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Linux/net/ipv4/fib_rules.c

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  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 static bool fib4_rule_matchall(const struct fib_rule *rule)
 51 {
 52         struct fib4_rule *r = container_of(rule, struct fib4_rule, common);
 53 
 54         if (r->dst_len || r->src_len || r->tos)
 55                 return false;
 56         return fib_rule_matchall(rule);
 57 }
 58 
 59 bool fib4_rule_default(const struct fib_rule *rule)
 60 {
 61         if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
 62             rule->l3mdev)
 63                 return false;
 64         if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
 65             rule->table != RT_TABLE_DEFAULT)
 66                 return false;
 67         return true;
 68 }
 69 EXPORT_SYMBOL_GPL(fib4_rule_default);
 70 
 71 int fib4_rules_dump(struct net *net, struct notifier_block *nb)
 72 {
 73         return fib_rules_dump(net, nb, AF_INET);
 74 }
 75 
 76 unsigned int fib4_rules_seq_read(struct net *net)
 77 {
 78         return fib_rules_seq_read(net, AF_INET);
 79 }
 80 
 81 int __fib_lookup(struct net *net, struct flowi4 *flp,
 82                  struct fib_result *res, unsigned int flags)
 83 {
 84         struct fib_lookup_arg arg = {
 85                 .result = res,
 86                 .flags = flags,
 87         };
 88         int err;
 89 
 90         /* update flow if oif or iif point to device enslaved to l3mdev */
 91         l3mdev_update_flow(net, flowi4_to_flowi(flp));
 92 
 93         err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
 94 #ifdef CONFIG_IP_ROUTE_CLASSID
 95         if (arg.rule)
 96                 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
 97         else
 98                 res->tclassid = 0;
 99 #endif
100 
101         if (err == -ESRCH)
102                 err = -ENETUNREACH;
103 
104         return err;
105 }
106 EXPORT_SYMBOL_GPL(__fib_lookup);
107 
108 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
109                             int flags, 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 static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
144 {
145         struct fib_result *result = (struct fib_result *) arg->result;
146         struct net_device *dev = NULL;
147 
148         if (result->fi)
149                 dev = result->fi->fib_dev;
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         return 1;
186 }
187 
188 static struct fib_table *fib_empty_table(struct net *net)
189 {
190         u32 id;
191 
192         for (id = 1; id <= RT_TABLE_MAX; id++)
193                 if (!fib_get_table(net, id))
194                         return fib_new_table(net, id);
195         return NULL;
196 }
197 
198 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
199         FRA_GENERIC_POLICY,
200         [FRA_FLOW]      = { .type = NLA_U32 },
201 };
202 
203 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
204                                struct fib_rule_hdr *frh,
205                                struct nlattr **tb)
206 {
207         struct net *net = sock_net(skb->sk);
208         int err = -EINVAL;
209         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
210 
211         if (frh->tos & ~IPTOS_TOS_MASK)
212                 goto errout;
213 
214         /* split local/main if they are not already split */
215         err = fib_unmerge(net);
216         if (err)
217                 goto errout;
218 
219         if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
220                 if (rule->action == FR_ACT_TO_TBL) {
221                         struct fib_table *table;
222 
223                         table = fib_empty_table(net);
224                         if (!table) {
225                                 err = -ENOBUFS;
226                                 goto errout;
227                         }
228 
229                         rule->table = table->tb_id;
230                 }
231         }
232 
233         if (frh->src_len)
234                 rule4->src = nla_get_in_addr(tb[FRA_SRC]);
235 
236         if (frh->dst_len)
237                 rule4->dst = nla_get_in_addr(tb[FRA_DST]);
238 
239 #ifdef CONFIG_IP_ROUTE_CLASSID
240         if (tb[FRA_FLOW]) {
241                 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
242                 if (rule4->tclassid)
243                         net->ipv4.fib_num_tclassid_users++;
244         }
245 #endif
246 
247         rule4->src_len = frh->src_len;
248         rule4->srcmask = inet_make_mask(rule4->src_len);
249         rule4->dst_len = frh->dst_len;
250         rule4->dstmask = inet_make_mask(rule4->dst_len);
251         rule4->tos = frh->tos;
252 
253         net->ipv4.fib_has_custom_rules = true;
