net/ipv6/xfrm6_policy.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * xfrm6_policy.c: based on xfrm4_policy.c
   4  *
   5  * Authors:
   6  *      Mitsuru KANDA @USAGI
   7  *      Kazunori MIYAZAWA @USAGI
   8  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   9  *              IPv6 support
  10  *      YOSHIFUJI Hideaki
  11  *              Split up af-specific portion
  12  *
  13  */
  14
  15 #include <linux/err.h>
  16 #include <linux/kernel.h>
  17 #include <linux/netdevice.h>
  18 #include <net/addrconf.h>
  19 #include <net/dst.h>
  20 #include <net/xfrm.h>
  21 #include <net/ip.h>
  22 #include <net/ipv6.h>
  23 #include <net/ip6_route.h>
  24 #include <net/l3mdev.h>
  25 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  26 #include <net/mip6.h>
  27 #endif
  28
  29 static struct dst_entry *xfrm6_dst_lookup(struct net *net, int tos, int oif,
  30                                           const xfrm_address_t *saddr,
  31                                           const xfrm_address_t *daddr,
  32                                           u32 mark)
  33 {
  34         struct flowi6 fl6;
  35         struct dst_entry *dst;
  36         int err;
  37
  38         memset(&fl6, 0, sizeof(fl6));
  39         fl6.flowi6_oif = l3mdev_master_ifindex_by_index(net, oif);
  40         fl6.flowi6_flags = FLOWI_FLAG_SKIP_NH_OIF;
  41         fl6.flowi6_mark = mark;
  42         memcpy(&fl6.daddr, daddr, sizeof(fl6.daddr));
  43         if (saddr)
  44                 memcpy(&fl6.saddr, saddr, sizeof(fl6.saddr));
  45
  46         dst = ip6_route_output(net, NULL, &fl6);
  47
  48         err = dst->error;
  49         if (dst->error) {
  50                 dst_release(dst);
  51                 dst = ERR_PTR(err);
  52         }
  53
  54         return dst;
  55 }
  56
  57 static int xfrm6_get_saddr(struct net *net, int oif,
  58                            xfrm_address_t *saddr, xfrm_address_t *daddr,
  59                            u32 mark)
  60 {
  61         struct dst_entry *dst;
  62         struct net_device *dev;
  63
  64         dst = xfrm6_dst_lookup(net, 0, oif, NULL, daddr, mark);
  65         if (IS_ERR(dst))
  66                 return -EHOSTUNREACH;
  67
  68         dev = ip6_dst_idev(dst)->dev;
  69         ipv6_dev_get_saddr(dev_net(dev), dev, &daddr->in6, 0, &saddr->in6);
  70         dst_release(dst);
  71         return 0;
  72 }
  73
  74 static int xfrm6_get_tos(const struct flowi *fl)
  75 {
  76         return 0;
  77 }
  78
  79 static int xfrm6_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  80                            int nfheader_len)
  81 {
  82         if (dst->ops->family == AF_INET6) {
  83                 struct rt6_info *rt = (struct rt6_info *)dst;
  84                 path->path_cookie = rt6_get_cookie(rt);
  85         }
  86
  87         path->u.rt6.rt6i_nfheader_len = nfheader_len;
  88
  89         return 0;
  90 }
  91
  92 static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  93                           const struct flowi *fl)
  94 {
  95         struct rt6_info *rt = (struct rt6_info *)xdst->route;
  96
  97         xdst->u.dst.dev = dev;
  98         dev_hold(dev);
  99
 100         xdst->u.rt6.rt6i_idev = in6_dev_get(dev);
 101         if (!xdst->u.rt6.rt6i_idev) {
 102                 dev_put(dev);
 103                 return -ENODEV;
 104         }
 105
 106         /* Sheit... I remember I did this right. Apparently,
 107          * it was magically lost, so this code needs audit */
 108         xdst->u.rt6.rt6i_flags = rt->rt6i_flags & (RTF_ANYCAST |
 109                                                    RTF_LOCAL);
 110         xdst->u.rt6.rt6i_metric = rt->rt6i_metric;
 111         xdst->u.rt6.rt6i_node = rt->rt6i_node;
 112         xdst->route_cookie = rt6_get_cookie(rt);
 113         xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
