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// Copyright (c) 2011 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 <utility>
#include <vector>
#include "base/gtest_prod_util.h"
#include "base/memory/ref_counted.h"
#include "base/memory/singleton.h"
#include "base/strings/string16.h"
#include "base/timer/timer.h"
#include "content/public/browser/browser_thread.h"
#include "url/gurl.h"
class EnumerateModulesModel;
namespace base {
class FilePath;
class ListValue;
// A helper class that implements the enumerate module functionality on the File
// thread.
class ModuleEnumerator : public base::RefCountedThreadSafe<ModuleEnumerator> {
// What type of module we are dealing with. Loaded modules are modules we
// detect as loaded in the process at the time of scanning. The others are
// modules of interest and may or may not be loaded in the process at the
// time of scan.
enum ModuleType {
// The blacklist status of the module. Suspected Bad modules have been
// partially matched (ie. name matches and location, but not description)
// whereas Confirmed Bad modules have been identified further (ie.
// AuthentiCode signer matches).
enum ModuleStatus {
// This is returned by the matching function when comparing against the
// blacklist and the module does not match the current entry in the
// blacklist.
// The module is not on the blacklist. Assume it is good.
// Module is a suspected bad module.
// Module is a bad bad dog.
// A bitmask with the possible resolutions for bad modules.
enum RecommendedAction {
NONE = 0,
UNINSTALL = 1 << 1,
DISABLE = 1 << 2,
UPDATE = 1 << 3,
SEE_LINK = 1 << 4,
NOTIFY_USER = 1 << 5,
// Which Windows OS is affected.
enum OperatingSystem {
ALL = -1,
XP = 1 << 0,
// The structure we populate when enumerating modules.
struct Module {
// The type of module found
ModuleType type;
// The module status (benign/bad/etc).
ModuleStatus status;
// The module path, not including filename.
base::string16 location;
// The name of the module (filename).
base::string16 name;
// The name of the product the module belongs to.
base::string16 product_name;
// The module file description.
base::string16 description;
// The module version.
base::string16 version;
// The signer of the digital certificate for the module.
base::string16 digital_signer;
// The help tips bitmask.
RecommendedAction recommended_action;
// The duplicate count within each category of modules.
int duplicate_count;
// Whether this module has been normalized (necessary before checking it
// against blacklist).
bool normalized;
// A vector typedef of all modules enumerated.
typedef std::vector<Module> ModulesVector;
// A structure we populate with the blacklist entries.
struct BlacklistEntry {
const char* filename;
const char* location;
const char* desc_or_signer;
const char* version_from; // Version where conflict started.
const char* version_to; // First version that works.
OperatingSystem os; // Bitmask, representing what OS this entry applies to.
RecommendedAction help_tip;
// A static function that normalizes the module information in the |module|
// struct. Module information needs to be normalized before comparing against
// the blacklist. This is because the same module can be described in many
// different ways, ie. file paths can be presented in long/short name form,
// and are not case sensitive on Windows. Also, the version string returned
// can include appended text, which we don't want to use during comparison
// against the blacklist.
static void NormalizeModule(Module* module);
// A static function that checks whether |module| has been |blacklisted|.
static ModuleStatus Match(const Module& module,
const BlacklistEntry& blacklisted);
explicit ModuleEnumerator(EnumerateModulesModel* observer);
// Start scanning the loaded module list (if a scan is not already in
// progress). This function does not block while reading the module list
// (unless we are in limited_mode, see below), and will notify when done
// through the MODULE_LIST_ENUMERATED notification.
// The process will also send MODULE_INCOMPATIBILITY_BADGE_CHANGE to let
// observers know when it is time to update the wrench menu badge.
// When in |limited_mode|, this function will not leverage the File thread
// to run asynchronously and will therefore block until scanning is done
// (and will also not send out any notifications).
void ScanNow(ModulesVector* list, bool limited_mode);
FRIEND_TEST_ALL_PREFIXES(EnumerateModulesTest, CollapsePath);
// The (currently) hard coded blacklist of known bad modules.
static const BlacklistEntry kModuleBlacklist[];
// This function does the actual file scanning work on the FILE thread (or
// block the main thread when in limited_mode). It enumerates all loaded
// modules in the process and other modules of interest, such as the
// registered Winsock LSP modules and stores them in |enumerated_modules_|.
// It then normalizes the module info and matches them against a blacklist
// of known bad modules. Finally, it calls ReportBack to let the observer
// know we are done.
void ScanImpl();
// Enumerate all modules loaded into the Chrome process.
void EnumerateLoadedModules();
// Enumerate all registered Windows shell extensions.
void EnumerateShellExtensions();
// Enumerate all registered Winsock LSP modules.
void EnumerateWinsockModules();
// Reads the registered shell extensions found under |parent| key in the
// registry.
void ReadShellExtensions(HKEY parent);
// Given a |module|, initializes the structure and loads additional
// information using the location field of the module.
void PopulateModuleInformation(Module* module);
// Checks the module list to see if a |module| of the same type, location
// and name has been added before and if so, increments its duplication
// counter. If it doesn't appear in the list, it is added.
void AddToListWithoutDuplicating(const Module&);
// Builds up a vector of path values mapping to environment variable,
// with pairs like [c:\windows\, %systemroot%]. This is later used to
// collapse paths like c:\windows\system32 into %systemroot%\system32, which
// we can use for comparison against our blacklist (which uses only env vars).
