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                     xdst->u.rt.fl.fl4_tos == fl->fl4_tos &&
  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                                 .tos = fl->fl4_tos
  67                         }
  68                 }
  69         };
  70         int i;
  71         int err;
  72         int header_len = 0;
  73         int trailer_len = 0;
  74
  75         dst = dst_prev = NULL;
  76         dst_hold(&rt->u.dst);
  77
  78         for (i = 0; i < nx; i++) {
  79                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
  80                 struct xfrm_dst *xdst;
  81                 int tunnel = 0;
  82
  83                 if (unlikely(dst1 == NULL)) {
  84                         err = -ENOBUFS;
  85                         dst_release(&rt->u.dst);
  86                         goto error;
  87                 }
  88
  89                 if (!dst)
  90                         dst = dst1;
  91                 else {
  92                         dst_prev->child = dst1;
  93                         dst1->flags |= DST_NOHASH;
  94                         dst_clone(dst1);
  95                 }
  96
  97                 xdst = (struct xfrm_dst *)dst1;
  98                 xdst->route = &rt->u.dst;
  99
 100                 dst1->next = dst_prev;
 101                 dst_prev = dst1;
 102                 if (xfrm[i]->props.mode) {
 103                         remote = xfrm[i]->id.daddr.a4;
 104                         local  = xfrm[i]->props.saddr.a4;
 105                         tunnel = 1;
 106                 }
 107                 header_len += xfrm[i]->props.header_len;
 108                 trailer_len += xfrm[i]->props.trailer_len;
 109
 110                 if (tunnel) {
 111                         fl_tunnel.fl4_src = local;
 112                         fl_tunnel.fl4_dst = remote;
 113                         err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
 114                                               &fl_tunnel, AF_INET);
 115                         if (err)
 116                                 goto error;
 117                 } else
 118                         dst_hold(&rt->u.dst);
 119         }
 120
 121         dst_prev->child = &rt->u.dst;
 122         dst->path = &rt->u.dst;
 123
 124         *dst_p = dst;
 125         dst = dst_prev;
 126
 127         dst_prev = *dst_p;
 128         i = 0;
 129         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
 130                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
 131                 x->u.rt.fl = *fl;
 132
 133                 dst_prev->xfrm = xfrm[i++];
 134                 dst_prev->dev = rt->u.dst.dev;
 135                 if (rt->u.dst.dev)
 136                         dev_hold(rt->u.dst.dev);
 137                 dst_prev->obsolete      = -1;
 138                 dst_prev->flags        |= DST_HOST;
 139                 dst_prev->lastuse       = jiffies;
 140                 dst_prev->header_len    = header_len;
 141                 dst_prev->trailer_len   = trailer_len;
 142                 memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
 143
 144                 /* Copy neighbout for reachability confirmation */
 145                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
 146                 dst_prev->input         = rt->u.dst.input;
 147                 dst_prev->output        = xfrm4_output;
 148                 if (rt->peer)
 149                         atomic_inc(&rt->peer->refcnt);
 150                 x->u.rt.peer = rt->peer;
 151                 /* Sheit... I remember I did this right. Apparently,
 152                  * it was magically lost, so this code needs audit */
 153                 x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
 154                 x->u.rt.rt_type = rt->rt_type;
 155                 x->u.rt.rt_src = rt0->rt_src;
 156                 x->u.rt.rt_dst = rt0->rt_dst;
 157                 x->u.rt.rt_gateway = rt->rt_gateway;
 158                 x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
 159                 x->u.rt.idev = rt0->idev;
 160                 in_dev_hold(rt0->idev);
 161                 header_len -= x->u.dst.xfrm->props.header_len;
 162                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
 163         }
 164
 165         xfrm_init_pmtu(dst);
 166         return 0;
 167
 168 error:
 169         if (dst)
 170                 dst_free(dst);
 171         return err;
 172 }
 173
 174 static void
 175 _decode_session4(struct sk_buff *skb, struct flowi *fl)
 176 {
 177         struct iphdr *iph = skb->nh.iph;
 178         u8 *xprth = skb->nh.raw + iph->ihl*4;
 179
 180         memset(fl, 0, sizeof(struct flowi));
 181         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
 182                 switch (iph->protocol) {
 183                 case IPPROTO_UDP:
 184                 case IPPROTO_TCP:
 185                 case IPPROTO_SCTP:
 186                 case IPPROTO_DCCP:
