X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/d8e99d6047e709b35eabb1395c2046100d1a1dda..41c494e2465efadc2e82002a07430e8aec85bc9b:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 279b82859..cbb7045a3 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -228,6 +228,14 @@ failure report bounce message + + de-tainting + tainting, de-tainting + + + detainting + tainting, de-tainting + dialup intermittently connected hosts @@ -3847,7 +3855,9 @@ 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" @@ -3919,6 +3929,18 @@ 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%&" +.oindex "&%-MCr%&" +These options are not intended for use by external callers. It is used internally +by Exim in conjunction with the &%-MCt%& option, and passes on the fact that +a TLS Server Name Indication was sent as part of the channel establishment. +The argument gives the SNI string. +The "r" variant indicates a DANE-verified connection. +.wen + .vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&> .oindex "&%-MCt%&" This option is not intended for use by external callers. It is used internally @@ -9460,7 +9482,22 @@ reasons, .cindex "tainted data" expansion .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). +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" +come down to using the tainted value as a lookup key in a trusted database. +This database could be the filesystem structure, +or the password file, +or accessed via a DBMS. +Specific methods are indexed under &"de-tainting"&. +.wen @@ -14396,6 +14433,8 @@ 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" @@ -15003,6 +15042,18 @@ 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" @@ -16846,7 +16897,7 @@ 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 @@ -16855,7 +16906,9 @@ 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 @@ -25392,11 +25445,14 @@ BDAT will not be used in conjunction with a transport filter. .option hosts_try_dane smtp "host list&!!" * .cindex DANE "transport options" .cindex DANE "attempting for certain servers" -If built with DANE support, Exim will require that a DNSSEC-validated -TLSA record is present for any host matching the list, -and that a DANE-verified TLS connection is made. See -the &%dnssec_request_domains%& router and transport options. -There will be no fallback to in-clear communication. +.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 &<>&. .option hosts_try_fastopen smtp "host list&!!" * @@ -27627,7 +27683,14 @@ 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: @@ -28693,6 +28756,12 @@ 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 @@ -38127,6 +38196,7 @@ 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 @@ -38520,6 +38590,11 @@ using a CA trust anchor, &`CA=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 @@ -38589,9 +38664,9 @@ the next chapter. The utilities described here are: "check address acceptance from given IP" .irow &<>& &'exim_dbmbuild'& "build a DBM file" .irow &<>& &'exinext'& "extract retry information" -.irow &<>& &'exim_dumpdb'& "dump a hints database" -.irow &<>& &'exim_tidydb'& "clean up a hints database" -.irow &<>& &'exim_fixdb'& "patch a hints database" +.irow &<>& &'exim_dumpdb'& "dump a hints database" +.irow &<>& &'exim_tidydb'& "clean up a hints database" +.irow &<>& &'exim_fixdb'& "patch a hints database" .irow &<>& &'exim_lock'& "lock a mailbox file" .endtable @@ -39093,7 +39168,7 @@ in a transport) -.section "exim_dumpdb" "SECID261" +.section "exim_dumpdb" "SECTdumpdb" .cindex "&'exim_dumpdb'&" The entire contents of a database are written to the standard output by the &'exim_dumpdb'& program, which has no options or arguments other than the @@ -39130,7 +39205,7 @@ cross-references. -.section "exim_tidydb" "SECID262" +.section "exim_tidydb" "SECTtidydb" .cindex "&'exim_tidydb'&" The &'exim_tidydb'& utility program is used to tidy up the contents of a hints database. If run with no options, it removes all records that are more than 30 @@ -39179,7 +39254,7 @@ databases is likely to keep on increasing. -.section "exim_fixdb" "SECID263" +.section "exim_fixdb" "SECTfixdb" .cindex "&'exim_fixdb'&" The &'exim_fixdb'& program is a utility for interactively modifying databases. Its main use is for testing Exim, but it might also be occasionally useful for