Merge pull request #5214 from matrix-org/babolivier/password-policy

Allow server admins to define and enforce a password policy (MSC2000)

11 files changed, 444 insertions, 5 deletions

diff --git a/changelog.d/5214.feature b/changelog.d/5214.feature
new file mode 100644
index 0000000000..6c0f15c901
--- /dev/null
+++ b/changelog.d/5214.feature
@@ -0,0 +1 @@
+Allow server admins to define and enforce a password policy (MSC2000).
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 8fd699c970..759ea49c5e 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1056,6 +1056,36 @@ password_config:
    #
    #pepper: "EVEN_MORE_SECRET"
 
+   # Define and enforce a password policy. Each parameter is optional, boolean
+   # parameters default to 'false' and integer parameters default to 0.
+   # This is an early implementation of MSC2000.
+   #
+   #policy:
+      # Whether to enforce the password policy.
+      #
+      #enabled: true
+
+      # Minimum accepted length for a password.
+      #
+      #minimum_length: 15
+
+      # Whether a password must contain at least one digit.
+      #
+      #require_digit: true
+
+      # Whether a password must contain at least one symbol.
+      # A symbol is any character that's not a number or a letter.
+      #
+      #require_symbol: true
+
+      # Whether a password must contain at least one lowercase letter.
+      #
+      #require_lowercase: true
+
+      # Whether a password must contain at least one lowercase letter.
+      #
+      #require_uppercase: true
+
 
 
 # Enable sending emails for notification events or expiry notices
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index ff89259dec..e6c67acf96 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
-# Copyright 2018 New Vector Ltd
+# Copyright 2017-2018 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -61,6 +62,13 @@ class Codes(object):
     INCOMPATIBLE_ROOM_VERSION = "M_INCOMPATIBLE_ROOM_VERSION"
     WRONG_ROOM_KEYS_VERSION = "M_WRONG_ROOM_KEYS_VERSION"
     EXPIRED_ACCOUNT = "ORG_MATRIX_EXPIRED_ACCOUNT"
+    PASSWORD_TOO_SHORT = "M_PASSWORD_TOO_SHORT"
+    PASSWORD_NO_DIGIT = "M_PASSWORD_NO_DIGIT"
+    PASSWORD_NO_UPPERCASE = "M_PASSWORD_NO_UPPERCASE"
+    PASSWORD_NO_LOWERCASE = "M_PASSWORD_NO_LOWERCASE"
+    PASSWORD_NO_SYMBOL = "M_PASSWORD_NO_SYMBOL"
+    PASSWORD_IN_DICTIONARY = "M_PASSWORD_IN_DICTIONARY"
+    WEAK_PASSWORD = "M_WEAK_PASSWORD"
 
 
 class CodeMessageException(RuntimeError):
@@ -349,6 +357,22 @@ class IncompatibleRoomVersionError(SynapseError):
         )
 
 
+class PasswordRefusedError(SynapseError):
+    """A password has been refused, either during password reset/change or registration.
+    """
+
+    def __init__(
+        self,
+        msg="This password doesn't comply with the server's policy",
+        errcode=Codes.WEAK_PASSWORD,
+    ):
+        super(PasswordRefusedError, self).__init__(
+            code=400,
+            msg=msg,
+            errcode=errcode,
+        )
+
+
 class RequestSendFailed(RuntimeError):
     """Sending a HTTP request over federation failed due to not being able to
     talk to the remote server for some reason.
diff --git a/synapse/config/password.py b/synapse/config/password.py
index eea59e772b..48a38512cb 100644
--- a/synapse/config/password.py
+++ b/synapse/config/password.py
@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
-# Copyright 2015, 2016 OpenMarket Ltd
+# Copyright 2015-2016 OpenMarket Ltd
+# Copyright 2017-2018 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -28,6 +30,10 @@ class PasswordConfig(Config):
         self.password_enabled = password_config.get("enabled", True)
         self.password_pepper = password_config.get("pepper", "")
 
