1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * NETLINK Kernel-user communication protocol.
4 *
5 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
6 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
7 * Patrick McHardy <kaber@trash.net>
8 *
9 * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith
10 * added netlink_proto_exit
11 * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br>
12 * use nlk_sk, as sk->protinfo is on a diet 8)
13 * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
14 * - inc module use count of module that owns
15 * the kernel socket in case userspace opens
16 * socket of same protocol
17 * - remove all module support, since netlink is
18 * mandatory if CONFIG_NET=y these days
19 */
20
21 #include <linux/module.h>
22
23 #include <linux/bpf.h>
24 #include <linux/capability.h>
25 #include <linux/kernel.h>
26 #include <linux/filter.h>
27 #include <linux/init.h>
28 #include <linux/signal.h>
29 #include <linux/sched.h>
30 #include <linux/errno.h>
31 #include <linux/string.h>
32 #include <linux/stat.h>
33 #include <linux/socket.h>
34 #include <linux/un.h>
35 #include <linux/fcntl.h>
36 #include <linux/termios.h>
37 #include <linux/sockios.h>
38 #include <linux/net.h>
39 #include <linux/fs.h>
40 #include <linux/slab.h>
41 #include <linux/uaccess.h>
42 #include <linux/skbuff.h>
43 #include <linux/netdevice.h>
44 #include <linux/rtnetlink.h>
45 #include <linux/proc_fs.h>
46 #include <linux/seq_file.h>
47 #include <linux/notifier.h>
48 #include <linux/security.h>
49 #include <linux/jhash.h>
50 #include <linux/jiffies.h>
51 #include <linux/random.h>
52 #include <linux/bitops.h>
53 #include <linux/mm.h>
54 #include <linux/types.h>
55 #include <linux/audit.h>
56 #include <linux/mutex.h>
57 #include <linux/vmalloc.h>
58 #include <linux/if_arp.h>
59 #include <linux/rhashtable.h>
60 #include <asm/cacheflush.h>
61 #include <linux/hash.h>
62 #include <linux/net_namespace.h>
63 #include <linux/nospec.h>
64 #include <linux/btf_ids.h>
65
66 #include <net/net_namespace.h>
67 #include <net/netns/generic.h>
68 #include <net/sock.h>
69 #include <net/scm.h>
70 #include <net/netlink.h>
71 #define CREATE_TRACE_POINTS
72 #include <trace/events/netlink.h>
73
74 #include "af_netlink.h"
75 #include "genetlink.h"
76
77 struct listeners {
78 struct rcu_head rcu;
79 unsigned long masks[];
80 };
81
82 /* state bits */
83 #define NETLINK_S_CONGESTED 0x0
84
netlink_is_kernel(struct sock * sk)85 static inline int netlink_is_kernel(struct sock *sk)
86 {
87 return nlk_test_bit(KERNEL_SOCKET, sk);
88 }
89
90 struct netlink_table *nl_table __read_mostly;
91 EXPORT_SYMBOL_GPL(nl_table);
92
93 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
94
95 static struct lock_class_key nlk_cb_mutex_keys[MAX_LINKS];
96
97 static const char *const nlk_cb_mutex_key_strings[MAX_LINKS + 1] = {
98 "nlk_cb_mutex-ROUTE",
99 "nlk_cb_mutex-1",
100 "nlk_cb_mutex-USERSOCK",
101 "nlk_cb_mutex-FIREWALL",
102 "nlk_cb_mutex-SOCK_DIAG",
103 "nlk_cb_mutex-NFLOG",
104 "nlk_cb_mutex-XFRM",
105 "nlk_cb_mutex-SELINUX",
106 "nlk_cb_mutex-ISCSI",
107 "nlk_cb_mutex-AUDIT",
108 "nlk_cb_mutex-FIB_LOOKUP",
109 "nlk_cb_mutex-CONNECTOR",
110 "nlk_cb_mutex-NETFILTER",
111 "nlk_cb_mutex-IP6_FW",
112 "nlk_cb_mutex-DNRTMSG",
113 "nlk_cb_mutex-KOBJECT_UEVENT",
114 "nlk_cb_mutex-GENERIC",
115 "nlk_cb_mutex-17",
116 "nlk_cb_mutex-SCSITRANSPORT",
117 "nlk_cb_mutex-ECRYPTFS",
118 "nlk_cb_mutex-RDMA",
119 "nlk_cb_mutex-CRYPTO",
120 "nlk_cb_mutex-SMC",
121 "nlk_cb_mutex-23",
122 "nlk_cb_mutex-24",
123 "nlk_cb_mutex-25",
124 "nlk_cb_mutex-26",
125 "nlk_cb_mutex-27",
126 "nlk_cb_mutex-28",
127 "nlk_cb_mutex-29",
128 "nlk_cb_mutex-30",
129 "nlk_cb_mutex-31",
130 "nlk_cb_mutex-MAX_LINKS"
131 };
132
133 static int netlink_dump(struct sock *sk, bool lock_taken);
134
135 /* nl_table locking explained:
136 * Lookup and traversal are protected with an RCU read-side lock. Insertion
137 * and removal are protected with per bucket lock while using RCU list
138 * modification primitives and may run in parallel to RCU protected lookups.
139 * Destruction of the Netlink socket may only occur *after* nl_table_lock has
140 * been acquired * either during or after the socket has been removed from
141 * the list and after an RCU grace period.
142 */
143 DEFINE_RWLOCK(nl_table_lock);
144 EXPORT_SYMBOL_GPL(nl_table_lock);
145 static atomic_t nl_table_users = ATOMIC_INIT(0);
146
147 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
148
149 static BLOCKING_NOTIFIER_HEAD(netlink_chain);
150
151
152 static const struct rhashtable_params netlink_rhashtable_params;
153
do_trace_netlink_extack(const char * msg)154 void do_trace_netlink_extack(const char *msg)
155 {
156 trace_netlink_extack(msg);
157 }
158 EXPORT_SYMBOL(do_trace_netlink_extack);
159
netlink_group_mask(u32 group)160 static inline u32 netlink_group_mask(u32 group)
161 {
162 if (group > 32)
163 return 0;
164 return group ? 1 << (group - 1) : 0;
165 }
166
netlink_to_full_skb(const struct sk_buff * skb,gfp_t gfp_mask)167 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
168 gfp_t gfp_mask)
169 {
170 unsigned int len = skb->len;
171 struct sk_buff *new;
172
173 new = alloc_skb(len, gfp_mask);
174 if (new == NULL)
175 return NULL;
176
177 NETLINK_CB(new).portid = NETLINK_CB(skb).portid;
178 NETLINK_CB(new).dst_group = NETLINK_CB(skb).dst_group;
179 NETLINK_CB(new).creds = NETLINK_CB(skb).creds;
180
181 skb_put_data(new, skb->data, len);
182 return new;
183 }
184
185 static unsigned int netlink_tap_net_id;
186
187 struct netlink_tap_net {
188 struct list_head netlink_tap_all;
189 struct mutex netlink_tap_lock;
190 };
191
netlink_add_tap(struct netlink_tap * nt)192 int netlink_add_tap(struct netlink_tap *nt)
193 {
194 struct net *net = dev_net(nt->dev);
195 struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
196
197 if (unlikely(nt->dev->type != ARPHRD_NETLINK))
198 return -EINVAL;
199
200 mutex_lock(&nn->netlink_tap_lock);
201 list_add_rcu(&nt->list, &nn->netlink_tap_all);
202 mutex_unlock(&nn->netlink_tap_lock);
203
204 __module_get(nt->module);
205
206 return 0;
207 }
208 EXPORT_SYMBOL_GPL(netlink_add_tap);
209
__netlink_remove_tap(struct netlink_tap * nt)210 static int __netlink_remove_tap(struct netlink_tap *nt)
211 {
212 struct net *net = dev_net(nt->dev);
213 struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
214 bool found = false;
215 struct netlink_tap *tmp;
216
217 mutex_lock(&nn->netlink_tap_lock);
218
219 list_for_each_entry(tmp, &nn->netlink_tap_all, list) {
220 if (nt == tmp) {
221 list_del_rcu(&nt->list);
222 found = true;
223 goto out;
224 }
225 }
226
227 pr_warn("__netlink_remove_tap: %p not found\n", nt);
228 out:
229 mutex_unlock(&nn->netlink_tap_lock);
230
231 if (found)
232 module_put(nt->module);
233
234 return found ? 0 : -ENODEV;
235 }
236
netlink_remove_tap(struct netlink_tap * nt)237 int netlink_remove_tap(struct netlink_tap *nt)
238 {
239 int ret;
240
241 ret = __netlink_remove_tap(nt);
242 synchronize_net();
243
244 return ret;
245 }
246 EXPORT_SYMBOL_GPL(netlink_remove_tap);
247
netlink_tap_init_net(struct net * net)248 static __net_init int netlink_tap_init_net(struct net *net)
249 {
250 struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
251
252 INIT_LIST_HEAD(&nn->netlink_tap_all);
253 mutex_init(&nn->netlink_tap_lock);
254 return 0;
255 }
256
257 static struct pernet_operations netlink_tap_net_ops = {
258 .init = netlink_tap_init_net,
259 .id = &netlink_tap_net_id,
260 .size = sizeof(struct netlink_tap_net),
261 };
262
netlink_filter_tap(const struct sk_buff * skb)263 static bool netlink_filter_tap(const struct sk_buff *skb)
264 {
265 struct sock *sk = skb->sk;
266
267 /* We take the more conservative approach and
268 * whitelist socket protocols that may pass.
269 */
270 switch (sk->sk_protocol) {
271 case NETLINK_ROUTE:
272 case NETLINK_USERSOCK:
273 case NETLINK_SOCK_DIAG:
274 case NETLINK_NFLOG:
275 case NETLINK_XFRM:
276 case NETLINK_FIB_LOOKUP:
277 case NETLINK_NETFILTER:
278 case NETLINK_GENERIC:
279 return true;
280 }
281
282 return false;
283 }
284
__netlink_deliver_tap_skb(struct sk_buff * skb,struct net_device * dev)285 static int __netlink_deliver_tap_skb(struct sk_buff *skb,
286 struct net_device *dev)
287 {
288 struct sk_buff *nskb;
289 struct sock *sk = skb->sk;
290 int ret = -ENOMEM;
291
292 if (!net_eq(dev_net(dev), sock_net(sk)))
293 return 0;
294
295 dev_hold(dev);
296
297 if (is_vmalloc_addr(skb->head))
298 nskb = netlink_to_full_skb(skb, GFP_ATOMIC);
299 else
300 nskb = skb_clone(skb, GFP_ATOMIC);
301 if (nskb) {
302 nskb->dev = dev;
303 nskb->protocol = htons((u16) sk->sk_protocol);
304 nskb->pkt_type = netlink_is_kernel(sk) ?
305 PACKET_KERNEL : PACKET_USER;
306 skb_reset_network_header(nskb);
307 ret = dev_queue_xmit(nskb);
308 if (unlikely(ret > 0))
309 ret = net_xmit_errno(ret);
310 }
311
312 dev_put(dev);
313 return ret;
314 }
315
__netlink_deliver_tap(struct sk_buff * skb,struct netlink_tap_net * nn)316 static void __netlink_deliver_tap(struct sk_buff *skb, struct netlink_tap_net *nn)
317 {
318 int ret;
319 struct netlink_tap *tmp;
320
321 if (!netlink_filter_tap(skb))
322 return;
323
324 list_for_each_entry_rcu(tmp, &nn->netlink_tap_all, list) {
325 ret = __netlink_deliver_tap_skb(skb, tmp->dev);
326 if (unlikely(ret))
327 break;
328 }
329 }
330
netlink_deliver_tap(struct net * net,struct sk_buff * skb)331 static void netlink_deliver_tap(struct net *net, struct sk_buff *skb)
332 {
333 struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
334
335 rcu_read_lock();
336
337 if (unlikely(!list_empty(&nn->netlink_tap_all)))
338 __netlink_deliver_tap(skb, nn);
339
340 rcu_read_unlock();
341 }
342
netlink_deliver_tap_kernel(struct sock * dst,struct sock * src,struct sk_buff * skb)343 static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
344 struct sk_buff *skb)
345 {
346 if (!(netlink_is_kernel(dst) && netlink_is_kernel(src)))
347 netlink_deliver_tap(sock_net(dst), skb);
348 }
349
netlink_overrun(struct sock * sk)350 static void netlink_overrun(struct sock *sk)
351 {
352 if (!nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
353 if (!test_and_set_bit(NETLINK_S_CONGESTED,
354 &nlk_sk(sk)->state)) {
355 WRITE_ONCE(sk->sk_err, ENOBUFS);
356 sk_error_report(sk);
357 }
358 }
359 atomic_inc(&sk->sk_drops);
360 }
361
netlink_rcv_wake(struct sock * sk)362 static void netlink_rcv_wake(struct sock *sk)
363 {
364 struct netlink_sock *nlk = nlk_sk(sk);
365
366 if (skb_queue_empty_lockless(&sk->sk_receive_queue))
367 clear_bit(NETLINK_S_CONGESTED, &nlk->state);
368 if (!test_bit(NETLINK_S_CONGESTED, &nlk->state))
369 wake_up_interruptible(&nlk->wait);
370 }
371
netlink_skb_destructor(struct sk_buff * skb)372 static void netlink_skb_destructor(struct sk_buff *skb)
373 {
374 if (is_vmalloc_addr(skb->head)) {
375 if (!skb->cloned ||
376 !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
377 vfree_atomic(skb->head);
378
379 skb->head = NULL;
380 }
381 if (skb->sk != NULL)
382 sock_rfree(skb);
383 }
384
netlink_skb_set_owner_r(struct sk_buff * skb,struct sock * sk)385 static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
386 {
387 WARN_ON(skb->sk != NULL);
388 skb->sk = sk;
389 skb->destructor = netlink_skb_destructor;
390 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
391 sk_mem_charge(sk, skb->truesize);
392 }
393
netlink_sock_destruct(struct sock * sk)394 static void netlink_sock_destruct(struct sock *sk)
395 {
396 skb_queue_purge(&sk->sk_receive_queue);
397
398 if (!sock_flag(sk, SOCK_DEAD)) {
399 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
400 return;
401 }
402
403 WARN_ON(atomic_read(&sk->sk_rmem_alloc));
404 WARN_ON(refcount_read(&sk->sk_wmem_alloc));
405 WARN_ON(nlk_sk(sk)->groups);
406 }
407
408 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
409 * SMP. Look, when several writers sleep and reader wakes them up, all but one
410 * immediately hit write lock and grab all the cpus. Exclusive sleep solves
411 * this, _but_ remember, it adds useless work on UP machines.
