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Linux/net/netlink/af_netlink.c

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  1 /*
  2  * NETLINK      Kernel-user communication protocol.
  3  *
  4  *              Authors:        Alan Cox <alan@lxorguk.ukuu.org.uk>
  5  *                              Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
  6  *                              Patrick McHardy <kaber@trash.net>
  7  *
  8  *              This program is free software; you can redistribute it and/or
  9  *              modify it under the terms of the GNU General Public License
 10  *              as published by the Free Software Foundation; either version
 11  *              2 of the License, or (at your option) any later version.
 12  *
 13  * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith
 14  *                               added netlink_proto_exit
 15  * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br>
 16  *                               use nlk_sk, as sk->protinfo is on a diet 8)
 17  * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
 18  *                               - inc module use count of module that owns
 19  *                                 the kernel socket in case userspace opens
 20  *                                 socket of same protocol
 21  *                               - remove all module support, since netlink is
 22  *                                 mandatory if CONFIG_NET=y these days
 23  */
 24 
 25 #include <linux/module.h>
 26 
 27 #include <linux/capability.h>
 28 #include <linux/kernel.h>
 29 #include <linux/init.h>
 30 #include <linux/signal.h>
 31 #include <linux/sched.h>
 32 #include <linux/errno.h>
 33 #include <linux/string.h>
 34 #include <linux/stat.h>
 35 #include <linux/socket.h>
 36 #include <linux/un.h>
 37 #include <linux/fcntl.h>
 38 #include <linux/termios.h>
 39 #include <linux/sockios.h>
 40 #include <linux/net.h>
 41 #include <linux/fs.h>
 42 #include <linux/slab.h>
 43 #include <asm/uaccess.h>
 44 #include <linux/skbuff.h>
 45 #include <linux/netdevice.h>
 46 #include <linux/rtnetlink.h>
 47 #include <linux/proc_fs.h>
 48 #include <linux/seq_file.h>
 49 #include <linux/notifier.h>
 50 #include <linux/security.h>
 51 #include <linux/jhash.h>
 52 #include <linux/jiffies.h>
 53 #include <linux/random.h>
 54 #include <linux/bitops.h>
 55 #include <linux/mm.h>
 56 #include <linux/types.h>
 57 #include <linux/audit.h>
 58 #include <linux/mutex.h>
 59 #include <linux/vmalloc.h>
 60 #include <linux/if_arp.h>
 61 #include <linux/rhashtable.h>
 62 #include <asm/cacheflush.h>
 63 #include <linux/hash.h>
 64 #include <linux/genetlink.h>
 65 
 66 #include <net/net_namespace.h>
 67 #include <net/sock.h>
 68 #include <net/scm.h>
 69 #include <net/netlink.h>
 70 
 71 #include "af_netlink.h"
 72 
 73 struct listeners {
 74         struct rcu_head         rcu;
 75         unsigned long           masks[0];
 76 };
 77 
 78 /* state bits */
 79 #define NETLINK_CONGESTED       0x0
 80 
 81 /* flags */
 82 #define NETLINK_KERNEL_SOCKET   0x1
 83 #define NETLINK_RECV_PKTINFO    0x2
 84 #define NETLINK_BROADCAST_SEND_ERROR    0x4
 85 #define NETLINK_RECV_NO_ENOBUFS 0x8
 86 
 87 static inline int netlink_is_kernel(struct sock *sk)
 88 {
 89         return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET;
 90 }
 91 
 92 struct netlink_table *nl_table;
 93 EXPORT_SYMBOL_GPL(nl_table);
 94 
 95 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 96 
 97 static int netlink_dump(struct sock *sk);
 98 static void netlink_skb_destructor(struct sk_buff *skb);
 99 
100 /* nl_table locking explained:
101  * Lookup and traversal are protected with nl_sk_hash_lock or nl_table_lock
102  * combined with an RCU read-side lock. Insertion and removal are protected
103  * with nl_sk_hash_lock while using RCU list modification primitives and may
104  * run in parallel to nl_table_lock protected lookups. Destruction of the
105  * Netlink socket may only occur *after* nl_table_lock has been acquired
106  * either during or after the socket has been removed from the list.
107  */
108 DEFINE_RWLOCK(nl_table_lock);
109 EXPORT_SYMBOL_GPL(nl_table_lock);
110 static atomic_t nl_table_users = ATOMIC_INIT(0);
111 
112 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
113 
114 /* Protects netlink socket hash table mutations */
115 DEFINE_MUTEX(nl_sk_hash_lock);
116 EXPORT_SYMBOL_GPL(nl_sk_hash_lock);
117 
118 #ifdef CONFIG_PROVE_LOCKING
119 static int lockdep_nl_sk_hash_is_held(void *parent)
120 {
121         if (debug_locks)
122                 return lockdep_is_held(&nl_sk_hash_lock) || lockdep_is_held(&nl_table_lock);
123         return 1;
124 }
125 #endif
126 
127 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
128 
129 static DEFINE_SPINLOCK(netlink_tap_lock);
130 static struct list_head netlink_tap_all __read_mostly;
131 
132 static inline u32 netlink_group_mask(u32 group)
133 {
134         return group ? 1 << (group - 1) : 0;
135 }
136 
137 int netlink_add_tap(struct netlink_tap *nt)
138 {
139         if (unlikely(nt->dev->type != ARPHRD_NETLINK))
140                 return -EINVAL;
141 
142         spin_lock(&netlink_tap_lock);
143         list_add_rcu(&nt->list, &netlink_tap_all);
144         spin_unlock(&netlink_tap_lock);
145 
146         __module_get(nt->module);
147 
148         return 0;
149 }
150 EXPORT_SYMBOL_GPL(netlink_add_tap);
151 
152 static int __netlink_remove_tap(struct netlink_tap *nt)
153 {
154         bool found = false;
155         struct netlink_tap *tmp;
156 
157         spin_lock(&netlink_tap_lock);
158 
159         list_for_each_entry(tmp, &netlink_tap_all, list) {
160                 if (nt == tmp) {
161                         list_del_rcu(&nt->list);
162                         found = true;
163                         goto out;
164                 }
165         }
166 
167         pr_warn("__netlink_remove_tap: %p not found\n", nt);
168 out:
169         spin_unlock(&netlink_tap_lock);
170 
171         if (found && nt->module)
172                 module_put(nt->module);
173 
174         return found ? 0 : -ENODEV;
175 }
176 
177 int netlink_remove_tap(struct netlink_tap *nt)
178 {
179         int ret;
180 
181         ret = __netlink_remove_tap(nt);
182         synchronize_net();
183 
184         return ret;
185 }
186 EXPORT_SYMBOL_GPL(netlink_remove_tap);
187 
188 static bool netlink_filter_tap(const struct sk_buff *skb)
189 {
190         struct sock *sk = skb->sk;
191 
192         /* We take the more conservative approach and
193          * whitelist socket protocols that may pass.
194          */
195         switch (sk->sk_protocol) {
196         case NETLINK_ROUTE:
197         case NETLINK_USERSOCK:
198         case NETLINK_SOCK_DIAG:
199         case NETLINK_NFLOG:
200         case NETLINK_XFRM:
201         case NETLINK_FIB_LOOKUP:
202         case NETLINK_NETFILTER:
203         case NETLINK_GENERIC:
204                 return true;
205         }
206 
207         return false;
208 }
209 
210 static int __netlink_deliver_tap_skb(struct sk_buff *skb,
211                                      struct net_device *dev)
212 {
213         struct sk_buff *nskb;
214         struct sock *sk = skb->sk;
215         int ret = -ENOMEM;
216 
217         dev_hold(dev);
218         nskb = skb_clone(skb, GFP_ATOMIC);
219         if (nskb) {
220                 nskb->dev = dev;
221                 nskb->protocol = htons((u16) sk->sk_protocol);
222                 nskb->pkt_type = netlink_is_kernel(sk) ?
223                                  PACKET_KERNEL : PACKET_USER;
224                 skb_reset_network_header(nskb);
225                 ret = dev_queue_xmit(nskb);
226                 if (unlikely(ret > 0))
227                         ret = net_xmit_errno(ret);
228         }
229 
230         dev_put(dev);
231         return ret;
232 }
233 
234 static void __netlink_deliver_tap(struct sk_buff *skb)
235 {
236         int ret;
237         struct netlink_tap *tmp;
238 
239         if (!netlink_filter_tap(skb))
240                 return;
241 
242         list_for_each_entry_rcu(tmp, &netlink_tap_all, list) {
243                 ret = __netlink_deliver_tap_skb(skb, tmp->dev);
244                 if (unlikely(ret))
245                         break;
246         }
247 }
248 
249 static void netlink_deliver_tap(struct sk_buff *skb)
250 {
251         rcu_read_lock();
252 
253         if (unlikely(!list_empty(&netlink_tap_all)))
254                 __netlink_deliver_tap(skb);
255 
256         rcu_read_unlock();
257 }
258 
259 static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
260                                        struct sk_buff *skb)
261 {
262         if (!(netlink_is_kernel(dst) && netlink_is_kernel(src)))
263                 netlink_deliver_tap(skb);
264 }
265 
266 static void netlink_overrun(struct sock *sk)
267 {
268         struct netlink_sock *nlk = nlk_sk(sk);
269 
270         if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
271                 if (!test_and_set_bit(NETLINK_CONGESTED, &nlk_sk(sk)->state)) {
272                         sk->sk_err = ENOBUFS;
273                         sk->sk_error_report(sk);
274                 }
275         }
276         atomic_inc(&sk->sk_drops);
277 }
278 
279 static void netlink_rcv_wake(struct sock *sk)
280 {
281         struct netlink_sock *nlk = nlk_sk(sk);
282 
283         if (skb_queue_empty(&sk->sk_receive_queue))
284                 clear_bit(NETLINK_CONGESTED, &nlk->state);
285         if (!test_bit(NETLINK_CONGESTED, &nlk->state))
286                 wake_up_interruptible(&nlk->wait);
287 }
288 
289 #ifdef CONFIG_NETLINK_MMAP
290 static bool netlink_skb_is_mmaped(const struct sk_buff *skb)
291 {
292         return NETLINK_CB(skb).flags & NETLINK_SKB_MMAPED;
293 }
294 
295 static bool netlink_rx_is_mmaped(struct sock *sk)
296 {
297         return nlk_sk(sk)->rx_ring.pg_vec != NULL;
298 }
299 
300 static bool netlink_tx_is_mmaped(struct sock *sk)
301 {
302         return nlk_sk(sk)->tx_ring.pg_vec != NULL;
303 }
304 
305 static __pure struct page *pgvec_to_page(const void *addr)
306 {
307         if (is_vmalloc_addr(addr))
308                 return vmalloc_to_page(addr);
309         else
310                 return virt_to_page(addr);
311 }
312 
313 static void free_pg_vec(void **pg_vec, unsigned int order, unsigned int len)
314 {
315         unsigned int i;
316 
317         for (i = 0; i < len; i++) {
318                 if (pg_vec[i] != NULL) {
319                         if (is_vmalloc_addr(pg_vec[i]))
320                                 vfree(pg_vec[i]);
321                         else
322                                 free_pages((unsigned long)pg_vec[i], order);
323                 }
324         }
325         kfree(pg_vec);
326 }
327 
328 static void *alloc_one_pg_vec_page(unsigned long order)
329 {
330         void *buffer;
331         gfp_t gfp_flags = GFP_KERNEL | __GFP_COMP | __GFP_ZERO |
332                           __GFP_NOWARN | __GFP_NORETRY;
333 
334         buffer = (void *)__get_free_pages(gfp_flags, order);
335         if (buffer != NULL)
336                 return buffer;
337 
338         buffer = vzalloc((1 << order) * PAGE_SIZE);
339         if (buffer != NULL)
340                 return buffer;
341 
342         gfp_flags &= ~__GFP_NORETRY;
343         return (void *)__get_free_pages(gfp_flags, order);
344 }
345 
346 static void **alloc_pg_vec(struct netlink_sock *nlk,
347                            struct nl_mmap_req *req, unsigned int order)
348 {
349         unsigned int block_nr = req->nm_block_nr;
350         unsigned int i;
351         void **pg_vec;
352 
353         pg_vec = kcalloc(block_nr, sizeof(void *), GFP_KERNEL);
354         if (pg_vec == NULL)
355                 return NULL;
356 
357         for (i = 0; i < block_nr; i++) {
358                 pg_vec[i] = alloc_one_pg_vec_page(order);
359                 if (pg_vec[i] == NULL)
360                         goto err1;
361         }
362 
363         return pg_vec;
364 err1:
365         free_pg_vec(pg_vec, order, block_nr);
366         return NULL;
367 }
368 
369 static int netlink_set_ring(struct sock *sk, struct nl_mmap_req *req,
370                             bool closing, bool tx_ring)
371 {
372         struct netlink_sock *nlk = nlk_sk(sk);
373         struct netlink_ring *ring;
374         struct sk_buff_head *queue;
375         void **pg_vec = NULL;
376         unsigned int order = 0;
377         int err;
378 
379         ring  = tx_ring ? &nlk->tx_ring : &nlk->rx_ring;
380         queue = tx_ring ? &sk->sk_write_queue : &sk->sk_receive_queue;
381 
382         if (!closing) {
383                 if (atomic_read(&nlk->mapped))
384                         return -EBUSY;
385                 if (atomic_read(&ring->pending))
386                         return -EBUSY;
387         }
388 
389         if (req->nm_block_nr) {
390                 if (ring->pg_vec != NULL)
391                         return -EBUSY;
392 
393                 if ((int)req->nm_block_size <= 0)
394                         return -EINVAL;
395                 if (!PAGE_ALIGNED(req->nm_block_size))
396                         return -EINVAL;
397                 if (req->nm_frame_size < NL_MMAP_HDRLEN)
398                         return -EINVAL;
399                 if (!IS_ALIGNED(req->nm_frame_size, NL_MMAP_MSG_ALIGNMENT))
400                         return -EINVAL;
401 
402                 ring->frames_per_block = req->nm_block_size /
403                                          req->nm_frame_size;
404                 if (ring->frames_per_block == 0)
405                         return -EINVAL;
406                 if (ring->frames_per_block * req->nm_block_nr !=
407                     req->nm_frame_nr)
408                         return -EINVAL;
409 
410                 order = get_order(req->nm_block_size);
411                 pg_vec = alloc_pg_vec(nlk, req, order);
412                 if (pg_vec == NULL)
413                         return -ENOMEM;
414         } else {
415                 if (req->nm_frame_nr)
416                         return -EINVAL;
417         }
418 
419         err = -EBUSY;
420         mutex_lock(&nlk->pg_vec_lock);
421         if (closing || atomic_read(&nlk->mapped) == 0) {
422                 err = 0;
423                 spin_lock_bh(&queue->lock);
424 
425                 ring->frame_max         = req->nm_frame_nr - 1;
426                 ring->head              = 0;
427                 ring->frame_size        = req->nm_frame_size;
428                 ring->pg_vec_pages      = req->nm_block_size / PAGE_SIZE;
429 
430                 swap(ring->pg_vec_len, req->nm_block_nr);
431                 swap(ring->pg_vec_order, order);
432                 swap(ring->pg_vec, pg_vec);
433 
434                 __skb_queue_purge(queue);
435                 spin_unlock_bh(&queue->lock);
436 
437                 WARN_ON(atomic_read(&nlk->mapped));
438         }
439         mutex_unlock(&nlk->pg_vec_lock);
