1 /* 2 * NETLINK Kernel-user communication protocol. 3 * 4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk> 5 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 * 12 * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith 13 * added netlink_proto_exit 14 * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br> 15 * use nlk_sk, as sk->protinfo is on a diet 8) 16 * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org> 17 * - inc module use count of module that owns 18 * the kernel socket in case userspace opens 19 * socket of same protocol 20 * - remove all module support, since netlink is 21 * mandatory if CONFIG_NET=y these days 22 */ 23 24 #include <linux/module.h> 25 26 #include <linux/capability.h> 27 #include <linux/kernel.h> 28 #include <linux/init.h> 29 #include <linux/signal.h> 30 #include <linux/sched.h> 31 #include <linux/errno.h> 32 #include <linux/string.h> 33 #include <linux/stat.h> 34 #include <linux/socket.h> 35 #include <linux/un.h> 36 #include <linux/fcntl.h> 37 #include <linux/termios.h> 38 #include <linux/sockios.h> 39 #include <linux/net.h> 40 #include <linux/fs.h> 41 #include <linux/slab.h> 42 #include <asm/uaccess.h> 43 #include <linux/skbuff.h> 44 #include <linux/netdevice.h> 45 #include <linux/rtnetlink.h> 46 #include <linux/proc_fs.h> 47 #include <linux/seq_file.h> 48 #include <linux/notifier.h> 49 #include <linux/security.h> 50 #include <linux/jhash.h> 51 #include <linux/jiffies.h> 52 #include <linux/random.h> 53 #include <linux/bitops.h> 54 #include <linux/mm.h> 55 #include <linux/types.h> 56 #include <linux/audit.h> 57 #include <linux/mutex.h> 58 59 #include <net/net_namespace.h> 60 #include <net/sock.h> 61 #include <net/scm.h> 62 #include <net/netlink.h> 63 64 #define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8) 65 #define NLGRPLONGS(x) (NLGRPSZ(x)/sizeof(unsigned long)) 66 67 struct netlink_sock { 68 /* struct sock has to be the first member of netlink_sock */ 69 struct sock sk; 70 u32 pid; 71 u32 dst_pid; 72 u32 dst_group; 73 u32 flags; 74 u32 subscriptions; 75 u32 ngroups; 76 unsigned long *groups; 77 unsigned long state; 78 wait_queue_head_t wait; 79 struct netlink_callback *cb; 80 struct mutex *cb_mutex; 81 struct mutex cb_def_mutex; 82 void (*netlink_rcv)(struct sk_buff *skb); 83 struct module *module; 84 }; 85 86 struct listeners_rcu_head { 87 struct rcu_head rcu_head; 88 void *ptr; 89 }; 90 91 #define NETLINK_KERNEL_SOCKET 0x1 92 #define NETLINK_RECV_PKTINFO 0x2 93 #define NETLINK_BROADCAST_SEND_ERROR 0x4 94 #define NETLINK_RECV_NO_ENOBUFS 0x8 95 96 static inline struct netlink_sock *nlk_sk(struct sock *sk) 97 { 98 return container_of(sk, struct netlink_sock, sk); 99 } 100 101 static inline int netlink_is_kernel(struct sock *sk) 102 { 103 return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET; 104 } 105 106 struct nl_pid_hash { 107 struct hlist_head *table; 108 unsigned long rehash_time; 109 110 unsigned int mask; 111 unsigned int shift; 112 113 unsigned int entries; 114 unsigned int max_shift; 115 116 u32 rnd; 117 }; 118 119 struct netlink_table { 120 struct nl_pid_hash hash; 121 struct hlist_head mc_list; 122 unsigned long *listeners; 123 unsigned int nl_nonroot; 124 unsigned int groups; 125 struct mutex *cb_mutex; 126 struct module *module; 127 int registered; 128 }; 129 130 static struct netlink_table *nl_table; 131 132 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait); 133 134 static int netlink_dump(struct sock *sk); 135 static void netlink_destroy_callback(struct netlink_callback *cb); 136 137 static DEFINE_RWLOCK(nl_table_lock); 138 static atomic_t nl_table_users = ATOMIC_INIT(0); 139 140 static ATOMIC_NOTIFIER_HEAD(netlink_chain); 141 142 static u32 netlink_group_mask(u32 group) 143 { 144 return group ? 