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TOMOYO Linux Cross Reference
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 <asm/cacheflush.h>
 61 
 62 #include <net/net_namespace.h>
 63 #include <net/sock.h>
 64 #include <net/scm.h>
 65 #include <net/netlink.h>
 66 
 67 #include "af_netlink.h"
 68 
 69 struct listeners {
 70         struct rcu_head         rcu;
 71         unsigned long           masks[0];
 72 };
 73 
 74 /* state bits */
 75 #define NETLINK_CONGESTED       0x0
 76 
 77 /* flags */
 78 #define NETLINK_KERNEL_SOCKET   0x1
 79 #define NETLINK_RECV_PKTINFO    0x2
 80 #define NETLINK_BROADCAST_SEND_ERROR    0x4
 81 #define NETLINK_RECV_NO_ENOBUFS 0x8
 82 
 83 static inline int netlink_is_kernel(struct sock *sk)
 84 {
 85         return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET;
 86 }
 87 
 88 struct netlink_table *nl_table;
 89 EXPORT_SYMBOL_GPL(nl_table);
 90 
 91 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 92 
 93 static int netlink_dump(struct sock *sk);
 94 static void netlink_skb_destructor(struct sk_buff *skb);
 95 
 96 DEFINE_RWLOCK(nl_table_lock);
 97 EXPORT_SYMBOL_GPL(nl_table_lock);
 98 static atomic_t nl_table_users = ATOMIC_INIT(0);
 99 
100 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
101 
102 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
103 
104 static inline u32 netlink_group_mask(u32 group)
105 {
106         return group ? 1 << (group - 1) : 0;
107 }
108 
109 static inline struct hlist_head *nl_portid_hashfn(struct nl_portid_hash *hash, u32 portid)
110 {
111         return &hash->table[jhash_1word(portid, hash->rnd) & hash->mask];
112 }
113 
114 static void netlink_overrun(struct sock *sk)
115 {
116         struct netlink_sock *nlk = nlk_sk(sk);
117 
118         if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
119                 if (!test_and_set_bit(NETLINK_CONGESTED, &nlk_sk(sk)->state)) {
120                         sk->sk_err = ENOBUFS;
121                         sk->sk_error_report(sk);
122                 }
123         }
124         atomic_inc(&sk->sk_drops);
125 }
126 
127 static void netlink_rcv_wake(struct sock *sk)
128 {
129         struct netlink_sock *nlk = nlk_sk(sk);
130 
131         if (skb_queue_empty(&sk->sk_receive_queue))
132                 clear_bit(NETLINK_CONGESTED, &nlk->state);
133         if (!test_bit(NETLINK_CONGESTED, &nlk->state))
134                 wake_up_interruptible(&nlk->wait);
135 }
136 
137 #ifdef CONFIG_NETLINK_MMAP
138 static bool netlink_skb_is_mmaped(const struct sk_buff *skb)
139 {
140         return NETLINK_CB(skb).flags & NETLINK_SKB_MMAPED;
141 }
142 
143 static bool netlink_rx_is_mmaped(struct sock *sk)
144 {
145         return nlk_sk(sk)->rx_ring.pg_vec != NULL;
146 }
147 
148 static bool netlink_tx_is_mmaped(struct sock *sk)
149 {
150         return nlk_sk(sk)->tx_ring.pg_vec != NULL;
151 }
152 
153 static __pure struct page *pgvec_to_page(const void *addr)
154 {
155         if (is_vmalloc_addr(addr))
156                 return vmalloc_to_page(addr);
157         else
158                 return virt_to_page(addr);
159 }
160 
161 static void free_pg_vec(void **pg_vec, unsigned int order, unsigned int len)
162 {
163         unsigned int i;
164 
165         for (i = 0; i < len; i++) {
166                 if (pg_vec[i] != NULL) {
167                         if (is_vmalloc_addr(pg_vec[i]))
168                                 vfree(pg_vec[i]);
169                         else
170                                 free_pages((unsigned long)pg_vec[i], order);
171                 }
172         }
173         kfree(pg_vec);
174 }
175 
176 static void *alloc_one_pg_vec_page(unsigned long order)
177 {
178         void *buffer;
179         gfp_t gfp_flags = GFP_KERNEL | __GFP_COMP | __GFP_ZERO |
180                           __GFP_NOWARN | __GFP_NORETRY;
181 
182         buffer = (void *)__get_free_pages(gfp_flags, order);
183         if (buffer != NULL)
184                 return buffer;
185 
186         buffer = vzalloc((1 << order) * PAGE_SIZE);
187         if (buffer != NULL)
188                 return buffer;
189 
190         gfp_flags &= ~__GFP_NORETRY;
191         return (void *)__get_free_pages(gfp_flags, order);
192 }
193 
194 static void **alloc_pg_vec(struct netlink_sock *nlk,
195                            struct nl_mmap_req *req, unsigned int order)
196 {
197         unsigned int block_nr = req->nm_block_nr;
198         unsigned int i;
199         void **pg_vec, *ptr;
200 
201         pg_vec = kcalloc(block_nr, sizeof(void *), GFP_KERNEL);
202         if (pg_vec == NULL)
203                 return NULL;
204 
205         for (i = 0; i < block_nr; i++) {
206                 pg_vec[i] = ptr = alloc_one_pg_vec_page(order);
207                 if (pg_vec[i] == NULL)
208                         goto err1;
209         }
210 
211         return pg_vec;
212 err1:
213         free_pg_vec(pg_vec, order, block_nr);
214         return NULL;
215 }
216 
217 
218 static void
219 __netlink_set_ring(struct sock *sk, struct nl_mmap_req *req, bool tx_ring, void **pg_vec,
220                    unsigned int order)
221 {
222         struct netlink_sock *nlk = nlk_sk(sk);
223         struct sk_buff_head *queue;
224         struct netlink_ring *ring;
225 
226         queue = tx_ring ? &sk->sk_write_queue : &sk->sk_receive_queue;
227         ring  = tx_ring ? &nlk->tx_ring : &nlk->rx_ring;
228 
229         spin_lock_bh(&queue->lock);
230 
231         ring->frame_max         = req->nm_frame_nr - 1;
232         ring->head              = 0;
233         ring->frame_size        = req->nm_frame_size;
234         ring->pg_vec_pages      = req->nm_block_size / PAGE_SIZE;
235 
236         swap(ring->pg_vec_len, req->nm_block_nr);
237         swap(ring->pg_vec_order, order);
238         swap(ring->pg_vec, pg_vec);
239 
240         __skb_queue_purge(queue);
241         spin_unlock_bh(&queue->lock);
242 
243         WARN_ON(atomic_read(&nlk->mapped));
244 
245         if (pg_vec)
246                 free_pg_vec(pg_vec, order, req->nm_block_nr);
247 }
248 
249 static int netlink_set_ring(struct sock *sk, struct nl_mmap_req *req,
250                             bool tx_ring)
251 {
252         struct netlink_sock *nlk = nlk_sk(sk);
253         struct netlink_ring *ring;
254         void **pg_vec = NULL;
255         unsigned int order = 0;
256 
257         ring  = tx_ring ? &nlk->tx_ring : &nlk->rx_ring;
258 
259         if (atomic_read(&nlk->mapped))
260                 return -EBUSY;
261         if (atomic_read(&ring->pending))
262                 return -EBUSY;
263 
264         if (req->nm_block_nr) {
265                 if (ring->pg_vec != NULL)
266                         return -EBUSY;
267 
268                 if ((int)req->nm_block_size <= 0)
269                         return -EINVAL;
270                 if (!IS_ALIGNED(req->nm_block_size, PAGE_SIZE))
271                         return -EINVAL;
272                 if (req->nm_frame_size < NL_MMAP_HDRLEN)
273                         return -EINVAL;
274                 if (!IS_ALIGNED(req->nm_frame_size, NL_MMAP_MSG_ALIGNMENT))
275                         return -EINVAL;
276 
277                 ring->frames_per_block = req->nm_block_size /
278                                          req->nm_frame_size;
279                 if (ring->frames_per_block == 0)
280                         return -EINVAL;
281                 if (ring->frames_per_block * req->nm_block_nr !=
282                     req->nm_frame_nr)
283                         return -EINVAL;
284 
285                 order = get_order(req->nm_block_size);
286                 pg_vec = alloc_pg_vec(nlk, req, order);
287                 if (pg_vec == NULL)
288                         return -ENOMEM;
289         } else {
290                 if (req->nm_frame_nr)
291                         return -EINVAL;
292         }
293 
294         mutex_lock(&nlk->pg_vec_lock);
295         if (atomic_read(&nlk->mapped) == 0) {
296                 __netlink_set_ring(sk, req, tx_ring, pg_vec, order);
297                 mutex_unlock(&nlk->pg_vec_lock);
298                 return 0;
299         }
300 
301         mutex_unlock(&nlk->pg_vec_lock);
302 
303         if (pg_vec)
304                 free_pg_vec(pg_vec, order, req->nm_block_nr);
305 
306         return -EBUSY;
307 }
308 
309 static void netlink_mm_open(struct vm_area_struct *vma)
310 {
311         struct file *file = vma->vm_file;
312         struct socket *sock = file->private_data;
313         struct sock *sk = sock->sk;
314 
315         if (sk)
316                 atomic_inc(&nlk_sk(sk)->mapped);
317 }
318 
319 static void netlink_mm_close(struct vm_area_struct *vma)
320 {
321         struct file *file = vma->vm_file;
322         struct socket *sock = file->private_data;
323         struct sock *sk = sock->sk;
324 
325         if (sk)
326                 atomic_dec(&nlk_sk(sk)->mapped);
327 }
328 
329 static const struct vm_operations_struct netlink_mmap_ops = {
330         .open   = netlink_mm_open,
331         .close  = netlink_mm_close,
332 };
333 
334 static int netlink_mmap(struct file *file, struct socket *sock,
335                         struct vm_area_struct *vma)
336 {
337         struct sock *sk = sock->sk;
338         struct netlink_sock *nlk = nlk_sk(sk);
339         struct netlink_ring *ring;
340         unsigned long start, size, expected;
341         unsigned int i;
342         int err = -EINVAL;
343 
344         if (vma->vm_pgoff)
345                 return -EINVAL;
346 
347         mutex_lock(&nlk->pg_vec_lock);
348 
349         expected = 0;
350         for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
351                 if (ring->pg_vec == NULL)
352                         continue;
353                 expected += ring->pg_vec_len * ring->pg_vec_pages * PAGE_SIZE;
354         }
355 
356         if (expected == 0)
357                 goto out;
358 
359         size = vma->vm_end - vma->vm_start;
360         if (size != expected)
361                 goto out;
362 
363         start = vma->vm_start;
364         for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
365                 if (ring->pg_vec == NULL)
366                         continue;
367 
368                 for (i = 0; i < ring->pg_vec_len; i++) {
369                         struct page *page;
370                         void *kaddr = ring->pg_vec[i];
371                         unsigned int pg_num;
372 
373                         for (pg_num = 0; pg_num < ring->pg_vec_pages; pg_num++) {
374                                 page = pgvec_to_page(kaddr);
375                                 err = vm_insert_page(vma, start, page);
376                                 if (err < 0)
377                                         goto out;
378                                 start += PAGE_SIZE;
379                                 kaddr += PAGE_SIZE;
380                         }
381                 }
382         }
383 
384         atomic_inc(&nlk->mapped);
385         vma->vm_ops = &netlink_mmap_ops;
386         err = 0;
387 out:
388         mutex_unlock(&nlk->pg_vec_lock);
389         return err;
390 }
391 
392 static void netlink_frame_flush_dcache(const struct nl_mmap_hdr *hdr, unsigned int nm_len)
393 {
394 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 1
395         struct page *p_start, *p_end;
396 
397         /* First page is flushed through netlink_{get,set}_status */
398         p_start = pgvec_to_page(hdr + PAGE_SIZE);
399         p_end   = pgvec_to_page((void *)hdr + NL_MMAP_HDRLEN + nm_len - 1);
400         while (p_start <= p_end) {
401                 flush_dcache_page(p_start);
402                 p_start++;
403         }
404 #endif
405 }
406 
407 static enum nl_mmap_status netlink_get_status(const struct nl_mmap_hdr *hdr)
408 {
409         smp_rmb();
410         flush_dcache_page(pgvec_to_page(hdr));
411         return hdr->nm_status;
412 }
413 
414 static void netlink_set_status(struct nl_mmap_hdr *hdr,
415                                enum nl_mmap_status status)
416 {
417         smp_mb();
418         hdr->nm_status = status;
419         flush_dcache_page(pgvec_to_page(hdr));
420 }
421 
422 static struct nl_mmap_hdr *
423 __netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos)
424 {
425         unsigned int pg_vec_pos, frame_off;
426 
427         pg_vec_pos = pos / ring->frames_per_block;
428         frame_off  = pos % ring->frames_per_block;
429 
430         return ring->pg_vec[pg_vec_pos] + (frame_off * ring->frame_size);
431 }
432 
433 static struct nl_mmap_hdr *
434 netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos,
435                      enum nl_mmap_status status)
436 {
437         struct nl_mmap_hdr *hdr;
438 
439         hdr = __netlink_lookup_frame(ring, pos);
440         if (netlink_get_status(hdr) != status)
441                 return NULL;
442 
443         return hdr;
444 }
445 
446 static struct nl_mmap_hdr *
447 netlink_current_frame(const struct netlink_ring *ring,
448                       enum nl_mmap_status status)
449 {
450         return netlink_lookup_frame(ring, ring->head, status);
451 }
452 
453 static struct nl_mmap_hdr *
454 netlink_previous_frame(const struct netlink_ring *ring,
455                        enum nl_mmap_status status)
456 {
457         unsigned int prev;
458 
459         prev = ring->head ? ring->head - 1 : ring->frame_max;
460         return netlink_lookup_frame(ring, prev, status);
461 }
462 
463 static void netlink_increment_head(struct netlink_ring *ring)
464 {
465         ring->head = ring->head != ring->frame_max ? ring->head + 1 : 0;
466 }
467 
468 static void netlink_forward_ring(struct netlink_ring *ring)
469 {
470         unsigned int head = ring->head, pos = head;
471         const struct nl_mmap_hdr *hdr;
472 
473         do {
474                 hdr = __netlink_lookup_frame(ring, pos);
475                 if (hdr->nm_status == NL_MMAP_STATUS_UNUSED)
476                         break;
477                 if (hdr->nm_status != NL_MMAP_STATUS_SKIP)
478                         break;
479                 netlink_increment_head(ring);
480         } while (ring->head != head);
481 }
482 
483 static bool netlink_dump_space(struct netlink_sock *nlk)
484 {
485         struct netlink_ring *ring = &nlk->rx_ring;
486         struct nl_mmap_hdr *hdr;
487         unsigned int n;
488 
489         hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
490         if (hdr == NULL)
491                 return false;
492 
493         n = ring->head + ring->frame_max / 2;
494         if (n > ring->frame_max)
495                 n -= ring->frame_max;
496 
497         hdr = __netlink_lookup_frame(ring, n);
498 
499         return hdr->nm_status == NL_MMAP_STATUS_UNUSED;
500 }
501 
502 static unsigned int netlink_poll(struct file *file, struct socket *sock,
503                                  poll_table *wait)
504 {
505         struct sock *sk = sock->sk;
506         struct netlink_sock *nlk = nlk_sk(sk);
507         unsigned int mask;
508         int err;
509 
510         if (nlk->rx_ring.pg_vec != NULL) {
511                 /* Memory mapped sockets don't call recvmsg(), so flow control
512                  * for dumps is performed here. A dump is allowed to continue
513                  * if at least half the ring is unused.