+        # Password policy
+        self.password_policy = password_config.get("policy", {})
+        self.password_policy_enabled = self.password_policy.pop("enabled", False)
+
     def default_config(self, config_dir_path, server_name, **kwargs):
         return """\
         password_config:
@@ -39,4 +45,34 @@ class PasswordConfig(Config):
            # DO NOT CHANGE THIS AFTER INITIAL SETUP!
            #
            #pepper: "EVEN_MORE_SECRET"
+
+           # Define and enforce a password policy. Each parameter is optional, boolean
+           # parameters default to 'false' and integer parameters default to 0.
+           # This is an early implementation of MSC2000.
+           #
+           #policy:
+              # Whether to enforce the password policy.
+              #
+              #enabled: true
+
+              # Minimum accepted length for a password.
+              #
+              #minimum_length: 15
+
+              # Whether a password must contain at least one digit.
+              #
+              #require_digit: true
+
+              # Whether a password must contain at least one symbol.
+              # A symbol is any character that's not a number or a letter.
+              #
+              #require_symbol: true
+
+              # Whether a password must contain at least one lowercase letter.
+              #
+              #require_lowercase: true
+
+              # Whether a password must contain at least one lowercase letter.
+              #
+              #require_uppercase: true
         """
diff --git a/synapse/handlers/password_policy.py b/synapse/handlers/password_policy.py
new file mode 100644
index 0000000000..9994b44455
--- /dev/null
+++ b/synapse/handlers/password_policy.py
@@ -0,0 +1,93 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+import re
+
+from synapse.api.errors import Codes, PasswordRefusedError
+
+logger = logging.getLogger(__name__)
+
+
+class PasswordPolicyHandler(object):
+    def __init__(self, hs):
+        self.policy = hs.config.password_policy
+        self.enabled = hs.config.password_policy_enabled
+
+        # Regexps for the spec'd policy parameters.
+        self.regexp_digit = re.compile("[0-9]")
+        self.regexp_symbol = re.compile("[^a-zA-Z0-9]")
+        self.regexp_uppercase = re.compile("[A-Z]")
+        self.regexp_lowercase = re.compile("[a-z]")
+
+    def validate_password(self, password):
+        """Checks whether a given password complies with the server's policy.
+
+        Args:
+            password (str): The password to check against the server's policy.
+
+        Raises:
+            PasswordRefusedError: The password doesn't comply with the server's policy.
+        """
+
+        if not self.enabled:
+            return
+
+        minimum_accepted_length = self.policy.get("minimum_length", 0)
+        if len(password) < minimum_accepted_length:
+            raise PasswordRefusedError(
+                msg=(
+                    "The password must be at least %d characters long"
+                    % minimum_accepted_length
+                ),
+                errcode=Codes.PASSWORD_TOO_SHORT,
+            )
+
+        if (
+            self.policy.get("require_digit", False) and
+            self.regexp_digit.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one digit",
+                errcode=Codes.PASSWORD_NO_DIGIT,
+            )
+
+        if (
+            self.policy.get("require_symbol", False) and
+            self.regexp_symbol.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one symbol",
+                errcode=Codes.PASSWORD_NO_SYMBOL,
+            )
+
+        if (
+            self.policy.get("require_uppercase", False) and
+            self.regexp_uppercase.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one uppercase letter",
+                errcode=Codes.PASSWORD_NO_UPPERCASE,
+            )
+
+        if (
+            self.policy.get("require_lowercase", False) and
+            self.regexp_lowercase.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one lowercase letter",
+                errcode=Codes.PASSWORD_NO_LOWERCASE,
+            )
diff --git a/synapse/handlers/set_password.py b/synapse/handlers/set_password.py
index 7ecdede4dc..b556d23173 100644
--- a/synapse/handlers/set_password.py
+++ b/synapse/handlers/set_password.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
-# Copyright 2017 New Vector Ltd
+# Copyright 2017-2018 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -29,9 +30,12 @@ class SetPasswordHandler(BaseHandler):
         super(SetPasswordHandler, self).__init__(hs)
         self._auth_handler = hs.get_auth_handler()
         self._device_handler = hs.get_device_handler()
+        self._password_policy_handler = hs.get_password_policy_handler()
 
     @defer.inlineCallbacks
     def set_password(self, user_id, newpassword, requester=None):
+        self._password_policy_handler.validate_password(newpassword)
+
         password_hash = yield self._auth_handler.hash(newpassword)
 
         except_device_id = requester.device_id if requester else None
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 3a24d31d1b..bd828b9e96 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -41,6 +41,7 @@ from synapse.rest.client.v2_alpha import (
     keys,
     notifications,
     openid,
+    password_policy,
     read_marker,
     receipts,
     register,
@@ -115,6 +116,7 @@ class ClientRestResource(JsonResource):
         room_upgrade_rest_servlet.register_servlets(hs, client_resource)
         capabilities.register_servlets(hs, client_resource)
         account_validity.register_servlets(hs, client_resource)
+        password_policy.register_servlets(hs, client_resource)
 
