Merge "libbinder: binders hold wire protocol version" am: 9c8f3f0dc4 (3637e29a) · Commits · e / os / platform_frameworks_native

libs/binder/BpBinder.cpp

+6 −5

Original line number	Diff line number	Diff line
		@@ -223,13 +223,14 @@ status_t BpBinder::transact(
		if (code >= FIRST_CALL_TRANSACTION && code <= LAST_CALL_TRANSACTION) {
		using android::internal::Stability;

		auto stability = Stability::get(this);
		auto required = privateVendor ? Stability::VENDOR : Stability::getLocalStability();
		auto category = Stability::getCategory(this);
		Stability::Level required = privateVendor ? Stability::VENDOR
		: Stability::getLocalLevel();

		if (CC_UNLIKELY(!Stability::check(stability, required))) {
		if (CC_UNLIKELY(!Stability::check(category, required))) {
		ALOGE("Cannot do a user transaction on a %s binder in a %s context.",
		Stability::stabilityString(stability).c_str(),
		Stability::stabilityString(required).c_str());
		category.debugString().c_str(),
		Stability::levelString(required).c_str());
		return BAD_TYPE;
		}
		}

libs/binder/Parcel.cpp

+3 −2

Original line number	Diff line number	Diff line
		@@ -171,7 +171,8 @@ status_t Parcel::finishFlattenBinder(
		if (status != OK) return status;

		internal::Stability::tryMarkCompilationUnit(binder.get());
		return writeInt32(internal::Stability::get(binder.get()));
		auto category = internal::Stability::getCategory(binder.get());
		return writeInt32(category.repr());
		}

		status_t Parcel::finishUnflattenBinder(
		@@ -181,7 +182,7 @@ status_t Parcel::finishUnflattenBinder(
		status_t status = readInt32(&stability);
		if (status != OK) return status;

		status = internal::Stability::set(binder.get(), stability, true /log/);
		status = internal::Stability::setRepr(binder.get(), stability, true /log/);
		if (status != OK) return status;

		*out = binder;

libs/binder/Stability.cpp

+74 −31

Original line number	Diff line number	Diff line
		@@ -13,6 +13,8 @@
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/
		#define LOG_TAG "Stability"

		#include <binder/Stability.h>

		#include <binder/BpBinder.h>
		@@ -21,34 +23,59 @@
		namespace android {
		namespace internal {

		// the libbinder parcel format is currently unstable

		// oldest version which is supported
		constexpr uint8_t kBinderWireFormatOldest = 1;
		// current version
		constexpr uint8_t kBinderWireFormatVersion = 1;

		Stability::Category Stability::Category::currentFromLevel(Level level) {
		return {
		.version = kBinderWireFormatVersion,
		.reserved = {0},
		.level = level,
		};
		}

		std::string Stability::Category::debugString() {
		return levelString(level) + " wire protocol version "
		+ std::to_string(version);
		}

		void Stability::markCompilationUnit(IBinder* binder) {
		status_t result = set(binder, getLocalStability(), true /log/);
		auto stability = Category::currentFromLevel(getLocalLevel());
		status_t result = setRepr(binder, stability.repr(), true /log/);
		LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");
		}

		void Stability::markVintf(IBinder* binder) {
		status_t result = set(binder, Level::VINTF, true /log/);
		auto stability = Category::currentFromLevel(Level::VINTF);
		status_t result = setRepr(binder, stability.repr(), true /log/);
		LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");
		}

		void Stability::debugLogStability(const std::string& tag, const sp<IBinder>& binder) {
		ALOGE("%s: stability is %s", tag.c_str(), stabilityString(get(binder.get())).c_str());
		auto stability = getCategory(binder.get());
		ALOGE("%s: stability is %s", tag.c_str(), stability.debugString().c_str());
		}

		void Stability::markVndk(IBinder* binder) {
		status_t result = set(binder, Level::VENDOR, true /log/);
		auto stability = Category::currentFromLevel(Level::VENDOR);
		status_t result = setRepr(binder, stability.repr(), true /log/);
		LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");
		}

		bool Stability::requiresVintfDeclaration(const sp<IBinder>& binder) {
		return check(get(binder.get()), Level::VINTF);
		return check(getCategory(binder.get()), Level::VINTF);
		}

		void Stability::tryMarkCompilationUnit(IBinder* binder) {
		(void) set(binder, getLocalStability(), false /log/);
		auto stability = Category::currentFromLevel(getLocalLevel());
		(void) setRepr(binder, stability.repr(), false /log/);
		}

