X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/8b78698fadd197d75137df1bb0b0aae4f601f7f3..d518c8b6721ea30a9dc3190e57157edd676234ec:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 9dabe1658..6c885176f 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 "4.95" .include ./local_params .set ACL "access control lists (ACLs)" @@ -54,7 +54,7 @@ .set drivernamemax "64" .macro copyyear -2020 +2021 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -193,7 +193,7 @@ .copyyear - University of Cambridge + The Exim Maintainers .literal off @@ -239,14 +239,6 @@ failure report bounce message - - de-tainting - tainting, de-tainting - - - detainting - tainting, de-tainting - dialup intermittently connected hosts @@ -766,17 +758,17 @@ 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 @@ -1421,7 +1413,6 @@ 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" A match verifies the variable &$domain$& (which carries tainted data) and assigns an untainted value to the &$domain_data$& variable. @@ -1431,7 +1422,6 @@ refer to section &<>&. When an untainted value is wanted, use this option rather than the generic &%condition%& option. -.wen .next .vindex "&$local_part_prefix$&" @@ -1442,7 +1432,6 @@ 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. @@ -1451,7 +1440,6 @@ 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 @@ -1492,7 +1480,6 @@ 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. @@ -1500,7 +1487,6 @@ 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 @@ -1751,20 +1737,20 @@ 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" @@ -1817,9 +1803,13 @@ the traditional &'ndbm'& interface. .next To complicate things further, there are several very different versions of the Berkeley DB package. Version 1.85 was stable for a very long time, releases -2.&'x'& and 3.&'x'& were current for a while, but the latest versions when Exim last revamped support were numbered 4.&'x'&. -Maintenance of some of the earlier releases has ceased. All versions of -Berkeley DB could be obtained from +2.&'x'& and 3.&'x'& were current for a while, +.new +but the latest versions when Exim last revamped support were numbered 5.&'x'&. +Maintenance of some of the earlier releases has ceased, +and Exim no longer supports versions before 3.&'x'&. +.wen +All versions of Berkeley DB could be obtained from &url(http://www.sleepycat.com/), which is now a redirect to their new owner's page with far newer versions listed. It is probably wise to plan to move your storage configurations away from @@ -1843,6 +1833,9 @@ USE_DB=yes .endd Similarly, for gdbm you set USE_GDBM, and for tdb you set USE_TDB. An error is diagnosed if you set more than one of these. +.new +You can set USE_NDBM if needed to override an operating system default. +.wen At the lowest level, the build-time configuration sets none of these options, thereby assuming an interface of type (1). However, some operating system @@ -1857,7 +1850,11 @@ in one of these lines: .code DBMLIB = -ldb DBMLIB = -ltdb +DBMLIB = -lgdbm -lgdbm_compat .endd +.new +The last of those was for a Linux having GDBM provide emulated NDBM facilities. +.wen Settings like that will work if the DBM library is installed in the standard place. Sometimes it is not, and the library's header file may also not be in the default path. You may need to set INCLUDE to specify where the header @@ -2593,6 +2590,25 @@ 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 @@ -3952,7 +3968,6 @@ 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 @@ -3960,7 +3975,6 @@ 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%&" @@ -3968,14 +3982,12 @@ 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%&" @@ -3986,12 +3998,10 @@ 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%&" @@ -4006,7 +4016,6 @@ 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%&" @@ -4016,7 +4025,6 @@ 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%&" @@ -4538,7 +4546,6 @@ 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" @@ -4557,7 +4564,6 @@ fast ramp-up of queue runner processes .next obtaining a current queue size .endlist -.wen .vitem &%-pd%& .oindex "&%-pd%&" @@ -6651,9 +6657,9 @@ 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 @@ -6665,10 +6671,10 @@ 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, @@ -6752,6 +6758,9 @@ domains = ${lookup{$sender_host_address}lsearch{/some/file}} domains = lsearch;/some/file .endd The first uses a string expansion, the result of which must be a domain list. +.new +The key for an expansion-style lookup must be given explicitly. +.wen No strings have been specified for a successful or a failing lookup; the defaults in this case are the looked-up data and an empty string, respectively. The expansion takes place before the string is processed as a list, and the @@ -6776,6 +6785,12 @@ domain2: Any data that follows the keys is not relevant when checking that the domain matches the list item. +.new +The key for a