netdev - [Patch bpf-next] unix_bpf: check socket type in unix_bpf_update

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Message-Id: <20210731195038.8084-1-xiyou.wangcong@gmail.com>
Date:   Sat, 31 Jul 2021 12:50:38 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     bpf@...r.kernel.org, jiang.wang@...edance.com,
        Cong Wang <cong.wang@...edance.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: [Patch bpf-next] unix_bpf: check socket type in unix_bpf_update_proto()

From: Cong Wang <cong.wang@...edance.com>

As of now, only AF_UNIX datagram socket supports sockmap.
But unix_proto is shared for all kinds of AF_UNIX sockets,
so we have to check the socket type in
unix_bpf_update_proto() to explicitly reject other types,
otherwise they could be added into sockmap too.

Fixes: c63829182c37 ("af_unix: Implement ->psock_update_sk_prot()")
Reported-by: Jakub Sitnicki <jakub@...udflare.com>
Cc: John Fastabend <john.fastabend@...il.com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Lorenz Bauer <lmb@...udflare.com>
Signed-off-by: Cong Wang <cong.wang@...edance.com>
---
 net/unix/unix_bpf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
index 177e883f451e..20f53575b5c9 100644
--- a/net/unix/unix_bpf.c
+++ b/net/unix/unix_bpf.c
@@ -105,6 +105,9 @@ static void unix_bpf_check_needs_rebuild(struct proto *ops)
 
 int unix_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 {
+	if (sk->sk_type != SOCK_DGRAM)
+		return -EOPNOTSUPP;
+
 	if (restore) {
 		sk->sk_write_space = psock->saved_write_space;
 		WRITE_ONCE(sk->sk_prot, psock->sk_proto);
-- 
2.27.0