linux/net/ipv4/fib_rules.c
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   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
  36struct 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
  50int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
  51{
  52        struct fib_lookup_arg arg = {
  53                .result = res,
  54                .flags = FIB_LOOKUP_NOREF,
  55        };
  56        int err;
  57
  58        err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
  59#ifdef CONFIG_IP_ROUTE_CLASSID
  60        if (arg.rule)
  61                res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
  62        else
  63                res->tclassid = 0;
  64#endif
  65        return err;
  66}
  67EXPORT_SYMBOL_GPL(__fib_lookup);
  68
  69static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  70                            int flags, struct fib_lookup_arg *arg)
  71{
  72        int err = -EAGAIN;
  73        struct fib_table *tbl;
  74
  75        switch (rule->action) {
  76        case FR_ACT_TO_TBL:
  77                break;
  78
  79        case FR_ACT_UNREACHABLE:
  80                err = -ENETUNREACH;
  81                goto errout;
  82
  83        case FR_ACT_PROHIBIT:
  84                err = -EACCES;
  85                goto errout;
  86
  87        case FR_ACT_BLACKHOLE:
  88        default:
  89                err = -EINVAL;
  90                goto errout;
  91        }
  92
  93        tbl = fib_get_table(rule->fr_net, rule->table);
  94        if (!tbl)
  95                goto errout;
  96
  97        err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
  98        if (err > 0)
  99                err = -EAGAIN;
 100errout:
 101        return err;
 102}
 103
 104
 105static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 106{
 107        struct fib4_rule *r = (struct fib4_rule *) rule;
 108        struct flowi4 *fl4 = &fl->u.ip4;
 109        __be32 daddr = fl4->daddr;
 110        __be32 saddr = fl4->saddr;
 111
 112        if (((saddr ^ r->src) & r->srcmask) ||
 113            ((daddr ^ r->dst) & r->dstmask))
 114                return 0;
 115
 116        if (r->tos && (r->tos != fl4->flowi4_tos))
 117                return 0;
 118
 119        return 1;
 120}
 121
 122static struct fib_table *fib_empty_table(struct net *net)
 123{
 124        u32 id;
 125
 126        for (id = 1; id <= RT_TABLE_MAX; id++)
 127                if (fib_get_table(net, id) == NULL)
 128                        return fib_new_table(net, id);
 129        return NULL;
 130}
 131
 132static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 133        FRA_GENERIC_POLICY,
 134        [FRA_FLOW]      = { .type = NLA_U32 },
 135};
 136
 137static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 138                               struct fib_rule_hdr *frh,
 139                               struct nlattr **tb)
 140{
 141        struct net *net = sock_net(skb->sk);
 142        int err = -EINVAL;
 143        struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 144
 145        if (frh->tos & ~IPTOS_TOS_MASK)
 146                goto errout;
 147
 148        if (rule->table == RT_TABLE_UNSPEC) {
 149                if (rule->action == FR_ACT_TO_TBL) {
 150                        struct fib_table *table;
 151
 152                        table = fib_empty_table(net);
 153                        if (table == NULL) {
 154                                err = -ENOBUFS;
 155                                goto errout;
 156                        }
 157
 158                        rule->table = table->tb_id;
 159                }
 160        }
 161
 162        if (frh->src_len)
 163                rule4->src = nla_get_be32(tb[FRA_SRC]);
 164
 165        if (frh->dst_len)
 166                rule4->dst = nla_get_be32(tb[FRA_DST]);
 167
 168#ifdef CONFIG_IP_ROUTE_CLASSID
 169        if (tb[FRA_FLOW]) {
 170                rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 171                if (rule4->tclassid)
 172                        net->ipv4.fib_num_tclassid_users++;
 173        }
 174#endif
 175
 176        rule4->src_len = frh->src_len;
 177        rule4->srcmask = inet_make_mask(rule4->src_len);
 178        rule4->dst_len = frh->dst_len;
 179        rule4->dstmask = inet_make_mask(rule4->dst_len);
 180        rule4->tos = frh->tos;
 181
 182        net->ipv4.fib_has_custom_rules = true;
 183        err = 0;
 184errout:
 185        return err;
 186}
 187
 188static void fib4_rule_delete(struct fib_rule *rule)
