Commit 291041e9 authored Oct 07, 2007 by Al Viro Committed by Linus Torvalds Oct 07, 2007

fix bogus reporting of signals by audit

Async signals should not be reported as sent by current in audit log. As
it is, we call audit_signal_info() too early in check_kill_permission().
Note that check_kill_permission() has that test already - it needs to know
if it should apply current-based permission checks. So the solution is to
move the call of audit_signal_info() between those.

Bogosity in question is easily reproduced - add a rule watching for e.g.
kill(2) from specific process (so that audit_signal_info() would not
short-circuit to nothing), say load_policy, watch the bogus OBJ_PID entry
in audit logs claiming that write(2) on selinuxfs file issued by
load_policy(8) had somehow managed to send a signal to syslogd...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7a5c5d57

kernel/signal.c

+11 −11

Original line number	Diff line number	Diff line
		@@ -531,18 +531,18 @@ static int check_kill_permission(int sig, struct siginfo *info,
		if (!valid_signal(sig))
		return error;

		if (info == SEND_SIG_NOINFO \|\| (!is_si_special(info) && SI_FROMUSER(info))) {
		error = audit_signal_info(sig, t); /* Let audit system see the signal */
		if (error)
		return error;

		error = -EPERM;
		if ((info == SEND_SIG_NOINFO \|\| (!is_si_special(info) && SI_FROMUSER(info)))
		&& ((sig != SIGCONT) \|\|
		if (((sig != SIGCONT) \|\|
		(process_session(current) != process_session(t)))
		&& (current->euid ^ t->suid) && (current->euid ^ t->uid)
		&& (current->uid ^ t->suid) && (current->uid ^ t->uid)
		&& !capable(CAP_KILL))
		return error;
		}

		return security_task_kill(t, info, sig, 0);
		}

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