From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 7172091B05 for ; Thu, 15 Feb 2024 20:21:45 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 417C318D2E for ; Thu, 15 Feb 2024 20:21:15 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS for ; Thu, 15 Feb 2024 20:21:13 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 6B99F48488 for ; Thu, 15 Feb 2024 20:21:13 +0100 (CET) Date: Thu, 15 Feb 2024 20:21:11 +0100 From: Stoiko Ivanov To: Maximiliano Sandoval Cc: pmg-devel@lists.proxmox.com Message-ID: <20240215202111.02c71819@rosa.proxmox.com> In-Reply-To: <20240116104301.247166-1-m.sandoval@proxmox.com> References: <20240116104301.247166-1-m.sandoval@proxmox.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.086 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record T_SCC_BODY_TEXT_LINE -0.01 - URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [dkimsign.pm, ietf.org, accept.pm, opendkim.org, proxmox.com, jetmore.org, rspamd.com, bcc.pm, config.pm] Subject: Re: [pmg-devel] [PATCH pmg-api v4] fix-2971: DKIM: Add setting to use From header when signing X-BeenThere: pmg-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Mail Gateway development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Feb 2024 19:21:45 -0000 Thanks for the update! I got around to give it a spin in my testbed - and it looks ok from a quick spin. The docs-patch would be great for the next version! a few comments inline: On Tue, 16 Jan 2024 11:43:01 +0100 Maximiliano Sandoval wrote: > We add an option to use the address from the `From:` header instead of > the Envelope From address. Following RFC 5322 [2], we use the `Sender:` > header when there are multiple addresses in the `From:` header. > > From RFC 7489 [1]: > > To illustrate, in relaxed mode, if a validated DKIM signature > successfully verifies with a "d=" domain of "example.com", and the > RFC5322.From address is "alerts@news.example.com", the DKIM "d=" > domain and the RFC5322.From domain are considered to be "in > alignment". In strict mode, this test would fail, since the "d=" > domain does not exactly match the FQDN of the address. > > Tested with the following command: > > swaks --from foo@bar1 --to EMAIL -s PMG_ADDR:26 --data "Date: %DATE%\nTo: %TO_ADDRESS%\nFrom: foo@bar2\nSubject: test %DATE%\nMessage-Id: <%MESSAGEID%>\nX-Mailer: swaks v%SWAKS_VERSION% jetmore.org/john/code/swaks/\n%NEW_HEADERS%\n%BODY%\n" > > [1] https://datatracker.ietf.org/doc/html/rfc7489#section-3.1.1 > [2] https://datatracker.ietf.org/doc/html/rfc5322#section-3.6.2 > > Signed-off-by: Maximiliano Sandoval > --- > Do note that for testing one has to restart pmg-smtp-filter after changing the setting value. > > Differences from v3: > - Take into account setting > - rename parsing function to parse_headers_for_signing > > src/PMG/Config.pm | 7 ++++ > src/PMG/DKIMSign.pm | 72 ++++++++++++++++++++++++++++++++++++---- > src/PMG/RuleDB/Accept.pm | 3 +- > src/PMG/RuleDB/BCC.pm | 3 +- > src/bin/pmg-smtp-filter | 1 + > 5 files changed, 75 insertions(+), 11 deletions(-) > > diff --git a/src/PMG/Config.pm b/src/PMG/Config.pm > index 7339e0d..840c0ad 100644 > --- a/src/PMG/Config.pm > +++ b/src/PMG/Config.pm > @@ -134,6 +134,11 @@ EODESC > description => "Default DKIM selector", > type => 'string', format => 'dns-name', #see RFC6376 3.1 > }, > + dkim_prefer_rfc5322_domain => { I checked what others do for those hard-to-name things - maybe we could orient ourselves on other mail-filters: * https://rspamd.com/doc/modules/dkim_signing.html (dkim_use_domain a enum with "envelope" and "header") - one upside is that that will remain a term even if RFC5322 is obsoleted at some future point... * opendkim seems to only use header information (but lets you select the headers, which are search, which I'd like to avoid for usage-simplicity) - http://opendkim.org/opendkim.conf.5.html > + description => "Whether to use the address from the From header when DKIM signing outbound mails.", > + type => 'boolean', > + default => 0, > + }, > }; > } > > @@ -152,6 +157,7 @@ sub options { > dkim_sign => { optional => 1 }, > dkim_sign_all_mail => { optional => 1 }, > dkim_selector => { optional => 1 }, > + dkim_prefer_rfc5322_domain => { optional => 1 }, > }; > } > > @@ -1788,6 +1794,7 @@ my $pmg_service_params = { > dkim_selector => 1, > dkim_sign => 1, > dkim_sign_all_mail => 1, > + dkim_prefer_rfc5322_domain => 1, > }, > }; > > diff --git a/src/PMG/DKIMSign.pm b/src/PMG/DKIMSign.pm > index 08197f8..2c73101 100644 > --- a/src/PMG/DKIMSign.pm > +++ b/src/PMG/DKIMSign.pm > @@ -2,6 +2,7 @@ package PMG::DKIMSign; > > use strict; > use warnings; > +use Email::Address::XS; > use Mail::DKIM::Signer; > use Mail::DKIM::TextWrap; > use Crypt::OpenSSL::RSA; > @@ -53,11 +54,16 @@ sub