Split init's source files init first stage and second stage (44aceed0) · Commits · e / os / android_system_core

init/Android.bp

+2 −0

Original line number	Diff line number	Diff line
		@@ -107,6 +107,7 @@ cc_library_static {
		"first_stage_mount.cpp",
		"import_parser.cpp",
		"init.cpp",
		"init_first_stage.cpp",
		"keychords.cpp",
		"modalias_handler.cpp",
		"parser.cpp",
		@@ -115,6 +116,7 @@ cc_library_static {
		"property_service.cpp",
		"property_type.cpp",
		"reboot.cpp",
		"reboot_utils.cpp",
		"security.cpp",
		"selinux.cpp",
		"service.cpp",

init/init.cpp

+7 −151

Original line number	Diff line number	Diff line
		@@ -18,15 +18,12 @@

		#include <dirent.h>
		#include <fcntl.h>
		#include <paths.h>
		#include <pthread.h>
		#include <seccomp_policy.h>
		#include <signal.h>
		#include <stdlib.h>
		#include <string.h>
		#include <sys/mount.h>
		#include <sys/signalfd.h>
		#include <sys/sysmacros.h>
		#include <sys/types.h>
		#include <unistd.h>

		@@ -43,8 +40,6 @@
		#include <cutils/android_reboot.h>
		#include <keyutils.h>
		#include <libavb/libavb.h>
		#include <private/android_filesystem_config.h>
		#include <selinux/android.h>

		#include "action_parser.h"
		#include "epoll.h"
		@@ -53,6 +48,7 @@
		#include "keychords.h"
		#include "property_service.h"
		#include "reboot.h"
		#include "reboot_utils.h"
		#include "security.h"
		#include "selinux.h"
		#include "sigchld_handler.h"
		@@ -417,14 +413,6 @@ static Result<Success> queue_property_triggers_action(const BuiltinArguments& ar
		return Success();
		}

		static void global_seccomp() {
		import_kernel_cmdline(false, [](const std::string& key, const std::string& value, bool in_qemu) {
		if (key == "androidboot.seccomp" && value == "global" && !set_global_seccomp_filter()) {
		LOG(FATAL) << "Failed to globally enable seccomp!";
		}
		});
		}

		// Set the UDC controller for the ConfigFS USB Gadgets.
		// Read the UDC controller in use from "/sys/class/udc".
		// In case of multiple UDC controllers select the first one.
		@@ -441,40 +429,6 @@ static void set_usb_controller() {
		}
		}

		static void InstallRebootSignalHandlers() {
		// Instead of panic'ing the kernel as is the default behavior when init crashes,
		// we prefer to reboot to bootloader on development builds, as this will prevent
		// boot looping bad configurations and allow both developers and test farms to easily
		// recover.
		struct sigaction action;
		memset(&action, 0, sizeof(action));
		sigfillset(&action.sa_mask);
		action.sa_handler = [](int signal) {
		// These signal handlers are also caught for processes forked from init, however we do not
		// want them to trigger reboot, so we directly call _exit() for children processes here.
		if (getpid() != 1) {
		_exit(signal);
		}

		// Calling DoReboot() or LOG(FATAL) is not a good option as this is a signal handler.
		// RebootSystem uses syscall() which isn't actually async-signal-safe, but our only option
		// and probably good enough given this is already an error case and only enabled for
		// development builds.
		RebootSystem(ANDROID_RB_RESTART2, "bootloader");
		};
		action.sa_flags = SA_RESTART;
		sigaction(SIGABRT, &action, nullptr);
		sigaction(SIGBUS, &action, nullptr);
		sigaction(SIGFPE, &action, nullptr);
		sigaction(SIGILL, &action, nullptr);
		sigaction(SIGSEGV, &action, nullptr);
		#if defined(SIGSTKFLT)
		sigaction(SIGSTKFLT, &action, nullptr);
		#endif
		sigaction(SIGSYS, &action, nullptr);
		sigaction(SIGTRAP, &action, nullptr);
		}

		static void HandleSigtermSignal(const signalfd_siginfo& siginfo) {
		if (siginfo.ssi_pid != 0) {
		// Drop any userspace SIGTERM requests.
		@@ -611,6 +565,8 @@ static void InitKernelLogging(char* argv[]) {
		android::base::InitLogging(argv, &android::base::KernelLogger, InitAborter);
		}

