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

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