2 * xfrm6_mode_transport.c - Transport mode encapsulation for IPv6.
4 * Copyright (C) 2002 USAGI/WIDE Project
5 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
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>
17 /* Add encapsulation header.
19 * The IP header and mutable extension headers will be moved forward to make
20 * space for the encapsulation header.
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 the mac header will be set to the
24 * nextheader field of the extension header directly preceding the
25 * encapsulation header, or in its absence, that of the top IP header.
26 * The value of the network header will always point to the top IP header
27 * while skb->data will point to the payload.
29 static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
37 hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
38 skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
39 skb_set_network_header(skb, -x->props.header_len);
40 skb_set_transport_header(skb, hdr_len - x->props.header_len);
41 __skb_pull(skb, hdr_len);
42 memmove(ipv6_hdr(skb), iph, hdr_len);
46 /* Remove encapsulation header.
48 * The IP header will be moved over the top of the encapsulation header.
50 * On entry, skb->h shall point to where the IP header should be and skb->nh
51 * shall be set to where the IP header currently is. skb->data shall point
52 * to the start of the payload.
54 static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
56 int ihl = skb->data - skb_transport_header(skb);
58 if (skb->transport_header != skb->network_header) {
59 memmove(skb_transport_header(skb),
60 skb_network_header(skb), ihl);
61 skb->network_header = skb->transport_header;
63 ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -
64 sizeof(struct ipv6hdr));
65 skb_reset_transport_header(skb);
69 static struct xfrm_mode xfrm6_transport_mode = {
70 .input = xfrm6_transport_input,
71 .output = xfrm6_transport_output,
73 .encap = XFRM_MODE_TRANSPORT,
76 static int __init xfrm6_transport_init(void)
78 return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6);
81 static void __exit xfrm6_transport_exit(void)
85 err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6);
89 module_init(xfrm6_transport_init);
90 module_exit(xfrm6_transport_exit);
91 MODULE_LICENSE("GPL");
92 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT);