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Linux/net/ipv6/addrlabel.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * IPv6 Address Label subsystem
  4  * for the IPv6 "Default" Source Address Selection
  5  *
  6  * Copyright (C)2007 USAGI/WIDE Project
  7  */
  8 /*
  9  * Author:
 10  *      YOSHIFUJI Hideaki @ USAGI/WIDE Project <yoshfuji@linux-ipv6.org>
 11  */
 12 
 13 #include <linux/kernel.h>
 14 #include <linux/list.h>
 15 #include <linux/rcupdate.h>
 16 #include <linux/in6.h>
 17 #include <linux/slab.h>
 18 #include <net/addrconf.h>
 19 #include <linux/if_addrlabel.h>
 20 #include <linux/netlink.h>
 21 #include <linux/rtnetlink.h>
 22 
 23 #if 0
 24 #define ADDRLABEL(x...) printk(x)
 25 #else
 26 #define ADDRLABEL(x...) do { ; } while (0)
 27 #endif
 28 
 29 /*
 30  * Policy Table
 31  */
 32 struct ip6addrlbl_entry {
 33         struct in6_addr prefix;
 34         int prefixlen;
 35         int ifindex;
 36         int addrtype;
 37         u32 label;
 38         struct hlist_node list;
 39         struct rcu_head rcu;
 40 };
 41 
 42 /*
 43  * Default policy table (RFC6724 + extensions)
 44  *
 45  * prefix               addr_type       label
 46  * -------------------------------------------------------------------------
 47  * ::1/128              LOOPBACK        0
 48  * ::/0                 N/A             1
 49  * 2002::/16            N/A             2
 50  * ::/96                COMPATv4        3
 51  * ::ffff:0:0/96        V4MAPPED        4
 52  * fc00::/7             N/A             5               ULA (RFC 4193)
 53  * 2001::/32            N/A             6               Teredo (RFC 4380)
 54  * 2001:10::/28         N/A             7               ORCHID (RFC 4843)
 55  * fec0::/10            N/A             11              Site-local
 56  *                                                      (deprecated by RFC3879)
 57  * 3ffe::/16            N/A             12              6bone
 58  *
 59  * Note: 0xffffffff is used if we do not have any policies.
 60  * Note: Labels for ULA and 6to4 are different from labels listed in RFC6724.
 61  */
 62 
 63 #define IPV6_ADDR_LABEL_DEFAULT 0xffffffffUL
 64 
 65 static const __net_initconst struct ip6addrlbl_init_table
 66 {
 67         const struct in6_addr *prefix;
 68         int prefixlen;
 69         u32 label;
 70 } ip6addrlbl_init_table[] = {
 71         {       /* ::/0 */
 72                 .prefix = &in6addr_any,
 73                 .label = 1,
 74         }, {    /* fc00::/7 */
 75                 .prefix = &(struct in6_addr){ { { 0xfc } } } ,
 76                 .prefixlen = 7,
 77                 .label = 5,
 78         }, {    /* fec0::/10 */
 79                 .prefix = &(struct in6_addr){ { { 0xfe, 0xc0 } } },
 80                 .prefixlen = 10,
 81                 .label = 11,
 82         }, {    /* 2002::/16 */
 83                 .prefix = &(struct in6_addr){ { { 0x20, 0x02 } } },
 84                 .prefixlen = 16,
 85                 .label = 2,
 86         }, {    /* 3ffe::/16 */
 87                 .prefix = &(struct in6_addr){ { { 0x3f, 0xfe } } },
 88                 .prefixlen = 16,
 89                 .label = 12,
 90         }, {    /* 2001::/32 */
 91                 .prefix = &(struct in6_addr){ { { 0x20, 0x01 } } },
 92                 .prefixlen = 32,
 93                 .label = 6,
 94         }, {    /* 2001:10::/28 */
 95                 .prefix = &(struct in6_addr){ { { 0x20, 0x01, 0x00, 0x10 } } },
 96                 .prefixlen = 28,
 97                 .label = 7,
 98         }, {    /* ::ffff:0:0 */
 99                 .prefix = &(struct in6_addr){ { { [10] = 0xff, [11] = 0xff } } },
100                 .prefixlen = 96,
101                 .label = 4,
102         }, {    /* ::/96 */
103                 .prefix = &in6addr_any,
104                 .prefixlen = 96,
105                 .label = 3,
106         }, {    /* ::1/128 */
107                 .prefix = &in6addr_loopback,
108                 .prefixlen = 128,
109                 .label = 0,
110         }
111 };
112 
113 /* Find label */
114 static bool __ip6addrlbl_match(const struct ip6addrlbl_entry *p,
115                                const struct in6_addr *addr,
116                                int addrtype, int ifindex)
117 {
118         if (p->ifindex && p->ifindex != ifindex)
119                 return false;
120         if (p->addrtype && p->addrtype != addrtype)
121                 return false;
122         if (!ipv6_prefix_equal(addr, &p->prefix, p->prefixlen))
123                 return false;
124         return true;
125 }
126 
127 static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
128                                                   const struct in6_addr *addr,
129                                                   int type, int ifindex)
130 {
131         struct ip6addrlbl_entry *p;
132 
133         hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
134                 if (__ip6addrlbl_match(p, addr, type, ifindex))
135                         return p;
136         }
137         return NULL;
138 }
139 
140 u32 ipv6_addr_label(struct net *net,
141                     const struct in6_addr *addr, int type, int ifindex)
142 {
143         u32 label;
