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 <asm/bug.h>
  12 #include <linux/compiler.h>
  13 #include <linux/config.h>
  14 #include <linux/inetdevice.h>
  15 #include <net/xfrm.h>
  16 #include <net/ip.h>
  17
  18 static struct dst_ops xfrm4_dst_ops;
  19 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  20
  21 static struct xfrm_type_map xfrm4_type_map = { .lock = RW_LOCK_UNLOCKED };
  22
  23 static int xfrm4_dst_lookup(struct xfrm_dst **dst, struct flowi *fl)
  24 {
  25         return __ip_route_output_key((struct rtable**)dst, fl);
  26 }
  27
  28 static struct dst_entry *
  29 __xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  30 {
  31         struct dst_entry *dst;
  32
  33         read_lock_bh(&policy->lock);
  34         for (dst = policy->bundles; dst; dst = dst->next) {
  35                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  36                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  37                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  38                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  39                     xfrm_bundle_ok(xdst, fl, AF_INET)) {
  40                         dst_clone(dst);
  41                         break;
  42                 }
  43         }
  44         read_unlock_bh(&policy->lock);
  45         return dst;
  46 }
  47
  48 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
  49  * all the metrics... Shortly, bundle a bundle.
  50  */
  51
  52 static int
  53 __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
  54                       struct flowi *fl, struct dst_entry **dst_p)
  55 {
  56         struct dst_entry *dst, *dst_prev;
  57         struct rtable *rt0 = (struct rtable*)(*dst_p);
  58         struct rtable *rt = rt0;
  59         u32 remote = fl->fl4_dst;
  60         u32 local  = fl->fl4_src;
  61         struct flowi fl_tunnel = {
  62                 .nl_u = {
  63                         .ip4_u = {
  64                                 .saddr = local,
  65                                 .daddr = remote
  66                         }
  67                 }
  68         };
  69         int i;
  70         int err;
  71         int header_len = 0;
  72         int trailer_len = 0;
  73
  74         dst = dst_prev = NULL;
  75         dst_hold(&rt->u.dst);
  76
  77         for (i = 0; i < nx; i++) {
  78                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
  79                 struct xfrm_dst *xdst;
  80                 int tunnel = 0;
  81
  82                 if (unlikely(dst1 == NULL)) {
  83                         err = -ENOBUFS;
  84                         dst_release(&rt->u.dst);
  85                         goto error;
  86                 }
  87
  88                 if (!dst)
  89                         dst = dst1;
  90                 else {
  91                         dst_prev->child = dst1;
  92                         dst1->flags |= DST_NOHASH;
  93                         dst_clone(dst1);
  94                 }
  95
  96                 xdst = (struct xfrm_dst *)dst1;
  97                 xdst->route = &rt->u.dst;
  98
  99                 dst1->next = dst_prev;
 100                 dst_prev = dst1;
 101                 if (xfrm[i]->props.mode) {
 102                         remote = xfrm[i]->id.daddr.a4;
 103                         local  = xfrm[i]->props.saddr.a4;
 104                         tunnel = 1;
 105                 }
 106                 header_len += xfrm[i]->props.header_len;
 107                 trailer_len += xfrm[i]->props.trailer_len;
 108
 109                 if (tunnel) {
 110                         fl_tunnel.fl4_src = local;
 111                         fl_tunnel.fl4_dst = remote;
 112                         err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
 113                                               &fl_tunnel, AF_INET);
 114                         if (err)
 115                                 goto error;
 116                 } else
 117                         dst_hold(&rt->u.dst);
 118         }
 119
 120         dst_prev->child = &rt->u.dst;
 121         dst->path = &rt->u.dst;
 122
 123         *dst_p = dst;
 124         dst = dst_prev;
 125
 126         dst_prev = *dst_p;
 127         i = 0;
 128         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
 129                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
 130                 x->u.rt.fl = *fl;
 131
 132                 dst_prev->xfrm = xfrm[i++];
 133                 dst_prev->dev = rt->u.dst.dev;
 134                 if (rt->u.dst.dev)
 135                         dev_hold(rt->u.dst.dev);
 136                 dst_prev->obsolete      = -1;
 137                 dst_prev->flags        |= DST_HOST;
 138                 dst_prev->lastuse       = jiffies;
 139                 dst_prev->header_len    = header_len;
 140                 dst_prev->trailer_len   = trailer_len;
 141                 memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
 142
 143                 /* Copy neighbout for reachability confirmation */
 144                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
 145                 dst_prev->input         = rt->u.dst.input;
 146                 dst_prev->output        = xfrm4_output;
 147                 if (rt->peer)
 148                         atomic_inc(&rt->peer->refcnt);
 149                 x->u.rt.peer = rt->peer;
 150                 /* Sheit... I remember I did this right. Apparently,
 151                  * it was magically lost, so this code needs audit */
 152                 x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
 153                 x->u.rt.rt_type = rt->rt_type;
 154                 x->u.rt.rt_src = rt0->rt_src;
 155                 x->u.rt.rt_dst = rt0->rt_dst;
 156                 x->u.rt.rt_gateway = rt->rt_gateway;
 157                 x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