412 */
413
netlink_table_grab(void)414 void netlink_table_grab(void)
415 __acquires(nl_table_lock)
416 {
417 might_sleep();
418
419 write_lock_irq(&nl_table_lock);
420
421 if (atomic_read(&nl_table_users)) {
422 DECLARE_WAITQUEUE(wait, current);
423
424 add_wait_queue_exclusive(&nl_table_wait, &wait);
425 for (;;) {
426 set_current_state(TASK_UNINTERRUPTIBLE);
427 if (atomic_read(&nl_table_users) == 0)
428 break;
429 write_unlock_irq(&nl_table_lock);
430 schedule();
431 write_lock_irq(&nl_table_lock);
432 }
433
434 __set_current_state(TASK_RUNNING);
435 remove_wait_queue(&nl_table_wait, &wait);
436 }
437 }
438
netlink_table_ungrab(void)439 void netlink_table_ungrab(void)
440 __releases(nl_table_lock)
441 {
442 write_unlock_irq(&nl_table_lock);
443 wake_up(&nl_table_wait);
444 }
445
446 static inline void
netlink_lock_table(void)447 netlink_lock_table(void)
448 {
449 unsigned long flags;
450
451 /* read_lock() synchronizes us to netlink_table_grab */
452
453 read_lock_irqsave(&nl_table_lock, flags);
454 atomic_inc(&nl_table_users);
455 read_unlock_irqrestore(&nl_table_lock, flags);
456 }
457
458 static inline void
netlink_unlock_table(void)459 netlink_unlock_table(void)
460 {
461 if (atomic_dec_and_test(&nl_table_users))
462 wake_up(&nl_table_wait);
463 }
464
465 struct netlink_compare_arg
466 {
467 possible_net_t pnet;
468 u32 portid;
469 };
470
471 /* Doing sizeof directly may yield 4 extra bytes on 64-bit. */
472 #define netlink_compare_arg_len \
473 (offsetof(struct netlink_compare_arg, portid) + sizeof(u32))
474
netlink_compare(struct rhashtable_compare_arg * arg,const void * ptr)475 static inline int netlink_compare(struct rhashtable_compare_arg *arg,
476 const void *ptr)
477 {
478 const struct netlink_compare_arg *x = arg->key;
479 const struct netlink_sock *nlk = ptr;
480
481 return nlk->portid != x->portid ||
482 !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
483 }
484
netlink_compare_arg_init(struct netlink_compare_arg * arg,struct net * net,u32 portid)485 static void netlink_compare_arg_init(struct netlink_compare_arg *arg,
486 struct net *net, u32 portid)
487 {
488 memset(arg, 0, sizeof(*arg));
489 write_pnet(&arg->pnet, net);
490 arg->portid = portid;
491 }
492
__netlink_lookup(struct netlink_table * table,u32 portid,struct net * net)493 static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
494 struct net *net)
495 {
496 struct netlink_compare_arg arg;
497
498 netlink_compare_arg_init(&arg, net, portid);
499 return rhashtable_lookup_fast(&table->hash, &arg,
500 netlink_rhashtable_params);
501 }
502
__netlink_insert(struct netlink_table * table,struct sock * sk)503 static int __netlink_insert(struct netlink_table *table, struct sock *sk)
504 {
505 struct netlink_compare_arg arg;
506
507 netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
508 return rhashtable_lookup_insert_key(&table->hash, &arg,
509 &nlk_sk(sk)->node,
510 netlink_rhashtable_params);
511 }
512
netlink_lookup(struct net * net,int protocol,u32 portid)513 static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
514 {
515 struct netlink_table *table = &nl_table[protocol];
516 struct sock *sk;
517
518 rcu_read_lock();
519 sk = __netlink_lookup(table, portid, net);
520 if (sk)
521 sock_hold(sk);
522 rcu_read_unlock();
523
524 return sk;
525 }
526
527 static const struct proto_ops netlink_ops;
528
529 static void
netlink_update_listeners(struct sock * sk)530 netlink_update_listeners(struct sock *sk)
531 {
532 struct netlink_table *tbl = &nl_table[sk->sk_protocol];
533 unsigned long mask;
534 unsigned int i;
535 struct listeners *listeners;
536
537 listeners = nl_deref_protected(tbl->listeners);
538 if (!listeners)
539 return;
540
541 for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
542 mask = 0;
543 sk_for_each_bound(sk, &tbl->mc_list) {
544 if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
545 mask |= nlk_sk(sk)->groups[i];
546 }
547 listeners->masks[i] = mask;
548 }
549 /* this function is only called with the netlink table "grabbed", which
550 * makes sure updates are visible before bind or setsockopt return. */
551 }
552
netlink_insert(struct sock * sk,u32 portid)553 static int netlink_insert(struct sock *sk, u32 portid)
554 {
555 struct netlink_table *table = &nl_table[sk->sk_protocol];
556 int err;
557
558 lock_sock(sk);
559
560 err = nlk_sk(sk)->portid == portid ? 0 : -EBUSY;
561 if (nlk_sk(sk)->bound)
562 goto err;
563
564 /* portid can be read locklessly from netlink_getname(). */
565 WRITE_ONCE(nlk_sk(sk)->portid, portid);
566
567 sock_hold(sk);
568
569 err = __netlink_insert(table, sk);
570 if (err) {
571 /* In case the hashtable backend returns with -EBUSY
572 * from here, it must not escape to the caller.
573 */
574 if (unlikely(err == -EBUSY))
575 err = -EOVERFLOW;
576 if (err == -EEXIST)
577 err = -EADDRINUSE;
578 sock_put(sk);
579 goto err;
580 }
581
582 /* We need to ensure that the socket is hashed and visible. */
583 smp_wmb();
584 /* Paired with lockless reads from netlink_bind(),
585 * netlink_connect() and netlink_sendmsg().
586 */
587 WRITE_ONCE(nlk_sk(sk)->bound, portid);
588
589 err:
590 release_sock(sk);
591 return err;
592 }
593
netlink_remove(struct sock * sk)594 static void netlink_remove(struct sock *sk)
595 {
596 struct netlink_table *table;
597
598 table = &nl_table[sk->sk_protocol];
599 if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node,
600 netlink_rhashtable_params)) {
601 WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
602 __sock_put(sk);
603 }
604
605 netlink_table_grab();
606 if (nlk_sk(sk)->subscriptions) {
607 __sk_del_bind_node(sk);
608 netlink_update_listeners(sk);
609 }
610 if (sk->sk_protocol == NETLINK_GENERIC)
611 atomic_inc(&genl_sk_destructing_cnt);
612 netlink_table_ungrab();
613 }
614
615 static struct proto netlink_proto = {
616 .name = "NETLINK",
617 .owner = THIS_MODULE,
618 .obj_size = sizeof(struct netlink_sock),
619 };
620
__netlink_create(struct net * net,struct socket * sock,int protocol,int kern)621 static int __netlink_create(struct net *net, struct socket *sock,
622 int protocol, int kern)
623 {
624 struct sock *sk;
625 struct netlink_sock *nlk;
626
627 sock->ops = &netlink_ops;
628
629 sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto, kern);
630 if (!sk)
631 return -ENOMEM;
632
633 sock_init_data(sock, sk);
634
635 nlk = nlk_sk(sk);
636 mutex_init(&nlk->nl_cb_mutex);
637 lockdep_set_class_and_name(&nlk->nl_cb_mutex,
638 nlk_cb_mutex_keys + protocol,
639 nlk_cb_mutex_key_strings[protocol]);
640 init_waitqueue_head(&nlk->wait);
641
642 sk->sk_destruct = netlink_sock_destruct;
643 sk->sk_protocol = protocol;
644 return 0;
645 }
646
netlink_create(struct net * net,struct socket * sock,int protocol,int kern)647 static int netlink_create(struct net *net, struct socket *sock, int protocol,
648 int kern)
649 {
650 struct module *module = NULL;
651 struct netlink_sock *nlk;
652 int (*bind)(struct net *net, int group);
653 void (*unbind)(struct net *net, int group);
654 void (*release)(struct sock *sock, unsigned long *groups);
655 int err = 0;
656
657 sock->state = SS_UNCONNECTED;
658
659 if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
660 return -ESOCKTNOSUPPORT;
661
662 if (protocol < 0 || protocol >= MAX_LINKS)
663 return -EPROTONOSUPPORT;
664 protocol = array_index_nospec(protocol, MAX_LINKS);
665
666 netlink_lock_table();
667 #ifdef CONFIG_MODULES
668 if (!nl_table[protocol].registered) {
669 netlink_unlock_table();
670 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
671 netlink_lock_table();
672 }
673 #endif
674 if (nl_table[protocol].registered &&
675 try_module_get(nl_table[protocol].module))
676 module = nl_table[protocol].module;
677 else
678 err = -EPROTONOSUPPORT;
679 bind = nl_table[protocol].bind;
680 unbind = nl_table[protocol].unbind;
681 release = nl_table[protocol].release;
682 netlink_unlock_table();
683
684 if (err < 0)
685 goto out;
686
687 err = __netlink_create(net, sock, protocol, kern);
688 if (err < 0)
689 goto out_module;
690
691 sock_prot_inuse_add(net, &netlink_proto, 1);
692
693 nlk = nlk_sk(sock->sk);
694 nlk->module = module;
695 nlk->netlink_bind = bind;
696 nlk->netlink_unbind = unbind;
697 nlk->netlink_release = release;
698 out:
699 return err;
700
701 out_module:
702 module_put(module);
703 goto out;
704 }
705
deferred_put_nlk_sk(struct rcu_head * head)706 static void deferred_put_nlk_sk(struct rcu_head *head)
707 {
708 struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu);
709 struct sock *sk = &nlk->sk;
710
711 kfree(nlk->groups);
712 nlk->groups = NULL;
713
714 if (!refcount_dec_and_test(&sk->sk_refcnt))
715 return;
716
717 sk_free(sk);
718 }
719
netlink_release(struct socket * sock)720 static int netlink_release(struct socket *sock)
721 {
722 struct sock *sk = sock->sk;
723 struct netlink_sock *nlk;
724
725 if (!sk)
726 return 0;
727
728 netlink_remove(sk);
729 sock_orphan(sk);
730 nlk = nlk_sk(sk);
731
732 /*
733 * OK. Socket is unlinked, any packets that arrive now
734 * will be purged.
