net/ipv6/xfrm6_policy.c

   1 /*
   2  * xfrm6_policy.c: based on xfrm4_policy.c
   3  *
   4  * Authors:
   5  *      Mitsuru KANDA @USAGI
   6  *      Kazunori MIYAZAWA @USAGI
   7  *      Kunihiro Ishiguro <kunihiro@ipinfusion.com>
   8  *              IPv6 support
   9  *      YOSHIFUJI Hideaki
  10  *              Split up af-specific portion
  11  *
  12  */
  13
  14 #include <linux/err.h>
  15 #include <linux/kernel.h>
  16 #include <linux/netdevice.h>
  17 #include <net/addrconf.h>
  18 #include <net/dst.h>
  19 #include <net/xfrm.h>
  20 #include <net/ip.h>
  21 #include <net/ipv6.h>
  22 #include <net/ip6_route.h>
  23 #include <net/l3mdev.h>
  24 #if IS_ENABLED(CONFIG_IPV6_MIP6)
  25 #include <net/mip6.h>
  26 #endif
  27
  28 static struct xfrm_policy_afinfo xfrm6_policy_afinfo;
  29
  30 static struct dst_entry *xfrm6_dst_lookup(struct net *net, int tos, int oif,
  31                                           const xfrm_address_t *saddr,
  32                                           const xfrm_address_t *daddr)
  33 {
  34         struct flowi6 fl6;
  35         struct dst_entry *dst;
  36         int err;
  37
  38         memset(&fl6, 0, sizeof(fl6));
  39         fl6.flowi6_oif = oif;
  40         fl6.flowi6_flags = FLOWI_FLAG_SKIP_NH_OIF;
  41         memcpy(&fl6.daddr, daddr, sizeof(fl6.daddr));
  42         if (saddr)
  43                 memcpy(&fl6.saddr, saddr, sizeof(fl6.saddr));
  44
  45         dst = ip6_route_output(net, NULL, &fl6);
  46
  47         err = dst->error;
  48         if (dst->error) {
  49                 dst_release(dst);
  50                 dst = ERR_PTR(err);
  51         }
  52
  53         return dst;
  54 }
  55
  56 static int xfrm6_get_saddr(struct net *net, int oif,
  57                            xfrm_address_t *saddr, xfrm_address_t *daddr)
  58 {
  59         struct dst_entry *dst;
  60         struct net_device *dev;
  61
  62         dst = xfrm6_dst_lookup(net, 0, oif, NULL, daddr);
  63         if (IS_ERR(dst))
  64                 return -EHOSTUNREACH;
  65
  66         dev = ip6_dst_idev(dst)->dev;
  67         ipv6_dev_get_saddr(dev_net(dev), dev, &daddr->in6, 0, &saddr->in6);
  68         dst_release(dst);
  69         return 0;
  70 }
  71
  72 static int xfrm6_get_tos(const struct flowi *fl)
  73 {
  74         return 0;
  75 }
  76
  77 static int xfrm6_init_path(struct xfrm_dst *path, struct dst_entry *dst,
  78                            int nfheader_len)
  79 {
  80         if (dst->ops->family == AF_INET6) {
  81                 struct rt6_info *rt = (struct rt6_info *)dst;
  82                 path->path_cookie = rt6_get_cookie(rt);
  83         }
  84
  85         path->u.rt6.rt6i_nfheader_len = nfheader_len;
  86
  87         return 0;
  88 }
  89
  90 static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
  91                           const struct flowi *fl)
  92 {
  93         struct rt6_info *rt = (struct rt6_info *)xdst->route;
  94
  95         xdst->u.dst.dev = dev;
  96         dev_hold(dev);
  97
  98         xdst->u.rt6.rt6i_idev = in6_dev_get(dev);
  99         if (!xdst->u.rt6.rt6i_idev) {
 100                 dev_put(dev);
 101                 return -ENODEV;
 102         }
 103
 104         /* Sheit... I remember I did this right. Apparently,
 105          * it was magically lost, so this code needs audit */
 106         xdst->u.rt6.rt6i_flags = rt->rt6i_flags & (RTF_ANYCAST |
 107                                                    RTF_LOCAL);
 108         xdst->u.rt6.rt6i_metric = rt->rt6i_metric;
 109         xdst->u.rt6.rt6i_node = rt->rt6i_node;
 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
 115         return 0;
 116 }
 117
 118 static inline void
 119 _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
 120 {
 121         struct flowi6 *fl6 = &fl->u.ip6;
 122         int onlyproto = 0;
 123         const struct ipv6hdr *hdr = ipv6_hdr(skb);
 124         u16 offset = sizeof(*hdr);
 125         struct ipv6_opt_hdr *exthdr;
 126         const unsigned char *nh = skb_network_header(skb);
 127         u16 nhoff = IP6CB(skb)->nhoff;
 128         int oif = 0;
 129         u8 nexthdr;
 130
 131         if (!nhoff)
 132                 nhoff = offsetof(struct ipv6hdr, nexthdr);
 133
 134         nexthdr = nh[nhoff];
 135
 136         if (skb_dst(skb))
 137                 oif = l3mdev_fib_oif(skb_dst(skb)->dev);
 138
 139         memset(fl6, 0, sizeof(struct flowi6));