		int first_stage_main(int argc, char** argv);

		int main(int argc, char** argv) {
		if (!strcmp(basename(argv[0]), "ueventd")) {
		return ueventd_main(argc, argv);
		@@ -622,114 +578,14 @@ int main(int argc, char** argv) {
		return SubcontextMain(argc, argv, &function_map);
		}

		if (REBOOT_BOOTLOADER_ON_PANIC) {
		InstallRebootSignalHandlers();
		}

		bool is_first_stage = (getenv("INIT_SECOND_STAGE") == nullptr);

		if (is_first_stage) {
		boot_clock::time_point start_time = boot_clock::now();

		std::vector<std::pair<std::string, int>> errors;
		#define CHECKCALL(x) \
		if (x != 0) errors.emplace_back(#x " failed", errno);

		// Clear the umask.
		umask(0);

		CHECKCALL(clearenv());
		CHECKCALL(setenv("PATH", _PATH_DEFPATH, 1));
		// Get the basic filesystem setup we need put together in the initramdisk
		// on / and then we'll let the rc file figure out the rest.
		CHECKCALL(mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755"));
		CHECKCALL(mkdir("/dev/pts", 0755));
		CHECKCALL(mkdir("/dev/socket", 0755));
		CHECKCALL(mount("devpts", "/dev/pts", "devpts", 0, NULL));
		#define MAKE_STR(x) __STRING(x)
		CHECKCALL(mount("proc", "/proc", "proc", 0, "hidepid=2,gid=" MAKE_STR(AID_READPROC)));
		#undef MAKE_STR
		// Don't expose the raw commandline to unprivileged processes.
		CHECKCALL(chmod("/proc/cmdline", 0440));
		gid_t groups[] = { AID_READPROC };
		CHECKCALL(setgroups(arraysize(groups), groups));
		CHECKCALL(mount("sysfs", "/sys", "sysfs", 0, NULL));
		CHECKCALL(mount("selinuxfs", "/sys/fs/selinux", "selinuxfs", 0, NULL));

		CHECKCALL(mknod("/dev/kmsg", S_IFCHR \| 0600, makedev(1, 11)));

		if constexpr (WORLD_WRITABLE_KMSG) {
		CHECKCALL(mknod("/dev/kmsg_debug", S_IFCHR \| 0622, makedev(1, 11)));
		}

		CHECKCALL(mknod("/dev/random", S_IFCHR \| 0666, makedev(1, 8)));
		CHECKCALL(mknod("/dev/urandom", S_IFCHR \| 0666, makedev(1, 9)));

		// This is needed for log wrapper, which gets called before ueventd runs.
		CHECKCALL(mknod("/dev/ptmx", S_IFCHR \| 0666, makedev(5, 2)));
		CHECKCALL(mknod("/dev/null", S_IFCHR \| 0666, makedev(1, 3)));

		// Mount staging areas for devices managed by vold
		// See storage config details at http://source.android.com/devices/storage/
		CHECKCALL(mount("tmpfs", "/mnt", "tmpfs", MS_NOEXEC \| MS_NOSUID \| MS_NODEV,
		"mode=0755,uid=0,gid=1000"));
		// /mnt/vendor is used to mount vendor-specific partitions that can not be
		// part of the vendor partition, e.g. because they are mounted read-write.
		CHECKCALL(mkdir("/mnt/vendor", 0755));
		// /mnt/product is used to mount product-specific partitions that can not be
		// part of the product partition, e.g. because they are mounted read-write.
		CHECKCALL(mkdir("/mnt/product", 0755));

		#undef CHECKCALL

		// Now that tmpfs is mounted on /dev and we have /dev/kmsg, we can actually
		// talk to the outside world...
		InitKernelLogging(argv);

		if (!errors.empty()) {
		for (const auto& [error_string, error_errno] : errors) {
		LOG(ERROR) << error_string << " " << strerror(error_errno);
		}
		LOG(FATAL) << "Init encountered errors starting first stage, aborting";
		}

