net/ipv6/xfrm6_mode_transport.c

   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 #include <net/protocol.h>
  17
  18 /* Add encapsulation header.
  19  *
  20  * The IP header and mutable extension headers will be moved forward to make
  21  * space for the encapsulation header.
  22  */
  23 static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
  24 {
  25         struct ipv6hdr *iph;
  26         u8 *prevhdr;
  27         int hdr_len;
  28
  29         iph = ipv6_hdr(skb);
  30         skb_set_inner_transport_header(skb, skb_transport_offset(skb));
  31
  32         hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
  33         if (hdr_len < 0)
  34                 return hdr_len;
  35         skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
  36         skb_set_network_header(skb, -x->props.header_len);
  37         skb->transport_header = skb->network_header + hdr_len;
  38         __skb_pull(skb, hdr_len);
  39         memmove(ipv6_hdr(skb), iph, hdr_len);
  40         return 0;
  41 }
  42
  43 /* Remove encapsulation header.
  44  *
  45  * The IP header will be moved over the top of the encapsulation header.
  46  *
  47  * On entry, skb->h shall point to where the IP header should be and skb->nh
  48  * shall be set to where the IP header currently is.  skb->data shall point
  49  * to the start of the payload.
  50  */
  51 static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
  52 {
  53         int ihl = skb->data - skb_transport_header(skb);
  54
  55         if (skb->transport_header != skb->network_header) {
  56                 memmove(skb_transport_header(skb),
  57                         skb_network_header(skb), ihl);
  58                 skb->network_header = skb->transport_header;
  59         }
  60         ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -
  61                                            sizeof(struct ipv6hdr));
  62         skb_reset_transport_header(skb);
  63         return 0;
  64 }
  65
  66 static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
  67                                                    struct sk_buff *skb,
  68                                                    netdev_features_t features)
  69 {
  70         const struct net_offload *ops;
  71         struct sk_buff *segs = ERR_PTR(-EINVAL);
  72         struct xfrm_offload *xo = xfrm_offload(skb);
  73
  74         skb->transport_header += x->props.header_len;
  75         ops = rcu_dereference(inet6_offloads[xo->proto]);
  76         if (likely(ops && ops->callbacks.gso_segment))
  77                 segs = ops->callbacks.gso_segment(skb, features);
  78
  79         return segs;
  80 }
  81
  82 static void xfrm6_transport_xmit(struct xfrm_state *x, struct sk_buff *skb)
  83 {
  84         struct xfrm_offload *xo = xfrm_offload(skb);
  85
  86         skb_reset_mac_len(skb);
  87         pskb_pull(skb, skb->mac_len + sizeof(struct ipv6hdr) + x->props.header_len);
  88
  89         if (xo->flags & XFRM_GSO_SEGMENT) {
  90                  skb_reset_transport_header(skb);
  91                  skb->transport_header -= x->props.header_len;
  92         }
  93 }
  94
  95
  96 static struct xfrm_mode xfrm6_transport_mode = {
  97         .input = xfrm6_transport_input,
  98         .output = xfrm6_transport_output,
  99         .gso_segment = xfrm4_transport_gso_segment,
 100         .xmit = xfrm6_transport_xmit,
 101         .owner = THIS_MODULE,
 102         .encap = XFRM_MODE_TRANSPORT,
 103 };
 104
 105 static int __init xfrm6_transport_init(void)
 106 {
 107         return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6);
 108 }
 109
 110 static void __exit xfrm6_transport_exit(void)
 111 {
 112         int err;
 113
 114         err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6);
 115         BUG_ON(err);
 116 }
 117
 118 module_init(xfrm6_transport_init);
 119 module_exit(xfrm6_transport_exit);
 120 MODULE_LICENSE("GPL");
 121 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT);