[PATCH] nbd: restrict sockets to TCP and UDP
From: Eric Dumazet <edumazet@google.com>
Date: 2025-09-09 13:22:52
Also in:
linux-block, lkml
Subsystem:
block layer, network block device (nbd), the rest · Maintainers:
Jens Axboe, Josef Bacik, Linus Torvalds
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.
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