api/file_handlers/app_file_handler_util.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "extensions/browser/api/file_handlers/app_file_handler_util.h"

#include <set>
#include <vector>

#include "base/bind.h"
#include "base/files/file.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/memory/scoped_refptr.h"
#include "base/task/post_task.h"
#include "base/task/task_traits.h"
#include "base/task/thread_pool.h"
#include "build/build_config.h"
#include "build/chromeos_buildflags.h"
#include "components/services/app_service/public/cpp/file_handler.h"
#include "components/services/app_service/public/cpp/file_handler_info.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/child_process_security_policy.h"
#include "extensions/browser/api/extensions_api_client.h"
#include "extensions/browser/entry_info.h"
#include "extensions/browser/extension_prefs.h"
#include "extensions/browser/granted_file_entry.h"
#include "extensions/common/permissions/permissions_data.h"
#include "net/base/mime_util.h"
#include "storage/browser/file_system/isolated_context.h"
#include "storage/common/file_system/file_system_mount_option.h"
#include "storage/common/file_system/file_system_types.h"

#if BUILDFLAG(IS_CHROMEOS_ASH)
#include "extensions/browser/api/file_handlers/non_native_file_system_delegate.h"
#endif

namespace extensions {

namespace app_file_handler_util {

const char kInvalidParameters[] = "Invalid parameters";
const char kSecurityError[] = "Security error";

namespace {

bool FileHandlerCanHandleFileWithExtension(const apps::FileHandlerInfo& handler,
                                           const base::FilePath& path) {
  for (auto extension = handler.extensions.cbegin();
       extension != handler.extensions.cend(); ++extension) {
    if (*extension == "*")
      return true;

    // Accept files whose extension or combined extension (e.g. ".tar.gz")
    // match the supported extensions of file handler.
    base::FilePath::StringType handler_extention(
        base::FilePath::kExtensionSeparator +
        base::FilePath::FromUTF8Unsafe(*extension).value());
    if (base::FilePath::CompareEqualIgnoreCase(handler_extention,
                                               path.Extension()) ||
        base::FilePath::CompareEqualIgnoreCase(handler_extention,
                                               path.FinalExtension())) {
      return true;
    }

    // Also accept files with no extension for handlers that support an
    // empty extension, i.e. both "foo" and "foo." match.
    if (extension->empty() &&
        path.MatchesExtension(base::FilePath::StringType())) {
      return true;
    }
  }
  return false;
}

bool FileHandlerCanHandleFileWithMimeType(const apps::FileHandlerInfo& handler,
                                          const std::string& mime_type) {
  for (auto type = handler.types.cbegin(); type != handler.types.cend();
       ++type) {
    if (net::MatchesMimeType(*type, mime_type))
      return true;
  }
  return false;
}

bool WebAppFileHandlerCanHandleFileWithExtension(
    const apps::FileHandler& file_handler,
    const base::FilePath& path) {
  // Build a list of file extensions supported by the handler.
  //
  // TODO(crbug.com/938103): Duplicates functionality from
  // FileHandlerManager::GetFileExtensionsFromFileHandlers.
  std::set<std::string> file_extensions;
  for (const auto& accept_entry : file_handler.accept)
    file_extensions.insert(accept_entry.file_extensions.begin(),
                           accept_entry.file_extensions.end());

  for (const auto& file_extension : file_extensions) {
    if (file_extension == "*")
      return true;

    // Accept files whose extensions or combined extensions (e.g. ".tar.gz")
    // match the supported extensions of the file handler.
    base::FilePath::StringType file_extension_stringtype(
        base::FilePath::FromUTF8Unsafe(file_extension).value());
    if (base::FilePath::CompareEqualIgnoreCase(file_extension_stringtype,
                                               path.Extension()) ||
        base::FilePath::CompareEqualIgnoreCase(file_extension_stringtype,
                                               path.FinalExtension()))
      return true;
  }
  return false;
}

bool WebAppFileHandlerCanHandleFileWithMimeType(
    const apps::FileHandler& file_handler,
    const std::string& mime_type) {
  for (const auto& accept_entry : file_handler.accept) {
    if (net::MatchesMimeType(accept_entry.mime_type, mime_type))
      return true;
  }
  return false;
}

bool PrepareNativeLocalFileForWritableApp(const base::FilePath& path,
                                          bool is_directory) {
  // Don't allow links.
  if (base::PathExists(path) && base::IsLink(path))
    return false;

  if (is_directory)
    return base::DirectoryExists(path);

