[Win] Add option to reauthenticate the OS user before revealing passwords.

chrome/browser/password_manager/password_manager_util_win.cc

+// Copyright (c) 2013 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.
+
+// windows.h must be first otherwise Win8 SDK breaks.
+#include <windows.h>
+#include <ntsecapi.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 "base/strings/utf_string_conversions.h"
+#include "grit/chromium_strings.h"
+#include "grit/generated_resources.h"
+#include "ui/base/l10n/l10n_util.h"
+
+#define PASSWORD_MANAGER_MAX_PASSWORD_TRIES 3
+
+namespace password_manager_util {
+
+bool AuthenticateUser() {
+  bool retval = false;
+  CREDUI_INFO cui = {};
+  WCHAR username[CREDUI_MAX_USERNAME_LENGTH+1] = {};
+  WCHAR displayname[CREDUI_MAX_USERNAME_LENGTH+1] = {};
+  WCHAR password[CREDUI_MAX_PASSWORD_LENGTH+1] = {};
+  DWORD username_length = CREDUI_MAX_USERNAME_LENGTH;
+  std::wstring product_name =
+      UTF16ToWide(l10n_util::GetStringUTF16(IDS_PRODUCT_NAME));
+  std::wstring password_prompt =
+      UTF16ToWide(l10n_util::GetStringUTF16(
+                  IDS_PASSWORDS_PAGE_AUTHENTICATION_PROMPT));
+  HANDLE handle = INVALID_HANDLE_VALUE;
+  int tries = 0;
+  bool use_displayname = false;
+  bool use_principalname = false;
+  DWORD logon_result = 0;
+
+  // On a domain, we obtain the User Principal Name
+  // for domain authentication.
+  if (GetUserNameEx(NameUserPrincipal, username, &username_length)) {
+    use_principalname = true;
+  } else {
+    username_length = CREDUI_MAX_USERNAME_LENGTH;
+    // Otherwise, we're a workstation, use the plain local username.
+    if (!GetUserName(username, &username_length)) {
+      DLOG(ERROR) << "Unable to obtain username " << GetLastError();
+      return false;
+    } else {
+      // As we are on a workstation, it's possible the user
+      // has no password, so check here.
+      logon_result = LogonUser(username,
+                               L".",
+                               L"",
+                               LOGON32_LOGON_NETWORK,
+                               LOGON32_PROVIDER_DEFAULT,
+                               &handle);
+      // Windows XP and above return ERROR_ACCOUNT_RESTRICTION for
+      // when the password is blank, so check for that here.
+      // See http://support.microsoft.com/kb/303846.
+      if (logon_result || GetLastError() == ERROR_ACCOUNT_RESTRICTION) {
+        SecureZeroMemory(username, sizeof(username));
+        if (logon_result)
+          CloseHandle(handle);
+        return true;
+      }
+    }
+  }
+
+  // Try and obtain a friendly display name.
+  username_length = CREDUI_MAX_USERNAME_LENGTH;
+  if (GetUserNameEx(NameDisplay, displayname, &username_length)) {
+    use_displayname = true;
+  }
+
+  cui.cbSize = sizeof(CREDUI_INFO);
+  cui.hwndParent = NULL;
+  cui.pszMessageText = password_prompt.c_str();
+  cui.pszCaptionText = product_name.c_str();
+
+  cui.hbmBanner = NULL;
+  BOOL save_password = FALSE;
+  DWORD credErr = NO_ERROR;
+  DWORD flags = CREDUI_FLAGS_GENERIC_CREDENTIALS |
+                CREDUI_FLAGS_EXCLUDE_CERTIFICATES |
+                CREDUI_FLAGS_KEEP_USERNAME |
+                CREDUI_FLAGS_ALWAYS_SHOW_UI |
+                CREDUI_FLAGS_DO_NOT_PERSIST;
+
+  do {
+    SecureZeroMemory(password, sizeof(password));
+    tries++;
+
+   // TODO(wfh) Make sure we support smart cards here.
+    credErr = CredUIPromptForCredentials(
+                  &cui,
+                  product_name.c_str(),
+                  NULL,
+                  0,
+                  use_displayname ? displayname : username,
+                  CREDUI_MAX_USERNAME_LENGTH+1,
+                  password,
+                  CREDUI_MAX_PASSWORD_LENGTH+1,
+                  &save_password,
+                  flags | (tries > 1 ? CREDUI_FLAGS_INCORRECT_PASSWORD : 0));
+
+    if (credErr == NO_ERROR) {
+      logon_result = LogonUser(username,
+                               use_principalname ? NULL : L".",
+                               password,
+                               LOGON32_LOGON_NETWORK,
+                               LOGON32_PROVIDER_DEFAULT,
+                               &handle);
+      if (logon_result) {
+          retval = true;
+        CloseHandle(handle);
+      } else {
+        if (GetLastError() == ERROR_ACCOUNT_RESTRICTION &&
+            wcslen(password) == 0) {
+          // Password is blank, so permit.
+          retval = true;
+        } else {
+          DLOG(WARNING) << "Unable to authenticate " << GetLastError();
+        }
+      }
+    }
+  } while (credErr == NO_ERROR &&
+           (retval == false && tries < PASSWORD_MANAGER_MAX_PASSWORD_TRIES));
+
+  SecureZeroMemory(displayname, sizeof(displayname));
+  SecureZeroMemory(username, sizeof(username));
+  SecureZeroMemory(password, sizeof(password));
+
+  return retval;
+}
+
+}  // namespace password_manager_util