1 << (group - 1) : 0; 145 } 146 147 static struct hlist_head *nl_pid_hashfn(struct nl_pid_hash *hash, u32 pid) 148 { 149 return &hash->table[jhash_1word(pid, hash->rnd) & hash->mask]; 150 } 151 152 static void netlink_sock_destruct(struct sock *sk) 153 { 154 struct netlink_sock *nlk = nlk_sk(sk); 155 156 if (nlk->cb) { 157 if (nlk->cb->done) 158 nlk->cb->done(nlk->cb); 159 netlink_destroy_callback(nlk->cb); 160 } 161 162 skb_queue_purge(&sk->sk_receive_queue); 163 164 if (!sock_flag(sk, SOCK_DEAD)) { 165 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk); 166 return; 167 } 168 169 WARN_ON(atomic_read(&sk->sk_rmem_alloc)); 170 WARN_ON(atomic_read(&sk->sk_wmem_alloc)); 171 WARN_ON(nlk_sk(sk)->groups); 172 } 173 174 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on 175 * SMP. Look, when several writers sleep and reader wakes them up, all but one 176 * immediately hit write lock and grab all the cpus. Exclusive sleep solves 177 * this, _but_ remember, it adds useless work on UP machines. 178 */ 179 180 void netlink_table_grab(void) 181 __acquires(nl_table_lock) 182 { 183 might_sleep(); 184 185 write_lock_irq(&nl_table_lock); 186 187 if (atomic_read(&nl_table_users)) { 188 DECLARE_WAITQUEUE(wait, current); 189 190 add_wait_queue_exclusive(&nl_table_wait, &wait); 191 for (;;) { 192 set_current_state(TASK_UNINTERRUPTIBLE); 193 if (atomic_read(&nl_table_users) == 0) 194 break; 195 write_unlock_irq(&nl_table_lock); 196 schedule(); 197 write_lock_irq(&nl_table_lock); 198 } 199 200 __set_current_state(TASK_RUNNING); 201 remove_wait_queue(&nl_table_wait, &wait); 202 } 203 } 204 205 void netlink_table_ungrab(void) 206 __releases(nl_table_lock) 207 { 208 write_unlock_irq(&nl_table_lock); 209 wake_up(&nl_table_wait); 210 } 211 212 static inline void 213 netlink_lock_table(void) 214 { 215 /* read_lock() synchronizes us to netlink_table_grab */ 216 217 read_lock(&nl_table_lock); 218 atomic_inc(&nl_table_users); 219 read_unlock(&nl_table_lock); 220 } 221 222 static inline void 223 netlink_unlock_table(void) 224 { 225 if (atomic_dec_and_test(&nl_table_users)) 226 wake_up(&nl_table_wait); 227 } 228 229 static inline struct sock *netlink_lookup(struct net *net, int protocol, 230 u32 pid) 231 { 232 struct nl_pid_hash *hash = &nl_table[protocol].hash; 233 struct hlist_head *head; 234 struct sock *sk; 235 struct hlist_node *node; 236 237 read_lock(&nl_table_lock); 238 head = nl_pid_hashfn(hash, pid); 239 sk_for_each(sk, node, head) { 240 if (net_eq(sock_net(sk), net) && (nlk_sk(sk)->pid == pid)) { 241 sock_hold(sk); 242 goto found; 243 } 244 } 245 sk = NULL; 246 found: 247 read_unlock(&nl_table_lock); 248 return sk; 249 } 250 251 static inline struct hlist_head *nl_pid_hash_zalloc(size_t size) 252 { 253 if (size <= PAGE_SIZE) 254 return kzalloc(size, GFP_ATOMIC); 255 else 256 return (struct hlist_head *) 257 __get_free_pages(GFP_ATOMIC | __GFP_ZERO, 258 get_order(size)); 259 } 260 261 static inline void nl_pid_hash_free(struct hlist_head *table, size_t size) 262 { 263 if (size <= PAGE_SIZE) 264 kfree(table); 265 else 266 free_pages((unsigned long)table, get_order(size)); 267 } 268 269 static int nl_pid_hash_rehash(struct nl_pid_hash *hash, int grow) 270 { 271 unsigned int omask, mask, shift; 272 size_t osize, size; 273 struct hlist_head *otable, *table; 274 int i; 275 276 omask = mask = hash->mask; 277 osize = size = (mask + 1) * sizeof(*table); 278 shift = hash->shift; 279 280 if (grow) { 281 if (++shift > hash->max_shift) 282 return 0; 283 mask = mask * 2 + 1; 284 size *= 2; 285 } 286 287 table = nl_pid_hash_zalloc(size); 288 if (!table) 289 return 0; 290 291 otable = hash->table; 292 hash->table = table; 293 hash->mask = mask; 294 hash->shift = shift; 295 get_random_bytes(&hash->rnd, sizeof(hash->rnd)); 296 297 for (i = 0; i <= omask; i++) { 298 struct sock *sk; 299 struct hlist_node *node, *tmp; 300 301 sk_for_each_safe(sk, node, tmp, &otable[i]) 302 __sk_add_node(sk, nl_pid_hashfn(hash, nlk_sk(sk)->pid)); 303 } 304 305 nl_pid_hash_free(otable, osize); 306 hash->rehash_time = jiffies + 10 * 60 * HZ; 307 