From: "Michael S. Tsirkin" <mst@redhat.com>
To: Max Gurtovoy <mgurtovoy@nvidia.com>
Cc: Yongji Xie <xieyongji@bytedance.com>,
Jason Wang <jasowang@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
virtualization <virtualization@lists.linux-foundation.org>,
linux-block@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5] virtio-blk: Add validation for block size in config space
Date: Mon, 23 Aug 2021 08:13:34 -0400 [thread overview]
Message-ID: <20210823080952-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <7f0181d7-ff5c-0346-66ee-1de3ed23f5dd@nvidia.com>
On Mon, Aug 23, 2021 at 01:45:31PM +0300, Max Gurtovoy wrote:
> It helpful if there is a justification for this.
>
> In this case, no such HW device exist and the only device that can cause
> this trouble today is user space VDUSE device that must be validated by the
> emulation VDUSE kernel driver.
>
> Otherwise, will can create 1000 commit like this in the virtio level (for
> example for each feature for each virtio device).
Yea, it's a lot of work but I don't think it's avoidable.
> >
> > > > > > And regardless of userspace device, we still need to fix it for other cases.
> > > > > which cases ? Do you know that there is a buggy HW we need to workaround ?
> > > > >
> > > > No, there isn't now. But this could be a potential attack surface if
> > > > the host doesn't trust the device.
> > > If the host doesn't trust a device, why it continues using it ?
> > >
> > IIUC this is the case for the encrypted VMs.
>
> what do you mean encrypted VM ?
>
> And how this small patch causes a VM to be 100% encryption supported ?
>
> > > Do you suggest we do these workarounds in all device drivers in the kernel ?
> > >
> > Isn't it the driver's job to validate some unreasonable configuration?
>
> The check should be in different layer.
>
> Virtio blk driver should not cover on some strange VDUSE stuff.
Yes I'm not convinced VDUSE is a valid use-case. I think that for
security and robustness it should validate data it gets from userspace
right there after reading it.
But I think this is useful for the virtio hardening thing.
https://lwn.net/Articles/865216/
Yongji - I think the commit log should be much more explicit that
this is hardening. Otherwise people get confused and think this
needs a CVE or a backport for security.
--
MST
next prev parent reply other threads:[~2021-08-23 12:14 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-09 10:16 [PATCH v5] virtio-blk: Add validation for block size in config space Xie Yongji
2021-08-10 3:05 ` Jason Wang
2021-08-10 4:59 ` Yongji Xie
2021-08-10 6:59 ` Jason Wang
2021-08-22 23:17 ` Max Gurtovoy
2021-08-23 4:31 ` Yongji Xie
2021-08-23 8:07 ` Max Gurtovoy
2021-08-23 8:35 ` Yongji Xie
2021-08-23 9:04 ` Max Gurtovoy
2021-08-23 9:27 ` Yongji Xie
2021-08-23 9:38 ` Max Gurtovoy
2021-08-23 10:33 ` Yongji Xie
2021-08-23 10:45 ` Max Gurtovoy
2021-08-23 11:41 ` Yongji Xie
2021-08-23 12:13 ` Michael S. Tsirkin [this message]
2021-08-23 12:40 ` Yongji Xie
2021-08-23 16:02 ` Michael S. Tsirkin
2021-08-23 22:31 ` Max Gurtovoy
2021-08-24 2:47 ` Jason Wang
2021-08-24 10:11 ` Max Gurtovoy
2021-08-24 12:52 ` Yongji Xie
2021-08-24 13:30 ` Max Gurtovoy
2021-08-24 13:38 ` Yongji Xie
2021-08-24 13:48 ` Max Gurtovoy
2021-10-04 15:27 ` Michael S. Tsirkin
2021-10-04 15:39 ` Michael S. Tsirkin
2021-10-05 15:52 ` Yongji Xie
2021-10-05 10:42 ` Michael S. Tsirkin
2021-10-05 15:45 ` Yongji Xie
2021-10-05 18:26 ` Martin K. Petersen
2021-10-11 11:40 ` Christoph Hellwig
2021-10-13 12:21 ` Michael S. Tsirkin
2021-10-13 12:34 ` Yongji Xie
2021-10-13 12:51 ` Michael S. Tsirkin
2021-10-13 12:59 ` Yongji Xie
2021-10-05 15:24 ` Yongji Xie
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