WIP: feat: redirect uri wildcards

Author: dopry

docs/settings.rst

@@ -63,6 +63,39 @@ assigned ports.
 Note that you may override ``Application.get_allowed_schemes()`` to set this on
 a per-application basis.
 
+ALLOW_REDIRECT_URI_WILDCARDS
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Default: ``False``
+
+SECURITY WARNING: Enabling this setting can introduce security vulnerabilities. Only enable
+this setting if you understand the risks. https://datatracker.ietf.org/doc/html/rfc6749#section-3.1.2
+states "The redirection endpoint URI MUST be an absolute URI as defined by [RFC3986] Section 4.3." The
+intent of the URI restrictions is to prevent open redirects and phishing attacks. If you do enable this
+ensure that the wildcards restrict URIs to resources under your control. You are strongly encouragd not
+to use this feature in production.
+
+When set to ``True``, the server will allow wildcard characters in the domains
+and paths for redirect_uris and post_logout_redirect_uris.
+
+``*`` is the only wildcard character allowed.
+
+``*`` can only be used as a prefix to a domain, must be the first character in
+the domain, and cannot be in the top or second level domain.  Matching is done using an
+endsWith check.
+
+For example,
+``https://*.example.com`` is allowed,
+``https://*-myproject.example.com`` is allowed,
+``https://*.sub.example.com`` is not allowed,
+``https://*.com`` is not allowed, and
+``https://example.*.com`` is not allowed.
+
+
+
+This feature is useful for working with CI service such as cloudflare, netlify, and vercel that offer branch
+deployments for development previews and user acceptance testing.
+
 ALLOWED_SCHEMES
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

oauth2_provider/models.py

@@ -213,7 +213,11 @@ def clean(self):
 
         if redirect_uris:
             validator = AllowedURIValidator(
-                allowed_schemes, name="redirect uri", allow_path=True, allow_query=True
+                allowed_schemes,
+                name="redirect uri",
+                allow_path=True,
+                allow_query=True,
+                allow_hostname_wildcard=oauth2_settings.ALLOW_REDIRECT_URI_WILDCARDS,
             )
             for uri in redirect_uris:
                 validator(uri)
@@ -227,7 +231,11 @@ def clean(self):
         allowed_origins = self.allowed_origins.strip().split()
         if allowed_origins:
             # oauthlib allows only https scheme for CORS
-            validator = AllowedURIValidator(oauth2_settings.ALLOWED_SCHEMES, "allowed origin")
+            validator = AllowedURIValidator(
+                oauth2_settings.ALLOWED_SCHEMES,
+                "allowed origin",
+                allow_hostname_wildcard=oauth2_settings.ALLOW_REDIRECT_URI_WILDCARDS,
+            )
             for uri in allowed_origins:
                 validator(uri)
 
@@ -782,35 +790,43 @@ def redirect_to_uri_allowed(uri, allowed_uris):
     for allowed_uri in allowed_uris:
         parsed_allowed_uri = urlparse(allowed_uri)
 
+        if parsed_allowed_uri.scheme != parsed_uri.scheme:
+            # match failed, continue
+            continue
+
+        """ check hostname """
+        if oauth2_settings.ALLOW_REDIRECT_URI_WILDCARDS and parsed_allowed_uri.hostname.startswith("*"):
+            """ wildcard hostname """
+            if not parsed_uri.hostname.endswith(parsed_allowed_uri.hostname[1:]):
+                continue
+        elif parsed_allowed_uri.hostname != parsed_uri.hostname:
+            continue
+
         # From RFC 8252 (Section 7.3)
+        # https://datatracker.ietf.org/doc/html/rfc8252#section-7.3
         #
         # Loopback redirect URIs use the "http" scheme
         # [...]
         # The authorization server MUST allow any port to be specified at the
         # time of the request for loopback IP redirect URIs, to accommodate
         # clients that obtain an available ephemeral port from the operating
         # system at the time of the request.
+        allowed_uri_is_loopback = parsed_allowed_uri.scheme == "http" and parsed_allowed_uri.hostname in [
+            "127.0.0.1",
+            "::1",
+        ]
+        """ check port """
+        if not allowed_uri_is_loopback and parsed_allowed_uri.port != parsed_uri.port:
+            continue
 
-        allowed_uri_is_loopback = (
-            parsed_allowed_uri.scheme == "http"
-            and parsed_allowed_uri.hostname in ["127.0.0.1", "::1"]
-            and parsed_allowed_uri.port is None
-        )
-        if (
-            allowed_uri_is_loopback
-            and parsed_allowed_uri.scheme == parsed_uri.scheme
-            and parsed_allowed_uri.hostname == parsed_uri.hostname
-            and parsed_allowed_uri.path == parsed_uri.path
-        ) or (
-            parsed_allowed_uri.scheme == parsed_uri.scheme
-            and parsed_allowed_uri.netloc == parsed_uri.netloc
-            and parsed_allowed_uri.path == parsed_uri.path
-        ):
-            aqs_set = set(parse_qsl(parsed_allowed_uri.query))
-            if aqs_set.issubset(uqs_set):
-                return True
+        """ check path """
+        if parsed_allowed_uri.path != parsed_uri.path:
+            continue
 