		LOG(INFO) << "init first stage started!";

		if (!DoFirstStageMount()) {
		LOG(FATAL) << "Failed to mount required partitions early ...";
		}

		SetInitAvbVersionInRecovery();

		// Enable seccomp if global boot option was passed (otherwise it is enabled in zygote).
		global_seccomp();

		// Set up SELinux, loading the SELinux policy.
		SelinuxSetupKernelLogging();
		SelinuxInitialize();

		// We're in the kernel domain, so re-exec init to transition to the init domain now
		// that the SELinux policy has been loaded.
		if (selinux_android_restorecon("/init", 0) == -1) {
		PLOG(FATAL) << "restorecon failed of /init failed";
		if (getenv("INIT_SECOND_STAGE") == nullptr) {
		return first_stage_main(argc, argv);
		}

		setenv("INIT_SECOND_STAGE", "true", 1);

		static constexpr uint32_t kNanosecondsPerMillisecond = 1e6;
		uint64_t start_ms = start_time.time_since_epoch().count() / kNanosecondsPerMillisecond;
		setenv("INIT_STARTED_AT", std::to_string(start_ms).c_str(), 1);

		char* path = argv[0];
		char* args[] = { path, nullptr };
		execv(path, args);

		// execv() only returns if an error happened, in which case we
		// panic and never fall through this conditional.
		PLOG(FATAL) << "execv(\"" << path << "\") failed";
		if (REBOOT_BOOTLOADER_ON_PANIC) {
		InstallRebootSignalHandlers();
		}

		// At this point we're in the second stage of init.
		InitKernelLogging(argv);
		LOG(INFO) << "init second stage started!";

init/init_first_stage.cpp

0 → 100644

+166 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2018 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#include <paths.h>
		#include <seccomp_policy.h>
		#include <stdlib.h>
		#include <sys/mount.h>
		#include <sys/stat.h>
		#include <sys/sysmacros.h>
		#include <sys/types.h>
		#include <unistd.h>

		#include <string>
		#include <vector>

		#include <android-base/chrono_utils.h>
		#include <android-base/logging.h>
		#include <cutils/android_reboot.h>
		#include <private/android_filesystem_config.h>
		#include <selinux/android.h>

		#include "first_stage_mount.h"
		#include "reboot_utils.h"
		#include "selinux.h"
		#include "util.h"

		using android::base::boot_clock;

		namespace android {
		namespace init {

		static void GlobalSeccomp() {
		import_kernel_cmdline(false, [](const std::string& key, const std::string& value,
		bool in_qemu) {
		if (key == "androidboot.seccomp" && value == "global" && !set_global_seccomp_filter()) {
		LOG(FATAL) << "Failed to globally enable seccomp!";
		}
		});
		}

		int first_stage_main(int argc, char** argv) {
		if (REBOOT_BOOTLOADER_ON_PANIC) {
		InstallRebootSignalHandlers();
		}

		boot_clock::time_point start_time = boot_clock::now();

		std::vector<std::pair<std::string, int>> errors;
		#define CHECKCALL(x) \
		if (x != 0) errors.emplace_back(#x " failed", errno);

		// Clear the umask.
		umask(0);

		CHECKCALL(clearenv());
		CHECKCALL(setenv("PATH", _PATH_DEFPATH, 1));
		// Get the basic filesystem setup we need put together in the initramdisk
		// on / and then we'll let the rc file figure out the rest.
		CHECKCALL(mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755"));
		CHECKCALL(mkdir("/dev/pts", 0755));
		CHECKCALL(mkdir("/dev/socket", 0755));
		CHECKCALL(mount("devpts", "/dev/pts", "devpts", 0, NULL));
		#define MAKE_STR(x) __STRING(x)
		CHECKCALL(mount("proc", "/proc", "proc", 0, "hidepid=2,gid=" MAKE_STR(AID_READPROC)));
		#undef MAKE_STR
		// Don't expose the raw commandline to unprivileged processes.
		CHECKCALL(chmod("/proc/cmdline", 0440));
		gid_t groups[] = {AID_READPROC};
		CHECKCALL(setgroups(arraysize(groups), groups));
		CHECKCALL(mount("sysfs", "/sys", "sysfs", 0, NULL));
		CHECKCALL(mount("selinuxfs", "/sys/fs/selinux", "selinuxfs", 0, NULL));

