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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// This file contains the archive file analysis implementation for download
// protection, which runs in a sandboxed utility process.
#include "chrome/common/safe_browsing/archive_analyzer_results.h"
#include "base/files/file.h"
#include "base/i18n/streaming_utf8_validator.h"
#include "base/logging.h"
#include "base/memory/scoped_refptr.h"
#include "base/metrics/histogram_functions.h"
#include "build/build_config.h"
#include "chrome/common/safe_browsing/binary_feature_extractor.h"
#include "chrome/common/safe_browsing/download_type_util.h"
#include "components/safe_browsing/content/common/file_type_policies.h"
#include "crypto/secure_hash.h"
#include "crypto/sha2.h"
#include "url/gurl.h"
#if BUILDFLAG(IS_MAC)
#include <mach-o/fat.h>
#include <mach-o/loader.h>
#include "base/containers/span.h"
#include "chrome/common/safe_browsing/disk_image_type_sniffer_mac.h"
#include "chrome/common/safe_browsing/mach_o_image_reader_mac.h"
#endif // BUILDFLAG(IS_MAC)
namespace safe_browsing {
namespace {
void AnalyzeContainedBinary(
const scoped_refptr<BinaryFeatureExtractor>& binary_feature_extractor,
base::File* temp_file,
ClientDownloadRequest::ArchivedBinary* archived_binary) {
if (!binary_feature_extractor->ExtractImageFeaturesFromFile(
temp_file->Duplicate(), BinaryFeatureExtractor::kDefaultOptions,
archived_binary->mutable_image_headers(),
archived_binary->mutable_signature()->mutable_signed_data())) {
archived_binary->clear_image_headers();
archived_binary->clear_signature();
} else if (!archived_binary->signature().signed_data_size()) {
// No SignedData blobs were extracted, so clear the
// signature field.
archived_binary->clear_signature();
}
}
} // namespace
ArchiveAnalyzerResults::ArchiveAnalyzerResults() = default;
ArchiveAnalyzerResults::ArchiveAnalyzerResults(
const ArchiveAnalyzerResults& other) = default;
ArchiveAnalyzerResults::~ArchiveAnalyzerResults() = default;
void UpdateArchiveAnalyzerResultsWithFile(base::FilePath path,
base::File* file,
int file_length,
bool is_encrypted,
bool is_directory,
bool contents_valid,
bool is_top_level,
ArchiveAnalyzerResults* results) {
results->encryption_info.is_encrypted |= is_encrypted;
if (is_top_level) {
results->encryption_info.is_top_level_encrypted |= is_encrypted;
}
scoped_refptr<BinaryFeatureExtractor> binary_feature_extractor(
new BinaryFeatureExtractor());
bool current_entry_is_executable;
#if BUILDFLAG(IS_MAC)
uint32_t magic;
file->Read(0, base::byte_span_from_ref(magic));
uint8_t dmg_header[DiskImageTypeSnifferMac::kAppleDiskImageTrailerSize];
file->Read(0, dmg_header);
bool is_checked =
FileTypePolicies::GetInstance()->IsCheckedBinaryFile(path) &&
!is_directory;
current_entry_is_executable =
is_checked || MachOImageReader::IsMachOMagicValue(magic) ||
DiskImageTypeSnifferMac::IsAppleDiskImageTrailer(dmg_header);
// We can skip checking the trailer if we already know the file is executable.
if (!current_entry_is_executable) {
uint8_t trailer[DiskImageTypeSnifferMac::kAppleDiskImageTrailerSize];
file->Seek(base::File::Whence::FROM_END,
DiskImageTypeSnifferMac::kAppleDiskImageTrailerSize);
file->ReadAtCurrentPos(trailer);
current_entry_is_executable =
DiskImageTypeSnifferMac::IsAppleDiskImageTrailer(trailer);
}
#else
current_entry_is_executable =
FileTypePolicies::GetInstance()->IsCheckedBinaryFile(path) &&
!is_directory;
#endif // BUILDFLAG(IS_MAC)
if (FileTypePolicies::GetInstance()->IsArchiveFile(path)) {
DVLOG(2) << "Downloaded a zipped archive: " << path.value();
results->has_archive = true;
results->archived_archive_filenames.push_back(path.BaseName());
ClientDownloadRequest::ArchivedBinary* archived_archive =
results->archived_binary.Add();
archived_archive->set_download_type(ClientDownloadRequest::ARCHIVE);
archived_archive->set_is_encrypted(is_encrypted);
archived_archive->set_is_archive(true);
SetNameForContainedFile(path, archived_archive);
if (contents_valid) {
SetLengthAndDigestForContainedFile(file, file_length, archived_archive);
}
} else {
#if BUILDFLAG(IS_MAC)
// This check prevents running analysis on .app files since they are
// really just directories and will cause binary feature extraction
// to fail.
if (path.Extension().compare(".app") == 0) {
DVLOG(2) << "Downloaded a zipped .app directory: " << path.value();
} else {
#endif // BUILDFLAG(IS_MAC)
DVLOG(2) << "Downloaded a zipped executable: " << path.value();
results->has_executable |= current_entry_is_executable;
ClientDownloadRequest::ArchivedBinary* archived_binary =
results->archived_binary.Add();
archived_binary->set_is_encrypted(is_encrypted);
archived_binary->set_download_type(
download_type_util::GetDownloadType(path));
archived_binary->set_is_executable(current_entry_is_executable);
SetNameForContainedFile(path, archived_binary);
if (contents_valid) {
SetLengthAndDigestForContainedFile(file, file_length, archived_binary);
}
if (current_entry_is_executable) {
AnalyzeContainedBinary(binary_feature_extractor, file, archived_binary);
}
#if BUILDFLAG(IS_MAC)
}
#endif // BUILDFLAG(IS_MAC)
}
}
safe_browsing::DownloadFileType_InspectionType GetFileType(
base::FilePath path) {
return FileTypePolicies::GetInstance()
->PolicyForFile(path, GURL{}, nullptr)
.inspection_type();
}
void SetNameForContainedFile(
const base::FilePath& path,
ClientDownloadRequest::ArchivedBinary* archived_binary) {
std::string file_path(path.AsUTF8Unsafe());
if (base::StreamingUtf8Validator::Validate(file_path)) {
archived_binary->set_file_path(file_path);
}
}
void SetLengthAndDigestForContainedFile(
base::File* temp_file,
int file_length,
ClientDownloadRequest::ArchivedBinary* archived_binary) {
archived_binary->set_length(file_length);
std::unique_ptr<crypto::SecureHash> hasher =
crypto::SecureHash::Create(crypto::SecureHash::SHA256);
const size_t kReadBufferSize = 4096;
uint8_t block[kReadBufferSize];
size_t bytes_read_previously = 0;
temp_file->Seek(base::File::Whence::FROM_BEGIN, 0);
while (true) {
std::optional<size_t> bytes_read_now =
temp_file->ReadAtCurrentPos(base::span(block));
if (!bytes_read_now) {
break;
}
if (*bytes_read_now > file_length - bytes_read_previously) {
bytes_read_now = file_length - bytes_read_previously;
}
if (*bytes_read_now <= 0) {
break;
}
hasher->Update(base::span(block).first(*bytes_read_now));
bytes_read_previously += *bytes_read_now;
}
uint8_t digest[crypto::kSHA256Length];
hasher->Finish(digest, std::size(digest));
archived_binary->mutable_digests()->set_sha256(digest, std::size(digest));
}
} // namespace safe_browsing
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