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 err = -ENETUNREACH; 85 goto errout; 86 87 case FR_ACT_PROHIBIT: 88 err = -EACCES; 89 goto errout; 90 91 case FR_ACT_BLACKHOLE: 92 default: 93 err = -EINVAL; 94 goto errout; 95 } 96 97 tbl = fib_get_table(rule->fr_net, rule->table); 98 if (!tbl) 99 goto errout; 100 101 err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags); 102 if (err > 0) 103 err = -EAGAIN; 104 errout: 105 return err; 106 } 107 108 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg) 109 { 110 struct fib_result *result = (struct fib_result *) arg->result; 111 struct net_device *dev = NULL; 112 113 if (result->fi) 114 dev = result->fi->fib_dev; 115 116 /* do not accept result if the route does 117 * not meet the required prefix length 118 */ 119 if (result->prefixlen <= rule->suppress_prefixlen) 120 goto suppress_route; 121 122 /* do not accept result if the route uses a device 123 * belonging to a forbidden interface group 124 */ 125 if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup) 126 goto suppress_route; 127 128 return false; 129 130 suppress_route: 131 if (!(arg->flags & FIB_LOOKUP_NOREF)) 132 fib_info_put(result->fi); 133 return true; 134 } 135 136 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags) 137 { 138 struct fib4_rule *r = (struct fib4_rule *) rule; 139 struct flowi4 *fl4 = &fl->u.ip4; 140 __be32 daddr = fl4->daddr; 141 __be32 saddr = fl4->saddr; 142 143 if (((saddr ^ r->src) & r->srcmask) || 144 ((daddr ^ r->dst) & r->dstmask)) 145 return 0; 146 147 if (r->tos && (r->tos != fl4->flowi4_tos)) 148 return 0; 149 150 return 1; 151 } 152 153 static struct fib_table *fib_empty_table(struct net *net) 154 { 155 u32 id; 156 157 for (id = 1; id <= RT_TABLE_MAX; id++) 158 if (fib_get_table(net, id) == NULL) 159 return fib_new_table(net, id); 160 return NULL; 161 } 162 163 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = { 164 FRA_GENERIC_POLICY, 165 [FRA_FLOW] = { .type = NLA_U32 }, 166 }; 167 168 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb, 169 struct fib_rule_hdr *frh, 170 struct nlattr **tb) 171 { 172 struct net *net = sock_net(skb->sk); 173 int err = -EINVAL; 174 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 175 176 if (frh->tos & ~IPTOS_TOS_MASK) 177 goto errout; 178 179 if (rule->table == RT_TABLE_UNSPEC) { 180 if (rule->action == FR_ACT_TO_TBL) { 181 struct fib_table *table; 182 183 table = fib_empty_table(net); 184 if (table == NULL) { 185 err = -ENOBUFS; 186 goto errout; 187 } 188 189 rule->table = table->tb_id; 190 } 191 } 192 193 if (frh->src_len) 194 rule4->src = nla_get_be32(tb[FRA_SRC]); 195 196 if (frh->dst_len) 197 rule4->dst = nla_get_be32(tb[FRA_DST]); 198 199 #ifdef CONFIG_IP_ROUTE_CLASSID 200 if (tb[FRA_FLOW]) { 201 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]); 202 if (rule4->tclassid) 203 net->ipv4.fib_num_tclassid_users++; 204 } 205 #endif 206 207 rule4->src_len = frh->src_len; 208 rule4->srcmask = inet_make_mask(rule4->src_len); 209 rule4->dst_len = frh->dst_len; 210 rule4->dstmask = inet_make_mask(rule4->dst_len); 211 rule4->tos = frh->tos; 212 213 net->ipv4.fib_has_custom_rules = true; 214 err = 0; 215 errout: 216 return err; 217 } 218 219 static void fib4_rule_delete(struct fib_rule *rule) 220 { 221 struct net *net = rule->fr_net; 222 #ifdef CONFIG_IP_ROUTE_CLASSID 223 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 224 