net/ipv6/xfrm6_policy.c

   1 /*
   2  * xfrm6_policy.c: based on xfrm4_policy.c
   3  *
   4  * Authors:
   5  *      Mitsuru KANDA @USAGI
   6  *      Kazunori MIYAZAWA @USAGI
   7  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   8  *              IPv6 support
   9  *      YOSHIFUJI Hideaki
  10  *              Split up af-specific portion
  11  *
  12  */
  13
  14 #include <linux/err.h>
  15 #include <linux/kernel.h>
  16 #include <linux/netdevice.h>
  17 #include <net/addrconf.h>
  18 #include <net/dst.h>
  19 #include <net/xfrm.h>
  20 #include <net/ip.h>
  21 #include <net/ipv6.h>
  22 #include <net/ip6_route.h>
  23 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  24 #include <net/mip6.h>
  25 #endif
  26
  27 static struct xfrm_policy_afinfo xfrm6_policy_afinfo;
  28
  29 static struct dst_entry *xfrm6_dst_lookup(struct net *net, int tos,
  30                                           const xfrm_address_t *saddr,
  31                                           const xfrm_address_t *daddr)
  32 {
  33         struct flowi6 fl6;
  34         struct dst_entry *dst;
  35         int err;
  36
  37         memset(&fl6, 0, sizeof(fl6));
  38         memcpy(&fl6.daddr, daddr, sizeof(fl6.daddr));
  39         if (saddr)
  40                 memcpy(&fl6.saddr, saddr, sizeof(fl6.saddr));
  41
  42         dst = ip6_route_output(net, NULL, &fl6);
  43
  44         err = dst->error;
  45         if (dst->error) {
  46                 dst_release(dst);
  47                 dst = ERR_PTR(err);
  48         }
  49
  50         return dst;
  51 }
  52
  53 static int xfrm6_get_saddr(struct net *net,
  54                            xfrm_address_t *saddr, xfrm_address_t *daddr)
  55 {
  56         struct dst_entry *dst;
  57         struct net_device *dev;
  58
  59         dst = xfrm6_dst_lookup(net, 0, NULL, daddr);
  60         if (IS_ERR(dst))
  61                 return -EHOSTUNREACH;
  62
  63         dev = ip6_dst_idev(dst)->dev;
  64         ipv6_dev_get_saddr(dev_net(dev), dev,
  65                            (struct in6_addr *)&daddr->a6, 0,
  66                            (struct in6_addr *)&saddr->a6);
  67         dst_release(dst);
  68         return 0;
  69 }
  70
  71 static int xfrm6_get_tos(const struct flowi *fl)
  72 {
  73         return 0;
  74 }
  75
  76 static void xfrm6_init_dst(struct net *net, struct xfrm_dst *xdst)
  77 {
  78         struct rt6_info *rt = (struct rt6_info *)xdst;
  79
  80         rt6_init_peer(rt, net->ipv6.peers);
  81 }
  82
  83 static int xfrm6_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  84                            int nfheader_len)
  85 {
  86         if (dst->ops->family == AF_INET6) {
  87                 struct rt6_info *rt = (struct rt6_info *)dst;
  88                 if (rt->rt6i_node)
  89                         path->path_cookie = rt->rt6i_node->fn_sernum;
  90         }
  91
  92         path->u.rt6.rt6i_nfheader_len = nfheader_len;
  93
  94         return 0;
  95 }
  96
  97 static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  98                           const struct flowi *fl)
  99 {
 100         struct rt6_info *rt = (struct rt6_info *)xdst->route;
 101
 102         xdst->u.dst.dev = dev;
 103         dev_hold(dev);
 104
 105         xdst->u.rt6.rt6i_idev = in6_dev_get(dev);
 106         if (!xdst->u.rt6.rt6i_idev) {
 107                 dev_put(dev);
 108                 return -ENODEV;
 109         }
 110
 111         rt6_transfer_peer(&xdst->u.rt6, rt);
 112
 113         /* Sheit... I remember I did this right. Apparently,
 114          * it was magically lost, so this code needs audit */
 115         xdst->u.rt6.rt6i_flags = rt->rt6i_flags & (RTF_ANYCAST |
 116                                                    RTF_LOCAL);
 117         xdst->u.rt6.rt6i_metric = rt->rt6i_metric;
 118         xdst->u.rt6.rt6i_node = rt->rt6i_node;
 119         if (rt->rt6i_node)
 120                 xdst->route_cookie = rt->rt6i_node->fn_sernum;
 121         xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
 122         xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
 123         xdst->u.rt6.rt6i_src = rt->rt6i_src;
 124
 125         return 0;
 126 }
 127
 128 static inline void
 129 _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
 130 {
 131         struct flowi6 *fl6 = &fl->u.ip6;
 132         int onlyproto = 0;
 133         u16 offset = skb_network_header_len(skb);
 134         const struct ipv6hdr *hdr = ipv6_hdr(skb);
 135         struct ipv6_opt_hdr *exthdr;
 136         const unsigned char *nh = skb_network_header(skb);
 137         u8 nexthdr = nh[IP6CB(skb)->nhoff];
 138         int oif = 0;
 139
 140         if (skb_dst(skb))
 141                 oif = skb_dst(skb)->dev->ifindex;
 142
 143         memset(fl6, 0, sizeof(struct flowi6));
 144         fl6->flowi6_mark = skb->mark;
 145         fl6->flowi6_oif = reverse ? skb->skb_iif : oif;
 146
