xref: /dports/www/chromium-legacy/chromium-88.0.4324.182/chrome/browser/chromeos/smb_client/smb_service.cc

// Copyright 2017 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 "chrome/browser/chromeos/smb_client/smb_service.h"

#include <utility>

#include "base/bind.h"
#include "base/callback_helpers.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/string_number_conversions.h"
#include "base/task/post_task.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/default_tick_clock.h"
#include "base/unguessable_token.h"
#include "chrome/browser/chromeos/file_system_provider/mount_path_util.h"
#include "chrome/browser/chromeos/file_system_provider/provided_file_system_info.h"
#include "chrome/browser/chromeos/kerberos/kerberos_credentials_manager.h"
#include "chrome/browser/chromeos/kerberos/kerberos_credentials_manager_factory.h"
#include "chrome/browser/chromeos/profiles/profile_helper.h"
#include "chrome/browser/chromeos/smb_client/discovery/mdns_host_locator.h"
#include "chrome/browser/chromeos/smb_client/discovery/netbios_client.h"
#include "chrome/browser/chromeos/smb_client/discovery/netbios_host_locator.h"
#include "chrome/browser/chromeos/smb_client/smb_file_system.h"
#include "chrome/browser/chromeos/smb_client/smb_file_system_id.h"
#include "chrome/browser/chromeos/smb_client/smb_kerberos_credentials_updater.h"
#include "chrome/browser/chromeos/smb_client/smb_provider.h"
#include "chrome/browser/chromeos/smb_client/smb_service_helper.h"
#include "chrome/browser/chromeos/smb_client/smb_share_info.h"
#include "chrome/browser/chromeos/smb_client/smb_url.h"
#include "chrome/browser/platform_util.h"
#include "chrome/browser/ui/webui/chromeos/smb_shares/smb_credentials_dialog.h"
#include "chrome/common/chrome_features.h"
#include "chrome/common/pref_names.h"
#include "chromeos/dbus/dbus_thread_manager.h"
#include "chromeos/dbus/smb_provider_client.h"
#include "components/pref_registry/pref_registry_syncable.h"
#include "components/prefs/pref_service.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/storage_partition.h"
#include "crypto/random.h"
#include "net/base/network_interfaces.h"
#include "url/url_util.h"

namespace chromeos {
namespace smb_client {

namespace {

const char kShareUrlKey[] = "share_url";
const char kModeKey[] = "mode";
const char kModeDropDownValue[] = "drop_down";
const char kModePreMountValue[] = "pre_mount";
const char kModeUnknownValue[] = "unknown";
const base::TimeDelta kHostDiscoveryInterval = base::TimeDelta::FromSeconds(60);
// -3 is chosen because -1 and -2 have special meaning in smbprovider.
const int32_t kInvalidMountId = -3;
// Maximum number of smbfs shares to be mounted at the same time, only enforced
// on user-initiated mount requests.
const size_t kMaxSmbFsShares = 16;
// Length of salt used to obfuscate stored password in smbfs.
const size_t kSaltLength = 16;
static_assert(kSaltLength >=
                  smbfs::mojom::CredentialStorageOptions::kMinSaltLength,
              "Minimum salt length is "
              "smbfs::mojom::CredentialStorageOptions::kMinSaltLength");

net::NetworkInterfaceList GetInterfaces() {
  net::NetworkInterfaceList list;
  if (!net::GetNetworkList(&list, net::EXCLUDE_HOST_SCOPE_VIRTUAL_INTERFACES)) {
    LOG(ERROR) << "GetInterfaces failed";
  }
  return list;
}

std::unique_ptr<NetBiosClientInterface> GetNetBiosClient(Profile* profile) {
  auto* network_context =
      content::BrowserContext::GetDefaultStoragePartition(profile)
          ->GetNetworkContext();
  return std::make_unique<NetBiosClient>(network_context);
}

bool IsSmbFsEnabled() {
  return base::FeatureList::IsEnabled(features::kSmbFs);
}

// Metric recording functions.

// This enum is used to define the buckets for an enumerated UMA histogram.
// Hence,
//   (a) existing enumerated constants should never be deleted or reordered, and
//   (b) new constants should only be appended at the end of the enumeration.
enum class AuthMethod {
  kNoCredentials = 0,
  kUsernameOnly = 1,
  kUsernameAndPassword = 2,
  kSSOKerberosAD = 3,
  kSSOKerberosGaia = 4,
  kMaxValue = kSSOKerberosGaia,
};

void RecordMountResult(SmbMountResult result) {
  DCHECK_LE(result, SmbMountResult::kMaxValue);
  UMA_HISTOGRAM_ENUMERATION("NativeSmbFileShare.MountResult", result);
}

void RecordRemountResult(SmbMountResult result) {
  DCHECK_LE(result, SmbMountResult::kMaxValue);
  UMA_HISTOGRAM_ENUMERATION("NativeSmbFileShare.RemountResult", result);
}

void RecordAuthenticationMethod(AuthMethod method) {
  DCHECK_LE(method, AuthMethod::kMaxValue);
  UMA_HISTOGRAM_ENUMERATION("NativeSmbFileShare.AuthenticationMethod", method);
}

base::ScopedFD MakeFdWithContents(const std::string& contents) {
  const size_t content_size = contents.size();

  base::ScopedFD read_fd, write_fd;
  if (!base::CreatePipe(&read_fd, &write_fd, true /* non_blocking */)) {
    LOG(ERROR) << "Unable to create pipe";
    return {};
  }
  bool success =
      base::WriteFileDescriptor(write_fd.get(),
                                reinterpret_cast<const char*>(&content_size),
                                sizeof(content_size)) &&
      base::WriteFileDescriptor(write_fd.get(), contents.data(), content_size);
  if (!success) {
    PLOG(ERROR) << "Unable to write contents to pipe";
    return {};
  }
  return read_fd;
}

