root/net/netlink/af_netlink.c

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DEFINITIONS

This source file includes following definitions.
  1. netlink_is_kernel
  2. netlink_group_mask
  3. netlink_to_full_skb
  4. netlink_add_tap
  5. __netlink_remove_tap
  6. netlink_remove_tap
  7. netlink_tap_init_net
  8. netlink_filter_tap
  9. __netlink_deliver_tap_skb
  10. __netlink_deliver_tap
  11. netlink_deliver_tap
  12. netlink_deliver_tap_kernel
  13. netlink_overrun
  14. netlink_rcv_wake
  15. netlink_skb_destructor
  16. netlink_skb_set_owner_r
  17. netlink_sock_destruct
  18. netlink_sock_destruct_work
  19. netlink_table_grab
  20. netlink_table_ungrab
  21. netlink_lock_table
  22. netlink_unlock_table
  23. netlink_compare
  24. netlink_compare_arg_init
  25. __netlink_lookup
  26. __netlink_insert
  27. netlink_lookup
  28. netlink_update_listeners
  29. netlink_insert
  30. netlink_remove
  31. __netlink_create
  32. netlink_create
  33. deferred_put_nlk_sk
  34. netlink_release
  35. netlink_autobind
  36. __netlink_ns_capable
  37. netlink_ns_capable
  38. netlink_capable
  39. netlink_net_capable
  40. netlink_allowed
  41. netlink_update_subscriptions
  42. netlink_realloc_groups
  43. netlink_undo_bind
  44. netlink_bind
  45. netlink_connect
  46. netlink_getname
  47. netlink_ioctl
  48. netlink_getsockbyportid
  49. netlink_getsockbyfilp
  50. netlink_alloc_large_skb
  51. netlink_attachskb
  52. __netlink_sendskb
  53. netlink_sendskb
  54. netlink_detachskb
  55. netlink_trim
  56. netlink_unicast_kernel
  57. netlink_unicast
  58. netlink_has_listeners
  59. netlink_strict_get_check
  60. netlink_broadcast_deliver
  61. do_one_broadcast
  62. netlink_broadcast_filtered
  63. netlink_broadcast
  64. do_one_set_err
  65. netlink_set_err
  66. netlink_update_socket_mc
  67. netlink_setsockopt
  68. netlink_getsockopt
  69. netlink_cmsg_recv_pktinfo
  70. netlink_cmsg_listen_all_nsid
  71. netlink_sendmsg
  72. netlink_recvmsg
  73. netlink_data_ready
  74. __netlink_kernel_create
  75. netlink_kernel_release
  76. __netlink_change_ngroups
  77. netlink_change_ngroups
  78. __netlink_clear_multicast_users
  79. __nlmsg_put
  80. netlink_dump
  81. __netlink_dump_start
  82. netlink_ack
  83. netlink_rcv_skb
  84. nlmsg_notify
  85. netlink_walk_start
  86. netlink_walk_stop
  87. __netlink_seq_next
  88. netlink_seq_start
  89. netlink_seq_next
  90. netlink_seq_stop
  91. netlink_seq_show
  92. netlink_register_notifier
  93. netlink_unregister_notifier
  94. netlink_net_init
  95. netlink_net_exit
  96. netlink_add_usersock_entry
  97. netlink_hash
  98. netlink_proto_init

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * NETLINK      Kernel-user communication protocol.
   4  *
   5  *              Authors:        Alan Cox <alan@lxorguk.ukuu.org.uk>
   6  *                              Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
   7  *                              Patrick McHardy <kaber@trash.net>
   8  *
   9  * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith
  10  *                               added netlink_proto_exit
  11  * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br>
  12  *                               use nlk_sk, as sk->protinfo is on a diet 8)
  13  * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
  14  *                               - inc module use count of module that owns
  15  *                                 the kernel socket in case userspace opens
  16  *                                 socket of same protocol
  17  *                               - remove all module support, since netlink is
  18  *                                 mandatory if CONFIG_NET=y these days
  19  */
  20 
  21 #include <linux/module.h>
  22 
  23 #include <linux/capability.h>
  24 #include <linux/kernel.h>
  25 #include <linux/init.h>
  26 #include <linux/signal.h>
  27 #include <linux/sched.h>
  28 #include <linux/errno.h>
  29 #include <linux/string.h>
  30 #include <linux/stat.h>
  31 #include <linux/socket.h>
  32 #include <linux/un.h>
  33 #include <linux/fcntl.h>
  34 #include <linux/termios.h>
  35 #include <linux/sockios.h>
  36 #include <linux/net.h>
  37 #include <linux/fs.h>
  38 #include <linux/slab.h>
  39 #include <linux/uaccess.h>
  40 #include <linux/skbuff.h>
  41 #include <linux/netdevice.h>
  42 #include <linux/rtnetlink.h>
  43 #include <linux/proc_fs.h>
  44 #include <linux/seq_file.h>
  45 #include <linux/notifier.h>
  46 #include <linux/security.h>
  47 #include <linux/jhash.h>
  48 #include <linux/jiffies.h>
  49 #include <linux/random.h>
  50 #include <linux/bitops.h>
  51 #include <linux/mm.h>
  52 #include <linux/types.h>
  53 #include <linux/audit.h>
  54 #include <linux/mutex.h>
  55 #include <linux/vmalloc.h>
  56 #include <linux/if_arp.h>
  57 #include <linux/rhashtable.h>
  58 #include <asm/cacheflush.h>
  59 #include <linux/hash.h>
  60 #include <linux/genetlink.h>
  61 #include <linux/net_namespace.h>
  62 #include <linux/nospec.h>
  63 
  64 #include <net/net_namespace.h>
  65 #include <net/netns/generic.h>
  66 #include <net/sock.h>
  67 #include <net/scm.h>
  68 #include <net/netlink.h>
  69 
  70 #include "af_netlink.h"
  71 
  72 struct listeners {
  73         struct rcu_head         rcu;
  74         unsigned long           masks[0];
  75 };
  76 
  77 /* state bits */
  78 #define NETLINK_S_CONGESTED             0x0
  79 
  80 static inline int netlink_is_kernel(struct sock *sk)
  81 {
  82         return nlk_sk(sk)->flags & NETLINK_F_KERNEL_SOCKET;
  83 }
  84 
  85 struct netlink_table *nl_table __read_mostly;
  86 EXPORT_SYMBOL_GPL(nl_table);
  87 
  88 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
  89 
  90 static struct lock_class_key nlk_cb_mutex_keys[MAX_LINKS];
  91 
  92 static const char *const nlk_cb_mutex_key_strings[MAX_LINKS + 1] = {
  93         "nlk_cb_mutex-ROUTE",
  94         "nlk_cb_mutex-1",
  95         "nlk_cb_mutex-USERSOCK",
  96         "nlk_cb_mutex-FIREWALL",
  97         "nlk_cb_mutex-SOCK_DIAG",
  98         "nlk_cb_mutex-NFLOG",
  99         "nlk_cb_mutex-XFRM",
 100         "nlk_cb_mutex-SELINUX",
 101         "nlk_cb_mutex-ISCSI",
 102         "nlk_cb_mutex-AUDIT",
 103         "nlk_cb_mutex-FIB_LOOKUP",
 104         "nlk_cb_mutex-CONNECTOR",
 105         "nlk_cb_mutex-NETFILTER",
 106         "nlk_cb_mutex-IP6_FW",
 107         "nlk_cb_mutex-DNRTMSG",
 108         "nlk_cb_mutex-KOBJECT_UEVENT",
 109         "nlk_cb_mutex-GENERIC",
 110         "nlk_cb_mutex-17",
 111         "nlk_cb_mutex-SCSITRANSPORT",
 112         "nlk_cb_mutex-ECRYPTFS",
 113         "nlk_cb_mutex-RDMA",
 114         "nlk_cb_mutex-CRYPTO",
 115         "nlk_cb_mutex-SMC",
 116         "nlk_cb_mutex-23",
 117         "nlk_cb_mutex-24",
 118         "nlk_cb_mutex-25",
 119         "nlk_cb_mutex-26",
 120         "nlk_cb_mutex-27",
 121         "nlk_cb_mutex-28",
 122         "nlk_cb_mutex-29",
 123         "nlk_cb_mutex-30",
 124         "nlk_cb_mutex-31",
 125         "nlk_cb_mutex-MAX_LINKS"
 126 };
 127 
 128 static int netlink_dump(struct sock *sk);
 129 
 130 /* nl_table locking explained:
 131  * Lookup and traversal are protected with an RCU read-side lock. Insertion
 132  * and removal are protected with per bucket lock while using RCU list
 133  * modification primitives and may run in parallel to RCU protected lookups.
 134  * Destruction of the Netlink socket may only occur *after* nl_table_lock has
 135  * been acquired * either during or after the socket has been removed from
 136  * the list and after an RCU grace period.
 137  */
 138 DEFINE_RWLOCK(nl_table_lock);
 139 EXPORT_SYMBOL_GPL(nl_table_lock);
 140 static atomic_t nl_table_users = ATOMIC_INIT(0);
 141 
 142 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
 143 
 144 static BLOCKING_NOTIFIER_HEAD(netlink_chain);
 145 
 146 
 147 static const struct rhashtable_params netlink_rhashtable_params;
 148 
 149 static inline u32 netlink_group_mask(u32 group)
 150 {
 151         return group ? 1 << (group - 1) : 0;
 152 }
 153 
 154 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
 155                                            gfp_t gfp_mask)
 156 {
 157         unsigned int len = skb_end_offset(skb);
 158         struct sk_buff *new;
 159 
 160         new = alloc_skb(len, gfp_mask);
 161         if (new == NULL)
 162                 return NULL;
 163 
 164         NETLINK_CB(new).portid = NETLINK_CB(skb).portid;
 165         NETLINK_CB(new).dst_group = NETLINK_CB(skb).dst_group;
 166         NETLINK_CB(new).creds = NETLINK_CB(skb).creds;
 167 
 168         skb_put_data(new, skb->data, len);
 169         return new;
 170 }
 171 
 172 static unsigned int netlink_tap_net_id;
 173 
 174 struct netlink_tap_net {
 175         struct list_head netlink_tap_all;
 176         struct mutex netlink_tap_lock;
 177 };
 178 
 179 int netlink_add_tap(struct netlink_tap *nt)
 180 {
 181         struct net *net = dev_net(nt->dev);
 182         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
 183 
 184         if (unlikely(nt->dev->type != ARPHRD_NETLINK))
 185                 return -EINVAL;
 186 
 187         mutex_lock(&nn->netlink_tap_lock);
 188         list_add_rcu(&nt->list, &nn->netlink_tap_all);
 189         mutex_unlock(&nn->netlink_tap_lock);
 190 
 191         __module_get(nt->module);
 192 
 193         return 0;
 194 }
 195 EXPORT_SYMBOL_GPL(netlink_add_tap);
 196 
 197 static int __netlink_remove_tap(struct netlink_tap *nt)
 198 {
 199         struct net *net = dev_net(nt->dev);
 200         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
 201         bool found = false;
 202         struct netlink_tap *tmp;
 203 
 204         mutex_lock(&nn->netlink_tap_lock);
 205 
 206         list_for_each_entry(tmp, &nn->netlink_tap_all, list) {
 207                 if (nt == tmp) {
 208                         list_del_rcu(&nt->list);
 209                         found = true;
 210                         goto out;
 211                 }
 212         }
 213 
 214         pr_warn("__netlink_remove_tap: %p not found\n", nt);
 215 out:
 216         mutex_unlock(&nn->netlink_tap_lock);
 217 
 218         if (found)
 219                 module_put(nt->module);
 220 
 221         return found ? 0 : -ENODEV;
 222 }
 223 
 224 int netlink_remove_tap(struct netlink_tap *nt)
 225 {
 226         int ret;
 227 
 228         ret = __netlink_remove_tap(nt);
 229         synchronize_net();
 230 
 231         return ret;
 232 }
 233 EXPORT_SYMBOL_GPL(netlink_remove_tap);
 234 
 235 static __net_init int netlink_tap_init_net(struct net *net)
 236 {
 237         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
 238 
 239         INIT_LIST_HEAD(&nn->netlink_tap_all);
 240         mutex_init(&nn->netlink_tap_lock);
 241         return 0;
 242 }
 243 
 244 static struct pernet_operations netlink_tap_net_ops = {
 245         .init = netlink_tap_init_net,
 246         .id   = &netlink_tap_net_id,
 247         .size = sizeof(struct netlink_tap_net),
 248 };
 249 
 250 static bool netlink_filter_tap(const struct sk_buff *skb)
 251 {
 252         struct sock *sk = skb->sk;
 253 
 254         /* We take the more conservative approach and
 255          * whitelist socket protocols that may pass.
