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