// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
// windows.h must be first otherwise Win8 SDK breaks.
#include <windows.h>
#include <LM.h>
#include <ntsecapi.h>
#include <stddef.h>
#include <stdint.h>
#include <wincred.h>
// SECURITY_WIN32 must be defined in order to get
// EXTENDED_NAME_FORMAT enumeration.
#define SECURITY_WIN32 1
#include <security.h>
#undef SECURITY_WIN32
#include <optional>
#include "base/containers/heap_array.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/hang_watcher.h"
#include "base/threading/scoped_thread_priority.h"
#include "base/time/time.h"
#include "base/win/win_util.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/password_manager/password_manager_util_win.h"
#include "chrome/grit/branded_strings.h"
#include "components/password_manager/core/browser/password_manager.h"
#include "components/password_manager/core/common/password_manager_pref_names.h"
#include "components/prefs/pref_service.h"
#include "ui/aura/window.h"
#include "ui/aura/window_tree_host.h"
#include "ui/base/l10n/l10n_util.h"
namespace password_manager_util_win {
namespace {
const unsigned kMaxPasswordRetries = 3;
struct PasswordCheckPrefs {
void Read(PrefService* local_state);
void Write(PrefService* local_state);
int64_t pref_last_changed = 0;
bool blank_password = false;
};
// Validates whether a credential buffer contains the credentials for the
// currently signed in user.
class CredentialBufferValidator {
public:
CredentialBufferValidator();
CredentialBufferValidator(const CredentialBufferValidator&) = delete;
CredentialBufferValidator& operator=(const CredentialBufferValidator&) =
delete;
~CredentialBufferValidator();
// Returns ERROR_SUCCESS if the credential buffer given matches the
// credentials of the user running Chrome. Otherwise an error describing
// the issue.
DWORD IsValid(ULONG auth_package, void* cred_buffer, ULONG cred_length);
private:
std::optional<base::HeapArray<uint8_t>> GetTokenInformation(HANDLE token);
// Name of app calling LsaLogonUser(). In this case, "chrome".
LSA_STRING name_;
// Handle to LSA server.
HANDLE lsa_ = INVALID_HANDLE_VALUE;
// Buffer holding information about the current process token.
std::optional<base::HeapArray<uint8_t>> cur_token_info_;
};
CredentialBufferValidator::CredentialBufferValidator() {
// Windows 7 does not support pseudo tokens with GetTokenInformation(), so
// make sure to open a real token.
HANDLE token;
if (!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &token)) {
DLOG(ERROR) << "Unable to obtain process token " << GetLastError();
return;
}
cur_token_info_ = GetTokenInformation(token);
CloseHandle(token);
if (!cur_token_info_) {
DLOG(ERROR) << "Unable to obtain current token info " << GetLastError();
return;
}
NTSTATUS sts = LsaConnectUntrusted(&lsa_);
if (sts != ERROR_SUCCESS) {
lsa_ = INVALID_HANDLE_VALUE;
return;
}
name_.Buffer = const_cast<PCHAR>("Chrome");
name_.Length = strlen(name_.Buffer);
name_.MaximumLength = name_.Length + 1;
}
CredentialBufferValidator::~CredentialBufferValidator() {
if (lsa_ != INVALID_HANDLE_VALUE) {
LsaDeregisterLogonProcess(lsa_);
}
}
DWORD CredentialBufferValidator::IsValid(ULONG auth_package,
void* auth_buffer,
ULONG auth_length) {
if (lsa_ == INVALID_HANDLE_VALUE) {
return ERROR_LOGON_FAILURE;
}
NTSTATUS sts;
NTSTATUS substs;
TOKEN_SOURCE source;
void* profile_buffer = nullptr;
ULONG profile_buffer_length = 0;
QUOTA_LIMITS limits;
LUID luid;
HANDLE token = INVALID_HANDLE_VALUE;
strcpy_s(source.SourceName, std::size(source.SourceName), "Chrome");
if (!AllocateLocallyUniqueId(&source.SourceIdentifier)) {
return GetLastError();
}
sts = LsaLogonUser(lsa_, &name_, Interactive, auth_package, auth_buffer,
