1 // Copyright 2012 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "net/http/transport_security_persister.h"
6
7 #include <algorithm>
8 #include <cstdint>
9 #include <memory>
10 #include <utility>
11 #include <vector>
12
13 #include "base/base64.h"
14 #include "base/feature_list.h"
15 #include "base/files/file_path.h"
16 #include "base/files/file_util.h"
17 #include "base/functional/bind.h"
18 #include "base/functional/callback.h"
19 #include "base/json/json_reader.h"
20 #include "base/json/json_writer.h"
21 #include "base/location.h"
22 #include "base/task/sequenced_task_runner.h"
23 #include "base/task/single_thread_task_runner.h"
24 #include "base/values.h"
25 #include "net/base/features.h"
26 #include "net/base/network_anonymization_key.h"
27 #include "net/cert/x509_certificate.h"
28 #include "net/http/transport_security_state.h"
29 #include "third_party/abseil-cpp/absl/types/optional.h"
30
31 namespace net {
32
33 namespace {
34
35 // This function converts the binary hashes to a base64 string which we can
36 // include in a JSON file.
HashedDomainToExternalString(const TransportSecurityState::HashedHost & hashed)37 std::string HashedDomainToExternalString(
38 const TransportSecurityState::HashedHost& hashed) {
39 return base::Base64Encode(hashed);
40 }
41
42 // This inverts |HashedDomainToExternalString|, above. It turns an external
43 // string (from a JSON file) into an internal (binary) array.
ExternalStringToHashedDomain(const std::string & external)44 absl::optional<TransportSecurityState::HashedHost> ExternalStringToHashedDomain(
45 const std::string& external) {
46 TransportSecurityState::HashedHost out;
47 absl::optional<std::vector<uint8_t>> hashed = base::Base64Decode(external);
48 if (!hashed.has_value() || hashed.value().size() != out.size()) {
49 return absl::nullopt;
50 }
51
52 std::copy_n(hashed.value().begin(), out.size(), out.begin());
53 return out;
54 }
55
56 // Version 2 of the on-disk format consists of a single JSON object. The
57 // top-level dictionary has "version", "sts", and "expect_ct" entries. The first
58 // is an integer, the latter two are unordered lists of dictionaries, each
59 // representing cached data for a single host.
60
61 // Stored in serialized dictionary values to distinguish incompatible versions.
62 // Version 1 is distinguished by the lack of an integer version value.
63 const char kVersionKey[] = "version";
64 const int kCurrentVersionValue = 2;
65
66 // Keys in top level serialized dictionary, for lists of STS and Expect-CT
67 // entries, respectively. The Expect-CT key is legacy and deleted when read.
68 const char kSTSKey[] = "sts";
69 const char kExpectCTKey[] = "expect_ct";
70
71 // Hostname entry, used in serialized STS dictionaries. Value is produced by
72 // passing hashed hostname strings to HashedDomainToExternalString().
73 const char kHostname[] = "host";
74
75 // Key values in serialized STS entries.
76 const char kStsIncludeSubdomains[] = "sts_include_subdomains";
77 const char kStsObserved[] = "sts_observed";
78 const char kExpiry[] = "expiry";
79 const char kMode[] = "mode";
80
81 // Values for "mode" used in serialized STS entries.
82 const char kForceHTTPS[] = "force-https";
83 const char kDefault[] = "default";
84
LoadState(const base::FilePath & path)85 std::string LoadState(const base::FilePath& path) {
86 std::string result;
87 if (!base::ReadFileToString(path, &result)) {
88 return "";
89 }
90 return result;
91 }
92
93 // Serializes STS data from |state| to a Value.
