& modifiers, to include information about the verification failure. +&*Note*&: The variable is cleared at the end of processing the ACL verb. .vitem &$address_data$& .vindex "&$address_data$&" @@ -12188,7 +12476,7 @@ to the relevant file. When, as a result of aliasing or forwarding, a message is directed to a pipe, this variable holds the pipe command when the transport is running. -.vitem "&$auth1$& &-- &$auth3$&" +.vitem "&$auth1$& &-- &$auth4$&" .vindex "&$auth1$&, &$auth2$&, etc" These variables are used in SMTP authenticators (see chapters &<>&&--&<>&). Elsewhere, they are empty. @@ -12222,11 +12510,10 @@ authentication, which means this variable could also be visible in all of the ACL's as well. -.vitem &$authenticated_sender$& +.tvar &$authenticated_sender$& .cindex "sender" "authenticated" .cindex "authentication" "sender" .cindex "AUTH" "on MAIL command" -.vindex "&$authenticated_sender$&" When acting as a server, Exim takes note of the AUTH= parameter on an incoming SMTP MAIL command if it believes the sender is sufficiently trusted, as described in section &<>&. Unless the data is the string @@ -12249,9 +12536,10 @@ command that does not succeed. Otherwise it is set to &"0"&. This makes it possible to distinguish between &"did not try to authenticate"& (&$sender_host_authenticated$& is empty and &$authentication_failed$& is set to &"0"&) and &"tried to authenticate but failed"& (&$sender_host_authenticated$& -is empty and &$authentication_failed$& is set to &"1"&). Failure includes any -negative response to an AUTH command, including (for example) an attempt to use -an undefined mechanism. +is empty and &$authentication_failed$& is set to &"1"&). +Failure includes cancellation of a authentication attempt, +and any negative response to an AUTH command, +(including, for example, an attempt to use an undefined mechanism). .vitem &$av_failed$& .cindex "content scanning" "AV scanner failure" @@ -12378,8 +12666,7 @@ the following data from the lookup: the list's domain name, the key that was looked up, the contents of any associated TXT record, and the value from the main A record. See section &<>& for more details. -.vitem &$domain$& -.vindex "&$domain$&" +.tvar &$domain$& When an address is being routed, or delivered on its own, this variable contains the domain. Uppercase letters in the domain are converted into lower case for &$domain$&. @@ -12432,29 +12719,32 @@ When the &%smtp_etrn_command%& option is being expanded, &$domain$& contains the complete argument of the ETRN command (see section &<>&). .endlist -.new .cindex "tainted data" If the origin of the data is an incoming message, -the result of expanding this variable is tainted. -When un untainted version is needed, one should be obtained from +the result of expanding this variable is tainted and may not +be further expanded or used as a filename. +When an untainted version is needed, one should be obtained from looking up the value in a local (therefore trusted) database. Often &$domain_data$& is usable in this role. -.wen .vitem &$domain_data$& .vindex "&$domain_data$&" -When the &%domains%& option on a router matches a domain by -means of a lookup, the data read by the lookup is available during the running -of the router as &$domain_data$&. In addition, if the driver routes the +When the &%domains%& condition on a router +or an ACL +matches a domain +against a list, the match value is copied to &$domain_data$&. +This is an enhancement over previous versions of Exim, when it only +applied to the data read by a lookup. +For details on match values see section &<>& et. al. + +If the router routes the address to a transport, the value is available in that transport. If the transport is handling multiple addresses, the value from the first address is used. -&$domain_data$& is also set when the &%domains%& condition in an ACL matches a -domain by means of a lookup. The data read by the lookup is available during -the rest of the ACL statement. In all other situations, this variable expands -to nothing. +&$domain_data$& set in an ACL is available during +the rest of the ACL statement. .vitem &$exim_gid$& .vindex "&$exim_gid$&" @@ -12477,6 +12767,7 @@ There may be other characters following the minor version. This value may be overridden by the &%exim_version%& main config option. .vitem &$header_$&<&'name'&> +.tmark This is not strictly an expansion variable. It is expansion syntax for inserting the message header line with the given name. Note that the name must be terminated by colon or white space, because it may contain a wide variety of @@ -12537,6 +12828,7 @@ allows you, for example, to do things like this: deny hosts = net-lsearch;/some/file message = $host_data .endd + .vitem &$host_lookup_deferred$& .cindex "host name" "lookup, failure of" .vindex "&$host_lookup_deferred$&" @@ -12594,13 +12886,11 @@ option in the &(appendfile)& transport. The variable contains the inode number of the temporary file which is about to be renamed. It can be used to construct a unique name for the file. -.vitem &$interface_address$& +.vitem &$interface_address$& &&& + &$interface_port$& .vindex "&$interface_address$&" -This is an obsolete name for &$received_ip_address$&. - -.vitem &$interface_port$& .vindex "&$interface_port$&" -This is an obsolete name for &$received_port$&. +These are obsolete names for &$received_ip_address$& and &$received_port$&. .vitem &$item$& .vindex "&$item$&" @@ -12621,8 +12911,7 @@ This variable contains the system load average, multiplied by 1000 so that it is an integer. For example, if the load average is 0.21, the value of the variable is 210. The value is recomputed every time the variable is referenced. -.vitem &$local_part$& -.vindex "&$local_part$&" +.tvar &$local_part$& When an address is being routed, or delivered on its own, this variable contains the local part. When a number of addresses are being delivered together (for example, multiple RCPT commands in an SMTP @@ -12634,10 +12923,10 @@ Global address rewriting happens when a message is received, so the value of because a message may have many recipients and the system filter is called just once. -.new .cindex "tainted data" If the origin of the data is an incoming message, -the result of expanding this variable is tainted. +the result of expanding this variable is tainted and +may not be further expanded or used as a filename. &*Warning*&: the content of this variable is usually provided by a potential attacker. @@ -12652,7 +12941,6 @@ rather than this variable. Often &$local_part_data$& is usable in this role. If needed, use a router &%address_data%& or &%set%& option for the retrieved data. -.wen When a message is being delivered to a file, pipe, or autoreply transport as a result of aliasing or forwarding, &$local_part$& is set to the local part of @@ -12688,20 +12976,14 @@ to process local parts in a case-dependent manner in a router, you can set the .vitem &$local_part_data$& .vindex "&$local_part_data$&" -When the &%local_parts%& option on a router matches a local part by means of a -lookup, the data read by the lookup is available during the running of the -router as &$local_part_data$&. In addition, if the driver routes the address -to a transport, the value is available in that transport. If the transport is -handling multiple addresses, the value from the first address is used. +When the &%local_parts%& condition on a router or ACL +matches a local part list +the match value is copied to &$local_part_data$&. +This is an enhancement over previous versions of Exim, when it only +applied to the data read by a lookup. +For details on match values see section &<>& et. al. -.new The &%check_local_user%& router option also sets this variable. -.wen - -&$local_part_data$& is also set when the &%local_parts%& condition in an ACL -matches a local part by means of a lookup. The data read by the lookup is -available during the rest of the ACL statement. In all other situations, this -variable expands to nothing. .vindex &$local_part_prefix$& &&& &$local_part_prefix_v$& &&& @@ -12712,7 +12994,6 @@ If a local part prefix or suffix has been recognized, it is not included in the value of &$local_part$& during routing and subsequent delivery. The values of any prefix or suffix are in &$local_part_prefix$& and &$local_part_suffix$&, respectively. -.new .cindex "tainted data" If the specification did not include a wildcard then the affix variable value is not tainted. @@ -12721,7 +13002,6 @@ If the affix specification included a wildcard then the portion of the affix matched by the wildcard is in &$local_part_prefix_v$& or &$local_part_suffix_v$& as appropriate, and both the whole and varying values are tainted. -.wen .vitem &$local_scan_data$& .vindex "&$local_scan_data$&" @@ -12797,7 +13077,7 @@ when the ACL &%malware%& condition is true (see section &<>&). This variable contains the number of bytes in the longest line that was received as part of the message, not counting the line termination character(s). -It is not valid if the &%spool_files_wireformat%& option is used. +It is not valid if the &%spool_wireformat%& option is used. .vitem &$message_age$& .cindex "message" "age of" @@ -12806,11 +13086,10 @@ This variable is set at the start of a delivery attempt to contain the number of seconds since the message was received. It does not change during a single delivery attempt. -.vitem &$message_body$& +.tvar &$message_body$& .cindex "body of message" "expansion variable" .cindex "message body" "in expansion" .cindex "binary zero" "in message body" -.vindex "&$message_body$&" .oindex "&%message_body_visible%&" This variable contains the initial portion of a message's body while it is being delivered, and is intended mainly for use in filter files. The maximum @@ -12823,10 +13102,9 @@ easier to search for phrases that might be split over a line break. However, this can be disabled by setting &%message_body_newlines%& to be true. Binary zeros are always converted into spaces. -.vitem &$message_body_end$& +.tvar &$message_body_end$& .cindex "body of message" "expansion variable" .cindex "message body" "in expansion" -.vindex "&$message_body_end$&" This variable contains the final portion of a message's body while it is being delivered. The format and maximum size are as for &$message_body$&. @@ -12841,7 +13119,7 @@ separates the body from the header. Newlines are included in the count. See also &$message_size$&, &$body_linecount$&, and &$body_zerocount$&. If the spool file is wireformat -(see the &%spool_files_wireformat%& main option) +(see the &%spool_wireformat%& main option) the CRLF line-terminators are included in the count. .vitem &$message_exim_id$& @@ -12853,15 +13131,13 @@ received. &*Note*&: This is &'not'& the contents of the &'Message-ID:'& header line; it is the local id that Exim assigns to the message, for example: &`1BXTIK-0001yO-VA`&. -.vitem &$message_headers$& -.vindex &$message_headers$& +.tvar &$message_headers$& This variable contains a concatenation of all the header lines when a message is being processed, except for lines added by routers or transports. The header lines are separated by newline characters. Their contents are decoded in the same way as a header line that is inserted by &%bheader%&. -.vitem &$message_headers_raw$& -.vindex &$message_headers_raw$& +.tvar &$message_headers_raw$& This variable is like &$message_headers$& except that no processing of the contents of header lines is done. @@ -12894,7 +13170,7 @@ deny condition = \ In the MAIL and RCPT ACLs, the value is zero because at that stage the message has not yet been received. -This variable is not valid if the &%spool_files_wireformat%& option is used. +This variable is not valid if the &%spool_wireformat%& option is used. .vitem &$message_size$& .cindex "size" "of message" @@ -12914,7 +13190,22 @@ While running a per message ACL (mail/rcpt/predata), &$message_size$& contains the size supplied on the MAIL command, or -1 if no size was given. The value may not, of course, be truthful. -.vitem &$mime_$&&'xxx'& +.vitem &$mime_anomaly_level$& &&& + &$mime_anomaly_text$& &&& + &$mime_boundary$& &&& + &$mime_charset$& &&& + &$mime_content_description$& &&& + &$mime_content_disposition$& &&& + &$mime_content_id$& &&& + &$mime_content_size$& &&& + &$mime_content_transfer_encoding$& &&& + &$mime_content_type$& &&& + &$mime_decoded_filename$& &&& + &$mime_filename$& &&& + &$mime_is_coverletter$& &&& + &$mime_is_multipart$& &&& + &$mime_is_rfc822$& &&& + &$mime_part_count$& A number of variables whose names start with &$mime$& are available when Exim is compiled with the content-scanning extension. For details, see section &<>&. @@ -12923,9 +13214,8 @@ details, see section &<>&. These variables are counters that can be incremented by means of the &%add%& command in filter files. -.vitem &$original_domain$& +.tvar &$original_domain$& .vindex "&$domain$&" -.vindex "&$original_domain$&" When a top-level address is being processed for delivery, this contains the same value as &$domain$&. However, if a &"child"& address (for example, generated by an alias, forward, or filter file) is being processed, this @@ -12938,9 +13228,8 @@ If a new address is created by means of a &%deliver%& command in a system filter, it is set up with an artificial &"parent"& address. This has the local part &'system-filter'& and the default qualify domain. -.vitem &$original_local_part$& +.tvar &$original_local_part$& .vindex "&$local_part$&" -.vindex "&$original_local_part$&" When a top-level address is being processed for delivery, this contains the same value as &$local_part$&, unless a prefix or suffix was removed from the local part, because &$original_local_part$& always contains the full local @@ -12978,13 +13267,11 @@ messages received via the command line, this is the uid of the sending user. For messages received by SMTP over TCP/IP, this is normally the uid of the Exim user. -.vitem &$parent_domain$& -.vindex "&$parent_domain$&" +.tvar &$parent_domain$& This variable is similar to &$original_domain$& (see above), except that it refers to the immediately preceding parent address. -.vitem &$parent_local_part$& -.vindex "&$parent_local_part$&" +.tvar &$parent_local_part$& This variable is similar to &$original_local_part$& (see above), except that it refers to the immediately preceding parent address. @@ -13003,6 +13290,11 @@ This is not an expansion variable, but is mentioned here because the string (described under &%transport_filter%& in chapter &<>&). It cannot be used in general expansion strings, and provokes an &"unknown variable"& error if encountered. +.new +&*Note*&: This value permits data supplied by a potential attacker to +be used in the command for a &(pipe)& transport. +Such configurations should be carefully assessed for security vulnerbilities. +.wen .vitem &$primary_hostname$& .vindex "&$primary_hostname$&" @@ -13027,18 +13319,10 @@ For details see chapter &<>&. This variable is set to &"yes"& if PRDR was requested by the client for the current message, otherwise &"no"&. -.vitem &$prvscheck_address$& -This variable is used in conjunction with the &%prvscheck%& expansion item, -which is described in sections &<>& and -&<>&. - -.vitem &$prvscheck_keynum$& -This variable is used in conjunction with the &%prvscheck%& expansion item, -which is described in sections &<>& and -&<>&. - -.vitem &$prvscheck_result$& -This variable is used in conjunction with the &%prvscheck%& expansion item, +.vitem &$prvscheck_address$& &&& + &$prvscheck_keynum$& &&& + &$prvscheck_result$& +These variables are used in conjunction with the &%prvscheck%& expansion item, which is described in sections &<>& and &<>&. @@ -13063,6 +13347,8 @@ The name of the spool queue in use; empty for the default queue. .cindex "spool" "number of messages" This variable contains the number of messages queued. It is evaluated on demand, but no more often than once every minute. +If there is no daemon notifier socket open, the value will be +an empty string. .vitem &$r_...$& .vindex &$r_...$& @@ -13098,18 +13384,19 @@ including the one added by Exim (so its value is always greater than zero). It is available in the DATA ACL, the non-SMTP ACL, and while routing and delivering. -.vitem &$received_for$& -.vindex "&$received_for$&" +.tvar &$received_for$& If there is only a single recipient address in an incoming message, this variable contains that address when the &'Received:'& header line is being built. The value is copied after recipient rewriting has happened, but before the &[local_scan()]& function is run. -.vitem &$received_ip_address$& +.vitem &$received_ip_address$& &&& + &$received_port$& .vindex "&$received_ip_address$&" -As soon as an Exim server starts processing an incoming TCP/IP connection, this -variable is set to the address of the local IP interface, and &$received_port$& -is set to the local port number. (The remote IP address and port are in +.vindex "&$received_port$&" +As soon as an Exim server starts processing an incoming TCP/IP connection, these +variables are set to the address and port on the local IP interface. +(The remote IP address and port are in &$sender_host_address$& and &$sender_host_port$&.) When testing with &%-bh%&, the port value is -1 unless it has been set using the &%-oMi%& command line option. @@ -13122,10 +13409,6 @@ messages that are received, thus making these variables available at delivery time. For outbound connections see &$sending_ip_address$&. -.vitem &$received_port$& -.vindex "&$received_port$&" -See &$received_ip_address$&. - .vitem &$received_protocol$& .vindex "&$received_protocol$&" When a message is being processed, this variable contains the name of the @@ -13193,8 +13476,7 @@ MAIL). The main use of this variable is expected to be to distinguish between rejections of MAIL and rejections of RCPT. -.vitem &$recipients$& -.vindex "&$recipients$&" +.tvar &$recipients$& This variable contains a list of envelope recipients for a message. A comma and a space separate the addresses in the replacement text. However, the variable is not generally available, to prevent exposure of Bcc recipients in @@ -13231,10 +13513,12 @@ This variable is set to contain the matching regular expression after a When a &%regex%& or &%mime_regex%& ACL condition succeeds, these variables contain the captured substrings identified by the regular expression. +.new +If the subject string was tainted then so will any captured substring. +.wen -.vitem &$reply_address$& -.vindex "&$reply_address$&" +.tvar &$reply_address$& When a message is being processed, this variable contains the contents of the &'Reply-To:'& header line if one exists and it is not empty, or otherwise the contents of the &'From:'& header line. Apart from the removal of leading @@ -13283,8 +13567,7 @@ One of its values causes the address to be passed to another router. When this happens, &$self_hostname$& is set to the name of the local host that the original router encountered. In other circumstances its contents are null. -.vitem &$sender_address$& -.vindex "&$sender_address$&" +.tvar &$sender_address$& When a message is being