list-style lookup is implicit, from the lookup context, if +the lookup is a single-key type (see below). +For query-style lookup types the key must be given explicitly. +.wen + It is possible, though no doubt confusing, to use both kinds of lookup at once. Consider a file containing lines like this: .code @@ -6785,7 +6800,6 @@ 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. @@ -6795,7 +6809,6 @@ 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 @@ -6812,7 +6825,7 @@ 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" All single-key lookups support the option &"ret=key"&. @@ -6826,6 +6839,12 @@ version of the lookup key. The &'query-style'& type accepts a generalized database query. No particular key value is assumed by Exim for query-style lookups. You can use whichever Exim variables you need to construct the database query. +.cindex "tainted data" "quoting for lookups" +.new +If tainted data is used in the query then it should be quuted by +using the &*${quote_*&<&'lookup-type'&>&*:*&<&'string'&>&*}*& expansion operator +appropriate for the lookup. +.wen .endlist The code for each lookup type is in a separate source file that is included in @@ -6978,11 +6997,9 @@ 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 @@ -7003,7 +7020,6 @@ is returned. For elements of type string, the returned value is de-quoted. -.new .next .cindex LMDB .cindex lookup lmdb @@ -7021,7 +7037,6 @@ 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 @@ -7423,11 +7438,9 @@ 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. -.new 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. -.wen 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 @@ -8285,7 +8298,6 @@ 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. @@ -8295,7 +8307,6 @@ 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. @@ -8519,10 +8530,8 @@ 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$& variable. @@ -8826,12 +8835,10 @@ other statements in the same ACL. .cindex "tainted data" "de-tainting" The value will be untainted. -.new &*Note*&: If the data result of the lookup (as opposed to the key) is empty, then this empty value is stored in &$domain_data$&. The option to return the key for the lookup, as the value, may be what is wanted. -.wen .next @@ -9618,13 +9625,8 @@ reasons, .cindex "tainted data" definition .cindex expansion "tainted data" and expansion of data deriving from the sender (&"tainted data"&) -.new is not permitted (including acessing a file using a tainted name). -The main config option &%allow_insecure_tainted_data%& can be used as -mitigation during uprades to more secure configurations. -.wen -.new Common ways of obtaining untainted equivalents of variables with tainted values .cindex "tainted data" "de-tainting" @@ -9633,7 +9635,6 @@ This database could be the filesystem structure, or the password file, or accessed via a DBMS. Specific methods are indexed under &"de-tainting"&. -.wen @@ -10346,7 +10347,6 @@ extracted is used. You can use &`fail`& instead of {<&'string3'&>} as in a string extract. -.new .vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*& .cindex quoting "for list" .cindex list quoting @@ -10355,7 +10355,6 @@ 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 "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&& @@ -10592,7 +10591,7 @@ sending the request. Values are &"yes"& (the default) or &"no"& &*tls*& Controls the use of TLS on the connection. Values are &"yes"& or &"no"& (the default). -If it is enabled, a shutdown as descripbed above is never done. +If it is enabled, a shutdown as described above is never done. .endlist @@ -10664,16 +10663,28 @@ expansion items. This item inserts &"raw"& header lines. It is described with the &%header%& expansion item in section &<>& above. -.vitem "&*${run{*&<&'command'&>&*&~*&<&'args'&>&*}{*&<&'string1'&>&*}&&& +.vitem "&*${run <&'options'&> {*&<&'command&~arg&~list'&>&*}{*&<&'string1'&>&*}&&& {*&<&'string2'&>&*}}*&" .cindex "expansion" "running a command" .cindex "&%run%& expansion item" -The command and its arguments are first expanded as one string. The string is -split apart into individual arguments by spaces, and then the command is run +This item runs an external command, as a subprocess. +.new +One option is supported after the word &'run'&, comma-separated. + +If the option &'preexpand'& is not used, +the command string is split into individual arguments by spaces +and then each argument is expanded. +Then the command is run in a separate process, but under the same uid and gid. As in other command executions from Exim, a shell is not used by default. If the command requires a shell, you must explicitly code it. +The command name may not be tainted, but the remaining arguments can be. +If the option &'preexpand'& is used, +.wen +the command and its arguments are first expanded as one string. The result is +split apart into individual arguments by spaces, and then the command is run +as