smc: disallow TCP_ULP in smc_setsockopt()

[ Upstream commit 8621436671f3a4bba5db57482e1ee604708bf1eb ]

syzbot is able to setup kTLS on an SMC socket which coincidentally
uses sk_user_data too. Later, kTLS treats it as psock so triggers a
refcnt warning. The root cause is that smc_setsockopt() simply calls
TCP setsockopt() which includes TCP_ULP. I do not think it makes
sense to setup kTLS on top of SMC sockets, so we should just disallow
this setup.

It is hard to find a commit to blame, but we can apply this patch
since the beginning of TCP_ULP.

Reported-and-tested-by: syzbot+b54a1ce86ba4a623b7f0@syzkaller.appspotmail.com
Fixes: 734942cc4ea6 ("tcp: ULP infrastructure")
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 47340b3b514f3bc484eaa885a95f7b668d777492..cb23cca72c24c25c22c8b7b77727477bf50bc1a3 100644 (file)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -2162,6 +2162,9 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
        struct smc_sock *smc;
        int val, rc;
 
+       if (level == SOL_TCP && optname == TCP_ULP)
+               return -EOPNOTSUPP;
+
        smc = smc_sk(sk);
 
        /* generic setsockopts reaching us here always apply to the
@@ -2186,7 +2189,6 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
        if (rc || smc->use_fallback)
                goto out;
        switch (optname) {
-       case TCP_ULP:
        case TCP_FASTOPEN:
        case TCP_FASTOPEN_CONNECT:
        case TCP_FASTOPEN_KEY: