File: download_protection_delegate_android.cc

package info (click to toggle)
chromium 139.0.7258.127-1
  • links: PTS, VCS
  • area: main
  • in suites:
  • size: 6,122,068 kB
  • sloc: cpp: 35,100,771; ansic: 7,163,530; javascript: 4,103,002; python: 1,436,920; asm: 946,517; xml: 746,709; pascal: 187,653; perl: 88,691; sh: 88,436; objc: 79,953; sql: 51,488; cs: 44,583; fortran: 24,137; makefile: 22,147; tcl: 15,277; php: 13,980; yacc: 8,984; ruby: 7,485; awk: 3,720; lisp: 3,096; lex: 1,327; ada: 727; jsp: 228; sed: 36
file content (383 lines) | stat: -rw-r--r-- 15,067 bytes parent folder | download | duplicates (3)
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
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/safe_browsing/download_protection/download_protection_delegate_android.h"

#include <algorithm>
#include <vector>

#include "base/feature_list.h"
#include "base/files/file_path.h"
#include "base/functional/bind.h"
#include "base/metrics/histogram_functions.h"
#include "base/notreached.h"
#include "base/rand_util.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/safe_browsing/android/download_protection_metrics_data.h"
#include "chrome/browser/safe_browsing/android/safe_browsing_referring_app_bridge_android.h"
#include "chrome/browser/safe_browsing/download_protection/check_client_download_request.h"
#include "chrome/browser/safe_browsing/download_protection/check_file_system_access_write_request.h"
#include "chrome/browser/safe_browsing/download_protection/download_protection_util.h"
#include "components/download/public/common/download_item.h"
#include "components/google/core/common/google_util.h"
#include "components/safe_browsing/android/safe_browsing_api_handler_bridge.h"
#include "components/safe_browsing/core/browser/referring_app_info.h"
#include "components/safe_browsing/core/common/features.h"
#include "components/safe_browsing/core/common/proto/csd.pb.h"
#include "components/safe_browsing/core/common/safe_browsing_prefs.h"
#include "components/version_info/android/channel_getter.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/download_item_utils.h"
#include "google_apis/common/api_key_request_util.h"
#include "google_apis/google_api_keys.h"
#include "net/http/http_request_headers.h"
#include "services/network/public/cpp/resource_request.h"
#include "url/url_constants.h"

namespace safe_browsing {
namespace {

using Outcome = DownloadProtectionMetricsData::AndroidDownloadProtectionOutcome;

// Default URL for download check server.
const char kDownloadRequestDefaultUrl[] =
    "https://androidchromeprotect.pa.googleapis.com/v1/download";

// Content-Type HTTP header field for the request.
const char kProtobufContentType[] = "application/x-protobuf";

// We sample 1% of allowlisted downloads to still send out download pings if
// other conditions are met.
const double kAllowlistDownloadSampleRate = 0.01;

bool IsDownloadRequestUrlValid(const GURL& url) {
  return url.is_valid() && url.SchemeIs(url::kHttpsScheme) &&
         google_util::IsGoogleAssociatedDomainUrl(url);
}

GURL ConstructDownloadRequestUrl() {
  std::string url_override = kMaliciousApkDownloadCheckServiceUrlOverride.Get();
  GURL url(url_override);
  if (!IsDownloadRequestUrlValid(url)) {
    url = GURL(kDownloadRequestDefaultUrl);
  }
  return url;
}

// Determines whether Android download protection should be active.
bool IsAndroidDownloadProtectionEnabled(Profile* profile) {
  if (!base::FeatureList::IsEnabled(kMaliciousApkDownloadCheck)) {
    return false;
  }

  if (!profile || !profile->GetPrefs()) {
    return false;
  }

  // Android download protection should only ever be enabled if Safe Browsing is
  // enabled.
  if (!IsSafeBrowsingEnabled(*profile->GetPrefs())) {
    return false;
  }

