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