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 <linux/export.h>
  30 #include <net/ip.h>
  31 #include <net/route.h>
  32 #include <net/tcp.h>
  33 #include <net/ip_fib.h>
  34 #include <net/fib_rules.h>
  35
  36 struct fib4_rule {
  37         struct fib_rule         common;
  38         u8                      dst_len;
  39         u8                      src_len;
  40         u8                      tos;
  41         __be32                  src;
  42         __be32                  srcmask;
  43         __be32                  dst;
  44         __be32                  dstmask;
  45 #ifdef CONFIG_IP_ROUTE_CLASSID
  46         u32                     tclassid;
  47 #endif
  48 };
  49
  50 #ifdef CONFIG_IP_ROUTE_CLASSID
  51 u32 fib_rules_tclass(const struct fib_result *res)
  52 {
  53         return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
  54 }
  55 #endif
  56
  57 int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
  58 {
  59         struct fib_lookup_arg arg = {
  60                 .result = res,
  61                 .flags = FIB_LOOKUP_NOREF,
  62         };
  63         int err;
  64
  65         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
  66         res->r = arg.rule;
  67
  68         return err;
  69 }
  70
  71 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  72                             int flags, struct fib_lookup_arg *arg)
  73 {
  74         int err = -EAGAIN;
  75         struct fib_table *tbl;
  76
  77         switch (rule->action) {
  78         case FR_ACT_TO_TBL:
  79                 break;
  80
  81         case FR_ACT_UNREACHABLE:
  82                 err = -ENETUNREACH;
  83                 goto errout;
  84
  85         case FR_ACT_PROHIBIT:
  86                 err = -EACCES;
  87                 goto errout;
  88
  89         case FR_ACT_BLACKHOLE:
  90         default:
  91                 err = -EINVAL;
  92                 goto errout;
  93         }
  94
  95         tbl = fib_get_table(rule->fr_net, rule->table);
  96         if (!tbl)
  97                 goto errout;
  98
  99         err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
 100         if (err > 0)
 101                 err = -EAGAIN;
 102 errout:
 103         return err;
 104 }
 105
 106
 107 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 108 {
 109         struct fib4_rule *r = (struct fib4_rule *) rule;
 110         struct flowi4 *fl4 = &fl->u.ip4;
 111         __be32 daddr = fl4->daddr;
 112         __be32 saddr = fl4->saddr;
 113
 114         if (((saddr ^ r->src) & r->srcmask) ||
 115             ((daddr ^ r->dst) & r->dstmask))
 116                 return 0;
 117
 118         if (r->tos && (r->tos != fl4->flowi4_tos))
 119                 return 0;
 120
 121         return 1;
 122 }
 123
 124 static struct fib_table *fib_empty_table(struct net *net)
 125 {
 126         u32 id;
 127
 128         for (id = 1; id <= RT_TABLE_MAX; id++)
 129                 if (fib_get_table(net, id) == NULL)
 130                         return fib_new_table(net, id);
 131         return NULL;
 132 }
 133
 134 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 135         FRA_GENERIC_POLICY,
 136         [FRA_FLOW]      = { .type = NLA_U32 },
 137 };
 138
 139 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 140                                struct fib_rule_hdr *frh,
 141                                struct nlattr **tb)
 142 {
 143         struct net *net = sock_net(skb->sk);
 144         int err = -EINVAL;
 145         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 146
 147         if (frh->tos & ~IPTOS_TOS_MASK)
 148                 goto errout;
 149
 150         if (rule->table == RT_TABLE_UNSPEC) {
 151                 if (rule->action == FR_ACT_TO_TBL) {
 152                         struct fib_table *table;
 153
 154                         table = fib_empty_table(net);
 155                         if (table == NULL) {
 156                                 err = -ENOBUFS;
 157                                 goto errout;
 158                         }
 159
 160                         rule->table = table->tb_id;
 161                 }
 162         }
 163
 164         if (frh->src_len)
 165                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 166
 167         if (frh->dst_len)
 168                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 169
 170 #ifdef CONFIG_IP_ROUTE_CLASSID
