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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "chrome/browser/metrics/extensions_metrics_provider.h"
      6 
      7 #include <algorithm>
      8 #include <set>
      9 #include <vector>
     10 
     11 #include "base/logging.h"
     12 #include "base/memory/scoped_ptr.h"
     13 #include "base/strings/stringprintf.h"
     14 #include "chrome/browser/browser_process.h"
     15 #include "chrome/browser/extensions/install_verifier.h"
     16 #include "chrome/browser/profiles/profile_manager.h"
     17 #include "components/metrics/metrics_log.h"
     18 #include "components/metrics/metrics_state_manager.h"
     19 #include "components/metrics/proto/system_profile.pb.h"
     20 #include "extensions/browser/extension_registry.h"
     21 #include "extensions/browser/extension_system.h"
     22 #include "extensions/common/extension_set.h"
     23 #include "third_party/smhasher/src/City.h"
     24 
     25 namespace {
     26 
     27 // The number of possible hash keys that a client may use.  The UMA client_id
     28 // value is reduced modulo this value to produce the key used by that
     29 // particular client.
     30 const size_t kExtensionListClientKeys = 4096;
     31 
     32 // The number of hash buckets into which extension IDs are mapped.  This sets
     33 // the possible output range of the HashExtension function.
     34 const size_t kExtensionListBuckets = 1024;
     35 
     36 // Possible states for extensions. The order of these enum values is important,
     37 // and is used when combining the state of multiple extensions and multiple
     38 // profiles. Combining two states should always result in the higher state.
     39 // Ex: One profile is in state FROM_STORE_VERIFIED, and another is in
     40 // FROM_STORE_UNVERIFIED. The state of the two profiles together will be
     41 // FROM_STORE_UNVERIFIED.
     42 // This enum should be kept in sync with the corresponding enum in
     43 // components/metrics/proto/system_profile.proto
     44 enum ExtensionState {
     45   NO_EXTENSIONS,
     46   FROM_STORE_VERIFIED,
     47   FROM_STORE_UNVERIFIED,
     48   OFF_STORE
     49 };
     50 
     51 metrics::SystemProfileProto::ExtensionsState ExtensionStateAsProto(
     52     ExtensionState value) {
     53   switch (value) {
     54     case NO_EXTENSIONS:
     55       return metrics::SystemProfileProto::NO_EXTENSIONS;
     56     case FROM_STORE_VERIFIED:
     57       return metrics::SystemProfileProto::NO_OFFSTORE_VERIFIED;
     58     case FROM_STORE_UNVERIFIED:
     59       return metrics::SystemProfileProto::NO_OFFSTORE_UNVERIFIED;
     60     case OFF_STORE:
     61       return metrics::SystemProfileProto::HAS_OFFSTORE;
     62   }
     63   NOTREACHED();
     64   return metrics::SystemProfileProto::NO_EXTENSIONS;
     65 }
     66 
     67 // Determines if the |extension| is an extension (can use extension APIs) and is
     68 // not from the webstore. If local information claims the extension is from the
     69 // webstore, we attempt to verify with |verifier| by checking if it has been
     70 // explicitly deemed invalid. If |verifier| is inactive or if the extension is
     71 // unknown to |verifier|, the local information is trusted.
     72 ExtensionState IsOffStoreExtension(
     73     const extensions::Extension& extension,
     74     const extensions::InstallVerifier& verifier) {
     75   if (!extension.is_extension() && !extension.is_legacy_packaged_app())
     76     return NO_EXTENSIONS;
     77 
     78   // Component extensions are considered safe.
     79   if (extensions::Manifest::IsComponentLocation(extension.location()))
     80     return NO_EXTENSIONS;
     81 
     82   if (verifier.AllowedByEnterprisePolicy(extension.id()))
     83     return NO_EXTENSIONS;
     84 
     85   if (!extensions::InstallVerifier::IsFromStore(extension))
     86     return OFF_STORE;
     87 
     88   // Local information about the extension implies it is from the store. We try
     89   // to use the install verifier to verify this.
     90   if (!verifier.IsKnownId(extension.id()))
     91     return FROM_STORE_UNVERIFIED;
     92 
     93   if (verifier.IsInvalid(extension.id()))
     94     return OFF_STORE;
     95 
     96   return FROM_STORE_VERIFIED;
     97 }
     98 
     99 // Finds the ExtensionState of |extensions|. The return value will be the
    100 // highest (as defined by the order of ExtensionState) value of each extension
    101 // in |extensions|.
    102 ExtensionState CheckForOffStore(const extensions::ExtensionSet& extensions,
    103                                 const extensions::InstallVerifier& verifier) {
    104   ExtensionState state = NO_EXTENSIONS;
    105   for (extensions::ExtensionSet::const_iterator it = extensions.begin();
    106        it != extensions.end() && state < OFF_STORE;
    107        ++it) {
    108     // Combine the state of each extension, always favoring the higher state as
    109     // defined by the order of ExtensionState.
