netfilter: nf_flow_table_offload: fix the nat port mangle.

Shift on 32-bit word to define the port number depends on the flow
direction.

Fixes: c29f74e0 ("netfilter: nf_flow_table: hardware offload support")
Fixes: 7acd9378 ("netfilter: nf_flow_table_offload: Correct memcpy size for flow_overload_mangle()")
Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_flow_table_offload.c

@@ -349,22 +349,26 @@ static void flow_offload_port_snat(struct net *net,
 				   struct nf_flow_rule *flow_rule)
 {
 	struct flow_action_entry *entry = flow_action_entry_next(flow_rule);
-	u32 mask = ~htonl(0xffff0000), port;
+	u32 mask, port;
 	u32 offset;
 
 	switch (dir) {
 	case FLOW_OFFLOAD_DIR_ORIGINAL:
 		port = ntohs(flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_port);
 		offset = 0; /* offsetof(struct tcphdr, source); */
+		port = htonl(port << 16);
+		mask = ~htonl(0xffff0000);
 		break;
 	case FLOW_OFFLOAD_DIR_REPLY:
 		port = ntohs(flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_port);
 		offset = 0; /* offsetof(struct tcphdr, dest); */
+		port = htonl(port);
+		mask = ~htonl(0xffff);
 		break;
 	default:
 		return;
 	}
-	port = htonl(port << 16);
+
 	flow_offload_mangle(entry, flow_offload_l4proto(flow), offset,
 			    &port, &mask);
 }
@@ -375,22 +379,26 @@ static void flow_offload_port_dnat(struct net *net,
 				   struct nf_flow_rule *flow_rule)
 {
 	struct flow_action_entry *entry = flow_action_entry_next(flow_rule);
-	u32 mask = ~htonl(0xffff), port;
+	u32 mask, port;
 	u32 offset;
 
 	switch (dir) {
 	case FLOW_OFFLOAD_DIR_ORIGINAL:
-		port = ntohs(flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.dst_port);
-		offset = 0; /* offsetof(struct tcphdr, source); */
+		port = ntohs(flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple.src_port);
+		offset = 0; /* offsetof(struct tcphdr, dest); */
+		port = htonl(port);
+		mask = ~htonl(0xffff);
 		break;
 	case FLOW_OFFLOAD_DIR_REPLY:
-		port = ntohs(flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.src_port);
-		offset = 0; /* offsetof(struct tcphdr, dest); */
+		port = ntohs(flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple.dst_port);
+		offset = 0; /* offsetof(struct tcphdr, source); */
+		port = htonl(port << 16);
+		mask = ~htonl(0xffff0000);
 		break;
 	default:
 		return;
 	}
-	port = htonl(port);
+
 	flow_offload_mangle(entry, flow_offload_l4proto(flow), offset,
 			    &port, &mask);
 }