[Gluster-users] Restrict root clients / experimental patch

[Pierre C]

Hi All,

I would like to use glusterfs in an environment where storage servers are
managed by an IT service - myself :) - and several users in the
organization can mount the distributed fs. The users are root on their
machines.
As far as I know about glusterfs, a root client user may impersonate any
uid/gid since it provides its uid/gid itself when it talks to the bricks
(like nfsv3).
The thing is, we want to enforce permissions, i.e. user X may only access
files shared with him even if he's root on his machine.
I found a draft spec about glusterfs+kerberos
<https://github.com/gluster/glusterfs-specs/blob/master/under_review/Kerberos.md>
but not much more so I think it's not possible with glusterfs right now,
correct?
(Also I feel that kerberos would be a bit heavy to manage)

---

An simple hack that I found is to add custom uid/gid fields in clients' ssl
certificates. The bricks use the client's uid/gid specified in its
certificate rather than using one specified by the user. This solution has
no effect on performance and there's no need for a central authentication.
The thing that changes is the way client certificates are generated and
glusterfsd needs a small patch.

I did an experimental implementation
<https://github.com/eshard/glusterfs/commit/768bf63154fdc59ba67d5788743adab8679ec5ab>
of this idea. Custom fields "1.2.3.4.5.6.7" and "1.2.3.4.5.6.8" are used
for uid and gid.
I tried it with custom CA trusted by all bricks and I issued a few client
certificates.
No server configuration is needed when a new client is added, when a client
is revoked the a CRL
<https://en.wikipedia.org/wiki/Certificate_revocation_list> must updated
and pushed to all servers.
By the way I didn't get glusterfs servers to accept my CRLs, do some people
use it?

Notes:
 * groups are not handled right now and since users may change groups
regularly I don't think it would be a great idea to freeze them in a
certificate. The bricks could possibly do an ldap lookup in order to
retrieve and cache the groups for an uid.
 * Clients obviously can't modify their certificates because they are
signed by CA

What do you think of this implementation, is it safe?
Do all client operations use auth_glusterfs_v2_authenticate or did I miss
other codepaths?

Thanks!

Pierre Carru
eshard

PS: By the way I found the source code very clean and well organized, nice
job :)
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