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Linux/net/ipv6/fib6_rules.c

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  1 /*
  2  * net/ipv6/fib6_rules.c        IPv6 Routing Policy Rules
  3  *
  4  * Copyright (C)2003-2006 Helsinki University of Technology
  5  * Copyright (C)2003-2006 USAGI/WIDE Project
  6  *
  7  *      This program is free software; you can redistribute it and/or
  8  *      modify it under the terms of the GNU General Public License as
  9  *      published by the Free Software Foundation, version 2.
 10  *
 11  * Authors
 12  *      Thomas Graf             <tgraf@suug.ch>
 13  *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
 14  */
 15 
 16 #include <linux/netdevice.h>
 17 #include <linux/notifier.h>
 18 #include <linux/export.h>
 19 
 20 #include <net/fib_rules.h>
 21 #include <net/ipv6.h>
 22 #include <net/addrconf.h>
 23 #include <net/ip6_route.h>
 24 #include <net/netlink.h>
 25 
 26 struct fib6_rule {
 27         struct fib_rule         common;
 28         struct rt6key           src;
 29         struct rt6key           dst;
 30         u8                      tclass;
 31 };
 32 
 33 static bool fib6_rule_matchall(const struct fib_rule *rule)
 34 {
 35         struct fib6_rule *r = container_of(rule, struct fib6_rule, common);
 36 
 37         if (r->dst.plen || r->src.plen || r->tclass)
 38                 return false;
 39         return fib_rule_matchall(rule);
 40 }
 41 
 42 bool fib6_rule_default(const struct fib_rule *rule)
 43 {
 44         if (!fib6_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
 45             rule->l3mdev)
 46                 return false;
 47         if (rule->table != RT6_TABLE_LOCAL && rule->table != RT6_TABLE_MAIN)
 48                 return false;
 49         return true;
 50 }
 51 EXPORT_SYMBOL_GPL(fib6_rule_default);
 52 
 53 int fib6_rules_dump(struct net *net, struct notifier_block *nb)
 54 {
 55         return fib_rules_dump(net, nb, AF_INET6);
 56 }
 57 
 58 unsigned int fib6_rules_seq_read(struct net *net)
 59 {
 60         return fib_rules_seq_read(net, AF_INET6);
 61 }
 62 
 63 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 64                                    int flags, pol_lookup_t lookup)
 65 {
 66         if (net->ipv6.fib6_has_custom_rules) {
 67                 struct fib_lookup_arg arg = {
 68                         .lookup_ptr = lookup,
 69                         .flags = FIB_LOOKUP_NOREF,
 70                 };
 71 
 72                 /* update flow if oif or iif point to device enslaved to l3mdev */
 73                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
 74 
 75                 fib_rules_lookup(net->ipv6.fib6_rules_ops,
 76                                  flowi6_to_flowi(fl6), flags, &arg);
 77 
 78                 if (arg.result)
 79                         return arg.result;
 80         } else {
 81                 struct rt6_info *rt;
 82 
 83                 rt = lookup(net, net->ipv6.fib6_local_tbl, fl6, flags);
 84                 if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
 85                         return &rt->dst;
 86                 ip6_rt_put(rt);
 87                 rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
 88                 if (rt->dst.error != -EAGAIN)
 89                         return &rt->dst;
 90                 ip6_rt_put(rt);
 91         }
 92 
 93         dst_hold(&net->ipv6.ip6_null_entry->dst);
 94         return &net->ipv6.ip6_null_entry->dst;
 95 }
 96 
 97 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
 98                             int flags, struct fib_lookup_arg *arg)
 99 {
100         struct flowi6 *flp6 = &flp->u.ip6;
101         struct rt6_info *rt = NULL;
102         struct fib6_table *table;
103         struct net *net = rule->fr_net;
104         pol_lookup_t lookup = arg->lookup_ptr;
105         int err = 0;
106         u32 tb_id;
107 
108         switch (rule->action) {
109         case FR_ACT_TO_TBL:
110                 break;
111         case FR_ACT_UNREACHABLE:
112                 err = -ENETUNREACH;
113                 rt = net->ipv6.ip6_null_entry;
114                 goto discard_pkt;
115         default:
116         case FR_ACT_BLACKHOLE:
117                 err = -EINVAL;
118                 rt = net->ipv6.ip6_blk_hole_entry;
119                 goto discard_pkt;
120         case FR_ACT_PROHIBIT:
121                 err = -EACCES;
122                 rt = net->ipv6.ip6_prohibit_entry;
123                 goto discard_pkt;
124         }
125 
126         tb_id = fib_rule_get_table(rule, arg);
127         table = fib6_get_table(net, tb_id);
128         if (!table) {
129                 err = -EAGAIN;
130                 goto out;
131         }
132 
133         rt = lookup(net, table, flp6, flags);
134         if (rt != net->ipv6.ip6_null_entry) {
135                 struct fib6_rule *r = (struct fib6_rule *)rule;
136 
137                 /*
138                  * If we need to find a source address for this traffic,
139                  * we check the result if it meets requirement of the rule.
