bpf: Check the protocol of a sock to agree the calls to bpf_setsockopt().

Resolve an issue when calling sol_tcp_sockopt() on a socket with ktls
enabled. Prior to this patch, sol_tcp_sockopt() would only allow calls
if the function pointer of setsockopt of the socket was set to
tcp_setsockopt(). However, any socket with ktls enabled would have its
function pointer set to tls_setsockopt(). To resolve this issue, the
patch adds a check of the protocol of the linux socket and allows
bpf_setsockopt() to be called if ktls is initialized on the linux
socket. This ensures that calls to sol_tcp_sockopt() will succeed on
sockets with ktls enabled.
Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Link: https://lore.kernel.org/r/20230125201608.908230-2-kuifeng@meta.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

net/core/filter.c

@@ -5204,7 +5204,7 @@ static int sol_tcp_sockopt(struct sock *sk, int optname,
 			   char *optval, int *optlen,
 			   bool getopt)
 {
-	if (sk->sk_prot->setsockopt != tcp_setsockopt)
+	if (sk->sk_protocol != IPPROTO_TCP)
 		return -EINVAL;
 
 	switch (optname) {