utility_sandbox_delegate_win.cc

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/utility_sandbox_delegate.h"

#include "base/check.h"
#include "base/feature_list.h"
#include "base/files/file_path.h"
#include "base/strings/utf_string_conversions.h"
#include "components/services/screen_ai/buildflags/buildflags.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/common/content_client.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/sandboxed_process_launcher_delegate.h"
#include "content/utility/sandbox_delegate_data.mojom.h"
#include "printing/buildflags/buildflags.h"
#include "sandbox/policy/mojom/sandbox.mojom.h"
#include "sandbox/policy/win/sandbox_win.h"
#include "sandbox/win/src/app_container.h"
#include "sandbox/win/src/sandbox_policy.h"
#include "sandbox/win/src/sandbox_types.h"
#include "services/network/public/mojom/network_service.mojom.h"

namespace content {
namespace {
// Audio:
//  lockdown_level_(sandbox::USER_LOCKDOWN),
//  initial_level_(sandbox::USER_RESTRICTED_SAME_ACCESS),
//
//  job_level_(sandbox::JobLevel::kLockdown),
//
//  integrity_level_(sandbox::INTEGRITY_LEVEL_LOW),
//  delayed_integrity_level_(sandbox::INTEGRITY_LEVEL_UNTRUSTED),
bool AudioInitializeConfig(sandbox::TargetConfig* config) {
  // Audio process privilege requirements:
  //  - Lockdown level of USER_NON_ADMIN
  //  - Delayed integrity level of INTEGRITY_LEVEL_LOW
  //
  // For audio streams to create shared memory regions, lockdown level must be
  // at least USER_LIMITED and delayed integrity level INTEGRITY_LEVEL_LOW,
  // otherwise CreateFileMapping() will fail with error code
  // ERROR_ACCESS_DENIED (0x5).
  //
  // For audio input streams to use ISimpleAudioVolume interface, lockdown
  // level must be set to USER_NON_ADMIN, otherwise
  // WASAPIAudioInputStream::Open() will fail with error code E_ACCESSDENIED
  // (0x80070005) when trying to get a reference to ISimpleAudioVolume
  // interface. See
  // https://cs.chromium.org/chromium/src/media/audio/win/audio_low_latency_input_win.cc
  // Use USER_RESTRICTED_NON_ADMIN over USER_NON_ADMIN to prevent failures when
  // AppLocker and similar application whitelisting solutions are in place.
  DCHECK(!config->IsConfigured());

  // Custom default policy allowing audio drivers to read device properties
  // (https://crbug.com/883326).
  auto result = config->SetIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  config->SetLockdownDefaultDacl();
  config->SetDelayedIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
  result = config->SetTokenLevel(sandbox::USER_RESTRICTED_SAME_ACCESS,
                                 sandbox::USER_RESTRICTED_NON_ADMIN);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  // The Audio Service process uses a base::SyncSocket for transmitting audio
  // data.
  result = config->AddRule(sandbox::SubSystem::kNamedPipes,
                           sandbox::Semantics::kNamedPipesAllowAny,
                           L"\\\\.\\pipe\\chrome.sync.*");
  if (result != sandbox::SBOX_ALL_OK) {
    return false;
  }

  config->SetDesktop(sandbox::Desktop::kAlternateWinstation);

  return true;
}

// Sets the sandbox policy for the network service process.
bool NetworkInitializeConfig(sandbox::TargetConfig* config) {
  DCHECK(!config->IsConfigured());
  // LPAC sandbox is enabled, so do not use a restricted token.
  auto result = config->SetTokenLevel(sandbox::USER_UNPROTECTED,
                                      sandbox::USER_UNPROTECTED);
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  // Network Sandbox in LPAC sandbox needs access to its data files. These
  // files are marked on disk with an ACE that permits this access.
  auto lpac_capability =
      GetContentClient()->browser()->GetLPACCapabilityNameForNetworkService();
  if (lpac_capability.empty())
    return false;
  auto app_container = config->GetAppContainer();
  if (!app_container)
    return false;
  app_container->AddCapability(lpac_capability.c_str());