auth_length, nullptr, &source, &profile_buffer,
&profile_buffer_length, &luid, &token, &limits, &substs);
LsaFreeReturnBuffer(profile_buffer);
std::optional<base::HeapArray<uint8_t>> logon_token_info =
GetTokenInformation(token);
CloseHandle(token);
if (sts != S_OK) {
return LsaNtStatusToWinError(sts);
}
if (!logon_token_info) {
return ERROR_NOT_ENOUGH_MEMORY;
}
PSID cur_sid =
reinterpret_cast<TOKEN_USER*>(cur_token_info_->data())->User.Sid;
PSID logon_sid =
reinterpret_cast<TOKEN_USER*>(logon_token_info->data())->User.Sid;
return EqualSid(cur_sid, logon_sid) ? ERROR_SUCCESS : ERROR_LOGON_FAILURE;
}
std::optional<base::HeapArray<uint8_t>>
CredentialBufferValidator::GetTokenInformation(HANDLE token) {
DWORD token_info_length = 0;
::GetTokenInformation(token, TokenUser, nullptr, 0, &token_info_length);
if (ERROR_INSUFFICIENT_BUFFER != GetLastError()) {
return std::nullopt;
}
auto token_info_buffer =
base::HeapArray<uint8_t>::WithSize(token_info_length);
if (!::GetTokenInformation(token, TokenUser, token_info_buffer.data(),
token_info_length, &token_info_length)) {
return std::nullopt;
}
return token_info_buffer;
}
void PasswordCheckPrefs::Read(PrefService* local_state) {
blank_password =
local_state->GetBoolean(password_manager::prefs::kOsPasswordBlank);
pref_last_changed =
local_state->GetInt64(password_manager::prefs::kOsPasswordLastChanged);
}
void PasswordCheckPrefs::Write(PrefService* local_state) {
local_state->SetBoolean(password_manager::prefs::kOsPasswordBlank,
blank_password);
local_state->SetInt64(password_manager::prefs::kOsPasswordLastChanged,
pref_last_changed);
}
int64_t GetPasswordLastChanged(const WCHAR* username) {
// Mitigate the issues caused by loading DLLs on a background thread
// (http://crbug/973868).
SCOPED_MAY_LOAD_LIBRARY_AT_BACKGROUND_PRIORITY();
LPUSER_INFO_1 user_info = nullptr;
DWORD age = 0;
NET_API_STATUS ret = NetUserGetInfo(nullptr, username, 1,
reinterpret_cast<LPBYTE*>(&user_info));
if (ret == NERR_Success) {
// Returns seconds since last password change.
age = user_info->usri1_password_age;
NetApiBufferFree(user_info);
} else {
return -1;
}
base::Time changed = base::Time::Now() - base::Seconds(age);
return changed.ToInternalValue();
}
bool CheckBlankPasswordWithPrefs(const WCHAR* username,
PasswordCheckPrefs* prefs) {
// If the user name has a backslash, then it is of the form DOMAIN\username.
// NetUserGetInfo() (called from GetPasswordLastChanged()) as well as
// LogonUser() below only wants the username portion.
LPCWSTR backslash = wcschr(username, L'\\');
if (backslash) {
username = backslash + 1;
}
int64_t last_changed = GetPasswordLastChanged(username);
// If we cannot determine when the password was last changed
// then assume the password is not blank
if (last_changed == -1) {
return false;
}
bool blank_password = prefs->blank_password;
bool need_recheck = true;
if (prefs->pref_last_changed > 0 &&
last_changed <= prefs->pref_last_changed) {
need_recheck = false;
}
if (need_recheck) {
// Mitigate the issues caused by loading DLLs on a background thread
// (http://crbug/973868).
SCOPED_MAY_LOAD_LIBRARY_AT_BACKGROUND_PRIORITY();
HANDLE handle = INVALID_HANDLE_VALUE;
// Attempt to login using blank password.
DWORD logon_result =
LogonUser(username, L".", L"", LOGON32_LOGON_INTERACTIVE,
LOGON32_PROVIDER_DEFAULT, &handle);
auto last_error = GetLastError();
// Win XP and later return ERROR_ACCOUNT_RESTRICTION for blank password.
if (logon_result) {
CloseHandle(handle);
}
// In the case the password is blank, then LogonUser returns a failure,
// handle is INVALID_HANDLE_VALUE, and GetLastError() is
// ERROR_ACCOUNT_RESTRICTION.
