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