514                  */
515                 while (nlk->cb != NULL && netlink_dump_space(nlk)) {
516                         err = netlink_dump(sk);
517                         if (err < 0) {
518                                 sk->sk_err = -err;
519                                 sk->sk_error_report(sk);
520                                 break;
521                         }
522                 }
523                 netlink_rcv_wake(sk);
524         }
525 
526         mask = datagram_poll(file, sock, wait);
527 
528         spin_lock_bh(&sk->sk_receive_queue.lock);
529         if (nlk->rx_ring.pg_vec) {
530                 netlink_forward_ring(&nlk->rx_ring);
531                 if (!netlink_previous_frame(&nlk->rx_ring, NL_MMAP_STATUS_UNUSED))
532                         mask |= POLLIN | POLLRDNORM;
533         }
534         spin_unlock_bh(&sk->sk_receive_queue.lock);
535 
536         spin_lock_bh(&sk->sk_write_queue.lock);
537         if (nlk->tx_ring.pg_vec) {
538                 if (netlink_current_frame(&nlk->tx_ring, NL_MMAP_STATUS_UNUSED))
539                         mask |= POLLOUT | POLLWRNORM;
540         }
541         spin_unlock_bh(&sk->sk_write_queue.lock);
542 
543         return mask;
544 }
545 
546 static struct nl_mmap_hdr *netlink_mmap_hdr(struct sk_buff *skb)
547 {
548         return (struct nl_mmap_hdr *)(skb->head - NL_MMAP_HDRLEN);
549 }
550 
551 static void netlink_ring_setup_skb(struct sk_buff *skb, struct sock *sk,
552                                    struct netlink_ring *ring,
553                                    struct nl_mmap_hdr *hdr)
554 {
555         unsigned int size;
556         void *data;
557 
558         size = ring->frame_size - NL_MMAP_HDRLEN;
559         data = (void *)hdr + NL_MMAP_HDRLEN;
560 
561         skb->head       = data;
562         skb->data       = data;
563         skb_reset_tail_pointer(skb);
564         skb->end        = skb->tail + size;
565         skb->len        = 0;
566 
567         skb->destructor = netlink_skb_destructor;
568         NETLINK_CB(skb).flags |= NETLINK_SKB_MMAPED;
569         NETLINK_CB(skb).sk = sk;
570 }
571 
572 static int netlink_mmap_sendmsg(struct sock *sk, struct msghdr *msg,
573                                 u32 dst_portid, u32 dst_group,
574                                 struct sock_iocb *siocb)
575 {
576         struct netlink_sock *nlk = nlk_sk(sk);
577         struct netlink_ring *ring;
578         struct nl_mmap_hdr *hdr;
579         struct sk_buff *skb;
580         unsigned int maxlen;
581         int err = 0, len = 0;
582 
583         mutex_lock(&nlk->pg_vec_lock);
584 
585         ring   = &nlk->tx_ring;
586         maxlen = ring->frame_size - NL_MMAP_HDRLEN;
587 
588         do {
589                 unsigned int nm_len;
590 
591                 hdr = netlink_current_frame(ring, NL_MMAP_STATUS_VALID);
592                 if (hdr == NULL) {
593                         if (!(msg->msg_flags & MSG_DONTWAIT) &&
594                             atomic_read(&nlk->tx_ring.pending))
595                                 schedule();
596                         continue;
597                 }
598 
599                 nm_len = ACCESS_ONCE(hdr->nm_len);
600                 if (nm_len > maxlen) {
601                         err = -EINVAL;
602                         goto out;
603                 }
604 
605                 netlink_frame_flush_dcache(hdr, nm_len);
606 
607                 skb = alloc_skb(nm_len, GFP_KERNEL);
608                 if (skb == NULL) {
609                         err = -ENOBUFS;
610                         goto out;
611                 }
612                 __skb_put(skb, nm_len);
613                 memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, nm_len);
614                 netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
615 
616                 netlink_increment_head(ring);
617 
618                 NETLINK_CB(skb).portid    = nlk->portid;
619                 NETLINK_CB(skb).dst_group = dst_group;
620                 NETLINK_CB(skb).creds     = siocb->scm->creds;
621 
622                 err = security_netlink_send(sk, skb);
623                 if (err) {
624                         kfree_skb(skb);
625                         goto out;
626                 }
627 
628                 if (unlikely(dst_group)) {
629                         atomic_inc(&skb->users);
630                         netlink_broadcast(sk, skb, dst_portid, dst_group,
631                                           GFP_KERNEL);
632                 }
633                 err = netlink_unicast(sk, skb, dst_portid,
634                                       msg->msg_flags & MSG_DONTWAIT);
635                 if (err < 0)
636                         goto out;
637                 len += err;
638 
639         } while (hdr != NULL ||
640                  (!(msg->msg_flags & MSG_DONTWAIT) &&
641                   atomic_read(&nlk->tx_ring.pending)));
642 
643         if (len > 0)
644                 err = len;
645 out:
646         mutex_unlock(&nlk->pg_vec_lock);
647         return err;
648 }
649 
650 static void netlink_queue_mmaped_skb(struct sock *sk, struct sk_buff *skb)
651 {
652         struct nl_mmap_hdr *hdr;
653 
654         hdr = netlink_mmap_hdr(skb);
655         hdr->nm_len     = skb->len;
656         hdr->nm_group   = NETLINK_CB(skb).dst_group;
657         hdr->nm_pid     = NETLINK_CB(skb).creds.pid;
658         hdr->nm_uid     = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
659         hdr->nm_gid     = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
660         netlink_frame_flush_dcache(hdr, hdr->nm_len);
661         netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
662 
663         NETLINK_CB(skb).flags |= NETLINK_SKB_DELIVERED;
664         kfree_skb(skb);
665 }
666 
667 static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
668 {
669         struct netlink_sock *nlk = nlk_sk(sk);
670         struct netlink_ring *ring = &nlk->rx_ring;
671         struct nl_mmap_hdr *hdr;
672 
673         spin_lock_bh(&sk->sk_receive_queue.lock);
674         hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
675         if (hdr == NULL) {
676                 spin_unlock_bh(&sk->sk_receive_queue.lock);
677                 kfree_skb(skb);
678                 netlink_overrun(sk);
679                 return;
680         }
681         netlink_increment_head(ring);
682         __skb_queue_tail(&sk->sk_receive_queue, skb);
683         spin_unlock_bh(&sk->sk_receive_queue.lock);
684 
685         hdr->nm_len     = skb->len;
686         hdr->nm_group   = NETLINK_CB(skb).dst_group;
687         hdr->nm_pid     = NETLINK_CB(skb).creds.pid;
688         hdr->nm_uid     = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
689         hdr->nm_gid     = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
690         netlink_set_status(hdr, NL_MMAP_STATUS_COPY);
691 }
692 
693 #else /* CONFIG_NETLINK_MMAP */
694 #define netlink_skb_is_mmaped(skb)      false
695 #define netlink_rx_is_mmaped(sk)        false
696 #define netlink_tx_is_mmaped(sk)        false
697 #define netlink_mmap                    sock_no_mmap
698 #define netlink_poll                    datagram_poll
699 #define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, siocb)     0
700 #endif /* CONFIG_NETLINK_MMAP */
701 
702 static void netlink_destroy_callback(struct netlink_callback *cb)
703 {
704         kfree_skb(cb->skb);
705         kfree(cb);
706 }
707 
708 static void netlink_consume_callback(struct netlink_callback *cb)
709 {
710         consume_skb(cb->skb);
711         kfree(cb);
712 }
713 
714 static void netlink_skb_destructor(struct sk_buff *skb)
715 {
716 #ifdef CONFIG_NETLINK_MMAP
717         struct nl_mmap_hdr *hdr;
718         struct netlink_ring *ring;
719         struct sock *sk;
720 
721         /* If a packet from the kernel to userspace was freed because of an
722          * error without being delivered to userspace, the kernel must reset
723          * the status. In the direction userspace to kernel, the status is
724          * always reset here after the packet was processed and freed.