// http://msdn.microsoft.com/en-us/library/windows/desktop/ms681385
blank_password = (logon_result || last_error == ERROR_ACCOUNT_RESTRICTION);
}
// Account for clock skew between pulling the password age and
// writing to the preferences by adding a small skew factor here.
last_changed += base::Time::kMicrosecondsPerSecond;
// Update the preferences with new values.
prefs->pref_last_changed = last_changed;
prefs->blank_password = blank_password;
return blank_password;
}
// Wrapper around CheckBlankPasswordWithPrefs to be called on UI thread.
bool CheckBlankPassword(const WCHAR* username) {
PrefService* local_state = g_browser_process->local_state();
PasswordCheckPrefs prefs;
prefs.Read(local_state);
bool result = CheckBlankPasswordWithPrefs(username, &prefs);
prefs.Write(local_state);
return result;
}
// Returns true if there is device authentication present on the machine, false
// otherwise.
bool DeviceAuthenticationPresent(const WCHAR* username) {
// If the machine is domain-joined, we should not check whether the password
// is blank and we should assume there is a password and thus there is device
// authentication present. Otherwise, if there is a non-blank password, also
// return that there is device authentication present.
return base::win::IsEnrolledToDomain() || !CheckBlankPassword(username);
}
} // namespace
bool AuthenticateUser(gfx::NativeWindow window,
const std::u16string& password_prompt) {
bool retval = false;
WCHAR cur_username[CREDUI_MAX_USERNAME_LENGTH + 1] = {};
DWORD cur_username_length = std::size(cur_username);
// If this is a standlone workstation, it's possible the current user has no
// password, so check here and allow it.
if (!GetUserNameEx(NameSamCompatible, cur_username, &cur_username_length)) {
DLOG(ERROR) << "Unable to obtain username " << GetLastError();
return false;
}
// If there is no device authentication set up on the machine, then
// automatically authenticate the user.
if (!DeviceAuthenticationPresent(cur_username)) {
return true;
}
// Build the strings to display in the credential UI. If these strings are
// left empty on domain joined machines, CredUIPromptForWindowsCredentials()
// fails to run.
std::u16string product_name = l10n_util::GetStringUTF16(IDS_PRODUCT_NAME);
CREDUI_INFO cui;
cui.cbSize = sizeof(cui);
cui.hwndParent = window->GetHost()->GetAcceleratedWidget();
cui.pszMessageText = base::as_wcstr(password_prompt);
cui.pszCaptionText = base::as_wcstr(product_name);
cui.hbmBanner = nullptr;
// Never consider the current scope as hung. The hang watching deadline (if
// any) is not valid since the user can take unbounded time to answer the
// password prompt (http://crbug.com/806174)
base::HangWatcher::InvalidateActiveExpectations();
CredentialBufferValidator validator;
DWORD err = 0;
size_t tries = 0;
do {
tries++;
// Show credential prompt, displaying error from previous try if needed.
// TODO(wfh): Make sure we support smart cards here.
ULONG auth_package = 0;
LPVOID cred_buffer = nullptr;
ULONG cred_buffer_size = 0;
err = CredUIPromptForWindowsCredentials(
&cui, err, &auth_package, nullptr, 0, &cred_buffer, &cred_buffer_size,
nullptr, CREDUIWIN_ENUMERATE_CURRENT_USER);
if (err != ERROR_SUCCESS) {
break;
}
// While CredUIPromptForWindowsCredentials() shows the currently logged
// on user by default, it can be changed at runtime. This is important,
// as it allows users to change to a different type of authentication
// mechanism, such as PIN or smartcard. However, this also allows the
// user to change to a completely different account on the machine. Make
// sure the user authenticated with the credentials of the currently
// logged on user.
err = validator.IsValid(auth_package, cred_buffer, cred_buffer_size);
retval = err == ERROR_SUCCESS;
} while (!retval && tries < kMaxPasswordRetries);
return retval;
}
bool CanAuthenticateWithScreenLock() {
WCHAR cur_username[CREDUI_MAX_USERNAME_LENGTH + 1] = {};
DWORD cur_username_length = std::size(cur_username);
if (!GetUserNameEx(NameSamCompatible, cur_username, &cur_username_length)) {
DLOG(ERROR) << "Unable to obtain username " << GetLastError();
return false;
}
return DeviceAuthenticationPresent(cur_username);
}
} // namespace password_manager_util_win
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