user_agent_utils.cc | Explore in Territory

// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/embedder_support/user_agent_utils.h"

#include <string>
#include <vector>

#include "base/command_line.h"
#include "base/debug/stack_trace.h"
#include "base/feature_list.h"
#include "base/no_destructor.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "base/system/sys_info.h"
#include "base/version.h"
#include "build/branding_buildflags.h"
#include "build/build_config.h"
#include "components/embedder_support/pref_names.h"
#include "components/embedder_support/switches.h"
#include "components/policy/core/common/policy_pref_names.h"
#include "components/prefs/pref_service.h"
#include "components/version_info/version_info.h"
#include "content/public/browser/web_contents.h"
#include "content/public/common/content_features.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/user_agent.h"
#include "net/http/http_util.h"
#include "third_party/blink/public/common/features.h"
#include "third_party/blink/public/common/user_agent/user_agent_metadata.h"

#if BUILDFLAG(IS_WIN)
#include <windows.h>

#include "base/win/registry.h"
#include "base/win/windows_version.h"
#endif  // BUILDFLAG(IS_WIN)

namespace embedder_support {

namespace {

#if BUILDFLAG(IS_WIN)

// The registry key where the UniversalApiContract version value can be read
// from.
constexpr wchar_t kWindowsRuntimeWellKnownContractsRegKeyName[] =
    L"SOFTWARE\\Microsoft\\WindowsRuntime\\WellKnownContracts";

// Name of the UniversalApiContract registry.
constexpr wchar_t kUniversalApiContractName[] =
    L"Windows.Foundation.UniversalApiContract";

// There's a chance that access to the registry key that contains the
// UniversalApiContract Version will not be available in the future. After we
// confirm that our Windows version is RS5 or greater, it is best to have the
// default return value be the highest known version number at the time this
// code is submitted. If the UniversalApiContract registry key is no longer
// available, there will either be a new API introduced, or we will need
// to rely on querying the IsApiContractPresentByMajor function used by
// user_agent_utils_unittest.cc.
const int kHighestKnownUniversalApiContractVersion = 15;

int GetPreRS5UniversalApiContractVersion() {
  // This calls Kernel32Version() to get the real non-spoofable version (as
  // opposed to base::win::GetVersion() which as of writing this seems to return
  // different results depending on compatibility mode, and is spoofable).
  // See crbug.com/1404448.
  const base::win::Version version = base::win::OSInfo::Kernel32Version();
  if (version == base::win::Version::WIN10) {
    return 1;
  }
  if (version == base::win::Version::WIN10_TH2) {
    return 2;
  }
  if (version == base::win::Version::WIN10_RS1) {
    return 3;
  }
  if (version == base::win::Version::WIN10_RS2) {
    return 4;
  }
  if (version == base::win::Version::WIN10_RS3) {
    return 5;
  }
  if (version == base::win::Version::WIN10_RS4) {
    return 6;
  }
  // The list above should account for all Windows versions prior to
  // RS5.
  NOTREACHED_IN_MIGRATION();
  return 0;
}

// Returns the UniversalApiContract version number, which is available for
// Windows versions greater than RS5. Otherwise, returns 0.
const std::string& GetUniversalApiContractVersion() {
  // Do not use this for runtime environment detection logic. This method should
  // only be used to help populate the Sec-CH-UA-Platform client hint. If
  // authoring code that depends on a minimum API contract version being
  // available, you should instead leverage the OS's IsApiContractPresentByMajor
  // method.
  static const base::NoDestructor<std::string> universal_api_contract_version(
      [] {
        int major_version = 0;
        int minor_version = 0;
        if (base::win::OSInfo::Kernel32Version() <=
            base::win::Version::WIN10_RS4) {
          major_version = GetPreRS5UniversalApiContractVersion();
        } else {
          base::win::RegKey version_key(
              HKEY_LOCAL_MACHINE, kWindowsRuntimeWellKnownContractsRegKeyName,
              KEY_QUERY_VALUE | KEY_WOW64_64KEY);
          if (version_key.Valid()) {
            DWORD universal_api_contract_version = 0;
            LONG result = version_key.ReadValueDW(
                kUniversalApiContractName, &universal_api_contract_version);
            if (result == ERROR_SUCCESS) {
              major_version = HIWORD(universal_api_contract_version);
              minor_version = LOWORD(universal_api_contract_version);
            } else {
              major_version = kHighestKnownUniversalApiContractVersion;
            }
          } else {
            major_version = kHighestKnownUniversalApiContractVersion;
          }
        }
        // The major version of the contract is stored in the HIWORD, while the
        // minor version is stored in the LOWORD.
        return base::StrCat({base::NumberToString(major_version), ".",
                             base::NumberToString(minor_version), ".0"});
      }());
  return *universal_api_contract_version;
}

const std::string& GetWindowsPlatformVersion() {
  return GetUniversalApiContractVersion();
}
#endif  // BUILDFLAG(IS_WIN)

// Returns true if the user agent reduction should be forced (or prevented).
// TODO(crbug.com/1330890): Remove this method along with policy.
bool ShouldReduceUserAgentMinorVersion(
    UserAgentReductionEnterprisePolicyState user_agent_reduction) { … }