 187                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 188                                 u16 *ports = (u16 *)xprth;
 189
 190                                 fl->fl_ip_sport = ports[0];
 191                                 fl->fl_ip_dport = ports[1];
 192                         }
 193                         break;
 194
 195                 case IPPROTO_ICMP:
 196                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
 197                                 u8 *icmp = xprth;
 198
 199                                 fl->fl_icmp_type = icmp[0];
 200                                 fl->fl_icmp_code = icmp[1];
 201                         }
 202                         break;
 203
 204                 case IPPROTO_ESP:
 205                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 206                                 u32 *ehdr = (u32 *)xprth;
 207
 208                                 fl->fl_ipsec_spi = ehdr[0];
 209                         }
 210                         break;
 211
 212                 case IPPROTO_AH:
 213                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
 214                                 u32 *ah_hdr = (u32*)xprth;
 215
 216                                 fl->fl_ipsec_spi = ah_hdr[1];
 217                         }
 218                         break;
 219
 220                 case IPPROTO_COMP:
 221                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
 222                                 u16 *ipcomp_hdr = (u16 *)xprth;
 223
 224                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 225                         }
 226                         break;
 227                 default:
 228                         fl->fl_ipsec_spi = 0;
 229                         break;
 230                 };
 231         }
 232         fl->proto = iph->protocol;
 233         fl->fl4_dst = iph->daddr;
 234         fl->fl4_src = iph->saddr;
 235         fl->fl4_tos = iph->tos;
 236 }
 237
 238 static inline int xfrm4_garbage_collect(void)
 239 {
 240         read_lock(&xfrm4_policy_afinfo.lock);
 241         xfrm4_policy_afinfo.garbage_collect();
 242         read_unlock(&xfrm4_policy_afinfo.lock);
 243         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
 244 }
 245
 246 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
 247 {
 248         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 249         struct dst_entry *path = xdst->route;
 250
 251         path->ops->update_pmtu(path, mtu);
 252 }
 253
 254 static void xfrm4_dst_destroy(struct dst_entry *dst)
 255 {
 256         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 257
 258         if (likely(xdst->u.rt.idev))
 259                 in_dev_put(xdst->u.rt.idev);
 260         xfrm_dst_destroy(xdst);
 261 }
 262
 263 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 264                              int unregister)
 265 {
 266         struct xfrm_dst *xdst;
 267
 268         if (!unregister)
 269                 return;
 270
 271         xdst = (struct xfrm_dst *)dst;
 272         if (xdst->u.rt.idev->dev == dev) {
 273                 struct in_device *loopback_idev = in_dev_get(&loopback_dev);
 274                 BUG_ON(!loopback_idev);
 275
 276                 do {
 277                         in_dev_put(xdst->u.rt.idev);
 278                         xdst->u.rt.idev = loopback_idev;
 279                         in_dev_hold(loopback_idev);
 280                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 281                 } while (xdst->u.dst.xfrm);
 282
 283                 __in_dev_put(loopback_idev);
 284         }
 285
 286         xfrm_dst_ifdown(dst, dev);
 287 }
 288
 289 static struct dst_ops xfrm4_dst_ops = {
 290         .family =               AF_INET,
 291         .protocol =             __constant_htons(ETH_P_IP),
 292         .gc =                   xfrm4_garbage_collect,
 293         .update_pmtu =          xfrm4_update_pmtu,
 294         .destroy =              xfrm4_dst_destroy,
 295         .ifdown =               xfrm4_dst_ifdown,
 296         .gc_thresh =            1024,
 297         .entry_size =           sizeof(struct xfrm_dst),
 298 };
 299
 300 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
 301         .family =               AF_INET,
 302         .lock =                 RW_LOCK_UNLOCKED,
 303         .type_map =             &xfrm4_type_map,
 304         .dst_ops =              &xfrm4_dst_ops,
 305         .dst_lookup =           xfrm4_dst_lookup,
 306         .find_bundle =          __xfrm4_find_bundle,
 307         .bundle_create =        __xfrm4_bundle_create,
 308         .decode_session =       _decode_session4,
 309 };
 310
 311 static void __init xfrm4_policy_init(void)
 312 {
 313         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
 314 }
 315
 316 static void __exit xfrm4_policy_fini(void)
 317 {
 318         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
 319 }
 320
 321 void __init xfrm4_init(void)
 322 {
 323         xfrm4_state_init();
 324         xfrm4_policy_init();
 325 }
 326