From f75140fe8504f1fa69e98facbf8258b67af7ebff Mon Sep 17 00:00:00 2001 From: Wietse Venema Date: Fri, 22 Dec 2023 00:00:00 -0500 Subject: [PATCH] postfix-3.5.23 --- postfix/HISTORY | 14 ++ postfix/RELEASE_NOTES | 25 ++ postfix/html/postconf.5.html | 59 +++++ postfix/html/smtpd.8.html | 363 +++++++++++++++--------------- postfix/man/man5/postconf.5 | 55 +++++ postfix/man/man8/smtpd.8 | 9 + postfix/mantools/postlink | 2 + postfix/proto/postconf.proto | 51 +++++ postfix/src/global/mail_params.h | 11 +- postfix/src/global/mail_version.h | 4 +- postfix/src/global/smtp_stream.c | 14 +- postfix/src/global/smtp_stream.h | 2 + postfix/src/smtpd/smtpd.c | 42 ++++ 13 files changed, 471 insertions(+), 180 deletions(-) diff --git a/postfix/HISTORY b/postfix/HISTORY index 0076c07de..2fd9bb97d 100644 --- a/postfix/HISTORY +++ b/postfix/HISTORY @@ -25399,3 +25399,17 @@ Apologies for any names omitted. delimiter. Fixed by restoring Postfix 2.10 behavior to use a configured recipient delimiter value. Reported by Tod A. Sandman. Files: proto/postconf.proto, local/local_expand.c. + +20231221 + + Security: with "smtpd_forbid_bare_newline = yes" (default + "no" for Postfix < 3.9), reply with "Error: bare + received" and disconnect when an SMTP client sends a line + ending in , violating the RFC 5321 requirement that + lines must end in . This prevents SMTP smuggling + attacks that target a recipient at a Postfix server. For + backwards compatibility, local clients are excluded by + default with "smtpd_forbid_bare_newline_exclusions = + $mynetworks". Files: mantools/postlink, proto/postconf.proto, + global/mail_params.h, global/smtp_stream.c, global/smtp_stream.h, + smtpd/smtpd.c. diff --git a/postfix/RELEASE_NOTES b/postfix/RELEASE_NOTES index 3aefabb2a..d411f2a0d 100644 --- a/postfix/RELEASE_NOTES +++ b/postfix/RELEASE_NOTES @@ -25,6 +25,31 @@ more recent Eclipse Public License 2.0. Recipients can choose to take the software under the license of their choice. Those who are more comfortable with the IPL can continue with that license. +Major changes with Postfix 3.5.23 +================================= + +Security: the Postfix SMTP server optionally disconnects a remote +SMTP client that sends a 'bare newline' line ending in SMTP. This +prevents an SMTP smuggling attack on recipients at a Postfix server. +For background, see https://www.postfix.org/smtp-smuggling.html + +Sites concerned about SMTP smuggling attacks should enable this +feature in Internet-facing Postfix servers. For compatibility with +non-standard clients, Postfix by default excludes clients in +mynetworks from this countermeasure. + +The recommended settings are: + + # Optionally disconnect remote SMTP clients that send bare newlines, + # but allow local clients with non-standard SMTP implementations + # such as netcat, fax machines, or load balancer health checks. + # + smtpd_forbid_bare_newline = no + smtpd_forbid_bare_newline_exclusions = $mynetworks + +This feature is back-ported from Postfix 3.9, with the difference +that "smtpd_forbid_bare_newline = no" by default. + Major changes with Postfix 3.5.20 ================================= diff --git a/postfix/html/postconf.5.html b/postfix/html/postconf.5.html index 163ad1d49..8c1dbebb2 100644 --- a/postfix/html/postconf.5.html +++ b/postfix/html/postconf.5.html @@ -15047,6 +15047,65 @@ This feature is available in Postfix 2.0 and later.

+ + +
smtpd_forbid_bare_newline +(default: Postfix < 3.9: no)
+ +

Reply with "Error: bare <LF> received" and disconnect +when a remote SMTP client sends a line ending in <LF>, violating +the RFC 5321 requirement that lines must end in <CR><LF>. +This feature is disbled by default with Postfix < 3.9. Use +smtpd_forbid_bare_newline_exclusions to exclude non-standard clients +such as netcat. Specify "smtpd_forbid_bare_newline = no" to disable +(not recommended for an Internet-connected MTA).

+ +

See +https://www.postfix.org/smtp-smuggling.html for details. + +

Example:

+ +
+
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+
+
+ +

This feature is available in Postfix ≥ 3.9, 3.8.4, 3.7.9, +3.6.13, and 3.5.23.

+ + +
+ +
smtpd_forbid_bare_newline_exclusions +(default: $mynetworks)
+ +

Exclude the specified clients from smtpd_forbid_bare_newline +enforcement. It uses the same syntax and parent-domain matching +behavior as mynetworks.

+ +

Example:

+ +
+
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+
+
+ +

This feature is available in Postfix ≥ 3.9, 3.8.4, 3.7.9, +3.6.13, and 3.5.23.

