From b14cc82682b7c80f96acd30ffea2d42c48b7dd6b Mon Sep 17 00:00:00 2001
From: Michael Telatynski <7t3chguy@gmail.com>
Date: Thu, 13 Mar 2025 14:47:09 +0000
Subject: [PATCH] OIDC: only pass logo_uri, policy_uri, tos_uri if they conform
 to "common base" (#4748)

* OIDC: only pass logo_uri, policy_uri, tos_uri if they conform to "common base"

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Tests

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>
---
 spec/unit/oidc/register.spec.ts | 26 ++++++++++++++++++++++++--
 src/oidc/register.ts            | 21 +++++++++++++++++----
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/spec/unit/oidc/register.spec.ts b/spec/unit/oidc/register.spec.ts
index 53124e0fd..ef72aa947 100644
--- a/spec/unit/oidc/register.spec.ts
+++ b/spec/unit/oidc/register.spec.ts
@@ -29,8 +29,8 @@ describe("registerOidcClient()", () => {
         redirectUris: [baseUrl],
         clientName,
         applicationType: "web",
-        tosUri: "http://tos-uri",
-        policyUri: "http://policy-uri",
+        tosUri: "https://just.testing/tos",
+        policyUri: "https://policy.just.testing",
         contacts: ["admin@example.com"],
     };
     const dynamicClientId = "xyz789";
@@ -67,6 +67,8 @@ describe("registerOidcClient()", () => {
                 id_token_signed_response_alg: "RS256",
                 token_endpoint_auth_method: "none",
                 application_type: "web",
+                tos_uri: "https://just.testing/tos",
+                policy_uri: "https://policy.just.testing",
             }),
         );
     });
@@ -114,4 +116,24 @@ describe("registerOidcClient()", () => {
             ),
         ).rejects.toThrow(OidcError.DynamicRegistrationNotSupported);
     });
+
+    it("should filter out invalid URIs", async () => {
+        fetchMockJest.post(delegatedAuthConfig.registration_endpoint!, {
+            status: 200,
+            body: JSON.stringify({ client_id: dynamicClientId }),
+        });
+        expect(
+            await registerOidcClient(delegatedAuthConfig, {
+                ...metadata,
+                tosUri: "http://just.testing/tos",
+                policyUri: "https://policy-uri/",
+            }),
+        ).toEqual(dynamicClientId);
+        expect(JSON.parse(fetchMockJest.mock.calls[0][1]!.body as string)).not.toEqual(
+            expect.objectContaining({
+                tos_uri: "http://just.testing/tos",
+                policy_uri: "https://policy-uri/",
+            }),
+        );
+    });
 });
diff --git a/src/oidc/register.ts b/src/oidc/register.ts
index eeed5ef07..22b70c0a0 100644
--- a/src/oidc/register.ts
+++ b/src/oidc/register.ts
@@ -54,8 +54,18 @@ interface OidcRegistrationRequestBody {
 
 export const DEVICE_CODE_SCOPE = "urn:ietf:params:oauth:grant-type:device_code";
 
+// Check that URIs have a common base, as per the MSC2966 definition
+const urlHasCommonBase = (base: URL, urlStr?: string): boolean => {
+    if (!urlStr) return false;
+    const url = new URL(urlStr);
+    if (url.protocol !== base.protocol) return false;
+    if (url.host !== base.host && !url.host.endsWith(`.${base.host}`)) return false;
+    return true;
+};
+
 /**
- * Attempts dynamic registration against the configured registration endpoint
+ * Attempts dynamic registration against the configured registration endpoint.
+ * Will ignore any URIs that do not use client_uri as a common base as per the spec.
  * @param delegatedAuthConfig - Auth config from {@link discoverAndValidateOIDCIssuerWellKnown}
  * @param clientMetadata - The metadata for the client which to register
  * @returns Promise<string> resolved with registered clientId
@@ -74,6 +84,8 @@ export const registerOidcClient = async (
         throw new Error(OidcError.DynamicRegistrationNotSupported);
     }
 
+    const commonBase = new URL(clientMetadata.clientUri);
+
     // https://openid.net/specs/openid-connect-registration-1_0.html
     const metadata: OidcRegistrationRequestBody = {
         client_name: clientMetadata.clientName,
@@ -84,11 +96,12 @@ export const registerOidcClient = async (
         id_token_signed_response_alg: "RS256",
         token_endpoint_auth_method: "none",
         application_type: clientMetadata.applicationType,
-        logo_uri: clientMetadata.logoUri,
         contacts: clientMetadata.contacts,
-        policy_uri: clientMetadata.policyUri,
-        tos_uri: clientMetadata.tosUri,
+        logo_uri: urlHasCommonBase(commonBase, clientMetadata.logoUri) ? clientMetadata.logoUri : undefined,
+        policy_uri: urlHasCommonBase(commonBase, clientMetadata.policyUri) ? clientMetadata.policyUri : undefined,
+        tos_uri: urlHasCommonBase(commonBase, clientMetadata.tosUri) ? clientMetadata.tosUri : undefined,
     };
+
     const headers = {
         "Accept": "application/json",
         "Content-Type": "application/json",