X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/9d783bb9f39bca59e720d0c543499b372c412441..6d05006594ffacbfde1c8c4e759332873a702087:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index b462f6758..cd81a2287 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -45,7 +45,7 @@ . Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.94" +.set previousversion "4.96" .include ./local_params .set ACL "access control lists (ACLs)" @@ -54,7 +54,7 @@ .set drivernamemax "64" .macro copyyear -2020 +2022 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -97,6 +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. @@ -193,148 +208,69 @@ .copyyear - University of Cambridge + The Exim Maintainers .literal off . ///////////////////////////////////////////////////////////////////////////// -. 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 +. These implement 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" -.literal xml - - $1, $2, etc. - numerical variables - - - address - rewriting - rewriting - - - Bounce Address Tag Validation - BATV - - - Client SMTP Authorization - CSA - - - CR character - carriage return - - - CRL - certificate revocation list - - - delivery - failure report - bounce message - - - dialup - intermittently connected hosts - - - exiscan - content scanning - - - failover - fallback - - - fallover - fallback - - - filter - Sieve - Sieve filter - - - ident - RFC 1413 - - - LF character - linefeed - - - maximum - limit - - - monitor - Exim monitor - - - no_xxx - entry for xxx - - - NUL - binary zero - - - passwd file - /etc/passwd - - - process id - pid - - - RBL - DNS list - - - redirection - address redirection - - - return path - envelope sender - - - scanning - content scanning - - - SSL - TLS - - - string - expansion - expansion - - - top bit - 8-bit characters - - - variables - expansion, variables - - - zero, binary - binary zero - - - headers - header lines +.macro seeother +.literal xml + + $3 +.arg 5 + $5 +.endarg + <$1>$4 - .literal off +.endmacro + +. NB: for the 4-arg variant the ordering is awkward +.macro see +.seeother see "$1" "$2" "$3" "$4" +.endmacro +.macro seealso +.seeother seealso "$1" "$2" "$3" "$4" +.endmacro + +.see variable "$1, $2, etc." "numerical variables" +.see concept address rewriting rewriting +.see concept "Bounce Address Tag Validation" BATV +.see concept "Client SMTP Authorization" CSA +.see concept "CR character" "carriage return" +.see concept CRL "certificate revocation list" +.seealso concept de-tainting "tainted data" +.see concept delivery "bounce message" "failure report" +.see concept dialup "intermittently connected hosts" +.see concept exiscan "content scanning" +.see concept fallover fallback +.see concept filter "Sieve filter" Sieve +.see concept headers "header lines" +.see concept ident "RFC 1413" +.see concept "LF character" "linefeed" +.seealso concept maximum limit +.see concept monitor "Exim monitor" +.see concept "no_xxx" "entry for xxx" +.see concept NUL "binary zero" +.see concept "passwd file" "/etc/passwd" +.see concept "process id" pid +.see concept RBL "DNS list" +.see concept redirection "address redirection" +.see concept "return path" "envelope sender" +.see concept scanning "content scanning" +.see concept SSL TLS +.see concept string expansion expansion +.see concept "top bit" "8-bit characters" +.see concept variables "expansion, variables" +.see concept "zero, binary" "binary zero" . ///////////////////////////////////////////////////////////////////////////// @@ -758,17 +694,17 @@ 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 @@ -1413,8 +1349,8 @@ 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. -.new .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$& variable. Such an untainted value is often needed in the transport. @@ -1423,7 +1359,6 @@ refer to section &<>&. When an untainted value is wanted, use this option rather than the generic &%condition%& option. -.wen .next .vindex "&$local_part_prefix$&" @@ -1434,7 +1369,6 @@ rather than the generic &%condition%& option. .cindex affix "router precondition" If the &%local_parts%& option is set, the local part of the address must be in the set of local parts that it defines. -.new A match verifies the variable &$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. @@ -1443,7 +1377,6 @@ refer to section &<>&. When an untainted value is wanted, use this option rather than the generic &%condition%& option. -.wen If &%local_part_prefix%& or &%local_part_suffix%& is in use, the prefix or suffix is removed from the local @@ -1484,7 +1417,6 @@ 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 &<>&. -.new Note that while using this option for address matching technically works, it does not set any de-tainted values. @@ -1492,7 +1424,6 @@ 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. -.wen .endlist @@ -1743,20 +1674,20 @@ 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" @@ -1809,9 +1740,11 @@ 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, +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'&. +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 @@ -1835,6 +1768,7 @@ 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. +You can set USE_NDBM if needed to override an operating system default. At the lowest level, the build-time configuration sets none of these options, thereby assuming an interface of type (1). However, some operating system @@ -1849,7 +1783,9 @@ in one of these lines: .code DBMLIB = -ldb DBMLIB = -ltdb +DBMLIB = -lgdbm -lgdbm_compat .endd +The last of those was for a Linux having GDBM provide emulated NDBM facilities. 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 @@ -2585,6 +2521,25 @@ 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 @@ -2879,6 +2834,12 @@ defined and macros will be expanded. Because macros in the config file are often used for secrets, those are only available to admin users. +.new +The word &"set"& at the start of a line, followed by a single space, +is recognised specially as defining a value for a variable. +The syntax is otherwise the same as the ACL modifier &"set ="&. +.wen + .vitem &%-bem%&&~<&'filename'&> .oindex "&%-bem%&" .cindex "testing" "string expansion" @@ -3668,41 +3629,41 @@ 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`& @@ -3944,7 +3905,6 @@ 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. -.new .vitem &%-MCL%& .oindex "&%-MCL%&" This option is not intended for use by external callers. It is used internally @@ -3952,7 +3912,6 @@ 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. -.wen .vitem &%-MCP%& .oindex "&%-MCP%&" @@ -3960,14 +3919,12 @@ 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. -.new .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. -.wen .vitem &%-MCQ%&&~<&'process&~id'&>&~<&'pipe&~fd'&> .oindex "&%-MCQ%&" @@ -3978,12 +3935,10 @@ 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. -.new .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. -.wen .vitem &%-MCS%& .oindex "&%-MCS%&" @@ -3998,7 +3953,6 @@ 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. -.new .vitem &%-MCr%&&~<&'SNI'&> &&& &%-MCs%&&~<&'SNI'&> .oindex "&%-MCs%&" @@ -4008,7 +3962,6 @@ 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. -.wen .vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&> .oindex "&%-MCt%&" @@ -4530,7 +4483,6 @@ 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. -.new .vitem &%-oY%& .oindex &%-oY%& .cindex "daemon notifier socket" @@ -4549,7 +4501,6 @@ fast ramp-up of queue runner processes .next obtaining a current queue size .endlist -.wen .vitem &%-pd%& .oindex "&%-pd%&" @@ -6643,9 +6594,9 @@ 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 @@ -6657,10 +6608,10 @@ 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, @@ -6744,6 +6695,7 @@ 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. +The key for an expansion-style lookup must be given explicitly. 