tor: Use fixed 9001 port for relaying

When ORPort is set to 'auto', Tor automatically allocates a port for it. During
it's first run, we able to extract the port number and open the firewall port.
However, unlike for pluggable transports, Tor does not seem to store this port
for future reuse in the state file. It hence opens a new port every time it is
started. This leads to a new port being assigned on next Tor startup and leads
to relay functionality not being reachable from outside.

According to the documentation, only possible values for ORPort are a fixed
number or 0 (disable) or auto (current behavior). Choose 9001 as this is the
commonly used port number for ORPort. The recommended port number of 443 is not
possible in FreedomBox due it is use for other purposes.

Closes: #1495.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

actions/tor

@@ -45,7 +45,12 @@ def parse_arguments():
     parser = argparse.ArgumentParser()
     subparsers = parser.add_subparsers(dest='subcommand', help='Sub command')
 
-    subparsers.add_parser('setup', help='Setup Tor configuration')
+    setup_parser = subparsers.add_parser('setup',
+                                         help='Setup Tor configuration')
+    setup_parser.add_argument(
+        '--old-version', type=int, required=True, help=
+        'Version number being upgraded from or None if setting up first time.')
+
     subparsers.add_parser('get-status', help='Get Tor status in JSON format')
 
     configure = subparsers.add_parser('configure', help='Configure Tor')
@@ -72,9 +77,17 @@ def parse_arguments():
     return parser.parse_args()
 
 
-def subcommand_setup(_):
+def subcommand_setup(arguments):
     """Setup Tor configuration after installing it."""
+    if arguments.old_version and arguments.old_version <= 2:
+        _upgrade_orport_value()
+        return
 
+    _first_time_setup()
+
+
+def _first_time_setup():
+    """Setup Tor configuration for the first time setting defaults."""
     # Disable default tor service. We will use tor@plinth instance
     # instead.
     _disable_apt_transport_tor()
@@ -129,6 +142,37 @@ def subcommand_setup(_):
         time.sleep(10)
 
 
+def _upgrade_orport_value():
+    """Change ORPort value from auto to 9001.
+
+    When ORPort is set to 'auto', Tor automatically allocates a port for it.
+    During it's first run, we able to extract the port number and open the
+    firewall port. However, unlike for pluggable transports, Tor does not seem
+    to store this port for future reuse in the state file. It hence opens a new
+    port every time it is started. This leads to a new port being assigned on
+    next Tor startup and leads to relay functionality not being reachable from
+    outside.
+
+    According to the documentation, only possible values for ORPort are a fixed
+    number or 0 (disable) or auto (above behavior). Choose 9001 as this is
+    the commonly used port number for ORPort. The recommended port number of
+    443 is not possible in FreedomBox due it is use for other purposes.
+
+    """
+    aug = augeas_load()
+
+    if _is_relay_enabled(aug):
+        aug.set(TOR_CONFIG + '/ORPort', '9001')
+
+    aug.save()
+
+    action_utils.service_try_restart('tor@plinth')
+
+    # Tor may not be running, don't try to read/update all ports
+    _update_port('orport', 9001)
+    action_utils.service_restart('firewalld')
+
+
 def subcommand_get_status(_):
     """Get Tor status in JSON format."""
     print(json.dumps(get_status()))
@@ -359,7 +403,7 @@ def _enable_relay(relay=None, bridge=None, aug=None):
     use_upstream_bridges = _are_upstream_bridges_enabled(aug)
 
     if relay == 'enable' and not use_upstream_bridges:
-        aug.set(TOR_CONFIG + '/ORPort', 'auto')
+        aug.set(TOR_CONFIG + '/ORPort', '9001')
     elif relay == 'disable':
         aug.remove(TOR_CONFIG + '/ORPort')
 
@@ -440,6 +484,21 @@ def _disable_apt_transport_tor():
     aug.save()
 
 
+def _update_port(name, number):
+    """Update firewall service information for single port."""
+    lines = """<?xml version="1.0" encoding="utf-8"?>
+<service>
+  <short>Tor - {0}</short>
+  <port protocol="tcp" port="{1}"/>
+</service>
+"""
+    try:
+        with open(SERVICE_FILE.format(name), 'w') as service_file:
+            service_file.writelines(lines.format(name, number))
+    except FileNotFoundError:
+        return
+
+
 def _update_ports():
     """Update firewall service information."""
     ready = False
@@ -458,18 +517,8 @@ def _update_ports():
 
         time.sleep(10)
 
-    lines = """<?xml version="1.0" encoding="utf-8"?>
-<service>
-  <short>Tor - {0}</short>
-  <port protocol="tcp" port="{1}"/>
-</service>
-"""
     for name, number in ports.items():
-        try:
-            with open(SERVICE_FILE.format(name), 'w') as service_file:
-                service_file.writelines(lines.format(name, number))
-        except FileNotFoundError:
-            return
+        _update_port(name, number)
 
     # XXX: We should ideally do firewalld reload instead.  However,
     # firewalld seems to fail to successfully reload sometimes.

plinth/modules/tor/__init__.py

@@ -31,7 +31,7 @@ from plinth.signals import domain_added, domain_removed
 from . import utils
 from .manifest import backup, clients
 
-version = 2
+version = 3
 
 depends = ['names']
 
@@ -106,9 +106,12 @@ def init():
 def setup(helper, old_version=None):
     """Install and configure the module."""
     helper.install(managed_packages)
-    helper.call('post', actions.superuser_run, 'tor', ['setup'])
-    helper.call('post', actions.superuser_run, 'tor',
-                ['configure', '--apt-transport-tor', 'enable'])
+    helper.call(
+        'post', actions.superuser_run, 'tor',
+        ['setup', '--old-version', str(old_version)])
+    if not old_version:
+        helper.call('post', actions.superuser_run, 'tor',
+                    ['configure', '--apt-transport-tor', 'enable'])
 
     global socks_service
     if socks_service is None:
@@ -116,7 +119,9 @@ def setup(helper, old_version=None):
             'tor-socks', _('Tor Anonymity Network'), ports=['tor-socks'],
             is_external=False, is_enabled=utils.is_enabled,
             is_running=utils.is_running)
-    helper.call('post', socks_service.notify_enabled, None, True)
+
+    if not old_version:
+        helper.call('post', socks_service.notify_enabled, None, True)
 
     global bridge_service
     if bridge_service is None:
@@ -124,7 +129,9 @@ def setup(helper, old_version=None):
             'tor-bridge', _('Tor Bridge Relay'),
             ports=['tor-orport', 'tor-obfs3', 'tor-obfs4'], is_external=True,
             is_enabled=utils.is_enabled, is_running=utils.is_running)
-    helper.call('post', bridge_service.notify_enabled, None, True)
+
+    if not old_version:
+        helper.call('post', bridge_service.notify_enabled, None, True)
 
     helper.call('post', update_hidden_service_domain)