sockmap, vsock: For connectible sockets allow only connected

[ Upstream commit 8fb5bb1 ]

sockmap expects all vsocks to have a transport assigned, which is expressed
in vsock_proto::psock_update_sk_prot(). However, there is an edge case
where an unconnected (connectible) socket may lose its previously assigned
transport. This is handled with a NULL check in the vsock/BPF recv path.

Another design detail is that listening vsocks are not supposed to have any
transport assigned at all. Which implies they are not supported by the
sockmap. But this is complicated by the fact that a socket, before
switching to TCP_LISTEN, may have had some transport assigned during a
failed connect() attempt. Hence, we may end up with a listening vsock in a
sockmap, which blows up quickly:

KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127]
CPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 Not tainted 6.14.0-rc1+
Workqueue: vsock-loopback vsock_loopback_work
RIP: 0010:vsock_read_skb+0x4b/0x90
Call Trace:
 sk_psock_verdict_data_ready+0xa4/0x2e0
 virtio_transport_recv_pkt+0x1ca8/0x2acc
 vsock_loopback_work+0x27d/0x3f0
 process_one_work+0x846/0x1420
 worker_thread+0x5b3/0xf80
 kthread+0x35a/0x700
 ret_from_fork+0x2d/0x70
 ret_from_fork_asm+0x1a/0x30

For connectible sockets, instead of relying solely on the state of
vsk->transport, tell sockmap to only allow those representing established
connections. This aligns with the behaviour for AF_INET and AF_UNIX.

Fixes: 634f1a7 ("vsock: support sockmap")
Signed-off-by: Michal Luczaj <[email protected]>
Acked-by: Stefano Garzarella <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
(cherry picked from commit 22b683217ad2112791a708693cb236507abd637a)
Signed-off-by: Jack Vogel <[email protected]>

Author: mmhal

net/core/sock_map.c

@@ -541,6 +541,9 @@ static bool sock_map_sk_state_allowed(const struct sock *sk)
 		return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_LISTEN);
 	if (sk_is_stream_unix(sk))
 		return (1 << sk->sk_state) & TCPF_ESTABLISHED;
+	if (sk_is_vsock(sk) &&
+	    (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET))
+		return (1 << sk->sk_state) & TCPF_ESTABLISHED;
 	return true;
 }