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   1 /*
   2  * xfrm6_policy.c: based on xfrm4_policy.c
   3  *
   4  * Authors:
   5  *      Mitsuru KANDA @USAGI
   6  *      Kazunori MIYAZAWA @USAGI
   7  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   8  *              IPv6 support
   9  *      YOSHIFUJI Hideaki
  10  *              Split up af-specific portion
  11  *
  12  */
  13
  14 #include <linux/compiler.h>
  15 #include <linux/netdevice.h>
  16 #include <net/addrconf.h>
  17 #include <net/xfrm.h>
  18 #include <net/ip.h>
  19 #include <net/ipv6.h>
  20 #include <net/ip6_route.h>
  21 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
  22 #include <net/mip6.h>
  23 #endif
  24
  25 static struct dst_ops xfrm6_dst_ops;
  26 static struct xfrm_policy_afinfo xfrm6_policy_afinfo;
  27
  28 static int xfrm6_dst_lookup(struct xfrm_dst **xdst, struct flowi *fl)
  29 {
  30         struct dst_entry *dst = ip6_route_output(NULL, fl);
  31         int err = dst->error;
  32         if (!err)
  33                 *xdst = (struct xfrm_dst *) dst;
  34         else
  35                 dst_release(dst);
  36         return err;
  37 }
  38
  39 static int xfrm6_get_saddr(xfrm_address_t *saddr, xfrm_address_t *daddr)
  40 {
  41         struct rt6_info *rt;
  42         struct flowi fl_tunnel = {
  43                 .nl_u = {
  44                         .ip6_u = {
  45                                 .daddr = *(struct in6_addr *)&daddr->a6,
  46                         },
  47                 },
  48         };
  49
  50         if (!xfrm6_dst_lookup((struct xfrm_dst **)&rt, &fl_tunnel)) {
  51                 ipv6_get_saddr(&rt->u.dst, (struct in6_addr *)&daddr->a6,
  52                                (struct in6_addr *)&saddr->a6);
  53                 dst_release(&rt->u.dst);
  54                 return 0;
  55         }
  56         return -EHOSTUNREACH;
  57 }
  58
  59 static struct dst_entry *
  60 __xfrm6_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  61 {
  62         struct dst_entry *dst;
  63
  64         /* Still not clear if we should set fl->fl6_{src,dst}... */
  65         read_lock_bh(&policy->lock);
  66         for (dst = policy->bundles; dst; dst = dst->next) {
  67                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  68                 struct in6_addr fl_dst_prefix, fl_src_prefix;
  69
  70                 ipv6_addr_prefix(&fl_dst_prefix,
  71                                  &fl->fl6_dst,
  72                                  xdst->u.rt6.rt6i_dst.plen);
  73                 ipv6_addr_prefix(&fl_src_prefix,
  74                                  &fl->fl6_src,
  75                                  xdst->u.rt6.rt6i_src.plen);
  76                 if (ipv6_addr_equal(&xdst->u.rt6.rt6i_dst.addr, &fl_dst_prefix) &&
  77                     ipv6_addr_equal(&xdst->u.rt6.rt6i_src.addr, &fl_src_prefix) &&
  78                     xfrm_bundle_ok(policy, xdst, fl, AF_INET6,
  79                                    (xdst->u.rt6.rt6i_dst.plen != 128 ||
  80                                     xdst->u.rt6.rt6i_src.plen != 128))) {
  81                         dst_clone(dst);
  82                         break;
  83                 }
  84         }
  85         read_unlock_bh(&policy->lock);
  86         return dst;
  87 }
  88
  89 static inline struct in6_addr*
  90 __xfrm6_bundle_addr_remote(struct xfrm_state *x, struct in6_addr *addr)
  91 {
  92         return (x->type->remote_addr) ?
  93                 (struct in6_addr*)x->type->remote_addr(x, (xfrm_address_t *)addr) :
  94                 (struct in6_addr*)&x->id.daddr;
  95 }
  96
  97 static inline struct in6_addr*
  98 __xfrm6_bundle_addr_local(struct xfrm_state *x, struct in6_addr *addr)
  99 {
 100         return (x->type->local_addr) ?