  // Add capability SID for 'network_service' for loopback access for testing.
  // Run 'checkNetIsolation.exe loopbackExempt -a -n=network_service' while
  // elevated to allow network service loopback access.
  // TODO(wfh): Remove this once the socket broker has landed. See
  // https://crbug.com/841001.
  app_container->AddCapabilitySddl(
      L"S-1-15-3-893703388-718787801-2109771152-172907555-2119217564-716812919-"
      L"652991501");

  // All other app container policies are set in
  // SandboxWin::StartSandboxedProcess.
  return true;
}

#if BUILDFLAG(ENABLE_OOP_PRINTING)
// Sets the sandbox policy for the print backend service process.
bool PrintBackendInitializeConfig(sandbox::TargetConfig* config) {
  DCHECK(!config->IsConfigured());
  // Print Backend policy lockdown level must be at least USER_LIMITED and
  // delayed integrity level INTEGRITY_LEVEL_LOW, otherwise ::OpenPrinter()
  // will fail with error code ERROR_ACCESS_DENIED (0x5).
  auto result = config->SetTokenLevel(sandbox::USER_RESTRICTED_SAME_ACCESS,
                                      sandbox::USER_LIMITED);
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  config->SetDelayedIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
  return true;
}
#endif

std::string UtilityAppContainerId(base::CommandLine& cmd_line) {
  return base::WideToUTF8(cmd_line.GetProgram().value());
}

bool IconReaderInitializeConfig(sandbox::TargetConfig* config) {
  DCHECK(!config->IsConfigured());

  auto result = config->SetTokenLevel(sandbox::USER_RESTRICTED_SAME_ACCESS,
                                      sandbox::USER_LOCKDOWN);
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  config->SetDelayedIntegrityLevel(sandbox::INTEGRITY_LEVEL_UNTRUSTED);
  result = config->SetIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  config->SetLockdownDefaultDacl();
  config->SetDesktop(sandbox::Desktop::kAlternateWinstation);

  sandbox::MitigationFlags flags = config->GetDelayedProcessMitigations();
  flags |= sandbox::MITIGATION_DYNAMIC_CODE_DISABLE;
  result = config->SetDelayedProcessMitigations(flags);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  // Allow file read. These should match IconLoader::GroupForFilepath().
  result =
      config->AddRule(sandbox::SubSystem::kFiles,
                      sandbox::Semantics::kFilesAllowReadonly, L"\\??\\*.exe");
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  result =
      config->AddRule(sandbox::SubSystem::kFiles,
                      sandbox::Semantics::kFilesAllowReadonly, L"\\??\\*.dll");
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  result =
      config->AddRule(sandbox::SubSystem::kFiles,
                      sandbox::Semantics::kFilesAllowReadonly, L"\\??\\*.ico");
  if (result != sandbox::SBOX_ALL_OK)
    return false;
  return true;
}

bool XrCompositingInitializeConfig(sandbox::TargetConfig* config,
                                   base::CommandLine& cmd_line,
                                   sandbox::mojom::Sandbox sandbox_type) {
  DCHECK(!config->IsConfigured());
  // TODO(https://crbug.com/881919): Try to harden the XR Compositor
  // sandbox to use mitigations and restrict the token.

  // Unprotected token/job.
  auto result = config->SetTokenLevel(sandbox::USER_UNPROTECTED,
                                      sandbox::USER_UNPROTECTED);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  result = sandbox::policy::SandboxWin::SetJobLevel(
      sandbox_type, sandbox::JobLevel::kUnprotected, 0, config);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  // There were issues with some mitigations, causing an inability
  // to load OpenVR and Oculus APIs.
  result = config->SetProcessMitigations(0);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  result = config->SetDelayedProcessMitigations(0);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  std::string appcontainer_id = UtilityAppContainerId(cmd_line);
  result = sandbox::policy::SandboxWin::AddAppContainerProfileToConfig(
      cmd_line, sandbox_type, appcontainer_id, config);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  return true;
}

