From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Kerrisk" Subject: Re: [parch 3/4] vfs: utimensat(): fix error checking for {UTIME_NOW,UTIME_OMIT} case Date: Wed, 4 Jun 2008 11:27:18 +0200 Message-ID: References: <4845C4CA.5070403@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, hch@lst.de, viro@zeniv.linux.org.uk, jamie@shareable.org, drepper@redhat.com, linux-fsdevel@vger.kernel.org, subrata@linux.vnet.ibm.com To: "Miklos Szeredi" Return-path: Received: from hu-out-0506.google.com ([72.14.214.238]:56955 "EHLO hu-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759282AbYFDJ1W (ORCPT ); Wed, 4 Jun 2008 05:27:22 -0400 Received: by hu-out-0506.google.com with SMTP id 28so5687745hub.21 for ; Wed, 04 Jun 2008 02:27:19 -0700 (PDT) In-Reply-To: Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Jun 4, 2008 at 7:12 AM, Miklos Szeredi 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