X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/0694f91e89112483d7ffb8312471b132c2acce77..d6870e76cf0b838eab1929e5d5afb486c4e7b448:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index c865e111b..edba1232f 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -161,6 +161,13 @@ .macro index .echo "** Don't use .index; use .cindex or .oindex or .vindex" .endmacro + + +. use this for a concept-index entry for a header line +.macro chindex +.cindex "&'$1'& header line" +.cindex "header lines" $1 +.endmacro . //////////////////////////////////////////////////////////////////////////// @@ -193,6 +200,8 @@ . This chunk of literal XML implements index entries of the form "x, see y" and . "x, see also y". However, the DocBook DTD doesn't allow entries . at the top level, so we have to put the .chapter directive first. + +. These do not turn up in the HTML output, unfortunately. The PDF does get them. . ///////////////////////////////////////////////////////////////////////////// .chapter "Introduction" "CHID1" @@ -318,6 +327,10 @@ zero, binary binary zero + + headers + header lines + .literal off @@ -1394,9 +1407,22 @@ Again, cutthrough delivery counts as a verification. .next Individual routers can be explicitly skipped when running the routers to check an address given in the SMTP EXPN command (see the &%expn%& option). + .next If the &%domains%& option is set, the domain of the address must be in the set of domains that it defines. +.new +.cindex "tainted data" "de-tainting" +A match verifies the variable &$domain$& (which carries tainted data) +and assigns an untainted value to the &$domain_data$& variable. +Such an untainted value is often needed in the transport. +For specifics of the matching operation and the resulting untainted value, +refer to section &<>&. + +When an untainted value is wanted, use this option +rather than the generic &%condition%& option. +.wen + .next .vindex "&$local_part_prefix$&" .vindex "&$local_part_prefix_v$&" @@ -1405,13 +1431,26 @@ of domains that it defines. .vindex "&$local_part_suffix_v$&" .cindex affix "router precondition" If the &%local_parts%& option is set, the local part of the address must be in -the set of local parts that it defines. If &%local_part_prefix%& or +the set of local parts that it defines. +.new +A match verifies the variable &$local_part$& (which carries tainted data) +and assigns an untainted value to the &$local_part_data$& variable. +Such an untainted value is often needed in the transport. +For specifics of the matching operation and the resulting untainted value, +refer to section &<>&. + +When an untainted value is wanted, use this option +rather than the generic &%condition%& option. +.wen + +If &%local_part_prefix%& or &%local_part_suffix%& is in use, the prefix or suffix is removed from the local part before this check. If you want to do precondition tests on local parts that include affixes, you can do so by using a &%condition%& option (see below) that uses the variables &$local_part$&, &$local_part_prefix$&, &$local_part_prefix_v$&, &$local_part_suffix$& and &$local_part_suffix_v$& as necessary. + .next .vindex "&$local_user_uid$&" .vindex "&$local_user_gid$&" @@ -1421,23 +1460,37 @@ an account on the local host. If this check succeeds, the uid and gid of the local user are placed in &$local_user_uid$& and &$local_user_gid$& and the user's home directory is placed in &$home$&; these values can be used in the remaining preconditions. + .next If the &%router_home_directory%& option is set, it is expanded at this point, because it overrides the value of &$home$&. If this expansion were left till later, the value of &$home$& as set by &%check_local_user%& would be used in subsequent tests. Having two different values of &$home$& in the same router could lead to confusion. + .next If the &%senders%& option is set, the envelope sender address must be in the set of addresses that it defines. + .next If the &%require_files%& option is set, the existence or non-existence of specified files is tested. + .next .cindex "customizing" "precondition" If the &%condition%& option is set, it is evaluated and tested. This option uses an expanded string to allow you to set up your own custom preconditions. Expanded strings are described in chapter &<>&. + +.new +Note that while using +this option for address matching technically works, +it does not set any de-tainted values. +Such values are often needed, either for router-specific options or +for transport options. +Using the &%domains%& and &%local_parts%& options is usually the most +convenient way to obtain them. +.wen .endlist @@ -2643,10 +2696,8 @@ Exim through the local