#if BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)
bool ScreenAIInitializeConfig(sandbox::TargetConfig* config,
                              sandbox::mojom::Sandbox sandbox_type) {
  DCHECK(!config->IsConfigured());

  auto result = config->SetTokenLevel(sandbox::USER_RESTRICTED_SAME_ACCESS,
                                      sandbox::USER_LOCKDOWN);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  result = sandbox::policy::SandboxWin::SetJobLevel(
      sandbox_type, sandbox::JobLevel::kLimitedUser, 0, config);
  if (result != sandbox::SBOX_ALL_OK)
    return false;

  return true;
}
#endif  // BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)

// If preload-libraries or pinuser32 is required, adds delegate blob for
// utility_main() to access before lockdown is initialized.
void AddDelegateData(sandbox::TargetPolicy* policy,
                     bool pin_user32,
                     std::vector<base::FilePath>& preload_libraries) {
  if (!pin_user32 && preload_libraries.empty()) {
    return;
  }
  auto sandbox_config = content::mojom::sandbox::UtilityConfig::New();
  if (pin_user32) {
    sandbox_config->pin_user32 = true;
  }
  if (!preload_libraries.empty()) {
    for (const auto& library_path : preload_libraries) {
      sandbox_config->preload_libraries.push_back(library_path);
    }
  }
  std::vector<uint8_t> blob =
      content::mojom::sandbox::UtilityConfig::Serialize(&sandbox_config);
  policy->AddDelegateData(blob);
}

}  // namespace

std::string UtilitySandboxedProcessLauncherDelegate::GetSandboxTag() {
  return sandbox::policy::SandboxWin::GetSandboxTagForDelegate(
      "utility", GetSandboxType());
}

bool UtilitySandboxedProcessLauncherDelegate::GetAppContainerId(
    std::string* appcontainer_id) {
  switch (sandbox_type_) {
    case sandbox::mojom::Sandbox::kMediaFoundationCdm:
    case sandbox::mojom::Sandbox::kNetwork:
    case sandbox::mojom::Sandbox::kWindowsSystemProxyResolver:
    case sandbox::mojom::Sandbox::kXrCompositing:
      *appcontainer_id = UtilityAppContainerId(cmd_line_);
      return true;
    default:
      return false;
  }
}

bool UtilitySandboxedProcessLauncherDelegate::DisableDefaultPolicy() {
  switch (sandbox_type_) {
    case sandbox::mojom::Sandbox::kAudio:
      // Default policy is disabled for audio process to allow audio drivers
      // to read device properties (https://crbug.com/883326).
      return true;
    case sandbox::mojom::Sandbox::kXrCompositing:
      return true;
    case sandbox::mojom::Sandbox::kMediaFoundationCdm:
      // Default policy is disabled for MF Cdm process to allow the application
      // of specific LPAC sandbox policies.
      return true;
    case sandbox::mojom::Sandbox::kNetwork:
      // An LPAC specific policy for network service is set elsewhere.
      return true;
    case sandbox::mojom::Sandbox::kWindowsSystemProxyResolver:
      // Default policy is disabled for Windows System Proxy Resolver process to
      // allow the application of specific LPAC sandbox policies.
      return true;
    default:
      return false;
  }
}

bool UtilitySandboxedProcessLauncherDelegate::ShouldLaunchElevated() {
  return sandbox_type_ ==
         sandbox::mojom::Sandbox::kNoSandboxAndElevatedPrivileges;
}

bool UtilitySandboxedProcessLauncherDelegate::InitializeConfig(
    sandbox::TargetConfig* config) {
  DCHECK(!config->IsConfigured());
  if (sandbox_type_ == sandbox::mojom::Sandbox::kAudio) {
    if (!AudioInitializeConfig(config)) {
      return false;
    }
  }
  if (sandbox_type_ == sandbox::mojom::Sandbox::kNetwork) {
    if (!NetworkInitializeConfig(config)) {
      return false;
    }
  }
  if (sandbox_type_ == sandbox::mojom::Sandbox::kIconReader) {
    if (!IconReaderInitializeConfig(config)) {
      return false;
    }
  }

  if (sandbox_type_ == sandbox::mojom::Sandbox::kXrCompositing) {
    if (!XrCompositingInitializeConfig(config, cmd_line_, sandbox_type_)) {
      return false;
    }
  }

