RPC binder: expose session to per-client roots

Bug: 274156888
Test: N/A
Change-Id: Iad721ebea7ddd461ed41f2ba1fc08849309f7611

5 files changed, 32 insertions, 20 deletions

diff --git a/libs/binder/RpcServer.cpp b/libs/binder/RpcServer.cpp
index 00e040f3a4..55fc16de45 100644
--- a/libs/binder/RpcServer.cpp
+++ b/libs/binder/RpcServer.cpp
@@ -154,7 +154,7 @@ void RpcServer::setRootObjectWeak(const wp<IBinder>& binder) {
     mRootObjectWeak = binder;
 }
 void RpcServer::setPerSessionRootObject(
-        std::function<sp<IBinder>(const void*, size_t)>&& makeObject) {
+        std::function<sp<IBinder>(wp<RpcSession> session, const void*, size_t)>&& makeObject) {
     RpcMutexLockGuard _l(mLock);
     mRootObject.clear();
     mRootObjectWeak.clear();
@@ -515,7 +515,8 @@ void RpcServer::establishConnection(
             // if null, falls back to server root
             sp<IBinder> sessionSpecificRoot;
             if (server->mRootObjectFactory != nullptr) {
-                sessionSpecificRoot = server->mRootObjectFactory(addr.data(), addrLen);
+                sessionSpecificRoot =
+                        server->mRootObjectFactory(wp<RpcSession>(session), addr.data(), addrLen);
                 if (sessionSpecificRoot == nullptr) {
                     ALOGE("Warning: server returned null from root object factory");
                 }
diff --git a/libs/binder/include/binder/RpcServer.h b/libs/binder/include/binder/RpcServer.h
index 56ac7b0c4f..b804f7b92a 100644
--- a/libs/binder/include/binder/RpcServer.h
+++ b/libs/binder/include/binder/RpcServer.h
@@ -163,14 +163,18 @@ public:
      * Allows a root object to be created for each session.
      *
      * Takes one argument: a callable that is invoked once per new session.
-     * The callable takes two arguments: a type-erased pointer to an OS- and
-     * transport-specific address structure, e.g., sockaddr_vm for vsock, and
-     * an integer representing the size in bytes of that structure. The
-     * callable should validate the size, then cast the type-erased pointer
-     * to a pointer to the actual type of the address, e.g., const void* to
-     * const sockaddr_vm*.
+     * The callable takes three arguments:
+     * - a weak pointer to the session. If you want to hold onto this in the root object, then
+     *   you should keep a weak pointer, and promote it when needed. For instance, if you refer
+     *   to this from the root object, then you could get ahold of transport-specific information.
+     * - a type-erased pointer to an OS- and transport-specific address structure, e.g.,
+     *   sockaddr_vm for vsock
+     * - an integer representing the size in bytes of that structure. The callable should
+     *   validate the size, then cast the type-erased pointer to a pointer to the actual type of the
+     *   address, e.g., const void* to const sockaddr_vm*.
      */
-    void setPerSessionRootObject(std::function<sp<IBinder>(const void*, size_t)>&& object);
+    void setPerSessionRootObject(
+            std::function<sp<IBinder>(wp<RpcSession> session, const void*, size_t)>&& object);
     sp<IBinder> getRootObject();
 
     /**
@@ -272,7 +276,7 @@ private:
 
     sp<IBinder> mRootObject;
     wp<IBinder> mRootObjectWeak;
-    std::function<sp<IBinder>(const void*, size_t)> mRootObjectFactory;
+    std::function<sp<IBinder>(wp<RpcSession>, const void*, size_t)> mRootObjectFactory;
     std::function<bool(const void*, size_t)> mConnectionFilter;
     std::function<void(base::borrowed_fd)> mServerSocketModifier;
     std::map<std::vector<uint8_t>, sp<RpcSession>> mSessions;
diff --git a/libs/binder/tests/binderRpcTestService.cpp b/libs/binder/tests/binderRpcTestService.cpp
index 5e83fbfab2..cb09a7fbab 100644
--- a/libs/binder/tests/binderRpcTestService.cpp
+++ b/libs/binder/tests/binderRpcTestService.cpp
@@ -164,7 +164,12 @@ int main(int argc, char* argv[]) {
         }
     }
 
-    server->setPerSessionRootObject([&](const void* addrPtr, size_t len) {
+    server->setPerSessionRootObject([&](wp<RpcSession> session, const void* addrPtr, size_t len) {
+        {
+            sp<RpcSession> spSession = session.promote();
+            CHECK_NE(nullptr, spSession.get());
+        }
+
         // UNIX sockets with abstract addresses return
         // sizeof(sa_family_t)==2 in addrlen
         CHECK_GE(len, sizeof(sa_family_t));
diff --git a/libs/binder/tests/binderRpcTestServiceTrusty.cpp b/libs/binder/tests/binderRpcTestServiceTrusty.cpp
index 5c7a96af32..cb632e95bf 100644
--- a/libs/binder/tests/binderRpcTestServiceTrusty.cpp
+++ b/libs/binder/tests/binderRpcTestServiceTrusty.cpp
@@ -93,14 +93,15 @@ int main(void) {
         if (!serverInfo.server->setProtocolVersion(serverVersion)) {
             return EXIT_FAILURE;
         }
-        serverInfo.server->setPerSessionRootObject([=](const void* /*addrPtr*/, size_t /*len*/) {
-            auto service = sp<MyBinderRpcTestTrusty>::make();
-            // Assign a unique connection identifier to service->port so
-            // getClientPort returns a unique value per connection
-            service->port = ++gConnectionCounter;
-            service->server = server;
-            return service;
-        });
+        serverInfo.server->setPerSessionRootObject(
+                [=](wp<RpcSession> /*session*/, const void* /*addrPtr*/, size_t /*len*/) {
+                    auto service = sp<MyBinderRpcTestTrusty>::make();
+                    // Assign a unique connection identifier to service->port so
+                    // getClientPort returns a unique value per connection
+                    service->port = ++gConnectionCounter;
+                    service->server = server;
+                    return service;
+                });
 
         servers.push_back(std::move(serverInfo));
     }
diff --git a/libs/binder/trusty/include/binder/RpcServerTrusty.h b/libs/binder/trusty/include/binder/RpcServerTrusty.h
index 119f2a393f..8924b3679f 100644
--- a/libs/binder/trusty/include/binder/RpcServerTrusty.h
+++ b/libs/binder/trusty/include/binder/RpcServerTrusty.h
@@ -68,7 +68,8 @@ public:
     }
     void setRootObject(const sp<IBinder>& binder) { mRpcServer->setRootObject(binder); }
     void setRootObjectWeak(const wp<IBinder>& binder) { mRpcServer->setRootObjectWeak(binder); }
-    void setPerSessionRootObject(std::function<sp<IBinder>(const void*, size_t)>&& object) {
+    void setPerSessionRootObject(
+            std::function<sp<IBinder>(wp<RpcSession> session, const void*, size_t)>&& object) {
         mRpcServer->setPerSessionRootObject(std::move(object));
     }
     sp<IBinder> getRootObject() { return mRpcServer->getRootObject(); }