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->route_cookie = rt6_get_cookie(rt);
 111         xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
 112         xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
 113         xdst->u.rt6.rt6i_src = rt->rt6i_src;
 114         INIT_LIST_HEAD(&xdst->u.rt6.rt6i_uncached);
 115         rt6_uncached_list_add(&xdst->u.rt6);
 116         atomic_inc(&dev_net(dev)->ipv6.rt6_stats->fib_rt_uncache);
 117
 118         return 0;
 119 }
 120
 121 static inline void
 122 _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
 123 {
 124         struct flowi6 *fl6 = &fl->u.ip6;
 125         int onlyproto = 0;
 126         const struct ipv6hdr *hdr = ipv6_hdr(skb);
 127         u32 offset = sizeof(*hdr);
 128         struct ipv6_opt_hdr *exthdr;
 129         const unsigned char *nh = skb_network_header(skb);
 130         u16 nhoff = IP6CB(skb)->nhoff;
 131         int oif = 0;
 132         u8 nexthdr;
 133
 134         if (!nhoff)
 135                 nhoff = offsetof(struct ipv6hdr, nexthdr);
 136
 137         nexthdr = nh[nhoff];
 138
 139         if (skb_dst(skb))
 140                 oif = skb_dst(skb)->dev->ifindex;
 141
 142         memset(fl6, 0, sizeof(struct flowi6));
 143         fl6->flowi6_mark = skb->mark;
 144         fl6->flowi6_oif = reverse ? skb->skb_iif : oif;
 145
 146         fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
 147         fl6->saddr = reverse ? hdr->daddr : hdr->saddr;
 148
 149         while (nh + offset + sizeof(*exthdr) < skb->data ||
 150                pskb_may_pull(skb, nh + offset + sizeof(*exthdr) - skb->data)) {
 151                 nh = skb_network_header(skb);
 152                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 153
 154                 switch (nexthdr) {
 155                 case NEXTHDR_FRAGMENT:
 156                         onlyproto = 1;
 157                         /* fall through */
 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 && (nh + offset + 2 < skb->data ||
 185                             pskb_may_pull(skb, nh + offset + 2 - skb->data))) {
 186                                 u8 *icmp;
 187
 188                                 nh = skb_network_header(skb);
 189                                 icmp = (u8 *)(nh + offset);
 190                                 fl6->fl6_icmp_type = icmp[0];
 191                                 fl6->fl6_icmp_code = icmp[1];
 192                         }
 193                         fl6->flowi6_proto = nexthdr;
 194                         return;
 195
 196 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 197                 case IPPROTO_MH:
 198                         offset += ipv6_optlen(exthdr);
 199                         if (!onlyproto && (nh + offset + 3 < skb->data ||
 200                             pskb_may_pull(skb, nh + offset + 3 - skb->data))) {
 201                                 struct ip6_mh *mh;
 202
 203                                 nh = skb_network_header(skb);
 204                                 mh = (struct ip6_mh *)(nh + offset);
 205                                 fl6->fl6_mh_type = mh->ip6mh_type;
 206                         }
 207                         fl6->flowi6_proto = nexthdr;
 208                         return;
 209 #endif
 210
 211                 /* XXX Why are there these headers? */
 212                 case IPPROTO_AH:
 213                 case IPPROTO_ESP:
 214                 case IPPROTO_COMP:
 215                 default:
 216                         fl6->fl6_ipsec_spi = 0;
 217                         fl6->flowi6_proto = nexthdr;
 218                         return;
 219                 }
 220         }
 221 }
 222
 223 static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
 224                               struct sk_buff *skb, u32 mtu,
 225                               bool confirm_neigh)
 226 {
 227         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 228         struct dst_entry *path = xdst->route;
 229
 230         path->ops->update_pmtu(path, sk, skb, mtu, confirm_neigh);
 231 }
 232
 233 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
 234                            struct sk_buff *skb)
 235 {
 236         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 237         struct dst_entry *path = xdst->route;
 238
 239         path->ops->redirect(path, sk, skb);
 240 }
 241
 242 static void xfrm6_dst_destroy(struct dst_entry *dst)
 243 {
 244         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 245
 246         if (likely(xdst->u.rt6.rt6i_idev))
 247                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 248         dst_destroy_metrics_generic(dst);
 249         if (xdst->u.rt6.rt6i_uncached_list)
 250                 rt6_uncached_list_del(&xdst->u.rt6);
 251         xfrm_dst_destroy(xdst);
 252 }
 253
 254 static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 255                              int unregister)
 256 {
 257         struct xfrm_dst *xdst;
 258
 259         if (!unregister)
 260                 return;
 261
 262         xdst = (struct xfrm_dst *)dst;
 263         if (xdst->u.rt6.rt6i_idev->dev == dev) {
 264                 struct inet6_dev *loopback_idev =
 265                         in6_dev_get(dev_net(dev)->loopback_dev);
 266                 BUG_ON(!loopback_idev);
 267
 268                 do {
 269                         in6_dev_put(xdst->u.rt6.rt6i_idev);