processed, this variable contains the sender's address that was received in the message's envelope. The case of letters in the address is retained, in both the local part and the domain. For bounce messages, the @@ -13299,12 +13582,10 @@ distinguish it from data from a recipient address. The value does not persist after the end of the current ACL statement. If you want to preserve it for longer, you can save it in an ACL variable. -.vitem &$sender_address_domain$& -.vindex "&$sender_address_domain$&" +.tvar &$sender_address_domain$& The domain portion of &$sender_address$&. -.vitem &$sender_address_local_part$& -.vindex "&$sender_address_local_part$&" +.tvar &$sender_address_local_part$& The local part portion of &$sender_address$&. .vitem &$sender_data$& @@ -13342,8 +13623,7 @@ This boolean variable is true if a successful HELO verification was .cindex "DNS" "DNSSEC" done using DNS information the resolver library stated was authenticated data. -.vitem &$sender_helo_name$& -.vindex "&$sender_helo_name$&" +.tvar &$sender_helo_name$& When a message is received from a remote host that has issued a HELO or EHLO command, the argument of that command is placed in this variable. It is also set if HELO or EHLO is used when a message is received using SMTP locally via @@ -13378,7 +13658,6 @@ library, by setting: dns_dnssec_ok = 1 .endd -.new In addition, on Linux with glibc 2.31 or newer the resolver library will default to stripping out a successful validation status. This will break a previously working Exim installation. @@ -13388,7 +13667,6 @@ glibc to pass through any successful validation with a new option in .code options trust-ad .endd -.wen Exim does not perform DNSSEC validation itself, instead leaving that to a validating resolver (e.g. unbound, or bind with suitable configuration). @@ -13402,8 +13680,7 @@ all EDNS0 options, then this will have no effect. OpenBSD's asr resolver is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3). -.vitem &$sender_host_name$& -.vindex "&$sender_host_name$&" +.tvar &$sender_host_name$& When a message is received from a remote host, this variable contains the host's name as obtained by looking up its IP address. For messages received by other means, this variable is empty. @@ -13521,8 +13798,7 @@ host name, as specified by the &%smtp_active_hostname%& option. The value of &$smtp_active_hostname$& is saved with any message that is received, so its value can be consulted during routing and delivery. -.vitem &$smtp_command$& -.vindex "&$smtp_command$&" +.tvar &$smtp_command$& During the processing of an incoming SMTP command, this variable contains the entire command. This makes it possible to distinguish between HELO and EHLO in the HELO ACL, and also to distinguish between commands such as these: @@ -13535,9 +13811,8 @@ command, the address in &$smtp_command$& is the original address before any rewriting, whereas the values in &$local_part$& and &$domain$& are taken from the address after SMTP-time rewriting. -.vitem &$smtp_command_argument$& +.tvar &$smtp_command_argument$& .cindex "SMTP" "command, argument for" -.vindex "&$smtp_command_argument$&" While an ACL is running to check an SMTP command, this variable contains the argument, that is, the text that follows the command name, with leading white space removed. Following the introduction of &$smtp_command$&, this variable is @@ -13569,7 +13844,11 @@ filter file to set values that can be tested in users' filter files. For example, a system filter could set a value indicating how likely it is that a message is junk mail. -.vitem &$spam_$&&'xxx'& +.vitem &$spam_score$& &&& + &$spam_score_int$& &&& + &$spam_bar$& &&& + &$spam_report$& &&& + &$spam_action$& A number of variables whose names start with &$spam$& are available when Exim is compiled with the content-scanning extension. For details, see section &<>&. @@ -13765,10 +14044,20 @@ the value of the Distinguished Name of the certificate is made available in the If certificate verification fails it may refer to a failing chain element which is not the leaf. -.vitem &$tls_in_sni$& -.vindex "&$tls_in_sni$&" + +.vitem &$tls_in_resumption$& &&& + &$tls_out_resumption$& +.vindex &$tls_in_resumption$& +.vindex &$tls_out_resumption$& +.cindex TLS resumption +Observability for TLS session resumption. See &<>& for details. + + +.tvar &$tls_in_sni$& .vindex "&$tls_sni$&" .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI "observability on server" When a TLS session is being established, if the client sends the Server Name Indication extension, the value will be placed in this variable. If the variable appears in &%tls_certificate%& then this option and @@ -13784,6 +14073,8 @@ the outbound. .vitem &$tls_out_sni$& .vindex "&$tls_out_sni$&" .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI "observability in client" During outbound SMTP deliveries, this variable reflects the value of the &%tls_sni%& option on the transport. @@ -13944,6 +14235,8 @@ taint mode of the Perl interpreter. You are encouraged to set this option to a true value. To avoid breaking existing installations, it defaults to false. +&*Note*&: This is entirely separate from Exim's tainted-data tracking. + .section "Calling Perl subroutines" "SECID86" When the configuration file includes a &%perl_startup%& option you can make use @@ -14378,9 +14671,11 @@ listed in more than one group. .section "Miscellaneous" "SECID96" .table2 +.row &%add_environment%& "environment variables" .row &%bi_command%& "to run for &%-bi%& command line option" .row &%debug_store%& "do extra internal checks" .row &%disable_ipv6%& "do no IPv6 processing" +.row &%keep_environment%& "environment variables" .row &%keep_malformed%& "for broken files &-- should not happen" .row &%localhost_number%& "for unique message ids in clusters" .row &%message_body_newlines%& "retain newlines in &$message_body$&" @@ -14501,6 +14796,7 @@ listed in more than one group. .row &%notifier_socket%& "override compiled-in value" .row &%pid_file_path%& "override compiled-in value" .row &%queue_run_max%& "maximum simultaneous queue runners" +.row &%smtp_backlog_monitor%& "level to log listen backlog" .endtable @@ -14576,8 +14872,10 @@ listed in more than one group. .row &%local_scan_timeout%& "timeout for &[local_scan()]&" .row &%message_size_limit%& "for all messages" .row &%percent_hack_domains%& "recognize %-hack for these domains" +.row &%proxy_protocol_timeout%& "timeout for proxy protocol negotiation" .row &%spamd_address%& "set interface to SpamAssassin" .row &%strict_acl_vars%& "object to unset ACL variables" +.row &%spf_smtp_comment_template%& "template for &$spf_smtp_comment$&" .endtable @@ -14599,8 +14897,10 @@ listed in more than one group. .table2 .row &%gnutls_compat_mode%& "use GnuTLS compatibility mode" .row &%gnutls_allow_auto_pkcs11%& "allow GnuTLS to autoload PKCS11 modules" +.row &%hosts_require_alpn%& "mandatory ALPN" .row &%openssl_options%& "adjust OpenSSL compatibility options" .row &%tls_advertise_hosts%& "advertise TLS to these hosts" +.row &%tls_alpn%& "acceptable protocol names" .row &%tls_certificate%& "location of server certificate" .row &%tls_crl%& "certificate revocation list" .row &%tls_dh_max_bits%& "clamp D-H bit count suggestion" @@ -14768,6 +15068,7 @@ See also the &'Policy controls'& section above. .row &%hold_domains%& "hold delivery for these domains" .row &%local_interfaces%& "for routing checks" .row &%queue_domains%& "no immediate delivery for these" +.row &%queue_fast_ramp%& "parallel delivery with 2-phase queue run" .row &%queue_only%& "no immediate delivery at all" .row &%queue_only_file%& "no immediate delivery if file exists" .row &%queue_only_load%& "no immediate delivery if load is high" @@ -14984,7 +15285,6 @@ domains (defined in the named domain list &%local_domains%& in the default configuration). This &"magic string"& matches the domain literal form of all the local host's IP addresses. - .option allow_mx_to_ip main boolean false .cindex "MX record" "pointing to IP address" It appears that more and more DNS zone administrators are breaking the rules @@ -15096,11 +15396,9 @@ required, it must come from the &%-oA%& command line option. This option defines a template file containing paragraphs of text to be used for constructing bounce messages. Details of the file's contents are given in chapter &<>&. -.new .cindex bounce_message_file "tainted data" The option is expanded to give the file path, which must be absolute and untainted. -.wen See also &%warn_message_file%&. @@ -15427,11 +15725,9 @@ etc. are ignored. If IP literals are enabled, the &(ipliteral)& router declines to handle IPv6 literal addresses. -.new .option dkim_verify_hashes main "string list" "sha256 : sha512" .cindex DKIM "selecting signature algorithms" This option gives a list of hash types which are acceptable in signatures, -.wen and an order of processing. Signatures with algorithms not in the list will be ignored. @@ -15450,14 +15746,12 @@ and an order of processing. Signatures with algorithms not in the list will be ignored. -.new .option dkim_verify_min_keysizes main "string list" "rsa=1024 ed25519=250" This option gives a list of key sizes which are acceptable in signatures. The list is keyed by the algorithm type for the key; the values are in bits. Signatures with keys smaller than given by this option will fail verification. The default enforces the RFC 8301 minimum key size for RSA signatures. -.wen .option dkim_verify_minimal main boolean false If set to true, verification of signatures will terminate after the @@ -15549,7 +15843,6 @@ default. A value of 0 coerces DNSSEC off, a value of 1 coerces DNSSEC on. If the resolver library does not support DNSSEC then this option has no effect. -.new On Linux with glibc 2.31 or newer this is insufficient, the resolver library will default to stripping out a successful validation status. This will break a previously working Exim installation. @@ -15559,7 +15852,6 @@ glibc to pass through any successful validation with a new option in .code options trust-ad .endd -.wen .option dns_ipv4_lookup main "domain list&!!" unset @@ -15653,15 +15945,13 @@ described in section &<>&. .cindex "ESMTP extensions" DSN DSN extensions (RFC3461) will be advertised in the EHLO message to, and accepted from, these hosts. -Hosts may use the NOTIFY and ENVID options on RCPT TO commands, -and RET and ORCPT options on MAIL FROM commands. +Hosts may use the NOTIFY and ORCPT options on RCPT TO commands, +and RET and ENVID options on MAIL FROM commands. A NOTIFY=SUCCESS option requests success-DSN messages. A NOTIFY= option with no argument requests that no delay or failure DSNs are sent. -.new &*Note*&: Supplying success-DSN messages has been criticised on privacy grounds; it can leak details of internal forwarding. -.wen .option dsn_from main "string&!!" "see below" .cindex "&'From:'& header line" "in bounces" @@ -16098,6 +16388,18 @@ hosts_connection_nolog = : If the &%smtp_connection%& log selector is not set, this option has no effect. +.option hosts_require_alpn main "host list&!!" unset +.cindex ALPN "require negotiation in server" +.cindex TLS ALPN +.cindex TLS "Application Layer Protocol Names" +If the TLS library supports ALPN +then a successful negotiation of ALPN will be required for any client +matching the list, for TLS to be used. +See also the &%tls_alpn%& option. + +&*Note*&: prevention of fallback to in-clear connection is not +managed by this option, and should be done separately. + .option hosts_proxy main "host list&!!" unset .cindex proxy "proxy protocol" @@ -16625,7 +16927,6 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)& transport driver. -.new .option notifier_socket main string "$spool_directory/exim_daemon_notify" This option gives the name for a unix-domain socket on which the daemon listens for work and information-requests. @@ -16635,12 +16936,14 @@ should need to modify the default. The option is expanded before use. If the platform supports Linux-style abstract socket names, the result is used with a nul byte prefixed. -Otherwise, it should be a full path name and use a directory accessible +Otherwise, +it should be a full path name and use a directory accessible to Exim. -If the Exim command line uses a &%-oX%& option and does not use &%-oP%& +If this option is set as empty, +or the command line &%-oY%& option is used, or +the command line uses a &%-oX%& option and does not use &%-oP%&, then a notifier socket is not created. -.wen .option openssl_options main "string list" "+no_sslv2 +no_sslv3 +single_dh_use +no_ticket +no_renegotiation" @@ -16827,7 +17130,7 @@ not count as protocol errors (see &%smtp_max_synprot_errors%&). .option pipelining_connect_advertise_hosts main "host list&!!" * .cindex "pipelining" "early connection" .cindex "pipelining" PIPE_CONNECT -.cindex "ESMTP extensions" X_PIPE_CONNECT +.cindex "ESMTP extensions" PIPE_CONNECT If Exim is built with the SUPPORT_PIPE_CONNECT build option this option controls which hosts the facility is advertised to and from which pipeline early-connection (before MAIL) SMTP @@ -16836,7 +17139,7 @@ When used, the pipelining saves on roundtrip times. See also the &%hosts_pipe_connect%& smtp transport option. -Currently the option name &"X_PIPE_CONNECT"& is used. +The SMTP service extension keyword advertised is &"PIPE_CONNECT"&. .option prdr_enable main boolean false @@ -16917,6 +17220,12 @@ admin user unless &%prod_requires_admin%& is set false. See also &%queue_list_requires_admin%& and &%commandline_checks_require_admin%&. +.option proxy_protocol_timeout main time 3s +.cindex proxy "proxy protocol" +This option sets the timeout for proxy protocol negotiation. +For details see section &<>&. + + .option qualify_domain main string "see below" .cindex "domain" "for qualifying addresses" .cindex "address" "qualification" @@ -16952,6 +17261,15 @@ domains that do not match are processed. All other deliveries wait until the next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&. +.option queue_fast_ramp main boolean false +.cindex "queue runner" "two phase" +.cindex "queue" "double scanning" +If set to true, two-phase queue runs, initiated using &%-qq%& on the +command line, may start parallel delivery processes during their first +phase. This will be done when a threshold number of messages have been +routed for a single host. + + .option queue_list_requires_admin main boolean true .cindex "restricting access to features" .oindex "&%-bp%&" @@ -17163,7 +17481,7 @@ or if the message was submitted locally (not using TCP/IP), and the &%-bnq%& option was not set. -.option recipients_max main integer 0 +.option recipients_max main integer 50000 .cindex "limit" "number of recipients" .cindex "recipient" "maximum number" If this option is set greater than zero, it specifies the maximum number of @@ -17208,6 +17526,9 @@ manager, there is no way of controlling the total number of simultaneous deliveries if the configuration allows a delivery attempt as soon as a message is received. +See also the &%max_parallel%& generic transport option, +and the &%serialize_hosts%& smtp transport option. + .cindex "number of deliveries" .cindex "delivery" "maximum number of" If you want to control the total number of deliveries on the system, you @@ -17376,7 +17697,7 @@ live with. . searchable. NM changed this occurrence for bug 1197 to no longer allow . the option name to split. -.option "smtp_accept_max_per_connection" main integer 1000 &&& +.option "smtp_accept_max_per_connection" main integer&!! 1000 &&& smtp_accept_max_per_connection .cindex "SMTP" "limiting incoming message count" .cindex "limit" "messages per SMTP connection" @@ -17386,6 +17707,9 @@ results in the transfer of a message. After the limit is reached, a 421 response is given to subsequent MAIL commands. This limit is a safety precaution against a client that goes mad (incidents of this type have been seen). +The option is expanded after the HELO or EHLO is received +and may depend on values available at that time. +An empty or zero value after expansion removes the limit. .option smtp_accept_max_per_host main string&!! unset @@ -17493,6 +17817,14 @@ messages, it is also used as the default for HELO commands in callout verification if there is no remote transport from which to obtain a &%helo_data%& value. +.option smtp_backlog_monitor main integer 0 +.cindex "connection backlog" monitoring +If this option is set to greater than zero, and the backlog of available +TCP connections on a socket listening for SMTP is larger than it, a line +is logged giving the value and the socket address and port. +The value is retrived jsut before an accept call. +This facility is only available on Linux. + .option smtp_banner main string&!! "see below" .cindex "SMTP" "welcome banner" .cindex "banner for SMTP" @@ -17523,7 +17855,7 @@ is zero). If there isn't enough space, a temporary error code is returned. .option smtp_connect_backlog main integer 20 -.cindex "connection backlog" +.cindex "connection backlog" "set maximum" .cindex "SMTP" "connection backlog" .cindex "backlog of connections" This option specifies a maximum number of waiting SMTP connections. Exim passes @@ -17573,12 +17905,10 @@ example: smtp_etrn_command = /etc/etrn_command $domain \ $sender_host_address .endd -.new If the option is not set, the argument for the ETRN command must be a &'#'& followed by an address string. In this case an &'exim -R '& command is used; if the ETRN ACL has set up a named-queue then &'-MCG '& is appended. -.wen A new process is created to run the command, but Exim does not wait for it to complete. Consequently, its status cannot be checked. If the command cannot be @@ -17761,6 +18091,46 @@ See section &<>& for more details. This option is available when Exim is compiled with SPF support. See section &<>& for more details. +.option spf_smtp_comment_template main string&!! "Please%_see%_http://www.open-spf.org/Why" +This option is available when Exim is compiled with SPF support. It +allows the customisation of the SMTP comment that the SPF library +generates. You are strongly encouraged to link to your own explanative +site. The template must not contain spaces. If you need spaces in the +output, use the proper placeholder. If libspf2 can not parse the +template, it uses a built-in default broken link. The following placeholders +(along with Exim variables (but see below)) are allowed in the template: +.ilist +&*%_*&: A space. +.next +&*%{L}*&: Envelope sender's local part. +.next +&*%{S}*&: Envelope sender. +.next +&*%{O}*&: Envelope sender's domain. +.next +&*%{D}*&: Current(?) domain. +.next +&*%{I}*&: SMTP client Ip. +.next +&*%{C}*&: SMTP client pretty IP. +.next +&*%{T}*&: Epoch time (UTC). +.next +&*%{P}*&: SMTP client domain name. +.next +&*%{V}*&: IP version. +.next +&*%{H}*&: EHLO/HELO domain. +.next +&*%{R}*&: Receiving domain. +.endlist +The capitalized placeholders do proper URL encoding, if you use them +lowercased, no encoding takes place. This list was compiled from the +libspf2 sources. + +A note on using Exim variables: As +currently the SPF library is initialized before