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