}  // namespace

bool SmbService::disable_share_discovery_for_testing_ = false;

SmbService::SmbService(Profile* profile,
                       std::unique_ptr<base::TickClock> tick_clock)
    : provider_id_(ProviderId::CreateFromNativeId("smb")),
      profile_(profile),
      tick_clock_(std::move(tick_clock)),
      registry_(profile) {
  user_manager::User* user =
      chromeos::ProfileHelper::Get()->GetUserByProfile(profile_);
  DCHECK(user);

  SmbProviderClient* client = GetSmbProviderClient();
  if (!client) {
    return;
  }

  if (user->IsActiveDirectoryUser()) {
    const std::string& account_id_guid = user->GetAccountId().GetObjGuid();
    SetupKerberos(account_id_guid);
    return;
  }

  KerberosCredentialsManager* credentials_manager =
      KerberosCredentialsManagerFactory::GetExisting(profile);
  if (credentials_manager && credentials_manager->IsKerberosEnabled()) {
    smb_credentials_updater_ = std::make_unique<SmbKerberosCredentialsUpdater>(
        credentials_manager,
        base::BindRepeating(&SmbService::UpdateKerberosCredentials,
                            AsWeakPtr()));
    SetupKerberos(smb_credentials_updater_->active_account_name());
    return;
  }

  // Post a task to complete setup. This is to allow unit tests to perform
  // expectations setup after constructing an instance. It also mirrors the
  // behaviour when Kerberos is being used.
  base::ThreadTaskRunnerHandle::Get()->PostTask(
      FROM_HERE, base::BindOnce(&SmbService::CompleteSetup, AsWeakPtr()));
}

SmbService::~SmbService() {
  net::NetworkChangeNotifier::RemoveNetworkChangeObserver(this);
  if (chromeos::PowerManagerClient::Get()) {
    chromeos::PowerManagerClient::Get()->RemoveObserver(this);
  }
}

void SmbService::Shutdown() {
  // Unmount and destroy all smbfs instances explicitly before destruction,
  // since SmbFsShare accesses KeyedServices on destruction.
  smbfs_shares_.clear();
}

// static
void SmbService::RegisterProfilePrefs(
    user_prefs::PrefRegistrySyncable* registry) {
  registry->RegisterBooleanPref(prefs::kNetworkFileSharesAllowed, true);
  registry->RegisterBooleanPref(prefs::kNetBiosShareDiscoveryEnabled, true);
  registry->RegisterBooleanPref(prefs::kNTLMShareAuthenticationEnabled, true);
  registry->RegisterListPref(prefs::kNetworkFileSharesPreconfiguredShares);
  registry->RegisterStringPref(prefs::kMostRecentlyUsedNetworkFileShareURL, "");
  SmbPersistedShareRegistry::RegisterProfilePrefs(registry);
}

void SmbService::UnmountSmbFs(const base::FilePath& mount_path) {
  DCHECK(!mount_path.empty());

  for (auto it = smbfs_shares_.begin(); it != smbfs_shares_.end(); ++it) {
    SmbFsShare* share = it->second.get();
    if (share->mount_path() == mount_path) {
      if (share->options().save_restore_password) {
        share->RemoveSavedCredentials(
            base::BindOnce(&SmbService::OnSmbfsRemoveSavedCredentialsDone,
                           base::Unretained(this), it->first));
      } else {
        // If the password wasn't saved, there's nothing for smbfs to do.
        OnSmbfsRemoveSavedCredentialsDone(it->first, true /* success */);
      }
      return;
    }
  }

  LOG(WARNING) << "Smbfs mount path not found: " << mount_path;
}

void SmbService::OnSmbfsRemoveSavedCredentialsDone(const std::string& mount_id,
                                                   bool success) {
  DCHECK(!mount_id.empty());

  auto it = smbfs_shares_.find(mount_id);
  if (it == smbfs_shares_.end()) {
    LOG(WARNING) << "Smbfs mount id " << mount_id << " already deleted";
    return;
  }

  // UnmountSmbFs() is called by an explicit unmount by the user. In this
  // case, forget the share.
  registry_.Delete(it->second->share_url());
  smbfs_shares_.erase(it);
}

