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b59f45d0 HX |
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 | */ | |
28 | static 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 | ||
31a4ab93 HX |
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 | */ | |
b59f45d0 HX |
53 | static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb) |
54 | { | |
31a4ab93 HX |
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; | |
b59f45d0 HX |
62 | return 0; |
63 | } | |
64 | ||
65 | static 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 | ||
72 | static int __init xfrm6_transport_init(void) | |
73 | { | |
74 | return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6); | |
75 | } | |
76 | ||
77 | static 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 | ||
85 | module_init(xfrm6_transport_init); | |
86 | module_exit(xfrm6_transport_exit); | |
87 | MODULE_LICENSE("GPL"); | |
88 | MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT); |