725          */
726         if (netlink_skb_is_mmaped(skb)) {
727                 hdr = netlink_mmap_hdr(skb);
728                 sk = NETLINK_CB(skb).sk;
729 
730                 if (NETLINK_CB(skb).flags & NETLINK_SKB_TX) {
731                         netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
732                         ring = &nlk_sk(sk)->tx_ring;
733                 } else {
734                         if (!(NETLINK_CB(skb).flags & NETLINK_SKB_DELIVERED)) {
735                                 hdr->nm_len = 0;
736                                 netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
737                         }
738                         ring = &nlk_sk(sk)->rx_ring;
739                 }
740 
741                 WARN_ON(atomic_read(&ring->pending) == 0);
742                 atomic_dec(&ring->pending);
743                 sock_put(sk);
744 
745                 skb->head = NULL;
746         }
747 #endif
748         if (skb->sk != NULL)
749                 sock_rfree(skb);
750 }
751 
752 static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
753 {
754         WARN_ON(skb->sk != NULL);
755         skb->sk = sk;
756         skb->destructor = netlink_skb_destructor;
757         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
758         sk_mem_charge(sk, skb->truesize);
759 }
760 
761 static void netlink_sock_destruct(struct sock *sk)
762 {
763         struct netlink_sock *nlk = nlk_sk(sk);
764 
765         if (nlk->cb) {
766                 if (nlk->cb->done)
767                         nlk->cb->done(nlk->cb);
768 
769                 module_put(nlk->cb->module);
770                 netlink_destroy_callback(nlk->cb);
771         }
772 
773         skb_queue_purge(&sk->sk_receive_queue);
774 #ifdef CONFIG_NETLINK_MMAP
775         if (1) {
776                 struct nl_mmap_req req;
777 
778                 memset(&req, 0, sizeof(req));
779                 if (nlk->rx_ring.pg_vec)
780                         __netlink_set_ring(sk, &req, false, NULL, 0);
781                 memset(&req, 0, sizeof(req));
782                 if (nlk->tx_ring.pg_vec)
783                         __netlink_set_ring(sk, &req, true, NULL, 0);
784         }
785 #endif /* CONFIG_NETLINK_MMAP */
786 
787         if (!sock_flag(sk, SOCK_DEAD)) {
788                 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
789                 return;
790         }
791 
792         WARN_ON(atomic_read(&sk->sk_rmem_alloc));
793         WARN_ON(atomic_read(&sk->sk_wmem_alloc));
794         WARN_ON(nlk_sk(sk)->groups);
795 }
796 
797 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
798  * SMP. Look, when several writers sleep and reader wakes them up, all but one
799  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
800  * this, _but_ remember, it adds useless work on UP machines.
801  */
802 
803 void netlink_table_grab(void)
804         __acquires(nl_table_lock)
805 {
806         might_sleep();
807 
808         write_lock_irq(&nl_table_lock);
809 
810         if (atomic_read(&nl_table_users)) {
811                 DECLARE_WAITQUEUE(wait, current);
812 
813                 add_wait_queue_exclusive(&nl_table_wait, &wait);
814                 for (;;) {
815                         set_current_state(TASK_UNINTERRUPTIBLE);
816                         if (atomic_read(&nl_table_users) == 0)
817                                 break;
818                         write_unlock_irq(&nl_table_lock);
819                         schedule();
820                         write_lock_irq(&nl_table_lock);
821                 }
822 
823                 __set_current_state(TASK_RUNNING);
824                 remove_wait_queue(&nl_table_wait, &wait);
825         }
826 }
827 
828 void netlink_table_ungrab(void)
829         __releases(nl_table_lock)
830 {
831         write_unlock_irq(&nl_table_lock);
832         wake_up(&nl_table_wait);
833 }
834 
835 static inline void
836 netlink_lock_table(void)
837 {
838         /* read_lock() synchronizes us to netlink_table_grab */
839 
840         read_lock(&nl_table_lock);
841         atomic_inc(&nl_table_users);
842         read_unlock(&nl_table_lock);
843 }
844 
845 static inline void
846 netlink_unlock_table(void)
847 {
848         if (atomic_dec_and_test(&nl_table_users))
849                 wake_up(&nl_table_wait);
850 }
851 
852 static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
853 {
854         struct nl_portid_hash *hash = &nl_table[protocol].hash;
855         struct hlist_head *head;
856         struct sock *sk;
857 
858         read_lock(&nl_table_lock);
859         head = nl_portid_hashfn(hash, portid);
860         sk_for_each(sk, head) {
861                 if (net_eq(sock_net(sk), net) && (nlk_sk(sk)->portid == portid)) {
862                         sock_hold(sk);
863                         goto found;
864                 }
865         }
866         sk = NULL;
867 found:
868         read_unlock(&nl_table_lock);
869         return sk;
870 }
871 
872 static struct hlist_head *nl_portid_hash_zalloc(size_t size)
873 {
874         if (size <= PAGE_SIZE)
875                 return kzalloc(size, GFP_ATOMIC);
876         else
877                 return (struct hlist_head *)
878                         __get_free_pages(GFP_ATOMIC | __GFP_ZERO,
879                                          get_order(size));
880 }
881 
882 static void nl_portid_hash_free(struct hlist_head *table, size_t size)
883 {
884         if (size <= PAGE_SIZE)
885                 kfree(table);
886         else
887                 free_pages((unsigned long)table, get_order(size));
888 }
889 
890 static int nl_portid_hash_rehash(struct nl_portid_hash *hash, int grow)
891 {
892         unsigned int omask, mask, shift;
893         size_t osize, size;
894         struct hlist_head *otable, *table;
895         int i;
896 
897         omask = mask = hash->mask;
898         osize = size = (mask + 1) * sizeof(*table);
899         shift = hash->shift;
900 
901         if (grow) {
902                 if (++shift > hash->max_shift)
903                         return 0;
904                 mask = mask * 2 + 1;
905                 size *= 2;
906         }
907 
908         table = nl_portid_hash_zalloc(size);
909         if (!table)
910                 return 0;
911 
912         otable = hash->table;
913         hash->table = table;
914         hash->mask = mask;
915         hash->shift = shift;
916         get_random_bytes(&hash->rnd, sizeof(hash->rnd));
917 
918         for (i = 0; i <= omask; i++) {
919                 struct sock *sk;
920                 struct hlist_node *tmp;
921 
922                 sk_for_each_safe(sk, tmp, &otable[i])
923                         __sk_add_node(sk, nl_portid_hashfn(hash, nlk_sk(sk)->portid));
924         }
925 
926         nl_portid_hash_free(otable, osize);
927         hash->rehash_time = jiffies + 10 * 60 * HZ;
928         return 1;
929 }
930 
931 static inline int nl_portid_hash_dilute(struct nl_portid_hash *hash, int len)
932 {
933         int avg = hash->entries >> hash->shift;
934 
935         if (unlikely(avg > 1) && nl_portid_hash_rehash(hash, 1))
936                 return 1;
937 
938         if (unlikely(len > avg) && time_after(jiffies, hash->rehash_time)) {
939                 nl_portid_hash_rehash(hash, 0);
940                 return 1;
941         }
942 
943         return 0;
944 }
945 
946 static const struct proto_ops netlink_ops;
947 
948 static void
949 netlink_update_listeners(struct sock *sk)
950 {
951         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
952         unsigned long mask;
953         unsigned int i;
954         struct listeners *listeners;
955 
956         listeners = nl_deref_protected(tbl->listeners);
957         if (!listeners)
958                 return;
959 
960         for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
961                 mask = 0;
962                 sk_for_each_bound(sk, &tbl->mc_list) {
963                         if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
964                                 mask |= nlk_sk(sk)->groups[i];
965                 }
966                 listeners->masks[i] = mask;
967         }
968         /* this function is only called with the netlink table "grabbed", which
969          * makes sure updates are visible before bind or setsockopt return. */
970 }
971 
972 static int netlink_insert(struct sock *sk, struct net *net, u32 portid)
973 {
974         struct nl_portid_hash *hash = &nl_table[sk->sk_protocol].hash;
975         struct hlist_head *head;
976         int err = -EADDRINUSE;
977         struct sock *osk;
978         int len;
979 
980         netlink_table_grab();
981         head = nl_portid_hashfn(hash, portid);
982         len = 0;
983         sk_for_each(osk, head) {
984                 if (net_eq(sock_net(osk), net) && (nlk_sk(osk)->portid == portid))
985                         break;
986                 len++;
987         }
988         if (osk)
989                 goto err;
990 
991         err = -EBUSY;
992         if (nlk_sk(sk)->portid)
993                 goto err;
994 
995         err = -ENOMEM;
996         if (BITS_PER_LONG > 32 && unlikely(hash->entries >= UINT_MAX))
997                 goto err;
998 
999         if (len && nl_portid_hash_dilute(hash, len))
1000                 head = nl_portid_hashfn(hash, portid);
1001         hash->entries++;
1002         nlk_sk(sk)->portid = portid;
1003         sk_add_node(sk, head);
1004         err = 0;
1005 
1006 err:
1007         netlink_table_ungrab();
1008         return err;
1009 }
1010 
1011 static void netlink_remove(struct sock *sk)
1012 {
1013         netlink_table_grab();
1014         if (sk_del_node_init(sk))
1015                 nl_table[sk->sk_protocol].hash.entries--;
1016         if (nlk_sk(sk)->subscriptions)
1017                 __sk_del_bind_node(sk);
1018         netlink_table_ungrab();
1019 }
1020 
1021 static struct proto netlink_proto = {
1022         .name     = "NETLINK",
1023         .owner    = THIS_MODULE,
1024         .obj_size = sizeof(struct netlink_sock),
1025 };
1026 
1027 static int __netlink_create(struct net *net, struct socket *sock,
1028                             struct mutex *cb_mutex, int protocol)
1029 {
1030         struct sock *sk;
1031         struct netlink_sock *nlk;
1032 
1033         sock->ops = &netlink_ops;
1034 
1035         sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto);
1036         if (!sk)
1037                 return -ENOMEM;
1038 
1039         sock_init_data(sock, sk);
1040 
1041         nlk = nlk_sk(sk);
1042         if (cb_mutex) {
1043                 nlk->cb_mutex = cb_mutex;
1044         } else {
1045                 nlk->cb_mutex = &nlk->cb_def_mutex;
1046                 mutex_init(nlk->cb_mutex);
1047         }
1048         init_waitqueue_head(&nlk->wait);
1049 #ifdef CONFIG_NETLINK_MMAP
1050         mutex_init(&nlk->pg_vec_lock);
1051 #endif
1052 
1053         sk->sk_destruct = netlink_sock_destruct;
1054         sk->sk_protocol = protocol;
1055         return 0;
1056 }
1057 
1058 static int netlink_create(struct net *net, struct socket *sock, int protocol,
1059                           int kern)
1060 {
1061         struct module *module = NULL;
1062         struct mutex *cb_mutex;
1063         struct netlink_sock *nlk;
1064         void (*bind)(int group);
1065         int err = 0;
1066 
1067         sock->state = SS_UNCONNECTED;
1068 
1069         if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
1070                 return -ESOCKTNOSUPPORT;
1071 
1072         if (protocol < 0 || protocol >= MAX_LINKS)
1073                 return -EPROTONOSUPPORT;
1074 
1075         netlink_lock_table();
1076 #ifdef CONFIG_MODULES
1077         if (!nl_table[protocol].registered) {
1078                 netlink_unlock_table();
1079                 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
1080                 netlink_lock_table();
1081         }
1082 #endif
1083         if (nl_table[protocol].registered &&
1084             try_module_get(nl_table[protocol].module))
1085                 module = nl_table[protocol].module;
1086         else
1087                 err = -EPROTONOSUPPORT;
1088         cb_mutex = nl_table[protocol].cb_mutex;
1089         bind = nl_table[protocol].bind;
1090         netlink_unlock_table();
1091 
1092         if (err < 0)
1093                 goto out;
1094 
1095         err = __netlink_create(net, sock, cb_mutex, protocol);
1096         if (err < 0)
1097                 goto out_module;
1098 
1099         local_bh_disable();
1100         sock_prot_inuse_add(net, &netlink_proto, 1);
1101         local_bh_enable();
1102 
1103         nlk = nlk_sk(sock->sk);
1104         nlk->module = module;
1105         nlk->netlink_bind = bind;
1106 out:
1107         return err;
1108 
1109 out_module:
1110         module_put(module);
1111         goto out;
1112 }
1113 
1114 static int netlink_release(struct socket *sock)
1115 {
1116         struct sock *sk = sock->sk;
1117         struct netlink_sock *nlk;
1118 
1119         if (!sk)
1120                 return 0;
1121 
1122         netlink_remove(sk);
1123         sock_orphan(sk);
1124         nlk = nlk_sk(sk);
1125 
1126         /*
1127          * OK. Socket is unlinked, any packets that arrive now
1128          * will be purged.
