tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * xfrm6_mode_transport.c - Transport mode encapsulation for IPv6.
3 *
4 * Copyright (C) 2002 USAGI/WIDE Project
5 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
6 */
7
8#include <linux/init.h>
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/stringify.h>
13#include <net/dst.h>
14#include <net/ipv6.h>
15#include <net/xfrm.h>
16
17/* Add encapsulation header.
18 *
19 * The IP header and mutable extension headers will be moved forward to make
20 * space for the encapsulation header.
21 *
22 * On exit, skb->h will be set to the start of the encapsulation header to be
23 * filled in by x->type->output and skb->nh will be set to the nextheader field
24 * of the extension header directly preceding the encapsulation header, or in
25 * its absence, that of the top IP header. The value of skb->data will always
26 * point to the top IP header.
27 */
28static int xfrm6_transport_output(struct sk_buff *skb)
29{
30 struct xfrm_state *x = skb->dst->xfrm;
31 struct ipv6hdr *iph;
32 u8 *prevhdr;
33 int hdr_len;
34
35 skb_push(skb, x->props.header_len);
36 iph = skb->nh.ipv6h;
37
38 hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
39 skb->nh.raw = prevhdr - x->props.header_len;
40 skb->h.raw = skb->data + hdr_len;
41 memmove(skb->data, iph, hdr_len);
42 return 0;
43}
44
45/* Remove encapsulation header.
46 *
47 * The IP header will be moved over the top of the encapsulation header.
48 *
49 * On entry, skb->h shall point to where the IP header should be and skb->nh
50 * shall be set to where the IP header currently is. skb->data shall point
51 * to the start of the payload.
52 */
53static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
54{
55 int ihl = skb->data - skb->h.raw;
56
57 if (skb->h.raw != skb->nh.raw)
58 skb->nh.raw = memmove(skb->h.raw, skb->nh.raw, ihl);
59 skb->nh.ipv6h->payload_len = htons(skb->len + ihl -
60 sizeof(struct ipv6hdr));
61 skb->h.raw = skb->data;
62 return 0;
63}
64
65static struct xfrm_mode xfrm6_transport_mode = {
66 .input = xfrm6_transport_input,
67 .output = xfrm6_transport_output,
68 .owner = THIS_MODULE,
69 .encap = XFRM_MODE_TRANSPORT,
70};
71
72static int __init xfrm6_transport_init(void)
73{
74 return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6);
75}
76
77static void __exit xfrm6_transport_exit(void)
78{
79 int err;
80
81 err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6);
82 BUG_ON(err);
83}
84
85module_init(xfrm6_transport_init);
86module_exit(xfrm6_transport_exit);
87MODULE_LICENSE("GPL");
88MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT);