net/ipv6/xfrm6_input.c

   1 /*
   2  * xfrm6_input.c: based on net/ipv4/xfrm4_input.c
   3  *
   4  * Authors:
   5  *      Mitsuru KANDA @USAGI
   6  *      Kazunori MIYAZAWA @USAGI
   7  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   8  *      YOSHIFUJI Hideaki @USAGI
   9  *              IPv6 support
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/string.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/netfilter_ipv6.h>
  16 #include <net/dsfield.h>
  17 #include <net/inet_ecn.h>
  18 #include <net/ip.h>
  19 #include <net/ipv6.h>
  20 #include <net/xfrm.h>
  21
  22 static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
  23 {
  24         struct ipv6hdr *outer_iph = skb->nh.ipv6h;
  25         struct ipv6hdr *inner_iph = skb->h.ipv6h;
  26
  27         if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
  28                 IP6_ECN_set_ce(inner_iph);
  29 }
  30
  31 int xfrm6_rcv_spi(struct sk_buff *skb, u32 spi)
  32 {
  33         int err;
  34         u32 seq;
  35         struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
  36         struct xfrm_state *x;
  37         int xfrm_nr = 0;
  38         int decaps = 0;
  39         int nexthdr;
  40         unsigned int nhoff;
  41
  42         nhoff = IP6CB(skb)->nhoff;
  43         nexthdr = skb->nh.raw[nhoff];
  44
  45         seq = 0;
  46         if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0)
  47                 goto drop;
  48
  49         do {
  50                 struct ipv6hdr *iph = skb->nh.ipv6h;
  51
  52                 if (xfrm_nr == XFRM_MAX_DEPTH)
  53                         goto drop;
  54
  55                 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, nexthdr, AF_INET6);
  56                 if (x == NULL)
  57                         goto drop;
  58                 spin_lock(&x->lock);
  59                 if (unlikely(x->km.state != XFRM_STATE_VALID))
  60                         goto drop_unlock;
  61
  62                 if (x->props.replay_window && xfrm_replay_check(x, seq))
  63                         goto drop_unlock;
  64
  65                 if (xfrm_state_check_expire(x))
  66                         goto drop_unlock;
  67
  68                 nexthdr = x->type->input(x, skb);
  69                 if (nexthdr <= 0)
  70                         goto drop_unlock;
  71
  72                 skb->nh.raw[nhoff] = nexthdr;
  73
  74                 if (x->props.replay_window)
  75                         xfrm_replay_advance(x, seq);
  76
  77                 x->curlft.bytes += skb->len;
  78                 x->curlft.packets++;
  79
  80                 spin_unlock(&x->lock);
  81
  82                 xfrm_vec[xfrm_nr++] = x;
  83
  84                 if (x->props.mode) { /* XXX */
  85                         if (nexthdr != IPPROTO_IPV6)
  86                                 goto drop;
  87                         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  88                                 goto drop;
  89                         if (skb_cloned(skb) &&
  90                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
  91                                 goto drop;
  92                         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
  93                                 ipv6_copy_dscp(skb->nh.ipv6h, skb->h.ipv6h);
  94                         if (!(x->props.flags & XFRM_STATE_NOECN))
  95                                 ipip6_ecn_decapsulate(skb);
  96                         skb->mac.raw = memmove(skb->data - skb->mac_len,
  97                                                skb->mac.raw, skb->mac_len);
  98                         skb->nh.raw = skb->data;
  99                         decaps = 1;
 100                         break;
 101                 }
 102
 103                 if ((err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) < 0)
 104                         goto drop;
 105         } while (!err);
 106
 107         /* Allocate new secpath or COW existing one. */
 108         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 109                 struct sec_path *sp;
 110                 sp = secpath_dup(skb->sp);
 111                 if (!sp)
 112                         goto drop;
 113                 if (skb->sp)
 114                         secpath_put(skb->sp);
 115                 skb->sp = sp;
 116         }
 117
 118         if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
 119                 goto drop;
 120
 121         memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
 122                xfrm_nr * sizeof(xfrm_vec[0]));
 123         skb->sp->len += xfrm_nr;
 124         skb->ip_summed = CHECKSUM_NONE;
 125
 126         nf_reset(skb);
 127
 128         if (decaps) {
 129                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
 130                         dst_release(skb->dst);
 131                         skb->dst = NULL;
 132                 }
 133                 netif_rx(skb);
 134                 return -1;
 135         } else {
 136 #ifdef CONFIG_NETFILTER
 137                 skb->nh.ipv6h->payload_len = htons(skb->len);
 138                 __skb_push(skb, skb->data - skb->nh.raw);
 139
 140                 NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
 141                         ip6_rcv_finish);
 142                 return -1;
 143 #else
 144                 return 1;
 145 #endif
 146         }
 147
 148 drop_unlock:
 149         spin_unlock(&x->lock);
 150         xfrm_state_put(x);
 151 drop:
 152         while (--xfrm_nr >= 0)
 153                 xfrm_state_put(xfrm_vec[xfrm_nr]);
 154         kfree_skb(skb);
 155         return -1;
 156 }
 157
 158 EXPORT_SYMBOL(xfrm6_rcv_spi);
 159
 160 int xfrm6_rcv(struct sk_buff **pskb)
 161 {
 162         return xfrm6_rcv_spi(*pskb, 0);
 163 }