Commit | Line | Data |
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b59f45d0 HX |
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 | */ | |
24 | static 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 | ||
31a4ab93 HX |
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 | */ | |
b59f45d0 HX |
49 | static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb) |
50 | { | |
31a4ab93 HX |
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; | |
b59f45d0 HX |
57 | return 0; |
58 | } | |
59 | ||
60 | static 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 | ||
67 | static int __init xfrm4_transport_init(void) | |
68 | { | |
69 | return xfrm_register_mode(&xfrm4_transport_mode, AF_INET); | |
70 | } | |
71 | ||
72 | static 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 | ||
80 | module_init(xfrm4_transport_init); | |
81 | module_exit(xfrm4_transport_exit); | |
82 | MODULE_LICENSE("GPL"); | |
83 | MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TRANSPORT); |