net/ipv4/fib_rules.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              IPv4 Forwarding Information Base: policy rules.
   7  *
   8  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   9  *              Thomas Graf <tgraf@suug.ch>
  10  *
  11  *              This program is free software; you can redistribute it and/or
  12  *              modify it under the terms of the GNU General Public License
  13  *              as published by the Free Software Foundation; either version
  14  *              2 of the License, or (at your option) any later version.
  15  *
  16  * Fixes:
  17  *              Rani Assaf      :       local_rule cannot be deleted
  18  *              Marc Boucher    :       routing by fwmark
  19  */
  20
  21 #include <linux/types.h>
  22 #include <linux/kernel.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/netlink.h>
  25 #include <linux/inetdevice.h>
  26 #include <linux/init.h>
  27 #include <linux/list.h>
  28 #include <linux/rcupdate.h>
  29 #include <net/ip.h>
  30 #include <net/route.h>
  31 #include <net/tcp.h>
  32 #include <net/ip_fib.h>
  33 #include <net/fib_rules.h>
  34
  35 struct fib4_rule {
  36         struct fib_rule         common;
  37         u8                      dst_len;
  38         u8                      src_len;
  39         u8                      tos;
  40         __be32                  src;
  41         __be32                  srcmask;
  42         __be32                  dst;
  43         __be32                  dstmask;
  44 #ifdef CONFIG_IP_ROUTE_CLASSID
  45         u32                     tclassid;
  46 #endif
  47 };
  48
  49 #ifdef CONFIG_IP_ROUTE_CLASSID
  50 u32 fib_rules_tclass(const struct fib_result *res)
  51 {
  52         return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
  53 }
  54 #endif
  55
  56 int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
  57 {
  58         struct fib_lookup_arg arg = {
  59                 .result = res,
  60                 .flags = FIB_LOOKUP_NOREF,
  61         };
  62         int err;
  63
  64         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
  65         res->r = arg.rule;
  66
  67         return err;
  68 }
  69
  70 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  71                             int flags, struct fib_lookup_arg *arg)
  72 {
  73         int err = -EAGAIN;
  74         struct fib_table *tbl;
  75
  76         switch (rule->action) {
  77         case FR_ACT_TO_TBL:
  78                 break;
  79
  80         case FR_ACT_UNREACHABLE:
  81                 err = -ENETUNREACH;
  82                 goto errout;
  83
  84         case FR_ACT_PROHIBIT:
  85                 err = -EACCES;
  86                 goto errout;
  87
  88         case FR_ACT_BLACKHOLE:
  89         default:
  90                 err = -EINVAL;
  91                 goto errout;
  92         }
  93
  94         tbl = fib_get_table(rule->fr_net, rule->table);
  95         if (!tbl)
  96                 goto errout;
  97
  98         err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
  99         if (err > 0)
 100                 err = -EAGAIN;
 101 errout:
 102         return err;
 103 }
 104
 105
 106 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 107 {
 108         struct fib4_rule *r = (struct fib4_rule *) rule;
 109         struct flowi4 *fl4 = &fl->u.ip4;
 110         __be32 daddr = fl4->daddr;
 111         __be32 saddr = fl4->saddr;
 112
 113         if (((saddr ^ r->src) & r->srcmask) ||
 114             ((daddr ^ r->dst) & r->dstmask))
 115                 return 0;
 116
 117         if (r->tos && (r->tos != fl4->flowi4_tos))
 118                 return 0;
 119
 120         return 1;
 121 }
 122
 123 static struct fib_table *fib_empty_table(struct net *net)
 124 {
 125         u32 id;
 126
 127         for (id = 1; id <= RT_TABLE_MAX; id++)
 128                 if (fib_get_table(net, id) == NULL)
 129                         return fib_new_table(net, id);
 130         return NULL;
 131 }
 132
 133 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 134         FRA_GENERIC_POLICY,
 135         [FRA_FLOW]      = { .type = NLA_U32 },
 136 };
 137
 138 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 139                                struct fib_rule_hdr *frh,
 140                                struct nlattr **tb)
 141 {
 142         struct net *net = sock_net(skb->sk);
 143         int err = -EINVAL;
 144         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 145
 146         if (frh->tos & ~IPTOS_TOS_MASK)
 147                 goto errout;
 148
 149         if (rule->table == RT_TABLE_UNSPEC) {
 150                 if (rule->action == FR_ACT_TO_TBL) {
 151                         struct fib_table *table;
 152
 153                         table = fib_empty_table(net);
 154                         if (table == NULL) {
 155                                 err = -ENOBUFS;
