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// Copyright 2014 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/common/safe_browsing/binary_feature_extractor.h"
#include <windows.h>
#include <softpub.h>
#include <stddef.h>
#include <stdint.h>
#include "base/containers/span.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/metrics/histogram_functions.h"
#include "base/threading/scoped_thread_priority.h"
#include "base/win/pe_image_reader.h"
#include "base/win/wintrust_shim.h"
#include "components/safe_browsing/core/common/proto/csd.pb.h"
namespace safe_browsing {
namespace {
// Conservatively set at 1 MB.
constexpr size_t kMaxDebugDataBytes = 1 * 1024 * 1024;
// An EnumCertificatesCallback that collects each SignedData blob.
bool OnCertificateEntry(uint16_t revision,
uint16_t certificate_type,
base::span<const uint8_t> certificate_data,
void* context) {
google::protobuf::RepeatedPtrField<std::string>* signed_data =
reinterpret_cast<google::protobuf::RepeatedPtrField<std::string>*>(
context);
if (revision == WIN_CERT_REVISION_2_0 &&
certificate_type == WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
signed_data->Add()->assign(certificate_data.begin(),
certificate_data.end());
}
return true;
}
} // namespace
void BinaryFeatureExtractor::CheckSignature(
const base::FilePath& file_path,
ClientDownloadRequest_SignatureInfo* signature_info) {
// Mitigate the issues caused by loading DLLs on a background thread
// (http://crbug/973868).
SCOPED_MAY_LOAD_LIBRARY_AT_BACKGROUND_PRIORITY();
DVLOG(2) << "Checking signature for " << file_path.value();
base::File file(file_path, base::File::FLAG_OPEN | base::File::FLAG_READ |
base::File::FLAG_WIN_SHARE_DELETE);
WINTRUST_FILE_INFO file_info = {0};
file_info.cbStruct = sizeof(file_info);
file_info.pcwszFilePath = file_path.value().c_str();
file_info.hFile = file.GetPlatformFile();
file_info.pgKnownSubject = NULL;
WINTRUST_DATA wintrust_data = {0};
wintrust_data.cbStruct = sizeof(wintrust_data);
wintrust_data.pPolicyCallbackData = NULL;
wintrust_data.pSIPClientData = NULL;
wintrust_data.dwUIChoice = WTD_UI_NONE;
wintrust_data.fdwRevocationChecks = WTD_REVOKE_NONE;
wintrust_data.dwUnionChoice = WTD_CHOICE_FILE;
wintrust_data.pFile = &file_info;
wintrust_data.dwStateAction = WTD_STATEACTION_VERIFY;
wintrust_data.hWVTStateData = NULL;
wintrust_data.pwszURLReference = NULL;
// Disallow revocation checks over the network.
wintrust_data.dwProvFlags = WTD_CACHE_ONLY_URL_RETRIEVAL;
wintrust_data.dwUIContext = WTD_UICONTEXT_EXECUTE;
// The WINTRUST_ACTION_GENERIC_VERIFY_V2 policy verifies that the certificate
// chains up to a trusted root CA, and that it has appropriate permission to
// sign code.
GUID policy_guid = WINTRUST_ACTION_GENERIC_VERIFY_V2;
LONG result = WinVerifyTrust(static_cast<HWND>(INVALID_HANDLE_VALUE),
&policy_guid,
&wintrust_data);
CRYPT_PROVIDER_DATA* prov_data = WTHelperProvDataFromStateData(
wintrust_data.hWVTStateData);
if (prov_data) {
if (prov_data->csSigners > 0) {
signature_info->set_trusted(result == ERROR_SUCCESS);
}
// SAFETY: CRYPT_PROVIDER_DATA is defined by Windows and guarantees
// pasSigners has csSsigners elements.
