net/ipv4/xfrm4_input.c

   1 /*
   2  * xfrm4_input.c
   3  *
   4  * Changes:
   5  *      YOSHIFUJI Hideaki @USAGI
   6  *              Split up af-specific portion
   7  *      Derek Atkins <derek@ihtfp.com>
   8  *              Add Encapsulation support
   9  *
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/string.h>
  14 #include <linux/netfilter.h>
  15 #include <linux/netfilter_ipv4.h>
  16 #include <net/ip.h>
  17 #include <net/xfrm.h>
  18
  19 int xfrm4_rcv(struct sk_buff *skb)
  20 {
  21         return xfrm4_rcv_encap(skb, 0);
  22 }
  23
  24 EXPORT_SYMBOL(xfrm4_rcv);
  25
  26 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
  27 {
  28         switch (nexthdr) {
  29         case IPPROTO_IPIP:
  30                 *spi = skb->nh.iph->saddr;
  31                 *seq = 0;
  32                 return 0;
  33         }
  34
  35         return xfrm_parse_spi(skb, nexthdr, spi, seq);
  36 }
  37
  38 #ifdef CONFIG_NETFILTER
  39 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
  40 {
  41         struct iphdr *iph = skb->nh.iph;
  42
  43         if (skb->dst == NULL) {
  44                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
  45                                    skb->dev))
  46                         goto drop;
  47         }
  48         return dst_input(skb);
  49 drop:
  50         kfree_skb(skb);
  51         return NET_RX_DROP;
  52 }
  53 #endif
  54
  55 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
  56 {
  57         int err;
  58         __be32 spi, seq;
  59         struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
  60         struct xfrm_state *x;
  61         int xfrm_nr = 0;
  62         int decaps = 0;
  63
  64         if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
  65                 goto drop;
  66
  67         do {
  68                 struct iphdr *iph = skb->nh.iph;
  69
  70                 if (xfrm_nr == XFRM_MAX_DEPTH)
  71                         goto drop;
  72
  73                 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET);
  74                 if (x == NULL)
  75                         goto drop;
  76
  77                 spin_lock(&x->lock);
  78                 if (unlikely(x->km.state != XFRM_STATE_VALID))
  79                         goto drop_unlock;
  80
  81                 if ((x->encap ? x->encap->encap_type : 0) != encap_type)
  82                         goto drop_unlock;
  83
  84                 if (x->props.replay_window && xfrm_replay_check(x, seq))
  85                         goto drop_unlock;
  86
  87                 if (xfrm_state_check_expire(x))
  88                         goto drop_unlock;
  89
  90                 if (x->type->input(x, skb))
  91                         goto drop_unlock;
  92
  93                 /* only the first xfrm gets the encap type */
  94                 encap_type = 0;
  95
  96                 if (x->props.replay_window)
  97                         xfrm_replay_advance(x, seq);
  98
  99                 x->curlft.bytes += skb->len;
 100                 x->curlft.packets++;
 101
 102                 spin_unlock(&x->lock);
 103
 104                 xfrm_vec[xfrm_nr++] = x;
 105
 106                 if (x->mode->input(x, skb))
 107                         goto drop;
 108
 109                 if (x->props.mode == XFRM_MODE_TUNNEL) {
 110                         decaps = 1;
 111                         break;
 112                 }
 113
 114                 if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
 115                         goto drop;
 116         } while (!err);
 117
 118         /* Allocate new secpath or COW existing one. */
 119
 120         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 121                 struct sec_path *sp;
 122                 sp = secpath_dup(skb->sp);
 123                 if (!sp)
 124                         goto drop;
 125                 if (skb->sp)
 126                         secpath_put(skb->sp);
 127                 skb->sp = sp;
 128         }
 129         if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
 130                 goto drop;
 131
 132         memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
 133                xfrm_nr * sizeof(xfrm_vec[0]));
 134         skb->sp->len += xfrm_nr;
 135
 136         nf_reset(skb);
 137
 138         if (decaps) {
 139                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
 140                         dst_release(skb->dst);
 141                         skb->dst = NULL;
 142                 }
 143                 netif_rx(skb);
 144                 return 0;
 145         } else {
 146 #ifdef CONFIG_NETFILTER
 147                 __skb_push(skb, skb->data - skb->nh.raw);
 148                 skb->nh.iph->tot_len = htons(skb->len);
 149                 ip_send_check(skb->nh.iph);
 150
 151                 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 152                         xfrm4_rcv_encap_finish);
 153                 return 0;
 154 #else
 155                 return -skb->nh.iph->protocol;
 156 #endif
 157         }
 158
 159 drop_unlock:
 160         spin_unlock(&x->lock);
 161         xfrm_state_put(x);
 162 drop:
 163         while (--xfrm_nr >= 0)
 164                 xfrm_state_put(xfrm_vec[xfrm_nr]);
 165
 166         kfree_skb(skb);
 167         return 0;
 168 }