735 */
736 if (nlk->netlink_release)
737 nlk->netlink_release(sk, nlk->groups);
738
739 /* must not acquire netlink_table_lock in any way again before unbind
740 * and notifying genetlink is done as otherwise it might deadlock
741 */
742 if (nlk->netlink_unbind) {
743 int i;
744
745 for (i = 0; i < nlk->ngroups; i++)
746 if (test_bit(i, nlk->groups))
747 nlk->netlink_unbind(sock_net(sk), i + 1);
748 }
749 if (sk->sk_protocol == NETLINK_GENERIC &&
750 atomic_dec_return(&genl_sk_destructing_cnt) == 0)
751 wake_up(&genl_sk_destructing_waitq);
752
753 sock->sk = NULL;
754 wake_up_interruptible_all(&nlk->wait);
755
756 skb_queue_purge(&sk->sk_write_queue);
757
758 if (nlk->portid && nlk->bound) {
759 struct netlink_notify n = {
760 .net = sock_net(sk),
761 .protocol = sk->sk_protocol,
762 .portid = nlk->portid,
763 };
764 blocking_notifier_call_chain(&netlink_chain,
765 NETLINK_URELEASE, &n);
766 }
767
768 /* Terminate any outstanding dump */
769 if (nlk->cb_running) {
770 if (nlk->cb.done)
771 nlk->cb.done(&nlk->cb);
772 module_put(nlk->cb.module);
773 kfree_skb(nlk->cb.skb);
774 }
775
776 module_put(nlk->module);
777
778 if (netlink_is_kernel(sk)) {
779 netlink_table_grab();
780 BUG_ON(nl_table[sk->sk_protocol].registered == 0);
781 if (--nl_table[sk->sk_protocol].registered == 0) {
782 struct listeners *old;
783
784 old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
785 RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
786 kfree_rcu(old, rcu);
787 nl_table[sk->sk_protocol].module = NULL;
788 nl_table[sk->sk_protocol].bind = NULL;
789 nl_table[sk->sk_protocol].unbind = NULL;
790 nl_table[sk->sk_protocol].flags = 0;
791 nl_table[sk->sk_protocol].registered = 0;
792 }
793 netlink_table_ungrab();
794 }
795
796 sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
797
798 call_rcu(&nlk->rcu, deferred_put_nlk_sk);
799 return 0;
800 }
801
netlink_autobind(struct socket * sock)802 static int netlink_autobind(struct socket *sock)
803 {
804 struct sock *sk = sock->sk;
805 struct net *net = sock_net(sk);
806 struct netlink_table *table = &nl_table[sk->sk_protocol];
807 s32 portid = task_tgid_vnr(current);
808 int err;
809 s32 rover = -4096;
810 bool ok;
811
812 retry:
813 cond_resched();
814 rcu_read_lock();
815 ok = !__netlink_lookup(table, portid, net);
816 rcu_read_unlock();
817 if (!ok) {
818 /* Bind collision, search negative portid values. */
819 if (rover == -4096)
820 /* rover will be in range [S32_MIN, -4097] */
821 rover = S32_MIN + get_random_u32_below(-4096 - S32_MIN);
822 else if (rover >= -4096)
823 rover = -4097;
824 portid = rover--;
825 goto retry;
826 }
827
828 err = netlink_insert(sk, portid);
829 if (err == -EADDRINUSE)
830 goto retry;
831
832 /* If 2 threads race to autobind, that is fine. */
833 if (err == -EBUSY)
834 err = 0;
835
836 return err;
837 }
838
839 /**
840 * __netlink_ns_capable - General netlink message capability test
841 * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
842 * @user_ns: The user namespace of the capability to use
843 * @cap: The capability to use
844 *
845 * Test to see if the opener of the socket we received the message
846 * from had when the netlink socket was created and the sender of the
847 * message has the capability @cap in the user namespace @user_ns.
848 */
__netlink_ns_capable(const struct netlink_skb_parms * nsp,struct user_namespace * user_ns,int cap)849 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
850 struct user_namespace *user_ns, int cap)
851 {
852 return ((nsp->flags & NETLINK_SKB_DST) ||
853 file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
854 ns_capable(user_ns, cap);
855 }
856 EXPORT_SYMBOL(__netlink_ns_capable);
857
858 /**
859 * netlink_ns_capable - General netlink message capability test
860 * @skb: socket buffer holding a netlink command from userspace
861 * @user_ns: The user namespace of the capability to use
862 * @cap: The capability to use
863 *
864 * Test to see if the opener of the socket we received the message
865 * from had when the netlink socket was created and the sender of the
866 * message has the capability @cap in the user namespace @user_ns.
867 */
netlink_ns_capable(const struct sk_buff * skb,struct user_namespace * user_ns,int cap)868 bool netlink_ns_capable(const struct sk_buff *skb,
869 struct user_namespace *user_ns, int cap)
870 {
871 return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
872 }
873 EXPORT_SYMBOL(netlink_ns_capable);
874
875 /**
876 * netlink_capable - Netlink global message capability test
877 * @skb: socket buffer holding a netlink command from userspace
878 * @cap: The capability to use
879 *
880 * Test to see if the opener of the socket we received the message
881 * from had when the netlink socket was created and the sender of the
882 * message has the capability @cap in all user namespaces.
883 */
netlink_capable(const struct sk_buff * skb,int cap)884 bool netlink_capable(const struct sk_buff *skb, int cap)
885 {
886 return netlink_ns_capable(skb, &init_user_ns, cap);
887 }
888 EXPORT_SYMBOL(netlink_capable);
889
890 /**
891 * netlink_net_capable - Netlink network namespace message capability test
892 * @skb: socket buffer holding a netlink command from userspace
893 * @cap: The capability to use
894 *
895 * Test to see if the opener of the socket we received the message
896 * from had when the netlink socket was created and the sender of the
897 * message has the capability @cap over the network namespace of
898 * the socket we received the message from.
899 */
netlink_net_capable(const struct sk_buff * skb,int cap)900 bool netlink_net_capable(const struct sk_buff *skb, int cap)
901 {
902 return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
903 }
904 EXPORT_SYMBOL(netlink_net_capable);
905
netlink_allowed(const struct socket * sock,unsigned int flag)906 static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
907 {
908 return (nl_table[sock->sk->sk_protocol].flags & flag) ||
909 ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
910 }
911
912 static void
netlink_update_subscriptions(struct sock * sk,unsigned int subscriptions)913 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
914 {
915 struct netlink_sock *nlk = nlk_sk(sk);
916
917 if (nlk->subscriptions && !subscriptions)
918 __sk_del_bind_node(sk);
919 else if (!nlk->subscriptions && subscriptions)
920 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
921 nlk->subscriptions = subscriptions;
922 }
923
netlink_realloc_groups(struct sock * sk)924 static int netlink_realloc_groups(struct sock *sk)
925 {
926 struct netlink_sock *nlk = nlk_sk(sk);
927 unsigned int groups;
928 unsigned long *new_groups;
929 int err = 0;
930
931 netlink_table_grab();
932
933 groups = nl_table[sk->sk_protocol].groups;
934 if (!nl_table[sk->sk_protocol].registered) {
935 err = -ENOENT;
936 goto out_unlock;
937 }
938
939 if (nlk->ngroups >= groups)
940 goto out_unlock;
941
942 new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
943 if (new_groups == NULL) {
944 err = -ENOMEM;
945 goto out_unlock;
946 }
947 memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
948 NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
949
950 nlk->groups = new_groups;
951 nlk->ngroups = groups;
952 out_unlock:
953 netlink_table_ungrab();
954 return err;
955 }
956
netlink_undo_bind(int group,long unsigned int groups,struct sock * sk)957 static void netlink_undo_bind(int group, long unsigned int groups,
958 struct sock *sk)
959 {
960 struct netlink_sock *nlk = nlk_sk(sk);
961 int undo;
962
963 if (!nlk->netlink_unbind)
964 return;
965
966 for (undo = 0; undo < group; undo++)
967 if (test_bit(undo, &groups))
968 nlk->netlink_unbind(sock_net(sk), undo + 1);
969 }
970
netlink_bind(struct socket * sock,struct sockaddr * addr,int addr_len)971 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
972 int addr_len)
973 {
974 struct sock *sk = sock->sk;
975 struct net *net = sock_net(sk);
976 struct netlink_sock *nlk = nlk_sk(sk);
977 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
978 int err = 0;
979 unsigned long groups;
980 bool bound;
981
982 if (addr_len < sizeof(struct sockaddr_nl))
983 return -EINVAL;
984
985 if (nladdr->nl_family != AF_NETLINK)
986 return -EINVAL;
987 groups = nladdr->nl_groups;
988
989 /* Only superuser is allowed to listen multicasts */
990 if (groups) {
991 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
992 return -EPERM;
993 err = netlink_realloc_groups(sk);
994 if (err)
995 return err;
996 }
997
998 if (nlk->ngroups < BITS_PER_LONG)
999 groups &= (1UL << nlk->ngroups) - 1;
1000
1001 /* Paired with WRITE_ONCE() in netlink_insert() */
1002 bound = READ_ONCE(nlk->bound);
1003 if (bound) {
1004 /* Ensure nlk->portid is up-to-date. */
1005 smp_rmb();
1006
1007 if (nladdr->nl_pid != nlk->portid)
1008 return -EINVAL;
1009 }
1010
1011 if (nlk->netlink_bind && groups) {
1012 int group;
1013
1014 /* nl_groups is a u32, so cap the maximum groups we can bind */
1015 for (group = 0; group < BITS_PER_TYPE(u32); group++) {
1016 if (!test_bit(group, &groups))
1017 continue;
1018 err = nlk->netlink_bind(net, group + 1);
1019 if (!err)
1020 continue;
1021 netlink_undo_bind(group, groups, sk);
1022 return err;
1023 }
1024 }
1025
1026 /* No need for barriers here as we return to user-space without
1027 * using any of the bound attributes.
1028 */
1029 netlink_lock_table();
1030 if (!bound) {
1031 err = nladdr->nl_pid ?
1032 netlink_insert(sk, nladdr->nl_pid) :
1033 netlink_autobind(sock);
1034 if (err) {
1035 netlink_undo_bind(BITS_PER_TYPE(u32), groups, sk);
1036 goto unlock;
1037 }
1038 }
1039
1040 if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
1041 goto unlock;
1042 netlink_unlock_table();
1043
1044 netlink_table_grab();
1045 netlink_update_subscriptions(sk, nlk->subscriptions +
1046 hweight32(groups) -
1047 hweight32(nlk->groups[0]));
1048 nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups;
1049 netlink_update_listeners(sk);
1050 netlink_table_ungrab();
1051
1052 return 0;
1053
1054 unlock:
1055 netlink_unlock_table();
1056 return err;
1057 }
1058
netlink_connect(struct socket * sock,struct sockaddr * addr,int alen,int flags)1059 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
1060 int alen, int flags)
1061 {
1062 int err = 0;
1063 struct sock *sk = sock->sk;
1064 struct netlink_sock *nlk = nlk_sk(sk);
1065 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
1066
1067 if (alen < sizeof(addr->sa_family))
1068 return -EINVAL;
1069
1070 if (addr->sa_family == AF_UNSPEC) {
1071 /* paired with READ_ONCE() in netlink_getsockbyportid() */
1072 WRITE_ONCE(sk->sk_state, NETLINK_UNCONNECTED);
1073 /* dst_portid and dst_group can be read locklessly */
1074 WRITE_ONCE(nlk->dst_portid, 0);
1075 WRITE_ONCE(nlk->dst_group, 0);
1076 return 0;
1077 }
1078 if (addr->sa_family != AF_NETLINK)
1079 return -EINVAL;
1080
1081 if (alen < sizeof(struct sockaddr_nl))
1082 return -EINVAL;
1083
1084 if ((nladdr->nl_groups || nladdr->nl_pid) &&
1085 !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1086 return -EPERM;
1087
1088 /* No need for barriers here as we return to user-space without
1089 * using any of the bound attributes.
1090 * Paired with WRITE_ONCE() in netlink_insert().
1091 */
1092 if (!READ_ONCE(nlk->bound))
1093 err = netlink_autobind(sock);
1094
1095 if (err == 0) {
1096 /* paired with READ_ONCE() in netlink_getsockbyportid() */
1097 WRITE_ONCE(sk->sk_state, NETLINK_CONNECTED);
1098 /* dst_portid and dst_group can be read locklessly */
1099 WRITE_ONCE(nlk->dst_portid, nladdr->nl_pid);
1100 WRITE_ONCE(nlk->dst_group, ffs(nladdr->nl_groups));
1101 }
1102
1103 return err;
1104 }
1105
netlink_getname(struct socket * sock,struct sockaddr * addr,int peer)1106 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
1107 int peer)
1108 {
1109 struct sock *sk = sock->sk;
1110 struct netlink_sock *nlk = nlk_sk(sk);
1111 DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
1112
1113 nladdr->nl_family = AF_NETLINK;
1114 nladdr->nl_pad = 0;
1115
1116 if (peer) {
1117 /* Paired with WRITE_ONCE() in netlink_connect() */
1118 nladdr->nl_pid = READ_ONCE(nlk->dst_portid);
1119 nladdr->nl_groups = netlink_group_mask(READ_ONCE(nlk->dst_group));
1120 } else {
1121 /* Paired with WRITE_ONCE() in netlink_insert() */
1122 nladdr->nl_pid = READ_ONCE(nlk->portid);
1123 netlink_lock_table();
1124 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
1125 netlink_unlock_table();
1126 }
1127 return sizeof(*nladdr);
1128 }
1129
netlink_ioctl(struct socket * sock,unsigned int cmd,unsigned long arg)1130 static int netlink_ioctl(struct socket *sock, unsigned int cmd,
1131 unsigned long arg)
1132 {
1133 /* try to hand this ioctl down to the NIC drivers.
