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 static struct fib_rules_ops fib4_rules_ops;
  36
  37 struct fib4_rule
  38 {
  39         struct fib_rule         common;
  40         u8                      dst_len;
  41         u8                      src_len;
  42         u8                      tos;
  43         __be32                  src;
  44         __be32                  srcmask;
  45         __be32                  dst;
  46         __be32                  dstmask;
  47 #ifdef CONFIG_IP_ROUTE_FWMARK
  48         u32                     fwmark;
  49         u32                     fwmask;
  50 #endif
  51 #ifdef CONFIG_NET_CLS_ROUTE
  52         u32                     tclassid;
  53 #endif
  54 };
  55
  56 static struct fib4_rule default_rule = {
  57         .common = {
  58                 .refcnt =       ATOMIC_INIT(2),
  59                 .pref =         0x7FFF,
  60                 .table =        RT_TABLE_DEFAULT,
  61                 .action =       FR_ACT_TO_TBL,
  62         },
  63 };
  64
  65 static struct fib4_rule main_rule = {
  66         .common = {
  67                 .refcnt =       ATOMIC_INIT(2),
  68                 .pref =         0x7FFE,
  69                 .table =        RT_TABLE_MAIN,
  70                 .action =       FR_ACT_TO_TBL,
  71         },
  72 };
  73
  74 static struct fib4_rule local_rule = {
  75         .common = {
  76                 .refcnt =       ATOMIC_INIT(2),
  77                 .table =        RT_TABLE_LOCAL,
  78                 .action =       FR_ACT_TO_TBL,
  79                 .flags =        FIB_RULE_PERMANENT,
  80         },
  81 };
  82
  83 static LIST_HEAD(fib4_rules);
  84
  85 #ifdef CONFIG_NET_CLS_ROUTE
  86 u32 fib_rules_tclass(struct fib_result *res)
  87 {
  88         return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
  89 }
  90 #endif
  91
  92 int fib_lookup(struct flowi *flp, struct fib_result *res)
  93 {
  94         struct fib_lookup_arg arg = {
  95                 .result = res,
  96         };
  97         int err;
  98
  99         err = fib_rules_lookup(&fib4_rules_ops, flp, 0, &arg);
 100         res->r = arg.rule;
 101
 102         return err;
 103 }
 104
 105 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
 106                             int flags, struct fib_lookup_arg *arg)
 107 {
 108         int err = -EAGAIN;
 109         struct fib_table *tbl;
 110
 111         switch (rule->action) {
 112         case FR_ACT_TO_TBL:
 113                 break;
 114
 115         case FR_ACT_UNREACHABLE:
 116                 err = -ENETUNREACH;
 117                 goto errout;
 118
 119         case FR_ACT_PROHIBIT:
 120                 err = -EACCES;
 121                 goto errout;
 122
 123         case FR_ACT_BLACKHOLE:
 124         default:
 125                 err = -EINVAL;
 126                 goto errout;
 127         }
 128
 129         if ((tbl = fib_get_table(rule->table)) == NULL)
 130                 goto errout;
 131
 132         err = tbl->tb_lookup(tbl, flp, (struct fib_result *) arg->result);
 133         if (err > 0)
 134                 err = -EAGAIN;
 135 errout:
 136         return err;
 137 }
 138
 139
 140 void fib_select_default(const struct flowi *flp, struct fib_result *res)
 141 {