 270                         xdst->u.rt6.rt6i_idev = loopback_idev;
 271                         in6_dev_hold(loopback_idev);
 272                         xdst = (struct xfrm_dst *)xfrm_dst_child(&xdst->u.dst);
 273                 } while (xdst->u.dst.xfrm);
 274
 275                 __in6_dev_put(loopback_idev);
 276         }
 277
 278         xfrm_dst_ifdown(dst, dev);
 279 }
 280
 281 static struct dst_ops xfrm6_dst_ops_template = {
 282         .family =               AF_INET6,
 283         .update_pmtu =          xfrm6_update_pmtu,
 284         .redirect =             xfrm6_redirect,
 285         .cow_metrics =          dst_cow_metrics_generic,
 286         .destroy =              xfrm6_dst_destroy,
 287         .ifdown =               xfrm6_dst_ifdown,
 288         .local_out =            __ip6_local_out,
 289         .gc_thresh =            32768,
 290 };
 291
 292 static const struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 293         .dst_ops =              &xfrm6_dst_ops_template,
 294         .dst_lookup =           xfrm6_dst_lookup,
 295         .get_saddr =            xfrm6_get_saddr,
 296         .decode_session =       _decode_session6,
 297         .get_tos =              xfrm6_get_tos,
 298         .init_path =            xfrm6_init_path,
 299         .fill_dst =             xfrm6_fill_dst,
 300         .blackhole_route =      ip6_blackhole_route,
 301 };
 302
 303 static int __init xfrm6_policy_init(void)
 304 {
 305         return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo, AF_INET6);
 306 }
 307
 308 static void xfrm6_policy_fini(void)
 309 {
 310         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 311 }
 312
 313 #ifdef CONFIG_SYSCTL
 314 static struct ctl_table xfrm6_policy_table[] = {
 315         {
 316                 .procname       = "xfrm6_gc_thresh",
 317                 .data           = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
 318                 .maxlen         = sizeof(int),
 319                 .mode           = 0644,
 320                 .proc_handler   = proc_dointvec,
 321         },
 322         { }
 323 };
 324
 325 static int __net_init xfrm6_net_sysctl_init(struct net *net)
 326 {
 327         struct ctl_table *table;
 328         struct ctl_table_header *hdr;
 329
 330         table = xfrm6_policy_table;
 331         if (!net_eq(net, &init_net)) {
 332                 table = kmemdup(table, sizeof(xfrm6_policy_table), GFP_KERNEL);
 333                 if (!table)
 334                         goto err_alloc;
 335
 336                 table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
 337         }
 338
 339         hdr = register_net_sysctl(net, "net/ipv6", table);
 340         if (!hdr)
 341                 goto err_reg;
 342
 343         net->ipv6.sysctl.xfrm6_hdr = hdr;
 344         return 0;
 345
 346 err_reg:
 347         if (!net_eq(net, &init_net))
 348                 kfree(table);
 349 err_alloc:
 350         return -ENOMEM;
 351 }
 352
 353 static void __net_exit xfrm6_net_sysctl_exit(struct net *net)
 354 {
 355         struct ctl_table *table;
 356
 357         if (!net->ipv6.sysctl.xfrm6_hdr)
 358                 return;
 359
 360         table = net->ipv6.sysctl.xfrm6_hdr->ctl_table_arg;
 361         unregister_net_sysctl_table(net->ipv6.sysctl.xfrm6_hdr);
 362         if (!net_eq(net, &init_net))
 363                 kfree(table);
 364 }
 365 #else /* CONFIG_SYSCTL */
 366 static inline int xfrm6_net_sysctl_init(struct net *net)
 367 {
 368         return 0;
 369 }
 370
 371 static inline void xfrm6_net_sysctl_exit(struct net *net)
 372 {
 373 }
 374 #endif
 375
 376 static int __net_init xfrm6_net_init(struct net *net)
 377 {
 378         int ret;
 379
 380         memcpy(&net->xfrm.xfrm6_dst_ops, &xfrm6_dst_ops_template,
 381                sizeof(xfrm6_dst_ops_template));
 382         ret = dst_entries_init(&net->xfrm.xfrm6_dst_ops);
 383         if (ret)
 384                 return ret;
 385
 386         ret = xfrm6_net_sysctl_init(net);
 387         if (ret)
 388                 dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 389
 390         return ret;
 391 }
 392
 393 static void __net_exit xfrm6_net_exit(struct net *net)
 394 {
 395         xfrm6_net_sysctl_exit(net);
 396         dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 397 }
 398
 399 static struct pernet_operations xfrm6_net_ops = {
 400         .init   = xfrm6_net_init,
 401         .exit   = xfrm6_net_exit,
 402 };
 403
 404 int __init xfrm6_init(void)
 405 {
 406         int ret;
 407
 408         ret = xfrm6_policy_init();
 409         if (ret)
 410                 goto out;
 411         ret = xfrm6_state_init();
 412         if (ret)
 413                 goto out_policy;
 414
 415         ret = xfrm6_protocol_init();
 416         if (ret)
 417                 goto out_state;
 418
 419         ret = register_pernet_subsys(&xfrm6_net_ops);
 420         if (ret)
 421                 goto out_protocol;
 422 out:
 423         return ret;
 424 out_protocol:
 425         xfrm6_protocol_fini();
 426 out_state:
 427         xfrm6_state_fini();
 428 out_policy:
 429         xfrm6_policy_fini();
 430         goto out;
 431 }
 432
 433 void xfrm6_fini(void)
 434 {
 435         unregister_pernet_subsys(&xfrm6_net_ops);
 436         xfrm6_protocol_fini();
 437         xfrm6_policy_fini();
 438         xfrm6_state_fini();
 439 }