 140         fl6->flowi6_mark = skb->mark;
 141         fl6->flowi6_oif = reverse ? skb->skb_iif : oif;
 142
 143         fl6->daddr = reverse ? hdr->saddr : hdr->daddr;
 144         fl6->saddr = reverse ? hdr->daddr : hdr->saddr;
 145
 146         while (nh + offset + 1 < skb->data ||
 147                pskb_may_pull(skb, nh + offset + 1 - skb->data)) {
 148                 nh = skb_network_header(skb);
 149                 exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 150
 151                 switch (nexthdr) {
 152                 case NEXTHDR_FRAGMENT:
 153                         onlyproto = 1;
 154                 case NEXTHDR_ROUTING:
 155                 case NEXTHDR_HOP:
 156                 case NEXTHDR_DEST:
 157                         offset += ipv6_optlen(exthdr);
 158                         nexthdr = exthdr->nexthdr;
 159                         exthdr = (struct ipv6_opt_hdr *)(nh + offset);
 160                         break;
 161
 162                 case IPPROTO_UDP:
 163                 case IPPROTO_UDPLITE:
 164                 case IPPROTO_TCP:
 165                 case IPPROTO_SCTP:
 166                 case IPPROTO_DCCP:
 167                         if (!onlyproto && (nh + offset + 4 < skb->data ||
 168                              pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
 169                                 __be16 *ports;
 170
 171                                 nh = skb_network_header(skb);
 172                                 ports = (__be16 *)(nh + offset);
 173                                 fl6->fl6_sport = ports[!!reverse];
 174                                 fl6->fl6_dport = ports[!reverse];
 175                         }
 176                         fl6->flowi6_proto = nexthdr;
 177                         return;
 178
 179                 case IPPROTO_ICMPV6:
 180                         if (!onlyproto && (nh + offset + 2 < skb->data ||
 181                             pskb_may_pull(skb, nh + offset + 2 - skb->data))) {
 182                                 u8 *icmp;
 183
 184                                 nh = skb_network_header(skb);
 185                                 icmp = (u8 *)(nh + offset);
 186                                 fl6->fl6_icmp_type = icmp[0];
 187                                 fl6->fl6_icmp_code = icmp[1];
 188                         }
 189                         fl6->flowi6_proto = nexthdr;
 190                         return;
 191
 192 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 193                 case IPPROTO_MH:
 194                         offset += ipv6_optlen(exthdr);
 195                         if (!onlyproto && (nh + offset + 3 < skb->data ||
 196                             pskb_may_pull(skb, nh + offset + 3 - skb->data))) {
 197                                 struct ip6_mh *mh;
 198
 199                                 nh = skb_network_header(skb);
 200                                 mh = (struct ip6_mh *)(nh + offset);
 201                                 fl6->fl6_mh_type = mh->ip6mh_type;
 202                         }
 203                         fl6->flowi6_proto = nexthdr;
 204                         return;
 205 #endif
 206
 207                 /* XXX Why are there these headers? */
 208                 case IPPROTO_AH:
 209                 case IPPROTO_ESP:
 210                 case IPPROTO_COMP:
 211                 default:
 212                         fl6->fl6_ipsec_spi = 0;
 213                         fl6->flowi6_proto = nexthdr;
 214                         return;
 215                 }
 216         }
 217 }
 218
 219 static inline int xfrm6_garbage_collect(struct dst_ops *ops)
 220 {
 221         struct net *net = container_of(ops, struct net, xfrm.xfrm6_dst_ops);
 222
 223         xfrm6_policy_afinfo.garbage_collect(net);
 224         return dst_entries_get_fast(ops) > ops->gc_thresh * 2;
 225 }
 226
 227 static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
 228                               struct sk_buff *skb, u32 mtu)
 229 {
 230         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 231         struct dst_entry *path = xdst->route;
 232
 233         path->ops->update_pmtu(path, sk, skb, mtu);
 234 }
 235
 236 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,
 237                            struct sk_buff *skb)
 238 {
 239         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 240         struct dst_entry *path = xdst->route;
