v4.19.13 snapshot.
diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
new file mode 100644
index 0000000..f8de248
--- /dev/null
+++ b/net/ipv4/xfrm4_input.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * xfrm4_input.c
+ *
+ * Changes:
+ * YOSHIFUJI Hideaki @USAGI
+ * Split up af-specific portion
+ * Derek Atkins <derek@ihtfp.com>
+ * Add Encapsulation support
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <net/ip.h>
+#include <net/xfrm.h>
+
+int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+ return xfrm4_extract_header(skb);
+}
+
+static int xfrm4_rcv_encap_finish2(struct net *net, struct sock *sk,
+ struct sk_buff *skb)
+{
+ return dst_input(skb);
+}
+
+static inline int xfrm4_rcv_encap_finish(struct net *net, struct sock *sk,
+ struct sk_buff *skb)
+{
+ if (!skb_dst(skb)) {
+ const struct iphdr *iph = ip_hdr(skb);
+
+ if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
+ iph->tos, skb->dev))
+ goto drop;
+ }
+
+ if (xfrm_trans_queue(skb, xfrm4_rcv_encap_finish2))
+ goto drop;
+
+ return 0;
+drop:
+ kfree_skb(skb);
+ return NET_RX_DROP;
+}
+
+int xfrm4_transport_finish(struct sk_buff *skb, int async)
+{
+ struct xfrm_offload *xo = xfrm_offload(skb);
+ struct iphdr *iph = ip_hdr(skb);
+
+ iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
+
+#ifndef CONFIG_NETFILTER
+ if (!async)
+ return -iph->protocol;
+#endif
+
+ __skb_push(skb, skb->data - skb_network_header(skb));
+ iph->tot_len = htons(skb->len);
+ ip_send_check(iph);
+
+ if (xo && (xo->flags & XFRM_GRO)) {
+ skb_mac_header_rebuild(skb);
+ skb_reset_transport_header(skb);
+ return 0;
+ }
+
+ NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
+ dev_net(skb->dev), NULL, skb, skb->dev, NULL,
+ xfrm4_rcv_encap_finish);
+ return 0;
+}
+
+/* If it's a keepalive packet, then just eat it.
+ * If it's an encapsulated packet, then pass it to the
+ * IPsec xfrm input.
+ * Returns 0 if skb passed to xfrm or was dropped.
+ * Returns >0 if skb should be passed to UDP.
+ * Returns <0 if skb should be resubmitted (-ret is protocol)
+ */
+int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
+{
+ struct udp_sock *up = udp_sk(sk);
+ struct udphdr *uh;
+ struct iphdr *iph;
+ int iphlen, len;
+
+ __u8 *udpdata;
+ __be32 *udpdata32;
+ __u16 encap_type = up->encap_type;
+
+ /* if this is not encapsulated socket, then just return now */
+ if (!encap_type)
+ return 1;
+
+ /* If this is a paged skb, make sure we pull up
+ * whatever data we need to look at. */
+ len = skb->len - sizeof(struct udphdr);
+ if (!pskb_may_pull(skb, sizeof(struct udphdr) + min(len, 8)))
+ return 1;
+
+ /* Now we can get the pointers */
+ uh = udp_hdr(skb);
+ udpdata = (__u8 *)uh + sizeof(struct udphdr);
+ udpdata32 = (__be32 *)udpdata;
+
+ switch (encap_type) {
+ default:
+ case UDP_ENCAP_ESPINUDP:
+ /* Check if this is a keepalive packet. If so, eat it. */
+ if (len == 1 && udpdata[0] == 0xff) {
+ goto drop;
+ } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0) {
+ /* ESP Packet without Non-ESP header */
+ len = sizeof(struct udphdr);
+ } else
+ /* Must be an IKE packet.. pass it through */
+ return 1;
+ break;
+ case UDP_ENCAP_ESPINUDP_NON_IKE:
+ /* Check if this is a keepalive packet. If so, eat it. */
+ if (len == 1 && udpdata[0] == 0xff) {
+ goto drop;
+ } else if (len > 2 * sizeof(u32) + sizeof(struct ip_esp_hdr) &&
+ udpdata32[0] == 0 && udpdata32[1] == 0) {
+
+ /* ESP Packet with Non-IKE marker */
+ len = sizeof(struct udphdr) + 2 * sizeof(u32);
+ } else
+ /* Must be an IKE packet.. pass it through */
+ return 1;
+ break;
+ }
+
+ /* At this point we are sure that this is an ESPinUDP packet,
+ * so we need to remove 'len' bytes from the packet (the UDP
+ * header and optional ESP marker bytes) and then modify the
+ * protocol to ESP, and then call into the transform receiver.
+ */
+ if (skb_unclone(skb, GFP_ATOMIC))
+ goto drop;
+
+ /* Now we can update and verify the packet length... */
+ iph = ip_hdr(skb);
+ iphlen = iph->ihl << 2;
+ iph->tot_len = htons(ntohs(iph->tot_len) - len);
+ if (skb->len < iphlen + len) {
+ /* packet is too small!?! */
+ goto drop;
+ }
+
+ /* pull the data buffer up to the ESP header and set the
+ * transport header to point to ESP. Keep UDP on the stack
+ * for later.
+ */
+ __skb_pull(skb, len);
+ skb_reset_transport_header(skb);
+
+ /* process ESP */
+ return xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, encap_type);
+
+drop:
+ kfree_skb(skb);
+ return 0;
+}
+
+int xfrm4_rcv(struct sk_buff *skb)
+{
+ return xfrm4_rcv_spi(skb, ip_hdr(skb)->protocol, 0);
+}
+EXPORT_SYMBOL(xfrm4_rcv);