From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Wed, 22 Aug 2007 04:22:32 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [66.187.233.31]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id l7MBMM4p000485 for ; Wed, 22 Aug 2007 04:22:25 -0700 Date: Tue, 21 Aug 2007 18:23:05 -0400 From: Jeff Layton Subject: Re: [PATCH 2/4] Fix mainline filesystems to handle ATTR_KILL_ bits correctly Message-Id: <20070821182305.7c0cb135.jlayton@redhat.com> In-Reply-To: <20070821212128.GC1741@filer.fsl.cs.sunysb.edu> References: <200708202053.l7KKrMYv017763@dantu.rdu.redhat.com> <46CA798C.1020101@sgi.com> <20070821073551.dac4a5dd.jlayton@redhat.com> <20070821212128.GC1741@filer.fsl.cs.sunysb.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Josef Sipek Cc: Timothy Shimmin , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs-oss On Tue, 21 Aug 2007 17:21:28 -0400 Josef Sipek wrote: > On Tue, Aug 21, 2007 at 07:35:51AM -0400, Jeff Layton wrote: > > On Tue, 21 Aug 2007 15:35:08 +1000 > > Timothy Shimmin wrote: > > > > > Jeff Layton wrote: > > > > This should fix all of the filesystems in the mainline kernels to handle > > > > ATTR_KILL_SUID and ATTR_KILL_SGID correctly. For most of them, this is > > > > just a matter of making sure that they call generic_attrkill early in > > > > the setattr inode op. > > > > > > > > Signed-off-by: Jeff Layton > > > > --- > > > > fs/xfs/linux-2.6/xfs_iops.c | 5 ++++- > > > > --- a/fs/xfs/linux-2.6/xfs_iops.c > > > > +++ b/fs/xfs/linux-2.6/xfs_iops.c > > > > @@ -651,12 +651,15 @@ xfs_vn_setattr( > > > > struct iattr *attr) > > > > { > > > > struct inode *inode = dentry->d_inode; > > > > - unsigned int ia_valid = attr->ia_valid; > > > > + unsigned int ia_valid; > > > > bhv_vnode_t *vp = vn_from_inode(inode); > > > > bhv_vattr_t vattr = { 0 }; > > > > int flags = 0; > > > > int error; > > > > > > > > + generic_attrkill(inode->i_mode, attr); > > > > + ia_valid = attr->ia_valid; > > > > + > > > > if (ia_valid & ATTR_UID) { > > > > vattr.va_mask |= XFS_AT_UID; > > > > vattr.va_uid = attr->ia_uid; > > > > > > Looks reasonable to me for XFS. > > > Acked-by: Tim Shimmin > > > > > > So before, this clearing would happen directly in notify_change() > > > and now this won't happen until notify_change() calls i_op->setattr > > > which for a particular fs it can call generic_attrkill() to do it. > > > So I guess for the cases where i_op->setattr is called outside of > > > via notify_change, we don't normally have ATTR_KILL_SUID/SGID > > > set so that nothing will happen there? > > > > Right. If neither ATTR_KILL bit is set then generic_attrkill is a > > noop. > > > > > I guess just wondering the effect with having the code on all > > > setattr's. (I'm not familiar with the code path) > > > > > > > These bits are referenced in very few places in the current kernel > > tree -- mostly in the VFS layer. The *only* place I see that they > > actually get interpreted into a mode change is in notify_change. So > > places that call setattr ops w/o going through notify_change are > > not likely to have those bits set. > > > > But hypothetically, if a fs did set ATTR_KILL_* and call setattr > > directly, then the setattr would now include a mode change that > > clears setuid or setgid bits where it may not have before. > I should probably clarify -- in the hypothetical situation above, the setattr function would have to call generic_attrkill (as most filesystems should do with this change). > It almost sounds like an argument for a new inode op (NULL would use > generic_attr_kill). > That's not a bad idea at all. I suppose that would be easier than modifying every fs like this, and it does seem like it might be cleaner. I need to mull it over, but that might be the best solution. -- Jeff Layton