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 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 if (hdr_len < 0)
32 return hdr_len;
33 skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
34 skb_set_network_header(skb, -x->props.header_len);
35 skb->transport_header = skb->network_header + hdr_len;
36 __skb_pull(skb, hdr_len);
37 memmove(ipv6_hdr(skb), iph, hdr_len);
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 */
49 static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
50 {
51 int ihl = skb->data - skb_transport_header(skb);
52
53 if (skb->transport_header != skb->network_header) {
54 memmove(skb_transport_header(skb),
55 skb_network_header(skb), ihl);
56 skb->network_header = skb->transport_header;
57 }
58 ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -
59 sizeof(struct ipv6hdr));
60 skb_reset_transport_header(skb);
61 return 0;
62 }
63
64 static struct xfrm_mode xfrm6_transport_mode = {
65 .input = xfrm6_transport_input,
66 .output = xfrm6_transport_output,
67 .owner = THIS_MODULE,
68 .encap = XFRM_MODE_TRANSPORT,
69 };
70
71 static int __init xfrm6_transport_init(void)
72 {
73 return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6);
74 }
75
76 static void __exit xfrm6_transport_exit(void)
77 {
78 int err;
79
80 err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6);
81 BUG_ON(err);
82 }
83
84 module_init(xfrm6_transport_init);
85 module_exit(xfrm6_transport_exit);
86 MODULE_LICENSE("GPL");
87 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT);
88
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