Merge changes Id8fc889f,I2145ad0e am: 5426122b9b am: 08cb54f49d

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1707789

Change-Id: I44d1b684d2a177b71c2a0aa64bd19d5fd1ba7b14

6 files changed, 137 insertions, 9 deletions

diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp
index ef7fd44419..18b77e6692 100644
--- a/libs/binder/IPCThreadState.cpp
+++ b/libs/binder/IPCThreadState.cpp
@@ -366,19 +366,45 @@ status_t IPCThreadState::clearLastError()
 
 pid_t IPCThreadState::getCallingPid() const
 {
+    checkContextIsBinderForUse(__func__);
     return mCallingPid;
 }
 
 const char* IPCThreadState::getCallingSid() const
 {
+    checkContextIsBinderForUse(__func__);
     return mCallingSid;
 }
 
 uid_t IPCThreadState::getCallingUid() const
 {
+    checkContextIsBinderForUse(__func__);
     return mCallingUid;
 }
 
+IPCThreadState::SpGuard* IPCThreadState::pushGetCallingSpGuard(SpGuard* guard) {
+    SpGuard* orig = mServingStackPointerGuard;
+    mServingStackPointerGuard = guard;
+    return orig;
+}
+
+void IPCThreadState::restoreGetCallingSpGuard(SpGuard* guard) {
+    mServingStackPointerGuard = guard;
+}
+
+void IPCThreadState::checkContextIsBinderForUse(const char* use) const {
+    if (mServingStackPointerGuard == nullptr) return;
+
+    if (!mServingStackPointer || mServingStackPointerGuard < mServingStackPointer) {
+        LOG_ALWAYS_FATAL("In context %s, %s does not make sense.",
+                         mServingStackPointerGuard->context, use);
+    }
+
+    // in the case mServingStackPointer is deeper in the stack than the guard,
+    // we must be serving a binder transaction (maybe nested). This is a binder
+    // context, so we don't abort
+}
+
 int64_t IPCThreadState::clearCallingIdentity()
 {
     // ignore mCallingSid for legacy reasons
@@ -847,15 +873,15 @@ status_t IPCThreadState::clearDeathNotification(int32_t handle, BpBinder* proxy)
 }
 
 IPCThreadState::IPCThreadState()
-    : mProcess(ProcessState::self()),
-      mServingStackPointer(nullptr),
-      mWorkSource(kUnsetWorkSource),
-      mPropagateWorkSource(false),
-      mIsLooper(false),
-      mStrictModePolicy(0),
-      mLastTransactionBinderFlags(0),
-      mCallRestriction(mProcess->mCallRestriction)
-{
+      : mProcess(ProcessState::self()),
+        mServingStackPointer(nullptr),
+        mServingStackPointerGuard(nullptr),
+        mWorkSource(kUnsetWorkSource),
+        mPropagateWorkSource(false),
+        mIsLooper(false),
+        mStrictModePolicy(0),
+        mLastTransactionBinderFlags(0),
+        mCallRestriction(mProcess->mCallRestriction) {
     pthread_setspecific(gTLS, this);
     clearCaller();
     mIn.setDataCapacity(256);
diff --git a/libs/binder/RpcState.cpp b/libs/binder/RpcState.cpp
index 2ba9fa2bd5..e5a6026f3b 100644
--- a/libs/binder/RpcState.cpp
+++ b/libs/binder/RpcState.cpp
@@ -18,7 +18,9 @@
 
 #include "RpcState.h"
 
+#include <android-base/scopeguard.h>
 #include <binder/BpBinder.h>
+#include <binder/IPCThreadState.h>
 #include <binder/RpcServer.h>
 
