cros-disks/smbfs_helper.cc

// Copyright 2019 The Chromium OS 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 "cros-disks/smbfs_helper.h"

#include <base/files/file_path.h>
#include <base/logging.h>
#include <base/strings/string_number_conversions.h>
#include <base/strings/string_util.h>

#include "cros-disks/fuse_mounter.h"
#include "cros-disks/mount_options.h"
#include "cros-disks/platform.h"
#include "cros-disks/uri.h"

namespace cros_disks {
namespace {

const char kUserName[] = "fuse-smbfs";
const char kHelperTool[] = "/usr/sbin/smbfs";
const char kType[] = "smbfs";

const char kMojoIdOptionPrefix[] = "mojo_id=";
const char kDbusSocketPath[] = "/run/dbus";

}  // namespace

SmbfsHelper::SmbfsHelper(const Platform* platform,
                         brillo::ProcessReaper* process_reaper)
    : FUSEHelper(kType,
                 platform,
                 process_reaper,
                 base::FilePath(kHelperTool),
                 kUserName) {}

SmbfsHelper::~SmbfsHelper() = default;

std::unique_ptr<FUSEMounter> SmbfsHelper::CreateMounter(
    const base::FilePath& working_dir,
    const Uri& source,
    const base::FilePath& target_path,
    const std::vector<std::string>& options) const {
  const std::string& mojo_id = source.path();

  // Enforced by FUSEHelper::CanMount().
  DCHECK(!mojo_id.empty());

  uid_t files_uid;
  gid_t files_gid;
  if (!platform()->GetUserAndGroupId(kFilesUser, &files_uid, nullptr) ||
      !platform()->GetGroupId(kFilesGroup, &files_gid)) {
    return nullptr;
  }

  MountOptions mount_options;
  mount_options.EnforceOption(kMojoIdOptionPrefix + mojo_id);
  mount_options.Initialize(options, true, base::IntToString(files_uid),
                           base::IntToString(files_gid));

  // Bind DBus communication socket into the sandbox.
  std::vector<FUSEMounter::BindPath> paths = {
      {kDbusSocketPath, true},
  };

  // TODO(crbug.com/939235): Create a seccomp policy for smbfs.
  return std::make_unique<FUSEMounter>(
      "", target_path.value(), type(), mount_options, platform(),
      process_reaper(), program_path().value(), user(), "", paths,
      true /* permit_network_access */);
}

}  // namespace cros_disks