linux-kernel - Re: [PATCH v1] vdpa: Complement vdpa_nl

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Message-ID: <00e14bc9e9a1f3749be62cbefc7adfaa1ba2d81c.camel@nvidia.com>
Date:   Tue, 25 Jul 2023 08:26:32 +0000
From:   Dragos Tatulea <dtatulea@...dia.com>
To:     "mst@...hat.com" <mst@...hat.com>
CC:     "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "linma@....edu.cn" <linma@....edu.cn>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Eli Cohen <elic@...dia.com>,
        "xuanzhuo@...ux.alibaba.com" <xuanzhuo@...ux.alibaba.com>,
        Parav Pandit <parav@...dia.com>
Subject: Re: [PATCH v1] vdpa: Complement vdpa_nl_policy for nlattr length
 check

On Mon, 2023-07-24 at 16:08 -0400, Michael S. Tsirkin wrote:
> On Mon, Jul 24, 2023 at 11:42:42AM +0000, Dragos Tatulea wrote:
> > On Mon, 2023-07-24 at 05:16 -0400, Michael S. Tsirkin wrote:
> > > On Mon, Jul 24, 2023 at 08:38:04AM +0000, Dragos Tatulea wrote:
> > > > 
> > > > On Mon, 2023-07-24 at 15:11 +0800, Jason Wang wrote:
> > > > > On Sun, Jul 23, 2023 at 6:02 PM Michael S. Tsirkin <mst@...hat.com>
> > > > > wrote:
> > > > > > 
> > > > > > On Sun, Jul 23, 2023 at 05:48:46PM +0800, Lin Ma wrote:
> > > > > > > 
> > > > > > > > Sure, that is another undergoing task I'm working on. If the
> > > > > > > > nlattr
> > > > > > > > is
> > > > > > > > parsed with
> > > > > > > > NL_VALIDATE_UNSPEC, any forgotten nlattr will be rejected,
> > > > > > > > therefore
> > > > > > > > (which is the default
> > > > > > > > for modern nla_parse).
> > > > > > > 
> > > > > > > For the general netlink interface, the deciding flag should be
> > > > > > > genl_ops.validate defined in
> > > > > > > each ops. The default validate flag is strict, while the developer
> > > > > > > can
> > > > > > > overwrite the flag
> > > > > > > with GENL_DONT_VALIDATE_STRICT to ease the validation. That is to
> > > > > > > say,
> > > > > > > safer code should
> > > > > > > enforce NL_VALIDATE_STRICT by not overwriting the validate flag.
> > > > > > > 
> > > > > > > Regrads
> > > > > > > Lin
> > > > > > 
> > > > > > 
> > > > > > Oh I see.
> > > > > > 
> > > > > > It started here:
> > > > > > 
> > > > > > commit 33b347503f014ebf76257327cbc7001c6b721956
> > > > > > Author: Parav Pandit <parav@...dia.com>
> > > > > > Date:   Tue Jan 5 12:32:00 2021 +0200
> > > > > > 
> > > > > >     vdpa: Define vdpa mgmt device, ops and a netlink interface
> > > > > > 
> > > > > > which did:
> > > > > > 
> > > > > > +               .validate = GENL_DONT_VALIDATE_STRICT |
> > > > > > GENL_DONT_VALIDATE_DUMP,
> > > > > > 
> > > > > > 
> > > > > > which was most likely just a copy paste from somewhere, right Parav?
> > > > > > 
> > > > > > and then everyone kept copying this around.
> > > > > > 
> > > > > > Parav, Eli can we drop these? There's a tiny chance of breaking
> > > > > > something
> > > > > > but I feel there aren't that many users outside mlx5 yet, so if you
> > > > > > guys can test on mlx5 and confirm no breakage, I think we are good.
> > > > > 
> > > > > Adding Dragos.
> > > > > 
> > > > I will check. Just to make sure I understand correctly: you want me to
> > > > drop
> > > > the
> > > > .validate flags all together in all vdpa ops and check, right?
> > > > 
> > > > Thanks,
> > > > Dragos
> > > 
> > > yes - I suspect you will then need this patch to make things work.
> > > 
> > Yep. Adding the patch and removing the .validate config on the vdpa_nl_ops
> > seems to work just fine.
> > 
> > Thanks,
> > Dragos
> 
> OK, post a patch?
> 
Sure, but how do I make it depend on this patch? Otherwise it will break things.

Thanks,
Dragos