return 1; 308 } 309 310 static inline int nl_pid_hash_dilute(struct nl_pid_hash *hash, int len) 311 { 312 int avg = hash->entries >> hash->shift; 313 314 if (unlikely(avg > 1) && nl_pid_hash_rehash(hash, 1)) 315 return 1; 316 317 if (unlikely(len > avg) && time_after(jiffies, hash->rehash_time)) { 318 nl_pid_hash_rehash(hash, 0); 319 return 1; 320 } 321 322 return 0; 323 } 324 325 static const struct proto_ops netlink_ops; 326 327 static void 328 netlink_update_listeners(struct sock *sk) 329 { 330 struct netlink_table *tbl = &nl_table[sk->sk_protocol]; 331 struct hlist_node *node; 332 unsigned long mask; 333 unsigned int i; 334 335 for (i = 0; i < NLGRPLONGS(tbl->groups); i++) { 336 mask = 0; 337 sk_for_each_bound(sk, node, &tbl->mc_list) { 338 if (i < NLGRPLONGS(nlk_sk(sk)->ngroups)) 339 mask |= nlk_sk(sk)->groups[i]; 340 } 341 tbl->listeners[i] = mask; 342 } 343 /* this function is only called with the netlink table "grabbed", which 344 * makes sure updates are visible before bind or setsockopt return. */ 345 } 346 347 static int netlink_insert(struct sock *sk, struct net *net, u32 pid) 348 { 349 struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash; 350 struct hlist_head *head; 351 int err = -EADDRINUSE; 352 struct sock *osk; 353 struct hlist_node *node; 354 int len; 355 356 netlink_table_grab(); 357 head = nl_pid_hashfn(hash, pid); 358 len = 0; 359 sk_for_each(osk, node, head) { 360 if (net_eq(sock_net(osk), net) && (nlk_sk(osk)->pid == pid)) 361 break; 362 len++; 363 } 364 if (node) 365 goto err; 366 367 err = -EBUSY; 368 if (nlk_sk(sk)->pid) 369 goto err; 370 371 err = -ENOMEM; 372 if (BITS_PER_LONG > 32 && unlikely(hash->entries >= UINT_MAX)) 373 goto err; 374 375 if (len && nl_pid_hash_dilute(hash, len)) 376 head = nl_pid_hashfn(hash, pid); 377 hash->entries++; 378 nlk_sk(sk)->pid = pid; 379 sk_add_node(sk, head); 380 err = 0; 381 382 err: 383 netlink_table_ungrab(); 384 return err; 385 } 386 387 static void netlink_remove(struct sock *sk) 388 { 389 netlink_table_grab(); 390 if (sk_del_node_init(sk)) 391 nl_table[sk->sk_protocol].hash.entries--; 392 if (nlk_sk(sk)->subscriptions) 393 __sk_del_bind_node(sk); 394 netlink_table_ungrab(); 395 } 396 397 static struct proto netlink_proto = { 398 .name = "NETLINK", 399 .owner = THIS_MODULE, 400 .obj_size = sizeof(struct netlink_sock), 401 }; 402 403 static int __netlink_create(struct net *net, struct socket *sock, 404 struct mutex *cb_mutex, int protocol) 405 { 406 struct sock *sk; 407 struct netlink_sock *nlk; 408 409 sock->ops = &netlink_ops; 410 411 sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto); 412 if (!sk) 413 return -ENOMEM; 414 415 sock_init_data(sock, sk); 416 417 nlk = nlk_sk(sk); 418 if (cb_mutex) 419 nlk->cb_mutex = cb_mutex; 420 else { 421 nlk->cb_mutex = &nlk->cb_def_mutex; 422 mutex_init(nlk->cb_mutex); 423 } 424 init_waitqueue_head(&nlk->wait); 425 426 sk->sk_destruct = netlink_sock_destruct; 427 sk->sk_protocol = protocol; 428 return 0; 429 } 430 431 static int netlink_create(struct net *net, struct socket *sock, int protocol) 432 { 433 struct module *module = NULL; 434 struct mutex *cb_mutex; 435 struct netlink_sock *nlk; 436 int err = 0; 437 438 sock->state = SS_UNCONNECTED; 439 440 if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM) 441 return -ESOCKTNOSUPPORT; 442 443 if (protocol < 0 || protocol >= MAX_LINKS) 444 return -EPROTONOSUPPORT; 445 446 netlink_lock_table(); 447 #ifdef CONFIG_MODULES 448 if (!nl_table[protocol].registered) { 449 netlink_unlock_table(); 450 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol); 451 netlink_lock_table(); 452 } 453 #endif 454 if (nl_table[protocol].registered && 455 try_module_get(nl_table[protocol].module)) 456 module = nl_table[protocol].module; 457 cb_mutex = nl_table[protocol].cb_mutex; 458 netlink_unlock_table(); 459 460 err = __netlink_create(net, sock, cb_mutex, protocol); 461 if (err < 0) 462 goto out_module; 463 464 local_bh_disable(); 465 sock_prot_inuse_add(net, &netlink_proto, 1); 466 local_bh_enable(); 467 468 nlk = nlk_sk(sock->sk); 469 nlk->module = module; 470 out: 471 return err; 472 473 out_module: 474 module_put(module); 475 goto out; 476 } 477 478 static int netlink_release(struct socket *sock) 479 { 480 struct sock *sk = sock->sk; 481 struct netlink_sock *nlk; 482 483 if (!sk) 484 return 0; 485 486 netlink_remove(sk); 487 sock_orphan(sk); 488 nlk = nlk_sk(sk); 489 490 /* 491 * OK. Socket is unlinked, any packets that arrive now 492 * will be purged. 