 158                 x->u.rt.idev = rt0->idev;
 159                 in_dev_hold(rt0->idev);
 160                 header_len -= x->u.dst.xfrm->props.header_len;
 161                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
 162         }
 163
 164         xfrm_init_pmtu(dst);
 165         return 0;
 166
 167 error:
 168         if (dst)
 169                 dst_free(dst);
 170         return err;
 171 }
 172
 173 static void
 174 _decode_session4(struct sk_buff *skb, struct flowi *fl)
 175 {
 176         struct iphdr *iph = skb->nh.iph;
 177         u8 *xprth = skb->nh.raw + iph->ihl*4;
 178
 179         memset(fl, 0, sizeof(struct flowi));
 180         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 181                 switch (iph->protocol) {
 182                 case IPPROTO_UDP:
 183                 case IPPROTO_TCP:
 184                 case IPPROTO_SCTP:
 185                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 186                                 u16 *ports = (u16 *)xprth;
 187
 188                                 fl->fl_ip_sport = ports[0];
 189                                 fl->fl_ip_dport = ports[1];
 190                         }
 191                         break;
 192
 193                 case IPPROTO_ICMP:
 194                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 195                                 u8 *icmp = xprth;
 196
 197                                 fl->fl_icmp_type = icmp[0];
 198                                 fl->fl_icmp_code = icmp[1];
 199                         }
 200                         break;
 201
 202                 case IPPROTO_ESP:
 203                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 204                                 u32 *ehdr = (u32 *)xprth;
 205
 206                                 fl->fl_ipsec_spi = ehdr[0];
 207                         }
 208                         break;
 209
 210                 case IPPROTO_AH:
 211                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 212                                 u32 *ah_hdr = (u32*)xprth;
 213
 214                                 fl->fl_ipsec_spi = ah_hdr[1];
 215                         }
 216                         break;
 217
 218                 case IPPROTO_COMP:
 219                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 220                                 u16 *ipcomp_hdr = (u16 *)xprth;
 221
 222                                 fl->fl_ipsec_spi = ntohl(ntohs(ipcomp_hdr[1]));
 223                         }
 224                         break;
 225                 default:
 226                         fl->fl_ipsec_spi = 0;
 227                         break;
 228                 };
 229         }
 230         fl->proto = iph->protocol;
 231         fl->fl4_dst = iph->daddr;
 232         fl->fl4_src = iph->saddr;
 233 }
 234
 235 static inline int xfrm4_garbage_collect(void)
 236 {
 237         read_lock(&xfrm4_policy_afinfo.lock);
 238         xfrm4_policy_afinfo.garbage_collect();
 239         read_unlock(&xfrm4_policy_afinfo.lock);
 240         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 241 }
 242
 243 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 244 {
 245         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 246         struct dst_entry *path = xdst->route;
 247
 248         path->ops->update_pmtu(path, mtu);
 249 }
 250
 251 static void xfrm4_dst_destroy(struct dst_entry *dst)
 252 {
 253         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 254
 255         if (likely(xdst->u.rt.idev))
 256                 in_dev_put(xdst->u.rt.idev);
 257         xfrm_dst_destroy(xdst);
 258 }
 259
 260 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 261                              int unregister)
 262 {
 263         struct xfrm_dst *xdst;
 264
 265         if (!unregister)
 266                 return;
 267
 268         xdst = (struct xfrm_dst *)dst;
 269         if (xdst->u.rt.idev->dev == dev) {
 270                 struct in_device *loopback_idev = in_dev_get(&loopback_dev);
 271                 BUG_ON(!loopback_idev);
 272
 273                 do {
 274                         in_dev_put(xdst->u.rt.idev);
 275                         xdst->u.rt.idev = loopback_idev;
 276                         in_dev_hold(loopback_idev);
 277                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 278                 } while (xdst->u.dst.xfrm);
 279
 280                 __in_dev_put(loopback_idev);
 281         }
 282
 283         xfrm_dst_ifdown(dst, dev);
 284 }
 285
 286 static struct dst_ops xfrm4_dst_ops = {
 287         .family =               AF_INET,
 288         .protocol =             __constant_htons(ETH_P_IP),
 289         .gc =                   xfrm4_garbage_collect,
 290         .update_pmtu =          xfrm4_update_pmtu,
 291         .destroy =              xfrm4_dst_destroy,
 292         .ifdown =               xfrm4_dst_ifdown,
 293         .gc_thresh =            1024,
 294         .entry_size =           sizeof(struct xfrm_dst),
 295 };
 296
 297 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 298         .family =               AF_INET,
 299         .lock =                 RW_LOCK_UNLOCKED,
 300         .type_map =             &xfrm4_type_map,
 301         .dst_ops =              &xfrm4_dst_ops,
 302         .dst_lookup =           xfrm4_dst_lookup,
 303         .find_bundle =          __xfrm4_find_bundle,
 304         .bundle_create =        __xfrm4_bundle_create,
 305         .decode_session =       _decode_session4,
 306 };
 307
 308 static void __init xfrm4_policy_init(void)
 309 {
 310         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 311 }
 312
 313 static void __exit xfrm4_policy_fini(void)
 314 {
 315         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 316 }
 317
 318 void __init xfrm4_init(void)
 319 {
 320         xfrm4_state_init();
 321         xfrm4_policy_init();
 322 }
 323