Merge "Let the kernel hwrng thread manage hw_random mixing." (b363fc8b) · Commits · e / os / android_system_core

init/init.cpp

+0 −5

Original line number	Diff line number	Diff line
		@@ -902,7 +902,6 @@ int SecondStageMain(int argc, char** argv) {
		am.QueueBuiltinAction(wait_for_coldboot_done_action, "wait_for_coldboot_done");
		am.QueueBuiltinAction(TransitionSnapuserdAction, "TransitionSnapuserd");
		// ... so that we can start queuing up actions that require stuff from /dev.
		am.QueueBuiltinAction(MixHwrngIntoLinuxRngAction, "MixHwrngIntoLinuxRng");
		am.QueueBuiltinAction(SetMmapRndBitsAction, "SetMmapRndBits");
		Keychords keychords;
		am.QueueBuiltinAction(
		@@ -918,10 +917,6 @@ int SecondStageMain(int argc, char** argv) {
		// Trigger all the boot actions to get us started.
		am.QueueEventTrigger("init");

		// Repeat mix_hwrng_into_linux_rng in case /dev/hw_random or /dev/random
		// wasn't ready immediately after wait_for_coldboot_done
		am.QueueBuiltinAction(MixHwrngIntoLinuxRngAction, "MixHwrngIntoLinuxRng");

		// Don't mount filesystems or start core system services in charger mode.
		std::string bootmode = GetProperty("ro.bootmode", "");
		if (bootmode == "charger") {

init/security.cpp

+0 −53

Original line number	Diff line number	Diff line
		@@ -36,59 +36,6 @@ using android::base::SetProperty;
		namespace android {
		namespace init {

		// Writes 512 bytes of output from Hardware RNG (/dev/hw_random, backed
		// by Linux kernel's hw_random framework) into Linux RNG's via /dev/urandom.
		// Does nothing if Hardware RNG is not present.
		//
		// Since we don't yet trust the quality of Hardware RNG, these bytes are not
		// mixed into the primary pool of Linux RNG and the entropy estimate is left
		// unmodified.
		//
		// If the HW RNG device /dev/hw_random is present, we require that at least
		// 512 bytes read from it are written into Linux RNG. QA is expected to catch
		// devices/configurations where these I/O operations are blocking for a long
		// time. We do not reboot or halt on failures, as this is a best-effort
		// attempt.
		Result<void> MixHwrngIntoLinuxRngAction(const BuiltinArguments&) {
		unique_fd hwrandom_fd(
		TEMP_FAILURE_RETRY(open("/dev/hw_random", O_RDONLY \| O_NOFOLLOW \| O_CLOEXEC)));
		if (hwrandom_fd == -1) {
		if (errno == ENOENT) {
		LOG(INFO) << "/dev/hw_random not found";
		// It's not an error to not have a Hardware RNG.
		return {};
		}
		return ErrnoError() << "Failed to open /dev/hw_random";
		}

		unique_fd urandom_fd(
		TEMP_FAILURE_RETRY(open("/dev/urandom", O_WRONLY \| O_NOFOLLOW \| O_CLOEXEC)));
		if (urandom_fd == -1) {
		return ErrnoError() << "Failed to open /dev/urandom";
		}

		char buf[512];
		size_t total_bytes_written = 0;
		while (total_bytes_written < sizeof(buf)) {
		ssize_t chunk_size =
		TEMP_FAILURE_RETRY(read(hwrandom_fd, buf, sizeof(buf) - total_bytes_written));
		if (chunk_size == -1) {
		return ErrnoError() << "Failed to read from /dev/hw_random";
		} else if (chunk_size == 0) {
		return Error() << "Failed to read from /dev/hw_random: EOF";
		}

		chunk_size = TEMP_FAILURE_RETRY(write(urandom_fd, buf, chunk_size));
		if (chunk_size == -1) {
		return ErrnoError() << "Failed to write to /dev/urandom";
		}
		total_bytes_written += chunk_size;
		}

		LOG(INFO) << "Mixed " << total_bytes_written << " bytes from /dev/hw_random into /dev/urandom";
		return {};
		}

		static bool SetHighestAvailableOptionValue(const std::string& path, int min, int max) {
		std::ifstream inf(path, std::fstream::in);
		if (!inf) {

init/security.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -26,7 +26,6 @@
		namespace android {
		namespace init {

		Result<void> MixHwrngIntoLinuxRngAction(const BuiltinArguments&);
		Result<void> SetMmapRndBitsAction(const BuiltinArguments&);
		Result<void> SetKptrRestrictAction(const BuiltinArguments&);
		Result<void> TestPerfEventSelinuxAction(const BuiltinArguments&);