LXR linux/net/ipv4/xfrm4_mode

   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#include <net/protocol.h>
  16
  17/* Add encapsulation header.
  18 *
  19 * The IP header will be moved forward to make space for the encapsulation
  20 * header.
  21 */
  22static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
  23{
  24        struct iphdr *iph = ip_hdr(skb);
  25        int ihl = iph->ihl * 4;
  26
  27        skb_set_inner_transport_header(skb, skb_transport_offset(skb));
  28
  29        skb_set_network_header(skb, -x->props.header_len);
  30        skb->mac_header = skb->network_header +
  31                          offsetof(struct iphdr, protocol);
  32        skb->transport_header = skb->network_header + ihl;
  33        __skb_pull(skb, ihl);
  34        memmove(skb_network_header(skb), iph, ihl);
  35        return 0;
  36}
  37
  38/* Remove encapsulation header.
  39 *
  40 * The IP header will be moved over the top of the encapsulation header.
  41 *
  42 * On entry, skb->h shall point to where the IP header should be and skb->nh
  43 * shall be set to where the IP header currently is.  skb->data shall point
  44 * to the start of the payload.
  45 */
  46static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb)
  47{
  48        int ihl = skb->data - skb_transport_header(skb);
  49        struct xfrm_offload *xo = xfrm_offload(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        ip_hdr(skb)->tot_len = htons(skb->len + ihl);
  57        if (!xo || !(xo->flags & XFRM_GRO))
  58                skb_reset_transport_header(skb);
  59        return 0;
  60}
  61
  62static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
  63                                                   struct sk_buff *skb,
  64                                                   netdev_features_t features)
  65{
  66        const struct net_offload *ops;
  67        struct sk_buff *segs = ERR_PTR(-EINVAL);
  68        struct xfrm_offload *xo = xfrm_offload(skb);
  69
  70        skb->transport_header += x->props.header_len;
  71        ops = rcu_dereference(inet_offloads[xo->proto]);
  72        if (likely(ops && ops->callbacks.gso_segment))
  73                segs = ops->callbacks.gso_segment(skb, features);
  74
  75        return segs;
  76}
  77
  78static void xfrm4_transport_xmit(struct xfrm_state *x, struct sk_buff *skb)
  79{
  80        struct xfrm_offload *xo = xfrm_offload(skb);
  81
  82        skb_reset_mac_len(skb);
  83        pskb_pull(skb, skb->mac_len + sizeof(struct iphdr) + x->props.header_len);
  84
  85        if (xo->flags & XFRM_GSO_SEGMENT) {
  86                 skb_reset_transport_header(skb);
  87                 skb->transport_header -= x->props.header_len;
  88        }
  89}
  90
  91static struct xfrm_mode xfrm4_transport_mode = {
  92        .input = xfrm4_transport_input,
  93        .output = xfrm4_transport_output,
  94        .gso_segment = xfrm4_transport_gso_segment,
  95        .xmit = xfrm4_transport_xmit,
  96        .owner = THIS_MODULE,
  97        .encap = XFRM_MODE_TRANSPORT,
  98};
  99
 100static int __init xfrm4_transport_init(void)
 101{
 102        return xfrm_register_mode(&xfrm4_transport_mode, AF_INET);
 103}
 104
 105static void __exit xfrm4_transport_exit(void)
 106{
 107        int err;
 108
 109        err = xfrm_unregister_mode(&xfrm4_transport_mode, AF_INET);
 110        BUG_ON(err);
 111}
 112
 113module_init(xfrm4_transport_init);
 114module_exit(xfrm4_transport_exit);
 115MODULE_LICENSE("GPL");
 116MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TRANSPORT);
 117