X-Git-Url: https://git.distorted.org.uk/~mdw/exim-config/blobdiff_plain/75c86bd182115940b3613352b00af423e4c0743b..HEAD:/base.m4

diff --git a/base.m4 b/base.m4
index 63d001c..d64b88b 100644
--- a/base.m4
+++ b/base.m4
@@ -44,6 +44,7 @@ extra_local_interfaces = <; 0.0.0.0 ; ::0
 
 SECTION(global, resource)m4_dnl
 deliver_queue_load_max = 8
+message_size_limit = 500M
 queue_only_load = 12
 smtp_accept_max = 16
 smtp_accept_queue = 32
@@ -59,6 +60,8 @@ gecos_name = $1
 gecos_pattern = ([^,:]*)
 
 SECTION(global, incoming)m4_dnl
+rfc1413_hosts = *
+rfc1413_query_timeout = 10s
 received_header_text = Received: \
 	${if def:sender_rcvhost \
 	     {from $sender_rcvhost\n\t} \
@@ -73,13 +76,23 @@ received_header_text = Received: \
 	${if def:sender_address \
 	     {(envelope-from $sender_address\
 	      ${if def:authenticated_id \
-		   {; auth=$authenticated_id}})\n\t}}\
+		   {; auth=${quote_local_part:$authenticated_id}} \
+		   {${if and {{def:authenticated_sender} \
+			      {match_address{$authenticated_sender} \
+					    {*@CONF_master_domain}}} \
+			 {; auth=${quote_local_part:\
+				    ${local_part:\
+				      $authenticated_sender}}}}}})\n\t}}\
 	id $message_exim_id\
 	${if def:received_for {\n\tfor $received_for}}
 
 SECTION(global, smtp)m4_dnl
 smtp_return_error_details = true
 accept_8bitmime = true
+chunking_advertise_hosts =
+
+SECTION(global, env)m4_dnl
+keep_environment =
 
 SECTION(global, process)m4_dnl
 extract_addresses_remove_arguments = false
@@ -93,7 +106,7 @@ SECTION(global, bounce)m4_dnl
 delay_warning = 1h : 24h : 2d
 
 SECTION(global, tls)m4_dnl
-tls_certificate = CONF_sysconf_dir/server.certlist
+tls_certificate = CONF_certlist
 tls_privatekey = CONF_sysconf_dir/server.key
 tls_advertise_hosts = ${if exists {CONF_sysconf_dir/server.key} {*}{}}
 tls_dhparam = CONF_ca_dir/dh-param-2048.pem
@@ -113,6 +126,10 @@ SECTION(global, acl)m4_dnl
 acl_smtp_helo = helo
 SECTION(acl, misc)m4_dnl
 helo:
+	## Don't worry if this is local submission.  MUAs won't necessarily
+	## have a clear idea of their hostnames.  (For some reason.)
+	accept	 condition = ${if eq{$acl_c_mode}{submission}}
+
 	## Check that the caller's claimed identity is actually plausible.
 	## This seems like it's a fairly effective filter on spamminess, but
 	## it's too blunt a tool.  Rather than reject, add a warning header.
@@ -144,6 +161,7 @@ SECTION(acl, misc)m4_dnl
 not_smtp_start:
 	## Record the user's name.
 	warn	 set acl_c_user = $sender_ident
+		 set acl_m_user = $sender_ident
 
 	## Done.
 	accept
@@ -195,8 +213,7 @@ mail_check_sender:
 
 	## See whether there's a special exception for this sender domain.
 	accept	 senders = ${LOOKUP_DOMAIN($sender_address_domain,
-			     {KV(senders, {$value}{})},
-			     {})}
+			     {KV(senders)})}
 
 	## Ensure that the sender is routable.  This is important to prevent
 	## undeliverable bounces.
@@ -226,6 +243,7 @@ check_submission:
 
 	## Remember to apply submission controls.
 	warn	 set acl_c_mode = submission
+		 control = no_enforce_sync
 
 	## Done.
 	accept
@@ -251,17 +269,17 @@ check_relay:
 	## we're the correct place to send this mail.
 
 	## Known clients and authenticated users are OK.
-	accept	  hosts = CONF_relay_clients
-	accept	  authenticated = *
+	accept	 hosts = CONF_relay_clients
+	accept	 authenticated = *
 