 256          */
 257         switch (sk->sk_protocol) {
 258         case NETLINK_ROUTE:
 259         case NETLINK_USERSOCK:
 260         case NETLINK_SOCK_DIAG:
 261         case NETLINK_NFLOG:
 262         case NETLINK_XFRM:
 263         case NETLINK_FIB_LOOKUP:
 264         case NETLINK_NETFILTER:
 265         case NETLINK_GENERIC:
 266                 return true;
 267         }
 268 
 269         return false;
 270 }
 271 
 272 static int __netlink_deliver_tap_skb(struct sk_buff *skb,
 273                                      struct net_device *dev)
 274 {
 275         struct sk_buff *nskb;
 276         struct sock *sk = skb->sk;
 277         int ret = -ENOMEM;
 278 
 279         if (!net_eq(dev_net(dev), sock_net(sk)))
 280                 return 0;
 281 
 282         dev_hold(dev);
 283 
 284         if (is_vmalloc_addr(skb->head))
 285                 nskb = netlink_to_full_skb(skb, GFP_ATOMIC);
 286         else
 287                 nskb = skb_clone(skb, GFP_ATOMIC);
 288         if (nskb) {
 289                 nskb->dev = dev;
 290                 nskb->protocol = htons((u16) sk->sk_protocol);
 291                 nskb->pkt_type = netlink_is_kernel(sk) ?
 292                                  PACKET_KERNEL : PACKET_USER;
 293                 skb_reset_network_header(nskb);
 294                 ret = dev_queue_xmit(nskb);
 295                 if (unlikely(ret > 0))
 296                         ret = net_xmit_errno(ret);
 297         }
 298 
 299         dev_put(dev);
 300         return ret;
 301 }
 302 
 303 static void __netlink_deliver_tap(struct sk_buff *skb, struct netlink_tap_net *nn)
 304 {
 305         int ret;
 306         struct netlink_tap *tmp;
 307 
 308         if (!netlink_filter_tap(skb))
 309                 return;
 310 
 311         list_for_each_entry_rcu(tmp, &nn->netlink_tap_all, list) {
 312                 ret = __netlink_deliver_tap_skb(skb, tmp->dev);
 313                 if (unlikely(ret))
 314                         break;
 315         }
 316 }
 317 
 318 static void netlink_deliver_tap(struct net *net, struct sk_buff *skb)
 319 {
 320         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
 321 
 322         rcu_read_lock();
 323 
 324         if (unlikely(!list_empty(&nn->netlink_tap_all)))
 325                 __netlink_deliver_tap(skb, nn);
 326 
 327         rcu_read_unlock();
 328 }
 329 
 330 static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
 331                                        struct sk_buff *skb)
 332 {
 333         if (!(netlink_is_kernel(dst) && netlink_is_kernel(src)))
 334                 netlink_deliver_tap(sock_net(dst), skb);
 335 }
 336 
 337 static void netlink_overrun(struct sock *sk)
 338 {
 339         struct netlink_sock *nlk = nlk_sk(sk);
 340 
 341         if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) {
 342                 if (!test_and_set_bit(NETLINK_S_CONGESTED,
 343                                       &nlk_sk(sk)->state)) {
 344                         sk->sk_err = ENOBUFS;
 345                         sk->sk_error_report(sk);
 346                 }
 347         }
 348         atomic_inc(&sk->sk_drops);
 349 }
 350 
 351 static void netlink_rcv_wake(struct sock *sk)
 352 {
 353         struct netlink_sock *nlk = nlk_sk(sk);
 354 
 355         if (skb_queue_empty(&sk->sk_receive_queue))
 356                 clear_bit(NETLINK_S_CONGESTED, &nlk->state);
 357         if (!test_bit(NETLINK_S_CONGESTED, &nlk->state))
 358                 wake_up_interruptible(&nlk->wait);
 359 }
 360 
 361 static void netlink_skb_destructor(struct sk_buff *skb)
 362 {
 363         if (is_vmalloc_addr(skb->head)) {
 364                 if (!skb->cloned ||
 365                     !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
 366                         vfree(skb->head);
 367 
 368                 skb->head = NULL;
 369         }
 370         if (skb->sk != NULL)
 371                 sock_rfree(skb);
 372 }
 373 
 374 static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
 375 {
 376         WARN_ON(skb->sk != NULL);
 377         skb->sk = sk;
 378         skb->destructor = netlink_skb_destructor;
 379         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
 380         sk_mem_charge(sk, skb->truesize);
 381 }
 382 
 383 static void netlink_sock_destruct(struct sock *sk)
 384 {
 385         struct netlink_sock *nlk = nlk_sk(sk);
 386 
 387         if (nlk->cb_running) {
 388                 if (nlk->cb.done)
 389                         nlk->cb.done(&nlk->cb);
 390                 module_put(nlk->cb.module);
 391                 kfree_skb(nlk->cb.skb);
 392         }
 393 
 394         skb_queue_purge(&sk->sk_receive_queue);
 395 
 396         if (!sock_flag(sk, SOCK_DEAD)) {
 397                 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
 398                 return;
 399         }
 400 
 401         WARN_ON(atomic_read(&sk->sk_rmem_alloc));
 402         WARN_ON(refcount_read(&sk->sk_wmem_alloc));
 403         WARN_ON(nlk_sk(sk)->groups);
 404 }
 405 
 406 static void netlink_sock_destruct_work(struct work_struct *work)
 407 {
 408         struct netlink_sock *nlk = container_of(work, struct netlink_sock,
 409                                                 work);
 410 
 411         sk_free(&nlk->sk);
 412 }
 413 
 414 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
 415  * SMP. Look, when several writers sleep and reader wakes them up, all but one
 416  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
 417  * this, _but_ remember, it adds useless work on UP machines.
 418  */
 419 
 420 void netlink_table_grab(void)
 421         __acquires(nl_table_lock)
 422 {
 423         might_sleep();
 424 
 425         write_lock_irq(&nl_table_lock);
 426 
 427         if (atomic_read(&nl_table_users)) {
 428                 DECLARE_WAITQUEUE(wait, current);
 429 
 430                 add_wait_queue_exclusive(&nl_table_wait, &wait);
 431                 for (;;) {
 432                         set_current_state(TASK_UNINTERRUPTIBLE);
 433                         if (atomic_read(&nl_table_users) == 0)
 434                                 break;
 435                         write_unlock_irq(&nl_table_lock);
 436                         schedule();
 437                         write_lock_irq(&nl_table_lock);
 438                 }
 439 
 440                 __set_current_state(TASK_RUNNING);
 441                 remove_wait_queue(&nl_table_wait, &wait);
 442         }
 443 }
 444 
 445 void netlink_table_ungrab(void)
 446         __releases(nl_table_lock)
 447 {
 448         write_unlock_irq(&nl_table_lock);
 449         wake_up(&nl_table_wait);
 450 }
 451 
 452 static inline void
 453 netlink_lock_table(void)
 454 {
 455         /* read_lock() synchronizes us to netlink_table_grab */
 456 
 457         read_lock(&nl_table_lock);
 458         atomic_inc(&nl_table_users);
 459         read_unlock(&nl_table_lock);
 460 }
 461 
 462 static inline void
 463 netlink_unlock_table(void)
 464 {
 465         if (atomic_dec_and_test(&nl_table_users))
 466                 wake_up(&nl_table_wait);
 467 }
 468 
 469 struct netlink_compare_arg
 470 {
 471         possible_net_t pnet;
 472         u32 portid;
 473 };
 474 
 475 /* Doing sizeof directly may yield 4 extra bytes on 64-bit. */
 476 #define netlink_compare_arg_len \
 477         (offsetof(struct netlink_compare_arg, portid) + sizeof(u32))
 478 
 479 static inline int netlink_compare(struct rhashtable_compare_arg *arg,
 480                                   const void *ptr)
 481 {
 482         const struct netlink_compare_arg *x = arg->key;
 483         const struct netlink_sock *nlk = ptr;
 484 
 485         return nlk->portid != x->portid ||
 486                !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
 487 }
 488 
 489 static void netlink_compare_arg_init(struct netlink_compare_arg *arg,
 490                                      struct net *net, u32 portid)
 491 {
 492         memset(arg, 0, sizeof(*arg));
 493         write_pnet(&arg->pnet, net);
 494         arg->portid = portid;
 495 }
 496 
 497 static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
 498                                      struct net *net)
 499 {
 500         struct netlink_compare_arg arg;
 501 
 502         netlink_compare_arg_init(&arg, net, portid);
 503         return rhashtable_lookup_fast(&table->hash, &arg,
 504                                       netlink_rhashtable_params);
 505 }
 506 
 507 static int __netlink_insert(struct netlink_table *table, struct sock *sk)
 508 {
 509         struct netlink_compare_arg arg;
 510 
 511         netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
 512         return rhashtable_lookup_insert_key(&table->hash, &arg,
 513                                             &nlk_sk(sk)->node,
 514                                             netlink_rhashtable_params);
 515 }
 516 
 517 static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
 518 {
 519         struct netlink_table *table = &nl_table[protocol];
 520         struct sock *sk;
 521 
 522         rcu_read_lock();
 523         sk = __netlink_lookup(table, portid, net);
 524         if (sk)
 525                 sock_hold(sk);
 526         rcu_read_unlock();
 527 
 528         return sk;
 529 }
 530 
 531 static const struct proto_ops netlink_ops;
 532 
 533 static void
 534 netlink_update_listeners(struct sock *sk)
 535 {
 536         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
 537         unsigned long mask;
 538         unsigned int i;
 539         struct listeners *listeners;
 540 
 541         listeners = nl_deref_protected(tbl->listeners);
 542         if (!listeners)
 543                 return;
 544 
 545         for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
 546                 mask = 0;
 547                 sk_for_each_bound(sk, &tbl->mc_list) {
 548                         if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
 549                                 mask |= nlk_sk(sk)->groups[i];
 550                 }
 551                 listeners->masks[i] = mask;
 552         }
 553         /* this function is only called with the netlink table "grabbed", which
 554          * makes sure updates are visible before bind or setsockopt return. */
 555 }
 556 
 557 static int netlink_insert(struct sock *sk, u32 portid)
 558 {
 559         struct netlink_table *table = &nl_table[sk->sk_protocol];
 560         int err;
 561 
 562         lock_sock(sk);
 563 
 564         err = nlk_sk(sk)->portid == portid ? 0 : -EBUSY;
 565         if (nlk_sk(sk)->bound)
 566                 goto err;
 567 
 568         nlk_sk(sk)->portid = portid;
 569         sock_hold(sk);
 570 
 571         err = __netlink_insert(table, sk);
 572         if (err) {
 573                 /* In case the hashtable backend returns with -EBUSY
 574                  * from here, it must not escape to the caller.