440 
441         if (pg_vec)
442                 free_pg_vec(pg_vec, order, req->nm_block_nr);
443         return err;
444 }
445 
446 static void netlink_mm_open(struct vm_area_struct *vma)
447 {
448         struct file *file = vma->vm_file;
449         struct socket *sock = file->private_data;
450         struct sock *sk = sock->sk;
451 
452         if (sk)
453                 atomic_inc(&nlk_sk(sk)->mapped);
454 }
455 
456 static void netlink_mm_close(struct vm_area_struct *vma)
457 {
458         struct file *file = vma->vm_file;
459         struct socket *sock = file->private_data;
460         struct sock *sk = sock->sk;
461 
462         if (sk)
463                 atomic_dec(&nlk_sk(sk)->mapped);
464 }
465 
466 static const struct vm_operations_struct netlink_mmap_ops = {
467         .open   = netlink_mm_open,
468         .close  = netlink_mm_close,
469 };
470 
471 static int netlink_mmap(struct file *file, struct socket *sock,
472                         struct vm_area_struct *vma)
473 {
474         struct sock *sk = sock->sk;
475         struct netlink_sock *nlk = nlk_sk(sk);
476         struct netlink_ring *ring;
477         unsigned long start, size, expected;
478         unsigned int i;
479         int err = -EINVAL;
480 
481         if (vma->vm_pgoff)
482                 return -EINVAL;
483 
484         mutex_lock(&nlk->pg_vec_lock);
485 
486         expected = 0;
487         for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
488                 if (ring->pg_vec == NULL)
489                         continue;
490                 expected += ring->pg_vec_len * ring->pg_vec_pages * PAGE_SIZE;
491         }
492 
493         if (expected == 0)
494                 goto out;
495 
496         size = vma->vm_end - vma->vm_start;
497         if (size != expected)
498                 goto out;
499 
500         start = vma->vm_start;
501         for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
502                 if (ring->pg_vec == NULL)
503                         continue;
504 
505                 for (i = 0; i < ring->pg_vec_len; i++) {
506                         struct page *page;
507                         void *kaddr = ring->pg_vec[i];
508                         unsigned int pg_num;
509 
510                         for (pg_num = 0; pg_num < ring->pg_vec_pages; pg_num++) {
511                                 page = pgvec_to_page(kaddr);
512                                 err = vm_insert_page(vma, start, page);
513                                 if (err < 0)
514                                         goto out;
515                                 start += PAGE_SIZE;
516                                 kaddr += PAGE_SIZE;
517                         }
518                 }
519         }
520 
521         atomic_inc(&nlk->mapped);
522         vma->vm_ops = &netlink_mmap_ops;
523         err = 0;
524 out:
525         mutex_unlock(&nlk->pg_vec_lock);
526         return err;
527 }
528 
529 static void netlink_frame_flush_dcache(const struct nl_mmap_hdr *hdr, unsigned int nm_len)
530 {
531 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 1
532         struct page *p_start, *p_end;
533 
534         /* First page is flushed through netlink_{get,set}_status */
535         p_start = pgvec_to_page(hdr + PAGE_SIZE);
536         p_end   = pgvec_to_page((void *)hdr + NL_MMAP_HDRLEN + nm_len - 1);
537         while (p_start <= p_end) {
538                 flush_dcache_page(p_start);
539                 p_start++;
540         }
541 #endif
542 }
543 
544 static enum nl_mmap_status netlink_get_status(const struct nl_mmap_hdr *hdr)
545 {
546         smp_rmb();
547         flush_dcache_page(pgvec_to_page(hdr));
548         return hdr->nm_status;
549 }
550 
551 static void netlink_set_status(struct nl_mmap_hdr *hdr,
552                                enum nl_mmap_status status)
553 {
554         smp_mb();
555         hdr->nm_status = status;
556         flush_dcache_page(pgvec_to_page(hdr));
557 }
558 
559 static struct nl_mmap_hdr *
560 __netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos)
561 {
562         unsigned int pg_vec_pos, frame_off;
563 
564         pg_vec_pos = pos / ring->frames_per_block;
565         frame_off  = pos % ring->frames_per_block;
566 
567         return ring->pg_vec[pg_vec_pos] + (frame_off * ring->frame_size);
568 }
569 
570 static struct nl_mmap_hdr *
571 netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos,
572                      enum nl_mmap_status status)
573 {
574         struct nl_mmap_hdr *hdr;
575 
576         hdr = __netlink_lookup_frame(ring, pos);
577         if (netlink_get_status(hdr) != status)
578                 return NULL;
579 
580         return hdr;
581 }
582 
583 static struct nl_mmap_hdr *
584 netlink_current_frame(const struct netlink_ring *ring,
585                       enum nl_mmap_status status)
586 {
587         return netlink_lookup_frame(ring, ring->head, status);
588 }
589 
590 static struct nl_mmap_hdr *
591 netlink_previous_frame(const struct netlink_ring *ring,
592                        enum nl_mmap_status status)
593 {
594         unsigned int prev;
595 
596         prev = ring->head ? ring->head - 1 : ring->frame_max;
597         return netlink_lookup_frame(ring, prev, status);
598 }
599 
600 static void netlink_increment_head(struct netlink_ring *ring)
601 {
602         ring->head = ring->head != ring->frame_max ? ring->head + 1 : 0;
603 }
604 
605 static void netlink_forward_ring(struct netlink_ring *ring)
606 {
607         unsigned int head = ring->head, pos = head;
608         const struct nl_mmap_hdr *hdr;
609 
610         do {
611                 hdr = __netlink_lookup_frame(ring, pos);
612                 if (hdr->nm_status == NL_MMAP_STATUS_UNUSED)
613                         break;
614                 if (hdr->nm_status != NL_MMAP_STATUS_SKIP)
615                         break;
616                 netlink_increment_head(ring);
617         } while (ring->head != head);
618 }
619 
620 static bool netlink_dump_space(struct netlink_sock *nlk)
621 {
622         struct netlink_ring *ring = &nlk->rx_ring;
623         struct nl_mmap_hdr *hdr;
624         unsigned int n;
625 
626         hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
627         if (hdr == NULL)
628                 return false;
629 
630         n = ring->head + ring->frame_max / 2;
631         if (n > ring->frame_max)
632                 n -= ring->frame_max;
633 
634         hdr = __netlink_lookup_frame(ring, n);
635 
636         return hdr->nm_status == NL_MMAP_STATUS_UNUSED;
637 }
638 
639 static unsigned int netlink_poll(struct file *file, struct socket *sock,
640                                  poll_table *wait)
641 {
642         struct sock *sk = sock->sk;
643         struct netlink_sock *nlk = nlk_sk(sk);
644         unsigned int mask;
645         int err;
646 
647         if (nlk->rx_ring.pg_vec != NULL) {
648                 /* Memory mapped sockets don't call recvmsg(), so flow control
649                  * for dumps is performed here. A dump is allowed to continue
650                  * if at least half the ring is unused.
651                  */
652                 while (nlk->cb_running && netlink_dump_space(nlk)) {
653                         err = netlink_dump(sk);
654                         if (err < 0) {
655                                 sk->sk_err = -err;
656                                 sk->sk_error_report(sk);
657                                 break;
658                         }
659                 }
660                 netlink_rcv_wake(sk);
661         }
662 
663         mask = datagram_poll(file, sock, wait);
664 
665         spin_lock_bh(&sk->sk_receive_queue.lock);
666         if (nlk->rx_ring.pg_vec) {
667                 netlink_forward_ring(&nlk->rx_ring);
668                 if (!netlink_previous_frame(&nlk->rx_ring, NL_MMAP_STATUS_UNUSED))
669                         mask |= POLLIN | POLLRDNORM;
670         }
671         spin_unlock_bh(&sk->sk_receive_queue.lock);
672 
673         spin_lock_bh(&sk->sk_write_queue.lock);
674         if (nlk->tx_ring.pg_vec) {
675                 if (netlink_current_frame(&nlk->tx_ring, NL_MMAP_STATUS_UNUSED))
676                         mask |= POLLOUT | POLLWRNORM;
677         }
678         spin_unlock_bh(&sk->sk_write_queue.lock);
679 
680         return mask;
681 }
682 
683 static struct nl_mmap_hdr *netlink_mmap_hdr(struct sk_buff *skb)
684 {
685         return (struct nl_mmap_hdr *)(skb->head - NL_MMAP_HDRLEN);
686 }
687 
688 static void netlink_ring_setup_skb(struct sk_buff *skb, struct sock *sk,
689                                    struct netlink_ring *ring,
690                                    struct nl_mmap_hdr *hdr)
691 {
692         unsigned int size;
693         void *data;
694 
695         size = ring->frame_size - NL_MMAP_HDRLEN;
696         data = (void *)hdr + NL_MMAP_HDRLEN;
697 
698         skb->head       = data;
699         skb->data       = data;
700         skb_reset_tail_pointer(skb);
701         skb->end        = skb->tail + size;
702         skb->len        = 0;
703 
704         skb->destructor = netlink_skb_destructor;
705         NETLINK_CB(skb).flags |= NETLINK_SKB_MMAPED;
706         NETLINK_CB(skb).sk = sk;
707 }
708 
709 static int netlink_mmap_sendmsg(struct sock *sk, struct msghdr *msg,
710                                 u32 dst_portid, u32 dst_group,
711                                 struct sock_iocb *siocb)
712 {
713         struct netlink_sock *nlk = nlk_sk(sk);
714         struct netlink_ring *ring;
715         struct nl_mmap_hdr *hdr;
716         struct sk_buff *skb;
717         unsigned int maxlen;
718         int err = 0, len = 0;
719 
720         mutex_lock(&nlk->pg_vec_lock);
721 
722         ring   = &nlk->tx_ring;
723         maxlen = ring->frame_size - NL_MMAP_HDRLEN;
724 
725         do {
726                 unsigned int nm_len;
727 
728                 hdr = netlink_current_frame(ring, NL_MMAP_STATUS_VALID);
729                 if (hdr == NULL) {
730                         if (!(msg->msg_flags & MSG_DONTWAIT) &&
731                             atomic_read(&nlk->tx_ring.pending))
732                                 schedule();
733                         continue;
734                 }
735 
736                 nm_len = ACCESS_ONCE(hdr->nm_len);
737                 if (nm_len > maxlen) {
738                         err = -EINVAL;
739                         goto out;
740                 }
741 
742                 netlink_frame_flush_dcache(hdr, nm_len);
743 
744                 skb = alloc_skb(nm_len, GFP_KERNEL);
745                 if (skb == NULL) {
746                         err = -ENOBUFS;
747                         goto out;
748                 }
749                 __skb_put(skb, nm_len);
750                 memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, nm_len);
751                 netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
752 
753                 netlink_increment_head(ring);
754 
755                 NETLINK_CB(skb).portid    = nlk->portid;
756                 NETLINK_CB(skb).dst_group = dst_group;
757                 NETLINK_CB(skb).creds     = siocb->scm->creds;
758 
759                 err = security_netlink_send(sk, skb);
760                 if (err) {
761                         kfree_skb(skb);
762                         goto out;
763                 }
764 
765                 if (unlikely(dst_group)) {
766                         atomic_inc(&skb->users);
767                         netlink_broadcast(sk, skb, dst_portid, dst_group,
768                                           GFP_KERNEL);
769                 }
770                 err = netlink_unicast(sk, skb, dst_portid,
771                                       msg->msg_flags & MSG_DONTWAIT);
772                 if (err < 0)
773                         goto out;
774                 len += err;
775 
776         } while (hdr != NULL ||
777                  (!(msg->msg_flags & MSG_DONTWAIT) &&
778                   atomic_read(&nlk->tx_ring.pending)));
779 
780         if (len > 0)
781                 err = len;
782 out:
783         mutex_unlock(&nlk->pg_vec_lock);
784         return err;
785 }
786 
787 static void netlink_queue_mmaped_skb(struct sock *sk, struct sk_buff *skb)
788 {
789         struct nl_mmap_hdr *hdr;
790 
791         hdr = netlink_mmap_hdr(skb);
792         hdr->nm_len     = skb->len;
793         hdr->nm_group   = NETLINK_CB(skb).dst_group;
794         hdr->nm_pid     = NETLINK_CB(skb).creds.pid;
795         hdr->nm_uid     = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
796         hdr->nm_gid     = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
797         netlink_frame_flush_dcache(hdr, hdr->nm_len);
798         netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
799 
800         NETLINK_CB(skb).flags |= NETLINK_SKB_DELIVERED;
801         kfree_skb(skb);
802 }
803 
804 static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
805 {
806         struct netlink_sock *nlk = nlk_sk(sk);
807         struct netlink_ring *ring = &nlk->rx_ring;
808         struct nl_mmap_hdr *hdr;
809 
810         spin_lock_bh(&sk->sk_receive_queue.lock);
811         hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
812         if (hdr == NULL) {
813                 spin_unlock_bh(&sk->sk_receive_queue.lock);
814                 kfree_skb(skb);
815                 netlink_overrun(sk);
816                 return;
817         }
818         netlink_increment_head(ring);
819         __skb_queue_tail(&sk->sk_receive_queue, skb);
820         spin_unlock_bh(&sk->sk_receive_queue.lock);
821 
822         hdr->nm_len     = skb->len;
823         hdr->nm_group   = NETLINK_CB(skb).dst_group;
824         hdr->nm_pid     = NETLINK_CB(skb).creds.pid;
825         hdr->nm_uid     = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
826         hdr->nm_gid     = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
827         netlink_set_status(hdr, NL_MMAP_STATUS_COPY);
828 }
829 
830 #else /* CONFIG_NETLINK_MMAP */
831 #define netlink_skb_is_mmaped(skb)      false
832 #define netlink_rx_is_mmaped(sk)        false
833 #define netlink_tx_is_mmaped(sk)        false
834 #define netlink_mmap                    sock_no_mmap
835 #define netlink_poll                    datagram_poll
836 #define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, siocb)     0
837 #endif /* CONFIG_NETLINK_MMAP */
838 
839 static void netlink_skb_destructor(struct sk_buff *skb)
840 {
841 #ifdef CONFIG_NETLINK_MMAP
842         struct nl_mmap_hdr *hdr;
843         struct netlink_ring *ring;
844         struct sock *sk;
845 
846         /* If a packet from the kernel to userspace was freed because of an
847          * error without being delivered to userspace, the kernel must reset
848          * the status. In the direction userspace to kernel, the status is
849          * always reset here after the packet was processed and freed.
850          */
851         if (netlink_skb_is_mmaped(skb)) {
852                 hdr = netlink_mmap_hdr(skb);
853                 sk = NETLINK_CB(skb).sk;
854 
855                 if (NETLINK_CB(skb).flags & NETLINK_SKB_TX) {
856                         netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
857                         ring = &nlk_sk(sk)->tx_ring;
858                 } else {
859                         if (!(NETLINK_CB(skb).flags & NETLINK_SKB_DELIVERED)) {
860                                 hdr->nm_len = 0;
861                                 netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
862                         }
863                         ring = &nlk_sk(sk)->rx_ring;
864                 }
865 
866                 WARN_ON(atomic_read(&ring->pending) == 0);
867                 atomic_dec(&ring->pending);
868                 sock_put(sk);
869 
870                 skb->head = NULL;
871         }
872 #endif
873         if (is_vmalloc_addr(skb->head)) {
874                 if (!skb->cloned ||
875                     !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
876                         vfree(skb->head);
877 
878                 skb->head = NULL;
879         }
880         if (skb->sk != NULL)
881                 sock_rfree(skb);
882 }
883 
884 static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
885 {
886         WARN_ON(skb->sk != NULL);
887         skb->sk = sk;
888         skb->destructor = netlink_skb_destructor;
889         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
890         sk_mem_charge(sk, skb->truesize);
891 }
892 
893 static void netlink_sock_destruct(struct sock *sk)
894 {
895         struct netlink_sock *nlk = nlk_sk(sk);
896 
897         if (nlk->cb_running) {
898                 if (nlk->cb.done)
899                         nlk->cb.done(&nlk->cb);
900 
901                 module_put(nlk->cb.module);
902                 kfree_skb(nlk->cb.skb);
903         }
904 
905         skb_queue_purge(&sk->sk_receive_queue);
906 #ifdef CONFIG_NETLINK_MMAP
907         if (1) {
908                 struct nl_mmap_req req;
909 
910                 memset(&req, 0, sizeof(req));
911                 if (nlk->rx_ring.pg_vec)
912                         netlink_set_ring(sk, &req, true, false);
913                 memset(&req, 0, sizeof(req));
914                 if (nlk->tx_ring.pg_vec)
915                         netlink_set_ring(sk, &req, true, true);
916         }
917 #endif /* CONFIG_NETLINK_MMAP */
918 
919         if (!sock_flag(sk, SOCK_DEAD)) {
920                 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
921                 return;
922         }
923 
924         WARN_ON(atomic_read(&sk->sk_rmem_alloc));
925         WARN_ON(atomic_read(&sk->sk_wmem_alloc));
926         WARN_ON(nlk_sk(sk)->groups);
927 }
928 
929 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
930  * SMP. Look, when several writers sleep and reader wakes them up, all but one
931  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
932  * this, _but_ remember, it adds useless work on UP machines.
933  */
934 
935 void netlink_table_grab(void)
936         __acquires(nl_table_lock)
937 {
938         might_sleep();
939 
940         write_lock_irq(&nl_table_lock);
941 
942         if (atomic_read(&nl_table_users)) {
943                 DECLARE_WAITQUEUE(wait, current);
944 
945                 add_wait_queue_exclusive(&nl_table_wait, &wait);
946                 for (;;) {
947                         set_current_state(TASK_UNINTERRUPTIBLE);
948                         if (atomic_read(&nl_table_users) == 0)
949                                 break;
950                         write_unlock_irq(&nl_table_lock);
951                         schedule();
952                         write_lock_irq(&nl_table_lock);
953                 }
954 
955                 __set_current_state(TASK_RUNNING);
956                 remove_wait_queue(&nl_table_wait, &wait);
957         }
958 }
959 
960 void netlink_table_ungrab(void)
961         __releases(nl_table_lock)
962 {
963         write_unlock_irq(&nl_table_lock);
964         wake_up(&nl_table_wait);
965 }
966 
967 static inline void
968 netlink_lock_table(void)
969 {
970         /* read_lock() synchronizes us to netlink_table_grab */
971 
972         read_lock(&nl_table_lock);
973         atomic_inc(&nl_table_users);
974         read_unlock(&nl_table_lock);
975 }
976 
977 static inline void
978 netlink_unlock_table(void)
979 {
980         if (atomic_dec_and_test(&nl_table_users))
981                 wake_up(&nl_table_wait);
982 }
983 
984 struct netlink_compare_arg
985 {
986         struct net *net;
987         u32 portid;
988 };
989 
990 static bool netlink_compare(void *ptr, void *arg)
991 {
992         struct netlink_compare_arg *x = arg;
993         struct sock *sk = ptr;
994 
995         return nlk_sk(sk)->portid == x->portid &&
996                net_eq(sock_net(sk), x->net);
997 }
998 
999 static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
1000                                      struct net *net)
1001 {
1002         struct netlink_compare_arg arg = {
1003                 .net = net,
1004                 .portid = portid,
1005         };
1006         u32 hash;
1007 
1008         hash = rhashtable_hashfn(&table->hash, &portid, sizeof(portid));
1009 
1010         return rhashtable_lookup_compare(&table->hash, hash,
1011                                          &netlink_compare, &arg);
1012 }
1013 
1014 static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
1015 {
1016         struct netlink_table *table = &nl_table[protocol];
1017         struct sock *sk;
1018 
1019         read_lock(&nl_table_lock);
1020         rcu_read_lock();
1021         sk = __netlink_lookup(table, portid, net);
1022         if (sk)
1023                 sock_hold(sk);
1024         rcu_read_unlock();
1025         read_unlock(&nl_table_lock);
1026 
1027         return sk;
1028 }
1029 
1030 static const struct proto_ops netlink_ops;
1031 
1032 static void
1033 netlink_update_listeners(struct sock *sk)
1034 {
1035         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
1036         unsigned long mask;
1037         unsigned int i;
1038         struct listeners *listeners;
1039 
1040         listeners = nl_deref_protected(tbl->listeners);
1041         if (!listeners)
1042                 return;
1043 
1044         for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
1045                 mask = 0;
1046                 sk_for_each_bound(sk, &tbl->mc_list) {
1047                         if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
1048                                 mask |= nlk_sk(sk)->groups[i];
1049                 }
1050                 listeners->masks[i] = mask;
1051         }
1052         /* this function is only called with the netlink table "grabbed", which
1053          * makes sure updates are visible before bind or setsockopt return. */
1054 }
1055 
1056 static int netlink_insert(struct sock *sk, struct net *net, u32 portid)
1057 {
1058         struct netlink_table *table = &nl_table[sk->sk_protocol];
1059         int err = -EADDRINUSE;
1060 
1061         mutex_lock(&nl_sk_hash_lock);
1062         if (__netlink_lookup(table, portid, net))
1063                 goto err;
1064 
1065         err = -EBUSY;
1066         if (nlk_sk(sk)->portid)
1067                 goto err;
1068 
1069         err = -ENOMEM;
1070         if (BITS_PER_LONG > 32 && unlikely(table->hash.nelems >= UINT_MAX))
1071                 goto err;
1072 
1073         nlk_sk(sk)->portid = portid;
1074         sock_hold(sk);
1075         rhashtable_insert(&table->hash, &nlk_sk(sk)->node);
1076         err = 0;
1077 err:
1078         mutex_unlock(&nl_sk_hash_lock);
1079         return err;
1080 }
1081 
1082 static void netlink_remove(struct sock *sk)
1083 {
1084         struct netlink_table *table;
1085 
1086         mutex_lock(&nl_sk_hash_lock);
1087         table = &nl_table[sk->sk_protocol];
1088         if (rhashtable_remove(&table->hash, &nlk_sk(sk)->node)) {
1089                 WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
1090                 __sock_put(sk);
1091         }
1092         mutex_unlock(&nl_sk_hash_lock);
1093 
1094         netlink_table_grab();
1095         if (nlk_sk(sk)->subscriptions) {
1096                 __sk_del_bind_node(sk);
1097                 netlink_update_listeners(sk);
1098         }
1099         if (sk->sk_protocol == NETLINK_GENERIC)
1100                 atomic_inc(&genl_sk_destructing_cnt);
1101         netlink_table_ungrab();
1102 }
1103 
1104 static struct proto netlink_proto = {
1105         .name     = "NETLINK",
1106         .owner    = THIS_MODULE,
1107         .obj_size = sizeof(struct netlink_sock),
1108 };
1109 
1110 static int __netlink_create(struct net *net, struct socket *sock,
1111                             struct mutex *cb_mutex, int protocol)
1112 {
1113         struct sock *sk;
1114         struct netlink_sock *nlk;
1115 
1116         sock->ops = &netlink_ops;
1117 
1118         sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto);
1119         if (!sk)
1120                 return -ENOMEM;
1121 
1122         sock_init_data(sock, sk);
1123 
1124         nlk = nlk_sk(sk);
1125         if (cb_mutex) {
1126                 nlk->cb_mutex = cb_mutex;
1127         } else {
1128                 nlk->cb_mutex = &nlk->cb_def_mutex;
1129                 mutex_init(nlk->cb_mutex);
1130         }
1131         init_waitqueue_head(&nlk->wait);
1132 #ifdef CONFIG_NETLINK_MMAP
1133         mutex_init(&nlk->pg_vec_lock);
1134 #endif
1135 
1136         sk->sk_destruct = netlink_sock_destruct;
1137         sk->sk_protocol = protocol;
1138         return 0;
1139 }
1140 
1141 static int netlink_create(struct net *net, struct socket *sock, int protocol,
1142                           int kern)
1143 {
1144         struct module *module = NULL;
1145         struct mutex *cb_mutex;
1146         struct netlink_sock *nlk;
1147         int (*bind)(struct net *net, int group);
1148         void (*unbind)(struct net *net, int group);
1149         int err = 0;
1150 
1151         sock->state = SS_UNCONNECTED;
1152 
1153         if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
1154                 return -ESOCKTNOSUPPORT;
1155 
1156         if (protocol < 0 || protocol >= MAX_LINKS)
1157                 return -EPROTONOSUPPORT;
1158 
1159         netlink_lock_table();
1160 #ifdef CONFIG_MODULES
1161         if (!nl_table[protocol].registered) {
1162                 netlink_unlock_table();
1163                 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
1164                 netlink_lock_table();
1165         }
1166 #endif
1167         if (nl_table[protocol].registered &&
1168             try_module_get(nl_table[protocol].module))
1169                 module = nl_table[protocol].module;
1170         else
1171                 err = -EPROTONOSUPPORT;
1172         cb_mutex = nl_table[protocol].cb_mutex;
1173         bind = nl_table[protocol].bind;
1174         unbind = nl_table[protocol].unbind;
1175         netlink_unlock_table();
1176 
1177         if (err < 0)
1178                 goto out;
1179 
1180         err = __netlink_create(net, sock, cb_mutex, protocol);
1181         if (err < 0)
1182                 goto out_module;
1183 
1184         local_bh_disable();
1185         sock_prot_inuse_add(net, &netlink_proto, 1);
1186         local_bh_enable();
1187 
1188         nlk = nlk_sk(sock->sk);
1189         nlk->module = module;
1190         nlk->netlink_bind = bind;
1191         nlk->netlink_unbind = unbind;
1192 out:
1193         return err;
1194 
1195 out_module:
1196         module_put(module);
1197         goto out;
1198 }
1199 
1200 static int netlink_release(struct socket *sock)
1201 {
1202         struct sock *sk = sock->sk;
1203         struct netlink_sock *nlk;
1204 
1205         if (!sk)
1206                 return 0;
1207 
1208         netlink_remove(sk);
1209         sock_orphan(sk);
1210         nlk = nlk_sk(sk);
1211 
1212         /*
1213          * OK. Socket is unlinked, any packets that arrive now
1214          * will be purged.
1215          */
1216 
1217         /* must not acquire netlink_table_lock in any way again before unbind
1218          * and notifying genetlink is done as otherwise it might deadlock
1219          */
1220         if (nlk->netlink_unbind) {
1221                 int i;
1222 
1223                 for (i = 0; i < nlk->ngroups; i++)
1224                         if (test_bit(i, nlk->groups))
1225                                 nlk->netlink_unbind(sock_net(sk), i + 1);
1226         }
1227         if (sk->sk_protocol == NETLINK_GENERIC &&
1228             atomic_dec_return(&genl_sk_destructing_cnt) == 0)
1229                 wake_up(&genl_sk_destructing_waitq);
1230 
1231         sock->sk = NULL;
1232         wake_up_interruptible_all(&nlk->wait);
1233 
1234         skb_queue_purge(&sk->sk_write_queue);
1235 
1236         if (nlk->portid) {
1237                 struct netlink_notify n = {
1238                                                 .net = sock_net(sk),
1239                                                 .protocol = sk->sk_protocol,
1240                                                 .portid = nlk->portid,
1241                                           };
1242                 atomic_notifier_call_chain(&netlink_chain,
1243                                 NETLINK_URELEASE, &n);
1244         }
1245 
1246         module_put(nlk->module);
1247 
1248         if (netlink_is_kernel(sk)) {
1249                 netlink_table_grab();
1250                 BUG_ON(nl_table[sk->sk_protocol].registered == 0);
1251                 if (--nl_table[sk->sk_protocol].registered == 0) {
1252                         struct listeners *old;
1253 
1254                         old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
1255                         RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
1256                         kfree_rcu(old, rcu);
1257                         nl_table[sk->sk_protocol].module = NULL;
1258                         nl_table[sk->sk_protocol].bind = NULL;
1259                         nl_table[sk->sk_protocol].unbind = NULL;
1260                         nl_table[sk->sk_protocol].flags = 0;
1261                         nl_table[sk->sk_protocol].registered = 0;
1262                 }
1263                 netlink_table_ungrab();
1264         }
1265 
1266         kfree(nlk->groups);
1267         nlk->groups = NULL;
1268 
1269         local_bh_disable();
1270         sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
1271         local_bh_enable();
1272         sock_put(sk);
1273         return 0;
1274 }
1275 
1276 static int netlink_autobind(struct socket *sock)
1277 {
1278         struct sock *sk = sock->sk;
1279         struct net *net = sock_net(sk);
1280         struct netlink_table *table = &nl_table[sk->sk_protocol];
1281         s32 portid = task_tgid_vnr(current);
1282         int err;
1283         static s32 rover = -4097;
1284 
1285 retry:
1286         cond_resched();
1287         netlink_table_grab();
1288         rcu_read_lock();
1289         if (__netlink_lookup(table, portid, net)) {
1290                 /* Bind collision, search negative portid values. */
1291                 portid = rover--;
1292                 if (rover > -4097)
1293                         rover = -4097;
1294                 rcu_read_unlock();
1295                 netlink_table_ungrab();
1296                 goto retry;
1297         }
1298         rcu_read_unlock();
1299         netlink_table_ungrab();
1300 
1301         err = netlink_insert(sk, net, portid);
1302         if (err == -EADDRINUSE)
1303                 goto retry;
1304 
1305         /* If 2 threads race to autobind, that is fine.  */
1306         if (err == -EBUSY)
1307                 err = 0;
1308 
1309         return err;
1310 }
1311 
1312 /**
1313  * __netlink_ns_capable - General netlink message capability test
1314  * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
1315  * @user_ns: The user namespace of the capability to use
1316  * @cap: The capability to use
1317  *
1318  * Test to see if the opener of the socket we received the message
1319  * from had when the netlink socket was created and the sender of the
1320  * message has has the capability @cap in the user namespace @user_ns.
1321  */
1322 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
1323                         struct user_namespace *user_ns, int cap)
1324 {
1325         return ((nsp->flags & NETLINK_SKB_DST) ||
1326                 file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
1327                 ns_capable(user_ns, cap);
1328 }
1329 EXPORT_SYMBOL(__netlink_ns_capable);
1330 
1331 /**
1332  * netlink_ns_capable - General netlink message capability test
1333  * @skb: socket buffer holding a netlink command from userspace
1334  * @user_ns: The user namespace of the capability to use
1335  * @cap: The capability to use
1336  *
1337  * Test to see if the opener of the socket we received the message
1338  * from had when the netlink socket was created and the sender of the
1339  * message has has the capability @cap in the user namespace @user_ns.
1340  */
1341 bool netlink_ns_capable(const struct sk_buff *skb,
1342                         struct user_namespace *user_ns, int cap)
1343 {
1344         return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
1345 }
1346 EXPORT_SYMBOL(netlink_ns_capable);
1347 
1348 /**
1349  * netlink_capable - Netlink global message capability test
1350  * @skb: socket buffer holding a netlink command from userspace
1351  * @cap: The capability to use
1352  *
1353  * Test to see if the opener of the socket we received the message
1354  * from had when the netlink socket was created and the sender of the
1355  * message has has the capability @cap in all user namespaces.
1356  */
1357 bool netlink_capable(const struct sk_buff *skb, int cap)
1358 {
1359         return netlink_ns_capable(skb, &init_user_ns, cap);
1360 }
1361 EXPORT_SYMBOL(netlink_capable);
1362 
1363 /**
1364  * netlink_net_capable - Netlink network namespace message capability test
1365  * @skb: socket buffer holding a netlink command from userspace
1366  * @cap: The capability to use
1367  *
1368  * Test to see if the opener of the socket we received the message
1369  * from had when the netlink socket was created and the sender of the
1370  * message has has the capability @cap over the network namespace of
1371  * the socket we received the message from.
1372  */
1373 bool netlink_net_capable(const struct sk_buff *skb, int cap)
1374 {
1375         return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
1376 }
1377 EXPORT_SYMBOL(netlink_net_capable);
1378 
1379 static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
1380 {
1381         return (nl_table[sock->sk->sk_protocol].flags & flag) ||
1382                 ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
1383 }
1384 
1385 static void
1386 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
1387 {
1388         struct netlink_sock *nlk = nlk_sk(sk);
1389 
1390         if (nlk->subscriptions && !subscriptions)
1391                 __sk_del_bind_node(sk);
1392         else if (!nlk->subscriptions && subscriptions)
1393                 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
1394         nlk->subscriptions = subscriptions;
1395 }
1396 
1397 static int netlink_realloc_groups(struct sock *sk)
1398 {
1399         struct netlink_sock *nlk = nlk_sk(sk);
1400         unsigned int groups;
1401         unsigned long *new_groups;
1402         int err = 0;
1403 
1404         netlink_table_grab();
1405 
1406         groups = nl_table[sk->sk_protocol].groups;
1407         if (!nl_table[sk->sk_protocol].registered) {
1408                 err = -ENOENT;
1409                 goto out_unlock;
1410         }
1411 
1412         if (nlk->ngroups >= groups)
1413                 goto out_unlock;
1414 
1415         new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
1416         if (new_groups == NULL) {
1417                 err = -ENOMEM;
1418                 goto out_unlock;
1419         }
1420         memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
1421                NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
1422 
1423         nlk->groups = new_groups;
1424         nlk->ngroups = groups;
1425  out_unlock:
1426         netlink_table_ungrab();
1427         return err;
1428 }
1429 
1430 static void netlink_undo_bind(int group, long unsigned int groups,
1431                               struct sock *sk)
1432 {
1433         struct netlink_sock *nlk = nlk_sk(sk);
1434         int undo;
1435 
1436         if (!nlk->netlink_unbind)
1437                 return;
1438 
1439         for (undo = 0; undo < group; undo++)
1440                 if (test_bit(undo, &groups))
1441                         nlk->netlink_unbind(sock_net(sk), undo + 1);
1442 }
1443 
1444 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
1445                         int addr_len)
1446 {
1447         struct sock *sk = sock->sk;
1448         struct net *net = sock_net(sk);
1449         struct netlink_sock *nlk = nlk_sk(sk);
1450         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
1451         int err;
1452         long unsigned int groups = nladdr->nl_groups;
1453 
1454         if (addr_len < sizeof(struct sockaddr_nl))
1455                 return -EINVAL;
1456 
1457         if (nladdr->nl_family != AF_NETLINK)
1458                 return -EINVAL;
1459 
1460         /* Only superuser is allowed to listen multicasts */
1461         if (groups) {
1462                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
1463                         return -EPERM;
1464                 err = netlink_realloc_groups(sk);
1465                 if (err)
1466                         return err;
1467         }
1468 
1469         if (nlk->portid)
1470                 if (nladdr->nl_pid != nlk->portid)
1471                         return -EINVAL;
1472 
1473         if (nlk->netlink_bind && groups) {
1474                 int group;
1475 
1476                 for (group = 0; group < nlk->ngroups; group++) {
1477                         if (!test_bit(group, &groups))
1478                                 continue;
1479                         err = nlk->netlink_bind(net, group + 1);
1480                         if (!err)
1481                                 continue;
1482                         netlink_undo_bind(group, groups, sk);
1483                         return err;
1484                 }
1485         }
1486 
1487         if (!nlk->portid) {
1488                 err = nladdr->nl_pid ?
