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
 117         return 0;
 118 }
 119
 120 static inline void
 121 _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
 122 {
 123         struct flowi6 *fl6 = &fl->u.ip6;
 124         int onlyproto = 0;
 125         const struct ipv6hdr *hdr = ipv6_hdr(skb);
 126         u16 offset = sizeof(*hdr);
 127         struct ipv6_opt_hdr *exthdr;
 128         const unsigned char *nh = skb_network_header(skb);
 129         u16 nhoff = IP6CB(skb)->nhoff;
 130         int oif = 0;
 131         u8 nexthdr;
 132
 133         if (!nhoff)
 134                 nhoff = offsetof(struct ipv6hdr, nexthdr);
 135
 136         nexthdr = nh[nhoff];
 137
 138         if (skb_dst(skb))
 139                 oif = skb_dst(skb)->dev->ifindex;
 140
 141         memset(fl6, 0, sizeof(struct flowi6));
 142         fl6->flowi6_mark = skb->mark;
 143         fl6->flowi6_oif = reverse ? skb->skb_iif : oif;
 144
 145         fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
 146         fl6->saddr = reverse ? hdr->daddr : hdr->saddr;
 147
 148         while (nh + offset + 1 < skb->data ||
 149                pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
 150                 nh = skb_network_header(skb);
 151                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 152
 153                 switch (nexthdr) {
 154                 case NEXTHDR_FRAGMENT:
 155                         onlyproto = 1;
 156                         /* fall through */
 157                 case NEXTHDR_ROUTING:
 158                 case NEXTHDR_HOP:
 159                 case NEXTHDR_DEST:
 160                         offset += ipv6_optlen(exthdr);
 161                         nexthdr = exthdr->nexthdr;
 162                         exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 163                         break;
 164
 165                 case IPPROTO_UDP:
 166                 case IPPROTO_UDPLITE:
 167                 case IPPROTO_TCP:
 168                 case IPPROTO_SCTP:
 169                 case IPPROTO_DCCP:
 170                         if (!onlyproto && (nh + offset + 4 < skb->data ||
 171                              pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
 172                                 __be16 *ports;
 173
 174                                 nh = skb_network_header(skb);
 175                                 ports = (__be16 *)(nh + offset);
 176                                 fl6->fl6_sport = ports[!!reverse];
 177                                 fl6->fl6_dport = ports[!reverse];
 178                         }
 179                         fl6->flowi6_proto = nexthdr;
 180                         return;
 181
 182                 case IPPROTO_ICMPV6:
 183                         if (!onlyproto && (nh + offset + 2 < skb->data ||
 184                             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                         offset += ipv6_optlen(exthdr);
 198                         if (!onlyproto && (nh + offset + 3 < skb->data ||
 199                             pskb_may_pull(skb, nh + offset + 3 - skb->data))) {
 200                                 struct ip6_mh *mh;
 201
 202                                 nh = skb_network_header(skb);
 203                                 mh = (struct ip6_mh *)(nh + offset);
 204                                 fl6->fl6_mh_type = mh->ip6mh_type;
 205                         }
 206                         fl6->flowi6_proto = nexthdr;
 207                         return;
 208 #endif
 209
 210                 /* XXX Why are there these headers? */
 211                 case IPPROTO_AH:
 212                 case IPPROTO_ESP:
 213                 case IPPROTO_COMP:
 214                 default:
 215                         fl6->fl6_ipsec_spi = 0;
 216                         fl6->flowi6_proto = nexthdr;
 217                         return;
 218                 }
 219         }
 220 }
 221
 222 static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
 223                               struct sk_buff *skb, u32 mtu)
 224 {
 225         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 226         struct dst_entry *path = xdst->route;
 227
 228         path->ops->update_pmtu(path, sk, skb, mtu);
 229 }
 230
 231 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
 232                            struct sk_buff *skb)
 233 {
 234         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 235         struct dst_entry *path = xdst->route;
 236
 237         path->ops->redirect(path, sk, skb);
 238 }
 239
 240 static void xfrm6_dst_destroy(struct dst_entry *dst)
 241 {
 242         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 243
 244         if (likely(xdst->u.rt6.rt6i_idev))
 245                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 246         dst_destroy_metrics_generic(dst);
 247         xfrm_dst_destroy(xdst);
 248 }
 249
 250 static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 251                              int unregister)
 252 {
 253         struct xfrm_dst *xdst;
 254
 255         if (!unregister)
 256                 return;
 257
 258         xdst = (struct xfrm_dst *)dst;
 259         if (xdst->u.rt6.rt6i_idev->dev == dev) {
 260                 struct inet6_dev *loopback_idev =
 261                         in6_dev_get(dev_net(dev)->loopback_dev);
