Bionic libs and the dynamic linker are bind mounted am: 2599088ff6 am: 82a0d5be74 (91894745) · Commits · e / os / android_system_core

init/builtins.cpp

+82 −0

Original line number	Diff line number	Diff line
		@@ -1093,6 +1093,86 @@ static Result<Success> do_parse_apex_configs(const BuiltinArguments& args) {
		}
		}

		static Result<Success> bind_mount_file(const char* source, const char* mount_point,
		bool remount_private) {
		if (remount_private && mount(nullptr, mount_point, nullptr, MS_PRIVATE, nullptr) == -1) {
		return ErrnoError() << "Could not change " << mount_point << " to a private mount point";
		}
		if (mount(source, mount_point, nullptr, MS_BIND, nullptr) == -1) {
		return ErrnoError() << "Could not bind-mount " << source << " to " << mount_point;
		}
		return Success();
		}

		static Result<Success> bind_mount_bionic(const char* linker_source, const char* lib_dir_source,
		const char* linker_mount_point, const char* lib_mount_dir,
		bool remount_private) {
		if (access(linker_source, F_OK) != 0) {
		return Success();
		}
		if (auto result = bind_mount_file(linker_source, linker_mount_point, remount_private);
		!result) {
		return result;
		}
		for (auto libname : kBionicLibFileNames) {
		std::string mount_point = lib_mount_dir + libname;
		std::string source = lib_dir_source + libname;
		if (auto result = bind_mount_file(source.c_str(), mount_point.c_str(), remount_private);
		!result) {
		return result;
		}
		}
		return Success();
		}

		// The bootstrap bionic libs and the bootstrap linker are bind-mounted to
		// the mount points for pre-apexd processes.
		static Result<Success> do_prepare_bootstrap_bionic(const BuiltinArguments& args) {
		static bool prepare_bootstrap_bionic_done = false;
		if (prepare_bootstrap_bionic_done) {
		return Error() << "prepare_bootstrap_bionic was already executed. Cannot be executed again";
		}
		if (auto result = bind_mount_bionic(kBootstrapLinkerPath, kBootstrapBionicLibsDir,
		kLinkerMountPoint, kBionicLibsMountPointDir, false);
		!result) {
		return result;
		}
		if (auto result = bind_mount_bionic(kBootstrapLinkerPath64, kBootstrapBionicLibsDir64,
		kLinkerMountPoint64, kBionicLibsMountPointDir64, false);
		!result) {
		return result;
		}

		LOG(INFO) << "prepare_bootstrap_bionic done";
		prepare_bootstrap_bionic_done = true;
		return Success();
		}

		// The bionic libs and the dynamic linker from the runtime APEX are bind-mounted
		// to the mount points. As a result, the previous mounts done by
		// prepare_bootstrap_bionic become hidden.
		static Result<Success> do_setup_runtime_bionic(const BuiltinArguments& args) {
		static bool setup_runtime_bionic_done = false;
		if (setup_runtime_bionic_done) {
		return Error() << "setup_runtime_bionic was already executed. Cannot be executed again";
		}
		if (auto result = bind_mount_bionic(kRuntimeLinkerPath, kRuntimeBionicLibsDir,
		kLinkerMountPoint, kBionicLibsMountPointDir, true);
		!result) {
		return result;
		}
		if (auto result = bind_mount_bionic(kRuntimeLinkerPath64, kRuntimeBionicLibsDir64,
		kLinkerMountPoint64, kBionicLibsMountPointDir64, true);
		!result) {
		return result;
		}

		ServiceList::GetInstance().MarkRuntimeAvailable();
		LOG(INFO) << "setup_runtime_bionic done";
		setup_runtime_bionic_done = true;
		return Success();
		}

		// Builtin-function-map start
		const BuiltinFunctionMap::Map& BuiltinFunctionMap::map() const {
		constexpr std::size_t kMax = std::numeric_limits<std::size_t>::max();
		@@ -1131,6 +1211,7 @@ const BuiltinFunctionMap::Map& BuiltinFunctionMap::map() const {
		{"mount_all", {1, kMax, {false, do_mount_all}}},
		{"mount", {3, kMax, {false, do_mount}}},
		{"parse_apex_configs", {0, 0, {false, do_parse_apex_configs}}},
		{"prepare_bootstrap_bionic",{0, 0, {false, do_prepare_bootstrap_bionic}}},
		{"umount", {1, 1, {false, do_umount}}},
		{"readahead", {1, 2, {true, do_readahead}}},
		{"restart", {1, 1, {false, do_restart}}},
		@@ -1139,6 +1220,7 @@ const BuiltinFunctionMap::Map& BuiltinFunctionMap::map() const {
		{"rm", {1, 1, {true, do_rm}}},
		{"rmdir", {1, 1, {true, do_rmdir}}},
		{"setprop", {2, 2, {true, do_setprop}}},
		{"setup_runtime_bionic", {0, 0, {false, do_setup_runtime_bionic}}},
		{"setrlimit", {3, 3, {false, do_setrlimit}}},
		{"start", {1, 1, {false, do_start}}},
		{"stop", {1, 1, {false, do_stop}}},

init/service.cpp

+76 −0

Original line number	Diff line number	Diff line
		@@ -140,6 +140,43 @@ Result<Success> Service::SetUpMountNamespace() const {
		return Success();
		}