    110     state = std::max(state, IsOffStoreExtension(**it, verifier));
    111   }
    112   return state;
    113 }
    114 
    115 }  // namespace
    116 
    117 ExtensionsMetricsProvider::ExtensionsMetricsProvider(
    118     metrics::MetricsStateManager* metrics_state_manager)
    119     : metrics_state_manager_(metrics_state_manager), cached_profile_(NULL) {
    120   DCHECK(metrics_state_manager_);
    121 }
    122 
    123 ExtensionsMetricsProvider::~ExtensionsMetricsProvider() {
    124 }
    125 
    126 // static
    127 int ExtensionsMetricsProvider::HashExtension(const std::string& extension_id,
    128                                              uint32 client_key) {
    129   DCHECK_LE(client_key, kExtensionListClientKeys);
    130   std::string message =
    131       base::StringPrintf("%u:%s", client_key, extension_id.c_str());
    132   uint64 output = CityHash64(message.data(), message.size());
    133   return output % kExtensionListBuckets;
    134 }
    135 
    136 Profile* ExtensionsMetricsProvider::GetMetricsProfile() {
    137   ProfileManager* profile_manager = g_browser_process->profile_manager();
    138   if (!profile_manager)
    139     return NULL;
    140 
    141   // If there is a cached profile, reuse that.  However, check that it is still
    142   // valid first.
    143   if (cached_profile_ && profile_manager->IsValidProfile(cached_profile_))
    144     return cached_profile_;
    145 
    146   // Find a suitable profile to use, and cache it so that we continue to report
    147   // statistics on the same profile.  We would simply use
    148   // ProfileManager::GetLastUsedProfile(), except that that has the side effect
    149   // of creating a profile if it does not yet exist.
    150   cached_profile_ = profile_manager->GetProfileByPath(
    151       profile_manager->GetLastUsedProfileDir(profile_manager->user_data_dir()));
    152   if (cached_profile_) {
    153     // Ensure that the returned profile is not an incognito profile.
    154     cached_profile_ = cached_profile_->GetOriginalProfile();
    155   }
    156   return cached_profile_;
    157 }
    158 
    159 scoped_ptr<extensions::ExtensionSet>
    160 ExtensionsMetricsProvider::GetInstalledExtensions(Profile* profile) {
    161   if (profile) {
    162     return extensions::ExtensionRegistry::Get(profile)
    163         ->GenerateInstalledExtensionsSet();
    164   }
    165   return scoped_ptr<extensions::ExtensionSet>();
    166 }
    167 
    168 uint64 ExtensionsMetricsProvider::GetClientID() {
    169   // TODO(blundell): Create a MetricsLog::ClientIDAsInt() API and call it
    170   // here as well as in MetricsLog's population of the client_id field of
    171   // the uma_proto.
    172   return metrics::MetricsLog::Hash(metrics_state_manager_->client_id());
    173 }
    174 
    175 void ExtensionsMetricsProvider::ProvideSystemProfileMetrics(
    176     metrics::SystemProfileProto* system_profile) {
    177   ProvideOffStoreMetric(system_profile);
    178   ProvideOccupiedBucketMetric(system_profile);
    179 }
    180 
    181 void ExtensionsMetricsProvider::ProvideOffStoreMetric(
    182     metrics::SystemProfileProto* system_profile) {
    183   ProfileManager* profile_manager = g_browser_process->profile_manager();
    184   if (!profile_manager)
    185     return;
    186 
    187   ExtensionState state = NO_EXTENSIONS;
    188 
    189   // The off-store metric includes information from all loaded profiles at the
    190   // time when this metric is generated.
    191   std::vector<Profile*> profiles = profile_manager->GetLoadedProfiles();
    192   for (size_t i = 0u; i < profiles.size() && state < OFF_STORE; ++i) {
    193     extensions::InstallVerifier* verifier =
    194         extensions::ExtensionSystem::Get(profiles[i])->install_verifier();
    195 
    196     scoped_ptr<extensions::ExtensionSet> extensions(
    197         GetInstalledExtensions(profiles[i]));
    198     if (!extensions)
    199       continue;
    200 
    201     // Combine the state from each profile, always favoring the higher state as
    202     // defined by the order of ExtensionState.
    203     state = std::max(state, CheckForOffStore(*extensions.get(), *verifier));
    204   }
    205 
    206   system_profile->set_offstore_extensions_state(ExtensionStateAsProto(state));
    207 }
    208 
    209 void ExtensionsMetricsProvider::ProvideOccupiedBucketMetric(
    210     metrics::SystemProfileProto* system_profile) {
    211   // UMA reports do not support multiple profiles, but extensions are installed
    212   // per-profile.  We return the extensions installed in the primary profile.
    213   // In the future, we might consider reporting data about extensions in all
    214   // profiles.
    215   Profile* profile = GetMetricsProfile();
    216 
    217   scoped_ptr<extensions::ExtensionSet> extensions(
    218       GetInstalledExtensions(profile));
    219   if (!extensions)
    220     return;
    221 
    222   const int client_key = GetClientID() % kExtensionListClientKeys;
    223 
    224   std::set<int> buckets;
    225   for (extensions::ExtensionSet::const_iterator it = extensions->begin();
    226        it != extensions->end();
    227        ++it) {
    228     buckets.insert(HashExtension((*it)->id(), client_key));
    229   }
    230 
    231   for (std::set<int>::const_iterator it = buckets.begin(); it != buckets.end();
    232        ++it) {
    233     system_profile->add_occupied_extension_bucket(*it);
    234   }
    235 }
    236