1134 */
1135 return -ENOIOCTLCMD;
1136 }
1137
netlink_getsockbyportid(struct sock * ssk,u32 portid)1138 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
1139 {
1140 struct sock *sock;
1141 struct netlink_sock *nlk;
1142
1143 sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
1144 if (!sock)
1145 return ERR_PTR(-ECONNREFUSED);
1146
1147 /* Don't bother queuing skb if kernel socket has no input function */
1148 nlk = nlk_sk(sock);
1149 /* dst_portid and sk_state can be changed in netlink_connect() */
1150 if (READ_ONCE(sock->sk_state) == NETLINK_CONNECTED &&
1151 READ_ONCE(nlk->dst_portid) != nlk_sk(ssk)->portid) {
1152 sock_put(sock);
1153 return ERR_PTR(-ECONNREFUSED);
1154 }
1155 return sock;
1156 }
1157
netlink_getsockbyfd(int fd)1158 struct sock *netlink_getsockbyfd(int fd)
1159 {
1160 CLASS(fd, f)(fd);
1161 struct inode *inode;
1162 struct sock *sock;
1163
1164 if (fd_empty(f))
1165 return ERR_PTR(-EBADF);
1166
1167 inode = file_inode(fd_file(f));
1168 if (!S_ISSOCK(inode->i_mode))
1169 return ERR_PTR(-ENOTSOCK);
1170
1171 sock = SOCKET_I(inode)->sk;
1172 if (sock->sk_family != AF_NETLINK)
1173 return ERR_PTR(-EINVAL);
1174
1175 sock_hold(sock);
1176 return sock;
1177 }
1178
netlink_alloc_large_skb(unsigned int size,int broadcast)1179 struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast)
1180 {
1181 size_t head_size = SKB_HEAD_ALIGN(size);
1182 struct sk_buff *skb;
1183 void *data;
1184
1185 if (head_size <= PAGE_SIZE || broadcast)
1186 return alloc_skb(size, GFP_KERNEL);
1187
1188 data = kvmalloc(head_size, GFP_KERNEL);
1189 if (!data)
1190 return NULL;
1191
1192 skb = __build_skb(data, head_size);
1193 if (!skb)
1194 kvfree(data);
1195 else if (is_vmalloc_addr(data))
1196 skb->destructor = netlink_skb_destructor;
1197
1198 return skb;
1199 }
1200
1201 /*
1202 * Attach a skb to a netlink socket.
1203 * The caller must hold a reference to the destination socket. On error, the
1204 * reference is dropped. The skb is not send to the destination, just all
1205 * all error checks are performed and memory in the queue is reserved.
1206 * Return values:
1207 * < 0: error. skb freed, reference to sock dropped.
1208 * 0: continue
1209 * 1: repeat lookup - reference dropped while waiting for socket memory.
1210 */
netlink_attachskb(struct sock * sk,struct sk_buff * skb,long * timeo,struct sock * ssk)1211 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
1212 long *timeo, struct sock *ssk)
1213 {
1214 struct netlink_sock *nlk;
1215
1216 nlk = nlk_sk(sk);
1217
1218 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1219 test_bit(NETLINK_S_CONGESTED, &nlk->state))) {
1220 DECLARE_WAITQUEUE(wait, current);
1221 if (!*timeo) {
1222 if (!ssk || netlink_is_kernel(ssk))
1223 netlink_overrun(sk);
1224 sock_put(sk);
1225 kfree_skb(skb);
1226 return -EAGAIN;
1227 }
1228
1229 __set_current_state(TASK_INTERRUPTIBLE);
1230 add_wait_queue(&nlk->wait, &wait);
1231
1232 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1233 test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
1234 !sock_flag(sk, SOCK_DEAD))
1235 *timeo = schedule_timeout(*timeo);
1236
1237 __set_current_state(TASK_RUNNING);
1238 remove_wait_queue(&nlk->wait, &wait);
1239 sock_put(sk);
1240
1241 if (signal_pending(current)) {
1242 kfree_skb(skb);
1243 return sock_intr_errno(*timeo);
1244 }
1245 return 1;
1246 }
1247 netlink_skb_set_owner_r(skb, sk);
1248 return 0;
1249 }
1250
__netlink_sendskb(struct sock * sk,struct sk_buff * skb)1251 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1252 {
1253 int len = skb->len;
1254
1255 netlink_deliver_tap(sock_net(sk), skb);
1256
1257 skb_queue_tail(&sk->sk_receive_queue, skb);
1258 sk->sk_data_ready(sk);
1259 return len;
1260 }
1261
netlink_sendskb(struct sock * sk,struct sk_buff * skb)1262 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1263 {
1264 int len = __netlink_sendskb(sk, skb);
1265
1266 sock_put(sk);
1267 return len;
1268 }
1269
netlink_detachskb(struct sock * sk,struct sk_buff * skb)1270 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
1271 {
1272 kfree_skb(skb);
1273 sock_put(sk);
1274 }
1275
netlink_trim(struct sk_buff * skb,gfp_t allocation)1276 static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
1277 {
1278 int delta;
1279
1280 skb_assert_len(skb);
1281 WARN_ON(skb->sk != NULL);
1282 delta = skb->end - skb->tail;
1283 if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
1284 return skb;
1285
1286 if (skb_shared(skb)) {
1287 struct sk_buff *nskb = skb_clone(skb, allocation);
1288 if (!nskb)
1289 return skb;
1290 consume_skb(skb);
1291 skb = nskb;
1292 }
1293
1294 pskb_expand_head(skb, 0, -delta,
1295 (allocation & ~__GFP_DIRECT_RECLAIM) |
1296 __GFP_NOWARN | __GFP_NORETRY);
1297 return skb;
1298 }
1299
netlink_unicast_kernel(struct sock * sk,struct sk_buff * skb,struct sock * ssk)1300 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
1301 struct sock *ssk)
1302 {
1303 int ret;
1304 struct netlink_sock *nlk = nlk_sk(sk);
1305
1306 ret = -ECONNREFUSED;
1307 if (nlk->netlink_rcv != NULL) {
1308 ret = skb->len;
1309 netlink_skb_set_owner_r(skb, sk);
1310 NETLINK_CB(skb).sk = ssk;
1311 netlink_deliver_tap_kernel(sk, ssk, skb);
1312 nlk->netlink_rcv(skb);
1313 consume_skb(skb);
1314 } else {
1315 kfree_skb(skb);
1316 }
1317 sock_put(sk);
1318 return ret;
1319 }
1320
netlink_unicast(struct sock * ssk,struct sk_buff * skb,u32 portid,int nonblock)1321 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
1322 u32 portid, int nonblock)
1323 {
1324 struct sock *sk;
1325 int err;
1326 long timeo;
1327
1328 skb = netlink_trim(skb, gfp_any());
1329
1330 timeo = sock_sndtimeo(ssk, nonblock);
1331 retry:
1332 sk = netlink_getsockbyportid(ssk, portid);
1333 if (IS_ERR(sk)) {
1334 kfree_skb(skb);
1335 return PTR_ERR(sk);
1336 }
1337 if (netlink_is_kernel(sk))
1338 return netlink_unicast_kernel(sk, skb, ssk);
1339
1340 if (sk_filter(sk, skb)) {
1341 err = skb->len;
1342 kfree_skb(skb);
1343 sock_put(sk);
1344 return err;
1345 }
1346
1347 err = netlink_attachskb(sk, skb, &timeo, ssk);
1348 if (err == 1)
1349 goto retry;
1350 if (err)
1351 return err;
1352
1353 return netlink_sendskb(sk, skb);
1354 }
1355 EXPORT_SYMBOL(netlink_unicast);
1356
netlink_has_listeners(struct sock * sk,unsigned int group)1357 int netlink_has_listeners(struct sock *sk, unsigned int group)
1358 {
1359 int res = 0;
1360 struct listeners *listeners;
1361
1362 BUG_ON(!netlink_is_kernel(sk));
1363
1364 rcu_read_lock();
1365 listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
1366
1367 if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
1368 res = test_bit(group - 1, listeners->masks);
1369
1370 rcu_read_unlock();
1371
1372 return res;
1373 }
1374 EXPORT_SYMBOL_GPL(netlink_has_listeners);
1375
netlink_strict_get_check(struct sk_buff * skb)1376 bool netlink_strict_get_check(struct sk_buff *skb)
1377 {
1378 return nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);
1379 }
1380 EXPORT_SYMBOL_GPL(netlink_strict_get_check);
1381
netlink_broadcast_deliver(struct sock * sk,struct sk_buff * skb)1382 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
1383 {
1384 struct netlink_sock *nlk = nlk_sk(sk);
1385
1386 if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
1387 !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
1388 netlink_skb_set_owner_r(skb, sk);
1389 __netlink_sendskb(sk, skb);
1390 return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
1391 }
1392 return -1;
1393 }
1394
1395 struct netlink_broadcast_data {
1396 struct sock *exclude_sk;
1397 struct net *net;
1398 u32 portid;
1399 u32 group;
1400 int failure;
1401 int delivery_failure;
1402 int congested;
1403 int delivered;
1404 gfp_t allocation;
1405 struct sk_buff *skb, *skb2;
1406 int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
1407 void *tx_data;
1408 };
1409
do_one_broadcast(struct sock * sk,struct netlink_broadcast_data * p)1410 static void do_one_broadcast(struct sock *sk,
1411 struct netlink_broadcast_data *p)
1412 {
1413 struct netlink_sock *nlk = nlk_sk(sk);
1414 int val;
1415
1416 if (p->exclude_sk == sk)
1417 return;
1418
1419 if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1420 !test_bit(p->group - 1, nlk->groups))
1421 return;
1422
1423 if (!net_eq(sock_net(sk), p->net)) {
1424 if (!nlk_test_bit(LISTEN_ALL_NSID, sk))
1425 return;
1426
1427 if (!peernet_has_id(sock_net(sk), p->net))
1428 return;
1429
1430 if (!file_ns_capable(sk->sk_socket->file, p->net->user_ns,
1431 CAP_NET_BROADCAST))
1432 return;
1433 }
1434
1435 if (p->failure) {
1436 netlink_overrun(sk);
1437 return;
1438 }
1439
1440 sock_hold(sk);
1441 if (p->skb2 == NULL) {
1442 if (skb_shared(p->skb)) {
1443 p->skb2 = skb_clone(p->skb, p->allocation);
1444 } else {
1445 p->skb2 = skb_get(p->skb);
1446 /*
1447 * skb ownership may have been set when
1448 * delivered to a previous socket.