SmbFsShare* SmbService::GetSmbFsShareForPath(const base::FilePath& path) {
  DCHECK(!path.empty());
  DCHECK(path.IsAbsolute());

  for (const auto& entry : smbfs_shares_) {
    const base::FilePath mount_path = entry.second->mount_path();
    if (mount_path == path || mount_path.IsParent(path)) {
      return entry.second.get();
    }
  }
  return nullptr;
}

void SmbService::GatherSharesInNetwork(HostDiscoveryResponse discovery_callback,
                                       GatherSharesResponse shares_callback) {
  auto preconfigured_shares = GetPreconfiguredSharePathsForDropdown();
  if (!preconfigured_shares.empty()) {
    shares_callback.Run(std::move(preconfigured_shares), false);
  }
  share_finder_->GatherSharesInNetwork(
      std::move(discovery_callback),
      base::BindOnce(
          [](GatherSharesResponse shares_callback,
             const std::vector<SmbUrl>& shares_gathered) {
            std::move(shares_callback).Run(shares_gathered, true);
          },
          std::move(shares_callback)));
}

void SmbService::UpdateSharePath(int32_t mount_id,
                                 const std::string& share_path,
                                 StartReadDirIfSuccessfulCallback reply) {
  GetSmbProviderClient()->UpdateSharePath(
      mount_id, share_path,
      base::BindOnce(&SmbService::OnUpdateSharePathResponse, AsWeakPtr(),
                     mount_id, std::move(reply)));
}

void SmbService::OnUpdateSharePathResponse(
    int32_t mount_id,
    StartReadDirIfSuccessfulCallback reply,
    smbprovider::ErrorType error) {
  if (error != smbprovider::ERROR_OK) {
    LOG(ERROR) << "Failed to update the share path for mount id " << mount_id;
    std::move(reply).Run(false /* should_retry_start_read_dir */);
    return;
  }
  std::move(reply).Run(true /* should_retry_start_read_dir */);
}

void SmbService::Mount(const file_system_provider::MountOptions& options,
                       const base::FilePath& share_path,
                       const std::string& username_input,
                       const std::string& password_input,
                       bool use_kerberos,
                       bool should_open_file_manager_after_mount,
                       bool save_credentials,
                       MountResponse callback) {
  SmbUrl parsed_url(share_path.value());
  if (!parsed_url.IsValid() || parsed_url.GetShare().empty()) {
    // Handle invalid URLs early to avoid having unaccounted for UMA counts for
    // authentication method.
    std::move(callback).Run(SmbMountResult::kInvalidUrl);
    return;
  }

  // When using kerberos, the URL must contain the hostname because that is used
  // to obtain the ticket. If the user enters an IP address, Samba will give us
  // a permission error, which isn't correct or useful to the end user.
  if (use_kerberos && url::HostIsIPAddress(parsed_url.GetHost())) {
    std::move(callback).Run(SmbMountResult::kInvalidSsoUrl);
    return;
  }

  if (IsShareMounted(parsed_url)) {
    // Prevent a share from being mounted twice. Although technically possible,
    // the UX when doing so is incomplete.
    std::move(callback).Run(SmbMountResult::kMountExists);
    return;
  }

  if (IsSmbFsEnabled() && smbfs_shares_.size() >= kMaxSmbFsShares) {
    // Prevent users from mounting an excessive number of shares.
    std::move(callback).Run(SmbMountResult::kTooManyOpened);
    return;
  }

  std::string username;
  std::string password;
  std::string workgroup;

  user_manager::User* user =
      chromeos::ProfileHelper::Get()->GetUserByProfile(profile_);
  DCHECK(user);

  if (use_kerberos) {
    // Differentiate between AD and KerberosEnabled via policy in metrics.
    if (IsKerberosEnabledViaPolicy()) {
      RecordAuthenticationMethod(AuthMethod::kSSOKerberosGaia);
    } else {
      RecordAuthenticationMethod(AuthMethod::kSSOKerberosAD);
    }

    // Get the user's username and workgroup from their email address to be used
    // for Kerberos authentication.
    ParseUserPrincipalName(user->GetDisplayEmail(), &username, &workgroup);
  } else {
    // Record authentication method metrics.
    if (!username_input.empty() && !password_input.empty()) {
      RecordAuthenticationMethod(AuthMethod::kUsernameAndPassword);
    } else if (!username_input.empty()) {
      RecordAuthenticationMethod(AuthMethod::kUsernameOnly);
    } else {
      RecordAuthenticationMethod(AuthMethod::kNoCredentials);
    }

    // Use provided credentials and parse the username into username and
    // workgroup if necessary.
    username = username_input;
    password = password_input;
    ParseUserName(username_input, &username, &workgroup);
  }

  // Construct the file system ID before calling mount so that numerous
  // arguments don't have to be plumbed through.
  file_system_provider::MountOptions provider_options(options);
  if (use_kerberos) {
    provider_options.file_system_id =
        CreateFileSystemId(share_path, use_kerberos);
  } else {
    std::string full_username;
    if (save_credentials) {
      // Only save the username if the user request credentials be saved.
      full_username = username;
      if (!workgroup.empty()) {
        DCHECK(!username.empty());
        full_username.append("@");
        full_username.append(workgroup);
      }
    }
    provider_options.file_system_id =
        CreateFileSystemIdForUser(share_path, full_username);
  }
  std::vector<uint8_t> salt;
  if (save_credentials && !password.empty()) {
    // Only generate a salt if threre's a password and we've been asked to save
    // credentials. If there is no password, there's nothing for smbfs to store
    // and the salt is unused.
    salt.resize(kSaltLength);
    crypto::RandBytes(salt);
  }
  SmbShareInfo info(parsed_url, options.display_name, username, workgroup,
                    use_kerberos, salt);
  MountInternal(provider_options, info, password, save_credentials,
                false /* skip_connect */,
                base::BindOnce(&SmbService::MountInternalDone,
                               base::Unretained(this), std::move(callback),
                               info, should_open_file_manager_after_mount));

  profile_->GetPrefs()->SetString(prefs::kMostRecentlyUsedNetworkFileShareURL,
                                  share_path.value());
}

void SmbService::MountInternalDone(MountResponse callback,
                                   const SmbShareInfo& info,
                                   bool should_open_file_manager_after_mount,
                                   SmbMountResult result,
                                   const base::FilePath& mount_path) {
  if (result != SmbMountResult::kSuccess) {
    std::move(callback).Run(result);
    return;
  }