 171         if (tb[FRA_FLOW])
 172                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 173 #endif
 174
 175         rule4->src_len = frh->src_len;
 176         rule4->srcmask = inet_make_mask(rule4->src_len);
 177         rule4->dst_len = frh->dst_len;
 178         rule4->dstmask = inet_make_mask(rule4->dst_len);
 179         rule4->tos = frh->tos;
 180
 181         err = 0;
 182 errout:
 183         return err;
 184 }
 185
 186 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 187                              struct nlattr **tb)
 188 {
 189         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 190
 191         if (frh->src_len && (rule4->src_len != frh->src_len))
 192                 return 0;
 193
 194         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 195                 return 0;
 196
 197         if (frh->tos && (rule4->tos != frh->tos))
 198                 return 0;
 199
 200 #ifdef CONFIG_IP_ROUTE_CLASSID
 201         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 202                 return 0;
 203 #endif
 204
 205         if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 206                 return 0;
 207
 208         if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 209                 return 0;
 210
 211         return 1;
 212 }
 213
 214 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 215                           struct fib_rule_hdr *frh)
 216 {
 217         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 218
 219         frh->dst_len = rule4->dst_len;
 220         frh->src_len = rule4->src_len;
 221         frh->tos = rule4->tos;
 222
 223         if (rule4->dst_len)
 224                 NLA_PUT_BE32(skb, FRA_DST, rule4->dst);
 225
 226         if (rule4->src_len)
 227                 NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
 228
 229 #ifdef CONFIG_IP_ROUTE_CLASSID
 230         if (rule4->tclassid)
 231                 NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 232 #endif
 233         return 0;
 234
 235 nla_put_failure:
 236         return -ENOBUFS;
 237 }
 238
 239 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 240 {
 241         return nla_total_size(4) /* dst */
 242                + nla_total_size(4) /* src */
 243                + nla_total_size(4); /* flow */
 244 }
 245
 246 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 247 {
 248         rt_cache_flush(ops->fro_net, -1);
 249 }
 250
 251 static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = {
 252         .family         = AF_INET,
 253         .rule_size      = sizeof(struct fib4_rule),
 254         .addr_size      = sizeof(u32),
 255         .action         = fib4_rule_action,
 256         .match          = fib4_rule_match,
 257         .configure      = fib4_rule_configure,
 258         .compare        = fib4_rule_compare,
 259         .fill           = fib4_rule_fill,
 260         .default_pref   = fib_default_rule_pref,
 261         .nlmsg_payload  = fib4_rule_nlmsg_payload,
 262         .flush_cache    = fib4_rule_flush_cache,
 263         .nlgroup        = RTNLGRP_IPV4_RULE,
 264         .policy         = fib4_rule_policy,
 265         .owner          = THIS_MODULE,
 266 };
 267
 268 static int fib_default_rules_init(struct fib_rules_ops *ops)
 269 {
 270         int err;
 271
 272         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 273         if (err < 0)
 274                 return err;
 275         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 276         if (err < 0)
 277                 return err;
 278         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 279         if (err < 0)
 280                 return err;
 281         return 0;
 282 }
 283
 284 int __net_init fib4_rules_init(struct net *net)
 285 {
 286         int err;
 287         struct fib_rules_ops *ops;
 288
 289         ops = fib_rules_register(&fib4_rules_ops_template, net);
 290         if (IS_ERR(ops))
 291                 return PTR_ERR(ops);
 292
 293         err = fib_default_rules_init(ops);
 294         if (err < 0)
 295                 goto fail;
 296         net->ipv4.rules_ops = ops;
 297         return 0;
 298
 299 fail:
 300         /* also cleans all rules already added */
 301         fib_rules_unregister(ops);
 302         return err;
 303 }
 304
 305 void __net_exit fib4_rules_exit(struct net *net)
 306 {
 307         fib_rules_unregister(net->ipv4.rules_ops);
 308 }