1449 */
1450 skb_orphan(p->skb2);
1451 }
1452 }
1453 if (p->skb2 == NULL) {
1454 netlink_overrun(sk);
1455 /* Clone failed. Notify ALL listeners. */
1456 p->failure = 1;
1457 if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
1458 p->delivery_failure = 1;
1459 goto out;
1460 }
1461
1462 if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
1463 kfree_skb(p->skb2);
1464 p->skb2 = NULL;
1465 goto out;
1466 }
1467
1468 if (sk_filter(sk, p->skb2)) {
1469 kfree_skb(p->skb2);
1470 p->skb2 = NULL;
1471 goto out;
1472 }
1473 NETLINK_CB(p->skb2).nsid = peernet2id(sock_net(sk), p->net);
1474 if (NETLINK_CB(p->skb2).nsid != NETNSA_NSID_NOT_ASSIGNED)
1475 NETLINK_CB(p->skb2).nsid_is_set = true;
1476 val = netlink_broadcast_deliver(sk, p->skb2);
1477 if (val < 0) {
1478 netlink_overrun(sk);
1479 if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
1480 p->delivery_failure = 1;
1481 } else {
1482 p->congested |= val;
1483 p->delivered = 1;
1484 p->skb2 = NULL;
1485 }
1486 out:
1487 sock_put(sk);
1488 }
1489
netlink_broadcast_filtered(struct sock * ssk,struct sk_buff * skb,u32 portid,u32 group,gfp_t allocation,netlink_filter_fn filter,void * filter_data)1490 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
1491 u32 portid,
1492 u32 group, gfp_t allocation,
1493 netlink_filter_fn filter,
1494 void *filter_data)
1495 {
1496 struct net *net = sock_net(ssk);
1497 struct netlink_broadcast_data info;
1498 struct sock *sk;
1499
1500 skb = netlink_trim(skb, allocation);
1501
1502 info.exclude_sk = ssk;
1503 info.net = net;
1504 info.portid = portid;
1505 info.group = group;
1506 info.failure = 0;
1507 info.delivery_failure = 0;
1508 info.congested = 0;
1509 info.delivered = 0;
1510 info.allocation = allocation;
1511 info.skb = skb;
1512 info.skb2 = NULL;
1513 info.tx_filter = filter;
1514 info.tx_data = filter_data;
1515
1516 /* While we sleep in clone, do not allow to change socket list */
1517
1518 netlink_lock_table();
1519
1520 sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1521 do_one_broadcast(sk, &info);
1522
1523 consume_skb(skb);
1524
1525 netlink_unlock_table();
1526
1527 if (info.delivery_failure) {
1528 kfree_skb(info.skb2);
1529 return -ENOBUFS;
1530 }
1531 consume_skb(info.skb2);
1532
1533 if (info.delivered) {
1534 if (info.congested && gfpflags_allow_blocking(allocation))
1535 yield();
1536 return 0;
1537 }
1538 return -ESRCH;
1539 }
1540 EXPORT_SYMBOL(netlink_broadcast_filtered);
1541
netlink_broadcast(struct sock * ssk,struct sk_buff * skb,u32 portid,u32 group,gfp_t allocation)1542 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
1543 u32 group, gfp_t allocation)
1544 {
1545 return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
1546 NULL, NULL);
1547 }
1548 EXPORT_SYMBOL(netlink_broadcast);
1549
1550 struct netlink_set_err_data {
1551 struct sock *exclude_sk;
1552 u32 portid;
1553 u32 group;
1554 int code;
1555 };
1556
do_one_set_err(struct sock * sk,struct netlink_set_err_data * p)1557 static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
1558 {
1559 struct netlink_sock *nlk = nlk_sk(sk);
1560 int ret = 0;
1561
1562 if (sk == p->exclude_sk)
1563 goto out;
1564
1565 if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
1566 goto out;
1567
1568 if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1569 !test_bit(p->group - 1, nlk->groups))
1570 goto out;
1571
1572 if (p->code == ENOBUFS && nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
1573 ret = 1;
1574 goto out;
1575 }
1576
1577 WRITE_ONCE(sk->sk_err, p->code);
1578 sk_error_report(sk);
1579 out:
1580 return ret;
1581 }
1582
1583 /**
1584 * netlink_set_err - report error to broadcast listeners
1585 * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
1586 * @portid: the PORTID of a process that we want to skip (if any)
1587 * @group: the broadcast group that will notice the error
1588 * @code: error code, must be negative (as usual in kernelspace)
1589 *
1590 * This function returns the number of broadcast listeners that have set the
1591 * NETLINK_NO_ENOBUFS socket option.
1592 */
netlink_set_err(struct sock * ssk,u32 portid,u32 group,int code)1593 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
1594 {
1595 struct netlink_set_err_data info;
1596 unsigned long flags;
1597 struct sock *sk;
1598 int ret = 0;
1599
1600 info.exclude_sk = ssk;
1601 info.portid = portid;
1602 info.group = group;
1603 /* sk->sk_err wants a positive error value */
1604 info.code = -code;
1605
1606 read_lock_irqsave(&nl_table_lock, flags);
1607
1608 sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1609 ret += do_one_set_err(sk, &info);
1610
1611 read_unlock_irqrestore(&nl_table_lock, flags);
1612 return ret;
1613 }
1614 EXPORT_SYMBOL(netlink_set_err);
1615
1616 /* must be called with netlink table grabbed */
netlink_update_socket_mc(struct netlink_sock * nlk,unsigned int group,int is_new)1617 static void netlink_update_socket_mc(struct netlink_sock *nlk,
1618 unsigned int group,
1619 int is_new)
1620 {
1621 int old, new = !!is_new, subscriptions;
1622
1623 old = test_bit(group - 1, nlk->groups);
1624 subscriptions = nlk->subscriptions - old + new;
1625 __assign_bit(group - 1, nlk->groups, new);
1626 netlink_update_subscriptions(&nlk->sk, subscriptions);
1627 netlink_update_listeners(&nlk->sk);
1628 }
1629
netlink_setsockopt(struct socket * sock,int level,int optname,sockptr_t optval,unsigned int optlen)1630 static int netlink_setsockopt(struct socket *sock, int level, int optname,
1631 sockptr_t optval, unsigned int optlen)
1632 {
1633 struct sock *sk = sock->sk;
1634 struct netlink_sock *nlk = nlk_sk(sk);
1635 unsigned int val = 0;
1636 int nr = -1;
1637
1638 if (level != SOL_NETLINK)
1639 return -ENOPROTOOPT;
1640
1641 if (optlen >= sizeof(int) &&
1642 copy_from_sockptr(&val, optval, sizeof(val)))
1643 return -EFAULT;
1644
1645 switch (optname) {
1646 case NETLINK_PKTINFO:
1647 nr = NETLINK_F_RECV_PKTINFO;
1648 break;
1649 case NETLINK_ADD_MEMBERSHIP:
1650 case NETLINK_DROP_MEMBERSHIP: {
1651 int err;
1652
1653 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
1654 return -EPERM;
1655 err = netlink_realloc_groups(sk);
1656 if (err)
1657 return err;
1658 if (!val || val - 1 >= nlk->ngroups)
1659 return -EINVAL;
1660 if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
1661 err = nlk->netlink_bind(sock_net(sk), val);
1662 if (err)
1663 return err;
1664 }
1665 netlink_table_grab();
1666 netlink_update_socket_mc(nlk, val,
1667 optname == NETLINK_ADD_MEMBERSHIP);
1668 netlink_table_ungrab();
1669 if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
1670 nlk->netlink_unbind(sock_net(sk), val);
1671
1672 break;
1673 }
1674 case NETLINK_BROADCAST_ERROR:
1675 nr = NETLINK_F_BROADCAST_SEND_ERROR;
1676 break;
1677 case NETLINK_NO_ENOBUFS:
1678 assign_bit(NETLINK_F_RECV_NO_ENOBUFS, &nlk->flags, val);
1679 if (val) {
1680 clear_bit(NETLINK_S_CONGESTED, &nlk->state);
1681 wake_up_interruptible(&nlk->wait);
1682 }
1683 break;
1684 case NETLINK_LISTEN_ALL_NSID:
1685 if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
1686 return -EPERM;
1687 nr = NETLINK_F_LISTEN_ALL_NSID;
1688 break;
1689 case NETLINK_CAP_ACK:
1690 nr = NETLINK_F_CAP_ACK;
1691 break;
1692 case NETLINK_EXT_ACK:
1693 nr = NETLINK_F_EXT_ACK;
1694 break;
1695 case NETLINK_GET_STRICT_CHK:
1696 nr = NETLINK_F_STRICT_CHK;
1697 break;
1698 default:
1699 return -ENOPROTOOPT;
1700 }
1701 if (nr >= 0)
1702 assign_bit(nr, &nlk->flags, val);
1703 return 0;
1704 }
1705
netlink_getsockopt(struct socket * sock,int level,int optname,char __user * optval,int __user * optlen)1706 static int netlink_getsockopt(struct socket *sock, int level, int optname,
1707 char __user *optval, int __user *optlen)
1708 {
1709 struct sock *sk = sock->sk;
1710 struct netlink_sock *nlk = nlk_sk(sk);
1711 unsigned int flag;
1712 int len, val;
1713
1714 if (level != SOL_NETLINK)
1715 return -ENOPROTOOPT;
1716
1717 if (get_user(len, optlen))
1718 return -EFAULT;
1719 if (len < 0)
1720 return -EINVAL;
1721
1722 switch (optname) {
1723 case NETLINK_PKTINFO:
1724 flag = NETLINK_F_RECV_PKTINFO;
1725 break;
1726 case NETLINK_BROADCAST_ERROR:
1727 flag = NETLINK_F_BROADCAST_SEND_ERROR;
1728 break;
1729 case NETLINK_NO_ENOBUFS:
1730 flag = NETLINK_F_RECV_NO_ENOBUFS;
1731 break;
1732 case NETLINK_LIST_MEMBERSHIPS: {
1733 int pos, idx, shift, err = 0;
1734
1735 netlink_lock_table();
1736 for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
1737 if (len - pos < sizeof(u32))
1738 break;
1739
1740 idx = pos / sizeof(unsigned long);
1741 shift = (pos % sizeof(unsigned long)) * 8;
1742 if (put_user((u32)(nlk->groups[idx] >> shift),
1743 (u32 __user *)(optval + pos))) {
1744 err = -EFAULT;
1745 break;
1746 }
1747 }
1748 if (put_user(ALIGN(BITS_TO_BYTES(nlk->ngroups), sizeof(u32)), optlen))
1749 err = -EFAULT;
1750 netlink_unlock_table();
1751 return err;
1752 }
1753 case NETLINK_LISTEN_ALL_NSID:
1754 flag = NETLINK_F_LISTEN_ALL_NSID;
1755 break;
1756 case NETLINK_CAP_ACK:
1757 flag = NETLINK_F_CAP_ACK;
1758 break;
1759 case NETLINK_EXT_ACK:
1760 flag = NETLINK_F_EXT_ACK;
1761 break;
1762 case NETLINK_GET_STRICT_CHK:
1763 flag = NETLINK_F_STRICT_CHK;
1764 break;
1765 default:
1766 return -ENOPROTOOPT;
1767 }
1768
1769 if (len < sizeof(int))
1770 return -EINVAL;
1771
1772 len = sizeof(int);
1773 val = test_bit(flag, &nlk->flags);
1774
1775 if (put_user(len, optlen) ||
1776 copy_to_user(optval, &val, len))
1777 return -EFAULT;
1778
1779 return 0;
1780 }
1781
netlink_cmsg_recv_pktinfo(struct msghdr * msg,struct sk_buff * skb)1782 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
1783 {
1784 struct nl_pktinfo info;
1785
1786 info.group = NETLINK_CB(skb).dst_group;
1787 put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
1788 }
1789
netlink_cmsg_listen_all_nsid(struct sock * sk,struct msghdr * msg,struct sk_buff * skb)1790 static void netlink_cmsg_listen_all_nsid(struct sock *sk, struct msghdr *msg,
1791 struct sk_buff *skb)
1792 {
1793 if (!NETLINK_CB(skb).nsid_is_set)
1794 return;
1795
1796 put_cmsg(msg, SOL_NETLINK, NETLINK_LISTEN_ALL_NSID, sizeof(int),
1797 &NETLINK_CB(skb).nsid);
1798 }
1799
netlink_sendmsg(struct socket * sock,struct msghdr * msg,size_t len)1800 static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
1801 {
1802 struct sock *sk = sock->sk;
1803 struct netlink_sock *nlk = nlk_sk(sk);
1804 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1805 u32 dst_portid;
1806 u32 dst_group;
1807 struct sk_buff *skb;
1808 int err;
1809 struct scm_cookie scm;
1810 u32 netlink_skb_flags = 0;
1811
1812 if (msg->msg_flags & MSG_OOB)
1813 return -EOPNOTSUPP;
1814
1815 if (len == 0) {
1816 pr_warn_once("Zero length message leads to an empty skb\n");
1817 return -ENODATA;
1818 }
1819
1820 err = scm_send(sock, msg, &scm, true);
1821 if (err < 0)
1822 return err;
1823
1824 if (msg->msg_namelen) {
1825 err = -EINVAL;
1826 if (msg->msg_namelen < sizeof(struct sockaddr_nl))
1827 goto out;
1828 if (addr->nl_family != AF_NETLINK)
1829 goto out;
1830 dst_portid = addr->nl_pid;
1831 dst_group = ffs(addr->nl_groups);
1832 err = -EPERM;
1833 if ((dst_group || dst_portid) &&
1834 !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1835 goto out;
1836 netlink_skb_flags |= NETLINK_SKB_DST;
1837 } else {
1838 /* Paired with WRITE_ONCE() in netlink_connect() */
1839 dst_portid = READ_ONCE(nlk->dst_portid);
1840 dst_group = READ_ONCE(nlk->dst_group);
1841 }
1842
1843 /* Paired with WRITE_ONCE() in netlink_insert() */
1844 if (!READ_ONCE(nlk->bound)) {
1845 err = netlink_autobind(sock);
1846 if (err)
1847 goto out;
1848 } else {
1849 /* Ensure nlk is hashed and visible. */
1850 smp_rmb();
1851 }
1852
1853 err = -EMSGSIZE;
1854 if (len > sk->sk_sndbuf - 32)
1855 goto out;
1856 err = -ENOBUFS;
1857 skb = netlink_alloc_large_skb(len, dst_group);
1858 if (skb == NULL)
1859 goto out;
1860
1861 NETLINK_CB(skb).portid = nlk->portid;
1862 NETLINK_CB(skb).dst_group = dst_group;
1863 NETLINK_CB(skb).creds = scm.creds;
1864 NETLINK_CB(skb).flags = netlink_skb_flags;
1865
1866 err = -EFAULT;
1867 if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
1868 kfree_skb(skb);
1869 goto out;
1870 }
1871
1872 err = security_netlink_send(sk, skb);
1873 if (err) {
1874 kfree_skb(skb);
1875 goto out;
1876 }
1877
1878 if (dst_group) {
1879 refcount_inc(&skb->users);
1880 netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
1881 }
1882 err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags & MSG_DONTWAIT);
1883
1884 out:
1885 scm_destroy(&scm);
1886 return err;
1887 }
1888
netlink_recvmsg(struct socket * sock,struct msghdr * msg,size_t len,int flags)1889 static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
1890 int flags)
1891 {
1892 struct scm_cookie scm;
1893 struct sock *sk = sock->sk;
1894 struct netlink_sock *nlk = nlk_sk(sk);
1895 size_t copied, max_recvmsg_len;
1896 struct sk_buff *skb, *data_skb;
1897 int err, ret;
1898
1899 if (flags & MSG_OOB)
1900 return -EOPNOTSUPP;
1901
1902 copied = 0;
1903
1904 skb = skb_recv_datagram(sk, flags, &err);
1905 if (skb == NULL)
1906 goto out;
1907
1908 data_skb = skb;
1909
1910 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES
1911 if (unlikely(skb_shinfo(skb)->frag_list)) {
1912 /*
1913 * If this skb has a frag_list, then here that means that we
1914 * will have to use the frag_list skb's data for compat tasks
1915 * and the regular skb's data for normal (non-compat) tasks.