		CHECKCALL(mknod("/dev/kmsg", S_IFCHR \| 0600, makedev(1, 11)));

		if constexpr (WORLD_WRITABLE_KMSG) {
		CHECKCALL(mknod("/dev/kmsg_debug", S_IFCHR \| 0622, makedev(1, 11)));
		}

		CHECKCALL(mknod("/dev/random", S_IFCHR \| 0666, makedev(1, 8)));
		CHECKCALL(mknod("/dev/urandom", S_IFCHR \| 0666, makedev(1, 9)));

		// This is needed for log wrapper, which gets called before ueventd runs.
		CHECKCALL(mknod("/dev/ptmx", S_IFCHR \| 0666, makedev(5, 2)));
		CHECKCALL(mknod("/dev/null", S_IFCHR \| 0666, makedev(1, 3)));

		// Mount staging areas for devices managed by vold
		// See storage config details at http://source.android.com/devices/storage/
		CHECKCALL(mount("tmpfs", "/mnt", "tmpfs", MS_NOEXEC \| MS_NOSUID \| MS_NODEV,
		"mode=0755,uid=0,gid=1000"));
		// /mnt/vendor is used to mount vendor-specific partitions that can not be
		// part of the vendor partition, e.g. because they are mounted read-write.
		CHECKCALL(mkdir("/mnt/vendor", 0755));
		// /mnt/product is used to mount product-specific partitions that can not be
		// part of the product partition, e.g. because they are mounted read-write.
		CHECKCALL(mkdir("/mnt/product", 0755));

		#undef CHECKCALL

		// Now that tmpfs is mounted on /dev and we have /dev/kmsg, we can actually
		// talk to the outside world...
		android::base::InitLogging(argv, &android::base::KernelLogger, [](const char*) {
		RebootSystem(ANDROID_RB_RESTART2, "bootloader");
		});

		if (!errors.empty()) {
		for (const auto& [error_string, error_errno] : errors) {
		LOG(ERROR) << error_string << " " << strerror(error_errno);
		}
		LOG(FATAL) << "Init encountered errors starting first stage, aborting";
		}

		LOG(INFO) << "init first stage started!";

		if (!DoFirstStageMount()) {
		LOG(FATAL) << "Failed to mount required partitions early ...";
		}

		SetInitAvbVersionInRecovery();

		// Does this need to be done in first stage init or can it be done later?
		// Enable seccomp if global boot option was passed (otherwise it is enabled in zygote).
		GlobalSeccomp();

		// Set up SELinux, loading the SELinux policy.
		SelinuxSetupKernelLogging();
		SelinuxInitialize();

		// Unneeded? It's an ext4 file system so shouldn't it have the right domain already?
		// We're in the kernel domain, so re-exec init to transition to the init domain now
		// that the SELinux policy has been loaded.
		if (selinux_android_restorecon("/init", 0) == -1) {
		PLOG(FATAL) << "restorecon failed of /init failed";
		}

		setenv("INIT_SECOND_STAGE", "true", 1);

		static constexpr uint32_t kNanosecondsPerMillisecond = 1e6;
		uint64_t start_ms = start_time.time_since_epoch().count() / kNanosecondsPerMillisecond;
		setenv("INIT_STARTED_AT", std::to_string(start_ms).c_str(), 1);

		const char* path = argv[0];
		const char* args[] = {path, nullptr};
		execv(path, const_cast<char**>(args));

		// execv() only returns if an error happened, in which case we
		// panic and never fall through this conditional.
		PLOG(FATAL) << "execv(\"" << path << "\") failed";

		return 1;
		}

		} // namespace init
		} // namespace android

init/reboot.cpp

+10 −53

Original line number	Diff line number	Diff line
		@@ -20,11 +20,9 @@
		#include <fcntl.h>
		#include <linux/fs.h>
		#include <mntent.h>
		#include <sys/capability.h>
		#include <sys/cdefs.h>
		#include <sys/ioctl.h>
		#include <sys/mount.h>
		#include <sys/reboot.h>
		#include <sys/stat.h>
		#include <sys/syscall.h>
		#include <sys/types.h>
		@@ -51,9 +49,9 @@
		#include <selinux/selinux.h>

