net/ipv4/xfrm4_policy.c

   1 /*
   2  * xfrm4_policy.c
   3  *
   4  * Changes:
   5  *      Kazunori MIYAZAWA @USAGI
   6  *      YOSHIFUJI Hideaki @USAGI
   7  *              Split up af-specific portion
   8  *
   9  */
  10
  11 #include <linux/compiler.h>
  12 #include <linux/inetdevice.h>
  13 #include <net/xfrm.h>
  14 #include <net/ip.h>
  15
  16 static struct dst_ops xfrm4_dst_ops;
  17 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  18
  19 static int xfrm4_dst_lookup(struct xfrm_dst **dst, struct flowi *fl)
  20 {
  21         return __ip_route_output_key((struct rtable**)dst, fl);
  22 }
  23
  24 static int xfrm4_get_saddr(xfrm_address_t *saddr, xfrm_address_t *daddr)
  25 {
  26         struct rtable *rt;
  27         struct flowi fl_tunnel = {
  28                 .nl_u = {
  29                         .ip4_u = {
  30                                 .daddr = daddr->a4,
  31                         },
  32                 },
  33         };
  34
  35         if (!xfrm4_dst_lookup((struct xfrm_dst **)&rt, &fl_tunnel)) {
  36                 saddr->a4 = rt->rt_src;
  37                 dst_release(&rt->u.dst);
  38                 return 0;
  39         }
  40         return -EHOSTUNREACH;
  41 }
  42
  43 static struct dst_entry *
  44 __xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  45 {
  46         struct dst_entry *dst;
  47
  48         read_lock_bh(&policy->lock);
  49         for (dst = policy->bundles; dst; dst = dst->next) {
  50                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  51                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  52                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  53                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  54                     xdst->u.rt.fl.fl4_tos == fl->fl4_tos &&
  55                     xfrm_bundle_ok(policy, xdst, fl, AF_INET, 0)) {
  56                         dst_clone(dst);
  57                         break;
  58                 }
  59         }
  60         read_unlock_bh(&policy->lock);
  61         return dst;
  62 }
  63
  64 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
  65  * all the metrics... Shortly, bundle a bundle.
  66  */
  67
  68 static int
  69 __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
  70                       struct flowi *fl, struct dst_entry **dst_p)
  71 {
  72         struct dst_entry *dst, *dst_prev;
  73         struct rtable *rt0 = (struct rtable*)(*dst_p);
  74         struct rtable *rt = rt0;
  75         struct flowi fl_tunnel = {
  76                 .nl_u = {
  77                         .ip4_u = {
  78                                 .saddr = fl->fl4_src,
  79                                 .daddr = fl->fl4_dst,
  80                                 .tos = fl->fl4_tos
  81                         }
  82                 }
  83         };
  84         int i;
  85         int err;
  86         int header_len = 0;
  87         int trailer_len = 0;
  88
  89         dst = dst_prev = NULL;
  90         dst_hold(&rt->u.dst);
  91
  92         for (i = 0; i < nx; i++) {
  93                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
  94                 struct xfrm_dst *xdst;
  95
  96                 if (unlikely(dst1 == NULL)) {
  97                         err = -ENOBUFS;
  98                         dst_release(&rt->u.dst);
  99                         goto error;
 100                 }
 101
 102                 if (!dst)
 103                         dst = dst1;
 104                 else {
 105                         dst_prev->child = dst1;
 106                         dst1->flags |= DST_NOHASH;
 107                         dst_clone(dst1);
 108                 }
 109
 110                 xdst = (struct xfrm_dst *)dst1;
 111                 xdst->route = &rt->u.dst;
 112                 xdst->genid = xfrm[i]->genid;
 113
 114                 dst1->next = dst_prev;
 115                 dst_prev = dst1;
 116
 117                 header_len += xfrm[i]->props.header_len;
 118                 trailer_len += xfrm[i]->props.trailer_len;
 119
 120                 if (xfrm[i]->props.mode == XFRM_MODE_TUNNEL) {
 121                         unsigned short encap_family = xfrm[i]->props.family;
 122                         switch (encap_family) {
 123                         case AF_INET:
 124                                 fl_tunnel.fl4_dst = xfrm[i]->id.daddr.a4;
 125                                 fl_tunnel.fl4_src = xfrm[i]->props.saddr.a4;
 126                                 break;
 127 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
 128                         case AF_INET6:
 129                                 ipv6_addr_copy(&fl_tunnel.fl6_dst, (struct in6_addr*)&xfrm[i]->id.daddr.a6);
 130                                 ipv6_addr_copy(&fl_tunnel.fl6_src, (struct in6_addr*)&xfrm[i]->props.saddr.a6);
 131                                 break;
 132 #endif
 133                         default:
 134                                 BUG_ON(1);
 135                         }
 136                         err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
 137                                               &fl_tunnel, encap_family);
 138                         if (err)
 139                                 goto error;
 140                 } else
 141                         dst_hold(&rt->u.dst);
 142         }
 143
 144         dst_prev->child = &rt->u.dst;
 145         dst->path = &rt->u.dst;
 146
 147         *dst_p = dst;
 148         dst = dst_prev;
 149
 150         dst_prev = *dst_p;
 151         i = 0;
 152         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
 153                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
 154                 struct xfrm_state_afinfo *afinfo;
 155                 x->u.rt.fl = *fl;
 156
 157                 dst_prev->xfrm = xfrm[i++];
 158                 dst_prev->dev = rt->u.dst.dev;
 159                 if (rt->u.dst.dev)
 160                         dev_hold(rt->u.dst.dev);
 161                 dst_prev->obsolete      = -1;
 162                 dst_prev->flags        |= DST_HOST;
 163                 dst_prev->lastuse       = jiffies;
 164                 dst_prev->header_len    = header_len;
 165                 dst_prev->nfheader_len  = 0;
 166                 dst_prev->trailer_len   = trailer_len;
 167                 memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
 168
 169                 /* Copy neighbout for reachability confirmation */
 170                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
 171                 dst_prev->input         = rt->u.dst.input;
 172                 /* XXX: When IPv6 module can be unloaded, we should manage reference
 173                  * to xfrm6_output in afinfo->output. Miyazawa
 174                  * */
 175                 afinfo = xfrm_state_get_afinfo(dst_prev->xfrm->props.family);
 176                 if (!afinfo) {
 177                         dst = *dst_p;
 178                         err = -EAFNOSUPPORT;
 179                         goto error;
 180                 }
 181                 dst_prev->output = afinfo->output;
 182                 xfrm_state_put_afinfo(afinfo);
 183                 if (dst_prev->xfrm->props.family == AF_INET && rt->peer)
 184                         atomic_inc(&rt->peer->refcnt);
 185                 x->u.rt.peer = rt->peer;
 186                 /* Sheit... I remember I did this right. Apparently,
 187                  * it was magically lost, so this code needs audit */
 188                 x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
 189                 x->u.rt.rt_type = rt->rt_type;
 190                 x->u.rt.rt_src = rt0->rt_src;
 191                 x->u.rt.rt_dst = rt0->rt_dst;
 192                 x->u.rt.rt_gateway = rt->rt_gateway;
 193                 x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
 194                 x->u.rt.idev = rt0->idev;
 195                 in_dev_hold(rt0->idev);
 196                 header_len -= x->u.dst.xfrm->props.header_len;
 197                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
 198         }
 199
 200         xfrm_init_pmtu(dst);
 201         return 0;
 202
 203 error:
 204         if (dst)
 205                 dst_free(dst);
 206         return err;
 207 }
 208
 209 static void
 210 _decode_session4(struct sk_buff *skb, struct flowi *fl)
 211 {
 212         struct iphdr *iph = ip_hdr(skb);
 213         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
 214
 215         memset(fl, 0, sizeof(struct flowi));
 216         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 217                 switch (iph->protocol) {
 218                 case IPPROTO_UDP:
 219                 case IPPROTO_UDPLITE:
 220                 case IPPROTO_TCP:
 221                 case IPPROTO_SCTP:
 222                 case IPPROTO_DCCP:
 223                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 224                                 __be16 *ports = (__be16 *)xprth;
 225
 226                                 fl->fl_ip_sport = ports[0];
 227                                 fl->fl_ip_dport = ports[1];
 228                         }
 229                         break;
 230
 231                 case IPPROTO_ICMP:
