1 files changed, 83 insertions, 0 deletions
diff --git a/net/ipv4/xfrm4_mode_transport.c b/net/ipv4/xfrm4_mode_transport.c
new file mode 100644
index 0000000..a9e6b3d
--- /dev/null
+++ b/net/ipv4/xfrm4_mode_transport.c
@@ -0,0 +1,83 @@
+/*
+ * xfrm4_mode_transport.c - Transport mode encapsulation for IPv4.
+ *
+ * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/stringify.h>
+#include <net/dst.h>
+#include <net/ip.h>
+#include <net/xfrm.h>
+
+/* Add encapsulation header.
+ *
+ * The IP header will be moved forward to make space for the encapsulation
+ * header.
+ *
+ * On exit, skb->h will be set to the start of the payload to be processed
+ * by x->type->output and skb->nh will be set to the top IP header.
+ */
+static int xfrm4_transport_output(struct sk_buff *skb)
+{
+	struct xfrm_state *x;
+	struct iphdr *iph;
+	int ihl;
+
+	iph = skb->nh.iph;
+	skb->h.ipiph = iph;
+
+	ihl = iph->ihl * 4;
+	skb->h.raw += ihl;
+
+	x = skb->dst->xfrm;
+	skb->nh.raw = memmove(skb_push(skb, x->props.header_len), iph, ihl);
+	return 0;
+}
+
+/* Remove encapsulation header.
+ *
+ * The IP header will be moved over the top of the encapsulation header.
+ *
+ * On entry, skb->h shall point to where the IP header should be and skb->nh
+ * 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)
+{
+	int ihl = skb->data - skb->h.raw;
+
+	if (skb->h.raw != skb->nh.raw)
+		skb->nh.raw = memmove(skb->h.raw, skb->nh.raw, ihl);
+	skb->nh.iph->tot_len = htons(skb->len + ihl);
+	skb->h.raw = skb->data;
+	return 0;
+}
+
+static struct xfrm_mode xfrm4_transport_mode = {
+	.input = xfrm4_transport_input,
+	.output = xfrm4_transport_output,
+	.owner = THIS_MODULE,
+	.encap = XFRM_MODE_TRANSPORT,
+};
+
+static int __init xfrm4_transport_init(void)
+{
+	return xfrm_register_mode(&xfrm4_transport_mode, AF_INET);
+}
+
+static void __exit xfrm4_transport_exit(void)
+{
+	int err;
+
+	err = xfrm_unregister_mode(&xfrm4_transport_mode, AF_INET);
+	BUG_ON(err);
+}
+
+module_init(xfrm4_transport_init);
+module_exit(xfrm4_transport_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TRANSPORT);