On 6/9/23 18:12, Aleksandr Mikhalitsyn wrote:
On Fri, Jun 9, 2023 at 12:00 PM Christian Brauner <brauner@xxxxxxxxxx> wrote:
On Fri, Jun 09, 2023 at 10:59:19AM +0200, Aleksandr Mikhalitsyn wrote:
On Fri, Jun 9, 2023 at 3:57 AM Xiubo Li <xiubli@xxxxxxxxxx> wrote:
On 6/8/23 23:42, Alexander Mikhalitsyn wrote:
Dear friends,
This patchset was originally developed by Christian Brauner but I'll continue
to push it forward. Christian allowed me to do that :)
This feature is already actively used/tested with LXD/LXC project.
Git tree (based on https://github.com/ceph/ceph-client.git master):
Hi Xiubo!
Could you rebase these patches to 'testing' branch ?
Will do in -v6.
And you still have missed several places, for example the following cases:
1 269 fs/ceph/addr.c <<ceph_netfs_issue_op_inline>>
req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_GETATTR,
mode);
+
2 389 fs/ceph/dir.c <<ceph_readdir>>
req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
+
3 789 fs/ceph/dir.c <<ceph_lookup>>
req = ceph_mdsc_create_request(mdsc, op, USE_ANY_MDS);
We don't have an idmapping passed to lookup from the VFS layer. As I
mentioned before, it's just impossible now.
->lookup() doesn't deal with idmappings and really can't otherwise you
risk ending up with inode aliasing which is really not something you
want. IOW, you can't fill in inode->i_{g,u}id based on a mount's
idmapping as inode->i_{g,u}id absolutely needs to be a filesystem wide
value. So better not even risk exposing the idmapping in there at all.
Thanks for adding, Christian!
I agree, every time when we use an idmapping we need to be careful with
what we map. AFAIU, inode->i_{g,u}id should be based on the filesystem
idmapping (not mount),
but in this case, Xiubo want's current_fs{u,g}id to be mapped
according to an idmapping.
Anyway, it's impossible at now and IMHO, until we don't have any
practical use case where
UID/GID-based path restriction is used in combination with idmapped
mounts it's not worth to
make such big changes in the VFS layer.
May be I'm not right, but it seems like UID/GID-based path restriction
is not a widespread
feature and I can hardly imagine it to be used with the container
workloads (for instance),
because it will require to always keep in sync MDS permissions
configuration with the
possible UID/GID ranges on the client. It looks like a nightmare for sysadmin.
It is useful when cephfs is used as an external storage on the host, but if you
share cephfs with a few containers with different user namespaces idmapping...
Hmm, while this will break the MDS permission check in cephfs then in
lookup case. If we really couldn't support it we should make it to
escape the check anyway or some OPs may fail and won't work as expected.
@Greg
For the lookup requests the idmapping couldn't get the mapped UID/GID
just like all the other requests, which is needed by the MDS permission
check. Is that okay to make it disable the check for this case ? I am
afraid this will break the MDS permssions logic.
Any idea ?
Thanks
- Xiubo
Kind regards,
Alex