  DCHECK(!mount_path.empty());
  if (should_open_file_manager_after_mount) {
    platform_util::ShowItemInFolder(profile_, mount_path);
  }

  if (IsSmbFsEnabled()) {
    registry_.Save(info);
  }

  RecordMountCount();
  std::move(callback).Run(SmbMountResult::kSuccess);
}

void SmbService::MountInternal(
    const file_system_provider::MountOptions& options,
    const SmbShareInfo& info,
    const std::string& password,
    bool save_credentials,
    bool skip_connect,
    MountInternalCallback callback) {
  user_manager::User* user =
      chromeos::ProfileHelper::Get()->GetUserByProfile(profile_);
  DCHECK(user);

  if (IsSmbFsEnabled()) {
    SmbFsShare::MountOptions smbfs_options;
    smbfs_options.resolved_host =
        share_finder_->GetResolvedHost(info.share_url().GetHost());
    smbfs_options.username = info.username();
    smbfs_options.workgroup = info.workgroup();
    smbfs_options.password = password;
    smbfs_options.allow_ntlm = IsNTLMAuthenticationEnabled();
    smbfs_options.skip_connect = skip_connect;
    if (save_credentials && !info.password_salt().empty()) {
      smbfs_options.save_restore_password = true;
      smbfs_options.account_hash = user->username_hash();
      smbfs_options.password_salt = info.password_salt();
    }
    if (info.use_kerberos()) {
      if (user->IsActiveDirectoryUser()) {
        smbfs_options.kerberos_options =
            base::make_optional<SmbFsShare::KerberosOptions>(
                SmbFsShare::KerberosOptions::Source::kActiveDirectory,
                user->GetAccountId().GetObjGuid());
      } else if (smb_credentials_updater_) {
        smbfs_options.kerberos_options =
            base::make_optional<SmbFsShare::KerberosOptions>(
                SmbFsShare::KerberosOptions::Source::kKerberos,
                smb_credentials_updater_->active_account_name());
      } else {
        LOG(WARNING) << "No Kerberos credential source available";
        std::move(callback).Run(SmbMountResult::kAuthenticationFailed, {});
        return;
      }
    }

    std::unique_ptr<SmbFsShare> mount = std::make_unique<SmbFsShare>(
        profile_, info.share_url(), info.display_name(), smbfs_options);
    if (smbfs_mounter_creation_callback_) {
      mount->SetMounterCreationCallbackForTest(
          smbfs_mounter_creation_callback_);
    }

    SmbFsShare* raw_mount = mount.get();
    const std::string mount_id = mount->mount_id();
    smbfs_shares_[mount_id] = std::move(mount);
    raw_mount->Mount(base::BindOnce(&SmbService::OnSmbfsMountDone, AsWeakPtr(),
                                    mount_id, std::move(callback)));
  } else {
    // If using kerberos, the hostname should not be resolved since kerberos
    // service tickets are keyed on hosname.
    const SmbUrl url = info.use_kerberos()
                           ? info.share_url()
                           : share_finder_->GetResolvedUrl(info.share_url());

    SmbProviderClient::MountOptions smb_mount_options;
    smb_mount_options.original_path = info.share_url().ToString();
    smb_mount_options.username = info.username();
    smb_mount_options.workgroup = info.workgroup();
    smb_mount_options.ntlm_enabled = IsNTLMAuthenticationEnabled();
    smb_mount_options.save_password = save_credentials && !info.use_kerberos();
    smb_mount_options.account_hash = user->username_hash();
    smb_mount_options.skip_connect = skip_connect;
    GetSmbProviderClient()->Mount(
        base::FilePath(url.ToString()), smb_mount_options,
        MakeFdWithContents(password),
        base::BindOnce(&SmbService::OnProviderMountDone, AsWeakPtr(),
                       std::move(callback), options, save_credentials));
  }
}

void SmbService::OnSmbfsMountDone(const std::string& smbfs_mount_id,
                                  MountInternalCallback callback,
                                  SmbMountResult result) {
  RecordMountResult(result);

  if (result != SmbMountResult::kSuccess) {
    smbfs_shares_.erase(smbfs_mount_id);
    std::move(callback).Run(result, {});
    return;
  }

  SmbFsShare* mount = smbfs_shares_[smbfs_mount_id].get();
  if (!mount) {
    LOG(ERROR) << "smbfs mount " << smbfs_mount_id << " does not exist";
    std::move(callback).Run(SmbMountResult::kUnknownFailure, {});
    return;
  }

  std::move(callback).Run(SmbMountResult::kSuccess, mount->mount_path());
}

void SmbService::OnProviderMountDone(
    MountInternalCallback callback,
    const file_system_provider::MountOptions& options,
    bool save_credentials,
    smbprovider::ErrorType error,
    int32_t mount_id) {
  SmbMountResult mount_result = TranslateErrorToMountResult(error);
  RecordMountResult(mount_result);

  if (mount_result != SmbMountResult::kSuccess) {
    std::move(callback).Run(mount_result, {});
    return;
  }