#if BUILDFLAG(ENABLE_SCREEN_AI_SERVICE)
  if (sandbox_type_ == sandbox::mojom::Sandbox::kScreenAI) {
    if (!ScreenAIInitializeConfig(config, sandbox_type_)) {
      return false;
    }
  }
#endif

  if (sandbox_type_ == sandbox::mojom::Sandbox::kSpeechRecognition) {
    auto result = config->SetIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
    if (result != sandbox::SBOX_ALL_OK) {
      return false;
    }
    config->SetDelayedIntegrityLevel(sandbox::INTEGRITY_LEVEL_LOW);
    result = config->SetTokenLevel(sandbox::USER_RESTRICTED_SAME_ACCESS,
                                   sandbox::USER_LIMITED);
    if (result != sandbox::SBOX_ALL_OK) {
      return false;
    }
  }

  if (sandbox_type_ == sandbox::mojom::Sandbox::kMediaFoundationCdm ||
      sandbox_type_ == sandbox::mojom::Sandbox::kWindowsSystemProxyResolver) {
    auto result = config->SetTokenLevel(sandbox::USER_UNPROTECTED,
                                        sandbox::USER_UNPROTECTED);
    if (result != sandbox::SBOX_ALL_OK) {
      return false;
    }
  }

  if (sandbox_type_ == sandbox::mojom::Sandbox::kService ||
      sandbox_type_ == sandbox::mojom::Sandbox::kServiceWithJit) {
    auto result = sandbox::policy::SandboxWin::AddWin32kLockdownPolicy(config);
    if (result != sandbox::SBOX_ALL_OK) {
      return false;
    }
  }

  if (sandbox_type_ == sandbox::mojom::Sandbox::kService) {
    auto delayed_flags = config->GetDelayedProcessMitigations();
    delayed_flags |= sandbox::MITIGATION_DYNAMIC_CODE_DISABLE;
    auto result = config->SetDelayedProcessMitigations(delayed_flags);
    if (result != sandbox::SBOX_ALL_OK) {
      return false;
    }
  }
#if BUILDFLAG(ENABLE_OOP_PRINTING)
  if (sandbox_type_ == sandbox::mojom::Sandbox::kPrintBackend) {
    if (!PrintBackendInitializeConfig(config)) {
      return false;
    }
  }
#endif

  return GetContentClient()->browser()->PreSpawnChild(
      config, sandbox_type_,
      ContentBrowserClient::ChildSpawnFlags::kChildSpawnFlagNone);
}

bool UtilitySandboxedProcessLauncherDelegate::ShouldUnsandboxedRunInJob() {
  auto utility_sub_type =
      cmd_line_.GetSwitchValueASCII(switches::kUtilitySubType);
  if (utility_sub_type == network::mojom::NetworkService::Name_)
    return true;
  return false;
}

bool UtilitySandboxedProcessLauncherDelegate::CetCompatible() {
  // TODO(1268074) can remove once v8 is cet-compatible.
  if (sandbox_type_ == sandbox::mojom::Sandbox::kServiceWithJit)
    return false;
  auto utility_sub_type =
      cmd_line_.GetSwitchValueASCII(switches::kUtilitySubType);
  return GetContentClient()->browser()->IsUtilityCetCompatible(
      utility_sub_type);
}

bool UtilitySandboxedProcessLauncherDelegate::AllowWindowsFontsDir() {
  // New utilities should use a font proxy rather than allowing direct access.
  if (sandbox_type_ == sandbox::mojom::Sandbox::kPrintCompositor) {
    return true;
  }
  return false;
}

bool UtilitySandboxedProcessLauncherDelegate::PreSpawnTarget(
    sandbox::TargetPolicy* policy) {
  AddDelegateData(policy, pin_user32_, preload_libraries_);
  return SandboxedProcessLauncherDelegate::PreSpawnTarget(policy);
}
}  // namespace content