		#include "action_manager.h"
		#include "capabilities.h"
		#include "init.h"
		#include "property_service.h"
		#include "reboot_utils.h"
		#include "service.h"
		#include "sigchld_handler.h"

		@@ -159,54 +157,6 @@ static void LogShutdownTime(UmountStat stat, Timer* t) {
		<< stat;
		}

		bool IsRebootCapable() {
		if (!CAP_IS_SUPPORTED(CAP_SYS_BOOT)) {
		PLOG(WARNING) << "CAP_SYS_BOOT is not supported";
		return true;
		}

		ScopedCaps caps(cap_get_proc());
		if (!caps) {
		PLOG(WARNING) << "cap_get_proc() failed";
		return true;
		}

		cap_flag_value_t value = CAP_SET;
		if (cap_get_flag(caps.get(), CAP_SYS_BOOT, CAP_EFFECTIVE, &value) != 0) {
		PLOG(WARNING) << "cap_get_flag(CAP_SYS_BOOT, EFFECTIVE) failed";
		return true;
		}
		return value == CAP_SET;
		}

		void __attribute__((noreturn)) RebootSystem(unsigned int cmd, const std::string& rebootTarget) {
		LOG(INFO) << "Reboot ending, jumping to kernel";

		if (!IsRebootCapable()) {
		// On systems where init does not have the capability of rebooting the
		// device, just exit cleanly.
		exit(0);
		}

		switch (cmd) {
		case ANDROID_RB_POWEROFF:
		reboot(RB_POWER_OFF);
		break;

		case ANDROID_RB_RESTART2:
		syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
		LINUX_REBOOT_CMD_RESTART2, rebootTarget.c_str());
		break;

		case ANDROID_RB_THERMOFF:
		reboot(RB_POWER_OFF);
		break;
		}
		// In normal case, reboot should not return.
		PLOG(ERROR) << "reboot call returned";
		abort();
		}

		/* Find all read+write block devices and emulated devices in /proc/mounts
		* and add them to correpsponding list.
		*/
		@@ -329,7 +279,14 @@ static UmountStat TryUmountAndFsck(bool runFsck, std::chrono::milliseconds timeo
		return stat;
		}

		void DoReboot(unsigned int cmd, const std::string& reason, const std::string& rebootTarget,
		//* Reboot / shutdown the system.
		// cmd ANDROID_RB_* as defined in android_reboot.h
		// reason Reason string like "reboot", "shutdown,userrequested"
		// rebootTarget Reboot target string like "bootloader". Otherwise, it should be an
		// empty string.
		// runFsck Whether to run fsck after umount is done.
		//
		static void DoReboot(unsigned int cmd, const std::string& reason, const std::string& rebootTarget,
		bool runFsck) {
		Timer t;
		LOG(INFO) << "Reboot start, reason: " << reason << ", rebootTarget: " << rebootTarget;

init/reboot.h

+0 −17

Original line number	Diff line number	Diff line
		@@ -22,26 +22,9 @@
		namespace android {
		namespace init {

		// This is a wrapper around the actual reboot calls. DoReboot() should be preferred in most cases.
		void __attribute__((noreturn)) RebootSystem(unsigned int cmd, const std::string& rebootTarget);

		/* Reboot / shutdown the system.
		* cmd ANDROID_RB_* as defined in android_reboot.h
		* reason Reason string like "reboot", "shutdown,userrequested"
		* rebootTarget Reboot target string like "bootloader". Otherwise, it should be an
		* empty string.
		* runFsck Whether to run fsck after umount is done.
		*/
		void DoReboot(unsigned int cmd, const std::string& reason, const std::string& rebootTarget,
		bool runFsck) __attribute__((__noreturn__));

		// Parses and handles a setprop sys.powerctl message.
		bool HandlePowerctlMessage(const std::string& command);

		// Determines whether the system is capable of rebooting. This is conservative,
		// so if any of the attempts to determine this fail, it will still return true.
		bool IsRebootCapable();

		} // namespace init
		} // namespace android