diff --git a/changelog.d/8052.feature b/changelog.d/8052.feature
new file mode 100644
index 0000000000..6aa020c764
--- /dev/null
+++ b/changelog.d/8052.feature
@@ -0,0 +1 @@
+Allow login to be blocked based on the values of SAML attributes.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index fe85978a1f..9235b89fb1 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1577,6 +1577,17 @@ saml2_config:
#
#grandfathered_mxid_source_attribute: upn
+ # It is possible to configure Synapse to only allow logins if SAML attributes
+ # match particular values. The requirements can be listed under
+ # `attribute_requirements` as shown below. All of the listed attributes must
+ # match for the login to be permitted.
+ #
+ #attribute_requirements:
+ # - attribute: userGroup
+ # value: "staff"
+ # - attribute: department
+ # value: "sales"
+
# Directory in which Synapse will try to find the template files below.
# If not set, default templates from within the Synapse package will be used.
#
diff --git a/synapse/config/_util.py b/synapse/config/_util.py
new file mode 100644
index 0000000000..cd31b1c3c9
--- /dev/null
+++ b/synapse/config/_util.py
@@ -0,0 +1,49 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 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.
+from typing import Any, List
+
+import jsonschema
+
+from synapse.config._base import ConfigError
+from synapse.types import JsonDict
+
+
+def validate_config(json_schema: JsonDict, config: Any, config_path: List[str]) -> None:
+ """Validates a config setting against a JsonSchema definition
+
+ This can be used to validate a section of the config file against a schema
+ definition. If the validation fails, a ConfigError is raised with a textual
+ description of the problem.
+
+ Args:
+ json_schema: the schema to validate against
+ config: the configuration value to be validated
+ config_path: the path within the config file. This will be used as a basis
+ for the error message.
+ """
+ try:
+ jsonschema.validate(config, json_schema)
+ except jsonschema.ValidationError as e:
+ # copy `config_path` before modifying it.
+ path = list(config_path)
+ for p in list(e.path):
+ if isinstance(p, int):
+ path.append("<item %i>" % p)
+ else:
+ path.append(str(p))
+
+ raise ConfigError(
+ "Unable to parse configuration: %s at %s" % (e.message, ".".join(path))
+ )
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index 293643b2de..9277b5f342 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -15,7 +15,9 @@
# limitations under the License.
import logging
+from typing import Any, List
+import attr
import jinja2
import pkg_resources
@@ -23,6 +25,7 @@ from synapse.python_dependencies import DependencyException, check_requirements
from synapse.util.module_loader import load_module, load_python_module
from ._base import Config, ConfigError
+from ._util import validate_config
logger = logging.getLogger(__name__)
@@ -80,6 +83,11 @@ class SAML2Config(Config):
self.saml2_enabled = True
+ attribute_requirements = saml2_config.get("attribute_requirements") or []
+ self.attribute_requirements = _parse_attribute_requirements_def(
+ attribute_requirements
+ )
+
self.saml2_grandfathered_mxid_source_attribute = saml2_config.get(
"grandfathered_mxid_source_attribute", "uid"
)
@@ -341,6 +349,17 @@ class SAML2Config(Config):
#
#grandfathered_mxid_source_attribute: upn
+ # It is possible to configure Synapse to only allow logins if SAML attributes
+ # match particular values. The requirements can be listed under
+ # `attribute_requirements` as shown below. All of the listed attributes must
+ # match for the login to be permitted.
+ #
+ #attribute_requirements:
+ # - attribute: userGroup
+ # value: "staff"
+ # - attribute: department
+ # value: "sales"
+
# Directory in which Synapse will try to find the template files below.
# If not set, default templates from within the Synapse package will be used.
#
@@ -368,3 +387,34 @@ class SAML2Config(Config):
""" % {
"config_dir_path": config_dir_path
}
+
+
+@attr.s(frozen=True)
+class SamlAttributeRequirement:
+ """Object describing a single requirement for SAML attributes."""
+
+ attribute = attr.ib(type=str)
+ value = attr.ib(type=str)
+
+ JSON_SCHEMA = {
+ "type": "object",
+ "properties": {"attribute": {"type": "string"}, "value": {"type": "string"}},
+ "required": ["attribute", "value"],
+ }
+
+
+ATTRIBUTE_REQUIREMENTS_SCHEMA = {
+ "type": "array",
+ "items": SamlAttributeRequirement.JSON_SCHEMA,
+}
+
+
+def _parse_attribute_requirements_def(
+ attribute_requirements: Any,
+) -> List[SamlAttributeRequirement]:
+ validate_config(
+ ATTRIBUTE_REQUIREMENTS_SCHEMA,
+ attribute_requirements,
+ config_path=["saml2_config", "attribute_requirements"],
+ )
+ return [SamlAttributeRequirement(**x) for x in attribute_requirements]
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index 2d506dc1f2..c1fcb98454 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -14,15 +14,16 @@
