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 const struct nla_policy fib4_rule_policy[FRA_MAX+1] = { 168 FRA_GENERIC_POLICY, 169 [FRA_FLOW] = { .type = NLA_U32 }, 170 }; 171 172 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb, 173 struct fib_rule_hdr *frh, 174 struct nlattr **tb) 175 { 176 struct net *net = sock_net(skb->sk); 177 int err = -EINVAL; 178 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 179 180 if (frh->tos & ~IPTOS_TOS_MASK) 181 goto errout; 182 183 /* split local/main if they are not already split */ 184 err = fib_unmerge(net); 185 if (err) 186 goto errout; 187 188 if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) { 189 if (rule->action == FR_ACT_TO_TBL) { 190 struct fib_table *table; 191 192 table = fib_empty_table(net); 193 if (!table) { 194 err = -ENOBUFS; 195 goto errout; 196 } 197 198 rule->table = table->tb_id; 199 } 200 } 201 202 if (frh->src_len) 203 rule4->src = nla_get_in_addr(tb[FRA_SRC]); 204 205 if (frh->dst_len) 206 rule4->dst = nla_get_in_addr(tb[FRA_DST]); 207 208 #ifdef CONFIG_IP_ROUTE_CLASSID 209 if (tb[FRA_FLOW]) { 210 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]); 211 if (rule4->tclassid) 212 net->ipv4.fib_num_tclassid_users++; 213 } 214 #endif 215 216 rule4->src_len = frh->src_len; 217 rule4->srcmask = inet_make_mask(rule4->src_len); 218 rule4->dst_len = frh->dst_len; 219 rule4->dstmask = inet_make_mask(rule4->dst_len); 220 rule4->tos = frh->tos; 221 222 net->ipv4.fib_has_custom_rules = true; 223 fib_flush_external(rule->fr_net); 224 225 err = 0; 226 errout: 227 return err; 228 } 229 230 static int fib4_rule_delete(struct fib_rule *rule) 231 { 232 struct net *net = rule->fr_net; 233 int err; 234 235 /* split local/main if they are not already split */ 236 err = fib_unmerge(net); 237 if (err) 238 goto errout; 239 240 #ifdef CONFIG_IP_ROUTE_CLASSID 241 if (((struct fib4_rule *)rule)->tclassid) 242 net->ipv4.fib_num_tclassid_users--; 243 #endif 244 net->ipv4.fib_has_custom_rules = true; 245 fib_flush_external(rule->fr_net); 246 errout: 247 return err; 248 } 249 250 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh, 251 struct nlattr **tb) 252 { 253 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 254 255 if (frh->src_len && (rule4->src_len != frh->src_len)) 256 return 0; 257 258 if (frh->dst_len && (rule4->dst_len != frh->dst_len)) 259 return 0; 260 261 if (frh->tos && (rule4->tos != frh->tos)) 262 return 0; 263 264 #ifdef CONFIG_IP_ROUTE_CLASSID 265 if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW]))) 266 return 0; 267 #endif 268 269 if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC]))) 270 return 0; 271 272 if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST]))) 273 return 0; 274 275 return 1; 276 } 277 278 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb, 279 struct fib_rule_hdr *frh) 280 { 281 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 282 283 frh->dst_len = rule4->dst_len; 284 frh->src_len = rule4->src_len; 285 frh->tos = rule4->tos; 286 287 if ((rule4->dst_len && 288 nla_put_in_addr(skb, FRA_DST, rule4->dst)) || 289 (rule4->src_len && 290 nla_put_in_addr(skb, FRA_SRC, rule4->src))) 291 goto nla_put_failure; 292 #ifdef CONFIG_IP_ROUTE_CLASSID 293 if (rule4->tclassid && 294 nla_put_u32(skb, FRA_FLOW, rule4->tclassid)) 295 goto nla_put_failure; 296 #endif 297 return 0; 298 299 nla_put_failure: 300 return -ENOBUFS; 301 } 302 303 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule) 304 { 305 return nla_total_size(4) /* dst */ 306 + nla_total_size(4) /* src */ 307 + nla_total_size(4); /* flow */ 308 } 309 310 static void fib4_rule_flush_cache(struct fib_rules_ops *ops) 311 { 312 rt_cache_flush(ops->fro_net); 313 } 314 315 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = { 316 .family = AF_INET, 317 .rule_size = sizeof(struct fib4_rule), 318 .addr_size = sizeof(u32), 319 .action = fib4_rule_action, 320 .suppress = fib4_rule_suppress, 321 .match = fib4_rule_match, 322 .configure = fib4_rule_configure, 323 .delete = fib4_rule_delete, 324 .compare = fib4_rule_compare, 325 .fill = fib4_rule_fill, 326 .nlmsg_payload = fib4_rule_nlmsg_payload, 327 .flush_cache = fib4_rule_flush_cache, 328 .nlgroup = RTNLGRP_IPV4_RULE, 329 .policy = fib4_rule_policy, 330 .owner = THIS_MODULE, 331 }; 332 333 static int fib_default_rules_init(struct fib_rules_ops *ops) 334 { 335 int err; 336 337 err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0); 338 if (err < 0) 339 return err; 340 err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0); 341 if (err < 0) 342 return err; 343 err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0); 344 if (err < 0) 345 return err; 346 return 0; 347 } 348 349 int __net_init fib4_rules_init(struct net *net) 350 { 351 int err; 352 struct fib_rules_ops *ops; 353 354 ops = fib_rules_register(&fib4_rules_ops_template, net); 355 if (IS_ERR(ops)) 356 return PTR_ERR(ops); 357 358 err = fib_default_rules_init(ops); 359 if (err < 0) 360 goto fail; 361 net->ipv4.rules_ops = ops; 362 net->ipv4.fib_has_custom_rules = false; 363 return 0; 364 365 fail: 366 /* also cleans all rules already added */ 367 fib_rules_unregister(ops); 368 return err; 369 } 370 371 void __net_exit fib4_rules_exit(struct net *net) 372 { 373 fib_rules_unregister(net->ipv4.rules_ops); 374 } 375