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Linux/net/ipv6/fib6_rules.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * net/ipv6/fib6_rules.c        IPv6 Routing Policy Rules
  4  *
  5  * Copyright (C)2003-2006 Helsinki University of Technology
  6  * Copyright (C)2003-2006 USAGI/WIDE Project
  7  *
  8  * Authors
  9  *      Thomas Graf             <tgraf@suug.ch>
 10  *      Ville Nuorvala          <vnuorval@tcs.hut.fi>
 11  */
 12 
 13 #include <linux/netdevice.h>
 14 #include <linux/notifier.h>
 15 #include <linux/export.h>
 16 
 17 #include <net/fib_rules.h>
 18 #include <net/ipv6.h>
 19 #include <net/addrconf.h>
 20 #include <net/ip6_route.h>
 21 #include <net/netlink.h>
 22 
 23 struct fib6_rule {
 24         struct fib_rule         common;
 25         struct rt6key           src;
 26         struct rt6key           dst;
 27         u8                      tclass;
 28 };
 29 
 30 static bool fib6_rule_matchall(const struct fib_rule *rule)
 31 {
 32         struct fib6_rule *r = container_of(rule, struct fib6_rule, common);
 33 
 34         if (r->dst.plen || r->src.plen || r->tclass)
 35                 return false;
 36         return fib_rule_matchall(rule);
 37 }
 38 
 39 bool fib6_rule_default(const struct fib_rule *rule)
 40 {
 41         if (!fib6_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
 42             rule->l3mdev)
 43                 return false;
 44         if (rule->table != RT6_TABLE_LOCAL && rule->table != RT6_TABLE_MAIN)
 45                 return false;
 46         return true;
 47 }
 48 EXPORT_SYMBOL_GPL(fib6_rule_default);
 49 
 50 int fib6_rules_dump(struct net *net, struct notifier_block *nb)
 51 {
 52         return fib_rules_dump(net, nb, AF_INET6);
 53 }
 54 
 55 unsigned int fib6_rules_seq_read(struct net *net)
 56 {
 57         return fib_rules_seq_read(net, AF_INET6);
 58 }
 59 
 60 /* called with rcu lock held; no reference taken on fib6_info */
 61 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
 62                 struct fib6_result *res, int flags)
 63 {
 64         int err;
 65 
 66         if (net->ipv6.fib6_has_custom_rules) {
 67                 struct fib_lookup_arg arg = {
 68                         .lookup_ptr = fib6_table_lookup,
 69                         .lookup_data = &oif,
 70                         .result = res,
 71                         .flags = FIB_LOOKUP_NOREF,
 72                 };
 73 
 74                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
 75 
 76                 err = fib_rules_lookup(net->ipv6.fib6_rules_ops,
 77                                        flowi6_to_flowi(fl6), flags, &arg);
 78         } else {
 79                 err = fib6_table_lookup(net, net->ipv6.fib6_local_tbl, oif,
 80                                         fl6, res, flags);
 81                 if (err || res->f6i == net->ipv6.fib6_null_entry)
 82                         err = fib6_table_lookup(net, net->ipv6.fib6_main_tbl,
 83                                                 oif, fl6, res, flags);
 84         }
 85 
 86         return err;
 87 }
 88 
 89 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 90                                    const struct sk_buff *skb,
 91                                    int flags, pol_lookup_t lookup)
 92 {
 93         if (net->ipv6.fib6_has_custom_rules) {
 94                 struct fib6_result res = {};
 95                 struct fib_lookup_arg arg = {
 96                         .lookup_ptr = lookup,
 97                         .lookup_data = skb,
 98                         .result = &res,
 99                         .flags = FIB_LOOKUP_NOREF,
100                 };
101 
102                 /* update flow if oif or iif point to device enslaved to l3mdev */
103                 l3mdev_update_flow(net, flowi6_to_flowi(fl6));
104 
105                 fib_rules_lookup(net->ipv6.fib6_rules_ops,
106                                  flowi6_to_flowi(fl6), flags, &arg);
107 
108                 if (res.rt6)
109                         return &res.rt6->dst;
110         } else {
111                 struct rt6_info *rt;
112 
113                 rt = lookup(net, net->ipv6.fib6_local_tbl, fl6, skb, flags);
114                 if (rt != net->ipv6.ip6_null_entry && rt->dst.error != -EAGAIN)
115                         return &rt->dst;
116                 ip6_rt_put_flags(rt, flags);
117                 rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
118                 if (rt->dst.error != -EAGAIN)
119                         return &rt->dst;
120                 ip6_rt_put_flags(rt, flags);
121         }
122 
123         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
124                 dst_hold(&net->ipv6.ip6_null_entry->dst);
125         return &net->ipv6.ip6_null_entry->dst;
126 }
127 
128 static int fib6_rule_saddr(struct net *net, struct fib_rule *rule, int flags,
129                            struct flowi6 *flp6, const struct net_device *dev)
130 {
131         struct fib6_rule *r = (struct fib6_rule *)rule;
132 
133         /* If we need to find a source address for this traffic,
134          * we check the result if it meets requirement of the rule.