  DCHECK_GE(mount_id, 0);
  mount_id_map_[options.file_system_id] = mount_id;

  base::File::Error result =
      GetProviderService()->MountFileSystem(provider_id_, options);
  if (result != base::File::FILE_OK) {
    mount_id_map_.erase(options.file_system_id);
    // If the password was asked to be saved, remove it.
    GetSmbProviderClient()->Unmount(
        mount_id, save_credentials /* remove_password */, base::DoNothing());

    std::move(callback).Run(TranslateErrorToMountResult(result), {});
    return;
  }

  base::FilePath mount_path = file_system_provider::util::GetMountPath(
      profile_, provider_id_, options.file_system_id);
  std::move(callback).Run(SmbMountResult::kSuccess, mount_path);
}

int32_t SmbService::GetMountId(const ProvidedFileSystemInfo& info) const {
  const auto iter = mount_id_map_.find(info.file_system_id());
  if (iter == mount_id_map_.end()) {
    // Either the mount process has not yet completed, or it failed to provide
    // us with a mount id.
    return kInvalidMountId;
  }
  return iter->second;
}

base::File::Error SmbService::Unmount(
    const std::string& file_system_id,
    file_system_provider::Service::UnmountReason reason) {
  base::File::Error result = GetProviderService()->UnmountFileSystem(
      provider_id_, file_system_id, reason);
  // Always erase the mount_id, because at this point, the share has already
  // been unmounted in smbprovider.
  mount_id_map_.erase(file_system_id);
  return result;
}

file_system_provider::Service* SmbService::GetProviderService() const {
  return file_system_provider::Service::Get(profile_);
}

SmbProviderClient* SmbService::GetSmbProviderClient() const {
  // If the DBusThreadManager or the SmbProviderClient aren't available,
  // there isn't much we can do. This should only happen when running tests.
  if (!chromeos::DBusThreadManager::IsInitialized() ||
      !chromeos::DBusThreadManager::Get()) {
    return nullptr;
  }
  return chromeos::DBusThreadManager::Get()->GetSmbProviderClient();
}

void SmbService::RestoreMounts() {
  std::vector<ProvidedFileSystemInfo> provided_file_systems =
      GetProviderService()->GetProvidedFileSystemInfoList(provider_id_);

  std::vector<SmbUrl> preconfigured_shares =
      GetPreconfiguredSharePathsForPremount();

  std::vector<SmbShareInfo> saved_smbfs_shares;
  if (IsSmbFsEnabled()) {
    // Restore smbfs shares.
    // TODO(crbug.com/1055571): Migrate saved smbprovider shares to smbfs.
    saved_smbfs_shares = registry_.GetAll();
  }

  if (!provided_file_systems.empty() || !saved_smbfs_shares.empty() ||
      !preconfigured_shares.empty()) {
    share_finder_->DiscoverHostsInNetwork(base::BindOnce(
        &SmbService::OnHostsDiscovered, AsWeakPtr(),
        std::move(provided_file_systems), std::move(saved_smbfs_shares),
        std::move(preconfigured_shares)));
  }
}

void SmbService::OnHostsDiscovered(
    const std::vector<ProvidedFileSystemInfo>& file_systems,
    const std::vector<SmbShareInfo>& saved_smbfs_shares,
    const std::vector<SmbUrl>& preconfigured_shares) {
  for (const auto& file_system : file_systems) {
    Remount(file_system);
  }
  for (const auto& smbfs_share : saved_smbfs_shares) {
    MountSavedSmbfsShare(smbfs_share);
  }
  for (const auto& url : preconfigured_shares) {
    MountPreconfiguredShare(url);
  }
}

void SmbService::OnHostsDiscoveredForUpdateSharePath(
    int32_t mount_id,
    const std::string& share_path,
    StartReadDirIfSuccessfulCallback reply) {
  SmbUrl resolved_url(share_path);
  if (share_finder_->TryResolveUrl(SmbUrl(share_path), &resolved_url)) {
    UpdateSharePath(mount_id, resolved_url.ToString(), std::move(reply));
  } else {
    std::move(reply).Run(false /* should_retry_start_read_dir */);
  }
}

void SmbService::Remount(const ProvidedFileSystemInfo& file_system_info) {
  const base::FilePath share_path =
      GetSharePathFromFileSystemId(file_system_info.file_system_id());
  const bool is_kerberos_chromad =
      IsKerberosChromadFileSystemId(file_system_info.file_system_id());

  std::string workgroup;
  std::string username;

  user_manager::User* user =
      chromeos::ProfileHelper::Get()->GetUserByProfile(profile_);
  DCHECK(user);
  if (is_kerberos_chromad) {
    DCHECK(user->IsActiveDirectoryUser());

    ParseUserPrincipalName(user->GetDisplayEmail(), &username, &workgroup);
  } else {
    base::Optional<std::string> user_workgroup =
        GetUserFromFileSystemId(file_system_info.file_system_id());
    if (user_workgroup &&
        !ParseUserName(*user_workgroup, &username, &workgroup)) {
      LOG(ERROR) << "Failed to parse username/workgroup from file system ID";
    }
  }