above. Since the arguments are split by spaces, when there is a variable expansion which has an empty result, it will cause the situation that the argument will simply be omitted when the program is actually executed by Exim. If the @@ -10684,6 +10695,9 @@ in a string containing quotes, because it would interfere with the quotes around the command arguments. A possible guard against this is to wrap the variable in the &%sg%& operator to change any quote marks to some other character. +.new +Neither the command nor any argument may be tainted. +.wen The standard input for the command exists, but is empty. The standard output and standard error are set to the same file descriptor. @@ -10796,10 +10810,8 @@ will sort an MX lookup into priority order. -.new .vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*& SRS encoding. See SECT &<>& for details. -.wen @@ -11219,10 +11231,8 @@ 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 &*${local_part:*&<&'string'&>&*}*& @@ -11234,7 +11244,8 @@ empty. The parsing correctly handles SMTPUTF8 Unicode in the string. -.vitem &*${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" @@ -11248,8 +11259,14 @@ the result back to text, with mask appended. For example, .code ${mask:10.111.131.206/28} .endd -returns the string &"10.111.131.192/28"&. Since this operation is expected to -be mostly used for looking up masked addresses in files, the result for an IPv6 +returns the string &"10.111.131.192/28"&. + +Since this operation is expected to +be mostly used for looking up masked addresses in files, the +.new +normal +.wen +result for an IPv6 address uses dots to separate components instead of colons, because colon terminates a key string in lsearch files. So, for example, .code @@ -11259,6 +11276,10 @@ returns the string .code 3ffe.ffff.836f.0a00.000a.0800.2000.0000/99 .endd +.new +If the optional form &*mask_n*& is used, IPv6 address result are instead +returned in normailsed form, using colons and with zero-compression. +.wen Letters in IPv6 addresses are always output in lower case. @@ -11785,11 +11806,9 @@ 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" @@ -11876,10 +11895,8 @@ 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'&>&*}*& &&& @@ -11900,6 +11917,19 @@ ${if inlisti{Needle}{fOo:NeeDLE:bAr}} ${if forany{fOo:NeeDLE:bAr}{eqi{$item}{Needle}}} .endd +.new +The variable &$value$& will be set for a successful match and can be +used in the success clause of an &%if%& expansion item using the condition. +.cindex "tainted data" "de-tainting" +It will have the same taint status as the list; expansions such as +.code +${if inlist {$h_mycode:} {0 : 1 : 42} {$value}} +.endd +can be used for de-tainting. +Any previous &$value$& is restored after the if. +.wen + + .vitem &*isip&~{*&<&'string'&>&*}*& &&& &*isip4&~{*&<&'string'&>&*}*& &&& &*isip6&~{*&<&'string'&>&*}*& @@ -12096,6 +12126,18 @@ item can be used, as in all address lists, to cause subsequent items to have their local parts matched casefully. Domains are always matched caselessly. +.new +The variable &$value$& will be set for a successful match and can be +used in the success clause of an &%if%& expansion item using the condition. +.cindex "tainted data" "de-tainting" +It will have the same taint status as the list; expansions such as +.code +${if match_local_part {$local_part} {alice : bill : charlotte : dave} {$value}} +.endd +can be used for de-tainting. +Any previous &$value$& is restored after the if. +.wen + Note that <&'string2'&> is not itself subject to string expansion, unless Exim was built with the EXPAND_LISTMATCH_RHS option. @@ -12112,8 +12154,9 @@ 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 @@ -12347,9 +12390,7 @@ 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. -.new &*Note*&: The variable is cleared at the end of processing the ACL verb. -.wen .vitem &$address_data$& .vindex "&$address_data$&" @@ -12653,14 +12694,12 @@ 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 @@ -12812,7 +12851,7 @@ a unique name for the file. &$interface_port$& .vindex "&$interface_address$&" .vindex "&$interface_port$&" -These are ebsolete names for &$received_ip_address$& and &$received_port$&. +These are obsolete names for &$received_ip_address$& and &$received_port$&. .vitem &$item$& .vindex "&$item$&" @@ -12901,12 +12940,10 @@ 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. @@ -13980,14 +14017,12 @@ 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 &$tls_in_sni$& @@ -14173,9 +14208,7 @@ 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" @@ -14612,7 +14645,6 @@ listed in more than one group. .section "Miscellaneous" "SECID96" .table2 .row &%add_environment%& "environment variables" -.row &%allow_insecure_tainted_data%& "turn taint errors into warnings" .row &%bi_command%& "to run for &%-bi%& command line option" .row &%debug_store%& "do extra internal checks" .row &%disable_ipv6%& "do no IPv6 processing" @@ -15226,19 +15258,6 @@ 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. -.new -.option allow_insecure_tainted_data main boolean false -.cindex "de-tainting" -.oindex "allow_insecure_tainted_data" -The handling of tainted data may break older (pre 4.94) configurations. -Setting this option to "true" turns taint errors (which result in a temporary -message rejection) into warnings. This option is meant as mitigation only -and deprecated already today. Future releases of Exim may ignore it. -The &%taint%& log selector can be used to suppress even the warnings. -.wen - - - .