Merge "ashmem: Ensure all memfds have non-executable permissions by default" into main (445d2e00) · Commits · e / os / android_system_core

libcutils/ashmem-dev.cpp

+14 −2

Original line number	Diff line number	Diff line
		@@ -114,8 +114,14 @@ static bool __has_memfd_support() {
		// Check if kernel support exists, otherwise fall back to ashmem.
		// This code needs to build on old API levels, so we can't use the libc
		// wrapper.
		//
		// MFD_NOEXEC_SEAL is used to match the semantics of the ashmem device,
		// which did not have executable permissions. This also seals the executable
		// permissions of the buffer (i.e. they cannot be changed by fchmod()).
		//
		// MFD_NOEXEC_SEAL implies MFD_ALLOW_SEALING.
		android::base::unique_fd fd(
		syscall(__NR_memfd_create, "test_android_memfd", MFD_CLOEXEC \| MFD_ALLOW_SEALING));
		syscall(__NR_memfd_create, "test_android_memfd", MFD_CLOEXEC \| MFD_NOEXEC_SEAL));
		if (fd == -1) {
		ALOGE("memfd_create failed: %s, no memfd support.\n", strerror(errno));
		return false;
		@@ -289,7 +295,13 @@ int ashmem_valid(int fd)
		static int memfd_create_region(const char* name, size_t size) {
		// This code needs to build on old API levels, so we can't use the libc
		// wrapper.
		android::base::unique_fd fd(syscall(__NR_memfd_create, name, MFD_CLOEXEC \| MFD_ALLOW_SEALING));
		//
		// MFD_NOEXEC_SEAL to match the semantics of the ashmem device, which did
		// not have executable permissions. This also seals the executable
		// permissions of the buffer (i.e. they cannot be changed by fchmod()).
		//
		// MFD_NOEXEC_SEAL implies MFD_ALLOW_SEALING.
		android::base::unique_fd fd(syscall(__NR_memfd_create, name, MFD_CLOEXEC \| MFD_NOEXEC_SEAL));

		if (fd == -1) {
		ALOGE("memfd_create(%s, %zd) failed: %s\n", name, size, strerror(errno));