1489                         netlink_insert(sk, net, nladdr->nl_pid) :
1490                         netlink_autobind(sock);
1491                 if (err) {
1492                         netlink_undo_bind(nlk->ngroups, groups, sk);
1493                         return err;
1494                 }
1495         }
1496 
1497         if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
1498                 return 0;
1499 
1500         netlink_table_grab();
1501         netlink_update_subscriptions(sk, nlk->subscriptions +
1502                                          hweight32(groups) -
1503                                          hweight32(nlk->groups[0]));
1504         nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups;
1505         netlink_update_listeners(sk);
1506         netlink_table_ungrab();
1507 
1508         return 0;
1509 }
1510 
1511 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
1512                            int alen, int flags)
1513 {
1514         int err = 0;
1515         struct sock *sk = sock->sk;
1516         struct netlink_sock *nlk = nlk_sk(sk);
1517         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
1518 
1519         if (alen < sizeof(addr->sa_family))
1520                 return -EINVAL;
1521 
1522         if (addr->sa_family == AF_UNSPEC) {
1523                 sk->sk_state    = NETLINK_UNCONNECTED;
1524                 nlk->dst_portid = 0;
1525                 nlk->dst_group  = 0;
1526                 return 0;
1527         }
1528         if (addr->sa_family != AF_NETLINK)
1529                 return -EINVAL;
1530 
1531         if ((nladdr->nl_groups || nladdr->nl_pid) &&
1532             !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1533                 return -EPERM;
1534 
1535         if (!nlk->portid)
1536                 err = netlink_autobind(sock);
1537 
1538         if (err == 0) {
1539                 sk->sk_state    = NETLINK_CONNECTED;
1540                 nlk->dst_portid = nladdr->nl_pid;
1541                 nlk->dst_group  = ffs(nladdr->nl_groups);
1542         }
1543 
1544         return err;
1545 }
1546 
1547 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
1548                            int *addr_len, int peer)
1549 {
1550         struct sock *sk = sock->sk;
1551         struct netlink_sock *nlk = nlk_sk(sk);
1552         DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
1553 
1554         nladdr->nl_family = AF_NETLINK;
1555         nladdr->nl_pad = 0;
1556         *addr_len = sizeof(*nladdr);
1557 
1558         if (peer) {
1559                 nladdr->nl_pid = nlk->dst_portid;
1560                 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
1561         } else {
1562                 nladdr->nl_pid = nlk->portid;
1563                 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
1564         }
1565         return 0;
1566 }
1567 
1568 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
1569 {
1570         struct sock *sock;
1571         struct netlink_sock *nlk;
1572 
1573         sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
1574         if (!sock)
1575                 return ERR_PTR(-ECONNREFUSED);
1576 
1577         /* Don't bother queuing skb if kernel socket has no input function */
1578         nlk = nlk_sk(sock);
1579         if (sock->sk_state == NETLINK_CONNECTED &&
1580             nlk->dst_portid != nlk_sk(ssk)->portid) {
1581                 sock_put(sock);
1582                 return ERR_PTR(-ECONNREFUSED);
1583         }
1584         return sock;
1585 }
1586 
1587 struct sock *netlink_getsockbyfilp(struct file *filp)
1588 {
1589         struct inode *inode = file_inode(filp);
1590         struct sock *sock;
1591 
1592         if (!S_ISSOCK(inode->i_mode))
1593                 return ERR_PTR(-ENOTSOCK);
1594 
1595         sock = SOCKET_I(inode)->sk;
1596         if (sock->sk_family != AF_NETLINK)
1597                 return ERR_PTR(-EINVAL);
1598 
1599         sock_hold(sock);
1600         return sock;
1601 }
1602 
1603 static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
1604                                                int broadcast)
1605 {
1606         struct sk_buff *skb;
1607         void *data;
1608 
1609         if (size <= NLMSG_GOODSIZE || broadcast)
1610                 return alloc_skb(size, GFP_KERNEL);
1611 
1612         size = SKB_DATA_ALIGN(size) +
1613                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
1614 
1615         data = vmalloc(size);
1616         if (data == NULL)
1617                 return NULL;
1618 
1619         skb = __build_skb(data, size);
1620         if (skb == NULL)
1621                 vfree(data);
1622         else
1623                 skb->destructor = netlink_skb_destructor;
1624 
1625         return skb;
1626 }
1627 
1628 /*
1629  * Attach a skb to a netlink socket.
1630  * The caller must hold a reference to the destination socket. On error, the
1631  * reference is dropped. The skb is not send to the destination, just all
1632  * all error checks are performed and memory in the queue is reserved.
1633  * Return values:
1634  * < 0: error. skb freed, reference to sock dropped.
1635  * 0: continue
1636  * 1: repeat lookup - reference dropped while waiting for socket memory.
1637  */
1638 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
1639                       long *timeo, struct sock *ssk)
1640 {
1641         struct netlink_sock *nlk;
1642 
1643         nlk = nlk_sk(sk);
1644 
1645         if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1646              test_bit(NETLINK_CONGESTED, &nlk->state)) &&
1647             !netlink_skb_is_mmaped(skb)) {
1648                 DECLARE_WAITQUEUE(wait, current);
1649                 if (!*timeo) {
1650                         if (!ssk || netlink_is_kernel(ssk))
1651                                 netlink_overrun(sk);
1652                         sock_put(sk);
1653                         kfree_skb(skb);
1654                         return -EAGAIN;
1655                 }
1656 
1657                 __set_current_state(TASK_INTERRUPTIBLE);
1658                 add_wait_queue(&nlk->wait, &wait);
1659 
1660                 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1661                      test_bit(NETLINK_CONGESTED, &nlk->state)) &&
1662                     !sock_flag(sk, SOCK_DEAD))
1663                         *timeo = schedule_timeout(*timeo);
1664 
1665                 __set_current_state(TASK_RUNNING);
1666                 remove_wait_queue(&nlk->wait, &wait);
1667                 sock_put(sk);
1668 
1669                 if (signal_pending(current)) {
1670                         kfree_skb(skb);
1671                         return sock_intr_errno(*timeo);
1672                 }
1673                 return 1;
1674         }
1675         netlink_skb_set_owner_r(skb, sk);
1676         return 0;
1677 }
1678 
1679 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1680 {
1681         int len = skb->len;
1682 
1683         netlink_deliver_tap(skb);
1684 
1685 #ifdef CONFIG_NETLINK_MMAP
1686         if (netlink_skb_is_mmaped(skb))
1687                 netlink_queue_mmaped_skb(sk, skb);
1688         else if (netlink_rx_is_mmaped(sk))
1689                 netlink_ring_set_copied(sk, skb);
1690         else
1691 #endif /* CONFIG_NETLINK_MMAP */
1692                 skb_queue_tail(&sk->sk_receive_queue, skb);
1693         sk->sk_data_ready(sk);
1694         return len;
1695 }
1696 
1697 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1698 {
1699         int len = __netlink_sendskb(sk, skb);
1700 
1701         sock_put(sk);
1702         return len;
1703 }
1704 
1705 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
1706 {
1707         kfree_skb(skb);
1708         sock_put(sk);
1709 }
1710 
1711 static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
1712 {
1713         int delta;
1714 
1715         WARN_ON(skb->sk != NULL);
1716         if (netlink_skb_is_mmaped(skb))
1717                 return skb;
1718 
1719         delta = skb->end - skb->tail;
1720         if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
1721                 return skb;
1722 
1723         if (skb_shared(skb)) {
1724                 struct sk_buff *nskb = skb_clone(skb, allocation);
1725                 if (!nskb)
1726                         return skb;
1727                 consume_skb(skb);
1728                 skb = nskb;
1729         }
1730 
1731         if (!pskb_expand_head(skb, 0, -delta, allocation))
1732                 skb->truesize -= delta;
1733 
1734         return skb;
1735 }
1736 
1737 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
1738                                   struct sock *ssk)
1739 {
1740         int ret;
1741         struct netlink_sock *nlk = nlk_sk(sk);
1742 
1743         ret = -ECONNREFUSED;
1744         if (nlk->netlink_rcv != NULL) {
1745                 ret = skb->len;
1746                 netlink_skb_set_owner_r(skb, sk);
1747                 NETLINK_CB(skb).sk = ssk;
1748                 netlink_deliver_tap_kernel(sk, ssk, skb);
1749                 nlk->netlink_rcv(skb);
1750                 consume_skb(skb);
1751         } else {
1752                 kfree_skb(skb);
1753         }
1754         sock_put(sk);
1755         return ret;
1756 }
1757 
1758 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
1759                     u32 portid, int nonblock)
1760 {
1761         struct sock *sk;
1762         int err;
1763         long timeo;
1764 
1765         skb = netlink_trim(skb, gfp_any());
1766 
1767         timeo = sock_sndtimeo(ssk, nonblock);
1768 retry:
1769         sk = netlink_getsockbyportid(ssk, portid);
1770         if (IS_ERR(sk)) {
1771                 kfree_skb(skb);
1772                 return PTR_ERR(sk);
1773         }
1774         if (netlink_is_kernel(sk))
1775                 return netlink_unicast_kernel(sk, skb, ssk);
1776 
1777         if (sk_filter(sk, skb)) {
1778                 err = skb->len;
1779                 kfree_skb(skb);
1780                 sock_put(sk);
1781                 return err;
1782         }
1783 
1784         err = netlink_attachskb(sk, skb, &timeo, ssk);
1785         if (err == 1)
1786                 goto retry;
1787         if (err)
1788                 return err;
1789 
1790         return netlink_sendskb(sk, skb);
1791 }
1792 EXPORT_SYMBOL(netlink_unicast);
1793 
1794 struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size,
1795                                   u32 dst_portid, gfp_t gfp_mask)
1796 {
1797 #ifdef CONFIG_NETLINK_MMAP
1798         struct sock *sk = NULL;
1799         struct sk_buff *skb;
1800         struct netlink_ring *ring;
1801         struct nl_mmap_hdr *hdr;
1802         unsigned int maxlen;
1803 
1804         sk = netlink_getsockbyportid(ssk, dst_portid);
1805         if (IS_ERR(sk))
1806                 goto out;
1807 
1808         ring = &nlk_sk(sk)->rx_ring;
1809         /* fast-path without atomic ops for common case: non-mmaped receiver */
1810         if (ring->pg_vec == NULL)
1811                 goto out_put;
1812 
1813         if (ring->frame_size - NL_MMAP_HDRLEN < size)
1814                 goto out_put;
1815 
1816         skb = alloc_skb_head(gfp_mask);
1817         if (skb == NULL)
1818                 goto err1;
1819 
1820         spin_lock_bh(&sk->sk_receive_queue.lock);
1821         /* check again under lock */
1822         if (ring->pg_vec == NULL)
1823                 goto out_free;
1824 
1825         /* check again under lock */
1826         maxlen = ring->frame_size - NL_MMAP_HDRLEN;
1827         if (maxlen < size)
1828                 goto out_free;
1829 
1830         netlink_forward_ring(ring);
1831         hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
1832         if (hdr == NULL)
1833                 goto err2;
1834         netlink_ring_setup_skb(skb, sk, ring, hdr);
1835         netlink_set_status(hdr, NL_MMAP_STATUS_RESERVED);
1836         atomic_inc(&ring->pending);
1837         netlink_increment_head(ring);
1838 
1839         spin_unlock_bh(&sk->sk_receive_queue.lock);
1840         return skb;
1841 
1842 err2:
1843         kfree_skb(skb);
1844         spin_unlock_bh(&sk->sk_receive_queue.lock);
1845         netlink_overrun(sk);
1846 err1:
1847         sock_put(sk);
1848         return NULL;
1849 
1850 out_free:
1851         kfree_skb(skb);
1852         spin_unlock_bh(&sk->sk_receive_queue.lock);
1853 out_put:
1854         sock_put(sk);
1855 out:
1856 #endif
1857         return alloc_skb(size, gfp_mask);
1858 }
1859 EXPORT_SYMBOL_GPL(netlink_alloc_skb);
1860 
1861 int netlink_has_listeners(struct sock *sk, unsigned int group)
1862 {
1863         int res = 0;
1864         struct listeners *listeners;
1865 
1866         BUG_ON(!netlink_is_kernel(sk));
1867 
1868         rcu_read_lock();
1869         listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
1870 
1871         if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
1872                 res = test_bit(group - 1, listeners->masks);
1873 
1874         rcu_read_unlock();
1875 
1876         return res;
1877 }
1878 EXPORT_SYMBOL_GPL(netlink_has_listeners);
1879 
1880 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
1881 {
1882         struct netlink_sock *nlk = nlk_sk(sk);
1883 
1884         if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
1885             !test_bit(NETLINK_CONGESTED, &nlk->state)) {
1886                 netlink_skb_set_owner_r(skb, sk);
1887                 __netlink_sendskb(sk, skb);
1888                 return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
1889         }
1890         return -1;
1891 }
1892 
1893 struct netlink_broadcast_data {
1894         struct sock *exclude_sk;
1895         struct net *net;
1896         u32 portid;
1897         u32 group;
1898         int failure;
1899         int delivery_failure;
1900         int congested;
1901         int delivered;
1902         gfp_t allocation;
1903         struct sk_buff *skb, *skb2;
1904         int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
1905         void *tx_data;
1906 };
1907 
1908 static void do_one_broadcast(struct sock *sk,
1909                                     struct netlink_broadcast_data *p)
1910 {
1911         struct netlink_sock *nlk = nlk_sk(sk);
1912         int val;
1913 
1914         if (p->exclude_sk == sk)
1915                 return;
1916 
1917         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1918             !test_bit(p->group - 1, nlk->groups))
1919                 return;
1920 
1921         if (!net_eq(sock_net(sk), p->net))
1922                 return;
1923 
1924         if (p->failure) {
1925                 netlink_overrun(sk);
1926                 return;
1927         }
1928 
1929         sock_hold(sk);
1930         if (p->skb2 == NULL) {
1931                 if (skb_shared(p->skb)) {
1932                         p->skb2 = skb_clone(p->skb, p->allocation);
1933                 } else {
1934                         p->skb2 = skb_get(p->skb);
1935                         /*
1936                          * skb ownership may have been set when
1937                          * delivered to a previous socket.