140                  */
141                 if ((rule->flags & FIB_RULE_FIND_SADDR) &&
142                     r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
143                         struct in6_addr saddr;
144 
145                         if (ipv6_dev_get_saddr(net,
146                                                ip6_dst_idev(&rt->dst)->dev,
147                                                &flp6->daddr,
148                                                rt6_flags2srcprefs(flags),
149                                                &saddr))
150                                 goto again;
151                         if (!ipv6_prefix_equal(&saddr, &r->src.addr,
152                                                r->src.plen))
153                                 goto again;
154                         flp6->saddr = saddr;
155                 }
156                 err = rt->dst.error;
157                 if (err != -EAGAIN)
158                         goto out;
159         }
160 again:
161         ip6_rt_put(rt);
162         err = -EAGAIN;
163         rt = NULL;
164         goto out;
165 
166 discard_pkt:
167         dst_hold(&rt->dst);
168 out:
169         arg->result = rt;
170         return err;
171 }
172 
173 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
174 {
175         struct rt6_info *rt = (struct rt6_info *) arg->result;
176         struct net_device *dev = NULL;
177 
178         if (rt->rt6i_idev)
179                 dev = rt->rt6i_idev->dev;
180 
181         /* do not accept result if the route does
182          * not meet the required prefix length
183          */
184         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
185                 goto suppress_route;
186 
187         /* do not accept result if the route uses a device
188          * belonging to a forbidden interface group
189          */
190         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
191                 goto suppress_route;
192 
193         return false;
194 
195 suppress_route:
196         ip6_rt_put(rt);
197         return true;
198 }
199 
200 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
201 {
202         struct fib6_rule *r = (struct fib6_rule *) rule;
203         struct flowi6 *fl6 = &fl->u.ip6;
204 
205         if (r->dst.plen &&
206             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
207                 return 0;
208 
209         /*
210          * If FIB_RULE_FIND_SADDR is set and we do not have a
211          * source address for the traffic, we defer check for
212          * source address.
213          */
214         if (r->src.plen) {
215                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
216                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
217                                                r->src.plen))
218                                 return 0;
219                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
220                         return 0;
221         }
222 
223         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
224                 return 0;
225 
226         return 1;
227 }
228 
229 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
230         FRA_GENERIC_POLICY,
231 };
232 
233 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
234                                struct fib_rule_hdr *frh,
235                                struct nlattr **tb)
236 {
237         int err = -EINVAL;
238         struct net *net = sock_net(skb->sk);
239         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
240 
241         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
242                 if (rule->table == RT6_TABLE_UNSPEC)
243                         goto errout;
244 
245                 if (fib6_new_table(net, rule->table) == NULL) {
246                         err = -ENOBUFS;
247                         goto errout;
248                 }
249         }
250 
251         if (frh->src_len)
252                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
253 
254         if (frh->dst_len)
255                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
256 
257         rule6->src.plen = frh->src_len;
258         rule6->dst.plen = frh->dst_len;
259         rule6->tclass = frh->tos;
260 
261         net->ipv6.fib6_has_custom_rules = true;
262         err = 0;
263 errout:
264         return err;
265 }
266 
267 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
268                              struct nlattr **tb)
269 {
270         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
271 
272         if (frh->src_len && (rule6->src.plen != frh->src_len))
273                 return 0;
274 
275         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
276                 return 0;
277 
278         if (frh->tos && (rule6->tclass != frh->tos))
279                 return 0;
280 
281         if (frh->src_len &&
282             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
283                 return 0;
284 
285         if (frh->dst_len &&
286             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
287                 return 0;
288 
289         return 1;
290 }
291 
292 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
293                           struct fib_rule_hdr *frh)
294 {
295         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
296 
297         frh->dst_len = rule6->dst.plen;
298         frh->src_len = rule6->src.plen;
299         frh->tos = rule6->tclass;
300 
301         if ((rule6->dst.plen &&
302              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
303             (rule6->src.plen &&
304              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
305                 goto nla_put_failure;
306         return 0;
307 
308 nla_put_failure:
309         return -ENOBUFS;
310 }
311 
312 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
313 {
314         return nla_total_size(16) /* dst */
315                + nla_total_size(16); /* src */
316 }
317 
318 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
319         .family                 = AF_INET6,
320         .rule_size              = sizeof(struct fib6_rule),
321         .addr_size              = sizeof(struct in6_addr),
322         .action                 = fib6_rule_action,
323         .match                  = fib6_rule_match,
324         .suppress               = fib6_rule_suppress,
325         .configure              = fib6_rule_configure,
326         .compare                = fib6_rule_compare,
327         .fill                   = fib6_rule_fill,
328         .nlmsg_payload          = fib6_rule_nlmsg_payload,
329         .nlgroup                = RTNLGRP_IPV6_RULE,
330         .policy                 = fib6_rule_policy,
331         .owner                  = THIS_MODULE,
332         .fro_net                = &init_net,
333 };
334 
335 static int __net_init fib6_rules_net_init(struct net *net)
336 {
337         struct fib_rules_ops *ops;
338         int err = -ENOMEM;
339 
340         ops = fib_rules_register(&fib6_rules_ops_template, net);
341         if (IS_ERR(ops))
342                 return PTR_ERR(ops);
343 
344         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
345         if (err)
346                 goto out_fib6_rules_ops;
347 
348         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
349         if (err)
350                 goto out_fib6_rules_ops;
351 
352         net->ipv6.fib6_rules_ops = ops;
353 out:
354         return err;
355 
356 out_fib6_rules_ops:
357         fib_rules_unregister(ops);
358         goto out;
359 }
360 
361 static void __net_exit fib6_rules_net_exit(struct net *net)
362 {
363         rtnl_lock();
364         fib_rules_unregister(net->ipv6.fib6_rules_ops);
365         rtnl_unlock();
366 }
367 
368 static struct pernet_operations fib6_rules_net_ops = {
369         .init = fib6_rules_net_init,
370         .exit = fib6_rules_net_exit,
371 };
372 
373 int __init fib6_rules_init(void)
374 {
375         return register_pernet_subsys(&fib6_rules_net_ops);
376 }
377 
378 
379 void fib6_rules_cleanup(void)
380 {
381         unregister_pernet_subsys(&fib6_rules_net_ops);
382 }
383 

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