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/config.h>
  13 #include <linux/inetdevice.h>
  14 #include <net/xfrm.h>
  15 #include <net/ip.h>
  16
  17 static struct dst_ops xfrm4_dst_ops;
  18 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
  19
  20 static struct xfrm_type_map xfrm4_type_map = { .lock = RW_LOCK_UNLOCKED };
  21
  22 static int xfrm4_dst_lookup(struct xfrm_dst **dst, struct flowi *fl)
  23 {
  24         return __ip_route_output_key((struct rtable**)dst, fl);
  25 }
  26
  27 static struct dst_entry *
  28 __xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
  29 {
  30         struct dst_entry *dst;
  31
  32         read_lock_bh(&policy->lock);
  33         for (dst = policy->bundles; dst; dst = dst->next) {
  34                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  35                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
  36                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
  37                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
  38                     xfrm_bundle_ok(xdst, fl, AF_INET)) {
  39                         dst_clone(dst);
  40                         break;
  41                 }
  42         }
  43         read_unlock_bh(&policy->lock);
  44         return dst;
  45 }
  46
  47 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
  48  * all the metrics... Shortly, bundle a bundle.
  49  */
  50
  51 static int
  52 __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
  53                       struct flowi *fl, struct dst_entry **dst_p)
  54 {
  55         struct dst_entry *dst, *dst_prev;
  56         struct rtable *rt0 = (struct rtable*)(*dst_p);
  57         struct rtable *rt = rt0;
  58         u32 remote = fl->fl4_dst;
  59         u32 local  = fl->fl4_src;
  60         struct flowi fl_tunnel = {
  61                 .nl_u = {
  62                         .ip4_u = {
  63                                 .saddr = local,
  64                                 .daddr = remote
  65                         }
  66                 }
  67         };
  68         int i;
  69         int err;
  70         int header_len = 0;
  71         int trailer_len = 0;
  72
  73         dst = dst_prev = NULL;
  74         dst_hold(&rt->u.dst);
  75
  76         for (i = 0; i < nx; i++) {
  77                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
  78                 struct xfrm_dst *xdst;
  79                 int tunnel = 0;
  80
  81                 if (unlikely(dst1 == NULL)) {
  82                         err = -ENOBUFS;
  83                         dst_release(&rt->u.dst);
  84                         goto error;
  85                 }
  86
  87                 if (!dst)
  88                         dst = dst1;
  89                 else {
  90                         dst_prev->child = dst1;
  91                         dst1->flags |= DST_NOHASH;
  92                         dst_clone(dst1);
  93                 }
  94
  95                 xdst = (struct xfrm_dst *)dst1;
  96                 xdst->route = &rt->u.dst;
  97
  98                 dst1->next = dst_prev;
  99                 dst_prev = dst1;
 100                 if (xfrm[i]->props.mode) {
 101                         remote = xfrm[i]->id.daddr.a4;
 102                         local  = xfrm[i]->props.saddr.a4;
 103                         tunnel = 1;
 104                 }
 105                 header_len += xfrm[i]->props.header_len;
 106                 trailer_len += xfrm[i]->props.trailer_len;
 107
 108                 if (tunnel) {
 109                         fl_tunnel.fl4_src = local;
 110                         fl_tunnel.fl4_dst = remote;
 111                         err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
 112                                               &fl_tunnel, AF_INET);
 113                         if (err)
 114                                 goto error;
 115                 } else
 116                         dst_hold(&rt->u.dst);
 117         }
 118
 119         dst_prev->child = &rt->u.dst;
 120         dst->path = &rt->u.dst;
 121
 122         *dst_p = dst;
 123         dst = dst_prev;
 124
 125         dst_prev = *dst_p;
 126         i = 0;
 127         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
 128                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
 129                 x->u.rt.fl = *fl;
 130
 131                 dst_prev->xfrm = xfrm[i++];
 132                 dst_prev->dev = rt->u.dst.dev;
 133                 if (rt->u.dst.dev)
 134                         dev_hold(rt->u.dst.dev);
 135                 dst_prev->obsolete      = -1;
 136                 dst_prev->flags        |= DST_HOST;
 137                 dst_prev->lastuse       = jiffies;
 138                 dst_prev->header_len    = header_len;
 139                 dst_prev->trailer_len   = trailer_len;
 140                 memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
 141
 142                 /* Copy neighbout for reachability confirmation */
 143                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
 144                 dst_prev->input         = rt->u.dst.input;
 145                 dst_prev->output        = xfrm4_output;
 146                 if (rt->peer)
 147                         atomic_inc(&rt->peer->refcnt);
 148                 x->u.rt.peer = rt->peer;
 149                 /* Sheit... I remember I did this right. Apparently,
 150                  * it was magically lost, so this code needs audit */
 151                 x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
 152                 x->u.rt.rt_type = rt->rt_type;
 153                 x->u.rt.rt_src = rt0->rt_src;
 154                 x->u.rt.rt_dst = rt0->rt_dst;
 155                 x->u.rt.rt_gateway = rt->rt_gateway;
 156                 x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
 157                 x->u.rt.idev = rt0->idev;
 158                 in_dev_hold(rt0->idev);
 159                 header_len -= x->u.dst.xfrm->props.header_len;
 160                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
 161         }
 162
 163         xfrm_init_pmtu(dst);
 164         return 0;
 165
 166 error:
 167         if (dst)
 168                 dst_free(dst);
 169         return err;
 170 }
 171
 172 static void
 173 _decode_session4(struct sk_buff *skb, struct flowi *fl)
 174 {
 175         struct iphdr *iph = skb->nh.iph;
 176         u8 *xprth = skb->nh.raw + iph->ihl*4;
 177
 178         memset(fl, 0, sizeof(struct flowi));
 179         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 180                 switch (iph->protocol) {
 181                 case IPPROTO_UDP:
 182                 case IPPROTO_TCP:
 183                 case IPPROTO_SCTP:
 184                 case IPPROTO_DCCP:
 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