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/string.h>
  13 #include <net/inet_ecn.h>
  14 #include <net/ip.h>
  15 #include <net/xfrm.h>
  16
  17 int xfrm4_rcv(struct sk_buff *skb)
  18 {
  19         return xfrm4_rcv_encap(skb, 0);
  20 }
  21
  22 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
  23 {
  24         struct iphdr *outer_iph = skb->nh.iph;
  25         struct iphdr *inner_iph = skb->h.ipiph;
  26
  27         if (INET_ECN_is_ce(outer_iph->tos))
  28                 IP_ECN_set_ce(inner_iph);
  29 }
  30
  31 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, u32 *spi, u32 *seq)
  32 {
  33         switch (nexthdr) {
  34         case IPPROTO_IPIP:
  35                 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  36                         return -EINVAL;
  37                 *spi = skb->nh.iph->saddr;
  38                 *seq = 0;
  39                 return 0;
  40         }
  41
  42         return xfrm_parse_spi(skb, nexthdr, spi, seq);
  43 }
  44
  45 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
  46 {
  47         int err;
  48         u32 spi, seq;
  49         struct sec_decap_state xfrm_vec[XFRM_MAX_DEPTH];
  50         struct xfrm_state *x;
  51         int xfrm_nr = 0;
  52         int decaps = 0;
  53
  54         if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
  55                 goto drop;
  56
  57         do {
  58                 struct iphdr *iph = skb->nh.iph;
  59
  60                 if (xfrm_nr == XFRM_MAX_DEPTH)
  61                         goto drop;
  62
  63                 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET);
  64                 if (x == NULL)
  65                         goto drop;
  66
  67                 spin_lock(&x->lock);
  68                 if (unlikely(x->km.state != XFRM_STATE_VALID))
  69                         goto drop_unlock;
  70
  71                 if (x->props.replay_window && xfrm_replay_check(x, seq))
  72                         goto drop_unlock;
  73
  74                 if (xfrm_state_check_expire(x))
  75                         goto drop_unlock;
  76
  77                 xfrm_vec[xfrm_nr].decap.decap_type = encap_type;
  78                 if (x->type->input(x, &(xfrm_vec[xfrm_nr].decap), skb))
  79                         goto drop_unlock;
  80
  81                 /* only the first xfrm gets the encap type */
  82                 encap_type = 0;
  83
  84                 if (x->props.replay_window)
  85                         xfrm_replay_advance(x, seq);
  86
  87                 x->curlft.bytes += skb->len;
  88                 x->curlft.packets++;
  89
  90                 spin_unlock(&x->lock);
  91
  92                 xfrm_vec[xfrm_nr++].xvec = x;
  93
  94                 iph = skb->nh.iph;
  95
  96                 if (x->props.mode) {
  97                         if (iph->protocol != IPPROTO_IPIP)
  98                                 goto drop;
  99                         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 100                                 goto drop;
 101                         if (skb_cloned(skb) &&
 102                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 103                                 goto drop;
 104                         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
 105                                 ipv4_copy_dscp(iph, skb->h.ipiph);
 106                         if (!(x->props.flags & XFRM_STATE_NOECN))
 107                                 ipip_ecn_decapsulate(skb);
 108                         skb->mac.raw = memmove(skb->data - skb->mac_len,
 109                                                skb->mac.raw, skb->mac_len);
 110                         skb->nh.raw = skb->data;
 111                         memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 112                         decaps = 1;
 113                         break;
 114                 }
 115
 116                 if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
 117                         goto drop;
 118         } while (!err);
 119
 120         /* Allocate new secpath or COW existing one. */
 121
 122         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 123                 struct sec_path *sp;
 124                 sp = secpath_dup(skb->sp);
 125                 if (!sp)
 126                         goto drop;
 127                 if (skb->sp)
 128                         secpath_put(skb->sp);
 129                 skb->sp = sp;
 130         }
 131         if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
 132                 goto drop;
 133
 134         memcpy(skb->sp->x+skb->sp->len, xfrm_vec, xfrm_nr*sizeof(struct sec_decap_state));
 135         skb->sp->len += xfrm_nr;
 136
 137         if (decaps) {
 138                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
 139                         dst_release(skb->dst);
 140                         skb->dst = NULL;
 141                 }
 142                 netif_rx(skb);
 143                 return 0;
 144         } else {
 145                 return -skb->nh.iph->protocol;
 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].xvec);
 154
 155         kfree_skb(skb);
 156         return 0;
 157 }