the SMTP EHLO phase, +the variables useful for expansion are quite limited. .option split_spool_directory main boolean false @@ -17912,6 +18282,7 @@ syslog. The value must be no longer than 32 characters. See chapter .option syslog_timestamp main boolean true .cindex "syslog" "timestamps" +.cindex timestamps syslog If &%syslog_timestamp%& is set false, the timestamps on Exim's log lines are omitted when these lines are sent to syslog. See chapter &<>& for details of Exim's logging. @@ -18044,7 +18415,18 @@ using the &%tls_certificate%& option. If TLS support for incoming connections is not required the &%tls_advertise_hosts%& option should be set empty. -.option tls_certificate main string list&!! unset +.option tls_alpn main "string list&!!" "smtp : esmtp" +.cindex TLS "Application Layer Protocol Names" +.cindex TLS ALPN +.cindex ALPN "set acceptable names for server" +If this option is set, +the TLS library supports ALPN, +and the client offers either more than +ALPN name or a name which does not match the list, +the TLS connection is declined. + + +.option tls_certificate main "string list&!!" unset .cindex "TLS" "server certificate; location of" .cindex "certificate" "server, location of" The value of this option is expanded, and must then be a list of absolute paths to @@ -18067,13 +18449,16 @@ when a list of more than one file is used, the &$tls_in_ourcert$& variable is unreliable. The macro "_TLS_BAD_MULTICERT_IN_OURCERT" will be defined for those versions. +.cindex SNI "selecting server certificate based on" If the option contains &$tls_out_sni$& and Exim is built against OpenSSL, then if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in &<>& will be re-expanded. -If this option is unset or empty a fresh self-signed certificate will be -generated for every connection. +If this option is unset or empty a self-signed certificate will be +used. +Under Linux this is generated at daemon startup; on other platforms it will be +generated fresh for every connection. .option tls_crl main string&!! unset .cindex "TLS" "server certificate revocation list" @@ -18116,12 +18501,7 @@ larger prime than requested. The value of this option is expanded and indicates the source of DH parameters to be used by Exim. -This option is ignored for GnuTLS version 3.6.0 and later. -The library manages parameter negotiation internally. - -&*Note: The Exim Maintainers strongly recommend, -for other TLS library versions, -using a filename with site-generated +&*Note: The Exim Maintainers strongly recommend using a filename with site-generated local DH parameters*&, which has been supported across all versions of Exim. The other specific constants available are a fallback so that even when "unconfigured", Exim can offer Perfect Forward Secrecy in older ciphersuites in TLS. @@ -18172,8 +18552,17 @@ of the later IKE values, which led into RFC7919 providing new fixed constants (the "ffdhe" identifiers). At this point, all of the "ike" values should be considered obsolete; -they're still in Exim to avoid breaking unusual configurations, but are +they are still in Exim to avoid breaking unusual configurations, but are candidates for removal the next time we have backwards-incompatible changes. +.new +Two of them in particular (&`ike1`& and &`ike22`&) are called out by RFC 8247 +as MUST NOT use for IPSEC, and two more (&`ike23`& and &`ike24`&) as +SHOULD NOT. +Because of this, Exim regards them as deprecated; if either of the first pair +are used, warnings will be logged in the paniclog, and if any are used then +warnings will be logged in the mainlog. +All four will be removed in a future Exim release. +.wen The TLS protocol does not negotiate an acceptable size for this; clients tend to hard-drop connections if what is offered by the server is unacceptable, @@ -18250,7 +18639,7 @@ further details, see section &<>&. -.option tls_privatekey main string list&!! unset +.option tls_privatekey main "string list&!!" unset .cindex "TLS" "server private key; location of" The value of this option is expanded, and must then be a list of absolute paths to files which contains the server's private keys. @@ -18284,6 +18673,12 @@ preference order of the available ciphers. Details are given in sections &<>& and &<>&. +.option tls_resumption_hosts main "host list&!!" unset +.cindex TLS resumption +This option controls which connections to offer the TLS resumption feature. +See &<>& for details. + + .option tls_try_verify_hosts main "host list&!!" unset .cindex "TLS" "client certificate verification" .cindex "certificate" "verification of client" @@ -18318,7 +18713,9 @@ than the public cert of individual clients. With both OpenSSL and GnuTLS, if the value is a file then the certificates are sent by Exim as a server to connecting clients, defining the list of accepted certificate authorities. Thus the values defined should be considered public data. To avoid this, -use the explicit directory version. +use the explicit directory version. (If your peer is Exim up to 4.85, +using GnuTLS, you may need to send the CAs (thus using the file +variant). Otherwise the peer doesn't send its certificate.) See &<>& for discussion of when this option might be re-expanded. @@ -18338,7 +18735,8 @@ either &%tls_verify_hosts%& or &%tls_try_verify_hosts%& is set and Any client that matches &%tls_verify_hosts%& is constrained by &%tls_verify_certificates%&. When the client initiates a TLS session, it must present one of the listed certificates. If it does not, the connection is -aborted. &*Warning*&: Including a host in &%tls_verify_hosts%& does not require +aborted. +&*Warning*&: Including a host in &%tls_verify_hosts%& does not require the host to use TLS. It can still send SMTP commands through unencrypted connections. Forcing a client to use TLS has to be done separately using an ACL to reject inappropriate commands when the connection is not encrypted. @@ -18480,11 +18878,9 @@ for constructing the warning message which is sent by Exim when a message has been in the queue for a specified amount of time, as specified by &%delay_warning%&. Details of the file's contents are given in chapter &<>&. -.new .cindex warn_message_file "tainted data" The option is expanded to give the file path, which must be absolute and untainted. -.wen See also &%bounce_message_file%&. @@ -18513,6 +18909,9 @@ which the preconditions are tested. The order of expansion of the options that provide data for a transport is: &%errors_to%&, &%headers_add%&, &%headers_remove%&, &%transport%&. +The name of a router is limited to be &drivernamemax; ASCII characters long; +prior to Exim 4.95 names would be silently truncated at this length, but now +it is enforced. .option address_data routers string&!! unset @@ -18639,7 +19038,11 @@ address (with affixes removed if relevant) is the name of an account on the local system. The check is done by calling the &[getpwnam()]& function rather than trying to read &_/etc/passwd_& directly. This means that other methods of holding password data (such as NIS) are supported. If the local part is a local -user, &$home$& is set from the password data, and can be tested in other +user, +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using router check_local_user option" +&$local_part_data$& is set to an untainted version of the local part and +&$home$& is set from the password data. The latter can be tested in other preconditions that are evaluated after this one (the order of evaluation is given in section &<>&). However, the value of &$home$& can be overridden by &%router_home_directory%&. If the local part is not a local user, @@ -18766,7 +19169,7 @@ transport option of the same name. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_request_domains%& will be done with -the dnssec request bit set. +the DNSSEC request bit set. This applies to all of the SRV, MX, AAAA, A lookup sequence. .option dnssec_require_domains routers "domain list&!!" unset @@ -18775,7 +19178,7 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_require_domains%& will be done with -the dnssec request bit set. Any returns not having the Authenticated Data bit +the DNSSEC request bit set. Any returns not having the Authenticated Data bit (AD bit) set will be ignored and logged as a host-lookup failure. This applies to all of the SRV, MX, AAAA, A lookup sequence. @@ -18786,7 +19189,8 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence. If this option is set, the router is skipped unless the current domain matches the list. If the match is achieved by means of a file lookup, the data that the lookup returned for the domain is placed in &$domain_data$& for use in string -expansions of the driver's private options. See section &<>& for +expansions of the driver's private options and in the transport. +See section &<>& for a list of the order in which preconditions are evaluated. @@ -18970,9 +19374,7 @@ colon-separated (by default, changeable in the usual way &<>& that is associated with any addresses that are accepted by the router. However, the option has no effect when an address is just being verified. Each list item is separately expanded, at transport time. -.new If an item ends in *, it will match any header with the given prefix. -.wen The way in which the text is used to remove header lines at transport time is described in section &<>&. Header lines are not actually removed until @@ -19085,11 +19487,9 @@ command for LMTP, SMTP, and BSMTP deliveries has the prefix removed by default. This behaviour can be overridden by setting &%rcpt_include_affixes%& true on the relevant transport. -.new .vindex &$local_part_prefix_v$& If wildcarding (above) was used then the part of the prefix matching the wildcard is available in &$local_part_prefix_v$&. -.wen When an address is being verified, &%local_part_prefix%& affects only the behaviour of the router. If the callout feature of verification is in use, this @@ -19153,12 +19553,13 @@ section &<>& for a discussion of local part lists. Because the string is expanded, it is possible to make it depend on the domain, for example: .code -local_parts = dbm;/usr/local/specials/$domain +local_parts = dbm;/usr/local/specials/$domain_data .endd .vindex "&$local_part_data$&" If the match is achieved by a lookup, the data that the lookup returned for the local part is placed in the variable &$local_part_data$& for use in -expansions of the router's private options. You might use this option, for +expansions of the router's private options or in the transport. +You might use this option, for example, if you have a large number of local virtual domains, and you want to send all postmaster mail to the same place without having to set up an alias in each virtual domain: @@ -19503,6 +19904,8 @@ Values containing a list-separator should have them doubled. When a router runs, the strings are evaluated in order, to create variables which are added to the set associated with the address. +This is done immediately after all the preconditions, before the +evaluation of the &%address_data%& option. The variable is set with the expansion of the value. The variables can be used by the router options (not including any preconditions) @@ -20924,7 +21327,6 @@ is not the case when the file contains syntactically valid items that happen to yield empty addresses, for example, items containing only RFC 2822 address comments. -.new .cindex "tainted data" "in filenames" .cindex redirect "tainted data" Tainted data may not be used for a filename. @@ -20935,7 +21337,6 @@ as they are provided by a potential attacker. In the examples above, &$local_part$& is used for looking up data held locally on the system, and not used directly (the second example derives &$home$& via the passsword file or database, using &$local_part$&). -.wen @@ -21162,11 +21563,9 @@ It must be given as .code list1: :include:/opt/lists/list1 .endd -.new .cindex "tainted data" "in filenames" .cindex redirect "tainted data" Tainted data may not be used for a filename. -.wen .next .cindex "address redirection" "to black hole" .cindex "delivery" "discard" @@ -21218,7 +21617,7 @@ The text is not included in the response to an EXPN command. In non-SMTP cases the text is included in the error message that Exim generates. .cindex "SMTP" "error codes" -By default, Exim sends a 451 SMTP code for a &':defer:'&, and 550 for +By default for verify, Exim sends a 451 SMTP code for a &':defer:'&, and 550 for &':fail:'&. However, if the message starts with three digits followed by a space, optionally followed by an extended code of the form &'n.n.n'&, also followed by a space, and the very first digit is the same as the default error @@ -22055,6 +22454,10 @@ and &$original_domain$& is never set. .scindex IIDgenoptra1 "generic options" "transport" .scindex IIDgenoptra2 "options" "generic; for transports" .scindex IIDgenoptra3 "transport" "generic options for" +The name of a transport is limited to be &drivernamemax; ASCII characters long; +prior to Exim 4.95 names would be silently truncated at this length, but now +it is enforced. + The following generic options apply to all transports: @@ -22124,6 +22527,12 @@ header, Exim has a configuration option (&%envelope_to_remove%&) which requests its removal from incoming messages, so that delivered messages can safely be resent to other recipients. +&*Note:*& If used on a transport handling multiple recipients +(the smtp transport unless &%rcpt_max%& is 1, the appendfile, pipe or lmtp +transport if &%batch_max%& is greater than 1) +then information about Bcc recipients will be leaked. +Doing so is generally not advised. + .option event_action transports string&!! unset .cindex events @@ -22175,9 +22584,7 @@ Each list item is separately expanded. If the result of the expansion is an empty string, or if the expansion is forced to fail, no action is taken. Other expansion failures are treated as errors and cause the delivery to be deferred. -.new If an item ends in *, it will match any header with the given prefix. -.wen Matching headers are omitted from the message as it is transported, as described in section &<>&. Header removal can also be specified by @@ -22356,7 +22763,7 @@ This defaults to the incoming sender address, but can be changed by setting .option return_path_add transports boolean false -.cindex "&'Return-path:'& header line" +.chindex Return-path: If this option is true, a &'Return-path:'& header is added to the message. Although the return path is normally available in the prefix line of BSD mailboxes, this is commonly not displayed by MUAs, and so the user does not @@ -22467,9 +22874,10 @@ an ideal name for this feature here, but as it was already implemented for the The expansion variables &$host$& and &$host_address$& are available when the transport is a remote one. They contain the name and IP address of the host to which the message is being sent. For example: +. used to have $sender_address in this cmdline, but it's tainted .code transport_filter = /some/directory/transport-filter.pl \ - $host $host_address $sender_address $pipe_addresses + $host $host_address $pipe_addresses .endd Two problems arise if you want to use more complicated expansion items to @@ -22732,14 +23140,17 @@ If &%file%& or &%directory%& is set for a delivery from a redirection, it is used to determine the file or directory name for the delivery. Normally, the contents of &$address_file$& are used in some way in the string expansion. .endlist -.new +If the &%create_file%& option is set to a path which +matches (see the option definition below for details) +a file or directory name +for the delivery, that name becomes de-tainted. + .cindex "tainted data" "in filenames" .cindex appendfile "tainted data" Tainted data may not be used for a file or directory name. This means that, for instance, &$local_part$& cannot be used directly as a component of a path. It can however be used as the key for a lookup which returns a path (or component). -.wen .cindex "Sieve filter" "configuring &(appendfile)&" @@ -22882,13 +23293,30 @@ delivery, it applies to the top level directory, not the maildir directories beneath. The option must be set to one of the words &"anywhere"&, &"inhome"&, or -&"belowhome"&. In the second and third cases, a home directory must have been -set for the transport. This option is not useful when an explicit filename is +&"belowhome"&, or to an absolute path. + +In the second and third cases, a home directory must have been +set for the transport, and the file or directory being created must +reside within it. +The "belowhome" checking additionally checks for attempts to use "../" +to evade the testing. +This option is not useful when an explicit filename is given for normal mailbox deliveries. It is intended for the case when filenames are generated from users' &_.forward_& files. These are usually handled by an &(appendfile)& transport called &%address_file%&. See also &%file_must_exist%&. +In the fourth case, +the value given for this option must be an absolute path for an +existing directory. +The value is used for checking instead of a home directory; +checking is done in "belowhome" mode. + +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using appendfile create_file option" +If "belowhome" checking is used, the file or directory path +becomes de-tainted. + .option directory appendfile string&!! unset This option is mutually exclusive with the &%file%& option, but one of &%file%& @@ -22901,6 +23329,9 @@ appended to a single mailbox file. A number of different formats are provided (see &%maildir_format%& and &%mailstore_format%&), and see section &<>& for further details of this form of delivery. +The result of expansion must not be tainted, unless the &%create_file%& option +specifies a path. + .option directory_file appendfile string&!! "see below" .cindex "base62" @@ -22933,6 +23364,9 @@ specifies a single file, to which the message is appended. One or more of &%use_fcntl_lock%&, &%use_flock_lock%&, or &%use_lockfile%& must be set with &%file%&. +The result of expansion must not be tainted, unless the &%create_file%& option +specifies a path. + .cindex "NFS" "lock file" .cindex "locking files" .cindex "lock files" @@ -24177,11 +24611,9 @@ directories are also controllable. See chapter &<>& for details of the local delivery environment and chapter &<>& for a discussion of local delivery batching. -.new .cindex "tainted data" "in pipe command" .cindex pipe "tainted data" Tainted data may not be used for the command name. -.wen .section "Concurrent delivery" "SECID140" @@ -24317,6 +24749,11 @@ This list is a compromise for maximum compatibility with other MTAs. Note that the &%environment%& option can be used to add additional variables to this environment. The environment for the &(pipe)& transport is not subject to the &%add_environment%& and &%keep_environment%& main config options. +.new +&*Note*&: Using enviroment variables loses track of tainted data. +Writers of &(pipe)& transport commands should be wary of data supplied +by potential attackers. +.wen .display &`DOMAIN `& the domain of the address &`HOME `& the home directory, if set @@ -24408,6 +24845,11 @@ the &%path%& option below). The command is split up into separate arguments by Exim, and each argument is separately expanded, as described in section &<>& above. +.new +.cindex "tainted data" +No part of the resulting command may be tainted. +.wen + .option environment pipe string&!! unset .cindex "&(pipe)& transport" "environment for command" @@ -24723,12 +25165,15 @@ use a shell to run pipe commands. .cindex "Cyrus" The next example shows a transport and a router for a system where local deliveries are handled by the Cyrus IMAP server. +. Used to have R: local_part_suffix = .