net/ipv6/fib6_rules.c

   1 /*
   2  * net/ipv6/fib6_rules.c        IPv6 Routing Policy Rules
   3  *
   4  * Copyright (C)2003-2006 Helsinki University of Technology
   5  * Copyright (C)2003-2006 USAGI/WIDE Project
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License as
   9  *      published by the Free Software Foundation, version 2.
  10  *
  11  * Authors
  12  *      Thomas Graf             <tgraf@suug.ch>
  13  *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
  14  */
  15
  16 #include <linux/netdevice.h>
  17 #include <linux/export.h>
  18
  19 #include <net/fib_rules.h>
  20 #include <net/ipv6.h>
  21 #include <net/addrconf.h>
  22 #include <net/ip6_route.h>
  23 #include <net/netlink.h>
  24
  25 struct fib6_rule {
  26         struct fib_rule         common;
  27         struct rt6key           src;
  28         struct rt6key           dst;
  29         u8                      tclass;
  30 };
  31
  32 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
  33                                    int flags, pol_lookup_t lookup)
  34 {
  35         struct rt6_info *rt;
  36         struct fib_lookup_arg arg = {
  37                 .lookup_ptr = lookup,
  38                 .flags = FIB_LOOKUP_NOREF,
  39         };
  40
  41         /* update flow if oif or iif point to device enslaved to l3mdev */
  42         l3mdev_update_flow(net, flowi6_to_flowi(fl6));
  43
  44         fib_rules_lookup(net->ipv6.fib6_rules_ops,
  45                          flowi6_to_flowi(fl6), flags, &arg);
  46
  47         rt = arg.result;
  48
  49         if (!rt) {
  50                 dst_hold(&net->ipv6.ip6_null_entry->dst);
  51                 return &net->ipv6.ip6_null_entry->dst;
  52         }
  53
  54         if (rt->rt6i_flags & RTF_REJECT &&
  55             rt->dst.error == -EAGAIN) {
  56                 ip6_rt_put(rt);
  57                 rt = net->ipv6.ip6_null_entry;
  58                 dst_hold(&rt->dst);
  59         }
  60
  61         return &rt->dst;
  62 }
  63
  64 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
  65                             int flags, struct fib_lookup_arg *arg)
  66 {
  67         struct flowi6 *flp6 = &flp->u.ip6;
  68         struct rt6_info *rt = NULL;
  69         struct fib6_table *table;
  70         struct net *net = rule->fr_net;
  71         pol_lookup_t lookup = arg->lookup_ptr;
  72         int err = 0;
  73         u32 tb_id;
  74
  75         switch (rule->action) {
  76         case FR_ACT_TO_TBL:
  77                 break;
  78         case FR_ACT_UNREACHABLE:
  79                 err = -ENETUNREACH;
  80                 rt = net->ipv6.ip6_null_entry;
  81                 goto discard_pkt;
  82         default:
  83         case FR_ACT_BLACKHOLE:
  84                 err = -EINVAL;
  85                 rt = net->ipv6.ip6_blk_hole_entry;
  86                 goto discard_pkt;
  87         case FR_ACT_PROHIBIT:
  88                 err = -EACCES;
  89                 rt = net->ipv6.ip6_prohibit_entry;
  90                 goto discard_pkt;
  91         }
  92
  93         tb_id = fib_rule_get_table(rule, arg);
  94         table = fib6_get_table(net, tb_id);
  95         if (!table) {
  96                 err = -EAGAIN;
  97                 goto out;
  98         }
  99
 100         rt = lookup(net, table, flp6, flags);
 101         if (rt != net->ipv6.ip6_null_entry) {
 102                 struct fib6_rule *r = (struct fib6_rule *)rule;
 103
 104                 /*
 105                  * If we need to find a source address for this traffic,
 106                  * we check the result if it meets requirement of the rule.
 107                  */
 108                 if ((rule->flags & FIB_RULE_FIND_SADDR) &&
 109                     r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
 110                         struct in6_addr saddr;
 111
 112                         if (ipv6_dev_get_saddr(net,
 113                                                ip6_dst_idev(&rt->dst)->dev,
 114                                                &flp6->daddr,
 115                                                rt6_flags2srcprefs(flags),
 116                                                &saddr))
 117                                 goto again;
 118                         if (!ipv6_prefix_equal(&saddr, &r->src.addr,
 119                                                r->src.plen))
 120                                 goto again;
 121                         flp6->saddr = saddr;
 122                 }
 123                 err = rt->dst.error;
 124                 goto out;
 125         }
 126 again:
 127         ip6_rt_put(rt);
 128         err = -EAGAIN;
 129         rt = NULL;
 130         goto out;
 131
 132 discard_pkt:
 133         dst_hold(&rt->dst);
 134 out:
 135         arg->result = rt;
 136         return err;
 137 }
 138
 139 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 140 {
 141         struct rt6_info *rt = (struct rt6_info *) arg->result;
 142         struct net_device *dev = NULL;
 143
 144         if (rt->rt6i_idev)
 145                 dev = rt->rt6i_idev->dev;
 146
 147         /* do not accept result if the route does
 148          * not meet the required prefix length
 149          */
 150         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
 151                 goto suppress_route;
 152
 153         /* do not accept result if the route uses a device
 154          * belonging to a forbidden interface group
 155          */
 156         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 157                 goto suppress_route;
 158
 159         return false;
 160
 161 suppress_route:
 162         ip6_rt_put(rt);
 163         return true;
 164 }
 165
 166 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 167 {
 168         struct fib6_rule *r = (struct fib6_rule *) rule;
 169         struct flowi6 *fl6 = &fl->u.ip6;
 170
 171         if (r->dst.plen &&
 172             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
 173                 return 0;
 174
 175         /*
 176          * If FIB_RULE_FIND_SADDR is set and we do not have a
 177          * source address for the traffic, we defer check for
 178          * source address.
