Merge "Reland: "init: chroot from recovery to /first_stage_ramdisk"" (88a1884d) · Commits · e / os / android_system_core

init/first_stage_mount.cpp

+2 −16

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@
		#include "first_stage_mount.h"

		#include <stdlib.h>
		#include <sys/mount.h>
		#include <unistd.h>

		#include <chrono>
		@@ -123,18 +124,8 @@ static inline bool IsDtVbmetaCompatible() {
		return is_android_dt_value_expected("vbmeta/compatible", "android,vbmeta");
		}

		static bool ForceNormalBoot() {
		static bool force_normal_boot = []() {
		std::string cmdline;
		android::base::ReadFileToString("/proc/cmdline", &cmdline);
		return cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;
		}();

		return force_normal_boot;
		}

		static bool IsRecoveryMode() {
		return !ForceNormalBoot() && access("/system/bin/recovery", F_OK) == 0;
		return access("/system/bin/recovery", F_OK) == 0;
		}

		// Class Definitions
		@@ -403,11 +394,6 @@ bool FirstStageMount::MountPartitions() {
		[](const auto& rec) { return rec->mount_point == "/system"s; });

		if (system_partition != mount_fstab_recs_.end()) {
		if (ForceNormalBoot()) {
		free((*system_partition)->mount_point);
		(*system_partition)->mount_point = strdup("/system_recovery_mount");
		}

		if (!MountPartition(*system_partition)) {
		return false;
		}

init/init_first_stage.cpp

+86 −0

Original line number	Diff line number	Diff line
		@@ -14,6 +14,8 @@
		* limitations under the License.
		*/

		#include <dirent.h>
		#include <fcntl.h>
		#include <paths.h>
		#include <stdlib.h>
		#include <sys/mount.h>
		@@ -26,19 +28,72 @@
		#include <vector>

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

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

		using android::base::boot_clock;

		using namespace std::literals;

		namespace android {
		namespace init {

		namespace {

		void FreeRamdisk(DIR* dir, dev_t dev) {
		int dfd = dirfd(dir);

		dirent* de;
		while ((de = readdir(dir)) != nullptr) {
		if (de->d_name == "."s \|\| de->d_name == ".."s) {
		continue;
		}

		bool is_dir = false;

		if (de->d_type == DT_DIR \|\| de->d_type == DT_UNKNOWN) {
		struct stat info;
		if (fstatat(dfd, de->d_name, &info, AT_SYMLINK_NOFOLLOW) != 0) {
		continue;
		}

		if (info.st_dev != dev) {
		continue;
		}

		if (S_ISDIR(info.st_mode)) {
		is_dir = true;
		auto fd = openat(dfd, de->d_name, O_RDONLY \| O_DIRECTORY);
		if (fd >= 0) {
		auto subdir =
		std::unique_ptr<DIR, decltype(&closedir)>{fdopendir(fd), closedir};
		if (subdir) {
		FreeRamdisk(subdir.get(), dev);
		} else {
		close(fd);
		}
		}
		}
		}
		unlinkat(dfd, de->d_name, is_dir ? AT_REMOVEDIR : 0);
		}
		}

		bool ForceNormalBoot() {
		std::string cmdline;
		android::base::ReadFileToString("/proc/cmdline", &cmdline);
		return cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;
		}

		} // namespace

		int main(int argc, char** argv) {
		if (REBOOT_BOOTLOADER_ON_PANIC) {
		InstallRebootSignalHandlers();
		@@ -117,10 +172,41 @@ int main(int argc, char** argv) {

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

		auto old_root_dir = std::unique_ptr<DIR, decltype(&closedir)>{opendir("/"), closedir};
		if (!old_root_dir) {
		PLOG(ERROR) << "Could not opendir(\"/\"), not freeing ramdisk";
		}

		struct stat old_root_info;
		if (stat("/", &old_root_info) != 0) {
		PLOG(ERROR) << "Could not stat(\"/\"), not freeing ramdisk";
		old_root_dir.reset();
		}

		if (ForceNormalBoot()) {
		mkdir("/first_stage_ramdisk", 0755);
		// SwitchRoot() must be called with a mount point as the target, so we bind mount the
		// target directory to itself here.
		if (mount("/first_stage_ramdisk", "/first_stage_ramdisk", nullptr, MS_BIND, nullptr) != 0) {
		LOG(FATAL) << "Could not bind mount /first_stage_ramdisk to itself";
		}
		SwitchRoot("/first_stage_ramdisk");
		}