// For desktop:
// Returns true if both kReduceUserAgentMinorVersionName and
// kReduceUserAgentPlatformOsCpu are enabled. It makes
// kReduceUserAgentPlatformOsCpu depend on kReduceUserAgentMinorVersionName.
//
// For android:
// Returns true if both kReduceUserAgentMinorVersionName and
// kReduceUserAgentAndroidVersionDeviceModel are enabled. It makes
// kReduceUserAgentAndroidVersionDeviceModel depend on
// kReduceUserAgentMinorVersionName.
//
// It helps us avoid introducing individual enterprise policy controls for
// sending unified platform for the user agent string.
bool ShouldSendUserAgentUnifiedPlatform(
    UserAgentReductionEnterprisePolicyState user_agent_reduction) { … }

const blink::UserAgentBrandList GetUserAgentBrandList(
    const std::string& major_version,
    bool enable_updated_grease_by_policy,
    const std::string& full_version,
    blink::UserAgentBrandVersionType output_version_type) { … }

// Return UserAgentBrandList with the major version populated in the brand
// `version` value.
// TODO(crbug.com/1291612): Consolidate *MajorVersionList() methods by using
// GetVersionNumber()
const blink::UserAgentBrandList GetUserAgentBrandMajorVersionList(
    bool enable_updated_grease_by_policy) { … }

// Return UserAgentBrandList with the full version populated in the brand
// `version` value.
// TODO(crbug.com/1291612): Consolidate *FullVersionList() methods by using
// GetVersionNumber()
blink::UserAgentBrandList GetUserAgentBrandFullVersionList(
    bool enable_updated_grease_by_policy) { … }

std::vector<std::string> GetFormFactorsClientHint(
    const blink::UserAgentMetadata& metadata,
    bool is_mobile) { … }

}  // namespace

std::string GetProductAndVersion(
    UserAgentReductionEnterprisePolicyState user_agent_reduction) { … }

// Internal function to handle return the full or "reduced" user agent string,
// depending on the UserAgentReduction enterprise policy.
std::string GetUserAgentInternal(
    UserAgentReductionEnterprisePolicyState user_agent_reduction) { … }

std::optional<std::string> GetUserAgentFromCommandLine() { … }

std::string GetUserAgent(
    UserAgentReductionEnterprisePolicyState user_agent_reduction) { … }

// Generate a pseudo-random permutation of the following brand/version pairs:
//   1. The base project (i.e. Chromium)
//   2. The browser brand, if available
//   3. A randomized string containing GREASE characters to ensure proper
//      header parsing, along with an arbitrarily low version to ensure proper
//      version checking.
blink::UserAgentBrandList GenerateBrandVersionList(
    int seed,
    std::optional<std::string> brand,
    const std::string& version,
    std::optional<std::string> maybe_greasey_brand,
    std::optional<std::string> maybe_greasey_version,
    bool enable_updated_grease_by_policy,
    blink::UserAgentBrandVersionType output_version_type) { … }

// Process greased overridden brand version which is either major version or
// full version, return the corresponding output version type.
blink::UserAgentBrandVersion GetProcessedGreasedBrandVersion(
    const std::string& greasey_brand,
    const std::string& greasey_version,
    blink::UserAgentBrandVersionType output_version_type) { … }

blink::UserAgentBrandVersion GetGreasedUserAgentBrandVersion(
    std::vector<int> permuted_order,
    int seed,
    std::optional<std::string> maybe_greasey_brand,
    std::optional<std::string> maybe_greasey_version,
    bool enable_updated_grease_by_policy,
    blink::UserAgentBrandVersionType output_version_type) { … }

std::string GetPlatformForUAMetadata() { … }

blink::UserAgentMetadata GetUserAgentMetadata(bool only_low_entropy_ch) { … }

blink::UserAgentMetadata GetUserAgentMetadata(const PrefService* pref_service,
                                              bool only_low_entropy_ch) { … }

#if BUILDFLAG(IS_ANDROID)
void SetDesktopUserAgentOverride(content::WebContents* web_contents,
                                 const blink::UserAgentMetadata& metadata,
                                 bool override_in_new_tabs) {
  const char kLinuxInfoStr[] = "X11; Linux x86_64";

  blink::UserAgentOverride spoofed_ua;
  spoofed_ua.ua_string_override = content::BuildUserAgentFromOSAndProduct(
      kLinuxInfoStr, GetProductAndVersion());
  spoofed_ua.ua_metadata_override = metadata;
  spoofed_ua.ua_metadata_override->platform = "Linux";
  spoofed_ua.ua_metadata_override->platform_version =
      std::string();  // match content::GetOSVersion(false) on Linux
  spoofed_ua.ua_metadata_override->model = std::string();
  spoofed_ua.ua_metadata_override->mobile = false;
  spoofed_ua.ua_metadata_override->form_factors =
      GetFormFactorsClientHint(metadata, /*is_mobile=*/false);
  // Match the above "CpuInfo" string, which is also the most common Linux
  // CPU architecture and bitness.`
  spoofed_ua.ua_metadata_override->architecture = "x86";
  spoofed_ua.ua_metadata_override->bitness = "64";
  spoofed_ua.ua_metadata_override->wow64 = false;

  web_contents->SetUserAgentOverride(spoofed_ua, override_in_new_tabs);
}
#endif  // BUILDFLAG(IS_ANDROID)

#if BUILDFLAG(IS_WIN)
int GetHighestKnownUniversalApiContractVersionForTesting() {
  return kHighestKnownUniversalApiContractVersion;
}
#endif  // BUILDFLAG(IS_WIN)

embedder_support::UserAgentReductionEnterprisePolicyState
GetUserAgentReductionFromPrefs(const PrefService* pref_service) { … }

}  // namespace embedder_support
chromium/components/embedder_support/user_agent_utils.cc