 	## Known domains are OK.
-	accept	  domains = +public
+	accept	 domains = +public
 
 	## Finally, domains in our table are OK, unless they say they aren't.
-	accept	  domains = \
-		${if exists{CONF_sysconf_dir/domains.conf} \
+	accept	 domains = \
+		 ${if exists{CONF_sysconf_dir/domains.conf} \
 		     {partial0-lsearch;	CONF_sysconf_dir/domains.conf}}
-		  condition = DOMKV(service, {$value}{true})
+		 condition = DOMKV(service, {$value}{true})
 
 	## Nope, that's not allowed.
 	deny
@@ -274,6 +292,10 @@ SECTION(global, acl)m4_dnl
 acl_smtp_data = data
 SECTION(acl, data)m4_dnl
 data:
+	## Don't accept messages with overly-long lines.
+	deny	 message = line length exceeds SMTP permitted maximum: \
+			$max_received_linelength > 998
+		 condition = ${if >{$max_received_linelength}{998}}
 
 SECTION(acl, data-tail)m4_dnl
 	accept
@@ -309,6 +331,10 @@ mail_check_auth:
 	deny	 message = Sender not authenticated
 		 condition = ${if !def:acl_c_user}
 
+	## Set the per-message authentication flag, since we now know that
+	## there's a sensible value.
+	warn	 set acl_m_user = $acl_c_user
+
 	## All done.
 	accept
 
@@ -393,6 +419,71 @@ m4_define(<:APPLY_HEADER_CHANGES:>,
 		<:${if def:acl_m_hdrrm{$acl_m_hdrrm:}}\
 		$2:>):>)
 
+m4_define(<:DKIM_SIGN_P:>,
+	<:and {{exists{CONF_sysconf_dir/dkim-sign.conf}} \
+	       {!def:h_DKIM-Signature:} \
+	       {!def:h_List-ID:} \
+	       {or {{def:authenticated_id} \
+		    {def:authenticated_sender}}} \
+	       {bool {DKIM_KEYS_INSTANCE(<:{true}:>, <:{false}:>)}}}:>)
+
+m4_define(<:DKIM_KEYS_INSTANCE:>,
+	<:${lookup {${domain:$h_From:}} partial0-lsearch \
+			{CONF_sysconf_dir/dkim-sign.conf} \
+		_LOOKUP_ARGS(<:$1:>, <:$2:>)}:>)
+m4_define(<:DKIM_KEYS_STATE:>, <:${lookup {$1} lsearch \
+		{DKIM_KEYS_INSTANCE(<:{CONF_dkim_keys_dir/$value/active/dkim-keys.state}:>)} \
+	_LOOKUP_ARGS(<:$2:>, <:$3:>, <:fail:>)}:>)
+m4_define(<:DKIM_KEYS_INFO:>, <:DKIM_KEYS_STATE(<:params:>,
+	<:{${if and {{>={$tod_epoch}{KV(t0)}} \
+		    {<{$tod_epoch}{${eval:KV(t0) + KV(n)*KV(step)}}}} \
+		{DKIM_KEYS_STATE(<:info.${eval:($tod_epoch - KV(t0))/KV(step)}:>,
+			<:$1:>, <:$2:>)} \
+		m4_ifelse(<:$2:>, <::>, <:fail:>, <:$2:>)}}:>,
+	m4_ifelse(<:$2:>, <::>, <:fail:>, <:$2:>)):>)
+
+m4_define(<:DKIM_SIGN:>,
+	<:dkim_domain = \
+		${if DKIM_SIGN_P \
+			{DKIM_KEYS_INSTANCE({${domain:$h_From:}})}}
+	dkim_selector = DKIM_KEYS_INFO(<:{KV(k)}:>)
+	##dkim_timestamps = m4_eval(<:7*24*60*60:>)
+	dkim_private_key = \
+		DKIM_KEYS_INSTANCE(<:m4_dnl
+			{CONF_dkim_keys_dir/$value/active/$dkim_selector.priv}:>)
+	dkim_canon = relaxed
+	dkim_strict = true
+	## The following ridiculous stunt does two important jobs.  Firstly,
+	## and more obviously, it arranges to include one more copy of each
+	## header name than the message actually contains, thereby causing
+	## the signature to fail if another header with the same name is
+	## added.  And secondly, and far more subtly, it also trims the
+	## spaces from the header names so that they're in the format that
+	## the signing machinery secretly wants.
+	dkim_sign_headers = \
+		${sg {${map {CONF_dkim_headers : \
+			     X-CONF_header_token-DKIM-Key-Publication} \
+			    {$item${sg {${expand:\$h_$item:}\n} \
+				       {((?:[^\n]+|\n\\s+)*)\n} \
+				       {:$item}}}}} \
+		     {::}{:}}
+	headers_add = \
+		${if DKIM_SIGN_P \
+			{DKIM_KEYS_INFO(<:m4_dnl
+				{X-CONF_header_token-DKIM-Key-Publication: \
+					DKIM signature not suitable \
+					as evidence after delivery;\n\t\
+					DKIM private key KV(k) will be \
+					published\n\t\
+					at KV(u)\n\t\
+					on or before KV(tpub)}:>)}}:>)
+
+
+m4_define(<:SMTP_DELIVERY:>,
+	<:## Prevent sending messages with overly long lines.  The use of
+	## `message_size_limit' here is somewhat misleading.
+	message_size_limit = ${if >{$max_received_linelength}{998}{1}{0}}:>)
+
 SECTION(transports)m4_dnl
 ## A standard transport for remote delivery.  By default, try to do TLS, and
 ## don't worry too much if it's not very secure: the alternative is sending
@@ -402,14 +493,18 @@ SECTION(transports)m4_dnl
 ## it into the transport name.  This is very unpleasant, of course.
 smtp:
 	driver = smtp
+	SMTP_DELIVERY
 	APPLY_HEADER_CHANGES
+	DKIM_SIGN
 	tls_require_ciphers = CONF_acceptable_ciphers
-	tls_dh_min_bits = 1020
+	tls_dh_min_bits = 508
 	tls_tempfail_tryclear = true
 