144         struct ip6addrlbl_entry *p;
145 
146         type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;
147 
148         rcu_read_lock();
149         p = __ipv6_addr_label(net, addr, type, ifindex);
150         label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
151         rcu_read_unlock();
152 
153         ADDRLABEL(KERN_DEBUG "%s(addr=%pI6, type=%d, ifindex=%d) => %08x\n",
154                   __func__, addr, type, ifindex, label);
155 
156         return label;
157 }
158 
159 /* allocate one entry */
160 static struct ip6addrlbl_entry *ip6addrlbl_alloc(const struct in6_addr *prefix,
161                                                  int prefixlen, int ifindex,
162                                                  u32 label)
163 {
164         struct ip6addrlbl_entry *newp;
165         int addrtype;
166 
167         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)\n",
168                   __func__, prefix, prefixlen, ifindex, (unsigned int)label);
169 
170         addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);
171 
172         switch (addrtype) {
173         case IPV6_ADDR_MAPPED:
174                 if (prefixlen > 96)
175                         return ERR_PTR(-EINVAL);
176                 if (prefixlen < 96)
177                         addrtype = 0;
178                 break;
179         case IPV6_ADDR_COMPATv4:
180                 if (prefixlen != 96)
181                         addrtype = 0;
182                 break;
183         case IPV6_ADDR_LOOPBACK:
184                 if (prefixlen != 128)
185                         addrtype = 0;
186                 break;
187         }
188 
189         newp = kmalloc(sizeof(*newp), GFP_KERNEL);
190         if (!newp)
191                 return ERR_PTR(-ENOMEM);
192 
193         ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
194         newp->prefixlen = prefixlen;
195         newp->ifindex = ifindex;
196         newp->addrtype = addrtype;
197         newp->label = label;
198         INIT_HLIST_NODE(&newp->list);
199         return newp;
200 }
201 
202 /* add a label */
203 static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp,
204                             int replace)
205 {
206         struct ip6addrlbl_entry *last = NULL, *p = NULL;
207         struct hlist_node *n;
208         int ret = 0;
209 
210         ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)\n", __func__, newp,
211                   replace);
212 
213         hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
214                 if (p->prefixlen == newp->prefixlen &&
215                     p->ifindex == newp->ifindex &&
216                     ipv6_addr_equal(&p->prefix, &newp->prefix)) {
217                         if (!replace) {
218                                 ret = -EEXIST;
219                                 goto out;
220                         }
221                         hlist_replace_rcu(&p->list, &newp->list);
222                         kfree_rcu(p, rcu);
223                         goto out;
224                 } else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
225                            (p->prefixlen < newp->prefixlen)) {
226                         hlist_add_before_rcu(&newp->list, &p->list);
227                         goto out;
228                 }
229                 last = p;
230         }
231         if (last)
232                 hlist_add_behind_rcu(&newp->list, &last->list);
233         else
234                 hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);
235 out:
236         if (!ret)
237                 net->ipv6.ip6addrlbl_table.seq++;
238         return ret;
239 }
240 
241 /* add a label */
242 static int ip6addrlbl_add(struct net *net,
243                           const struct in6_addr *prefix, int prefixlen,
244                           int ifindex, u32 label, int replace)
245 {
246         struct ip6addrlbl_entry *newp;
247         int ret = 0;
248 
249         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)\n",
250                   __func__, prefix, prefixlen, ifindex, (unsigned int)label,
251                   replace);
252 
253         newp = ip6addrlbl_alloc(prefix, prefixlen, ifindex, label);
254         if (IS_ERR(newp))
255                 return PTR_ERR(newp);
256         spin_lock(&net->ipv6.ip6addrlbl_table.lock);
257         ret = __ip6addrlbl_add(net, newp, replace);
258         spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
259         if (ret)
260                 kfree(newp);
261         return ret;
262 }
263 
264 /* remove a label */
265 static int __ip6addrlbl_del(struct net *net,
266                             const struct in6_addr *prefix, int prefixlen,
267                             int ifindex)
268 {
269         struct ip6addrlbl_entry *p = NULL;
270         struct hlist_node *n;
271         int ret = -ESRCH;
272 
273         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
274                   __func__, prefix, prefixlen, ifindex);
275 
276         hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
277                 if (p->prefixlen == prefixlen &&
278                     p->ifindex == ifindex &&
279                     ipv6_addr_equal(&p->prefix, prefix)) {