254 
255         err = 0;
256 errout:
257         return err;
258 }
259 
260 static int fib4_rule_delete(struct fib_rule *rule)
261 {
262         struct net *net = rule->fr_net;
263         int err;
264 
265         /* split local/main if they are not already split */
266         err = fib_unmerge(net);
267         if (err)
268                 goto errout;
269 
270 #ifdef CONFIG_IP_ROUTE_CLASSID
271         if (((struct fib4_rule *)rule)->tclassid)
272                 net->ipv4.fib_num_tclassid_users--;
273 #endif
274         net->ipv4.fib_has_custom_rules = true;
275 errout:
276         return err;
277 }
278 
279 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
280                              struct nlattr **tb)
281 {
282         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
283 
284         if (frh->src_len && (rule4->src_len != frh->src_len))
285                 return 0;
286 
287         if (frh->dst_len && (rule4->dst_len != frh->dst_len))
288                 return 0;
289 
290         if (frh->tos && (rule4->tos != frh->tos))
291                 return 0;
292 
293 #ifdef CONFIG_IP_ROUTE_CLASSID
294         if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
295                 return 0;
296 #endif
297 
298         if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
299                 return 0;
300 
301         if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
302                 return 0;
303 
304         return 1;
305 }
306 
307 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
308                           struct fib_rule_hdr *frh)
309 {
310         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
311 
312         frh->dst_len = rule4->dst_len;
313         frh->src_len = rule4->src_len;
314         frh->tos = rule4->tos;
315 
316         if ((rule4->dst_len &&
317              nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
318             (rule4->src_len &&
319              nla_put_in_addr(skb, FRA_SRC, rule4->src)))
320                 goto nla_put_failure;
321 #ifdef CONFIG_IP_ROUTE_CLASSID
322         if (rule4->tclassid &&
323             nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
324                 goto nla_put_failure;
325 #endif
326         return 0;
327 
328 nla_put_failure:
329         return -ENOBUFS;
330 }
331 
332 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
333 {
334         return nla_total_size(4) /* dst */
335                + nla_total_size(4) /* src */
336                + nla_total_size(4); /* flow */
337 }
338 
339 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
340 {
341         rt_cache_flush(ops->fro_net);
342 }
343 
344 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
345         .family         = AF_INET,
346         .rule_size      = sizeof(struct fib4_rule),
347         .addr_size      = sizeof(u32),
348         .action         = fib4_rule_action,
349         .suppress       = fib4_rule_suppress,
350         .match          = fib4_rule_match,
351         .configure      = fib4_rule_configure,
352         .delete         = fib4_rule_delete,
353         .compare        = fib4_rule_compare,
354         .fill           = fib4_rule_fill,
355         .nlmsg_payload  = fib4_rule_nlmsg_payload,
356         .flush_cache    = fib4_rule_flush_cache,
357         .nlgroup        = RTNLGRP_IPV4_RULE,
358         .policy         = fib4_rule_policy,
359         .owner          = THIS_MODULE,
360 };
361 
362 static int fib_default_rules_init(struct fib_rules_ops *ops)
363 {
364         int err;
365 
366         err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
367         if (err < 0)
368                 return err;
369         err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
370         if (err < 0)
371                 return err;
372         err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
373         if (err < 0)
374                 return err;
375         return 0;
376 }
377 
378 int __net_init fib4_rules_init(struct net *net)
379 {
380         int err;
381         struct fib_rules_ops *ops;
382 
383         ops = fib_rules_register(&fib4_rules_ops_template, net);
384         if (IS_ERR(ops))
385                 return PTR_ERR(ops);
386 
387         err = fib_default_rules_init(ops);
388         if (err < 0)
389                 goto fail;
390         net->ipv4.rules_ops = ops;
391         net->ipv4.fib_has_custom_rules = false;
392         return 0;
393 
394 fail:
395         /* also cleans all rules already added */
396         fib_rules_unregister(ops);
397         return err;
398 }
399 
400 void __net_exit fib4_rules_exit(struct net *net)
401 {
402         fib_rules_unregister(net->ipv4.rules_ops);
403 }
404 

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