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   1 /*
   2  * xfrm_input.c
   3  *
   4  * Changes:
   5  *      YOSHIFUJI Hideaki @USAGI
   6  *              Split up af-specific portion
   7  *
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/module.h>
  12 #include <linux/netdevice.h>
  13 #include <net/dst.h>
  14 #include <net/ip.h>
  15 #include <net/xfrm.h>
  16
  17 static struct kmem_cache *secpath_cachep __read_mostly;
  18
  19 void __secpath_destroy(struct sec_path *sp)
  20 {
  21         int i;
  22         for (i = 0; i < sp->len; i++)
  23                 xfrm_state_put(sp->xvec[i]);
  24         kmem_cache_free(secpath_cachep, sp);
  25 }
  26 EXPORT_SYMBOL(__secpath_destroy);
  27
  28 struct sec_path *secpath_dup(struct sec_path *src)
  29 {
  30         struct sec_path *sp;
  31
  32         sp = kmem_cache_alloc(secpath_cachep, GFP_ATOMIC);
  33         if (!sp)
  34                 return NULL;
  35
  36         sp->len = 0;
  37         if (src) {
  38                 int i;
  39
  40                 memcpy(sp, src, sizeof(*sp));
  41                 for (i = 0; i < sp->len; i++)
  42                         xfrm_state_hold(sp->xvec[i]);
  43         }
  44         atomic_set(&sp->refcnt, 1);
  45         return sp;
  46 }
  47 EXPORT_SYMBOL(secpath_dup);
  48
  49 /* Fetch spi and seq from ipsec header */
  50
  51 int xfrm_parse_spi(struct sk_buff *skb, u8 nexthdr, __be32 *spi, __be32 *seq)
  52 {
  53         int offset, offset_seq;
  54         int hlen;
  55
  56         switch (nexthdr) {
  57         case IPPROTO_AH:
  58                 hlen = sizeof(struct ip_auth_hdr);
  59                 offset = offsetof(struct ip_auth_hdr, spi);
  60                 offset_seq = offsetof(struct ip_auth_hdr, seq_no);
  61                 break;
  62         case IPPROTO_ESP:
  63                 hlen = sizeof(struct ip_esp_hdr);
  64                 offset = offsetof(struct ip_esp_hdr, spi);
  65                 offset_seq = offsetof(struct ip_esp_hdr, seq_no);
  66                 break;
  67         case IPPROTO_COMP:
  68                 if (!pskb_may_pull(skb, sizeof(struct ip_comp_hdr)))
  69                         return -EINVAL;
  70                 *spi = htonl(ntohs(*(__be16*)(skb_transport_header(skb) + 2)));
  71                 *seq = 0;
  72                 return 0;
  73         default:
  74                 return 1;
  75         }
  76
  77         if (!pskb_may_pull(skb, hlen))
  78                 return -EINVAL;
  79
  80         *spi = *(__be32*)(skb_transport_header(skb) + offset);
  81         *seq = *(__be32*)(skb_transport_header(skb) + offset_seq);
  82         return 0;
  83 }
  84 EXPORT_SYMBOL(xfrm_parse_spi);
  85
  86 int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
  87 {
  88         int err;
  89
  90         err = x->outer_mode->afinfo->extract_input(x, skb);
  91         if (err)
  92                 return err;
  93
  94         skb->protocol = x->inner_mode->afinfo->eth_proto;
  95         return x->inner_mode->input2(x, skb);
  96 }
  97 EXPORT_SYMBOL(xfrm_prepare_input);
  98
  99 int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 100 {
 101         int err;
 102         __be32 seq;
 103         struct xfrm_state *x;
 104         xfrm_address_t *daddr;
 105         int decaps = 0;
 106         int async = 0;
 107
 108         /* A negative encap_type indicates async resumption. */
 109         if (encap_type < 0) {
 110                 async = 1;
 111                 x = skb->sp->xvec[skb->sp->len - 1];
 112                 seq = XFRM_SKB_CB(skb)->seq;
 113                 goto resume;
 114         }
 115
 116         /* Allocate new secpath or COW existing one. */
 117         if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 118                 struct sec_path *sp;
 119
 120                 sp = secpath_dup(skb->sp);
 121                 if (!sp)
 122                         goto drop;
 123                 if (skb->sp)