1129          */
1130 
1131         sock->sk = NULL;
1132         wake_up_interruptible_all(&nlk->wait);
1133 
1134         skb_queue_purge(&sk->sk_write_queue);
1135 
1136         if (nlk->portid) {
1137                 struct netlink_notify n = {
1138                                                 .net = sock_net(sk),
1139                                                 .protocol = sk->sk_protocol,
1140                                                 .portid = nlk->portid,
1141                                           };
1142                 atomic_notifier_call_chain(&netlink_chain,
1143                                 NETLINK_URELEASE, &n);
1144         }
1145 
1146         module_put(nlk->module);
1147 
1148         netlink_table_grab();
1149         if (netlink_is_kernel(sk)) {
1150                 BUG_ON(nl_table[sk->sk_protocol].registered == 0);
1151                 if (--nl_table[sk->sk_protocol].registered == 0) {
1152                         struct listeners *old;
1153 
1154                         old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
1155                         RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
1156                         kfree_rcu(old, rcu);
1157                         nl_table[sk->sk_protocol].module = NULL;
1158                         nl_table[sk->sk_protocol].bind = NULL;
1159                         nl_table[sk->sk_protocol].flags = 0;
1160                         nl_table[sk->sk_protocol].registered = 0;
1161                 }
1162         } else if (nlk->subscriptions) {
1163                 netlink_update_listeners(sk);
1164         }
1165         netlink_table_ungrab();
1166 
1167         kfree(nlk->groups);
1168         nlk->groups = NULL;
1169 
1170         local_bh_disable();
1171         sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
1172         local_bh_enable();
1173         sock_put(sk);
1174         return 0;
1175 }
1176 
1177 static int netlink_autobind(struct socket *sock)
1178 {
1179         struct sock *sk = sock->sk;
1180         struct net *net = sock_net(sk);
1181         struct nl_portid_hash *hash = &nl_table[sk->sk_protocol].hash;
1182         struct hlist_head *head;
1183         struct sock *osk;
1184         s32 portid = task_tgid_vnr(current);
1185         int err;
1186         static s32 rover = -4097;
1187 
1188 retry:
1189         cond_resched();
1190         netlink_table_grab();
1191         head = nl_portid_hashfn(hash, portid);
1192         sk_for_each(osk, head) {
1193                 if (!net_eq(sock_net(osk), net))
1194                         continue;
1195                 if (nlk_sk(osk)->portid == portid) {
1196                         /* Bind collision, search negative portid values. */
1197                         portid = rover--;
1198                         if (rover > -4097)
1199                                 rover = -4097;
1200                         netlink_table_ungrab();
1201                         goto retry;
1202                 }
1203         }
1204         netlink_table_ungrab();
1205 
1206         err = netlink_insert(sk, net, portid);
1207         if (err == -EADDRINUSE)
1208                 goto retry;
1209 
1210         /* If 2 threads race to autobind, that is fine.  */
1211         if (err == -EBUSY)
1212                 err = 0;
1213 
1214         return err;
1215 }
1216 
1217 /**
1218  * __netlink_ns_capable - General netlink message capability test
1219  * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
1220  * @user_ns: The user namespace of the capability to use
1221  * @cap: The capability to use
1222  *
1223  * Test to see if the opener of the socket we received the message
1224  * from had when the netlink socket was created and the sender of the
1225  * message has has the capability @cap in the user namespace @user_ns.
1226  */
1227 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
1228                         struct user_namespace *user_ns, int cap)
1229 {
1230         return ((nsp->flags & NETLINK_SKB_DST) ||
1231                 file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
1232                 ns_capable(user_ns, cap);
1233 }
1234 EXPORT_SYMBOL(__netlink_ns_capable);
1235 
1236 /**
1237  * netlink_ns_capable - General netlink message capability test
1238  * @skb: socket buffer holding a netlink command from userspace
1239  * @user_ns: The user namespace of the capability to use
1240  * @cap: The capability to use
1241  *
1242  * Test to see if the opener of the socket we received the message
1243  * from had when the netlink socket was created and the sender of the
1244  * message has has the capability @cap in the user namespace @user_ns.
1245  */
1246 bool netlink_ns_capable(const struct sk_buff *skb,
1247                         struct user_namespace *user_ns, int cap)
1248 {
1249         return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
1250 }
1251 EXPORT_SYMBOL(netlink_ns_capable);
1252 
1253 /**
1254  * netlink_capable - Netlink global message capability test
1255  * @skb: socket buffer holding a netlink command from userspace
1256  * @cap: The capability to use
1257  *
1258  * Test to see if the opener of the socket we received the message
1259  * from had when the netlink socket was created and the sender of the
1260  * message has has the capability @cap in all user namespaces.
1261  */
1262 bool netlink_capable(const struct sk_buff *skb, int cap)
1263 {
1264         return netlink_ns_capable(skb, &init_user_ns, cap);
1265 }
1266 EXPORT_SYMBOL(netlink_capable);
1267 
1268 /**
1269  * netlink_net_capable - Netlink network namespace message capability test
1270  * @skb: socket buffer holding a netlink command from userspace
1271  * @cap: The capability to use
1272  *
1273  * Test to see if the opener of the socket we received the message
1274  * from had when the netlink socket was created and the sender of the
1275  * message has has the capability @cap over the network namespace of
1276  * the socket we received the message from.
1277  */
1278 bool netlink_net_capable(const struct sk_buff *skb, int cap)
1279 {
1280         return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
1281 }
1282 EXPORT_SYMBOL(netlink_net_capable);
1283 
1284 static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
1285 {
1286         return (nl_table[sock->sk->sk_protocol].flags & flag) ||
1287                 ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
1288 }
1289 
1290 static void
1291 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
1292 {
1293         struct netlink_sock *nlk = nlk_sk(sk);
1294 
1295         if (nlk->subscriptions && !subscriptions)
1296                 __sk_del_bind_node(sk);
1297         else if (!nlk->subscriptions && subscriptions)
1298                 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
1299         nlk->subscriptions = subscriptions;
1300 }
1301 
1302 static int netlink_realloc_groups(struct sock *sk)
1303 {
1304         struct netlink_sock *nlk = nlk_sk(sk);
1305         unsigned int groups;
1306         unsigned long *new_groups;
1307         int err = 0;
1308 
1309         netlink_table_grab();
1310 
1311         groups = nl_table[sk->sk_protocol].groups;
1312         if (!nl_table[sk->sk_protocol].registered) {
1313                 err = -ENOENT;
1314                 goto out_unlock;
1315         }
1316 
1317         if (nlk->ngroups >= groups)
1318                 goto out_unlock;
1319 
1320         new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
1321         if (new_groups == NULL) {
1322                 err = -ENOMEM;
1323                 goto out_unlock;
1324         }
1325         memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
1326                NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
1327 
1328         nlk->groups = new_groups;
1329         nlk->ngroups = groups;
1330  out_unlock:
1331         netlink_table_ungrab();
1332         return err;
1333 }
1334 
1335 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
1336                         int addr_len)
1337 {
1338         struct sock *sk = sock->sk;
1339         struct net *net = sock_net(sk);
1340         struct netlink_sock *nlk = nlk_sk(sk);
1341         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
1342         int err;
1343 
1344         if (addr_len < sizeof(struct sockaddr_nl))
1345                 return -EINVAL;
1346 
1347         if (nladdr->nl_family != AF_NETLINK)
1348                 return -EINVAL;
1349 
1350         /* Only superuser is allowed to listen multicasts */
1351         if (nladdr->nl_groups) {
1352                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
1353                         return -EPERM;
1354                 err = netlink_realloc_groups(sk);
1355                 if (err)
1356                         return err;
1357         }
1358 
1359         if (nlk->portid) {
1360                 if (nladdr->nl_pid != nlk->portid)
1361                         return -EINVAL;
1362         } else {
1363                 err = nladdr->nl_pid ?
1364                         netlink_insert(sk, net, nladdr->nl_pid) :
1365                         netlink_autobind(sock);
1366                 if (err)
1367                         return err;
1368         }
1369 
1370         if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
1371                 return 0;
1372 
1373         netlink_table_grab();
1374         netlink_update_subscriptions(sk, nlk->subscriptions +
1375                                          hweight32(nladdr->nl_groups) -
1376                                          hweight32(nlk->groups[0]));
1377         nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
1378         netlink_update_listeners(sk);
1379         netlink_table_ungrab();
1380 
1381         if (nlk->netlink_bind && nlk->groups[0]) {
1382                 int i;
1383 
1384                 for (i=0; i<nlk->ngroups; i++) {
1385                         if (test_bit(i, nlk->groups))
1386                                 nlk->netlink_bind(i);
1387                 }
1388         }
1389 
1390         return 0;
1391 }
1392 
1393 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
1394                            int alen, int flags)
1395 {
1396         int err = 0;
1397         struct sock *sk = sock->sk;
1398         struct netlink_sock *nlk = nlk_sk(sk);
1399         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
1400 
1401         if (alen < sizeof(addr->sa_family))
1402                 return -EINVAL;
1403 
1404         if (addr->sa_family == AF_UNSPEC) {
1405                 sk->sk_state    = NETLINK_UNCONNECTED;
1406                 nlk->dst_portid = 0;
1407                 nlk->dst_group  = 0;
1408                 return 0;
1409         }
1410         if (addr->sa_family != AF_NETLINK)
1411                 return -EINVAL;
1412 
1413         /* Only superuser is allowed to send multicasts */
1414         if (nladdr->nl_groups && !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1415                 return -EPERM;
1416 
1417         if (!nlk->portid)
1418                 err = netlink_autobind(sock);
1419 
1420         if (err == 0) {
1421                 sk->sk_state    = NETLINK_CONNECTED;
1422                 nlk->dst_portid = nladdr->nl_pid;
1423                 nlk->dst_group  = ffs(nladdr->nl_groups);
1424         }
1425 
1426         return err;
1427 }
1428 
1429 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
1430                            int *addr_len, int peer)
1431 {
1432         struct sock *sk = sock->sk;
1433         struct netlink_sock *nlk = nlk_sk(sk);
1434         DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
1435 
1436         nladdr->nl_family = AF_NETLINK;
1437         nladdr->nl_pad = 0;
1438         *addr_len = sizeof(*nladdr);
1439 
1440         if (peer) {
1441                 nladdr->nl_pid = nlk->dst_portid;
1442                 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
1443         } else {
1444                 nladdr->nl_pid = nlk->portid;
1445                 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
1446         }
1447         return 0;
1448 }
1449 
1450 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
1451 {
1452         struct sock *sock;
1453         struct netlink_sock *nlk;
1454 
1455         sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
1456         if (!sock)
1457                 return ERR_PTR(-ECONNREFUSED);
1458 
1459         /* Don't bother queuing skb if kernel socket has no input function */
1460         nlk = nlk_sk(sock);
1461         if (sock->sk_state == NETLINK_CONNECTED &&
1462             nlk->dst_portid != nlk_sk(ssk)->portid) {
1463                 sock_put(sock);
1464                 return ERR_PTR(-ECONNREFUSED);
1465         }
1466         return sock;
1467 }
1468 
1469 struct sock *netlink_getsockbyfilp(struct file *filp)
1470 {
1471         struct inode *inode = file_inode(filp);
1472         struct sock *sock;
1473 
1474         if (!S_ISSOCK(inode->i_mode))
1475                 return ERR_PTR(-ENOTSOCK);
1476 
1477         sock = SOCKET_I(inode)->sk;
1478         if (sock->sk_family != AF_NETLINK)
1479                 return ERR_PTR(-EINVAL);
1480 
1481         sock_hold(sock);
1482         return sock;
1483 }
1484 
1485 /*
1486  * Attach a skb to a netlink socket.
1487  * The caller must hold a reference to the destination socket. On error, the
1488  * reference is dropped. The skb is not send to the destination, just all
1489  * all error checks are performed and memory in the queue is reserved.
1490  * Return values:
1491  * < 0: error. skb freed, reference to sock dropped.
1492  * 0: continue
1493  * 1: repeat lookup - reference dropped while waiting for socket memory.
