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