 189{
 190        struct net *net = rule->fr_net;
 191#ifdef CONFIG_IP_ROUTE_CLASSID
 192        struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 193
 194        if (rule4->tclassid)
 195                net->ipv4.fib_num_tclassid_users--;
 196#endif
 197        net->ipv4.fib_has_custom_rules = true;
 198}
 199
 200static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 201                             struct nlattr **tb)
 202{
 203        struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 204
 205        if (frh->src_len && (rule4->src_len != frh->src_len))
 206                return 0;
 207
 208        if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 209                return 0;
 210
 211        if (frh->tos && (rule4->tos != frh->tos))
 212                return 0;
 213
 214#ifdef CONFIG_IP_ROUTE_CLASSID
 215        if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 216                return 0;
 217#endif
 218
 219        if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 220                return 0;
 221
 222        if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 223                return 0;
 224
 225        return 1;
 226}
 227
 228static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 229                          struct fib_rule_hdr *frh)
 230{
 231        struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 232
 233        frh->dst_len = rule4->dst_len;
 234        frh->src_len = rule4->src_len;
 235        frh->tos = rule4->tos;
 236
 237        if ((rule4->dst_len &&
 238             nla_put_be32(skb, FRA_DST, rule4->dst)) ||
 239            (rule4->src_len &&
 240             nla_put_be32(skb, FRA_SRC, rule4->src)))
 241                goto nla_put_failure;
 242#ifdef CONFIG_IP_ROUTE_CLASSID
 243        if (rule4->tclassid &&
 244            nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
 245                goto nla_put_failure;
 246#endif
 247        return 0;
 248
 249nla_put_failure:
 250        return -ENOBUFS;
 251}
 252
 253static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 254{
 255        return nla_total_size(4) /* dst */
 256               + nla_total_size(4) /* src */
 257               + nla_total_size(4); /* flow */
 258}
 259
 260static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
 261{
 262        rt_cache_flush(ops->fro_net);
 263}
 264
 265static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = {
 266        .family         = AF_INET,
 267        .rule_size      = sizeof(struct fib4_rule),
 268        .addr_size      = sizeof(u32),
 269        .action         = fib4_rule_action,
 270        .match          = fib4_rule_match,
 271        .configure      = fib4_rule_configure,
 272        .delete         = fib4_rule_delete,
 273        .compare        = fib4_rule_compare,
 274        .fill           = fib4_rule_fill,
 275        .default_pref   = fib_default_rule_pref,
 276        .nlmsg_payload  = fib4_rule_nlmsg_payload,
 277        .flush_cache    = fib4_rule_flush_cache,
 278        .nlgroup        = RTNLGRP_IPV4_RULE,
 279        .policy         = fib4_rule_policy,
 280        .owner          = THIS_MODULE,
 281};
 282
 283static int fib_default_rules_init(struct fib_rules_ops *ops)
 284{
 285        int err;
 286
 287        err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
 288        if (err < 0)
 289                return err;
 290        err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
 291        if (err < 0)
 292                return err;
 293        err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
 294        if (err < 0)
 295                return err;
 296        return 0;
 297}
 298
 299int __net_init fib4_rules_init(struct net *net)
 300{
 301        int err;
 302        struct fib_rules_ops *ops;
 303
 304        ops = fib_rules_register(&fib4_rules_ops_template, net);
 305        if (IS_ERR(ops))
 306                return PTR_ERR(ops);
 307
 308        err = fib_default_rules_init(ops);
 309        if (err < 0)
 310                goto fail;
 311        net->ipv4.rules_ops = ops;
 312        net->ipv4.fib_has_custom_rules = false;
 313        return 0;
 314
 315fail:
 316        /* also cleans all rules already added */
 317        fib_rules_unregister(ops);
 318        return err;
 319}
 320
 321void __net_exit fib4_rules_exit(struct net *net)
 322{
 323        fib_rules_unregister(net->ipv4.rules_ops);
 324}
 325
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