  // In telemetry-only mode, APK download checks should only be active for
  // Enhanced Protection users.
  if (kMaliciousApkDownloadCheckTelemetryOnly.Get() &&
      !IsEnhancedProtectionEnabled(*profile->GetPrefs())) {
    return false;
  }
  return true;
}

// Determines whether Android download protection should be active.
// Also sets the metrics outcome if the result is disabled.
bool IsAndroidDownloadProtectionEnabledForDownloadProfile(
    download::DownloadItem* item) {
  CHECK(item);
  bool enabled = IsAndroidDownloadProtectionEnabled(Profile::FromBrowserContext(
      content::DownloadItemUtils::GetBrowserContext(item)));
  if (!enabled) {
    DownloadProtectionMetricsData::SetOutcome(
        item, Outcome::kDownloadProtectionDisabled);
  }
  return enabled;
}

void LogGetReferringAppInfoResult(internal::GetReferringAppInfoResult result) {
  base::UmaHistogramEnumeration(
      "SBClientDownload.Android.GetReferringAppInfo.Result", result);
}

void PopulateReferringAppInfoInProto(internal::ReferringAppInfo info,
                                     ClientDownloadRequest* request_proto) {
  *request_proto->mutable_referring_app_info() = GetReferringAppInfoProto(info);
}

void MaybePopulateReferringAppInfo(const download::DownloadItem* item,
                                   CollectModificationCallback callback) {
  CHECK(item);
  // Note: The web_contents will be null if the original download page has
  // been navigated away from.
  content::WebContents* web_contents =
      content::DownloadItemUtils::GetWebContents(item);
  if (!web_contents) {
    LogGetReferringAppInfoResult(
        internal::GetReferringAppInfoResult::kNotAttempted);
    std::move(callback).Run(NoModificationToRequestProto());
    return;
  }
  internal::ReferringAppInfo info =
      GetReferringAppInfo(web_contents, /*get_webapk_info=*/true);
  LogGetReferringAppInfoResult(internal::ReferringAppInfoToResult(info));
  if (!info.has_referring_app() && !info.has_referring_webapk()) {
    std::move(callback).Run(NoModificationToRequestProto());
    return;
  }

  std::move(callback).Run(
      base::BindOnce(&PopulateReferringAppInfoInProto, std::move(info)));
}

void PopulateRateLimitingKeyInProto(const std::string& rate_limiting_key,
                                    ClientDownloadRequest* request_proto) {
  request_proto->set_rate_limiting_key(rate_limiting_key);
}

}  // namespace

DownloadProtectionDelegateAndroid::DownloadProtectionDelegateAndroid()
    : download_request_url_(ConstructDownloadRequestUrl()) {}

DownloadProtectionDelegateAndroid::~DownloadProtectionDelegateAndroid() =
    default;

bool DownloadProtectionDelegateAndroid::ShouldCheckDownloadUrl(
    download::DownloadItem* item) const {
  return IsAndroidDownloadProtectionEnabledForDownloadProfile(item);
}

bool DownloadProtectionDelegateAndroid::MayCheckClientDownload(
    download::DownloadItem* item) const {
  bool is_enabled = IsAndroidDownloadProtectionEnabledForDownloadProfile(item);
  if (is_enabled && !IsDownloadRequestUrlValid(download_request_url_)) {
    DownloadProtectionMetricsData::SetOutcome(item, Outcome::kMisconfigured);
    return false;
  }
  if (!is_enabled) {
    return false;
  }

  MayCheckDownloadResult may_check_download_result =
      IsSupportedDownload(*item, item->GetFileNameToReportUser());
  return MayCheckItem(may_check_download_result, /*download_item=*/item);
}

bool DownloadProtectionDelegateAndroid::MayCheckFileSystemAccessWrite(
    content::FileSystemAccessWriteItem* item) const {
  Profile* profile = Profile::FromBrowserContext(item->browser_context);
  if (!IsAndroidDownloadProtectionEnabled(profile)) {
    return false;
  }
  if (!IsDownloadRequestUrlValid(download_request_url_)) {
    return false;
  }
  DownloadCheckResultReason ignored_reason = REASON_MAX;
  MayCheckDownloadResult may_check_download_result =
      CheckFileSystemAccessWriteRequest::IsSupportedDownload(
          item->target_file_path, &ignored_reason);
  return MayCheckItem(may_check_download_result);
}

