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Rectify race condition in rm -P processing by checking that the file 

we opened is the one we expected to get. Also use O_NOFOLLOW to help
avoid even opening devices, which sometimes produce side effects.

Reported by Radoslaw A. Zarzynski.
This commit is contained in:
dholland 2012-06-13 07:35:37 +00:00
parent 08f6c5569f
commit 61f93db25f
1 changed files with 14 additions and 4 deletions
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18
bin/rm/rm.c
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@ -1,4 +1,4 @@
/* $NetBSD: rm.c,v 1.51 2012/01/21 16:38:41 christos Exp $ */ /* $NetBSD: rm.c,v 1.52 2012/06/13 07:35:37 dholland Exp $ */
/*- /*-
* Copyright (c) 1990, 1993, 1994, 2003 * Copyright (c) 1990, 1993, 1994, 2003
@ -39,7 +39,7 @@ __COPYRIGHT("@(#) Copyright (c) 1990, 1993, 1994\
#if 0 #if 0
static char sccsid[] = "@(#)rm.c 8.8 (Berkeley) 4/27/95"; static char sccsid[] = "@(#)rm.c 8.8 (Berkeley) 4/27/95";
#else #else
__RCSID("$NetBSD: rm.c,v 1.51 2012/01/21 16:38:41 christos Exp $"); __RCSID("$NetBSD: rm.c,v 1.52 2012/06/13 07:35:37 dholland Exp $");
#endif #endif
#endif /* not lint */ #endif /* not lint */
@ -380,7 +380,7 @@ rm_file(char **argv)
static int static int
rm_overwrite(char *file, struct stat *sbp) rm_overwrite(char *file, struct stat *sbp)
{ {
struct stat sb; struct stat sb, sb2;
int fd, randint; int fd, randint;
char randchar; char randchar;
@ -394,9 +394,19 @@ rm_overwrite(char *file, struct stat *sbp)
return 0; return 0;
/* flags to try to defeat hidden caching by forcing seeks */ /* flags to try to defeat hidden caching by forcing seeks */
if ((fd = open(file, O_RDWR|O_SYNC|O_RSYNC, 0)) == -1) if ((fd = open(file, O_RDWR|O_SYNC|O_RSYNC|O_NOFOLLOW, 0)) == -1)
goto err; goto err;
if (fstat(fd, &sb2)) {
goto err;
}
if (sb2.st_dev != sbp->st_dev || sb2.st_ino != sbp->st_ino ||
!S_ISREG(sb2.st_mode)) {
errno = EPERM;
goto err;
}
#define RAND_BYTES 1 #define RAND_BYTES 1
#define THIS_BYTE 0 #define THIS_BYTE 0