+ +
smtpd_forbid_unauth_pipelining diff --git a/postfix/html/smtpd.8.html b/postfix/html/smtpd.8.html index c51adb736..78b6abe18 100644 --- a/postfix/html/smtpd.8.html +++ b/postfix/html/smtpd.8.html @@ -612,12 +612,12 @@ SMTPD(8) SMTPD(8) tialization functions. OBSOLETE STARTTLS CONTROLS - The following configuration parameters exist for compatibility with - Postfix versions before 2.3. Support for these will be removed in a + The following configuration parameters exist for compatibility with + Postfix versions before 2.3. Support for these will be removed in a future release. smtpd_use_tls (no) - Opportunistic TLS: announce STARTTLS support to remote SMTP + Opportunistic TLS: announce STARTTLS support to remote SMTP clients, but do not require that clients use TLS encryption. smtpd_enforce_tls (no) @@ -625,92 +625,92 @@ SMTPD(8) SMTPD(8) and require that clients use TLS encryption. smtpd_tls_cipherlist (empty) - Obsolete Postfix < 2.3 control for the Postfix SMTP server TLS + Obsolete Postfix < 2.3 control for the Postfix SMTP server TLS cipher list. SMTPUTF8 CONTROLS Preliminary SMTPUTF8 support is introduced with Postfix 3.0. smtputf8_enable (yes) - Enable preliminary SMTPUTF8 support for the protocols described + Enable preliminary SMTPUTF8 support for the protocols described in RFC 6531..6533. strict_smtputf8 (no) Enable stricter enforcement of the SMTPUTF8 protocol. smtputf8_autodetect_classes (sendmail, verify) - Detect that a message requires SMTPUTF8 support for the speci- + Detect that a message requires SMTPUTF8 support for the speci- fied mail origin classes. Available in Postfix version 3.2 and later: enable_idna2003_compatibility (no) - Enable 'transitional' compatibility between IDNA2003 and - IDNA2008, when converting UTF-8 domain names to/from the ASCII + Enable 'transitional' compatibility between IDNA2003 and + IDNA2008, when converting UTF-8 domain names to/from the ASCII form that is used for DNS lookups. VERP SUPPORT CONTROLS - With VERP style delivery, each recipient of a message receives a cus- - tomized copy of the message with his/her own recipient address encoded + With VERP style delivery, each recipient of a message receives a cus- + tomized copy of the message with his/her own recipient address encoded in the envelope sender address. The VERP_README file describes config- - uration and operation details of Postfix support for variable envelope - return path addresses. VERP style delivery is requested with the SMTP - XVERP command or with the "sendmail -V" command-line option and is + uration and operation details of Postfix support for variable envelope + return path addresses. VERP style delivery is requested with the SMTP + XVERP command or with the "sendmail -V" command-line option and is available in Postfix version 1.1 and later. default_verp_delimiters (+=) The two default VERP delimiter characters. verp_delimiter_filter (-=+) - The characters Postfix accepts as VERP delimiter characters on + The characters Postfix accepts as VERP delimiter characters on the Postfix sendmail(1) command line and in SMTP commands. Available in Postfix version 1.1 and 2.0: authorized_verp_clients ($mynetworks) - What remote SMTP clients are allowed to specify the XVERP com- + What remote SMTP clients are allowed to specify the XVERP com- mand. Available in Postfix version 2.1 and later: smtpd_authorized_verp_clients ($authorized_verp_clients) - What remote SMTP clients are allowed to specify the XVERP com- + What remote SMTP clients are allowed to specify the XVERP com- mand. TROUBLE SHOOTING CONTROLS - The DEBUG_README document describes how to debug parts of the Postfix - mail system. The methods vary from making the software log a lot of + The DEBUG_README document describes how to debug parts of the Postfix + mail system. The methods vary from making the software log a lot of detail, to running some daemon processes under control of a call tracer or debugger. debug_peer_level (2) - The increment in verbose logging level when a remote client or + The increment in verbose logging level when a remote client or server matches a pattern in the debug_peer_list parameter. debug_peer_list (empty) - Optional list of remote client or server hostname or network + Optional list of remote client or server hostname or network address patterns that cause the verbose logging level to increase by the amount specified in $debug_peer_level. error_notice_recipient (postmaster) - The recipient of postmaster notifications about mail delivery + The recipient of postmaster notifications about mail delivery problems that are caused by policy, resource, software or proto- col errors. internal_mail_filter_classes (empty) - What categories of Postfix-generated mail are subject to - before-queue content inspection by non_smtpd_milters, + What categories of Postfix-generated mail are subject to + before-queue content inspection by non_smtpd_milters, header_checks and body_checks. notify_classes (resource, software) The list of error classes that are reported to the postmaster. smtpd_reject_footer (empty) - Optional information that is appended after each Postfix SMTP + Optional information that is appended after each Postfix SMTP server 4XX or 5XX response. soft_bounce (no) - Safety net to keep mail queued that would otherwise be returned + Safety net to keep mail queued that would otherwise be returned to the sender. Available in Postfix version 2.1 and later: @@ -721,109 +721,109 @@ SMTPD(8) SMTPD(8) Available in Postfix version 2.10 and later: smtpd_log_access_permit_actions (empty) - Enable logging of the named "permit" actions in SMTP server - access lists (by default, the SMTP server logs "reject" actions + Enable logging of the named "permit" actions in SMTP server + access lists (by default, the SMTP server logs "reject" actions but not "permit" actions). KNOWN VERSUS UNKNOWN RECIPIENT CONTROLS - As of Postfix version 2.0, the SMTP server rejects mail for unknown + As of Postfix version 2.0, the SMTP server rejects mail for unknown recipients. This prevents the mail queue from clogging up with undeliv- - erable MAILER-DAEMON messages. Additional information on this topic is + erable MAILER-DAEMON messages. Additional information on this topic is in the LOCAL_RECIPIENT_README and ADDRESS_CLASS_README documents. show_user_unknown_table_name (yes) - Display the name of the recipient table in the "User unknown" + Display the name of the recipient table in the "User unknown" responses. canonical_maps (empty) - Optional address mapping lookup tables for message headers and + Optional address mapping lookup tables for message headers and envelopes. recipient_canonical_maps (empty) - Optional address mapping lookup tables for envelope and header + Optional address mapping lookup tables for envelope and header recipient addresses. sender_canonical_maps (empty) - Optional address mapping lookup tables for envelope and header + Optional address mapping lookup tables for envelope and header sender addresses. Parameters concerning known/unknown local recipients: mydestination ($myhostname, localhost.