SerializeSTSData(const TransportSecurityState * state)94 base::Value::List SerializeSTSData(const TransportSecurityState* state) {
95 base::Value::List sts_list;
96
97 TransportSecurityState::STSStateIterator sts_iterator(*state);
98 for (; sts_iterator.HasNext(); sts_iterator.Advance()) {
99 const TransportSecurityState::STSState& sts_state =
100 sts_iterator.domain_state();
101
102 base::Value::Dict serialized;
103 serialized.Set(kHostname,
104 HashedDomainToExternalString(sts_iterator.hostname()));
105 serialized.Set(kStsIncludeSubdomains, sts_state.include_subdomains);
106 serialized.Set(kStsObserved,
107 sts_state.last_observed.InSecondsFSinceUnixEpoch());
108 serialized.Set(kExpiry, sts_state.expiry.InSecondsFSinceUnixEpoch());
109
110 switch (sts_state.upgrade_mode) {
111 case TransportSecurityState::STSState::MODE_FORCE_HTTPS:
112 serialized.Set(kMode, kForceHTTPS);
113 break;
114 case TransportSecurityState::STSState::MODE_DEFAULT:
115 serialized.Set(kMode, kDefault);
116 break;
117 }
118
119 sts_list.Append(std::move(serialized));
120 }
121 return sts_list;
122 }
123
124 // Deserializes STS data from a Value created by the above method.
DeserializeSTSData(const base::Value & sts_list,TransportSecurityState * state)125 void DeserializeSTSData(const base::Value& sts_list,
126 TransportSecurityState* state) {
127 if (!sts_list.is_list())
128 return;
129
130 base::Time current_time(base::Time::Now());
131
132 for (const base::Value& sts_entry : sts_list.GetList()) {
133 const base::Value::Dict* sts_dict = sts_entry.GetIfDict();
134 if (!sts_dict)
135 continue;
136
137 const std::string* hostname = sts_dict->FindString(kHostname);
138 absl::optional<bool> sts_include_subdomains =
139 sts_dict->FindBool(kStsIncludeSubdomains);
140 absl::optional<double> sts_observed = sts_dict->FindDouble(kStsObserved);
141 absl::optional<double> expiry = sts_dict->FindDouble(kExpiry);
142 const std::string* mode = sts_dict->FindString(kMode);
143
144 if (!hostname || !sts_include_subdomains.has_value() ||
145 !sts_observed.has_value() || !expiry.has_value() || !mode) {
146 continue;
147 }
148
149 TransportSecurityState::STSState sts_state;
150 sts_state.include_subdomains = *sts_include_subdomains;
151 sts_state.last_observed =
152 base::Time::FromSecondsSinceUnixEpoch(*sts_observed);
153 sts_state.expiry = base::Time::FromSecondsSinceUnixEpoch(*expiry);
154
155 if (*mode == kForceHTTPS) {
156 sts_state.upgrade_mode =
157 TransportSecurityState::STSState::MODE_FORCE_HTTPS;
158 } else if (*mode == kDefault) {
159 sts_state.upgrade_mode = TransportSecurityState::STSState::MODE_DEFAULT;
160 } else {
161 continue;
162 }
163
164 if (sts_state.expiry < current_time || !sts_state.ShouldUpgradeToSSL())
165 continue;
166
167 absl::optional<TransportSecurityState::HashedHost> hashed =
168 ExternalStringToHashedDomain(*hostname);
169 if (!hashed.has_value())
170 continue;
171
172 state->AddOrUpdateEnabledSTSHosts(hashed.value(), sts_state);
173 }
174 }
175
OnWriteFinishedTask(scoped_refptr<base::SequencedTaskRunner> task_runner,base::OnceClosure callback,bool result)176 void OnWriteFinishedTask(scoped_refptr<base::SequencedTaskRunner> task_runner,
177 base::OnceClosure callback,
178 bool result) {
179 task_runner->PostTask(FROM_HERE, std::move(callback));
180 }
181
182 } // namespace
183
TransportSecurityPersister(TransportSecurityState * state,const scoped_refptr<base::SequencedTaskRunner> & background_runner,const base::FilePath & data_path)184 TransportSecurityPersister::TransportSecurityPersister(
185 TransportSecurityState* state,
186 const scoped_refptr<base::SequencedTaskRunner>& background_runner,
187 const base::FilePath& data_path)
188 : transport_security_state_(state),
189 writer_(data_path, background_runner),
190 foreground_runner_(base::SingleThreadTaskRunner::GetCurrentDefault()),
191 background_runner_(background_runner) {
192 transport_security_state_->SetDelegate(this);
193
194 background_runner_->PostTaskAndReplyWithResult(