 142         if (res->r && res->r->action == FR_ACT_TO_TBL &&
 143             FIB_RES_GW(*res) && FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK) {
 144                 struct fib_table *tb;
 145                 if ((tb = fib_get_table(res->r->table)) != NULL)
 146                         tb->tb_select_default(tb, flp, res);
 147         }
 148 }
 149
 150 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 151 {
 152         struct fib4_rule *r = (struct fib4_rule *) rule;
 153         __be32 daddr = fl->fl4_dst;
 154         __be32 saddr = fl->fl4_src;
 155
 156         if (((saddr ^ r->src) & r->srcmask) ||
 157             ((daddr ^ r->dst) & r->dstmask))
 158                 return 0;
 159
 160         if (r->tos && (r->tos != fl->fl4_tos))
 161                 return 0;
 162
 163 #ifdef CONFIG_IP_ROUTE_FWMARK
 164         if ((r->fwmark ^ fl->fl4_fwmark) & r->fwmask)
 165                 return 0;
 166 #endif
 167
 168         return 1;
 169 }
 170
 171 static struct fib_table *fib_empty_table(void)
 172 {
 173         u32 id;
 174
 175         for (id = 1; id <= RT_TABLE_MAX; id++)
 176                 if (fib_get_table(id) == NULL)
 177                         return fib_new_table(id);
 178         return NULL;
 179 }
 180
 181 static struct nla_policy fib4_rule_policy[FRA_MAX+1] __read_mostly = {
 182         [FRA_IFNAME]    = { .type = NLA_STRING, .len = IFNAMSIZ - 1 },
 183         [FRA_PRIORITY]  = { .type = NLA_U32 },
 184         [FRA_SRC]       = { .type = NLA_U32 },
 185         [FRA_DST]       = { .type = NLA_U32 },
 186         [FRA_FWMARK]    = { .type = NLA_U32 },
 187         [FRA_FWMASK]    = { .type = NLA_U32 },
 188         [FRA_FLOW]      = { .type = NLA_U32 },
 189         [FRA_TABLE]     = { .type = NLA_U32 },
 190 };
 191
 192 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 193                                struct nlmsghdr *nlh, struct fib_rule_hdr *frh,
 194                                struct nlattr **tb)
 195 {
 196         int err = -EINVAL;
 197         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 198
 199         if (frh->src_len > 32 || frh->dst_len > 32 ||
 200             (frh->tos & ~IPTOS_TOS_MASK))
 201                 goto errout;
 202
 203         if (rule->table == RT_TABLE_UNSPEC) {
 204                 if (rule->action == FR_ACT_TO_TBL) {
 205                         struct fib_table *table;
 206
 207                         table = fib_empty_table();
 208                         if (table == NULL) {
 209                                 err = -ENOBUFS;
 210                                 goto errout;
 211                         }
 212
 213                         rule->table = table->tb_id;
 214                 }
 215         }
 216
 217         if (tb[FRA_SRC])
 218                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 219
 220         if (tb[FRA_DST])
 221                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 222
 223 #ifdef CONFIG_IP_ROUTE_FWMARK
 224         if (tb[FRA_FWMARK]) {
 225                 rule4->fwmark = nla_get_u32(tb[FRA_FWMARK]);
 226                 if (rule4->fwmark)
 227                         /* compatibility: if the mark value is non-zero all bits
 228                          * are compared unless a mask is explicitly specified.