 114         xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
 115         xdst->u.rt6.rt6i_src = rt->rt6i_src;
 116         INIT_LIST_HEAD(&xdst->u.rt6.rt6i_uncached);
 117         rt6_uncached_list_add(&xdst->u.rt6);
 118         atomic_inc(&dev_net(dev)->ipv6.rt6_stats->fib_rt_uncache);
 119
 120         return 0;
 121 }
 122
 123 static inline void
 124 _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
 125 {
 126         struct flowi6 *fl6 = &fl->u.ip6;
 127         int onlyproto = 0;
 128         const struct ipv6hdr *hdr = ipv6_hdr(skb);
 129         u32 offset = sizeof(*hdr);
 130         struct ipv6_opt_hdr *exthdr;
 131         const unsigned char *nh = skb_network_header(skb);
 132         u16 nhoff = IP6CB(skb)->nhoff;
 133         int oif = 0;
 134         u8 nexthdr;
 135
 136         if (!nhoff)
 137                 nhoff = offsetof(struct ipv6hdr, nexthdr);
 138
 139         nexthdr = nh[nhoff];
 140
 141         if (skb_dst(skb))
 142                 oif = skb_dst(skb)->dev->ifindex;
 143
 144         memset(fl6, 0, sizeof(struct flowi6));
 145         fl6->flowi6_mark = skb->mark;
 146         fl6->flowi6_oif = reverse ? skb->skb_iif : oif;
 147
 148         fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
 149         fl6->saddr = reverse ? hdr->daddr : hdr->saddr;
 150
 151         while (nh + offset + 1 < skb->data ||
 152                pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
 153                 nh = skb_network_header(skb);
 154                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 155
 156                 switch (nexthdr) {
 157                 case NEXTHDR_FRAGMENT:
 158                         onlyproto = 1;
 159                         /* fall through */
 160                 case NEXTHDR_ROUTING:
 161                 case NEXTHDR_HOP:
 162                 case NEXTHDR_DEST:
 163                         offset += ipv6_optlen(exthdr);
 164                         nexthdr = exthdr->nexthdr;
 165                         exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 166                         break;
 167
 168                 case IPPROTO_UDP:
 169                 case IPPROTO_UDPLITE:
 170                 case IPPROTO_TCP:
 171                 case IPPROTO_SCTP:
 172                 case IPPROTO_DCCP:
 173                         if (!onlyproto && (nh + offset + 4 < skb->data ||
 174                              pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
 175                                 __be16 *ports;
 176
 177                                 nh = skb_network_header(skb);
 178                                 ports = (__be16 *)(nh + offset);
 179                                 fl6->fl6_sport = ports[!!reverse];
 180                                 fl6->fl6_dport = ports[!reverse];
 181                         }
 182                         fl6->flowi6_proto = nexthdr;
 183                         return;
 184
 185                 case IPPROTO_ICMPV6:
 186                         if (!onlyproto && (nh + offset + 2 < skb->data ||
 187                             pskb_may_pull(skb, nh + offset + 2 - skb->data))) {
 188                                 u8 *icmp;
 189
 190                                 nh = skb_network_header(skb);
 191                                 icmp = (u8 *)(nh + offset);
 192                                 fl6->fl6_icmp_type = icmp[0];
 193                                 fl6->fl6_icmp_code = icmp[1];
 194                         }
 195                         fl6->flowi6_proto = nexthdr;
 196                         return;
 197
 198 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 199                 case IPPROTO_MH:
 200                         offset += ipv6_optlen(exthdr);
 201                         if (!onlyproto && (nh + offset + 3 < skb->data ||
 202                             pskb_may_pull(skb, nh + offset + 3 - skb->data))) {
