> The POSIX.1 draft spec for utimensat() says that to do anything
> other than setting both timestamps to a time other than the
> current time (i.e., times is not NULL, and both tv_nsec fields
> are not UTIME_NOW and both tv_nsec fields are not UTIME_OMIT),
> either:
>
> a) the caller's effective user ID must match the file owner; or
> b) the caller must have appropriate privileges.
>
> If this condition is violated, then the error EPERM should result.
> However, the current implementation does not generate EPERM if
> one tv_nsec field is UTIME_NOW while the other is UTIME_OMIT.
> It should give this error for that case.
>
> This patch:
>
> a) Repairs that problem.
> b) Removes the now unneeded nsec_special() helper function.
>
> Miklos suggested an alternative idea, migrating the
> is_owner_or_cap() checks into fs/attr.c:inode_change_ok() via
> the use of an ATTR_OWNER_CHECK flag. Maybe we could do that
> later, but for now I've gone with this version, which is
> simpler, and can be more easily read as being correct.
Wise decision.
> CC: Miklos Szeredi <miklos@xxxxxxxxxx>
> CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> CC: Ulrich Drepper <drepper@xxxxxxxxxx>
> Signed-off-by: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
>
>
> --- linux-2.6.26-rc4/fs/utimes.c 2008-06-03 23:11:53.000000000 +0200
> +++ linux-2.6.26-rc4-utimensat-fix-v4/fs/utimes.c 2008-06-03 23:04:48.000000000 +0200
> @@ -40,14 +40,9 @@
>
> #endif
>
> -static bool nsec_special(long nsec)
> -{
> - return nsec == UTIME_OMIT || nsec == UTIME_NOW;
> -}
> -
> static bool nsec_valid(long nsec)
> {
> - if (nsec_special(nsec))
> + if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
> return true;
>
> return nsec >= 0 && nsec <= 999999999;
> @@ -135,8 +130,7 @@
> * 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))) {
> + if (!times) {
This can be restored to be the "else" branch of the "if (times)".
> error = -EACCES;
> if (IS_IMMUTABLE(inode))
> goto mnt_drop_write_and_out;
> @@ -151,6 +145,18 @@
> goto mnt_drop_write_and_out;
> }
> }
> + } else if ((times[0].tv_nsec == UTIME_NOW &&
> + times[1].tv_nsec == UTIME_OMIT)
> + ||
> + (times[0].tv_nsec == UTIME_OMIT &&
> + times[1].tv_nsec == UTIME_NOW)) {
And I'd rather put this inside the "if (times)" for clarity.
> + error =-EPERM;
> +
> + if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
> + goto mnt_drop_write_and_out;
And then you would've realized, that this check was already done.
> +
> + if (!is_owner_or_cap(inode))
> + goto mnt_drop_write_and_out;
OK.
> }
> mutex_lock(&inode->i_mutex);
> error = notify_change(dentry, &newattrs);
>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
