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: Oleg Nesterov <[email protected]> Cc: Roland McGrath <[email protected]> Reviewed-by: Sukadev Bhattiprolu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
Kleist · Dec 16, 2009 · 614c517 · 614c517
1 parent d519650
commit 614c517
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Showing 2 changed files with 13 additions and 8 deletions.
diff --git a/include/linux/sched.h b/include/linux/sched.h
@@ -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.
  */

diff --git a/kernel/signal.c b/kernel/signal.c
@@ -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;