 #include "Debug.h"
@@ -28,6 +30,8 @@
 
 namespace android {
 
+using base::ScopeGuard;
+
 RpcState::RpcState() {}
 RpcState::~RpcState() {}
 
@@ -470,6 +474,18 @@ status_t RpcState::getAndExecuteCommand(const base::unique_fd& fd, const sp<RpcS
 
 status_t RpcState::processServerCommand(const base::unique_fd& fd, const sp<RpcSession>& session,
                                         const RpcWireHeader& command) {
+    IPCThreadState* kernelBinderState = IPCThreadState::selfOrNull();
+    IPCThreadState::SpGuard spGuard{"processing binder RPC command"};
+    IPCThreadState::SpGuard* origGuard;
+    if (kernelBinderState != nullptr) {
+        origGuard = kernelBinderState->pushGetCallingSpGuard(&spGuard);
+    }
+    ScopeGuard guardUnguard = [&]() {
+        if (kernelBinderState != nullptr) {
+            kernelBinderState->restoreGetCallingSpGuard(origGuard);
+        }
+    };
+
     switch (command.command) {
         case RPC_COMMAND_TRANSACT:
             return processTransact(fd, session, command);
diff --git a/libs/binder/include/binder/IPCThreadState.h b/libs/binder/include/binder/IPCThreadState.h
index 23a0cb0148..5220b62d62 100644
--- a/libs/binder/include/binder/IPCThreadState.h
+++ b/libs/binder/include/binder/IPCThreadState.h
@@ -81,6 +81,32 @@ public:
              */
             uid_t               getCallingUid() const;
 
+            /**
+             * Make it an abort to rely on getCalling* for a section of
+             * execution.
+             *
+             * Usage:
+             *     IPCThreadState::SpGuard guard { "..." };
+             *     auto* orig = pushGetCallingSpGuard(&guard);
+             *     {
+             *         // will abort if you call getCalling*, unless you are
+             *         // serving a nested binder transaction
+             *     }
+             *     restoreCallingSpGuard(orig);
+             */
+            struct SpGuard {
+                const char* context;
+            };
+            SpGuard* pushGetCallingSpGuard(SpGuard* guard);
+            void restoreGetCallingSpGuard(SpGuard* guard);
+            /**
+             * Used internally by getCalling*. Can also be used to assert that
+             * you are in a binder context (getCalling* is valid). This is
+             * intentionally not exposed as a boolean API since code should be
+             * written to know its environment.
+             */
+            void checkContextIsBinderForUse(const char* use) const;
+
             void                setStrictModePolicy(int32_t policy);
             int32_t             getStrictModePolicy() const;
 
@@ -203,6 +229,7 @@ private:
             Parcel              mOut;
             status_t            mLastError;
             const void*         mServingStackPointer;
+            SpGuard* mServingStackPointerGuard;
             pid_t               mCallingPid;
             const char*         mCallingSid;
             uid_t               mCallingUid;
diff --git a/libs/binder/tests/IBinderRpcTest.aidl b/libs/binder/tests/IBinderRpcTest.aidl
index ef4198d8f2..41daccc1cf 100644
--- a/libs/binder/tests/IBinderRpcTest.aidl
+++ b/libs/binder/tests/IBinderRpcTest.aidl
@@ -55,4 +55,6 @@ interface IBinderRpcTest {
     oneway void sleepMsAsync(int ms);
 
     void die(boolean cleanup);
+
+    void useKernelBinderCallingId();
 }
diff --git a/libs/binder/tests/binderLibTest.cpp b/libs/binder/tests/binderLibTest.cpp
index 0c3fbcd2da..45b277624c 100644
--- a/libs/binder/tests/binderLibTest.cpp
+++ b/libs/binder/tests/binderLibTest.cpp
@@ -73,6 +73,7 @@ enum BinderLibTestTranscationCode {
     BINDER_LIB_TEST_REGISTER_SERVER,
     BINDER_LIB_TEST_ADD_SERVER,
     BINDER_LIB_TEST_ADD_POLL_SERVER,
+    BINDER_LIB_TEST_USE_CALLING_GUARD_TRANSACTION,
     BINDER_LIB_TEST_CALL_BACK,
     BINDER_LIB_TEST_CALL_BACK_VERIFY_BUF,
     BINDER_LIB_TEST_DELAYED_CALL_BACK,
@@ -604,6 +605,24 @@ TEST_F(BinderLibTest, CallBack)
     EXPECT_THAT(callBack->getResult(), StatusEq(NO_ERROR));
 }
 