  // Create the file if it doesn't already exist.
  int creation_flags = base::File::FLAG_OPEN_ALWAYS | base::File::FLAG_READ;
  base::File file(path, creation_flags);

  return file.IsValid();
}

// Checks whether a list of paths are all OK for writing and calls a provided
// on_success or on_failure callback when done. A path is OK for writing if it
// is not a symlink, is not in a blocklisted path and can be opened for writing.
// Creates files if they do not exist, but fails for non-existent directory
// paths. On Chrome OS, also fails for non-local files that don't already exist.
class WritableFileChecker
    : public base::RefCountedThreadSafe<WritableFileChecker> {
 public:
  WritableFileChecker(
      const std::vector<base::FilePath>& paths,
      content::BrowserContext* context,
      const std::set<base::FilePath>& directory_paths,
      base::OnceClosure on_success,
      base::OnceCallback<void(const base::FilePath&)> on_failure);

  void Check();

 private:
  friend class base::RefCountedThreadSafe<WritableFileChecker>;
  virtual ~WritableFileChecker();

  // Called when a work item is completed. If all work items are done, this
  // calls the success or failure callback.
  void TaskDone();

  // Reports an error in completing a work item. This may be called more than
  // once, but only the last message will be retained.
  void Error(const base::FilePath& error_path);

  void CheckLocalWritableFiles();

  // Called when processing a file is completed with either a success or an
  // error.
  void OnPrepareFileDone(const base::FilePath& path, bool success);

  const std::vector<base::FilePath> paths_;
  content::BrowserContext* context_;
  const std::set<base::FilePath> directory_paths_;
  size_t outstanding_tasks_;
  base::FilePath error_path_;
  base::OnceClosure on_success_;
  base::OnceCallback<void(const base::FilePath&)> on_failure_;
};

WritableFileChecker::WritableFileChecker(
    const std::vector<base::FilePath>& paths,
    content::BrowserContext* context,
    const std::set<base::FilePath>& directory_paths,
    base::OnceClosure on_success,
    base::OnceCallback<void(const base::FilePath&)> on_failure)
    : paths_(paths),
      context_(context),
      directory_paths_(directory_paths),
      outstanding_tasks_(1),
      on_success_(std::move(on_success)),
      on_failure_(std::move(on_failure)) {}

void WritableFileChecker::Check() {
  outstanding_tasks_ = paths_.size();
  for (const auto& path : paths_) {
    bool is_directory = directory_paths_.find(path) != directory_paths_.end();
#if BUILDFLAG(IS_CHROMEOS_ASH)
    NonNativeFileSystemDelegate* delegate =
        ExtensionsAPIClient::Get()->GetNonNativeFileSystemDelegate();
    if (delegate && delegate->IsUnderNonNativeLocalPath(context_, path)) {
      if (is_directory) {
        delegate->IsNonNativeLocalPathDirectory(
            context_, path,
            base::BindOnce(&WritableFileChecker::OnPrepareFileDone, this,
                           path));
      } else {
        delegate->PrepareNonNativeLocalFileForWritableApp(
            context_, path,
            base::BindOnce(&WritableFileChecker::OnPrepareFileDone, this,
                           path));
      }
      continue;
    }
#endif
    base::ThreadPool::PostTaskAndReplyWithResult(
        FROM_HERE, {base::TaskPriority::USER_BLOCKING, base::MayBlock()},
        base::BindOnce(&PrepareNativeLocalFileForWritableApp, path,
                       is_directory),
        base::BindOnce(&WritableFileChecker::OnPrepareFileDone, this, path));
  }
}

WritableFileChecker::~WritableFileChecker() {}

void WritableFileChecker::TaskDone() {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  if (--outstanding_tasks_ == 0) {
    if (error_path_.empty())
      std::move(on_success_).Run();
    else
      std::move(on_failure_).Run(error_path_);
    on_success_.Reset();
    on_failure_.Reset();
  }
}

// Reports an error in completing a work item. This may be called more than
// once, but only the last message will be retained.
void WritableFileChecker::Error(const base::FilePath& error_path) {
  DCHECK(!error_path.empty());
  error_path_ = error_path;
  TaskDone();
}

void WritableFileChecker::OnPrepareFileDone(const base::FilePath& path,
                                            bool success) {
  if (success)
    TaskDone();
  else
    Error(path);
}