 262                 BUG_ON(!loopback_idev);
 263
 264                 do {
 265                         in6_dev_put(xdst->u.rt6.rt6i_idev);
 266                         xdst->u.rt6.rt6i_idev = loopback_idev;
 267                         in6_dev_hold(loopback_idev);
 268                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 269                 } while (xdst->u.dst.xfrm);
 270
 271                 __in6_dev_put(loopback_idev);
 272         }
 273
 274         xfrm_dst_ifdown(dst, dev);
 275 }
 276
 277 static struct dst_ops xfrm6_dst_ops_template = {
 278         .family =               AF_INET6,
 279         .update_pmtu =          xfrm6_update_pmtu,
 280         .redirect =             xfrm6_redirect,
 281         .cow_metrics =          dst_cow_metrics_generic,
 282         .destroy =              xfrm6_dst_destroy,
 283         .ifdown =               xfrm6_dst_ifdown,
 284         .local_out =            __ip6_local_out,
 285         .gc_thresh =            32768,
 286 };
 287
 288 static const struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 289         .dst_ops =              &xfrm6_dst_ops_template,
 290         .dst_lookup =           xfrm6_dst_lookup,
 291         .get_saddr =            xfrm6_get_saddr,
 292         .decode_session =       _decode_session6,
 293         .get_tos =              xfrm6_get_tos,
 294         .init_path =            xfrm6_init_path,
 295         .fill_dst =             xfrm6_fill_dst,
 296         .blackhole_route =      ip6_blackhole_route,
 297 };
 298
 299 static int __init xfrm6_policy_init(void)
 300 {
 301         return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo, AF_INET6);
 302 }
 303
 304 static void xfrm6_policy_fini(void)
 305 {
 306         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 307 }
 308
 309 #ifdef CONFIG_SYSCTL
 310 static struct ctl_table xfrm6_policy_table[] = {
 311         {
 312                 .procname       = "xfrm6_gc_thresh",
 313                 .data           = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
 314                 .maxlen         = sizeof(int),
 315                 .mode           = 0644,
 316                 .proc_handler   = proc_dointvec,
 317         },
 318         { }
 319 };
 320
 321 static int __net_init xfrm6_net_sysctl_init(struct net *net)
 322 {
 323         struct ctl_table *table;
 324         struct ctl_table_header *hdr;
 325
 326         table = xfrm6_policy_table;
 327         if (!net_eq(net, &init_net)) {
 328                 table = kmemdup(table, sizeof(xfrm6_policy_table), GFP_KERNEL);
 329                 if (!table)
 330                         goto err_alloc;
 331
 332                 table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
 333         }
 334
 335         hdr = register_net_sysctl(net, "net/ipv6", table);
 336         if (!hdr)
 337                 goto err_reg;
 338
 339         net->ipv6.sysctl.xfrm6_hdr = hdr;
 340         return 0;
 341
 342 err_reg:
 343         if (!net_eq(net, &init_net))
 344                 kfree(table);
 345 err_alloc:
 346         return -ENOMEM;
 347 }
 348
 349 static void __net_exit xfrm6_net_sysctl_exit(struct net *net)
 350 {
 351         struct ctl_table *table;
 352
 353         if (!net->ipv6.sysctl.xfrm6_hdr)
 354                 return;
 355
 356         table = net->ipv6.sysctl.xfrm6_hdr->ctl_table_arg;
 357         unregister_net_sysctl_table(net->ipv6.sysctl.xfrm6_hdr);
 358         if (!net_eq(net, &init_net))
 359                 kfree(table);
 360 }
 361 #else /* CONFIG_SYSCTL */
 362 static inline int xfrm6_net_sysctl_init(struct net *net)
 363 {
 364         return 0;
 365 }
 366
 367 static inline void xfrm6_net_sysctl_exit(struct net *net)
 368 {
 369 }
 370 #endif
 371
 372 static int __net_init xfrm6_net_init(struct net *net)
 373 {
 374         int ret;
 375
 376         memcpy(&net->xfrm.xfrm6_dst_ops, &xfrm6_dst_ops_template,
 377                sizeof(xfrm6_dst_ops_template));
 378         ret = dst_entries_init(&net->xfrm.xfrm6_dst_ops);
 379         if (ret)
 380                 return ret;
 381
 382         ret = xfrm6_net_sysctl_init(net);
 383         if (ret)
 384                 dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 385
 386         return ret;
 387 }
 388
 389 static void __net_exit xfrm6_net_exit(struct net *net)
 390 {
 391         xfrm6_net_sysctl_exit(net);
 392         dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 393 }
 394
 395 static struct pernet_operations xfrm6_net_ops = {
 396         .init   = xfrm6_net_init,
 397         .exit   = xfrm6_net_exit,
 398 };
 399
 400 int __init xfrm6_init(void)
 401 {
 402         int ret;
 403
 404         ret = xfrm6_policy_init();
 405         if (ret)
 406                 goto out;
 407         ret = xfrm6_state_init();
 408         if (ret)
 409                 goto out_policy;
 410
 411         ret = xfrm6_protocol_init();
 412         if (ret)
 413                 goto out_state;
 414
 415         register_pernet_subsys(&xfrm6_net_ops);
 416 out:
 417         return ret;
 418 out_state:
 419         xfrm6_state_fini();
 420 out_policy:
 421         xfrm6_policy_fini();
 422         goto out;
 423 }
 424
 425 void xfrm6_fini(void)
 426 {
 427         unregister_pernet_subsys(&xfrm6_net_ops);
 428         xfrm6_protocol_fini();
 429         xfrm6_policy_fini();
 430         xfrm6_state_fini();
 431 }