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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 | static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb) | |
22 | { | |
23 | struct iphdr *iph = ip_hdr(skb); | |
24 | int ihl = iph->ihl * 4; | |
25 | ||
26 | skb_set_network_header(skb, -x->props.header_len); | |
27 | skb->mac_header = skb->network_header + | |
28 | offsetof(struct iphdr, protocol); | |
29 | skb->transport_header = skb->network_header + ihl; | |
30 | __skb_pull(skb, ihl); | |
31 | memmove(skb_network_header(skb), iph, ihl); | |
32 | return 0; | |
33 | } | |
34 | ||
35 | /* Remove encapsulation header. | |
36 | * | |
37 | * The IP header will be moved over the top of the encapsulation header. | |
38 | * | |
39 | * On entry, skb->h shall point to where the IP header should be and skb->nh | |
40 | * shall be set to where the IP header currently is. skb->data shall point | |
41 | * to the start of the payload. | |
42 | */ | |
43 | static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb) | |
44 | { | |
45 | int ihl = skb->data - skb_transport_header(skb); | |
46 | struct xfrm_offload *xo = xfrm_offload(skb); | |
47 | ||
48 | if (skb->transport_header != skb->network_header) { | |
49 | memmove(skb_transport_header(skb), | |
50 | skb_network_header(skb), ihl); | |
51 | skb->network_header = skb->transport_header; | |
52 | } | |
53 | ip_hdr(skb)->tot_len = htons(skb->len + ihl); | |
54 | if (!xo || !(xo->flags & XFRM_GRO)) | |
55 | skb_reset_transport_header(skb); | |
56 | return 0; | |
57 | } | |
58 | ||
59 | static struct xfrm_mode xfrm4_transport_mode = { | |
60 | .input = xfrm4_transport_input, | |
61 | .output = xfrm4_transport_output, | |
62 | .owner = THIS_MODULE, | |
63 | .encap = XFRM_MODE_TRANSPORT, | |
64 | }; | |
65 | ||
66 | static int __init xfrm4_transport_init(void) | |
67 | { | |
68 | return xfrm_register_mode(&xfrm4_transport_mode, AF_INET); | |
69 | } | |
70 | ||
71 | static void __exit xfrm4_transport_exit(void) | |
72 | { | |
73 | int err; | |
74 | ||
75 | err = xfrm_unregister_mode(&xfrm4_transport_mode, AF_INET); | |
76 | BUG_ON(err); | |
77 | } | |
78 | ||
79 | module_init(xfrm4_transport_init); | |
80 | module_exit(xfrm4_transport_exit); | |
81 | MODULE_LICENSE("GPL"); | |
82 | MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TRANSPORT); |