Binder: support storing interface stability
This adds runtime information for what the stability class of a binder
is in preparation for allowing binders system<->vendor. However, this
shouldn't necessarily be restricted to this case. For instance, it may
also be used to separate APEX interface stability levels. The idea is
that for code serving an interface of a given stability, only intefaces
of greater stability can be sent to it. This is slightly less
restrictive than existing binder domains. For instance, this could
potentially support having a single interface 'vintf' interface which is
shared by both system and vendor (this removing the need for infra like
ITokenManager).
The API that is exposed only allows marking a binder as a specific
stability class (see Stability.h). For instance, 'markVintf' marks an
API as being exposed system<->vendor. Although, infrastructure in
servicemanager, aidl, sepolicy, and VTS still need to support this in
order to be useful.
The actual implementation of these stability classes (bitmasks) is not
exposed and may be changed arbitrarily. Currently these bitmasks are
32-bit integers. These are sent to other processes because the type
system in AIDL cannot encode the stability requirements here without
either dropping IBinder or differentating IBinder by stability level
(which we don't want). So, where possible, AIDL will differentiate
stability level at compile time, but when IBinder is used, for
handwritten interfaces, and as a backup in case any other piece of the
infrastructure fails, the stability is also checked at runtime.
Bug: 136027762
Test: atest binderStabilityTest
Change-Id: Ia637ee3652d55550e7fce78876458f391b1dd928
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 5537430..0b9849a 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -164,14 +164,34 @@
ALOGE("Invalid object type 0x%08x", obj.hdr.type);
}
-inline static status_t finish_flatten_binder(
- const sp<IBinder>& /*binder*/, const flat_binder_object& flat, Parcel* out)
+status_t Parcel::finishFlattenBinder(
+ const sp<IBinder>& binder, const flat_binder_object& flat)
{
- return out->writeObject(flat, false);
+ status_t status = writeObject(flat, false);
+ if (status != OK) return status;
+
+ return writeInt32(internal::Stability::get(binder.get()));
}
-static status_t flatten_binder(const sp<ProcessState>& /*proc*/,
- const sp<IBinder>& binder, Parcel* out)
+status_t Parcel::finishUnflattenBinder(
+ const sp<IBinder>& binder, sp<IBinder>* out) const
+{
+ int32_t stability;
+ status_t status = readInt32(&stability);
+ if (status != OK) return status;
+
+ if (!internal::Stability::check(stability, mRequiredStability)) {
+ return BAD_TYPE;
+ }
+
+ status = internal::Stability::set(binder.get(), stability);
+ if (status != OK) return status;
+
+ *out = binder;
+ return OK;
+}
+
+status_t Parcel::flattenBinder(const sp<IBinder>& binder)
{
flat_binder_object obj;
@@ -209,30 +229,24 @@
obj.cookie = 0;
}
- return finish_flatten_binder(binder, obj, out);
+ return finishFlattenBinder(binder, obj);
}
-inline static status_t finish_unflatten_binder(
- BpBinder* /*proxy*/, const flat_binder_object& /*flat*/,
- const Parcel& /*in*/)
+status_t Parcel::unflattenBinder(sp<IBinder>* out) const
{
- return NO_ERROR;
-}
-
-static status_t unflatten_binder(const sp<ProcessState>& proc,
- const Parcel& in, sp<IBinder>* out)
-{
- const flat_binder_object* flat = in.readObject(false);
+ const flat_binder_object* flat = readObject(false);
if (flat) {
switch (flat->hdr.type) {
- case BINDER_TYPE_BINDER:
- *out = reinterpret_cast<IBinder*>(flat->cookie);
- return finish_unflatten_binder(nullptr, *flat, in);
- case BINDER_TYPE_HANDLE:
- *out = proc->getStrongProxyForHandle(flat->handle);
- return finish_unflatten_binder(
- static_cast<BpBinder*>(out->get()), *flat, in);
+ case BINDER_TYPE_BINDER: {
+ sp<IBinder> binder = reinterpret_cast<IBinder*>(flat->cookie);
+ return finishUnflattenBinder(binder, out);
+ }
+ case BINDER_TYPE_HANDLE: {
+ sp<IBinder> binder =
+ ProcessState::self()->getStrongProxyForHandle(flat->handle);
+ return finishUnflattenBinder(binder, out);
+ }
}
}
return BAD_TYPE;
@@ -337,6 +351,10 @@
return NO_ERROR;
}
+void Parcel::setTransactingBinder(const sp<IBinder>& binder) const {
+ mRequiredStability = internal::Stability::get(binder.get());
+}
+
status_t Parcel::setData(const uint8_t* buffer, size_t len)
{
if (len > INT32_MAX) {
@@ -1032,7 +1050,7 @@
status_t Parcel::writeStrongBinder(const sp<IBinder>& val)
{
- return flatten_binder(ProcessState::self(), val, this);
+ return flattenBinder(val);
}
status_t Parcel::writeStrongBinderVector(const std::vector<sp<IBinder>>& val)
@@ -1978,7 +1996,7 @@
status_t Parcel::readNullableStrongBinder(sp<IBinder>* val) const
{
- return unflatten_binder(ProcessState::self(), *this, val);
+ return unflattenBinder(val);
}
sp<IBinder> Parcel::readStrongBinder() const
@@ -2682,9 +2700,10 @@
mObjectsCapacity = 0;
mNextObjectHint = 0;
mObjectsSorted = false;
+ mAllowFds = true;
mHasFds = false;
mFdsKnown = true;
- mAllowFds = true;
+ mRequiredStability = internal::Stability::UNDECLARED;
mOwner = nullptr;
mOpenAshmemSize = 0;
mWorkSourceRequestHeaderPosition = 0;