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         u16 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 {
 228         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 229         struct dst_entry *path = xdst->route;
 230
 231         path->ops->update_pmtu(path, sk, skb, mtu);
 232 }
 233
 234 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
 235                            struct sk_buff *skb)
 236 {
 237         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 238         struct dst_entry *path = xdst->route;
 239
 240         path->ops->redirect(path, sk, skb);
 241 }
 242
 243 static void xfrm6_dst_destroy(struct dst_entry *dst)
 244 {
 245         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 246
 247         if (likely(xdst->u.rt6.rt6i_idev))
 248                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 249         dst_destroy_metrics_generic(dst);
 250         if (xdst->u.rt6.rt6i_uncached_list)
 251                 rt6_uncached_list_del(&xdst->u.rt6);
 252         xfrm_dst_destroy(xdst);
 253 }
 254
 255 static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 256                              int unregister)
 257 {
 258         struct xfrm_dst *xdst;
 259
 260         if (!unregister)
 261                 return;
 262
 263         xdst = (struct xfrm_dst *)dst;
 264         if (xdst->u.rt6.rt6i_idev->dev == dev) {
 265                 struct inet6_dev *loopback_idev =
 266                         in6_dev_get(dev_net(dev)->loopback_dev);
 267                 BUG_ON(!loopback_idev);
 268
 269                 do {
 270                         in6_dev_put(xdst->u.rt6.rt6i_idev);
 271                         xdst->u.rt6.rt6i_idev = loopback_idev;
 272                         in6_dev_hold(loopback_idev);
 273                         xdst = (struct xfrm_dst *)xfrm_dst_child(&xdst->u.dst);
 274                 } while (xdst->u.dst.xfrm);
 275
 276                 __in6_dev_put(loopback_idev);
 277         }
 278
 279         xfrm_dst_ifdown(dst, dev);
 280 }
 281
 282 static struct dst_ops xfrm6_dst_ops_template = {
 283         .family =               AF_INET6,
 284         .update_pmtu =          xfrm6_update_pmtu,
 285         .redirect =             xfrm6_redirect,
 286         .cow_metrics =          dst_cow_metrics_generic,
 287         .destroy =              xfrm6_dst_destroy,
 288         .ifdown =               xfrm6_dst_ifdown,
 289         .local_out =            __ip6_local_out,
 290         .gc_thresh =            32768,
 291 };
 292
 293 static const struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 294         .dst_ops =              &xfrm6_dst_ops_template,
 295         .dst_lookup =           xfrm6_dst_lookup,
 296         .get_saddr =            xfrm6_get_saddr,
 297         .decode_session =       _decode_session6,
 298         .get_tos =              xfrm6_get_tos,
 299         .init_path =            xfrm6_init_path,
 300         .fill_dst =             xfrm6_fill_dst,
 301         .blackhole_route =      ip6_blackhole_route,
 302 };
 303
 304 static int __init xfrm6_policy_init(void)
 305 {
 306         return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo, AF_INET6);
 307 }
 308
 309 static void xfrm6_policy_fini(void)
 310 {
 311         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 312 }
 313
 314 #ifdef CONFIG_SYSCTL
 315 static struct ctl_table xfrm6_policy_table[] = {
 316         {
 317                 .procname       = "xfrm6_gc_thresh",
 318                 .data           = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
 319                 .maxlen         = sizeof(int),
 320                 .mode           = 0644,
 321                 .proc_handler   = proc_dointvec,
 322         },
 323         { }
 324 };
 325
 326 static int __net_init xfrm6_net_sysctl_init(struct net *net)
 327 {
 328         struct ctl_table *table;
 329         struct ctl_table_header *hdr;
 330
 331         table = xfrm6_policy_table;
 332         if (!net_eq(net, &init_net)) {
 333                 table = kmemdup(table, sizeof(xfrm6_policy_table), GFP_KERNEL);
 334                 if (!table)
 335                         goto err_alloc;
 336
 337                 table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
 338         }
 339
 340         hdr = register_net_sysctl(net, "net/ipv6", table);
 341         if (!hdr)
 342                 goto err_reg;
 343
 344         net->ipv6.sysctl.xfrm6_hdr = hdr;
 345         return 0;
 346
 347 err_reg:
 348         if (!net_eq(net, &init_net))
 349                 kfree(table);
 350 err_alloc:
 351         return -ENOMEM;
 352 }
 353
 354 static void __net_exit xfrm6_net_sysctl_exit(struct net *net)
 355 {
 356         struct ctl_table *table;
 357
 358         if (!net->ipv6.sysctl.xfrm6_hdr)
 359                 return;
 360
 361         table = net->ipv6.sysctl.xfrm6_hdr->ctl_table_arg;
 362         unregister_net_sysctl_table(net->ipv6.sysctl.xfrm6_hdr);
 363         if (!net_eq(net, &init_net))
 364                 kfree(table);
 365 }
 366 #else /* CONFIG_SYSCTL */
 367 static inline int xfrm6_net_sysctl_init(struct net *net)
 368 {
 369         return 0;
 370 }
 371
 372 static inline void xfrm6_net_sysctl_exit(struct net *net)
 373 {
 374 }
 375 #endif
 376
 377 static int __net_init xfrm6_net_init(struct net *net)
 378 {
 379         int ret;
 380
 381         memcpy(&net->xfrm.xfrm6_dst_ops, &xfrm6_dst_ops_template,
 382                sizeof(xfrm6_dst_ops_template));
 383         ret = dst_entries_init(&net->xfrm.xfrm6_dst_ops);
 384         if (ret)
 385                 return ret;
 386
 387         ret = xfrm6_net_sysctl_init(net);
 388         if (ret)
 389                 dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 390
 391         return ret;
 392 }
 393
 394 static void __net_exit xfrm6_net_exit(struct net *net)
 395 {
 396         xfrm6_net_sysctl_exit(net);
 397         dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 398 }
 399
 400 static struct pernet_operations xfrm6_net_ops = {
 401         .init   = xfrm6_net_init,
 402         .exit   = xfrm6_net_exit,
 403 };
 404
 405 int __init xfrm6_init(void)
 406 {
 407         int ret;
 408
 409         ret = xfrm6_policy_init();
 410         if (ret)
 411                 goto out;
 412         ret = xfrm6_state_init();
 413         if (ret)
 414                 goto out_policy;
 415
 416         ret = xfrm6_protocol_init();
 417         if (ret)
 418                 goto out_state;
 419
 420         register_pernet_subsys(&xfrm6_net_ops);
 421 out:
 422         return ret;
 423 out_state:
 424         xfrm6_state_fini();
 425 out_policy:
 426         xfrm6_policy_fini();
 427         goto out;
 428 }
 429
 430 void xfrm6_fini(void)
 431 {
 432         unregister_pernet_subsys(&xfrm6_net_ops);
 433         xfrm6_protocol_fini();
 434         xfrm6_policy_fini();
 435         xfrm6_state_fini();
 436 }