net: diag: support v4mapped sockets in inet_diag_find_one_icsk()

Lorenzo reported that we could not properly find v4mapped sockets
in inet_diag_find_one_icsk(). This patch fixes the issue.
Reported-by: NLorenzo Colitti <lorenzo@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NLorenzo Colitti <lorenzo@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/inet_diag.c

@@ -361,13 +361,20 @@ struct sock *inet_diag_find_one_icsk(struct net *net,
 				 req->id.idiag_dport, req->id.idiag_src[0],
 				 req->id.idiag_sport, req->id.idiag_if);
 #if IS_ENABLED(CONFIG_IPV6)
-	else if (req->sdiag_family == AF_INET6)
-		sk = inet6_lookup(net, hashinfo,
-				  (struct in6_addr *)req->id.idiag_dst,
-				  req->id.idiag_dport,
-				  (struct in6_addr *)req->id.idiag_src,
-				  req->id.idiag_sport,
-				  req->id.idiag_if);
+	else if (req->sdiag_family == AF_INET6) {
+		if (ipv6_addr_v4mapped((struct in6_addr *)req->id.idiag_dst) &&
+		    ipv6_addr_v4mapped((struct in6_addr *)req->id.idiag_src))
+			sk = inet_lookup(net, hashinfo, req->id.idiag_dst[3],
+					 req->id.idiag_dport, req->id.idiag_src[3],
+					 req->id.idiag_sport, req->id.idiag_if);
+		else
+			sk = inet6_lookup(net, hashinfo,
+					  (struct in6_addr *)req->id.idiag_dst,
+					  req->id.idiag_dport,
+					  (struct in6_addr *)req->id.idiag_src,
+					  req->id.idiag_sport,
+					  req->id.idiag_if);
+	}
 #endif
 	else
 		return ERR_PTR(-EINVAL);