linux/net/xfrm/xfrm_input.c
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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
  17static struct kmem_cache *secpath_cachep __read_mostly;
  18
  19void __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}
  26EXPORT_SYMBOL(__secpath_destroy);
  27
  28struct 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}
  47EXPORT_SYMBOL(secpath_dup);
  48
  49/* Fetch spi and seq from ipsec header */
  50
  51int 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
  85int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
  86{
  87        struct xfrm_mode *inner_mode = x->inner_mode;
  88        int err;
  89
  90        err = x->outer_mode->afinfo->extract_input(x, skb);
  91        if (err)
  92                return err;
  93
  94        if (x->sel.family == AF_UNSPEC) {
  95                inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
  96                if (inner_mode == NULL)
  97                        return -EAFNOSUPPORT;
  98        }
  99
 100        skb->protocol = inner_mode->afinfo->eth_proto;
 101        return inner_mode->input2(x, skb);
 102}
 103EXPORT_SYMBOL(xfrm_prepare_input);
 104
 105int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 106{
 107        struct net *net = dev_net(skb->dev);
 108        int err;
 109        __be32 seq;
 110        __be32 seq_hi;
 111        struct xfrm_state *x;
 112        xfrm_address_t *daddr;
 113        struct xfrm_mode *inner_mode;
 114        unsigned int family;
 115        int decaps = 0;
 116        int async = 0;
 117
 118        /* A negative encap_type indicates async resumption. */
 119        if (encap_type < 0) {
 120                async = 1;
 121                x = xfrm_input_state(skb);
 122                seq = XFRM_SKB_CB(skb)->seq.input.low;
 123                goto resume;
 124        }
 125
 126        /* Allocate new secpath or COW existing one. */
 127        if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
 128                struct sec_path *sp;
 129
 130                sp = secpath_dup(skb->sp);
 131                if (!sp) {
 132                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINERROR);
 133                        goto drop;
 134                }
 135                if (skb->sp)
 136                        secpath_put(skb->sp);
 137                skb->sp = sp;
 138        }
 139
 140        daddr = (xfrm_address_t *)(skb_network_header(skb) +
 141                                   XFRM_SPI_SKB_CB(skb)->daddroff);
 142        family = XFRM_SPI_SKB_CB(skb)->family;
 143
 144        seq = 0;
 145        if (!spi && (err = xfrm_parse_spi(skb, nexthdr, &spi, &seq)) != 0) {
 146                XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
 147                goto drop;
 148        }
 149
 150        do {
 151                if (skb->sp->len == XFRM_MAX_DEPTH) {
 152                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR);
 153                        goto drop;
 154                }
 155
 156                x = xfrm_state_lookup(net, skb->mark, daddr, spi, nexthdr, family);
 157                if (x == NULL) {
 158                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);
 159                        xfrm_audit_state_notfound(skb, family, spi, seq);
 160                        goto drop;
 161                }
 162
 163                skb->sp->xvec[skb->sp->len++] = x;
 164
 165                spin_lock(&x->lock);
 166                if (unlikely(x->km.state != XFRM_STATE_VALID)) {
 167                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEINVALID);
 168                        goto drop_unlock;
 169                }
 170
 171                if ((x->encap ? x->encap->encap_type : 0) != encap_type) {
 172                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMISMATCH);
 173                        goto drop_unlock;
 174                }
 175
 176                if (x->repl->check(x, skb, seq)) {
 177                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
 178                        goto drop_unlock;
 179                }
 180
 181                if (xfrm_state_check_expire(x)) {
 182                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEEXPIRED);
 183                        goto drop_unlock;
 184                }
 185
 186                spin_unlock(&x->lock);
 187
 188                seq_hi = htonl(xfrm_replay_seqhi(x, seq));
 189
 190                XFRM_SKB_CB(skb)->seq.input.low = seq;
 191                XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
 192
 193                skb_dst_force(skb);
 194
 195                nexthdr = x->type->input(x, skb);
 196
 197                if (nexthdr == -EINPROGRESS)
 198                        return 0;
 199
 200resume:
 201                spin_lock(&x->lock);
 202                if (nexthdr <= 0) {
 203                        if (nexthdr == -EBADMSG) {
 204                                xfrm_audit_state_icvfail(x, skb,
 205                                                         x->type->proto);
 206                                x->stats.integrity_failed++;
 207                        }
 208                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEPROTOERROR);
 209                        goto drop_unlock;
 210                }
 211
 212                /* only the first xfrm gets the encap type */
 213                encap_type = 0;
 214
 215                if (async && x->repl->recheck(x, skb, seq)) {
 216                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
 217                        goto drop_unlock;
 218                }
 219
 220                x->repl->advance(x, seq);
 221
 222                x->curlft.bytes += skb->len;
 223                x->curlft.packets++;
 224
 225                spin_unlock(&x->lock);
 226
 227                XFRM_MODE_SKB_CB(skb)->protocol = nexthdr;
 228
 229                inner_mode = x->inner_mode;
 230
 231                if (x->sel.family == AF_UNSPEC) {
 232                        inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
 233                        if (inner_mode == NULL)
 234                                goto drop;
 235                }
 236
 237                if (inner_mode->input(x, skb)) {
 238                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEMODEERROR);
 239                        goto drop;
 240                }
 241
 242                if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
 243                        decaps = 1;
 244                        break;
 245                }
 246
 247                /*
 248                 * We need the inner address.  However, we only get here for
 249                 * transport mode so the outer address is identical.
 250                 */
 251                daddr = &x->id.daddr;
 252                family = x->outer_mode->afinfo->family;
 253
 254                err = xfrm_parse_spi(skb, nexthdr, &spi, &seq);
 255                if (err < 0) {
 256                        XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);
 257                        goto drop;
 258                }
 259        } while (!err);
 260
 261        nf_reset(skb);
 262
 263        if (decaps) {
 264                skb_dst_drop(skb);
 265                netif_rx(skb);
 266                return 0;
 267        } else {
 268                return x->inner_mode->afinfo->transport_finish(skb, async);
 269        }
 270
 271drop_unlock:
 272        spin_unlock(&x->lock);
 273drop:
 274        kfree_skb(skb);
 275        return 0;
 276}
 277EXPORT_SYMBOL(xfrm_input);
 278
 279int xfrm_input_resume(struct sk_buff *skb, int nexthdr)
 280{
 281        return xfrm_input(skb, nexthdr, 0, -1);
 282}
 283EXPORT_SYMBOL(xfrm_input_resume);
 284
 285void __init xfrm_input_init(void)
 286{
 287        secpath_cachep = kmem_cache_create("secpath_cache",
 288                                           sizeof(struct sec_path),
 289                                           0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
 290                                           NULL);
 291}
 292
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