MayCheckDownloadResult DownloadProtectionDelegateAndroid::IsSupportedDownload(
    download::DownloadItem& item,
    const base::FilePath& target_path) const {
  // On Android, the target path is likely a content-URI. Therefore, use the
  // display name instead. This assumes the DownloadItem's display name has
  // already been populated by InProgressDownloadManager.
  // TODO(chlily): The display name may not be populated properly at the point
  // when this is called.
  base::FilePath file_name = item.GetFileNameToReportUser();

  DownloadCheckResultReason reason = REASON_MAX;
  MayCheckDownloadResult may_check_download_result =
      CheckClientDownloadRequest::IsSupportedDownload(item, file_name, &reason);
  if (may_check_download_result != MayCheckDownloadResult::kMayCheckDownload) {
    DownloadProtectionMetricsData::SetOutcome(
        &item, DownloadProtectionMetricsData::ConvertDownloadCheckResultReason(
                   reason));
  }
  return may_check_download_result;
}

std::vector<PendingClientDownloadRequestModification>
DownloadProtectionDelegateAndroid::ProduceClientDownloadRequestModifications(
    const download::DownloadItem* item,
    Profile* profile) {
  std::vector<PendingClientDownloadRequestModification> modifications;

  // Populate referring_app_info.
  if (item) {
    modifications.emplace_back(
        base::BindOnce(&MaybePopulateReferringAppInfo, item));
  }

  // Populate rate_limiting_key.
  if (profile) {
    modifications.emplace_back(base::BindOnce(
        &DownloadProtectionDelegateAndroid::PopulateRateLimitingKey,
        weak_factory_.GetWeakPtr(), profile->UniqueId()));
  }

  return modifications;
}

void DownloadProtectionDelegateAndroid::FinalizeResourceRequest(
    network::ResourceRequest& resource_request) {
  resource_request.headers.SetHeader(net::HttpRequestHeaders::kContentType,
                                     kProtobufContentType);
  google_apis::AddAPIKeyToRequest(
      resource_request,
      google_apis::GetAPIKey(version_info::android::GetChannel()));
}

const GURL& DownloadProtectionDelegateAndroid::GetDownloadRequestUrl() const {
  return download_request_url_;
}

net::NetworkTrafficAnnotationTag DownloadProtectionDelegateAndroid::
    CompleteClientDownloadRequestTrafficAnnotation(
        const net::PartialNetworkTrafficAnnotationTag&
            partial_traffic_annotation) const {
  // TODO(crbug.com/397407934): Update the `data` and `user_data` fields after
  // additional Android-specific data is added to ClientDownloadRequest.
  return net::BranchedCompleteNetworkTrafficAnnotation(
      "client_download_request_android", "client_download_request_for_platform",
      partial_traffic_annotation, R"(
          semantics {
            description:
              "Chromium checks whether a given APK download is likely to be "
              "dangerous by sending this client download request to Google's "
              "Android Chrome protection server. The server will respond to "
              "this request by sending back a verdict, indicating if this "
              "download is safe or the danger type of this download (e.g. "
              "dangerous content, uncommon content, potentially harmful, etc)."
            trigger:
              "This request may be triggered when an eligible download is "
              "about to complete, for a random sample of eligible downloads "
              "at a sampling rate between 0% and 100% configured via "
              "fieldtrial. A download is eligible if the download URL is valid "
              "and its file extension matches '.apk'."
            data:
              "URL of the file to be downloaded, its referrer chain, digest "
              "and other features extracted from the downloaded file. Refer to "
              "ClientDownloadRequest message in https://cs.chromium.org/"
              "chromium/src/components/safe_browsing/csd.proto for all "
              "submitted features."
            user_data {
              type: SENSITIVE_URL
              type: WEB_CONTENT
            }
            last_reviewed: "2025-03-10"
          })");
}

