Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 73243284 authored by Roland McGrath's avatar Roland McGrath Committed by Linus Torvalds
Browse files

Return EPERM not ECHILD on security_task_wait failure 



wait* syscalls return -ECHILD even when an individual PID of a live child
was requested explicitly, when security_task_wait denies the operation.
This means that something like a broken SELinux policy can produce an
unexpected failure that looks just like a bug with wait or ptrace or
something.

This patch makes do_wait return -EACCES (or other appropriate error returned
from security_task_wait() instead of -ECHILD if some children were ruled out
solely because security_task_wait failed.

[jmorris@namei.org: switch error code to EACCES]
Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Acked-by: default avatarStephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 906e0be1

kernel/exit.c

+15 −2
Original line number Diff line number Diff line
@@ -1033,6 +1033,8 @@ asmlinkage void sys_exit_group(int error_code) 


static int eligible_child(pid_t pid, int options, struct task_struct *p)

{

	int err;



	if (pid > 0) {

		if (p->pid != pid)

			return 0;
@@ -1066,8 +1068,9 @@ static int eligible_child(pid_t pid, int options, struct task_struct *p) 
	if (delay_group_leader(p))

		return 2;



	if (security_task_wait(p))

		return 0;

	err = security_task_wait(p);

	if (err)

		return err;



	return 1;

}
@@ -1449,6 +1452,7 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 
	DECLARE_WAITQUEUE(wait, current);

	struct task_struct *tsk;

	int flag, retval;

	int allowed, denied;



	add_wait_queue(&current->signal->wait_chldexit,&wait);

repeat:
@@ -1457,6 +1461,7 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 
	 * match our criteria, even if we are not able to reap it yet.

	 */

	flag = 0;

	allowed = denied = 0;

	current->state = TASK_INTERRUPTIBLE;

	read_lock(&tasklist_lock);

	tsk = current;
@@ -1472,6 +1477,12 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 
			if (!ret)

				continue;



			if (unlikely(ret < 0)) {

				denied = ret;

				continue;

			}

			allowed = 1;



			switch (p->state) {

			case TASK_TRACED:

				/*
@@ -1570,6 +1581,8 @@ static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 
		goto repeat;

	}

	retval = -ECHILD;

	if (unlikely(denied) && !allowed)

		retval = denied;

end:

	current->state = TASK_RUNNING;

	remove_wait_queue(&current->signal->wait_chldexit,&wait);