// NOTE: The vector will not contain an exhaustive list of environment
// variables, only the ones currently found on the blacklist or ones that are
// likely to appear there.
void PreparePathMappings();
// For a given |module|, collapse the path from c:\windows to %systemroot%,
// based on the |path_mapping_| vector.
void CollapsePath(Module* module);
// Takes each module in the |enumerated_modules_| vector and matches it
// against a fixed blacklist of bad and suspected bad modules.
void MatchAgainstBlacklist();
// This function executes on the UI thread when the scanning and matching
// process is done. It notifies the observer.
void ReportBack();
// Given a filename, returns the Subject (who signed it) retrieved from
// the digital signature (Authenticode).
base::string16 GetSubjectNameFromDigitalSignature(
const base::FilePath& filename);
// The typedef for the vector that maps a regular file path to %env_var%.
typedef std::vector< std::pair<base::string16, base::string16> > PathMapping;
// The vector of paths to %env_var%, used to account for differences in
// where people keep there files, c:\windows vs. d:\windows, etc.
PathMapping path_mapping_;
// The vector containing all the enumerated modules (loaded and modules of
// interest).
ModulesVector* enumerated_modules_;
// The observer, who needs to be notified when we are done.
EnumerateModulesModel* observer_;
// See limited_mode below.
bool limited_mode_;
// The thread that we need to call back on to report that we are done.
content::BrowserThread::ID callback_thread_id_;
// This is a singleton class that enumerates all modules loaded into Chrome,
// both currently loaded modules (called DLLs on Windows) and modules 'of
// interest', such as WinSock LSP modules. This class also marks each module
// as benign or suspected bad or outright bad, using a supplied blacklist that
// is currently hard-coded.
// To use this class, grab the singleton pointer and call ScanNow().
// Then wait to get notified through MODULE_LIST_ENUMERATED when the list is
// ready.
// This class can be used on the UI thread as it asynchronously offloads the
// file work over to the FILE thread and reports back to the caller with a
// notification.
class EnumerateModulesModel {
// UMA histogram constants.
enum UmaModuleConflictHistogramOptions {
ACTION_BOUNDARY, // Must be the last value.
static EnumerateModulesModel* GetInstance();
// Returns true if we should show the conflict notification. The conflict
// notification is only shown once during the lifetime of the process.
bool ShouldShowConflictWarning() const;
// Called when the user has acknowledged the conflict notification.
void AcknowledgeConflictNotification();
// Returns the number of suspected bad modules found in the last scan.
// Returns 0 if no scan has taken place yet.
int suspected_bad_modules_detected() const {
return suspected_bad_modules_detected_;
// Returns the number of confirmed bad modules found in the last scan.
// Returns 0 if no scan has taken place yet.
int confirmed_bad_modules_detected() const {
return confirmed_bad_modules_detected_;
// Returns how many modules to notify the user about.
int modules_to_notify_about() const {
return modules_to_notify_about_;
// Set to true when we the scanning process can not rely on certain Chrome
// services to exists.
void set_limited_mode(bool limited_mode) {
limited_mode_ = limited_mode;
// Checks to see if a scanning task should be started and sets one off, if so.
void MaybePostScanningTask();
// Asynchronously start the scan for the loaded module list, except when in
// limited_mode (in which case it blocks).
void ScanNow();
// Gets the whole module list as a ListValue.
base::ListValue* GetModuleList() const;
// Gets the Help Center URL for the first *notable* conflict module that we've
// elected to notify the user about.
GURL GetFirstNotableConflict();
friend struct DefaultSingletonTraits<EnumerateModulesModel>;
friend class ModuleEnumerator;
virtual ~EnumerateModulesModel();
// Called on the UI thread when the helper class is done scanning.
void DoneScanning();
// Constructs a Help Center article URL for help with a particular module.
// The module must have the SEE_LINK attribute for |recommended_action| set,
// otherwise this returns a blank string.
GURL ConstructHelpCenterUrl(const ModuleEnumerator::Module& module) const;
// The vector containing all the modules enumerated. Will be normalized and
// any bad modules will be marked.
ModuleEnumerator::ModulesVector enumerated_modules_;
// The object responsible for enumerating the modules on the File thread.
scoped_refptr<ModuleEnumerator> module_enumerator_;
// When this singleton object is constructed we go and fire off this timer to
// start scanning for modules after a certain amount of time has passed.
base::OneShotTimer<EnumerateModulesModel> check_modules_timer_;
// While normally |false|, this mode can be set to indicate that the scanning
// process should not rely on certain services normally available to Chrome,
// such as the resource bundle and the notification system, not to mention
// having multiple threads. This mode is useful during diagnostics, which
// runs without firing up all necessary Chrome services first.
bool limited_mode_;
// True if we are currently scanning for modules.
bool scanning_;
// Whether the conflict notification has been acknowledged by the user.
bool conflict_notification_acknowledged_;
// The number of confirmed bad modules (not including suspected bad ones)
// found during last scan.
int confirmed_bad_modules_detected_;
// The number of bad modules the user needs to be aggressively notified about.
int modules_to_notify_about_;
// The number of suspected bad modules (not including confirmed bad ones)
// found during last scan.
int suspected_bad_modules_detected_;