X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/40ed89b32412fdab2ca147c27fdb856a5623e382..c77d3d85fe:/doc/doc-docbook/spec.xfpt?ds=sidebyside diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 0358ae9d3..c21bc0dcc 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -6741,6 +6741,30 @@ lookup types support only literal keys. &*Warning 2*&: In a host list, you must always use &(net-iplsearch)& so that the implicit key is the host's IP address rather than its name (see section &<>&). + +.new +&*Warning 3*&: Do not use an IPv4-mapped IPv6 address for a key; use the +IPv4. Such addresses being searched for are converted to IPv4. +.wen +.next +.new +.cindex lookup json +.cindex json "lookup type" +.cindex JSON expansions +&(json)&: The given file is a text file with a JSON structure. +An element of the structure is extracted, defined by the search key. +The key is a list of subelement selectors +(colon-separated by default but changeable in the usual way) +which are applied in turn to select smaller and smaller portions +of the JSON structure. +If a selector is numeric, it must apply to a JSON array; the (zero-based) +nunbered array element is selected. +Otherwise it must apply to a JSON object; the named element is selected. +The final resulting element can be a simple JSON type or a JSON object +or array; for the latter two a string-representation os the JSON +is returned. +For elements of type string, the returned value is de-quoted. +.wen .next .cindex "linear search" .cindex "lookup" "lsearch" @@ -8659,8 +8683,12 @@ to quote keys was made available in &(lsearch)& files. However, the more recently implemented &(iplsearch)& files do require colons in IPv6 keys (notated using the quoting facility) so as to distinguish them from IPv4 keys. For this reason, when the lookup type is &(iplsearch)&, IPv6 addresses are -converted using colons and not dots. In all cases, full, unabbreviated IPv6 +converted using colons and not dots. +.new +In all cases except IPv4-mapped IPv6, full, unabbreviated IPv6 addresses are always used. +The latter are converted to IPv4 addresses, in dotted-quad form. +.wen Ideally, it would be nice to tidy up this anomalous situation by changing to colons in all cases, given that quoting is now available for &(lsearch)&. @@ -9518,6 +9546,8 @@ This forces an expansion failure (see section &<>&); {<&'string2'&>} must be present for &"fail"& to be recognized. .vitem "&*${extract json{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&& + {*&<&'string3'&>&*}}*&" &&& + "&*${extract jsons{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&& {*&<&'string3'&>&*}}*&" .cindex "expansion" "extracting from JSON object" .cindex JSON expansions @@ -9532,6 +9562,13 @@ The expanded <&'string1'&> must be of the form: The braces, commas and colons, and the quoting of the member name are required; the spaces are optional. Matching of the key against the member names is done case-sensitively. +For the &"json"& variant, +if a returned value is a JSON string, it retains its leading and +trailing quotes. +.new +For the &"jsons"& variant, which is intended for use with JSON strings, the +leading and trailing quotes are removed from the returned value. +.wen . XXX should be a UTF-8 compare The results of matching are handled as above. @@ -9568,7 +9605,9 @@ yields &"99"&. Two successive separators mean that the field between them is empty (for example, the fifth field above). -.vitem "&*${extract json{*&<&'number'&>&*}}&&& +.vitem "&*${extract json {*&<&'number'&>&*}}&&& + {*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" &&& + "&*${extract jsons{*&<&'number'&>&*}}&&& {*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&" .cindex "expansion" "extracting from JSON array" .cindex JSON expansions @@ -9577,6 +9616,13 @@ apart from leading and trailing white space, which is ignored. Field selection and result handling is as above; there is no choice of field separator. +For the &"json"& variant, +if a returned value is a JSON string, it retains its leading and +trailing quotes. +.new +For the &"jsons"& variant, which is intended for use with JSON strings, the +leading and trailing quotes are removed from the returned value. +.wen .vitem &*${filter{*&<&'string'&>&*}{*&<&'condition'&>&*}}*& @@ -11304,6 +11350,25 @@ being processed, to enable these expansion items to be nested. To scan a named list, expand it with the &*listnamed*& operator. +.new +.vitem "&*forall_json{*&<&'a JSON array'&>&*}{*&<&'a condition'&>&*}*&" &&& + "&*forany_json{*&<&'a JSON array'&>&*}{*&<&'a condition'&>&*}*&" &&& + "&*forall_jsons{*&<&'a JSON array'&>&*}{*&<&'a condition'&>&*}*&" &&& + "&*forany_jsons{*&<&'a JSON array'&>&*}{*&<&'a condition'&>&*}*&" +.cindex JSON "iterative conditions" +.cindex JSON expansions +.cindex expansion "&*forall_json*& condition" +.cindex expansion "&*forany_json*& condition" +.cindex expansion "&*forall_jsons*& condition" +.cindex expansion "&*forany_jsons*& condition" +As for the above, except that the first argument must, after expansion, +be a JSON array. +The array separator is not changeable. +For the &"jsons"& variants the elements are expected to be JSON strings +and have their quotes removed before the evaluation of the condition. +.wen + + .vitem &*ge&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& &*gei&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& @@ -13291,6 +13356,12 @@ The deprecated &$tls_cipher$& variable is the same as &$tls_in_cipher$& during m but in the context of an outward SMTP delivery taking place via the &(smtp)& transport becomes the same as &$tls_out_cipher$&. +.new +.vitem &$tls_in_cipher_std$& +.vindex "&$tls_in_cipher_std$&" +As above, but returning the RFC standard name for the cipher suite. +.wen + .vitem &$tls_out_cipher$& .vindex "&$tls_out_cipher$&" This variable is @@ -13299,6 +13370,12 @@ and then set to the outgoing cipher suite if one is negotiated. See chapter &<>& for details of TLS support and chapter &<>& for details of the &(smtp)& transport. +,new +.vitem &$tls_out_cipher_std$& +.vindex "&$tls_out_cipher_std$&" +As above, but returning the RFC standard name for the cipher suite. +.wen + .vitem &$tls_out_dane$& .vindex &$tls_out_dane$& DANE active status. See section &<>&. @@ -16529,23 +16606,26 @@ on at the end (preceded by a semicolon). The string is expanded each time it is used. If the expansion yields an empty string, no &'Received:'& header line is added to the message. Otherwise, the string should start with the text &"Received:"& and conform to the RFC 2822 specification for &'Received:'& -header lines. The default setting is: +header lines. +.new +The default setting is: .code received_header_text = Received: \ ${if def:sender_rcvhost {from $sender_rcvhost\n\t}\ - {${if def:sender_ident \ - {from ${quote_local_part:$sender_ident} }}\ - ${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\ + {${if def:sender_ident \ + {from ${quote_local_part:$sender_ident} }}\ + ${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\ by $primary_hostname \ - ${if def:received_protocol {with $received_protocol}} \ - ${if def:tls_in_cipher {($tls_in_cipher)\n\t}}\ + ${if def:received_protocol {with $received_protocol }}\ + ${if def:tls_in_cipher_std { tls $tls_in_cipher_std\n\t}}\ (Exim $version_number)\n\t\ ${if def:sender_address \ {(envelope-from <$sender_address>)\n\t}}\ id $message_exim_id\ ${if def:received_for {\n\tfor $received_for}} .endd +.wen The reference to the TLS cipher is omitted when Exim is built without TLS support. The use of conditional expansions ensures that this works for both @@ -26128,6 +26208,7 @@ included by setting AUTH_CRAM_MD5=yes AUTH_CYRUS_SASL=yes AUTH_DOVECOT=yes +AUTH_EXTERNAL=yes AUTH_GSASL=yes AUTH_HEIMDAL_GSSAPI=yes AUTH_PLAINTEXT=yes @@ -26139,15 +26220,20 @@ authentication mechanism (RFC 2195), and the second provides an interface to the Cyrus SASL authentication library. The third is an interface to Dovecot's authentication system, delegating the work via a socket interface. -The fourth provides an interface to the GNU SASL authentication library, which +.new +The fourth provides for negotiation of authentication done via non-SMTP means, +as defined by RFC 4422 Appendix A. +.wen +The fifth provides an interface to the GNU SASL authentication library, which provides mechanisms but typically not data sources. -The fifth provides direct access to Heimdal GSSAPI, geared for Kerberos, but +The sixth provides direct access to Heimdal GSSAPI, geared for Kerberos, but supporting setting a server keytab. -The sixth can be configured to support +The seventh can be configured to support the PLAIN authentication mechanism (RFC 2595) or the LOGIN mechanism, which is -not formally documented, but used by several MUAs. The seventh authenticator +not formally documented, but used by several MUAs. +The eighth authenticator supports Microsoft's &'Secure Password Authentication'& mechanism. -The eighth is an Exim authenticator but not an SMTP one; +The last is an Exim authenticator but not an SMTP one; instead it can use information from a TLS negotiation. The authenticators are configured using the same syntax as other drivers (see @@ -27382,6 +27468,143 @@ msn: +. //////////////////////////////////////////////////////////////////////////// +. //////////////////////////////////////////////////////////////////////////// + +.chapter "The external authenticator" "CHAPexternauth" +.scindex IIDexternauth1 "&(external)& authenticator" +.scindex IIDexternauth2 "authenticators" "&(external)&" +.cindex "authentication" "Client Certificate" +.cindex "authentication" "X509" +.cindex "Certificate-based authentication" +The &(external)& authenticator provides support for +authentication based on non-SMTP information. +The specification is in RFC 4422 Appendix A +(&url(https://tools.ietf.org/html/rfc4422)). +It is only a transport and negotiation mechanism; +the process of authentication is entirely controlled +by the server configuration. + +The client presents an identity in-clear. +It is probably wise for a server to only advertise, +and for clients to only attempt, +this authentication method on a secure (eg. under TLS) connection. + +One possible use, compatible with the +K-9 Mail Andoid client (&url(https://k9mail.github.io/)), +is for using X509 client certificates. + +It thus overlaps in function with the TLS authenticator +(see &<>&) +but is a full SMTP SASL authenticator +rather than being implicit for TLS-connection carried +client certificates only. + +The examples and discussion in this chapter assume that +client-certificate authentication is being done. + +The client must present a certificate, +for which it must have been requested via the +&%tls_verify_hosts%& or &%tls_try_verify_hosts%& main options +(see &<>&). +For authentication to be effective the certificate should be +verifiable against a trust-anchor certificate known to the server. + +.section "External options" "SECTexternsoptions" +.cindex "options" "&(external)& authenticator (server)" +The &(external)& authenticator has two server options: + +.option server_param2 external string&!! unset +.option server_param3 external string&!! unset +.cindex "variables (&$auth1$& &$auth2$& etc)" "in &(external)& authenticator" +These options are expanded before the &%server_condition%& option +and the result are placed in &$auth2$& and &$auth3$& resectively. +If the expansion is forced to fail, authentication fails. Any other expansion +failure causes a temporary error code to be returned. + +They can be used to clarify the coding of a complex &%server_condition%&. + +.section "Using external in a server" "SECTexternserver" +.cindex "AUTH" "in &(external)& authenticator" +.cindex "numerical variables (&$1$& &$2$& etc)" &&& + "in &(external)& authenticator" +.vindex "&$auth1$&, &$auth2$&, etc" +.cindex "base64 encoding" "in &(external)& authenticator" + +When running as a server, &(external)& performs the authentication test by +expanding a string. The data sent by the client with the AUTH command, or in +response to subsequent prompts, is base64 encoded, and so may contain any byte +values when decoded. The decoded value is treated as +an identity for authentication and +placed in the expansion variable &$auth1$&. + +For compatibility with previous releases of Exim, the value is also placed in +the expansion variable &$1$&. However, the use of this +variable for this purpose is now deprecated, as it can lead to confusion in +string expansions that also use them for other things. + +.vindex "&$authenticated_id$&" +Once an identity has been received, +&%server_condition%& is expanded. If the expansion is forced to fail, +authentication fails. Any other expansion failure causes a temporary error code +to be returned. If the result of a successful expansion is an empty string, +&"0"&, &"no"&, or &"false"&, authentication fails. If the result of the +expansion is &"1"&, &"yes"&, or &"true"&, authentication succeeds and the +generic &%server_set_id%& option is expanded and saved in &$authenticated_id$&. +For any other result, a temporary error code is returned, with the expanded +string as the error text. + +Example: +.code +ext_ccert_san_mail: + driver = external + public_name = EXTERNAL + + server_advertise_condition = $tls_in_certificate_verified + server_param2 = ${certextract {subj_altname,mail,>:} \ + {$tls_in_peercert}} + server_condition = ${if forany {$auth2} \ + {eq {$item}{$auth1}}} + server_set_id = $auth1 +.endd +This accepts a client certificate that is verifiable against any +of your configured trust-anchors +(which usually means the full set of public CAs) +and which has a mail-SAN matching the claimed identity sent by the client. + +Note that, up to TLS1.2, the client cert is on the wire in-clear, including the SAN, +The account name is therefore guessable by an opponent. +TLS 1.3 protects both server and client certificates, and is not vulnerable +in this way. +Likewise, a traditional plaintext SMTP AUTH done inside TLS is not. + + +.section "Using external in a client" "SECTexternclient" +.cindex "options" "&(external)& authenticator (client)" +The &(external)& authenticator has one client option: + +.option client_send external string&!! unset +This option is expanded and sent with the AUTH command as the +identity being asserted. + +Example: +.code +ext_ccert: + driver = external + public_name = EXTERNAL + + client_condition = ${if !eq{$tls_out_cipher}{}} + client_send = myaccount@smarthost.example.net +.endd + + +.ecindex IIDexternauth1 +.ecindex IIDexternauth2 + + + + + . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -36787,7 +37010,7 @@ the following table: &`F `& sender address (on delivery lines) &`H `& host name and IP address &`I `& local interface used -&`id `& message id for incoming message +&`id `& message id (from header) for incoming message &`K `& CHUNKING extension used &`L `& on &`<=`& and &`=>`& lines: PIPELINING extension used &`M8S `& 8BITMIME status for incoming message @@ -36894,6 +37117,8 @@ selection marked by asterisks: &` incoming_port `& remote port on <= lines &`*lost_incoming_connection `& as it says (includes timeouts) &` millisec `& millisecond timestamps and RT,QT,DT,D times +&`*msg_id `& on <= lines, Message-ID: header value +&` msg_id_created `& on <= lines, Message-ID: header value when one had to be added &` outgoing_interface `& local interface on => lines &` outgoing_port `& add remote port to => lines &`*queue_run `& start and end queue runs @@ -37077,6 +37302,16 @@ connection is unexpectedly dropped. &%millisec%&: Timestamps have a period and three decimal places of finer granularity appended to the seconds value. .next +.new +.cindex "log" "message id" +&%msg_id%&: The value of the Message-ID: header. +.next +&%msg_id_created%&: The value of the Message-ID: header, when one had to be created. +This will be either because the message is a bounce, or was submitted locally +(submission mode) without one. +The field identifier will have an asterix appended: &"id*="&. +.wen +.next .cindex "log" "outgoing interface" .cindex "log" "local interface" .cindex "log" "local address and port" @@ -39320,7 +39555,7 @@ senders). .cindex "DKIM" "signing" For signing to be usable you must have published a DKIM record in DNS. -Note that RFC 8301 says: +Note that RFC 8301 (which does not cover EC keys) says: .code rsa-sha1 MUST NOT be used for signing or verifying. @@ -39340,7 +39575,11 @@ These options take (expandable) strings as arguments. .option dkim_domain smtp string list&!! unset The domain(s) you want to sign with. After expansion, this can be a list. -Each element in turn is put into the &%$dkim_domain%& expansion variable +Each element in turn, +.new +lowercased, +.wen +is put into the &%$dkim_domain%& expansion variable while expanding the remaining signing options. If it is empty after expansion, DKIM signing is not done, and no error will result even if &%dkim_strict%& is set. @@ -39394,8 +39633,9 @@ Signers MUST use RSA keys of at least 1024 bits for all keys. Signers SHOULD use RSA keys of at least 2048 bits. .endd -Support for EC keys is being developed under -&url(https://datatracker.ietf.org/doc/draft-ietf-dcrup-dkim-crypto/). +.new +EC keys for DKIM are defined by RFC 8463. +.wen They are considerably smaller than RSA keys for equivalent protection. As they are a recent development, users should consider dual-signing (by setting a list of selectors, and an expansion for this option) @@ -39415,10 +39655,12 @@ openssl pkey -outform DER -pubout -in dkim_ed25519.private | tail -c +13 | base6 certtool --load_privkey=dkim_ed25519.private --pubkey_info --outder | tail -c +13 | base64 .endd -Note that the format -of Ed25519 keys in DNS has not yet been decided; this release supports -both of the leading candidates at this time, a future release will -probably drop support for whichever proposal loses. +.new +Exim also supports an alternate format +of Ed25519 keys in DNS which was a candidate during development +of the standard, but not adopted. +A future release will probably drop that support. +.wen .option dkim_hash smtp string&!! sha256 Can be set to any one of the supported hash methods, which are: @@ -39541,6 +39783,14 @@ dkim_verify_signers = $sender_address_domain:$dkim_signers If a domain or identity is listed several times in the (expanded) value of &%dkim_verify_signers%&, the ACL is only called once for that domain or identity. +.new +Note that if the option is set using untrustworthy data +(such as the From: header) +care should be taken to force lowercase for domains +and for the domain part if identities. +The default setting can be regarded as trustworthy in this respect. +.wen + If multiple signatures match a domain (or identity), the ACL is called once for each matching signature. @@ -39978,6 +40228,8 @@ of the proxy): .endd If &$proxy_session$& is set but &$proxy_external_address$& is empty there was a protocol error. +The variables &$sender_host_address$& and &$sender_host_port$& +will have values for the actual client system, not the proxy. Since the real connections are all coming from the proxy, and the per host connection tracking is done before Proxy Protocol is