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                 case NEXTHDR_ROUTING:
 157                 case NEXTHDR_HOP:
 158                 case NEXTHDR_DEST:
 159                         offset += ipv6_optlen(exthdr);
 160                         nexthdr = exthdr->nexthdr;
 161                         exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 162                         break;
 163
 164                 case IPPROTO_UDP:
 165                 case IPPROTO_UDPLITE:
 166                 case IPPROTO_TCP:
 167                 case IPPROTO_SCTP:
 168                 case IPPROTO_DCCP:
 169                         if (!onlyproto && (nh + offset + 4 < skb->data ||
 170                              pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
 171                                 __be16 *ports;
 172
 173                                 nh = skb_network_header(skb);
 174                                 ports = (__be16 *)(nh + offset);
 175                                 fl6->fl6_sport = ports[!!reverse];
 176                                 fl6->fl6_dport = ports[!reverse];
 177                         }
 178                         fl6->flowi6_proto = nexthdr;
 179                         return;
 180
 181                 case IPPROTO_ICMPV6:
 182                         if (!onlyproto && (nh + offset + 2 < skb->data ||
 183                             pskb_may_pull(skb, nh + offset + 2 - skb->data))) {
 184                                 u8 *icmp;
 185
 186                                 nh = skb_network_header(skb);
 187                                 icmp = (u8 *)(nh + offset);
 188                                 fl6->fl6_icmp_type = icmp[0];
 189                                 fl6->fl6_icmp_code = icmp[1];
 190                         }
 191                         fl6->flowi6_proto = nexthdr;
 192                         return;
 193
 194 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 195                 case IPPROTO_MH:
 196                         offset += ipv6_optlen(exthdr);
 197                         if (!onlyproto && (nh + offset + 3 < skb->data ||
 198                             pskb_may_pull(skb, nh + offset + 3 - skb->data))) {
 199                                 struct ip6_mh *mh;
 200
 201                                 nh = skb_network_header(skb);
 202                                 mh = (struct ip6_mh *)(nh + offset);
 203                                 fl6->fl6_mh_type = mh->ip6mh_type;
 204                         }
 205                         fl6->flowi6_proto = nexthdr;
 206                         return;
 207 #endif
 208
 209                 /* XXX Why are there these headers? */
 210                 case IPPROTO_AH:
 211                 case IPPROTO_ESP:
 212                 case IPPROTO_COMP:
 213                 default:
 214                         fl6->fl6_ipsec_spi = 0;
 215                         fl6->flowi6_proto = nexthdr;
 216                         return;
 217                 }
 218         }
 219 }
 220
 221 static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
 222                               struct sk_buff *skb, u32 mtu)
 223 {
 224         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 225         struct dst_entry *path = xdst->route;
 226
 227         path->ops->update_pmtu(path, sk, skb, mtu);
 228 }
 229
 230 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
 231                            struct sk_buff *skb)
 232 {
 233         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 234         struct dst_entry *path = xdst->route;
 235
 236         path->ops->redirect(path, sk, skb);
 237 }
 238
 239 static void xfrm6_dst_destroy(struct dst_entry *dst)
 240 {
 241         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 242
 243         if (likely(xdst->u.rt6.rt6i_idev))
 244                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 245         dst_destroy_metrics_generic(dst);
 246         xfrm_dst_destroy(xdst);
 247 }
 248
 249 static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 250                              int unregister)
 251 {
 252         struct xfrm_dst *xdst;
 253
 254         if (!unregister)
 255                 return;
 256
 257         xdst = (struct xfrm_dst *)dst;
 258         if (xdst->u.rt6.rt6i_idev->dev == dev) {
 259                 struct inet6_dev *loopback_idev =
 260                         in6_dev_get(dev_net(dev)->loopback_dev);
 261                 BUG_ON(!loopback_idev);
 262
 263                 do {
 264                         in6_dev_put(xdst->u.rt6.rt6i_idev);
 265                         xdst->u.rt6.rt6i_idev = loopback_idev;
 266                         in6_dev_hold(loopback_idev);
 267                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
 268                 } while (xdst->u.dst.xfrm);
 269
 270                 __in6_dev_put(loopback_idev);
 271         }
 272
