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 return err; 66 } 67 EXPORT_SYMBOL_GPL(__fib_lookup); 68 69 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp, 70 int flags, struct fib_lookup_arg *arg) 71 { 72 int err = -EAGAIN; 73 struct fib_table *tbl; 74 75 switch (rule->action) { 76 case FR_ACT_TO_TBL: 77 break; 78 79 case FR_ACT_UNREACHABLE: 80 err = -ENETUNREACH; 81 goto errout; 82 83 case FR_ACT_PROHIBIT: 84 err = -EACCES; 85 goto errout; 86 87 case FR_ACT_BLACKHOLE: 88 default: 89 err = -EINVAL; 90 goto errout; 91 } 92 93 tbl = fib_get_table(rule->fr_net, rule->table); 94 if (!tbl) 95 goto errout; 96 97 err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags); 98 if (err > 0) 99 err = -EAGAIN; 100 errout: 101 return err; 102 } 103 104 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg) 105 { 106 struct fib_result *result = (struct fib_result *) arg->result; 107 struct net_device *dev = result->fi->fib_dev; 108 109 /* do not accept result if the route does 110 * not meet the required prefix length 111 */ 112 if (result->prefixlen <= rule->suppress_prefixlen) 113 goto suppress_route; 114 115 /* do not accept result if the route uses a device 116 * belonging to a forbidden interface group 117 */ 118 if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup) 119 goto suppress_route; 120 121 return false; 122 123 suppress_route: 124 if (!(arg->flags & FIB_LOOKUP_NOREF)) 125 fib_info_put(result->fi); 126 return true; 127 } 128 129 static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags) 130 { 131 struct fib4_rule *r = (struct fib4_rule *) rule; 132 struct flowi4 *fl4 = &fl->u.ip4; 133 __be32 daddr = fl4->daddr; 134 __be32 saddr = fl4->saddr; 135 136 if (((saddr ^ r->src) & r->srcmask) || 137 ((daddr ^ r->dst) & r->dstmask)) 138 return 0; 139 140 if (r->tos && (r->tos != fl4->flowi4_tos)) 141 return 0; 142 143 return 1; 144 } 145 146 static struct fib_table *fib_empty_table(struct net *net) 147 { 148 u32 id; 149 150 for (id = 1; id <= RT_TABLE_MAX; id++) 151 if (fib_get_table(net, id) == NULL) 152 return fib_new_table(net, id); 153 return NULL; 154 } 155 156 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = { 157 FRA_GENERIC_POLICY, 158 [FRA_FLOW] = { .type = NLA_U32 }, 159 }; 160 161 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb, 162 struct fib_rule_hdr *frh, 163 struct nlattr **tb) 164 { 165 struct net *net = sock_net(skb->sk); 166 int err = -EINVAL; 167 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 168 169 if (frh->tos & ~IPTOS_TOS_MASK) 170 goto errout; 171 172 if (rule->table == RT_TABLE_UNSPEC) { 173 if (rule->action == FR_ACT_TO_TBL) { 174 struct fib_table *table; 175 176 table = fib_empty_table(net); 177 if (table == NULL) { 178 err = -ENOBUFS; 179 goto errout; 180 } 181 182 rule->table = table->tb_id; 183 } 184 } 185 186 if (frh->src_len) 187 rule4->src = nla_get_be32(tb[FRA_SRC]); 188 189 if (frh->dst_len) 190 rule4->dst = nla_get_be32(tb[FRA_DST]); 191 192 #ifdef CONFIG_IP_ROUTE_CLASSID 193 if (tb[FRA_FLOW]) { 194 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]); 195 if (rule4->tclassid) 196 net->ipv4.fib_num_tclassid_users++; 197 } 198 #endif 199 200 rule4->src_len = frh->src_len; 201 rule4->srcmask = inet_make_mask(rule4->src_len); 202 rule4->dst_len = frh->dst_len; 203 rule4->dstmask = inet_make_mask(rule4->dst_len); 204 rule4->tos = frh->tos; 205 206 net->ipv4.fib_has_custom_rules = true; 207 err = 0; 208 errout: 209 return err; 210 } 211 212 static void fib4_rule_delete(struct fib_rule *rule) 213 { 214 struct net *net = rule->fr_net; 215 #ifdef CONFIG_IP_ROUTE_CLASSID 216 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 217 218 if (rule4->tclassid) 219 net->ipv4.fib_num_tclassid_users--; 220 #endif 221 net->ipv4.fib_has_custom_rules = true; 222 } 223 224 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh, 225 struct nlattr **tb) 226 { 227 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 228 229 if (frh->src_len && (rule4->src_len != frh->src_len)) 230 return 0; 231 232 if (frh->dst_len && (rule4->dst_len != frh->dst_len)) 233 return 0; 234 235 if (frh->tos && (rule4->tos != frh->tos)) 236 return 0; 237 238 #ifdef CONFIG_IP_ROUTE_CLASSID 239 if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW]))) 240 return 0; 241 #endif 242 243 if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC]))) 244 return 0; 245 246 if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST]))) 247 return 0; 248 249 return 1; 250 } 251 252 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb, 253 struct fib_rule_hdr *frh) 254 { 255 struct fib4_rule *rule4 = (struct fib4_rule *) rule; 256 257 frh->dst_len = rule4->dst_len; 258 frh->src_len = rule4->src_len; 259 frh->tos = rule4->tos; 260 261 if ((rule4->dst_len && 262 nla_put_be32(skb, FRA_DST, rule4->dst)) || 263 (rule4->src_len && 264 nla_put_be32(skb, FRA_SRC, rule4->src))) 265 goto nla_put_failure; 266 #ifdef CONFIG_IP_ROUTE_CLASSID 267 if (rule4->tclassid && 268 nla_put_u32(skb, FRA_FLOW, rule4->tclassid)) 269 goto nla_put_failure; 270 #endif 271 return 0; 272 273 nla_put_failure: 274 return -ENOBUFS; 275 } 276 277 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule) 278 { 279 return nla_total_size(4) /* dst */ 280 + nla_total_size(4) /* src */ 281 + nla_total_size(4); /* flow */ 282 } 283 284 static void fib4_rule_flush_cache(struct fib_rules_ops *ops) 285 { 286 rt_cache_flush(ops->fro_net); 287 } 288 289 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = { 290 .family = AF_INET, 291 .rule_size = sizeof(struct fib4_rule), 292 .addr_size = sizeof(u32), 293 .action = fib4_rule_action, 294 .suppress = fib4_rule_suppress, 295 .match = fib4_rule_match, 296 .configure = fib4_rule_configure, 297 .delete = fib4_rule_delete, 298 .compare = fib4_rule_compare, 299 .fill = fib4_rule_fill, 300 .default_pref = fib_default_rule_pref, 301 .nlmsg_payload = fib4_rule_nlmsg_payload, 302 .flush_cache = fib4_rule_flush_cache, 303 .nlgroup = RTNLGRP_IPV4_RULE, 304 .policy = fib4_rule_policy, 305 .owner = THIS_MODULE, 306 }; 307 308 static int fib_default_rules_init(struct fib_rules_ops *ops) 309 { 310 int err; 311 312 err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0); 313 if (err < 0) 314 return err; 315 err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0); 316 if (err < 0) 317 return err; 318 err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0); 319 if (err < 0) 320 return err; 321 return 0; 322 } 323 324 int __net_init fib4_rules_init(struct net *net) 325 { 326 int err; 327 struct fib_rules_ops *ops; 328 329 ops = fib_rules_register(&fib4_rules_ops_template, net); 330 if (IS_ERR(ops)) 331 return PTR_ERR(ops); 332 333 err = fib_default_rules_init(ops); 334 if (err < 0) 335 goto fail; 336 net->ipv4.rules_ops = ops; 337 net->ipv4.fib_has_custom_rules = false; 338 return 0; 339 340 fail: 341 /* also cleans all rules already added */ 342 fib_rules_unregister(ops); 343 return err; 344 } 345 346 void __net_exit fib4_rules_exit(struct net *net) 347 { 348 fib_rules_unregister(net->ipv4.rules_ops); 349 } 350