interface (see the &%-bm%& and &%-f%& options below). See the &%untrusted_set_sender%& option for a way of permitting non-trusted users to set envelope senders. -.cindex "&'From:'& header line" -.cindex "&'Sender:'& header line" -.cindex "header lines" "From:" -.cindex "header lines" "Sender:" +.chindex From: +.chindex Sender: For a trusted user, there is never any check on the contents of the &'From:'& header line, and a &'Sender:'& line is never added. Furthermore, any existing &'Sender:'& line in incoming local (non-TCP/IP) messages is not removed. @@ -3845,7 +3896,9 @@ id, and the remaining ones must be email addresses. However, if the message is active (in the middle of a delivery attempt), it is not altered. This option can be used only by an admin user. -.vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&~<&'sequence&~number'&>&&& +.vitem "&%-MC%&&~<&'transport'&>&~<&'hostname'&>&&& + &~<&'host&~IP'&>&&& + &~<&'sequence&~number'&>&&& &~<&'message&~id'&>" .oindex "&%-MC%&" .cindex "SMTP" "passed connection" @@ -4742,9 +4795,9 @@ recognized when Exim is run normally. It allows for the setting up of explicit .vitem &%-t%& .oindex "&%-t%&" .cindex "recipient" "extracting from header lines" -.cindex "&'Bcc:'& header line" -.cindex "&'Cc:'& header line" -.cindex "&'To:'& header line" +.chindex Bcc: +.chindex Cc: +.chindex To: When Exim is receiving a locally-generated, non-SMTP message on its standard input, the &%-t%& option causes the recipients of the message to be obtained from the &'To:'&, &'Cc:'&, and &'Bcc:'& header lines in the message instead of @@ -8428,7 +8481,10 @@ 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$& variable. @@ -9513,7 +9569,9 @@ reasons, .cindex "tainted data" definition .cindex expansion "tainted data" and expansion of data deriving from the sender (&"tainted data"&) -is not permitted. +.new +is not permitted (including acessing a file using a tainted name). +.wen .new Common ways of obtaining untainted equivalents of variables with @@ -9671,7 +9729,7 @@ If the ACL returns defer the result is a forced-fail. Otherwise the expansion f .vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&" .cindex authentication "results header" -.cindex headers "authentication-results:" +.chindex Authentication-Results: .cindex authentication "expansion item" This item returns a string suitable for insertion as an &'Authentication-Results:'& @@ -10102,7 +10160,7 @@ newline at the very end. For the &%header%& and &%bheader%& expansion, for those headers that contain lists of addresses, a comma is also inserted at the junctions between headers. This does not happen for the &%rheader%& expansion. -.cindex "tainted data" +.cindex "tainted data" "message headers" When the headers are from an incoming message, the result of expanding any of these variables is tainted. @@ -11674,6 +11732,7 @@ 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*& @@ -12279,7 +12338,7 @@ to the relevant file. When, as a result of aliasing or forwarding, a message is directed to a pipe, this variable holds the pipe command when the transport is running. -.vitem "&$auth1$& &-- &$auth3$&" +.vitem "&$auth1$& &-- &$auth4$&" .vindex "&$auth1$&, &$auth2$&, etc" These variables are used in SMTP authenticators (see chapters &<>&&--&<>&). Elsewhere, they are empty. @@ -13658,7 +13717,11 @@ filter file to set values that can be tested in users' filter files. For example, a system filter could set a value indicating how likely it is that a message is junk mail. -.vitem &$spam_$&&'xxx'& +.vitem &$spam_score$& &&& + &$spam_score_int$& &&& + &$spam_bar$& &&& + &$spam_report$& &&& + &$spam_action$& A number of variables whose names start with &$spam$& are available when Exim is compiled with the content-scanning extension. For details, see section &<>&. @@ -14048,6 +14111,10 @@ 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" When the configuration file includes a &%perl_startup%& option you can make use @@ -16928,7 +16995,7 @@ not count as protocol errors (see &%smtp_max_synprot_errors%&). .option pipelining_connect_advertise_hosts main "host list&!!" * .cindex "pipelining" "early connection" .cindex "pipelining" PIPE_CONNECT -.cindex "ESMTP extensions" X_PIPE_CONNECT +.cindex "ESMTP extensions" PIPE_CONNECT If Exim is built with the SUPPORT_PIPE_CONNECT build option this option controls which hosts the facility is advertised to and from which pipeline early-connection (before MAIL) SMTP @@ -16937,7 +17004,9 @@ When used, the pipelining saves on roundtrip times. See also the &%hosts_pipe_connect%& smtp transport option. -Currently the option name &"X_PIPE_CONNECT"& is used. +.new +The SMTP