 575                  */
 576                 if (unlikely(err == -EBUSY))
 577                         err = -EOVERFLOW;
 578                 if (err == -EEXIST)
 579                         err = -EADDRINUSE;
 580                 sock_put(sk);
 581                 goto err;
 582         }
 583 
 584         /* We need to ensure that the socket is hashed and visible. */
 585         smp_wmb();
 586         nlk_sk(sk)->bound = portid;
 587 
 588 err:
 589         release_sock(sk);
 590         return err;
 591 }
 592 
 593 static void netlink_remove(struct sock *sk)
 594 {
 595         struct netlink_table *table;
 596 
 597         table = &nl_table[sk->sk_protocol];
 598         if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node,
 599                                     netlink_rhashtable_params)) {
 600                 WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
 601                 __sock_put(sk);
 602         }
 603 
 604         netlink_table_grab();
 605         if (nlk_sk(sk)->subscriptions) {
 606                 __sk_del_bind_node(sk);
 607                 netlink_update_listeners(sk);
 608         }
 609         if (sk->sk_protocol == NETLINK_GENERIC)
 610                 atomic_inc(&genl_sk_destructing_cnt);
 611         netlink_table_ungrab();
 612 }
 613 
 614 static struct proto netlink_proto = {
 615         .name     = "NETLINK",
 616         .owner    = THIS_MODULE,
 617         .obj_size = sizeof(struct netlink_sock),
 618 };
 619 
 620 static int __netlink_create(struct net *net, struct socket *sock,
 621                             struct mutex *cb_mutex, int protocol,
 622                             int kern)
 623 {
 624         struct sock *sk;
 625         struct netlink_sock *nlk;
 626 
 627         sock->ops = &netlink_ops;
 628 
 629         sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto, kern);
 630         if (!sk)
 631                 return -ENOMEM;
 632 
 633         sock_init_data(sock, sk);
 634 
 635         nlk = nlk_sk(sk);
 636         if (cb_mutex) {
 637                 nlk->cb_mutex = cb_mutex;
 638         } else {
 639                 nlk->cb_mutex = &nlk->cb_def_mutex;
 640                 mutex_init(nlk->cb_mutex);
 641                 lockdep_set_class_and_name(nlk->cb_mutex,
 642                                            nlk_cb_mutex_keys + protocol,
 643                                            nlk_cb_mutex_key_strings[protocol]);
 644         }
 645         init_waitqueue_head(&nlk->wait);
 646 
 647         sk->sk_destruct = netlink_sock_destruct;
 648         sk->sk_protocol = protocol;
 649         return 0;
 650 }
 651 
 652 static int netlink_create(struct net *net, struct socket *sock, int protocol,
 653                           int kern)
 654 {
 655         struct module *module = NULL;
 656         struct mutex *cb_mutex;
 657         struct netlink_sock *nlk;
 658         int (*bind)(struct net *net, int group);
 659         void (*unbind)(struct net *net, int group);
 660         int err = 0;
 661 
 662         sock->state = SS_UNCONNECTED;
 663 
 664         if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
 665                 return -ESOCKTNOSUPPORT;
 666 
 667         if (protocol < 0 || protocol >= MAX_LINKS)
 668                 return -EPROTONOSUPPORT;
 669         protocol = array_index_nospec(protocol, MAX_LINKS);
 670 
 671         netlink_lock_table();
 672 #ifdef CONFIG_MODULES
 673         if (!nl_table[protocol].registered) {
 674                 netlink_unlock_table();
 675                 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
 676                 netlink_lock_table();
 677         }
 678 #endif
 679         if (nl_table[protocol].registered &&
 680             try_module_get(nl_table[protocol].module))
 681                 module = nl_table[protocol].module;
 682         else
 683                 err = -EPROTONOSUPPORT;
 684         cb_mutex = nl_table[protocol].cb_mutex;
 685         bind = nl_table[protocol].bind;
 686         unbind = nl_table[protocol].unbind;
 687         netlink_unlock_table();
 688 
 689         if (err < 0)
 690                 goto out;
 691 
 692         err = __netlink_create(net, sock, cb_mutex, protocol, kern);
 693         if (err < 0)
 694                 goto out_module;
 695 
 696         local_bh_disable();
 697         sock_prot_inuse_add(net, &netlink_proto, 1);
 698         local_bh_enable();
 699 
 700         nlk = nlk_sk(sock->sk);
 701         nlk->module = module;
 702         nlk->netlink_bind = bind;
 703         nlk->netlink_unbind = unbind;
 704 out:
 705         return err;
 706 
 707 out_module:
 708         module_put(module);
 709         goto out;
 710 }
 711 
 712 static void deferred_put_nlk_sk(struct rcu_head *head)
 713 {
 714         struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu);
 715         struct sock *sk = &nlk->sk;
 716 
 717         kfree(nlk->groups);
 718         nlk->groups = NULL;
 719 
 720         if (!refcount_dec_and_test(&sk->sk_refcnt))
 721                 return;
 722 
 723         if (nlk->cb_running && nlk->cb.done) {
 724                 INIT_WORK(&nlk->work, netlink_sock_destruct_work);
 725                 schedule_work(&nlk->work);
 726                 return;
 727         }
 728 
 729         sk_free(sk);
 730 }
 731 
 732 static int netlink_release(struct socket *sock)
 733 {
 734         struct sock *sk = sock->sk;
 735         struct netlink_sock *nlk;
 736 
 737         if (!sk)
 738                 return 0;
 739 
 740         netlink_remove(sk);
 741         sock_orphan(sk);
 742         nlk = nlk_sk(sk);
 743 
 744         /*
 745          * OK. Socket is unlinked, any packets that arrive now
 746          * will be purged.
 747          */
 748 
 749         /* must not acquire netlink_table_lock in any way again before unbind
 750          * and notifying genetlink is done as otherwise it might deadlock
 751          */
 752         if (nlk->netlink_unbind) {
 753                 int i;
 754 
 755                 for (i = 0; i < nlk->ngroups; i++)
 756                         if (test_bit(i, nlk->groups))
 757                                 nlk->netlink_unbind(sock_net(sk), i + 1);
 758         }
 759         if (sk->sk_protocol == NETLINK_GENERIC &&
 760             atomic_dec_return(&genl_sk_destructing_cnt) == 0)
 761                 wake_up(&genl_sk_destructing_waitq);
 762 
 763         sock->sk = NULL;
 764         wake_up_interruptible_all(&nlk->wait);
 765 
 766         skb_queue_purge(&sk->sk_write_queue);
 767 
 768         if (nlk->portid && nlk->bound) {
 769                 struct netlink_notify n = {
 770                                                 .net = sock_net(sk),
 771                                                 .protocol = sk->sk_protocol,
 772                                                 .portid = nlk->portid,
 773                                           };
 774                 blocking_notifier_call_chain(&netlink_chain,
 775                                 NETLINK_URELEASE, &n);
 776         }
 777 
 778         module_put(nlk->module);
 779 
 780         if (netlink_is_kernel(sk)) {
 781                 netlink_table_grab();
 782                 BUG_ON(nl_table[sk->sk_protocol].registered == 0);
 783                 if (--nl_table[sk->sk_protocol].registered == 0) {
 784                         struct listeners *old;
 785 
 786                         old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
 787                         RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
 788                         kfree_rcu(old, rcu);
 789                         nl_table[sk->sk_protocol].module = NULL;
 790                         nl_table[sk->sk_protocol].bind = NULL;
 791                         nl_table[sk->sk_protocol].unbind = NULL;
 792                         nl_table[sk->sk_protocol].flags = 0;
 793                         nl_table[sk->sk_protocol].registered = 0;
 794                 }
 795                 netlink_table_ungrab();
 796         }
 797 
 798         local_bh_disable();
 799         sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
 800         local_bh_enable();
 801         call_rcu(&nlk->rcu, deferred_put_nlk_sk);
 802         return 0;
 803 }
 804 
 805 static int netlink_autobind(struct socket *sock)
 806 {
 807         struct sock *sk = sock->sk;
 808         struct net *net = sock_net(sk);
 809         struct netlink_table *table = &nl_table[sk->sk_protocol];
 810         s32 portid = task_tgid_vnr(current);
 811         int err;
 812         s32 rover = -4096;
 813         bool ok;
 814 
 815 retry:
 816         cond_resched();
 817         rcu_read_lock();
 818         ok = !__netlink_lookup(table, portid, net);
 819         rcu_read_unlock();
 820         if (!ok) {
 821                 /* Bind collision, search negative portid values. */
 822                 if (rover == -4096)
 823                         /* rover will be in range [S32_MIN, -4097] */
 824                         rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN);
 825                 else if (rover >= -4096)
 826                         rover = -4097;
 827                 portid = rover--;
 828                 goto retry;
 829         }
 830 
 831         err = netlink_insert(sk, portid);
 832         if (err == -EADDRINUSE)
 833                 goto retry;
 834 
 835         /* If 2 threads race to autobind, that is fine.  */
 836         if (err == -EBUSY)
 837                 err = 0;
 838 
 839         return err;
 840 }
 841 
 842 /**
 843  * __netlink_ns_capable - General netlink message capability test
 844  * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
 845  * @user_ns: The user namespace of the capability to use
 846  * @cap: The capability to use
 847  *
 848  * Test to see if the opener of the socket we received the message
 849  * from had when the netlink socket was created and the sender of the
 850  * message has has the capability @cap in the user namespace @user_ns.
 851  */
 852 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
 853                         struct user_namespace *user_ns, int cap)
 854 {
 855         return ((nsp->flags & NETLINK_SKB_DST) ||
 856                 file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
 857                 ns_capable(user_ns, cap);
 858 }
 859 EXPORT_SYMBOL(__netlink_ns_capable);
 860 
 861 /**
 862  * netlink_ns_capable - General netlink message capability test
 863  * @skb: socket buffer holding a netlink command from userspace
 864  * @user_ns: The user namespace of the capability to use
 865  * @cap: The capability to use
 866  *
 867  * Test to see if the opener of the socket we received the message
 868  * from had when the netlink socket was created and the sender of the
 869  * message has has the capability @cap in the user namespace @user_ns.
 870  */
 871 bool netlink_ns_capable(const struct sk_buff *skb,
 872                         struct user_namespace *user_ns, int cap)
 873 {
 874         return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
 875 }
 876 EXPORT_SYMBOL(netlink_ns_capable);
 877 
 878 /**
 879  * netlink_capable - Netlink global message capability test
 880  * @skb: socket buffer holding a netlink command from userspace
 881  * @cap: The capability to use
 882  *
 883  * Test to see if the opener of the socket we received the message
 884  * from had when the netlink socket was created and the sender of the
 885  * message has has the capability @cap in all user namespaces.
 886  */
 887 bool netlink_capable(const struct sk_buff *skb, int cap)
 888 {
 889         return netlink_ns_capable(skb, &init_user_ns, cap);
 890 }
 891 EXPORT_SYMBOL(netlink_capable);
 892 
 893 /**
 894  * netlink_net_capable - Netlink network namespace message capability test
 895  * @skb: socket buffer holding a netlink command from userspace
 896  * @cap: The capability to use
 897  *
 898  * Test to see if the opener of the socket we received the message
 899  * from had when the netlink socket was created and the sender of the
 900  * message has has the capability @cap over the network namespace of
 901  * the socket we received the message from.
