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// 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/file_system_access_metadata.h"
#include "base/strings/string_util.h"
#include "chrome/browser/safe_browsing/download_protection/download_protection_util.h"
#include "components/download/public/common/download_danger_type.h"
#include "components/enterprise/connectors/core/reporting_utils.h"
#include "net/base/mime_util.h"
namespace safe_browsing {
FileSystemAccessMetadata::FileSystemAccessMetadata(
std::unique_ptr<content::FileSystemAccessWriteItem> item)
: item_(std::move(item)),
tab_url_(item_->web_contents ? item_->web_contents->GetLastCommittedURL()
: GURL()) {
CHECK(item_);
}
FileSystemAccessMetadata::~FileSystemAccessMetadata() = default;
content::BrowserContext* FileSystemAccessMetadata::GetBrowserContext() const {
return item_->browser_context;
}
safe_browsing::ReferrerChain FileSystemAccessMetadata::GetReferrerChain()
const {
std::unique_ptr<safe_browsing::ReferrerChainData> referrer_chain_data =
safe_browsing::IdentifyReferrerChain(
*item_, enterprise_connectors::kReferrerUserGestureLimit);
if (referrer_chain_data && referrer_chain_data->GetReferrerChain()) {
return *referrer_chain_data->GetReferrerChain();
}
return safe_browsing::ReferrerChain();
}
const base::FilePath& FileSystemAccessMetadata::GetFullPath() const {
return item_->full_path;
}
const base::FilePath& FileSystemAccessMetadata::GetTargetFilePath() const {
return item_->target_file_path;
}
const std::string& FileSystemAccessMetadata::GetHash() const {
return item_->sha256_hash;
}
int64_t FileSystemAccessMetadata::GetTotalBytes() const {
return item_->size;
}
std::string FileSystemAccessMetadata::GetMimeType() const {
if (!mime_type_computed_) {
// Get MIME type based on file extension.
std::string mime_type;
base::FilePath::StringType ext =
base::ToLowerASCII(item_->target_file_path.FinalExtension());
// Remove leading dot from extension.
if (!ext.empty() && ext[0] == FILE_PATH_LITERAL('.')) {
ext = ext.substr(1);
}
// Searches within chrome's built-in list of filetype/extension
// associations, as using `GetMimeTypeFromExtension` includes
// platform-defined mime type mappings that can potentially block.
// TODO(crbug.com/407598185): Add platform MIME types lookup for better
// protection.
if (net::GetWellKnownMimeTypeFromExtension(ext, &mime_type)) {
mime_type_ = mime_type;
} else {
// Default to octet-stream for unknown MIME type.
mime_type_ = "application/octet-stream";
}
mime_type_computed_ = true;
}
return mime_type_;
}
const GURL& FileSystemAccessMetadata::GetURL() const {
return item_->frame_url;
}
const GURL& FileSystemAccessMetadata::GetTabUrl() const {
return tab_url_;
}
bool FileSystemAccessMetadata::HasUserGesture() const {
return item_->has_user_gesture;
}
bool FileSystemAccessMetadata::IsObfuscated() const {
// No support for enterprise obfuscation for filesystem access API.
return false;
}
bool FileSystemAccessMetadata::IsTopLevelEncryptedArchive() const {
// No support for password-protected files for filesystem access API.
return false;
}
bool FileSystemAccessMetadata::IsForDownloadItem(
download::DownloadItem* download) const {
return false;
}
download::DownloadDangerType FileSystemAccessMetadata::GetDangerType() const {
// Used as the default pre-scan and fallback danger type since FSA doesn't
// have preliminary danger type checks.
return download::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS;
}
enterprise_connectors::EventResult
FileSystemAccessMetadata::GetPreScanEventResult(
download::DownloadDangerType danger_type) const {
// Currently for file system access deep scans, pre-scan danger type
// should always be DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS and event result
// ALLOWED.
if (danger_type != download::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS) {
DVLOG(1) << "Unexpected danger type for fsa scan: " << danger_type;
}
return enterprise_connectors::EventResult::ALLOWED;
}
std::unique_ptr<DownloadRequestMaker>
FileSystemAccessMetadata::CreateDownloadRequestFromMetadata(
scoped_refptr<BinaryFeatureExtractor> binary_feature_extractor) const {
return DownloadRequestMaker::CreateFromFileSystemAccess(
binary_feature_extractor, *item_);
}
std::unique_ptr<DeepScanningMetadata::DownloadScopedObservation>
FileSystemAccessMetadata::GetDownloadObservation(
download::DownloadItem::Observer* observer) {
return nullptr;
}
void FileSystemAccessMetadata::SetCallback(CheckDownloadCallback callback) {
callback_ = std::move(callback);
}
void FileSystemAccessMetadata::ProcessScanResult(
DownloadCheckResultReason reason,
DownloadCheckResult deep_scan_result) {
if (deep_scan_result == DownloadCheckResult::ASYNC_SCANNING ||
deep_scan_result == DownloadCheckResult::ASYNC_LOCAL_PASSWORD_SCANNING) {
return;
}
// Callback should only be run once, ignore any subsequent scan results.
if (!callback_.is_null()) {
std::move(callback_).Run(MaybeOverrideScanResult(reason, deep_scan_result));
}
}
base::WeakPtr<FileSystemAccessMetadata> FileSystemAccessMetadata::GetWeakPtr() {
return weakptr_factory_.GetWeakPtr();
}
} // namespace safe_browsing
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