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signals: SEND_SIG_NOINFO should be considered as SI_FROMUSER()

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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: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Reviewed-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2009-12-15 16:47:22 -08:00 committed by Linus Torvalds
parent d519650373
commit 614c517d7c
2 changed files with 13 additions and 8 deletions
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5
include/linux/sched.h
View file

@ -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.
*/

16
kernel/signal.c
View file

@ -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;