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

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