         # moving to /_synapse/admin
         synapse.rest.admin.register_servlets_for_client_rest_resource(
diff --git a/synapse/rest/client/v2_alpha/password_policy.py b/synapse/rest/client/v2_alpha/password_policy.py
new file mode 100644
index 0000000000..d6e00de12c
--- /dev/null
+++ b/synapse/rest/client/v2_alpha/password_policy.py
@@ -0,0 +1,58 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+from synapse.http.servlet import RestServlet
+
+from ._base import client_v2_patterns
+
+logger = logging.getLogger(__name__)
+
+
+class PasswordPolicyServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/password_policy$")
+
+    def __init__(self, hs):
+        """
+        Args:
+            hs (synapse.server.HomeServer): server
+        """
+        super(PasswordPolicyServlet, self).__init__()
+
+        self.policy = hs.config.password_policy
+        self.enabled = hs.config.password_policy_enabled
+
+    def on_GET(self, request):
+        if not self.enabled or not self.policy:
+            return (200, {})
+
+        policy = {}
+
+        for param in [
+            "minimum_length",
+            "require_digit",
+            "require_symbol",
+            "require_lowercase",
+            "require_uppercase",
+        ]:
+            if param in self.policy:
+                policy["m.%s" % param] = self.policy[param]
+
+        return (200, policy)
+
+
+def register_servlets(hs, http_server):
+    PasswordPolicyServlet(hs).register(http_server)
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index a47f8b0c35..12a9b876d5 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
-# Copyright 2015 - 2016 OpenMarket Ltd
-# Copyright 2017 Vector Creations Ltd
+# Copyright 2015-2016 OpenMarket Ltd
+# Copyright 2017-2018 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -202,6 +203,7 @@ class RegisterRestServlet(RestServlet):
         self.room_member_handler = hs.get_room_member_handler()
         self.macaroon_gen = hs.get_macaroon_generator()
         self.ratelimiter = hs.get_registration_ratelimiter()
+        self.password_policy_handler = hs.get_password_policy_handler()
         self.clock = hs.get_clock()
 
     @interactive_auth_handler
@@ -245,6 +247,7 @@ class RegisterRestServlet(RestServlet):
             if (not isinstance(body['password'], string_types) or
                     len(body['password']) > 512):
                 raise SynapseError(400, "Invalid password")
+            self.password_policy_handler.validate_password(body['password'])
             desired_password = body["password"]
 
         desired_username = None
diff --git a/synapse/server.py b/synapse/server.py
index 80d40b9272..84e8a3a43e 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2017-2018 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -62,6 +64,7 @@ from synapse.handlers.groups_local import GroupsLocalHandler
 from synapse.handlers.initial_sync import InitialSyncHandler
 from synapse.handlers.message import EventCreationHandler, MessageHandler
 from synapse.handlers.pagination import PaginationHandler
+from synapse.handlers.password_policy import PasswordPolicyHandler
 from synapse.handlers.presence import PresenceHandler
 from synapse.handlers.profile import BaseProfileHandler, MasterProfileHandler
 from synapse.handlers.read_marker import ReadMarkerHandler
@@ -187,6 +190,7 @@ class HomeServer(object):
         'registration_handler',
         'account_validity_handler',
         'event_client_serializer',
+        'password_policy_handler',
     ]
 
     REQUIRED_ON_MASTER_STARTUP = [
@@ -516,6 +520,9 @@ class HomeServer(object):
     def build_event_client_serializer(self):
         return EventClientSerializer(self)
 
+    def build_password_policy_handler(self):
+        return PasswordPolicyHandler(self)
+
     def remove_pusher(self, app_id, push_key, user_id):
         return self.get_pusherpool().remove_pusher(app_id, push_key, user_id)
 