$mydomain, localhost) - The list of domains that are delivered via the $local_transport + The list of domains that are delivered via the $local_transport mail delivery transport. inet_interfaces (all) - The network interface addresses that this mail system receives + The network interface addresses that this mail system receives mail on. proxy_interfaces (empty) - The network interface addresses that this mail system receives + The network interface addresses that this mail system receives mail on by way of a proxy or network address translation unit. inet_protocols (all) - The Internet protocols Postfix will attempt to use when making + The Internet protocols Postfix will attempt to use when making or accepting connections. local_recipient_maps (proxy:unix:passwd.byname $alias_maps) Lookup tables with all names or addresses of local recipients: a - recipient address is local when its domain matches $mydestina- + recipient address is local when its domain matches $mydestina- tion, $inet_interfaces or $proxy_interfaces. unknown_local_recipient_reject_code (550) The numerical Postfix SMTP server response code when a recipient - address is local, and $local_recipient_maps specifies a list of + address is local, and $local_recipient_maps specifies a list of lookup tables that does not match the recipient. Parameters concerning known/unknown recipients of relay destinations: relay_domains (Postfix >= 3.0: empty, Postfix < 3.0: $mydestination) - What destination domains (and subdomains thereof) this system + What destination domains (and subdomains thereof) this system will relay mail to. relay_recipient_maps (empty) - Optional lookup tables with all valid addresses in the domains + Optional lookup tables with all valid addresses in the domains that match $relay_domains. unknown_relay_recipient_reject_code (550) - The numerical Postfix SMTP server reply code when a recipient - address matches $relay_domains, and relay_recipient_maps speci- - fies a list of lookup tables that does not match the recipient + The numerical Postfix SMTP server reply code when a recipient + address matches $relay_domains, and relay_recipient_maps speci- + fies a list of lookup tables that does not match the recipient address. - Parameters concerning known/unknown recipients in virtual alias + Parameters concerning known/unknown recipients in virtual alias domains: virtual_alias_domains ($virtual_alias_maps) - Postfix is final destination for the specified list of virtual - alias domains, that is, domains for which all addresses are + Postfix is final destination for the specified list of virtual + alias domains, that is, domains for which all addresses are aliased to addresses in other local or remote domains. virtual_alias_maps ($virtual_maps) - Optional lookup tables that alias specific mail addresses or + Optional lookup tables that alias specific mail addresses or domains to other local or remote address. unknown_virtual_alias_reject_code (550) - The Postfix SMTP server reply code when a recipient address - matches $virtual_alias_domains, and $virtual_alias_maps speci- - fies a list of lookup tables that does not match the recipient + The Postfix SMTP server reply code when a recipient address + matches $virtual_alias_domains, and $virtual_alias_maps speci- + fies a list of lookup tables that does not match the recipient address. Parameters concerning known/unknown recipients in virtual mailbox domains: virtual_mailbox_domains ($virtual_mailbox_maps) - Postfix is final destination for the specified list of domains; - mail is delivered via the $virtual_transport mail delivery + Postfix is final destination for the specified list of domains; + mail is delivered via the $virtual_transport mail delivery transport. virtual_mailbox_maps (empty) - Optional lookup tables with all valid addresses in the domains + Optional lookup tables with all valid addresses in the domains that match $virtual_mailbox_domains. unknown_virtual_mailbox_reject_code (550) - The Postfix SMTP server reply code when a recipient address - matches $virtual_mailbox_domains, and $virtual_mailbox_maps + The Postfix SMTP server reply code when a recipient address + matches $virtual_mailbox_domains, and $virtual_mailbox_maps specifies a list of lookup tables that does not match the recip- ient address. @@ -832,7 +832,7 @@ SMTPD(8) SMTPD(8) control client request rates. line_length_limit (2048) - Upon input, long lines are chopped up into pieces of at most + Upon input, long lines are chopped up into pieces of at most this length; upon delivery, long lines are reconstructed. queue_minfree (0) @@ -840,58 +840,58 @@ SMTPD(8) SMTPD(8) tem that is needed to receive mail. message_size_limit (10240000) - The maximal size in bytes of a message, including envelope + The maximal size in bytes of a message, including envelope information. smtpd_recipient_limit (1000) - The maximal number of recipients that the Postfix SMTP server + The maximal number of recipients that the Postfix SMTP server accepts per message delivery request. smtpd_timeout (normal: 300s, overload: 10s) - The time limit for sending a Postfix SMTP server response and + The time limit for sending a Postfix SMTP server response and for receiving a remote SMTP client request. smtpd_history_flush_threshold (100) - The maximal number of lines in the Postfix SMTP server command - history before it is flushed upon receipt of EHLO, RSET, or end + The maximal number of lines in the Postfix SMTP server command + history before it is flushed upon receipt of EHLO, RSET, or end of DATA. Available in Postfix version 2.3 and later: smtpd_peername_lookup (yes) - Attempt to look up the remote SMTP client hostname, and verify + Attempt to look up the remote SMTP client hostname, and verify that the name matches the client IP address. The per SMTP client connection count and request rate limits are imple- - mented in co-operation with the anvil(8) service, and are available in + mented in co-operation with the anvil(8) service, and are available in Postfix version 2.2 and later. smtpd_client_connection_count_limit (50) - How many simultaneous connections any client is allowed to make + How many simultaneous connections any client is allowed to make to this service. smtpd_client_connection_rate_limit (0) - The maximal number of connection attempts any client is allowed + The maximal number of connection attempts any client is allowed to make to this service per time unit. smtpd_client_message_rate_limit (0) - The maximal number of message delivery requests that any client - is allowed to make to this service per time unit, regardless of + The maximal number of message delivery requests that any client + is allowed to make to this service per time unit, regardless of whether or not Postfix actually accepts those messages. smtpd_client_recipient_rate_limit (0) - The maximal number of recipient addresses that any client is - allowed to send to this service per time unit, regardless of + The maximal number of recipient addresses that any client is + allowed to send to this service per time unit, regardless of whether or not Postfix actually accepts those recipients. smtpd_client_event_limit_exceptions ($mynetworks) - Clients that are excluded from smtpd_client_*_count/rate_limit + Clients that are excluded from smtpd_client_*_count/rate_limit restrictions. Available in Postfix version 2.3 and later: smtpd_client_new_tls_session_rate_limit (0) - The maximal number of new (i.e., uncached) TLS sessions that a + The maximal number of new (i.e., uncached) TLS sessions that a remote SMTP client is allowed to negotiate with this service per time unit. @@ -899,74 +899,85 @@ SMTPD(8) SMTPD(8) smtpd_per_record_deadline (normal: no, overload: yes) Change the behavior of the smtpd_timeout and smtpd_start- - tls_timeout time limits, from a time limit per read or write - system call, to a time limit to send or receive a complete - record (an SMTP command line, SMTP response line, SMTP message + tls_timeout time limits, from a time limit per read or write + system call, to a time limit to send or receive a complete + record (an SMTP command line, SMTP response line, SMTP message content line, or TLS protocol message). Available in Postfix version 3.1 and later: smtpd_client_auth_rate_limit (0) - The maximal number of AUTH commands that any client is allowed - to send to this service per time unit, regardless of whether or + The maximal number of AUTH commands that any client is allowed + to send to this service per time unit, regardless of whether or not Postfix actually accepts those commands. Available in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later: smtpd_forbid_unauth_pipelining (Postfix >= 3.9: yes) - Disconnect remote SMTP clients that violate RFC 2920 (or 5321) + Disconnect remote SMTP clients that violate RFC 2920 (or 5321) command pipelining constraints. + Available in Postfix 3.9, 3.8.4, 3.7.9, 3.6.13, 3.5.23 and