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 @@ -15899,8 +15918,8 @@ 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. @@ -16342,7 +16361,6 @@ hosts_connection_nolog = : If the &%smtp_connection%& log selector is not set, this option has no effect. -.new .option hosts_require_alpn main "host list&!!" unset .cindex ALPN "require negotiation in server" .cindex TLS ALPN @@ -16354,7 +16372,6 @@ 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. -.wen .option hosts_proxy main "host list&!!" unset @@ -16893,14 +16910,11 @@ 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. @@ -17098,9 +17112,7 @@ 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 .option prdr_enable main boolean false @@ -17181,12 +17193,10 @@ 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" @@ -17224,7 +17234,6 @@ 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 .cindex "queue runner" "two phase" .cindex "queue" "double scanning" @@ -17232,7 +17241,6 @@ 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 @@ -17672,11 +17680,9 @@ 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 @@ -18382,7 +18388,6 @@ using the &%tls_certificate%& option. If TLS support for incoming connections is not required the &%tls_advertise_hosts%& option should be set empty. -.new .option tls_alpn main "string list&!!" "smtp : esmtp" .cindex TLS "Application Layer Protocol Names" .cindex TLS ALPN @@ -18392,7 +18397,6 @@ 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. -.wen .option tls_certificate main "string list&!!" unset @@ -18425,11 +18429,9 @@ 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" @@ -18472,12 +18474,7 @@ 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. @@ -18528,8 +18525,17 @@ of the later IKE values, which led into RFC7919 providing new fixed constants (the "ffdhe" identifiers). At this point, all of the "ike" values should be considered obsolete; -they're still in Exim to avoid breaking unusual configurations, but are +they are still in Exim to avoid breaking unusual configurations, but are candidates for removal the next time we have backwards-incompatible changes. +.new +Two of them in particular (&`ike1`& and &`ike22`&) are called out by RFC 8247 +as MUST NOT use for IPSEC, and two more (&`ike23`& and &`ike24`&) as +SHOULD NOT. +Because of this, Exim regards them as deprecated; if either of the first pair +are used, warnings will be logged in the paniclog, and if any are used then +warnings will be logged in the mainlog. +All four will be removed in a future Exim release. +.wen The TLS protocol does not negotiate an acceptable size for this; clients tend to hard-drop connections if what is offered by the server is unacceptable, @@ -18640,12 +18646,10 @@ 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 @@ -18704,7 +18708,8 @@ 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. @@ -18877,11 +18882,9 @@ 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 @@ -19873,10 +19876,8 @@ 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) @@ -22425,11 +22426,9 @@ 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: @@ -22500,13 +22499,11 @@ 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. -.new &*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. -.wen .option event_action transports string&!! unset @@ -23266,10 +23263,8 @@ 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 @@ -23282,7 +23277,6 @@ 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. @@ -23292,7 +23286,6 @@ checking is done in "belowhome" mode. .cindex "tainted data" "de-tainting" If "belowhome" checking is used, the file or directory path becomes de-tainted. -.wen .option directory appendfile string&!! unset @@ -23306,10 +23299,8 @@ 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" @@ -23343,10 +23334,8 @@ 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" @@ -25703,7 +25692,6 @@ 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. -.new .option hosts_require_alpn smtp "host list&!!" unset .cindex ALPN "require negotiation in client" .cindex TLS ALPN @@ -25715,7 +25703,6 @@ See also the &%tls_alpn%& option. &*Note*&: prevention of fallback to in-clear connection is not managed by this option; see &%hosts_require_tls%&. -.wen .option hosts_require_dane smtp "host list&!!" unset .cindex DANE "transport options" @@ -25750,9 +25737,7 @@ 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. @@ -25768,13 +25753,11 @@ 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 &<>&. @@ -25863,7 +25846,6 @@ 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 @@ -25874,7 +25856,6 @@ 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 @@ -25890,11 +25871,9 @@ 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" @@ -26000,7 +25979,6 @@ This option enables use of SOCKS proxies for connections made by the transport. For details see section &<>&. -.new .option tls_alpn smtp string&!! unset .cindex TLS "Application Layer Protocol Names" .cindex TLS ALPN @@ -26011,7 +25989,6 @@ the value given is used. As of writing no value has been standardised for email use. The authors suggest using &"smtp"&. -.wen @@ -26079,12 +26056,10 @@ 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 @@ -26094,9 +26069,7 @@ 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 @@ -26191,6 +26164,10 @@ 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" @@ -27309,11 +27286,9 @@ 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 @@ -28058,10 +28033,8 @@ 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 @@ -28388,11 +28361,9 @@ 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 @@ -28415,10 +28386,8 @@ 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 @@ -28430,7 +28399,6 @@ 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$& with the salt. @@ -28447,7 +28415,6 @@ If the authentication succeeds then the above variables are set, plus the calculated salted password value value in &$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 @@ -28474,12 +28441,10 @@ 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" @@ -29152,12 +29117,10 @@ 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 @@ -29631,7 +29594,6 @@ 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 @@ -29683,7 +29645,6 @@ 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 @@ -29755,13 +29716,11 @@ 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: @@ -29809,7 +29768,6 @@ outgoing connection. -.new .section "Caching of static client configuration items" "SECTclientTLScache" .cindex certificate caching .cindex privatekey caching @@ -29860,7 +29818,6 @@ 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 @@ -29900,10 +29857,8 @@ nothing more to it. Choosing a sensible value not derived insecurely is the only point of caution. The &$tls_out_sni$& variable will be set to this string for the lifetime of the client connection (including during authentication). -.new If DANE validated the connection attempt then the value of the &%tls_sni%& option is forced to the domain part of the recipient address. -.wen Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string received from a client. @@ -29945,7 +29900,6 @@ When Exim is built against GnuTLS, SNI support is available as of GnuTLS 0.5.10. (Its presence predates the current API which Exim uses, so if Exim built, then you have SNI support). -.new .cindex TLS ALPN .cindex ALPN "general information" .cindex TLS "Application Layer Protocol Names" @@ -29972,7 +29926,6 @@ depends on the behavious of the peer This feature is available when Exim is built with OpenSSL 1.1.0 or later or GnuTLS 3.2.0 or later; the macro _HAVE_TLS_ALPN will be defined when this is so. -.wen @@ -30120,7 +30073,6 @@ Open-source PKI book, available online at .ecindex IIDencsmtp2 -.new .section "TLS Resumption" "SECTresumption" .cindex TLS resumption TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined @@ -30212,7 +30164,6 @@ Issues: .endlist .endlist -.wen .section DANE "SECDANE" @@ -30562,6 +30513,11 @@ accepted by an &%accept%& verb that has a &%message%& modifier, the contents of the message override the banner message that is otherwise specified by the &%smtp_banner%& option. +.new +For tls-on-connect connections, the ACL is run after the TLS connection +is accepted (however, &%host_reject_connection%& is tested before). +.wen + .section "The EHLO/HELO ACL" "SECID192" .cindex "EHLO" "ACL for" @@ -31490,11 +31446,9 @@ anyway. If the message contains newlines, this gives rise to a multi-line SMTP response. .vindex "&$acl_verify_message$&" -.new While the text is being expanded, the &$acl_verify_message$& variable contains any message previously set. Afterwards, &$acl_verify_message$& is cleared. -.wen If &%message%& is used on a statement that verifies an address, the message specified overrides any message that is generated by the verification process. @@ -31681,12 +31635,43 @@ sender when the destination system is doing content-scan based rejection. This control turns on debug logging, almost as though Exim had been invoked with &`-d`&, with the output going to a new logfile in the usual logs directory, by default called &'debuglog'&. -The filename can be adjusted with the &'tag'& option, which -may access any variables already defined. The logging may be adjusted with -the &'opts'& option, which takes the same values as the &`-d`& command-line -option. -Logging started