1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
|
# -*- coding: utf-8 -*-
# Copyright 2015 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from twisted.internet import defer
from synapse.events.utils import prune_event, old_prune_event
from syutil.jsonutil import encode_canonical_json
from synapse.crypto.event_signing import check_event_content_hash
from synapse.api.errors import SynapseError
import logging
logger = logging.getLogger(__name__)
class FederationBase(object):
@defer.inlineCallbacks
def _check_sigs_and_hash_and_fetch(self, origin, pdus, outlier=False):
"""Takes a list of PDUs and checks the signatures and hashs of each
one. If a PDU fails its signature check then we check if we have it in
the database and if not then request if from the originating server of
that PDU.
If a PDU fails its content hash check then it is redacted.
The given list of PDUs are not modified, instead the function returns
a new list.
Args:
pdu (list)
outlier (bool)
Returns:
Deferred : A list of PDUs that have valid signatures and hashes.
"""
signed_pdus = []
for pdu in pdus:
try:
new_pdu = yield self._check_sigs_and_hash(pdu)
signed_pdus.append(new_pdu)
except SynapseError:
# FIXME: We should handle signature failures more gracefully.
# Check local db.
new_pdu = yield self.store.get_event(
pdu.event_id,
allow_rejected=True
)
if new_pdu:
signed_pdus.append(new_pdu)
continue
# Check pdu.origin
if pdu.origin != origin:
new_pdu = yield self.get_pdu(
destinations=[pdu.origin],
event_id=pdu.event_id,
outlier=outlier,
)
if new_pdu:
signed_pdus.append(new_pdu)
continue
logger.warn("Failed to find copy of %s with valid signature")
defer.returnValue(signed_pdus)
@defer.inlineCallbacks
def _check_sigs_and_hash(self, pdu):
"""Throws a SynapseError if the PDU does not have the correct
signatures.
Returns:
FrozenEvent: Either the given event or it redacted if it failed the
content hash check.
"""
# Check signatures are correct.
redacted_event = prune_event(pdu)
redacted_pdu_json = redacted_event.get_pdu_json()
old_redacted = old_prune_event(pdu)
old_redacted_pdu_json = old_redacted.get_pdu_json()
try:
try:
yield self.keyring.verify_json_for_server(
pdu.origin, old_redacted_pdu_json
)
except SynapseError:
yield self.keyring.verify_json_for_server(
pdu.origin, redacted_pdu_json
)
except SynapseError:
logger.warn(
"Signature check failed for %s redacted to %s",
encode_canonical_json(pdu.get_pdu_json()),
encode_canonical_json(redacted_pdu_json),
)
raise
if not check_event_content_hash(pdu):
logger.warn(
"Event content has been tampered, redacting %s, %s",
pdu.event_id, encode_canonical_json(pdu.get_dict())
)
defer.returnValue(redacted_event)
defer.returnValue(pdu)
|
