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Re: XFS reports lchmod failure, but changes file system contents
- From: Christoph Hellwig <hch at infradead dot org>
- To: "Darrick J. Wong" <darrick dot wong at oracle dot com>
- Cc: Florian Weimer <fw at deneb dot enyo dot de>, linux-xfs at vger dot kernel dot org, libc-alpha at sourceware dot org, linux-fsdevel at vger dot kernel dot org, viro at zeniv dot linux dot org dot uk
- Date: Wed, 12 Feb 2020 10:11:28 -0800
- Subject: Re: XFS reports lchmod failure, but changes file system contents
- References: <874kvwowke.fsf@mid.deneb.enyo.de> <20200212161604.GP6870@magnolia>
On Wed, Feb 12, 2020 at 08:16:04AM -0800, Darrick J. Wong wrote:
> xfs_setattr_nonsize calls posix_acl_chmod which returns EOPNOTSUPP
> because the xfs symlink inode_operations do not include a ->set_acl
> pointer.
>
> I /think/ that posix_acl_chmod code exists to enforce that the file mode
> reflects any acl that might be set on the inode, but in this case the
> inode is a symbolic link.
>
> I don't remember off the top of my head if ACLs are supposed to apply to
> symlinks, but what do you think about adding get_acl/set_acl pointers to
> xfs_symlink_inode_operations and xfs_inline_symlink_inode_operations ?
Symlinks don't have permissions or ACLs, so adding them makes no
sense.
xfs doesn't seem all that different from the other file systems,
so I suspect you'll also see it with other on-disk file systems.
We probably need a check high up in the chmod and co code to reject
the operation early for O_PATH file descriptors pointing to symlinks.