 147         fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
 148         fl6->saddr = reverse ? hdr->daddr : hdr->saddr;
 149
 150         while (nh + offset + 1 < skb->data ||
 151                pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
 152                 nh = skb_network_header(skb);
 153                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 154
 155                 switch (nexthdr) {
 156                 case NEXTHDR_FRAGMENT:
 157                         onlyproto = 1;
 158                 case NEXTHDR_ROUTING:
 159                 case NEXTHDR_HOP:
 160                 case NEXTHDR_DEST:
 161                         offset += ipv6_optlen(exthdr);
 162                         nexthdr = exthdr->nexthdr;
 163                         exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 164                         break;
 165
 166                 case IPPROTO_UDP:
 167                 case IPPROTO_UDPLITE:
 168                 case IPPROTO_TCP:
 169                 case IPPROTO_SCTP:
 170                 case IPPROTO_DCCP:
 171                         if (!onlyproto && (nh + offset + 4 < skb->data ||
 172                              pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
 173                                 __be16 *ports;
 174
 175                                 nh = skb_network_header(skb);
 176                                 ports = (__be16 *)(nh + offset);
 177                                 fl6->fl6_sport = ports[!!reverse];
 178                                 fl6->fl6_dport = ports[!reverse];
 179                         }
 180                         fl6->flowi6_proto = nexthdr;
 181                         return;
 182
 183                 case IPPROTO_ICMPV6:
 184                         if (!onlyproto && pskb_may_pull(skb, nh + offset + 2 - skb->data)) {
 185                                 u8 *icmp;
 186
 187                                 nh = skb_network_header(skb);
 188                                 icmp = (u8 *)(nh + offset);
 189                                 fl6->fl6_icmp_type = icmp[0];
 190                                 fl6->fl6_icmp_code = icmp[1];
 191                         }
 192                         fl6->flowi6_proto = nexthdr;
 193                         return;
 194
 195 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 196                 case IPPROTO_MH:
 197                         if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) {
 198                                 struct ip6_mh *mh;
 199
 200                                 nh = skb_network_header(skb);
 201                                 mh = (struct ip6_mh *)(nh + offset);
 202                                 fl6->fl6_mh_type = mh->ip6mh_type;
 203                         }
 204                         fl6->flowi6_proto = nexthdr;
 205                         return;
 206 #endif
 207
 208                 /* XXX Why are there these headers? */
 209                 case IPPROTO_AH:
 210                 case IPPROTO_ESP:
 211                 case IPPROTO_COMP:
 212                 default:
 213                         fl6->fl6_ipsec_spi = 0;
 214                         fl6->flowi6_proto = nexthdr;
 215                         return;
 216                 }
 217         }
 218 }
 219
 220 static inline int xfrm6_garbage_collect(struct dst_ops *ops)
 221 {
 222         struct net *net = container_of(ops, struct net, xfrm.xfrm6_dst_ops);
 223
 224         xfrm6_policy_afinfo.garbage_collect(net);
 225         return dst_entries_get_fast(ops) > ops->gc_thresh * 2;
 226 }
 227
 228 static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
 229                               struct sk_buff *skb, u32 mtu)
 230 {
 231         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 232         struct dst_entry *path = xdst->route;
 233
 234         path->ops->update_pmtu(path, sk, skb, mtu);
 235 }
 236
 237 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
 238                            struct sk_buff *skb)
 239 {
 240         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 241         struct dst_entry *path = xdst->route;
 242
 243         path->ops->redirect(path, sk, skb);
 244 }
 245
 246 static void xfrm6_dst_destroy(struct dst_entry *dst)
 247 {
 248         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 249
 250         if (likely(xdst->u.rt6.rt6i_idev))
 251                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 252         dst_destroy_metrics_generic(dst);
 253         if (rt6_has_peer(&xdst->u.rt6)) {
 254                 struct inet_peer *peer = rt6_peer_ptr(&xdst->u.rt6);
 255                 inet_putpeer(peer);
 256         }
 257         xfrm_dst_destroy(xdst);
 258 }
 259
 260 static void xfrm6_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.rt6.rt6i_idev->dev == dev) {
 270                 struct inet6_dev *loopback_idev =
 271                         in6_dev_get(dev_net(dev)->loopback_dev);