		Stability::Level Stability::getLocalStability() {
		Stability::Level Stability::getLocalLevel() {
		#ifdef __ANDROID_VNDK__
		#ifdef __ANDROID_APEX__
		// TODO(b/142684679) avoid use_vendor on system APEXes
		@@ -67,65 +94,81 @@ Stability::Level Stability::getLocalStability() {
		#endif
		}

		status_t Stability::set(IBinder* binder, int32_t stability, bool log) {
		Level currentStability = get(binder);
		status_t Stability::setRepr(IBinder* binder, int32_t representation, bool log) {
		auto current = getCategory(binder);
		auto setting = Category::fromRepr(representation);

		// If we have ahold of a binder with a newer declared version, then it
		// should support older versions, and we will simply write our parcels with
		// the current wire parcel format.
		if (setting.version < kBinderWireFormatOldest) {
		// always log, because this shouldn't happen
		ALOGE("Cannot accept binder with older binder wire protocol version "
		"%u. Versions less than %u are unsupported.", setting.version,
		kBinderWireFormatOldest);
		return BAD_TYPE;
		}

		// null binder is always written w/ 'UNDECLARED' stability
		if (binder == nullptr) {
		if (stability == UNDECLARED) {
		if (setting.level == UNDECLARED) {
		return OK;
		} else {
		if (log) {
		ALOGE("Null binder written with stability %s.",
		stabilityString(stability).c_str());
		levelString(setting.level).c_str());
		}
		return BAD_TYPE;
		}
		}

		if (!isDeclaredStability(stability)) {
		if (!isDeclaredLevel(setting.level)) {
		if (log) {
		ALOGE("Can only set known stability, not %d.", stability);
		ALOGE("Can only set known stability, not %u.", setting.level);
		}
		return BAD_TYPE;
		}

		if (currentStability != Level::UNDECLARED && currentStability != stability) {
		if (current.repr() != 0 && current != setting) {
		if (log) {
		ALOGE("Interface being set with %s but it is already marked as %s.",
		stabilityString(stability).c_str(), stabilityString(currentStability).c_str());
		ALOGE("Interface being set with %s but it is already marked as %s",
		setting.debugString().c_str(),
		current.debugString().c_str());
		}
		return BAD_TYPE;
		}

		if (currentStability == stability) return OK;
		if (current == setting) return OK;

		BBinder* local = binder->localBinder();
		if (local != nullptr) {
		local->mStability = static_cast<int32_t>(stability);
		local->mStability = setting.repr();
		} else {
		binder->remoteBinder()->mStability = static_cast<int32_t>(stability);
		binder->remoteBinder()->mStability = setting.repr();
		}

		return OK;
		}

		Stability::Level Stability::get(IBinder* binder) {
		if (binder == nullptr) return UNDECLARED;
		Stability::Category Stability::getCategory(IBinder* binder) {
		if (binder == nullptr) {
		return Category::currentFromLevel(Level::UNDECLARED);
		}

		BBinder* local = binder->localBinder();
		if (local != nullptr) {
		return static_cast<Stability::Level>(local->mStability);
		return Category::fromRepr(local->mStability);
		}

		return static_cast<Stability::Level>(binder->remoteBinder()->mStability);
		return Category::fromRepr(binder->remoteBinder()->mStability);
		}

		bool Stability::check(int32_t provided, Level required) {
		bool stable = (provided & required) == required;
		bool Stability::check(Category provided, Level required) {
		bool stable = (provided.level & required) == required;

		if (!isDeclaredStability(provided) && provided != UNDECLARED) {
		ALOGE("Unknown stability when checking interface stability %d.", provided);
		if (provided.level != UNDECLARED && !isDeclaredLevel(provided.level)) {
		ALOGE("Unknown stability when checking interface stability %d.",
		provided.level);

		stable = false;
		}
		@@ -133,18 +176,18 @@ bool Stability::check(int32_t provided, Level required) {
		return stable;
		}

		bool Stability::isDeclaredStability(int32_t stability) {
		bool Stability::isDeclaredLevel(Level stability) {
		return stability == VENDOR \|\| stability == SYSTEM \|\| stability == VINTF;
		}

		std::string Stability::stabilityString(int32_t stability) {
		switch (stability) {
		std::string Stability::levelString(Level level) {
		switch (level) {
		case Level::UNDECLARED: return "undeclared stability";
		case Level::VENDOR: return "vendor stability";
		case Level::SYSTEM: return "system stability";
		case Level::VINTF: return "vintf stability";
		}
		return "unknown stability " + std::to_string(stability);
		return "unknown stability " + std::to_string(level);
		}