* + T: -m $local_part_suffix_v +. but that suffix is tainted so cannot be used in a command arg +. Really, you'd want to use a lookup for acceptable suffixes to do real detainting .code # transport local_delivery_cyrus: driver = pipe command = /usr/cyrus/bin/deliver \ - -m ${substr_1:$local_part_suffix} -- $local_part + -- $local_part_data user = cyrus group = mail return_output @@ -24740,7 +25185,6 @@ local_delivery_cyrus: local_user_cyrus: driver = accept check_local_user - local_part_suffix = .* transport = local_delivery_cyrus .endd Note the unsetting of &%message_prefix%& and &%message_suffix%&, and the use of @@ -24888,12 +25332,14 @@ authenticated as a client. .option command_timeout smtp time 5m +.cindex timeout "smtp transport command" This sets a timeout for receiving a response to an SMTP command that has been sent out. It is also used when waiting for the initial banner line from the remote host. Its value must not be zero. .option connect_timeout smtp time 5m +.cindex timeout "smtp transport connect" This sets a timeout for the &[connect()]& function, which sets up a TCP/IP call to a remote host. A setting of zero allows the system timeout (typically several minutes) to act. To have any effect, the value of this option must be @@ -24929,6 +25375,7 @@ be treated as unset and &%tls_require_ciphers%& will be used instead. .option data_timeout smtp time 5m +.cindex timeout "for transmitted SMTP data blocks" This sets a timeout for the transmission of each block in the data portion of the message. As a result, the overall timeout for a message depends on the size of the message. Its value must not be zero. See also &%final_timeout%&. @@ -24936,7 +25383,7 @@ of the message. Its value must not be zero. See also &%final_timeout%&. .option dkim_canon smtp string&!! unset DKIM signing option. For details see section &<>&. -.option dkim_domain smtp string list&!! unset +.option dkim_domain smtp "string list&!!" unset DKIM signing option. For details see section &<>&. .option dkim_hash smtp string&!! sha256 DKIM signing option. For details see section &<>&. @@ -24999,7 +25446,7 @@ details. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_request_domains%& will be done with -the dnssec request bit set. Setting this transport option is only useful if the +the DNSSEC request bit set. Setting this transport option is only useful if the transport overrides or sets the host names. See the &%dnssec_request_domains%& router option. @@ -25011,7 +25458,7 @@ router option. .cindex "security" "MX lookup" .cindex "DNS" "DNSSEC" DNS lookups for domains matching &%dnssec_require_domains%& will be done with -the dnssec request bit set. Setting this transport option is only +the DNSSEC request bit set. Setting this transport option is only useful if the transport overrides or sets the host names. See the &%dnssec_require_domains%& router option. @@ -25067,6 +25514,7 @@ fails"& facility. .option final_timeout smtp time 10m +.cindex timeout "for transmitted SMTP data accept" This is the timeout that applies while waiting for the response to the final line containing just &"."& that terminates a message. Its value must not be zero. @@ -25102,12 +25550,45 @@ servers or different local IP addresses. For example, if you want the string that is used for &%helo_data%& to be obtained by a DNS lookup of the outgoing interface address, you could use this: .code -helo_data = ${lookup dnsdb{ptr=$sending_ip_address}{$value}\ +helo_data = ${lookup dnsdb{ptr=$sending_ip_address} \ + {${listextract{1}{<\n $value}}} \ {$primary_hostname}} .endd The use of &%helo_data%& applies both to sending messages and when doing callouts. +.new +.option host_name_extract smtp "string list&!!" "see below" +.cindex "load balancer" "hosts behind" +.cindex TLS resumption +Some mail-accepting sites +(notably Microsoft) +operate many servers behind a network load-balancer. When this is done, +with separated TLS session caches, TLS session resuption becomes problematic. +It will only succeed when the same server happens to be selected by the +load-balancer, matching the session stored in the client's cache. + +Exim can pull out a server name, if there is one, from the response to the +client's SMTP EHLO command. +The default value of this option: +.code + ${if and { {match {$host} {.outlook.com\$}} \ + {match {$item} {\N^250-([\w.]+)\s\N}} \ + } {$1}} +.endd +suffices for one known case. +During the expansion of this option the &$item$& variable will have the +server's EHLO response. +The result of the option expansion is included in the key used to store and +retrieve the TLS session, for session resumption. + +Operators of high-load sites may wish to evaluate their logs for indications +of other destination sites operating load-balancers, and develop a suitable +expression for this option. +The smtp:ehlo event and the &$tls_out_resumption$& variable +will be useful for such work. +.wen + .option hosts smtp "string list&!!" unset Hosts are associated with an address by a router such as &(dnslookup)&, which finds the hosts by looking up the address domain in the DNS, or by @@ -25175,7 +25656,10 @@ so combines well with TCP Fast Open. See also the &%pipelining_connect_advertise_hosts%& main option. Note: -When the facility is used, the transport &%helo_data%& option +.new +When the facility is used, if the transport &%interface%& option is unset +the &%helo_data%& option +.wen will be expanded before the &$sending_ip_address$& variable is filled in. A check is made for the use of that variable, without the @@ -25286,16 +25770,33 @@ Exim will request a Certificate Status on a TLS session for any host that matches this list. &%tls_verify_certificates%& should also be set for the transport. +.option hosts_require_alpn smtp "host list&!!" unset +.cindex ALPN "require negotiation in client" +.cindex TLS ALPN +.cindex TLS "Application Layer Protocol Names" +If the TLS library supports ALPN +then a successful negotiation of ALPN will be required for any host +matching the list, for TLS to be used. +See also the &%tls_alpn%& option. + +&*Note*&: prevention of fallback to in-clear connection is not +managed by this option; see &%hosts_require_tls%&. + .option hosts_require_dane smtp "host list&!!" unset .cindex DANE "transport options" .cindex DANE "requiring for certain servers" If built with DANE support, Exim will require that a DNSSEC-validated TLSA record is present for any host matching the list, -and that a DANE-verified TLS connection is made. See -the &%dnssec_request_domains%& router and transport options. +and that a DANE-verified TLS connection is made. There will be no fallback to in-clear communication. +See the &%dnssec_request_domains%& router and transport options. See section &<>&. +.option hosts_require_helo smtp "host list&!!" * +.cindex "HELO/EHLO" requiring +Exim will require an accepted HELO or EHLO command from a host matching +this list, before accepting a MAIL command. + .option hosts_require_ocsp smtp "host list&!!" unset .cindex "TLS" "requiring for certain servers" Exim will request, and check for a valid Certificate Status being given, on a @@ -25313,9 +25814,10 @@ incoming messages, use an appropriate ACL. .cindex "authentication" "optional in client" This option provides a list of servers to which, provided they announce authentication support, Exim will attempt to authenticate as a client when it -connects. If authentication fails, Exim will try to transfer the message -unauthenticated. See also &%hosts_require_auth%&, and chapter -&<>& for details of authentication. +connects. If authentication fails +and &%hosts_require_auth%& permits, +Exim will try to transfer the message unauthenticated. +See also chapter &<>& for details of authentication. .option hosts_try_chunking smtp "host list&!!" * .cindex CHUNKING "enabling, in client" @@ -25323,19 +25825,18 @@ unauthenticated. See also &%hosts_require_auth%&, and chapter .cindex "RFC 3030" "CHUNKING" This option provides a list of servers to which, provided they announce CHUNKING support, Exim will attempt to use BDAT commands rather than DATA. -.new Unless DKIM signing is being done, -.wen BDAT will not be used in conjunction with a transport filter. .option hosts_try_dane smtp "host list&!!" * .cindex DANE "transport options" .cindex DANE "attempting for certain servers" -If built with DANE support, Exim will require that a DNSSEC-validated -TLSA record is present for any host matching the list, -and that a DANE-verified TLS connection is made. See -the &%dnssec_request_domains%& router and transport options. -There will be no fallback to in-clear communication. +If built with DANE support, Exim will look up a +TLSA record for any host matching the list, +If one is found and that lookup was DNSSEC-validated, +then Exim requires that a DANE-verified TLS connection is made for that host; +there will be no fallback to in-clear communication. +See the &%dnssec_request_domains%& router and transport options. See section &<>&. .option hosts_try_fastopen smtp "host list&!!" * @@ -25420,7 +25921,19 @@ has advertised support for IGNOREQUOTA in its response to the LHLO command. This option limits the number of RCPT commands that are sent in a single SMTP message transaction. Each set of addresses is treated independently, and so can cause parallel connections to the same host if &%remote_max_parallel%& -permits this. +permits this. A value setting of zero disables the limit. + + +.option message_linelength_limit smtp integer 998 +.cindex "line length" limit +This option sets the maximum line length, in bytes, that the transport +will send. Any messages with lines exceeding the given value +will fail and a failure-DSN ("bounce") message will if possible be returned +to the sender. +The default value is that defined by the SMTP standards. + +It is generally wise to also check in the data ACL so that messages +received via SMTP can be refused without producing a bounce. .option multi_domain smtp boolean&!! true @@ -25436,6 +25949,10 @@ It is expanded per-address and can depend on any of &$address_data$&, &$domain_data$&, &$local_part_data$&, &$host$&, &$host_address$& and &$host_port$&. +If the connection is DANE-enabled then this option is ignored; +only messages having the domain used for the DANE TLSA lookup are +sent on the connection. + .option port smtp string&!! "see below" .cindex "port" "sending TCP/IP" .cindex "TCP/IP" "setting outgoing port" @@ -25473,7 +25990,7 @@ If this option is set to &"smtps"&, the default value for the &%port%& option changes to &"smtps"&, and the transport initiates TLS immediately after connecting, as an outbound SSL-on-connect, instead of using STARTTLS to upgrade. The Internet standards bodies used to strongly discourage use of this mode, -but as of RFC 8314 it is perferred over STARTTLS for message submission +but as of RFC 8314 it is preferred over STARTTLS for message submission (as distinct from MTA-MTA communication). @@ -25540,6 +26057,19 @@ This option enables use of SOCKS proxies for connections made by the transport. For details see section &<>&. +.option tls_alpn smtp string&!! unset +.cindex TLS "Application Layer Protocol Names" +.cindex TLS ALPN +.cindex ALPN "set name in client" +If this option is set +and the TLS library supports ALPN, +the value given is used. + +As of writing no value has been standardised for email use. +The authors suggest using &"smtp"&. + + + .option tls_certificate smtp string&!! unset .cindex "TLS" "client certificate, location of" .cindex "certificate" "client, location of" @@ -25604,11 +26134,21 @@ is used in different ways by OpenSSL and GnuTLS (see sections ciphers is a preference order. +.option tls_resumption_hosts smtp "host list&!!" unset +.cindex TLS resumption +This option controls which connections to use the TLS resumption feature. +See &<>& for details. + + .option tls_sni smtp string&!! unset .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI "setting in client" .vindex "&$tls_sni$&" -If this option is set then it sets the $tls_out_sni variable and causes any +If this option is set +and the connection is not DANE-validated +then it sets the $tls_out_sni variable and causes any TLS session to pass this value as the Server Name Indication extension to the remote side, which can be used by the remote side to select an appropriate certificate and private key for the session. @@ -25702,6 +26242,10 @@ certificate verification must succeed. The &%tls_verify_certificates%& option must also be set. If both this option and &%tls_try_verify_hosts%& are unset operation is as if this option selected all hosts. +&*Warning*&: Including a host in &%tls_verify_hosts%& does not require +that connections use TLS. +Fallback to in-clear communication will be done unless restricted by +the &%hosts_require_tls%& option. .option utf8_downconvert smtp integer&!! -1 .cindex utf8 "address downconversion" @@ -26820,6 +27364,10 @@ permitted to use it as a relay. SMTP authentication is not of relevance to the transfer of mail between servers that have no managerial connection with each other. +The name of an authenticator is limited to be &drivernamemax; ASCII characters long; +prior to Exim 4.95 names would be silently truncated at this length, but now +it is enforced. + .cindex "AUTH" "description of" .cindex "ESMTP extensions" AUTH Very briefly, the way SMTP authentication works is as follows: @@ -27112,7 +27660,7 @@ conditions: .ilist The client host must match &%auth_advertise_hosts%& (default *). .next -It the &%server_advertise_condition%& option is set, its expansion must not +If the &%server_advertise_condition%& option is set, its expansion must not yield the empty string, &"0"&, &"no"&, or &"false"&. .endlist @@ -27220,7 +27768,7 @@ encode '\0user@domain.com\0pas$$word' .endd gives an incorrect answer because of the unescaped &"@"& and &"$"& characters. -If you have the &%mimencode%& command installed, another way to do produce +If you have the &%mimencode%& command installed, another way to produce base64-encoded strings is to run the command .code echo -e -n `\0user\0password' | mimencode @@ -27562,7 +28110,12 @@ fixed_plain: client_send = ^username^mysecret .endd The lack of colons means that the entire text is sent with the AUTH -command, with the circumflex characters converted to NULs. A similar example +command, with the circumflex characters converted to NULs. +Note that due to the ambiguity of parsing three consectutive circumflex characters +there is no way to provide a password having a leading circumflex. + + +A similar example that uses the LOGIN mechanism is: .code fixed_login: @@ -27836,8 +28389,7 @@ connection, a client certificate has been verified, the &"valid-client-cert"& option is passed. When authentication succeeds, the identity of the user who authenticated is placed in &$auth1$&. -.new -The Dovecot configuration to match the above wil look +The Dovecot configuration to match the above will look something like: .code conf.d/10-master.conf :- @@ -27856,7 +28408,6 @@ conf.d/10-auth.conf :- auth_mechanisms = plain login ntlm .endd -.wen .ecindex IIDdcotauth1 .ecindex IIDdcotauth2 @@ -27883,12 +28434,15 @@ scale to handle future authentication mechanisms, so no guarantee can be made that any particular new authentication mechanism will be supported without code changes in Exim. -.new The library is expected to add support in an upcoming realease for the SCRAM-SHA-256 method. The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined when this happens. +To see the list of mechanisms supported by the library run Exim with "auth" debug +enabled and look for a line containing "GNU SASL supports". +Note however that some may not have been tested from Exim. + .option client_authz gsasl string&!! unset This option can be used to supply an &'authorization id'& @@ -27907,25 +28461,41 @@ the password to be used, in clear. .option client_username gsasl string&!! unset This option is exapanded before use, and should result in the account name to be used. -.wen -.new + .option client_spassword gsasl string&!! unset +This option is only supported for library versions 1.9.1 and greater. +The macro _HAVE_AUTH_GSASL_SCRAM_S_KEY will be defined when this is so. + If a SCRAM mechanism is being used and this option is set +and correctly sized it is used in preference to &%client_password%&. The value after expansion should be a 40 (for SHA-1) or 64 (for SHA-256) character string with the PBKDF2-prepared password, hex-encoded. + Note that this value will depend on the salt and iteration-count supplied by the server. -.wen +The option is expanded before use. +During the expansion &$auth1$& is set with the client username, +&$auth2$& with the iteration count, and +&$auth3$& with the salt. +The intent of this option +is to support clients that can cache thes salted password +to save on recalculation costs. +The cache lookup should return an unusable value +(eg. an empty string) +if the salt or iteration count has changed +If the authentication succeeds then the above variables are set, +.vindex "&$auth4$&" +plus the calculated salted password value value in &$auth4$&, +during the expansion of the &%client_set_id%& option. +A side-effect of this expansion can be used to prime the cache. -.option server_channelbinding gsasl boolean false -Do not set this true and rely on the properties -without consulting a cryptographic engineer. +.option server_channelbinding gsasl boolean false Some authentication mechanisms are able to use external context at both ends of the session to bind the authentication to that context, and fail the authentication process if that context differs. Specifically, some TLS @@ -27936,20 +28506,23 @@ This should have meant that certificate identity and verification becomes a non-issue, as a man-in-the-middle attack will cause the correct client and server to see different identifiers and authentication will fail. -.new This is only usable by mechanisms which support "channel binding"; at time of writing, that's the SCRAM family. When using this feature the "-PLUS" variants of the method names need to be used. -.wen This defaults off to ensure smooth upgrade across Exim releases, in case this option causes some clients to start failing. Some future release of Exim might have switched the default to be true. -However, Channel Binding in TLS has proven to be vulnerable in current versions. -Do not plan to rely upon this feature for security, ever, without consulting -with a subject matter expert (a cryptographic engineer). +. However, Channel Binding in TLS has proven to be vulnerable in current versions. +. Do not plan to rely upon this feature for security, ever, without consulting +. with a subject matter expert (a cryptographic engineer). + +This option was deprecated in previous releases due to doubts over +the "Triple Handshake" vulnerability. +Exim takes suitable precausions (requiring Extended Master Secret if TLS +Session Resumption was used) for safety. .option server_hostname gsasl string&!! "see below" @@ -27997,7 +28570,6 @@ Some mechanisms will use this data. .option server_scram_iter gsasl string&!! 