1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * INET An implementation of the TCP/IP protocol suite for the LINUX 4 * operating system. INET is implemented using the BSD Socket 5 * interface as the means of communication with the user level. 6 * 7 * IPv4 Forwarding Information Base: policy rules. 8 * 9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 10 * Thomas Graf <tgraf@suug.ch> 11 * 12 * Fixes: 13 * Rani Assaf : local_rule cannot be deleted 14 * Marc Boucher : routing by fwmark 15 */ 16 17 #include <linux/types.h> 18 #include <linux/kernel.h> 19 #include <linux/netdevice.h> 20 #include <linux/netlink.h> 21 #include <linux/inetdevice.h> 22 #include <linux/init.h> 23 #include <linux/list.h> 24 #include <linux/rcupdate.h> 25 #include <linux/export.h> 26 #include <net/ip.h> 27 #include <net/route.h> 28 #include <net/tcp.h> 29 #include <net/ip_fib.h> 30 #include <net/nexthop.h> 31 #include <net/fib_rules.h> 32 #include <linux/indirect_call_wrapper.h> 33 34 struct fib4_rule { 35 struct fib_rule common; 36 u8 dst_len; 37 u8 src_len; 38 u8 tos; 39 __be32 src; 40 __be32 srcmask; 41 __be32 dst; 42 __be32 dstmask; 43 #ifdef CONFIG_IP_ROUTE_CLASSID 44 u32 tclassid; 45 #endif 46 }; 47 48 static bool fib4_rule_matchall(const struct fib_rule *rule) 49 { 50 struct fib4_rule *r = container_of(rule, struct fib4_rule, common); 51 52 if (r->dst_len || r->src_len || r->tos) 53 return false; 54 return fib_rule_matchall(rule); 55 } 56 57 bool fib4_rule_default(const struct fib_rule *rule) 58 { 59 if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL || 60 rule->l3mdev) 61 return false; 62 if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN && 63 rule->table != RT_TABLE_DEFAULT) 64 return false; 65 return true; 66 } 67 EXPORT_SYMBOL_GPL(fib4_rule_default); 68 69 int fib4_rules_dump(struct net *net, struct notifier_block *nb, 70 struct netlink_ext_ack *extack) 71 { 72 return fib_rules_dump(net, nb, AF_INET, extack); 73 } 74 75 unsigned int fib4_rules_seq_read(struct net *net) 76 { 77 return fib_rules_seq_read(net, AF_INET); 78 } 79 80 int __fib_lookup(struct net *net, struct flowi4 *flp, 81 struct fib_result *res, unsigned int flags) 82 { 83 struct fib_lookup_arg arg = { 84 .result = res, 85 .flags = flags, 86 }; 87 int err; 88 89 /* update flow if oif or iif point to device enslaved to l3mdev */ 90 l3mdev_update_flow(net, flowi4_to_flowi(flp)); 91 92 err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg); 93 #ifdef CONFIG_IP_ROUTE_CLASSID 94 if (arg.rule) 95 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid; 96 else 97 res->tclassid = 0; 98 #endif 99 100 if (err == -ESRCH) 101 err = -ENETUNREACH; 102 103 return err; 104 } 105 EXPORT_SYMBOL_GPL(__fib_lookup); 106 107 INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule, 108 struct flowi *flp, int flags, 109 struct fib_lookup_arg *arg) 110 { 111 int err = -EAGAIN; 112 struct fib_table *tbl; 113 u32 tb_id; 114 115 switch (rule->action) { 116 case FR_ACT_TO_TBL: 117 break; 118 119 case FR_ACT_UNREACHABLE: 120 return -ENETUNREACH; 121 122 case FR_ACT_PROHIBIT: 123 return -EACCES; 124 125 case FR_ACT_BLACKHOLE: 126 default: 127 return -EINVAL; 128 } 129 130 rcu_read_lock(); 131 132 tb_id = fib_rule_get_table(rule, arg); 133 tbl = fib_get_table(rule->fr_net, tb_id); 134 if (tbl) 135 err = fib_table_lookup(tbl, &flp->u.ip4, 136 (struct fib_result *)arg->result, 137 arg->flags); 138 139 rcu_read_unlock(); 140 return err; 141 } 142 143 INDIRECT_CALLABLE_SCOPE bool fib4_rule_suppress(struct fib_rule *rule, 144 struct fib_lookup_arg *arg) 145 { 146 struct fib_result *result = (struct fib_result *) arg->result; 147 struct net_device *dev = NULL; 148 149 if (result->fi) { 150 struct fib_nh_common *nhc = fib_info_nhc(result->fi, 0); 151 152 dev = nhc->nhc_dev; 153 } 154 155 /* do not accept result if the route does 156 * not meet the required prefix length 157 */ 158 if (result->prefixlen <= rule->suppress_prefixlen) 159 goto suppress_route; 160 161 /* do not accept result if the route uses a device 162 * belonging to a forbidden interface group 163 */ 164 if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup) 165 goto suppress_route; 166 167 return false; 168 169 suppress_route: 170 if (!(arg->flags & FIB_LOOKUP_NOREF)) 171 fib_info_put(result->fi); 172 return true; 173 } 174 175 INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule, 176 struct flowi *fl, int flags) 177 { 178 struct fib4_rule *r = (struct fib4_rule *) rule; 179 struct flowi4 *fl4 = &fl->u.ip4; 180 __be32 daddr = fl4->daddr; 181 __be32 saddr = fl4->saddr; 182 183 if (((saddr ^ r->src) & r->srcmask) || 184 ((daddr ^ r->dst) & r->dstmask)) 185 return 0; 186 187 if (r->tos && (r->tos != fl4->flowi4_tos)) 188 return 0; 189 190 if (rule->ip_proto && (rule->ip_proto != fl4->flowi4_proto)) 191 return 0; 192 193 if (fib_rule_port_range_set(&rule->sport_range) && 194 !fib_rule_port_inrange(&rule->sport_range, fl4->fl4_sport)) 195 return 0; 196 197 if (fib_rule_port_range_set(&rule->dport_range) && 198 !fib_rule_port_inrange(&rule->dport_range, fl4->fl4_dport)) 199 return 0; 200 201 return 1; 202 } 203 204 static struct fib_table *fib_empty_table(struct net *net) 205 { 206 u32 id = 1; 207 208 while (1) { 209 if (!fib_get_table(net, id)) 210 return fib_new_table(net, id); 211 212 if (id++ == RT_TABLE_MAX) 213 break; 214 } 215 return NULL; 216 } 217 218 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = { 219 FRA_GENERIC_POLICY, 220 [FRA_FLOW] = { .type = NLA_U32 }, 221 }; 222 223 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb, 224 struct fib_rule_hdr *frh, 225 struct nlattr **tb, 226 struct netlink_ext_ack *extack) 227 { 228 struct net *net = sock_net(skb->sk); 229 int err = -EINVAL; 230 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 231 232 if (frh->tos & ~IPTOS_TOS_MASK) { 233 NL_SET_ERR_MSG(extack, "Invalid tos"); 234 goto errout; 235 } 236 237 /* split local/main if they are not already split */ 238 err = fib_unmerge(net); 239 if (err) 240 goto errout; 241 242 if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) { 243 if (rule->action == FR_ACT_TO_TBL) { 244 struct fib_table *table; 245 246 table = fib_empty_table(net); 247 if (!table) { 248 err = -ENOBUFS; 249 goto errout; 250 } 251 252 rule->table = table->tb_id; 253 } 254 } 255 256 if (frh->src_len) 257 rule4->src = nla_get_in_addr(tb[FRA_SRC]); 258 259 if (frh->dst_len) 260 rule4->dst = nla_get_in_addr(tb[FRA_DST]); 261 262 #ifdef CONFIG_IP_ROUTE_CLASSID 263 if (tb[FRA_FLOW]) { 264 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]); 265 if (rule4->tclassid) 266 net->ipv4.fib_num_tclassid_users++; 267 } 268 #endif 269 270 if (fib_rule_requires_fldissect(rule)) 271 net->ipv4.fib_rules_require_fldissect++; 272 273 rule4->src_len = frh->src_len; 274 rule4->srcmask = inet_make_mask(rule4->src_len); 275 rule4->dst_len = frh->dst_len; 276 rule4->dstmask = inet_make_mask(rule4->dst_len); 277 rule4->tos = frh->tos; 278 279 net->ipv4.fib_has_custom_rules = true; 280 281 err = 0; 282 errout: 283 return err; 284 } 285 286 static int fib4_rule_delete(struct fib_rule *rule) 287 { 288 struct net *net = rule->fr_net; 289 int err; 290 291 /* split local/main if they are not already split */ 292 err = fib_unmerge(net); 293 if (err) 294 goto errout; 