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