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 @@ -6755,6 +6707,7 @@ 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 @@ -6768,6 +6721,10 @@ domain2: Any data that follows the keys is not relevant when checking that the domain matches the list item. +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. + It is possible, though no doubt confusing, to use both kinds of lookup at once. Consider a file containing lines like this: .code @@ -6777,7 +6734,6 @@ 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. @@ -6787,7 +6743,6 @@ 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. -.wen 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 @@ -6804,20 +6759,24 @@ 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. .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. -.cindex "tainted data" "de-tainting" .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" +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. .endlist The code for each lookup type is in a separate source file that is included in @@ -6970,11 +6929,9 @@ the implicit key is the host's IP address rather than its name (see section IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this notation before executing the lookup.) -.new One option is supported, "ret=full", to request the return of the entire line -rather than omitting the key porttion. +rather than omitting the key portion. Note however that the key portion will have been de-quoted. -.wen .next .cindex lookup json @@ -6995,7 +6952,6 @@ is returned. For elements of type string, the returned value is de-quoted. -.new .next .cindex LMDB .cindex lookup lmdb @@ -7013,7 +6969,6 @@ 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. -.wen .next @@ -7415,6 +7370,10 @@ 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 @@ -7882,16 +7841,16 @@ 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 @@ -8271,7 +8230,6 @@ 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%& There are two ways of specifying the file. @@ -8281,7 +8239,6 @@ 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. -.wen A deprecated method is available, prefixing the query with the filename separated by white space. @@ -8505,10 +8462,8 @@ will store a result in the &$host_data$& variable. A &%local_parts%& router option or &%local_parts%& ACL condition will store a result in the &$local_part_data$& variable. .vitem domains -.new A &%domains%& router option or &%domains%& ACL condition will store a result in the &$domain_data$& variable. -.wen .vitem senders A &%senders%& router option or &%senders%& ACL condition will store a result in the &$sender_data$& variable. @@ -8810,14 +8765,13 @@ or a &%domains%& condition in an ACL statement, the value is preserved in the &$domain_data$& variable and can be referred to in other router options or other statements in the same ACL. .cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using ACL domains condition" The value will be untainted. -.new &*Note*&: If the data result of the lookup (as opposed to the key) is empty, then this empty value is stored in &$domain_data$&. The option to return the key for the lookup, as the value, may be what is wanted. -.wen .next @@ -8853,6 +8807,7 @@ whether or not the query succeeds. However, when a lookup is used for the &%domains%& option on a router, the value is preserved in the &$domain_data$& variable and can be referred to in other options. .cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using router domains option" The value will be untainted. .next @@ -9604,11 +9559,8 @@ reasons, .cindex "tainted data" definition .cindex expansion "tainted data" and expansion of data deriving from the sender (&"tainted data"&) -.new is not permitted (including acessing a file using a tainted name). -.wen -.new Common ways of obtaining untainted equivalents of variables with tainted values .cindex "tainted data" "de-tainting" @@ -9617,7 +9569,6 @@ This database could be the filesystem structure, or the password file, or accessed via a DBMS. Specific methods are indexed under &"de-tainting"&. -.wen @@ -10330,7 +10281,6 @@ extracted is used. You can use &`fail`& instead of {<&'string3'&>} as in a string extract. -.new .vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*& .cindex quoting "for list" .cindex list quoting @@ -10339,7 +10289,6 @@ 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. -.wen .vitem "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& @@ -10576,7 +10525,7 @@ sending the request. Values are &"yes"& (the default) or &"no"& &*tls*& Controls the use of TLS on the connection. Values are &"yes"& or &"no"& (the default). -If it is enabled, a shutdown as descripbed above is never done. +If it is enabled, a shutdown as described above is never done. .endlist @@ -10648,16 +10597,30 @@ expansion items. This item inserts &"raw"& header lines. It is described with the &%header%& expansion item in section &<>& above. -.vitem "&*${run{*&<&'command'&>&*&~*&<&'args'&>&*}{*&<&'string1'&>&*}&&& +.vitem "&*${run <&'options'&> {*&<&'command&~arg&~list'&>&*}{*&<&'string1'&>&*}&&& {*&<&'string2'&>&*}}*&" .cindex "expansion" "running a command" .cindex "&%run%& expansion item" -The command and its arguments are first expanded as one string. The string is -split apart into individual arguments by spaces, and then the command is run +This item runs an external command, as a subprocess. +One option is supported after the word &'run'&, comma-separated. + +If the option &'preexpand'& is not used, +the command string is split into individual arguments by spaces +and then each argument is expanded. +Then the command is run in a separate process, but under the same uid and gid. As in other command executions from Exim, a shell is not used by default. If the command requires a shell, you must explicitly code it. +The command name may not be tainted, but the remaining arguments can be. + +&*Note*&: if tainted arguments are used, they are supplied by a +potential attacker; +a careful assessment for security vulnerabilities should be done. +If the option &'preexpand'& is used, +the command and its arguments are first expanded as one string. The result is +split apart into individual arguments by spaces, and then the command is run +as above. Since the arguments are split by spaces, when there is a variable expansion which has an empty result, it will cause the situation that the argument will simply be omitted when the program is actually executed by Exim. If the @@ -10668,6 +10631,7 @@ in a string containing quotes, because it would interfere with the quotes around the command arguments. A possible guard against this is to wrap the variable in the &%sg%& operator to change any quote marks to some other character. +Neither the command nor any argument may be tainted. The standard input for the command exists, but is empty. The standard output and standard error are set to the same file descriptor. @@ -10780,23 +10744,21 @@ will sort an MX lookup into priority order. -.new .vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*& SRS encoding. See SECT &<>& for details. -.wen -.vitem &*${substr{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*& +.vitem &*${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 @@ -11203,10 +11165,8 @@ 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. -.new &*Note*&: Neither string-expansion of lists referenced by named-list syntax elements, nor expansion of lookup elements, is done by the &%listnamed%& operator. -.wen .vitem &*${local_part:*&<&'string'&>&*}*& @@ -11218,7 +11178,8 @@ empty. The parsing correctly handles SMTPUTF8 Unicode in the string. -.vitem &*${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" @@ -11232,8 +11193,12 @@ 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 +normal +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 @@ -11243,6 +11208,8 @@ returns the string .code 3ffe.ffff.836f.0a00.000a.0800.2000.0000/99 .endd +If the optional form &*mask_n*& is used, IPv6 address result are