Merge "init: Wait for snapuserd before starting second stage" (286c1d58) · Commits · e / os / android_system_core

fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_server.cpp

+7 −2

Original line number	Diff line number	Diff line
		@@ -599,8 +599,13 @@ bool UserSnapshotServer::WaitForSocket() {
		return false;
		}

		// We must re-initialize property service access, since we launched before
		// second-stage init.
		// This initialization of system property is important. When daemon is
		// launched post selinux transition (before init second stage),
		// bionic libc initializes system property as part of __libc_init_common();
		// however that initialization fails silently given that fact that we don't
		// have /dev/__properties__ setup which is created at init second stage.
		//
		// At this point, we have the handlers setup and is safe to setup property.
		__system_properties_init();

		if (!android::base::WaitForProperty("snapuserd.proxy_ready", "true")) {

init/snapuserd_transition.cpp

+58 −0

Original line number	Diff line number	Diff line
		@@ -32,6 +32,7 @@
		#include <android-base/strings.h>
		#include <android-base/unique_fd.h>
		#include <cutils/sockets.h>
		#include <fs_avb/fs_avb.h>
		#include <libsnapshot/snapshot.h>
		#include <private/android_filesystem_config.h>
		#include <procinfo/process_map.h>
		@@ -247,6 +248,56 @@ void SnapuserdSelinuxHelper::FinishTransition() {
		}
		}

		/*
		* Before starting init second stage, we will wait
		* for snapuserd daemon to be up and running; bionic libc
		* may read /system/etc/selinux/plat_property_contexts file
		* before invoking main() function. This will happen if
		* init initializes property during second stage. Any access
		* to /system without snapuserd daemon will lead to a deadlock.
		*
		* Thus, we do a simple probe by reading system partition. This
		* read will eventually be serviced by daemon confirming that
		* daemon is up and running. Furthermore, we are still in the kernel
		* domain and sepolicy has not been enforced yet. Thus, access
		* to these device mapper block devices are ok even though
		* we may see audit logs.
		*/
		bool SnapuserdSelinuxHelper::TestSnapuserdIsReady() {
		std::string dev = "/dev/block/mapper/system"s + fs_mgr_get_slot_suffix();
		android::base::unique_fd fd(open(dev.c_str(), O_RDONLY \| O_DIRECT));
		if (fd < 0) {
		PLOG(ERROR) << "open " << dev << " failed";
		return false;
		}

		void* addr;
		ssize_t page_size = getpagesize();
		if (posix_memalign(&addr, page_size, page_size) < 0) {
		PLOG(ERROR) << "posix_memalign with page size " << page_size;
		return false;
		}

		std::unique_ptr<void, decltype(&::free)> buffer(addr, ::free);

		int iter = 0;
		while (iter < 10) {
		ssize_t n = TEMP_FAILURE_RETRY(pread(fd.get(), buffer.get(), page_size, 0));
		if (n < 0) {
		// Wait for sometime before retry
		std::this_thread::sleep_for(100ms);
		} else if (n == page_size) {
		return true;
		} else {
		LOG(ERROR) << "pread returned: " << n << " from: " << dev << " expected: " << page_size;
		}

		iter += 1;
		}

		return false;
		}

		void SnapuserdSelinuxHelper::RelaunchFirstStageSnapuserd() {
		auto fd = GetRamdiskSnapuserdFd();
		if (!fd) {
		@@ -268,6 +319,13 @@ void SnapuserdSelinuxHelper::RelaunchFirstStageSnapuserd() {
		setenv(kSnapuserdFirstStagePidVar, std::to_string(pid).c_str(), 1);

		LOG(INFO) << "Relaunched snapuserd with pid: " << pid;

		if (!TestSnapuserdIsReady()) {
		PLOG(FATAL) << "snapuserd daemon failed to launch";
		} else {
		LOG(INFO) << "snapuserd daemon is up and running";
		}

		return;
		}

init/snapuserd_transition.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -56,6 +56,7 @@ class SnapuserdSelinuxHelper final {
		private:
		void RelaunchFirstStageSnapuserd();
		void ExecSnapuserd();
		bool TestSnapuserdIsReady();

		std::unique_ptr<SnapshotManager> sm_;
		BlockDevInitializer block_dev_init_;