195 FROM_HERE, base::BindOnce(&LoadState, writer_.path()),
196 base::BindOnce(&TransportSecurityPersister::CompleteLoad,
197 weak_ptr_factory_.GetWeakPtr()));
198 }
199
~TransportSecurityPersister()200 TransportSecurityPersister::~TransportSecurityPersister() {
201 DCHECK(foreground_runner_->RunsTasksInCurrentSequence());
202
203 if (writer_.HasPendingWrite())
204 writer_.DoScheduledWrite();
205
206 transport_security_state_->SetDelegate(nullptr);
207 }
208
StateIsDirty(TransportSecurityState * state)209 void TransportSecurityPersister::StateIsDirty(TransportSecurityState* state) {
210 DCHECK(foreground_runner_->RunsTasksInCurrentSequence());
211 DCHECK_EQ(transport_security_state_, state);
212
213 writer_.ScheduleWrite(this);
214 }
215
WriteNow(TransportSecurityState * state,base::OnceClosure callback)216 void TransportSecurityPersister::WriteNow(TransportSecurityState* state,
217 base::OnceClosure callback) {
218 DCHECK(foreground_runner_->RunsTasksInCurrentSequence());
219 DCHECK_EQ(transport_security_state_, state);
220
221 writer_.RegisterOnNextWriteCallbacks(
222 base::OnceClosure(),
223 base::BindOnce(
224 &OnWriteFinishedTask, foreground_runner_,
225 base::BindOnce(&TransportSecurityPersister::OnWriteFinished,
226 weak_ptr_factory_.GetWeakPtr(), std::move(callback))));
227 absl::optional<std::string> data = SerializeData();
228 if (data) {
229 writer_.WriteNow(std::move(data).value());
230 } else {
231 writer_.WriteNow(std::string());
232 }
233 }
234
OnWriteFinished(base::OnceClosure callback)235 void TransportSecurityPersister::OnWriteFinished(base::OnceClosure callback) {
236 DCHECK(foreground_runner_->RunsTasksInCurrentSequence());
237 std::move(callback).Run();
238 }
239
SerializeData()240 absl::optional<std::string> TransportSecurityPersister::SerializeData() {
241 CHECK(foreground_runner_->RunsTasksInCurrentSequence());
242
243 base::Value::Dict toplevel;
244 toplevel.Set(kVersionKey, kCurrentVersionValue);
245 toplevel.Set(kSTSKey, SerializeSTSData(transport_security_state_));
246
247 std::string output;
248 if (!base::JSONWriter::Write(toplevel, &output)) {
249 return absl::nullopt;
250 }
251 return output;
252 }
253
LoadEntries(const std::string & serialized)254 void TransportSecurityPersister::LoadEntries(const std::string& serialized) {
255 DCHECK(foreground_runner_->RunsTasksInCurrentSequence());
256
257 transport_security_state_->ClearDynamicData();
258 bool contains_legacy_expect_ct_data = false;
259 Deserialize(serialized, transport_security_state_,
260 contains_legacy_expect_ct_data);
261 if (contains_legacy_expect_ct_data) {
262 StateIsDirty(transport_security_state_);
263 }
264 }
265
Deserialize(const std::string & serialized,TransportSecurityState * state,bool & contains_legacy_expect_ct_data)266 void TransportSecurityPersister::Deserialize(
267 const std::string& serialized,
268 TransportSecurityState* state,
269 bool& contains_legacy_expect_ct_data) {
270 absl::optional<base::Value> value = base::JSONReader::Read(serialized);
271 if (!value || !value->is_dict())
272 return;
273
274 base::Value::Dict& dict = value->GetDict();
275 absl::optional<int> version = dict.FindInt(kVersionKey);
276
277 // Stop if the data is out of date (or in the previous format that didn't have
278 // a version number).
279 if (!version || *version != kCurrentVersionValue)
280 return;
281
282 base::Value* sts_value = dict.Find(kSTSKey);
283 if (sts_value)
284 DeserializeSTSData(*sts_value, state);
285
286 // If an Expect-CT key is found on deserialization, record this so that a
287 // write can be scheduled to clear it from disk.
288 contains_legacy_expect_ct_data = !!dict.Find(kExpectCTKey);
289 }
290
CompleteLoad(const std::string & state)291 void TransportSecurityPersister::CompleteLoad(const std::string& state) {
292 DCHECK(foreground_runner_->RunsTasksInCurrentSequence());
293
294 if (state.empty())
295 return;
296
297 LoadEntries(state);
298 }
299
300 } // namespace net
301