295 296 #ifdef CONFIG_IP_ROUTE_CLASSID 297 if (((struct fib4_rule *)rule)->tclassid) 298 net->ipv4.fib_num_tclassid_users--; 299 #endif 300 net->ipv4.fib_has_custom_rules = true; 301 302 if (net->ipv4.fib_rules_require_fldissect && 303 fib_rule_requires_fldissect(rule)) 304 net->ipv4.fib_rules_require_fldissect--; 305 errout: 306 return err; 307 } 308 309 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh, 310 struct nlattr **tb) 311 { 312 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 313 314 if (frh->src_len && (rule4->src_len != frh->src_len)) 315 return 0; 316 317 if (frh->dst_len && (rule4->dst_len != frh->dst_len)) 318 return 0; 319 320 if (frh->tos && (rule4->tos != frh->tos)) 321 return 0; 322 323 #ifdef CONFIG_IP_ROUTE_CLASSID 324 if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW]))) 325 return 0; 326 #endif 327 328 if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC]))) 329 return 0; 330 331 if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST]))) 332 return 0; 333 334 return 1; 335 } 336 337 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb, 338 struct fib_rule_hdr *frh) 339 { 340 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 341 342 frh->dst_len = rule4->dst_len; 343 frh->src_len = rule4->src_len; 344 frh->tos = rule4->tos; 345 346 if ((rule4->dst_len && 347 nla_put_in_addr(skb, FRA_DST, rule4->dst)) || 348 (rule4->src_len && 349 nla_put_in_addr(skb, FRA_SRC, rule4->src))) 350 goto nla_put_failure; 351 #ifdef CONFIG_IP_ROUTE_CLASSID 352 if (rule4->tclassid && 353 nla_put_u32(skb, FRA_FLOW, rule4->tclassid)) 354 goto nla_put_failure; 355 #endif 356 return 0; 357 358 nla_put_failure: 359 return -ENOBUFS; 360 } 361 362 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule) 363 { 364 return nla_total_size(4) /* dst */ 365 + nla_total_size(4) /* src */ 366 + nla_total_size(4); /* flow */ 367 } 368 369 static void fib4_rule_flush_cache(struct fib_rules_ops *ops) 370 { 371 rt_cache_flush(ops->fro_net); 372 } 373 374 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = { 375 .family = AF_INET, 376 .rule_size = sizeof(struct fib4_rule), 377 .addr_size = sizeof(u32), 378 .action = fib4_rule_action, 379 .suppress = fib4_rule_suppress, 380 .match = fib4_rule_match, 381 .configure = fib4_rule_configure, 382 .delete = fib4_rule_delete, 383 .compare = fib4_rule_compare, 384 .fill = fib4_rule_fill, 385 .nlmsg_payload = fib4_rule_nlmsg_payload, 386 .flush_cache = fib4_rule_flush_cache, 387 .nlgroup = RTNLGRP_IPV4_RULE, 388 .policy = fib4_rule_policy, 389 .owner = THIS_MODULE, 390 }; 391 392 static int fib_default_rules_init(struct fib_rules_ops *ops) 393 { 394 int err; 395 396 err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0); 397 if (err < 0) 398 return err; 399 err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0); 400 if (err < 0) 401 return err; 402 err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0); 403 if (err < 0) 404 return err; 405 return 0; 406 } 407 408 int __net_init fib4_rules_init(struct net *net) 409 { 410 int err; 411 struct fib_rules_ops *ops; 412 413 ops = fib_rules_register(&fib4_rules_ops_template, net); 414 if (IS_ERR(ops)) 415 return PTR_ERR(ops); 416 417 err = fib_default_rules_init(ops); 418 if (err < 0) 419 goto fail; 420 net->ipv4.rules_ops = ops; 421 net->ipv4.fib_has_custom_rules = false; 422 net->ipv4.fib_rules_require_fldissect = 0; 423 return 0; 424 425 fail: 426 /* also cleans all rules already added */ 427 fib_rules_unregister(ops); 428 return err; 429 } 430 431 void __net_exit fib4_rules_exit(struct net *net) 432 { 433 fib_rules_unregister(net->ipv4.rules_ops); 434 } 435