instead +returned in normailsed form, using colons and with zero-compression. Letters in IPv6 addresses are always output in lower case. @@ -11574,14 +11541,14 @@ 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} ... @@ -11769,11 +11736,9 @@ 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. -.new &*Note:*& Testing a path using this condition is not a sufficient way of de-tainting it. Consider using a dsearch lookup. -.wen .vitem &*first_delivery*& .cindex "delivery" "first" @@ -11860,10 +11825,8 @@ case-independent. Case and collation order are defined per the system C locale. -.new .vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*& SRS decode. See SECT &<>& for details. -.wen .vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& @@ -11884,6 +11847,18 @@ ${if inlisti{Needle}{fOo:NeeDLE:bAr}} ${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}} .endd +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$& is restored after the if. + + .vitem &*isip&~{*&<&'string'&>&*}*& &&& &*isip4&~{*&<&'string'&>&*}*& &&& &*isip6&~{*&<&'string'&>&*}*& @@ -12080,6 +12055,17 @@ item can be used, as in all address lists, to cause subsequent items to have their local parts matched casefully. Domains are always matched caselessly. +The variable &$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. + Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. @@ -12096,8 +12082,9 @@ 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 @@ -12274,6 +12261,14 @@ 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. +.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. .vlist .vitem "&$0$&, &$1$&, etc" @@ -12288,6 +12283,7 @@ 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. +If the subject string was tainted then any captured substring will also be. .vitem "&$acl_arg1$&, &$acl_arg2$&, etc" Within an acl condition, expansion condition or expansion item @@ -12322,8 +12318,8 @@ 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 = $acl_verify_message @@ -12331,6 +12327,7 @@ warn !verify = sender You can use &$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$&" @@ -12412,11 +12409,10 @@ authentication, which means this variable could also be visible in all of the ACL's as well. -.vitem &$authenticated_sender$& +.tvar &$authenticated_sender$& .cindex "sender" "authenticated" .cindex "authentication" "sender" .cindex "AUTH" "on MAIL command" -.vindex "&$authenticated_sender$&" When acting as a server, Exim takes note of the AUTH= parameter on an incoming SMTP MAIL command if it believes the sender is sufficiently trusted, as described in section &<>&. Unless the data is the string @@ -12439,9 +12435,10 @@ command that does not succeed. Otherwise it is set to &"0"&. This makes it possible to distinguish between &"did not try to authenticate"& (&$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$& .cindex "content scanning" "AV scanner failure" @@ -12568,8 +12565,7 @@ the following data from the lookup: the list's domain name, the key that was looked up, the contents of any associated TXT record, and the value from the main A record. See section &<>& for more details. -.vitem &$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$&. @@ -12634,14 +12630,12 @@ Often &$domain_data$& is usable in this role. .vitem &$domain_data$& .vindex "&$domain_data$&" When the &%domains%& condition on a router -.new or an ACL matches a domain against a list, the match value is copied to &$domain_data$&. This is an enhancement over previous versions of Exim, when it only applied to the data read by a lookup. For details on match values see section &<>& et. al. -.wen If the router routes the address to a transport, the value is available in that transport. If the @@ -12672,6 +12666,7 @@ There may be other characters following the minor version. This value may be overridden by the &%exim_version%& main config option. .vitem &$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 @@ -12732,6 +12727,7 @@ 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$&" @@ -12789,13 +12785,11 @@ option in the &(appendfile)& transport. The variable contains the inode number of the temporary file which is about to be renamed. It can be used to construct a unique name for the file. -.vitem &$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$&" @@ -12816,8 +12810,7 @@ This variable contains the system load average, multiplied by 1000 so that it is an integer. For example, if the load average is 0.21, the value of the variable is 210. The value is recomputed every time the variable is referenced. -.vitem &$local_part$& -.vindex "&$local_part$&" +.tvar &$local_part$& When an address is being routed, or delivered on its own, this variable contains the local part. When a number of addresses are being delivered together (for example, multiple RCPT commands in an SMTP @@ -12884,12 +12877,10 @@ to process local parts in a case-dependent manner in a router, you can set the .vindex "&$local_part_data$&" When the &%local_parts%& condition on a router or ACL matches a local part list -.new the match value is copied to &$local_part_data$&. This is an enhancement over previous versions of Exim, when it only applied to the data read by a lookup. For details on match values see section &<>& et. al. -.wen The &%check_local_user%& router option also sets this variable. @@ -12985,7 +12976,7 @@ when the ACL &%malware%& condition is true (see section &<>&). This variable contains the number of bytes in the longest line that was received as part of the message, not counting the line termination character(s). -It is not valid if the &%spool_files_wireformat%& option is used. +It is not valid if the &%spool_wireformat%& option is used. .vitem &$message_age$& .cindex "message" "age of" @@ -12994,11 +12985,10 @@ This variable is set at the start of a delivery attempt to contain the number of seconds since the message was received. It does not change during a single delivery attempt. -.vitem &$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$&" .oindex "&%message_body_visible%&" This variable contains the initial portion of a message's body while it is being delivered, and is intended mainly for use in filter files. The maximum @@ -13011,10 +13001,9 @@ easier to search for phrases that might be split over a line break. However, this can be disabled by setting &%message_body_newlines%& to be true. Binary zeros are always converted into spaces. -.vitem &$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$&. @@ -13029,7 +13018,7 @@ separates the body from the header. Newlines are included in the count. See also &$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$& @@ -13041,15 +13030,13 @@ received. &*Note*&: This is &'not'& the contents of the &'Message-ID:'& header line; it is the local id that Exim assigns to the message, for example: &`1BXTIK-0001yO-VA`&. -.vitem &$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$& except that no processing of the contents of header lines is done. @@ -13082,7 +13069,7 @@ deny condition = \ In the MAIL and RCPT ACLs, the value is zero because at that stage the message has not yet been received. -This variable is not valid if the &%spool_files_wireformat%& option is used. +This variable is not valid if the &%spool_wireformat%& option is used. .vitem &$message_size$& .cindex "size" "of message" @@ -13102,7 +13089,22 @@ While running a per message ACL (mail/rcpt/predata), &$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$& are available when Exim is compiled with the content-scanning extension. For details, see section &<>&. @@ -13111,9 +13113,8 @@ details, see section &<>&. These variables are counters that can be incremented by means of the &%add%& command in filter files. -.vitem &$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$&. However, if a &"child"& address (for example, generated by an alias, forward, or filter file) is being processed, this @@ -13126,9 +13127,8 @@ If a new address is created