X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/2081aac24b67f3f3f34389aadc06354abcad0cad..20395676aba7fa5eb9a2c5e0b9f582ec2b3e71e4:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 5c42afc93..05d8e6ed1 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -51,6 +51,8 @@ .set ACL "access control lists (ACLs)" .set I "    " +.set drivernamemax "64" + .macro copyyear 2020 .endmacro @@ -237,6 +239,14 @@ failure report bounce message + + de-tainting + tainting, de-tainting + + + detainting + tainting, de-tainting + dialup intermittently connected hosts @@ -3848,9 +3858,11 @@ headers.) .cindex "Solaris" "&'mail'& command" .cindex "dot" "in incoming non-SMTP message" This option, which has the same effect as &%-oi%&, specifies that a dot on a -line by itself should not terminate an incoming, non-SMTP message. I can find -no documentation for this option in Solaris 2.4 Sendmail, but the &'mailx'& -command in Solaris 2.4 uses it. See also &%-ti%&. +line by itself should not terminate an incoming, non-SMTP message. +Solaris 2.4 (SunOS 5.4) Sendmail has a similar &%-i%& processing option +&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf), +p. 1M-529), and therefore a &%-oi%& command line option, which both are used +by its &'mailx'& command. .vitem &%-L%&&~<&'tag'&> .oindex "&%-L%&" @@ -3940,6 +3952,16 @@ 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 +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%&" This option is not intended for use by external callers. It is used internally @@ -4160,8 +4182,9 @@ the standard output. This option can be used only by an admin user. .vitem &%-m%& .oindex "&%-m%&" -This is apparently a synonym for &%-om%& that is accepted by Sendmail, so Exim -treats it that way too. +This is a synonym for &%-om%& that is accepted by Sendmail +(&url(https://docs.oracle.com/cd/E19457-01/801-6680-1M/801-6680-1M.pdf) +p. 1M-258), so Exim treats it that way too. .vitem &%-N%& .oindex "&%-N%&" @@ -5958,7 +5981,7 @@ Libraries you use may depend on specific environment settings. This imposes a security risk (e.g. PATH). There are two lists: &%keep_environment%& for the variables to import as they are, and &%add_environment%& for variables we want to set to a fixed value. -Note that TZ is handled separately, by the $%timezone%$ runtime +Note that TZ is handled separately, by the &%timezone%& runtime option and by the TIMEZONE_DEFAULT buildtime option. .code # keep_environment = ^LDAP @@ -8492,7 +8515,7 @@ 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 +will store a result in the &$domain_data$& variable. .wen .vitem senders A &%senders%& router option or &%senders%& ACL condition @@ -8845,7 +8868,7 @@ If the pattern starts with the name of a lookup type of either kind (single-key or query-style) it may be followed by a comma and options, The options are lookup-type specific and consist of a comma-separated list. -Each item starts with a tag and and equals "=". +Each item starts with a tag and and equals "=" sign. .next .cindex "domain list" "matching literal domain name" @@ -8964,9 +8987,13 @@ accept hosts = @[] .endd .next .cindex "CIDR notation" -If the pattern is an IP address followed by a slash and a mask length (for -example 10.11.42.0/24), it is matched against the IP address of the subject -host under the given mask. This allows, an entire network of hosts to be +If the pattern is an IP address followed by a slash and a mask length, for +example +.code +10.11.42.0/24 +.endd +, it is matched against the IP address of the subject +host under the given mask. This allows an entire network of hosts to be included (or excluded) by a single item. The mask uses CIDR notation; it specifies the number of address bits that must match, starting from the most significant end of the address. @@ -9587,6 +9614,8 @@ reasons, 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 @@ -10155,7 +10184,7 @@ They are visible in DKIM, PRDR and DATA ACLs. Header lines that are added in a RCPT ACL (for example) are saved until the message's incoming header lines are available, at which point they are added. -When any of the above ACLs ar +When any of the above ACLs are running, however, header lines added by earlier ACLs are visible. Upper case and lower case letters are synonymous in header names. If the @@ -10431,10 +10460,11 @@ additional arguments need be given; the maximum number permitted, including the name of the subroutine, is nine. The return value of the subroutine is inserted into the expanded string, unless -the return value is &%undef%&. In that case, the expansion fails in the same -way as an explicit &"fail"& on a lookup item. The return value is a scalar. -Whatever you return is evaluated in a scalar context. For example, if you -return the name of a Perl vector, the return value is the size of the vector, +the return value is &%undef%&. In that case, the entire expansion is +forced to fail, in the same way as an explicit &"fail"& on a lookup item +does (see section &<>&). Whatever you return is evaluated +in a scalar context, thus the return value is a scalar. For example, if you +return a Perl vector, the return value is the size of the vector, not its contents. If the subroutine exits by calling Perl's &%die%& function, the expansion fails @@ -10484,7 +10514,7 @@ For more discussion and an example, see section &<>&. .cindex "expansion" "inserting an entire file" .cindex "file" "inserting into expansion" .cindex "&%readfile%& expansion item" -The