On 6/24/23 15:11, Aleksandr Mikhalitsyn wrote:
On Sat, Jun 24, 2023 at 3:37 AM Xiubo Li <xiubli@xxxxxxxxxx> wrote:
[...]
> > >
> > > I thought about this too and came to the same conclusion, that
UID/GID
> > > based
> > > restriction can be applied dynamically, so detecting it on mount-time
> > > helps not so much.
> > >
> > For this you please raise one PR to ceph first to support this, and in
> > the PR we can discuss more for the MDS auth caps. And after the PR
> > getting merged then in this patch series you need to check the
> > corresponding option or flag to determine whether could the idmap
> > mounting succeed.
>
> I'm sorry but I don't understand what we want to support here. Do we
want to
> add some new ceph request that allows to check if UID/GID-based
> permissions are applied for
> a particular ceph client user?
IMO we should prevent user to set UID/GID-based permisions caps from
ceph side.
As I know currently there is no way to prevent users to set MDS auth
caps, IMO in ceph side at least we need one flag or option to disable
this once users want this fs cluster sever for idmap mounts use case.
How this should be visible from the user side? We introducing a new
kernel client mount option,
like "nomdscaps", then pass flag to the MDS and MDS should check that
MDS auth permissions
are not applied (on the mount time) and prevent them from being
applied later while session is active. Like that?
At the same time I'm thinking about protocol extension that adds 2
additional fields for UID/GID. This will allow to correctly
handle everything. I wanted to avoid any changes to the protocol or
server-side things. But if we want to change MDS side,
maybe it's better then to go this way?
There is another way:
For each client it will have a dedicated client auth caps, something like:
client.foo
key: *key*
caps: [mds] allow r, allow rw path=/bar
caps: [mon] allow r
caps: [osd] allow rw tag cephfs data=cephfs_a
When mounting this client with idmap enabled, then we can just check the
above [mds] caps, if there has any UID/GID based permissions set, then
fail the mounting.
That means this kind client couldn't be mounted with idmap enabled.
Also we need to make sure that once there is a mount with idmap enabled,
the corresponding client caps couldn't be append the UID/GID based
permissions. This need a patch in ceph anyway IMO.
Thanks
- Xiubo
Thanks,
Alex
Thanks
- Xiubo