 203                                 struct ip6_mh *mh;
 204
 205                                 nh = skb_network_header(skb);
 206                                 mh = (struct ip6_mh *)(nh + offset);
 207                                 fl6->fl6_mh_type = mh->ip6mh_type;
 208                         }
 209                         fl6->flowi6_proto = nexthdr;
 210                         return;
 211 #endif
 212
 213                 /* XXX Why are there these headers? */
 214                 case IPPROTO_AH:
 215                 case IPPROTO_ESP:
 216                 case IPPROTO_COMP:
 217                 default:
 218                         fl6->fl6_ipsec_spi = 0;
 219                         fl6->flowi6_proto = nexthdr;
 220                         return;
 221                 }
 222         }
 223 }
 224
 225 static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
 226                               struct sk_buff *skb, u32 mtu,
 227                               bool confirm_neigh)
 228 {
 229         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 230         struct dst_entry *path = xdst->route;
 231
 232         path->ops->update_pmtu(path, sk, skb, mtu, confirm_neigh);
 233 }
 234
 235 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
 236                            struct sk_buff *skb)
 237 {
 238         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 239         struct dst_entry *path = xdst->route;
 240
 241         path->ops->redirect(path, sk, skb);
 242 }
 243
 244 static void xfrm6_dst_destroy(struct dst_entry *dst)
 245 {
 246         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 247
 248         if (likely(xdst->u.rt6.rt6i_idev))
 249                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 250         dst_destroy_metrics_generic(dst);
 251         if (xdst->u.rt6.rt6i_uncached_list)
 252                 rt6_uncached_list_del(&xdst->u.rt6);
 253         xfrm_dst_destroy(xdst);
 254 }
 255
 256 static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 257                              int unregister)
 258 {
 259         struct xfrm_dst *xdst;
 260
 261         if (!unregister)
 262                 return;
 263
 264         xdst = (struct xfrm_dst *)dst;
 265         if (xdst->u.rt6.rt6i_idev->dev == dev) {
 266                 struct inet6_dev *loopback_idev =
 267                         in6_dev_get(dev_net(dev)->loopback_dev);
 268                 BUG_ON(!loopback_idev);
 269
 270                 do {
 271                         in6_dev_put(xdst->u.rt6.rt6i_idev);
 272                         xdst->u.rt6.rt6i_idev = loopback_idev;
 273                         in6_dev_hold(loopback_idev);
 274                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 275                 } while (xdst->u.dst.xfrm);
 276
 277                 __in6_dev_put(loopback_idev);
 278         }
 279
 280         xfrm_dst_ifdown(dst, dev);
 281 }
 282
 283 static struct dst_ops xfrm6_dst_ops_template = {
 284         .family =               AF_INET6,
 285         .update_pmtu =          xfrm6_update_pmtu,
 286         .redirect =             xfrm6_redirect,
 287         .cow_metrics =          dst_cow_metrics_generic,
 288         .destroy =              xfrm6_dst_destroy,
 289         .ifdown =               xfrm6_dst_ifdown,
 290         .local_out =            __ip6_local_out,
 291         .gc_thresh =            32768,
 292 };
 293
 294 static const struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 295         .dst_ops =              &xfrm6_dst_ops_template,
 296         .dst_lookup =           xfrm6_dst_lookup,
 297         .get_saddr =            xfrm6_get_saddr,
 298         .decode_session =       _decode_session6,
 299         .get_tos =              xfrm6_get_tos,
 300         .init_path =            xfrm6_init_path,
 301         .fill_dst =             xfrm6_fill_dst,
