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 */
xfrm6_transport_output(struct xfrm_state * x,struct sk_buff * skb)22 static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
23 {
24 struct ipv6hdr *iph;
25 u8 *prevhdr;
26 int hdr_len;
27
28 iph = ipv6_hdr(skb);
29
30 hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
31 skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
32 skb_set_network_header(skb, -x->props.header_len);
33 skb->transport_header = skb->network_header + hdr_len;
34 __skb_pull(skb, hdr_len);
35 memmove(ipv6_hdr(skb), iph, hdr_len);
36 return 0;
37 }
38
39 /* Remove encapsulation header.
40 *
41 * The IP header will be moved over the top of the encapsulation header.
42 *
43 * On entry, skb->h shall point to where the IP header should be and skb->nh
44 * shall be set to where the IP header currently is. skb->data shall point
45 * to the start of the payload.
46 */
xfrm6_transport_input(struct xfrm_state * x,struct sk_buff * skb)47 static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
48 {
49 int ihl = skb->data - skb_transport_header(skb);
50
51 if (skb->transport_header != skb->network_header) {
52 memmove(skb_transport_header(skb),
53 skb_network_header(skb), ihl);
54 skb->network_header = skb->transport_header;
55 }
56 ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -
57 sizeof(struct ipv6hdr));
58 skb_reset_transport_header(skb);
59 return 0;
60 }
61
62 static struct xfrm_mode xfrm6_transport_mode = {
63 .input = xfrm6_transport_input,
64 .output = xfrm6_transport_output,
65 .owner = THIS_MODULE,
66 .encap = XFRM_MODE_TRANSPORT,
67 };
68
xfrm6_transport_init(void)69 static int __init xfrm6_transport_init(void)
70 {
71 return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6);
72 }
73
xfrm6_transport_exit(void)74 static void __exit xfrm6_transport_exit(void)
75 {
76 int err;
77
78 err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6);
79 BUG_ON(err);
80 }
81
82 module_init(xfrm6_transport_init);
83 module_exit(xfrm6_transport_exit);
84 MODULE_LICENSE("GPL");
85 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT);
86