Re: [PATCH] nbd: restrict sockets to TCP and UDP

[Eric Dumazet]

On Tue, Sep 9, 2025 at 6:32 AM Richard W.M. Jones <rjones@xxxxxxxxxx> wrote:
>
> On Tue, Sep 09, 2025 at 01:22:43PM +0000, Eric Dumazet wrote:
> > Recently, syzbot started to abuse NBD with all kinds of sockets.
> >
> > Commit cf1b2326b734 ("nbd: verify socket is supported during setup")
> > made sure the socket supported a shutdown() method.
> >
> > Explicitely accept TCP and UNIX stream sockets.
>
> I'm not clear what the actual problem is, but I will say that libnbd &
> nbdkit (which are another NBD client & server, interoperable with the
> kernel) we support and use NBD over vsock[1].  And we could support
> NBD over pretty much any stream socket (Infiniband?) [2].
>
> [1] https://libguestfs.org/nbd_aio_connect_vsock.3.html
>     https://libguestfs.org/nbdkit-service.1.html#AF_VSOCK
> [2] https://libguestfs.org/nbd_connect_socket.3.html
>
> TCP and Unix domain sockets are by far the most widely used, but I
> don't think it's fair to exclude other socket types.

If we have known and supported socket types, please send a patch to add them.

I asked the question last week and got nothing about vsock or other types.

https://lore.kernel.org/netdev/CANn89iLNFHBMTF2Pb6hHERYpuih9eQZb6A12+ndzBcQs_kZoBA@xxxxxxxxxxxxxx/

For sure, we do not want datagram sockets, RAW, netlink, and many others.