create_signature { > > #determines which domain should be used for signing based on the e-mailaddress > sub signing_domain { > - my ($self, $sender_email) = @_; > - > - my @parts = split('@', $sender_email); > - die "no domain in sender e-mail\n" if scalar(@parts) < 2; > - my $input_domain = $parts[-1]; > + my ($self, $sender_email, $entity, $prefer_rfc5322_domain) = @_; > + > + my $input_domain; > + if ($prefer_rfc5322_domain) { > + $input_domain = parse_headers_for_signing($entity); > + } else { > + my @parts = split('@', $sender_email); > + die "no domain in sender e-mail\n" if scalar(@parts) < 2; > + $input_domain = $parts[-1]; > + } > > if ($self->{sign_all}) { > $self->domain($input_domain) if $self->{sign_all}; > @@ -84,8 +90,60 @@ sub signing_domain { > } > > > +sub parse_headers_for_signing { > + # If there is exactly one single address in the 'From' header we use that > + # address for signing, otherwise we use the 'Sender' header. as hinted in my reply to your v1: https://lists.proxmox.com/pipermail/pmg-devel/2024-January/002625.html if I read the DMARC-RFC right this fallback is not wanted there (and DKIM itself does not mention that the dkim-domain (d= tag in the signature header, would need to be particularly related to either header or envelope-addresses) > + my ($entity) = @_; > + > + my @sender_list; > + my @from_list; > + > + my @from_headers = $entity->head->get('from'); > + foreach my $from_header (@from_headers) { > + my @senders = Email::Address::XS->parse($from_header); > + foreach my $sender (@senders) { > + push(@from_list, @senders); > + } > + } > + my $from_count = scalar(@from_list); > + > + if ($from_count > 1) { > + my @send_headers = $entity->head->get('sender'); > + foreach my $send_header (@send_headers) { > + my @senders = Email::Address::XS->parse($send_header); > + foreach my $sender (@senders) { > + push(@sender_list, $sender); > + } > + } > + my $send_count = scalar(@sender_list); > + > + if ($send_count > 1) { > + syslog( > + 'warning', > + "Email has more than one address in its 'Sender' it won't be signed." > + ." See RFC 5322 Section 3.6.2" > + ); > + } elsif ($send_count == 1) { > + return $sender_list[0]->host(); > + } else { > + syslog( > + 'warning', > + "Email has multiple addresses in its 'From' header and no 'Sender'" > + ." header, it won't be signed. See RFC 5322 Section 3.6.2" > + ); > + } > + } elsif ($from_count == 1) { > + return $from_list[0]->host(); > + } > +} > + > + > sub sign_entity { > - my ($entity, $selector, $sender, $sign_all) = @_; > + my ($entity, $dkim, $sender) = @_; > + > + my $sign_all = $dkim->{sign_all}; > + my $prefer_rfc5322_domain = $dkim->{prefer_rfc5322_domain}; > + my $selector = $dkim->{selector}; > > die "no selector provided\n" if ! $selector; > > @@ -110,7 +168,7 @@ sub sign_entity { > > $signer->extended_headers($extended_headers); > > - if ($signer->signing_domain($sender)) { > + if ($signer->signing_domain($sender, $entity, $prefer_rfc5322_domain)) { > $entity->print($signer); > my $signature = $signer->create_signature(); > $entity->head->add('DKIM-Signature', $signature, 0); > diff --git a/src/PMG/RuleDB/Accept.pm b/src/PMG/RuleDB/Accept.pm > index 4ebd6da..d14c2fb 100644 > --- a/src/PMG/RuleDB/Accept.pm > +++ b/src/PMG/RuleDB/Accept.pm > @@ -102,8 +102,7 @@ sub execute { > > if ($dkim->{sign}) { > eval { > - $entity = PMG::DKIMSign::sign_entity($entity, > - $dkim->{selector}, $msginfo->{sender}, $dkim->{sign_all}); > + $entity = PMG::DKIMSign::sign_entity($entity, $dkim, $msginfo->{sender}); > }; > syslog('warning', > "Could not create DKIM-Signature - disabling Signing: $@") if $@; > diff --git a/src/PMG/RuleDB/BCC.pm b/src/PMG/RuleDB/BCC.pm > index 0f016f8..65b6fb5 100644 > --- a/src/PMG/RuleDB/BCC.pm > +++ b/src/PMG/RuleDB/BCC.pm > @@ -142,8 +142,7 @@ sub execute { > my $dkim = $msginfo->{dkim} // {}; > if ($dkim->{sign}) { > eval { > - $entity = PMG::DKIMSign::sign_entity($entity, > - $dkim->{selector}, $msginfo->{sender}, $dkim->{sign_all}); > + $entity = PMG::DKIMSign::sign_entity($entity, $dkim, $msginfo->{sender}); > }; > syslog('warning', > "Could not create DKIM-Signature - disabling Signing: $@") if $@; > diff --git a/src/bin/pmg-smtp-filter b/src/bin/pmg-smtp-filter > index 7da3de8..f7502f2 100755 > --- a/src/bin/pmg-smtp-filter > +++ b/src/bin/pmg-smtp-filter > @@ -627,6 +627,7 @@ sub handle_smtp { > my $dkim_sign = $msginfo->{trusted} && $pmg_cfg->get('admin', 'dkim_sign'); > if ($dkim_sign) { > $msginfo->{dkim}->{sign} = $dkim_sign; > + $msginfo->{dkim}->{prefer_rfc5322_domain} = $pmg_cfg->get('admin', 'dkim_prefer_rfc5322_domain'); > $msginfo->{dkim}->{sign_all} = $pmg_cfg->get('admin', 'dkim_sign_all_mail'); > $msginfo->{dkim}->{selector} = $pmg_cfg->get('admin', 'dkim_selector'); > }