 902  */
 903 bool netlink_net_capable(const struct sk_buff *skb, int cap)
 904 {
 905         return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
 906 }
 907 EXPORT_SYMBOL(netlink_net_capable);
 908 
 909 static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
 910 {
 911         return (nl_table[sock->sk->sk_protocol].flags & flag) ||
 912                 ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
 913 }
 914 
 915 static void
 916 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
 917 {
 918         struct netlink_sock *nlk = nlk_sk(sk);
 919 
 920         if (nlk->subscriptions && !subscriptions)
 921                 __sk_del_bind_node(sk);
 922         else if (!nlk->subscriptions && subscriptions)
 923                 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
 924         nlk->subscriptions = subscriptions;
 925 }
 926 
 927 static int netlink_realloc_groups(struct sock *sk)
 928 {
 929         struct netlink_sock *nlk = nlk_sk(sk);
 930         unsigned int groups;
 931         unsigned long *new_groups;
 932         int err = 0;
 933 
 934         netlink_table_grab();
 935 
 936         groups = nl_table[sk->sk_protocol].groups;
 937         if (!nl_table[sk->sk_protocol].registered) {
 938                 err = -ENOENT;
 939                 goto out_unlock;
 940         }
 941 
 942         if (nlk->ngroups >= groups)
 943                 goto out_unlock;
 944 
 945         new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
 946         if (new_groups == NULL) {
 947                 err = -ENOMEM;
 948                 goto out_unlock;
 949         }
 950         memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
 951                NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
 952 
 953         nlk->groups = new_groups;
 954         nlk->ngroups = groups;
 955  out_unlock:
 956         netlink_table_ungrab();
 957         return err;
 958 }
 959 
 960 static void netlink_undo_bind(int group, long unsigned int groups,
 961                               struct sock *sk)
 962 {
 963         struct netlink_sock *nlk = nlk_sk(sk);
 964         int undo;
 965 
 966         if (!nlk->netlink_unbind)
 967                 return;
 968 
 969         for (undo = 0; undo < group; undo++)
 970                 if (test_bit(undo, &groups))
 971                         nlk->netlink_unbind(sock_net(sk), undo + 1);
 972 }
 973 
 974 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 975                         int addr_len)
 976 {
 977         struct sock *sk = sock->sk;
 978         struct net *net = sock_net(sk);
 979         struct netlink_sock *nlk = nlk_sk(sk);
 980         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
 981         int err = 0;
 982         unsigned long groups;
 983         bool bound;
 984 
 985         if (addr_len < sizeof(struct sockaddr_nl))
 986                 return -EINVAL;
 987 
 988         if (nladdr->nl_family != AF_NETLINK)
 989                 return -EINVAL;
 990         groups = nladdr->nl_groups;
 991 
 992         /* Only superuser is allowed to listen multicasts */
 993         if (groups) {
 994                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
 995                         return -EPERM;
 996                 err = netlink_realloc_groups(sk);
 997                 if (err)
 998                         return err;
 999         }
1000 
1001         if (nlk->ngroups < BITS_PER_LONG)
1002                 groups &= (1UL << nlk->ngroups) - 1;
1003 
1004         bound = nlk->bound;
1005         if (bound) {
1006                 /* Ensure nlk->portid is up-to-date. */
1007                 smp_rmb();
1008 
1009                 if (nladdr->nl_pid != nlk->portid)
1010                         return -EINVAL;
1011         }
1012 
1013         netlink_lock_table();
1014         if (nlk->netlink_bind && groups) {
1015                 int group;
1016 
1017                 /* nl_groups is a u32, so cap the maximum groups we can bind */
1018                 for (group = 0; group < BITS_PER_TYPE(u32); group++) {
1019                         if (!test_bit(group, &groups))
1020                                 continue;
1021                         err = nlk->netlink_bind(net, group + 1);
1022                         if (!err)
1023                                 continue;
1024                         netlink_undo_bind(group, groups, sk);
1025                         goto unlock;
1026                 }
1027         }
1028 
1029         /* No need for barriers here as we return to user-space without
1030          * using any of the bound attributes.
1031          */
1032         if (!bound) {
1033                 err = nladdr->nl_pid ?
1034                         netlink_insert(sk, nladdr->nl_pid) :
1035                         netlink_autobind(sock);
1036                 if (err) {
1037                         netlink_undo_bind(BITS_PER_TYPE(u32), groups, sk);
1038                         goto unlock;
1039                 }
1040         }
1041 
1042         if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
1043                 goto unlock;
1044         netlink_unlock_table();
1045 
1046         netlink_table_grab();
1047         netlink_update_subscriptions(sk, nlk->subscriptions +
1048                                          hweight32(groups) -
1049                                          hweight32(nlk->groups[0]));
1050         nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups;
1051         netlink_update_listeners(sk);
1052         netlink_table_ungrab();
1053 
1054         return 0;
1055 
1056 unlock:
1057         netlink_unlock_table();
1058         return err;
1059 }
1060 
1061 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
1062                            int alen, int flags)
1063 {
1064         int err = 0;
1065         struct sock *sk = sock->sk;
1066         struct netlink_sock *nlk = nlk_sk(sk);
1067         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
1068 
1069         if (alen < sizeof(addr->sa_family))
1070                 return -EINVAL;
1071 
1072         if (addr->sa_family == AF_UNSPEC) {
1073                 sk->sk_state    = NETLINK_UNCONNECTED;
1074                 nlk->dst_portid = 0;
1075                 nlk->dst_group  = 0;
1076                 return 0;
1077         }
1078         if (addr->sa_family != AF_NETLINK)
1079                 return -EINVAL;
1080 
1081         if (alen < sizeof(struct sockaddr_nl))
1082                 return -EINVAL;
1083 
1084         if ((nladdr->nl_groups || nladdr->nl_pid) &&
1085             !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1086                 return -EPERM;
1087 
1088         /* No need for barriers here as we return to user-space without
1089          * using any of the bound attributes.
1090          */
1091         if (!nlk->bound)
1092                 err = netlink_autobind(sock);
1093 
1094         if (err == 0) {
1095                 sk->sk_state    = NETLINK_CONNECTED;
1096                 nlk->dst_portid = nladdr->nl_pid;
1097                 nlk->dst_group  = ffs(nladdr->nl_groups);
1098         }
1099 
1100         return err;
1101 }
1102 
1103 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
1104                            int peer)
1105 {
1106         struct sock *sk = sock->sk;
1107         struct netlink_sock *nlk = nlk_sk(sk);
1108         DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
1109 
1110         nladdr->nl_family = AF_NETLINK;
1111         nladdr->nl_pad = 0;
1112 
1113         if (peer) {
1114                 nladdr->nl_pid = nlk->dst_portid;
1115                 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
1116         } else {
1117                 nladdr->nl_pid = nlk->portid;
1118                 netlink_lock_table();
1119                 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
1120                 netlink_unlock_table();
1121         }
1122         return sizeof(*nladdr);
1123 }
1124 
1125 static int netlink_ioctl(struct socket *sock, unsigned int cmd,
1126                          unsigned long arg)
1127 {
1128         /* try to hand this ioctl down to the NIC drivers.
1129          */
1130         return -ENOIOCTLCMD;
1131 }
1132 
1133 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
1134 {
1135         struct sock *sock;
1136         struct netlink_sock *nlk;
1137 
1138         sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
1139         if (!sock)
1140                 return ERR_PTR(-ECONNREFUSED);
1141 
1142         /* Don't bother queuing skb if kernel socket has no input function */
1143         nlk = nlk_sk(sock);
1144         if (sock->sk_state == NETLINK_CONNECTED &&
1145             nlk->dst_portid != nlk_sk(ssk)->portid) {
1146                 sock_put(sock);
1147                 return ERR_PTR(-ECONNREFUSED);
1148         }
1149         return sock;
1150 }
1151 
1152 struct sock *netlink_getsockbyfilp(struct file *filp)
1153 {
1154         struct inode *inode = file_inode(filp);
1155         struct sock *sock;
1156 
1157         if (!S_ISSOCK(inode->i_mode))
1158                 return ERR_PTR(-ENOTSOCK);
1159 
1160         sock = SOCKET_I(inode)->sk;
1161         if (sock->sk_family != AF_NETLINK)
1162                 return ERR_PTR(-EINVAL);
1163 
1164         sock_hold(sock);
1165         return sock;
1166 }
1167 
1168 static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
1169                                                int broadcast)
1170 {
1171         struct sk_buff *skb;
1172         void *data;
1173 
1174         if (size <= NLMSG_GOODSIZE || broadcast)
1175                 return alloc_skb(size, GFP_KERNEL);
1176 
1177         size = SKB_DATA_ALIGN(size) +
1178                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
1179 
1180         data = vmalloc(size);
1181         if (data == NULL)
1182                 return NULL;
1183 
1184         skb = __build_skb(data, size);
1185         if (skb == NULL)
1186                 vfree(data);
1187         else
1188                 skb->destructor = netlink_skb_destructor;
1189 
1190         return skb;
1191 }
1192 
1193 /*
1194  * Attach a skb to a netlink socket.
1195  * The caller must hold a reference to the destination socket. On error, the
1196  * reference is dropped. The skb is not send to the destination, just all
1197  * all error checks are performed and memory in the queue is reserved.
1198  * Return values:
1199  * < 0: error. skb freed, reference to sock dropped.
1200  * 0: continue
1201  * 1: repeat lookup - reference dropped while waiting for socket memory.
1202  */
1203 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
1204                       long *timeo, struct sock *ssk)
1205 {
1206         struct netlink_sock *nlk;
1207 
1208         nlk = nlk_sk(sk);
1209 
1210         if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1211              test_bit(NETLINK_S_CONGESTED, &nlk->state))) {
1212                 DECLARE_WAITQUEUE(wait, current);
1213                 if (!*timeo) {
1214                         if (!ssk || netlink_is_kernel(ssk))
1215                                 netlink_overrun(sk);
1216                         sock_put(sk);
1217                         kfree_skb(skb);
1218                         return -EAGAIN;
1219                 }
1220 
1221                 __set_current_state(TASK_INTERRUPTIBLE);
1222                 add_wait_queue(&nlk->wait, &wait);
1223 
1224                 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1225                      test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
1226                     !sock_flag(sk, SOCK_DEAD))
1227                         *timeo = schedule_timeout(*timeo);
1228 
1229                 __set_current_state(TASK_RUNNING);
1230                 remove_wait_queue(&nlk->wait, &wait);
1231                 sock_put(sk);
1232 
1233                 if (signal_pending(current)) {
1234                         kfree_skb(skb);
1235                         return sock_intr_errno(*timeo);
1236                 }
1237                 return 1;
1238         }
1239         netlink_skb_set_owner_r(skb, sk);
1240         return 0;
1241 }
1242 
1243 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1244 {
1245         int len = skb->len;
1246 
1247         netlink_deliver_tap(sock_net(sk), skb);
1248 
1249         skb_queue_tail(&sk->sk_receive_queue, skb);
1250         sk->sk_data_ready(sk);
1251         return len;
1252 }
1253 
1254 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1255 {
1256         int len = __netlink_sendskb(sk, skb);
1257 
1258         sock_put(sk);
1259         return len;
1260 }
1261 
1262 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
1263 {
1264         kfree_skb(skb);
1265         sock_put(sk);
1266 }
1267 
1268 static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
1269 {
1270         int delta;
1271 
1272         WARN_ON(skb->sk != NULL);
1273         delta = skb->end - skb->tail;
1274         if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
1275                 return skb;
1276 
1277         if (skb_shared(skb)) {
1278                 struct sk_buff *nskb = skb_clone(skb, allocation);
1279                 if (!nskb)
1280                         return skb;
1281                 consume_skb(skb);
1282                 skb = nskb;
1283         }
1284 
1285         pskb_expand_head(skb, 0, -delta,
1286                          (allocation & ~__GFP_DIRECT_RECLAIM) |
1287                          __GFP_NOWARN | __GFP_NORETRY);
1288         return skb;
1289 }
1290 
1291 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
1292                                   struct sock *ssk)
1293 {
1294         int ret;
1295         struct netlink_sock *nlk = nlk_sk(sk);
1296 
1297         ret = -ECONNREFUSED;
1298         if (nlk->netlink_rcv != NULL) {
1299                 ret = skb->len;
1300                 netlink_skb_set_owner_r(skb, sk);
1301                 NETLINK_CB(skb).sk = ssk;
1302                 netlink_deliver_tap_kernel(sk, ssk, skb);
1303                 nlk->netlink_rcv(skb);
1304                 consume_skb(skb);
1305         } else {
1306                 kfree_skb(skb);
1307         }
1308         sock_put(sk);
1309         return ret;
1310 }
1311 
1312 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
1313                     u32 portid, int nonblock)
1314 {
1315         struct sock *sk;
1316         int err;
1317         long timeo;
1318 
1319         skb = netlink_trim(skb, gfp_any());
1320 
1321         timeo = sock_sndtimeo(ssk, nonblock);
1322 retry:
1323         sk = netlink_getsockbyportid(ssk, portid);
1324         if (IS_ERR(sk)) {
1325                 kfree_skb(skb);
1326                 return PTR_ERR(sk);
1327         }
1328         if (netlink_is_kernel(sk))
1329                 return netlink_unicast_kernel(sk, skb, ssk);
1330 
1331         if (sk_filter(sk, skb)) {
1332                 err = skb->len;
1333                 kfree_skb(skb);
1334                 sock_put(sk);
1335                 return err;
1336         }
1337 
1338         err = netlink_attachskb(sk, skb, &timeo, ssk);
1339         if (err == 1)
1340                 goto retry;
1341         if (err)
1342                 return err;
1343 
1344         return netlink_sendskb(sk, skb);
1345 }
1346 EXPORT_SYMBOL(netlink_unicast);
1347 
1348 int netlink_has_listeners(struct sock *sk, unsigned int group)
1349 {
1350         int res = 0;
1351         struct listeners *listeners;
1352 
1353         BUG_ON(!netlink_is_kernel(sk));
1354 
1355         rcu_read_lock();
1356         listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
1357 
1358         if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
1359                 res = test_bit(group - 1, listeners->masks);
1360 
1361         rcu_read_unlock();
1362 
1363         return res;
1364 }
1365 EXPORT_SYMBOL_GPL(netlink_has_listeners);
1366 
1367 bool netlink_strict_get_check(struct sk_buff *skb)
1368 {
1369         const struct netlink_sock *nlk = nlk_sk(NETLINK_CB(skb).sk);
1370 
1371         return nlk->flags & NETLINK_F_STRICT_CHK;
1372 }
1373 EXPORT_SYMBOL_GPL(netlink_strict_get_check);
1374 
1375 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
1376 {
1377         struct netlink_sock *nlk = nlk_sk(sk);
1378 
1379         if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
1380             !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
1381                 netlink_skb_set_owner_r(skb, sk);
1382                 __netlink_sendskb(sk, skb);
1383                 return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
1384         }
1385         return -1;
1386 }
1387 
1388 struct netlink_broadcast_data {
1389         struct sock *exclude_sk;
1390         struct net *net;
1391         u32 portid;
1392         u32 group;
1393         int failure;
1394         int delivery_failure;
1395         int congested;
1396         int delivered;
1397         gfp_t allocation;
1398         struct sk_buff *skb, *skb2;
1399         int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
1400         void *tx_data;
1401 };
1402 
1403 static void do_one_broadcast(struct sock *sk,
1404                                     struct netlink_broadcast_data *p)
1405 {
1406         struct netlink_sock *nlk = nlk_sk(sk);
1407         int val;
1408 
1409         if (p->exclude_sk == sk)
1410                 return;
1411 
1412         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1413             !test_bit(p->group - 1, nlk->groups))
1414                 return;
1415 
1416         if (!net_eq(sock_net(sk), p->net)) {
1417                 if (!(nlk->flags & NETLINK_F_LISTEN_ALL_NSID))
1418                         return;
1419 
1420                 if (!peernet_has_id(sock_net(sk), p->net))
1421                         return;
1422 
1423                 if (!file_ns_capable(sk->sk_socket->file, p->net->user_ns,
1424                                      CAP_NET_BROADCAST))
1425                         return;
1426         }
1427 
1428         if (p->failure) {
1429                 netlink_overrun(sk);
1430                 return;
1431         }
1432 
1433         sock_hold(sk);
1434         if (p->skb2 == NULL) {
1435                 if (skb_shared(p->skb)) {
1436                         p->skb2 = skb_clone(p->skb, p->allocation);
1437                 } else {
1438                         p->skb2 = skb_get(p->skb);
1439                         /*
1440                          * skb ownership may have been set when
1441                          * delivered to a previous socket.
