The patch titled vfs: fix permission checking in sys_utimensat has been removed from the -mm tree. Its filename was vfs-fix-permission-checking-in-sys_utimensat.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: vfs: fix permission checking in sys_utimensat From: Miklos Szeredi <mszeredi@xxxxxxx> If utimensat() is called with both times set to UTIME_NOW or one of them to UTIME_NOW and the other to UTIME_OMIT, then it will update the file time without any permission checking. I don't think this can be used for anything other than a local DoS, but could be quite bewildering at that (e.g. "Why was that large source tree rebuilt when I didn't modify anything???") This affects all kernels from 2.6.22, when the utimensat() syscall was introduced. Fix by doing the same permission checking as for the "times == NULL" case. Thanks to Michael Kerrisk, whose utimensat-non-conformances-and-fixes.patch in -mm also fixes this (and breaks other stuff), only he didn't realize the security implications of this bug. Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx> Cc: Ulrich Drepper <drepper@xxxxxxxxxx> Cc: Michael Kerrisk <mtk-manpages@xxxxxxx> Cc: <stable@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/utimes.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff -puN fs/utimes.c~vfs-fix-permission-checking-in-sys_utimensat fs/utimes.c --- a/fs/utimes.c~vfs-fix-permission-checking-in-sys_utimensat +++ a/fs/utimes.c @@ -40,9 +40,14 @@ asmlinkage long sys_utime(char __user *f #endif +static bool nsec_special(long nsec) +{ + return nsec == UTIME_OMIT || nsec == UTIME_NOW; +} + static bool nsec_valid(long nsec) { - if (nsec == UTIME_OMIT || nsec == UTIME_NOW) + if (nsec_special(nsec)) return true; return nsec >= 0 && nsec <= 999999999; @@ -119,7 +124,15 @@ long do_utimes(int dfd, char __user *fil newattrs.ia_mtime.tv_nsec = times[1].tv_nsec; newattrs.ia_valid |= ATTR_MTIME_SET; } - } else { + } + + /* + * If times is NULL or both times are either UTIME_OMIT or + * UTIME_NOW, then need to check permissions, because + * inode_change_ok() won't do it. + */ + if (!times || (nsec_special(times[0].tv_nsec) && + nsec_special(times[1].tv_nsec))) { error = -EACCES; if (IS_IMMUTABLE(inode)) goto mnt_drop_write_and_out; _ Patches currently in -mm which might be from mszeredi@xxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html