  SmbUrl parsed_url(share_path.value());
  if (!parsed_url.IsValid()) {
    OnRemountResponse(file_system_info.file_system_id(),
                      smbprovider::ERROR_INVALID_URL, kInvalidMountId);
    return;
  }

  // If using kerberos, the hostname should not be resolved since kerberos
  // service tickets are keyed on hosname.
  const SmbUrl resolved_url = is_kerberos_chromad
                                  ? parsed_url
                                  : share_finder_->GetResolvedUrl(parsed_url);

  // An empty password is passed to Mount to conform with the credentials API
  // which expects username & workgroup strings along with a password file
  // descriptor.
  SmbProviderClient::MountOptions smb_mount_options;
  smb_mount_options.original_path = parsed_url.ToString();
  smb_mount_options.username = username;
  smb_mount_options.workgroup = workgroup;
  smb_mount_options.ntlm_enabled = IsNTLMAuthenticationEnabled();
  smb_mount_options.skip_connect = true;
  smb_mount_options.restore_password =
      !username.empty() && !is_kerberos_chromad;
  smb_mount_options.account_hash = user->username_hash();
  GetSmbProviderClient()->Mount(
      base::FilePath(resolved_url.ToString()), smb_mount_options,
      MakeFdWithContents(""),
      base::BindOnce(&SmbService::OnRemountResponse, AsWeakPtr(),
                     file_system_info.file_system_id()));
}

void SmbService::OnRemountResponse(const std::string& file_system_id,
                                   smbprovider::ErrorType error,
                                   int32_t mount_id) {
  RecordRemountResult(TranslateErrorToMountResult(error));

  if (error != smbprovider::ERROR_OK) {
    LOG(ERROR) << "SmbService: failed to restore filesystem with error: "
               << error;
    // Note: The filesystem isn't removed on failure because doing so will
    // stop persisting the mount. The mount should only be removed as a result
    // of user action, and not due to failures, which might be transient (i.e.
    // smbprovider crashed).
    return;
  }

  DCHECK_GE(mount_id, 0);
  mount_id_map_[file_system_id] = mount_id;
}

void SmbService::MountSavedSmbfsShare(const SmbShareInfo& info) {
  MountInternal(
      {} /* fsp::MountOptions, ignored by smbfs */, info, "" /* password */,
      true /* save_credentials */, true /* skip_connect */,
      base::BindOnce(
          [](SmbMountResult result, const base::FilePath& mount_path) {
            LOG_IF(ERROR, result != SmbMountResult::kSuccess)
                << "Error restoring saved share: " << static_cast<int>(result);
          }));
}

void SmbService::MountPreconfiguredShare(const SmbUrl& share_url) {
  file_system_provider::MountOptions mount_options;
  mount_options.display_name =
      base::FilePath(share_url.ToString()).BaseName().value();
  mount_options.writable = true;
  // |is_chromad_kerberos| is false because we do not pass user and workgroup
  // at mount time. Premounts also do not get remounted and currently
  // |is_chromad_kerberos| is only used at remounts to determine if the share
  // was mounted with chromad kerberos.
  // TODO(crbug.com/922269): Support kerberos for preconfigured shares.
  mount_options.file_system_id = CreateFileSystemId(
      base::FilePath(share_url.ToString()), false /* is_chromad_kerberos */);
  // Disable remounting of preconfigured shares.
  mount_options.persistent = false;

  // Note: Preconfigured shares are mounted without credentials.
  SmbShareInfo info(share_url, mount_options.display_name, "" /* username */,
                    "" /* workgroup */, false /* use_kerberos */);
  MountInternal(
      mount_options, info, "" /* password */, false /* save_credentials */,
      true /* skip_connect */,
      base::BindOnce(&SmbService::OnMountPreconfiguredShareDone, AsWeakPtr()));
}

void SmbService::OnMountPreconfiguredShareDone(
    SmbMountResult result,
    const base::FilePath& mount_path) {
  LOG_IF(ERROR, result != SmbMountResult::kSuccess)
      << "Error mounting preconfigured share: " << static_cast<int>(result);
}

bool SmbService::IsKerberosEnabledViaPolicy() const {
  return smb_credentials_updater_ &&
         smb_credentials_updater_->IsKerberosEnabled();
}

void SmbService::SetupKerberos(const std::string& account_identifier) {
  SmbProviderClient* client = GetSmbProviderClient();
  if (!client) {
    return;
  }

  client->SetupKerberos(
      account_identifier,
      base::BindOnce(&SmbService::OnSetupKerberosResponse, AsWeakPtr()));
}

void SmbService::UpdateKerberosCredentials(
    const std::string& account_identifier) {
  SmbProviderClient* client = GetSmbProviderClient();
  if (!client) {
    return;
  }

  client->SetupKerberos(
      account_identifier,
      base::BindOnce(&SmbService::OnUpdateKerberosCredentialsResponse,
                     AsWeakPtr()));
}

void SmbService::OnUpdateKerberosCredentialsResponse(bool success) {
  LOG_IF(ERROR, !success) << "Update Kerberos credentials failed.";
}

void SmbService::OnSetupKerberosResponse(bool success) {
  if (!success) {
    LOG(ERROR) << "SmbService: Kerberos setup failed.";
  }

  CompleteSetup();
}

void SmbService::CompleteSetup() {
  share_finder_ = std::make_unique<SmbShareFinder>(GetSmbProviderClient());
  RegisterHostLocators();

