[src/trunk]: src/lib/libc/gen Never invoke utmp_update() recursively if we ar...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2f6a7fbedc79
branches:  trunk
changeset: 769654:2f6a7fbedc79
user:      christos <christos%NetBSD.org@localhost>
date:      Sat Sep 17 01:52:29 2011 +0000

description:
Never invoke utmp_update() recursively if we are root. Instead close the
read-only file so it can be opened later. It can happen when a setuid
program utmp_update, seteuid(ruid) -> getutxent() -> seteuid(0) -> pututxent()

diffstat:

 lib/libc/gen/utmpx.c |  16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diffs (37 lines):

diff -r a1a3cc359fd8 -r 2f6a7fbedc79 lib/libc/gen/utmpx.c
--- a/lib/libc/gen/utmpx.c      Sat Sep 17 01:50:54 2011 +0000
+++ b/lib/libc/gen/utmpx.c      Sat Sep 17 01:52:29 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: utmpx.c,v 1.26 2009/01/11 02:46:27 christos Exp $       */
+/*     $NetBSD: utmpx.c,v 1.27 2011/09/17 01:52:29 christos Exp $       */
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
 #include <sys/cdefs.h>
 
 #if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: utmpx.c,v 1.26 2009/01/11 02:46:27 christos Exp $");
+__RCSID("$NetBSD: utmpx.c,v 1.27 2011/09/17 01:52:29 christos Exp $");
 #endif /* LIBC_SCCS and not lint */
 
 #include "namespace.h"
@@ -247,9 +247,15 @@
        if (utx == NULL)
                return NULL;
 
-       if (strcmp(_PATH_UTMPX, utfile) == 0)
-               if ((fp != NULL && readonly) || (fp == NULL && geteuid() != 0))
-                       return utmp_update(utx);
+       if (strcmp(_PATH_UTMPX, utfile) == 0) {
+               if (geteuid() == 0) {
+                       if (fp != NULL && readonly)
+                               endutxent();
+               } else {
+                       if (fp == NULL || readonly)
+                               return utmp_update(utx);
+               }
+       }
 
 
        (void)memcpy(&temp, utx, sizeof(temp));