280                         hlist_del_rcu(&p->list);
281                         kfree_rcu(p, rcu);
282                         ret = 0;
283                         break;
284                 }
285         }
286         return ret;
287 }
288 
289 static int ip6addrlbl_del(struct net *net,
290                           const struct in6_addr *prefix, int prefixlen,
291                           int ifindex)
292 {
293         struct in6_addr prefix_buf;
294         int ret;
295 
296         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
297                   __func__, prefix, prefixlen, ifindex);
298 
299         ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
300         spin_lock(&net->ipv6.ip6addrlbl_table.lock);
301         ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
302         spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
303         return ret;
304 }
305 
306 /* add default label */
307 static int __net_init ip6addrlbl_net_init(struct net *net)
308 {
309         int err = 0;
310         int i;
311 
312         ADDRLABEL(KERN_DEBUG "%s\n", __func__);
313 
314         spin_lock_init(&net->ipv6.ip6addrlbl_table.lock);
315         INIT_HLIST_HEAD(&net->ipv6.ip6addrlbl_table.head);
316 
317         for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
318                 int ret = ip6addrlbl_add(net,
319                                          ip6addrlbl_init_table[i].prefix,
320                                          ip6addrlbl_init_table[i].prefixlen,
321                                          0,
322                                          ip6addrlbl_init_table[i].label, 0);
323                 /* XXX: should we free all rules when we catch an error? */
324                 if (ret && (!err || err != -ENOMEM))
325                         err = ret;
326         }
327         return err;
328 }
329 
330 static void __net_exit ip6addrlbl_net_exit(struct net *net)
331 {
332         struct ip6addrlbl_entry *p = NULL;
333         struct hlist_node *n;
334 
335         /* Remove all labels belonging to the exiting net */
336         spin_lock(&net->ipv6.ip6addrlbl_table.lock);
337         hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
338                 hlist_del_rcu(&p->list);
339                 kfree_rcu(p, rcu);
340         }
341         spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
342 }
343 
344 static struct pernet_operations ipv6_addr_label_ops = {
345         .init = ip6addrlbl_net_init,
346         .exit = ip6addrlbl_net_exit,
347 };
348 
349 int __init ipv6_addr_label_init(void)
350 {
351         return register_pernet_subsys(&ipv6_addr_label_ops);
352 }
353 
354 void ipv6_addr_label_cleanup(void)
355 {
356         unregister_pernet_subsys(&ipv6_addr_label_ops);
357 }
358 
359 static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
360         [IFAL_ADDRESS]          = { .len = sizeof(struct in6_addr), },
361         [IFAL_LABEL]            = { .len = sizeof(u32), },
362 };
363 
364 static bool addrlbl_ifindex_exists(struct net *net, int ifindex)
365 {
366 
367         struct net_device *dev;
368 
369         rcu_read_lock();
370         dev = dev_get_by_index_rcu(net, ifindex);
371         rcu_read_unlock();
372 
373         return dev != NULL;
374 }
375 
376 static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
377                              struct netlink_ext_ack *extack)
378 {
379         struct net *net = sock_net(skb->sk);
380         struct ifaddrlblmsg *ifal;
381         struct nlattr *tb[IFAL_MAX+1];
382         struct in6_addr *pfx;
383         u32 label;
384         int err = 0;
385 
386         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy,
387                           extack);
388         if (err < 0)
389                 return err;
390 
391         ifal = nlmsg_data(nlh);
392 
393         if (ifal->ifal_family != AF_INET6 ||
394             ifal->ifal_prefixlen > 128)
395                 return -EINVAL;
396 
397         if (!tb[IFAL_ADDRESS])
398                 return -EINVAL;
399         pfx = nla_data(tb[IFAL_ADDRESS]);
400 
401         if (!tb[IFAL_LABEL])
402                 return -EINVAL;
403         label = nla_get_u32(tb[IFAL_LABEL]);
404         if (label == IPV6_ADDR_LABEL_DEFAULT)
405                 return -EINVAL;
406 
407         switch (nlh->nlmsg_type) {
408         case RTM_NEWADDRLABEL:
409                 if (ifal->ifal_index &&
410                     !addrlbl_ifindex_exists(net, ifal->ifal_index))
411                         return -EINVAL;
412 
413                 err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,
414                                      ifal->ifal_index, label,
415                                      nlh->nlmsg_flags & NLM_F_REPLACE);
416                 break;
417         case RTM_DELADDRLABEL:
418                 err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,
419                                      ifal->ifal_index);
420                 break;
421         default:
422                 err = -EOPNOTSUPP;
423         }
424         return err;
425 }
426 
427 static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
428                               int prefixlen, int ifindex, u32 lseq)
429 {
