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