  GetProviderService()->RegisterProvider(std::make_unique<SmbProvider>(
      base::BindRepeating(&SmbService::GetMountId, base::Unretained(this)),
      base::BindRepeating(&SmbService::Unmount, base::Unretained(this)),
      base::BindRepeating(&SmbService::RequestCredentials,
                          base::Unretained(this)),
      base::BindRepeating(&SmbService::RequestUpdatedSharePath,
                          base::Unretained(this))));
  RestoreMounts();
  net::NetworkChangeNotifier::AddNetworkChangeObserver(this);
  if (chromeos::PowerManagerClient::Get()) {
    chromeos::PowerManagerClient::Get()->AddObserver(this);
  }

  if (setup_complete_callback_) {
    std::move(setup_complete_callback_).Run();
  }
}

void SmbService::OnSetupCompleteForTesting(base::OnceClosure callback) {
  DCHECK(!setup_complete_callback_);
  if (share_finder_) {
    std::move(callback).Run();
    return;
  }
  setup_complete_callback_ = std::move(callback);
}

void SmbService::SetSmbFsMounterCreationCallbackForTesting(
    SmbFsShare::MounterCreationCallback callback) {
  smbfs_mounter_creation_callback_ = std::move(callback);
}

void SmbService::RegisterHostLocators() {
  if (disable_share_discovery_for_testing_) {
    return;
  }

  SetUpMdnsHostLocator();
  if (IsNetBiosDiscoveryEnabled()) {
    SetUpNetBiosHostLocator();
  } else {
    LOG(WARNING) << "SmbService: NetBios discovery disabled.";
  }
}

void SmbService::SetUpMdnsHostLocator() {
  share_finder_->RegisterHostLocator(std::make_unique<MDnsHostLocator>());
}

void SmbService::SetUpNetBiosHostLocator() {
  auto get_interfaces = base::BindRepeating(&GetInterfaces);
  auto client_factory = base::BindRepeating(&GetNetBiosClient, profile_);

  auto netbios_host_locator = std::make_unique<NetBiosHostLocator>(
      std::move(get_interfaces), std::move(client_factory),
      GetSmbProviderClient());

  share_finder_->RegisterHostLocator(std::move(netbios_host_locator));
}

bool SmbService::IsNetBiosDiscoveryEnabled() const {
  return profile_->GetPrefs()->GetBoolean(prefs::kNetBiosShareDiscoveryEnabled);
}

bool SmbService::IsNTLMAuthenticationEnabled() const {
  return profile_->GetPrefs()->GetBoolean(
      prefs::kNTLMShareAuthenticationEnabled);
}

bool SmbService::IsShareMounted(const SmbUrl& share) const {
  std::vector<ProvidedFileSystemInfo> file_systems =
      GetProviderService()->GetProvidedFileSystemInfoList(provider_id_);

  for (const auto& info : file_systems) {
    base::FilePath share_path =
        GetSharePathFromFileSystemId(info.file_system_id());
    SmbUrl parsed_url(share_path.value());
    DCHECK(parsed_url.IsValid());
    if (parsed_url.ToString() == share.ToString()) {
      return true;
    }
  }

  for (const auto& entry : smbfs_shares_) {
    if (entry.second->share_url().ToString() == share.ToString()) {
      return true;
    }
  }
  return false;
}

std::vector<SmbUrl> SmbService::GetPreconfiguredSharePaths(
    const std::string& policy_mode) const {
  std::vector<SmbUrl> preconfigured_urls;

  const base::Value* preconfigured_shares = profile_->GetPrefs()->GetList(
      prefs::kNetworkFileSharesPreconfiguredShares);

  for (const base::Value& info : preconfigured_shares->GetList()) {
    // |info| is a dictionary with entries for |share_url| and |mode|.
    const base::Value* share_url = info.FindKey(kShareUrlKey);
    const base::Value* mode = info.FindKey(kModeKey);

    if (policy_mode == kModeUnknownValue) {
      // kModeUnknownValue is used to filter for any shares that do not match
      // a presently known mode for preconfiguration. As new preconfigure
      // modes are added, this should be kept in sync.
      if (mode->GetString() != kModeDropDownValue &&
          mode->GetString() != kModePreMountValue) {
        preconfigured_urls.emplace_back(share_url->GetString());
      }

    } else {
      // Filter normally
      if (mode->GetString() == policy_mode) {
        preconfigured_urls.emplace_back(share_url->GetString());
      }
    }
  }
  return preconfigured_urls;
}

void SmbService::RequestCredentials(const std::string& share_path,
                                    int32_t mount_id,
                                    base::OnceClosure reply) {
  smb_dialog::SmbCredentialsDialog::Show(
      base::NumberToString(mount_id), share_path,
      base::BindOnce(&SmbService::OnSmbCredentialsDialogShown, AsWeakPtr(),
                     mount_id, std::move(reply)));
}

void SmbService::OnSmbCredentialsDialogShown(int32_t mount_id,
                                             base::OnceClosure reply,
                                             bool canceled,
                                             const std::string& username,
                                             const std::string& password) {
  if (canceled) {
    return;
  }

  std::string parsed_username = username;
  std::string workgroup;
  ParseUserName(username, &parsed_username, &workgroup);