1938                          */
1939                         skb_orphan(p->skb2);
1940                 }
1941         }
1942         if (p->skb2 == NULL) {
1943                 netlink_overrun(sk);
1944                 /* Clone failed. Notify ALL listeners. */
1945                 p->failure = 1;
1946                 if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
1947                         p->delivery_failure = 1;
1948         } else if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
1949                 kfree_skb(p->skb2);
1950                 p->skb2 = NULL;
1951         } else if (sk_filter(sk, p->skb2)) {
1952                 kfree_skb(p->skb2);
1953                 p->skb2 = NULL;
1954         } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {
1955                 netlink_overrun(sk);
1956                 if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
1957                         p->delivery_failure = 1;
1958         } else {
1959                 p->congested |= val;
1960                 p->delivered = 1;
1961                 p->skb2 = NULL;
1962         }
1963         sock_put(sk);
1964 }
1965 
1966 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 portid,
1967         u32 group, gfp_t allocation,
1968         int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
1969         void *filter_data)
1970 {
1971         struct net *net = sock_net(ssk);
1972         struct netlink_broadcast_data info;
1973         struct sock *sk;
1974 
1975         skb = netlink_trim(skb, allocation);
1976 
1977         info.exclude_sk = ssk;
1978         info.net = net;
1979         info.portid = portid;
1980         info.group = group;
1981         info.failure = 0;
1982         info.delivery_failure = 0;
1983         info.congested = 0;
1984         info.delivered = 0;
1985         info.allocation = allocation;
1986         info.skb = skb;
1987         info.skb2 = NULL;
1988         info.tx_filter = filter;
1989         info.tx_data = filter_data;
1990 
1991         /* While we sleep in clone, do not allow to change socket list */
1992 
1993         netlink_lock_table();
1994 
1995         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1996                 do_one_broadcast(sk, &info);
1997 
1998         consume_skb(skb);
1999 
2000         netlink_unlock_table();
2001 
2002         if (info.delivery_failure) {
2003                 kfree_skb(info.skb2);
2004                 return -ENOBUFS;
2005         }
2006         consume_skb(info.skb2);
2007 
2008         if (info.delivered) {
2009                 if (info.congested && (allocation & __GFP_WAIT))
2010                         yield();
2011                 return 0;
2012         }
2013         return -ESRCH;
2014 }
2015 EXPORT_SYMBOL(netlink_broadcast_filtered);
2016 
2017 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
2018                       u32 group, gfp_t allocation)
2019 {
2020         return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
2021                 NULL, NULL);
2022 }
2023 EXPORT_SYMBOL(netlink_broadcast);
2024 
2025 struct netlink_set_err_data {
2026         struct sock *exclude_sk;
2027         u32 portid;
2028         u32 group;
2029         int code;
2030 };
2031 
2032 static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
2033 {
2034         struct netlink_sock *nlk = nlk_sk(sk);
2035         int ret = 0;
2036 
2037         if (sk == p->exclude_sk)
2038                 goto out;
2039 
2040         if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
2041                 goto out;
2042 
2043         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
2044             !test_bit(p->group - 1, nlk->groups))
2045                 goto out;
2046 
2047         if (p->code == ENOBUFS && nlk->flags & NETLINK_RECV_NO_ENOBUFS) {
2048                 ret = 1;
2049                 goto out;
2050         }
2051 
2052         sk->sk_err = p->code;
2053         sk->sk_error_report(sk);
2054 out:
2055         return ret;
2056 }
2057 
2058 /**
2059  * netlink_set_err - report error to broadcast listeners
2060  * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
2061  * @portid: the PORTID of a process that we want to skip (if any)
2062  * @group: the broadcast group that will notice the error
2063  * @code: error code, must be negative (as usual in kernelspace)
2064  *
2065  * This function returns the number of broadcast listeners that have set the
2066  * NETLINK_RECV_NO_ENOBUFS socket option.
2067  */
2068 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
2069 {
2070         struct netlink_set_err_data info;
2071         struct sock *sk;
2072         int ret = 0;
2073 
2074         info.exclude_sk = ssk;
2075         info.portid = portid;
2076         info.group = group;
2077         /* sk->sk_err wants a positive error value */
2078         info.code = -code;
2079 
2080         read_lock(&nl_table_lock);
2081 
2082         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
2083                 ret += do_one_set_err(sk, &info);
2084 
2085         read_unlock(&nl_table_lock);
2086         return ret;
2087 }
2088 EXPORT_SYMBOL(netlink_set_err);
2089 
2090 /* must be called with netlink table grabbed */
2091 static void netlink_update_socket_mc(struct netlink_sock *nlk,
2092                                      unsigned int group,
2093                                      int is_new)
2094 {
2095         int old, new = !!is_new, subscriptions;
2096 
2097         old = test_bit(group - 1, nlk->groups);
2098         subscriptions = nlk->subscriptions - old + new;
2099         if (new)
2100                 __set_bit(group - 1, nlk->groups);
2101         else
2102                 __clear_bit(group - 1, nlk->groups);
2103         netlink_update_subscriptions(&nlk->sk, subscriptions);
2104         netlink_update_listeners(&nlk->sk);
2105 }
2106 
2107 static int netlink_setsockopt(struct socket *sock, int level, int optname,
2108                               char __user *optval, unsigned int optlen)
2109 {
2110         struct sock *sk = sock->sk;
2111         struct netlink_sock *nlk = nlk_sk(sk);
2112         unsigned int val = 0;
2113         int err;
2114 
2115         if (level != SOL_NETLINK)
2116                 return -ENOPROTOOPT;
2117 
2118         if (optname != NETLINK_RX_RING && optname != NETLINK_TX_RING &&
2119             optlen >= sizeof(int) &&
2120             get_user(val, (unsigned int __user *)optval))
2121                 return -EFAULT;
2122 
2123         switch (optname) {
2124         case NETLINK_PKTINFO:
2125                 if (val)
2126                         nlk->flags |= NETLINK_RECV_PKTINFO;
2127                 else
2128                         nlk->flags &= ~NETLINK_RECV_PKTINFO;
2129                 err = 0;
2130                 break;
2131         case NETLINK_ADD_MEMBERSHIP:
2132         case NETLINK_DROP_MEMBERSHIP: {
2133                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
2134                         return -EPERM;
2135                 err = netlink_realloc_groups(sk);
2136                 if (err)
2137                         return err;
2138                 if (!val || val - 1 >= nlk->ngroups)
2139                         return -EINVAL;
2140                 if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
2141                         err = nlk->netlink_bind(sock_net(sk), val);
2142                         if (err)
2143                                 return err;
2144                 }
2145                 netlink_table_grab();
2146                 netlink_update_socket_mc(nlk, val,
2147                                          optname == NETLINK_ADD_MEMBERSHIP);
2148                 netlink_table_ungrab();
2149                 if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
2150                         nlk->netlink_unbind(sock_net(sk), val);
2151 
2152                 err = 0;
2153                 break;
2154         }
2155         case NETLINK_BROADCAST_ERROR:
2156                 if (val)
2157                         nlk->flags |= NETLINK_BROADCAST_SEND_ERROR;
2158                 else
2159                         nlk->flags &= ~NETLINK_BROADCAST_SEND_ERROR;
2160                 err = 0;
2161                 break;
2162         case NETLINK_NO_ENOBUFS:
2163                 if (val) {
2164                         nlk->flags |= NETLINK_RECV_NO_ENOBUFS;
2165                         clear_bit(NETLINK_CONGESTED, &nlk->state);
2166                         wake_up_interruptible(&nlk->wait);
2167                 } else {
2168                         nlk->flags &= ~NETLINK_RECV_NO_ENOBUFS;
2169                 }
2170                 err = 0;
2171                 break;
2172 #ifdef CONFIG_NETLINK_MMAP
2173         case NETLINK_RX_RING:
2174         case NETLINK_TX_RING: {
2175                 struct nl_mmap_req req;
2176 
2177                 /* Rings might consume more memory than queue limits, require
2178                  * CAP_NET_ADMIN.
2179                  */
2180                 if (!capable(CAP_NET_ADMIN))
2181                         return -EPERM;
2182                 if (optlen < sizeof(req))
2183                         return -EINVAL;
2184                 if (copy_from_user(&req, optval, sizeof(req)))
2185                         return -EFAULT;
2186                 err = netlink_set_ring(sk, &req, false,
2187                                        optname == NETLINK_TX_RING);
2188                 break;
2189         }
2190 #endif /* CONFIG_NETLINK_MMAP */
2191         default:
2192                 err = -ENOPROTOOPT;
2193         }
2194         return err;
2195 }
2196 
2197 static int netlink_getsockopt(struct socket *sock, int level, int optname,
2198                               char __user *optval, int __user *optlen)
2199 {
2200         struct sock *sk = sock->sk;
2201         struct netlink_sock *nlk = nlk_sk(sk);
2202         int len, val, err;
2203 
2204         if (level != SOL_NETLINK)
2205                 return -ENOPROTOOPT;
2206 
2207         if (get_user(len, optlen))
2208                 return -EFAULT;
2209         if (len < 0)
2210                 return -EINVAL;
2211 
2212         switch (optname) {
2213         case NETLINK_PKTINFO:
2214                 if (len < sizeof(int))
2215                         return -EINVAL;
2216                 len = sizeof(int);
2217                 val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0;
2218                 if (put_user(len, optlen) ||
2219                     put_user(val, optval))
2220                         return -EFAULT;
2221                 err = 0;
2222                 break;
2223         case NETLINK_BROADCAST_ERROR:
2224                 if (len < sizeof(int))
2225                         return -EINVAL;
2226                 len = sizeof(int);
2227                 val = nlk->flags & NETLINK_BROADCAST_SEND_ERROR ? 1 : 0;
2228                 if (put_user(len, optlen) ||
2229                     put_user(val, optval))
2230                         return -EFAULT;
2231                 err = 0;
2232                 break;
2233         case NETLINK_NO_ENOBUFS:
2234                 if (len < sizeof(int))
2235                         return -EINVAL;
2236                 len = sizeof(int);
2237                 val = nlk->flags & NETLINK_RECV_NO_ENOBUFS ? 1 : 0;
2238                 if (put_user(len, optlen) ||
2239                     put_user(val, optval))
2240                         return -EFAULT;
2241                 err = 0;
2242                 break;
2243         default:
2244                 err = -ENOPROTOOPT;
2245         }
2246         return err;
2247 }
2248 
2249 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
2250 {
2251         struct nl_pktinfo info;
2252 
2253         info.group = NETLINK_CB(skb).dst_group;
2254         put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
2255 }
2256 
2257 static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
2258                            struct msghdr *msg, size_t len)
2259 {
2260         struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
2261         struct sock *sk = sock->sk;
2262         struct netlink_sock *nlk = nlk_sk(sk);
2263         DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
2264         u32 dst_portid;
2265         u32 dst_group;
2266         struct sk_buff *skb;
2267         int err;
2268         struct scm_cookie scm;
2269         u32 netlink_skb_flags = 0;
2270 
2271         if (msg->msg_flags&MSG_OOB)
2272                 return -EOPNOTSUPP;
2273 
2274         if (NULL == siocb->scm)
2275                 siocb->scm = &scm;
2276 
2277         err = scm_send(sock, msg, siocb->scm, true);
2278         if (err < 0)
2279                 return err;
2280 
2281         if (msg->msg_namelen) {
2282                 err = -EINVAL;
2283                 if (addr->nl_family != AF_NETLINK)
2284                         goto out;
2285                 dst_portid = addr->nl_pid;
2286                 dst_group = ffs(addr->nl_groups);
2287                 err =  -EPERM;
2288                 if ((dst_group || dst_portid) &&
2289                     !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
2290                         goto out;
2291                 netlink_skb_flags |= NETLINK_SKB_DST;
2292         } else {
2293                 dst_portid = nlk->dst_portid;
2294                 dst_group = nlk->dst_group;
2295         }
2296 
2297         if (!nlk->portid) {
2298                 err = netlink_autobind(sock);
2299                 if (err)
2300                         goto out;
2301         }
2302 
2303         if (netlink_tx_is_mmaped(sk) &&
2304             msg->msg_iter.iov->iov_base == NULL) {
2305                 err = netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group,
2306                                            siocb);
2307                 goto out;
2308         }
2309 
2310         err = -EMSGSIZE;
2311         if (len > sk->sk_sndbuf - 32)
2312                 goto out;
2313         err = -ENOBUFS;
2314         skb = netlink_alloc_large_skb(len, dst_group);
2315         if (skb == NULL)
2316                 goto out;
2317 
2318         NETLINK_CB(skb).portid  = nlk->portid;
2319         NETLINK_CB(skb).dst_group = dst_group;
2320         NETLINK_CB(skb).creds   = siocb->scm->creds;
2321         NETLINK_CB(skb).flags   = netlink_skb_flags;
2322 
2323         err = -EFAULT;
2324         if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
2325                 kfree_skb(skb);
2326                 goto out;
2327         }
2328 
2329         err = security_netlink_send(sk, skb);
2330         if (err) {
2331                 kfree_skb(skb);
2332                 goto out;
2333         }
2334 
2335         if (dst_group) {
2336                 atomic_inc(&skb->users);
2337                 netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
2338         }
2339         err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT);
2340 
2341 out:
2342         scm_destroy(siocb->scm);
2343         return err;
2344 }
2345 
2346 static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
2347                            struct msghdr *msg, size_t len,
2348                            int flags)
2349 {
2350         struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
2351         struct scm_cookie scm;
2352         struct sock *sk = sock->sk;
2353         struct netlink_sock *nlk = nlk_sk(sk);
2354         int noblock = flags&MSG_DONTWAIT;
2355         size_t copied;
2356         struct sk_buff *skb, *data_skb;
2357         int err, ret;
2358 
2359         if (flags&MSG_OOB)
2360                 return -EOPNOTSUPP;
2361 
2362         copied = 0;
2363 
2364         skb = skb_recv_datagram(sk, flags, noblock, &err);
2365         if (skb == NULL)
2366                 goto out;
2367 
2368         data_skb = skb;
2369 
2370 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES
2371         if (unlikely(skb_shinfo(skb)->frag_list)) {
2372                 /*
2373                  * If this skb has a frag_list, then here that means that we
2374                  * will have to use the frag_list skb's data for compat tasks
2375                  * and the regular skb's data for normal (non-compat) tasks.