1916 *
1917 * If we need to send the compat skb, assign it to the
1918 * 'data_skb' variable so that it will be used below for data
1919 * copying. We keep 'skb' for everything else, including
1920 * freeing both later.
1921 */
1922 if (flags & MSG_CMSG_COMPAT)
1923 data_skb = skb_shinfo(skb)->frag_list;
1924 }
1925 #endif
1926
1927 /* Record the max length of recvmsg() calls for future allocations */
1928 max_recvmsg_len = max(READ_ONCE(nlk->max_recvmsg_len), len);
1929 max_recvmsg_len = min_t(size_t, max_recvmsg_len,
1930 SKB_WITH_OVERHEAD(32768));
1931 WRITE_ONCE(nlk->max_recvmsg_len, max_recvmsg_len);
1932
1933 copied = data_skb->len;
1934 if (len < copied) {
1935 msg->msg_flags |= MSG_TRUNC;
1936 copied = len;
1937 }
1938
1939 err = skb_copy_datagram_msg(data_skb, 0, msg, copied);
1940
1941 if (msg->msg_name) {
1942 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1943 addr->nl_family = AF_NETLINK;
1944 addr->nl_pad = 0;
1945 addr->nl_pid = NETLINK_CB(skb).portid;
1946 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
1947 msg->msg_namelen = sizeof(*addr);
1948 }
1949
1950 if (nlk_test_bit(RECV_PKTINFO, sk))
1951 netlink_cmsg_recv_pktinfo(msg, skb);
1952 if (nlk_test_bit(LISTEN_ALL_NSID, sk))
1953 netlink_cmsg_listen_all_nsid(sk, msg, skb);
1954
1955 memset(&scm, 0, sizeof(scm));
1956 scm.creds = *NETLINK_CREDS(skb);
1957 if (flags & MSG_TRUNC)
1958 copied = data_skb->len;
1959
1960 skb_free_datagram(sk, skb);
1961
1962 if (READ_ONCE(nlk->cb_running) &&
1963 atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
1964 ret = netlink_dump(sk, false);
1965 if (ret) {
1966 WRITE_ONCE(sk->sk_err, -ret);
1967 sk_error_report(sk);
1968 }
1969 }
1970
1971 scm_recv(sock, msg, &scm, flags);
1972 out:
1973 netlink_rcv_wake(sk);
1974 return err ? : copied;
1975 }
1976
netlink_data_ready(struct sock * sk)1977 static void netlink_data_ready(struct sock *sk)
1978 {
1979 BUG();
1980 }
1981
1982 /*
1983 * We export these functions to other modules. They provide a
1984 * complete set of kernel non-blocking support for message
1985 * queueing.
1986 */
1987
1988 struct sock *
__netlink_kernel_create(struct net * net,int unit,struct module * module,struct netlink_kernel_cfg * cfg)1989 __netlink_kernel_create(struct net *net, int unit, struct module *module,
1990 struct netlink_kernel_cfg *cfg)
1991 {
1992 struct socket *sock;
1993 struct sock *sk;
1994 struct netlink_sock *nlk;
1995 struct listeners *listeners = NULL;
1996 unsigned int groups;
1997
1998 BUG_ON(!nl_table);
1999
2000 if (unit < 0 || unit >= MAX_LINKS)
2001 return NULL;
2002
2003 if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
2004 return NULL;
2005
2006 if (__netlink_create(net, sock, unit, 1) < 0)
2007 goto out_sock_release_nosk;
2008
2009 sk = sock->sk;
2010
2011 if (!cfg || cfg->groups < 32)
2012 groups = 32;
2013 else
2014 groups = cfg->groups;
2015
2016 listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2017 if (!listeners)
2018 goto out_sock_release;
2019
2020 sk->sk_data_ready = netlink_data_ready;
2021 if (cfg && cfg->input)
2022 nlk_sk(sk)->netlink_rcv = cfg->input;
2023
2024 if (netlink_insert(sk, 0))
2025 goto out_sock_release;
2026
2027 nlk = nlk_sk(sk);
2028 set_bit(NETLINK_F_KERNEL_SOCKET, &nlk->flags);
2029
2030 netlink_table_grab();
2031 if (!nl_table[unit].registered) {
2032 nl_table[unit].groups = groups;
2033 rcu_assign_pointer(nl_table[unit].listeners, listeners);
2034 nl_table[unit].module = module;
2035 if (cfg) {
2036 nl_table[unit].bind = cfg->bind;
2037 nl_table[unit].unbind = cfg->unbind;
2038 nl_table[unit].release = cfg->release;
2039 nl_table[unit].flags = cfg->flags;
2040 }
2041 nl_table[unit].registered = 1;
2042 } else {
2043 kfree(listeners);
2044 nl_table[unit].registered++;
2045 }
2046 netlink_table_ungrab();
2047 return sk;
2048
2049 out_sock_release:
2050 kfree(listeners);
2051 netlink_kernel_release(sk);
2052 return NULL;
2053
2054 out_sock_release_nosk:
2055 sock_release(sock);
2056 return NULL;
2057 }
2058 EXPORT_SYMBOL(__netlink_kernel_create);
2059
2060 void
netlink_kernel_release(struct sock * sk)2061 netlink_kernel_release(struct sock *sk)
2062 {
2063 if (sk == NULL || sk->sk_socket == NULL)
2064 return;
2065
2066 sock_release(sk->sk_socket);
2067 }
2068 EXPORT_SYMBOL(netlink_kernel_release);
2069
__netlink_change_ngroups(struct sock * sk,unsigned int groups)2070 int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
2071 {
2072 struct listeners *new, *old;
2073 struct netlink_table *tbl = &nl_table[sk->sk_protocol];
2074
2075 if (groups < 32)
2076 groups = 32;
2077
2078 if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
2079 new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
2080 if (!new)
2081 return -ENOMEM;
2082 old = nl_deref_protected(tbl->listeners);
2083 memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
2084 rcu_assign_pointer(tbl->listeners, new);
2085
2086 kfree_rcu(old, rcu);
2087 }
2088 tbl->groups = groups;
2089
2090 return 0;
2091 }
2092
2093 /**
2094 * netlink_change_ngroups - change number of multicast groups
2095 *
2096 * This changes the number of multicast groups that are available
2097 * on a certain netlink family. Note that it is not possible to
2098 * change the number of groups to below 32. Also note that it does
2099 * not implicitly call netlink_clear_multicast_users() when the
2100 * number of groups is reduced.
2101 *
2102 * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
2103 * @groups: The new number of groups.
2104 */
netlink_change_ngroups(struct sock * sk,unsigned int groups)2105 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
2106 {
2107 int err;
2108
2109 netlink_table_grab();
2110 err = __netlink_change_ngroups(sk, groups);
2111 netlink_table_ungrab();
2112
2113 return err;
2114 }
2115
__netlink_clear_multicast_users(struct sock * ksk,unsigned int group)2116 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
2117 {
2118 struct sock *sk;
2119 struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
2120 struct hlist_node *tmp;
2121
2122 sk_for_each_bound_safe(sk, tmp, &tbl->mc_list)
2123 netlink_update_socket_mc(nlk_sk(sk), group, 0);
2124 }
2125
2126 struct nlmsghdr *
__nlmsg_put(struct sk_buff * skb,u32 portid,u32 seq,int type,int len,int flags)2127 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
2128 {
2129 struct nlmsghdr *nlh;
2130 int size = nlmsg_msg_size(len);
2131
2132 nlh = skb_put(skb, NLMSG_ALIGN(size));
2133 nlh->nlmsg_type = type;
2134 nlh->nlmsg_len = size;
2135 nlh->nlmsg_flags = flags;
2136 nlh->nlmsg_pid = portid;
2137 nlh->nlmsg_seq = seq;
2138 if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
2139 memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
2140 return nlh;
2141 }
2142 EXPORT_SYMBOL(__nlmsg_put);
2143
2144 static size_t
netlink_ack_tlv_len(struct netlink_sock * nlk,int err,const struct netlink_ext_ack * extack)2145 netlink_ack_tlv_len(struct netlink_sock *nlk, int err,
2146 const struct netlink_ext_ack *extack)
2147 {
2148 size_t tlvlen;
2149
2150 if (!extack || !test_bit(NETLINK_F_EXT_ACK, &nlk->flags))
2151 return 0;
2152
2153 tlvlen = 0;
2154 if (extack->_msg)
2155 tlvlen += nla_total_size(strlen(extack->_msg) + 1);
2156 if (extack->cookie_len)
2157 tlvlen += nla_total_size(extack->cookie_len);
2158
2159 /* Following attributes are only reported as error (not warning) */
2160 if (!err)
2161 return tlvlen;
2162
2163 if (extack->bad_attr)
2164 tlvlen += nla_total_size(sizeof(u32));
2165 if (extack->policy)
2166 tlvlen += netlink_policy_dump_attr_size_estimate(extack->policy);
2167 if (extack->miss_type)
2168 tlvlen += nla_total_size(sizeof(u32));
2169 if (extack->miss_nest)
2170 tlvlen += nla_total_size(sizeof(u32));
2171
2172 return tlvlen;
2173 }
2174
nlmsg_check_in_payload(const struct nlmsghdr * nlh,const void * addr)2175 static bool nlmsg_check_in_payload(const struct nlmsghdr *nlh, const void *addr)
2176 {
2177 return !WARN_ON(addr < nlmsg_data(nlh) ||
2178 addr - (const void *) nlh >= nlh->nlmsg_len);
2179 }
2180
2181 static void
netlink_ack_tlv_fill(struct sk_buff * skb,const struct nlmsghdr * nlh,int err,const struct netlink_ext_ack * extack)2182 netlink_ack_tlv_fill(struct sk_buff *skb, const struct nlmsghdr *nlh, int err,
2183 const struct netlink_ext_ack *extack)
2184 {
2185 if (extack->_msg)
2186 WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg));
2187 if (extack->cookie_len)
2188 WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
2189 extack->cookie_len, extack->cookie));
2190
2191 if (!err)
2192 return;
2193
2194 if (extack->bad_attr && nlmsg_check_in_payload(nlh, extack->bad_attr))
2195 WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
2196 (u8 *)extack->bad_attr - (const u8 *)nlh));
2197 if (extack->policy)
2198 netlink_policy_dump_write_attr(skb, extack->policy,
2199 NLMSGERR_ATTR_POLICY);
2200 if (extack->miss_type)
2201 WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_MISS_TYPE,
2202 extack->miss_type));
2203 if (extack->miss_nest && nlmsg_check_in_payload(nlh, extack->miss_nest))
2204 WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_MISS_NEST,
2205 (u8 *)extack->miss_nest - (const u8 *)nlh));
2206 }
2207
2208 /*
2209 * It looks a bit ugly.
2210 * It would be better to create kernel thread.
