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 <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>
diff --git a/kernel/signal.c b/kernel/signal.c
index 6b982f2..a0ba428 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -607,6 +607,17 @@
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 @@
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 @@
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;