Added write protection for session to engine map. am: b6cdd12394 am: b7aa89024e

Original change: https://googleplex-android-review.googlesource.com/c/platform/vendor/widevine/+/15180882

Change-Id: I02aa84ef497a1ac8fb6ae4b04aec85133819ccd5

libwvdrmengine/cdm/include/wv_content_decryption_module.h

@@ -215,6 +215,14 @@ class WvContentDecryptionModule : public android::RefBase, public TimerHandler {
   void DisableTimerAndWaitForExit();
   void OnTimerEvent();
 
+  // Fill the |metrics| parameter with the metrics data for the CdmEngine
+  // associated with the given |identifier|. If the CdmEngine instance does
+  // not exist, this will return an error.
+  // This methods assumes that |metrics| is not null and that the |cdms_lock_|
+  // has already been acquired.
+  CdmResponseType GetMetricsInternal(const CdmIdentifier& identifier,
+                                     drm_metrics::WvCdmMetrics* metrics);
+
   static std::mutex session_sharing_id_generation_lock_;
   std::mutex timer_lock_;
   Timer timer_;
@@ -222,14 +230,27 @@ class WvContentDecryptionModule : public android::RefBase, public TimerHandler {
   // instance variables
   // This manages the lifetime of the CDM instances.
   std::map<CdmIdentifier, CdmInfo> cdms_;
-  std::mutex cdms_lock_;
-
   // This contains weak pointers to the CDM instances contained in |cdms_|.
   std::map<std::string, CdmEngine*> cdm_by_session_id_;
+  // Lock for accessing either |cdms_| or |cdm_by_session_id_|.
+  // This lock should be acquired for any of the following:
+  // 1) Getting a CDM instance from |cdms_| or |cdm_by_session_id_|
+  //    - Hold lock while searching, release lock once pointer is acquired
+  // 2) Iterating over |cdms_| or |cdm_by_session_id_|
+  //    - Hold lock for the entire duration of iterating over CDMs
+  //    - DO NOT release the lock until all operations are complete
+  //    - This MUST be done regardless of whether |cdms_| or
+  //      |cdm_by_session_id_| is being modified
+  // 3) Creating a new CDM instance with |cdms_|
+  //    - Hold lock when creating AND initializing the CDM
+  //    - Release once CDM is fully initialized
+  // 4) Linking a session to a CDM with |cdm_by_session_id_|
+  //    - Hold lock when mapping a session ID to a CDM, release once set
+  // 5) Unlinking a session from a CDM with |cdm_by_session_id_|
+  //    - Hold lock when erasing, release once erased.
+  std::mutex cdms_lock_;
 
   CORE_DISALLOW_COPY_AND_ASSIGN(WvContentDecryptionModule);
 };
-
 }  // namespace wvcdm
-
 #endif  // CDM_BASE_WV_CONTENT_DECRYPTION_MODULE_H_

libwvdrmengine/cdm/src/wv_content_decryption_module.cpp

@@ -71,6 +71,7 @@ CdmResponseType WvContentDecryptionModule::OpenSession(
   CdmResponseType sts = cdm_engine->OpenSession(key_system, property_set,
                                                 event_listener, session_id);
   if (sts == NO_ERROR) {
+    std::unique_lock<std::mutex> auto_lock(cdms_lock_);
     cdm_by_session_id_[*session_id] = cdm_engine;
   }
   return sts;
@@ -82,12 +83,11 @@ CdmResponseType WvContentDecryptionModule::CloseSession(
   CdmEngine* cdm_engine = GetCdmForSessionId(session_id);
   // TODO(rfrias): Avoid reusing the error codes from CdmEngine.
   if (!cdm_engine) return SESSION_NOT_FOUND_1;
-  std::unique_lock<std::mutex> auto_lock(cdms_lock_);
+  const CdmResponseType sts = cdm_engine->CloseSession(session_id);
-  CdmResponseType sts = cdm_engine->CloseSession(session_id);
   if (sts == NO_ERROR) {
+    std::unique_lock<std::mutex> auto_lock(cdms_lock_);
     cdm_by_session_id_.erase(session_id);
   }
-
   return sts;
 }
 
@@ -107,6 +107,7 @@ CdmResponseType WvContentDecryptionModule::GenerateKeyRequest(
   if (license_type == kLicenseTypeRelease) {
     sts = cdm_engine->OpenKeySetSession(key_set_id, property_set, nullptr);
     if (sts != NO_ERROR) return sts;
+    std::unique_lock<std::mutex> auto_lock(cdms_lock_);
     cdm_by_session_id_[key_set_id] = cdm_engine;
   }
 