+TEST_F(BinderLibTest, NoBinderCallContextGuard) {
+    IPCThreadState::SpGuard spGuard{"NoBinderCallContext"};
+    IPCThreadState::SpGuard *origGuard = IPCThreadState::self()->pushGetCallingSpGuard(&spGuard);
+
+    // yes, this test uses threads, but it's careful and uses fork in addServer
+    EXPECT_DEATH({ IPCThreadState::self()->getCallingPid(); },
+                 "In context NoBinderCallContext, getCallingPid does not make sense.");
+
+    IPCThreadState::self()->restoreGetCallingSpGuard(origGuard);
+}
+
+TEST_F(BinderLibTest, BinderCallContextGuard) {
+    sp<IBinder> binder = addServer();
+    Parcel data, reply;
+    EXPECT_THAT(binder->transact(BINDER_LIB_TEST_USE_CALLING_GUARD_TRANSACTION, data, &reply),
+                StatusEq(DEAD_OBJECT));
+}
+
 TEST_F(BinderLibTest, AddServer)
 {
     sp<IBinder> server = addServer();
@@ -1262,6 +1281,18 @@ class BinderLibTestService : public BBinder
                 pthread_mutex_unlock(&m_serverWaitMutex);
                 return ret;
             }
+            case BINDER_LIB_TEST_USE_CALLING_GUARD_TRANSACTION: {
+                IPCThreadState::SpGuard spGuard{"GuardInBinderTransaction"};
+                IPCThreadState::SpGuard *origGuard =
+                        IPCThreadState::self()->pushGetCallingSpGuard(&spGuard);
+
+                // if the guard works, this should abort
+                (void)IPCThreadState::self()->getCallingPid();
+
+                IPCThreadState::self()->restoreGetCallingSpGuard(origGuard);
+                return NO_ERROR;
+            }
+
             case BINDER_LIB_TEST_GETPID:
                 reply->writeInt32(getpid());
                 return NO_ERROR;
@@ -1489,6 +1520,11 @@ int run_server(int index, int readypipefd, bool usePoll)
 {
     binderLibTestServiceName += String16(binderserversuffix);
 
+    // Testing to make sure that calls that we are serving can use getCallin*
+    // even though we don't here.
+    IPCThreadState::SpGuard spGuard{"main server thread"};
+    (void)IPCThreadState::self()->pushGetCallingSpGuard(&spGuard);
+
     status_t ret;
     sp<IServiceManager> sm = defaultServiceManager();
     BinderLibTestService* testServicePtr;
diff --git a/libs/binder/tests/binderRpcTest.cpp b/libs/binder/tests/binderRpcTest.cpp
index 260be570f9..9c263b1f21 100644
--- a/libs/binder/tests/binderRpcTest.cpp
+++ b/libs/binder/tests/binderRpcTest.cpp
@@ -23,6 +23,7 @@
 #include <android/binder_libbinder.h>
 #include <binder/Binder.h>
 #include <binder/BpBinder.h>
+#include <binder/IPCThreadState.h>
 #include <binder/IServiceManager.h>
 #include <binder/ProcessState.h>
 #include <binder/RpcServer.h>
@@ -178,6 +179,13 @@ public:
             _exit(1);
         }
     }
+    Status useKernelBinderCallingId() override {
+        // this is WRONG! It does not make sense when using RPC binder, and
+        // because it is SO wrong, and so much code calls this, it should abort!
+
+        (void)IPCThreadState::self()->getCallingPid();
+        return Status::ok();
+    }
 };
 sp<IBinder> MyBinderRpcTest::mHeldBinder;
 
@@ -874,6 +882,19 @@ TEST_P(BinderRpc, Die) {
     }
 }
 
+TEST_P(BinderRpc, UseKernelBinderCallingId) {
+    auto proc = createRpcTestSocketServerProcess(1);
+
+    // we can't allocate IPCThreadState so actually the first time should
+    // succeed :(
+    EXPECT_OK(proc.rootIface->useKernelBinderCallingId());
+
+    // second time! we catch the error :)
+    EXPECT_EQ(DEAD_OBJECT, proc.rootIface->useKernelBinderCallingId().transactionError());
+
+    proc.expectInvalid = true;
+}
+
 TEST_P(BinderRpc, WorksWithLibbinderNdkPing) {
     auto proc = createRpcTestSocketServerProcess(1);