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                 *spi = skb->nh.iph->saddr;
  41                 *seq = 0;
  42                 return 0;
  43         }
  44
  45         return xfrm_parse_spi(skb, nexthdr, spi, seq);
  46 }
  47
  48 #ifdef CONFIG_NETFILTER
  49 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
  50 {
  51         struct iphdr *iph = skb->nh.iph;
  52
  53         if (skb->dst == NULL) {
  54                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
  55                                    skb->dev))
  56                         goto drop;
  57         }
  58         return dst_input(skb);
  59 drop:
  60         kfree_skb(skb);
  61         return NET_RX_DROP;
  62 }
  63 #endif
  64
  65 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
  66 {
  67         int err;
  68         u32 spi, seq;
  69         struct xfrm_state *xfrm_vec[XFRM_MAX_DEPTH];
  70         struct xfrm_state *x;
  71         int xfrm_nr = 0;
  72         int decaps = 0;
  73
  74         if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
  75                 goto drop;
  76
  77         do {
  78                 struct iphdr *iph = skb->nh.iph;
  79
  80                 if (xfrm_nr == XFRM_MAX_DEPTH)
  81                         goto drop;
  82
  83                 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET);
  84                 if (x == NULL)
  85                         goto drop;
  86
  87                 spin_lock(&x->lock);
  88                 if (unlikely(x->km.state != XFRM_STATE_VALID))
  89                         goto drop_unlock;
  90
  91                 if ((x->encap ? x->encap->encap_type : 0) != encap_type)
  92                         goto drop_unlock;
  93
  94                 if (x->props.replay_window && xfrm_replay_check(x, seq))
  95                         goto drop_unlock;
  96
  97                 if (xfrm_state_check_expire(x))
  98                         goto drop_unlock;
  99
 100                 if (x->type->input(x, 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++] = 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->xvec + skb->sp->len, xfrm_vec,
 157                xfrm_nr * sizeof(xfrm_vec[0]));
 158         skb->sp->len += xfrm_nr;
 159
 160         nf_reset(skb);
 161
 162         if (decaps) {
 163                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
 164                         dst_release(skb->dst);
 165                         skb->dst = NULL;
 166                 }
 167                 netif_rx(skb);
 168                 return 0;
 169         } else {
 170 #ifdef CONFIG_NETFILTER
 171                 __skb_push(skb, skb->data - skb->nh.raw);
 172                 skb->nh.iph->tot_len = htons(skb->len);
 173                 ip_send_check(skb->nh.iph);
 174
 175                 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 176                         xfrm4_rcv_encap_finish);
 177                 return 0;
 178 #else
 179                 return -skb->nh.iph->protocol;
 180 #endif
 181         }
 182
 183 drop_unlock:
 184         spin_unlock(&x->lock);
 185         xfrm_state_put(x);
 186 drop:
 187         while (--xfrm_nr >= 0)
 188                 xfrm_state_put(xfrm_vec[xfrm_nr]);
 189
 190         kfree_skb(skb);
 191         return 0;
 192 }