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/inet_ecn.h>
  17 #include <net/ip.h>
  18 #include <net/xfrm.h>
  19
  20 int xfrm4_rcv(struct sk_buff *skb)
  21 {
  22         return xfrm4_rcv_encap(skb, 0);
  23 }
  24
  25 EXPORT_SYMBOL(xfrm4_rcv);
  26
  27 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
  28 {
  29         struct iphdr *outer_iph = skb->nh.iph;
  30         struct iphdr *inner_iph = skb->h.ipiph;
  31
  32         if (INET_ECN_is_ce(outer_iph->tos))
  33                 IP_ECN_set_ce(inner_iph);
  34 }
  35
  36 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, u32 *spi, u32 *seq)
  37 {
  38         switch (nexthdr) {
  39         case IPPROTO_IPIP:
  40                 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  41                         return -EINVAL;
  42                 *spi = skb->nh.iph->saddr;
  43                 *seq = 0;
  44                 return 0;
  45         }
  46
  47         return xfrm_parse_spi(skb, nexthdr, spi, seq);
  48 }
  49
  50 #ifdef CONFIG_NETFILTER
  51 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
  52 {
  53         struct iphdr *iph = skb->nh.iph;
  54
  55         if (skb->dst == NULL) {
  56                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
  57                                    skb->dev))
  58                         goto drop;
  59         }
  60         return dst_input(skb);
  61 drop:
  62         kfree_skb(skb);
  63         return NET_RX_DROP;
  64 }
  65 #endif
  66
  67 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
  68 {
  69         int err;
  70         u32 spi, seq;
  71         struct sec_decap_state xfrm_vec[XFRM_MAX_DEPTH];
  72         struct xfrm_state *x;
  73         int xfrm_nr = 0;
  74         int decaps = 0;
  75
  76         if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
  77                 goto drop;
  78
  79         do {
  80                 struct iphdr *iph = skb->nh.iph;
  81
  82                 if (xfrm_nr == XFRM_MAX_DEPTH)
  83                         goto drop;
  84
  85                 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET);
  86                 if (x == NULL)
  87                         goto drop;
  88
  89                 spin_lock(&x->lock);
  90                 if (unlikely(x->km.state != XFRM_STATE_VALID))
  91                         goto drop_unlock;
  92
  93                 if (x->props.replay_window && xfrm_replay_check(x, seq))
  94                         goto drop_unlock;
  95
  96                 if (xfrm_state_check_expire(x))
  97                         goto drop_unlock;
  98
  99                 xfrm_vec[xfrm_nr].decap.decap_type = encap_type;
 100                 if (x->type->input(x, &(xfrm_vec[xfrm_nr].decap), skb))
 101                         goto drop_unlock;
 102
 103                 /* only the first xfrm gets the encap type */
 104                 encap_type = 0;
 105
 106                 if (x->props.replay_window)
 107                         xfrm_replay_advance(x, seq);
 108
 109                 x->curlft.bytes += skb->len;
 110                 x->curlft.packets++;
 111
 112                 spin_unlock(&x->lock);
 113
 114                 xfrm_vec[xfrm_nr++].xvec = x;
 115
 116                 iph = skb->nh.iph;
 117
 118                 if (x->props.mode) {
 119                         if (iph->protocol != IPPROTO_IPIP)
 120                                 goto drop;
 121                         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 122                                 goto drop;
 123                         if (skb_cloned(skb) &&
 124                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 125                                 goto drop;
 126                         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
 127                                 ipv4_copy_dscp(iph, skb->h.ipiph);
 128                         if (!(x->props.flags & XFRM_STATE_NOECN))
 129                                 ipip_ecn_decapsulate(skb);
 130                         skb->mac.raw = memmove(skb->data - skb->mac_len,
 131                                                skb->mac.raw, skb->mac_len);
 132                         skb->nh.raw = skb->data;
 133                         memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 134                         decaps = 1;
 135                         break;
 136                 }
 137
 138                 if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
 139                         goto drop;
 140         } while (!err);
 141
 142         /* Allocate new secpath or COW existing one. */
 143
 144         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 145                 struct sec_path *sp;
 146                 sp = secpath_dup(skb->sp);
 147                 if (!sp)
 148                         goto drop;
 149                 if (skb->sp)
 150                         secpath_put(skb->sp);
 151                 skb->sp = sp;
 152         }
 153         if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
 154                 goto drop;
 155
 156         memcpy(skb->sp->x+skb->sp->len, xfrm_vec, xfrm_nr*sizeof(struct sec_decap_state));
 157         skb->sp->len += xfrm_nr;
 158
 159         nf_reset(skb);
 160
 161         if (decaps) {
 162                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
 163                         dst_release(skb->dst);
 164                         skb->dst = NULL;
 165                 }
 166                 netif_rx(skb);
 167                 return 0;
 168         } else {
 169 #ifdef CONFIG_NETFILTER
 170                 __skb_push(skb, skb->data - skb->nh.raw);
 171                 skb->nh.iph->tot_len = htons(skb->len);
 172                 ip_send_check(skb->nh.iph);
 173
 174                 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 175                         xfrm4_rcv_encap_finish);
 176                 return 0;
 177 #else
 178                 return -skb->nh.iph->protocol;
 179 #endif
 180         }
 181
 182 drop_unlock:
 183         spin_unlock(&x->lock);
 184         xfrm_state_put(x);
 185 drop:
 186         while (--xfrm_nr >= 0)
 187                 xfrm_state_put(xfrm_vec[xfrm_nr].xvec);
 188
 189         kfree_skb(skb);
 190         return 0;
 191 }