later: + + smtpd_forbid_bare_newline (Postfix < 3.9: no) + Reply with "Error: bare <LF> received" and disconnect when a + remote SMTP client sends a line ending in <LF>, violating the + RFC 5321 requirement that lines must end in <CR><LF>. + + smtpd_forbid_bare_newline_exclusions ($mynetworks) + Exclude the specified clients from smtpd_forbid_bare_newline + enforcement. + TARPIT CONTROLS - When a remote SMTP client makes errors, the Postfix SMTP server can - insert delays before responding. This can help to slow down run-away - software. The behavior is controlled by an error counter that counts + When a remote SMTP client makes errors, the Postfix SMTP server can + insert delays before responding. This can help to slow down run-away + software. The behavior is controlled by an error counter that counts the number of errors within an SMTP session that a client makes without delivering mail. smtpd_error_sleep_time (1s) - With Postfix version 2.1 and later: the SMTP server response - delay after a client has made more than $smtpd_soft_error_limit - errors, and fewer than $smtpd_hard_error_limit errors, without + With Postfix version 2.1 and later: the SMTP server response + delay after a client has made more than $smtpd_soft_error_limit + errors, and fewer than $smtpd_hard_error_limit errors, without delivering mail. smtpd_soft_error_limit (10) - The number of errors a remote SMTP client is allowed to make - without delivering mail before the Postfix SMTP server slows + The number of errors a remote SMTP client is allowed to make + without delivering mail before the Postfix SMTP server slows down all its responses. smtpd_hard_error_limit (normal: 20, overload: 1) - The maximal number of errors a remote SMTP client is allowed to + The maximal number of errors a remote SMTP client is allowed to make without delivering mail. smtpd_junk_command_limit (normal: 100, overload: 1) - The number of junk commands (NOOP, VRFY, ETRN or RSET) that a - remote SMTP client can send before the Postfix SMTP server + The number of junk commands (NOOP, VRFY, ETRN or RSET) that a + remote SMTP client can send before the Postfix SMTP server starts to increment the error counter with each junk command. Available in Postfix version 2.1 and later: smtpd_recipient_overshoot_limit (1000) - The number of recipients that a remote SMTP client can send in + The number of recipients that a remote SMTP client can send in excess of the limit specified with $smtpd_recipient_limit, - before the Postfix SMTP server increments the per-session error + before the Postfix SMTP server increments the per-session error count for each excess recipient. ACCESS POLICY DELEGATION CONTROLS - As of version 2.1, Postfix can be configured to delegate access policy - decisions to an external server that runs outside Postfix. See the + As of version 2.1, Postfix can be configured to delegate access policy + decisions to an external server that runs outside Postfix. See the file SMTPD_POLICY_README for more information. smtpd_policy_service_max_idle (300s) - The time after which an idle SMTPD policy service connection is + The time after which an idle SMTPD policy service connection is closed. smtpd_policy_service_max_ttl (1000s) - The time after which an active SMTPD policy service connection + The time after which an active SMTPD policy service connection is closed. smtpd_policy_service_timeout (100s) - The time limit for connecting to, writing to, or receiving from + The time limit for connecting to, writing to, or receiving from a delegated SMTPD policy server. Available in Postfix version 3.0 and later: @@ -976,81 +987,81 @@ SMTPD(8) SMTPD(8) The default action when an SMTPD policy service request fails. smtpd_policy_service_request_limit (0) - The maximal number of requests per SMTPD policy service connec- + The maximal number of requests per SMTPD policy service connec- tion, or zero (no limit). smtpd_policy_service_try_limit (2) - The maximal number of attempts to send an SMTPD policy service + The maximal number of attempts to send an SMTPD policy service request before giving up. smtpd_policy_service_retry_delay (1s) - The delay between attempts to resend a failed SMTPD policy ser- + The delay between attempts to resend a failed SMTPD policy ser- vice request. Available in Postfix version 3.1 and later: smtpd_policy_service_policy_context (empty) - Optional information that the Postfix SMTP server specifies in - the "policy_context" attribute of a policy service request - (originally, to share the same service endpoint among multiple + Optional information that the Postfix SMTP server specifies in + the "policy_context" attribute of a policy service request + (originally, to share the same service endpoint among multiple check_policy_service clients). ACCESS CONTROLS - The SMTPD_ACCESS_README document gives an introduction to all the SMTP + The SMTPD_ACCESS_README document gives an introduction to all the SMTP server access control features. smtpd_delay_reject (yes) - Wait until the RCPT TO command before evaluating + Wait until the RCPT TO command before evaluating $smtpd_client_restrictions, $smtpd_helo_restrictions and $smtpd_sender_restrictions, or wait until the ETRN command - before evaluating $smtpd_client_restrictions and + before evaluating $smtpd_client_restrictions and $smtpd_helo_restrictions. parent_domain_matches_subdomains (see 'postconf -d' output) - A list of Postfix features where the pattern "example.com" also - matches subdomains of example.com, instead of requiring an + A list of Postfix features where the pattern "example.com" also + matches subdomains of example.com, instead of requiring an explicit ".example.com" pattern. smtpd_client_restrictions (empty) - Optional restrictions that the Postfix SMTP server applies in + Optional restrictions that the Postfix SMTP server applies in the context of a client connection request. smtpd_helo_required (no) - Require that a remote SMTP client introduces itself with the - HELO or EHLO command before sending the MAIL command or other + Require that a remote SMTP client introduces itself with the + HELO or EHLO command before sending the MAIL command or other commands that require EHLO negotiation. smtpd_helo_restrictions (empty) - Optional restrictions that the Postfix SMTP server applies in + Optional restrictions that the Postfix SMTP server applies in the context of a client HELO command. smtpd_sender_restrictions (empty) - Optional restrictions that the Postfix SMTP server applies in + Optional restrictions that the Postfix SMTP server applies in the context of a client MAIL FROM command. smtpd_recipient_restrictions (see 'postconf -d' output) - Optional restrictions that the Postfix SMTP server applies in - the context of a client RCPT TO command, after + Optional restrictions that the Postfix SMTP server applies in + the context of a client RCPT TO command, after smtpd_relay_restrictions. smtpd_etrn_restrictions (empty) - Optional restrictions that the Postfix SMTP server applies in + Optional restrictions that the Postfix SMTP server applies in the context of a client ETRN command. allow_untrusted_routing (no) - Forward mail with sender-specified routing - (user[@%!]remote[@%!]site) from untrusted clients to destina- + Forward mail with sender-specified routing + (user[@%!]remote[@%!]site) from untrusted clients to destina- tions matching $relay_domains. smtpd_restriction_classes (empty) User-defined aliases for groups of access restrictions. smtpd_null_access_lookup_key (<>) - The lookup key to be used in SMTP access(5) tables instead of + The lookup key to be used in SMTP access(5) tables instead of the null sender address. permit_mx_backup_networks (empty) - Restrict the use of the permit_mx_backup SMTP access feature to + Restrict the use of the permit_mx_backup SMTP access feature to only domains whose primary MX hosts match the listed networks. Available in Postfix version 2.0 and later: @@ -1060,19 +1071,19 @@ SMTPD(8) SMTPD(8) applies in the context of the SMTP DATA