Re: [PATCH] overlayfs: ignore empty NFSv4 ACLs in ext4 upperdir

[Andreas Gruenbacher]

On Thu, 2 May 2019 at 19:16, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
> On Thu, May 02, 2019 at 05:08:14PM +0200, Andreas GrÃnbacher wrote:
> > You'll still see permissions that differ from what the filesystem
> > enforces, and copy-up would change that behavior.
>
> That's always true, and this issue isn't really specific to NFSv4 ACLs
> (or ACLs at all), it already exists with just mode bits.  The client
> doesn't know how principals may be mapped on the server, doesn't know
> group membership, etc.
>
> That's the usual model, anyway.  Permissions are almost entirely the
> server's responsibility, and we just provide a few attributes to set/get
> those server-side permissions.

Sure, if the client and server don't share the same user and group
databases, ACLs can get a very different meaning.

Andreas

> The overlayfs/NFS case is different, I think: the nfs filesystem may be
> just a static read-only template for a filesystem that's only ever used
> by clients, and for all I know maybe permissions should only be
> interpreted on the client side in that case.
>
> --b.