ServiceManager: support debug dump w/ PIDs

To enable binder service-name based dumps of services when the same
interface might be registered from multiple different processes.

The getDebugPid command can't be sent instead to specific instances,
since if they are hung, the PID couldn't be retrieved.

For partiy w/ HIDL, this uses the 'list' selinux permission to control
reading debug dumps.

Bug: 175322136
Test: using this info to dump AIDL HALs in ANR
Change-Id: I4bc7c2df5faa6be1cdcc69b2a7fc882293f1d249

5 files changed, 58 insertions, 0 deletions

diff --git a/cmds/servicemanager/ServiceManager.cpp b/cmds/servicemanager/ServiceManager.cpp
index b21010d49a..0dbab4e055 100644
--- a/cmds/servicemanager/ServiceManager.cpp
+++ b/cmds/servicemanager/ServiceManager.cpp
@@ -623,4 +623,21 @@ Status ServiceManager::tryUnregisterService(const std::string& name, const sp<IB
     return Status::ok();
 }
 
+Status ServiceManager::getServiceDebugInfo(std::vector<ServiceDebugInfo>* outReturn) {
+    if (!mAccess->canList(mAccess->getCallingContext())) {
+        return Status::fromExceptionCode(Status::EX_SECURITY);
+    }
+
+    outReturn->reserve(mNameToService.size());
+    for (auto const& [name, service] : mNameToService) {
+        ServiceDebugInfo info;
+        info.name = name;
+        info.debugPid = service.debugPid;
+
+        outReturn->push_back(std::move(info));
+    }
+
+    return Status::ok();
+}
+
 }  // namespace android
diff --git a/cmds/servicemanager/ServiceManager.h b/cmds/servicemanager/ServiceManager.h
index 9f43eb4f58..c0891152e6 100644
--- a/cmds/servicemanager/ServiceManager.h
+++ b/cmds/servicemanager/ServiceManager.h
@@ -26,6 +26,7 @@ namespace android {
 
 using os::IClientCallback;
 using os::IServiceCallback;
+using os::ServiceDebugInfo;
 
 class ServiceManager : public os::BnServiceManager, public IBinder::DeathRecipient {
 public:
@@ -48,6 +49,7 @@ public:
     binder::Status registerClientCallback(const std::string& name, const sp<IBinder>& service,
                                           const sp<IClientCallback>& cb) override;
     binder::Status tryUnregisterService(const std::string& name, const sp<IBinder>& binder) override;
+    binder::Status getServiceDebugInfo(std::vector<ServiceDebugInfo>* outReturn) override;
     void binderDied(const wp<IBinder>& who) override;
     void handleClientCallbacks();
 
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index e754d74655..ed079db4b3 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -214,6 +214,7 @@ filegroup {
         "aidl/android/os/IClientCallback.aidl",
         "aidl/android/os/IServiceCallback.aidl",
         "aidl/android/os/IServiceManager.aidl",
+        "aidl/android/os/ServiceDebugInfo.aidl",
     ],
     path: "aidl",
 }
diff --git a/libs/binder/aidl/android/os/IServiceManager.aidl b/libs/binder/aidl/android/os/IServiceManager.aidl
index 2b1e49283f..ce30050a89 100644
--- a/libs/binder/aidl/android/os/IServiceManager.aidl
+++ b/libs/binder/aidl/android/os/IServiceManager.aidl
@@ -18,6 +18,7 @@ package android.os;
 
 import android.os.IClientCallback;
 import android.os.IServiceCallback;
+import android.os.ServiceDebugInfo;
 
 /**
  * Basic interface for finding and publishing system services.
@@ -116,4 +117,9 @@ interface IServiceManager {
      * Attempt to unregister and remove a service. Will fail if the service is still in use.
      */
     void tryUnregisterService(@utf8InCpp String name, IBinder service);
+
+    /**
+     * Get debug information for all currently registered services.
+     */
+    ServiceDebugInfo[] getServiceDebugInfo();
 }
diff --git a/libs/binder/aidl/android/os/ServiceDebugInfo.aidl b/libs/binder/aidl/android/os/ServiceDebugInfo.aidl
new file mode 100644
index 0000000000..b95d222394
--- /dev/null
+++ b/libs/binder/aidl/android/os/ServiceDebugInfo.aidl
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.os;
+
+/**
+ * Debug information associated with a registered service
+ * @hide
+ */
+parcelable ServiceDebugInfo {
+    /**
+     * Service name (see IServiceManager.addService/checkService/getService)
+     */
+    @utf8InCpp String name;
+    /**
+     * PID of service at the time of registration (may no longer be valid).
+     */
+    int debugPid;
+}