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 static bool fib4_rule_matchall(const struct fib_rule *rule) 51 { 52 struct fib4_rule *r = container_of(rule, struct fib4_rule, common); 53 54 if (r->dst_len || r->src_len || r->tos) 55 return false; 56 return fib_rule_matchall(rule); 57 } 58 59 bool fib4_rule_default(const struct fib_rule *rule) 60 { 61 if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL || 62 rule->l3mdev) 63 return false; 64 if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN && 65 rule->table != RT_TABLE_DEFAULT) 66 return false; 67 return true; 68 } 69 EXPORT_SYMBOL_GPL(fib4_rule_default); 70 71 int __fib_lookup(struct net *net, struct flowi4 *flp, 72 struct fib_result *res, unsigned int flags) 73 { 74 struct fib_lookup_arg arg = { 75 .result = res, 76 .flags = flags, 77 }; 78 int err; 79 80 /* update flow if oif or iif point to device enslaved to l3mdev */ 81 l3mdev_update_flow(net, flowi4_to_flowi(flp)); 82 83 err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg); 84 #ifdef CONFIG_IP_ROUTE_CLASSID 85 if (arg.rule) 86 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid; 87 else 88 res->tclassid = 0; 89 #endif 90 91 if (err == -ESRCH) 92 err = -ENETUNREACH; 93 94 return err; 95 } 96 EXPORT_SYMBOL_GPL(__fib_lookup); 97 98 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp, 99 int flags, struct fib_lookup_arg *arg) 100 { 101 int err = -EAGAIN; 102 struct fib_table *tbl; 103 u32 tb_id; 104 105 switch (rule->action) { 106 case FR_ACT_TO_TBL: 107 break; 108 109 case FR_ACT_UNREACHABLE: 110 return -ENETUNREACH; 111 112 case FR_ACT_PROHIBIT: 113 return -EACCES; 114 115 case FR_ACT_BLACKHOLE: 116 default: 117 return -EINVAL; 118 } 119 120 rcu_read_lock(); 121 122 tb_id = fib_rule_get_table(rule, arg); 123 tbl = fib_get_table(rule->fr_net, tb_id); 124 if (tbl) 125 err = fib_table_lookup(tbl, &flp->u.ip4, 126 (struct fib_result *)arg->result, 127 arg->flags); 128 129 rcu_read_unlock(); 130 return err; 131 } 132 133 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg) 134 { 135 struct fib_result *result = (struct fib_result *) arg->result; 136 struct net_device *dev = NULL; 137 138 if (result->fi) 139 dev = result->fi->fib_dev; 140 141 /* do not accept result if the route does 142 * not meet the required prefix length 143 */ 144 if (result->prefixlen <= rule->suppress_prefixlen) 145 goto suppress_route; 146 147 /* do not accept result if the route uses a device 148 * belonging to a forbidden interface group 149 */ 150 if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup) 151 goto suppress_route; 152 153 return false; 154 155 suppress_route: 156 if (!(arg->flags & FIB_LOOKUP_NOREF)) 157 fib_info_put(result->fi); 158 return true; 159 } 160 161 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags) 162 { 163 struct fib4_rule *r = (struct fib4_rule *) rule; 164 struct flowi4 *fl4 = &fl->u.ip4; 165 __be32 daddr = fl4->daddr; 166 __be32 saddr = fl4->saddr; 167 168 if (((saddr ^ r->src) & r->srcmask) || 169 ((daddr ^ r->dst) & r->dstmask)) 170 return 0; 171 172 if (r->tos && (r->tos != fl4->flowi4_tos)) 173 return 0; 174 175 return 1; 176 } 177 178 static struct fib_table *fib_empty_table(struct net *net) 179 { 180 u32 id; 181 182 for (id = 1; id <= RT_TABLE_MAX; id++) 183 if (!fib_get_table(net, id)) 184 return fib_new_table(net, id); 185 return NULL; 186 } 187 188 static int call_fib_rule_notifier(struct notifier_block *nb, struct net *net, 189 enum fib_event_type event_type, 190 struct fib_rule *rule) 191 { 192 struct fib_rule_notifier_info info = { 193 .rule = rule, 194 }; 195 196 return call_fib_notifier(nb, net, event_type, &info.info); 197 } 198 199 static int call_fib_rule_notifiers(struct net *net, 200 enum fib_event_type event_type, 201 struct fib_rule *rule) 202 { 203 struct fib_rule_notifier_info info = { 204 .rule = rule, 205 }; 206 207 return call_fib_notifiers(net, event_type, &info.info); 208 } 209 210 /* Called with rcu_read_lock() */ 211 void fib_rules_notify(struct net *net, struct notifier_block *nb) 212 { 213 struct fib_rules_ops *ops = net->ipv4.rules_ops; 214 struct fib_rule *rule; 215 216 list_for_each_entry_rcu(rule, &ops->rules_list, list) 217 call_fib_rule_notifier(nb, net, FIB_EVENT_RULE_ADD, rule); 218 } 219 220 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = { 221 FRA_GENERIC_POLICY, 222 [FRA_FLOW] = { .type = NLA_U32 }, 223 }; 224 225 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb, 226 struct fib_rule_hdr *frh, 227 struct nlattr **tb) 228 { 229 struct net *net = sock_net(skb->sk); 230 int err = -EINVAL; 231 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 232 233 if (frh->tos & ~IPTOS_TOS_MASK) 234 goto errout; 235 236 /* split local/main if they are not already split */ 237 err = fib_unmerge(net); 238 