135          */
136         if ((rule->flags & FIB_RULE_FIND_SADDR) &&
137             r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
138                 struct in6_addr saddr;
139 
140                 if (ipv6_dev_get_saddr(net, dev, &flp6->daddr,
141                                        rt6_flags2srcprefs(flags), &saddr))
142                         return -EAGAIN;
143 
144                 if (!ipv6_prefix_equal(&saddr, &r->src.addr, r->src.plen))
145                         return -EAGAIN;
146 
147                 flp6->saddr = saddr;
148         }
149 
150         return 0;
151 }
152 
153 static int fib6_rule_action_alt(struct fib_rule *rule, struct flowi *flp,
154                                 int flags, struct fib_lookup_arg *arg)
155 {
156         struct fib6_result *res = arg->result;
157         struct flowi6 *flp6 = &flp->u.ip6;
158         struct net *net = rule->fr_net;
159         struct fib6_table *table;
160         int err, *oif;
161         u32 tb_id;
162 
163         switch (rule->action) {
164         case FR_ACT_TO_TBL:
165                 break;
166         case FR_ACT_UNREACHABLE:
167                 return -ENETUNREACH;
168         case FR_ACT_PROHIBIT:
169                 return -EACCES;
170         case FR_ACT_BLACKHOLE:
171         default:
172                 return -EINVAL;
173         }
174 
175         tb_id = fib_rule_get_table(rule, arg);
176         table = fib6_get_table(net, tb_id);
177         if (!table)
178                 return -EAGAIN;
179 
180         oif = (int *)arg->lookup_data;
181         err = fib6_table_lookup(net, table, *oif, flp6, res, flags);
182         if (!err && res->f6i != net->ipv6.fib6_null_entry)
183                 err = fib6_rule_saddr(net, rule, flags, flp6,
184                                       res->nh->fib_nh_dev);
185         else
186                 err = -EAGAIN;
187 
188         return err;
189 }
190 
191 static int __fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
192                               int flags, struct fib_lookup_arg *arg)
193 {
194         struct fib6_result *res = arg->result;
195         struct flowi6 *flp6 = &flp->u.ip6;
196         struct rt6_info *rt = NULL;
197         struct fib6_table *table;
198         struct net *net = rule->fr_net;
199         pol_lookup_t lookup = arg->lookup_ptr;
200         int err = 0;
201         u32 tb_id;
202 
203         switch (rule->action) {
204         case FR_ACT_TO_TBL:
205                 break;
206         case FR_ACT_UNREACHABLE:
207                 err = -ENETUNREACH;
208                 rt = net->ipv6.ip6_null_entry;
209                 goto discard_pkt;
210         default:
211         case FR_ACT_BLACKHOLE:
212                 err = -EINVAL;
213                 rt = net->ipv6.ip6_blk_hole_entry;
214                 goto discard_pkt;
215         case FR_ACT_PROHIBIT:
216                 err = -EACCES;
217                 rt = net->ipv6.ip6_prohibit_entry;
218                 goto discard_pkt;
219         }
220 
221         tb_id = fib_rule_get_table(rule, arg);
222         table = fib6_get_table(net, tb_id);
223         if (!table) {
224                 err = -EAGAIN;
225                 goto out;
226         }
227 
228         rt = lookup(net, table, flp6, arg->lookup_data, flags);
229         if (rt != net->ipv6.ip6_null_entry) {
230                 err = fib6_rule_saddr(net, rule, flags, flp6,
231                                       ip6_dst_idev(&rt->dst)->dev);
232 
233                 if (err == -EAGAIN)
234                         goto again;
235 
236                 err = rt->dst.error;
237                 if (err != -EAGAIN)
238                         goto out;
239         }
240 again:
241         ip6_rt_put_flags(rt, flags);
242         err = -EAGAIN;
243         rt = NULL;
244         goto out;
245 
246 discard_pkt:
247         if (!(flags & RT6_LOOKUP_F_DST_NOREF))
248                 dst_hold(&rt->dst);
249 out:
250         res->rt6 = rt;
251         return err;
252 }
253 
254 static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
255                             int flags, struct fib_lookup_arg *arg)
256 {
257         if (arg->lookup_ptr == fib6_table_lookup)
258                 return fib6_rule_action_alt(rule, flp, flags, arg);