4096 This option provides data for the SCRAM family of mechanisms. -.new The &$auth1$&, &$auth2$& and &$auth3$& variables are available when this option is expanded. @@ -28008,21 +28580,17 @@ a compute cost factor imposed on the client either the iteration count or the salt). A minimum value of 4096 is required by the standards for all current SCRAM mechanism variants. -.wen .option server_scram_salt gsasl string&!! unset This option provides data for the SCRAM family of mechanisms. -.new The &$auth1$&, &$auth2$& and &$auth3$& variables are available when this option is expanded. The value should be a base64-encoded string, of random data typically 4-to-16 bytes long. If unset or empty after expansion the library will provides a value for the protocol conversation. -.wen -.new .option server_key gsasl string&!! unset .option server_skey gsasl string&!! unset These options can be used for the SCRAM family of mechanisms @@ -28048,7 +28616,6 @@ If unset or not of the right length, &%server_password%& will be used. The libgsasl library release includes a utility &'gsasl'& which can be used to generate these values. -.wen .option server_service gsasl string &`smtp`& @@ -28275,7 +28842,7 @@ and for clients to only attempt, this authentication method on a secure (eg. under TLS) connection. One possible use, compatible with the -K-9 Mail Andoid client (&url(https://k9mail.github.io/)), +K-9 Mail Android client (&url(https://k9mail.github.io/)), is for using X509 client certificates. It thus overlaps in function with the TLS authenticator @@ -28628,6 +29195,10 @@ Some other recently added features may only be available in one or the other. This should be documented with the feature. If the documentation does not explicitly state that the feature is infeasible in the other TLS implementation, then patches are welcome. +.next +The output from "exim -bV" will show which (if any) support was included +in the build. +Also, the macro "_HAVE_OPENSSL" or "_HAVE_GNUTLS" will be defined. .endlist @@ -29101,6 +29672,59 @@ There is no current way to staple a proof for a client certificate. .endd +.section "Caching of static server configuration items" "SECTserverTLScache" +.cindex certificate caching +.cindex privatekey caching +.cindex crl caching +.cindex ocsp caching +.cindex ciphers caching +.cindex "CA bundle" caching +.cindex "certificate authorities" caching +.cindex tls_certificate caching +.cindex tls_privatekey caching +.cindex tls_crl caching +.cindex tls_ocsp_file caching +.cindex tls_require_ciphers caching +.cindex tls_verify_certificate caching +.cindex caching certificate +.cindex caching privatekey +.cindex caching crl +.cindex caching ocsp +.cindex caching ciphers +.cindex caching "certificate authorities +If any of the main configuration options &%tls_certificate%&, &%tls_privatekey%&, +&%tls_crl%& and &%tls_ocsp_file%& have values with no +expandable elements, +then the associated information is loaded at daemon startup. +It is made available +to child processes forked for handling received SMTP connections. + +This caching is currently only supported under Linux and FreeBSD. + +If caching is not possible, for example if an item has to be dependent +on the peer host so contains a &$sender_host_name$& expansion, the load +of the associated information is done at the startup of the TLS connection. + +The cache is invalidated and reloaded after any changes to the directories +containing files specified by these options. + +The information specified by the main option &%tls_verify_certificates%& +is similarly cached so long as it specifies files explicitly +or (under GnuTLS) is the string &"system,cache"&. +The latter case is not automatically invalidated; +it is the operator's responsibility to arrange for a daemon restart +any time the system certificate authority bundle is updated. +A HUP signal is sufficient for this. +The value &"system"& results in no caching under GnuTLS. + +The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system" +is acceptable in configurations for the Exim executavble. + +Caching of the system Certificate Authorities bundle can +save siginificant time and processing on every TLS connection +accepted by Exim. + + .section "Configuring an Exim client to use TLS" "SECTclientTLS" @@ -29141,7 +29765,10 @@ unencrypted. The &%tls_certificate%& and &%tls_privatekey%& options of the &(smtp)& transport provide the client with a certificate, which is passed to the server -if it requests it. If the server is Exim, it will request a certificate only if +if it requests it. +This is an optional thing for TLS connections, although either end +may insist on it. +If the server is Exim, it will request a certificate only if &%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client. &*Note*&: Do not use a certificate which has the OCSP-must-staple extension, @@ -29166,8 +29793,12 @@ certificate verification to the listed servers. Verification either must or need not succeed respectively. The &%tls_verify_cert_hostnames%& option lists hosts for which additional -checks are made: that the host name (the one in the DNS A record) -is valid for the certificate. +name checks are made on the server certificate. +The match against this list is, as per other Exim usage, the +IP for the host. That is most closely associated with the +name on the DNS A (or AAAA) record for the host. +However, the name that needs to be in the certificate +is the one at the head of any CNAME chain leading to the A record. The option defaults to always checking. The &(smtp)& transport has two OCSP-related options: @@ -29215,8 +29846,64 @@ outgoing connection. +.section "Caching of static client configuration items" "SECTclientTLScache" +.cindex certificate caching +.cindex privatekey caching +.cindex crl caching +.cindex ciphers caching +.cindex "CA bundle" caching +.cindex "certificate authorities" caching +.cindex tls_certificate caching +.cindex tls_privatekey caching +.cindex tls_crl caching +.cindex tls_require_ciphers caching +.cindex tls_verify_certificate caching +.cindex caching certificate +.cindex caching privatekey +.cindex caching crl +.cindex caching ciphers +.cindex caching "certificate authorities +If any of the transport configuration options &%tls_certificate%&, &%tls_privatekey%& +and &%tls_crl%& have values with no +expandable elements, +then the associated information is loaded per smtp transport +at daemon startup, at the start of a queue run, or on a +command-line specified message delivery. +It is made available +to child processes forked for handling making SMTP connections. + +This caching is currently only supported under Linux. + +If caching is not possible, the load +of the associated information is done at the startup of the TLS connection. + +The cache is invalidated in the daemon +and reloaded after any changes to the directories +containing files specified by these options. + +The information specified by the main option &%tls_verify_certificates%& +is similarly cached so long as it specifies files explicitly +or (under GnuTLS) is the string &"system,cache"&. +The latter case is not automatically invaludated; +it is the operator's responsibility to arrange for a daemon restart +any time the system certificate authority bundle is updated. +A HUP signal is sufficient for this. +The value &"system"& results in no caching under GnuTLS. + +The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system" +is acceptable in configurations for the Exim executavble. + +Caching of the system Certificate Authorities bundle can +save siginificant time and processing on every TLS connection +initiated by Exim. + + + + .section "Use of TLS Server Name Indication" "SECTtlssni" .cindex "TLS" "Server Name Indication" +.cindex "TLS" SNI +.cindex SNI .vindex "&$tls_in_sni$&" .oindex "&%tls_in_sni%&" With TLS1.0 or above, there is an extension mechanism by which extra @@ -29248,6 +29935,11 @@ nothing more to it. Choosing a sensible value not derived insecurely is the only point of caution. The &$tls_out_sni$& variable will be set to this string for the lifetime of the client connection (including during authentication). +.new +If DANE validated the connection attempt then the value of the &%tls_sni%& option +is forced to the name of the destination host, after any MX- or CNAME-following. +.wen + Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string received from a client. It can be logged with the &%log_selector%& item &`+tls_sni`&. @@ -29288,6 +29980,33 @@ When Exim is built against GnuTLS, SNI support is available as of GnuTLS 0.5.10. (Its presence predates the current API which Exim uses, so if Exim built, then you have SNI support). +.cindex TLS ALPN +.cindex ALPN "general information" +.cindex TLS "Application Layer Protocol Names" +There is a TLS feature related to SNI +called Application Layer Protocol Name (ALPN). +This is intended to declare, or select, what protocol layer will be using a TLS +connection. +The client for the connection proposes a set of protocol names, and +the server responds with a selected one. +It is not, as of 2021, commonly used for SMTP connections. +However, to guard against misirected or malicious use of web clients +(which often do use ALPN) against MTA ports, Exim by default check that +there is no incompatible ALPN specified by a client for a TLS connection. +If there is, the connection is rejected. + +As a client Exim does not supply ALPN by default. +The behaviour of both client and server can be configured using the options +&%tls_alpn%& and &%hosts_require_alpn%&. +There are no variables providing observability. +Some feature-specific logging may appear on denied connections, but this +depends on the behavious of the peer +(not all peers can send a feature-specific TLS Alert). + +This feature is available when Exim is built with +OpenSSL 1.1.0 or later or GnuTLS 3.2.0 or later; +the macro _HAVE_TLS_ALPN will be defined when this is so. + .section "Multiple messages on the same encrypted TCP/IP connection" &&& @@ -29361,7 +30080,7 @@ Ivan is the author of the popular TLS testing tools at .section "Certificate chains" "SECID186" -The file named by &%tls_certificate%& may contain more than one +A file named by &%tls_certificate%& may contain more than one certificate. This is useful in the case where the certificate that is being sent is validated by an intermediate certificate which the other end does not have. Multiple certificates must be in the correct order in the file. @@ -29434,6 +30153,98 @@ Open-source PKI book, available online at .ecindex IIDencsmtp2 +.section "TLS Resumption" "SECTresumption" +.cindex TLS resumption +TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined +in RFC 5077 for 1.2). The support for this requires GnuTLS 3.6.3 or OpenSSL 1.1.1 +(or later). + +Session resumption (this is the "stateless" variant) involves the server sending +a "session ticket" to the client on one connection, which can be stored by the +client and used for a later session. The ticket contains sufficient state for +the server to reconstruct the TLS session, avoiding some expensive crypto +calculation and (on TLS1.2) one full packet roundtrip time. + +.ilist +Operational cost/benefit: + + The extra data being transmitted costs a minor amount, and the client has + extra costs in storing and retrieving the data. + + In the Exim/Gnutls implementation the extra cost on an initial connection + which is TLS1.2 over a loopback path is about 6ms on 2017-laptop class hardware. + The saved cost on a subsequent connection is about 4ms; three or more + connections become a net win. On longer network paths, two or more + connections will have an average lower startup time thanks to the one + saved packet roundtrip. TLS1.3 will save the crypto cpu costs but not any + packet roundtrips. + +.cindex "hints database" tls + Since a new hints DB is used on the TLS client, + the hints DB maintenance should be updated to additionally handle "tls". + +.next +Security aspects: + + The session ticket is encrypted, but is obviously an additional security + vulnarability surface. An attacker able to decrypt it would have access + all connections using the resumed session. + The session ticket encryption key is not committed to storage by the server + and is rotated regularly (OpenSSL: 1hr, and one previous key is used for + overlap; GnuTLS 6hr but does not specify any overlap). + Tickets have limited lifetime (2hr, and new ones issued after 1hr under + OpenSSL. GnuTLS 2hr, appears to not do overlap). + + There is a question-mark over the security of the Diffie-Helman parameters + used for session negotiation. + +.next +Observability: + + The &%log_selector%& "tls_resumption" appends an asterisk to the tls_cipher "X=" + element. + + The variables &$tls_in_resumption$& and &$tls_out_resumption$& + have bits 0-4 indicating respectively + support built, client requested ticket, client offered session, + server issued ticket, resume used. A suitable decode list is provided + in the builtin macro _RESUME_DECODE for in &%listextract%& expansions. + +.next +Control: + +The &%tls_resumption_hosts%& main option specifies a hostlist for which +exim, operating as a server, will offer resumption to clients. +Current best practice is to not offer the feature to MUA connection. +Commonly this can be done like this: +.code +tls_resumption_hosts = ${if inlist {$received_port}{587:465} {:}{*}} +.endd +If the peer host matches the list after expansion then resumption +is offered and/or accepted. + +The &%tls_resumption_hosts%& smtp transport option performs the +equivalent function for operation as a client. +If the peer host matches the list after expansion then resumption +is attempted (if a stored session is available) or the information +stored (if supplied by the peer). + + +.next +Issues: + + In a resumed session: +.ilist + The variables &$tls_{in,out}_cipher$& will have values different + to the original (under GnuTLS). +.next + The variables &$tls_{in,out}_ocsp$& will be "not requested" or "no response", + and the &%hosts_require_ocsp%& smtp trasnport option will fail. +. XXX need to do something with that hosts_require_ocsp +.endlist + +.endlist + .section DANE "SECDANE" .cindex DANE @@ -29451,7 +30262,7 @@ by (a) is thought to be smaller than that of the set of root CAs. It also allows the server to declare (implicitly) that connections to it should use TLS. An MITM could simply fail to pass on a server's STARTTLS. -DANE scales better than having to maintain (and side-channel communicate) copies of server certificates +DANE scales better than having to maintain (and communicate via side-channel) copies of server certificates for every possible target server. It also scales (slightly) better than having to maintain on an SMTP client a copy of the standard CAs bundle. It also means not having to pay a CA for certificates. @@ -29575,7 +30386,7 @@ the &%dnssec_request_domains%& router or transport option. DANE will only be usable if the target host has DNSSEC-secured MX, A and TLSA records. -A TLSA lookup will be done if either of the above options match and the host-lookup succeeded using dnssec. +A TLSA lookup will be done if either of the above options match and the host-lookup succeeded using DNSSEC. If a TLSA lookup is done and succeeds, a DANE-verified TLS connection will be required for the host. If it does not, the host will not be used; there is no fallback to non-DANE or non-TLS. @@ -29596,6 +30407,7 @@ If DANE is requested and useable (see above) the following transport options are tls_verify_certificates tls_crl tls_verify_cert_hostnames + tls_sni .endd If DANE is not usable, whether requested or not, and CA-anchored @@ -29781,6 +30593,11 @@ accepted by an &%accept%& verb that has a &%message%& modifier, the contents of the message override the banner message that is otherwise specified by the &%smtp_banner%& option. +.new +For tls-on-connect connections, the ACL is run after the TLS connection +is accepted (however, &%host_reject_connection%& is tested before). +.wen + .section "The EHLO/HELO ACL" "SECID192" .cindex "EHLO" "ACL for" @@ -30709,8 +31526,9 @@ anyway. If the message contains newlines, this gives rise to a multi-line SMTP response. .vindex "&$acl_verify_message$&" -For ACLs that are called by an &%acl =%& ACL condition, the message is -stored in &$acl_verify_message$&, from which the calling ACL may use it. +While the text is being expanded, the &$acl_verify_message$& variable +contains any message previously set. +Afterwards, &$acl_verify_message$& is cleared. If &%message%& is used on a statement that verifies an address, the message specified overrides any message that is generated by the verification process. @@ -30897,12 +31715,43 @@ sender when the destination system is doing content-scan based rejection. This control turns on debug logging, almost as though Exim had been invoked with &`-d`&, with the output going to a new logfile in the usual logs directory, by default called &'debuglog'&. -The filename can be adjusted with the &'tag'& option, which -may access any variables already defined. The logging may be adjusted with -the &'opts'& option, which takes the same values as the &`-d`& command-line -option. -Logging started this way may be stopped, and the file removed, -with the &'kill'& option. + +.new +Options are a slash-separated list. +If an option takes an argument, the option name and argument are separated by +an equals character. +Several options are supported: +.wen +.display +tag=<&'suffix'&> The filename can be adjusted with thise option. + The argument, which may access any variables already defined, + is appended to the default name. + +opts=<&'debug&~options'&> The argument specififes what is to be logged, + using the same values as the &`-d`& command-line option. + +stop Logging started with this control may be + stopped by using this option. + +kill Logging started with this control may be + stopped by using this option. + Additionally the debug file will be removed, + providing one means for speculative debug tracing. + +pretrigger=<&'size'&> This option specifies a memory buffuer to be used + for pre-trigger debug capture. + Debug lines are recorded in the buffer until + and if) a trigger occurs; at which time they are + dumped to the debug file. Newer lines displace the + oldest if the buffer is full. After a trigger, + immediate writes to file are done as normal. + +trigger=<&'reason'&> This option selects cause for the pretrigger buffer + see above) to be copied to file. A reason of $*now* + take effect immediately; one of &*paniclog*& triggers + on a write to the panic log. +.endd + Some examples (which depend on variables that don't exist in all contexts): .code @@ -30911,6 +31760,8 @@ contexts): control = debug/opts=+expand+acl control = debug/tag=.