by means of a &%deliver%& command in a system filter, it is set up with an artificial &"parent"& address. This has the local part &'system-filter'& and the default qualify domain. -.vitem &$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$& always contains the full local @@ -13166,13 +13166,11 @@ messages received via the command line, this is the uid of the sending user. For messages received by SMTP over TCP/IP, this is normally the uid of the Exim user. -.vitem &$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$& (see above), except that it refers to the immediately preceding parent address. @@ -13191,6 +13189,9 @@ This is not an expansion variable, but is mentioned here because the string (described under &%transport_filter%& in chapter &<>&). It cannot be used in general expansion strings, and provokes an &"unknown variable"& error if encountered. +&*Note*&: This value permits data supplied by a potential attacker to +be used in the command for a &(pipe)& transport. +Such configurations should be carefully assessed for security vulnerbilities. .vitem &$primary_hostname$& .vindex "&$primary_hostname$&" @@ -13215,18 +13216,10 @@ For details see chapter &<>&. This variable is set to &"yes"& if PRDR was requested by the client for the current message, otherwise &"no"&. -.vitem &$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$& +These variables are used in conjunction with the &%prvscheck%& expansion item, which is described in sections &<>& and &<>&. @@ -13288,18 +13281,19 @@ including the one added by Exim (so its value is always greater than zero). It is available in the DATA ACL, the non-SMTP ACL, and while routing and delivering. -.vitem &$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$&.) When testing with &%-bh%&, the port value is -1 unless it has been set using the &%-oMi%& command line option. @@ -13312,10 +13306,6 @@ messages that are received, thus making these variables available at delivery time. For outbound connections see &$sending_ip_address$&. -.vitem &$received_port$& -.vindex "&$received_port$&" -See &$received_ip_address$&. - .vitem &$received_protocol$& .vindex "&$received_protocol$&" When a message is being processed, this variable contains the name of the @@ -13383,8 +13373,7 @@ MAIL). The main use of this variable is expected to be to distinguish between rejections of MAIL and rejections of RCPT. -.vitem &$recipients$& -.vindex "&$recipients$&" +.tvar &$recipients$& This variable contains a list of envelope recipients for a message. A comma and a space separate the addresses in the replacement text. However, the variable is not generally available, to prevent exposure of Bcc recipients in @@ -13421,10 +13410,10 @@ This variable is set to contain the matching regular expression after a When a &%regex%& or &%mime_regex%& ACL condition succeeds, these variables contain the captured substrings identified by the regular expression. +If the subject string was tainted then so will any captured substring. -.vitem &$reply_address$& -.vindex "&$reply_address$&" +.tvar &$reply_address$& When a message is being processed, this variable contains the contents of the &'Reply-To:'& header line if one exists and it is not empty, or otherwise the contents of the &'From:'& header line. Apart from the removal of leading @@ -13473,8 +13462,7 @@ One of its values causes the address to be passed to another router. When this happens, &$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$& When a message is being processed, this variable contains the sender's address that was received in the message's envelope. The case of letters in the address is retained, in both the local part and the domain. For bounce messages, the @@ -13489,12 +13477,10 @@ distinguish it from data from a recipient address. The value does not persist after the end of the current ACL statement. If you want to preserve it for longer, you can save it in an ACL variable. -.vitem &$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$& @@ -13532,8 +13518,7 @@ This boolean variable is true if a successful HELO verification was .cindex "DNS" "DNSSEC" done using DNS information the resolver library stated was authenticated data. -.vitem &$sender_helo_name$& -.vindex "&$sender_helo_name$&" +.tvar &$sender_helo_name$& When a message is received from a remote host that has issued a HELO or EHLO command, the argument of that command is placed in this variable. It is also set if HELO or EHLO is used when a message is received using SMTP locally via @@ -13590,8 +13575,7 @@ all EDNS0 options, then this will have no effect. OpenBSD's asr resolver is known to currently ignore EDNS0, documented in CAVEATS of asr_run(3). -.vitem &$sender_host_name$& -.vindex "&$sender_host_name$&" +.tvar &$sender_host_name$& When a message is received from a remote host, this variable contains the host's name as obtained by looking up its IP address. For messages received by other means, this variable is empty. @@ -13709,8 +13693,7 @@ host name, as specified by the &%smtp_active_hostname%& option. The value of &$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$& During the processing of an incoming SMTP command, this variable contains the entire command. This makes it possible to distinguish between HELO and EHLO in the HELO ACL, and also to distinguish between commands such as these: @@ -13723,9 +13706,8 @@ command, the address in &$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$&, this variable is @@ -13958,18 +13940,15 @@ If certificate verification fails it may refer to a failing chain element which is not the leaf. -.new .vitem &$tls_in_resumption$& &&& &$tls_out_resumption$& .vindex &$tls_in_resumption$& .vindex &$tls_out_resumption$& .cindex TLS resumption Observability for TLS session resumption. See &<>& for details. -.wen -.vitem &$tls_in_sni$& -.vindex "&$tls_in_sni$&" +.tvar &$tls_in_sni$& .vindex "&$tls_sni$&" .cindex "TLS" "Server Name Indication" .cindex "TLS" SNI @@ -14151,9 +14130,7 @@ 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. -.new &*Note*&: This is entirely separate from Exim's tainted-data tracking. -.wen .section "Calling Perl subroutines" "SECID86" @@ -14644,6 +14621,7 @@ listed in more than one group. .row &%log_timezone%& "add timezone to log lines" .row &%message_logs%& "create per-message logs" .row &%preserve_message_logs%& "after message completion" +.row &%panic_coredump%& "request coredump on fatal errors" .row &%process_log_path%& "for SIGUSR1 and &'exiwhat'&" .row &%slow_lookup_log%& "control logging of slow DNS lookups" .row &%syslog_duplication%& "controls duplicate log lines on syslog" @@ -14714,7 +14692,7 @@ 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 baclog" +.row &%smtp_backlog_monitor%& "level to log listen backlog" .endtable @@ -14815,8 +14793,11 @@ 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 &%hosts_require_helo%& "mandatory HELO/EHLO" .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" @@ -15201,7 +15182,6 @@ 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 @@ -15862,8 +15842,8 @@ 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. @@ -16302,8 +16282,29 @@ local processes, you must create a host list with an empty item. For example: .code hosts_connection_nolog = : .endd -If the &%smtp_connection%& log selector is not set, this option has no effect. +.new +The hosts affected by this option also do not log "no MAIL in SMTP connection" +lines, as may commonly be produced by a monitoring system. +.wen + + +.