259 
260         return __fib6_rule_action(rule, flp, flags, arg);
261 }
262 
263 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
264 {
265         struct fib6_result *res = arg->result;
266         struct rt6_info *rt = res->rt6;
267         struct net_device *dev = NULL;
268 
269         if (!rt)
270                 return false;
271 
272         if (rt->rt6i_idev)
273                 dev = rt->rt6i_idev->dev;
274 
275         /* do not accept result if the route does
276          * not meet the required prefix length
277          */
278         if (rt->rt6i_dst.plen <= rule->suppress_prefixlen)
279                 goto suppress_route;
280 
281         /* do not accept result if the route uses a device
282          * belonging to a forbidden interface group
283          */
284         if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
285                 goto suppress_route;
286 
287         return false;
288 
289 suppress_route:
290         if (!(arg->flags & FIB_LOOKUP_NOREF))
291                 ip6_rt_put(rt);
292         return true;
293 }
294 
295 static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
296 {
297         struct fib6_rule *r = (struct fib6_rule *) rule;
298         struct flowi6 *fl6 = &fl->u.ip6;
299 
300         if (r->dst.plen &&
301             !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
302                 return 0;
303 
304         /*
305          * If FIB_RULE_FIND_SADDR is set and we do not have a
306          * source address for the traffic, we defer check for
307          * source address.
308          */
309         if (r->src.plen) {
310                 if (flags & RT6_LOOKUP_F_HAS_SADDR) {
311                         if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
312                                                r->src.plen))
313                                 return 0;
314                 } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
315                         return 0;
316         }
317 
318         if (r->tclass && r->tclass != ip6_tclass(fl6->flowlabel))
319                 return 0;
320 
321         if (rule->ip_proto && (rule->ip_proto != fl6->flowi6_proto))
322                 return 0;
323 
324         if (fib_rule_port_range_set(&rule->sport_range) &&
325             !fib_rule_port_inrange(&rule->sport_range, fl6->fl6_sport))
326                 return 0;
327 
328         if (fib_rule_port_range_set(&rule->dport_range) &&
329             !fib_rule_port_inrange(&rule->dport_range, fl6->fl6_dport))
330                 return 0;
331 
332         return 1;
333 }
334 
335 static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
336         FRA_GENERIC_POLICY,
337 };
338 
339 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
340                                struct fib_rule_hdr *frh,
341                                struct nlattr **tb,
342                                struct netlink_ext_ack *extack)
343 {
344         int err = -EINVAL;
345         struct net *net = sock_net(skb->sk);
346         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
347 
348         if (rule->action == FR_ACT_TO_TBL && !rule->l3mdev) {
349                 if (rule->table == RT6_TABLE_UNSPEC) {
350                         NL_SET_ERR_MSG(extack, "Invalid table");
351                         goto errout;
352                 }
353 
354                 if (fib6_new_table(net, rule->table) == NULL) {
355                         err = -ENOBUFS;
356                         goto errout;
357                 }
358         }
359 
360         if (frh->src_len)
361                 rule6->src.addr = nla_get_in6_addr(tb[FRA_SRC]);
362 
363         if (frh->dst_len)
364                 rule6->dst.addr = nla_get_in6_addr(tb[FRA_DST]);
365 
366         rule6->src.plen = frh->src_len;
367         rule6->dst.plen = frh->dst_len;
368         rule6->tclass = frh->tos;
369 
370         if (fib_rule_requires_fldissect(rule))
371                 net->ipv6.fib6_rules_require_fldissect++;
372 
373         net->ipv6.fib6_has_custom_rules = true;
374         err = 0;
375 errout:
376         return err;
377 }
378 
379 static int fib6_rule_delete(struct fib_rule *rule)
380 {
