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