service extension keyword advertised is &"PIPE_CONNECT"&. +.wen .option prdr_enable main boolean false @@ -18810,7 +18879,10 @@ address (with affixes removed if relevant) is the name of an account on the local system. The check is done by calling the &[getpwnam()]& function rather than trying to read &_/etc/passwd_& directly. This means that other methods of holding password data (such as NIS) are supported. If the local part is a local -user, &$home$& is set from the password data, and can be tested in other +user, +.cindex "tainted data" "de-tainting" +&$local_part_data$& is set to an untainted version of the local part and +&$home$& is set from the password data. The latter can be tested in other preconditions that are evaluated after this one (the order of evaluation is given in section &<>&). However, the value of &$home$& can be overridden by &%router_home_directory%&. If the local part is not a local user, @@ -18957,7 +19029,8 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence. If this option is set, the router is skipped unless the current domain matches the list. If the match is achieved by means of a file lookup, the data that the lookup returned for the domain is placed in &$domain_data$& for use in string -expansions of the driver's private options. See section &<>& for +expansions of the driver's private options and in the transport. +See section &<>& for a list of the order in which preconditions are evaluated. @@ -19320,12 +19393,13 @@ section &<>& for a discussion of local part lists. Because the string is expanded, it is possible to make it depend on the domain, for example: .code -local_parts = dbm;/usr/local/specials/$domain +local_parts = dbm;/usr/local/specials/$domain_data .endd .vindex "&$local_part_data$&" If the match is achieved by a lookup, the data that the lookup returned for the local part is placed in the variable &$local_part_data$& for use in -expansions of the router's private options. You might use this option, for +expansions of the router's private options or in the transport. +You might use this option, for example, if you have a large number of local virtual domains, and you want to send all postmaster mail to the same place without having to set up an alias in each virtual domain: @@ -19670,6 +19744,10 @@ 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) @@ -22517,7 +22595,7 @@ This defaults to the incoming sender address, but can be changed by setting .option return_path_add transports boolean false -.cindex "&'Return-path:'& header line" +.chindex Return-path: If this option is true, a &'Return-path:'& header is added to the message. Although the return path is normally available in the prefix line of BSD mailboxes, this is commonly not displayed by MUAs, and so the user does not @@ -25045,12 +25123,14 @@ authenticated as a client. .option command_timeout smtp time 5m +.cindex timeout "smtp transport command" This sets a timeout for receiving a response to an SMTP command that has been sent out. It is also used when waiting for the initial banner line from the remote host. Its value must not be zero. .option connect_timeout smtp time 5m +.cindex timeout "smtp transport connect" This sets a timeout for the &[connect()]& function, which sets up a TCP/IP call to a remote host. A setting of zero allows the system timeout (typically several minutes) to act. To have any effect, the value of this option must be @@ -25086,6 +25166,7 @@ be treated as unset and &%tls_require_ciphers%& will be used instead. .option data_timeout smtp time 5m +.cindex timeout "for transmitted SMTP data blocks" This sets a timeout for the transmission of each block in the data portion of the message. As a result, the overall timeout for a message depends on the size of the message. Its value must not be zero. See also &%final_timeout%&. @@ -25224,6 +25305,7 @@ fails"& facility. .option final_timeout smtp time 10m +.cindex timeout "for transmitted SMTP data accept" This is the timeout that applies while waiting for the response to the final line containing just &"."& that terminates a message. Its value must not be zero. @@ -25470,9 +25552,12 @@ incoming messages, use an appropriate ACL. .cindex "authentication" "optional in client" This option provides a list of servers to which, provided they announce authentication support, Exim will attempt to authenticate as a client when it -connects. If authentication fails, Exim will try to transfer the message -unauthenticated. See also &%hosts_require_auth%&, and chapter -&<>& for details of authentication. +connects. If authentication fails +.new +and &%hosts_require_auth%& permits, +.wen +Exim will try to transfer the message unauthenticated. +See also chapter &<>& for details of authentication. .option hosts_try_chunking smtp "host list&!!" * .cindex CHUNKING "enabling, in client" @@ -25648,7 +25733,7 @@ If this option is set to &"smtps"&, the default value for the &%port%& option changes to &"smtps"&, and the transport initiates TLS immediately after connecting, as an outbound SSL-on-connect, instead of using STARTTLS to upgrade. The Internet standards bodies used to strongly discourage use of this mode, -but as of RFC 8314 it is perferred over STARTTLS for message submission +but as of RFC 8314 it is preferred over STARTTLS for message submission (as distinct from MTA-MTA communication). @@ -27301,7 +27386,7 @@ conditions: .ilist The client host must match &%auth_advertise_hosts%& (default *). .next -It the &%server_advertise_condition%& option is set, its expansion must not +If the &%server_advertise_condition%& option is set, its expansion must not yield the empty string, &"0"&, &"no"&, or &"false"&. .endlist @@ -27409,7 +27494,7 @@ encode '\0user@domain.com\0pas$$word' .endd gives an incorrect answer because of the unescaped &"@"& and &"$"& characters. -If you have the &%mimencode%& command installed, another way to do produce +If you have the &%mimencode%& command installed, another way to produce base64-encoded strings is to run the command .code echo -e -n `\0user\0password' | mimencode @@ -27751,7 +27836,14 @@ fixed_plain: client_send = ^username^mysecret .endd The lack of colons means that the entire text is sent with the AUTH -command, with the circumflex characters converted to NULs. A similar example +command, with the circumflex characters converted to NULs. +.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 that uses the LOGIN mechanism is: .code fixed_login: @@ -28075,6 +28167,12 @@ 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 This option can be used to supply an &'authorization id'& @@ -28094,21 +28192,44 @@ the password to be used, in clear. This option is exapanded before use, and should result in 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 it is used in preference to &%client_password%&. The value after expansion should be a 40 (for SHA-1) or 64 (for SHA-256) character string with the PBKDF2-prepared password, hex-encoded. + Note that this value will depend on the salt and iteration-count supplied by the server. - +The option is expanded before use. +.new +During the expansion &$auth1$& is set with the client username, +&$auth2$& with the iteration count, and +&$auth3$& with the salt. + +The intent of this option +is to support clients that can cache thes salted password +to save on recalculation costs. +The cache lookup should return an unusable value +(eg. an empty string) +if the salt or iteration count has changed + +If the authentication succeeds then the above variables are set, +.vindex "&$auth4$&" +plus the calculated salted password value value in &$auth4$&, +during the expansion of the &%client_set_id%& option. +A side-effect of this expansion can be used to prime the cache. +.wen .option server_channelbinding gsasl boolean false -Do not set this true and rely on the properties -without consulting a cryptographic engineer. - Some authentication mechanisms are able to use external context at both ends of the session to bind the authentication to that context, and fail the authentication process if that context differs. Specifically, some TLS @@ -28128,9 +28249,16 @@ This defaults off to ensure smooth upgrade across Exim releases, in case this option causes some clients to start failing. Some future release of Exim might have switched the default to be true. -However, Channel Binding in TLS has proven to be vulnerable in current versions. -Do not plan to rely upon this feature for security, ever, without consulting -with a subject matter expert (a cryptographic engineer). +. However, Channel Binding in TLS has proven to be vulnerable in current versions. +. Do not plan to rely upon this feature for security, ever, without consulting +. with a subject matter expert (a cryptographic engineer). + +.