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 xfrm_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->encap->encap_type != encap_type)
  94                         goto drop_unlock;
  95
  96                 if (x->props.replay_window && xfrm_replay_check(x, seq))
  97                         goto drop_unlock;
  98
  99                 if (xfrm_state_check_expire(x))
 100                         goto drop_unlock;
 101
 102                 if (x->type->input(x, skb))
 103                         goto drop_unlock;
 104
 105                 /* only the first xfrm gets the encap type */
 106                 encap_type = 0;
 107
 108                 if (x->props.replay_window)
 109                         xfrm_replay_advance(x, seq);
 110
 111                 x->curlft.bytes += skb->len;
 112                 x->curlft.packets++;
 113
 114                 spin_unlock(&x->lock);
 115
 116                 xfrm_vec[xfrm_nr++] = x;
 117
 118                 iph = skb->nh.iph;
 119
 120                 if (x->props.mode) {
 121                         if (iph->protocol != IPPROTO_IPIP)
 122                                 goto drop;
 123                         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 124                                 goto drop;
 125                         if (skb_cloned(skb) &&
 126                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 127                                 goto drop;
 128                         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
 129                                 ipv4_copy_dscp(iph, skb->h.ipiph);
 130                         if (!(x->props.flags & XFRM_STATE_NOECN))
 131                                 ipip_ecn_decapsulate(skb);
 132                         skb->mac.raw = memmove(skb->data - skb->mac_len,
 133                                                skb->mac.raw, skb->mac_len);
 134                         skb->nh.raw = skb->data;
 135                         memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 136                         decaps = 1;
 137                         break;
 138                 }
 139
 140                 if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
 141                         goto drop;
 142         } while (!err);
 143
 144         /* Allocate new secpath or COW existing one. */
 145
 146         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 147                 struct sec_path *sp;
 148                 sp = secpath_dup(skb->sp);
 149                 if (!sp)
 150                         goto drop;
 151                 if (skb->sp)
 152                         secpath_put(skb->sp);
 153                 skb->sp = sp;
 154         }
 155         if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
 156                 goto drop;
 157
 158         memcpy(skb->sp->xvec + skb->sp->len, xfrm_vec,
 159                xfrm_nr * sizeof(xfrm_vec[0]));
 160         skb->sp->len += xfrm_nr;
 161
 162         nf_reset(skb);
 163
 164         if (decaps) {
 165                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
 166                         dst_release(skb->dst);
 167                         skb->dst = NULL;
 168                 }
 169                 netif_rx(skb);
 170                 return 0;
 171         } else {
 172 #ifdef CONFIG_NETFILTER
 173                 __skb_push(skb, skb->data - skb->nh.raw);
 174                 skb->nh.iph->tot_len = htons(skb->len);
 175                 ip_send_check(skb->nh.iph);
 176
 177                 NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 178                         xfrm4_rcv_encap_finish);
 179                 return 0;
 180 #else
 181                 return -skb->nh.iph->protocol;
 182 #endif
 183         }
 184
 185 drop_unlock:
 186         spin_unlock(&x->lock);
 187         xfrm_state_put(x);
 188 drop:
 189         while (--xfrm_nr >= 0)
 190                 xfrm_state_put(xfrm_vec[xfrm_nr]);
 191
 192         kfree_skb(skb);
 193         return 0;
 194 }