filename and end-of-line string are first expanded separately. The file is +The filename and end-of-line (eol) string are first expanded separately. The file is then read, and its contents replace the entire item. All newline characters in the file are replaced by the end-of-line string if it is present. Otherwise, newlines are left in the string. @@ -10521,7 +10551,7 @@ ${readsocket{inet:[::1]:1234}{request string}} Only a single host name may be given, but if looking it up yields more than one IP address, they are each tried in turn until a connection is made. For both kinds of socket, Exim makes a connection, writes the request string -unless it is an empty string; and no terminating NUL is ever sent) +(unless it is an empty string; no terminating NUL is ever sent) and reads from the socket until an end-of-file is read. A timeout of 5 seconds is applied. Additional, optional arguments extend what can be done. Firstly, you can vary the timeout. For example: @@ -10987,7 +11017,7 @@ is controlled by the &%print_topbitchars%& option. .vitem &*${escape8bit:*&<&'string'&>&*}*& .cindex "expansion" "escaping 8-bit characters" .cindex "&%escape8bit%& expansion item" -If the string contains and characters with the most significant bit set, +If the string contains any characters with the most significant bit set, they are converted to escape sequences starting with a backslash. Backslashes and DEL characters are also converted. @@ -11454,7 +11484,7 @@ Now deprecated, a synonym for the &%base64%& expansion operator. .cindex "expansion" "string length" .cindex "string" "length in expansion" .cindex "&%strlen%& expansion item" -The item is replace by the length of the expanded string, expressed as a +The item is replaced by the length of the expanded string, expressed as a decimal number. &*Note*&: Do not confuse &%strlen%& with &%length%&. All measurement is done in bytes and is not UTF-8 aware. @@ -14570,6 +14600,7 @@ 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" @@ -14694,6 +14725,7 @@ listed in more than one group. .row &%notifier_socket%& "override compiled-in value" .row &%pid_file_path%& "override compiled-in value" .row &%queue_run_max%& "maximum simultaneous queue runners" +.row &%smtp_backlog_monitor%& "level to log listen backlog" .endtable @@ -15180,6 +15212,18 @@ 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" @@ -17374,7 +17418,7 @@ or if the message was submitted locally (not using TCP/IP), and the &%-bnq%& option was not set. -.option recipients_max main integer 0 +.option recipients_max main integer 50000 .cindex "limit" "number of recipients" .cindex "recipient" "maximum number" If this option is set greater than zero, it specifies the maximum number of @@ -17712,6 +17756,14 @@ messages, it is also used as the default for HELO commands in callout verification if there is no remote transport from which to obtain a &%helo_data%& value. +.option smtp_backlog_monitor main integer 0 +.cindex "connection backlog" monitoring +If this option is set to greater than zero, and the backlog of available +TCP connections on a socket listening for SMTP is larger than it, a line +is logged giving the value and the socket address and port. +The value is retrived jsut before an accept call. +This facility is only available on Linux. + .option smtp_banner main string&!! "see below" .cindex "SMTP" "welcome banner" .cindex "banner for SMTP" @@ -17742,7 +17794,7 @@ is zero). If there isn't enough space, a temporary error code is returned. .option smtp_connect_backlog main integer 20 -.cindex "connection backlog" +.cindex "connection backlog" "set maximum" .cindex "SMTP" "connection backlog" .cindex "backlog of connections" This option specifies a maximum number of waiting SMTP connections. Exim passes @@ -18331,8 +18383,12 @@ if the OpenSSL build supports TLS extensions and the TLS client sends the Server Name Indication extension, then this option and others documented in &<>& will be re-expanded. -If this option is unset or empty a fresh self-signed certificate will be -generated for every connection. +If this option is unset or empty a self-signed certificate will be +.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" @@ -18780,6 +18836,11 @@ 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 @@ -21486,7 +21547,7 @@ The text is not included in the response to an EXPN command. In non-SMTP cases the text is included in the error message that Exim generates. .cindex "SMTP" "error codes" -By default, Exim sends a 451 SMTP code for a &':defer:'&, and 550 for +By default for verify, Exim sends a 451 SMTP code for a &':defer:'&, and 550 for &':fail:'&. However, if the message starts with three digits followed by a space, optionally followed by an extended code of the form &'n.n.n'&, also followed by a space, and the very first digit is the same as the default error @@ -22323,6 +22384,12 @@ 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: @@ -22998,6 +23065,11 @@ If &%file%& or &%directory%& is set for a delivery from a redirection, it is used to determine the file or directory name for the delivery. Normally, the contents of &$address_file$& are used in some way in the string expansion. .endlist +If the &%create_file%& option is set to a path which +matches (see the option definition below for details) +a file or directory name +for the delivery, that name becomes de-tainted. + .cindex "tainted data" "in filenames" .cindex appendfile "tainted data" Tainted data may not be used for a file or directory name. @@ -23145,14 +23217,34 @@ 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"&. In the second and third cases, a home directory must have been -set for the transport. This option is not useful when an explicit filename is +&"belowhome"&, or to an absolute path. +.