# limitations under the License.
import logging
import re
-from typing import Callable, Dict, Optional, Set, Tuple
+from typing import TYPE_CHECKING, Callable, Dict, Optional, Set, Tuple
import attr
import saml2
import saml2.response
from saml2.client import Saml2Client
-from synapse.api.errors import SynapseError
+from synapse.api.errors import AuthError, SynapseError
from synapse.config import ConfigError
+from synapse.config.saml2_config import SamlAttributeRequirement
from synapse.http.servlet import parse_string
from synapse.http.site import SynapseRequest
from synapse.module_api import ModuleApi
@@ -34,6 +35,9 @@ from synapse.types import (
from synapse.util.async_helpers import Linearizer
from synapse.util.iterutils import chunk_seq
+if TYPE_CHECKING:
+ import synapse.server
+
logger = logging.getLogger(__name__)
@@ -49,7 +53,7 @@ class Saml2SessionData:
class SamlHandler:
- def __init__(self, hs):
+ def __init__(self, hs: "synapse.server.HomeServer"):
self._saml_client = Saml2Client(hs.config.saml2_sp_config)
self._auth = hs.get_auth()
self._auth_handler = hs.get_auth_handler()
@@ -62,6 +66,7 @@ class SamlHandler:
self._grandfathered_mxid_source_attribute = (
hs.config.saml2_grandfathered_mxid_source_attribute
)
+ self._saml2_attribute_requirements = hs.config.saml2.attribute_requirements
# plugin to do custom mapping from saml response to mxid
self._user_mapping_provider = hs.config.saml2_user_mapping_provider_class(
@@ -73,7 +78,7 @@ class SamlHandler:
self._auth_provider_id = "saml"
# a map from saml session id to Saml2SessionData object
- self._outstanding_requests_dict = {}
+ self._outstanding_requests_dict = {} # type: Dict[str, Saml2SessionData]
# a lock on the mappings
self._mapping_lock = Linearizer(name="saml_mapping", clock=self._clock)
@@ -165,11 +170,18 @@ class SamlHandler:
saml2.BINDING_HTTP_POST,
outstanding=self._outstanding_requests_dict,
)
+ except saml2.response.UnsolicitedResponse as e:
+ # the pysaml2 library helpfully logs an ERROR here, but neglects to log
+ # the session ID. I don't really want to put the full text of the exception
+ # in the (user-visible) exception message, so let's log the exception here
+ # so we can track down the session IDs later.
+ logger.warning(str(e))
+ raise SynapseError(400, "Unexpected SAML2 login.")
except Exception as e:
- raise SynapseError(400, "Unable to parse SAML2 response: %s" % (e,))
+ raise SynapseError(400, "Unable to parse SAML2 response: %s." % (e,))
if saml2_auth.not_signed:
- raise SynapseError(400, "SAML2 response was not signed")
+ raise SynapseError(400, "SAML2 response was not signed.")
logger.debug("SAML2 response: %s", saml2_auth.origxml)
for assertion in saml2_auth.assertions:
@@ -188,6 +200,9 @@ class SamlHandler:
saml2_auth.in_response_to, None
)
+ for requirement in self._saml2_attribute_requirements:
+ _check_attribute_requirement(saml2_auth.ava, requirement)
+
remote_user_id = self._user_mapping_provider.get_remote_user_id(
saml2_auth, client_redirect_url
)
@@ -294,6 +309,21 @@ class SamlHandler:
del self._outstanding_requests_dict[reqid]
+def _check_attribute_requirement(ava: dict, req: SamlAttributeRequirement):
+ values = ava.get(req.attribute, [])
+ for v in values:
+ if v == req.value:
+ return
+
+ logger.info(
+ "SAML2 attribute %s did not match required value '%s' (was '%s')",
+ req.attribute,
+ req.value,
+ values,
+ )
+ raise AuthError(403, "You are not authorized to log in here.")
+
+
DOT_REPLACE_PATTERN = re.compile(
("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
)
diff --git a/synapse/res/templates/saml_error.html b/synapse/res/templates/saml_error.html
index bfd6449c5d..01cd9bdaf3 100644
--- a/synapse/res/templates/saml_error.html
+++ b/synapse/res/templates/saml_error.html
@@ -2,10 +2,17 @@
<html lang="en">
<head>
<meta charset="UTF-8">
- <title>SSO error</title>
+ <title>SSO login error</title>
</head>
<body>
- <p>Oops! Something went wrong during authentication<span id="errormsg"></span>.</p>
+{# a 403 means we have actively rejected their login #}
+{% if code == 403 %}
+ <p>You are not allowed to log in here.</p>
+{% else %}
+ <p>
+ There was an error during authentication:
+ </p>
+ <div id="errormsg" style="margin:20px 80px">{{ msg }}</div>
<p>
If you are seeing this page after clicking a link sent to you via email, make
sure you only click the confirmation link once, and that you open the
@@ -37,9 +44,9 @@
// to print one.
let errorDesc = new URLSearchParams(searchStr).get("error_description")
if (errorDesc) {
-
- document.getElementById("errormsg").innerText = ` ("${errorDesc}")`;
+ document.getElementById("errormsg").innerText = errorDesc;
}
</script>
+{% endif %}
</body>
-</html>
\ No newline at end of file
+</html>
|