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" @@ -35946,8 +36074,7 @@ incoming SMTP message from a source that is not permitted to send them. .section "Resent- header lines" "SECID220" -.cindex "&%Resent-%& header lines" -.cindex "header lines" "Resent-" +.chindex Resent- RFC 2822 makes provision for sets of header lines starting with the string &`Resent-`& to be added to a message when it is resent by the original recipient to somebody else. These headers are &'Resent-Date:'&, @@ -36003,8 +36130,7 @@ existing &'Bcc:'& is not removed. .section "The Date: header line" "SECID223" -.cindex "&'Date:'& header line" -.cindex "header lines" "Date:" +.cindex Date: If a locally-generated or submission-mode message has no &'Date:'& header line, Exim adds one, using the current date and time, unless the &%suppress_local_fixups%& control has been specified. @@ -36021,8 +36147,7 @@ messages. .section "The Envelope-to: header line" "SECID225" -.cindex "&'Envelope-to:'& header line" -.cindex "header lines" "Envelope-to:" +.chindex Envelope-to: .oindex "&%envelope_to_remove%&" &'Envelope-to:'& header lines are not part of the standard RFC 2822 header set. Exim can be configured to add them to the final delivery of messages. (See the @@ -36033,8 +36158,7 @@ messages. .section "The From: header line" "SECTthefrohea" -.cindex "&'From:'& header line" -.cindex "header lines" "From:" +.chindex From: .cindex "Sendmail compatibility" "&""From""& line" .cindex "message" "submission" .cindex "submission mode" @@ -36077,8 +36201,7 @@ name as described in section &<>&. .section "The Message-ID: header line" "SECID226" -.cindex "&'Message-ID:'& header line" -.cindex "header lines" "Message-ID:" +.chindex Message-ID: .cindex "message" "submission" .oindex "&%message_id_header_text%&" If a locally-generated or submission-mode incoming message does not contain a @@ -36093,8 +36216,7 @@ in this header line by setting the &%message_id_header_text%& and/or .section "The Received: header line" "SECID227" -.cindex "&'Received:'& header line" -.cindex "header lines" "Received:" +.chindex Received: A &'Received:'& header line is added at the start of every message. The contents are defined by the &%received_header_text%& configuration option, and Exim automatically adds a semicolon and a timestamp to the configured string. @@ -36110,8 +36232,7 @@ changed to the time of acceptance, which is (apart from a small delay while the .section "The References: header line" "SECID228" -.cindex "&'References:'& header line" -.cindex "header lines" "References:" +.chindex References: Messages created by the &(autoreply)& transport include a &'References:'& header line. This is constructed according to the rules that are described in section 3.64 of RFC 2822 (which states that replies should contain such a @@ -36125,8 +36246,7 @@ incoming message. If there are more than 12, the first one and then the final .section "The Return-path: header line" "SECID229" -.cindex "&'Return-path:'& header line" -.cindex "header lines" "Return-path:" +.chindex Return-path: .oindex "&%return_path_remove%&" &'Return-path:'& header lines are defined as something an MTA may insert when it does the final delivery of messages. (See the generic &%return_path_add%& @@ -36139,7 +36259,7 @@ default), Exim removes &'Return-path:'& header lines from incoming messages. .section "The Sender: header line" "SECTthesenhea" .cindex "&'Sender:'& header line" .cindex "message" "submission" -.cindex "header lines" "Sender:" +.chindex Sender: For a locally-originated message from an untrusted user, Exim may remove an existing &'Sender:'& header line, and it may add a new one. You can modify these actions by setting the &%local_sender_retain%& option true, the @@ -38239,8 +38359,11 @@ parentheses afterwards. When more than one address is included in a single delivery (for example, two SMTP RCPT commands in one transaction) the second and subsequent addresses are flagged with &`->`& instead of &`=>`&. When two or more messages are delivered -down a single SMTP connection, an asterisk follows the IP address in the log -lines for the second and subsequent messages. +down a single SMTP connection, an asterisk follows the +.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 will not be present in the log lines for the second and subsequent messages. @@ -38607,6 +38730,7 @@ routing email addresses, but it does apply to &"byname"& lookups. client's ident port times out. .next .cindex "log" "incoming interface" +.cindex "log" "outgoing interface" .cindex "log" "local interface" .cindex "log" "local address and port" .cindex "TCP/IP" "logging local address and port" @@ -38615,7 +38739,10 @@ client's ident port times out. to the &"<="& line as an IP address in square brackets, tagged by I= and followed by a colon and the port number. The local interface and port are also added to other SMTP log lines, for example, &"SMTP connection from"&, to -rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines. +rejection lines, and (despite the name) to outgoing +.new +&"=>"&, &"->"&, &"=="& and &"**"& lines. +.wen The latter can be disabled by turning off the &%outgoing_interface%& option. .next .cindex log "incoming proxy address"