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
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
|
// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/cert/multi_log_ct_verifier.h"
#include <vector>
#include "base/bind.h"
#include "base/callback_helpers.h"
#include "base/metrics/histogram.h"
#include "net/base/net_errors.h"
#include "net/base/net_log.h"
#include "net/cert/ct_log_verifier.h"
#include "net/cert/ct_objects_extractor.h"
#include "net/cert/ct_serialization.h"
#include "net/cert/ct_signed_certificate_timestamp_log_param.h"
#include "net/cert/ct_verify_result.h"
#include "net/cert/sct_status_flags.h"
#include "net/cert/x509_certificate.h"
namespace net {
namespace {
// Record SCT verification status. This metric would help detecting presence
// of unknown CT logs as well as bad deployments (invalid SCTs).
void LogSCTStatusToUMA(ct::SCTVerifyStatus status) {
UMA_HISTOGRAM_ENUMERATION(
"Net.CertificateTransparency.SCTStatus", status, ct::SCT_STATUS_MAX);
}
// Record SCT origin enum. This metric measure the popularity
// of the various channels of providing SCTs for a certificate.
void LogSCTOriginToUMA(ct::SignedCertificateTimestamp::Origin origin) {
UMA_HISTOGRAM_ENUMERATION("Net.CertificateTransparency.SCTOrigin",
origin,
ct::SignedCertificateTimestamp::SCT_ORIGIN_MAX);
}
// Count the number of SCTs that were available for each SSL connection
// (including SCTs embedded in the certificate).
// This metric would allow measuring:
// * Of all SSL connections, how many had SCTs available for validation.
// * When SCTs are available, how many are available per connection.
void LogNumSCTsToUMA(const ct::CTVerifyResult& result) {
UMA_HISTOGRAM_CUSTOM_COUNTS("Net.CertificateTransparency.SCTsPerConnection",
result.invalid_scts.size() +
result.verified_scts.size() +
result.unknown_logs_scts.size(),
1,
10,
11);
}
} // namespace
MultiLogCTVerifier::MultiLogCTVerifier() { }
MultiLogCTVerifier::~MultiLogCTVerifier() { }
void MultiLogCTVerifier::AddLog(scoped_ptr<CTLogVerifier> log_verifier) {
DCHECK(log_verifier);
if (!log_verifier)
return;
linked_ptr<CTLogVerifier> log(log_verifier.release());
logs_[log->key_id()] = log;
}
void MultiLogCTVerifier::AddLogs(
ScopedVector<CTLogVerifier> log_verifiers) {
for (ScopedVector<CTLogVerifier>::iterator it =
log_verifiers.begin(); it != log_verifiers.end(); ++it) {
linked_ptr<CTLogVerifier> log(*it);
VLOG(1) << "Adding CT log: " << log->description();
logs_[log->key_id()] = log;
}
// Ownership of the pointers in |log_verifiers| is transferred to |logs_|
log_verifiers.weak_clear();
}
int MultiLogCTVerifier::Verify(
X509Certificate* cert,
const std::string& stapled_ocsp_response,
const std::string& sct_list_from_tls_extension,
ct::CTVerifyResult* result,
const BoundNetLog& net_log) {
DCHECK(cert);
DCHECK(result);
result->verified_scts.clear();
result->invalid_scts.clear();
result->unknown_logs_scts.clear();
bool has_verified_scts = false;
std::string embedded_scts;
if (!cert->GetIntermediateCertificates().empty() &&
ct::ExtractEmbeddedSCTList(
cert->os_cert_handle(),
&embedded_scts)) {
ct::LogEntry precert_entry;
has_verified_scts =
ct::GetPrecertLogEntry(
cert->os_cert_handle(),
cert->GetIntermediateCertificates().front(),
&precert_entry) &&
VerifySCTs(
embedded_scts,
precert_entry,
ct::SignedCertificateTimestamp::SCT_EMBEDDED,
result);
}
std::string sct_list_from_ocsp;
if (!stapled_ocsp_response.empty() &&
!cert->GetIntermediateCertificates().empty()) {
ct::ExtractSCTListFromOCSPResponse(
cert->GetIntermediateCertificates().front(), cert->serial_number(),
stapled_ocsp_response, &sct_list_from_ocsp);
}
// Log to Net Log, after extracting SCTs but before possibly failing on
// X.509 entry creation.