2376                  *
2377                  * If we need to send the compat skb, assign it to the
2378                  * 'data_skb' variable so that it will be used below for data
2379                  * copying. We keep 'skb' for everything else, including
2380                  * freeing both later.
2381                  */
2382                 if (flags & MSG_CMSG_COMPAT)
2383                         data_skb = skb_shinfo(skb)->frag_list;
2384         }
2385 #endif
2386 
2387         /* Record the max length of recvmsg() calls for future allocations */
2388         nlk->max_recvmsg_len = max(nlk->max_recvmsg_len, len);
2389         nlk->max_recvmsg_len = min_t(size_t, nlk->max_recvmsg_len,
2390                                      16384);
2391 
2392         copied = data_skb->len;
2393         if (len < copied) {
2394                 msg->msg_flags |= MSG_TRUNC;
2395                 copied = len;
2396         }
2397 
2398         skb_reset_transport_header(data_skb);
2399         err = skb_copy_datagram_msg(data_skb, 0, msg, copied);
2400 
2401         if (msg->msg_name) {
2402                 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
2403                 addr->nl_family = AF_NETLINK;
2404                 addr->nl_pad    = 0;
2405                 addr->nl_pid    = NETLINK_CB(skb).portid;
2406                 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
2407                 msg->msg_namelen = sizeof(*addr);
2408         }
2409 
2410         if (nlk->flags & NETLINK_RECV_PKTINFO)
2411                 netlink_cmsg_recv_pktinfo(msg, skb);
2412 
2413         if (NULL == siocb->scm) {
2414                 memset(&scm, 0, sizeof(scm));
2415                 siocb->scm = &scm;
2416         }
2417         siocb->scm->creds = *NETLINK_CREDS(skb);
2418         if (flags & MSG_TRUNC)
2419                 copied = data_skb->len;
2420 
2421         skb_free_datagram(sk, skb);
2422 
2423         if (nlk->cb_running &&
2424             atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
2425                 ret = netlink_dump(sk);
2426                 if (ret) {
2427                         sk->sk_err = -ret;
2428                         sk->sk_error_report(sk);
2429                 }
2430         }
2431 
2432         scm_recv(sock, msg, siocb->scm, flags);
2433 out:
2434         netlink_rcv_wake(sk);
2435         return err ? : copied;
2436 }
2437 
2438 static void netlink_data_ready(struct sock *sk)
2439 {
2440         BUG();
2441 }
2442 
2443 /*
2444  *      We export these functions to other modules. They provide a
2445  *      complete set of kernel non-blocking support for message
2446  *      queueing.
2447  */
2448 
2449 struct sock *
2450 __netlink_kernel_create(struct net *net, int unit, struct module *module,
2451                         struct netlink_kernel_cfg *cfg)
2452 {
2453         struct socket *sock;
2454         struct sock *sk;
2455         struct netlink_sock *nlk;
2456         struct listeners *listeners = NULL;
2457         struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL;
2458         unsigned int groups;
2459 
2460         BUG_ON(!nl_table);
2461 
2462         if (unit < 0 || unit >= MAX_LINKS)
2463                 return NULL;
2464 
2465         if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
2466                 return NULL;
2467 
2468         /*
2469          * We have to just have a reference on the net from sk, but don't
2470          * get_net it. Besides, we cannot get and then put the net here.
2471          * So we create one inside init_net and the move it to net.
2472          */
2473 
2474         if (__netlink_create(&init_net, sock, cb_mutex, unit) < 0)
2475                 goto out_sock_release_nosk;
2476 
2477         sk = sock->sk;
2478         sk_change_net(sk, net);
2479 
2480         if (!cfg || cfg->groups < 32)
2481                 groups = 32;
2482         else
2483                 groups = cfg->groups;
2484 
2485         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2486         if (!listeners)
2487                 goto out_sock_release;
2488 
2489         sk->sk_data_ready = netlink_data_ready;
2490         if (cfg && cfg->input)
2491                 nlk_sk(sk)->netlink_rcv = cfg->input;
2492 
2493         if (netlink_insert(sk, net, 0))
2494                 goto out_sock_release;
2495 
2496         nlk = nlk_sk(sk);
2497         nlk->flags |= NETLINK_KERNEL_SOCKET;
2498 
2499         netlink_table_grab();
2500         if (!nl_table[unit].registered) {
2501                 nl_table[unit].groups = groups;
2502                 rcu_assign_pointer(nl_table[unit].listeners, listeners);
2503                 nl_table[unit].cb_mutex = cb_mutex;
2504                 nl_table[unit].module = module;
2505                 if (cfg) {
2506                         nl_table[unit].bind = cfg->bind;
2507                         nl_table[unit].unbind = cfg->unbind;
2508                         nl_table[unit].flags = cfg->flags;
2509                         if (cfg->compare)
2510                                 nl_table[unit].compare = cfg->compare;
2511                 }
2512                 nl_table[unit].registered = 1;
2513         } else {
2514                 kfree(listeners);
2515                 nl_table[unit].registered++;
2516         }
2517         netlink_table_ungrab();
2518         return sk;
2519 
2520 out_sock_release:
2521         kfree(listeners);
2522         netlink_kernel_release(sk);
2523         return NULL;
2524 
2525 out_sock_release_nosk:
2526         sock_release(sock);
2527         return NULL;
2528 }
2529 EXPORT_SYMBOL(__netlink_kernel_create);
2530 
2531 void
2532 netlink_kernel_release(struct sock *sk)
2533 {
2534         sk_release_kernel(sk);
2535 }
2536 EXPORT_SYMBOL(netlink_kernel_release);
2537 
2538 int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
2539 {
2540         struct listeners *new, *old;
2541         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
2542 
2543         if (groups < 32)
2544                 groups = 32;
2545 
2546         if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
2547                 new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
2548                 if (!new)
2549                         return -ENOMEM;
2550                 old = nl_deref_protected(tbl->listeners);
2551                 memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
2552                 rcu_assign_pointer(tbl->listeners, new);
2553 
2554                 kfree_rcu(old, rcu);
2555         }
2556         tbl->groups = groups;
2557 
2558         return 0;
2559 }
2560 
2561 /**
2562  * netlink_change_ngroups - change number of multicast groups
2563  *
2564  * This changes the number of multicast groups that are available
2565  * on a certain netlink family. Note that it is not possible to
2566  * change the number of groups to below 32. Also note that it does
2567  * not implicitly call netlink_clear_multicast_users() when the
2568  * number of groups is reduced.
2569  *
2570  * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
2571  * @groups: The new number of groups.
2572  */
2573 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
2574 {
2575         int err;
2576 
2577         netlink_table_grab();
2578         err = __netlink_change_ngroups(sk, groups);
2579         netlink_table_ungrab();
2580 
2581         return err;
2582 }
2583 
2584 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
2585 {
2586         struct sock *sk;
2587         struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
2588 
2589         sk_for_each_bound(sk, &tbl->mc_list)
2590                 netlink_update_socket_mc(nlk_sk(sk), group, 0);
2591 }
2592 
2593 struct nlmsghdr *
2594 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
2595 {
2596         struct nlmsghdr *nlh;
2597         int size = nlmsg_msg_size(len);
2598 
2599         nlh = (struct nlmsghdr *)skb_put(skb, NLMSG_ALIGN(size));
2600         nlh->nlmsg_type = type;
2601         nlh->nlmsg_len = size;
2602         nlh->nlmsg_flags = flags;
2603         nlh->nlmsg_pid = portid;
2604         nlh->nlmsg_seq = seq;
2605         if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
2606                 memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
2607         return nlh;
2608 }
2609 EXPORT_SYMBOL(__nlmsg_put);
2610 
2611 /*
2612  * It looks a bit ugly.
2613  * It would be better to create kernel thread.
2614  */
2615 
2616 static int netlink_dump(struct sock *sk)
2617 {
2618         struct netlink_sock *nlk = nlk_sk(sk);
2619         struct netlink_callback *cb;
2620         struct sk_buff *skb = NULL;
2621         struct nlmsghdr *nlh;
2622         int len, err = -ENOBUFS;
2623         int alloc_size;
2624 
2625         mutex_lock(nlk->cb_mutex);
2626         if (!nlk->cb_running) {
2627                 err = -EINVAL;
2628                 goto errout_skb;
2629         }
2630 
2631         cb = &nlk->cb;
2632         alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
2633 
2634         if (!netlink_rx_is_mmaped(sk) &&
2635             atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
2636                 goto errout_skb;
2637 
2638         /* NLMSG_GOODSIZE is small to avoid high order allocations being
2639          * required, but it makes sense to _attempt_ a 16K bytes allocation
2640          * to reduce number of system calls on dump operations, if user
2641          * ever provided a big enough buffer.
2642          */
2643         if (alloc_size < nlk->max_recvmsg_len) {
2644                 skb = netlink_alloc_skb(sk,
2645                                         nlk->max_recvmsg_len,
2646                                         nlk->portid,
2647                                         GFP_KERNEL |
2648                                         __GFP_NOWARN |
2649                                         __GFP_NORETRY);
2650                 /* available room should be exact amount to avoid MSG_TRUNC */
2651                 if (skb)
2652                         skb_reserve(skb, skb_tailroom(skb) -
2653                                          nlk->max_recvmsg_len);
2654         }
2655         if (!skb)
2656                 skb = netlink_alloc_skb(sk, alloc_size, nlk->portid,
2657                                         GFP_KERNEL);
2658         if (!skb)
2659                 goto errout_skb;
2660         netlink_skb_set_owner_r(skb, sk);
2661 
2662         len = cb->dump(skb, cb);
2663 
2664         if (len > 0) {
2665                 mutex_unlock(nlk->cb_mutex);
2666 
2667                 if (sk_filter(sk, skb))
2668                         kfree_skb(skb);
2669                 else
2670                         __netlink_sendskb(sk, skb);
2671                 return 0;
2672         }
2673 
2674         nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
2675         if (!nlh)
2676                 goto errout_skb;
2677 
2678         nl_dump_check_consistent(cb, nlh);
2679 
2680         memcpy(nlmsg_data(nlh), &len, sizeof(len));
2681 
2682         if (sk_filter(sk, skb))
2683                 kfree_skb(skb);
2684         else
2685                 __netlink_sendskb(sk, skb);
2686 
2687         if (cb->done)
2688                 cb->done(cb);
2689 
2690         nlk->cb_running = false;
2691         mutex_unlock(nlk->cb_mutex);
2692         module_put(cb->module);
2693         consume_skb(cb->skb);
2694         return 0;
2695 
2696 errout_skb:
2697         mutex_unlock(nlk->cb_mutex);
2698         kfree_skb(skb);
2699         return err;
2700 }
2701 
2702 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
2703                          const struct nlmsghdr *nlh,
2704                          struct netlink_dump_control *control)
2705 {
2706         struct netlink_callback *cb;
2707         struct sock *sk;
2708         struct netlink_sock *nlk;
2709         int ret;
2710 
2711         /* Memory mapped dump requests need to be copied to avoid looping
2712          * on the pending state in netlink_mmap_sendmsg() while the CB hold
2713          * a reference to the skb.
2714          */
2715         if (netlink_skb_is_mmaped(skb)) {
2716                 skb = skb_copy(skb, GFP_KERNEL);
2717                 if (skb == NULL)
2718                         return -ENOBUFS;
2719         } else
2720                 atomic_inc(&skb->users);
2721 
2722         sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
2723         if (sk == NULL) {
2724                 ret = -ECONNREFUSED;
2725                 goto error_free;
2726         }
2727 
2728         nlk = nlk_sk(sk);
2729         mutex_lock(nlk->cb_mutex);
2730         /* A dump is in progress... */
2731         if (nlk->cb_running) {
2732                 ret = -EBUSY;
2733                 goto error_unlock;
2734         }
2735         /* add reference of module which cb->dump belongs to */
2736         if (!try_module_get(control->module)) {
2737                 ret = -EPROTONOSUPPORT;
2738                 goto error_unlock;
2739         }
2740 
2741         cb = &nlk->cb;
2742         memset(cb, 0, sizeof(*cb));
2743         cb->dump = control->dump;
2744         cb->done = control->done;
2745         cb->nlh = nlh;
2746         cb->data = control->data;
2747         cb->module = control->module;
2748         cb->min_dump_alloc = control->min_dump_alloc;
2749         cb->skb = skb;
2750 
2751         nlk->cb_running = true;
2752 
2753         mutex_unlock(nlk->cb_mutex);
2754 
2755         ret = netlink_dump(sk);
2756         sock_put(sk);
2757 
2758         if (ret)
2759                 return ret;
2760 
2761         /* We successfully started a dump, by returning -EINTR we
2762          * signal not to send ACK even if it was requested.