430         struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
431         ifal->ifal_family = AF_INET6;
432         ifal->ifal_prefixlen = prefixlen;
433         ifal->ifal_flags = 0;
434         ifal->ifal_index = ifindex;
435         ifal->ifal_seq = lseq;
436 };
437 
438 static int ip6addrlbl_fill(struct sk_buff *skb,
439                            struct ip6addrlbl_entry *p,
440                            u32 lseq,
441                            u32 portid, u32 seq, int event,
442                            unsigned int flags)
443 {
444         struct nlmsghdr *nlh = nlmsg_put(skb, portid, seq, event,
445                                          sizeof(struct ifaddrlblmsg), flags);
446         if (!nlh)
447                 return -EMSGSIZE;
448 
449         ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);
450 
451         if (nla_put_in6_addr(skb, IFAL_ADDRESS, &p->prefix) < 0 ||
452             nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
453                 nlmsg_cancel(skb, nlh);
454                 return -EMSGSIZE;
455         }
456 
457         nlmsg_end(skb, nlh);
458         return 0;
459 }
460 
461 static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
462 {
463         struct net *net = sock_net(skb->sk);
464         struct ip6addrlbl_entry *p;
465         int idx = 0, s_idx = cb->args[0];
466         int err;
467 
468         rcu_read_lock();
469         hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
470                 if (idx >= s_idx) {
471                         err = ip6addrlbl_fill(skb, p,
472                                               net->ipv6.ip6addrlbl_table.seq,
473                                               NETLINK_CB(cb->skb).portid,
474                                               cb->nlh->nlmsg_seq,
475                                               RTM_NEWADDRLABEL,
476                                               NLM_F_MULTI);
477                         if (err < 0)
478                                 break;
479                 }
480                 idx++;
481         }
482         rcu_read_unlock();
483         cb->args[0] = idx;
484         return skb->len;
485 }
486 
487 static inline int ip6addrlbl_msgsize(void)
488 {
489         return NLMSG_ALIGN(sizeof(struct ifaddrlblmsg))
490                 + nla_total_size(16)    /* IFAL_ADDRESS */
491                 + nla_total_size(4);    /* IFAL_LABEL */
492 }
493 
494 static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
495                           struct netlink_ext_ack *extack)
496 {
497         struct net *net = sock_net(in_skb->sk);
498         struct ifaddrlblmsg *ifal;
499         struct nlattr *tb[IFAL_MAX+1];
500         struct in6_addr *addr;
501         u32 lseq;
502         int err = 0;
503         struct ip6addrlbl_entry *p;
504         struct sk_buff *skb;
505 
506         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy,
507                           extack);
508         if (err < 0)
509                 return err;
510 
511         ifal = nlmsg_data(nlh);
512 
513         if (ifal->ifal_family != AF_INET6 ||
514             ifal->ifal_prefixlen != 128)
515                 return -EINVAL;
516 
517         if (ifal->ifal_index &&
518             !addrlbl_ifindex_exists(net, ifal->ifal_index))
519                 return -EINVAL;
520 
521         if (!tb[IFAL_ADDRESS])
522                 return -EINVAL;
523         addr = nla_data(tb[IFAL_ADDRESS]);
524 
525         skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL);
526         if (!skb)
527                 return -ENOBUFS;
528 
529         err = -ESRCH;
530 
531         rcu_read_lock();
532         p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
533         lseq = net->ipv6.ip6addrlbl_table.seq;
534         if (p)
535                 err = ip6addrlbl_fill(skb, p, lseq,
536                                       NETLINK_CB(in_skb).portid,
537                                       nlh->nlmsg_seq,
538                                       RTM_NEWADDRLABEL, 0);
539         rcu_read_unlock();
540 
541         if (err < 0) {
542                 WARN_ON(err == -EMSGSIZE);
543                 kfree_skb(skb);
544         } else {
545                 err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
546         }
547         return err;
548 }
549 
550 int __init ipv6_addr_label_rtnl_register(void)
551 {
552         int ret;
553 
554         ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_NEWADDRLABEL,
555                                    ip6addrlbl_newdel,
556                                    NULL, RTNL_FLAG_DOIT_UNLOCKED);
557         if (ret < 0)
558                 return ret;
559         ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_DELADDRLABEL,
560                                    ip6addrlbl_newdel,
561                                    NULL, RTNL_FLAG_DOIT_UNLOCKED);
562         if (ret < 0)
563                 return ret;
564         ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETADDRLABEL,
565                                    ip6addrlbl_get,
566                                    ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED);
567         return ret;
568 }
569 

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