if (err) 239 goto errout; 240 241 if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) { 242 if (rule->action == FR_ACT_TO_TBL) { 243 struct fib_table *table; 244 245 table = fib_empty_table(net); 246 if (!table) { 247 err = -ENOBUFS; 248 goto errout; 249 } 250 251 rule->table = table->tb_id; 252 } 253 } 254 255 if (frh->src_len) 256 rule4->src = nla_get_in_addr(tb[FRA_SRC]); 257 258 if (frh->dst_len) 259 rule4->dst = nla_get_in_addr(tb[FRA_DST]); 260 261 #ifdef CONFIG_IP_ROUTE_CLASSID 262 if (tb[FRA_FLOW]) { 263 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]); 264 if (rule4->tclassid) 265 net->ipv4.fib_num_tclassid_users++; 266 } 267 #endif 268 269 rule4->src_len = frh->src_len; 270 rule4->srcmask = inet_make_mask(rule4->src_len); 271 rule4->dst_len = frh->dst_len; 272 rule4->dstmask = inet_make_mask(rule4->dst_len); 273 rule4->tos = frh->tos; 274 275 net->ipv4.fib_has_custom_rules = true; 276 call_fib_rule_notifiers(net, FIB_EVENT_RULE_ADD, rule); 277 278 err = 0; 279 errout: 280 return err; 281 } 282 283 static int fib4_rule_delete(struct fib_rule *rule) 284 { 285 struct net *net = rule->fr_net; 286 int err; 287 288 /* split local/main if they are not already split */ 289 err = fib_unmerge(net); 290 if (err) 291 goto errout; 292 293 #ifdef CONFIG_IP_ROUTE_CLASSID 294 if (((struct fib4_rule *)rule)->tclassid) 295 net->ipv4.fib_num_tclassid_users--; 296 #endif 297 net->ipv4.fib_has_custom_rules = true; 298 call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL, rule); 299 errout: 300 return err; 301 } 302 303 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh, 304 struct nlattr **tb) 305 { 306 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 307 308 if (frh->src_len && (rule4->src_len != frh->src_len)) 309 return 0; 310 311 if (frh->dst_len && (rule4->dst_len != frh->dst_len)) 312 return 0; 313 314 if (frh->tos && (rule4->tos != frh->tos)) 315 return 0; 316 317 #ifdef CONFIG_IP_ROUTE_CLASSID 318 if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW]))) 319 return 0; 320 #endif 321 322 if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC]))) 323 return 0; 324 325 if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST]))) 326 return 0; 327 328 return 1; 329 } 330 331 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb, 332 struct fib_rule_hdr *frh) 333 { 334 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 335 336 frh->dst_len = rule4->dst_len; 337 frh->src_len = rule4->src_len; 338 frh->tos = rule4->tos; 339 340 if ((rule4->dst_len && 341 nla_put_in_addr(skb, FRA_DST, rule4->dst)) || 342 (rule4->src_len && 343 nla_put_in_addr(skb, FRA_SRC, rule4->src))) 344 goto nla_put_failure; 345 #ifdef CONFIG_IP_ROUTE_CLASSID 346 if (rule4->tclassid && 347 nla_put_u32(skb, FRA_FLOW, rule4->tclassid)) 348 goto nla_put_failure; 349 #endif 350 return 0; 351 352 nla_put_failure: 353 return -ENOBUFS; 354 } 355 356 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule) 357 { 358 return nla_total_size(4) /* dst */ 359 + nla_total_size(4) /* src */ 360 + nla_total_size(4); /* flow */ 361 } 362 363 static void fib4_rule_flush_cache(struct fib_rules_ops *ops) 364 { 365 rt_cache_flush(ops->fro_net); 366 } 367 368 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = { 369 .family = AF_INET, 370 .rule_size = sizeof(struct fib4_rule), 371 .addr_size = sizeof(u32), 372 .action = fib4_rule_action, 373 .suppress = fib4_rule_suppress, 374 .match = fib4_rule_match, 375 .configure = fib4_rule_configure, 376 .delete = fib4_rule_delete, 377 .compare = fib4_rule_compare, 378 .fill = fib4_rule_fill, 379 .nlmsg_payload = fib4_rule_nlmsg_payload, 380 .flush_cache = fib4_rule_flush_cache, 381 .nlgroup = RTNLGRP_IPV4_RULE, 382 .policy = fib4_rule_policy, 383 .owner = THIS_MODULE, 384 }; 385 386 static int fib_default_rules_init(struct fib_rules_ops *ops) 387 { 388 int err; 389 390 err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0); 391 if (err < 0) 392 return err; 393 err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0); 394 if (err < 0) 395 return err; 396 err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0); 397 if (err < 0) 398 return err; 399 return 0; 400 } 401 402 int __net_init fib4_rules_init(struct net *net) 403 { 404 int err; 405 struct fib_rules_ops *ops; 406 407 ops = fib_rules_register(&fib4_rules_ops_template, net); 408 if (IS_ERR(ops)) 409 return PTR_ERR(ops); 410 411 err = fib_default_rules_init(ops); 412 if (err < 0) 413 goto fail; 414 net->ipv4.rules_ops = ops; 415 net->ipv4.fib_has_custom_rules = false; 416 return 0; 417 418 fail: 419 /* also cleans all rules already added */ 420 fib_rules_unregister(ops); 421 return err; 422 } 423 424 void __net_exit fib4_rules_exit(struct net *net) 425 { 426 fib_rules_unregister(net->ipv4.rules_ops); 427 } 428