		Result<Success> Service::SetUpPreApexdMounts() const {
		// If a pre-apexd service is 're' launched after the runtime APEX is
		// available, unmount the linker and bionic libs which are currently
		// bind mounted to the files in the runtime APEX. This will reveal
		// the hidden mount points (targetting the bootstrap ones in the
		// system partition) which were setup before the runtime APEX was
		// started. Note that these unmounts are done in a separate mount namespace
		// for the process. It does not affect other processes including the init.
		if (pre_apexd_ && ServiceList::GetInstance().IsRuntimeAvailable()) {
		if (access(kLinkerMountPoint, F_OK) == 0) {
		if (umount(kLinkerMountPoint) == -1) {
		return ErrnoError() << "Could not umount " << kLinkerMountPoint;
		}
		for (const auto& libname : kBionicLibFileNames) {
		std::string mount_point = kBionicLibsMountPointDir + libname;
		if (umount(mount_point.c_str()) == -1) {
		return ErrnoError() << "Could not umount " << mount_point;
		}
		}
		}

		if (access(kLinkerMountPoint64, F_OK) == 0) {
		if (umount(kLinkerMountPoint64) == -1) {
		return ErrnoError() << "Could not umount " << kLinkerMountPoint64;
		}
		for (const auto& libname : kBionicLibFileNames) {
		std::string mount_point = kBionicLibsMountPointDir64 + libname;
		std::string source = kBootstrapBionicLibsDir64 + libname;
		if (umount(mount_point.c_str()) == -1) {
		return ErrnoError() << "Could not umount " << mount_point;
		}
		}
		}
		}
		return Success();
		}

		Result<Success> Service::SetUpPidNamespace() const {
		if (prctl(PR_SET_NAME, name_.c_str()) == -1) {
		return ErrnoError() << "Could not set name";
		@@ -929,6 +966,14 @@ Result<Success> Service::Start() {
		scon = *result;
		}

		if (!ServiceList::GetInstance().IsRuntimeAvailable() && !pre_apexd_) {
		// If this service is started before the runtime APEX gets available,
		// mark it as pre-apexd one. Note that this marking is permanent. So
		// for example, if the service is re-launched (e.g., due to crash),
		// it is still recognized as pre-apexd... for consistency.
		pre_apexd_ = true;
		}

		LOG(INFO) << "starting service '" << name_ << "'...";

		pid_t pid = -1;
		@@ -945,6 +990,26 @@ Result<Success> Service::Start() {
		LOG(FATAL) << "Service '" << name_ << "' could not enter namespaces: " << result.error();
		}

		if (pre_apexd_) {
		// pre-apexd process gets a private copy of the mount namespace.
		// However, this does not mean that mount/unmount events are not
		// shared across pre-apexd processes and post-apexd processes.
		// Most of the events are still shared because the propagation
		// type of / is set to 'shared'. (see `mount rootfs rootfs /shared
		// rec` in init.rc)
		//
		// This unsharing is required to not propagate the mount events
		// under /system/lib/{libc\|libdl\|libm}.so and /system/bin/linker(64)
		// whose propagation type is set to private. With this,
		// bind-mounting the bionic libs and the dynamic linker from the
		// runtime APEX to the mount points does not affect pre-apexd
		// processes which should use the bootstrap ones.
		if (unshare(CLONE_NEWNS) != 0) {
		LOG(FATAL) << "Creating a new mount namespace for service"
		<< " '" << name_ << "' failed: " << strerror(errno);
		}
		}

		if (namespace_flags_ & CLONE_NEWNS) {
		if (auto result = SetUpMountNamespace(); !result) {
		LOG(FATAL) << "Service '" << name_
		@@ -952,6 +1017,13 @@ Result<Success> Service::Start() {
		}
		}

		if (pre_apexd_ && ServiceList::GetInstance().IsRuntimeAvailable()) {
		if (auto result = SetUpPreApexdMounts(); !result) {
		LOG(FATAL) << "Pre-apexd service '" << name_
		<< "' could not setup the mount points: " << result.error();
		}
		}

		if (namespace_flags_ & CLONE_NEWPID) {
		// This will fork again to run an init process inside the PID
		// namespace.
		@@ -1324,6 +1396,10 @@ void ServiceList::MarkServicesUpdate() {
		delayed_service_names_.clear();
		}

		void ServiceList::MarkRuntimeAvailable() {
		runtime_available_ = true;
		}

		void ServiceList::DelayService(const Service& service) {
		if (services_update_finished_) {
		LOG(ERROR) << "Cannot delay the start of service '" << service.name()

init/service.h

+25 −0

Original line number	Diff line number	Diff line
		@@ -62,6 +62,24 @@
		namespace android {
		namespace init {