this way may be stopped, and the file removed, -with the &'kill'& option. + +.new +Options are a slash-separated list. +If an option takes an argument, the option name and argument are separated by +an equals character. +Several options are supported: +.wen +.display +tag=<&'suffix'&> The filename can be adjusted with thise option. + The argument, which may access any variables already defined, + is appended to the default name. + +opts=<&'debug&~options'&> The argument specififes what is to be logged, + using the same values as the &`-d`& command-line option. + +stop Logging started with this control may be + stopped by using this option. + +kill Logging started with this control may be + stopped by using this option. + Additionally the debug file will be removed, + providing one means for speculative debug tracing. + +pretrigger=<&'size'&> This option specifies a memory buffuer to be used + for pre-trigger debug capture. + Debug lines are recorded in the buffer until + and if) a trigger occurs; at which time they are + dumped to the debug file. Newer lines displace the + oldest if the buffer is full. After a trigger, + immediate writes to file are done as normal. + +trigger=<&'reason'&> This option selects cause for the pretrigger buffer + see above) to be copied to file. A reason of $*now* + take effect immediately; one of &*paniclog*& triggers + on a write to the panic log. +.endd + Some examples (which depend on variables that don't exist in all contexts): .code @@ -31695,6 +31680,8 @@ contexts): control = debug/opts=+expand+acl control = debug/tag=.$message_exim_id/opts=+expand control = debug/kill + control = debug/opts=+all/pretrigger=1024/trigger=paniclog + control = debug/trigger=now .endd @@ -32325,6 +32312,14 @@ content-scanning extension, and is available only in the DATA, MIME, and non-SMTP ACLs. It causes the incoming message to be scanned for a match with any of the regular expressions. For details, see chapter &<>&. +.new +.vitem &*seen&~=&~*&<&'parameters'&> +.cindex "&%sseen%& ACL condition" +This condition can be used to test if a situation has been previously met, +for example for greylisting. +Details are given in section &<>&. +.wen + .vitem &*sender_domains&~=&~*&<&'domain&~list'&> .cindex "&%sender_domains%& ACL condition" .cindex "sender" "ACL checking" @@ -32749,12 +32744,10 @@ 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" @@ -33049,6 +33042,59 @@ address you should specify alternate list separators for both the outer dnslists = <; dnsbl.example.com/<|$acl_m_addrslist .endd + +.new +.section "Previously seen user and hosts" "SECTseen" +.cindex "&%sseen%& ACL condition" +.cindex greylisting +The &%seen%& ACL condition can be used to test whether a +situation has been previously met. +It uses a hints database to record a timestamp against a key. +host. The syntax of the condition is: +.display +&`seen =`& <&'time interval'&> &`/`& <&'options'&> +.endd + +For example, +.code +defer seen = -5m / key=${sender_host_address}_$local_part@$domain +.endd +in a RCPT ACL will implement simple greylisting. + +The parameters for the condition +are an interval followed, slash-separated, by 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"&. + +Creates and updates are marked with the current time. + +Finally, a &"before"& test which succeeds, and for which the record +is old enough, will be refreshed with a timestamp of the test time. +This can prevent tidying of the database from removing the entry. +The interval for this is, by default, 10 days. +An explicit interval can be set using a +&%refresh=value%& option. + +Note that &"seen"& should be added to the list of hints databases +for maintenance if this ACL condition is used. +.wen + + .section "Rate limiting incoming messages" "SECTratelimiting" .cindex "rate limiting" "client sending" .cindex "limiting client sending rates" @@ -33354,7 +33400,6 @@ 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 @@ -33362,7 +33407,6 @@ 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" @@ -33397,7 +33441,6 @@ 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 @@ -33729,7 +33772,6 @@ behaviour will be the same. -.new .section "Quota caching" "SECTquotacache" .cindex "hints database" "quota cache" .cindex "quota" "cache, description of" @@ -33759,7 +33801,6 @@ 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" @@ -35322,8 +35363,10 @@ discussed below. .vitem &*header_line&~*header_last*& A pointer to the last of the header lines. -.vitem &*uschar&~*headers_charset*& +.new +.vitem &*const&~uschar&~*headers_charset*& The value of the &%headers_charset%& configuration option. +.wen .vitem &*BOOL&~host_checking*& This variable is TRUE during a host checking session that is initiated by the @@ -38629,9 +38672,7 @@ 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 @@ -38884,7 +38925,6 @@ selection marked by asterisks: &` smtp_protocol_error `& SMTP protocol errors &` smtp_syntax_error `& SMTP syntax errors &` subject `& contents of &'Subject:'& on <= lines -&`*taint `& taint errors or warnings &`*tls_certificate_verified `& certificate verification status &`*tls_cipher `& TLS cipher suite on <= and => lines &` tls_peerdn `& TLS peer DN on <= and => lines @@ -39011,9 +39051,7 @@ 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" @@ -39280,11 +39318,6 @@ using a CA trust anchor, &`CV=dane`& if using a DNS trust anchor, and &`CV=no`& if not. .next -.cindex "log" "Taint warnings" -&%taint%&: Log warnings about tainted data. This selector can't be -turned of if &%allow_insecure_tainted_data%& is false (which is the -default). -.next .cindex "log" "TLS cipher" .cindex "TLS" "logging cipher" &%tls_cipher%&: When a message is sent or received over an encrypted @@ -39298,11 +39331,9 @@ 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" @@ -39431,9 +39462,6 @@ 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: @@ -39490,7 +39518,22 @@ Display messages in reverse order. Include delivered recipients in queue listing. .endlist +The following options give alternates for configuration: + +.vlist +.vitem &*-C*&&~<&'config&~file'&> +is used to specify an alternate &_exim.conf_& which might +contain alternate exim configuration the queue management might be using. + +.vitem &*-E*&&~<&'path'&> +can be used to specify a path for the exim binary, +overriding the built-in one. +.endlist + There is one more option, &%-h%&, which outputs a list of options. +.new +At least one selection option, or either the &*-c*& or &*-h*& option, must be given. +.wen @@ -39850,9 +39893,7 @@ 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 @@ -39874,12 +39915,18 @@ 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, +.new +taking as arguments the spool and database names. +An option &'-z'& may be given to regest times in UTC; +otherwise times are in the local timezone. +.wen +For example, to dump the retry database: .code exim_dumpdb /var/spool/exim retry .endd -Two lines of output are produced for each entry: +For the retry database +two lines of output are produced for each entry: .code T:mail.ref.example:192.168.242.242 146 77 Connection refused 31-Oct-1995 12:00:12 02-Nov-1995 12:21:39 02-Nov-1995 20:21:39 * @@ -39961,7 +40008,7 @@ 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. @@ -39978,6 +40025,12 @@ resets the time of the next delivery attempt. Time values are given as a sequence of digit pairs for year, month, day, hour, and minute. Colons can be used as optional separators. +.new +Both displayed and input times are in the local timezone by default. +If an option &'-z'& is used on the command line, displayed times +are in UTC. +.wen + @@ -40748,7 +40801,7 @@ 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: @@ -40758,7 +40811,7 @@ 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 @@ -40999,8 +41052,18 @@ was received, in the conventional Unix form &-- the number of seconds since the start of the epoch. The second number is a count of the number of messages warning of delayed delivery that have been sent to the sender. -There follow a number of lines starting with a hyphen. These can appear in any -order, and are omitted when not relevant: +.new +There follow a number of lines starting with a hyphen. +These contain variables, can appear in any +order, and are omitted when not relevant. + +If there is a second hyphen after the first, +the corresponding data is tainted. +If there is a value in parentheses, the data is quoted for a lookup. + +The following word specifies a variable, +and the remainder of the item depends on the variable. +.wen .vlist .vitem "&%-acl%&&~<&'number'&>&~<&'length'&>" @@ -41156,9 +41219,6 @@ 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%& @@ -41362,14 +41422,12 @@ 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. @@ -41979,7 +42037,6 @@ 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 @@ -42074,7 +42131,6 @@ Example usage: .endd -.wen @@ -42643,6 +42699,7 @@ Events have names which correspond to the point in process at which they fire. 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. +.new The current list of events is: .display &`dane:fail after transport `& per connection @@ -42657,9 +42714,11 @@ The current list of events is: &`tcp:connect before transport `& per connection &`tcp:close after transport `& per connection &`tls:cert before both `& per certificate in verification chain +&`tls:fail:connect after main `& per connection &`smtp:connect after transport `& per connection &`smtp:ehlo after transport `& per connection .endd +.wen New event types may be added in future. The event name is a colon-separated list, defining the type of @@ -42685,6 +42744,7 @@ with the event type: &`msg:rcpt:host:defer `& error string &`msg:rcpt:defer `& error string &`tls:cert `& verification chain depth +&`tls:fail:connect `& error string &`smtp:connect `& smtp banner &`smtp:ehlo `& smtp ehlo response .endd