+
+/* Remove encapsulation header.
+ *
+ * The IP header will be moved over the top of the encapsulation header.
+ *
+ * On entry, skb_transport_header() shall point to where the IP header
+ * should be and skb_network_header() shall be set to where the IP header
+ * currently is. skb->data shall point to the start of the payload.
+ */
+static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+#if IS_ENABLED(CONFIG_INET_XFRM_MODE_TRANSPORT)
+ int ihl = skb->data - skb_transport_header(skb);
+
+ if (skb->transport_header != skb->network_header) {
+ memmove(skb_transport_header(skb),
+ skb_network_header(skb), ihl);
+ skb->network_header = skb->transport_header;
+ }
+ ip_hdr(skb)->tot_len = htons(skb->len + ihl);
+ skb_reset_transport_header(skb);
+ return 0;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+#if IS_ENABLED(CONFIG_INET6_XFRM_MODE_TRANSPORT)
+ int ihl = skb->data - skb_transport_header(skb);
+
+ if (skb->transport_header != skb->network_header) {
+ memmove(skb_transport_header(skb),
+ skb_network_header(skb), ihl);
+ skb->network_header = skb->transport_header;
+ }
+ ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -
+ sizeof(struct ipv6hdr));
+ skb_reset_transport_header(skb);
+ return 0;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+static int xfrm_inner_mode_input(struct xfrm_state *x,
+ const struct xfrm_mode *inner_mode,
+ struct sk_buff *skb)
+{
+ switch (inner_mode->encap) {
+ case XFRM_MODE_BEET:
+ case XFRM_MODE_TUNNEL:
+ return xfrm_prepare_input(x, skb);
+ case XFRM_MODE_TRANSPORT:
+ if (inner_mode->family == AF_INET)
+ return xfrm4_transport_input(x, skb);
+ if (inner_mode->family == AF_INET6)
+ return xfrm6_transport_input(x, skb);
+ break;
+ case XFRM_MODE_ROUTEOPTIMIZATION:
+ WARN_ON_ONCE(1);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ break;
+ }
+
+ return -EOPNOTSUPP;
+}