Add methods to read/update request headers
Test: atest ParcelTest
Bug: 123744028
Change-Id: I3fc738a81bf2e091145d13da89e9da111c3494c8
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index f779d6e..49592a8 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -599,17 +599,53 @@
return mHasFds;
}
+void Parcel::updateWorkSourceRequestHeaderPosition() const {
+ // Only update the request headers once. We only want to point
+ // to the first headers read/written.
+ if (!mRequestHeaderPresent) {
+ mWorkSourceRequestHeaderPosition = dataPosition();
+ mRequestHeaderPresent = true;
+ }
+}
+
// Write RPC headers. (previously just the interface token)
status_t Parcel::writeInterfaceToken(const String16& interface)
{
const IPCThreadState* threadState = IPCThreadState::self();
writeInt32(threadState->getStrictModePolicy() | STRICT_MODE_PENALTY_GATHER);
+ updateWorkSourceRequestHeaderPosition();
writeInt32(threadState->shouldPropagateWorkSource() ?
threadState->getCallingWorkSourceUid() : IPCThreadState::kUnsetWorkSource);
// currently the interface identification token is just its name as a string
return writeString16(interface);
}
+bool Parcel::replaceCallingWorkSourceUid(uid_t uid)
+{
+ if (!mRequestHeaderPresent) {
+ return false;
+ }
+
+ const size_t initialPosition = dataPosition();
+ setDataPosition(mWorkSourceRequestHeaderPosition);
+ status_t err = writeInt32(uid);
+ setDataPosition(initialPosition);
+ return err == NO_ERROR;
+}
+
+uid_t Parcel::readCallingWorkSourceUid()
+{
+ if (!mRequestHeaderPresent) {
+ return IPCThreadState::kUnsetWorkSource;
+ }
+
+ const size_t initialPosition = dataPosition();
+ setDataPosition(mWorkSourceRequestHeaderPosition);
+ uid_t uid = readInt32();
+ setDataPosition(initialPosition);
+ return uid;
+}
+
bool Parcel::checkInterface(IBinder* binder) const
{
return enforceInterface(binder->getInterfaceDescriptor());
@@ -634,6 +670,7 @@
threadState->setStrictModePolicy(strictPolicy);
}
// WorkSource.
+ updateWorkSourceRequestHeaderPosition();
int32_t workSource = readInt32();
threadState->setCallingWorkSourceUidWithoutPropagation(workSource);
// Interface descriptor.
@@ -2889,6 +2926,8 @@
mAllowFds = true;
mOwner = nullptr;
mOpenAshmemSize = 0;
+ mWorkSourceRequestHeaderPosition = 0;
+ mRequestHeaderPresent = false;
// racing multiple init leads only to multiple identical write
if (gMaxFds == 0) {
diff --git a/libs/binder/include/binder/Parcel.h b/libs/binder/include/binder/Parcel.h
index 240b708..afdfe4f 100644
--- a/libs/binder/include/binder/Parcel.h
+++ b/libs/binder/include/binder/Parcel.h
@@ -395,6 +395,12 @@
static size_t getGlobalAllocSize();
static size_t getGlobalAllocCount();
+ bool replaceCallingWorkSourceUid(uid_t uid);
+ // Returns the work source provided by the caller. This can only be trusted for trusted calling
+ // uid.
+ uid_t readCallingWorkSourceUid();
+ void readRequestHeaders() const;
+
private:
typedef void (*release_func)(Parcel* parcel,
const uint8_t* data, size_t dataSize,
@@ -429,6 +435,7 @@
void initState();
void scanForFds() const;
status_t validateReadData(size_t len) const;
+ void updateWorkSourceRequestHeaderPosition() const;
template<class T>
status_t readAligned(T *pArg) const;
@@ -477,6 +484,9 @@
mutable size_t mNextObjectHint;
mutable bool mObjectsSorted;
+ mutable bool mRequestHeaderPresent;
+ mutable size_t mWorkSourceRequestHeaderPosition;
+
mutable bool mFdsKnown;
mutable bool mHasFds;
bool mAllowFds;