}  // namespace

WebAppFileHandlerMatch::WebAppFileHandlerMatch(
    const apps::FileHandler* file_handler)
    : file_handler_(file_handler) {}
WebAppFileHandlerMatch::~WebAppFileHandlerMatch() = default;

const apps::FileHandler& WebAppFileHandlerMatch::file_handler() const {
  return *file_handler_;
}

bool WebAppFileHandlerMatch::matched_mime_type() const {
  return matched_mime_type_;
}

bool WebAppFileHandlerMatch::matched_file_extension() const {
  return matched_file_extension_;
}

bool WebAppFileHandlerMatch::DoMatch(const EntryInfo& entry) {
  // TODO(crbug.com/1060026): At the moment, apps::FileHandler doesn't have
  // an include_directories flag. It may be necessary to add one as this new
  // representation replaces apps::FileHandlerInfo.
  if (entry.is_directory)
    return false;

  if (WebAppFileHandlerCanHandleFileWithMimeType(*file_handler_,
                                                 entry.mime_type)) {
    matched_mime_type_ = true;
    return true;
  }

  if (WebAppFileHandlerCanHandleFileWithExtension(*file_handler_, entry.path)) {
    matched_file_extension_ = true;
    return true;
  }

  return false;
}

const apps::FileHandlerInfo* FileHandlerForId(const Extension& app,
                                              const std::string& handler_id) {
  const FileHandlersInfo* file_handlers = FileHandlers::GetFileHandlers(&app);
  if (!file_handlers)
    return NULL;

  for (auto i = file_handlers->cbegin(); i != file_handlers->cend(); i++) {
    if (i->id == handler_id)
      return &*i;
  }
  return NULL;
}

std::vector<FileHandlerMatch> FindFileHandlerMatchesForEntries(
    const Extension& app,
    const std::vector<EntryInfo>& entries) {
  if (entries.empty())
    return std::vector<FileHandlerMatch>();

  // Look for file handlers which can handle all the MIME types
  // or file name extensions specified.
  const FileHandlersInfo* file_handlers = FileHandlers::GetFileHandlers(&app);
  if (!file_handlers)
    return std::vector<FileHandlerMatch>();

  return MatchesFromFileHandlersForEntries(*file_handlers, entries);
}

std::vector<FileHandlerMatch> MatchesFromFileHandlersForEntries(
    const FileHandlersInfo& file_handlers,
    const std::vector<EntryInfo>& entries) {
  std::vector<FileHandlerMatch> matches;

  for (const apps::FileHandlerInfo& handler : file_handlers) {
    bool handles_all_types = true;
    FileHandlerMatch match;

    // Lifetime of the handler should be the same as usage of the matches
    // so the pointer shouldn't end up stale.
    match.handler = &handler;
    match.matched_mime = match.matched_file_extension = false;
    for (const auto& entry : entries) {
      if (entry.is_directory) {
        if (!handler.include_directories) {
          handles_all_types = false;
          break;
        }
      } else {
        match.matched_mime =
            FileHandlerCanHandleFileWithMimeType(handler, entry.mime_type);
        if (!match.matched_mime) {
          match.matched_file_extension =
              FileHandlerCanHandleFileWithExtension(handler, entry.path);
          if (!match.matched_file_extension) {
            handles_all_types = false;
            break;
          }
        }
      }
    }
    if (handles_all_types) {
      matches.push_back(match);
    }
  }
  return matches;
}

std::vector<WebAppFileHandlerMatch> MatchesFromWebAppFileHandlersForEntries(
    const apps::FileHandlers& file_handlers,
    const std::vector<EntryInfo>& entries) {
  std::vector<WebAppFileHandlerMatch> matches;

  for (const auto& file_handler : file_handlers) {
    bool handles_all_types = true;

