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