1494  */
1495 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
1496                       long *timeo, struct sock *ssk)
1497 {
1498         struct netlink_sock *nlk;
1499 
1500         nlk = nlk_sk(sk);
1501 
1502         if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1503              test_bit(NETLINK_CONGESTED, &nlk->state)) &&
1504             !netlink_skb_is_mmaped(skb)) {
1505                 DECLARE_WAITQUEUE(wait, current);
1506                 if (!*timeo) {
1507                         if (!ssk || netlink_is_kernel(ssk))
1508                                 netlink_overrun(sk);
1509                         sock_put(sk);
1510                         kfree_skb(skb);
1511                         return -EAGAIN;
1512                 }
1513 
1514                 __set_current_state(TASK_INTERRUPTIBLE);
1515                 add_wait_queue(&nlk->wait, &wait);
1516 
1517                 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1518                      test_bit(NETLINK_CONGESTED, &nlk->state)) &&
1519                     !sock_flag(sk, SOCK_DEAD))
1520                         *timeo = schedule_timeout(*timeo);
1521 
1522                 __set_current_state(TASK_RUNNING);
1523                 remove_wait_queue(&nlk->wait, &wait);
1524                 sock_put(sk);
1525 
1526                 if (signal_pending(current)) {
1527                         kfree_skb(skb);
1528                         return sock_intr_errno(*timeo);
1529                 }
1530                 return 1;
1531         }
1532         netlink_skb_set_owner_r(skb, sk);
1533         return 0;
1534 }
1535 
1536 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1537 {
1538         int len = skb->len;
1539 
1540 #ifdef CONFIG_NETLINK_MMAP
1541         if (netlink_skb_is_mmaped(skb))
1542                 netlink_queue_mmaped_skb(sk, skb);
1543         else if (netlink_rx_is_mmaped(sk))
1544                 netlink_ring_set_copied(sk, skb);
1545         else
1546 #endif /* CONFIG_NETLINK_MMAP */
1547                 skb_queue_tail(&sk->sk_receive_queue, skb);
1548         sk->sk_data_ready(sk, len);
1549         return len;
1550 }
1551 
1552 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1553 {
1554         int len = __netlink_sendskb(sk, skb);
1555 
1556         sock_put(sk);
1557         return len;
1558 }
1559 
1560 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
1561 {
1562         kfree_skb(skb);
1563         sock_put(sk);
1564 }
1565 
1566 static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
1567 {
1568         int delta;
1569 
1570         WARN_ON(skb->sk != NULL);
1571         if (netlink_skb_is_mmaped(skb))
1572                 return skb;
1573 
1574         delta = skb->end - skb->tail;
1575         if (delta * 2 < skb->truesize)
1576                 return skb;
1577 
1578         if (skb_shared(skb)) {
1579                 struct sk_buff *nskb = skb_clone(skb, allocation);
1580                 if (!nskb)
1581                         return skb;
1582                 consume_skb(skb);
1583                 skb = nskb;
1584         }
1585 
1586         if (!pskb_expand_head(skb, 0, -delta, allocation))
1587                 skb->truesize -= delta;
1588 
1589         return skb;
1590 }
1591 
1592 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
1593                                   struct sock *ssk)
1594 {
1595         int ret;
1596         struct netlink_sock *nlk = nlk_sk(sk);
1597 
1598         ret = -ECONNREFUSED;
1599         if (nlk->netlink_rcv != NULL) {
1600                 ret = skb->len;
1601                 netlink_skb_set_owner_r(skb, sk);
1602                 NETLINK_CB(skb).sk = ssk;
1603                 nlk->netlink_rcv(skb);
1604                 consume_skb(skb);
1605         } else {
1606                 kfree_skb(skb);
1607         }
1608         sock_put(sk);
1609         return ret;
1610 }
1611 
1612 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
1613                     u32 portid, int nonblock)
1614 {
1615         struct sock *sk;
1616         int err;
1617         long timeo;
1618 
1619         skb = netlink_trim(skb, gfp_any());
1620 
1621         timeo = sock_sndtimeo(ssk, nonblock);
1622 retry:
1623         sk = netlink_getsockbyportid(ssk, portid);
1624         if (IS_ERR(sk)) {
1625                 kfree_skb(skb);
1626                 return PTR_ERR(sk);
1627         }
1628         if (netlink_is_kernel(sk))
1629                 return netlink_unicast_kernel(sk, skb, ssk);
1630 
1631         if (sk_filter(sk, skb)) {
1632                 err = skb->len;
1633                 kfree_skb(skb);
1634                 sock_put(sk);
1635                 return err;
1636         }
1637 
1638         err = netlink_attachskb(sk, skb, &timeo, ssk);
1639         if (err == 1)
1640                 goto retry;
1641         if (err)
1642                 return err;
1643 
1644         return netlink_sendskb(sk, skb);
1645 }
1646 EXPORT_SYMBOL(netlink_unicast);
1647 
1648 struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size,
1649                                   u32 dst_portid, gfp_t gfp_mask)
1650 {
1651 #ifdef CONFIG_NETLINK_MMAP
1652         struct sock *sk = NULL;
1653         struct sk_buff *skb;
1654         struct netlink_ring *ring;
1655         struct nl_mmap_hdr *hdr;
1656         unsigned int maxlen;
1657 
1658         sk = netlink_getsockbyportid(ssk, dst_portid);
1659         if (IS_ERR(sk))
1660                 goto out;
1661 
1662         ring = &nlk_sk(sk)->rx_ring;
1663         /* fast-path without atomic ops for common case: non-mmaped receiver */
1664         if (ring->pg_vec == NULL)
1665                 goto out_put;
1666 
1667         skb = alloc_skb_head(gfp_mask);
1668         if (skb == NULL)
1669                 goto err1;
1670 
1671         spin_lock_bh(&sk->sk_receive_queue.lock);
1672         /* check again under lock */
1673         if (ring->pg_vec == NULL)
1674                 goto out_free;
1675 
1676         maxlen = ring->frame_size - NL_MMAP_HDRLEN;
1677         if (maxlen < size)
1678                 goto out_free;
1679 
1680         netlink_forward_ring(ring);
1681         hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
1682         if (hdr == NULL)
1683                 goto err2;
1684         netlink_ring_setup_skb(skb, sk, ring, hdr);
1685         netlink_set_status(hdr, NL_MMAP_STATUS_RESERVED);
1686         atomic_inc(&ring->pending);
1687         netlink_increment_head(ring);
1688 
1689         spin_unlock_bh(&sk->sk_receive_queue.lock);
1690         return skb;
1691 
1692 err2:
1693         kfree_skb(skb);
1694         spin_unlock_bh(&sk->sk_receive_queue.lock);
1695         netlink_overrun(sk);
1696 err1:
1697         sock_put(sk);
1698         return NULL;
1699 
1700 out_free:
1701         kfree_skb(skb);
1702         spin_unlock_bh(&sk->sk_receive_queue.lock);
1703 out_put:
1704         sock_put(sk);
1705 out:
1706 #endif
1707         return alloc_skb(size, gfp_mask);
1708 }
1709 EXPORT_SYMBOL_GPL(netlink_alloc_skb);
1710 
1711 int netlink_has_listeners(struct sock *sk, unsigned int group)
1712 {
1713         int res = 0;
1714         struct listeners *listeners;
1715 
1716         BUG_ON(!netlink_is_kernel(sk));
1717 
1718         rcu_read_lock();
1719         listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
1720 
1721         if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
1722                 res = test_bit(group - 1, listeners->masks);
1723 
1724         rcu_read_unlock();
1725 
1726         return res;
1727 }
1728 EXPORT_SYMBOL_GPL(netlink_has_listeners);
1729 
1730 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
1731 {
1732         struct netlink_sock *nlk = nlk_sk(sk);
1733 
1734         if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
1735             !test_bit(NETLINK_CONGESTED, &nlk->state)) {
1736                 netlink_skb_set_owner_r(skb, sk);
1737                 __netlink_sendskb(sk, skb);
1738                 return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
1739         }
1740         return -1;
1741 }
1742 
1743 struct netlink_broadcast_data {
1744         struct sock *exclude_sk;
1745         struct net *net;
1746         u32 portid;
1747         u32 group;
1748         int failure;
1749         int delivery_failure;
1750         int congested;
1751         int delivered;
1752         gfp_t allocation;
1753         struct sk_buff *skb, *skb2;
1754         int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
1755         void *tx_data;
1756 };
1757 
1758 static int do_one_broadcast(struct sock *sk,
1759                                    struct netlink_broadcast_data *p)
1760 {
1761         struct netlink_sock *nlk = nlk_sk(sk);
1762         int val;
1763 
1764         if (p->exclude_sk == sk)
1765                 goto out;
1766 
1767         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1768             !test_bit(p->group - 1, nlk->groups))
1769                 goto out;
1770 
1771         if (!net_eq(sock_net(sk), p->net))
1772                 goto out;
1773 
1774         if (p->failure) {
1775                 netlink_overrun(sk);
1776                 goto out;
1777         }
1778 
1779         sock_hold(sk);
1780         if (p->skb2 == NULL) {
1781                 if (skb_shared(p->skb)) {
1782                         p->skb2 = skb_clone(p->skb, p->allocation);
1783                 } else {
1784                         p->skb2 = skb_get(p->skb);
1785                         /*
1786                          * skb ownership may have been set when
1787                          * delivered to a previous socket.
1788                          */
1789                         skb_orphan(p->skb2);
1790                 }
1791         }
1792         if (p->skb2 == NULL) {
1793                 netlink_overrun(sk);
1794                 /* Clone failed. Notify ALL listeners. */
1795                 p->failure = 1;
1796                 if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
1797                         p->delivery_failure = 1;
1798         } else if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
1799                 kfree_skb(p->skb2);
1800                 p->skb2 = NULL;
1801         } else if (sk_filter(sk, p->skb2)) {
1802                 kfree_skb(p->skb2);
1803                 p->skb2 = NULL;
1804         } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {
1805                 netlink_overrun(sk);
1806                 if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
1807                         p->delivery_failure = 1;
1808         } else {
1809                 p->congested |= val;
1810                 p->delivered = 1;
1811                 p->skb2 = NULL;
1812         }
1813         sock_put(sk);
1814 
1815 out:
1816         return 0;
1817 }
1818 
1819 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 portid,
1820         u32 group, gfp_t allocation,
1821         int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
1822         void *filter_data)
1823 {
1824         struct net *net = sock_net(ssk);
1825         struct netlink_broadcast_data info;
1826         struct sock *sk;
1827 
1828         skb = netlink_trim(skb, allocation);
1829 
1830         info.exclude_sk = ssk;
1831         info.net = net;
1832         info.portid = portid;
1833         info.group = group;
1834         info.failure = 0;
1835         info.delivery_failure = 0;
1836         info.congested = 0;
1837         info.delivered = 0;
1838         info.allocation = allocation;
1839         info.skb = skb;
1840         info.skb2 = NULL;
1841         info.tx_filter = filter;
1842         info.tx_data = filter_data;
1843 
1844         /* While we sleep in clone, do not allow to change socket list */
1845 
1846         netlink_lock_table();
1847 
1848         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1849                 do_one_broadcast(sk, &info);
1850 
1851         consume_skb(skb);
1852 
1853         netlink_unlock_table();
1854 
1855         if (info.delivery_failure) {
1856                 kfree_skb(info.skb2);
1857                 return -ENOBUFS;
1858         }
1859         consume_skb(info.skb2);
1860 
1861         if (info.delivered) {
1862                 if (info.congested && (allocation & __GFP_WAIT))
1863                         yield();
1864                 return 0;
1865         }
1866         return -ESRCH;
1867 }
1868 EXPORT_SYMBOL(netlink_broadcast_filtered);
1869 
1870 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
1871                       u32 group, gfp_t allocation)
1872 {
1873         return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
1874                 NULL, NULL);
1875 }
1876 EXPORT_SYMBOL(netlink_broadcast);
1877 
1878 struct netlink_set_err_data {
1879         struct sock *exclude_sk;
1880         u32 portid;
1881         u32 group;
1882         int code;
1883 };
1884 
1885 static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
1886 {
1887         struct netlink_sock *nlk = nlk_sk(sk);
1888         int ret = 0;
1889 
1890         if (sk == p->exclude_sk)
1891                 goto out;
1892 
1893         if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
1894                 goto out;
1895 
1896         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1897             !test_bit(p->group - 1, nlk->groups))
1898                 goto out;
1899 
1900         if (p->code == ENOBUFS && nlk->flags & NETLINK_RECV_NO_ENOBUFS) {
1901                 ret = 1;
1902                 goto out;
1903         }
1904 
1905         sk->sk_err = p->code;
1906         sk->sk_error_report(sk);
1907 out:
1908         return ret;
1909 }
1910 
1911 /**
1912  * netlink_set_err - report error to broadcast listeners
1913  * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
1914  * @portid: the PORTID of a process that we want to skip (if any)
1915  * @groups: the broadcast group that will notice the error
1916  * @code: error code, must be negative (as usual in kernelspace)
1917  *
1918  * This function returns the number of broadcast listeners that have set the
1919  * NETLINK_RECV_NO_ENOBUFS socket option.