command. smtpd_expansion_filter (see 'postconf -d' output) - What characters are allowed in $name expansions of RBL reply + What characters are allowed in $name expansions of RBL reply templates. Available in Postfix version 2.1 and later: smtpd_reject_unlisted_sender (no) - Request that the Postfix SMTP server rejects mail from unknown - sender addresses, even when no explicit reject_unlisted_sender + Request that the Postfix SMTP server rejects mail from unknown + sender addresses, even when no explicit reject_unlisted_sender access restriction is specified. smtpd_reject_unlisted_recipient (yes) - Request that the Postfix SMTP server rejects mail for unknown - recipient addresses, even when no explicit + Request that the Postfix SMTP server rejects mail for unknown + recipient addresses, even when no explicit reject_unlisted_recipient access restriction is specified. Available in Postfix version 2.2 and later: @@ -1086,17 +1097,17 @@ SMTPD(8) SMTPD(8) smtpd_relay_restrictions (permit_mynetworks, permit_sasl_authenticated, defer_unauth_destination) Access restrictions for mail relay control that the Postfix SMTP - server applies in the context of the RCPT TO command, before + server applies in the context of the RCPT TO command, before smtpd_recipient_restrictions. SENDER AND RECIPIENT ADDRESS VERIFICATION CONTROLS - Postfix version 2.1 introduces sender and recipient address verifica- + Postfix version 2.1 introduces sender and recipient address verifica- tion. This feature is implemented by sending probe email messages that are not actually delivered. This feature is requested via the - reject_unverified_sender and reject_unverified_recipient access - restrictions. The status of verification probes is maintained by the - verify(8) server. See the file ADDRESS_VERIFICATION_README for infor- - mation about how to configure and operate the Postfix sender/recipient + reject_unverified_sender and reject_unverified_recipient access + restrictions. The status of verification probes is maintained by the + verify(8) server. See the file ADDRESS_VERIFICATION_README for infor- + mation about how to configure and operate the Postfix sender/recipient address verification service. address_verify_poll_count (normal: 3, overload: 1) @@ -1108,7 +1119,7 @@ SMTPD(8) SMTPD(8) fication request in progress. address_verify_sender ($double_bounce_sender) - The sender address to use in address verification probes; prior + The sender address to use in address verification probes; prior to Postfix 2.5 the default was "postmaster". unverified_sender_reject_code (450) @@ -1116,18 +1127,18 @@ SMTPD(8) SMTPD(8) address is rejected by the reject_unverified_sender restriction. unverified_recipient_reject_code (450) - The numerical Postfix SMTP server response when a recipient - address is rejected by the reject_unverified_recipient restric- + The numerical Postfix SMTP server response when a recipient + address is rejected by the reject_unverified_recipient restric- tion. Available in Postfix version 2.6 and later: unverified_sender_defer_code (450) - The numerical Postfix SMTP server response code when a sender + The numerical Postfix SMTP server response code when a sender address probe fails due to a temporary error condition. unverified_recipient_defer_code (450) - The numerical Postfix SMTP server response when a recipient + The numerical Postfix SMTP server response when a recipient address probe fails due to a temporary error condition. unverified_sender_reject_reason (empty) @@ -1139,17 +1150,17 @@ SMTPD(8) SMTPD(8) reject_unverified_recipient. unverified_sender_tempfail_action ($reject_tempfail_action) - The Postfix SMTP server's action when reject_unverified_sender + The Postfix SMTP server's action when reject_unverified_sender fails due to a temporary error condition. unverified_recipient_tempfail_action ($reject_tempfail_action) - The Postfix SMTP server's action when reject_unverified_recipi- + The Postfix SMTP server's action when reject_unverified_recipi- ent fails due to a temporary error condition. Available with Postfix 2.9 and later: address_verify_sender_ttl (0s) - The time between changes in the time-dependent portion of + The time between changes in the time-dependent portion of address verification probe sender addresses. ACCESS CONTROL RESPONSES @@ -1161,36 +1172,36 @@ SMTPD(8) SMTPD(8) map "reject" action. defer_code (450) - The numerical Postfix SMTP server response code when a remote + The numerical Postfix SMTP server response code when a remote SMTP client request is rejected by the "defer" restriction. invalid_hostname_reject_code (501) - The numerical Postfix SMTP server response code when the client - HELO or EHLO command parameter is rejected by the + The numerical Postfix SMTP server response code when the client + HELO or EHLO command parameter is rejected by the reject_invalid_helo_hostname restriction. maps_rbl_reject_code (554) - The numerical Postfix SMTP server response code when a remote - SMTP client request is blocked by the reject_rbl_client, + The numerical Postfix SMTP server response code when a remote + SMTP client request is blocked by the reject_rbl_client, reject_rhsbl_client, reject_rhsbl_reverse_client, reject_rhsbl_sender or reject_rhsbl_recipient restriction. non_fqdn_reject_code (504) - The numerical Postfix SMTP server reply code when a client - request is rejected by the reject_non_fqdn_helo_hostname, + The numerical Postfix SMTP server reply code when a client + request is rejected by the reject_non_fqdn_helo_hostname, reject_non_fqdn_sender or reject_non_fqdn_recipient restriction. plaintext_reject_code (450) - The numerical Postfix SMTP server response code when a request + The numerical Postfix SMTP server response code when a request is rejected by the reject_plaintext_session restriction. reject_code (554) - The numerical Postfix SMTP server response code when a remote + The numerical Postfix SMTP server response code when a remote SMTP client request is rejected by the "reject" restriction. relay_domains_reject_code (554) - The numerical Postfix SMTP server response code when a client - request is rejected by the reject_unauth_destination recipient + The numerical Postfix SMTP server response code when a client + request is rejected by the reject_unauth_destination recipient restriction. unknown_address_reject_code (450) @@ -1198,24 +1209,24 @@ SMTPD(8) SMTPD(8) a sender or recipient address because its domain is unknown. unknown_client_reject_code (450) - The numerical Postfix SMTP server response code when a client - without valid address <=> name mapping is rejected by the + The numerical Postfix SMTP server response code when a client + without valid address <=> name mapping is rejected by the reject_unknown_client_hostname restriction. unknown_hostname_reject_code (450) - The numerical Postfix SMTP server response code when the host- - name specified with the HELO or EHLO command is rejected by the + The numerical Postfix SMTP server response code when the host- + name specified with the HELO or EHLO command is rejected by the reject_unknown_helo_hostname restriction. Available in Postfix version 2.0 and later: default_rbl_reply (see 'postconf -d' output) - The default Postfix SMTP server response template for a request + The default Postfix SMTP server response template for a request that is rejected by an RBL-based restriction. multi_recipient_bounce_reject_code (550) - The numerical Postfix SMTP server response code when a remote - SMTP client request is blocked by the reject_multi_recipi- + The numerical Postfix SMTP server response code when a remote + SMTP client request is blocked by the reject_multi_recipi- ent_bounce restriction. rbl_reply_maps (empty) @@ -1225,52 +1236,52 @@ SMTPD(8) SMTPD(8) access_map_defer_code (450) The numerical Postfix SMTP server response code for an access(5) - map "defer" action, including "defer_if_permit" or + map "defer" action, including "defer_if_permit" or "defer_if_reject". reject_tempfail_action (defer_if_permit) - The Postfix SMTP server's action when a reject-type restriction + The Postfix SMTP server's action when a reject-type restriction fails due to a temporary error condition. unknown_helo_hostname_tempfail_action ($reject_tempfail_action) - The Postfix SMTP server's action when reject_unknown_helo_host- + The Postfix SMTP server's action when reject_unknown_helo_host- name fails due to a temporary error condition. unknown_address_tempfail_action ($reject_tempfail_action) - The Postfix SMTP server's action when - reject_unknown_sender_domain or reject_unknown_recipient_domain + The Postfix SMTP server's action when + reject_unknown_sender_domain or reject_unknown_recipient_domain fail due to a temporary error condition. MISCELLANEOUS CONTROLS config_directory (see 'postconf -d' output) - The default location of the Postfix main.cf and master.cf con- + The default location of the Postfix main.cf and master.cf con- figuration files. daemon_timeout (18000s) - How much time a Postfix daemon process may take to handle a + How much time a Postfix daemon process may take to handle a request before it is terminated by a built-in watchdog timer. command_directory (see 'postconf -d' output) The location of all postfix administrative commands. double_bounce_sender (double-bounce) - The sender address of postmaster notifications that are gener- + The sender address of postmaster notifications that are gener- ated by the mail system. ipc_timeout (3600s) - The time limit for sending or receiving information over an + The time limit for sending or receiving information over an internal communication channel. mail_name (Postfix) - The mail system name that is displayed in Received: headers, in + The mail system name that is displayed in Received: headers, in the SMTP greeting banner, and in bounced mail. mail_owner (postfix) - The UNIX system account that owns the Postfix queue and most + The UNIX system account that owns the Postfix queue and most Postfix daemon processes. max_idle (100s) - The maximum amount of time that an idle Postfix daemon process + The maximum amount of time that an idle Postfix daemon process waits for an incoming connection before terminating voluntarily. max_use (100) @@ -1281,11 +1292,11 @@ SMTPD(8) SMTPD(8) The internet hostname of this mail system. mynetworks (see 'postconf -d' output) - The list of "trusted" remote SMTP clients that have more privi- + The list of "trusted" remote SMTP clients that have more privi- leges than "strangers". myorigin ($myhostname) - The domain name that locally-posted mail appears to come from, + The domain name that locally-posted mail appears to come from, and that locally posted mail is delivered to. process_id (read-only) @@ -1298,25 +1309,25 @@ SMTPD(8) SMTPD(8) The location of the Postfix top-level queue directory. recipient_delimiter (empty) - The set of characters that can separate a user name from its - extension (example: user+foo), or a .forward file name from its + The set of characters that can separate a user name from its + extension (example: user+foo), or a .forward file name from its extension (example: .forward+foo). smtpd_banner ($myhostname ESMTP $mail_name) - The text that follows the 220 status code in the SMTP greeting + The text that follows the 220 status code in the SMTP greeting banner. syslog_facility (mail) The syslog facility of Postfix logging. syslog_name (see 'postconf -d' output) - A prefix that is prepended to the process name in syslog + A prefix that is prepended to the process name in syslog records, so that, for example, "smtpd" becomes "prefix/smtpd". Available in Postfix version 2.2 and later: smtpd_forbidden_commands (CONNECT, GET, POST) - List of commands that cause the Postfix SMTP server to immedi- + List of commands that cause the Postfix SMTP server to immedi- ately terminate the session with a 221 code. Available in Postfix version 2.5 and later: @@ -1333,7 +1344,7 @@ SMTPD(8) SMTPD(8) Available in Postfix 3.4 and later: smtpd_reject_footer_maps (empty) - Lookup tables, indexed by the complete Postfix SMTP server 4xx + Lookup tables, indexed by the complete Postfix SMTP server 4xx or 5xx response, with reject footer templates. SEE ALSO diff --git a/postfix/man/man5/postconf.5 b/postfix/man/man5/postconf.5 index d2150dac6..10e4f2c53 100644 --- a/postfix/man/man5/postconf.5 +++ b/postfix/man/man5/postconf.5 @@ -10206,6 +10206,61 @@ The smtpd_expansion_filter value is not subject to Postfix configuration parameter $name expansion. .PP This feature is available in Postfix 2.0 and later. +.SH smtpd_forbid_bare_newline (default: Postfix < 3.9: no) +Reply with "Error: bare received" and disconnect +when a remote SMTP client sends a line ending in , violating +the RFC 5321 requirement that lines must end in . +This feature is disbled by default with Postfix < 3.9. Use +smtpd_forbid_bare_newline_exclusions to exclude non\-standard clients +such as netcat. Specify "smtpd_forbid_bare_newline = no" to disable +(not recommended for an Internet\-connected MTA). +.PP +See +https://www.postfix.org/smtp\-smuggling.html for details. +.PP +Example: +.sp +.in +4 +.nf +.na +.ft C +# Disconnect remote SMTP clients that send bare newlines, but allow +# local clients with non\-standard SMTP implementations such as netcat, +# fax machines, or load balancer health checks. +# +smtpd_forbid_bare_newline = yes +smtpd_forbid_bare_newline_exclusions = $mynetworks +.fi +.ad +.ft R +.in -4 +.PP +This feature is available in Postfix >= 3.9, 3.8.4, 3.7.9, +3.6.13, and 3.5.23. +.SH smtpd_forbid_bare_newline_exclusions (default: $mynetworks) +Exclude the specified clients from smtpd_forbid_bare_newline +enforcement. It uses the same syntax and parent\-domain matching +behavior as mynetworks. +.PP +Example: +.sp +.in +4 +.nf +.na +.ft C +# Disconnect remote SMTP clients that send bare newlines, but allow +# local clients with non\-standard SMTP implementations such as netcat, +# fax machines, or load balancer health checks. +# +smtpd_forbid_bare_newline = yes +smtpd_forbid_bare_newline_exclusions = $mynetworks +.fi +.ad +.ft R +.in -4 +.PP +This feature is available in Postfix >= 3.9, 3.8.4, 3.7.9, +3.6.13, and 3.5.23. .SH smtpd_forbid_unauth_pipelining (default: Postfix >= 3.9: yes) Disconnect remote SMTP clients that violate RFC 2920 (or 5321) command pipelining constraints. The server replies with "554 5.5.0 diff --git a/postfix/man/man8/smtpd.8 b/postfix/man/man8/smtpd.8 index 8a4ba20d0..9745d16f1 100644 --- a/postfix/man/man8/smtpd.8 +++ b/postfix/man/man8/smtpd.8 @@ -809,6 +809,15 @@ Available in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later: .IP "\fBsmtpd_forbid_unauth_pipelining (Postfix >= 3.9: yes)\fR" Disconnect remote SMTP clients that violate RFC 2920 (or 5321) command pipelining constraints. +.PP +Available in Postfix 3.9, 3.8.4, 3.7.9, 3.6.13, 3.5.23 and later: +.IP "\fBsmtpd_forbid_bare_newline (Postfix < 3.9: no)\fR" +Reply with "Error: bare received" and disconnect +when a remote SMTP client sends a line ending in , violating +the RFC 5321 requirement that lines must end in . +.IP "\fBsmtpd_forbid_bare_newline_exclusions ($mynetworks)\fR" +Exclude the specified clients from smtpd_forbid_bare_newline +enforcement. .SH "TARPIT CONTROLS" .na .nf diff --git a/postfix/mantools/postlink b/postfix/mantools/postlink index f93d5e6fa..8d70f26e9 100755 --- a/postfix/mantools/postlink +++ b/postfix/mantools/postlink @@ -548,6 +548,8 @@ while (<>) { s;\bsmtpd_etrn_restrictions\b;$&;g; s;\bsmtpd_expansion_filter\b;$&;g; s;\bsmtpd_for[-]*\n*[ ]*bidden_commands\b;$&;g; + s;\bsmtpd_for[-]*\n*[ ]*bid_bare_newline\b;$&;g; + s;\bsmtpd_for[-]*\n*[ ]*bid_bare_newline_exclusions\b;$&;g; s;\bsmtpd_for[-]*\n*[ ]*bid_unauth_pipelining\b;$&;g; s;\bsmtpd_hard_error_limit\b;$&;g; s;\bsmtpd_helo_required\b;$&;g; diff --git a/postfix/proto/postconf.proto b/postfix/proto/postconf.proto index c6af1b38e..3d43f2323 100644 --- a/postfix/proto/postconf.proto +++ b/postfix/proto/postconf.proto @@ -17863,6 +17863,57 @@ MinProtocol = TLSv1

