On Tue, Nov 23, 2021 at 10:25:20AM +0800, Jason Wang wrote: > On Tue, Nov 23, 2021 at 4:24 AM Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > > > On Mon, 22 Nov 2021 14:25:26 +0800 > > Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > > > I think the fixes are: > > > > > > 1) fixing the vhost vsock > > > 2) use suppress_used_validation=true to let vsock driver to validate > > > the in buffer length > > > 3) probably a new feature so the driver can only enable the validation > > > when the feature is enabled. > > > > I'm not sure, I would consider a F_DEV_Y_FIXED_BUG_X a perfectly good > > feature. Frankly the set of such bugs is device implementation > > specific and it makes little sense to specify a feature bit > > that says the device implementation claims to adhere to some > > aspect of the specification. Also what would be the semantic > > of not negotiating F_DEV_Y_FIXED_BUG_X? > > Yes, I agree. Rethink of the feature bit, it seems unnecessary, > especially considering the driver should not care about the used > length for tx. > > > > > On the other hand I see no other way to keep the validation > > permanently enabled for fixed implementations, and get around the problem > > with broken implementations. So we could have something like > > VHOST_USED_LEN_STRICT. > > It's more about a choice of the driver's knowledge. For vsock TX it > should be fine. If we introduce a parameter and disable it by default, > it won't be very useful. > > > > > Maybe, we can also think of 'warn and don't alter behavior' instead of > > 'warn' and alter behavior. Or maybe even not having such checks on in > > production, but only when testing. > > I think there's an agreement that virtio drivers need more hardening, > that's why a lot of patches were merged. Especially considering the > new requirements came from confidential computing, smart NIC and > VDUSE. For virtio drivers, enabling the validation may help to > > 1) protect the driver from the buggy and malicious device > 2) uncover the bugs of the devices (as vsock did, and probably rpmsg) > 3) force the have a smart driver that can do the validation itself > then we can finally remove the validation in the core > > So I'd like to keep it enabled. > > Thanks Let's see how far we can get. But yes, maybe we were too aggressive in breaking things by default, a warning might be a better choice for a couple of cycles. > > > > Regards, > > Halil > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