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_require_helo main "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_proxy main "host list&!!" unset @@ -16842,14 +16843,11 @@ 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, -.new "if nonempty," it should be a full path name and use a directory accessible to Exim. -.new If this option is set as empty, or the command line &%-oY%& option is used, or -.wen the command line uses a &%-oX%& option and does not use &%-oP%&, then a notifier socket is not created. @@ -16963,6 +16961,19 @@ to be used in conjunction with &(oracle)& lookups (see section &<>&). The option is available only if Exim has been built with Oracle support. +.new +.option panic_coredump main boolean false +This option is rarely needed but can help for some debugging investigations. +If set, when an internal error is detected by Exim which is sufficient +to terminate the process +(all such are logged in the paniclog) +then a coredump is requested. + +Note that most systems require additional administrative configuration +to permit write a core file for a setuid program, which is Exim's +common installed configuration. +.wen + .option percent_hack_domains main "domain list&!!" unset .cindex "&""percent hack""&" .cindex "source routing" "in email address" @@ -17037,9 +17048,9 @@ 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" PIPE_CONNECT -If Exim is built with the SUPPORT_PIPE_CONNECT build option +.cindex "pipelining" PIPECONNECT +.cindex "ESMTP extensions" PIPECONNECT +If Exim is built without the DISABLE_PIPE_CONNECT build option this option controls which hosts the facility is advertised to and from which pipeline early-connection (before MAIL) SMTP commands are acceptable. @@ -17047,9 +17058,11 @@ When used, the pipelining saves on roundtrip times. See also the &%hosts_pipe_connect%& smtp transport option. -.new -The SMTP service extension keyword advertised is &"PIPE_CONNECT"&. -.wen +The SMTP service extension keyword advertised is &"PIPECONNECT"&; +it permits the client to pipeline +TCP connection and hello command (inclear phase), +or TLS-establishment and hello command (encrypted phase), +on later connections to the same host. .option prdr_enable main boolean false @@ -17130,12 +17143,10 @@ admin user unless &%prod_requires_admin%& is set false. See also &%queue_list_requires_admin%& and &%commandline_checks_require_admin%&. -.new .option proxy_protocol_timeout main time 3s .cindex proxy "proxy protocol" This option sets the timeout for proxy protocol negotiation. For details see section &<>&. -.wen .option qualify_domain main string "see below" @@ -17173,15 +17184,13 @@ domains that do not match are processed. All other deliveries wait until the next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&. -.new -.option queue_fast_ramp main boolean false +.option queue_fast_ramp main boolean true .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. -.wen .option queue_list_requires_admin main boolean true @@ -17419,7 +17428,7 @@ initial set of recipients. The remote server should then re-send the message for the remaining recipients at a later time. -.option remote_max_parallel main integer 2 +.option remote_max_parallel main integer 4 .cindex "delivery" "parallelism for remote" This option controls parallel delivery of one message to a number of remote hosts. If the value is less than 2, parallel delivery is disabled, and Exim @@ -17621,11 +17630,9 @@ 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). -.new 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. -.wen .option smtp_accept_max_per_host main string&!! unset @@ -18331,7 +18338,18 @@ 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 @@ -18361,11 +18379,9 @@ Server Name Indication extension, then this option and others documented in &<>& will be re-expanded. If this option is unset or empty a self-signed certificate will be -.new used. Under Linux this is generated at daemon startup; on other platforms it will be generated fresh for every connection. -.wen .option tls_crl main string&!! unset .cindex "TLS" "server certificate revocation list" @@ -18408,12 +18424,7 @@ 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. @@ -18464,8 +18475,15 @@ 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. +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. 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, @@ -18542,7 +18560,7 @@ 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. @@ -18576,12 +18594,10 @@ preference order of the available ciphers. Details are given in sections &<>& and &<>&. -.new .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. -.wen .option tls_try_verify_hosts main "host list&!!" unset @@ -18640,7 +18656,8 @@ 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. @@ -18813,11 +18830,9 @@ 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%&. -.new 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. -.wen .option address_data routers string&!! unset @@ -18946,6 +18961,7 @@ 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, .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$& is set from the password data. The latter can be tested in other preconditions that are evaluated after this one (the order of evaluation is @@ -19809,10 +19825,8 @@ Values containing a list-separator should have them doubled. When a router runs, the strings are evaluated in order, to create variables which are added to the set associated with the address. -.new This is done immediately after all the preconditions, before the evaluation of the &%address_data%& option. -.wen The variable is set with the expansion of the value. The variables can be used by the router options (not including any preconditions) @@ -22361,11 +22375,9 @@ and &$original_domain$& is never set. .scindex IIDgenoptra1 "generic options" "transport" .scindex IIDgenoptra2 "options" "generic; for transports" .scindex IIDgenoptra3 "transport" "generic options for" -.new The name of a transport is limited to be &drivernamemax; ASCII characters long; prior to Exim 4.95 names would be silently truncated at this length, but now it is enforced. -.wen The following generic options apply to all transports: @@ -22436,6 +22448,12 @@ header, Exim has a configuration option (&%envelope_to_remove%&) which requests its removal from incoming messages, so that delivered messages can safely be resent to other recipients. +&*Note:*& If used on a transport handling multiple recipients +(the smtp transport unless &%rcpt_max%& is 1, the appendfile, pipe or lmtp +transport if &%batch_max%& is greater than 1) +then information about Bcc recipients will be leaked. +Doing so is generally not advised. + .option event_action transports string&!! unset .cindex events @@ -22777,9 +22795,10 @@ an ideal name for this feature here, but as it was already implemented for the The expansion variables &$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 @@ -23194,10 +23213,8 @@ directories defined by the &%directory%& option. In the case of maildir delivery, it applies to the top level directory, not the maildir directories beneath. -.new The option must be set to one of the words &"anywhere"&, &"inhome"&, or &"belowhome"&, or to an absolute path. -.wen In the second and third cases, a home directory must have been set for the transport, and the file or directory being created must @@ -23210,7 +23227,6 @@ are generated from users' &_.forward_& files. These are usually handled by an &(appendfile)& transport called &%address_file%&. See also &%file_must_exist%&. -.new In the fourth case, the value given for this option must be an absolute path for an existing directory. @@ -23218,9 +23234,9 @@ 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. -.wen .option directory appendfile string&!! unset @@ -23234,10 +23250,8 @@ 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. -.new The result of expansion must not be tainted, unless the &%create_file%& option specifies a path. -.wen .option directory_file appendfile string&!! "see below" @@ -23271,10 +23285,8 @@ 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%&. -.new The result of expansion must not be tainted, unless the &%create_file%& option specifies a path. -.wen .cindex "NFS" "lock file" .cindex "locking files" @@ -24658,6 +24670,9 @@ 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. +&*Note*&: Using enviroment variables loses track of tainted data. +Writers of &(pipe)& transport commands should be wary of data supplied +by potential attackers. .display &`DOMAIN `& the domain of the address &`HOME `& the home directory, if set @@ -24749,6 +24764,9 @@ 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. +.cindex "tainted data" +No part of the resulting command may be tainted. + .option environment pipe string&!! unset .cindex "&(pipe)& transport" "environment for command" @@ -25064,12 +25082,15 @@ 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 @@ -25081,7 +25102,6 @@ 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 @@ -25280,7 +25300,7 @@ 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 &<>&. @@ -25447,12 +25467,43 @@ 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. +.