2008-06-03 22:26:21

by Michael Kerrisk

Subject: [parch 2/4] vfs: utimensat(): be consistent with utime() for immutable and append-only files

This patch fixes utimensat() to make its behavior consistent
with that of utime()/utimes() when dealing with files marked
immutable and append-only.

The current utimensat() implementation also returns EPERM if
'times' is non-NULL and the tv_nsec fields are both UTIME_NOW.
For consistency, the

(times != NULL && times[0].tv_nsec == UTIME_NOW &&
times[1].tv_nsec == UTIME_NOW)

case should be treated like the traditional utimes() case where
'times' is NULL. That is, the call should succeed for a file
marked append-only and should give the error EACCES if the file
is marked as immutable.

The simple way to do this is to set 'times' to NULL
if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW).

This is also the natural approach, since POSIX.1 semantics consider the
times == {{x, UTIME_NOW}, {y, UTIME_NOW}}
to be exactly equivalent to the case for
times == NULL.

(Thanks to Miklos for pointing this out.)

Patch 3 in this series relies on the simplification provided
by this patch.

CC: Miklos Szeredi <[email protected]>
CC: Al Viro <[email protected]>
CC: Ulrich Drepper <[email protected]>
Signed-off-by: Michael Kerrisk <[email protected]>

--- linux-2.6.26-rc4/fs/utimes.c 2008-06-03 22:47:07.000000000 +0200
+++ linux-2.6.26-rc4-utimensat-fix-v4/fs/utimes.c 2008-06-03 22:59:55.000000000 +0200
@@ -102,6 +102,10 @@
if (error)
goto dput_and_out;

+ if (times && times[0].tv_nsec == UTIME_NOW &&
+ times[1].tv_nsec == UTIME_NOW)
+ times = NULL;
+
/* Don't worry, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {

2008-06-04 04:30:28

by Miklos Szeredi

Subject: Re: [parch 2/4] vfs: utimensat(): be consistent with utime() for immutable and append-only files

> This patch fixes utimensat() to make its behavior consistent
> with that of utime()/utimes() when dealing with files marked
> immutable and append-only.
>
> The current utimensat() implementation also returns EPERM if
> 'times' is non-NULL and the tv_nsec fields are both UTIME_NOW.
> For consistency, the
>
> (times != NULL && times[0].tv_nsec == UTIME_NOW &&
> times[1].tv_nsec == UTIME_NOW)
>
> case should be treated like the traditional utimes() case where
> 'times' is NULL. That is, the call should succeed for a file
> marked append-only and should give the error EACCES if the file
> is marked as immutable.
>
> The simple way to do this is to set 'times' to NULL
> if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW).
>
> This is also the natural approach, since POSIX.1 semantics consider the
> times == {{x, UTIME_NOW}, {y, UTIME_NOW}}
> to be exactly equivalent to the case for
> times == NULL.
>
> (Thanks to Miklos for pointing this out.)
>
> Patch 3 in this series relies on the simplification provided
> by this patch.
>
> CC: Miklos Szeredi <[email protected]>
> CC: Al Viro <[email protected]>
> CC: Ulrich Drepper <[email protected]>
> Signed-off-by: Michael Kerrisk <[email protected]>

Acked-by: Miklos Szeredi <[email protected]>