Commit 614c517d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

signals: SEND_SIG_NOINFO should be considered as SI_FROMUSER() 



No changes in compiled code. The patch adds the new helper, si_fromuser()
and changes check_kill_permission() to use this helper.

The real effect of this patch is that from now we "officially" consider
SEND_SIG_NOINFO signal as "from user-space" signals. This is already true
if we look at the code which uses SEND_SIG_NOINFO, except __send_signal()
has another opinion - see the next patch.

The naming of these special SEND_SIG_XXX siginfo's is really bad
imho.  From __send_signal()'s pov they mean

	SEND_SIG_NOINFO		from user
	SEND_SIG_PRIV		from kernel
	SEND_SIG_FORCED		no info

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Reviewed-by: default avatarSukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d5196503

include/linux/sched.h

+0 −5
Original line number Diff line number Diff line
@@ -2102,11 +2102,6 @@ static inline int kill_cad_pid(int sig, int priv) 
#define SEND_SIG_PRIV	((struct siginfo *) 1)

#define SEND_SIG_FORCED	((struct siginfo *) 2)



static inline int is_si_special(const struct siginfo *info)

{

	return info <= SEND_SIG_FORCED;

}



/*

 * True if we are on the alternate signal stack.

 */

kernel/signal.c

+13 −3
Original line number Diff line number Diff line
@@ -607,6 +607,17 @@ static int rm_from_queue(unsigned long mask, struct sigpending *s) 
	return 1;

}



static inline int is_si_special(const struct siginfo *info)

{

	return info <= SEND_SIG_FORCED;

}



static inline bool si_fromuser(const struct siginfo *info)

{

	return info == SEND_SIG_NOINFO ||

		(!is_si_special(info) && SI_FROMUSER(info));

}



/*

 * Bad permissions for sending the signal

 * - the caller must hold at least the RCU read lock
@@ -621,7 +632,7 @@ static int check_kill_permission(int sig, struct siginfo *info, 
	if (!valid_signal(sig))

		return -EINVAL;



	if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))

	if (!si_fromuser(info))

		return 0;



	error = audit_signal_info(sig, t); /* Let audit system see the signal */
@@ -1186,8 +1197,7 @@ int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid, 
		goto out_unlock;

	}

	pcred = __task_cred(p);

	if ((info == SEND_SIG_NOINFO ||

	     (!is_si_special(info) && SI_FROMUSER(info))) &&

	if (si_fromuser(info) &&

	    euid != pcred->suid && euid != pcred->uid &&

	    uid  != pcred->suid && uid  != pcred->uid) {

		ret = -EPERM;

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