225 if (rule4->tclassid) 226 net->ipv4.fib_num_tclassid_users--; 227 #endif 228 net->ipv4.fib_has_custom_rules = true; 229 } 230 231 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh, 232 struct nlattr **tb) 233 { 234 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 235 236 if (frh->src_len && (rule4->src_len != frh->src_len)) 237 return 0; 238 239 if (frh->dst_len && (rule4->dst_len != frh->dst_len)) 240 return 0; 241 242 if (frh->tos && (rule4->tos != frh->tos)) 243 return 0; 244 245 #ifdef CONFIG_IP_ROUTE_CLASSID 246 if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW]))) 247 return 0; 248 #endif 249 250 if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC]))) 251 return 0; 252 253 if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST]))) 254 return 0; 255 256 return 1; 257 } 258 259 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb, 260 struct fib_rule_hdr *frh) 261 { 262 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 263 264 frh->dst_len = rule4->dst_len; 265 frh->src_len = rule4->src_len; 266 frh->tos = rule4->tos; 267 268 if ((rule4->dst_len && 269 nla_put_be32(skb, FRA_DST, rule4->dst)) || 270 (rule4->src_len && 271 nla_put_be32(skb, FRA_SRC, rule4->src))) 272 goto nla_put_failure; 273 #ifdef CONFIG_IP_ROUTE_CLASSID 274 if (rule4->tclassid && 275 nla_put_u32(skb, FRA_FLOW, rule4->tclassid)) 276 goto nla_put_failure; 277 #endif 278 return 0; 279 280 nla_put_failure: 281 return -ENOBUFS; 282 } 283 284 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule) 285 { 286 return nla_total_size(4) /* dst */ 287 + nla_total_size(4) /* src */ 288 + nla_total_size(4); /* flow */ 289 } 290 291 static void fib4_rule_flush_cache(struct fib_rules_ops *ops) 292 { 293 rt_cache_flush(ops->fro_net); 294 } 295 296 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = { 297 .family = AF_INET, 298 .rule_size = sizeof(struct fib4_rule), 299 .addr_size = sizeof(u32), 300 .action = fib4_rule_action, 301 .suppress = fib4_rule_suppress, 302 .match = fib4_rule_match, 303 .configure = fib4_rule_configure, 304 .delete = fib4_rule_delete, 305 .compare = fib4_rule_compare, 306 .fill = fib4_rule_fill, 307 .default_pref = fib_default_rule_pref, 308 .nlmsg_payload = fib4_rule_nlmsg_payload, 309 .flush_cache = fib4_rule_flush_cache, 310 .nlgroup = RTNLGRP_IPV4_RULE, 311 .policy = fib4_rule_policy, 312 .owner = THIS_MODULE, 313 }; 314 315 static int fib_default_rules_init(struct fib_rules_ops *ops) 316 { 317 int err; 318 319 err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0); 320 if (err < 0) 321 return err; 322 err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0); 323 if (err < 0) 324 return err; 325 err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0); 326 if (err < 0) 327 return err; 328 return 0; 329 } 330 331 int __net_init fib4_rules_init(struct net *net) 332 { 333 int err; 334 struct fib_rules_ops *ops; 335 336 ops = fib_rules_register(&fib4_rules_ops_template, net); 337 if (IS_ERR(ops)) 338 return PTR_ERR(ops); 339 340 err = fib_default_rules_init(ops); 341 if (err < 0) 342 goto fail; 343 net->ipv4.rules_ops = ops; 344 net->ipv4.fib_has_custom_rules = false; 345 return 0; 346 347 fail: 348 /* also cleans all rules already added */ 349 fib_rules_unregister(ops); 350 return err; 351 } 352 353 void __net_exit fib4_rules_exit(struct net *net) 354 { 355 fib_rules_unregister(net->ipv4.rules_ops); 356 } 357