Merge "Split fork and specialize in zygote" (f40f0522) · Commits · e / os / android_frameworks_base

core/jni/com_android_internal_os_Zygote.cpp

+219 −196

Original line number	Diff line number	Diff line
		@@ -535,20 +535,14 @@ static bool FillFileDescriptorVector(JNIEnv* env,
		return true;
		}

		// Utility routine to fork zygote and specialize the child process.
		static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids,
		// Utility routine to specialize a zygote child process.
		static void SpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArray javaGids,
		jint runtime_flags, jobjectArray javaRlimits,
		jlong permittedCapabilities, jlong effectiveCapabilities,
		jint mount_external,
		jstring java_se_info, jstring java_se_name,
		bool is_system_server, jintArray fdsToClose,
		jintArray fdsToIgnore, bool is_child_zygote,
		jstring instructionSet, jstring dataDir) {
		SetSignalHandlers();

		sigset_t sigchld;
		sigemptyset(&sigchld);
		sigaddset(&sigchld, SIGCHLD);
		jint mount_external, jstring java_se_info, jstring java_se_name,
		bool is_system_server, bool is_child_zygote, jstring instructionSet,
		jstring dataDir) {
		std::string error_msg;

		auto fail_fn = [env, java_se_name, is_system_server](const std::string& msg)
		__attribute__ ((noreturn)) {
		@@ -568,57 +562,6 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
		__builtin_unreachable();
		};

		// Temporarily block SIGCHLD during forks. The SIGCHLD handler might
		// log, which would result in the logging FDs we close being reopened.
		// This would cause failures because the FDs are not whitelisted.
		//
		// Note that the zygote process is single threaded at this point.
		if (sigprocmask(SIG_BLOCK, &sigchld, nullptr) == -1) {
		fail_fn(CREATE_ERROR("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)));
		}

		// Close any logging related FDs before we start evaluating the list of
		// file descriptors.
		__android_log_close();

		std::string error_msg;

		// If this is the first fork for this zygote, create the open FD table.
		// If it isn't, we just need to check whether the list of open files has
		// changed (and it shouldn't in the normal case).
		std::vector<int> fds_to_ignore;
		if (!FillFileDescriptorVector(env, fdsToIgnore, &fds_to_ignore, &error_msg)) {
		fail_fn(error_msg);
		}
		if (gOpenFdTable == NULL) {
		gOpenFdTable = FileDescriptorTable::Create(fds_to_ignore, &error_msg);
		if (gOpenFdTable == NULL) {
		fail_fn(error_msg);
		}
		} else if (!gOpenFdTable->Restat(fds_to_ignore, &error_msg)) {
		fail_fn(error_msg);
		}

		pid_t pid = fork();

		if (pid == 0) {
		PreApplicationInit();

		// Clean up any descriptors which must be closed immediately
		if (!DetachDescriptors(env, fdsToClose, &error_msg)) {
		fail_fn(error_msg);
		}

		// Re-open all remaining open file descriptors so that they aren't shared
		// with the zygote across a fork.
		if (!gOpenFdTable->ReopenOrDetach(&error_msg)) {
		fail_fn(error_msg);
		}

		if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) {
		fail_fn(CREATE_ERROR("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)));
		}

		// Keep capabilities across UID change, unless we're staying root.
		if (uid != 0) {
		if (!EnableKeepCapabilities(&error_msg)) {
		@@ -667,12 +610,11 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
		if (rc == -EROFS) {
		ALOGW("createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?");
		} else {
		ALOGE("createProcessGroup(%d, %d) failed: %s", uid, pid, strerror(-rc));
		ALOGE("createProcessGroup(%d, %d) failed: %s", uid, 0/pid/, strerror(-rc));
		}
		}
		}

		std::string error_msg;
		if (!SetGids(env, javaGids, &error_msg)) {
		fail_fn(error_msg);
		}
		@@ -786,14 +728,90 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
		if (env->ExceptionCheck()) {
		fail_fn("Error calling post fork hooks.");
		}
		} else if (pid > 0) {
		// the parent process
		}

		// Utility routine to fork zygote and specialize the child process.
		static pid_t ForkCommon(JNIEnv* env, jstring java_se_name, bool is_system_server,
		jintArray fdsToClose, jintArray fdsToIgnore) {
		SetSignalHandlers();