 179          */
 180         if (r->src.plen) {
 181                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
 182                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
 183                                                r->src.plen))
 184                                 return 0;
 185                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
 186                         return 0;
 187         }
 188
 189         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
 190                 return 0;
 191
 192         return 1;
 193 }
 194
 195 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
 196         FRA_GENERIC_POLICY,
 197 };
 198
 199 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 200                                struct fib_rule_hdr *frh,
 201                                struct nlattr **tb)
 202 {
 203         int err = -EINVAL;
 204         struct net *net = sock_net(skb->sk);
 205         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 206
 207         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
 208                 if (rule->table == RT6_TABLE_UNSPEC)
 209                         goto errout;
 210
 211                 if (fib6_new_table(net, rule->table) == NULL) {
 212                         err = -ENOBUFS;
 213                         goto errout;
 214                 }
 215         }
 216
 217         if (frh->src_len)
 218                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
 219
 220         if (frh->dst_len)
 221                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
 222
 223         rule6->src.plen = frh->src_len;
 224         rule6->dst.plen = frh->dst_len;
 225         rule6->tclass = frh->tos;
 226
 227         err = 0;
 228 errout:
 229         return err;
 230 }
 231
 232 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 233                              struct nlattr **tb)
 234 {
 235         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 236
 237         if (frh->src_len && (rule6->src.plen != frh->src_len))
 238                 return 0;
 239
 240         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
 241                 return 0;
 242
 243         if (frh->tos && (rule6->tclass != frh->tos))
 244                 return 0;
 245
 246         if (frh->src_len &&
 247             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
 248                 return 0;
 249
 250         if (frh->dst_len &&
 251             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
 252                 return 0;
 253
 254         return 1;
 255 }
 256
 257 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 258                           struct fib_rule_hdr *frh)
 259 {
 260         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 261
 262         frh->dst_len = rule6->dst.plen;
 263         frh->src_len = rule6->src.plen;
 264         frh->tos = rule6->tclass;
 265
 266         if ((rule6->dst.plen &&
 267              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
 268             (rule6->src.plen &&
 269              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
 270                 goto nla_put_failure;
 271         return 0;
 272
 273 nla_put_failure:
 274         return -ENOBUFS;
 275 }
 276
 277 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
 278 {
 279         return nla_total_size(16) /* dst */
 280                + nla_total_size(16); /* src */
 281 }
 282
 283 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
 284         .family                 = AF_INET6,
 285         .rule_size              = sizeof(struct fib6_rule),
 286         .addr_size              = sizeof(struct in6_addr),
 287         .action                 = fib6_rule_action,
 288         .match                  = fib6_rule_match,
 289         .suppress               = fib6_rule_suppress,
 290         .configure              = fib6_rule_configure,
 291         .compare                = fib6_rule_compare,
 292         .fill                   = fib6_rule_fill,
 293         .nlmsg_payload          = fib6_rule_nlmsg_payload,
 294         .nlgroup                = RTNLGRP_IPV6_RULE,
 295         .policy                 = fib6_rule_policy,
 296         .owner                  = THIS_MODULE,
 297         .fro_net                = &init_net,
 298 };
 299
 300 static int __net_init fib6_rules_net_init(struct net *net)
 301 {
 302         struct fib_rules_ops *ops;
 303         int err = -ENOMEM;
 304
 305         ops = fib_rules_register(&fib6_rules_ops_template, net);
 306         if (IS_ERR(ops))
 307                 return PTR_ERR(ops);
 308
 309         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
 310         if (err)
 311                 goto out_fib6_rules_ops;
 312
 313         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
 314         if (err)
 315                 goto out_fib6_rules_ops;
 316
 317         net->ipv6.fib6_rules_ops = ops;
 318 out:
 319         return err;
 320
 321 out_fib6_rules_ops:
 322         fib_rules_unregister(ops);
 323         goto out;
 324 }
 325
 326 static void __net_exit fib6_rules_net_exit(struct net *net)
 327 {
 328         rtnl_lock();
 329         fib_rules_unregister(net->ipv6.fib6_rules_ops);
 330         rtnl_unlock();
 331 }
 332
 333 static struct pernet_operations fib6_rules_net_ops = {
 334         .init = fib6_rules_net_init,
 335         .exit = fib6_rules_net_exit,
 336 };
 337
 338 int __init fib6_rules_init(void)
 339 {
 340         return register_pernet_subsys(&fib6_rules_net_ops);
 341 }
 342
 343
 344 void fib6_rules_cleanup(void)
 345 {
 346         unregister_pernet_subsys(&fib6_rules_net_ops);
 347 }