@@ -130,6 +131,7 @@ CdmResponseType WvContentDecryptionModule::GenerateKeyRequest(
                                        app_parameters, key_request);
   if (license_type == kLicenseTypeRelease && sts != KEY_MESSAGE) {
     cdm_engine->CloseKeySetSession(key_set_id);
+    std::unique_lock<std::mutex> auto_lock(cdms_lock_);
     cdm_by_session_id_.erase(key_set_id);
   }
   return sts;
@@ -152,6 +154,7 @@ CdmResponseType WvContentDecryptionModule::AddKey(
   // Empty session id indicates license type release.
   if (sts == KEY_ADDED && session_id.empty()) {
     cdm_engine->CloseKeySetSession(release_key_set_id);
+    std::unique_lock<std::mutex> auto_lock(cdms_lock_);
     cdm_by_session_id_.erase(release_key_set_id);
   }
   return sts;
@@ -297,11 +300,11 @@ CdmResponseType WvContentDecryptionModule::GetSecureStopIds(
   }
 
   CdmEngine* cdm_engine = EnsureCdmForIdentifier(identifier);
-  CdmResponseType sts =
+  const CdmResponseType sts =
       cdm_engine->ListUsageIds(app_id, kSecurityLevelL1, nullptr, ssids);
   std::vector<CdmSecureStopId> secure_stop_ids;
-  CdmResponseType sts_l3 = cdm_engine->ListUsageIds(app_id, kSecurityLevelL3,
+  const CdmResponseType sts_l3 = cdm_engine->ListUsageIds(
-                                                    nullptr, &secure_stop_ids);
+      app_id, kSecurityLevelL3, nullptr, &secure_stop_ids);
   ssids->insert(ssids->end(), secure_stop_ids.begin(), secure_stop_ids.end());
   return sts_l3 != NO_ERROR ? sts_l3 : sts;
 }
@@ -383,17 +386,19 @@ CdmResponseType WvContentDecryptionModule::GetMetrics(
   if (!metrics || !full_list_returned) {
     return PARAMETER_NULL;
   }
+  std::unique_lock<std::mutex> auto_lock(cdms_lock_);
   for (auto& key_value_pair : cdms_) {
+    const CdmIdentifier& identifier = key_value_pair.first;
     drm_metrics::WvCdmMetrics metric;
-    CdmResponseType status = GetMetrics(key_value_pair.first, &metric);
+    const CdmResponseType status = GetMetricsInternal(identifier, &metric);
     if (status == NO_ERROR) {
       metrics->push_back(metric);
     } else {
       LOGD("GetMetrics call failed: cdm identifier=%u, error=%d",
-           key_value_pair.first.unique_id, status);
+           identifier.unique_id, status);
     }
   }
-  // With no streaming activities, cdms_ size would be zero,
+  // With no streaming activities, |cdms_| size would be zero,
   // treat it as a non full list in that case.
   *full_list_returned = !cdms_.empty() && metrics->size() == cdms_.size();
 
@@ -410,6 +415,12 @@ CdmResponseType WvContentDecryptionModule::GetMetrics(
     return PARAMETER_NULL;
   }
   std::unique_lock<std::mutex> auto_lock(cdms_lock_);
+  return GetMetricsInternal(identifier, metrics);
+}
+
+CdmResponseType WvContentDecryptionModule::GetMetricsInternal(
+    const CdmIdentifier& identifier, drm_metrics::WvCdmMetrics* metrics) {
+  // Note: Caller should lock before calling.
   auto it = cdms_.find(identifier);
   if (it == cdms_.end()) {
     LOGE("Cdm Identifier not found");
@@ -454,6 +465,7 @@ CdmEngine* WvContentDecryptionModule::EnsureCdmForIdentifier(
 
 CdmEngine* WvContentDecryptionModule::GetCdmForSessionId(
     const std::string& session_id) {
+  std::unique_lock<std::mutex> auto_lock(cdms_lock_);
   // Use find to avoid creating empty entries when not found.
   auto it = cdm_by_session_id_.find(session_id);
   if (it == cdm_by_session_id_.end()) return nullptr;
@@ -462,10 +474,8 @@ CdmEngine* WvContentDecryptionModule::GetCdmForSessionId(
 
 void WvContentDecryptionModule::CloseAllCdms() {
   std::unique_lock<std::mutex> auto_lock(cdms_lock_);
-
+  cdm_by_session_id_.clear();
-  for (auto it = cdms_.begin(); it != cdms_.end();) {
+  cdms_.clear();
-    it = cdms_.erase(it);
-  }
 }
 
 CdmResponseType WvContentDecryptionModule::CloseCdm(