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$& variable +will be useful for such work. + .option hosts smtp "string list&!!" unset Hosts are associated with an address by a router such as &(dnslookup)&, which finds the hosts by looking up the address domain in the DNS, or by @@ -25506,7 +25557,7 @@ that matches this list, even if the server host advertises PIPELINING support. .option hosts_pipe_connect smtp "host list&!!" unset .cindex "pipelining" "early connection" -.cindex "pipelining" PIPE_CONNECT +.cindex "pipelining" PIPECONNECT If Exim is built with the SUPPORT_PIPE_CONNECT build option this option controls which to hosts the facility watched for and recorded, and used for subsequent connections. @@ -25520,7 +25571,8 @@ so combines well with TCP Fast Open. See also the &%pipelining_connect_advertise_hosts%& main option. Note: -When the facility is used, the transport &%helo_data%& option +When the facility is used, if the transport &%interface%& option is unset +the &%helo_data%& option will be expanded before the &$sending_ip_address$& variable is filled in. A check is made for the use of that variable, without the @@ -25631,6 +25683,18 @@ 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" @@ -25659,9 +25723,7 @@ incoming messages, use an appropriate ACL. 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 -.new and &%hosts_require_auth%& permits, -.wen Exim will try to transfer the message unauthenticated. See also chapter &<>& for details of authentication. @@ -25677,13 +25739,11 @@ 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" -.new 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. -.wen See the &%dnssec_request_domains%& router and transport options. See section &<>&. @@ -25772,7 +25832,6 @@ so can cause parallel connections to the same host if &%remote_max_parallel%& permits this. A value setting of zero disables the limit. -.new .option message_linelength_limit smtp integer 998 .cindex "line length" limit This option sets the maximum line length, in bytes, that the transport @@ -25783,7 +25842,6 @@ 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. -.wen .option multi_domain smtp boolean&!! true @@ -25799,11 +25857,9 @@ It is expanded per-address and can depend on any of &$address_data$&, &$domain_data$&, &$local_part_data$&, &$host$&, &$host_address$& and &$host_port$&. -.new If the connection is DANE-enabled then this option is ignored; only messages having the domain used for the DANE TLSA lookup are sent on the connection. -.wen .option port smtp string&!! "see below" .cindex "port" "sending TCP/IP" @@ -25909,6 +25965,19 @@ This option enables use of SOCKS proxies for connections made by the transport. For details see section &<>&. +.option tls_alpn smtp string&!! unset +.cindex TLS "Application Layer Protocol Names" +.cindex TLS ALPN +.cindex ALPN "set name in client" +If this option is set +and the TLS library supports ALPN, +the value given is used. + +As of writing no value has been standardised for email use. +The authors suggest using &"smtp"&. + + + .option tls_certificate smtp string&!! unset .cindex "TLS" "client certificate, location of" .cindex "certificate" "client, location of" @@ -25973,12 +26042,10 @@ is used in different ways by OpenSSL and GnuTLS (see sections ciphers is a preference order. -.new .option tls_resumption_hosts smtp "host list&!!" unset .cindex TLS resumption This option controls which connections to use the TLS resumption feature. See &<>& for details. -.wen @@ -25988,9 +26055,7 @@ See &<>& for details. .cindex SNI "setting in client" .vindex "&$tls_sni$&" If this option is set -.new and the connection is not DANE-validated -.wen 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 @@ -26085,6 +26150,10 @@ 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" @@ -27203,11 +27272,9 @@ 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. -.new 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. -.wen .cindex "AUTH" "description of" .cindex "ESMTP extensions" AUTH @@ -27952,10 +28019,8 @@ fixed_plain: .endd The lack of colons means that the entire text is sent with the AUTH command, with the circumflex characters converted to NULs. -.new Note that due to the ambiguity of parsing three consectutive circumflex characters there is no way to provide a password having a leading circumflex. -.wen A similar example @@ -28282,11 +28347,9 @@ realease for the SCRAM-SHA-256 method. The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined when this happens. -.new 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. -.wen .option client_authz gsasl string&!! unset @@ -28309,10 +28372,8 @@ the account name to be used. .option client_spassword gsasl string&!! unset -.new 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. -.wen If a SCRAM mechanism is being used and this option is set and correctly sized @@ -28324,7 +28385,6 @@ with the PBKDF2-prepared password, hex-encoded. Note that this value will depend on the salt and iteration-count supplied by the server. The option is expanded before use. -.new During the expansion &$auth1$& is set with the client username, &$auth2$& with the iteration count, and &$auth3$& with the salt. @@ -28341,7 +28401,6 @@ If the authentication succeeds then the above variables are set, plus the calculated salted password value value in &$auth4$&, during the expansion of the &%client_set_id%& option. A side-effect of this expansion can be used to prime the cache. -.wen .option server_channelbinding gsasl boolean false @@ -28368,12 +28427,10 @@ of Exim might have switched the default to be true. . Do not plan to rely upon this feature for security, ever, without consulting . with a subject matter expert (a cryptographic engineer). -.new 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. -.wen .option server_hostname gsasl string&!! "see below" @@ -29046,12 +29103,10 @@ 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. -.new .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. -.wen .endlist @@ -29525,7 +29580,6 @@ There is no current way to staple a proof for a client certificate. .endd -.new .section "Caching of static server configuration items" "SECTserverTLScache" .cindex certificate caching .cindex privatekey caching @@ -29577,7 +29631,6 @@ 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. -.wen @@ -29649,13 +29702,11 @@ or need not succeed respectively. The &%tls_verify_cert_hostnames%& option lists hosts for which additional name checks are made on the server certificate. -.new 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. -.wen The option defaults to always checking. The &(smtp)& transport has two OCSP-related options: @@ -29703,7 +29754,6 @@ outgoing connection. -.new .section "Caching of static client configuration items" "SECTclientTLScache" .cindex certificate caching .cindex privatekey caching @@ -29754,7 +29804,6 @@ 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. -.wen @@ -29794,10 +29843,8 @@ nothing more to it. Choosing a sensible value not derived insecurely is the only point of caution. The &$tls_out_sni$& variable will be set to this string for the lifetime of the client connection (including during authentication). -.new If DANE validated the connection attempt then the value of the &%tls_sni%& option -is forced to the domain part of the recipient address. -.wen +is forced to the name of the destination host, after any MX- or CNAME-following. Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string received from a client. @@ -29839,6 +29886,33 @@ 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" &&& @@ -29985,7 +30059,6 @@ Open-source PKI book, available online at .ecindex IIDencsmtp2 -.new .section "TLS Resumption" "SECTresumption" .cindex TLS resumption TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined @@ -30077,7 +30150,6 @@ Issues: .endlist .endlist -.wen .section DANE "SECDANE" @@ -30427,6 +30499,9 @@ 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. +For tls-on-connect connections, the ACL is run after the TLS connection +is accepted (however, &%host_reject_connection%& is tested before). + .section "The EHLO/HELO ACL" "SECID192" .cindex "EHLO" "ACL for" @@ -31355,8 +31430,9 @@ 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. @@ -31543,12 +31619,43 @@ 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. + +Logging set up by the control will be maintained across spool residency. + +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: +.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 $*now* + take effect immediately; one of &*paniclog*& triggers + on a write to the panic log. +.endd + Some examples (which depend on variables that don't exist in all contexts): .code @@ -31557,6 +31664,8 @@ contexts): control = debug/opts=+expand+acl control = debug/tag=.$message_exim_id/opts=+expand control = debug/kill + control = debug/opts=+all/pretrigger=1024/trigger=paniclog + control = debug/trigger=now .endd @@ -32074,7 +32183,7 @@ different variants of this condition to describe briefly here. See sections .cindex "domain" "ACL checking" .cindex "&ACL;" "testing a recipient domain" .vindex "&$domain_data$&" -This condition is relevant only after a RCPT command. It checks that the domain +This condition is relevant only in a RCPT ACL. It checks that the domain of the recipient address is in the domain list. If percent-hack processing is enabled, it is done before this test is done. If the check succeeds with a lookup, the result of the lookup is placed in &$domain_data$& until the next @@ -32142,7 +32251,7 @@ which gives a custom error message for each denied host. .cindex "local part" "ACL checking" .cindex "&ACL;" "testing a local part" .vindex "&$local_part_data$&" -This condition is relevant only after a RCPT command. It checks that the local +This condition is relevant only in a RCPT ACL. It checks that the local part of the recipient address is in the list. If percent-hack processing is enabled, it is done before this test. If the check succeeds with a lookup, the result of the lookup is placed in &$local_part_data$&, which remains set until @@ -32176,7 +32285,7 @@ messages. Details are given in section &<>&. .cindex "&%recipients%& ACL condition" .cindex "recipient" "ACL checking" .cindex "&ACL;" "testing a recipient" -This condition is relevant only after a RCPT command. It checks the entire +This condition is relevant only in a RCPT ACL. It checks the entire recipient address against a list of recipients. .vitem &*regex&~=&~*&<&'list&~of&~regular&~expressions'&> @@ -32187,6 +32296,12 @@ 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 &<>&. +.vitem &*seen&~=&~*&<&'parameters'&> +.cindex "&%seen%& 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 &<>&. + .vitem &*sender_domains&~=&~*&<&'domain&~list'&> .cindex "&%sender_domains%& ACL condition" .cindex "sender" "ACL checking" @@ -32445,11 +32560,11 @@ 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`&" @@ -32598,25 +32713,23 @@ 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. -.new 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. -.wen .section "Variables set from DNS lists" "SECID204" @@ -32911,6 +33024,61 @@ address you should specify alternate list separators for both the outer dnslists = <; dnsbl.example.com/<|$acl_m_addrslist .endd + +.section "Previously seen user and hosts" "SECTseen" +.cindex "&%een%& ACL condition" +.cindex greylisting +The &%seen%& ACL condition can be used to test whether a +situation has been previously met. +It uses a hints database to record a timestamp against a key. +host. The syntax of the condition is: +.display +&`seen =`& <&'optional flag'&><&'time interval'&> &`/`& <&'options'&> +.endd + +For example, +.code +defer seen = -5m / key=${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. + + .section "Rate limiting incoming messages" "SECTratelimiting" .cindex "rate limiting" "client sending" .cindex "limiting client sending rates" @@ -33216,7 +33384,6 @@ 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 &<>&. -.new .next If the &%quota%& option is specified for recipient verify, successful routing to an appendfile transport is followed by a call into @@ -33224,7 +33391,6 @@ 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). -.wen .endlist .cindex "verifying address" "differentiating failures" @@ -33241,6 +33407,7 @@ 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: @@ -33258,7 +33425,6 @@ connection, HELO, or MAIL). &%recipient%&: The RCPT command in a callout was rejected. .next &%postmaster%&: The postmaster check in a callout was rejected. -.new .next &%quota%&: The quota check for a local recipient did non pass. .endlist @@ -33355,6 +33521,13 @@ 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%&. +.cindex "tainted data" "de-tainting" +.cindex "de-tainting" "using recipient 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. + @@ -33590,7 +33763,6 @@ behaviour will be the same. -.new .section "Quota caching" "SECTquotacache" .cindex "hints database" "quota cache" .cindex "quota" "cache, description of" @@ -33620,7 +33792,6 @@ As above, for a negative entry. .vitem &*no_cache*& Set both positive and negative lifetimes to zero. -.wen .section "Sender address verification reporting" "SECTsenaddver" .cindex "verifying" "suppressing error details" @@ -35144,11 +35315,11 @@ 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 @@ -35183,7 +35354,7 @@ discussed below. .vitem &*header_line&~*header_last*& A pointer to the last of the header lines. -.vitem &*uschar&~*headers_charset*& +.vitem &*const&~uschar&~*headers_charset*& The value of the &%headers_charset%& configuration option. .vitem &*BOOL&~host_checking*& @@ -35468,11 +35639,11 @@ 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. @@ -37569,8 +37740,8 @@ 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 @@ -38179,7 +38350,7 @@ 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"&. If no such item exists, log files are written in the &_log_& subdirectory of the spool directory. This is -equivalent to the setting: +equivalent to the configuration file setting: .code log_file_path = $spool_directory/log/%slog .endd @@ -38190,7 +38361,7 @@ that is where the logs are written. A log file path may also contain &`%D`& or &`%M`& if datestamped log filenames are in use &-- see section &<>& below. -Here are some examples of possible settings: +Here are some examples of possible Makefile settings: .display &`LOG_FILE_PATH=syslog `& syslog only &`LOG_FILE_PATH=:syslog `& syslog and default path @@ -38365,16 +38536,16 @@ 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" @@ -38490,9 +38661,7 @@ 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 -.new remote IP address (and port if enabled) -.wen 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 @@ -38695,65 +38864,64 @@ 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_exclusive `& exclude recieve time from QT times -&` 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_resumption `& append * to cipher field -&` 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 &<>& @@ -38871,9 +39039,7 @@ 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 -.new &"=>"&, &"->"&, &"=="& and &"**"& lines. -.wen The latter can be disabled by turning off the &%outgoing_interface%& option. .next .cindex log "incoming proxy address" @@ -38951,7 +39117,7 @@ On accept lines, where PIPELINING was offered but not used by the client, the field has a minus appended. .cindex "pipelining" "early connection" -If Exim is built with the SUPPORT_PIPE_CONNECT build option +If Exim is built without the DISABLE_PIPE_CONNECT build option accept "L" fields have a period appended if the feature was offered but not used, or an asterisk appended if used. Delivery "L" fields have an asterisk appended if used. @@ -39153,11 +39319,9 @@ added to the log line, preceded by DN=. .next .cindex "log" "TLS resumption" .cindex "TLS" "logging session resumption" -.new &%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. -.wen .next .cindex "log" "TLS SNI" .cindex "TLS" "logging SNI" @@ -39255,12 +39419,12 @@ 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 @@ -39286,9 +39450,6 @@ 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: @@ -39345,7 +39506,20 @@ 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. +At least one selection option, or either the &*-c*& or &*-h*& option, must be given. @@ -39705,9 +39879,7 @@ for remote hosts .next &'ratelimit'&: the data for implementing the ratelimit ACL condition .next -.new &'tls'&: TLS session resumption data -.wen .next &'misc'&: other hints data .endlist @@ -39729,12 +39901,17 @@ in a transport) .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, +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. +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 * @@ -39816,7 +39993,7 @@ databases is likely to keep on increasing. .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. @@ -39833,6 +40010,10 @@ 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. +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. + @@ -40603,7 +40784,7 @@ 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: @@ -40613,7 +40794,7 @@ Use of &%${expand...}%& may provide a path for shell injection attacks. Letting untrusted data provide a regular expression is unwise. .next Using &%${match...}%& to apply a fixed regular expression against untrusted -data may result in pathological behaviour within PCRE. Be aware of what +data may result in pathological behaviour within PCRE2. Be aware of what "backtracking" means and consider options for being more strict with a regular expression. Avenues to explore include limiting what can match (avoiding &`.`& when &`[a-z0-9]`& or other character class will do), use of atomic grouping and @@ -40854,8 +41035,16 @@ was received, in the conventional Unix form &-- the number of seconds since the start of the epoch. The second number is a count of the number of messages warning of delayed delivery that have been sent to the sender. -There follow a number of lines starting with a hyphen. These can appear in any -order, and are omitted when not relevant: +There follow a number of lines starting with a hyphen. +These contain variables, can appear in any +order, and are omitted when not relevant. + +If there is a second hyphen after the first, +the corresponding data is tainted. +If there is a value in parentheses, the data is quoted for a lookup. + +The following word specifies a variable, +and the remainder of the item depends on the variable. .vlist .vitem "&%-acl%&&~<&'number'&>&~<&'length'&>" @@ -41011,9 +41200,6 @@ was received from the client, this records the Distinguished Name from that certificate. .endlist -Any of the above may have an extra hyphen prepended, to indicate the the -corresponding data is untrusted. - Following the options there is a list of those addresses to which the message is not to be delivered. This set of addresses is initialized from the command line when the &%-t%& option is used and &%extract_addresses_remove_arguments%& @@ -41203,6 +41389,7 @@ The domain(s) you want to sign with. After expansion, this can be a list. Each element in turn, lowercased, +.vindex "&$dkim_domain$&" is put into the &%$dkim_domain%& expansion variable while expanding the remaining signing options. If it is empty after expansion, DKIM signing is not done, @@ -41212,19 +41399,18 @@ and no error will result even if &%dkim_strict%& is set. 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 +.vindex "&$dkim_selector$&" variable &%$dkim_selector%& which may be used in the &%dkim_private_key%& option along with &%$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. -.new 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/$dkim_selector .endd -.wen .option dkim_private_key smtp string&!! unset This sets the private key to use. @@ -41702,6 +41888,9 @@ You may deny messages when this occurs. .vitem &%temperror%& This indicates a temporary error during all processing, including Exim's SPF processing. You may defer messages when this occurs. + +.vitem &%invalid%& +There was an error during processing of the SPF lookup .endlist You can prefix each string with an exclamation mark to invert @@ -41738,10 +41927,14 @@ variables: .vitem &$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. @@ -41749,8 +41942,8 @@ 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 &$spf_result_guessed$& @@ -41827,7 +42020,6 @@ The lookup will return the same result strings as can appear in .section "SRS (Sender Rewriting Scheme)" SECTSRS .cindex SRS "sender rewriting scheme" -.new 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 @@ -41861,6 +42053,7 @@ 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. +If this value is empty the the expansion result will be empty. The third argument should be the recipient domain of the message when it arrived at this system. .endlist @@ -41922,7 +42115,6 @@ Example usage: .endd -.wen @@ -42035,16 +42227,16 @@ 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 RFC5322.From field -&'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 @@ -42210,13 +42402,13 @@ 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$& @@ -42263,15 +42455,15 @@ is an IP address and any subsequent elements are options. Options are a string =. The list of options is in the following table: -.display -&'auth '& authentication method -&'name '& authentication username -&'pass '& authentication password -&'port '& tcp port -&'tmo '& connection timeout -&'pri '& priority -&'weight '& selection bias -.endd +.itable none 0 0 2 1pt left 1pt left +.irow &'auth'& "authentication method" +.irow &'name'& "authentication username" +.irow &'pass'& "authentication password" +.irow &'port'& "tcp port" +.irow &'tmo'& "connection timeout" +.irow &'pri'& "priority" +.irow &'weight'& "selection bias" +.endtable More details on each of these options follows: @@ -42387,11 +42579,11 @@ This is usually for use in a Message Submission Agent context, but could be used for any message. If a value is appended it may be: -.display -&`1 `& mandatory downconversion -&`0 `& no downconversion -&`-1 `& if SMTPUTF8 not supported by destination host -.endd +.itable none 0 0 2 1pt right 1pt left +.irow &`1`& "mandatory downconversion" +.irow &`0`& "no downconversion" +.irow &`-1`& "if SMTPUTF8 not supported by destination host" +.endtable If no value is given, 1 is used. If mua_wrapper is set, the utf8_downconvert control @@ -42492,22 +42684,23 @@ The name is placed in the variable &$event_name$& and the event action expansion must check this, as it will be called for every possible event type. The current list of events is: -.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 +.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 New event types may be added in future. The event name is a colon-separated list, defining the type of @@ -42523,23 +42716,24 @@ 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 @@ -42555,11 +42749,11 @@ 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.