  GetSmbProviderClient()->UpdateMountCredentials(
      mount_id, workgroup, parsed_username, MakeFdWithContents(password),
      base::BindOnce(
          [](int32_t mount_id, base::OnceClosure reply,
             smbprovider::ErrorType error) {
            if (error == smbprovider::ERROR_OK) {
              std::move(reply).Run();
            } else {
              LOG(ERROR) << "Failed to update the credentials for mount id "
                         << mount_id;
            }
          },
          mount_id, std::move(reply)));
}

std::vector<SmbUrl> SmbService::GetPreconfiguredSharePathsForDropdown() const {
  auto drop_down_paths = GetPreconfiguredSharePaths(kModeDropDownValue);
  auto fallback_paths = GetPreconfiguredSharePaths(kModeUnknownValue);

  for (auto&& fallback_path : fallback_paths) {
    drop_down_paths.push_back(std::move(fallback_path));
  }

  return drop_down_paths;
}

std::vector<SmbUrl> SmbService::GetPreconfiguredSharePathsForPremount() const {
  return GetPreconfiguredSharePaths(kModePreMountValue);
}

void SmbService::RequestUpdatedSharePath(
    const std::string& share_path,
    int32_t mount_id,
    StartReadDirIfSuccessfulCallback reply) {
  if (ShouldRunHostDiscoveryAgain()) {
    previous_host_discovery_time_ = tick_clock_->NowTicks();
    share_finder_->DiscoverHostsInNetwork(
        base::BindOnce(&SmbService::OnHostsDiscoveredForUpdateSharePath,
                       AsWeakPtr(), mount_id, share_path, std::move(reply)));
    return;
  }
  // Host discovery did not run, but try to resolve the hostname in case a
  // previous host discovery found the host.
  SmbUrl resolved_url(share_path);
  if (share_finder_->TryResolveUrl(SmbUrl(share_path), &resolved_url)) {
    UpdateSharePath(mount_id, share_path, std::move(reply));
  } else {
    std::move(reply).Run(false /* should_retry_start_read_dir */);
  }
}

bool SmbService::ShouldRunHostDiscoveryAgain() const {
  return tick_clock_->NowTicks() >
         previous_host_discovery_time_ + kHostDiscoveryInterval;
}

void SmbService::OnNetworkChanged(
    net::NetworkChangeNotifier::ConnectionType type) {
  // Run host discovery to refresh list of cached hosts for subsequent name
  // resolution attempts.
  share_finder_->DiscoverHostsInNetwork(base::DoNothing()
                                        /* HostDiscoveryResponse */);
}

void SmbService::RecordMountCount() const {
  const std::vector<ProvidedFileSystemInfo> file_systems =
      GetProviderService()->GetProvidedFileSystemInfoList(provider_id_);
  UMA_HISTOGRAM_COUNTS_100("NativeSmbFileShare.MountCount",
                           file_systems.size() + smbfs_shares_.size());
}

void SmbService::SuspendImminent(
    power_manager::SuspendImminent::Reason reason) {
  for (auto it = smbfs_shares_.begin(); it != smbfs_shares_.end(); ++it) {
    SmbFsShare* share = it->second.get();

    // For each share, block suspend until the unmount has completed, to ensure
    // that no smbfs instances are active when the system goes to sleep.
    auto token = base::UnguessableToken::Create();
    chromeos::PowerManagerClient::Get()->BlockSuspend(token, "SmbService");
    share->Unmount(
        base::BindOnce(&SmbService::OnSuspendUnmountDone, AsWeakPtr(), token));
  }
}

void SmbService::OnSuspendUnmountDone(
    base::UnguessableToken power_manager_suspend_token,
    chromeos::MountError result) {
  LOG_IF(ERROR, result != chromeos::MountError::MOUNT_ERROR_NONE)
      << "Could not unmount smbfs share during suspension: "
      << static_cast<int>(result);
  // Regardless of the outcome, unblock suspension for this share.
  chromeos::PowerManagerClient::Get()->UnblockSuspend(
      power_manager_suspend_token);
}

void SmbService::SuspendDone(const base::TimeDelta& sleep_duration) {
  // Don't iterate directly over the share map during the remount
  // process as shares can be removed on failure in OnSmbfsMountDone.
  std::vector<std::string> mount_ids;
  for (const auto& s : smbfs_shares_)
    mount_ids.push_back(s.first);

  for (const auto& mount_id : mount_ids) {
    auto share_it = smbfs_shares_.find(mount_id);
    if (share_it == smbfs_shares_.end()) {
      LOG(WARNING) << "Smbfs mount id " << mount_id
                   << " no longer present during remount after suspend";
      continue;
    }
    SmbFsShare* share = share_it->second.get();

    // Don't try to reconnect as we race the network stack in getting an IP
    // address.
    SmbFsShare::MountOptions options = share->options();
    options.skip_connect = true;
    // Observing power management changes from SmbService allows us to remove
    // the share in OnSmbfsMountDone if remount fails.
    share->Remount(
        options, base::BindOnce(
                     &SmbService::OnSmbfsMountDone, AsWeakPtr(), mount_id,
                     base::BindOnce([](SmbMountResult result,
                                       const base::FilePath& mount_path) {
                       LOG_IF(ERROR, result != SmbMountResult::kSuccess)
                           << "Error remounting smbfs share after suspension: "
                           << static_cast<int>(result);
                     })));
  }
}

}  // namespace smb_client
}  // namespace chromeos