Always allow a r/w opening of /dev/null though the namei check. This

pattern is common, especially because of daemon(3) usage.  Will probably
help some daemons move their pledge() calls further upwards.
ok doug,

diff --git a/sys/kern/kern_pledge.c b/sys/kern/kern_pledge.c
index b3e3f29..6bcbaf2 100644 (file)
--- a/sys/kern/kern_pledge.c
+++ b/sys/kern/kern_pledge.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_pledge.c,v 1.36 2015/10/16 14:04:11 semarie Exp $        */
+/*     $OpenBSD: kern_pledge.c,v 1.37 2015/10/16 14:20:48 deraadt Exp $        */
 
 /*
  * Copyright (c) 2015 Nicholas Marriott <nicm@openbsd.org>
@@ -537,6 +537,13 @@ pledge_namei(struct proc *p, char *origpath)
                        return (0);
                break;
        case SYS_open:
+               /* daemon(3) or other such functions */
+               if ((p->p_pledgenote == TMN_RPATH ||
+                   p->p_pledgenote == TMN_WPATH)) {
+                       if (strcmp(path, "/dev/null") == 0)
+                               return (0);
+               }
+
                /* getpw* and friends need a few files */
                if ((p->p_pledgenote == TMN_RPATH) &&
                    (p->p_p->ps_pledge & PLEDGE_GETPW)) {