Merge "init: only mlock() system pages when performing snapuserd transitions." (c90fce43) · Commits · e / os / android_system_core

init/Android.bp

+2 −0

Original line number	Diff line number	Diff line
		@@ -143,6 +143,7 @@ cc_defaults {
		"libcgrouprc_format",
		"liblmkd_utils",
		"libmodprobe",
		"libprocinfo",
		"libprotobuf-cpp-lite",
		"libpropertyinfoserializer",
		"libpropertyinfoparser",
		@@ -308,6 +309,7 @@ cc_binary {
		"libsnapshot_cow",
		"libsnapshot_init",
		"update_metadata-protos",
		"libprocinfo",
		],

		static_executable: true,

init/Android.mk

+1 −0

Original line number	Diff line number	Diff line
		@@ -130,6 +130,7 @@ LOCAL_STATIC_LIBRARIES := \
		libsnapshot_cow \
		libsnapshot_init \
		update_metadata-protos \
		libprocinfo \

		LOCAL_SANITIZE := signed-integer-overflow
		# First stage init is weird: it may start without stdout/stderr, and no /proc.

init/snapuserd_transition.cpp

+30 −3

Original line number	Diff line number	Diff line
		@@ -24,6 +24,7 @@

		#include <filesystem>
		#include <string>
		#include <string_view>

		#include <android-base/file.h>
		#include <android-base/logging.h>
		@@ -34,6 +35,7 @@
		#include <libsnapshot/snapshot.h>
		#include <libsnapshot/snapuserd_client.h>
		#include <private/android_filesystem_config.h>
		#include <procinfo/process_map.h>
		#include <selinux/android.h>

		#include "block_dev_initializer.h"
		@@ -157,6 +159,33 @@ SnapuserdSelinuxHelper::SnapuserdSelinuxHelper(std::unique_ptr<SnapshotManager>&
		});
		}

		static void LockAllSystemPages() {
		bool ok = true;
		auto callback = [&](const android::procinfo::MapInfo& map) -> void {
		if (!ok \|\| android::base::StartsWith(map.name, "/dev/") \|\|
		!android::base::StartsWith(map.name, "/")) {
		return;
		}
		auto start = reinterpret_cast<const void*>(map.start);
		auto len = map.end - map.start;
		if (!len) {
		return;
		}
		if (mlock(start, len) < 0) {
		LOG(ERROR) << "mlock failed, " << start << " for " << len << " bytes.";
		ok = false;
		}
		};

		if (!android::procinfo::ReadProcessMaps(getpid(), callback) \|\| !ok) {
		LOG(FATAL) << "Could not process /proc/" << getpid() << "/maps file for init, "
		<< "falling back to mlockall().";
		if (mlockall(MCL_CURRENT) < 0) {
		LOG(FATAL) << "mlockall failed";
		}
		}
		}

		void SnapuserdSelinuxHelper::StartTransition() {
		LOG(INFO) << "Starting SELinux transition of snapuserd";

		@@ -170,9 +199,7 @@ void SnapuserdSelinuxHelper::StartTransition() {

		// We cannot access /system after the transition, so make sure init is
		// pinned in memory.
		if (mlockall(MCL_CURRENT) < 0) {
		LOG(FATAL) << "mlockall failed";
		}
		LockAllSystemPages();

		argv_.emplace_back("snapuserd");
		argv_.emplace_back("-no_socket");