 101                 (struct in6_addr*)x->type->local_addr(x, (xfrm_address_t *)addr) :
 102                 (struct in6_addr*)&x->props.saddr;
 103 }
 104
 105 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
 106  * all the metrics... Shortly, bundle a bundle.
 107  */
 108
 109 static int
 110 __xfrm6_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
 111                       struct flowi *fl, struct dst_entry **dst_p)
 112 {
 113         struct dst_entry *dst, *dst_prev;
 114         struct rt6_info *rt0 = (struct rt6_info*)(*dst_p);
 115         struct rt6_info *rt  = rt0;
 116         struct flowi fl_tunnel = {
 117                 .nl_u = {
 118                         .ip6_u = {
 119                                 .saddr = fl->fl6_src,
 120                                 .daddr = fl->fl6_dst,
 121                         }
 122                 }
 123         };
 124         int i;
 125         int err = 0;
 126         int header_len = 0;
 127         int trailer_len = 0;
 128
 129         dst = dst_prev = NULL;
 130         dst_hold(&rt->u.dst);
 131
 132         for (i = 0; i < nx; i++) {
 133                 struct dst_entry *dst1 = dst_alloc(&xfrm6_dst_ops);
 134                 struct xfrm_dst *xdst;
 135
 136                 if (unlikely(dst1 == NULL)) {
 137                         err = -ENOBUFS;
 138                         dst_release(&rt->u.dst);
 139                         goto error;
 140                 }
 141
 142                 if (!dst)
 143                         dst = dst1;
 144                 else {
 145                         dst_prev->child = dst1;
 146                         dst1->flags |= DST_NOHASH;
 147                         dst_clone(dst1);
 148                 }
 149
 150                 xdst = (struct xfrm_dst *)dst1;
 151                 xdst->route = &rt->u.dst;
 152                 xdst->genid = xfrm[i]->genid;
 153                 if (rt->rt6i_node)
 154                         xdst->route_cookie = rt->rt6i_node->fn_sernum;
 155
 156                 dst1->next = dst_prev;
 157                 dst_prev = dst1;
 158
 159                 if (xfrm[i]->type->flags & XFRM_TYPE_NON_FRAGMENT)
 160                         dst->nfheader_len += xfrm[i]->props.header_len;
 161                 header_len += xfrm[i]->props.header_len;
 162                 trailer_len += xfrm[i]->props.trailer_len;
 163
 164                 if (xfrm[i]->props.mode != XFRM_MODE_TRANSPORT) {
 165                         unsigned short encap_family = xfrm[i]->props.family;
 166                         switch(encap_family) {
 167                         case AF_INET:
 168                                 fl_tunnel.fl4_dst = xfrm[i]->id.daddr.a4;
 169                                 fl_tunnel.fl4_src = xfrm[i]->props.saddr.a4;
 170                                 break;
 171                         case AF_INET6:
 172                                 ipv6_addr_copy(&fl_tunnel.fl6_dst, __xfrm6_bundle_addr_remote(xfrm[i], &fl->fl6_dst));
 173
 174                                 ipv6_addr_copy(&fl_tunnel.fl6_src, __xfrm6_bundle_addr_local(xfrm[i], &fl->fl6_src));
 175                                 break;
 176                         default:
 177                                 BUG_ON(1);
 178                         }
 179
 180                         err = xfrm_dst_lookup((struct xfrm_dst **) &rt,
 181                                               &fl_tunnel, encap_family);
 182                         if (err)
 183                                 goto error;
 184                 } else
 185                         dst_hold(&rt->u.dst);
 186         }
 187
 188         dst_prev->child = &rt->u.dst;
 189         dst->path = &rt->u.dst;
 190         if (rt->rt6i_node)
 191                 ((struct xfrm_dst *)dst)->path_cookie = rt->rt6i_node->fn_sernum;
 192
 193         *dst_p = dst;
 194         dst = dst_prev;
 195
 196         dst_prev = *dst_p;
 197         i = 0;
 198         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
 199                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
 200
