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Commit 3bcac026 authored by David Howells's avatar David Howells Committed by James Morris
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SELinux: Don't flush inherited SIGKILL during execve() 



Don't flush inherited SIGKILL during execve() in SELinux's post cred commit
hook.  This isn't really a security problem: if the SIGKILL came before the
credentials were changed, then we were right to receive it at the time, and
should honour it; if it came after the creds were changed, then we definitely
should honour it; and in any case, all that will happen is that the process
will be scrapped before it ever returns to userspace.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent 88c48db9

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1875,6 +1875,7 @@ extern void sched_dead(struct task_struct *p); 


extern void proc_caches_init(void);

extern void flush_signals(struct task_struct *);

extern void __flush_signals(struct task_struct *);

extern void ignore_signals(struct task_struct *);

extern void flush_signal_handlers(struct task_struct *, int force_default);

extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);

kernel/signal.c

+8 −3
Original line number Diff line number Diff line
@@ -238,14 +238,19 @@ void flush_sigqueue(struct sigpending *queue) 
/*

 * Flush all pending signals for a task.

 */

void __flush_signals(struct task_struct *t)

{

	clear_tsk_thread_flag(t, TIF_SIGPENDING);

	flush_sigqueue(&t->pending);

	flush_sigqueue(&t->signal->shared_pending);

}



void flush_signals(struct task_struct *t)

{

	unsigned long flags;



	spin_lock_irqsave(&t->sighand->siglock, flags);

	clear_tsk_thread_flag(t, TIF_SIGPENDING);

	flush_sigqueue(&t->pending);

	flush_sigqueue(&t->signal->shared_pending);

	__flush_signals(t);

	spin_unlock_irqrestore(&t->sighand->siglock, flags);

}

security/selinux/hooks.c

+5 −4
Original line number Diff line number Diff line
@@ -2394,11 +2394,12 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm) 
		memset(&itimer, 0, sizeof itimer);

		for (i = 0; i < 3; i++)

			do_setitimer(i, &itimer, NULL);

		flush_signals(current);

		spin_lock_irq(&current->sighand->siglock);

		if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {

			__flush_signals(current);

			flush_signal_handlers(current, 1);

			sigemptyset(&current->blocked);

		recalc_sigpending();

		}

		spin_unlock_irq(&current->sighand->siglock);

	}