+#ifdef CONFIG_NF_NAT_NEEDED
+/* Modelled after nf_nat_ipv[46]_fn().
+ * range is only used for new, uninitialized NAT state.
+ * Returns either NF_ACCEPT or NF_DROP.
+ */
+static int ovs_ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ const struct nf_nat_range *range,
+ enum nf_nat_manip_type maniptype)
+{
+ int hooknum, nh_off, err = NF_ACCEPT;
+
+ nh_off = skb_network_offset(skb);
+ skb_pull(skb, nh_off);
+
+ /* See HOOK2MANIP(). */
+ if (maniptype == NF_NAT_MANIP_SRC)
+ hooknum = NF_INET_LOCAL_IN; /* Source NAT */
+ else
+ hooknum = NF_INET_LOCAL_OUT; /* Destination NAT */
+
+ switch (ctinfo) {
+ case IP_CT_RELATED:
+ case IP_CT_RELATED_REPLY:
+ if (skb->protocol == htons(ETH_P_IP) &&
+ ip_hdr(skb)->protocol == IPPROTO_ICMP) {
+ if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
+ hooknum))
+ err = NF_DROP;
+ goto push;
+#if IS_ENABLED(CONFIG_NF_NAT_IPV6)
+ } else if (skb->protocol == htons(ETH_P_IPV6)) {
+ __be16 frag_off;
+ u8 nexthdr = ipv6_hdr(skb)->nexthdr;
+ int hdrlen = ipv6_skip_exthdr(skb,
+ sizeof(struct ipv6hdr),
+ &nexthdr, &frag_off);
+
+ if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
+ if (!nf_nat_icmpv6_reply_translation(skb, ct,
+ ctinfo,
+ hooknum,
+ hdrlen))
+ err = NF_DROP;
+ goto push;
+ }
+#endif
+ }
+ /* Non-ICMP, fall thru to initialize if needed. */
+ case IP_CT_NEW:
+ /* Seen it before? This can happen for loopback, retrans,
+ * or local packets.
+ */
+ if (!nf_nat_initialized(ct, maniptype)) {
+ /* Initialize according to the NAT action. */
+ err = (range && range->flags & NF_NAT_RANGE_MAP_IPS)
+ /* Action is set up to establish a new
+ * mapping.
+ */
+ ? nf_nat_setup_info(ct, range, maniptype)
+ : nf_nat_alloc_null_binding(ct, hooknum);
+ if (err != NF_ACCEPT)
+ goto push;
+ }
+ break;
+
+ case IP_CT_ESTABLISHED:
+ case IP_CT_ESTABLISHED_REPLY:
+ break;
+
+ default:
+ err = NF_DROP;
+ goto push;
+ }
+
+ err = nf_nat_packet(ct, ctinfo, hooknum, skb);
+push:
+ skb_push(skb, nh_off);
+
+ return err;
+}
+
+static void ovs_nat_update_key(struct sw_flow_key *key,
+ const struct sk_buff *skb,
+ enum nf_nat_manip_type maniptype)
+{
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ __be16 src;
+
+ key->ct.state |= OVS_CS_F_SRC_NAT;
+ if (key->eth.type == htons(ETH_P_IP))
+ key->ipv4.addr.src = ip_hdr(skb)->saddr;
+ else if (key->eth.type == htons(ETH_P_IPV6))
+ memcpy(&key->ipv6.addr.src, &ipv6_hdr(skb)->saddr,
+ sizeof(key->ipv6.addr.src));
+ else
+ return;
+
+ if (key->ip.proto == IPPROTO_UDP)
+ src = udp_hdr(skb)->source;
+ else if (key->ip.proto == IPPROTO_TCP)
+ src = tcp_hdr(skb)->source;
+ else if (key->ip.proto == IPPROTO_SCTP)
+ src = sctp_hdr(skb)->source;
+ else
+ return;
+
+ key->tp.src = src;
+ } else {
+ __be16 dst;
+
+ key->ct.state |= OVS_CS_F_DST_NAT;
+ if (key->eth.type == htons(ETH_P_IP))
+ key->ipv4.addr.dst = ip_hdr(skb)->daddr;
+ else if (key->eth.type == htons(ETH_P_IPV6))
+ memcpy(&key->ipv6.addr.dst, &ipv6_hdr(skb)->daddr,
+ sizeof(key->ipv6.addr.dst));
+ else
+ return;
+
+ if (key->ip.proto == IPPROTO_UDP)
+ dst = udp_hdr(skb)->dest;
+ else if (key->ip.proto == IPPROTO_TCP)
+ dst = tcp_hdr(skb)->dest;
+ else if (key->ip.proto == IPPROTO_SCTP)
+ dst = sctp_hdr(skb)->dest;
+ else
+ return;
+
+ key->tp.dst = dst;
+ }
+}
+
+/* Returns NF_DROP if the packet should be dropped, NF_ACCEPT otherwise. */
+static int ovs_ct_nat(struct net *net, struct sw_flow_key *key,
+ const struct ovs_conntrack_info *info,
+ struct sk_buff *skb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo)
+{
+ enum nf_nat_manip_type maniptype;
+ int err;
+
+ if (nf_ct_is_untracked(ct)) {
+ /* A NAT action may only be performed on tracked packets. */
+ return NF_ACCEPT;
+ }
+
+ /* Add NAT extension if not confirmed yet. */
+ if (!nf_ct_is_confirmed(ct) && !nf_ct_nat_ext_add(ct))
+ return NF_ACCEPT; /* Can't NAT. */
+
+ /* Determine NAT type.
+ * Check if the NAT type can be deduced from the tracked connection.
+ * Make sure expected traffic is NATted only when committing.
+ */
+ if (info->nat & OVS_CT_NAT && ctinfo != IP_CT_NEW &&
+ ct->status & IPS_NAT_MASK &&
+ (!(ct->status & IPS_EXPECTED_BIT) || info->commit)) {
+ /* NAT an established or related connection like before. */
+ if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY)
+ /* This is the REPLY direction for a connection
+ * for which NAT was applied in the forward
+ * direction. Do the reverse NAT.
+ */
+ maniptype = ct->status & IPS_SRC_NAT
+ ? NF_NAT_MANIP_DST : NF_NAT_MANIP_SRC;
+ else
+ maniptype = ct->status & IPS_SRC_NAT
+ ? NF_NAT_MANIP_SRC : NF_NAT_MANIP_DST;
+ } else if (info->nat & OVS_CT_SRC_NAT) {
+ maniptype = NF_NAT_MANIP_SRC;
+ } else if (info->nat & OVS_CT_DST_NAT) {
+ maniptype = NF_NAT_MANIP_DST;
+ } else {
+ return NF_ACCEPT; /* Connection is not NATed. */
+ }
+ err = ovs_ct_nat_execute(skb, ct, ctinfo, &info->range, maniptype);
+
+ /* Mark NAT done if successful and update the flow key. */
+ if (err == NF_ACCEPT)
+ ovs_nat_update_key(key, skb, maniptype);
+
+ return err;
+}
+#else /* !CONFIG_NF_NAT_NEEDED */
+static int ovs_ct_nat(struct net *net, struct sw_flow_key *key,
+ const struct ovs_conntrack_info *info,
+ struct sk_buff *skb, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo)
+{
+ return NF_ACCEPT;
+}
+#endif
+