		// Block SIGCHLD prior to fork.
		sigset_t sigchld;
		sigemptyset(&sigchld);
		sigaddset(&sigchld, SIGCHLD);

		auto fail_fn = [env, java_se_name, is_system_server](const std::string& msg)
		__attribute__ ((noreturn)) {
		const char* se_name_c_str = nullptr;
		std::unique_ptr<ScopedUtfChars> se_name;
		if (java_se_name != nullptr) {
		se_name.reset(new ScopedUtfChars(env, java_se_name));
		se_name_c_str = se_name->c_str();
		}
		if (se_name_c_str == nullptr && is_system_server) {
		se_name_c_str = "system_server";
		}
		const std::string& error_msg = (se_name_c_str == nullptr)
		? msg
		: StringPrintf("(%s) %s", se_name_c_str, msg.c_str());
		env->FatalError(error_msg.c_str());
		__builtin_unreachable();
		};

		// Temporarily block SIGCHLD during forks. The SIGCHLD handler might
		// log, which would result in the logging FDs we close being reopened.
		// This would cause failures because the FDs are not whitelisted.
		//
		// Note that the zygote process is single threaded at this point.
		if (sigprocmask(SIG_BLOCK, &sigchld, nullptr) == -1) {
		fail_fn(CREATE_ERROR("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)));
		}

		// Close any logging related FDs before we start evaluating the list of
		// file descriptors.
		__android_log_close();

		std::string error_msg;

		// If this is the first fork for this zygote, create the open FD table.
		// If it isn't, we just need to check whether the list of open files has
		// changed (and it shouldn't in the normal case).
		std::vector<int> fds_to_ignore;
		if (!FillFileDescriptorVector(env, fdsToIgnore, &fds_to_ignore, &error_msg)) {
		fail_fn(error_msg);
		}
		if (gOpenFdTable == NULL) {
		gOpenFdTable = FileDescriptorTable::Create(fds_to_ignore, &error_msg);
		if (gOpenFdTable == NULL) {
		fail_fn(error_msg);
		}
		} else if (!gOpenFdTable->Restat(fds_to_ignore, &error_msg)) {
		fail_fn(error_msg);
		}

		pid_t pid = fork();

		if (pid == 0) {
		// The child process.
		PreApplicationInit();

		// Clean up any descriptors which must be closed immediately
		if (!DetachDescriptors(env, fdsToClose, &error_msg)) {
		fail_fn(error_msg);
		}

		// Re-open all remaining open file descriptors so that they aren't shared
		// with the zygote across a fork.
		if (!gOpenFdTable->ReopenOrDetach(&error_msg)) {
		fail_fn(error_msg);
		}
		}

		// We blocked SIGCHLD prior to a fork, we unblock it here.
		if (sigprocmask(SIG_UNBLOCK, &sigchld, nullptr) == -1) {
		fail_fn(CREATE_ERROR("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno)));
		}
		}

		return pid;
		}

		@@ -879,22 +897,27 @@ static jint com_android_internal_os_Zygote_nativeForkAndSpecialize(
		// available.
		capabilities &= GetEffectiveCapabilityMask(env);

		return ForkAndSpecializeCommon(env, uid, gid, gids, runtime_flags,
		rlimits, capabilities, capabilities, mount_external, se_info,
		se_name, false, fdsToClose, fdsToIgnore, is_child_zygote == JNI_TRUE,
		instructionSet, appDataDir);
		pid_t pid = ForkCommon(env, se_name, false, fdsToClose, fdsToIgnore);
		if (pid == 0) {
		SpecializeCommon(env, uid, gid, gids, runtime_flags, rlimits,
		capabilities, capabilities,
		mount_external, se_info, se_name, false,
		is_child_zygote == JNI_TRUE, instructionSet, appDataDir);
		}
		return pid;
		}

		static jint com_android_internal_os_Zygote_nativeForkSystemServer(
		JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids,
		jint runtime_flags, jobjectArray rlimits, jlong permittedCapabilities,
		jlong effectiveCapabilities) {
		pid_t pid = ForkAndSpecializeCommon(env, uid, gid, gids,
		runtime_flags, rlimits,
		pid_t pid = ForkCommon(env, NULL, true, NULL, NULL);
		if (pid == 0) {
		SpecializeCommon(env, uid, gid, gids, runtime_flags, rlimits,
		permittedCapabilities, effectiveCapabilities,
		MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true, NULL,
		NULL, false, NULL, NULL);
		if (pid > 0) {
		MOUNT_EXTERNAL_DEFAULT, NULL, NULL, true,
		false, NULL, NULL);
		} else if (pid > 0) {
		// The zygote process checks whether the child process has died or not.
		ALOGI("System server process %d has been created", pid);
		gSystemServerPid = pid;