Merge pull request #427 from pichak/add-sender-login-mismatch

Reject outgoing mail if MAIL FROM (envelope sender) does not match login name or is not an alias that directs mail (directly) to login name.

setup/mail-postfix.sh

@@ -160,6 +160,7 @@ tools/editconf.py /etc/postfix/main.cf virtual_transport=lmtp:[127.0.0.1]:10025
 #
 # * `reject_non_fqdn_sender`: Reject not-nice-looking return paths.
 # * `reject_unknown_sender_domain`: Reject return paths with invalid domains.
+# * `reject_authenticated_sender_login_mismatch`: Reject if mail FROM address does not match the client SASL login
 # * `reject_rhsbl_sender`: Reject return paths that use blacklisted domains.
 # * `permit_sasl_authenticated`: Authenticated users (i.e. on port 587) can skip further checks.
 # * `permit_mynetworks`: Mail that originates locally can skip further checks.
@@ -173,7 +174,7 @@ tools/editconf.py /etc/postfix/main.cf virtual_transport=lmtp:[127.0.0.1]:10025
 # whitelisted) then postfix does a DEFER_IF_REJECT, which results in all "unknown user" sorts of messages turning into #NODOC
 # "450 4.7.1 Client host rejected: Service unavailable". This is a retry code, so the mail doesn't properly bounce. #NODOC
 tools/editconf.py /etc/postfix/main.cf \
-	smtpd_sender_restrictions="reject_non_fqdn_sender,reject_unknown_sender_domain,reject_rhsbl_sender dbl.spamhaus.org" \
+	smtpd_sender_restrictions="reject_non_fqdn_sender,reject_unknown_sender_domain,reject_authenticated_sender_login_mismatch,reject_rhsbl_sender dbl.spamhaus.org" \
 	smtpd_recipient_restrictions=permit_sasl_authenticated,permit_mynetworks,"reject_rbl_client zen.spamhaus.org",reject_unlisted_recipient,"check_policy_service inet:127.0.0.1:10023"
 
 # Postfix connects to Postgrey on the 127.0.0.1 interface specifically. Ensure that

setup/mail-users.sh

@@ -69,6 +69,22 @@ tools/editconf.py /etc/postfix/main.cf \
 	smtpd_sasl_path=private/auth \
 	smtpd_sasl_auth_enable=yes
 
+# ### Sender Validation
+
+# Use a Sqlite3 database to set login maps. This is used with
+# reject_authenticated_sender_login_mismatch to see if user is
+# allowed to send mail using FROM field specified in the request.
+tools/editconf.py /etc/postfix/main.cf \
+	smtpd_sender_login_maps=sqlite:/etc/postfix/sender-login-maps.cf
+
+# SQL statement to set login map which includes the case when user is
+# sending email using a valid alias.
+# This is the same as virtual-alias-maps.cf, See below
+cat > /etc/postfix/sender-login-maps.cf << EOF;
+dbpath=$db_path
+query = SELECT destination from (SELECT destination, 0 as priority FROM aliases WHERE source='%s' UNION SELECT email as destination, 1 as priority FROM users WHERE email='%s') ORDER BY priority LIMIT 1;
+EOF
+
 # ### Destination Validation
 
 # Use a Sqlite3 database to check whether a destination email address exists,