2763          */
2764         return -EINTR;
2765 
2766 error_unlock:
2767         sock_put(sk);
2768         mutex_unlock(nlk->cb_mutex);
2769 error_free:
2770         kfree_skb(skb);
2771         return ret;
2772 }
2773 EXPORT_SYMBOL(__netlink_dump_start);
2774 
2775 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
2776 {
2777         struct sk_buff *skb;
2778         struct nlmsghdr *rep;
2779         struct nlmsgerr *errmsg;
2780         size_t payload = sizeof(*errmsg);
2781 
2782         /* error messages get the original request appened */
2783         if (err)
2784                 payload += nlmsg_len(nlh);
2785 
2786         skb = netlink_alloc_skb(in_skb->sk, nlmsg_total_size(payload),
2787                                 NETLINK_CB(in_skb).portid, GFP_KERNEL);
2788         if (!skb) {
2789                 struct sock *sk;
2790 
2791                 sk = netlink_lookup(sock_net(in_skb->sk),
2792                                     in_skb->sk->sk_protocol,
2793                                     NETLINK_CB(in_skb).portid);
2794                 if (sk) {
2795                         sk->sk_err = ENOBUFS;
2796                         sk->sk_error_report(sk);
2797                         sock_put(sk);
2798                 }
2799                 return;
2800         }
2801 
2802         rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2803                           NLMSG_ERROR, payload, 0);
2804         errmsg = nlmsg_data(rep);
2805         errmsg->error = err;
2806         memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh));
2807         netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);
2808 }
2809 EXPORT_SYMBOL(netlink_ack);
2810 
2811 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
2812                                                      struct nlmsghdr *))
2813 {
2814         struct nlmsghdr *nlh;
2815         int err;
2816 
2817         while (skb->len >= nlmsg_total_size(0)) {
2818                 int msglen;
2819 
2820                 nlh = nlmsg_hdr(skb);
2821                 err = 0;
2822 
2823                 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
2824                         return 0;
2825 
2826                 /* Only requests are handled by the kernel */
2827                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
2828                         goto ack;
2829 
2830                 /* Skip control messages */
2831                 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
2832                         goto ack;
2833 
2834                 err = cb(skb, nlh);
2835                 if (err == -EINTR)
2836                         goto skip;
2837 
2838 ack:
2839                 if (nlh->nlmsg_flags & NLM_F_ACK || err)
2840                         netlink_ack(skb, nlh, err);
2841 
2842 skip:
2843                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
2844                 if (msglen > skb->len)
2845                         msglen = skb->len;
2846                 skb_pull(skb, msglen);
2847         }
2848 
2849         return 0;
2850 }
2851 EXPORT_SYMBOL(netlink_rcv_skb);
2852 
2853 /**
2854  * nlmsg_notify - send a notification netlink message
2855  * @sk: netlink socket to use
2856  * @skb: notification message
2857  * @portid: destination netlink portid for reports or 0
2858  * @group: destination multicast group or 0
2859  * @report: 1 to report back, 0 to disable
2860  * @flags: allocation flags
2861  */
2862 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
2863                  unsigned int group, int report, gfp_t flags)
2864 {
2865         int err = 0;
2866 
2867         if (group) {
2868                 int exclude_portid = 0;
2869 
2870                 if (report) {
2871                         atomic_inc(&skb->users);
2872                         exclude_portid = portid;
2873                 }
2874 
2875                 /* errors reported via destination sk->sk_err, but propagate
2876                  * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
2877                 err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
2878         }
2879 
2880         if (report) {
2881                 int err2;
2882 
2883                 err2 = nlmsg_unicast(sk, skb, portid);
2884                 if (!err || err == -ESRCH)
2885                         err = err2;
2886         }
2887 
2888         return err;
2889 }
2890 EXPORT_SYMBOL(nlmsg_notify);
2891 
2892 #ifdef CONFIG_PROC_FS
2893 struct nl_seq_iter {
2894         struct seq_net_private p;
2895         int link;
2896         int hash_idx;
2897 };
2898 
2899 static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos)
2900 {
2901         struct nl_seq_iter *iter = seq->private;
2902         int i, j;
2903         struct netlink_sock *nlk;
2904         struct sock *s;
2905         loff_t off = 0;
2906 
2907         for (i = 0; i < MAX_LINKS; i++) {
2908                 struct rhashtable *ht = &nl_table[i].hash;
2909                 const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
2910 
2911                 for (j = 0; j < tbl->size; j++) {
2912                         rht_for_each_entry_rcu(nlk, tbl->buckets[j], node) {
2913                                 s = (struct sock *)nlk;
2914 
2915                                 if (sock_net(s) != seq_file_net(seq))
2916                                         continue;
2917                                 if (off == pos) {
2918                                         iter->link = i;
2919                                         iter->hash_idx = j;
2920                                         return s;
2921                                 }
2922                                 ++off;
2923                         }
2924                 }
2925         }
2926         return NULL;
2927 }
2928 
2929 static void *netlink_seq_start(struct seq_file *seq, loff_t *pos)
2930         __acquires(nl_table_lock) __acquires(RCU)
2931 {
2932         read_lock(&nl_table_lock);
2933         rcu_read_lock();
2934         return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2935 }
2936 
2937 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2938 {
2939         struct rhashtable *ht;
2940         struct netlink_sock *nlk;
2941         struct nl_seq_iter *iter;
2942         struct net *net;
2943         int i, j;
2944 
2945         ++*pos;
2946 
2947         if (v == SEQ_START_TOKEN)
2948                 return netlink_seq_socket_idx(seq, 0);
2949 
2950         net = seq_file_net(seq);
2951         iter = seq->private;
2952         nlk = v;
2953 
2954         i = iter->link;
2955         ht = &nl_table[i].hash;
2956         rht_for_each_entry(nlk, nlk->node.next, ht, node)
2957                 if (net_eq(sock_net((struct sock *)nlk), net))
2958                         return nlk;
2959 
2960         j = iter->hash_idx + 1;
2961 
2962         do {
2963                 const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
2964 
2965                 for (; j < tbl->size; j++) {
2966                         rht_for_each_entry(nlk, tbl->buckets[j], ht, node) {
2967                                 if (net_eq(sock_net((struct sock *)nlk), net)) {
2968                                         iter->link = i;
2969                                         iter->hash_idx = j;
2970                                         return nlk;
2971                                 }
2972                         }
2973                 }
2974 
2975                 j = 0;
2976         } while (++i < MAX_LINKS);
2977 
2978         return NULL;
2979 }
2980 
2981 static void netlink_seq_stop(struct seq_file *seq, void *v)
2982         __releases(RCU) __releases(nl_table_lock)
2983 {
2984         rcu_read_unlock();
2985         read_unlock(&nl_table_lock);
2986 }
2987 
2988 
2989 static int netlink_seq_show(struct seq_file *seq, void *v)
2990 {
2991         if (v == SEQ_START_TOKEN) {
2992                 seq_puts(seq,
2993                          "sk       Eth Pid    Groups   "
2994                          "Rmem     Wmem     Dump     Locks     Drops     Inode\n");
2995         } else {
2996                 struct sock *s = v;
2997                 struct netlink_sock *nlk = nlk_sk(s);
2998 
2999                 seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %d %-8d %-8d %-8lu\n",
3000                            s,
3001                            s->sk_protocol,
3002                            nlk->portid,
3003                            nlk->groups ? (u32)nlk->groups[0] : 0,
3004                            sk_rmem_alloc_get(s),
3005                            sk_wmem_alloc_get(s),
3006                            nlk->cb_running,
3007                            atomic_read(&s->sk_refcnt),
3008                            atomic_read(&s->sk_drops),
3009                            sock_i_ino(s)
3010                         );
3011 
3012         }
3013         return 0;
3014 }
3015 
3016 static const struct seq_operations netlink_seq_ops = {
3017         .start  = netlink_seq_start,
3018         .next   = netlink_seq_next,
3019         .stop   = netlink_seq_stop,
3020         .show   = netlink_seq_show,
3021 };
3022 
3023 
3024 static int netlink_seq_open(struct inode *inode, struct file *file)
3025 {
3026         return seq_open_net(inode, file, &netlink_seq_ops,
3027                                 sizeof(struct nl_seq_iter));
3028 }
3029 
3030 static const struct file_operations netlink_seq_fops = {
3031         .owner          = THIS_MODULE,
3032         .open           = netlink_seq_open,
3033         .read           = seq_read,
3034         .llseek         = seq_lseek,
3035         .release        = seq_release_net,
3036 };
3037 
3038 #endif
3039 
3040 int netlink_register_notifier(struct notifier_block *nb)
3041 {
3042         return atomic_notifier_chain_register(&netlink_chain, nb);
3043 }
3044 EXPORT_SYMBOL(netlink_register_notifier);
3045 
3046 int netlink_unregister_notifier(struct notifier_block *nb)
3047 {
3048         return atomic_notifier_chain_unregister(&netlink_chain, nb);
3049 }
3050 EXPORT_SYMBOL(netlink_unregister_notifier);
3051 
3052 static const struct proto_ops netlink_ops = {
3053         .family =       PF_NETLINK,
3054         .owner =        THIS_MODULE,
3055         .release =      netlink_release,
3056         .bind =         netlink_bind,
3057         .connect =      netlink_connect,
3058         .socketpair =   sock_no_socketpair,
3059         .accept =       sock_no_accept,
3060         .getname =      netlink_getname,
3061         .poll =         netlink_poll,
3062         .ioctl =        sock_no_ioctl,
3063         .listen =       sock_no_listen,
3064         .shutdown =     sock_no_shutdown,
3065         .setsockopt =   netlink_setsockopt,
3066         .getsockopt =   netlink_getsockopt,
3067         .sendmsg =      netlink_sendmsg,
3068         .recvmsg =      netlink_recvmsg,
3069         .mmap =         netlink_mmap,
3070         .sendpage =     sock_no_sendpage,
3071 };
3072 
3073 static const struct net_proto_family netlink_family_ops = {
3074         .family = PF_NETLINK,
3075         .create = netlink_create,
3076         .owner  = THIS_MODULE,  /* for consistency 8) */
3077 };
3078 
3079 static int __net_init netlink_net_init(struct net *net)
3080 {
3081 #ifdef CONFIG_PROC_FS
3082         if (!proc_create("netlink", 0, net->proc_net, &netlink_seq_fops))
3083                 return -ENOMEM;
3084 #endif
3085         return 0;
3086 }
3087 
3088 static void __net_exit netlink_net_exit(struct net *net)
3089 {
3090 #ifdef CONFIG_PROC_FS
3091         remove_proc_entry("netlink", net->proc_net);
3092 #endif
3093 }
3094 
3095 static void __init netlink_add_usersock_entry(void)
3096 {
3097         struct listeners *listeners;
3098         int groups = 32;
3099 
3100         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
3101         if (!listeners)
3102                 panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
3103 
3104         netlink_table_grab();
3105 
3106         nl_table[NETLINK_USERSOCK].groups = groups;
3107         rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
3108         nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
3109         nl_table[NETLINK_USERSOCK].registered = 1;
3110         nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND;
3111 
3112         netlink_table_ungrab();
3113 }
3114 
3115 static struct pernet_operations __net_initdata netlink_net_ops = {
3116         .init = netlink_net_init,
3117         .exit = netlink_net_exit,
3118 };
3119 
3120 static int __init netlink_proto_init(void)
3121 {
3122         int i;
3123         int err = proto_register(&netlink_proto, 0);
3124         struct rhashtable_params ht_params = {
3125                 .head_offset = offsetof(struct netlink_sock, node),
3126                 .key_offset = offsetof(struct netlink_sock, portid),
3127                 .key_len = sizeof(u32), /* portid */
3128                 .hashfn = jhash,
3129                 .max_shift = 16, /* 64K */
3130                 .grow_decision = rht_grow_above_75,
3131                 .shrink_decision = rht_shrink_below_30,
3132 #ifdef CONFIG_PROVE_LOCKING
3133                 .mutex_is_held = lockdep_nl_sk_hash_is_held,
3134 #endif
3135         };
3136 
3137         if (err != 0)
3138                 goto out;
3139 
3140         BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
3141 
3142         nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
3143         if (!nl_table)
3144                 goto panic;
3145 
3146         for (i = 0; i < MAX_LINKS; i++) {
3147                 if (rhashtable_init(&nl_table[i].hash, &ht_params) < 0) {
3148                         while (--i > 0)
3149                                 rhashtable_destroy(&nl_table[i].hash);
3150                         kfree(nl_table);
3151                         goto panic;
3152                 }
3153         }
3154 
3155         INIT_LIST_HEAD(&netlink_tap_all);
3156 
3157         netlink_add_usersock_entry();
3158 
3159         sock_register(&netlink_family_ops);
3160         register_pernet_subsys(&netlink_net_ops);
3161         /* The netlink device handler may be needed early. */
3162         rtnetlink_init();
3163 out:
3164         return err;
3165 panic:
3166         panic("netlink_init: Cannot allocate nl_table\n");
3167 }
3168 
3169 core_initcall(netlink_proto_init);
3170 

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