-    return False
+        """ check querystring """
+        aqs_set = set(parse_qsl(parsed_allowed_uri.query))
+        if not aqs_set.issubset(uqs_set):
+            continue  # circuit break
 
 
 def is_origin_allowed(origin, allowed_origins):
@@ -833,4 +849,5 @@ def is_origin_allowed(origin, allowed_origins):
             and parsed_allowed_origin.netloc == parsed_origin.netloc
         ):
             return True
+
     return False

oauth2_provider/settings.py

@@ -71,6 +71,7 @@
     "REQUEST_APPROVAL_PROMPT": "force",
     "ALLOWED_REDIRECT_URI_SCHEMES": ["http", "https"],
     "ALLOWED_SCHEMES": ["https"],
+    "ALLOW_REDIRECT_URI_WILDCARDS": False,
     "OIDC_ENABLED": False,
     "OIDC_ISS_ENDPOINT": "",
     "OIDC_USERINFO_ENDPOINT": "",

oauth2_provider/validators.py

@@ -5,6 +5,8 @@
 from django.core.validators import URLValidator
 from django.utils.encoding import force_str
 
+from .settings import oauth2_settings
+
 
 class URIValidator(URLValidator):
     scheme_re = r"^(?:[a-z][a-z0-9\.\-\+]*)://"
@@ -21,7 +23,15 @@ class URIValidator(URLValidator):
 class AllowedURIValidator(URIValidator):
     # TODO: find a way to get these associated with their form fields in place of passing name
     # TODO: submit PR to get `cause` included in the parent class ValidationError params`
-    def __init__(self, schemes, name, allow_path=False, allow_query=False, allow_fragments=False):
+    def __init__(
+        self,
+        schemes,
+        name,
+        allow_path=False,
+        allow_query=False,
+        allow_fragments=False,
+        allow_hostname_wildcard=False,
+    ):
         """
         :param schemes: List of allowed schemes. E.g.: ["https"]
         :param name: Name of the validated URI. It is required for validation message. E.g.: "Origin"
@@ -34,6 +44,7 @@ def __init__(self, schemes, name, allow_path=False, allow_query=False, allow_fra
         self.allow_path = allow_path
         self.allow_query = allow_query
         self.allow_fragments = allow_fragments
+        self.allow_hostname_wildcard = allow_hostname_wildcard
 
     def __call__(self, value):
         value = force_str(value)
@@ -68,8 +79,52 @@ def __call__(self, value):
                 params={"name": self.name, "value": value, "cause": "path not allowed"},
             )
 
+        if oauth2_settings.ALLOW_REDIRECT_URI_WILDCARDS and self.allow_hostname_wildcard and "*" in netloc:
+            domain_parts = netloc.split(".")
+            if netloc.count("*") > 1:
+                raise ValidationError(
+                    "%(name)s URI validation error. %(cause)s: %(value)s",
+                    params={
+                        "name": self.name,
+                        "value": value,
+                        "cause": "only one wildcard is allowed in the hostname",
+                    },
+                )
+            if not netloc.startswith("*"):
+                raise ValidationError(
+                    "%(name)s URI validation error. %(cause)s: %(value)s",
+                    params={
+                        "name": self.name,
+                        "value": value,
+                        "cause": "wildcards must be at the beginning of the hostname",
+                    },
+                )
+            if len(domain_parts) < 3:
+                raise ValidationError(
+                    "%(name)s URI validation error. %(cause)s: %(value)s",
+                    params={
+                        "name": self.name,
+                        "value": value,
+                        "cause": "wildcards cannot be in the top level or second level domain",
+                    },
+                )
+
+            # strip the wildcard from the netloc, we'll reassamble the value later to pass to URI Validator
+            if netloc.startswith("*."):
+                netloc = netloc[2:]
+            else:
+                netloc = netloc[1:]
+
+        # we stripped the wildcard from the netloc and path if they were allowed and present since they would
+        # fail validation we'll reassamble the URI to pass to the URIValidator
+        reassambled_uri = f"{scheme}://{netloc}{path}"
+        if query:
+            reassambled_uri += f"?{query}"
+        if fragment:
+            reassambled_uri += f"#{fragment}"
+
         try:
-            super().__call__(value)
+            super().__call__(reassambled_uri)
         except ValidationError as e:
             raise ValidationError(
                 "%(name)s URI validation error. %(cause)s: %(value)s",

tests/test_oidc_views.py

@@ -299,6 +299,8 @@ def test_validate_logout_request(oidc_tokens, public_application, rp_settings):
             post_logout_redirect_uri="http://other.org",
         )
 
+    # TODO: test wildcards
+
 
 @pytest.mark.django_db(databases=retrieve_current_databases())
 @pytest.mark.parametrize("ALWAYS_PROMPT", [True, False])