Merge branch 'master' into tests/new_filters

CHANGELOG.md

@@ -11,6 +11,13 @@ All notable changes to this project will be documented in this file. The format
 - **Tests:**
   - Refactored helper methods for sending e-mails with specific `Message-ID` headers and the helpers for retrieving + filtering logs, which together help isolate logs relevant to specific mail when multiple mails have been processed within a single test.
 
+### Fixes
+
+- **Dovecot:**
+  - Restrict the auth mechanisms for PassDB configs we manage (oauth2, passwd-file, ldap) ([#3812](https://github.com/docker-mailserver/docker-mailserver/pull/3812))
+    - Prevents misleading auth failures from attempting to authenticate against a PassDB with incompatible auth mechanisms.
+    - When the new OAuth2 feature was enabled, it introduced false-positives with logged auth failures which triggered Fail2Ban to ban the IP.
+
 ## [v13.3.0](https://github.com/docker-mailserver/docker-mailserver/releases/tag/v13.3.0)
 
 ### Features

target/dovecot/auth-ldap.conf.ext

@@ -0,0 +1,21 @@
+# NOTE: This is effectively the same default LDAP config shipped by Dovecot
+# The only difference is the addition of the passdb mechanisms field,
+# which restricts what auth mechanisms are supported / expected.
+# This prevents unnecessary auth failure logs triggering Fail2Ban when
+# additional passdb are enabled (OAuth2).
+
+passdb {
+  driver = ldap
+  mechanism = plain login
+
+  # Path for LDAP configuration file, see example-config/dovecot-ldap.conf.ext
+  args = /etc/dovecot/dovecot-ldap.conf.ext
+}
+
+userdb {
+  driver = ldap
+  args = /etc/dovecot/dovecot-ldap.conf.ext
+
+  # Default fields can be used to specify defaults that LDAP may override
+  #default_fields = home=/home/virtual/%u
+}

target/dovecot/auth-oauth2.conf.ext

@@ -1,5 +1,12 @@
+# Allow clients to use these additional mechanisms:
 auth_mechanisms = $auth_mechanisms oauthbearer xoauth2
 
+# Dovecot docs consider the oauth2 driver as a "success/failure" type PassDB:
+# https://doc.dovecot.org/configuration_manual/authentication/password_databases_passdb/#success-failure-database
+# Which implies it cannot be configured for the non-plaintext SASL mechanisms listed here:
+# https://doc.dovecot.org/configuration_manual/authentication/authentication_mechanisms/#dovecot-supports-the-following-non-plaintext-mechanisms
+# However that is not the case, these mechanisms are still valid to prevent trying other incompatible mechanisms (like `plain`).
+
 passdb {
     driver = oauth2
     mechanisms = xoauth2 oauthbearer

target/dovecot/auth-passwdfile.inc

@@ -9,6 +9,7 @@
 
 passdb {
   driver = passwd-file
+  mechanisms = plain login
   args = scheme=SHA512-CRYPT username_format=%u /etc/dovecot/userdb
 }
 

test/config/oauth2/Caddyfile

@@ -38,6 +38,9 @@
   }
 }
 
+# NOTE: This portion of config is only relevant for understanding what happens seamlesssly,
+# DMS tests no longer use raw IMAP commands with netcat, thus none of this is relevant beyond reference for troubleshooting.
+#
 # /imap/xoauth2
 # Generate IMAP commands for authentication testing
 # Base64 encoded credentials can alternative be done via CLI with:

test/files/auth/imap-oauth2-oauthbearer.txt

@@ -1,4 +0,0 @@
-a0 NOOP See test/config/oauth2/Caddyfile to generate the below OAUTHBEARER string
-a1 AUTHENTICATE OAUTHBEARER bixhPXVzZXIxQGxvY2FsaG9zdC5sb2NhbGRvbWFpbiwBaG9zdD1sb2NhbGhvc3QBcG9ydD0xNDMBYXV0aD1CZWFyZXIgRE1TX1lXTmpaWE56WDNSdmEyVnUBAQ==
-a2 EXAMINE INBOX
-a3 LOGOUT

test/files/auth/imap-oauth2-xoauth2.txt

@@ -1,4 +0,0 @@
-a0 NOOP See test/config/oauth2/Caddyfile to generate the below XOAUTH2 string
-a1 AUTHENTICATE XOAUTH2 dXNlcj11c2VyMUBsb2NhbGhvc3QubG9jYWxkb21haW4BYXV0aD1CZWFyZXIgRE1TX1lXTmpaWE56WDNSdmEyVnUBAQ==
-a2 EXAMINE INBOX
-a3 LOGOUT

test/tests/serial/mail_with_oauth2.bats

@@ -58,21 +58,59 @@ function teardown_file() {
   docker network rm "${DMS_TEST_NETWORK}"
 }
 