$message_exim_id/opts=+expand control = debug/kill + control = debug/opts=+all/pretrigger=1024/trigger=paniclog + control = debug/trigger=now .endd @@ -31063,7 +31914,6 @@ response to an EHLO command. Therefore, it should normally appear in an ACL controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also &%pipelining_advertise_hosts%&. -.new .vitem &*control&~=&~queue/*&<&'options'&>* &&& &*control&~=&~queue_only*& .oindex "&%queue%&" @@ -31088,7 +31938,6 @@ able to send all such messages on a single connection. The control only applies to the current message, not to any subsequent ones that may be received in the same SMTP connection. -.wen .vitem &*control&~=&~submission/*&<&'options'&> .cindex "message" "submission" @@ -31543,6 +32392,14 @@ content-scanning extension, and is available only in the DATA, MIME, and non-SMTP ACLs. It causes the incoming message to be scanned for a match with any of the regular expressions. For details, see chapter &<>&. +.new +.vitem &*seen&~=&~*&<&'parameters'&> +.cindex "&%sseen%& ACL condition" +This condition can be used to test if a situation has been previously met, +for example for greylisting. +Details are given in section &<>&. +.wen + .vitem &*sender_domains&~=&~*&<&'domain&~list'&> .cindex "&%sender_domains%& ACL condition" .cindex "sender" "ACL checking" @@ -31602,8 +32459,9 @@ send email. Details of how this works are given in section .cindex "header lines" "verifying header names only ASCII" .cindex "verifying" "header names only ASCII" This condition is relevant only in an ACL that is run after a message has been -received, that is, in an ACL specified by &%acl_smtp_data%& or -&%acl_not_smtp%&. It checks all header names (not the content) to make sure +received. +This usually means an ACL specified by &%acl_smtp_data%& or &%acl_not_smtp%&. +It checks all header names (not the content) to make sure there are no non-ASCII characters, also excluding control characters. The allowable characters are decimal ASCII values 33 through 126. @@ -31758,7 +32616,7 @@ Note that '/' is legal in local-parts; if the address may have such (eg. is generated from the received message) they must be protected from the options parsing by doubling: .code -verify = sender=${sg{${address:$h_sender:}}{/}{//}} +verify = sender=${listquote{/}{${address:$h_sender:}}} .endd .endlist @@ -31800,11 +32658,11 @@ This is usually the required action when &%dnslists%& is used with &%deny%& (which is the most common usage), because it prevents a DNS failure from blocking mail. However, you can change this behaviour by putting one of the following special items in the list: -.display -&`+include_unknown `& behave as if the item is on the list -&`+exclude_unknown `& behave as if the item is not on the list (default) -&`+defer_unknown `& give a temporary error -.endd +.itable none 0 0 2 1pt left 1pt left +.irow "+include_unknown" "behave as if the item is on the list" +.irow "+exclude_unknown" "behave as if the item is not on the list (default)" +.irow "+defer_unknown " "give a temporary error" +.endtable .cindex "&`+include_unknown`&" .cindex "&`+exclude_unknown`&" .cindex "&`+defer_unknown`&" @@ -31953,19 +32811,24 @@ DNS lists are constructed using address records in the DNS. The original RBL just used the address 127.0.0.1 on the right hand side of each record, but the RBL+ list and some other lists use a number of values with different meanings. The values used on the RBL+ list are: -.display -127.1.0.1 RBL -127.1.0.2 DUL -127.1.0.3 DUL and RBL -127.1.0.4 RSS -127.1.0.5 RSS and RBL -127.1.0.6 RSS and DUL -127.1.0.7 RSS and DUL and RBL -.endd +.itable none 0 0 2 1pt left 1pt left +.irow 127.1.0.1 "RBL" +.irow 127.1.0.2 "DUL" +.irow 127.1.0.3 "DUL and RBL" +.irow 127.1.0.4 "RSS" +.irow 127.1.0.5 "RSS and RBL" +.irow 127.1.0.6 "RSS and DUL" +.irow 127.1.0.7 "RSS and DUL and RBL" +.endtable Section &<>& below describes how you can distinguish between different values. Some DNS lists may return more than one address record; see section &<>& for details of how they are checked. +Values returned by a properly running DBSBL should be in the 127.0.0.0/8 +range. If a DNSBL operator loses control of the domain, lookups on it +may start returning other addresses. Because of this, Exim now ignores +returned values outside the 127/8 region. + .section "Variables set from DNS lists" "SECID204" .cindex "expansion" "variables, set from DNS list" @@ -32102,6 +32965,14 @@ deny dnslists = relays.ordb.org .endd which is less clear, and harder to maintain. +Negation can also be used with a bitwise-and restriction. +The dnslists condition with only be trus if a result is returned +by the lookup which, anded with the restriction, is all zeroes. +For example: +.code +deny dnslists = zen.spamhaus.org!&0.255.255.0 +.endd + @@ -32251,6 +33122,63 @@ address you should specify alternate list separators for both the outer dnslists = <; dnsbl.example.com/<|$acl_m_addrslist .endd + +.new +.section "Previously seen user and hosts" "SECTseen" +.cindex "&%sseen%& ACL condition" +.cindex greylisting +The &%seen%& ACL condition can be used to test whether a +situation has been previously met. +It uses a hints database to record a timestamp against a key. +host. The syntax of the condition is: +.display +&`seen =`& <&'optional flag'&><&'time interval'&> &`/`& <&'options'&> +.endd + +For example, +.code +defer seen = -5m / key=${sender_host_address}_$local_part@$domain +.endd +in a RCPT ACL will implement simple greylisting. + +The parameters for the condition are +a possible minus sign, +then an interval, +then, slash-separated, a list of options. +The interval is taken as an offset before the current time, +and used for the test. +If the interval is preceded by a minus sign then the condition returns +whether a record is found which is before the test time. +Otherwise, the condition returns whether one is found which is since the +test time. + +Options are read in order with later ones overriding earlier ones. + +The default key is &$sender_host_address$&. +An explicit key can be set using a &%key=value%& option. + +If a &%readonly%& option is given then +no record create or update is done. +If a &%write%& option is given then +a record create or update is always done. +An update is done if the test is for &"since"&. +If none of those hold and there was no existing record, +a record is created. + +Creates and updates are marked with the current time. + +Finally, a &"before"& test which succeeds, and for which the record +is old enough, will be refreshed with a timestamp of the test time. +This can prevent tidying of the database from removing the entry. +The interval for this is, by default, 10 days. +An explicit interval can be set using a +&%refresh=value%& option. + +Note that &"seen"& should be added to the list of hints databases +for maintenance if this ACL condition is used. +.wen + + .section "Rate limiting incoming messages" "SECTratelimiting" .cindex "rate limiting" "client sending" .cindex "limiting client sending rates" @@ -32340,7 +33268,7 @@ in kilobytes, megabytes, or gigabytes, respectively. The &%per_rcpt%& option causes Exim to limit the rate at which recipients are accepted. It can be used in the &%acl_smtp_rcpt%&, &%acl_smtp_predata%&, -&%acl_smtp_mime%&, &%acl_smtp_data%&, or &%acl_smtp_rcpt%& ACLs. In +&%acl_smtp_mime%&, or &%acl_smtp_data%& ACLs. In &%acl_smtp_rcpt%& the rate is updated one recipient at a time; in the other ACLs the rate is updated with the total (accepted) recipient count in one go. Note that in either case the rate limiting engine will see a message with many @@ -32556,6 +33484,13 @@ The &%success_on_redirect%& option causes verification always to succeed immediately after a successful redirection. By default, if a redirection generates just one address, that address is also verified. See further discussion in section &<>&. +.next +If the &%quota%& option is specified for recipient verify, +successful routing to an appendfile transport is followed by a call into +the transport to evaluate the quota status for the recipient. +No actual delivery is done, but verification will succeed if the quota +is sufficient for the message (if the sender gave a message size) or +not already exceeded (otherwise). .endlist .cindex "verifying address" "differentiating failures" @@ -32572,6 +33507,7 @@ warn !verify = sender If you are writing your own custom rejection message or log message when denying access, you can use this variable to include information about the verification failure. +This variable is cleared at the end of processing the ACL verb. In addition, &$sender_verify_failure$& or &$recipient_verify_failure$& (as appropriate) contains one of the following words: @@ -32589,6 +33525,8 @@ connection, HELO, or MAIL). &%recipient%&: The RCPT command in a callout was rejected. .next &%postmaster%&: The postmaster check in a callout was rejected. +.next +&%quota%&: The quota check for a local recipient did non pass. .endlist The main use of these variables is expected to be to distinguish between @@ -32683,6 +33621,15 @@ output before performing a callout in an ACL, to avoid unexpected timeouts in clients when the SMTP PIPELINING extension is in use. The flushing can be disabled by using a &%control%& modifier to set &%no_callout_flush%&. +.new +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using receipient verify" +A recipient callout which gets a 2&'xx'& code +will assign untainted values to the +&$domain_data$& and &$local_part_data$& variables, +corresponding to the domain and local parts of the recipient address. +.wen + @@ -32918,6 +33865,36 @@ behaviour will be the same. +.section "Quota caching" "SECTquotacache" +.cindex "hints database" "quota cache" +.cindex "quota" "cache, description of" +.cindex "caching" "quota" +Exim caches the results of quota verification +in order to reduce the amount of resources used. +The &"callout"& hints database is used. + +The default cache periods are five minutes for a positive (good) result +and one hour for a negative result. +To change the periods the &%quota%& option can be followed by an equals sign +and a number of optional paramemters, separated by commas. +For example: +.code +verify = recipient/quota=cachepos=1h,cacheneg=1d +.endd +Possible parameters are: +.vlist +.vitem &*cachepos&~=&~*&<&'time&~interval'&> +.cindex "quota cache" "positive entry expiry, specifying" +Set the lifetime for a positive cache entry. +A value of zero seconds is legitimate. + +.vitem &*cacheneg&~=&~*&<&'time&~interval'&> +.cindex "quota cache" "negative entry expiry, specifying" +As above, for a negative entry. + +.vitem &*no_cache*& +Set both positive and negative lifetimes to zero. + .section "Sender address verification reporting" "SECTsenaddver" .cindex "verifying" "suppressing error details" See section &<>& for a general discussion of @@ -34235,10 +35212,8 @@ HAVE_LOCAL_SCAN=yes LOCAL_SCAN_SOURCE=Local/local_scan.c .endd for example. The function must be called &[local_scan()]&; -.new the source file(s) for it should first #define LOCAL_SCAN and then #include "local_scan.h". -.wen It is called by Exim after it has received a message, when the success return code is about to be sent. This is after all the ACLs have been run. The return code from your @@ -34442,11 +35417,11 @@ C variables are as follows: .vlist .vitem &*int&~body_linecount*& This variable contains the number of lines in the message's body. -It is not valid if the &%spool_files_wireformat%& option is used. +It is not valid if the &%spool_wireformat%& option is used. .vitem &*int&~body_zerocount*& This variable contains the number of binary zero bytes in the message's body. -It is not valid if the &%spool_files_wireformat%& option is used. +It is not valid if the &%spool_wireformat%& option is used. .vitem &*unsigned&~int&~debug_selector*& This variable is set to zero when no debugging is taking place. Otherwise, it @@ -34481,8 +35456,10 @@ discussed below. .vitem &*header_line&~*header_last*& A pointer to the last of the header lines. -.vitem &*uschar&~*headers_charset*& +.new +.vitem &*const&~uschar&~*headers_charset*& The value of the &%headers_charset%& configuration option. +.wen .vitem &*BOOL&~host_checking*& This variable is TRUE during a host checking session that is initiated by the @@ -34766,11 +35743,11 @@ added zero byte is not included in the returned count. .vitem &*int&~lss_match_domain(uschar&~*domain,&~uschar&~*list)*& This function checks for a match in a domain list. Domains are always matched caselessly. The return value is one of the following: -.display -&`OK `& match succeeded -&`FAIL `& match failed -&`DEFER `& match deferred -.endd +.itable none 0 0 2 1pt left 1pt left +.irow &`OK`& "match succeeded" +.irow &`FAIL`& "match failed" +.irow &`DEFER`& "match deferred" +.endtable DEFER is usually caused by some kind of lookup defer, such as the inability to contact a database. @@ -34919,7 +35896,6 @@ dropping of a TCP/IP connection), you can call &'smtp_fflush()'&, which has no arguments. It flushes the output stream, and returns a non-zero value if there is an error. -.new .vitem &*void&~*store_get(int,BOOL)*& This function accesses Exim's internal store (memory) manager. It gets a new chunk of memory whose size is given by the first argument. @@ -34928,7 +35904,6 @@ data possibly coming from an attacker (eg. the message content), FALSE if it is locally-sourced. Exim bombs out if it ever runs out of memory. See the next section for a discussion of memory handling. -.wen .vitem &*void&~*store_get_perm(int,BOOL)*& This function is like &'store_get()'&, but it always gets memory from the @@ -35249,14 +36224,14 @@ address if its delivery failed. .section "Per-address filtering" "SECTperaddfil" -.vindex "&$domain$&" -.vindex "&$local_part$&" +.vindex "&$domain_data$&" +.vindex "&$local_part_data$&" In contrast to the system filter, which is run just once per message for each delivery attempt, it is also possible to set up a system-wide filtering operation that runs once for each recipient address. In this case, variables -such as &$local_part$& and &$domain$& can be used, and indeed, the choice of -filter file could be made dependent on them. This is an example of a router -which implements such a filter: +such as &$local_part_data$& and &$domain_data$& can be used, +and indeed, the choice of filter file could be made dependent on them. +This is an example of a router which implements such a filter: .code central_filter: check_local_user @@ -35504,8 +36479,7 @@ incoming SMTP message from a source that is not permitted to send them. .section "Resent- header lines" "SECID220" -.cindex "&%Resent-%& header lines" -.cindex "header lines" "Resent-" +.chindex Resent- RFC 2822 makes provision for sets of header lines starting with the string &`Resent-`& to be added to a message when it is resent by the original recipient to somebody else. These headers are &'Resent-Date:'&, @@ -35561,8 +36535,7 @@ existing &'Bcc:'& is not removed. .section "The Date: header line" "SECID223" -.cindex "&'Date:'& header line" -.cindex "header lines" "Date:" +.cindex Date: If a locally-generated or submission-mode message has no &'Date:'& header line, Exim adds one, using the current date and time, unless the &%suppress_local_fixups%& control has been specified. @@ -35579,8 +36552,7 @@ messages. .section "The Envelope-to: header line" "SECID225" -.cindex "&'Envelope-to:'& header line" -.cindex "header lines" "Envelope-to:" +.chindex Envelope-to: .oindex "&%envelope_to_remove%&" &'Envelope-to:'& header lines are not part of the standard RFC 2822 header set. Exim can be configured to add them to the final delivery of messages. (See the @@ -35591,8 +36563,7 @@ messages. .section "The From: header line" "SECTthefrohea" -.cindex "&'From:'& header line" -.cindex "header lines" "From:" +.chindex From: .cindex "Sendmail compatibility" "&""From""& line" .cindex "message" "submission" .cindex "submission mode" @@ -35635,8 +36606,7 @@ name as described in section &<>&. .section "The Message-ID: header line" "SECID226" -.cindex "&'Message-ID:'& header line" -.cindex "header lines" "Message-ID:" +.chindex Message-ID: .cindex "message" "submission" .oindex "&%message_id_header_text%&" If a locally-generated or submission-mode incoming message does not contain a @@ -35651,8 +36621,7 @@ in this header line by setting the &%message_id_header_text%& and/or .section "The Received: header line" "SECID227" -.cindex "&'Received:'& header line" -.cindex "header lines" "Received:" +.chindex Received: A &'Received:'& header line is added at the start of every message. The contents are defined by the &%received_header_text%& configuration option, and Exim automatically adds a semicolon and a timestamp to the configured string. @@ -35668,8 +36637,7 @@ changed to the time of acceptance, which is (apart from a small delay while the .section "The References: header line" "SECID228" -.cindex "&'References:'& header line" -.cindex "header lines" "References:" +.chindex References: Messages created by the &(autoreply)& transport include a &'References:'& header line. This is constructed according to the rules that are described in section 3.64 of RFC 2822 (which states that replies should contain such a @@ -35683,8 +36651,7 @@ incoming message. If there are more than 12, the first one and then the final .section "The Return-path: header line" "SECID229" -.cindex "&'Return-path:'& header line" -.cindex "header lines" "Return-path:" +.chindex Return-path: .oindex "&%return_path_remove%&" &'Return-path:'& header lines are defined as something an MTA may insert when it does the final delivery of messages. (See the generic &%return_path_add%& @@ -35697,7 +36664,7 @@ default), Exim removes &'Return-path:'& header lines from incoming messages. .section "The Sender: header line" "SECTthesenhea" .cindex "&'Sender:'& header line" .cindex "message" "submission" -.cindex "header lines" "Sender:" +.chindex Sender: For a locally-originated message from an untrusted user, Exim may remove an existing &'Sender:'& header line, and it may add a new one. You can modify these actions by setting the &%local_sender_retain%& option true, the @@ -36877,8 +37844,8 @@ lists_request: lists_post: driver = redirect domains = lists.example - senders = ${if exists {/usr/lists/$local_part}\ - {lsearch;/usr/lists/$local_part}{*}} + local_parts = ${lookup {$local_part} dsearch,filter=file,ret=full {/usr/lists}} + senders = ${if exists {$local_part_data} {lsearch;$local_part_data}{*}} file = ${lookup {$local_part} dsearch,ret=full {/usr/lists}} forbid_pipe forbid_file @@ -37042,13 +38009,11 @@ virtual: data = ${lookup{$local_part}lsearch{/etc/mail/virtual/$domain_data}} no_more .endd -.new The &%domains%& option