2211 */
2212
netlink_dump_done(struct netlink_sock * nlk,struct sk_buff * skb,struct netlink_callback * cb,struct netlink_ext_ack * extack)2213 static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb,
2214 struct netlink_callback *cb,
2215 struct netlink_ext_ack *extack)
2216 {
2217 struct nlmsghdr *nlh;
2218 size_t extack_len;
2219
2220 nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(nlk->dump_done_errno),
2221 NLM_F_MULTI | cb->answer_flags);
2222 if (WARN_ON(!nlh))
2223 return -ENOBUFS;
2224
2225 nl_dump_check_consistent(cb, nlh);
2226 memcpy(nlmsg_data(nlh), &nlk->dump_done_errno, sizeof(nlk->dump_done_errno));
2227
2228 extack_len = netlink_ack_tlv_len(nlk, nlk->dump_done_errno, extack);
2229 if (extack_len) {
2230 nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
2231 if (skb_tailroom(skb) >= extack_len) {
2232 netlink_ack_tlv_fill(skb, cb->nlh,
2233 nlk->dump_done_errno, extack);
2234 nlmsg_end(skb, nlh);
2235 }
2236 }
2237
2238 return 0;
2239 }
2240
netlink_dump(struct sock * sk,bool lock_taken)2241 static int netlink_dump(struct sock *sk, bool lock_taken)
2242 {
2243 struct netlink_sock *nlk = nlk_sk(sk);
2244 struct netlink_ext_ack extack = {};
2245 struct netlink_callback *cb;
2246 struct sk_buff *skb = NULL;
2247 size_t max_recvmsg_len;
2248 struct module *module;
2249 int err = -ENOBUFS;
2250 int alloc_min_size;
2251 int alloc_size;
2252
2253 if (!lock_taken)
2254 mutex_lock(&nlk->nl_cb_mutex);
2255 if (!nlk->cb_running) {
2256 err = -EINVAL;
2257 goto errout_skb;
2258 }
2259
2260 if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
2261 goto errout_skb;
2262
2263 /* NLMSG_GOODSIZE is small to avoid high order allocations being
2264 * required, but it makes sense to _attempt_ a 32KiB allocation
2265 * to reduce number of system calls on dump operations, if user
2266 * ever provided a big enough buffer.
2267 */
2268 cb = &nlk->cb;
2269 alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
2270
2271 max_recvmsg_len = READ_ONCE(nlk->max_recvmsg_len);
2272 if (alloc_min_size < max_recvmsg_len) {
2273 alloc_size = max_recvmsg_len;
2274 skb = alloc_skb(alloc_size,
2275 (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) |
2276 __GFP_NOWARN | __GFP_NORETRY);
2277 }
2278 if (!skb) {
2279 alloc_size = alloc_min_size;
2280 skb = alloc_skb(alloc_size, GFP_KERNEL);
2281 }
2282 if (!skb)
2283 goto errout_skb;
2284
2285 /* Trim skb to allocated size. User is expected to provide buffer as
2286 * large as max(min_dump_alloc, 32KiB (max_recvmsg_len capped at
2287 * netlink_recvmsg())). dump will pack as many smaller messages as
2288 * could fit within the allocated skb. skb is typically allocated
2289 * with larger space than required (could be as much as near 2x the
2290 * requested size with align to next power of 2 approach). Allowing
2291 * dump to use the excess space makes it difficult for a user to have a
2292 * reasonable static buffer based on the expected largest dump of a
2293 * single netdev. The outcome is MSG_TRUNC error.
2294 */
2295 skb_reserve(skb, skb_tailroom(skb) - alloc_size);
2296
2297 /* Make sure malicious BPF programs can not read unitialized memory
2298 * from skb->head -> skb->data
2299 */
2300 skb_reset_network_header(skb);
2301 skb_reset_mac_header(skb);
2302
2303 netlink_skb_set_owner_r(skb, sk);
2304
2305 if (nlk->dump_done_errno > 0) {
2306 cb->extack = &extack;
2307
2308 nlk->dump_done_errno = cb->dump(skb, cb);
2309
2310 /* EMSGSIZE plus something already in the skb means
2311 * that there's more to dump but current skb has filled up.
2312 * If the callback really wants to return EMSGSIZE to user space
2313 * it needs to do so again, on the next cb->dump() call,
2314 * without putting data in the skb.
2315 */
2316 if (nlk->dump_done_errno == -EMSGSIZE && skb->len)
2317 nlk->dump_done_errno = skb->len;
2318
2319 cb->extack = NULL;
2320 }
2321
2322 if (nlk->dump_done_errno > 0 ||
2323 skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) {
2324 mutex_unlock(&nlk->nl_cb_mutex);
2325
2326 if (sk_filter(sk, skb))
2327 kfree_skb(skb);
2328 else
2329 __netlink_sendskb(sk, skb);
2330 return 0;
2331 }
2332
2333 if (netlink_dump_done(nlk, skb, cb, &extack))
2334 goto errout_skb;
2335
2336 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES
2337 /* frag_list skb's data is used for compat tasks
2338 * and the regular skb's data for normal (non-compat) tasks.
2339 * See netlink_recvmsg().
2340 */
2341 if (unlikely(skb_shinfo(skb)->frag_list)) {
2342 if (netlink_dump_done(nlk, skb_shinfo(skb)->frag_list, cb, &extack))
2343 goto errout_skb;
2344 }
2345 #endif
2346
2347 if (sk_filter(sk, skb))
2348 kfree_skb(skb);
2349 else
2350 __netlink_sendskb(sk, skb);
2351
2352 if (cb->done)
2353 cb->done(cb);
2354
2355 WRITE_ONCE(nlk->cb_running, false);
2356 module = cb->module;
2357 skb = cb->skb;
2358 mutex_unlock(&nlk->nl_cb_mutex);
2359 module_put(module);
2360 consume_skb(skb);
2361 return 0;
2362
2363 errout_skb:
2364 mutex_unlock(&nlk->nl_cb_mutex);
2365 kfree_skb(skb);
2366 return err;
2367 }
2368
__netlink_dump_start(struct sock * ssk,struct sk_buff * skb,const struct nlmsghdr * nlh,struct netlink_dump_control * control)2369 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
2370 const struct nlmsghdr *nlh,
2371 struct netlink_dump_control *control)
2372 {
2373 struct netlink_callback *cb;
2374 struct netlink_sock *nlk;
2375 struct sock *sk;
2376 int ret;
2377
2378 refcount_inc(&skb->users);
2379
2380 sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
2381 if (sk == NULL) {
2382 ret = -ECONNREFUSED;
2383 goto error_free;
2384 }
2385
2386 nlk = nlk_sk(sk);
2387 mutex_lock(&nlk->nl_cb_mutex);
2388 /* A dump is in progress... */
2389 if (nlk->cb_running) {
2390 ret = -EBUSY;
2391 goto error_unlock;
2392 }
2393 /* add reference of module which cb->dump belongs to */
2394 if (!try_module_get(control->module)) {
2395 ret = -EPROTONOSUPPORT;
2396 goto error_unlock;
2397 }
2398
2399 cb = &nlk->cb;
2400 memset(cb, 0, sizeof(*cb));
2401 cb->dump = control->dump;
2402 cb->done = control->done;
2403 cb->nlh = nlh;
2404 cb->data = control->data;
2405 cb->module = control->module;
2406 cb->min_dump_alloc = control->min_dump_alloc;
2407 cb->flags = control->flags;
2408 cb->skb = skb;
2409
2410 cb->strict_check = nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);
2411
2412 if (control->start) {
2413 cb->extack = control->extack;
2414 ret = control->start(cb);
2415 cb->extack = NULL;
2416 if (ret)
2417 goto error_put;
2418 }
2419
2420 WRITE_ONCE(nlk->cb_running, true);
2421 nlk->dump_done_errno = INT_MAX;
2422
2423 ret = netlink_dump(sk, true);
2424
2425 sock_put(sk);
2426
2427 if (ret)
2428 return ret;
2429
2430 /* We successfully started a dump, by returning -EINTR we
2431 * signal not to send ACK even if it was requested.
2432 */
2433 return -EINTR;
2434
2435 error_put:
2436 module_put(control->module);
2437 error_unlock:
2438 sock_put(sk);
2439 mutex_unlock(&nlk->nl_cb_mutex);
2440 error_free:
2441 kfree_skb(skb);
2442 return ret;
2443 }
2444 EXPORT_SYMBOL(__netlink_dump_start);
2445
netlink_ack(struct sk_buff * in_skb,struct nlmsghdr * nlh,int err,const struct netlink_ext_ack * extack)2446 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
2447 const struct netlink_ext_ack *extack)
2448 {
2449 struct sk_buff *skb;
2450 struct nlmsghdr *rep;
2451 struct nlmsgerr *errmsg;
2452 size_t payload = sizeof(*errmsg);
2453 struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
2454 unsigned int flags = 0;
2455 size_t tlvlen;
2456
2457 /* Error messages get the original request appened, unless the user
2458 * requests to cap the error message, and get extra error data if
2459 * requested.
2460 */
2461 if (err && !test_bit(NETLINK_F_CAP_ACK, &nlk->flags))
2462 payload += nlmsg_len(nlh);
2463 else
2464 flags |= NLM_F_CAPPED;
2465
2466 tlvlen = netlink_ack_tlv_len(nlk, err, extack);
2467 if (tlvlen)
2468 flags |= NLM_F_ACK_TLVS;
2469
2470 skb = nlmsg_new(payload + tlvlen, GFP_KERNEL);
2471 if (!skb)
2472 goto err_skb;
2473
2474 rep = nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2475 NLMSG_ERROR, sizeof(*errmsg), flags);
2476 if (!rep)
2477 goto err_bad_put;
2478 errmsg = nlmsg_data(rep);
2479 errmsg->error = err;
2480 errmsg->msg = *nlh;
2481
2482 if (!(flags & NLM_F_CAPPED)) {
2483 if (!nlmsg_append(skb, nlmsg_len(nlh)))
2484 goto err_bad_put;
2485
2486 memcpy(nlmsg_data(&errmsg->msg), nlmsg_data(nlh),
2487 nlmsg_len(nlh));
2488 }
2489
2490 if (tlvlen)
2491 netlink_ack_tlv_fill(skb, nlh, err, extack);
2492
2493 nlmsg_end(skb, rep);
2494
2495 nlmsg_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid);
2496
2497 return;
2498
2499 err_bad_put:
2500 nlmsg_free(skb);
2501 err_skb:
2502 WRITE_ONCE(NETLINK_CB(in_skb).sk->sk_err, ENOBUFS);
2503 sk_error_report(NETLINK_CB(in_skb).sk);
2504 }
2505 EXPORT_SYMBOL(netlink_ack);
2506
netlink_rcv_skb(struct sk_buff * skb,int (* cb)(struct sk_buff *,struct nlmsghdr *,struct netlink_ext_ack *))2507 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
2508 struct nlmsghdr *,
2509 struct netlink_ext_ack *))
2510 {
2511 struct netlink_ext_ack extack;
2512 struct nlmsghdr *nlh;
2513 int err;
2514
2515 while (skb->len >= nlmsg_total_size(0)) {
2516 int msglen;
2517
2518 memset(&extack, 0, sizeof(extack));
2519 nlh = nlmsg_hdr(skb);
2520 err = 0;
2521
2522 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
2523 return 0;
2524
2525 /* Only requests are handled by the kernel */
2526 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
2527 goto ack;
2528
2529 /* Skip control messages */
2530 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
2531 goto ack;
2532
2533 err = cb(skb, nlh, &extack);
2534 if (err == -EINTR)
2535 goto skip;
2536
2537 ack:
2538 if (nlh->nlmsg_flags & NLM_F_ACK || err)
2539 netlink_ack(skb, nlh, err, &extack);
2540
2541 skip:
2542 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
2543 if (msglen > skb->len)
2544 msglen = skb->len;
2545 skb_pull(skb, msglen);
2546 }
2547
2548 return 0;
2549 }
2550 EXPORT_SYMBOL(netlink_rcv_skb);
2551
2552 /**
2553 * nlmsg_notify - send a notification netlink message
2554 * @sk: netlink socket to use
2555 * @skb: notification message
2556 * @portid: destination netlink portid for reports or 0
2557 * @group: destination multicast group or 0
2558 * @report: 1 to report back, 0 to disable
2559 * @flags: allocation flags
2560 */
nlmsg_notify(struct sock * sk,struct sk_buff * skb,u32 portid,unsigned int group,int report,gfp_t flags)2561 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
2562 unsigned int group, int report, gfp_t flags)
2563 {
2564 int err = 0;
2565
2566 if (group) {
2567 int exclude_portid = 0;