    // The lifetime of the file handler should be the same as the usage of the
    // matches, so the pointer shouldn't end up stale.
    WebAppFileHandlerMatch match(&file_handler);

    for (const auto& entry : entries) {
      if (!match.DoMatch(entry)) {
        handles_all_types = false;
        break;
      }
    }

    if (handles_all_types)
      matches.push_back(match);
  }

  return matches;
}

bool FileHandlerCanHandleEntry(const apps::FileHandlerInfo& handler,
                               const EntryInfo& entry) {
  if (entry.is_directory)
    return handler.include_directories;

  return FileHandlerCanHandleFileWithMimeType(handler, entry.mime_type) ||
         FileHandlerCanHandleFileWithExtension(handler, entry.path);
}

bool WebAppFileHandlerCanHandleEntry(const apps::FileHandler& handler,
                                     const EntryInfo& entry) {
  // TODO(crbug.com/938103): At the moment, apps::FileHandler doesn't have an
  // include_directories flag. It may be necessary to add one as this new
  // representation replaces apps::FileHandlerInfo.
  if (entry.is_directory)
    return false;

  return WebAppFileHandlerCanHandleFileWithMimeType(handler, entry.mime_type) ||
         WebAppFileHandlerCanHandleFileWithExtension(handler, entry.path);
}

GrantedFileEntry CreateFileEntry(content::BrowserContext* context,
                                 const Extension* extension,
                                 int renderer_id,
                                 const base::FilePath& path,
                                 bool is_directory) {
  GrantedFileEntry result;
  storage::IsolatedContext* isolated_context =
      storage::IsolatedContext::GetInstance();
  DCHECK(isolated_context);

  storage::IsolatedContext::ScopedFSHandle filesystem =
      isolated_context->RegisterFileSystemForPath(
          storage::kFileSystemTypeNativeForPlatformApp, std::string(), path,
          &result.registered_name);
  result.filesystem_id = filesystem.id();

  content::ChildProcessSecurityPolicy* policy =
      content::ChildProcessSecurityPolicy::GetInstance();
  policy->GrantReadFileSystem(renderer_id, result.filesystem_id);
  if (HasFileSystemWritePermission(extension)) {
    if (is_directory) {
      policy->GrantCreateReadWriteFileSystem(renderer_id, result.filesystem_id);
    } else {
      policy->GrantWriteFileSystem(renderer_id, result.filesystem_id);
      policy->GrantDeleteFromFileSystem(renderer_id, result.filesystem_id);
    }
  }

  result.id = result.filesystem_id + ":" + result.registered_name;
  return result;
}

void PrepareFilesForWritableApp(
    const std::vector<base::FilePath>& paths,
    content::BrowserContext* context,
    const std::set<base::FilePath>& directory_paths,
    base::OnceClosure on_success,
    base::OnceCallback<void(const base::FilePath&)> on_failure) {
  auto checker = base::MakeRefCounted<WritableFileChecker>(
      paths, context, directory_paths, std::move(on_success),
      std::move(on_failure));
  checker->Check();
}

bool HasFileSystemWritePermission(const Extension* extension) {
  return extension->permissions_data()->HasAPIPermission(
      APIPermission::kFileSystemWrite);
}

bool ValidateFileEntryAndGetPath(const std::string& filesystem_name,
                                 const std::string& filesystem_path,
                                 int render_process_id,
                                 base::FilePath* file_path,
                                 std::string* error) {
  if (filesystem_path.empty()) {
    *error = kInvalidParameters;
    return false;
  }

  std::string filesystem_id;
  if (!storage::CrackIsolatedFileSystemName(filesystem_name, &filesystem_id)) {
    *error = kInvalidParameters;
    return false;
  }

  // Only return the display path if the process has read access to the
  // filesystem.
  content::ChildProcessSecurityPolicy* policy =
      content::ChildProcessSecurityPolicy::GetInstance();
  if (!policy->CanReadFileSystem(render_process_id, filesystem_id)) {
    *error = kSecurityError;
    return false;
  }

  storage::IsolatedContext* context = storage::IsolatedContext::GetInstance();
  base::FilePath relative_path =
      base::FilePath::FromUTF8Unsafe(filesystem_path);
  base::FilePath virtual_path =
      context->CreateVirtualRootPath(filesystem_id).Append(relative_path);
  storage::FileSystemType type;
  storage::FileSystemMountOption mount_option;
  std::string cracked_id;
  if (!context->CrackVirtualPath(virtual_path, &filesystem_id, &type,
                                 &cracked_id, file_path, &mount_option)) {
    *error = kInvalidParameters;
    return false;
  }

  // The file system API is only intended to operate on file entries that
  // correspond to a native file, selected by the user so only allow file
  // systems returned by the file system API or from a drag and drop operation.
  if (type != storage::kFileSystemTypeNativeForPlatformApp &&
      type != storage::kFileSystemTypeDragged) {
    *error = kInvalidParameters;
    return false;
  }

  return true;
}

}  // namespace app_file_handler_util

}  // namespace extensions