specifies that the router is to be skipped, unless there is a file in the &_/etc/mail/virtual_& directory whose name is the same as the domain that is being processed. The &(dsearch)& lookup used results in an untainted version of &$domain$& being placed into the &$domain_data$& variable. -.wen When the router runs, it looks up the local part in the file to find a new address (or list of addresses). The &%no_more%& @@ -37079,7 +38044,7 @@ follows: .code my_mailboxes: driver = appendfile - file = /var/mail/$domain/$local_part_data + file = /var/mail/$domain_data/$local_part_data user = mail .endd This uses a directory of mailboxes for each domain. The &%user%& setting is @@ -37119,7 +38084,7 @@ It runs a user's &_.forward_& file for all local parts of the form cases by testing the variable &$local_part_suffix$&. For example: .code if $local_part_suffix contains -special then -save /home/$local_part/Mail/special +save /home/$local_part_data/Mail/special endif .endd If the filter file does not exist, or does not deal with such addresses, they @@ -37487,7 +38452,7 @@ implying the use of a default path. When Exim encounters an empty item in the list, it searches the list defined by LOG_FILE_PATH, and uses the first item it finds that is neither empty nor &"syslog"&. This means that an empty item in &%log_file_path%& can be used to -mean &"use the path specified at build time"&. It no such item exists, log +mean &"use the path specified at build time"&. If no such item exists, log files are written in the &_log_& subdirectory of the spool directory. This is equivalent to the setting: .code @@ -37675,16 +38640,16 @@ One line is written to the main log for each message received, and for each successful, unsuccessful, and delayed delivery. These lines can readily be picked out by the distinctive two-character flags that immediately follow the timestamp. The flags are: -.display -&`<=`& message arrival -&`(=`& message fakereject -&`=>`& normal message delivery -&`->`& additional address in same delivery -&`>>`& cutthrough message delivery -&`*>`& delivery suppressed by &%-N%& -&`**`& delivery failed; address bounced -&`==`& delivery deferred; temporary problem -.endd +.itable none 0 0 2 1pt left 1pt left +.irow &%<=%& "message arrival" +.irow &%(=%& "message fakereject" +.irow &%=>%& "normal message delivery" +.irow &%->%& "additional address in same delivery" +.irow &%>>%& "cutthrough message delivery" +.irow &%*>%& "delivery suppressed by &%-N%&" +.irow &%**%& "delivery failed; address bounced" +.irow &%==%& "delivery deferred; temporary problem" +.endtable .section "Logging message reception" "SECID251" @@ -37784,7 +38749,8 @@ fields record the router and transport that were used to process the address. If SMTP AUTH was used for the delivery there is an additional item A= followed by the name of the authenticator that was used. If an authenticated identification was set up by the authenticator's &%client_set_id%& -option, this is logged too, separated by a colon from the authenticator name. +option, this is logged too, as a second colon-separated list item. +Optionally (see the &%smtp_mailauth%& &%log_selector%&) there may be a third list item. If a shadow transport was run after a successful local delivery, the log line for the successful delivery has an item added on the end, of the form @@ -37798,8 +38764,9 @@ parentheses afterwards. When more than one address is included in a single delivery (for example, two SMTP RCPT commands in one transaction) the second and subsequent addresses are flagged with &`->`& instead of &`=>`&. When two or more messages are delivered -down a single SMTP connection, an asterisk follows the IP address in the log -lines for the second and subsequent messages. +down a single SMTP connection, an asterisk follows the +remote IP address (and port if enabled) +in the log lines for the second and subsequent messages. When two or more messages are delivered down a single TLS connection, the DNS and some TLS-related information logged for the first message delivered will not be present in the log lines for the second and subsequent messages. @@ -38001,63 +38968,64 @@ log_selector = +arguments -retry_defer .endd The list of optional log items is in the following table, with the default selection marked by asterisks: -.display -&` 8bitmime `& received 8BITMIME status -&`*acl_warn_skipped `& skipped &%warn%& statement in ACL -&` address_rewrite `& address rewriting -&` all_parents `& all parents in => lines -&` arguments `& command line arguments -&`*connection_reject `& connection rejections -&`*delay_delivery `& immediate delivery delayed -&` deliver_time `& time taken to attempt delivery -&` delivery_size `& add &`S=`&&'nnn'& to => lines -&`*dkim `& DKIM verified domain on <= lines -&` dkim_verbose `& separate full DKIM verification result line, per signature -&`*dnslist_defer `& defers of DNS list (aka RBL) lookups -&` dnssec `& DNSSEC secured lookups -&`*etrn `& ETRN commands -&`*host_lookup_failed `& as it says -&` ident_timeout `& timeout for ident connection -&` incoming_interface `& local interface on <= and => lines -&` incoming_port `& remote port on <= lines -&`*lost_incoming_connection `& as it says (includes timeouts) -&` millisec `& millisecond timestamps and RT,QT,DT,D times -&`*msg_id `& on <= lines, Message-ID: header value -&` msg_id_created `& on <= lines, Message-ID: header value when one had to be added -&` outgoing_interface `& local interface on => lines -&` outgoing_port `& add remote port to => lines -&`*queue_run `& start and end queue runs -&` queue_time `& time on queue for one recipient -&` queue_time_overall `& time on queue for whole message -&` pid `& Exim process id -&` pipelining `& PIPELINING use, on <= and => lines -&` proxy `& proxy address on <= and => lines -&` receive_time `& time taken to receive message -&` received_recipients `& recipients on <= lines -&` received_sender `& sender on <= lines -&`*rejected_header `& header contents on reject log -&`*retry_defer `& &"retry time not reached"& -&` return_path_on_delivery `& put return path on => and ** lines -&` sender_on_delivery `& add sender to => lines -&`*sender_verify_fail `& sender verification failures -&`*size_reject `& rejection because too big -&`*skip_delivery `& delivery skipped in a queue run -&`*smtp_confirmation `& SMTP confirmation on => lines -&` smtp_connection `& incoming SMTP connections -&` smtp_incomplete_transaction`& incomplete SMTP transactions -&` smtp_mailauth `& AUTH argument to MAIL commands -&` smtp_no_mail `& session with no MAIL commands -&` smtp_protocol_error `& SMTP protocol errors -&` smtp_syntax_error `& SMTP syntax errors -&` subject `& contents of &'Subject:'& on <= lines -&`*tls_certificate_verified `& certificate verification status -&`*tls_cipher `& TLS cipher suite on <= and => lines -&` tls_peerdn `& TLS peer DN on <= and => lines -&` tls_sni `& TLS SNI on <= lines -&` unknown_in_list `& DNS lookup failed in list match - -&` all `& all of the above -.endd +.itable none 0 0 3 1pt left 10pt center 1pt left +.irow &`8bitmime`&   "received 8BITMIME status" +.irow &`acl_warn_skipped`& * "skipped &%warn%& statement in ACL" +.irow &`address_rewrite`&   "address rewriting" +.irow &`all_parents`&   "all parents in => lines" +.irow &`arguments`&   "command line arguments" +.irow &`connection_reject`& * "connection rejections" +.irow &`delay_delivery`& * "immediate delivery delayed" +.irow &`deliver_time`&   "time taken to attempt delivery" +.irow &`delivery_size`&   "add &`S=`&&'nnn'& to => lines" +.irow &`dkim`& * "DKIM verified domain on <= lines" +.irow &`dkim_verbose`&   "separate full DKIM verification result line, per signature" +.irow &`dnslist_defer`& * "defers of DNS list (aka RBL) lookups" +.irow &`dnssec`&   "DNSSEC secured lookups" +.irow &`etrn`& * "ETRN commands" +.irow &`host_lookup_failed`& * "as it says" +.irow &`ident_timeout`&   "timeout for ident connection" +.irow &`incoming_interface`&   "local interface on <= and => lines" +.irow &`incoming_port`&   "remote port on <= lines" +.irow &`lost_incoming_connection`& * "as it says (includes timeouts)" +.irow &`millisec`&   "millisecond timestamps and RT,QT,DT,D times" +.irow &`msg_id`& * "on <= lines, Message-ID: header value" +.irow &`msg_id_created`&   "on <= lines, Message-ID: header value when one had to be added" +.irow &`outgoing_interface`&   "local interface on => lines" +.irow &`outgoing_port`&   "add remote port to => lines" +.irow &`queue_run`& * "start and end queue runs" +.irow &`queue_time`&   "time on queue for one recipient" +.irow &`queue_time_exclusive`&   "exclude recieve time from QT times" +.irow &`queue_time_overall`&   "time on queue for whole message" +.irow &`pid`&   "Exim process id" +.irow &`pipelining`&   "PIPELINING use, on <= and => lines" +.irow &`proxy`&   "proxy address on <= and => lines" +.irow &`receive_time`&   "time taken to receive message" +.irow &`received_recipients`&   "recipients on <= lines" +.irow &`received_sender`&   "sender on <= lines" +.irow &`rejected_header`& * "header contents on reject log" +.irow &`retry_defer`& * "&&retry time not reached&&" +.irow &`return_path_on_delivery`&   "put return path on => and ** lines" +.irow &`sender_on_delivery`&   "add sender to => lines" +.irow &`sender_verify_fail`& * "sender verification failures" +.irow &`size_reject`& * "rejection because too big" +.irow &`skip_delivery`& * "delivery skipped in a queue run" +.irow &`smtp_confirmation`& * "SMTP confirmation on => lines" +.irow &`smtp_connection`&   "incoming SMTP connections" +.irow &`smtp_incomplete_transaction`&   "incomplete SMTP transactions" +.irow &`smtp_mailauth`&   "AUTH argument to MAIL commands" +.irow &`smtp_no_mail`&   "session with no MAIL commands" +.irow &`smtp_protocol_error`&   "SMTP protocol errors" +.irow &`smtp_syntax_error`&   "SMTP syntax errors" +.irow &`subject`&   "contents of &'Subject:'& on <= lines" +.irow &`tls_certificate_verified`& * "certificate verification status" +.irow &`tls_cipher`& * "TLS cipher suite on <= and => lines" +.irow &`tls_peerdn`&   "TLS peer DN on <= and => lines" +.irow &`tls_resumption`&   "append * to cipher field" +.irow &`tls_sni`&   "TLS SNI on <= lines" +.irow &`unknown_in_list`&   "DNS lookup failed in list match" +.irow &`all`&   "&*all of the above*&" +.endtable See also the &%slow_lookup_log%& main configuration option, section &<>& @@ -38165,6 +39133,7 @@ routing email addresses, but it does apply to &"byname"& lookups. client's ident port times out. .next .cindex "log" "incoming interface" +.cindex "log" "outgoing interface" .cindex "log" "local interface" .cindex "log" "local address and port" .cindex "TCP/IP" "logging local address and port" @@ -38173,7 +39142,8 @@ client's ident port times out. to the &"<="& line as an IP address in square brackets, tagged by I= and followed by a colon and the port number. The local interface and port are also added to other SMTP log lines, for example, &"SMTP connection from"&, to -rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines. +rejection lines, and (despite the name) to outgoing +&"=>"&, &"->"&, &"=="& and &"**"& lines. The latter can be disabled by turning off the &%outgoing_interface%& option. .next .cindex log "incoming proxy address" @@ -38264,18 +39234,13 @@ Delivery "L" fields have an asterisk appended if used. .cindex "log" "queue time" &%queue_time%&: The amount of time the message has been in the queue on the local host is logged as QT=<&'time'&> on delivery (&`=>`&) lines, for example, -&`QT=3m45s`&. The clock starts when Exim starts to receive the message, so it -includes reception time as well as the delivery time for the current address. -This means that it may be longer than the difference between the arrival and -delivery log line times, because the arrival log line is not written until the -message has been successfully received. +&`QT=3m45s`&. If millisecond logging is enabled, short times will be shown with greater precision, eg. &`QT=1.578s`&. .next &%queue_time_overall%&: The amount of time the message has been in the queue on the local host is logged as QT=<&'time'&> on &"Completed"& lines, for -example, &`QT=3m45s`&. The clock starts when Exim starts to receive the -message, so it includes reception time as well as the total delivery time. +example, &`QT=3m45s`&. .next .cindex "log" "receive duration" &%receive_time%&: For each message, the amount of real time it has taken to @@ -38334,10 +39299,12 @@ it is too big. .cindex "log" "frozen messages; skipped" .cindex "frozen messages" "logging skipping" &%skip_delivery%&: A log line is written whenever a message is skipped during a -queue run because it is frozen or because another process is already delivering -it. +queue run because it another process is already delivering it or because +it is frozen. .cindex "&""spool file is locked""&" -The message that is written is &"spool file is locked"&. +.cindex "&""message is frozen""&" +The message that is written is either &"spool file is locked"& or +&"message is frozen"&. .next .cindex "log" "smtp confirmation" .cindex "SMTP" "logging confirmation" @@ -38440,7 +39407,7 @@ unchanged, or whether they should be rendered as escape sequences. when TLS is in use. The item is &`CV=yes`& if the peer's certificate was verified using a CA trust anchor, -&`CA=dane`& if using a DNS trust anchor, +&`CV=dane`& if using a DNS trust anchor, and &`CV=no`& if not. .next .cindex "log" "TLS cipher" @@ -38454,8 +39421,15 @@ connection, the cipher suite used is added to the log line, preceded by X=. connection, and a certificate is supplied by the remote host, the peer DN is added to the log line, preceded by DN=. .next +.cindex "log" "TLS resumption" +.cindex "TLS" "logging session resumption" +&%tls_resumption%&: When a message is sent or received over an encrypted +connection and the TLS session resumed one used on a previous TCP connection, +an asterisk is appended to the X= cipher field in the log line. +.next .cindex "log" "TLS SNI" .cindex "TLS" "logging SNI" +.cindex SNI logging &%tls_sni%&: When a message is received over an encrypted connection, and the remote host provided the Server Name Indication extension, the SNI is added to the log line, preceded by SNI=. @@ -38512,9 +39486,9 @@ the next chapter. The utilities described here are: "check address acceptance from given IP" .irow &<>& &'exim_dbmbuild'& "build a DBM file" .irow &<>& &'exinext'& "extract retry information" -.irow &<>& &'exim_dumpdb'& "dump a hints database" -.irow &<>& &'exim_tidydb'& "clean up a hints database" -.irow &<>& &'exim_fixdb'& "patch a hints database" +.irow &<>& &'exim_dumpdb'& "dump a hints database" +.irow &<>& &'exim_tidydb'& "clean up a hints database" +.irow &<>& &'exim_fixdb'& "patch a hints database" .irow &<>& &'exim_lock'& "lock a mailbox file" .endtable @@ -38549,12 +39523,12 @@ but the format of the output is different. For this reason, there are some system configuration options that configure exactly how &'exiwhat'& works. If it doesn't seem to be working for you, check the following compile-time options: -.display -&`EXIWHAT_PS_CMD `& the command for running &'ps'& -&`EXIWHAT_PS_ARG `& the argument for &'ps'& -&`EXIWHAT_EGREP_ARG `& the argument for &'egrep'& to select from &'ps'& output -&`EXIWHAT_KILL_ARG `& the argument for the &'kill'& command -.endd +.itable none 0 0 2 1pt left 1pt left +.irow &`EXIWHAT_PS_CMD`& "the command for running &'ps'&" +.irow &`EXIWHAT_PS_ARG`& "the argument for &'ps'&" +.irow &`EXIWHAT_EGREP_ARG`& "the argument for &'egrep'& to select from &'ps'& output" +.irow &`EXIWHAT_KILL_ARG`& "the argument for the &'kill'& command" +.endtable An example of typical output from &'exiwhat'& is .code 164 daemon: -q1h, listening on port 25 @@ -38580,9 +39554,6 @@ or (in case &*-a*& switch is specified) .code exim -bp .endd -The &*-C*& option is used to specify an alternate &_exim.conf_& which might -contain alternate exim configuration the queue management might be using. - to obtain a queue listing, and then greps the output to select messages that match given criteria. The following selection options are available: @@ -38639,7 +39610,22 @@ Display messages in reverse order. Include delivered recipients in queue listing. .endlist +The following options give alternates for configuration: + +.vlist +.vitem &*-C*&&~<&'config&~file'&> +is used to specify an alternate &_exim.conf_& which might +contain alternate exim configuration the queue management might be using. + +.vitem &*-E*&&~<&'path'&> +can be used to specify a path for the exim binary, +overriding the built-in one. +.endlist + There is one more option, &%-h%&, which outputs a list of options. +.new +At least one selection option, or either the &*-c*& or &*-h*& option, must be given. +.wen @@ -38999,6 +39985,8 @@ for remote hosts .next &'ratelimit'&: the data for implementing the ratelimit ACL condition .next +&'tls'&: TLS session resumption data +.next &'misc'&: other hints data .endlist @@ -39016,15 +40004,22 @@ in a transport) -.section "exim_dumpdb" "SECID261" +.section "exim_dumpdb" "SECTdumpdb" .cindex "&'exim_dumpdb'&" The entire contents of a database are written to the standard output by the -&'exim_dumpdb'& program, which has no options or arguments other than the -spool and database names. For example, to dump the retry database: +&'exim_dumpdb'& program, +.new +taking as arguments the spool and database names. +An option &'-z'& may be given to request times in UTC; +otherwise times are in the local timezone. +An option &'-k'& may be given to dump only the record keys. +.wen +For example, to dump the retry database: .code exim_dumpdb /var/spool/exim retry .endd -Two lines of output are produced for each entry: +For the retry database +two lines of output are produced for each entry: .code T:mail.ref.example:192.168.242.242 146 77 Connection refused 31-Oct-1995 12:00:12 02-Nov-1995 12:21:39 02-Nov-1995 20:21:39 * @@ -39053,7 +40048,7 @@ cross-references. -.section "exim_tidydb" "SECID262" +.section "exim_tidydb" "SECTtidydb" .cindex "&'exim_tidydb'&" The &'exim_tidydb'& utility program is used to tidy up the contents of a hints database. If run with no options, it removes all records that are more than 30 @@ -39102,11 +40097,11 @@ databases is likely to keep on increasing. -.section "exim_fixdb" "SECID263" +.section "exim_fixdb" "SECTfixdb" .cindex "&'exim_fixdb'&" The &'exim_fixdb'& program is a utility for interactively modifying databases. Its main use is for testing Exim, but it might also be occasionally useful for -getting round problems in a live system. It has no options, and its interface +getting round problems in a live system. Its interface is somewhat crude. On entry, it prompts for input with a right angle-bracket. A key of a database record can then be entered, and the data for that record is displayed. @@ -39123,6 +40118,12 @@ resets the time of the next delivery attempt. Time values are given as a sequence of digit pairs for year, month, day, hour, and minute. Colons can be used as optional separators. +.new +Both displayed and input times are in the local timezone by default. +If an option &'-z'& is used on the command line, displayed times +are in UTC. +.wen + @@ -39893,7 +40894,7 @@ Consider the use of the &%inlisti%& expansion condition instead. .cindex "security" "data sources" .cindex "security" "regular expressions" .cindex "regular expressions" "security" -.cindex "PCRE" "security" +.cindex "PCRE2" "security" If configuration data for Exim can come from untrustworthy sources, there are some issues to be aware of: @@ -39903,7 +40904,7 @@ Use of &%${expand...