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 */ 28static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb) 29{ 30 struct ipv6hdr *iph; 31 u8 *prevhdr; 32 int hdr_len; 33 34 skb_push(skb, x->props.header_len); 35 iph = ipv6_hdr(skb); 36 37 hdr_len = x->type->hdr_offset(x, skb, &prevhdr); 38 skb_set_network_header(skb, 39 (prevhdr - x->props.header_len) - skb->data); 40 skb_set_transport_header(skb, hdr_len); 41 memmove(skb->data, iph, hdr_len); 42 return 0; 43} 44 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 */ 53static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb) 54{ 55 int ihl = skb->data - skb_transport_header(skb); 56 57 if (skb->transport_header != skb->network_header) { 58 memmove(skb_transport_header(skb), 59 skb_network_header(skb), ihl); 60 skb->network_header = skb->transport_header; 61 } 62 ipv6_hdr(skb)->payload_len = htons(skb->len + ihl - 63 sizeof(struct ipv6hdr)); 64 skb_reset_transport_header(skb); 65 return 0; 66} 67 68static struct xfrm_mode xfrm6_transport_mode = { 69 .input = xfrm6_transport_input, 70 .output = xfrm6_transport_output, 71 .owner = THIS_MODULE, 72 .encap = XFRM_MODE_TRANSPORT, 73}; 74 75static int __init xfrm6_transport_init(void) 76{ 77 return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6); 78} 79 80static void __exit xfrm6_transport_exit(void) 81{ 82 int err; 83 84 err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6); 85 BUG_ON(err); 86} 87 88module_init(xfrm6_transport_init); 89module_exit(xfrm6_transport_exit); 90MODULE_LICENSE("GPL"); 91MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT); 92