This feature is available in Postfix ≥ 3.9, 3.8.1, 3.7.6, 3.6.10, and 3.5.20.

+%PARAM smtpd_forbid_bare_newline Postfix < 3.9: no + +

Reply with "Error: bare <LF> received" and disconnect +when a remote SMTP client sends a line ending in <LF>, violating +the RFC 5321 requirement that lines must end in <CR><LF>. +This feature is disbled by default with Postfix < 3.9. Use +smtpd_forbid_bare_newline_exclusions to exclude non-standard clients +such as netcat. Specify "smtpd_forbid_bare_newline = no" to disable +(not recommended for an Internet-connected MTA).

+ +

See +https://www.postfix.org/smtp-smuggling.html for details. + +

Example:

+ +
+
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+
+
+ +

This feature is available in Postfix ≥ 3.9, 3.8.4, 3.7.9, +3.6.13, and 3.5.23.

+ +%PARAM smtpd_forbid_bare_newline_exclusions $mynetworks + +

Exclude the specified clients from smtpd_forbid_bare_newline +enforcement. It uses the same syntax and parent-domain matching +behavior as mynetworks.

+ +

Example:

+ +
+
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+
+
+ +

This feature is available in Postfix ≥ 3.9, 3.8.4, 3.7.9, +3.6.13, and 3.5.23.

