| 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 | static 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 | */ |
| 47 | static 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 | |
| 62 | static 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 | |
| 69 | static int __init xfrm6_transport_init(void) |
| 70 | { |
| 71 | return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6); |
| 72 | } |
| 73 | |
| 74 | static 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 | |
| 82 | module_init(xfrm6_transport_init); |
| 83 | module_exit(xfrm6_transport_exit); |
| 84 | MODULE_LICENSE("GPL"); |
| 85 | MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT); |