1920  */
1921 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
1922 {
1923         struct netlink_set_err_data info;
1924         struct sock *sk;
1925         int ret = 0;
1926 
1927         info.exclude_sk = ssk;
1928         info.portid = portid;
1929         info.group = group;
1930         /* sk->sk_err wants a positive error value */
1931         info.code = -code;
1932 
1933         read_lock(&nl_table_lock);
1934 
1935         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1936                 ret += do_one_set_err(sk, &info);
1937 
1938         read_unlock(&nl_table_lock);
1939         return ret;
1940 }
1941 EXPORT_SYMBOL(netlink_set_err);
1942 
1943 /* must be called with netlink table grabbed */
1944 static void netlink_update_socket_mc(struct netlink_sock *nlk,
1945                                      unsigned int group,
1946                                      int is_new)
1947 {
1948         int old, new = !!is_new, subscriptions;
1949 
1950         old = test_bit(group - 1, nlk->groups);
1951         subscriptions = nlk->subscriptions - old + new;
1952         if (new)
1953                 __set_bit(group - 1, nlk->groups);
1954         else
1955                 __clear_bit(group - 1, nlk->groups);
1956         netlink_update_subscriptions(&nlk->sk, subscriptions);
1957         netlink_update_listeners(&nlk->sk);
1958 }
1959 
1960 static int netlink_setsockopt(struct socket *sock, int level, int optname,
1961                               char __user *optval, unsigned int optlen)
1962 {
1963         struct sock *sk = sock->sk;
1964         struct netlink_sock *nlk = nlk_sk(sk);
1965         unsigned int val = 0;
1966         int err;
1967 
1968         if (level != SOL_NETLINK)
1969                 return -ENOPROTOOPT;
1970 
1971         if (optname != NETLINK_RX_RING && optname != NETLINK_TX_RING &&
1972             optlen >= sizeof(int) &&
1973             get_user(val, (unsigned int __user *)optval))
1974                 return -EFAULT;
1975 
1976         switch (optname) {
1977         case NETLINK_PKTINFO:
1978                 if (val)
1979                         nlk->flags |= NETLINK_RECV_PKTINFO;
1980                 else
1981                         nlk->flags &= ~NETLINK_RECV_PKTINFO;
1982                 err = 0;
1983                 break;
1984         case NETLINK_ADD_MEMBERSHIP:
1985         case NETLINK_DROP_MEMBERSHIP: {
1986                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
1987                         return -EPERM;
1988                 err = netlink_realloc_groups(sk);
1989                 if (err)
1990                         return err;
1991                 if (!val || val - 1 >= nlk->ngroups)
1992                         return -EINVAL;
1993                 netlink_table_grab();
1994                 netlink_update_socket_mc(nlk, val,
1995                                          optname == NETLINK_ADD_MEMBERSHIP);
1996                 netlink_table_ungrab();
1997 
1998                 if (nlk->netlink_bind)
1999                         nlk->netlink_bind(val);
2000 
2001                 err = 0;
2002                 break;
2003         }
2004         case NETLINK_BROADCAST_ERROR:
2005                 if (val)
2006                         nlk->flags |= NETLINK_BROADCAST_SEND_ERROR;
2007                 else
2008                         nlk->flags &= ~NETLINK_BROADCAST_SEND_ERROR;
2009                 err = 0;
2010                 break;
2011         case NETLINK_NO_ENOBUFS:
2012                 if (val) {
2013                         nlk->flags |= NETLINK_RECV_NO_ENOBUFS;
2014                         clear_bit(NETLINK_CONGESTED, &nlk->state);
2015                         wake_up_interruptible(&nlk->wait);
2016                 } else {
2017                         nlk->flags &= ~NETLINK_RECV_NO_ENOBUFS;
2018                 }
2019                 err = 0;
2020                 break;
2021 #ifdef CONFIG_NETLINK_MMAP
2022         case NETLINK_RX_RING:
2023         case NETLINK_TX_RING: {
2024                 struct nl_mmap_req req;
2025 
2026                 /* Rings might consume more memory than queue limits, require
2027                  * CAP_NET_ADMIN.
2028                  */
2029                 if (!capable(CAP_NET_ADMIN))
2030                         return -EPERM;
2031                 if (optlen < sizeof(req))
2032                         return -EINVAL;
2033                 if (copy_from_user(&req, optval, sizeof(req)))
2034                         return -EFAULT;
2035                 err = netlink_set_ring(sk, &req,
2036                                        optname == NETLINK_TX_RING);
2037                 break;
2038         }
2039 #endif /* CONFIG_NETLINK_MMAP */
2040         default:
2041                 err = -ENOPROTOOPT;
2042         }
2043         return err;
2044 }
2045 
2046 static int netlink_getsockopt(struct socket *sock, int level, int optname,
2047                               char __user *optval, int __user *optlen)
2048 {
2049         struct sock *sk = sock->sk;
2050         struct netlink_sock *nlk = nlk_sk(sk);
2051         int len, val, err;
2052 
2053         if (level != SOL_NETLINK)
2054                 return -ENOPROTOOPT;
2055 
2056         if (get_user(len, optlen))
2057                 return -EFAULT;
2058         if (len < 0)
2059                 return -EINVAL;
2060 
2061         switch (optname) {
2062         case NETLINK_PKTINFO:
2063                 if (len < sizeof(int))
2064                         return -EINVAL;
2065                 len = sizeof(int);
2066                 val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0;
2067                 if (put_user(len, optlen) ||
2068                     put_user(val, optval))
2069                         return -EFAULT;
2070                 err = 0;
2071                 break;
2072         case NETLINK_BROADCAST_ERROR:
2073                 if (len < sizeof(int))
2074                         return -EINVAL;
2075                 len = sizeof(int);
2076                 val = nlk->flags & NETLINK_BROADCAST_SEND_ERROR ? 1 : 0;
2077                 if (put_user(len, optlen) ||
2078                     put_user(val, optval))
2079                         return -EFAULT;
2080                 err = 0;
2081                 break;
2082         case NETLINK_NO_ENOBUFS:
2083                 if (len < sizeof(int))
2084                         return -EINVAL;
2085                 len = sizeof(int);
2086                 val = nlk->flags & NETLINK_RECV_NO_ENOBUFS ? 1 : 0;
2087                 if (put_user(len, optlen) ||
2088                     put_user(val, optval))
2089                         return -EFAULT;
2090                 err = 0;
2091                 break;
2092         default:
2093                 err = -ENOPROTOOPT;
2094         }
2095         return err;
2096 }
2097 
2098 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
2099 {
2100         struct nl_pktinfo info;
2101 
2102         info.group = NETLINK_CB(skb).dst_group;
2103         put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
2104 }
2105 
2106 static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
2107                            struct msghdr *msg, size_t len)
2108 {
2109         struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
2110         struct sock *sk = sock->sk;
2111         struct netlink_sock *nlk = nlk_sk(sk);
2112         struct sockaddr_nl *addr = msg->msg_name;
2113         u32 dst_portid;
2114         u32 dst_group;
2115         struct sk_buff *skb;
2116         int err;
2117         struct scm_cookie scm;
2118         u32 netlink_skb_flags = 0;
2119 
2120         if (msg->msg_flags&MSG_OOB)
2121                 return -EOPNOTSUPP;
2122 
2123         if (NULL == siocb->scm)
2124                 siocb->scm = &scm;
2125 
2126         err = scm_send(sock, msg, siocb->scm, true);
2127         if (err < 0)
2128                 return err;
2129 
2130         if (msg->msg_namelen) {
2131                 err = -EINVAL;
2132                 if (addr->nl_family != AF_NETLINK)
2133                         goto out;
2134                 dst_portid = addr->nl_pid;
2135                 dst_group = ffs(addr->nl_groups);
2136                 err =  -EPERM;
2137                 if ((dst_group || dst_portid) &&
2138                     !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
2139                         goto out;
2140                 netlink_skb_flags |= NETLINK_SKB_DST;
2141         } else {
2142                 dst_portid = nlk->dst_portid;
2143                 dst_group = nlk->dst_group;
2144         }
2145 
2146         if (!nlk->portid) {
2147                 err = netlink_autobind(sock);
2148                 if (err)
2149                         goto out;
2150         }
2151 
2152         if (netlink_tx_is_mmaped(sk) &&
2153             msg->msg_iov->iov_base == NULL) {
2154                 err = netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group,
2155                                            siocb);
2156                 goto out;
2157         }
2158 
2159         err = -EMSGSIZE;
2160         if (len > sk->sk_sndbuf - 32)
2161                 goto out;
2162         err = -ENOBUFS;
2163         skb = alloc_skb(len, GFP_KERNEL);
2164         if (skb == NULL)
2165                 goto out;
2166 
2167         NETLINK_CB(skb).portid  = nlk->portid;
2168         NETLINK_CB(skb).dst_group = dst_group;
2169         NETLINK_CB(skb).creds   = siocb->scm->creds;
2170         NETLINK_CB(skb).flags   = netlink_skb_flags;
2171 
2172         err = -EFAULT;
2173         if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
2174                 kfree_skb(skb);
2175                 goto out;
2176         }
2177 
2178         err = security_netlink_send(sk, skb);
2179         if (err) {
2180                 kfree_skb(skb);
2181                 goto out;
2182         }
2183 
2184         if (dst_group) {
2185                 atomic_inc(&skb->users);
2186                 netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
2187         }
2188         err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT);
2189 
2190 out:
2191         scm_destroy(siocb->scm);
2192         return err;
2193 }
2194 
2195 static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
2196                            struct msghdr *msg, size_t len,
2197                            int flags)
2198 {
2199         struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
2200         struct scm_cookie scm;
2201         struct sock *sk = sock->sk;
2202         struct netlink_sock *nlk = nlk_sk(sk);
2203         int noblock = flags&MSG_DONTWAIT;
2204         size_t copied;
2205         struct sk_buff *skb, *data_skb;
2206         int err, ret;
2207 
2208         if (flags&MSG_OOB)
2209                 return -EOPNOTSUPP;
2210 
2211         copied = 0;
2212 
2213         skb = skb_recv_datagram(sk, flags, noblock, &err);
2214         if (skb == NULL)
2215                 goto out;
2216 
2217         data_skb = skb;
2218 
2219 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES
2220         if (unlikely(skb_shinfo(skb)->frag_list)) {
2221                 /*
2222                  * If this skb has a frag_list, then here that means that we
2223                  * will have to use the frag_list skb's data for compat tasks
2224                  * and the regular skb's data for normal (non-compat) tasks.
2225                  *
2226                  * If we need to send the compat skb, assign it to the
2227                  * 'data_skb' variable so that it will be used below for data
2228                  * copying. We keep 'skb' for everything else, including
2229                  * freeing both later.