 229                          */
 230                         rule4->fwmask = 0xFFFFFFFF;
 231         }
 232
 233         if (tb[FRA_FWMASK])
 234                 rule4->fwmask = nla_get_u32(tb[FRA_FWMASK]);
 235 #endif
 236
 237 #ifdef CONFIG_NET_CLS_ROUTE
 238         if (tb[FRA_FLOW])
 239                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 240 #endif
 241
 242         rule4->src_len = frh->src_len;
 243         rule4->srcmask = inet_make_mask(rule4->src_len);
 244         rule4->dst_len = frh->dst_len;
 245         rule4->dstmask = inet_make_mask(rule4->dst_len);
 246         rule4->tos = frh->tos;
 247
 248         err = 0;
 249 errout:
 250         return err;
 251 }
 252
 253 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 254                              struct nlattr **tb)
 255 {
 256         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 257
 258         if (frh->src_len && (rule4->src_len != frh->src_len))
 259                 return 0;
 260
 261         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
 262                 return 0;
 263
 264         if (frh->tos && (rule4->tos != frh->tos))
 265                 return 0;
 266
 267 #ifdef CONFIG_IP_ROUTE_FWMARK
 268         if (tb[FRA_FWMARK] && (rule4->fwmark != nla_get_u32(tb[FRA_FWMARK])))
 269                 return 0;
 270
 271         if (tb[FRA_FWMASK] && (rule4->fwmask != nla_get_u32(tb[FRA_FWMASK])))
 272                 return 0;
 273 #endif
 274
 275 #ifdef CONFIG_NET_CLS_ROUTE
 276         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
 277                 return 0;
 278 #endif
 279
 280         if (tb[FRA_SRC] && (rule4->src != nla_get_be32(tb[FRA_SRC])))
 281                 return 0;
 282
 283         if (tb[FRA_DST] && (rule4->dst != nla_get_be32(tb[FRA_DST])))
 284                 return 0;
 285
 286         return 1;
 287 }
 288
 289 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
 290                           struct nlmsghdr *nlh, struct fib_rule_hdr *frh)
 291 {
 292         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 293
 294         frh->family = AF_INET;
 295         frh->dst_len = rule4->dst_len;
 296         frh->src_len = rule4->src_len;
 297         frh->tos = rule4->tos;
 298
 299 #ifdef CONFIG_IP_ROUTE_FWMARK
 300         if (rule4->fwmark)
 301                 NLA_PUT_U32(skb, FRA_FWMARK, rule4->fwmark);
 302
 303         if (rule4->fwmask || rule4->fwmark)
 304                 NLA_PUT_U32(skb, FRA_FWMASK, rule4->fwmask);
 305 #endif
 306
 307         if (rule4->dst_len)
 308                 NLA_PUT_BE32(skb, FRA_DST, rule4->dst);
 309
 310         if (rule4->src_len)
 311                 NLA_PUT_BE32(skb, FRA_SRC, rule4->src);
 312
 313 #ifdef CONFIG_NET_CLS_ROUTE
 314         if (rule4->tclassid)
 315                 NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 316 #endif
 317         return 0;
 318
 319 nla_put_failure:
 320         return -ENOBUFS;
 321 }
 322
 323 int fib4_rules_dump(struct sk_buff *skb, struct netlink_callback *cb)
 324 {
 325         return fib_rules_dump(skb, cb, AF_INET);
 326 }
 327
 328 static u32 fib4_rule_default_pref(void)
 329 {
 330         struct list_head *pos;
 331         struct fib_rule *rule;
 332
 333         if (!list_empty(&fib4_rules)) {
 334                 pos = fib4_rules.next;
 335                 if (pos->next != &fib4_rules) {
 336                         rule = list_entry(pos->next, struct fib_rule, list);
 337                         if (rule->pref)
 338                                 return rule->pref - 1;
 339                 }
 340         }
 341
 342         return 0;
 343 }
 344
 345 static struct fib_rules_ops fib4_rules_ops = {
 346         .family         = AF_INET,
 347         .rule_size      = sizeof(struct fib4_rule),
 348         .action         = fib4_rule_action,
 349         .match          = fib4_rule_match,
 350         .configure      = fib4_rule_configure,
 351         .compare        = fib4_rule_compare,
 352         .fill           = fib4_rule_fill,
 353         .default_pref   = fib4_rule_default_pref,
 354         .nlgroup        = RTNLGRP_IPV4_RULE,
 355         .policy         = fib4_rule_policy,
 356         .rules_list     = &fib4_rules,
 357         .owner          = THIS_MODULE,
 358 };
 359
 360 void __init fib4_rules_init(void)
 361 {
 362         list_add_tail(&local_rule.common.list, &fib4_rules);
 363         list_add_tail(&main_rule.common.list, &fib4_rules);
 364         list_add_tail(&default_rule.common.list, &fib4_rules);
 365
 366         fib_rules_register(&fib4_rules_ops);
 367 }