1442                          */
1443                         skb_orphan(p->skb2);
1444                 }
1445         }
1446         if (p->skb2 == NULL) {
1447                 netlink_overrun(sk);
1448                 /* Clone failed. Notify ALL listeners. */
1449                 p->failure = 1;
1450                 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
1451                         p->delivery_failure = 1;
1452                 goto out;
1453         }
1454         if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
1455                 kfree_skb(p->skb2);
1456                 p->skb2 = NULL;
1457                 goto out;
1458         }
1459         if (sk_filter(sk, p->skb2)) {
1460                 kfree_skb(p->skb2);
1461                 p->skb2 = NULL;
1462                 goto out;
1463         }
1464         NETLINK_CB(p->skb2).nsid = peernet2id(sock_net(sk), p->net);
1465         if (NETLINK_CB(p->skb2).nsid != NETNSA_NSID_NOT_ASSIGNED)
1466                 NETLINK_CB(p->skb2).nsid_is_set = true;
1467         val = netlink_broadcast_deliver(sk, p->skb2);
1468         if (val < 0) {
1469                 netlink_overrun(sk);
1470                 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
1471                         p->delivery_failure = 1;
1472         } else {
1473                 p->congested |= val;
1474                 p->delivered = 1;
1475                 p->skb2 = NULL;
1476         }
1477 out:
1478         sock_put(sk);
1479 }
1480 
1481 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 portid,
1482         u32 group, gfp_t allocation,
1483         int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
1484         void *filter_data)
1485 {
1486         struct net *net = sock_net(ssk);
1487         struct netlink_broadcast_data info;
1488         struct sock *sk;
1489 
1490         skb = netlink_trim(skb, allocation);
1491 
1492         info.exclude_sk = ssk;
1493         info.net = net;
1494         info.portid = portid;
1495         info.group = group;
1496         info.failure = 0;
1497         info.delivery_failure = 0;
1498         info.congested = 0;
1499         info.delivered = 0;
1500         info.allocation = allocation;
1501         info.skb = skb;
1502         info.skb2 = NULL;
1503         info.tx_filter = filter;
1504         info.tx_data = filter_data;
1505 
1506         /* While we sleep in clone, do not allow to change socket list */
1507 
1508         netlink_lock_table();
1509 
1510         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1511                 do_one_broadcast(sk, &info);
1512 
1513         consume_skb(skb);
1514 
1515         netlink_unlock_table();
1516 
1517         if (info.delivery_failure) {
1518                 kfree_skb(info.skb2);
1519                 return -ENOBUFS;
1520         }
1521         consume_skb(info.skb2);
1522 
1523         if (info.delivered) {
1524                 if (info.congested && gfpflags_allow_blocking(allocation))
1525                         yield();
1526                 return 0;
1527         }
1528         return -ESRCH;
1529 }
1530 EXPORT_SYMBOL(netlink_broadcast_filtered);
1531 
1532 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
1533                       u32 group, gfp_t allocation)
1534 {
1535         return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
1536                 NULL, NULL);
1537 }
1538 EXPORT_SYMBOL(netlink_broadcast);
1539 
1540 struct netlink_set_err_data {
1541         struct sock *exclude_sk;
1542         u32 portid;
1543         u32 group;
1544         int code;
1545 };
1546 
1547 static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
1548 {
1549         struct netlink_sock *nlk = nlk_sk(sk);
1550         int ret = 0;
1551 
1552         if (sk == p->exclude_sk)
1553                 goto out;
1554 
1555         if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
1556                 goto out;
1557 
1558         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1559             !test_bit(p->group - 1, nlk->groups))
1560                 goto out;
1561 
1562         if (p->code == ENOBUFS && nlk->flags & NETLINK_F_RECV_NO_ENOBUFS) {
1563                 ret = 1;
1564                 goto out;
1565         }
1566 
1567         sk->sk_err = p->code;
1568         sk->sk_error_report(sk);
1569 out:
1570         return ret;
1571 }
1572 
1573 /**
1574  * netlink_set_err - report error to broadcast listeners
1575  * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
1576  * @portid: the PORTID of a process that we want to skip (if any)
1577  * @group: the broadcast group that will notice the error
1578  * @code: error code, must be negative (as usual in kernelspace)
1579  *
1580  * This function returns the number of broadcast listeners that have set the
1581  * NETLINK_NO_ENOBUFS socket option.
1582  */
1583 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
1584 {
1585         struct netlink_set_err_data info;
1586         struct sock *sk;
1587         int ret = 0;
1588 
1589         info.exclude_sk = ssk;
1590         info.portid = portid;
1591         info.group = group;
1592         /* sk->sk_err wants a positive error value */
1593         info.code = -code;
1594 
1595         read_lock(&nl_table_lock);
1596 
1597         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1598                 ret += do_one_set_err(sk, &info);
1599 
1600         read_unlock(&nl_table_lock);
1601         return ret;
1602 }
1603 EXPORT_SYMBOL(netlink_set_err);
1604 
1605 /* must be called with netlink table grabbed */
1606 static void netlink_update_socket_mc(struct netlink_sock *nlk,
1607                                      unsigned int group,
1608                                      int is_new)
1609 {
1610         int old, new = !!is_new, subscriptions;
1611 
1612         old = test_bit(group - 1, nlk->groups);
1613         subscriptions = nlk->subscriptions - old + new;
1614         if (new)
1615                 __set_bit(group - 1, nlk->groups);
1616         else
1617                 __clear_bit(group - 1, nlk->groups);
1618         netlink_update_subscriptions(&nlk->sk, subscriptions);
1619         netlink_update_listeners(&nlk->sk);
1620 }
1621 
1622 static int netlink_setsockopt(struct socket *sock, int level, int optname,
1623                               char __user *optval, unsigned int optlen)
1624 {
1625         struct sock *sk = sock->sk;
1626         struct netlink_sock *nlk = nlk_sk(sk);
1627         unsigned int val = 0;
1628         int err;
1629 
1630         if (level != SOL_NETLINK)
1631                 return -ENOPROTOOPT;
1632 
1633         if (optlen >= sizeof(int) &&
1634             get_user(val, (unsigned int __user *)optval))
1635                 return -EFAULT;
1636 
1637         switch (optname) {
1638         case NETLINK_PKTINFO:
1639                 if (val)
1640                         nlk->flags |= NETLINK_F_RECV_PKTINFO;
1641                 else
1642                         nlk->flags &= ~NETLINK_F_RECV_PKTINFO;
1643                 err = 0;
1644                 break;
1645         case NETLINK_ADD_MEMBERSHIP:
1646         case NETLINK_DROP_MEMBERSHIP: {
1647                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
1648                         return -EPERM;
1649                 err = netlink_realloc_groups(sk);
1650                 if (err)
1651                         return err;
1652                 if (!val || val - 1 >= nlk->ngroups)
1653                         return -EINVAL;
1654                 if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
1655                         err = nlk->netlink_bind(sock_net(sk), val);
1656                         if (err)
1657                                 return err;
1658                 }
1659                 netlink_table_grab();
1660                 netlink_update_socket_mc(nlk, val,
1661                                          optname == NETLINK_ADD_MEMBERSHIP);
1662                 netlink_table_ungrab();
1663                 if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
1664                         nlk->netlink_unbind(sock_net(sk), val);
1665 
1666                 err = 0;
1667                 break;
1668         }
1669         case NETLINK_BROADCAST_ERROR:
1670                 if (val)
1671                         nlk->flags |= NETLINK_F_BROADCAST_SEND_ERROR;
1672                 else
1673                         nlk->flags &= ~NETLINK_F_BROADCAST_SEND_ERROR;
1674                 err = 0;
1675                 break;
1676         case NETLINK_NO_ENOBUFS:
1677                 if (val) {
1678                         nlk->flags |= NETLINK_F_RECV_NO_ENOBUFS;
1679                         clear_bit(NETLINK_S_CONGESTED, &nlk->state);
1680                         wake_up_interruptible(&nlk->wait);
1681                 } else {
1682                         nlk->flags &= ~NETLINK_F_RECV_NO_ENOBUFS;
1683                 }
1684                 err = 0;
1685                 break;
1686         case NETLINK_LISTEN_ALL_NSID:
1687                 if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
1688                         return -EPERM;
1689 
1690                 if (val)
1691                         nlk->flags |= NETLINK_F_LISTEN_ALL_NSID;
1692                 else
1693                         nlk->flags &= ~NETLINK_F_LISTEN_ALL_NSID;
1694                 err = 0;
1695                 break;
1696         case NETLINK_CAP_ACK:
1697                 if (val)
1698                         nlk->flags |= NETLINK_F_CAP_ACK;
1699                 else
1700                         nlk->flags &= ~NETLINK_F_CAP_ACK;
1701                 err = 0;
1702                 break;
1703         case NETLINK_EXT_ACK:
1704                 if (val)
1705                         nlk->flags |= NETLINK_F_EXT_ACK;
1706                 else
1707                         nlk->flags &= ~NETLINK_F_EXT_ACK;
1708                 err = 0;
1709                 break;
1710         case NETLINK_GET_STRICT_CHK:
1711                 if (val)
1712                         nlk->flags |= NETLINK_F_STRICT_CHK;
1713                 else
1714                         nlk->flags &= ~NETLINK_F_STRICT_CHK;
1715                 err = 0;
1716                 break;
1717         default:
1718                 err = -ENOPROTOOPT;
1719         }
1720         return err;
1721 }
1722 
1723 static int netlink_getsockopt(struct socket *sock, int level, int optname,
1724                               char __user *optval, int __user *optlen)
1725 {
1726         struct sock *sk = sock->sk;
1727         struct netlink_sock *nlk = nlk_sk(sk);
1728         int len, val, err;
1729 
1730         if (level != SOL_NETLINK)
1731                 return -ENOPROTOOPT;
1732 
1733         if (get_user(len, optlen))
1734                 return -EFAULT;
1735         if (len < 0)
1736                 return -EINVAL;
1737 
1738         switch (optname) {
