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Modify StoreKeyFetcher to read from server_keys_json. (#15417)
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Before this change:

* `PerspectivesKeyFetcher` and `ServerKeyFetcher` write to `server_keys_json`.
* `PerspectivesKeyFetcher` also writes to `server_signature_keys`.
* `StoreKeyFetcher` reads from `server_signature_keys`.

After this change:

* `PerspectivesKeyFetcher` and `ServerKeyFetcher` write to `server_keys_json`.
* `PerspectivesKeyFetcher` also writes to `server_signature_keys`.
* `StoreKeyFetcher` reads from `server_keys_json`.

This results in `StoreKeyFetcher` now using the results from `ServerKeyFetcher`
in addition to those from `PerspectivesKeyFetcher`, i.e. keys which are directly
fetched from a server will now be pulled from the database instead of refetched.

An additional minor change is included to avoid creating a `PerspectivesKeyFetcher`
(and checking it) if no `trusted_key_servers` are configured.

The overall impact of this should be better usage of cached results:

* If a server has no trusted key servers configured then it should reduce how often keys
  are fetched.
* if a server's trusted key server does not have a requested server's keys cached then it
  should reduce how often keys are directly fetched.
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clokep authored Apr 20, 2023
1 parent ae69d69 commit 5e024a0
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1 change: 1 addition & 0 deletions changelog.d/15417.bugfix
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix a long-standing bug where cached key results which were directly fetched would not be properly re-used.
30 changes: 15 additions & 15 deletions synapse/crypto/keyring.py
Original file line number Diff line number Diff line change
Expand Up @@ -150,18 +150,19 @@ class Keyring:
def __init__(
self, hs: "HomeServer", key_fetchers: "Optional[Iterable[KeyFetcher]]" = None
):
self.clock = hs.get_clock()

if key_fetchers is None:
key_fetchers = (
# Fetch keys from the database.
StoreKeyFetcher(hs),
# Fetch keys from a configured Perspectives server.
PerspectivesKeyFetcher(hs),
# Fetch keys from the origin server directly.
ServerKeyFetcher(hs),
)
self._key_fetchers = key_fetchers
# Always fetch keys from the database.
mutable_key_fetchers: List[KeyFetcher] = [StoreKeyFetcher(hs)]
# Fetch keys from configured trusted key servers, if any exist.
key_servers = hs.config.key.key_servers
if key_servers:
mutable_key_fetchers.append(PerspectivesKeyFetcher(hs))
# Finally, fetch keys from the origin server directly.
mutable_key_fetchers.append(ServerKeyFetcher(hs))

self._key_fetchers: Iterable[KeyFetcher] = tuple(mutable_key_fetchers)
else:
self._key_fetchers = key_fetchers

self._fetch_keys_queue: BatchingQueue[
_FetchKeyRequest, Dict[str, Dict[str, FetchKeyResult]]
Expand Down Expand Up @@ -510,7 +511,7 @@ async def _fetch_keys(
for key_id in queue_value.key_ids
)

res = await self.store.get_server_verify_keys(key_ids_to_fetch)
res = await self.store.get_server_keys_json(key_ids_to_fetch)
keys: Dict[str, Dict[str, FetchKeyResult]] = {}
for (server_name, key_id), key in res.items():
keys.setdefault(server_name, {})[key_id] = key
Expand All @@ -522,7 +523,6 @@ def __init__(self, hs: "HomeServer"):
super().__init__(hs)

self.store = hs.get_datastores().main
self.config = hs.config

async def process_v2_response(
self, from_server: str, response_json: JsonDict, time_added_ms: int
Expand Down Expand Up @@ -626,7 +626,7 @@ def __init__(self, hs: "HomeServer"):
super().__init__(hs)
self.clock = hs.get_clock()
self.client = hs.get_federation_http_client()
self.key_servers = self.config.key.key_servers
self.key_servers = hs.config.key.key_servers

async def _fetch_keys(
self, keys_to_fetch: List[_FetchKeyRequest]
Expand Down Expand Up @@ -775,7 +775,7 @@ async def get_server_verify_key_v2_indirect(

keys.setdefault(server_name, {}).update(processed_response)

await self.store.store_server_verify_keys(
await self.store.store_server_signature_keys(
perspective_name, time_now_ms, added_keys
)

Expand Down
2 changes: 1 addition & 1 deletion synapse/rest/key/v2/remote_key_resource.py
Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,7 @@ async def query_keys(
for key_id in key_ids:
store_queries.append((server_name, key_id, None))

cached = await self.store.get_server_keys_json(store_queries)
cached = await self.store.get_server_keys_json_for_remote(store_queries)

json_results: Set[bytes] = set()

Expand Down
99 changes: 87 additions & 12 deletions synapse/storage/databases/main/keys.py
Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,12 @@
# limitations under the License.

import itertools
import json
import logging
from typing import Any, Dict, Iterable, List, Mapping, Optional, Tuple

from signedjson.key import decode_verify_key_bytes
from unpaddedbase64 import decode_base64

from synapse.storage._base import SQLBaseStore
from synapse.storage.database import LoggingTransaction
Expand All @@ -36,15 +38,16 @@ class KeyStore(SQLBaseStore):
"""Persistence for signature verification keys"""

@cached()
def _get_server_verify_key(
def _get_server_signature_key(
self, server_name_and_key_id: Tuple[str, str]
) -> FetchKeyResult:
raise NotImplementedError()

@cachedList(
cached_method_name="_get_server_verify_key", list_name="server_name_and_key_ids"
cached_method_name="_get_server_signature_key",
list_name="server_name_and_key_ids",
)
async def get_server_verify_keys(
async def get_server_signature_keys(
self, server_name_and_key_ids: Iterable[Tuple[str, str]]
) -> Dict[Tuple[str, str], FetchKeyResult]:
"""
Expand All @@ -62,10 +65,12 @@ def _get_keys(txn: Cursor, batch: Tuple[Tuple[str, str], ...]) -> None:
"""Processes a batch of keys to fetch, and adds the result to `keys`."""

# batch_iter always returns tuples so it's safe to do len(batch)
sql = (
"SELECT server_name, key_id, verify_key, ts_valid_until_ms "
"FROM server_signature_keys WHERE 1=0"
) + " OR (server_name=? AND key_id=?)" * len(batch)
sql = """
SELECT server_name, key_id, verify_key, ts_valid_until_ms
FROM server_signature_keys WHERE 1=0
""" + " OR (server_name=? AND key_id=?)" * len(
batch
)

txn.execute(sql, tuple(itertools.chain.from_iterable(batch)))

Expand All @@ -89,9 +94,9 @@ def _txn(txn: Cursor) -> Dict[Tuple[str, str], FetchKeyResult]:
_get_keys(txn, batch)
return keys

return await self.db_pool.runInteraction("get_server_verify_keys", _txn)
return await self.db_pool.runInteraction("get_server_signature_keys", _txn)

async def store_server_verify_keys(
async def store_server_signature_keys(
self,
from_server: str,
ts_added_ms: int,
Expand Down Expand Up @@ -119,7 +124,7 @@ async def store_server_verify_keys(
)
)
# invalidate takes a tuple corresponding to the params of
# _get_server_verify_key. _get_server_verify_key only takes one
# _get_server_signature_key. _get_server_signature_key only takes one
# param, which is itself the 2-tuple (server_name, key_id).
invalidations.append((server_name, key_id))

Expand All @@ -134,10 +139,10 @@ async def store_server_verify_keys(
"verify_key",
),
value_values=value_values,
desc="store_server_verify_keys",
desc="store_server_signature_keys",
)

invalidate = self._get_server_verify_key.invalidate
invalidate = self._get_server_signature_key.invalidate
for i in invalidations:
invalidate((i,))

Expand Down Expand Up @@ -180,16 +185,86 @@ async def store_server_keys_json(
desc="store_server_keys_json",
)