2230                  */
2231                 if (flags & MSG_CMSG_COMPAT)
2232                         data_skb = skb_shinfo(skb)->frag_list;
2233         }
2234 #endif
2235 
2236         copied = data_skb->len;
2237         if (len < copied) {
2238                 msg->msg_flags |= MSG_TRUNC;
2239                 copied = len;
2240         }
2241 
2242         skb_reset_transport_header(data_skb);
2243         err = skb_copy_datagram_iovec(data_skb, 0, msg->msg_iov, copied);
2244 
2245         if (msg->msg_name) {
2246                 struct sockaddr_nl *addr = (struct sockaddr_nl *)msg->msg_name;
2247                 addr->nl_family = AF_NETLINK;
2248                 addr->nl_pad    = 0;
2249                 addr->nl_pid    = NETLINK_CB(skb).portid;
2250                 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
2251                 msg->msg_namelen = sizeof(*addr);
2252         }
2253 
2254         if (nlk->flags & NETLINK_RECV_PKTINFO)
2255                 netlink_cmsg_recv_pktinfo(msg, skb);
2256 
2257         if (NULL == siocb->scm) {
2258                 memset(&scm, 0, sizeof(scm));
2259                 siocb->scm = &scm;
2260         }
2261         siocb->scm->creds = *NETLINK_CREDS(skb);
2262         if (flags & MSG_TRUNC)
2263                 copied = data_skb->len;
2264 
2265         skb_free_datagram(sk, skb);
2266 
2267         if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
2268                 ret = netlink_dump(sk);
2269                 if (ret) {
2270                         sk->sk_err = -ret;
2271                         sk->sk_error_report(sk);
2272                 }
2273         }
2274 
2275         scm_recv(sock, msg, siocb->scm, flags);
2276 out:
2277         netlink_rcv_wake(sk);
2278         return err ? : copied;
2279 }
2280 
2281 static void netlink_data_ready(struct sock *sk, int len)
2282 {
2283         BUG();
2284 }
2285 
2286 /*
2287  *      We export these functions to other modules. They provide a
2288  *      complete set of kernel non-blocking support for message
2289  *      queueing.
2290  */
2291 
2292 struct sock *
2293 __netlink_kernel_create(struct net *net, int unit, struct module *module,
2294                         struct netlink_kernel_cfg *cfg)
2295 {
2296         struct socket *sock;
2297         struct sock *sk;
2298         struct netlink_sock *nlk;
2299         struct listeners *listeners = NULL;
2300         struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL;
2301         unsigned int groups;
2302 
2303         BUG_ON(!nl_table);
2304 
2305         if (unit < 0 || unit >= MAX_LINKS)
2306                 return NULL;
2307 
2308         if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
2309                 return NULL;
2310 
2311         /*
2312          * We have to just have a reference on the net from sk, but don't
2313          * get_net it. Besides, we cannot get and then put the net here.
2314          * So we create one inside init_net and the move it to net.
2315          */
2316 
2317         if (__netlink_create(&init_net, sock, cb_mutex, unit) < 0)
2318                 goto out_sock_release_nosk;
2319 
2320         sk = sock->sk;
2321         sk_change_net(sk, net);
2322 
2323         if (!cfg || cfg->groups < 32)
2324                 groups = 32;
2325         else
2326                 groups = cfg->groups;
2327 
2328         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2329         if (!listeners)
2330                 goto out_sock_release;
2331 
2332         sk->sk_data_ready = netlink_data_ready;
2333         if (cfg && cfg->input)
2334                 nlk_sk(sk)->netlink_rcv = cfg->input;
2335 
2336         if (netlink_insert(sk, net, 0))
2337                 goto out_sock_release;
2338 
2339         nlk = nlk_sk(sk);
2340         nlk->flags |= NETLINK_KERNEL_SOCKET;
2341 
2342         netlink_table_grab();
2343         if (!nl_table[unit].registered) {
2344                 nl_table[unit].groups = groups;
2345                 rcu_assign_pointer(nl_table[unit].listeners, listeners);
2346                 nl_table[unit].cb_mutex = cb_mutex;
2347                 nl_table[unit].module = module;
2348                 if (cfg) {
2349                         nl_table[unit].bind = cfg->bind;
2350                         nl_table[unit].flags = cfg->flags;
2351                 }
2352                 nl_table[unit].registered = 1;
2353         } else {
2354                 kfree(listeners);
2355                 nl_table[unit].registered++;
2356         }
2357         netlink_table_ungrab();
2358         return sk;
2359 
2360 out_sock_release:
2361         kfree(listeners);
2362         netlink_kernel_release(sk);
2363         return NULL;
2364 
2365 out_sock_release_nosk:
2366         sock_release(sock);
2367         return NULL;
2368 }
2369 EXPORT_SYMBOL(__netlink_kernel_create);
2370 
2371 void
2372 netlink_kernel_release(struct sock *sk)
2373 {
2374         sk_release_kernel(sk);
2375 }
2376 EXPORT_SYMBOL(netlink_kernel_release);
2377 
2378 int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
2379 {
2380         struct listeners *new, *old;
2381         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
2382 
2383         if (groups < 32)
2384                 groups = 32;
2385 
2386         if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
2387                 new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
2388                 if (!new)
2389                         return -ENOMEM;
2390                 old = nl_deref_protected(tbl->listeners);
2391                 memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
2392                 rcu_assign_pointer(tbl->listeners, new);
2393 
2394                 kfree_rcu(old, rcu);
2395         }
2396         tbl->groups = groups;
2397 
2398         return 0;
2399 }
2400 
2401 /**
2402  * netlink_change_ngroups - change number of multicast groups
2403  *
2404  * This changes the number of multicast groups that are available
2405  * on a certain netlink family. Note that it is not possible to
2406  * change the number of groups to below 32. Also note that it does
2407  * not implicitly call netlink_clear_multicast_users() when the
2408  * number of groups is reduced.
2409  *
2410  * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
2411  * @groups: The new number of groups.
2412  */
2413 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
2414 {
2415         int err;
2416 
2417         netlink_table_grab();
2418         err = __netlink_change_ngroups(sk, groups);
2419         netlink_table_ungrab();
2420 
2421         return err;
2422 }
2423 
2424 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
2425 {
2426         struct sock *sk;
2427         struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
2428 
2429         sk_for_each_bound(sk, &tbl->mc_list)
2430                 netlink_update_socket_mc(nlk_sk(sk), group, 0);
2431 }
2432 
2433 /**
2434  * netlink_clear_multicast_users - kick off multicast listeners
2435  *
2436  * This function removes all listeners from the given group.
2437  * @ksk: The kernel netlink socket, as returned by
2438  *      netlink_kernel_create().
2439  * @group: The multicast group to clear.
2440  */
2441 void netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
2442 {
2443         netlink_table_grab();
2444         __netlink_clear_multicast_users(ksk, group);
2445         netlink_table_ungrab();
2446 }
2447 
2448 struct nlmsghdr *
2449 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
2450 {
2451         struct nlmsghdr *nlh;
2452         int size = nlmsg_msg_size(len);
2453 
2454         nlh = (struct nlmsghdr*)skb_put(skb, NLMSG_ALIGN(size));
2455         nlh->nlmsg_type = type;
2456         nlh->nlmsg_len = size;
2457         nlh->nlmsg_flags = flags;
2458         nlh->nlmsg_pid = portid;
2459         nlh->nlmsg_seq = seq;
2460         if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
2461                 memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
2462         return nlh;
2463 }
2464 EXPORT_SYMBOL(__nlmsg_put);
2465 
2466 /*
2467  * It looks a bit ugly.
2468  * It would be better to create kernel thread.
2469  */
2470 
2471 static int netlink_dump(struct sock *sk)
2472 {
2473         struct netlink_sock *nlk = nlk_sk(sk);
2474         struct netlink_callback *cb;
2475         struct sk_buff *skb = NULL;
2476         struct nlmsghdr *nlh;
2477         int len, err = -ENOBUFS;
2478         int alloc_size;
2479 
2480         mutex_lock(nlk->cb_mutex);
2481 
2482         cb = nlk->cb;
2483         if (cb == NULL) {
2484                 err = -EINVAL;
2485                 goto errout_skb;
2486         }
2487 
2488         alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
2489 
2490         if (!netlink_rx_is_mmaped(sk) &&
2491             atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
2492                 goto errout_skb;
2493         skb = netlink_alloc_skb(sk, alloc_size, nlk->portid, GFP_KERNEL);
2494         if (!skb)
2495                 goto errout_skb;
2496         netlink_skb_set_owner_r(skb, sk);
2497 
2498         len = cb->dump(skb, cb);
2499 
2500         if (len > 0) {
2501                 mutex_unlock(nlk->cb_mutex);
2502 
2503                 if (sk_filter(sk, skb))
2504                         kfree_skb(skb);
2505                 else
2506                         __netlink_sendskb(sk, skb);
2507                 return 0;
2508         }
2509 
2510         nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
2511         if (!nlh)
2512                 goto errout_skb;
2513 
2514         nl_dump_check_consistent(cb, nlh);
2515 
2516         memcpy(nlmsg_data(nlh), &len, sizeof(len));
2517 
2518         if (sk_filter(sk, skb))
2519                 kfree_skb(skb);
2520         else
2521                 __netlink_sendskb(sk, skb);
2522 
2523         if (cb->done)
2524                 cb->done(cb);
2525         nlk->cb = NULL;
2526         mutex_unlock(nlk->cb_mutex);
2527 
2528         module_put(cb->module);
2529         netlink_consume_callback(cb);
2530         return 0;
2531 
2532 errout_skb:
2533         mutex_unlock(nlk->cb_mutex);
2534         kfree_skb(skb);
2535         return err;
2536 }
2537 
2538 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
2539                          const struct nlmsghdr *nlh,
2540                          struct netlink_dump_control *control)
2541 {
2542         struct netlink_callback *cb;
2543         struct sock *sk;
2544         struct netlink_sock *nlk;
2545         int ret;
2546 
2547         cb = kzalloc(sizeof(*cb), GFP_KERNEL);
2548         if (cb == NULL)
2549                 return -ENOBUFS;
2550 
2551         /* Memory mapped dump requests need to be copied to avoid looping
2552          * on the pending state in netlink_mmap_sendmsg() while the CB hold
2553          * a reference to the skb.
2554          */
2555         if (netlink_skb_is_mmaped(skb)) {
2556                 skb = skb_copy(skb, GFP_KERNEL);
2557                 if (skb == NULL) {
2558                         kfree(cb);
2559                         return -ENOBUFS;
2560                 }
2561         } else
2562                 atomic_inc(&skb->users);
2563 
2564         cb->dump = control->dump;
2565         cb->done = control->done;
2566         cb->nlh = nlh;
2567         cb->data = control->data;
2568         cb->module = control->module;
2569         cb->min_dump_alloc = control->min_dump_alloc;
2570         cb->skb = skb;
2571 
2572         sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
2573         if (sk == NULL) {
2574                 netlink_destroy_callback(cb);
2575                 return -ECONNREFUSED;
2576         }
2577         nlk = nlk_sk(sk);
2578 
2579         mutex_lock(nlk->cb_mutex);
2580         /* A dump is in progress... */
2581         if (nlk->cb) {
2582                 mutex_unlock(nlk->cb_mutex);
2583                 netlink_destroy_callback(cb);
2584                 ret = -EBUSY;
2585                 goto out;
2586         }
2587         /* add reference of module which cb->dump belongs to */
2588         if (!try_module_get(cb->module)) {
2589                 mutex_unlock(nlk->cb_mutex);
2590                 netlink_destroy_callback(cb);
2591                 ret = -EPROTONOSUPPORT;
2592                 goto out;
2593         }
2594 
2595         nlk->cb = cb;
2596         mutex_unlock(nlk->cb_mutex);
2597 
2598         ret = netlink_dump(sk);
2599 out:
2600         sock_put(sk);
2601 
2602         if (ret)
2603                 return ret;
2604 
2605         /* We successfully started a dump, by returning -EINTR we
2606          * signal not to send ACK even if it was requested.