+ %PARAM smtpd_forbid_unauth_pipelining Postfix ≥ 3.9: yes

Disconnect remote SMTP clients that violate RFC 2920 (or 5321) diff --git a/postfix/src/global/mail_params.h b/postfix/src/global/mail_params.h index ccf0b259b..87973bd41 100644 --- a/postfix/src/global/mail_params.h +++ b/postfix/src/global/mail_params.h @@ -4142,7 +4142,16 @@ extern char *var_smtp_dns_re_filter; extern char *var_smtpd_dns_re_filter; /* - * Share TLS sessions through tlproxy(8). + * Backwards compatibility. + */ +#define VAR_SMTPD_FORBID_BARE_LF "smtpd_forbid_bare_newline" +#define DEF_SMTPD_FORBID_BARE_LF 0 + +#define VAR_SMTPD_FORBID_BARE_LF_EXCL "smtpd_forbid_bare_newline_exclusions" +#define DEF_SMTPD_FORBID_BARE_LF_EXCL "$" VAR_MYNETWORKS + + /* + * Share TLS sessions through tlsproxy(8). */ #define VAR_SMTP_TLS_CONN_REUSE "smtp_tls_connection_reuse" #define DEF_SMTP_TLS_CONN_REUSE 0 diff --git a/postfix/src/global/mail_version.h b/postfix/src/global/mail_version.h index e7aaad923..6332387b7 100644 --- a/postfix/src/global/mail_version.h +++ b/postfix/src/global/mail_version.h @@ -20,8 +20,8 @@ * Patches change both the patchlevel and the release date. Snapshots have no * patchlevel; they change the release date only. */ -#define MAIL_RELEASE_DATE "20231101" -#define MAIL_VERSION_NUMBER "3.5.22" +#define MAIL_RELEASE_DATE "20231222" +#define MAIL_VERSION_NUMBER "3.5.23" #ifdef SNAPSHOT #define MAIL_VERSION_DATE "-" MAIL_RELEASE_DATE diff --git a/postfix/src/global/smtp_stream.c b/postfix/src/global/smtp_stream.c index a42cdcfd2..cb611d1b2 100644 --- a/postfix/src/global/smtp_stream.c +++ b/postfix/src/global/smtp_stream.c @@ -50,6 +50,8 @@ /* VSTREAM *stream; /* char *format; /* va_list ap; +/* +/* int smtp_forbid_bare_lf; /* AUXILIARY API /* int smtp_get_noexcept(vp, stream, maxlen, flags) /* VSTRING *vp; @@ -124,11 +126,16 @@ /* smtp_vprintf() is the machine underneath smtp_printf(). /* /* smtp_get_noexcept() implements the subset of smtp_get() -/* without timeouts and without making long jumps. Instead, +/* without long jumps for timeout or EOF errors. Instead, /* query the stream status with vstream_feof() etc. +/* This function will make a VSTREAM long jump (error code +/* SMTP_ERR_LF) when rejecting input with a bare newline byte. /* /* smtp_timeout_setup() is a backwards-compatibility interface /* for programs that don't require per-record deadline support. +/* +/* smtp_forbid_bare_lf controls whether smtp_get_noexcept() +/* will reject input with a bare newline byte. /* DIAGNOSTICS /* .fi /* .ad @@ -201,6 +208,8 @@ #include "smtp_stream.h" +int smtp_forbid_bare_lf; + /* smtp_timeout_reset - reset per-stream error flags, restart deadline timer */ static void smtp_timeout_reset(VSTREAM *stream) @@ -404,6 +413,9 @@ int smtp_get_noexcept(VSTRING *vp, VSTREAM *stream, ssize_t bound, int flags */ case '\n': vstring_truncate(vp, VSTRING_LEN(vp) - 1); + if (smtp_forbid_bare_lf + && (VSTRING_LEN(vp) == 0 || vstring_end(vp)[-1] != '\r')) + vstream_longjmp(stream, SMTP_ERR_LF); while (VSTRING_LEN(vp) > 0 && vstring_end(vp)[-1] == '\r') vstring_truncate(vp, VSTRING_LEN(vp) - 1); VSTRING_TERMINATE(vp); diff --git a/postfix/src/global/smtp_stream.h b/postfix/src/global/smtp_stream.h index ec824b3c3..da1c68af8 100644 --- a/postfix/src/global/smtp_stream.h +++ b/postfix/src/global/smtp_stream.h @@ -32,6 +32,7 @@ #define SMTP_ERR_QUIET 3 /* silent cleanup (application) */ #define SMTP_ERR_NONE 4 /* non-error case */ #define SMTP_ERR_DATA 5 /* application data error */ +#define SMTP_ERR_LF 6 /* bare protocol error */ extern void smtp_stream_setup(VSTREAM *, int, int); extern void PRINTFLIKE(2, 3) smtp_printf(VSTREAM *, const char *,...); @@ -43,6 +44,7 @@ extern void smtp_fputs(const char *, ssize_t len, VSTREAM *); extern void smtp_fwrite(const char *, ssize_t len, VSTREAM *); extern void smtp_fread_buf(VSTRING *, ssize_t len, VSTREAM *); extern void smtp_fputc(int, VSTREAM *); +extern int smtp_forbid_bare_lf; extern void smtp_vprintf(VSTREAM *, const char *, va_list); diff --git a/postfix/src/smtpd/smtpd.c b/postfix/src/smtpd/smtpd.c index d3baac0f3..7a75020c2 100644 --- a/postfix/src/smtpd/smtpd.c +++ b/postfix/src/smtpd/smtpd.c @@ -763,6 +763,15 @@ /* .IP "\fBsmtpd_forbid_unauth_pipelining (Postfix >= 3.9: yes)\fR" /* Disconnect remote SMTP clients that violate RFC 2920 (or 5321) /* command pipelining constraints. +/* .PP +/* Available in Postfix 3.9, 3.8.4, 3.7.9, 3.6.13, 3.5.23 and later: +/* .IP "\fBsmtpd_forbid_bare_newline (Postfix < 3.9: no)\fR" +/* Reply with "Error: bare received" and disconnect +/* when a remote SMTP client sends a line ending in , violating +/* the RFC 5321 requirement that lines must end in . +/* .IP "\fBsmtpd_forbid_bare_newline_exclusions ($mynetworks)\fR" +/* Exclude the specified clients from smtpd_forbid_bare_newline +/* enforcement. /* TARPIT CONTROLS /* .ad /* .fi @@ -1468,6 +1477,10 @@ char *var_tlsproxy_service; char *var_smtpd_uproxy_proto; int var_smtpd_uproxy_tmout; +bool var_smtpd_forbid_bare_lf; +char *var_smtpd_forbid_bare_lf_excl; +static NAMADR_LIST *bare_lf_excl; + /* * Silly little macros. */ @@ -1542,6 +1555,7 @@ static void tls_reset(SMTPD_STATE *); #define REASON_TIMEOUT "timeout" #define REASON_LOST_CONNECTION "lost connection" #define REASON_ERROR_LIMIT "too many errors" +#define REASON_BARE_LF "bare received" #ifdef USE_TLS @@ -3968,6 +3982,7 @@ static int bdat_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv) */ done = 0; do { + int payload_err; /* * Do not skip the smtp_fread_buf() call if read_len == 0. We still @@ -3981,6 +3996,10 @@ static int bdat_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv) smtp_fread_buf(state->buffer, read_len, state->client); state->bdat_get_stream = vstream_memreopen( state->bdat_get_stream, state->buffer, O_RDONLY); + vstream_control(state->bdat_get_stream, CA_VSTREAM_CTL_EXCEPT, + CA_VSTREAM_CTL_END); + if ((payload_err = vstream_setjmp(state->bdat_get_stream)) != 0) + vstream_longjmp(state->client, payload_err); /* * Read lines from the fragment. The last line may continue in the @@ -4656,6 +4675,9 @@ static int xclient_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv) */ xclient_allowed = namadr_list_match(xclient_hosts, state->name, state->addr); + smtp_forbid_bare_lf = SMTPD_STAND_ALONE((state)) == 0 + && var_smtpd_forbid_bare_lf + && !namadr_list_match(bare_lf_excl, state->name, state->addr); /* NOT: tls_reset() */ if (got_helo == 0) helo_reset(state); @@ -5474,6 +5496,13 @@ static void smtpd_proto(SMTPD_STATE *state) var_myhostname); break; + case SMTP_ERR_LF: + state->reason = REASON_BARE_LF; + if (vstream_setjmp(state->client) == 0) + smtpd_chat_reply(state, "521 5.5.2 %s Error: bare received", + var_myhostname); + break; + case 0: /* @@ -6032,6 +6061,13 @@ static void smtpd_service(VSTREAM *stream, char *service, char **argv) xforward_allowed = SMTPD_STAND_ALONE((&state)) == 0 && namadr_list_match(xforward_hosts, state.name, state.addr); + /* + * Enforce strict SMTP line endings, with compatibility exclusions. + */ + smtp_forbid_bare_lf = SMTPD_STAND_ALONE((&state)) == 0 + && var_smtpd_forbid_bare_lf + && !namadr_list_match(bare_lf_excl, state.name, state.addr); + /* * See if we need to turn on verbose logging for this client. */ @@ -6093,6 +6129,10 @@ static void pre_jail_init(char *unused_name, char **unused_argv) hogger_list = namadr_list_init(VAR_SMTPD_HOGGERS, MATCH_FLAG_RETURN | match_parent_style(VAR_SMTPD_HOGGERS), var_smtpd_hoggers); + bare_lf_excl = namadr_list_init(VAR_SMTPD_FORBID_BARE_LF_EXCL, + MATCH_FLAG_RETURN + | match_parent_style(VAR_MYNETWORKS), + var_smtpd_forbid_bare_lf_excl); /* * Open maps before dropping privileges so we can read passwords etc. @@ -6451,6 +6491,7 @@ int main(int argc, char **argv) VAR_SMTPD_DELAY_OPEN, DEF_SMTPD_DELAY_OPEN, &var_smtpd_delay_open, VAR_SMTPD_CLIENT_PORT_LOG, DEF_SMTPD_CLIENT_PORT_LOG, &var_smtpd_client_port_log, VAR_SMTPD_FORBID_UNAUTH_PIPE, DEF_SMTPD_FORBID_UNAUTH_PIPE, &var_smtpd_forbid_unauth_pipe, + VAR_SMTPD_FORBID_BARE_LF, DEF_SMTPD_FORBID_BARE_LF, &var_smtpd_forbid_bare_lf, 0, }; static const CONFIG_NBOOL_TABLE nbool_table[] = { @@ -6564,6 +6605,7 @@ int main(int argc, char **argv) VAR_SMTPD_POLICY_CONTEXT, DEF_SMTPD_POLICY_CONTEXT, &var_smtpd_policy_context, 0, 0, VAR_SMTPD_DNS_RE_FILTER, DEF_SMTPD_DNS_RE_FILTER, &var_smtpd_dns_re_filter, 0, 0, VAR_SMTPD_REJ_FTR_MAPS, DEF_SMTPD_REJ_FTR_MAPS, &var_smtpd_rej_ftr_maps, 0, 0, + VAR_SMTPD_FORBID_BARE_LF_EXCL, DEF_SMTPD_FORBID_BARE_LF_EXCL, &var_smtpd_forbid_bare_lf_excl, 0, 0, 0, }; static const CONFIG_RAW_TABLE raw_table[] = {