 232                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 233                                 u8 *icmp = xprth;
 234
 235                                 fl->fl_icmp_type = icmp[0];
 236                                 fl->fl_icmp_code = icmp[1];
 237                         }
 238                         break;
 239
 240                 case IPPROTO_ESP:
 241                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 242                                 __be32 *ehdr = (__be32 *)xprth;
 243
 244                                 fl->fl_ipsec_spi = ehdr[0];
 245                         }
 246                         break;
 247
 248                 case IPPROTO_AH:
 249                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 250                                 __be32 *ah_hdr = (__be32*)xprth;
 251
 252                                 fl->fl_ipsec_spi = ah_hdr[1];
 253                         }
 254                         break;
 255
 256                 case IPPROTO_COMP:
 257                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 258                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
 259
 260                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 261                         }
 262                         break;
 263                 default:
 264                         fl->fl_ipsec_spi = 0;
 265                         break;
 266                 }
 267         }
 268         fl->proto = iph->protocol;
 269         fl->fl4_dst = iph->daddr;
 270         fl->fl4_src = iph->saddr;
 271         fl->fl4_tos = iph->tos;
 272 }
 273
 274 static inline int xfrm4_garbage_collect(void)
 275 {
 276         xfrm4_policy_afinfo.garbage_collect();
 277         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 278 }
 279
 280 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 281 {
 282         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 283         struct dst_entry *path = xdst->route;
 284
 285         path->ops->update_pmtu(path, mtu);
 286 }
 287
 288 static void xfrm4_dst_destroy(struct dst_entry *dst)
 289 {
 290         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 291
 292         if (likely(xdst->u.rt.idev))
 293                 in_dev_put(xdst->u.rt.idev);
 294         if (dst->xfrm && dst->xfrm->props.family == AF_INET && likely(xdst->u.rt.peer))
 295                 inet_putpeer(xdst->u.rt.peer);
 296         xfrm_dst_destroy(xdst);
 297 }
 298
 299 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 300                              int unregister)
 301 {
 302         struct xfrm_dst *xdst;
 303
 304         if (!unregister)
 305                 return;
 306
 307         xdst = (struct xfrm_dst *)dst;
 308         if (xdst->u.rt.idev->dev == dev) {
 309                 struct in_device *loopback_idev = in_dev_get(&loopback_dev);
 310                 BUG_ON(!loopback_idev);
 311
 312                 do {
 313                         in_dev_put(xdst->u.rt.idev);
 314                         xdst->u.rt.idev = loopback_idev;
 315                         in_dev_hold(loopback_idev);
 316                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 317                 } while (xdst->u.dst.xfrm);
 318
 319                 __in_dev_put(loopback_idev);
 320         }
 321
 322         xfrm_dst_ifdown(dst, dev);
 323 }
 324
 325 static struct dst_ops xfrm4_dst_ops = {
 326         .family =               AF_INET,
 327         .protocol =             __constant_htons(ETH_P_IP),
 328         .gc =                   xfrm4_garbage_collect,
 329         .update_pmtu =          xfrm4_update_pmtu,
 330         .destroy =              xfrm4_dst_destroy,
 331         .ifdown =               xfrm4_dst_ifdown,
 332         .gc_thresh =            1024,
 333         .entry_size =           sizeof(struct xfrm_dst),
 334 };
 335
 336 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 337         .family =               AF_INET,
 338         .dst_ops =              &xfrm4_dst_ops,
 339         .dst_lookup =           xfrm4_dst_lookup,
 340         .get_saddr =            xfrm4_get_saddr,
 341         .find_bundle =          __xfrm4_find_bundle,
 342         .bundle_create =        __xfrm4_bundle_create,
 343         .decode_session =       _decode_session4,
 344 };
 345
 346 static void __init xfrm4_policy_init(void)
 347 {
 348         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 349 }
 350
 351 static void __exit xfrm4_policy_fini(void)
 352 {
 353         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 354 }
 355
 356 void __init xfrm4_init(void)
 357 {
 358         xfrm4_state_init();
 359         xfrm4_policy_init();
 360 }
 361