# invalidate takes a tuple corresponding to the params of
# _get_server_keys_json. _get_server_keys_json only takes one
# param, which is itself the 2-tuple (server_name, key_id).
self._get_server_keys_json.invalidate((((server_name, key_id),)))

@cached()
def _get_server_keys_json(
self, server_name_and_key_id: Tuple[str, str]
) -> FetchKeyResult:
raise NotImplementedError()

@cachedList(
cached_method_name="_get_server_keys_json", list_name="server_name_and_key_ids"
)
async def get_server_keys_json(
self, server_name_and_key_ids: Iterable[Tuple[str, str]]
) -> Dict[Tuple[str, str], FetchKeyResult]:
"""
Args:
server_name_and_key_ids:
iterable of (server_name, key-id) tuples to fetch keys for
Returns:
A map from (server_name, key_id) -> FetchKeyResult, or None if the
key is unknown
"""
keys = {}

def _get_keys(txn: Cursor, batch: Tuple[Tuple[str, str], ...]) -> None:
"""Processes a batch of keys to fetch, and adds the result to `keys`."""

# batch_iter always returns tuples so it's safe to do len(batch)
sql = """
SELECT server_name, key_id, key_json, ts_valid_until_ms
FROM server_keys_json WHERE 1=0
""" + " OR (server_name=? AND key_id=?)" * len(
batch
)

txn.execute(sql, tuple(itertools.chain.from_iterable(batch)))

for server_name, key_id, key_json_bytes, ts_valid_until_ms in txn:
if ts_valid_until_ms is None:
# Old keys may be stored with a ts_valid_until_ms of null,
# in which case we treat this as if it was set to `0`, i.e.
# it won't match key requests that define a minimum
# `ts_valid_until_ms`.
ts_valid_until_ms = 0

# The entire signed JSON response is stored in server_keys_json,
# fetch out the bits needed.
key_json = json.loads(bytes(key_json_bytes))
key_base64 = key_json["verify_keys"][key_id]["key"]

keys[(server_name, key_id)] = FetchKeyResult(
verify_key=decode_verify_key_bytes(
key_id, decode_base64(key_base64)
),
valid_until_ts=ts_valid_until_ms,
)

def _txn(txn: Cursor) -> Dict[Tuple[str, str], FetchKeyResult]:
for batch in batch_iter(server_name_and_key_ids, 50):
_get_keys(txn, batch)
return keys

return await self.db_pool.runInteraction("get_server_keys_json", _txn)

async def get_server_keys_json_for_remote(
self, server_keys: Iterable[Tuple[str, Optional[str], Optional[str]]]
) -> Dict[Tuple[str, Optional[str], Optional[str]], List[Dict[str, Any]]]:
"""Retrieve the key json for a list of server_keys and key ids.
If no keys are found for a given server, key_id and source then
that server, key_id, and source triplet entry will be an empty list.
The JSON is returned as a byte array so that it can be efficiently
used in an HTTP response.
Args:
server_keys: List of (server_name, key_id, source) triplets.
Returns:
A mapping from (server_name, key_id, source) triplets to a list of dicts
"""
Expand Down
62 changes: 31 additions & 31 deletions tests/crypto/test_keyring.py
Original file line number Diff line number Diff line change
Expand Up @@ -190,10 +190,23 @@ def test_verify_json_for_server(self) -> None:
kr = keyring.Keyring(self.hs)

key1 = signedjson.key.generate_signing_key("1")
r = self.hs.get_datastores().main.store_server_verify_keys(
r = self.hs.get_datastores().main.store_server_keys_json(
"server9",
int(time.time() * 1000),
{("server9", get_key_id(key1)): FetchKeyResult(get_verify_key(key1), 1000)},
get_key_id(key1),
from_server="test",
ts_now_ms=int(time.time() * 1000),
ts_expires_ms=1000,
# The entire response gets signed & stored, just include the bits we
# care about.
key_json_bytes=canonicaljson.encode_canonical_json(
{
"verify_keys": {
get_key_id(key1): {
"key": encode_verify_key_base64(get_verify_key(key1))
}
}
}
),
)
self.get_success(r)