-@test "should authenticate with XOAUTH2 over IMAP" {
-  _nc_wrapper 'auth/imap-oauth2-xoauth2.txt' '-w 1 0.0.0.0 143'
-  __verify_successful_login 'XOAUTH2'
+@test "should authenticate with XOAUTH2" {
+  __should_login_successfully_with 'XOAUTH2'
 }
 
-@test "should authenticate with OAUTHBEARER over IMAP" {
-  _nc_wrapper 'auth/imap-oauth2-oauthbearer.txt' '-w 1 0.0.0.0 143'
-  __verify_successful_login 'OAUTHBEARER'
+@test "should authenticate with OAUTHBEARER" {
+  __should_login_successfully_with 'OAUTHBEARER'
 }
 
-function __verify_successful_login() {
+function __should_login_successfully_with() {
   local AUTH_METHOD=${1}
+  # These values are the auth credentials checked against the Caddy `/userinfo` endpoint:
+  local USER_ACCOUNT='user1@localhost.localdomain'
+  local ACCESS_TOKEN='DMS_YWNjZXNzX3Rva2Vu'
 
+  __verify_auth_with_imap
+  __verify_auth_with_smtp
+}
+
+# Dovecot direct auth verification via IMAP:
+function __verify_auth_with_imap() {
+  # NOTE: Include the `--verbose` option if you're troubleshooting and want to see the protocol exchange messages
+  # NOTE: `--user username:password` is valid for testing `PLAIN` auth mechanism, but you should prefer swaks instead.
+  _run_in_container curl --silent \
+    --login-options "AUTH=${AUTH_METHOD}" --oauth2-bearer "${ACCESS_TOKEN}" --user "${USER_ACCOUNT}" \
+    --url 'imap://localhost:143' -X 'LOGOUT'
+
+  __dovecot_logs_should_verify_success
+}
+
+# Postfix delegates by default to Dovecot via SASL:
+# NOTE: This won't be compatible with LDAP if `ENABLE_SASLAUTHD=1` with `ldap` SASL mechanism:
+function __verify_auth_with_smtp() {
+  # NOTE: `--upload-file` with some mail content seems required for using curl to test OAuth2 authentication.
+  # TODO: Replace with swaks and early exit option when it supports XOAUTH2 + OAUTHBEARER:
+  _run_in_container curl --silent \
+    --login-options "AUTH=${AUTH_METHOD}" --oauth2-bearer "${ACCESS_TOKEN}" --user "${USER_ACCOUNT}" \
+    --url 'smtp://localhost:587' --mail-from "${USER_ACCOUNT}" --mail-rcpt "${USER_ACCOUNT}" --upload-file - <<< 'RFC 5322 content - not important'
+
+  # Postfix specific auth logs:
+  _run_in_container grep 'postfix/submission/smtpd' /var/log/mail.log
+  assert_output --partial "sasl_method=${AUTH_METHOD}, sasl_username=${USER_ACCOUNT}"
+
+  # Dovecot logs should still be checked as it is handling the actual auth process under the hood:
+  __dovecot_logs_should_verify_success
+}
+
+function __dovecot_logs_should_verify_success() {
   # Inspect the relevant Dovecot logs to catch failure / success:
   _service_log_should_contain_string 'mail' 'dovecot:'
   refute_output --partial 'oauth2 failed: Introspection failed'
-  assert_output --partial "dovecot: imap-login: Login: user=<user1@localhost.localdomain>, method=${AUTH_METHOD}"
+  assert_output --partial "dovecot: imap-login: Login: user=<${USER_ACCOUNT}>, method=${AUTH_METHOD}"
+
+  # If another PassDB is enabled, it should not have been attempted with the XOAUTH2 / OAUTHBEARER mechanisms:
+  # dovecot: auth: passwd-file(${USER_ACCOUNT},127.0.0.1): Password mismatch (SHA1 of given password: d390c1) - trying the next passdb
+  refute_output --partial 'trying the next passdb'
 }