381         struct net *net = rule->fr_net;
382 
383         if (net->ipv6.fib6_rules_require_fldissect &&
384             fib_rule_requires_fldissect(rule))
385                 net->ipv6.fib6_rules_require_fldissect--;
386 
387         return 0;
388 }
389 
390 static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
391                              struct nlattr **tb)
392 {
393         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
394 
395         if (frh->src_len && (rule6->src.plen != frh->src_len))
396                 return 0;
397 
398         if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
399                 return 0;
400 
401         if (frh->tos && (rule6->tclass != frh->tos))
402                 return 0;
403 
404         if (frh->src_len &&
405             nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
406                 return 0;
407 
408         if (frh->dst_len &&
409             nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
410                 return 0;
411 
412         return 1;
413 }
414 
415 static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
416                           struct fib_rule_hdr *frh)
417 {
418         struct fib6_rule *rule6 = (struct fib6_rule *) rule;
419 
420         frh->dst_len = rule6->dst.plen;
421         frh->src_len = rule6->src.plen;
422         frh->tos = rule6->tclass;
423 
424         if ((rule6->dst.plen &&
425              nla_put_in6_addr(skb, FRA_DST, &rule6->dst.addr)) ||
426             (rule6->src.plen &&
427              nla_put_in6_addr(skb, FRA_SRC, &rule6->src.addr)))
428                 goto nla_put_failure;
429         return 0;
430 
431 nla_put_failure:
432         return -ENOBUFS;
433 }
434 
435 static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
436 {
437         return nla_total_size(16) /* dst */
438                + nla_total_size(16); /* src */
439 }
440 
441 static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
442         .family                 = AF_INET6,
443         .rule_size              = sizeof(struct fib6_rule),
444         .addr_size              = sizeof(struct in6_addr),
445         .action                 = fib6_rule_action,
446         .match                  = fib6_rule_match,
447         .suppress               = fib6_rule_suppress,
448         .configure              = fib6_rule_configure,
449         .delete                 = fib6_rule_delete,
450         .compare                = fib6_rule_compare,
451         .fill                   = fib6_rule_fill,
452         .nlmsg_payload          = fib6_rule_nlmsg_payload,
453         .nlgroup                = RTNLGRP_IPV6_RULE,
454         .policy                 = fib6_rule_policy,
455         .owner                  = THIS_MODULE,
456         .fro_net                = &init_net,
457 };
458 
459 static int __net_init fib6_rules_net_init(struct net *net)
460 {
461         struct fib_rules_ops *ops;
462         int err = -ENOMEM;
463 
464         ops = fib_rules_register(&fib6_rules_ops_template, net);
465         if (IS_ERR(ops))
466                 return PTR_ERR(ops);
467 
468         err = fib_default_rule_add(ops, 0, RT6_TABLE_LOCAL, 0);
469         if (err)
470                 goto out_fib6_rules_ops;
471 
472         err = fib_default_rule_add(ops, 0x7FFE, RT6_TABLE_MAIN, 0);
473         if (err)
474                 goto out_fib6_rules_ops;
475 
476         net->ipv6.fib6_rules_ops = ops;
477         net->ipv6.fib6_rules_require_fldissect = 0;
478 out:
479         return err;
480 
481 out_fib6_rules_ops:
482         fib_rules_unregister(ops);
483         goto out;
484 }
485 
486 static void __net_exit fib6_rules_net_exit(struct net *net)
487 {
488         rtnl_lock();
489         fib_rules_unregister(net->ipv6.fib6_rules_ops);
490         rtnl_unlock();
491 }
492 
493 static struct pernet_operations fib6_rules_net_ops = {
494         .init = fib6_rules_net_init,
495         .exit = fib6_rules_net_exit,
496 };
497 
498 int __init fib6_rules_init(void)
499 {
500         return register_pernet_subsys(&fib6_rules_net_ops);
501 }
502 
503 
504 void fib6_rules_cleanup(void)
505 {
506         unregister_pernet_subsys(&fib6_rules_net_ops);
507 }
508 

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