Remove tls_fingerprints option (#9280)

Signed-off-by: Jerin J Titus <72017981+jerinjtitus@users.noreply.github.com>

6 files changed, 1 insertions, 95 deletions

diff --git a/changelog.d/9280.removal b/changelog.d/9280.removal
new file mode 100644
index 0000000000..c2ed3d308d
--- /dev/null
+++ b/changelog.d/9280.removal
@@ -0,0 +1 @@
+Removed support for the deprecated `tls_fingerprints` configuration setting. Contributed by Jerin J Titus.
\ No newline at end of file
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index f0f9f06a6e..6576b153d0 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -683,33 +683,6 @@ acme:
     #
     account_key_file: DATADIR/acme_account.key
 
-# List of allowed TLS fingerprints for this server to publish along
-# with the signing keys for this server. Other matrix servers that
-# make HTTPS requests to this server will check that the TLS
-# certificates returned by this server match one of the fingerprints.
-#
-# Synapse automatically adds the fingerprint of its own certificate
-# to the list. So if federation traffic is handled directly by synapse
-# then no modification to the list is required.
-#
-# If synapse is run behind a load balancer that handles the TLS then it
-# will be necessary to add the fingerprints of the certificates used by
-# the loadbalancers to this list if they are different to the one
-# synapse is using.
-#
-# Homeservers are permitted to cache the list of TLS fingerprints
-# returned in the key responses up to the "valid_until_ts" returned in
-# key. It may be necessary to publish the fingerprints of a new
-# certificate and wait until the "valid_until_ts" of the previous key
-# responses have passed before deploying it.
-#
-# You can calculate a fingerprint from a given TLS listener via:
-# openssl s_client -connect $host:$port < /dev/null 2> /dev/null |
-#   openssl x509 -outform DER | openssl sha256 -binary | base64 | tr -d '='
-# or by checking matrix.org/federationtester/api/report?server_name=$host
-#
-#tls_fingerprints: [{"sha256": "<base64_encoded_sha256_fingerprint>"}]
-
 
 ## Federation ##
 
diff --git a/scripts-dev/convert_server_keys.py b/scripts-dev/convert_server_keys.py
index 961dc59f11..d4314a054c 100644
--- a/scripts-dev/convert_server_keys.py
+++ b/scripts-dev/convert_server_keys.py
@@ -1,4 +1,3 @@
-import hashlib
 import json
 import sys
 import time
@@ -54,15 +53,9 @@ def convert_v1_to_v2(server_name, valid_until, keys, certificate):
         "server_name": server_name,
         "verify_keys": {key_id: {"key": key} for key_id, key in keys.items()},
         "valid_until_ts": valid_until,
-        "tls_fingerprints": [fingerprint(certificate)],
     }
 
 
-def fingerprint(certificate):
-    finger = hashlib.sha256(certificate)
-    return {"sha256": encode_base64(finger.digest())}
-
-
 def rows_v2(server, json):
     valid_until = json["valid_until_ts"]
     key_json = encode_canonical_json(json)
diff --git a/synapse/config/tls.py b/synapse/config/tls.py
index 7df4e4c3e6..26f1150ca5 100644
--- a/synapse/config/tls.py
+++ b/synapse/config/tls.py
@@ -16,11 +16,8 @@ import logging
 import os
 import warnings
 from datetime import datetime
-from hashlib import sha256
 from typing import List, Optional, Pattern
 
-from unpaddedbase64 import encode_base64
-
 from OpenSSL import SSL, crypto
 from twisted.internet._sslverify import Certificate, trustRootFromCertificates
 
@@ -83,13 +80,6 @@ class TlsConfig(Config):
                     "configured."
                 )
 
-        self._original_tls_fingerprints = config.get("tls_fingerprints", [])
-
-        if self._original_tls_fingerprints is None:
-            self._original_tls_fingerprints = []
-
-        self.tls_fingerprints = list(self._original_tls_fingerprints)
-
         # Whether to verify certificates on outbound federation traffic
         self.federation_verify_certificates = config.get(
             "federation_verify_certificates", True
@@ -248,19 +238,6 @@ class TlsConfig(Config):
                     e,
                 )
 