 302         .blackhole_route =      ip6_blackhole_route,
 303 };
 304
 305 static int __init xfrm6_policy_init(void)
 306 {
 307         return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo, AF_INET6);
 308 }
 309
 310 static void xfrm6_policy_fini(void)
 311 {
 312         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 313 }
 314
 315 #ifdef CONFIG_SYSCTL
 316 static struct ctl_table xfrm6_policy_table[] = {
 317         {
 318                 .procname       = "xfrm6_gc_thresh",
 319                 .data           = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
 320                 .maxlen         = sizeof(int),
 321                 .mode           = 0644,
 322                 .proc_handler   = proc_dointvec,
 323         },
 324         { }
 325 };
 326
 327 static int __net_init xfrm6_net_sysctl_init(struct net *net)
 328 {
 329         struct ctl_table *table;
 330         struct ctl_table_header *hdr;
 331
 332         table = xfrm6_policy_table;
 333         if (!net_eq(net, &init_net)) {
 334                 table = kmemdup(table, sizeof(xfrm6_policy_table), GFP_KERNEL);
 335                 if (!table)
 336                         goto err_alloc;
 337
 338                 table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
 339         }
 340
 341         hdr = register_net_sysctl(net, "net/ipv6", table);
 342         if (!hdr)
 343                 goto err_reg;
 344
 345         net->ipv6.sysctl.xfrm6_hdr = hdr;
 346         return 0;
 347
 348 err_reg:
 349         if (!net_eq(net, &init_net))
 350                 kfree(table);
 351 err_alloc:
 352         return -ENOMEM;
 353 }
 354
 355 static void __net_exit xfrm6_net_sysctl_exit(struct net *net)
 356 {
 357         struct ctl_table *table;
 358
 359         if (!net->ipv6.sysctl.xfrm6_hdr)
 360                 return;
 361
 362         table = net->ipv6.sysctl.xfrm6_hdr->ctl_table_arg;
 363         unregister_net_sysctl_table(net->ipv6.sysctl.xfrm6_hdr);
 364         if (!net_eq(net, &init_net))
 365                 kfree(table);
 366 }
 367 #else /* CONFIG_SYSCTL */
 368 static inline int xfrm6_net_sysctl_init(struct net *net)
 369 {
 370         return 0;
 371 }
 372
 373 static inline void xfrm6_net_sysctl_exit(struct net *net)
 374 {
 375 }
 376 #endif
 377
 378 static int __net_init xfrm6_net_init(struct net *net)
 379 {
 380         int ret;
 381
 382         memcpy(&net->xfrm.xfrm6_dst_ops, &xfrm6_dst_ops_template,
 383                sizeof(xfrm6_dst_ops_template));
 384         ret = dst_entries_init(&net->xfrm.xfrm6_dst_ops);
 385         if (ret)
 386                 return ret;
 387
 388         ret = xfrm6_net_sysctl_init(net);
 389         if (ret)
 390                 dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 391
 392         return ret;
 393 }
 394
 395 static void __net_exit xfrm6_net_exit(struct net *net)
 396 {
 397         xfrm6_net_sysctl_exit(net);
 398         dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 399 }
 400
 401 static struct pernet_operations xfrm6_net_ops = {
 402         .init   = xfrm6_net_init,
 403         .exit   = xfrm6_net_exit,
 404 };
 405
 406 int __init xfrm6_init(void)
 407 {
 408         int ret;
 409
 410         ret = xfrm6_policy_init();
 411         if (ret)
 412                 goto out;
 413         ret = xfrm6_state_init();
 414         if (ret)
 415                 goto out_policy;
 416
 417         ret = xfrm6_protocol_init();
 418         if (ret)
 419                 goto out_state;
 420
 421         register_pernet_subsys(&xfrm6_net_ops);
 422 out:
 423         return ret;
 424 out_state:
 425         xfrm6_state_fini();
 426 out_policy:
 427         xfrm6_policy_fini();
 428         goto out;
 429 }
 430
 431 void xfrm6_fini(void)
 432 {
 433         unregister_pernet_subsys(&xfrm6_net_ops);
 434         xfrm6_protocol_fini();
 435         xfrm6_policy_fini();
 436         xfrm6_state_fini();
 437 }