2568
2569 if (report) {
2570 refcount_inc(&skb->users);
2571 exclude_portid = portid;
2572 }
2573
2574 /* errors reported via destination sk->sk_err, but propagate
2575 * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
2576 err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
2577 if (err == -ESRCH)
2578 err = 0;
2579 }
2580
2581 if (report) {
2582 int err2;
2583
2584 err2 = nlmsg_unicast(sk, skb, portid);
2585 if (!err)
2586 err = err2;
2587 }
2588
2589 return err;
2590 }
2591 EXPORT_SYMBOL(nlmsg_notify);
2592
2593 #ifdef CONFIG_PROC_FS
2594 struct nl_seq_iter {
2595 struct seq_net_private p;
2596 struct rhashtable_iter hti;
2597 int link;
2598 };
2599
netlink_walk_start(struct nl_seq_iter * iter)2600 static void netlink_walk_start(struct nl_seq_iter *iter)
2601 {
2602 rhashtable_walk_enter(&nl_table[iter->link].hash, &iter->hti);
2603 rhashtable_walk_start(&iter->hti);
2604 }
2605
netlink_walk_stop(struct nl_seq_iter * iter)2606 static void netlink_walk_stop(struct nl_seq_iter *iter)
2607 {
2608 rhashtable_walk_stop(&iter->hti);
2609 rhashtable_walk_exit(&iter->hti);
2610 }
2611
__netlink_seq_next(struct seq_file * seq)2612 static void *__netlink_seq_next(struct seq_file *seq)
2613 {
2614 struct nl_seq_iter *iter = seq->private;
2615 struct netlink_sock *nlk;
2616
2617 do {
2618 for (;;) {
2619 nlk = rhashtable_walk_next(&iter->hti);
2620
2621 if (IS_ERR(nlk)) {
2622 if (PTR_ERR(nlk) == -EAGAIN)
2623 continue;
2624
2625 return nlk;
2626 }
2627
2628 if (nlk)
2629 break;
2630
2631 netlink_walk_stop(iter);
2632 if (++iter->link >= MAX_LINKS)
2633 return NULL;
2634
2635 netlink_walk_start(iter);
2636 }
2637 } while (sock_net(&nlk->sk) != seq_file_net(seq));
2638
2639 return nlk;
2640 }
2641
netlink_seq_start(struct seq_file * seq,loff_t * posp)2642 static void *netlink_seq_start(struct seq_file *seq, loff_t *posp)
2643 __acquires(RCU)
2644 {
2645 struct nl_seq_iter *iter = seq->private;
2646 void *obj = SEQ_START_TOKEN;
2647 loff_t pos;
2648
2649 iter->link = 0;
2650
2651 netlink_walk_start(iter);
2652
2653 for (pos = *posp; pos && obj && !IS_ERR(obj); pos--)
2654 obj = __netlink_seq_next(seq);
2655
2656 return obj;
2657 }
2658
netlink_seq_next(struct seq_file * seq,void * v,loff_t * pos)2659 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2660 {
2661 ++*pos;
2662 return __netlink_seq_next(seq);
2663 }
2664
netlink_native_seq_stop(struct seq_file * seq,void * v)2665 static void netlink_native_seq_stop(struct seq_file *seq, void *v)
2666 {
2667 struct nl_seq_iter *iter = seq->private;
2668
2669 if (iter->link >= MAX_LINKS)
2670 return;
2671
2672 netlink_walk_stop(iter);
2673 }
2674
2675
netlink_native_seq_show(struct seq_file * seq,void * v)2676 static int netlink_native_seq_show(struct seq_file *seq, void *v)
2677 {
2678 if (v == SEQ_START_TOKEN) {
2679 seq_puts(seq,
2680 "sk Eth Pid Groups "
2681 "Rmem Wmem Dump Locks Drops Inode\n");
2682 } else {
2683 struct sock *s = v;
2684 struct netlink_sock *nlk = nlk_sk(s);
2685
2686 seq_printf(seq, "%pK %-3d %-10u %08x %-8d %-8d %-5d %-8d %-8u %-8lu\n",
2687 s,
2688 s->sk_protocol,
2689 nlk->portid,
2690 nlk->groups ? (u32)nlk->groups[0] : 0,
2691 sk_rmem_alloc_get(s),
2692 sk_wmem_alloc_get(s),
2693 READ_ONCE(nlk->cb_running),
2694 refcount_read(&s->sk_refcnt),
2695 atomic_read(&s->sk_drops),
2696 sock_i_ino(s)
2697 );
2698
2699 }
2700 return 0;
2701 }
2702
2703 #ifdef CONFIG_BPF_SYSCALL
2704 struct bpf_iter__netlink {
2705 __bpf_md_ptr(struct bpf_iter_meta *, meta);
2706 __bpf_md_ptr(struct netlink_sock *, sk);
2707 };
2708
DEFINE_BPF_ITER_FUNC(netlink,struct bpf_iter_meta * meta,struct netlink_sock * sk)2709 DEFINE_BPF_ITER_FUNC(netlink, struct bpf_iter_meta *meta, struct netlink_sock *sk)
2710
2711 static int netlink_prog_seq_show(struct bpf_prog *prog,
2712 struct bpf_iter_meta *meta,
2713 void *v)
2714 {
2715 struct bpf_iter__netlink ctx;
2716
2717 meta->seq_num--; /* skip SEQ_START_TOKEN */
2718 ctx.meta = meta;
2719 ctx.sk = nlk_sk((struct sock *)v);
2720 return bpf_iter_run_prog(prog, &ctx);
2721 }
2722
netlink_seq_show(struct seq_file * seq,void * v)2723 static int netlink_seq_show(struct seq_file *seq, void *v)
2724 {
2725 struct bpf_iter_meta meta;
2726 struct bpf_prog *prog;
2727
2728 meta.seq = seq;
2729 prog = bpf_iter_get_info(&meta, false);
2730 if (!prog)
2731 return netlink_native_seq_show(seq, v);
2732
2733 if (v != SEQ_START_TOKEN)
2734 return netlink_prog_seq_show(prog, &meta, v);
2735
2736 return 0;
2737 }
2738
netlink_seq_stop(struct seq_file * seq,void * v)2739 static void netlink_seq_stop(struct seq_file *seq, void *v)
2740 {
2741 struct bpf_iter_meta meta;
2742 struct bpf_prog *prog;
2743
2744 if (!v) {
2745 meta.seq = seq;
2746 prog = bpf_iter_get_info(&meta, true);
2747 if (prog)
2748 (void)netlink_prog_seq_show(prog, &meta, v);
2749 }
2750
2751 netlink_native_seq_stop(seq, v);
2752 }
2753 #else
netlink_seq_show(struct seq_file * seq,void * v)2754 static int netlink_seq_show(struct seq_file *seq, void *v)
2755 {
2756 return netlink_native_seq_show(seq, v);
2757 }
2758
netlink_seq_stop(struct seq_file * seq,void * v)2759 static void netlink_seq_stop(struct seq_file *seq, void *v)
2760 {
2761 netlink_native_seq_stop(seq, v);
2762 }
2763 #endif
2764
2765 static const struct seq_operations netlink_seq_ops = {
2766 .start = netlink_seq_start,
2767 .next = netlink_seq_next,
2768 .stop = netlink_seq_stop,
2769 .show = netlink_seq_show,
2770 };
2771 #endif
2772
netlink_register_notifier(struct notifier_block * nb)2773 int netlink_register_notifier(struct notifier_block *nb)
2774 {
2775 return blocking_notifier_chain_register(&netlink_chain, nb);
2776 }
2777 EXPORT_SYMBOL(netlink_register_notifier);
2778
netlink_unregister_notifier(struct notifier_block * nb)2779 int netlink_unregister_notifier(struct notifier_block *nb)
2780 {
2781 return blocking_notifier_chain_unregister(&netlink_chain, nb);
2782 }
2783 EXPORT_SYMBOL(netlink_unregister_notifier);
2784
2785 static const struct proto_ops netlink_ops = {
2786 .family = PF_NETLINK,
2787 .owner = THIS_MODULE,
2788 .release = netlink_release,
2789 .bind = netlink_bind,
2790 .connect = netlink_connect,
2791 .socketpair = sock_no_socketpair,
2792 .accept = sock_no_accept,
2793 .getname = netlink_getname,
2794 .poll = datagram_poll,
2795 .ioctl = netlink_ioctl,
2796 .listen = sock_no_listen,
2797 .shutdown = sock_no_shutdown,
2798 .setsockopt = netlink_setsockopt,
2799 .getsockopt = netlink_getsockopt,
2800 .sendmsg = netlink_sendmsg,
2801 .recvmsg = netlink_recvmsg,
2802 .mmap = sock_no_mmap,
2803 };
2804
2805 static const struct net_proto_family netlink_family_ops = {
2806 .family = PF_NETLINK,
2807 .create = netlink_create,
2808 .owner = THIS_MODULE, /* for consistency 8) */
2809 };
2810
netlink_net_init(struct net * net)2811 static int __net_init netlink_net_init(struct net *net)
2812 {
2813 #ifdef CONFIG_PROC_FS
2814 if (!proc_create_net("netlink", 0, net->proc_net, &netlink_seq_ops,
2815 sizeof(struct nl_seq_iter)))
2816 return -ENOMEM;
2817 #endif
2818 return 0;
2819 }
2820
netlink_net_exit(struct net * net)2821 static void __net_exit netlink_net_exit(struct net *net)
2822 {
2823 #ifdef CONFIG_PROC_FS
2824 remove_proc_entry("netlink", net->proc_net);
2825 #endif
2826 }
2827
netlink_add_usersock_entry(void)2828 static void __init netlink_add_usersock_entry(void)
2829 {
2830 struct listeners *listeners;
2831 int groups = 32;
2832
2833 listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2834 if (!listeners)
2835 panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
2836
2837 netlink_table_grab();
2838
2839 nl_table[NETLINK_USERSOCK].groups = groups;
2840 rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
2841 nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
2842 nl_table[NETLINK_USERSOCK].registered = 1;
2843 nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND;
2844
2845 netlink_table_ungrab();
2846 }
2847
2848 static struct pernet_operations __net_initdata netlink_net_ops = {
2849 .init = netlink_net_init,
2850 .exit = netlink_net_exit,
2851 };
2852
netlink_hash(const void * data,u32 len,u32 seed)2853 static inline u32 netlink_hash(const void *data, u32 len, u32 seed)
2854 {
2855 const struct netlink_sock *nlk = data;
2856 struct netlink_compare_arg arg;
2857
2858 netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
2859 return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
2860 }
2861
2862 static const struct rhashtable_params netlink_rhashtable_params = {
2863 .head_offset = offsetof(struct netlink_sock, node),
2864 .key_len = netlink_compare_arg_len,
2865 .obj_hashfn = netlink_hash,
2866 .obj_cmpfn = netlink_compare,
2867 .automatic_shrinking = true,
2868 };
2869
2870 #if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
2871 BTF_ID_LIST(btf_netlink_sock_id)
2872 BTF_ID(struct, netlink_sock)
2873
2874 static const struct bpf_iter_seq_info netlink_seq_info = {
2875 .seq_ops = &netlink_seq_ops,
2876 .init_seq_private = bpf_iter_init_seq_net,
2877 .fini_seq_private = bpf_iter_fini_seq_net,
2878 .seq_priv_size = sizeof(struct nl_seq_iter),
2879 };
2880
2881 static struct bpf_iter_reg netlink_reg_info = {
2882 .target = "netlink",
2883 .ctx_arg_info_size = 1,
2884 .ctx_arg_info = {
2885 { offsetof(struct bpf_iter__netlink, sk),
2886 PTR_TO_BTF_ID_OR_NULL },
2887 },
2888 .seq_info = &netlink_seq_info,
2889 };
2890
bpf_iter_register(void)2891 static int __init bpf_iter_register(void)
2892 {
2893 netlink_reg_info.ctx_arg_info[0].btf_id = *btf_netlink_sock_id;
2894 return bpf_iter_reg_target(&netlink_reg_info);
2895 }
2896 #endif
2897
netlink_proto_init(void)2898 static int __init netlink_proto_init(void)
2899 {
2900 int i;
2901 int err = proto_register(&netlink_proto, 0);
2902
2903 if (err != 0)
2904 goto out;
2905
2906 #if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
2907 err = bpf_iter_register();
2908 if (err)
2909 goto out;
2910 #endif
2911
2912 BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof_field(struct sk_buff, cb));
2913
2914 nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
2915 if (!nl_table)
2916 goto panic;
2917
2918 for (i = 0; i < MAX_LINKS; i++) {
2919 if (rhashtable_init(&nl_table[i].hash,
2920 &netlink_rhashtable_params) < 0)
2921 goto panic;
2922 }
2923
2924 netlink_add_usersock_entry();
2925
2926 sock_register(&netlink_family_ops);
2927 register_pernet_subsys(&netlink_net_ops);
2928 register_pernet_subsys(&netlink_tap_net_ops);
2929 /* The netlink device handler may be needed early. */
2930 rtnetlink_init();
2931 out:
2932 return err;
2933 panic:
2934 panic("netlink_init: Cannot allocate nl_table\n");
2935 }
2936
2937 core_initcall(netlink_proto_init);
2938