}%& may provide a path for shell injection attacks. Letting untrusted data provide a regular expression is unwise. .next Using &%${match...}%& to apply a fixed regular expression against untrusted -data may result in pathological behaviour within PCRE. Be aware of what +data may result in pathological behaviour within PCRE2. Be aware of what "backtracking" means and consider options for being more strict with a regular expression. Avenues to explore include limiting what can match (avoiding &`.`& when &`[a-z0-9]`& or other character class will do), use of atomic grouping and @@ -40144,8 +41145,18 @@ was received, in the conventional Unix form &-- the number of seconds since the start of the epoch. The second number is a count of the number of messages warning of delayed delivery that have been sent to the sender. -There follow a number of lines starting with a hyphen. These can appear in any -order, and are omitted when not relevant: +.new +There follow a number of lines starting with a hyphen. +These contain variables, can appear in any +order, and are omitted when not relevant. + +If there is a second hyphen after the first, +the corresponding data is tainted. +If there is a value in parentheses, the data is quoted for a lookup. + +The following word specifies a variable, +and the remainder of the item depends on the variable. +.wen .vlist .vitem "&%-acl%&&~<&'number'&>&~<&'length'&>" @@ -40301,9 +41312,6 @@ was received from the client, this records the Distinguished Name from that certificate. .endlist -Any of the above may have an extra hyphen prepended, to indicate the the -corresponding data is untrusted. - Following the options there is a list of those addresses to which the message is not to be delivered. This set of addresses is initialized from the command line when the &%-t%& option is used and &%extract_addresses_remove_arguments%& @@ -40412,8 +41420,8 @@ There is no dot-stuffing (and no dot-termination). . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// -.chapter "DKIM, SPF and DMARC" "CHAPdkim" &&& - "DKIM, SPF and DMARC Support" +.chapter "DKIM, SPF, SRS and DMARC" "CHAPdkim" &&& + "DKIM, SPF, SRS and DMARC Support" .section "DKIM (DomainKeys Identified Mail)" SECDKIM .cindex "DKIM" @@ -40488,7 +41496,7 @@ but for EC keys it is the base64 of the pure key; no ASN.1 wrapping. Signing is enabled by setting private options on the SMTP transport. These options take (expandable) strings as arguments. -.option dkim_domain smtp string list&!! unset +.option dkim_domain smtp "string list&!!" unset The domain(s) you want to sign with. After expansion, this can be a list. Each element in turn, @@ -40498,7 +41506,7 @@ while expanding the remaining signing options. If it is empty after expansion, DKIM signing is not done, and no error will result even if &%dkim_strict%& is set. -.option dkim_selector smtp string list&!! unset +.option dkim_selector smtp "string list&!!" unset This sets the key selector string. After expansion, which can use &$dkim_domain$&, this can be a list. Each element in turn is put in the expansion @@ -40507,6 +41515,13 @@ option along with &%$dkim_domain%&. If the option is empty after expansion, DKIM signing is not done for this domain, and no error will result even if &%dkim_strict%& is set. +To do, for example, dual-signing with RSA and EC keys +this could be be used: +.code +dkim_selector = ec_sel : rsa_sel +dkim_private_key = KEYS_DIR/$dkim_selector +.endd + .option dkim_private_key smtp string&!! unset This sets the private key to use. You can use the &%$dkim_domain%& and @@ -40618,9 +41633,7 @@ When unspecified, the header names listed in RFC4871 will be used, whether or not each header is present in the message. The default list is available for the expansion in the macro &"_DKIM_SIGN_HEADERS"& -.new and an oversigning variant is in &"_DKIM_OVERSIGN_HEADERS"&. -.wen If a name is repeated, multiple headers by that name (or the absence thereof) will be signed. The textually later headers in the headers part of the @@ -40871,10 +41884,8 @@ Notes from the key record (tag n=). .vitem &%$dkim_key_length%& Number of bits in the key. -.new Valid only once the key is loaded, which is at the time the header signature is verified, which is after the body hash is. -.wen Note that RFC 8301 says: .code @@ -40987,6 +41998,9 @@ You may deny messages when this occurs. .vitem &%temperror%& This indicates a temporary error during all processing, including Exim's SPF processing. You may defer messages when this occurs. + +.vitem &%invalid%& +There was an error during processing of the SPF lookup .endlist You can prefix each string with an exclamation mark to invert @@ -41023,10 +42037,14 @@ variables: .vitem &$spf_received$& .vindex &$spf_received$& - This contains a complete Received-SPF: header that can be - added to the message. Please note that according to the SPF - draft, this header must be added at the top of the header - list. Please see section 10 on how you can do this. + This contains a complete Received-SPF: header (name and + content) that can be added to the message. Please note that + according to the SPF draft, this header must be added at the + top of the header list, i.e. with +.code +add_header = :at_start:$spf_received +.endd + See section &<>& for further details. Note: in case of "Best-guess" (see below), the convention is to put this string in a header called X-SPF-Guess: instead. @@ -41034,8 +42052,8 @@ variables: .vitem &$spf_result$& .vindex &$spf_result$& This contains the outcome of the SPF check in string form, - one of pass, fail, softfail, none, neutral, permerror or - temperror. + currently one of pass, fail, softfail, none, neutral, permerror, + temperror, or &"(invalid)"&. .vitem &$spf_result_guessed$& .vindex &$spf_result_guessed$& @@ -41044,8 +42062,11 @@ variables: .vitem &$spf_smtp_comment$& .vindex &$spf_smtp_comment$& +.vindex &%spf_smtp_comment_template%& This contains a string that can be used in a SMTP response to the calling party. Useful for "fail". + The string is generated by the SPF library from the template configured in the main config + option &%spf_smtp_comment_template%&. .endlist @@ -41106,6 +42127,106 @@ The lookup will return the same result strings as can appear in +.section "SRS (Sender Rewriting Scheme)" SECTSRS +.cindex SRS "sender rewriting scheme" + +SRS can be used to modify sender addresses when forwarding so that +SPF verification does not object to them. +It operates by encoding the original envelope sender in a new +sender local part and using a domain run by the forwarding site +as the new domain for the sender. Any DSN message should be returned +to this new sender at the forwarding site, which can extract the +original sender from the coded local part and forward the DSN to +the originator. + +This is a way of avoiding the breakage that SPF does to forwarding. +The constructed local-part will be longer than the original, +leading to possible problems with very long addresses. +The changing of the sender address also hinders the tracing of mail +problems. + +Exim can be built to include native SRS support. To do this +SUPPORT_SRS=yes must be defined in &_Local/Makefile_&. +If this has been done, the macros _HAVE_SRS and _HAVE_NATIVE_SRS +will be defined. +The support is limited to SRS0-encoding; SRS1 is not supported. + +.cindex SRS excoding +To encode an address use this expansion item: +.vlist +.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*& +.cindex "&%srs_encode%& expansion item" +.cindex SRS "expansion item" +The first argument should be a secret known and used by all systems +handling the recipient domain for the original message. +There is no need to periodically change this key; a timestamp is also +encoded. +The second argument should be given as the envelope sender address before this +encoding operation. +The third argument should be the recipient domain of the message when +it arrived at this system. +.endlist + +.cindex SRS decoding +To decode an address use this expansion condition: +.vlist +.vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*& +The first argument should be the recipient local prt as is was received. +The second argument is the site secret. + +If the messages is not for an SRS-encoded recipient the condition will +return false. If it is, the condition will return true and the variable +&$srs_recipient$& will be set to the decoded (original) value. +.endlist + +Example usage: +.code + #macro + SRS_SECRET = + + #routers + + outbound: + driver = dnslookup + # if outbound, and forwarding has been done, use an alternate transport + domains = ! +my_domains + transport = ${if eq {$local_part@$domain} \ + {$original_local_part@$original_domain} \ + {remote_smtp} {remote_forwarded_smtp}} + + inbound_srs: + driver = redirect + senders = : + domains = +my_domains + # detect inbound bounces which are SRS'd, and decode them + condition = ${if inbound_srs {$local_part} {SRS_SECRET}} + data = $srs_recipient + + inbound_srs_failure: + driver = redirect + senders = : + domains = +my_domains + # detect inbound bounces which look SRS'd but are invalid + condition = ${if inbound_srs {$local_part} {}} + allow_fail + data = :fail: Invalid SRS recipient address + + #... further routers here + + + # transport; should look like the non-forward outbound + # one, plus the max_rcpt and return_path options + remote_forwarded_smtp: + driver = smtp + # modify the envelope from, for mails that we forward + max_rcpt = 1 + return_path = ${srs_encode {SRS_SECRET} {$return_path} {$original_domain}} +.endd + + + + + .section DMARC SECDMARC .cindex DMARC verification @@ -41140,10 +42261,8 @@ during domain parsing. Maintained by Mozilla, the most current version can be downloaded from a link at &url(https://publicsuffix.org/list/public_suffix_list.dat). See also the util/renew-opendmarc-tlds.sh script. -.new The default for the option is unset. If not set, DMARC processing is disabled. -.wen The &%dmarc_history_file%& option, if set @@ -41217,16 +42336,16 @@ The &"dmarc_status"& condition takes a list of strings on its right-hand side. These strings describe recommended action based on the DMARC check. To understand what the policy recommendations mean, refer to the DMARC website above. Valid strings are: -.display -&'accept '& The DMARC check passed and the library recommends accepting the email. -&'reject '& The DMARC check failed and the library recommends rejecting the email. -&'quarantine '& The DMARC check failed and the library recommends keeping it for further inspection. -&'none '& The DMARC check passed and the library recommends no specific action, neutral. -&'norecord '& No policy section in the DMARC record for this sender domain. -&'nofrom '& Unable to determine the domain of the sender. -&'temperror '& Library error or dns error. -&'off '& The DMARC check was disabled for this email. -.endd +.itable none 0 0 2 1pt left 1pt left +.irow &'accept'& "The DMARC check passed and the library recommends accepting the email" +.irow &'reject'& "The DMARC check failed and the library recommends rejecting the email" +.irow &'quarantine'& "The DMARC check failed and the library recommends keeping it for further inspection" +.irow &'none'& "The DMARC check passed and the library recommends no specific action, neutral" +.irow &'norecord'& "No policy section in the DMARC record for this RFC5322.From field" +.irow &'nofrom'& "Unable to determine the domain of the sender" +.irow &'temperror'& "Library error or dns error" +.irow &'off'& "The DMARC check was disabled for this email" +.endtable You can prefix each string with an exclamation mark to invert its meaning, for example "!accept" will match all results but "accept". The string list is evaluated left-to-right in a @@ -41386,18 +42505,19 @@ automatically determines which version is in use. The Proxy Protocol header is the first data received on a TCP connection and is inserted before any TLS-on-connect handshake from the client; Exim negotiates TLS between Exim-as-server and the remote client, not between -Exim and the proxy server. +Exim and the proxy server. The Proxy Protocol header must be received +within &%proxy_protocol_timeout%&, which defaults to 3s. The following expansion variables are usable (&"internal"& and &"external"& here refer to the interfaces of the proxy): -.display -&'proxy_external_address '& IP of host being proxied or IP of remote interface of proxy -&'proxy_external_port '& Port of host being proxied or Port on remote interface of proxy -&'proxy_local_address '& IP of proxy server inbound or IP of local interface of proxy -&'proxy_local_port '& Port of proxy server inbound or Port on local interface of proxy -&'proxy_session '& boolean: SMTP connection via proxy -.endd +.itable none 0 0 2 1pt left 1pt left +.irow $proxy_external_address "IP of host being proxied or IP of remote interface of proxy" +.irow $proxy_external_port "Port of host being proxied or Port on remote interface of proxy" +.irow $proxy_local_address "IP of proxy server inbound or IP of local interface of proxy" +.irow $proxy_local_port "Port of proxy server inbound or Port on local interface of proxy" +.irow $proxy_session "boolean: SMTP connection via proxy" +.endtable If &$proxy_session$& is set but &$proxy_external_address$& is empty there was a protocol error. The variables &$sender_host_address$& and &$sender_host_port$& @@ -41444,15 +42564,15 @@ is an IP address and any subsequent elements are options. Options are a string =. The list of options is in the following table: -.display -&'auth '& authentication method -&'name '& authentication username -&'pass '& authentication password -&'port '& tcp port -&'tmo '& connection timeout -&'pri '& priority -&'weight '& selection bias -.endd +.itable none 0 0 2 1pt left 1pt left +.irow &'auth'& "authentication method" +.irow &'name'& "authentication username" +.irow &'pass'& "authentication password" +.irow &'port'& "tcp port" +.irow &'tmo'& "connection timeout" +.irow &'pri'& "priority" +.irow &'weight'& "selection bias" +.endtable More details on each of these options follows: @@ -41568,11 +42688,11 @@ This is usually for use in a Message Submission Agent context, but could be used for any message. If a value is appended it may be: -.display -&`1 `& mandatory downconversion -&`0 `& no downconversion -&`-1 `& if SMTPUTF8 not supported by destination host -.endd +.itable none 0 0 2 1pt right 1pt left +.irow &`1`& "mandatory downconversion" +.irow &`0`& "no downconversion" +.irow &`-1`& "if SMTPUTF8 not supported by destination host" +.endtable If no value is given, 1 is used. If mua_wrapper is set, the utf8_downconvert control @@ -41674,23 +42794,24 @@ expansion must check this, as it will be called for every possible event type. .new The current list of events is: +.itable all 0 0 4 1pt left 1pt center 1pt center 1pt left +.irow dane:fail after transport "per connection" +.irow msg:complete after main "per message" +.irow msg:defer after transport "per message per delivery try" +.irow msg:delivery after transport "per recipient" +.irow msg:rcpt:host:defer after transport "per recipient per host" +.irow msg:rcpt:defer after transport "per recipient" +.irow msg:host:defer after transport "per host per delivery try; host errors" +.irow msg:fail:delivery after transport "per recipient" +.irow msg:fail:internal after main "per recipient" +.irow tcp:connect before transport "per connection" +.irow tcp:close after transport "per connection" +.irow tls:cert before both "per certificate in verification chain" +.irow tls:fail:connect after main "per connection" +.irow smtp:connect after transport "per connection" +.irow smtp:ehlo after transport "per connection" +.endtable .wen -.display -&`dane:fail after transport `& per connection -&`msg:complete after main `& per message -&`msg:defer after transport `& per message per delivery try -&`msg:delivery after transport `& per recipient -&`msg:rcpt:host:defer after transport `& per recipient per host -&`msg:rcpt:defer after transport `& per recipient -&`msg:host:defer after transport `& per host per delivery try; host errors -&`msg:fail:delivery after transport `& per recipient -&`msg:fail:internal after main `& per recipient -&`tcp:connect before transport `& per connection -&`tcp:close after transport `& per connection -&`tls:cert before both `& per certificate in verification chain -&`smtp:connect after transport `& per connection -&`smtp:ehlo after transport `& per connection -.endd New event types may be added in future. The event name is a colon-separated list, defining the type of @@ -41706,23 +42827,24 @@ should define the event action. An additional variable, &$event_data$&, is filled with information varying with the event type: -.display -&`dane:fail `& failure reason -&`msg:defer `& error string -&`msg:delivery `& smtp confirmation message -&`msg:fail:internal `& failure reason -&`msg:fail:delivery `& smtp error message -&`msg:host:defer `& error string -&`msg:rcpt:host:defer `& error string -&`msg:rcpt:defer `& error string -&`tls:cert `& verification chain depth -&`smtp:connect `& smtp banner -&`smtp:ehlo `& smtp ehlo response -.endd +.itable all 0 0 2 1pt left 1pt left +.irow dane:fail "failure reason" +.irow msg:defer "error string" +.irow msg:delivery "smtp confirmation message" +.irow msg:fail:internal "failure reason" +.irow msg:fail:delivery "smtp error message" +.irow msg:host:defer "error string" +.irow msg:rcpt:host:defer "error string" +.irow msg:rcpt:defer "error string" +.irow tls:cert "verification chain depth" +.irow tls:fail:connect "error string" +.irow smtp:connect "smtp banner" +.irow smtp:ehlo "smtp ehlo response" +.endtable The :defer events populate one extra variable: &$event_defer_errno$&. -For complex operations an ACL expansion can be used in &%event_action%& +For complex operations an ACL expansion can be used in &%event_action%&, however due to the multiple contexts that Exim operates in during the course of its processing: .ilist @@ -41738,11 +42860,11 @@ a useful way of writing to the main log. The expansion of the event_action option should normally return an empty string. Should it return anything else the following will be forced: -.display -&`tcp:connect `& do not connect -&`tls:cert `& refuse verification -&`smtp:connect `& close connection -.endd +.itable all 0 0 2 1pt left 1pt left +.irow tcp:connect "do not connect" +.irow tls:cert "refuse verification" +.irow smtp:connect "close connection" +.endtable All other message types ignore the result string, and no other use is made of it.