for (CRYPT_PROVIDER_SGNR pas_signer : UNSAFE_BUFFERS(
base::span(prov_data->pasSigners, prov_data->csSigners))) {
const CERT_CHAIN_CONTEXT* cert_chain_context = pas_signer.pChainContext;
if (!cert_chain_context)
break;
// SAFETY: CERT_CHAIN_CONTEXT is defined by Windows and guarantees
// rgpChain has cChain elements.
for (CERT_SIMPLE_CHAIN* simple_chain : UNSAFE_BUFFERS(base::span(
cert_chain_context->rgpChain, cert_chain_context->cChain))) {
ClientDownloadRequest_CertificateChain* chain =
signature_info->add_certificate_chain();
if (!simple_chain)
break;
// SAFETY: CERT_SIMPLE_CHAIN is defined by Windows and
// guarantees rgpElement has cElement elements.
for (CERT_CHAIN_ELEMENT* element : UNSAFE_BUFFERS(base::span(
simple_chain->rgpElement, simple_chain->cElement))) {
chain->add_element()->set_certificate(
element->pCertContext->pbCertEncoded,
element->pCertContext->cbCertEncoded);
}
}
}
// Free the provider data.
wintrust_data.dwStateAction = WTD_STATEACTION_CLOSE;
WinVerifyTrust(static_cast<HWND>(INVALID_HANDLE_VALUE),
&policy_guid, &wintrust_data);
}
}
bool BinaryFeatureExtractor::ExtractImageFeaturesFromData(
base::span<const uint8_t> data,
ExtractHeadersOption options,
ClientDownloadRequest_ImageHeaders* image_headers,
google::protobuf::RepeatedPtrField<std::string>* signed_data) {
base::win::PeImageReader pe_image;
if (!pe_image.Initialize(data)) {
return false;
}
// Copy the headers.
ClientDownloadRequest_PEImageHeaders* pe_headers =
image_headers->mutable_pe_headers();
pe_headers->set_dos_header(pe_image.GetDosHeader(), sizeof(IMAGE_DOS_HEADER));
pe_headers->set_file_header(pe_image.GetCoffFileHeader(),
sizeof(IMAGE_FILE_HEADER));
base::span<const uint8_t> optional_header_data =
pe_image.GetOptionalHeaderData();
if (pe_image.GetWordSize() == base::win::PeImageReader::WORD_SIZE_32) {
pe_headers->set_optional_headers32(optional_header_data.data(),
optional_header_data.size());
} else {
pe_headers->set_optional_headers64(optional_header_data.data(),
optional_header_data.size());
}
const size_t number_of_sections = pe_image.GetNumberOfSections();
for (size_t i = 0; i != number_of_sections; ++i) {
pe_headers->add_section_header(pe_image.GetSectionHeaderAt(i),
sizeof(IMAGE_SECTION_HEADER));
}
if (!(options & BinaryFeatureExtractor::kOmitExports)) {
base::span<const uint8_t> export_section = pe_image.GetExportSection();
if (!export_section.empty()) {
pe_headers->set_export_section_data(export_section.data(),
export_section.size());
}
}
size_t number_of_debug_entries = pe_image.GetNumberOfDebugEntries();
for (size_t i = 0; i != number_of_debug_entries; ++i) {
base::span<const uint8_t> raw_data;
const IMAGE_DEBUG_DIRECTORY* directory_entry =
pe_image.GetDebugEntry(i, raw_data);
if (directory_entry) {
ClientDownloadRequest_PEImageHeaders_DebugData* debug_data =
pe_headers->add_debug_data();
debug_data->set_directory_entry(directory_entry,
sizeof(IMAGE_DEBUG_DIRECTORY));
if (!raw_data.empty()) {
size_t raw_data_size = std::min(raw_data.size(), kMaxDebugDataBytes);
debug_data->set_raw_data(raw_data.data(), raw_data_size);
}
}
}
if (signed_data)
pe_image.EnumCertificates(&OnCertificateEntry, signed_data);
return true;
}
} // namespace safe_browsing
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