email: Implement email_server ipc set_sasl and set_submission

- Rewrote action script to eliminate stdin communication
- Changed return type of audit.*.get()
  - An audit can return multiple lines of diagnostics
- Move recommended endpoint URLs into function docstrings

actions/email_server

@@ -3,15 +3,23 @@
 
 import logging
 import os
-import signal
 import sys
 
-import plinth.modules.email_server.postconf as postconf
+import plinth.modules.email_server.audit as audit
 
 logger = logging.getLogger(__name__)
 
 EXIT_SYNTAX = 10
-EXIT_TIMEOUT = 20
+EXIT_PERM = 20
+
+
+def reserved_for_root(fun):
+    def wrapped(*args, **kwargs):
+        if os.getuid() != 0:
+            logger.critical('This action is reserved for root')
+            sys.exit(EXIT_PERM)
+        return fun(*args, **kwargs)
+    return wrapped
 
 
 def main():
@@ -24,43 +32,14 @@ def main():
     globals()[function_name]()
 
 
-def ipc_postconf_set_many_v1():
-    """Set postconf values"""
-    if os.getuid() != 0:
-        logger.warning('Run as root?')
-    new_config = _postconf_parse_stdin()
-    with postconf.postconf_mutex.lock_all():
-        for key, value in new_config.items():
-            postconf.set_no_lock_assuming_root(key, value)
+@reserved_for_root
+def ipc_set_sasl():
+    audit.ldap.action_set_sasl()
 
 
-def _postconf_parse_stdin():
-    new_config = {}
-    # Set timeout handler
-    signal.signal(signal.SIGALRM, _timeout_handler)
-    while True:
-        key = _timed_input('Key: ')
-        if not key: break
-        postconf.validate_key(key)
-        value = _timed_input('Value: ')
-        postconf.validate_value(value)
-        new_config[key] = value
-    return new_config
-
-
-def _timed_input(prompt):
-    # Set timeout
-    signal.alarm(3)
-    result = input(prompt)
-    # Disable timeout
-    signal.alarm(0)
-    return result
-
-
-def _timeout_handler(signum, frame):
-    # https://stackoverflow.com/a/1336751
-    logger.critical('[Time out]')
-    sys.exit(EXIT_TIMEOUT)
+@reserved_for_root
+def ipc_set_submission():
+    audit.ldap.action_set_submission()
 
 
 if __name__ == '__main__':

plinth/modules/email_server/__init__.py

@@ -13,7 +13,7 @@ from plinth.modules.firewall.components import Firewall
 from . import audit
 from . import manifest
 
-version = 1
+version = 31
 managed_packages = ['postfix', 'dovecot-pop3d', 'dovecot-imapd',
                     'dovecot-lmtpd', 'dovecot-ldap', 'dovecot-managesieved']
 managed_services = ['postfix', 'dovecot']
@@ -86,8 +86,8 @@ class EmailServerApp(plinth.app.App):
     def diagnose(self):
         """Run diagnostics and return the results"""
         results = super().diagnose()
-        results.append(audit.domain.get().summarize())
-        results.append(audit.ldap.get().summarize())
+        results.extend([r.summarize() for r in audit.domain.get()])
+        results.extend([r.summarize() for r in audit.ldap.get()])
         return results
 
 

plinth/modules/email_server/audit/domain.py

@@ -6,7 +6,7 @@ from . import models
 
 def get():
     # Stub
-    return models.Result('Email domains')
+    return [models.Result('Email domains')]
 
 
 def repair():

plinth/modules/email_server/audit/ldap.py

@@ -1,4 +1,8 @@
+"""Audit of LDAP and mail submission settings"""
 # SPDX-License-Identifier: AGPL-3.0-or-later
+
+from plinth import actions
+
 import plinth.modules.email_server.postconf as postconf
 from . import models
 
@@ -8,18 +12,49 @@ default_config = {
     'smtpd_sasl_path': 'private/auth'
 }
 
+submission_flags = postconf.ServiceFlags(
+    service='submission', type='inet', private='n', unpriv='-', chroot='y',
+    wakeup='-', maxproc='-', command_args='smtpd'
+)
+
+default_submission_options = {
+    'syslog_name': 'postfix/submission',
+    'smtpd_tls_security_level': 'encrypt',
+    'smtpd_client_restrictions': 'permit_sasl_authenticated,reject',
+    'smtpd_relay_restrictions': 'permit_sasl_authenticated,reject'
+}
+
 