2607          */
2608         return -EINTR;
2609 }
2610 EXPORT_SYMBOL(__netlink_dump_start);
2611 
2612 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
2613 {
2614         struct sk_buff *skb;
2615         struct nlmsghdr *rep;
2616         struct nlmsgerr *errmsg;
2617         size_t payload = sizeof(*errmsg);
2618 
2619         /* error messages get the original request appened */
2620         if (err)
2621                 payload += nlmsg_len(nlh);
2622 
2623         skb = netlink_alloc_skb(in_skb->sk, nlmsg_total_size(payload),
2624                                 NETLINK_CB(in_skb).portid, GFP_KERNEL);
2625         if (!skb) {
2626                 struct sock *sk;
2627 
2628                 sk = netlink_lookup(sock_net(in_skb->sk),
2629                                     in_skb->sk->sk_protocol,
2630                                     NETLINK_CB(in_skb).portid);
2631                 if (sk) {
2632                         sk->sk_err = ENOBUFS;
2633                         sk->sk_error_report(sk);
2634                         sock_put(sk);
2635                 }
2636                 return;
2637         }
2638 
2639         rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2640                           NLMSG_ERROR, payload, 0);
2641         errmsg = nlmsg_data(rep);
2642         errmsg->error = err;
2643         memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh));
2644         netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);
2645 }
2646 EXPORT_SYMBOL(netlink_ack);
2647 
2648 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
2649                                                      struct nlmsghdr *))
2650 {
2651         struct nlmsghdr *nlh;
2652         int err;
2653 
2654         while (skb->len >= nlmsg_total_size(0)) {
2655                 int msglen;
2656 
2657                 nlh = nlmsg_hdr(skb);
2658                 err = 0;
2659 
2660                 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
2661                         return 0;
2662 
2663                 /* Only requests are handled by the kernel */
2664                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
2665                         goto ack;
2666 
2667                 /* Skip control messages */
2668                 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
2669                         goto ack;
2670 
2671                 err = cb(skb, nlh);
2672                 if (err == -EINTR)
2673                         goto skip;
2674 
2675 ack:
2676                 if (nlh->nlmsg_flags & NLM_F_ACK || err)
2677                         netlink_ack(skb, nlh, err);
2678 
2679 skip:
2680                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
2681                 if (msglen > skb->len)
2682                         msglen = skb->len;
2683                 skb_pull(skb, msglen);
2684         }
2685 
2686         return 0;
2687 }
2688 EXPORT_SYMBOL(netlink_rcv_skb);
2689 
2690 /**
2691  * nlmsg_notify - send a notification netlink message
2692  * @sk: netlink socket to use
2693  * @skb: notification message
2694  * @portid: destination netlink portid for reports or 0
2695  * @group: destination multicast group or 0
2696  * @report: 1 to report back, 0 to disable
2697  * @flags: allocation flags
2698  */
2699 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
2700                  unsigned int group, int report, gfp_t flags)
2701 {
2702         int err = 0;
2703 
2704         if (group) {
2705                 int exclude_portid = 0;
2706 
2707                 if (report) {
2708                         atomic_inc(&skb->users);
2709                         exclude_portid = portid;
2710                 }
2711 
2712                 /* errors reported via destination sk->sk_err, but propagate
2713                  * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
2714                 err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
2715         }
2716 
2717         if (report) {
2718                 int err2;
2719 
2720                 err2 = nlmsg_unicast(sk, skb, portid);
2721                 if (!err || err == -ESRCH)
2722                         err = err2;
2723         }
2724 
2725         return err;
2726 }
2727 EXPORT_SYMBOL(nlmsg_notify);
2728 
2729 #ifdef CONFIG_PROC_FS
2730 struct nl_seq_iter {
2731         struct seq_net_private p;
2732         int link;
2733         int hash_idx;
2734 };
2735 
2736 static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos)
2737 {
2738         struct nl_seq_iter *iter = seq->private;
2739         int i, j;
2740         struct sock *s;
2741         loff_t off = 0;
2742 
2743         for (i = 0; i < MAX_LINKS; i++) {
2744                 struct nl_portid_hash *hash = &nl_table[i].hash;
2745 
2746                 for (j = 0; j <= hash->mask; j++) {
2747                         sk_for_each(s, &hash->table[j]) {
2748                                 if (sock_net(s) != seq_file_net(seq))
2749                                         continue;
2750                                 if (off == pos) {
2751                                         iter->link = i;
2752                                         iter->hash_idx = j;
2753                                         return s;
2754                                 }
2755                                 ++off;
2756                         }
2757                 }
2758         }
2759         return NULL;
2760 }
2761 
2762 static void *netlink_seq_start(struct seq_file *seq, loff_t *pos)
2763         __acquires(nl_table_lock)
2764 {
2765         read_lock(&nl_table_lock);
2766         return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2767 }
2768 
2769 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2770 {
2771         struct sock *s;
2772         struct nl_seq_iter *iter;
2773         int i, j;
2774 
2775         ++*pos;
2776 
2777         if (v == SEQ_START_TOKEN)
2778                 return netlink_seq_socket_idx(seq, 0);
2779 
2780         iter = seq->private;
2781         s = v;
2782         do {
2783                 s = sk_next(s);
2784         } while (s && sock_net(s) != seq_file_net(seq));
2785         if (s)
2786                 return s;
2787 
2788         i = iter->link;
2789         j = iter->hash_idx + 1;
2790 
2791         do {
2792                 struct nl_portid_hash *hash = &nl_table[i].hash;
2793 
2794                 for (; j <= hash->mask; j++) {
2795                         s = sk_head(&hash->table[j]);
2796                         while (s && sock_net(s) != seq_file_net(seq))
2797                                 s = sk_next(s);
2798                         if (s) {
2799                                 iter->link = i;
2800                                 iter->hash_idx = j;
2801                                 return s;
2802                         }
2803                 }
2804 
2805                 j = 0;
2806         } while (++i < MAX_LINKS);
2807 
2808         return NULL;
2809 }
2810 
2811 static void netlink_seq_stop(struct seq_file *seq, void *v)
2812         __releases(nl_table_lock)
2813 {
2814         read_unlock(&nl_table_lock);
2815 }
2816 
2817 
2818 static int netlink_seq_show(struct seq_file *seq, void *v)
2819 {
2820         if (v == SEQ_START_TOKEN) {
2821                 seq_puts(seq,
2822                          "sk       Eth Pid    Groups   "
2823                          "Rmem     Wmem     Dump     Locks     Drops     Inode\n");
2824         } else {
2825                 struct sock *s = v;
2826                 struct netlink_sock *nlk = nlk_sk(s);
2827 
2828                 seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %pK %-8d %-8d %-8lu\n",
2829                            s,
2830                            s->sk_protocol,
2831                            nlk->portid,
2832                            nlk->groups ? (u32)nlk->groups[0] : 0,
2833                            sk_rmem_alloc_get(s),
2834                            sk_wmem_alloc_get(s),
2835                            nlk->cb,
2836                            atomic_read(&s->sk_refcnt),
2837                            atomic_read(&s->sk_drops),
2838                            sock_i_ino(s)
2839                         );
2840 
2841         }
2842         return 0;
2843 }
2844 
2845 static const struct seq_operations netlink_seq_ops = {
2846         .start  = netlink_seq_start,
2847         .next   = netlink_seq_next,
2848         .stop   = netlink_seq_stop,
2849         .show   = netlink_seq_show,
2850 };
2851 
2852 
2853 static int netlink_seq_open(struct inode *inode, struct file *file)
2854 {
2855         return seq_open_net(inode, file, &netlink_seq_ops,
2856                                 sizeof(struct nl_seq_iter));
2857 }
2858 
2859 static const struct file_operations netlink_seq_fops = {
2860         .owner          = THIS_MODULE,
2861         .open           = netlink_seq_open,
2862         .read           = seq_read,
2863         .llseek         = seq_lseek,
2864         .release        = seq_release_net,
2865 };
2866 
2867 #endif
2868 
2869 int netlink_register_notifier(struct notifier_block *nb)
2870 {
2871         return atomic_notifier_chain_register(&netlink_chain, nb);
2872 }
2873 EXPORT_SYMBOL(netlink_register_notifier);
2874 
2875 int netlink_unregister_notifier(struct notifier_block *nb)
2876 {
2877         return atomic_notifier_chain_unregister(&netlink_chain, nb);
2878 }
2879 EXPORT_SYMBOL(netlink_unregister_notifier);
2880 
2881 static const struct proto_ops netlink_ops = {
2882         .family =       PF_NETLINK,
2883         .owner =        THIS_MODULE,
2884         .release =      netlink_release,
2885         .bind =         netlink_bind,
2886         .connect =      netlink_connect,
2887         .socketpair =   sock_no_socketpair,
2888         .accept =       sock_no_accept,
2889         .getname =      netlink_getname,
2890         .poll =         netlink_poll,
2891         .ioctl =        sock_no_ioctl,
2892         .listen =       sock_no_listen,
2893         .shutdown =     sock_no_shutdown,
2894         .setsockopt =   netlink_setsockopt,
2895         .getsockopt =   netlink_getsockopt,
2896         .sendmsg =      netlink_sendmsg,
2897         .recvmsg =      netlink_recvmsg,
2898         .mmap =         netlink_mmap,
2899         .sendpage =     sock_no_sendpage,
2900 };
2901 
2902 static const struct net_proto_family netlink_family_ops = {
2903         .family = PF_NETLINK,
2904         .create = netlink_create,
2905         .owner  = THIS_MODULE,  /* for consistency 8) */
2906 };
2907 
2908 static int __net_init netlink_net_init(struct net *net)
2909 {
2910 #ifdef CONFIG_PROC_FS
2911         if (!proc_create("netlink", 0, net->proc_net, &netlink_seq_fops))
2912                 return -ENOMEM;
2913 #endif
2914         return 0;
2915 }
2916 
2917 static void __net_exit netlink_net_exit(struct net *net)
2918 {
2919 #ifdef CONFIG_PROC_FS
2920         remove_proc_entry("netlink", net->proc_net);
2921 #endif
2922 }
2923 
2924 static void __init netlink_add_usersock_entry(void)
2925 {
2926         struct listeners *listeners;
2927         int groups = 32;
2928 
2929         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2930         if (!listeners)
2931                 panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
2932 
2933         netlink_table_grab();
2934 
2935         nl_table[NETLINK_USERSOCK].groups = groups;
2936         rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
2937         nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
2938         nl_table[NETLINK_USERSOCK].registered = 1;
2939         nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND;
2940 
2941         netlink_table_ungrab();
2942 }
2943 
2944 static struct pernet_operations __net_initdata netlink_net_ops = {
2945         .init = netlink_net_init,
2946         .exit = netlink_net_exit,
2947 };
2948 
2949 static int __init netlink_proto_init(void)
2950 {
2951         int i;
2952         unsigned long limit;
2953         unsigned int order;
2954         int err = proto_register(&netlink_proto, 0);
2955 
2956         if (err != 0)
2957                 goto out;
2958 
2959         BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
2960 
2961         nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
2962         if (!nl_table)
2963                 goto panic;
2964 
2965         if (totalram_pages >= (128 * 1024))
2966                 limit = totalram_pages >> (21 - PAGE_SHIFT);
2967         else
2968                 limit = totalram_pages >> (23 - PAGE_SHIFT);
2969 
2970         order = get_bitmask_order(limit) - 1 + PAGE_SHIFT;
2971         limit = (1UL << order) / sizeof(struct hlist_head);
2972         order = get_bitmask_order(min(limit, (unsigned long)UINT_MAX)) - 1;
2973 
2974         for (i = 0; i < MAX_LINKS; i++) {
2975                 struct nl_portid_hash *hash = &nl_table[i].hash;
2976 
2977                 hash->table = nl_portid_hash_zalloc(1 * sizeof(*hash->table));
2978                 if (!hash->table) {
2979                         while (i-- > 0)
2980                                 nl_portid_hash_free(nl_table[i].hash.table,
2981                                                  1 * sizeof(*hash->table));
2982                         kfree(nl_table);
2983                         goto panic;
2984                 }
2985                 hash->max_shift = order;
2986                 hash->shift = 0;
2987                 hash->mask = 0;
2988                 hash->rehash_time = jiffies;
2989         }
2990 
2991         netlink_add_usersock_entry();
2992 
2993         sock_register(&netlink_family_ops);
2994         register_pernet_subsys(&netlink_net_ops);
2995         /* The netlink device handler may be needed early. */
2996         rtnetlink_init();
2997 out:
2998         return err;
2999 panic:
3000         panic("netlink_init: Cannot allocate nl_table\n");
3001 }
3002 
3003 core_initcall(netlink_proto_init);
3004 

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