 m4_define(<:SMTP_TRANS_DHBITS:>,
 	<:driver = smtp
+	SMTP_DELIVERY
 	APPLY_HEADER_CHANGES
+	DKIM_SIGN
 	hosts_try_auth = *
 	hosts_require_tls = DOMKV(tls-peer-ca, {*}{})
 	hosts_require_auth = \
@@ -427,15 +522,20 @@ m4_define(<:SMTP_TRANS_DHBITS:>,
 		      {CONF_acceptable_ciphers})
 	tls_dh_min_bits = $1
 	tls_tempfail_tryclear = true:>)m4_dnl
+smtp_dhbits_512:
+	SMTP_TRANS_DHBITS(508)
+smtp_dhbits_768:
+	SMTP_TRANS_DHBITS(764)
 smtp_dhbits_1024:
 	SMTP_TRANS_DHBITS(1020)
 smtp_dhbits_2048:
-	SMTP_TRANS_DHBITS(2046)
+	SMTP_TRANS_DHBITS(2044)
 
 ## Transport to a local SMTP server; use TLS and perform client
 ## authentication.
 smtp_local:
 	driver = smtp
+	SMTP_DELIVERY
 	APPLY_HEADER_CHANGES
 	hosts_require_tls = *
 	tls_certificate = CONF_sysconf_dir/client.certlist
@@ -444,9 +544,11 @@ smtp_local:
 	tls_require_ciphers = CONF_good_ciphers
 	tls_dh_min_bits = 2046
 	tls_tempfail_tryclear = false
-	authenticated_sender = ${if def:authenticated_id \
-				    {$authenticated_id@CONF_master_domain} \
-				    fail}
+	authenticated_sender_force = true
+	authenticated_sender = \
+		${if def:acl_m_user {$acl_m_user@CONF_master_domain} \
+		     {${if def:authenticated_sender {$authenticated_sender} \
+			   fail}}}
 
 ## A standard transport for local delivery.
 deliver:
@@ -493,6 +595,13 @@ DIVERT(null)
 ### Retry configuration.
 
 SECTION(retry, default)m4_dnl
+## Be persistent when sending to the site relay.  It ought to work, but
+## particularly satellites such as laptops often encounter annoying temporary
+## failures due to network unavailability, and the usual gradual policy can
+## leave mail building up for no good reason.
+CONF_smarthost				* \
+	F,4d,15m
+
 ## Default.
 *					* \
 	F,2h,15m; G,16h,2h,1.5; F,4d,6h