 272                 BUG_ON(!loopback_idev);
 273
 274                 do {
 275                         in6_dev_put(xdst->u.rt6.rt6i_idev);
 276                         xdst->u.rt6.rt6i_idev = loopback_idev;
 277                         in6_dev_hold(loopback_idev);
 278                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 279                 } while (xdst->u.dst.xfrm);
 280
 281                 __in6_dev_put(loopback_idev);
 282         }
 283
 284         xfrm_dst_ifdown(dst, dev);
 285 }
 286
 287 static struct dst_ops xfrm6_dst_ops = {
 288         .family =               AF_INET6,
 289         .protocol =             cpu_to_be16(ETH_P_IPV6),
 290         .gc =                   xfrm6_garbage_collect,
 291         .update_pmtu =          xfrm6_update_pmtu,
 292         .redirect =             xfrm6_redirect,
 293         .cow_metrics =          dst_cow_metrics_generic,
 294         .destroy =              xfrm6_dst_destroy,
 295         .ifdown =               xfrm6_dst_ifdown,
 296         .local_out =            __ip6_local_out,
 297         .gc_thresh =            32768,
 298 };
 299
 300 static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 301         .family =               AF_INET6,
 302         .dst_ops =              &xfrm6_dst_ops,
 303         .dst_lookup =           xfrm6_dst_lookup,
 304         .get_saddr =            xfrm6_get_saddr,
 305         .decode_session =       _decode_session6,
 306         .get_tos =              xfrm6_get_tos,
 307         .init_dst =             xfrm6_init_dst,
 308         .init_path =            xfrm6_init_path,
 309         .fill_dst =             xfrm6_fill_dst,
 310         .blackhole_route =      ip6_blackhole_route,
 311 };
 312
 313 static int __init xfrm6_policy_init(void)
 314 {
 315         return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo);
 316 }
 317
 318 static void xfrm6_policy_fini(void)
 319 {
 320         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 321 }
 322
 323 #ifdef CONFIG_SYSCTL
 324 static struct ctl_table xfrm6_policy_table[] = {
 325         {
 326                 .procname       = "xfrm6_gc_thresh",
 327                 .data           = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
 328                 .maxlen         = sizeof(int),
 329                 .mode           = 0644,
 330                 .proc_handler   = proc_dointvec,
 331         },
 332         { }
 333 };
 334
 335 static int __net_init xfrm6_net_init(struct net *net)
 336 {
 337         struct ctl_table *table;
 338         struct ctl_table_header *hdr;
 339
 340         table = xfrm6_policy_table;
 341         if (!net_eq(net, &init_net)) {
 342                 table = kmemdup(table, sizeof(xfrm6_policy_table), GFP_KERNEL);
 343                 if (!table)
 344                         goto err_alloc;
 345
 346                 table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
 347         }
 348
 349         hdr = register_net_sysctl(net, "net/ipv6", table);
 350         if (!hdr)
 351                 goto err_reg;
 352
 353         net->ipv6.sysctl.xfrm6_hdr = hdr;
 354         return 0;
 355
 356 err_reg:
 357         if (!net_eq(net, &init_net))
 358                 kfree(table);
 359 err_alloc:
 360         return -ENOMEM;
 361 }
 362
 363 static void __net_exit xfrm6_net_exit(struct net *net)
 364 {
 365         struct ctl_table *table;
 366
 367         if (net->ipv6.sysctl.xfrm6_hdr == NULL)
 368                 return;
 369
 370         table = net->ipv6.sysctl.xfrm6_hdr->ctl_table_arg;
 371         unregister_net_sysctl_table(net->ipv6.sysctl.xfrm6_hdr);
 372         if (!net_eq(net, &init_net))
 373                 kfree(table);
 374 }
 375
 376 static struct pernet_operations xfrm6_net_ops = {
 377         .init   = xfrm6_net_init,
 378         .exit   = xfrm6_net_exit,
 379 };
 380 #endif
 381
 382 int __init xfrm6_init(void)
 383 {
 384         int ret;
 385
 386         dst_entries_init(&xfrm6_dst_ops);
 387
 388         ret = xfrm6_policy_init();
 389         if (ret) {
 390                 dst_entries_destroy(&xfrm6_dst_ops);
 391                 goto out;
 392         }
 393         ret = xfrm6_state_init();
 394         if (ret)
 395                 goto out_policy;
 396
 397         ret = xfrm6_protocol_init();
 398         if (ret)
 399                 goto out_state;
 400
 401 #ifdef CONFIG_SYSCTL
 402         register_pernet_subsys(&xfrm6_net_ops);
 403 #endif
 404 out:
 405         return ret;
 406 out_state:
 407         xfrm6_state_fini();
 408 out_policy:
 409         xfrm6_policy_fini();
 410         goto out;
 411 }
 412
 413 void xfrm6_fini(void)
 414 {
 415 #ifdef CONFIG_SYSCTL
 416         unregister_pernet_subsys(&xfrm6_net_ops);
 417 #endif
 418         xfrm6_protocol_fini();
 419         xfrm6_policy_fini();
 420         xfrm6_state_fini();
 421         dst_entries_destroy(&xfrm6_dst_ops);
 422 }