-# GET /audit/domain
 def get():
-    """Compare current values with the default. Generate an audit report"""
-    results = models.Result('LDAP for user accounts')
+    """Compare current values with the default. Generate an audit report
+
+    Recommended endpoint name:
+    GET /audit/ldap
+    """
+    results = models.Result('Postfix uses Dovecot for SASL authentication')
     current_config = postconf.get_many(list(default_config.keys()))
     for key, value in default_config.items():
         if current_config[key] != value:
             results.fails.append('{} should equal {}'.format(key, value))
-    return results
+    return [results]
 
 
-# POST /audit/domain/repair
 def repair():
+    """Tries to repair LDAP and mail submission settings
+
+    Recommended endpoint name:
+    POST /audit/ldap/repair
+    """
+    actions.superuser_run('email_server', ['ipc', 'set_sasl'])
+    actions.superuser_run('email_server', ['ipc', 'set_submission'])
+
+
+def action_set_sasl():
+    """Called by email_server ipc set_sasl"""
     postconf.set_many(default_config)
+
+
+def action_set_submission():
+    """Called by email_server ipc set_submission"""
+    postconf.set_master_cf_options(service_flags=submission_flags,
+                                   options=default_submission_options)

plinth/modules/email_server/postconf.py

@@ -1,6 +1,7 @@
 """Postconf wrapper providing thread-safe operations"""
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
+import dataclasses
 import re
 import subprocess
 import plinth.actions
@@ -9,38 +10,67 @@ from .lock import Mutex
 postconf_mutex = Mutex('plinth-email-postconf.lock')
 
 
+@dataclasses.dataclass
+class ServiceFlags:
+    service: str
+    type: str
+    private: str
+    unpriv: str
+    chroot: str
+    wakeup: str
+    maxproc: str
+    command_args: str
+
+    def serialize(self) -> str:
+        return ' '.join([self.service, self.type, self.private, self.unpriv,
+                         self.chroot, self.wakeup, self.maxproc,
+                         self.command_args])
+
+
 def get_many(key_list):
     """Acquire resource lock. Get the list of postconf values as specified.
     Return a key-value map"""
     result = {}
+    for key in key_list:
+        validate_key(key)
     with postconf_mutex.lock_all():
         for key in key_list:
-            result[key] = get_no_lock(key)
+            result[key] = get_unsafe(key)
         return result
 
 
 def set_many(kv_map):
     """Acquire resource lock. Set the list of postconf values as specified"""
-    # Encode email_server ipc input
-    lines = []
     for key, value in kv_map.items():
         validate_key(key)
         validate_value(value)
-        lines.append(key)
-        lines.append(value)
-    lines.append('\n')
-    stdin = '\n'.join(lines).encode('utf-8')
 
-    # Run action script as root
-    args = ['ipc', 'postconf_set_many_v1']
-    with postconf_mutex.lock_threads_only():
-        # The action script will take care of file locking
-        plinth.actions.superuser_run('email_server', args, input=stdin)
+    with postconf_mutex.lock_all():
+        for key, value in kv_map.items():
+            set_unsafe(key, value)
 
 
-def get_no_lock(key):
-    """Get postconf value (no locking)"""
-    validate_key(key)
+def set_master_cf_options(service_flags, options):
+    """Acquire resource lock. Set master.cf service options"""
+    if not isinstance(service_flags, ServiceFlags):
+        raise TypeError('service_flags')
+    for key, value in options.items():
+        validate_key(key)
+        validate_value(value)
+
+    service_slash_type = service_flags.service + '/' + service_flags.type
+    flag_string = service_flags.serialize()
+
+    with postconf_mutex.lock_all():
+        # /sbin/postconf -M "service/type=flag_string"
+        set_unsafe(service_slash_type, flag_string, '-M')
+        for short_key, value in options.items():
+            # /sbin/postconf -P "service/type/short_key=value"
+            set_unsafe(service_slash_type + '/' + short_key, value, '-P')
+
+
+def get_unsafe(key):
+    """Get postconf value (no locking, no sanitization)"""
     result = _run(['/sbin/postconf', key])
     match = key + ' = '
     if not result.startswith(match):
@@ -48,11 +78,12 @@ def get_no_lock(key):
     return result[len(match):].strip()
 
 
-def set_no_lock_assuming_root(key, value):
-    """Set postconf value (assuming root and no locking)"""
-    validate_key(key)
-    validate_value(value)
-    _run(['/sbin/postconf', '{}={}'.format(key, value)])
+def set_unsafe(key, value, flag=''):
+    """Set postconf value (assuming root, no locking, no sanitization)"""
+    if flag:
+        _run(['/sbin/postconf', flag, '{}={}'.format(key, value)])
+    else:
+        _run(['/sbin/postconf', '{}={}'.format(key, value)])
 
 
 def _run(args):