Use the federation blacklist for requests to untrusted Identity Servers (#6000)

Uses a SimpleHttpClient instance equipped with the federation_ip_range_blacklist list for requests to identity servers provided by user input. Does not use a blacklist when contacting identity servers specified by account_threepid_delegates. The homeserver trusts the latter and we don't want to prevent homeserver admins from specifying delegates that are on internal IP addresses.

Fixes #5935

1 files changed, 15 insertions, 3 deletions

diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index af6f591942..264bdc2189 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -31,6 +31,7 @@ from synapse.api.errors import (
     SynapseError,
 )
 from synapse.config.emailconfig import ThreepidBehaviour
+from synapse.http.client import SimpleHttpClient
 from synapse.util.stringutils import random_string
 
 from ._base import BaseHandler
@@ -42,7 +43,12 @@ class IdentityHandler(BaseHandler):
     def __init__(self, hs):
         super(IdentityHandler, self).__init__(hs)
 
-        self.http_client = hs.get_simple_http_client()
+        self.http_client = SimpleHttpClient(hs)
+        # We create a blacklisting instance of SimpleHttpClient for contacting identity
+        # servers specified by clients
+        self.blacklisting_http_client = SimpleHttpClient(
+            hs, ip_blacklist=hs.config.federation_ip_range_blacklist
+        )
         self.federation_http_client = hs.get_http_client()
         self.hs = hs
 
@@ -143,7 +149,9 @@ class IdentityHandler(BaseHandler):
             bind_url = "https://%s/_matrix/identity/api/v1/3pid/bind" % (id_server,)
 
         try:
-            data = yield self.http_client.post_json_get_json(
+            # Use the blacklisting http client as this call is only to identity servers
+            # provided by a client
+            data = yield self.blacklisting_http_client.post_json_get_json(
                 bind_url, bind_data, headers=headers
             )
 
@@ -246,7 +254,11 @@ class IdentityHandler(BaseHandler):
         headers = {b"Authorization": auth_headers}
 
         try:
-            yield self.http_client.post_json_get_json(url, content, headers)
+            # Use the blacklisting http client as this call is only to identity servers
+            # provided by a client
+            yield self.blacklisting_http_client.post_json_get_json(
+                url, content, headers
+            )
             changed = True
         except HttpResponseException as e:
             changed = False