kernel/linux/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             INET_ECN_is_not_ce(inner_iph->tos))
  29                 IP_ECN_set_ce(inner_iph);
  30 }
  31
  32 static int xfrm4_parse_spi(struct sk_buff *skb, u8 nexthdr, u32 *spi, u32 *seq)
  33 {
  34         switch (nexthdr) {
  35         case IPPROTO_IPIP:
  36                 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  37                         return -EINVAL;
  38                 *spi = skb->nh.iph->saddr;
  39                 *seq = 0;
  40                 return 0;
  41         }
  42
  43         return xfrm_parse_spi(skb, nexthdr, spi, seq);
  44 }
  45
  46 int xfrm4_rcv_encap(struct sk_buff *skb, __u16 encap_type)
  47 {
  48         int err;
  49         u32 spi, seq;
  50         struct sec_decap_state xfrm_vec[XFRM_MAX_DEPTH];
  51         struct xfrm_state *x;
  52         int xfrm_nr = 0;
  53         int decaps = 0;
  54
  55         if ((err = xfrm4_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) != 0)
  56                 goto drop;
  57
  58         do {
  59                 struct iphdr *iph = skb->nh.iph;
  60
  61                 if (xfrm_nr == XFRM_MAX_DEPTH)
  62                         goto drop;
  63
  64                 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, iph->protocol, AF_INET);
  65                 if (x == NULL)
  66                         goto drop;
  67
  68                 spin_lock(&x->lock);
  69                 if (unlikely(x->km.state != XFRM_STATE_VALID))
  70                         goto drop_unlock;
  71
  72                 if (x->props.replay_window && xfrm_replay_check(x, seq))
  73                         goto drop_unlock;
  74
  75                 if (xfrm_state_check_expire(x))
  76                         goto drop_unlock;
  77
  78                 xfrm_vec[xfrm_nr].decap.decap_type = encap_type;
  79                 if (x->type->input(x, &(xfrm_vec[xfrm_nr].decap), skb))
  80                         goto drop_unlock;
  81
  82                 /* only the first xfrm gets the encap type */
  83                 encap_type = 0;
  84
  85                 if (x->props.replay_window)
  86                         xfrm_replay_advance(x, seq);
  87
  88                 x->curlft.bytes += skb->len;
  89                 x->curlft.packets++;
  90
  91                 spin_unlock(&x->lock);
  92
  93                 xfrm_vec[xfrm_nr++].xvec = x;
  94
  95                 iph = skb->nh.iph;
  96
  97                 if (x->props.mode) {
  98                         if (iph->protocol != IPPROTO_IPIP)
  99                                 goto drop;
 100                         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 101                                 goto drop;
 102                         if (skb_cloned(skb) &&
 103                             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 104                                 goto drop;
 105                         if (!(x->props.flags & XFRM_STATE_NOECN))
 106                                 ipip_ecn_decapsulate(skb);
 107                         skb->mac.raw = memmove(skb->data - skb->mac_len,
 108                                                skb->mac.raw, skb->mac_len);
 109                         skb->nh.raw = skb->data;
 110                         memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
 111                         decaps = 1;
 112                         break;
 113                 }
 114
 115                 if ((err = xfrm_parse_spi(skb, skb->nh.iph->protocol, &spi, &seq)) < 0)
 116                         goto drop;
 117         } while (!err);
 118
 119         /* Allocate new secpath or COW existing one. */
 120
 121         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 122                 struct sec_path *sp;
 123                 sp = secpath_dup(skb->sp);
 124                 if (!sp)
 125                         goto drop;
 126                 if (skb->sp)
 127                         secpath_put(skb->sp);
 128                 skb->sp = sp;
 129         }
 130         if (xfrm_nr + skb->sp->len > XFRM_MAX_DEPTH)
 131                 goto drop;
 132
 133         memcpy(skb->sp->x+skb->sp->len, xfrm_vec, xfrm_nr*sizeof(struct sec_decap_state));
 134         skb->sp->len += xfrm_nr;
 135
 136         if (decaps) {
 137                 if (!(skb->dev->flags&IFF_LOOPBACK)) {
 138                         dst_release(skb->dst);
 139                         skb->dst = NULL;
 140                 }
 141                 netif_rx(skb);
 142                 return 0;
 143         } else {
 144                 return -skb->nh.iph->protocol;
 145         }
 146
 147 drop_unlock:
 148         spin_unlock(&x->lock);
 149         xfrm_state_put(x);
 150 drop:
 151         while (--xfrm_nr >= 0)
 152                 xfrm_state_put(xfrm_vec[xfrm_nr].xvec);
 153
 154         kfree_skb(skb);
 155         return 0;
 156 }