 273         xfrm_dst_ifdown(dst, dev);
 274 }
 275
 276 static struct dst_ops xfrm6_dst_ops_template = {
 277         .family =               AF_INET6,
 278         .update_pmtu =          xfrm6_update_pmtu,
 279         .redirect =             xfrm6_redirect,
 280         .cow_metrics =          dst_cow_metrics_generic,
 281         .destroy =              xfrm6_dst_destroy,
 282         .ifdown =               xfrm6_dst_ifdown,
 283         .local_out =            __ip6_local_out,
 284         .gc_thresh =            32768,
 285 };
 286
 287 static const struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 288         .dst_ops =              &xfrm6_dst_ops_template,
 289         .dst_lookup =           xfrm6_dst_lookup,
 290         .get_saddr =            xfrm6_get_saddr,
 291         .decode_session =       _decode_session6,
 292         .get_tos =              xfrm6_get_tos,
 293         .init_path =            xfrm6_init_path,
 294         .fill_dst =             xfrm6_fill_dst,
 295         .blackhole_route =      ip6_blackhole_route,
 296 };
 297
 298 static int __init xfrm6_policy_init(void)
 299 {
 300         return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo, AF_INET6);
 301 }
 302
 303 static void xfrm6_policy_fini(void)
 304 {
 305         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 306 }
 307
 308 #ifdef CONFIG_SYSCTL
 309 static struct ctl_table xfrm6_policy_table[] = {
 310         {
 311                 .procname       = "xfrm6_gc_thresh",
 312                 .data           = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
 313                 .maxlen         = sizeof(int),
 314                 .mode           = 0644,
 315                 .proc_handler   = proc_dointvec,
 316         },
 317         { }
 318 };
 319
 320 static int __net_init xfrm6_net_sysctl_init(struct net *net)
 321 {
 322         struct ctl_table *table;
 323         struct ctl_table_header *hdr;
 324
 325         table = xfrm6_policy_table;
 326         if (!net_eq(net, &init_net)) {
 327                 table = kmemdup(table, sizeof(xfrm6_policy_table), GFP_KERNEL);
 328                 if (!table)
 329                         goto err_alloc;
 330
 331                 table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
 332         }
 333
 334         hdr = register_net_sysctl(net, "net/ipv6", table);
 335         if (!hdr)
 336                 goto err_reg;
 337
 338         net->ipv6.sysctl.xfrm6_hdr = hdr;
 339         return 0;
 340
 341 err_reg:
 342         if (!net_eq(net, &init_net))
 343                 kfree(table);
 344 err_alloc:
 345         return -ENOMEM;
 346 }
 347
 348 static void __net_exit xfrm6_net_sysctl_exit(struct net *net)
 349 {
 350         struct ctl_table *table;
 351
 352         if (!net->ipv6.sysctl.xfrm6_hdr)
 353                 return;
 354
 355         table = net->ipv6.sysctl.xfrm6_hdr->ctl_table_arg;
 356         unregister_net_sysctl_table(net->ipv6.sysctl.xfrm6_hdr);
 357         if (!net_eq(net, &init_net))
 358                 kfree(table);
 359 }
 360 #else /* CONFIG_SYSCTL */
 361 static inline int xfrm6_net_sysctl_init(struct net *net)
 362 {
 363         return 0;
 364 }
 365
 366 static inline void xfrm6_net_sysctl_exit(struct net *net)
 367 {
 368 }
 369 #endif
 370
 371 static int __net_init xfrm6_net_init(struct net *net)
 372 {
 373         int ret;
 374
 375         memcpy(&net->xfrm.xfrm6_dst_ops, &xfrm6_dst_ops_template,
 376                sizeof(xfrm6_dst_ops_template));
 377         ret = dst_entries_init(&net->xfrm.xfrm6_dst_ops);
 378         if (ret)
 379                 return ret;
 380
 381         ret = xfrm6_net_sysctl_init(net);
 382         if (ret)
 383                 dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 384
 385         return ret;
 386 }
 387
 388 static void __net_exit xfrm6_net_exit(struct net *net)
 389 {
 390         xfrm6_net_sysctl_exit(net);
 391         dst_entries_destroy(&net->xfrm.xfrm6_dst_ops);
 392 }
 393
 394 static struct pernet_operations xfrm6_net_ops = {
 395         .init   = xfrm6_net_init,
 396         .exit   = xfrm6_net_exit,
 397 };
 398
 399 int __init xfrm6_init(void)
 400 {
 401         int ret;
 402
 403         ret = xfrm6_policy_init();
 404         if (ret)
 405                 goto out;
 406         ret = xfrm6_state_init();
 407         if (ret)
 408                 goto out_policy;
 409
 410         ret = xfrm6_protocol_init();
 411         if (ret)
 412                 goto out_state;
 413
 414         register_pernet_subsys(&xfrm6_net_ops);
 415 out:
 416         return ret;
 417 out_state:
 418         xfrm6_state_fini();
 419 out_policy:
 420         xfrm6_policy_fini();
 421         goto out;
 422 }
 423
 424 void xfrm6_fini(void)
 425 {
 426         unregister_pernet_subsys(&xfrm6_net_ops);
 427         xfrm6_protocol_fini();
 428         xfrm6_policy_fini();
 429         xfrm6_state_fini();
 430 }