 124                         secpath_put(skb->sp);
 125                 skb->sp = sp;
 126         }
 127
 128         daddr = (xfrm_address_t *)(skb_network_header(skb) +
 129                                    XFRM_SPI_SKB_CB(skb)->daddroff);
 130
 131         seq = 0;
 132         if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0)
 133                 goto drop;
 134
 135         do {
 136                 if (skb->sp->len == XFRM_MAX_DEPTH)
 137                         goto drop;
 138
 139                 x = xfrm_state_lookup(daddr, spi, nexthdr, AF_INET);
 140                 if (x == NULL)
 141                         goto drop;
 142
 143                 skb->sp->xvec[skb->sp->len++] = x;
 144
 145                 spin_lock(&x->lock);
 146                 if (unlikely(x->km.state != XFRM_STATE_VALID))
 147                         goto drop_unlock;
 148
 149                 if ((x->encap ? x->encap->encap_type : 0) != encap_type)
 150                         goto drop_unlock;
 151
 152                 if (x->props.replay_window && xfrm_replay_check(x, seq))
 153                         goto drop_unlock;
 154
 155                 if (xfrm_state_check_expire(x))
 156                         goto drop_unlock;
 157
 158                 spin_unlock(&x->lock);
 159
 160                 XFRM_SKB_CB(skb)->seq = seq;
 161
 162                 nexthdr = x->type->input(x, skb);
 163
 164                 if (nexthdr == -EINPROGRESS)
 165                         return 0;
 166
 167 resume:
 168                 spin_lock(&x->lock);
 169                 if (nexthdr <= 0) {
 170                         if (nexthdr == -EBADMSG)
 171                                 x->stats.integrity_failed++;
 172                         goto drop_unlock;
 173                 }
 174
 175                 /* only the first xfrm gets the encap type */
 176                 encap_type = 0;
 177
 178                 if (x->props.replay_window)
 179                         xfrm_replay_advance(x, seq);
 180
 181                 x->curlft.bytes += skb->len;
 182                 x->curlft.packets++;
 183
 184                 spin_unlock(&x->lock);
 185
 186                 XFRM_MODE_SKB_CB(skb)->protocol = nexthdr;
 187
 188                 if (x->inner_mode->input(x, skb))
 189                         goto drop;
 190
 191                 if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
 192                         decaps = 1;
 193                         break;
 194                 }
 195
 196                 /*
 197                  * We need the inner address.  However, we only get here for
 198                  * transport mode so the outer address is identical.
 199                  */
 200                 daddr = &x->id.daddr;
 201
 202                 err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
 203                 if (err < 0)
 204                         goto drop;
 205         } while (!err);
 206
 207         nf_reset(skb);
 208
 209         if (decaps) {
 210                 dst_release(skb->dst);
 211                 skb->dst = NULL;
 212                 netif_rx(skb);
 213                 return 0;
 214         } else {
 215                 return x->inner_mode->afinfo->transport_finish(skb, async);
 216         }
 217
 218 drop_unlock:
 219         spin_unlock(&x->lock);
 220 drop:
 221         kfree_skb(skb);
 222         return 0;
 223 }
 224 EXPORT_SYMBOL(xfrm_input);
 225
 226 int xfrm_input_resume(struct sk_buff *skb, int nexthdr)
 227 {
 228         return xfrm_input(skb, nexthdr, 0, -1);
 229 }
 230 EXPORT_SYMBOL(xfrm_input_resume);
 231
 232 void __init xfrm_input_init(void)
 233 {
 234         secpath_cachep = kmem_cache_create("secpath_cache",
 235                                            sizeof(struct sec_path),
 236                                            0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
 237                                            NULL);
 238 }