1739         case NETLINK_PKTINFO:
1740                 if (len < sizeof(int))
1741                         return -EINVAL;
1742                 len = sizeof(int);
1743                 val = nlk->flags & NETLINK_F_RECV_PKTINFO ? 1 : 0;
1744                 if (put_user(len, optlen) ||
1745                     put_user(val, optval))
1746                         return -EFAULT;
1747                 err = 0;
1748                 break;
1749         case NETLINK_BROADCAST_ERROR:
1750                 if (len < sizeof(int))
1751                         return -EINVAL;
1752                 len = sizeof(int);
1753                 val = nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR ? 1 : 0;
1754                 if (put_user(len, optlen) ||
1755                     put_user(val, optval))
1756                         return -EFAULT;
1757                 err = 0;
1758                 break;
1759         case NETLINK_NO_ENOBUFS:
1760                 if (len < sizeof(int))
1761                         return -EINVAL;
1762                 len = sizeof(int);
1763                 val = nlk->flags & NETLINK_F_RECV_NO_ENOBUFS ? 1 : 0;
1764                 if (put_user(len, optlen) ||
1765                     put_user(val, optval))
1766                         return -EFAULT;
1767                 err = 0;
1768                 break;
1769         case NETLINK_LIST_MEMBERSHIPS: {
1770                 int pos, idx, shift;
1771 
1772                 err = 0;
1773                 netlink_lock_table();
1774                 for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
1775                         if (len - pos < sizeof(u32))
1776                                 break;
1777 
1778                         idx = pos / sizeof(unsigned long);
1779                         shift = (pos % sizeof(unsigned long)) * 8;
1780                         if (put_user((u32)(nlk->groups[idx] >> shift),
1781                                      (u32 __user *)(optval + pos))) {
1782                                 err = -EFAULT;
1783                                 break;
1784                         }
1785                 }
1786                 if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
1787                         err = -EFAULT;
1788                 netlink_unlock_table();
1789                 break;
1790         }
1791         case NETLINK_CAP_ACK:
1792                 if (len < sizeof(int))
1793                         return -EINVAL;
1794                 len = sizeof(int);
1795                 val = nlk->flags & NETLINK_F_CAP_ACK ? 1 : 0;
1796                 if (put_user(len, optlen) ||
1797                     put_user(val, optval))
1798                         return -EFAULT;
1799                 err = 0;
1800                 break;
1801         case NETLINK_EXT_ACK:
1802                 if (len < sizeof(int))
1803                         return -EINVAL;
1804                 len = sizeof(int);
1805                 val = nlk->flags & NETLINK_F_EXT_ACK ? 1 : 0;
1806                 if (put_user(len, optlen) || put_user(val, optval))
1807                         return -EFAULT;
1808                 err = 0;
1809                 break;
1810         case NETLINK_GET_STRICT_CHK:
1811                 if (len < sizeof(int))
1812                         return -EINVAL;
1813                 len = sizeof(int);
1814                 val = nlk->flags & NETLINK_F_STRICT_CHK ? 1 : 0;
1815                 if (put_user(len, optlen) || put_user(val, optval))
1816                         return -EFAULT;
1817                 err = 0;
1818                 break;
1819         default:
1820                 err = -ENOPROTOOPT;
1821         }
1822         return err;
1823 }
1824 
1825 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
1826 {
1827         struct nl_pktinfo info;
1828 
1829         info.group = NETLINK_CB(skb).dst_group;
1830         put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
1831 }
1832 
1833 static void netlink_cmsg_listen_all_nsid(struct sock *sk, struct msghdr *msg,
1834                                          struct sk_buff *skb)
1835 {
1836         if (!NETLINK_CB(skb).nsid_is_set)
1837                 return;
1838 
1839         put_cmsg(msg, SOL_NETLINK, NETLINK_LISTEN_ALL_NSID, sizeof(int),
1840                  &NETLINK_CB(skb).nsid);
1841 }
1842 
1843 static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
1844 {
1845         struct sock *sk = sock->sk;
1846         struct netlink_sock *nlk = nlk_sk(sk);
1847         DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1848         u32 dst_portid;
1849         u32 dst_group;
1850         struct sk_buff *skb;
1851         int err;
1852         struct scm_cookie scm;
1853         u32 netlink_skb_flags = 0;
1854 
1855         if (msg->msg_flags&MSG_OOB)
1856                 return -EOPNOTSUPP;
1857 
1858         err = scm_send(sock, msg, &scm, true);
1859         if (err < 0)
1860                 return err;
1861 
1862         if (msg->msg_namelen) {
1863                 err = -EINVAL;
1864                 if (msg->msg_namelen < sizeof(struct sockaddr_nl))
1865                         goto out;
1866                 if (addr->nl_family != AF_NETLINK)
1867                         goto out;
1868                 dst_portid = addr->nl_pid;
1869                 dst_group = ffs(addr->nl_groups);
1870                 err =  -EPERM;
1871                 if ((dst_group || dst_portid) &&
1872                     !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1873                         goto out;
1874                 netlink_skb_flags |= NETLINK_SKB_DST;
1875         } else {
1876                 dst_portid = nlk->dst_portid;
1877                 dst_group = nlk->dst_group;
1878         }
1879 
1880         if (!nlk->bound) {
1881                 err = netlink_autobind(sock);
1882                 if (err)
1883                         goto out;
1884         } else {
1885                 /* Ensure nlk is hashed and visible. */
1886                 smp_rmb();
1887         }
1888 
1889         err = -EMSGSIZE;
1890         if (len > sk->sk_sndbuf - 32)
1891                 goto out;
1892         err = -ENOBUFS;
1893         skb = netlink_alloc_large_skb(len, dst_group);
1894         if (skb == NULL)
1895                 goto out;
1896 
1897         NETLINK_CB(skb).portid  = nlk->portid;
1898         NETLINK_CB(skb).dst_group = dst_group;
1899         NETLINK_CB(skb).creds   = scm.creds;
1900         NETLINK_CB(skb).flags   = netlink_skb_flags;
1901 
1902         err = -EFAULT;
1903         if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
1904                 kfree_skb(skb);
1905                 goto out;
1906         }
1907 
1908         err = security_netlink_send(sk, skb);
1909         if (err) {
1910                 kfree_skb(skb);
1911                 goto out;
1912         }
1913 
1914         if (dst_group) {
1915                 refcount_inc(&skb->users);
1916                 netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
1917         }
1918         err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT);
1919 
1920 out:
1921         scm_destroy(&scm);
1922         return err;
1923 }
1924 
1925 static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
1926                            int flags)
1927 {
1928         struct scm_cookie scm;
1929         struct sock *sk = sock->sk;
1930         struct netlink_sock *nlk = nlk_sk(sk);
1931         int noblock = flags&MSG_DONTWAIT;
1932         size_t copied;
1933         struct sk_buff *skb, *data_skb;
1934         int err, ret;
1935 
1936         if (flags&MSG_OOB)
1937                 return -EOPNOTSUPP;
1938 
1939         copied = 0;
1940 
1941         skb = skb_recv_datagram(sk, flags, noblock, &err);
1942         if (skb == NULL)
1943                 goto out;
1944 
1945         data_skb = skb;
1946 
1947 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES
1948         if (unlikely(skb_shinfo(skb)->frag_list)) {
1949                 /*
1950                  * If this skb has a frag_list, then here that means that we
1951                  * will have to use the frag_list skb's data for compat tasks
1952                  * and the regular skb's data for normal (non-compat) tasks.
1953                  *
1954                  * If we need to send the compat skb, assign it to the
1955                  * 'data_skb' variable so that it will be used below for data
1956                  * copying. We keep 'skb' for everything else, including
1957                  * freeing both later.
1958                  */
1959                 if (flags & MSG_CMSG_COMPAT)
1960                         data_skb = skb_shinfo(skb)->frag_list;
1961         }
1962 #endif
1963 
1964         /* Record the max length of recvmsg() calls for future allocations */
1965         nlk->max_recvmsg_len = max(nlk->max_recvmsg_len, len);
1966         nlk->max_recvmsg_len = min_t(size_t, nlk->max_recvmsg_len,
1967                                      SKB_WITH_OVERHEAD(32768));
1968 
1969         copied = data_skb->len;
1970         if (len < copied) {
1971                 msg->msg_flags |= MSG_TRUNC;
1972                 copied = len;
1973         }
1974 
1975         skb_reset_transport_header(data_skb);
1976         err = skb_copy_datagram_msg(data_skb, 0, msg, copied);
1977 
1978         if (msg->msg_name) {
1979                 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1980                 addr->nl_family = AF_NETLINK;
1981                 addr->nl_pad    = 0;
1982                 addr->nl_pid    = NETLINK_CB(skb).portid;
1983                 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
1984                 msg->msg_namelen = sizeof(*addr);
1985         }
1986 
1987         if (nlk->flags & NETLINK_F_RECV_PKTINFO)
1988                 netlink_cmsg_recv_pktinfo(msg, skb);
1989         if (nlk->flags & NETLINK_F_LISTEN_ALL_NSID)
1990                 netlink_cmsg_listen_all_nsid(sk, msg, skb);
1991 
1992         memset(&scm, 0, sizeof(scm));
1993         scm.creds = *NETLINK_CREDS(skb);
1994         if (flags & MSG_TRUNC)
1995                 copied = data_skb->len;
1996 
1997         skb_free_datagram(sk, skb);
1998 
1999         if (nlk->cb_running &&
2000             atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
2001                 ret = netlink_dump(sk);
2002                 if (ret) {
2003                         sk->sk_err = -ret;
2004                         sk->sk_error_report(sk);
2005                 }
2006         }
2007 
2008         scm_recv(sock, msg, &scm, flags);
2009 out:
2010         netlink_rcv_wake(sk);
2011         return err ? : copied;
2012 }
2013 
2014 static void netlink_data_ready(struct sock *sk)
2015 {
2016         BUG();
2017 }
2018 
2019 /*
2020  *      We export these functions to other modules. They provide a
2021  *      complete set of kernel non-blocking support for message
2022  *      queueing.
