Merge pull request #745 from cbcoutinho/feat/strict-auth-allowlists

feat(auth): drop test-client defaults, add ALLOWED_MGMT_CLIENT allowlist

nextcloud_mcp_server/auth/client_registry.py

@@ -66,7 +66,15 @@ class ClientRegistry:
         - http://localhost:* and http://127.0.0.1:* are allowed (native clients)
         - https:// redirect URIs are allowed (cloud clients)
         - http:// non-localhost redirect URIs are rejected with a warning
+
+        If the env var is unset or empty, the registry remains empty and
+        ``validate_client`` rejects every client_id (fail-closed). There are no
+        built-in defaults; operators must opt-in clients explicitly.
         """
+        # NOTE: ALLOWED_MCP_CLIENTS and ALLOWED_MGMT_CLIENT are currently separate
+        # env vars to keep the MCP-route and management-API auth surfaces
+        # independent. These may be consolidated into a single env var later
+        # once the deployment story stabilises.
         allowed_clients = os.getenv("ALLOWED_MCP_CLIENTS", "").strip()
 
         if allowed_clients:
@@ -123,9 +131,11 @@ class ClientRegistry:
                     )
                     logger.info(f"Registered static client: {entry}")
 
-        # Add well-known clients if not explicitly configured
         if not self._clients:
-            self._add_well_known_clients()
+            logger.warning(
+                "Client registry is empty: ALLOWED_MCP_CLIENTS is unset or empty. "
+                "All MCP-flow OAuth requests will be rejected until configured."
+            )
 
     def _get_client_name(self, client_id: str) -> str:
         """Get human-readable name for client_id."""
@@ -135,35 +145,9 @@ class ClientRegistry:
             "continue-dev": "Continue IDE Extension",
             "zed-editor": "Zed Editor",
             "vscode-mcp": "VS Code MCP Extension",
-            "test-mcp-client": "Test MCP Client",
         }
         return known_names.get(client_id, client_id.replace("-", " ").title())
 
-    def _add_well_known_clients(self):
-        """Add well-known MCP clients for testing and development."""
-        well_known = [
-            MCPClientInfo(
-                client_id="claude-desktop",
-                name="Claude Desktop",
-                redirect_uris=["http://localhost:*", "http://127.0.0.1:*"],
-                allowed_scopes=["*"],
-                is_public=True,
-                metadata={"vendor": "Anthropic"},
-            ),
-            MCPClientInfo(
-                client_id="test-mcp-client",
-                name="Test MCP Client",
-                redirect_uris=["http://localhost:*", "http://127.0.0.1:*"],
-                allowed_scopes=["*"],
-                is_public=True,
-                metadata={"purpose": "testing"},
-            ),
-        ]
-
-        for client in well_known:
-            self._clients[client.client_id] = client
-            logger.info(f"Registered well-known client: {client.client_id}")
-
     def validate_client(
         self,
         client_id: str,

nextcloud_mcp_server/auth/unified_verifier.py

@@ -17,6 +17,7 @@ Key Design Principles:
 
 import hashlib
 import logging
+import os
 import time
 from typing import Any
 
@@ -97,6 +98,25 @@ class UnifiedTokenVerifier(TokenVerifier):
         self._token_cache: dict[str, tuple[dict[str, Any], float]] = {}
         self.cache_ttl = 3600  # 1 hour default
 
+        # NOTE: ALLOWED_MCP_CLIENTS and ALLOWED_MGMT_CLIENT are currently separate
+        # env vars to keep the MCP-route and management-API auth surfaces
+        # independent. These may be consolidated into a single env var later
+        # once the deployment story stabilises.
+        self._allowed_mgmt_clients: frozenset[str] = frozenset(
+            entry.strip()
+            for entry in os.getenv("ALLOWED_MGMT_CLIENT", "").split(",")
+            if entry.strip()
+        )
+        if not self._allowed_mgmt_clients:
+            logger.warning(
+                "ALLOWED_MGMT_CLIENT is unset or empty: management API will reject "
+                "all requests until configured."
+            )
+        else:
+            logger.info(
+                f"Management API allowlist: {sorted(self._allowed_mgmt_clients)}"
+            )
+
         logger.info(
             f"UnifiedTokenVerifier initialized in {self.mode} mode. "
             f"MCP audience: {settings.oidc_client_id} or {settings.nextcloud_mcp_server_url}, "
@@ -169,10 +189,11 @@ class UnifiedTokenVerifier(TokenVerifier):
             token: Bearer token to verify
 
         Returns:
-            AccessToken if valid (regardless of audience), None otherwise
+            AccessToken if valid AND issued by an allowlisted client, None otherwise
         """
         # Check cache first (using separate cache key to avoid mixing with MCP tokens)
         cache_key = f"mgmt:{hashlib.sha256(token.encode()).hexdigest()}"
+        access_token: AccessToken | None = None
         if cache_key in self._token_cache:
             userinfo, expiry = self._token_cache[cache_key]
             if time.time() < expiry:
@@ -181,7 +202,7 @@ class UnifiedTokenVerifier(TokenVerifier):
                 username = userinfo.get("sub") or userinfo.get("preferred_username")
                 scope_string = userinfo.get("scope", "")
                 scopes = scope_string.split() if scope_string else []
-                return AccessToken(
+                access_token = AccessToken(
                     token=token,
                     client_id=userinfo.get("client_id", ""),
                     scopes=scopes,
@@ -191,10 +212,23 @@ class UnifiedTokenVerifier(TokenVerifier):
             else:
                 del self._token_cache[cache_key]
 
-        oauth_token_cache_hits_total.labels(hit="false").inc()
+        if access_token is None:
+            oauth_token_cache_hits_total.labels(hit="false").inc()
+            access_token = await self._verify_without_audience_check(token, cache_key)
 
-        # Verify token without audience check
-        return await self._verify_without_audience_check(token, cache_key)
+        if access_token is None:
+            return None
+
+        # Enforce ALLOWED_MGMT_CLIENT allowlist (fail-closed when unset)
+        token_client_id = access_token.client_id
+        if not token_client_id or token_client_id not in self._allowed_mgmt_clients:
+            logger.warning(
+                "Management API token rejected: client_id %r not in ALLOWED_MGMT_CLIENT",
+                token_client_id,
+            )
+            return None
+
+        return access_token
 
     async def _verify_mcp_audience(self, token: str) -> AccessToken | None:
         """