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

		struct stat new_root_info;
		if (stat("/", &new_root_info) != 0) {
		PLOG(ERROR) << "Could not stat(\"/\"), not freeing ramdisk";
		old_root_dir.reset();
		}

		if (old_root_dir && old_root_info.st_dev != new_root_info.st_dev) {
		FreeRamdisk(old_root_dir.get(), old_root_info.st_dev);
		}

		SetInitAvbVersionInRecovery();

		static constexpr uint32_t kNanosecondsPerMillisecond = 1e6;

init/switch_root.cpp

+3 −55

Original line number	Diff line number	Diff line
		@@ -16,7 +16,6 @@

		#include "switch_root.h"

		#include <dirent.h>
		#include <fcntl.h>
		#include <mntent.h>
		#include <sys/mount.h>
		@@ -35,45 +34,6 @@ namespace init {

		namespace {

		void FreeRamdisk(DIR* dir, dev_t dev) {
		int dfd = dirfd(dir);

		dirent* de;
		while ((de = readdir(dir)) != nullptr) {
		if (de->d_name == "."s \|\| de->d_name == ".."s) {
		continue;
		}

		bool is_dir = false;

		if (de->d_type == DT_DIR \|\| de->d_type == DT_UNKNOWN) {
		struct stat info;
		if (fstatat(dfd, de->d_name, &info, AT_SYMLINK_NOFOLLOW) != 0) {
		continue;
		}

		if (info.st_dev != dev) {
		continue;
		}

		if (S_ISDIR(info.st_mode)) {
		is_dir = true;
		auto fd = openat(dfd, de->d_name, O_RDONLY \| O_DIRECTORY);
		if (fd >= 0) {
		auto subdir =
		std::unique_ptr<DIR, decltype(&closedir)>{fdopendir(fd), closedir};
		if (subdir) {
		FreeRamdisk(subdir.get(), dev);
		} else {
		close(fd);
		}
		}
		}
		}
		unlinkat(dfd, de->d_name, is_dir ? AT_REMOVEDIR : 0);
		}
		}

		std::vector<std::string> GetMounts(const std::string& new_root) {
		auto fp = std::unique_ptr<std::FILE, decltype(&endmntent)>{setmntent("/proc/mounts", "re"),
		endmntent};
		@@ -112,24 +72,16 @@ std::vector<std::string> GetMounts(const std::string& new_root) {
		void SwitchRoot(const std::string& new_root) {
		auto mounts = GetMounts(new_root);

		LOG(INFO) << "Switching root to '" << new_root << "'";

		for (const auto& mount_path : mounts) {
		auto new_mount_path = new_root + mount_path;
		mkdir(new_mount_path.c_str(), 0755);
		if (mount(mount_path.c_str(), new_mount_path.c_str(), nullptr, MS_MOVE, nullptr) != 0) {
		PLOG(FATAL) << "Unable to move mount at '" << mount_path << "'";
		}
		}

		auto old_root_dir = std::unique_ptr<DIR, decltype(&closedir)>{opendir("/"), closedir};
		if (!old_root_dir) {
		PLOG(ERROR) << "Could not opendir(\"/\"), not freeing ramdisk";
		}

		struct stat old_root_info;
		if (stat("/", &old_root_info) != 0) {
		PLOG(ERROR) << "Could not stat(\"/\"), not freeing ramdisk";
		old_root_dir.reset();
		}

		if (chdir(new_root.c_str()) != 0) {
		PLOG(FATAL) << "Could not chdir to new_root, '" << new_root << "'";
		}
		@@ -141,10 +93,6 @@ void SwitchRoot(const std::string& new_root) {
		if (chroot(".") != 0) {
		PLOG(FATAL) << "Unable to chroot to new root";
		}

		if (old_root_dir) {
		FreeRamdisk(old_root_dir.get(), old_root_info.st_dev);
		}
		}

		} // namespace init