		} // namespace internal

libs/binder/include/binder/Stability.h

+65 −7

Original line number	Diff line number	Diff line
		@@ -26,6 +26,29 @@ class ProcessState;

		namespace internal {

		// Stability encodes how a binder changes over time. There are two levels of
		// stability:
		// 1). the interface stability - this is how a particular set of API calls (a
		// particular ordering of things like writeInt32/readInt32) are changed over
		// time. If one release, we have 'writeInt32' and the next release, we have
		// 'writeInt64', then this interface doesn't have a very stable
		// Stability::Level. Usually this ordering is controlled by a .aidl file.
		// 2). the wire format stability - this is how these API calls map to actual
		// bytes that are written to the wire (literally, this is how they are written
		// to the kernel inside of IBinder::transact, but it may be expanded to other
		// wires in the future). For instance, writeInt32 in binder translates to
		// writing a 4-byte little-endian integer in two's complement. You can imagine
		// in the future, we change writeInt32/readInt32 to instead write 8-bytes with
		// that integer and some check bits. In this case, the wire format changes,
		// but as long as a client libbinder knows to keep on writing a 4-byte value
		// to old servers, and new servers know how to interpret the 8-byte result,
		// they can still communicate.
		//
		// Every binder object has a stability level associated with it, and when
		// communicating with a binder, we make sure that the command we sent is one
		// that it knows how to process. The summary of stability of a binder is
		// represented by a Stability::Category object.

		// WARNING: These APIs are only ever expected to be called by auto-generated code.
		// Instead of calling them, you should set the stability of a .aidl interface
		class Stability final {
		@@ -73,7 +96,7 @@ private:

		static void tryMarkCompilationUnit(IBinder* binder);

		enum Level : int32_t {
		enum Level : uint8_t {
		UNDECLARED = 0,

		VENDOR = 0b000011,
		@@ -81,19 +104,54 @@ private:
		VINTF = 0b111111,
		};

		// This is the format of stability passed on the wire.
		struct Category {
		static inline Category fromRepr(int32_t representation) {
		return reinterpret_cast<Category>(&representation);
		}
		int32_t repr() const {
		return reinterpret_cast<const int32_t>(this);
		}
		static inline Category currentFromLevel(Level level);

		bool operator== (const Category& o) const {
		return repr() == o.repr();
		}
		bool operator!= (const Category& o) const {
		return !(*this == o);
		}

		std::string debugString();

		// This is the version of the wire protocol associated with the host
		// process of a particular binder. As the wire protocol changes, if
		// sending a transaction to a binder with an old version, the Parcel
		// class must write parcels according to the version documented here.
		uint8_t version;

		uint8_t reserved[2];

		// bitmask of Stability::Level
		Level level;
		};
		static_assert(sizeof(Category) == sizeof(int32_t));

		// returns the stability according to how this was built
		static Level getLocalStability();
		static Level getLocalLevel();

		// applies stability to binder if stability level is known
		__attribute__((warn_unused_result))
		static status_t set(IBinder* binder, int32_t stability, bool log);
		static status_t setRepr(IBinder* binder, int32_t representation, bool log);

		static Level get(IBinder* binder);
		// get stability information as encoded on the wire
		static Category getCategory(IBinder* binder);

		static bool check(int32_t provided, Level required);
		// whether a transaction on binder is allowed, if the transaction
		// is done from a context with a specific stability level
		static bool check(Category provided, Level required);

		static bool isDeclaredStability(int32_t stability);
		static std::string stabilityString(int32_t stability);
		static bool isDeclaredLevel(Level level);
		static std::string levelString(Level level);

		Stability();
		};