-        self.tls_fingerprints = list(self._original_tls_fingerprints)
-
-        if self.tls_certificate:
-            # Check that our own certificate is included in the list of fingerprints
-            # and include it if it is not.
-            x509_certificate_bytes = crypto.dump_certificate(
-                crypto.FILETYPE_ASN1, self.tls_certificate
-            )
-            sha256_fingerprint = encode_base64(sha256(x509_certificate_bytes).digest())
-            sha256_fingerprints = {f["sha256"] for f in self.tls_fingerprints}
-            if sha256_fingerprint not in sha256_fingerprints:
-                self.tls_fingerprints.append({"sha256": sha256_fingerprint})
-
     def generate_config_section(
         self,
         config_dir_path,
@@ -443,33 +420,6 @@ class TlsConfig(Config):
             # If unspecified, we will use CONFDIR/client.key.
             #
             account_key_file: %(default_acme_account_file)s
-
-        # List of allowed TLS fingerprints for this server to publish along
-        # with the signing keys for this server. Other matrix servers that
-        # make HTTPS requests to this server will check that the TLS
-        # certificates returned by this server match one of the fingerprints.
-        #
-        # Synapse automatically adds the fingerprint of its own certificate
-        # to the list. So if federation traffic is handled directly by synapse
-        # then no modification to the list is required.
-        #
-        # If synapse is run behind a load balancer that handles the TLS then it
-        # will be necessary to add the fingerprints of the certificates used by
-        # the loadbalancers to this list if they are different to the one
-        # synapse is using.
-        #
-        # Homeservers are permitted to cache the list of TLS fingerprints
-        # returned in the key responses up to the "valid_until_ts" returned in
-        # key. It may be necessary to publish the fingerprints of a new
-        # certificate and wait until the "valid_until_ts" of the previous key
-        # responses have passed before deploying it.
-        #
-        # You can calculate a fingerprint from a given TLS listener via:
-        # openssl s_client -connect $host:$port < /dev/null 2> /dev/null |
-        #   openssl x509 -outform DER | openssl sha256 -binary | base64 | tr -d '='
-        # or by checking matrix.org/federationtester/api/report?server_name=$host
-        #
-        #tls_fingerprints: [{"sha256": "<base64_encoded_sha256_fingerprint>"}]
         """
             # Lowercase the string representation of boolean values
             % {
diff --git a/synapse/rest/key/v2/local_key_resource.py b/synapse/rest/key/v2/local_key_resource.py
index e8dbe240d8..a5fcd15e3a 100644
--- a/synapse/rest/key/v2/local_key_resource.py
+++ b/synapse/rest/key/v2/local_key_resource.py
@@ -48,11 +48,6 @@ class LocalKey(Resource):
                     "key": # base64 encoded NACL verification key.
                 }
             },
-            "tls_fingerprints": [ # Fingerprints of the TLS certs this server uses.
-                {
-                    "sha256": # base64 encoded sha256 fingerprint of the X509 cert
-                },
-            ],
             "signatures": {
                 "this.server.example.com": {
                    "algorithm:version": # NACL signature for this server
@@ -89,14 +84,11 @@ class LocalKey(Resource):
                 "expired_ts": key.expired_ts,
             }
 
-        tls_fingerprints = self.config.tls_fingerprints
-
         json_object = {
             "valid_until_ts": self.valid_until_ts,
             "server_name": self.config.server_name,
             "verify_keys": verify_keys,
             "old_verify_keys": old_verify_keys,
-            "tls_fingerprints": tls_fingerprints,
         }
         for key in self.config.signing_key:
             json_object = sign_json(json_object, self.config.server_name, key)
diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
index f648678b09..aba1734a55 100644
--- a/synapse/rest/key/v2/remote_key_resource.py
+++ b/synapse/rest/key/v2/remote_key_resource.py
@@ -73,9 +73,6 @@ class RemoteKey(DirectServeJsonResource):
                         "expired_ts": 0, # when the key stop being used.
                     }
                 }
-                "tls_fingerprints": [
-                    { "sha256": # fingerprint }
-                ]
                 "signatures": {
                     "remote.server.example.com": {...}
                     "this.server.example.com": {...}