 156                                 goto errout;
 157                         }
 158
 159                         rule->table = table->tb_id;
 160                 }
 161         }
 162
 163         if (frh->src_len)
 164                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 165
 166         if (frh->dst_len)
 167                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 168
 169 #ifdef CONFIG_IP_ROUTE_CLASSID
 170         if (tb[FRA_FLOW])
 171                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 172 #endif
 173
 174         rule4->src_len = frh->src_len;
 175         rule4->srcmask = inet_make_mask(rule4->src_len);
 176         rule4->dst_len = frh->dst_len;
 177         rule4->dstmask = inet_make_mask(rule4->dst_len);
 178         rule4->tos = frh->tos;
 179
 180         err = 0;
 181 errout:
 182         return err;
 183 }
 184
 185 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 186                              struct nlattr **tb)
 187 {
 188         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 189
 190         if (frh->src_len && (rule4->src_len != frh->src_len))
 191                 return 0;
 192
 193         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 194                 return 0;
 195
 196         if (frh->tos && (rule4->tos != frh->tos))
 197                 return 0;
 198
 199 #ifdef CONFIG_IP_ROUTE_CLASSID
 200         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 201                 return 0;
 202 #endif
 203
 204         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 205                 return 0;
 206
 207         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 208                 return 0;
 209
 210         return 1;
 211 }
 212
 213 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 214                           struct fib_rule_hdr *frh)
 215 {
 216         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 217
 218         frh->dst_len = rule4->dst_len;
 219         frh->src_len = rule4->src_len;
 220         frh->tos = rule4->tos;
 221
 222         if (rule4->dst_len)
 223                 NLA_PUT_BE32(skb, FRA_DST, rule4->dst);
 224
 225         if (rule4->src_len)
 226                 NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
 227
 228 #ifdef CONFIG_IP_ROUTE_CLASSID
 229         if (rule4->tclassid)
 230                 NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 231 #endif
 232         return 0;
 233
 234 nla_put_failure:
 235         return -ENOBUFS;
 236 }
 237
 238 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 239 {
 240         return nla_total_size(4) /* dst */
 241                + nla_total_size(4) /* src */
 242                + nla_total_size(4); /* flow */
 243 }
 244
 245 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 246 {
 247         rt_cache_flush(ops->fro_net, -1);
 248 }
 249
 250 static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = {
 251         .family         = AF_INET,
 252         .rule_size      = sizeof(struct fib4_rule),
 253         .addr_size      = sizeof(u32),
 254         .action         = fib4_rule_action,
 255         .match          = fib4_rule_match,
 256         .configure      = fib4_rule_configure,
 257         .compare        = fib4_rule_compare,
 258         .fill           = fib4_rule_fill,
 259         .default_pref   = fib_default_rule_pref,
 260         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 261         .flush_cache    = fib4_rule_flush_cache,
 262         .nlgroup        = RTNLGRP_IPV4_RULE,
 263         .policy         = fib4_rule_policy,
 264         .owner          = THIS_MODULE,
 265 };
 266
 267 static int fib_default_rules_init(struct fib_rules_ops *ops)
 268 {
 269         int err;
 270
 271         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 272         if (err < 0)
 273                 return err;
 274         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 275         if (err < 0)
 276                 return err;
 277         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 278         if (err < 0)
 279                 return err;
 280         return 0;
 281 }
 282
 283 int __net_init fib4_rules_init(struct net *net)
 284 {
 285         int err;
 286         struct fib_rules_ops *ops;
 287
 288         ops = fib_rules_register(&fib4_rules_ops_template, net);
 289         if (IS_ERR(ops))
 290                 return PTR_ERR(ops);
 291
 292         err = fib_default_rules_init(ops);
 293         if (err < 0)
 294                 goto fail;
 295         net->ipv4.rules_ops = ops;
 296         return 0;
 297
 298 fail:
 299         /* also cleans all rules already added */
 300         fib_rules_unregister(ops);
 301         return err;
 302 }
 303
 304 void __net_exit fib4_rules_exit(struct net *net)
 305 {
 306         fib_rules_unregister(net->ipv4.rules_ops);
 307 }