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