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From: Trond Myklebust <trondmy@hammerspace.com>
To: "bfields@fieldses.org" <bfields@fieldses.org>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"Anna.Schumaker@netapp.com" <Anna.Schumaker@netapp.com>
Subject: Re: [PATCH 6/9] NFSv4: Convert the NFS client idmapper to use the container user namespace
Date: Thu, 25 Apr 2019 16:40:18 +0000
Message-ID: <e3553fd56047430f171a3c285150b56d5fc69ccd.camel@hammerspace.com> (raw)
In-Reply-To: <20190425153339.GB8133@fieldses.org>

On Thu, 2019-04-25 at 11:33 -0400, bfields@fieldses.org wrote:
> On Thu, Apr 25, 2019 at 03:00:22PM +0000, Trond Myklebust wrote:
> > The assumption is that if you have enough privileges to mount a
> > filesystem using the NFS client, then you would also have enough
> > privileges to run a userspace client, so there is little point in
> > restricting the NFS client.
> > 
> > So the guiding principle is that a NFS client mount that is started
> > in
> > a container should behave as if it were started by a process in a
> > "real
> > VM". That means that the root uid/gid in the container maps to a
> > root
> > uid/gid on the wire.
> > Ditto, if there is a need to run the idmapper in the container,
> > then
> > the expectation is that processes running as 'user' with uid 'u',
> > will
> > see their creds mapped correctly by the idmapper. Again, that's
> > what
> > you would see if the process were running in a VM instead of a
> > container.
> > 
> > Does that all make sense?
> 
> Yes, thanks!
> 
> I thought there was a problem that the idmapper depended on
> keyring usermodehelper calls that it was hard to pass namespace
> information to.  Did that get fixed and I missed it or or forgot?

No, you are correct, and so we assume the container is using rpc.idmapd
(and rpc.gssd) if it is running NFSv4 with RPCSEC_GSS.

If the keyring upcall gets fixed, then we may allow it to be used in
future kernels.

> > So this means that any orchestrator software which may be setting
> > up
> > NFS mounts as part of setting up the container has 2 options:
> > 
> >    1. Either perform the mount outside the container namespaces, in
> > which
> >       case the container process uids/gids are mapped from their
> >       user_namespace into the user_namespace of the orchestrator,
> > and the
> >       uids/gids on the wire will reflect those mapped uids/gids (so
> > uid 0
> >       in the container will be mapped to uid xxx where xxx is
> > decided by
> >       the orchestrator).
> >    2. Perform the mount inside the container namespaces, in which
> > case the
> >       container process uids/gids go on the wire as-is.
> 
> OK, great, that sounds perfect.
> 
> --b.
-- 
Trond Myklebust
CTO, Hammerspace Inc
4300 El Camino Real, Suite 105
Los Altos, CA 94022
www.hammer.space



  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-24 21:46 [PATCH 0/9] Client container fixes Trond Myklebust
2019-04-24 21:46 ` [PATCH 1/9] SUNRPC: Cache cred of process creating the rpc_client Trond Myklebust
2019-04-24 21:46   ` [PATCH 2/9] NFS: Store the credential of the mount process in the nfs_server Trond Myklebust
2019-04-24 21:46     ` [PATCH 3/9] SUNRPC: Use the client user namespace when encoding creds Trond Myklebust
2019-04-24 21:46       ` [PATCH 4/9] SUNRPC: Use namespace of listening daemon in the client AUTH_GSS upcall Trond Myklebust
2019-04-24 21:46         ` [PATCH 5/9] NFS: Convert NFSv3 to use the container user namespace Trond Myklebust
2019-04-24 21:46           ` [PATCH 6/9] NFSv4: Convert the NFS client idmapper " Trond Myklebust
2019-04-24 21:46             ` [PATCH 7/9] NFS: Convert NFSv2 " Trond Myklebust
2019-04-24 21:46               ` [PATCH 8/9] NFS: When mounting, don't share filesystems between different user namespaces Trond Myklebust
2019-04-24 21:46                 ` [PATCH 9/9] lockd: Store the lockd client credential in struct nlm_host Trond Myklebust
2019-04-25 14:32             ` [PATCH 6/9] NFSv4: Convert the NFS client idmapper to use the container user namespace bfields
2019-04-25 15:00               ` Trond Myklebust
2019-04-25 15:33                 ` bfields
2019-04-25 16:40                   ` Trond Myklebust [this message]
2019-04-25 16:45                     ` bfields
2019-04-25 16:48                       ` Trond Myklebust
2019-04-25 20:16                         ` bfields
2019-06-14 18:52   ` [PATCH 1/9] SUNRPC: Cache cred of process creating the rpc_client Ido Schimmel
2019-06-20 12:33     ` Ido Schimmel

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