 201                 dst_prev->xfrm = xfrm[i++];
 202                 dst_prev->dev = rt->u.dst.dev;
 203                 if (rt->u.dst.dev)
 204                         dev_hold(rt->u.dst.dev);
 205                 dst_prev->obsolete      = -1;
 206                 dst_prev->flags        |= DST_HOST;
 207                 dst_prev->lastuse       = jiffies;
 208                 dst_prev->header_len    = header_len;
 209                 dst_prev->trailer_len   = trailer_len;
 210                 memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
 211
 212                 /* Copy neighbour for reachability confirmation */
 213                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
 214                 dst_prev->input         = rt->u.dst.input;
 215                 dst_prev->output = dst_prev->xfrm->outer_mode->afinfo->output;
 216                 /* Sheit... I remember I did this right. Apparently,
 217                  * it was magically lost, so this code needs audit */
 218                 x->u.rt6.rt6i_flags    = rt0->rt6i_flags&(RTF_ANYCAST|RTF_LOCAL);
 219                 x->u.rt6.rt6i_metric   = rt0->rt6i_metric;
 220                 x->u.rt6.rt6i_node     = rt0->rt6i_node;
 221                 x->u.rt6.rt6i_gateway  = rt0->rt6i_gateway;
 222                 memcpy(&x->u.rt6.rt6i_gateway, &rt0->rt6i_gateway, sizeof(x->u.rt6.rt6i_gateway));
 223                 x->u.rt6.rt6i_dst      = rt0->rt6i_dst;
 224                 x->u.rt6.rt6i_src      = rt0->rt6i_src;
 225                 x->u.rt6.rt6i_idev     = rt0->rt6i_idev;
 226                 in6_dev_hold(rt0->rt6i_idev);
 227                 header_len -= x->u.dst.xfrm->props.header_len;
 228                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
 229         }
 230
 231         xfrm_init_pmtu(dst);
 232         return 0;
 233
 234 error:
 235         if (dst)
 236                 dst_free(dst);
 237         return err;
 238 }
 239
 240 static inline void
 241 _decode_session6(struct sk_buff *skb, struct flowi *fl)
 242 {
 243         u16 offset = skb_network_header_len(skb);
 244         struct ipv6hdr *hdr = ipv6_hdr(skb);
 245         struct ipv6_opt_hdr *exthdr;
 246         const unsigned char *nh = skb_network_header(skb);
 247         u8 nexthdr = nh[IP6CB(skb)->nhoff];
 248
 249         memset(fl, 0, sizeof(struct flowi));
 250         ipv6_addr_copy(&fl->fl6_dst, &hdr->daddr);
 251         ipv6_addr_copy(&fl->fl6_src, &hdr->saddr);
 252
 253         while (pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
 254                 nh = skb_network_header(skb);
 255                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 256
 257                 switch (nexthdr) {
 258                 case NEXTHDR_ROUTING:
 259                 case NEXTHDR_HOP:
 260                 case NEXTHDR_DEST:
 261                         offset += ipv6_optlen(exthdr);
 262                         nexthdr = exthdr->nexthdr;
 263                         exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 264                         break;
 265
 266                 case IPPROTO_UDP:
 267                 case IPPROTO_UDPLITE:
 268                 case IPPROTO_TCP:
 269                 case IPPROTO_SCTP:
 270                 case IPPROTO_DCCP:
 271                         if (pskb_may_pull(skb, nh + offset + 4 - skb->data)) {
 272                                 __be16 *ports = (__be16 *)exthdr;
 273
 274                                 fl->fl_ip_sport = ports[0];
 275                                 fl->fl_ip_dport = ports[1];
 276                         }
 277                         fl->proto = nexthdr;
 278                         return;
 279
 280                 case IPPROTO_ICMPV6:
 281                         if (pskb_may_pull(skb, nh + offset + 2 - skb->data)) {
 282                                 u8 *icmp = (u8 *)exthdr;
 283
 284                                 fl->fl_icmp_type = icmp[0];
 285                                 fl->fl_icmp_code = icmp[1];
 286                         }
 287                         fl->proto = nexthdr;
 288                         return;