float DownloadProtectionDelegateAndroid::GetAllowlistedDownloadSampleRate()
    const {
  return kAllowlistDownloadSampleRate;
}

float DownloadProtectionDelegateAndroid::GetUnsupportedFileSampleRate(
    const base::FilePath& filename) const {
  // "Light" pings for a sample of unsupported files is disabled on Android.
  return 0.0;
}

void DownloadProtectionDelegateAndroid::SetNextShouldSampleForTesting(
    bool should_sample) {
  should_sample_override_ = should_sample;
}

bool DownloadProtectionDelegateAndroid::ShouldSampleEligibleFile() const {
  // Use the value overridden for testing.
  if (should_sample_override_.has_value()) {
    bool should_sample = *should_sample_override_;
    should_sample_override_.reset();
    return should_sample;
  }

  int sample_percentage = kMaliciousApkDownloadCheckSamplePercentage.Get();
  // If sample_percentage param is misconfigured, don't apply sampling.
  if (sample_percentage < 0 || sample_percentage > 100) {
    sample_percentage = 100;
  }
  // This ensures that in telemetry-only mode, we sample at most 10% of
  // eligible downloads.
  if (kMaliciousApkDownloadCheckTelemetryOnly.Get()) {
    sample_percentage = std::min(sample_percentage, 10);
  }
  // Avoid the syscall if possible.
  if (sample_percentage >= 100) {
    CHECK_EQ(sample_percentage, 100);
    return true;
  }
  return base::RandDouble() * 100 < sample_percentage;
}

bool DownloadProtectionDelegateAndroid::MayCheckItem(
    MayCheckDownloadResult may_check_download_result,
    download::DownloadItem* item) const {
  switch (may_check_download_result) {
    case MayCheckDownloadResult::kMayNotCheckDownload:
      return false;

    case MayCheckDownloadResult::kMayCheckDownload: {
      // Apply random sampling only to eligible files (APK files).
      bool should_sample = ShouldSampleEligibleFile();
      if (item && !should_sample) {
        DownloadProtectionMetricsData::SetOutcome(item, Outcome::kNotSampled);
      }
      return should_sample;
    }

    case MayCheckDownloadResult::kMaySendSampledPingOnly:
      // "Light" sampled pings for unsupported filetypes are not supported on
      // Android. GetUnsupportedFileSampleRate() enforces that later, so return
      // true here to be consistent with the semantics of
      // MayCheckDownloadResult.
      return true;
  }
}

void DownloadProtectionDelegateAndroid::PopulateRateLimitingKey(
    const std::string& profile_id,
    CollectModificationCallback callback) {
  if (!rate_limiting_key_manager_) {
    base::OnceCallback<void(const std::string&)> on_got_safety_net_id =
        base::BindOnce(
            &DownloadProtectionDelegateAndroid::InitRateLimitingKeyManager,
            weak_factory_.GetWeakPtr());
    base::OnceClosure try_populate_again = base::BindOnce(
        &DownloadProtectionDelegateAndroid::PopulateRateLimitingKey,
        weak_factory_.GetWeakPtr(), profile_id, std::move(callback));
    // Kick off a lookup to get the safety_net_id and initialize the manager,
    // then try again.
    SafeBrowsingApiHandlerBridge::GetInstance().StartGetSafetyNetId(
        std::move(on_got_safety_net_id).Then(std::move(try_populate_again)));
    return;
  }

  CHECK(rate_limiting_key_manager_);
  std::move(callback).Run(base::BindOnce(
      &PopulateRateLimitingKeyInProto,
      rate_limiting_key_manager_->GetCurrentRateLimitingKey(profile_id)));
}

void DownloadProtectionDelegateAndroid::InitRateLimitingKeyManager(
    const std::string& safety_net_id) {
  if (!rate_limiting_key_manager_) {
    rate_limiting_key_manager_.emplace(safety_net_id);
  }
}

}  // namespace safe_browsing