2023  */
2024 
2025 struct sock *
2026 __netlink_kernel_create(struct net *net, int unit, struct module *module,
2027                         struct netlink_kernel_cfg *cfg)
2028 {
2029         struct socket *sock;
2030         struct sock *sk;
2031         struct netlink_sock *nlk;
2032         struct listeners *listeners = NULL;
2033         struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL;
2034         unsigned int groups;
2035 
2036         BUG_ON(!nl_table);
2037 
2038         if (unit < 0 || unit >= MAX_LINKS)
2039                 return NULL;
2040 
2041         if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
2042                 return NULL;
2043 
2044         if (__netlink_create(net, sock, cb_mutex, unit, 1) < 0)
2045                 goto out_sock_release_nosk;
2046 
2047         sk = sock->sk;
2048 
2049         if (!cfg || cfg->groups < 32)
2050                 groups = 32;
2051         else
2052                 groups = cfg->groups;
2053 
2054         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2055         if (!listeners)
2056                 goto out_sock_release;
2057 
2058         sk->sk_data_ready = netlink_data_ready;
2059         if (cfg && cfg->input)
2060                 nlk_sk(sk)->netlink_rcv = cfg->input;
2061 
2062         if (netlink_insert(sk, 0))
2063                 goto out_sock_release;
2064 
2065         nlk = nlk_sk(sk);
2066         nlk->flags |= NETLINK_F_KERNEL_SOCKET;
2067 
2068         netlink_table_grab();
2069         if (!nl_table[unit].registered) {
2070                 nl_table[unit].groups = groups;
2071                 rcu_assign_pointer(nl_table[unit].listeners, listeners);
2072                 nl_table[unit].cb_mutex = cb_mutex;
2073                 nl_table[unit].module = module;
2074                 if (cfg) {
2075                         nl_table[unit].bind = cfg->bind;
2076                         nl_table[unit].unbind = cfg->unbind;
2077                         nl_table[unit].flags = cfg->flags;
2078                         if (cfg->compare)
2079                                 nl_table[unit].compare = cfg->compare;
2080                 }
2081                 nl_table[unit].registered = 1;
2082         } else {
2083                 kfree(listeners);
2084                 nl_table[unit].registered++;
2085         }
2086         netlink_table_ungrab();
2087         return sk;
2088 
2089 out_sock_release:
2090         kfree(listeners);
2091         netlink_kernel_release(sk);
2092         return NULL;
2093 
2094 out_sock_release_nosk:
2095         sock_release(sock);
2096         return NULL;
2097 }
2098 EXPORT_SYMBOL(__netlink_kernel_create);
2099 
2100 void
2101 netlink_kernel_release(struct sock *sk)
2102 {
2103         if (sk == NULL || sk->sk_socket == NULL)
2104                 return;
2105 
2106         sock_release(sk->sk_socket);
2107 }
2108 EXPORT_SYMBOL(netlink_kernel_release);
2109 
2110 int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
2111 {
2112         struct listeners *new, *old;
2113         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
2114 
2115         if (groups < 32)
2116                 groups = 32;
2117 
2118         if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
2119                 new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
2120                 if (!new)
2121                         return -ENOMEM;
2122                 old = nl_deref_protected(tbl->listeners);
2123                 memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
2124                 rcu_assign_pointer(tbl->listeners, new);
2125 
2126                 kfree_rcu(old, rcu);
2127         }
2128         tbl->groups = groups;
2129 
2130         return 0;
2131 }
2132 
2133 /**
2134  * netlink_change_ngroups - change number of multicast groups
2135  *
2136  * This changes the number of multicast groups that are available
2137  * on a certain netlink family. Note that it is not possible to
2138  * change the number of groups to below 32. Also note that it does
2139  * not implicitly call netlink_clear_multicast_users() when the
2140  * number of groups is reduced.
2141  *
2142  * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
2143  * @groups: The new number of groups.
2144  */
2145 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
2146 {
2147         int err;
2148 
2149         netlink_table_grab();
2150         err = __netlink_change_ngroups(sk, groups);
2151         netlink_table_ungrab();
2152 
2153         return err;
2154 }
2155 
2156 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
2157 {
2158         struct sock *sk;
2159         struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
2160 
2161         sk_for_each_bound(sk, &tbl->mc_list)
2162                 netlink_update_socket_mc(nlk_sk(sk), group, 0);
2163 }
2164 
2165 struct nlmsghdr *
2166 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
2167 {
2168         struct nlmsghdr *nlh;
2169         int size = nlmsg_msg_size(len);
2170 
2171         nlh = skb_put(skb, NLMSG_ALIGN(size));
2172         nlh->nlmsg_type = type;
2173         nlh->nlmsg_len = size;
2174         nlh->nlmsg_flags = flags;
2175         nlh->nlmsg_pid = portid;
2176         nlh->nlmsg_seq = seq;
2177         if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
2178                 memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
2179         return nlh;
2180 }
2181 EXPORT_SYMBOL(__nlmsg_put);
2182 
2183 /*
2184  * It looks a bit ugly.
2185  * It would be better to create kernel thread.
2186  */
2187 
2188 static int netlink_dump(struct sock *sk)
2189 {
2190         struct netlink_sock *nlk = nlk_sk(sk);
2191         struct netlink_ext_ack extack = {};
2192         struct netlink_callback *cb;
2193         struct sk_buff *skb = NULL;
2194         struct nlmsghdr *nlh;
2195         struct module *module;
2196         int err = -ENOBUFS;
2197         int alloc_min_size;
2198         int alloc_size;
2199 
2200         mutex_lock(nlk->cb_mutex);
2201         if (!nlk->cb_running) {
2202                 err = -EINVAL;
2203                 goto errout_skb;
2204         }
2205 
2206         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
2207                 goto errout_skb;
2208 
2209         /* NLMSG_GOODSIZE is small to avoid high order allocations being
2210          * required, but it makes sense to _attempt_ a 16K bytes allocation
2211          * to reduce number of system calls on dump operations, if user
2212          * ever provided a big enough buffer.
2213          */
2214         cb = &nlk->cb;
2215         alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
2216 
2217         if (alloc_min_size < nlk->max_recvmsg_len) {
2218                 alloc_size = nlk->max_recvmsg_len;
2219                 skb = alloc_skb(alloc_size,
2220                                 (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) |
2221                                 __GFP_NOWARN | __GFP_NORETRY);
2222         }
2223         if (!skb) {
2224                 alloc_size = alloc_min_size;
2225                 skb = alloc_skb(alloc_size, GFP_KERNEL);
2226         }
2227         if (!skb)
2228                 goto errout_skb;
2229 
2230         /* Trim skb to allocated size. User is expected to provide buffer as
2231          * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at
2232          * netlink_recvmsg())). dump will pack as many smaller messages as
2233          * could fit within the allocated skb. skb is typically allocated
2234          * with larger space than required (could be as much as near 2x the
2235          * requested size with align to next power of 2 approach). Allowing
2236          * dump to use the excess space makes it difficult for a user to have a
2237          * reasonable static buffer based on the expected largest dump of a
2238          * single netdev. The outcome is MSG_TRUNC error.
2239          */
2240         skb_reserve(skb, skb_tailroom(skb) - alloc_size);
2241         netlink_skb_set_owner_r(skb, sk);
2242 
2243         if (nlk->dump_done_errno > 0) {
2244                 cb->extack = &extack;
2245                 nlk->dump_done_errno = cb->dump(skb, cb);
2246                 cb->extack = NULL;
2247         }
2248 
2249         if (nlk->dump_done_errno > 0 ||
2250             skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) {
2251                 mutex_unlock(nlk->cb_mutex);
2252 
2253                 if (sk_filter(sk, skb))
2254                         kfree_skb(skb);
2255                 else
2256                         __netlink_sendskb(sk, skb);
2257                 return 0;
2258         }
2259 
2260         nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE,
2261                                sizeof(nlk->dump_done_errno),
2262                                NLM_F_MULTI | cb->answer_flags);
2263         if (WARN_ON(!nlh))
2264                 goto errout_skb;
2265 
2266         nl_dump_check_consistent(cb, nlh);
2267 
2268         memcpy(nlmsg_data(nlh), &nlk->dump_done_errno,
2269                sizeof(nlk->dump_done_errno));
2270 
2271         if (extack._msg && nlk->flags & NETLINK_F_EXT_ACK) {
2272                 nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
2273                 if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack._msg))
2274                         nlmsg_end(skb, nlh);
2275         }
2276 
2277         if (sk_filter(sk, skb))
2278                 kfree_skb(skb);
2279         else
2280                 __netlink_sendskb(sk, skb);
2281 
2282         if (cb->done)
2283                 cb->done(cb);
2284 
2285         nlk->cb_running = false;
2286         module = cb->module;
2287         skb = cb->skb;
2288         mutex_unlock(nlk->cb_mutex);
2289         module_put(module);
2290         consume_skb(skb);
2291         return 0;
2292 
2293 errout_skb:
2294         mutex_unlock(nlk->cb_mutex);
2295         kfree_skb(skb);
2296         return err;
2297 }
2298 
2299 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
2300                          const struct nlmsghdr *nlh,
2301                          struct netlink_dump_control *control)
2302 {
2303         struct netlink_sock *nlk, *nlk2;
2304         struct netlink_callback *cb;
2305         struct sock *sk;
2306         int ret;
2307 
2308         refcount_inc(&skb->users);
2309 
2310         sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
2311         if (sk == NULL) {
2312                 ret = -ECONNREFUSED;
2313                 goto error_free;
2314         }
2315 
2316         nlk = nlk_sk(sk);
2317         mutex_lock(nlk->cb_mutex);
2318         /* A dump is in progress... */
2319         if (nlk->cb_running) {
2320                 ret = -EBUSY;
2321                 goto error_unlock;
2322         }
2323         /* add reference of module which cb->dump belongs to */
2324         if (!try_module_get(control->module)) {
2325                 ret = -EPROTONOSUPPORT;
2326                 goto error_unlock;
2327         }
2328 
2329         cb = &nlk->cb;
2330         memset(cb, 0, sizeof(*cb));
2331         cb->dump = control->dump;
2332         cb->done = control->done;
2333         cb->nlh = nlh;
2334         cb->data = control->data;
2335         cb->module = control->module;
2336         cb->min_dump_alloc = control->min_dump_alloc;
2337         cb->skb = skb;
2338 
2339         nlk2 = nlk_sk(NETLINK_CB(skb).sk);
2340         cb->strict_check = !!(nlk2->flags & NETLINK_F_STRICT_CHK);
2341 
2342         if (control->start) {
2343                 ret = control->start(cb);
2344                 if (ret)
2345                         goto error_put;
2346         }
2347 
2348         nlk->cb_running = true;
2349         nlk->dump_done_errno = INT_MAX;
2350 
2351         mutex_unlock(nlk->cb_mutex);
2352 
2353         ret = netlink_dump(sk);
2354 
2355         sock_put(sk);
2356 
2357         if (ret)
2358                 return ret;
2359 
2360         /* We successfully started a dump, by returning -EINTR we
2361          * signal not to send ACK even if it was requested.
2362          */
2363         return -EINTR;
2364 
2365 error_put:
2366         module_put(control->module);
2367 error_unlock:
2368         sock_put(sk);
2369         mutex_unlock(nlk->cb_mutex);
2370 error_free:
2371         kfree_skb(skb);
2372         return ret;
2373 }
2374 EXPORT_SYMBOL(__netlink_dump_start);
2375 
2376 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
2377                  const struct netlink_ext_ack *extack)
2378 {
2379         struct sk_buff *skb;
2380         struct nlmsghdr *rep;
2381         struct nlmsgerr *errmsg;
2382         size_t payload = sizeof(*errmsg);
2383         size_t tlvlen = 0;
2384         struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
2385         unsigned int flags = 0;
2386         bool nlk_has_extack = nlk->flags & NETLINK_F_EXT_ACK;
2387 
2388         /* Error messages get the original request appened, unless the user
2389          * requests to cap the error message, and get extra error data if
2390          * requested.