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 +reside within it. +The "belowhome" checking additionally checks for attempts to use "../" +to evade the testing. +This option is not useful when an explicit filename is given for normal mailbox deliveries. It is intended for the case when filenames are generated from users' &_.forward_& files. These are usually handled by an &(appendfile)& transport called &%address_file%&. See also &%file_must_exist%&. +.new +In the fourth case, +the value given for this option must be an absolute path for an +existing directory. +The value is used for checking instead of a home directory; +checking is done in "belowhome" mode. + +.cindex "tainted data" "de-tainting" +If "belowhome" checking is used, the file or directory path +becomes de-tainted. +.wen + .option directory appendfile string&!! unset This option is mutually exclusive with the &%file%& option, but one of &%file%& @@ -23165,6 +23257,11 @@ 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" .cindex "base62" @@ -23197,6 +23294,11 @@ 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" .cindex "lock files" @@ -25562,6 +25664,11 @@ There will be no fallback to in-clear communication. See the &%dnssec_request_domains%& router and transport options. See section &<>&. +.option hosts_require_helo smtp "host list&!!" * +.cindex "HELO/EHLO" requiring +Exim will require an accepted HELO or EHLO command from a host matching +this list, before accepting a MAIL command. + .option hosts_require_ocsp smtp "host list&!!" unset .cindex "TLS" "requiring for certain servers" Exim will request, and check for a valid Certificate Status being given, on a @@ -25690,7 +25797,7 @@ has advertised support for IGNOREQUOTA in its response to the LHLO command. This option limits the number of RCPT commands that are sent in a single SMTP message transaction. Each set of addresses is treated independently, and so can cause parallel connections to the same host if &%remote_max_parallel%& -permits this. +permits this. A value setting of zero disables the limit. .new @@ -27124,6 +27231,12 @@ 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 Very briefly, the way SMTP authentication works is as follows: @@ -38092,7 +38205,7 @@ implying the use of a default path. When Exim encounters an empty item in the list, it searches the list defined by LOG_FILE_PATH, and uses the first item it finds that is neither empty nor &"syslog"&. This means that an empty item in &%log_file_path%& can be used to -mean &"use the path specified at build time"&. It no such item exists, log +mean &"use the path specified at build time"&. If no such item exists, log files are written in the &_log_& subdirectory of the spool directory. This is equivalent to the setting: .code @@ -38637,6 +38750,7 @@ selection marked by asterisks: &` outgoing_port `& add remote port to => lines &`*queue_run `& start and end queue runs &` queue_time `& time on queue for one recipient +&`*queue_time_exclusive `& exclude recieve time from QT times &` queue_time_overall `& time on queue for whole message &` pid `& Exim process id &` pipelining `& PIPELINING use, on <= and => lines @@ -38659,6 +38773,7 @@ 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 @@ -38878,18 +38993,13 @@ Delivery "L" fields have an asterisk appended if used. .cindex "log" "queue time" &%queue_time%&: The amount of time the message has been in the queue on the local host is logged as QT=<&'time'&> on delivery (&`=>`&) lines, for example, -&`QT=3m45s`&. The clock starts when Exim starts to receive the message, so it -includes reception time as well as the delivery time for the current address. -This means that it may be longer than the difference between the arrival and -delivery log line times, because the arrival log line is not written until the -message has been successfully received. +&`QT=3m45s`&. If millisecond logging is enabled, short times will be shown with greater precision, eg. &`QT=1.578s`&. .next &%queue_time_overall%&: The amount of time the message has been in the queue on the local host is logged as QT=<&'time'&> on &"Completed"& lines, for -example, &`QT=3m45s`&. The clock starts when Exim starts to receive the -message, so it includes reception time as well as the total delivery time. +example, &`QT=3m45s`&. .next .cindex "log" "receive duration" &%receive_time%&: For each message, the amount of real time it has taken to @@ -38948,10 +39058,12 @@ it is too big. .cindex "log" "frozen messages; skipped" .cindex "frozen messages" "logging skipping" &%skip_delivery%&: A log line is written whenever a message is skipped during a -queue run because it is frozen or because another process is already delivering -it. +queue run because it another process is already delivering it or because +it is frozen. .cindex "&""spool file is locked""&" -The message that is written is &"spool file is locked"&. +.cindex "&""message is frozen""&" +The message that is written is either &"spool file is locked"& or +&"message is frozen"&. .next .cindex "log" "smtp confirmation" .cindex "SMTP" "logging confirmation" @@ -39057,6 +39169,11 @@ 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