 241
 242         path->ops->redirect(path, sk, skb);
 243 }
 244
 245 static void xfrm6_dst_destroy(struct dst_entry *dst)
 246 {
 247         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
 248
 249         if (likely(xdst->u.rt6.rt6i_idev))
 250                 in6_dev_put(xdst->u.rt6.rt6i_idev);
 251         dst_destroy_metrics_generic(dst);
 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 *)xdst->u.dst.child;
 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 = {
 283         .family =               AF_INET6,
 284         .gc =                   xfrm6_garbage_collect,
 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 =            INT_MAX,
 292 };
 293
 294 static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 295         .family =               AF_INET6,
 296         .dst_ops =              &xfrm6_dst_ops,
 297         .dst_lookup =           xfrm6_dst_lookup,
 298         .get_saddr =            xfrm6_get_saddr,
 299         .decode_session =       _decode_session6,
 300         .get_tos =              xfrm6_get_tos,
 301         .init_path =            xfrm6_init_path,
 302         .fill_dst =             xfrm6_fill_dst,
 303         .blackhole_route =      ip6_blackhole_route,
 304 };
 305
 306 static int __init xfrm6_policy_init(void)
 307 {
 308         return xfrm_policy_register_afinfo(&xfrm6_policy_afinfo);
 309 }
 310
 311 static void xfrm6_policy_fini(void)
 312 {
 313         xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
 314 }
 315
 316 #ifdef CONFIG_SYSCTL
 317 static struct ctl_table xfrm6_policy_table[] = {
 318         {
 319                 .procname       = "xfrm6_gc_thresh",
 320                 .data           = &init_net.xfrm.xfrm6_dst_ops.gc_thresh,
 321                 .maxlen         = sizeof(int),
 322                 .mode           = 0644,
 323                 .proc_handler   = proc_dointvec,
 324         },
 325         { }
 326 };
 327
 328 static int __net_init xfrm6_net_init(struct net *net)
 329 {
 330         struct ctl_table *table;
 331         struct ctl_table_header *hdr;
 332
 333         table = xfrm6_policy_table;
 334         if (!net_eq(net, &init_net)) {
 335                 table = kmemdup(table, sizeof(xfrm6_policy_table), GFP_KERNEL);
 336                 if (!table)
 337                         goto err_alloc;
 338
 339                 table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
 340         }
 341
 342         hdr = register_net_sysctl(net, "net/ipv6", table);
 343         if (!hdr)
 344                 goto err_reg;
 345
 346         net->ipv6.sysctl.xfrm6_hdr = hdr;
 347         return 0;
 348
 349 err_reg:
 350         if (!net_eq(net, &init_net))
 351                 kfree(table);
 352 err_alloc:
 353         return -ENOMEM;
 354 }
 355
 356 static void __net_exit xfrm6_net_exit(struct net *net)
 357 {
 358         struct ctl_table *table;
 359
 360         if (!net->ipv6.sysctl.xfrm6_hdr)
 361                 return;
 362
 363         table = net->ipv6.sysctl.xfrm6_hdr->ctl_table_arg;
 364         unregister_net_sysctl_table(net->ipv6.sysctl.xfrm6_hdr);
 365         if (!net_eq(net, &init_net))
 366                 kfree(table);
 367 }
 368
 369 static struct pernet_operations xfrm6_net_ops = {
 370         .init   = xfrm6_net_init,
 371         .exit   = xfrm6_net_exit,
 372 };
 373 #endif
 374
 375 int __init xfrm6_init(void)
 376 {
 377         int ret;
 378
 379         dst_entries_init(&xfrm6_dst_ops);
 380
 381         ret = xfrm6_policy_init();
 382         if (ret) {
 383                 dst_entries_destroy(&xfrm6_dst_ops);
 384                 goto out;
 385         }
 386         ret = xfrm6_state_init();
 387         if (ret)
 388                 goto out_policy;
 389
 390         ret = xfrm6_protocol_init();
 391         if (ret)
 392                 goto out_state;
 393
 394 #ifdef CONFIG_SYSCTL
 395         register_pernet_subsys(&xfrm6_net_ops);
 396 #endif
 397 out:
 398         return ret;
 399 out_state:
 400         xfrm6_state_fini();
 401 out_policy:
 402         xfrm6_policy_fini();
 403         goto out;
 404 }
 405
 406 void xfrm6_fini(void)
 407 {
 408 #ifdef CONFIG_SYSCTL
 409         unregister_pernet_subsys(&xfrm6_net_ops);
 410 #endif
 411         xfrm6_protocol_fini();
 412         xfrm6_policy_fini();
 413         xfrm6_state_fini();
 414         dst_entries_destroy(&xfrm6_dst_ops);
 415 }