 289
 290 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 291                 case IPPROTO_MH:
 292                         if (pskb_may_pull(skb, nh + offset + 3 - skb->data)) {
 293                                 struct ip6_mh *mh;
 294                                 mh = (struct ip6_mh *)exthdr;
 295
 296                                 fl->fl_mh_type = mh->ip6mh_type;
 297                         }
 298                         fl->proto = nexthdr;
 299                         return;
 300 #endif
 301
 302                 /* XXX Why are there these headers? */
 303                 case IPPROTO_AH:
 304                 case IPPROTO_ESP:
 305                 case IPPROTO_COMP:
 306                 default:
 307                         fl->fl_ipsec_spi = 0;
 308                         fl->proto = nexthdr;
 309                         return;
 310                 }
 311         }
 312 }
 313
 314 static inline int xfrm6_garbage_collect(void)
 315 {
 316         xfrm6_policy_afinfo.garbage_collect();
 317         return (atomic_read(&xfrm6_dst_ops.entries) > xfrm6_dst_ops.gc_thresh*2);
 318 }
 319
 320 static void xfrm6_update_pmtu(struct dst_entry *dst, u32 mtu)
 321 {
 322         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 323         struct dst_entry *path = xdst->route;
 324
 325         path->ops->update_pmtu(path, mtu);
 326 }
 327
 328 static void xfrm6_dst_destroy(struct dst_entry *dst)
 329 {
 330         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 331
 332         if (likely(xdst->u.rt6.rt6i_idev))
 333                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 334         xfrm_dst_destroy(xdst);
 335 }
 336
 337 static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 338                              int unregister)
 339 {
 340         struct xfrm_dst *xdst;
 341
 342         if (!unregister)
 343                 return;
 344
 345         xdst = (struct xfrm_dst *)dst;
 346         if (xdst->u.rt6.rt6i_idev->dev == dev) {
 347                 struct inet6_dev *loopback_idev = in6_dev_get(init_net.loopback_dev);
 348                 BUG_ON(!loopback_idev);
 349
 350                 do {
 351                         in6_dev_put(xdst->u.rt6.rt6i_idev);
 352                         xdst->u.rt6.rt6i_idev = loopback_idev;
 353                         in6_dev_hold(loopback_idev);
 354                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 355                 } while (xdst->u.dst.xfrm);
 356
 357                 __in6_dev_put(loopback_idev);
 358         }
 359
 360         xfrm_dst_ifdown(dst, dev);
 361 }
 362
 363 static struct dst_ops xfrm6_dst_ops = {
 364         .family =               AF_INET6,
 365         .protocol =             __constant_htons(ETH_P_IPV6),
 366         .gc =                   xfrm6_garbage_collect,
 367         .update_pmtu =          xfrm6_update_pmtu,
 368         .destroy =              xfrm6_dst_destroy,
 369         .ifdown =               xfrm6_dst_ifdown,
 370         .gc_thresh =            1024,
 371         .entry_size =           sizeof(struct xfrm_dst),
 372 };
 373
 374 static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 375         .family =               AF_INET6,
 376         .dst_ops =              &xfrm6_dst_ops,
 377         .dst_lookup =           xfrm6_dst_lookup,
 378         .get_saddr =            xfrm6_get_saddr,
 379         .find_bundle =          __xfrm6_find_bundle,
 380         .bundle_create =        __xfrm6_bundle_create,
 381         .decode_session =       _decode_session6,
 382 };
 383
 384 static void __init xfrm6_policy_init(void)
 385 {
 386         xfrm_policy_register_afinfo(&xfrm6_policy_afinfo);
 387 }
 388
 389 static void xfrm6_policy_fini(void)
 390 {
 391         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 392 }
 393
 394 void __init xfrm6_init(void)
 395 {
 396         xfrm6_policy_init();
 397         xfrm6_state_init();
 398 }
 399
 400 void xfrm6_fini(void)
 401 {
 402         //xfrm6_input_fini();
 403         xfrm6_policy_fini();
 404         xfrm6_state_fini();
 405 }