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                 goto out;
 108         }
 109 again:
 110         ip6_rt_put(rt);
 111         err = -EAGAIN;
 112         rt = NULL;
 113         goto out;
 114
 115 discard_pkt:
 116         dst_hold(&rt->dst);
 117 out:
 118         arg->result = rt;
 119         return err;
 120 }
 121
 122 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
 123 {
 124         struct rt6_info *rt = (struct rt6_info *) arg->result;
 125         struct net_device *dev = NULL;
 126
 127         if (rt->rt6i_idev)
 128                 dev = rt->rt6i_idev->dev;
 129
 130         /* do not accept result if the route does
 131          * not meet the required prefix length
 132          */
 133         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
 134                 goto suppress_route;
 135
 136         /* do not accept result if the route uses a device
 137          * belonging to a forbidden interface group
 138          */
 139         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
 140                 goto suppress_route;
 141
 142         return false;
 143
 144 suppress_route:
 145         ip6_rt_put(rt);
 146         return true;
 147 }
 148
 149 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 150 {
 151         struct fib6_rule *r = (struct fib6_rule *) rule;
 152         struct flowi6 *fl6 = &fl->u.ip6;
 153
 154         if (r->dst.plen &&
 155             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
 156                 return 0;
 157
 158         /*
 159          * If FIB_RULE_FIND_SADDR is set and we do not have a
 160          * source address for the traffic, we defer check for
 161          * source address.
 162          */
 163         if (r->src.plen) {
 164                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
 165                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
 166                                                r->src.plen))
 167                                 return 0;
 168                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
 169                         return 0;
 170         }
 171
 172         if (r->tclass && r->tclass != ((ntohl(fl6->flowlabel) >> 20) & 0xff))
 173                 return 0;
 174
 175         return 1;
 176 }
 177
 178 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
 179         FRA_GENERIC_POLICY,
 180 };
 181
 182 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 183                                struct fib_rule_hdr *frh,
 184                                struct nlattr **tb)
 185 {
 186         int err = -EINVAL;
 187         struct net *net = sock_net(skb->sk);
 188         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 189
 190         if (rule->action == FR_ACT_TO_TBL) {
 191                 if (rule->table == RT6_TABLE_UNSPEC)
 192                         goto errout;
 193
 194                 if (fib6_new_table(net, rule->table) == NULL) {
 195                         err = -ENOBUFS;
 196                         goto errout;
 197                 }
 198         }
 199
 200         if (frh->src_len)
 201                 nla_memcpy(&rule6->src.addr, tb[FRA_SRC],
 202                            sizeof(struct in6_addr));
 203
 204         if (frh->dst_len)
 205                 nla_memcpy(&rule6->dst.addr, tb[FRA_DST],
 206                            sizeof(struct in6_addr));
 207
 208         rule6->src.plen = frh->src_len;
 209         rule6->dst.plen = frh->dst_len;
 210         rule6->tclass = frh->tos;
 211
 212         err = 0;
 213 errout:
 214         return err;
 215 }
 216
 217 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 218                              struct nlattr **tb)
 219 {
 220         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 221
 222         if (frh->src_len && (rule6->src.plen != frh->src_len))
 223                 return 0;
 224
 225         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
 226                 return 0;
 227
 228         if (frh->tos && (rule6->tclass != frh->tos))
 229                 return 0;
 230
 231         if (frh->src_len &&
 232             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
 233                 return 0;
 234
 235         if (frh->dst_len &&
 236             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
 237                 return 0;
 238
 239         return 1;
 240 }
 241
 242 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 243                           struct fib_rule_hdr *frh)
 244 {
 245         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 246
 247         frh->dst_len = rule6->dst.plen;
 248         frh->src_len = rule6->src.plen;
 249         frh->tos = rule6->tclass;
 250
 251         if ((rule6->dst.plen &&
 252              nla_put(skb, FRA_DST, sizeof(struct in6_addr),
 253                      &rule6->dst.addr)) ||
 254             (rule6->src.plen &&
 255              nla_put(skb, FRA_SRC, sizeof(struct in6_addr),
 256                      &rule6->src.addr)))
 257                 goto nla_put_failure;
 258         return 0;
 259
 260 nla_put_failure:
 261         return -ENOBUFS;
 262 }
 263
 264 static u32 fib6_rule_default_pref(struct fib_rules_ops *ops)
 265 {
 266         return 0x3FFF;
 267 }
 268
 269 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
 270 {
 271         return nla_total_size(16) /* dst */
 272                + nla_total_size(16); /* src */
 273 }
 274
 275 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
 276         .family                 = AF_INET6,
 277         .rule_size              = sizeof(struct fib6_rule),
 278         .addr_size              = sizeof(struct in6_addr),
 279         .action                 = fib6_rule_action,
 280         .match                  = fib6_rule_match,
 281         .suppress               = fib6_rule_suppress,
 282         .configure              = fib6_rule_configure,
 283         .compare                = fib6_rule_compare,
 284         .fill                   = fib6_rule_fill,
 285         .default_pref           = fib6_rule_default_pref,
 286         .nlmsg_payload          = fib6_rule_nlmsg_payload,
 287         .nlgroup                = RTNLGRP_IPV6_RULE,
 288         .policy                 = fib6_rule_policy,
 289         .owner                  = THIS_MODULE,
 290         .fro_net                = &init_net,
 291 };
 292
 293 static int __net_init fib6_rules_net_init(struct net *net)
 294 {
 295         struct fib_rules_ops *ops;
 296         int err = -ENOMEM;
 297
 298         ops = fib_rules_register(&fib6_rules_ops_template, net);
 299         if (IS_ERR(ops))
 300                 return PTR_ERR(ops);
 301         net->ipv6.fib6_rules_ops = ops;
 302
 303
 304         err = fib_default_rule_add(net->ipv6.fib6_rules_ops, 0,
 305                                    RT6_TABLE_LOCAL, 0);
 306         if (err)
 307                 goto out_fib6_rules_ops;
 308
 309         err = fib_default_rule_add(net->ipv6.fib6_rules_ops,
 310                                    0x7FFE, RT6_TABLE_MAIN, 0);
 311         if (err)
 312                 goto out_fib6_rules_ops;
 313
 314 out:
 315         return err;
 316
 317 out_fib6_rules_ops:
 318         fib_rules_unregister(ops);
 319         goto out;
 320 }
 321
 322 static void __net_exit fib6_rules_net_exit(struct net *net)
 323 {
 324         fib_rules_unregister(net->ipv6.fib6_rules_ops);
 325 }
 326
 327 static struct pernet_operations fib6_rules_net_ops = {
 328         .init = fib6_rules_net_init,
 329         .exit = fib6_rules_net_exit,
 330 };
 331
 332 int __init fib6_rules_init(void)
 333 {
 334         return register_pernet_subsys(&fib6_rules_net_ops);
 335 }
 336
 337
 338 void fib6_rules_cleanup(void)
 339 {
 340         unregister_pernet_subsys(&fib6_rules_net_ops);
 341 }