2391          */
2392         if (nlk_has_extack && extack && extack->_msg)
2393                 tlvlen += nla_total_size(strlen(extack->_msg) + 1);
2394 
2395         if (err) {
2396                 if (!(nlk->flags & NETLINK_F_CAP_ACK))
2397                         payload += nlmsg_len(nlh);
2398                 else
2399                         flags |= NLM_F_CAPPED;
2400                 if (nlk_has_extack && extack && extack->bad_attr)
2401                         tlvlen += nla_total_size(sizeof(u32));
2402         } else {
2403                 flags |= NLM_F_CAPPED;
2404 
2405                 if (nlk_has_extack && extack && extack->cookie_len)
2406                         tlvlen += nla_total_size(extack->cookie_len);
2407         }
2408 
2409         if (tlvlen)
2410                 flags |= NLM_F_ACK_TLVS;
2411 
2412         skb = nlmsg_new(payload + tlvlen, GFP_KERNEL);
2413         if (!skb) {
2414                 NETLINK_CB(in_skb).sk->sk_err = ENOBUFS;
2415                 NETLINK_CB(in_skb).sk->sk_error_report(NETLINK_CB(in_skb).sk);
2416                 return;
2417         }
2418 
2419         rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2420                           NLMSG_ERROR, payload, flags);
2421         errmsg = nlmsg_data(rep);
2422         errmsg->error = err;
2423         memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
2424 
2425         if (nlk_has_extack && extack) {
2426                 if (extack->_msg) {
2427                         WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
2428                                                extack->_msg));
2429                 }
2430                 if (err) {
2431                         if (extack->bad_attr &&
2432                             !WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
2433                                      (u8 *)extack->bad_attr >= in_skb->data +
2434                                                                in_skb->len))
2435                                 WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
2436                                                     (u8 *)extack->bad_attr -
2437                                                     (u8 *)nlh));
2438                 } else {
2439                         if (extack->cookie_len)
2440                                 WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
2441                                                 extack->cookie_len,
2442                                                 extack->cookie));
2443                 }
2444         }
2445 
2446         nlmsg_end(skb, rep);
2447 
2448         netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);
2449 }
2450 EXPORT_SYMBOL(netlink_ack);
2451 
2452 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
2453                                                    struct nlmsghdr *,
2454                                                    struct netlink_ext_ack *))
2455 {
2456         struct netlink_ext_ack extack;
2457         struct nlmsghdr *nlh;
2458         int err;
2459 
2460         while (skb->len >= nlmsg_total_size(0)) {
2461                 int msglen;
2462 
2463                 memset(&extack, 0, sizeof(extack));
2464                 nlh = nlmsg_hdr(skb);
2465                 err = 0;
2466 
2467                 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
2468                         return 0;
2469 
2470                 /* Only requests are handled by the kernel */
2471                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
2472                         goto ack;
2473 
2474                 /* Skip control messages */
2475                 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
2476                         goto ack;
2477 
2478                 err = cb(skb, nlh, &extack);
2479                 if (err == -EINTR)
2480                         goto skip;
2481 
2482 ack:
2483                 if (nlh->nlmsg_flags & NLM_F_ACK || err)
2484                         netlink_ack(skb, nlh, err, &extack);
2485 
2486 skip:
2487                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
2488                 if (msglen > skb->len)
2489                         msglen = skb->len;
2490                 skb_pull(skb, msglen);
2491         }
2492 
2493         return 0;
2494 }
2495 EXPORT_SYMBOL(netlink_rcv_skb);
2496 
2497 /**
2498  * nlmsg_notify - send a notification netlink message
2499  * @sk: netlink socket to use
2500  * @skb: notification message
2501  * @portid: destination netlink portid for reports or 0
2502  * @group: destination multicast group or 0
2503  * @report: 1 to report back, 0 to disable
2504  * @flags: allocation flags
2505  */
2506 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
2507                  unsigned int group, int report, gfp_t flags)
2508 {
2509         int err = 0;
2510 
2511         if (group) {
2512                 int exclude_portid = 0;
2513 
2514                 if (report) {
2515                         refcount_inc(&skb->users);
2516                         exclude_portid = portid;
2517                 }
2518 
2519                 /* errors reported via destination sk->sk_err, but propagate
2520                  * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
2521                 err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
2522         }
2523 
2524         if (report) {
2525                 int err2;
2526 
2527                 err2 = nlmsg_unicast(sk, skb, portid);
2528                 if (!err || err == -ESRCH)
2529                         err = err2;
2530         }
2531 
2532         return err;
2533 }
2534 EXPORT_SYMBOL(nlmsg_notify);
2535 
2536 #ifdef CONFIG_PROC_FS
2537 struct nl_seq_iter {
2538         struct seq_net_private p;
2539         struct rhashtable_iter hti;
2540         int link;
2541 };
2542 
2543 static void netlink_walk_start(struct nl_seq_iter *iter)
2544 {
2545         rhashtable_walk_enter(&nl_table[iter->link].hash, &iter->hti);
2546         rhashtable_walk_start(&iter->hti);
2547 }
2548 
2549 static void netlink_walk_stop(struct nl_seq_iter *iter)
2550 {
2551         rhashtable_walk_stop(&iter->hti);
2552         rhashtable_walk_exit(&iter->hti);
2553 }
2554 
2555 static void *__netlink_seq_next(struct seq_file *seq)
2556 {
2557         struct nl_seq_iter *iter = seq->private;
2558         struct netlink_sock *nlk;
2559 
2560         do {
2561                 for (;;) {
2562                         nlk = rhashtable_walk_next(&iter->hti);
2563 
2564                         if (IS_ERR(nlk)) {
2565                                 if (PTR_ERR(nlk) == -EAGAIN)
2566                                         continue;
2567 
2568                                 return nlk;
2569                         }
2570 
2571                         if (nlk)
2572                                 break;
2573 
2574                         netlink_walk_stop(iter);
2575                         if (++iter->link >= MAX_LINKS)
2576                                 return NULL;
2577 
2578                         netlink_walk_start(iter);
2579                 }
2580         } while (sock_net(&nlk->sk) != seq_file_net(seq));
2581 
2582         return nlk;
2583 }
2584 
2585 static void *netlink_seq_start(struct seq_file *seq, loff_t *posp)
2586 {
2587         struct nl_seq_iter *iter = seq->private;
2588         void *obj = SEQ_START_TOKEN;
2589         loff_t pos;
2590 
2591         iter->link = 0;
2592 
2593         netlink_walk_start(iter);
2594 
2595         for (pos = *posp; pos && obj && !IS_ERR(obj); pos--)
2596                 obj = __netlink_seq_next(seq);
2597 
2598         return obj;
2599 }
2600 
2601 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2602 {
2603         ++*pos;
2604         return __netlink_seq_next(seq);
2605 }
2606 
2607 static void netlink_seq_stop(struct seq_file *seq, void *v)
2608 {
2609         struct nl_seq_iter *iter = seq->private;
2610 
2611         if (iter->link >= MAX_LINKS)
2612                 return;
2613 
2614         netlink_walk_stop(iter);
2615 }
2616 
2617 
2618 static int netlink_seq_show(struct seq_file *seq, void *v)
2619 {
2620         if (v == SEQ_START_TOKEN) {
2621                 seq_puts(seq,
2622                          "sk               Eth Pid        Groups   "
2623                          "Rmem     Wmem     Dump  Locks    Drops    Inode\n");
2624         } else {
2625                 struct sock *s = v;
2626                 struct netlink_sock *nlk = nlk_sk(s);
2627 
2628                 seq_printf(seq, "%pK %-3d %-10u %08x %-8d %-8d %-5d %-8d %-8u %-8lu\n",
2629                            s,
2630                            s->sk_protocol,
2631                            nlk->portid,
2632                            nlk->groups ? (u32)nlk->groups[0] : 0,
2633                            sk_rmem_alloc_get(s),
2634                            sk_wmem_alloc_get(s),
2635                            nlk->cb_running,
2636                            refcount_read(&s->sk_refcnt),
2637                            atomic_read(&s->sk_drops),
2638                            sock_i_ino(s)
2639                         );
2640 
2641         }
2642         return 0;
2643 }
2644 
2645 static const struct seq_operations netlink_seq_ops = {
2646         .start  = netlink_seq_start,
2647         .next   = netlink_seq_next,
2648         .stop   = netlink_seq_stop,
2649         .show   = netlink_seq_show,
2650 };
2651 #endif
2652 
2653 int netlink_register_notifier(struct notifier_block *nb)
2654 {
2655         return blocking_notifier_chain_register(&netlink_chain, nb);
2656 }
2657 EXPORT_SYMBOL(netlink_register_notifier);
2658 
2659 int netlink_unregister_notifier(struct notifier_block *nb)
2660 {
2661         return blocking_notifier_chain_unregister(&netlink_chain, nb);
2662 }
2663 EXPORT_SYMBOL(netlink_unregister_notifier);
2664 
2665 static const struct proto_ops netlink_ops = {
2666         .family =       PF_NETLINK,
2667         .owner =        THIS_MODULE,
2668         .release =      netlink_release,
2669         .bind =         netlink_bind,
2670         .connect =      netlink_connect,
2671         .socketpair =   sock_no_socketpair,
2672         .accept =       sock_no_accept,
2673         .getname =      netlink_getname,
2674         .poll =         datagram_poll,
2675         .ioctl =        netlink_ioctl,
2676         .listen =       sock_no_listen,
2677         .shutdown =     sock_no_shutdown,
2678         .setsockopt =   netlink_setsockopt,
2679         .getsockopt =   netlink_getsockopt,
2680         .sendmsg =      netlink_sendmsg,
2681         .recvmsg =      netlink_recvmsg,
2682         .mmap =         sock_no_mmap,
2683         .sendpage =     sock_no_sendpage,
2684 };
2685 
2686 static const struct net_proto_family netlink_family_ops = {
2687         .family = PF_NETLINK,
2688         .create = netlink_create,
2689         .owner  = THIS_MODULE,  /* for consistency 8) */
2690 };
2691 
2692 static int __net_init netlink_net_init(struct net *net)
2693 {
2694 #ifdef CONFIG_PROC_FS
2695         if (!proc_create_net("netlink", 0, net->proc_net, &netlink_seq_ops,
2696                         sizeof(struct nl_seq_iter)))
2697                 return -ENOMEM;
2698 #endif
2699         return 0;
2700 }
2701 
2702 static void __net_exit netlink_net_exit(struct net *net)
2703 {
2704 #ifdef CONFIG_PROC_FS
2705         remove_proc_entry("netlink", net->proc_net);
2706 #endif
2707 }
2708 
2709 static void __init netlink_add_usersock_entry(void)
2710 {
2711         struct listeners *listeners;
2712         int groups = 32;
2713 
2714         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2715         if (!listeners)
2716                 panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
2717 
2718         netlink_table_grab();
2719 
2720         nl_table[NETLINK_USERSOCK].groups = groups;
2721         rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
2722         nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
2723         nl_table[NETLINK_USERSOCK].registered = 1;
2724         nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND;
2725 
2726         netlink_table_ungrab();
2727 }
2728 
2729 static struct pernet_operations __net_initdata netlink_net_ops = {
2730         .init = netlink_net_init,
2731         .exit = netlink_net_exit,
2732 };
2733 
2734 static inline u32 netlink_hash(const void *data, u32 len, u32 seed)
2735 {
2736         const struct netlink_sock *nlk = data;
2737         struct netlink_compare_arg arg;
2738 
2739         netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
2740         return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
2741 }
2742 
2743 static const struct rhashtable_params netlink_rhashtable_params = {
2744         .head_offset = offsetof(struct netlink_sock, node),
2745         .key_len = netlink_compare_arg_len,
2746         .obj_hashfn = netlink_hash,
2747         .obj_cmpfn = netlink_compare,
2748         .automatic_shrinking = true,
2749 };
2750 
2751 static int __init netlink_proto_init(void)
2752 {
2753         int i;
2754         int err = proto_register(&netlink_proto, 0);
2755 
2756         if (err != 0)
2757                 goto out;
2758 
2759         BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
2760 
2761         nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
2762         if (!nl_table)
2763                 goto panic;
2764 
2765         for (i = 0; i < MAX_LINKS; i++) {
2766                 if (rhashtable_init(&nl_table[i].hash,
2767                                     &netlink_rhashtable_params) < 0) {
2768                         while (--i > 0)
2769                                 rhashtable_destroy(&nl_table[i].hash);
2770                         kfree(nl_table);
2771                         goto panic;
2772                 }
2773         }
2774 
2775         netlink_add_usersock_entry();
2776 
2777         sock_register(&netlink_family_ops);
2778         register_pernet_subsys(&netlink_net_ops);
2779         register_pernet_subsys(&netlink_tap_net_ops);
2780         /* The netlink device handler may be needed early. */
2781         rtnetlink_init();
2782 out:
2783         return err;
2784 panic:
2785         panic("netlink_init: Cannot allocate nl_table\n");
2786 }
2787 
2788 core_initcall(netlink_proto_init);

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