		static constexpr const char* kLinkerMountPoint = "/system/bin/linker";
		static constexpr const char* kBootstrapLinkerPath = "/system/bin/linker";
		static constexpr const char* kRuntimeLinkerPath = "/apex/com.android.runtime/bin/linker";

		static constexpr const char* kBionicLibsMountPointDir = "/system/lib/";
		static constexpr const char* kBootstrapBionicLibsDir = "/system/lib/";
		static constexpr const char* kRuntimeBionicLibsDir = "/apex/com.android.runtime/lib/bionic/";

		static constexpr const char* kLinkerMountPoint64 = "/system/bin/linker64";
		static constexpr const char* kBootstrapLinkerPath64 = "/system/bin/linker64";
		static constexpr const char* kRuntimeLinkerPath64 = "/apex/com.android.runtime/bin/linker64";

		static constexpr const char* kBionicLibsMountPointDir64 = "/system/lib64/";
		static constexpr const char* kBootstrapBionicLibsDir64 = "/system/lib64/";
		static constexpr const char* kRuntimeBionicLibsDir64 = "/apex/com.android.runtime/lib64/bionic/";

		static const std::vector<std::string> kBionicLibFileNames = {"libc.so", "libm.so", "libdl.so"};

		class Service {
		public:
		Service(const std::string& name, Subcontext* subcontext_for_restart_commands,
		@@ -124,6 +142,7 @@ class Service {
		std::optional<std::chrono::seconds> timeout_period() const { return timeout_period_; }
		const std::vector<std::string>& args() const { return args_; }
		bool is_updatable() const { return updatable_; }
		bool is_pre_apexd() const { return pre_apexd_; }

		private:
		using OptionParser = Result<Success> (Service::*)(std::vector<std::string>&& args);
		@@ -132,6 +151,7 @@ class Service {
		Result<Success> SetUpMountNamespace() const;
		Result<Success> SetUpPidNamespace() const;
		Result<Success> EnterNamespaces() const;
		Result<Success> SetUpPreApexdMounts() const;
		void NotifyStateChange(const std::string& new_state) const;
		void StopOrReset(int how);
		void ZapStdio() const;
		@@ -242,6 +262,8 @@ class Service {
		std::vector<std::string> args_;

		std::vector<std::function<void(const siginfo_t& siginfo)>> reap_callbacks_;

		bool pre_apexd_ = false;
		};

		class ServiceList {
		@@ -284,13 +306,16 @@ class ServiceList {
		const std::vector<Service*> services_in_shutdown_order() const;

		void MarkServicesUpdate();
		void MarkRuntimeAvailable();
		bool IsServicesUpdated() const { return services_update_finished_; }
		bool IsRuntimeAvailable() const { return runtime_available_; }
		void DelayService(const Service& service);

		private:
		std::vector<std::unique_ptr<Service>> services_;

		bool services_update_finished_ = false;
		bool runtime_available_ = false;
		std::vector<std::string> delayed_service_names_;
		};

rootdir/init.rc

+16 −5

Original line number	Diff line number	Diff line
		@@ -12,6 +12,12 @@ import /init.usb.configfs.rc
		import /init.${ro.zygote}.rc

		on early-init
		# Mount shared so changes propagate into child namespaces
		# Do this before other processes are started from init. Otherwise,
		# processes launched while the propagation type of / is 'private'
		# won't get mount events from others.
		mount rootfs rootfs / shared rec

		# Set init and its forked children's oom_adj.
		write /proc/1/oom_score_adj -1000

		@@ -40,6 +46,8 @@ on early-init
		# cgroup for system_server and surfaceflinger
		mkdir /dev/memcg/system 0550 system system

		prepare_bootstrap_bionic

		start ueventd

		on init
		@@ -350,8 +358,6 @@ on post-fs
		# Once everything is setup, no need to modify /.
		# The bind+remount combination allows this to work in containers.
		mount rootfs rootfs / remount bind ro nodev
		# Mount shared so changes propagate into child namespaces
		mount rootfs rootfs / shared rec
		# Mount default storage into root namespace
		mount none /mnt/runtime/default /storage bind rec
		mount none none /storage slave rec
		@@ -587,6 +593,14 @@ on post-fs-data
		# Check any timezone data in /data is newer than the copy in the runtime module, delete if not.
		exec - system system -- /system/bin/tzdatacheck /apex/com.android.runtime/etc/tz /data/misc/zoneinfo

		# Wait for apexd to finish activating APEXes before starting more processes.
		# This certainly reduces the parallelism but is required to make as many processes
		# as possible to use the bionic libs from the runtime APEX. This takes less than 50ms
		# so the impact on the booting time is not significant.
		wait_for_prop apexd.status ready
		setup_runtime_bionic
		parse_apex_configs

		# If there is no post-fs-data action in the init.<device>.rc file, you
		# must uncomment this line, otherwise encrypted filesystems
		# won't work.
		@@ -808,6 +822,3 @@ on property:ro.debuggable=1
		service flash_recovery /system/bin/install-recovery.sh
		class main
		oneshot

		on property:apexd.status=ready
		parse_apex_configs