Merge "init: Fix a race condition in KillProcessGroup()" (7f046419) · Commits · e / os / android_system_core

init/service.cpp

+32 −4

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

		#include "service.h"

		#include <errno.h>
		#include <fcntl.h>
		#include <inttypes.h>
		#include <linux/securebits.h>
		@@ -532,7 +533,6 @@ void Service::RunService(const std::vector<Descriptor>& descriptors, Interproces
		if (!byte.ok()) {
		LOG(ERROR) << name_ << ": failed to read from notification channel: " << byte.error();
		}
		fifo.Close();
		if (!*byte) {
		LOG(FATAL) << "Service '" << name_ << "' failed to start due to a fatal error";
		_exit(EXIT_FAILURE);
		@@ -556,6 +556,12 @@ void Service::RunService(const std::vector<Descriptor>& descriptors, Interproces
		// priority. Aborts on failure.
		SetProcessAttributesAndCaps();

		// If SetProcessAttributes() called setsid(), report this to the parent.
		if (RequiresConsole(proc_attr_)) {
		fifo.Write(2);
		}
		fifo.Close();

		if (!ExpandArgsAndExecv(args_, sigstop_)) {
		PLOG(ERROR) << "cannot execv('" << args_[0]
		<< "'). See the 'Debugging init' section of init's README.md for tips";
		@@ -656,11 +662,8 @@ Result<void> Service::Start() {

		if (pid == 0) {
		umask(077);
		fifo.CloseWriteFd();
		RunService(descriptors, std::move(fifo));
		_exit(127);
		} else {
		fifo.CloseReadFd();
		}

		if (pid < 0) {
		@@ -717,6 +720,31 @@ Result<void> Service::Start() {
		return Error() << "Sending cgroups activated notification failed: " << result.error();
		}

		// Call setpgid() from the parent process to make sure that this call has
		// finished before the parent process calls kill(-pgid, ...).
		if (proc_attr_.console.empty()) {
		if (setpgid(pid, pid) < 0) {
		switch (errno) {
		case EACCES: // Child has already performed execve().
		case ESRCH: // Child process no longer exists.
		break;
		default:
		PLOG(ERROR) << "setpgid() from parent failed";
		}
		}
		} else {
		// The Read() call below will return an error if the child is killed.
		if (Result<uint8_t> result = fifo.Read(); !result.ok() \|\| *result != 2) {
		if (!result.ok()) {
		return Error() << "Waiting for setsid() failed: " << result.error();
		} else {
		return Error() << "Waiting for setsid() failed: " << *result << " <> 2";
		}
		}
		}

		fifo.Close();

		NotifyStateChange("running");
		reboot_on_failure.Disable();
		return {};

init/service.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -155,7 +155,7 @@ class Service {
		void ResetFlagsForStart();
		Result<void> CheckConsole();
		void ConfigureMemcg();
		void RunService(const std::vector<Descriptor>& descriptors, InterprocessFifo cgroups_activated);
		void RunService(const std::vector<Descriptor>& descriptors, InterprocessFifo fifo);
		void SetMountNamespace();
		static unsigned long next_start_order_;
		static bool is_exec_service_running_;

init/service_utils.cpp

+6 −2

Original line number	Diff line number	Diff line
		@@ -240,11 +240,15 @@ Result<void> SetProcessAttributes(const ProcessAttributes& attr) {
		}
		}

		if (!attr.console.empty()) {
		if (RequiresConsole(attr)) {
		setsid();
		OpenConsole(attr.console);
		} else {
		if (setpgid(0, getpid()) == -1) {
		// Without PID namespaces, this call duplicates the setpgid() call from
		// the parent process. With PID namespaces, this setpgid() call sets the
		// process group ID for a child of the init process in the PID
		// namespace.
		if (setpgid(0, 0) == -1) {
		return ErrnoError() << "setpgid failed";
		}
		SetupStdio(attr.stdio_to_kmsg);

init/service_utils.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -89,6 +89,11 @@ struct ProcessAttributes {
		int priority;
		bool stdio_to_kmsg;
		};

		inline bool RequiresConsole(const ProcessAttributes& attr) {
		return !attr.console.empty();
		}

		Result<void> SetProcessAttributes(const ProcessAttributes& attr);

		Result<void> WritePidToFiles(std::vector<std::string>* files);