On Wed, Mar 09, 2022 at 11:22:11AM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > Filipe Manana pointed out that XFS' behavior w.r.t. setuid/setgid > revocation isn't consistent with btrfs[1] or ext4. Those two > filesystems use the VFS function setattr_copy to convey certain > attributes from struct iattr into the VFS inode structure. > > Andrey Zhadchenko reported[2] that XFS uses the wrong user namespace to > decide if it should clear setgid and setuid on a file attribute update. > This is a second symptom of the problem that Filipe noticed. > > XFS, on the other hand, open-codes setattr_copy in xfs_setattr_mode, > xfs_setattr_nonsize, and xfs_setattr_time. Regrettably, setattr_copy is > /not/ a simple copy function; it contains additional logic to clear the > setgid bit when setting the mode, and XFS' version no longer matches. > > The VFS implements its own setuid/setgid stripping logic, which > establishes consistent behavior. It's a tad unfortunate that it's > scattered across notify_change, should_remove_suid, and setattr_copy but > XFS should really follow the Linux VFS. Adapt XFS to use the VFS > functions and get rid of the old functions. > > [1] https://lore.kernel.org/fstests/CAL3q7H47iNQ=Wmk83WcGB-KBJVOEtR9+qGczzCeXJ9Y2KCV25Q@xxxxxxxxxxxxxx/ > [2] https://lore.kernel.org/linux-xfs/20220221182218.748084-1-andrey.zhadchenko@xxxxxxxxxxxxx/ > > Fixes: f736d93d76d3 ("xfs: support idmapped mounts") > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > --- > fs/xfs/xfs_iops.c | 56 +++-------------------------------------------------- > fs/xfs/xfs_pnfs.c | 3 ++- > 2 files changed, 5 insertions(+), 54 deletions(-) Looks good, nice cleanup as well as being more correct. Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx> -- Dave Chinner david@xxxxxxxxxxxxx
