On Wed, Jun 4, 2008 at 7:12 AM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
>> > 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.
>
> Or maybe not. Isn't this a simpler and more readable patch?
The idea is okay (we talked about it already), but I don't like doing
it now because it only migrates *one* of the is_owner_or_cap() checks
out of do_utimes(). We could revisit this later in the context of
migrating both checks out of do_utimes(), but I'd prefer to leave that
for now.
> Index: linux/fs/attr.c
> ===================================================================
> --- linux.orig/fs/attr.c 2008-06-03 13:10:11.000000000 +0200
> +++ linux/fs/attr.c 2008-06-04 07:07:23.000000000 +0200
> @@ -51,7 +51,7 @@ int inode_change_ok(struct inode *inode,
> }
>
> /* Check for setting the inode time. */
> - if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
> + if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_UPDATE_TIMES)) {
> if (!is_owner_or_cap(inode))
> goto error;
> }
> Index: linux/fs/utimes.c
> ===================================================================
> --- linux.orig/fs/utimes.c 2008-06-03 13:10:11.000000000 +0200
> +++ linux/fs/utimes.c 2008-06-04 07:10:53.000000000 +0200
> @@ -102,9 +102,14 @@ long do_utimes(int dfd, char __user *fil
> if (error)
> goto dput_and_out;
>
> - /* Don't worry, the checks are done in inode_change_ok() */
> newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
> if (times) {
> + /*
> + * Checking the owner is done in inode_change_ok(),
> + * even for the special UTIME_OMIT/UTIME_NOW cases.
> + */
> + newattrs.ia_valid |= ATTR_UPDATE_TIMES
> +
> error = -EPERM;
> if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
> goto mnt_drop_write_and_out;
> Index: linux/include/linux/fs.h
> ===================================================================
> --- linux.orig/include/linux/fs.h 2008-06-03 13:10:25.000000000 +0200
> +++ linux/include/linux/fs.h 2008-06-04 07:07:43.000000000 +0200
> @@ -333,6 +333,7 @@ typedef void (dio_iodone_t)(struct kiocb
> #define ATTR_FILE 8192
> #define ATTR_KILL_PRIV 16384
> #define ATTR_OPEN 32768 /* Truncating from open(O_TRUNC) */
> +#define ATTR_UPDATE_TIMES (1 << 16)
>
> /*
> * This is the Inode Attributes structure, used for notify_change(). It
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html
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