Re: [PATCH] nbd: restrict sockets to TCP and UDP
From: Richard W.M. Jones <hidden>
Date: 2025-09-09 13:32:46
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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. Rich.
quoted hunk ↗ jump to hunk
Fixes: cf1b2326b734 ("nbd: verify socket is supported during setup") Reported-by: syzbot+e1cd6bd8493060bd701d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/CANn89iJ+76eE3A_8S_zTpSyW5hvPRn6V57458hCZGY5hbH_bFA@mail.gmail.com/T/#m081036e8747cd7e2626c1da5d78c8b9d1e55b154 (local) Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Mike Christie <redacted> Cc: Richard W.M. Jones <redacted> Cc: Jens Axboe <axboe@kernel.dk> Cc: Yu Kuai <redacted> Cc: linux-block@vger.kernel.org Cc: nbd@other.debian.org --- drivers/block/nbd.c | 8 ++++++++ 1 file changed, 8 insertions(+)diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 6463d0e8d0cef71e73e67fecd16de4dec1c75da7..87b0b78249da3325023949585f4daf40486c9692 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c@@ -1217,6 +1217,14 @@ static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd, if (!sock) return NULL; + if (!sk_is_tcp(sock->sk) && + !sk_is_stream_unix(sock->sk)) { + dev_err(disk_to_dev(nbd->disk), "Unsupported socket: should be TCP or UNIX.\n"); + *err = -EINVAL; + sockfd_put(sock); + return NULL; + } + if (sock->ops->shutdown == sock_no_shutdown) { dev_err(disk_to_dev(nbd->disk), "Unsupported socket: shutdown callout must be supported.\n"); *err = -EINVAL;-- 2.51.0.384.g4c02a37b29-goog
-- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html