Expand Down Expand Up @@ -280,45 +293,26 @@ def test_verify_json_for_server_with_null_valid_until_ms(self) -> None:
mock_fetcher = Mock()
mock_fetcher.get_keys = Mock(return_value=make_awaitable({}))

kr = keyring.Keyring(
self.hs, key_fetchers=(StoreKeyFetcher(self.hs), mock_fetcher)
)

key1 = signedjson.key.generate_signing_key("1")
r = self.hs.get_datastores().main.store_server_verify_keys(
r = self.hs.get_datastores().main.store_server_signature_keys(
"server9",
int(time.time() * 1000),
# None is not a valid value in FetchKeyResult, but we're abusing this
# API to insert null values into the database. The nulls get converted
# to 0 when fetched in KeyStore.get_server_verify_keys.
# to 0 when fetched in KeyStore.get_server_signature_keys.
{("server9", get_key_id(key1)): FetchKeyResult(get_verify_key(key1), None)}, # type: ignore[arg-type]
)
self.get_success(r)

json1: JsonDict = {}
signedjson.sign.sign_json(json1, "server9", key1)

# should fail immediately on an unsigned object
d = kr.verify_json_for_server("server9", {}, 0)
self.get_failure(d, SynapseError)

# should fail on a signed object with a non-zero minimum_valid_until_ms,
# as it tries to refetch the keys and fails.
d = kr.verify_json_for_server("server9", json1, 500)
self.get_failure(d, SynapseError)

# We expect the keyring tried to refetch the key once.
mock_fetcher.get_keys.assert_called_once_with(
"server9", [get_key_id(key1)], 500
)

# should succeed on a signed object with a 0 minimum_valid_until_ms
d = kr.verify_json_for_server(
"server9",
json1,
0,
d = self.hs.get_datastores().main.get_server_signature_keys(
[("server9", get_key_id(key1))]
)
self.get_success(d)
result = self.get_success(d)
self.assertEquals(result[("server9", get_key_id(key1))].valid_until_ts, 0)

def test_verify_json_dedupes_key_requests(self) -> None:
"""Two requests for the same key should be deduped."""
Expand Down Expand Up @@ -464,7 +458,9 @@ async def get_json(destination: str, path: str, **kwargs: Any) -> JsonDict:
# check that the perspectives store is correctly updated
lookup_triplet = (SERVER_NAME, testverifykey_id, None)
key_json = self.get_success(
self.hs.get_datastores().main.get_server_keys_json([lookup_triplet])
self.hs.get_datastores().main.get_server_keys_json_for_remote(
[lookup_triplet]
)
)
res_keys = key_json[lookup_triplet]
self.assertEqual(len(res_keys), 1)
Expand Down Expand Up @@ -582,7 +578,9 @@ def test_get_keys_from_perspectives(self) -> None:
# check that the perspectives store is correctly updated
lookup_triplet = (SERVER_NAME, testverifykey_id, None)
key_json = self.get_success(
self.hs.get_datastores().main.get_server_keys_json([lookup_triplet])
self.hs.get_datastores().main.get_server_keys_json_for_remote(
[lookup_triplet]
)
)
res_keys = key_json[lookup_triplet]
self.assertEqual(len(res_keys), 1)
Expand Down Expand Up @@ -703,7 +701,9 @@ def test_get_perspectives_own_key(self) -> None:
# check that the perspectives store is correctly updated
lookup_triplet = (SERVER_NAME, testverifykey_id, None)
key_json = self.get_success(
self.hs.get_datastores().main.get_server_keys_json([lookup_triplet])
self.hs.get_datastores().main.get_server_keys_json_for_remote(
[lookup_triplet]
)
)
res_keys = key_json[lookup_triplet]
self.assertEqual(len(res_keys), 1)
Expand Down
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