diff --git a/tests/rest/client/v2_alpha/test_password_policy.py b/tests/rest/client/v2_alpha/test_password_policy.py
new file mode 100644
index 0000000000..17c22fe751
--- /dev/null
+++ b/tests/rest/client/v2_alpha/test_password_policy.py
@@ -0,0 +1,181 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+
+from synapse.api.constants import LoginType
+from synapse.api.errors import Codes
+from synapse.rest import admin
+from synapse.rest.client.v1 import login
+from synapse.rest.client.v2_alpha import account, password_policy, register
+
+from tests import unittest
+
+
+class PasswordPolicyTestCase(unittest.HomeserverTestCase):
+    """Tests the password policy feature and its compliance with MSC2000.
+
+    When validating a password, Synapse does the necessary checks in this order:
+
+        1. Password is long enough
+        2. Password contains digit(s)
+        3. Password contains symbol(s)
+        4. Password contains uppercase letter(s)
+        5. Password contains lowercase letter(s)
+
+    Therefore, each test in this test case that tests whether a password triggers the
+    right error code to be returned provides a password good enough to pass the previous
+    steps but not the one it's testing (nor any step that comes after).
+    """
+
+    servlets = [
+        admin.register_servlets_for_client_rest_resource,
+        login.register_servlets,
+        register.register_servlets,
+        password_policy.register_servlets,
+        account.register_servlets,
+    ]
+
+    def make_homeserver(self, reactor, clock):
+        self.register_url = "/_matrix/client/r0/register"
+        self.policy = {
+            "enabled": True,
+            "minimum_length": 10,
+            "require_digit": True,
+            "require_symbol": True,
+            "require_lowercase": True,
+            "require_uppercase": True,
+        }
+
+        config = self.default_config()
+        config["password_config"] = {
+            "policy": self.policy,
+        }
+
+        hs = self.setup_test_homeserver(config=config)
+        return hs
+
+    def test_get_policy(self):
+        """Tests if the /password_policy endpoint returns the configured policy."""
+
+        request, channel = self.make_request("GET", "/_matrix/client/r0/password_policy")
+        self.render(request)
+
+        self.assertEqual(channel.code, 200, channel.result)
+        self.assertEqual(channel.json_body, {
+            "m.minimum_length": 10,
+            "m.require_digit": True,
+            "m.require_symbol": True,
+            "m.require_lowercase": True,
+            "m.require_uppercase": True,
+        }, channel.result)
+
+    def test_password_too_short(self):
+        request_data = json.dumps({"username": "kermit", "password": "shorty"})
+        request, channel = self.make_request("POST", self.register_url, request_data)
+        self.render(request)
+
+        self.assertEqual(channel.code, 400, channel.result)
+        self.assertEqual(
+            channel.json_body["errcode"],
+            Codes.PASSWORD_TOO_SHORT,
+            channel.result,
+        )
+
+    def test_password_no_digit(self):
+        request_data = json.dumps({"username": "kermit", "password": "longerpassword"})
+        request, channel = self.make_request("POST", self.register_url, request_data)
+        self.render(request)
+
+        self.assertEqual(channel.code, 400, channel.result)
+        self.assertEqual(
+            channel.json_body["errcode"],
+            Codes.PASSWORD_NO_DIGIT,
+            channel.result,
+        )
+
+    def test_password_no_symbol(self):
+        request_data = json.dumps({"username": "kermit", "password": "l0ngerpassword"})
+        request, channel = self.make_request("POST", self.register_url, request_data)
+        self.render(request)
+
+        self.assertEqual(channel.code, 400, channel.result)
+        self.assertEqual(
+            channel.json_body["errcode"],
+            Codes.PASSWORD_NO_SYMBOL,
+            channel.result,
+        )
+
+    def test_password_no_uppercase(self):
+        request_data = json.dumps({"username": "kermit", "password": "l0ngerpassword!"})
+        request, channel = self.make_request("POST", self.register_url, request_data)
+        self.render(request)
+
+        self.assertEqual(channel.code, 400, channel.result)
+        self.assertEqual(
+            channel.json_body["errcode"],
+            Codes.PASSWORD_NO_UPPERCASE,
+            channel.result,
+        )
+
+    def test_password_no_lowercase(self):
+        request_data = json.dumps({"username": "kermit", "password": "L0NGERPASSWORD!"})
+        request, channel = self.make_request("POST", self.register_url, request_data)
+        self.render(request)
+
+        self.assertEqual(channel.code, 400, channel.result)
+        self.assertEqual(
+            channel.json_body["errcode"],
+            Codes.PASSWORD_NO_LOWERCASE,
+            channel.result,
+        )
+
+    def test_password_compliant(self):
+        request_data = json.dumps({"username": "kermit", "password": "L0ngerpassword!"})
+        request, channel = self.make_request("POST", self.register_url, request_data)
+        self.render(request)
+
+        # Getting a 401 here means the password has passed validation and the server has
+        # responded with a list of registration flows.
+        self.assertEqual(channel.code, 401, channel.result)
+
+    def test_password_change(self):
+        """This doesn't test every possible use case, only that hitting /account/password
+        triggers the password validation code.
+        """
+        compliant_password = "C0mpl!antpassword"
+        not_compliant_password = "notcompliantpassword"
+
+        user_id = self.register_user("kermit", compliant_password)
+        tok = self.login("kermit", compliant_password)
+
+        request_data = json.dumps({
+            "new_password": not_compliant_password,
+            "auth": {
+                "password": compliant_password,
+                "type": LoginType.PASSWORD,
+                "user": user_id,
+            }
+        })
+        request, channel = self.make_request(
+            "POST",
+            "/_matrix/client/r0/account/password",
+            request_data,
+            access_token=tok,
+        )
+        self.render(request)
+
+        self.assertEqual(channel.code, 400, channel.result)
+        self.assertEqual(channel.json_body["errcode"], Codes.PASSWORD_NO_DIGIT)