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 */ 22static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb) 23{ 24 struct ipv6hdr *iph; 25 u8 *prevhdr; 26 int hdr_len; 27 28 iph = ipv6_hdr(skb); 29 30 hdr_len = x->type->hdr_offset(x, skb, &prevhdr); 31 skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data); 32 skb_set_network_header(skb, -x->props.header_len); 33 skb->transport_header = skb->network_header + hdr_len; 34 __skb_pull(skb, hdr_len); 35 memmove(ipv6_hdr(skb), iph, hdr_len); 36 return 0; 37} 38 39/* Remove encapsulation header. 40 * 41 * The IP header will be moved over the top of the encapsulation header. 42 * 43 * On entry, skb->h shall point to where the IP header should be and skb->nh 44 * shall be set to where the IP header currently is. skb->data shall point 45 * to the start of the payload. 46 */ 47static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb) 48{ 49 int ihl = skb->data - skb_transport_header(skb); 50 51 if (skb->transport_header != skb->network_header) { 52 memmove(skb_transport_header(skb), 53 skb_network_header(skb), ihl); 54 skb->network_header = skb->transport_header; 55 } 56 ipv6_hdr(skb)->payload_len = htons(skb->len + ihl - 57 sizeof(struct ipv6hdr)); 58 skb_reset_transport_header(skb); 59 return 0; 60} 61 62static struct xfrm_mode xfrm6_transport_mode = { 63 .input = xfrm6_transport_input, 64 .output = xfrm6_transport_output, 65 .owner = THIS_MODULE, 66 .encap = XFRM_MODE_TRANSPORT, 67}; 68 69static int __init xfrm6_transport_init(void) 70{ 71 return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6); 72} 73 74static void __exit xfrm6_transport_exit(void) 75{ 76 int err; 77 78 err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6); 79 BUG_ON(err); 80} 81 82module_init(xfrm6_transport_init); 83module_exit(xfrm6_transport_exit); 84MODULE_LICENSE("GPL"); 85MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT); 86