NetLog::ParametersCallback net_log_callback =
base::Bind(&NetLogRawSignedCertificateTimestampCallback,
&embedded_scts, &sct_list_from_ocsp, &sct_list_from_tls_extension);
net_log.AddEvent(
NetLog::TYPE_SIGNED_CERTIFICATE_TIMESTAMPS_RECEIVED,
net_log_callback);
ct::LogEntry x509_entry;
if (ct::GetX509LogEntry(cert->os_cert_handle(), &x509_entry)) {
has_verified_scts |= VerifySCTs(
sct_list_from_ocsp,
x509_entry,
ct::SignedCertificateTimestamp::SCT_FROM_OCSP_RESPONSE,
result);
has_verified_scts |= VerifySCTs(
sct_list_from_tls_extension,
x509_entry,
ct::SignedCertificateTimestamp::SCT_FROM_TLS_EXTENSION,
result);
}
NetLog::ParametersCallback net_log_checked_callback =
base::Bind(&NetLogSignedCertificateTimestampCallback, result);
net_log.AddEvent(
NetLog::TYPE_SIGNED_CERTIFICATE_TIMESTAMPS_CHECKED,
net_log_checked_callback);
LogNumSCTsToUMA(*result);
if (has_verified_scts)
return OK;
return ERR_CT_NO_SCTS_VERIFIED_OK;
}
bool MultiLogCTVerifier::VerifySCTs(
const std::string& encoded_sct_list,
const ct::LogEntry& expected_entry,
ct::SignedCertificateTimestamp::Origin origin,
ct::CTVerifyResult* result) {
if (logs_.empty())
return false;
base::StringPiece temp(encoded_sct_list);
std::vector<base::StringPiece> sct_list;
if (!ct::DecodeSCTList(&temp, &sct_list))
return false;
bool verified = false;
for (std::vector<base::StringPiece>::const_iterator it = sct_list.begin();
it != sct_list.end(); ++it) {
base::StringPiece encoded_sct(*it);
LogSCTOriginToUMA(origin);
scoped_refptr<ct::SignedCertificateTimestamp> decoded_sct;
if (!DecodeSignedCertificateTimestamp(&encoded_sct, &decoded_sct)) {
LogSCTStatusToUMA(ct::SCT_STATUS_NONE);
// XXX(rsleevi): Should we really just skip over bad SCTs?
continue;
}
decoded_sct->origin = origin;
verified |= VerifySingleSCT(decoded_sct, expected_entry, result);
}
return verified;
}
bool MultiLogCTVerifier::VerifySingleSCT(
scoped_refptr<ct::SignedCertificateTimestamp> sct,
const ct::LogEntry& expected_entry,
ct::CTVerifyResult* result) {
// Assume this SCT is untrusted until proven otherwise.
IDToLogMap::iterator it = logs_.find(sct->log_id);
if (it == logs_.end()) {
DVLOG(1) << "SCT does not match any known log.";
result->unknown_logs_scts.push_back(sct);
LogSCTStatusToUMA(ct::SCT_STATUS_LOG_UNKNOWN);
return false;
}
sct->log_description = it->second->description();
if (!it->second->Verify(expected_entry, *sct.get())) {
DVLOG(1) << "Unable to verify SCT signature.";
result->invalid_scts.push_back(sct);
LogSCTStatusToUMA(ct::SCT_STATUS_INVALID);
return false;
}
// SCT verified ok, just make sure the timestamp is legitimate.
if (sct->timestamp > base::Time::Now()) {
DVLOG(1) << "SCT is from the future!";
result->invalid_scts.push_back(sct);
LogSCTStatusToUMA(ct::SCT_STATUS_INVALID);
return false;
}
LogSCTStatusToUMA(ct::SCT_STATUS_OK);
result->verified_scts.push_back(sct);
return true;
}
} // namespace net
|
