tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * xfrm4_mode_transport.c - Transport mode encapsulation for IPv4.
3 *
4 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
5 */
6
7#include <linux/init.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/stringify.h>
12#include <net/dst.h>
13#include <net/ip.h>
14#include <net/xfrm.h>
15
16/* Add encapsulation header.
17 *
18 * The IP header will be moved forward to make space for the encapsulation
19 * header.
20 *
21 * On exit, skb->h will be set to the start of the payload to be processed
22 * by x->type->output and skb->nh will be set to the top IP header.
23 */
24static int xfrm4_transport_output(struct sk_buff *skb)
25{
26 struct xfrm_state *x;
27 struct iphdr *iph;
28 int ihl;
29
30 iph = skb->nh.iph;
31 skb->h.ipiph = iph;
32
33 ihl = iph->ihl * 4;
34 skb->h.raw += ihl;
35
36 x = skb->dst->xfrm;
37 skb->nh.raw = memmove(skb_push(skb, x->props.header_len), iph, ihl);
38 return 0;
39}
40
41/* Remove encapsulation header.
42 *
43 * The IP header will be moved over the top of the encapsulation header.
44 *
45 * On entry, skb->h shall point to where the IP header should be and skb->nh
46 * shall be set to where the IP header currently is. skb->data shall point
47 * to the start of the payload.
48 */
49static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb)
50{
51 int ihl = skb->data - skb->h.raw;
52
53 if (skb->h.raw != skb->nh.raw)
54 skb->nh.raw = memmove(skb->h.raw, skb->nh.raw, ihl);
55 skb->nh.iph->tot_len = htons(skb->len + ihl);
56 skb->h.raw = skb->data;
57 return 0;
58}
59
60static struct xfrm_mode xfrm4_transport_mode = {
61 .input = xfrm4_transport_input,
62 .output = xfrm4_transport_output,
63 .owner = THIS_MODULE,
64 .encap = XFRM_MODE_TRANSPORT,
65};
66
67static int __init xfrm4_transport_init(void)
68{
69 return xfrm_register_mode(&xfrm4_transport_mode, AF_INET);
70}
71
72static void __exit xfrm4_transport_exit(void)
73{
74 int err;
75
76 err = xfrm_unregister_mode(&xfrm4_transport_mode, AF_INET);
77 BUG_ON(err);
78}
79
80module_init(xfrm4_transport_init);
81module_exit(xfrm4_transport_exit);
82MODULE_LICENSE("GPL");
83MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TRANSPORT);