493 */ 494 495 sock->sk = NULL; 496 wake_up_interruptible_all(&nlk->wait); 497 498 skb_queue_purge(&sk->sk_write_queue); 499 500 if (nlk->pid && !nlk->subscriptions) { 501 struct netlink_notify n = { 502 .net = sock_net(sk), 503 .protocol = sk->sk_protocol, 504 .pid = nlk->pid, 505 }; 506 atomic_notifier_call_chain(&netlink_chain, 507 NETLINK_URELEASE, &n); 508 } 509 510 module_put(nlk->module); 511 512 netlink_table_grab(); 513 if (netlink_is_kernel(sk)) { 514 BUG_ON(nl_table[sk->sk_protocol].registered == 0); 515 if (--nl_table[sk->sk_protocol].registered == 0) { 516 kfree(nl_table[sk->sk_protocol].listeners); 517 nl_table[sk->sk_protocol].module = NULL; 518 nl_table[sk->sk_protocol].registered = 0; 519 } 520 } else if (nlk->subscriptions) 521 netlink_update_listeners(sk); 522 netlink_table_ungrab(); 523 524 kfree(nlk->groups); 525 nlk->groups = NULL; 526 527 local_bh_disable(); 528 sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1); 529 local_bh_enable(); 530 sock_put(sk); 531 return 0; 532 } 533 534 static int netlink_autobind(struct socket *sock) 535 { 536 struct sock *sk = sock->sk; 537 struct net *net = sock_net(sk); 538 struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash; 539 struct hlist_head *head; 540 struct sock *osk; 541 struct hlist_node *node; 542 s32 pid = current->tgid; 543 int err; 544 static s32 rover = -4097; 545 546 retry: 547 cond_resched(); 548 netlink_table_grab(); 549 head = nl_pid_hashfn(hash, pid); 550 sk_for_each(osk, node, head) { 551 if (!net_eq(sock_net(osk), net)) 552 continue; 553 if (nlk_sk(osk)->pid == pid) { 554 /* Bind collision, search negative pid values. */ 555 pid = rover--; 556 if (rover > -4097) 557 rover = -4097; 558 netlink_table_ungrab(); 559 goto retry; 560 } 561 } 562 netlink_table_ungrab(); 563 564 err = netlink_insert(sk, net, pid); 565 if (err == -EADDRINUSE) 566 goto retry; 567 568 /* If 2 threads race to autobind, that is fine. */ 569 if (err == -EBUSY) 570 err = 0; 571 572 return err; 573 } 574 575 static inline int netlink_capable(struct socket *sock, unsigned int flag) 576 { 577 return (nl_table[sock->sk->sk_protocol].nl_nonroot & flag) || 578 capable(CAP_NET_ADMIN); 579 } 580 581 static void 582 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions) 583 { 584 struct netlink_sock *nlk = nlk_sk(sk); 585 586 if (nlk->subscriptions && !subscriptions) 587 __sk_del_bind_node(sk); 588 else if (!nlk->subscriptions && subscriptions) 589 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list); 590 nlk->subscriptions = subscriptions; 591 } 592 593 static int netlink_realloc_groups(struct sock *sk) 594 { 595 struct netlink_sock *nlk = nlk_sk(sk); 596 unsigned int groups; 597 unsigned long *new_groups; 598 int err = 0; 599 600 netlink_table_grab(); 601 602 groups = nl_table[sk->sk_protocol].groups; 603 if (!nl_table[sk->sk_protocol].registered) { 604 err = -ENOENT; 605 goto out_unlock; 606 } 607 608 if (nlk->ngroups >= groups) 609 goto out_unlock; 610 611 new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC); 612 if (new_groups == NULL) { 613 err = -ENOMEM; 614 goto out_unlock; 615 } 616 memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0, 617 NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups)); 618 619 nlk->groups = new_groups; 620 nlk->ngroups = groups; 621 out_unlock: 622 netlink_table_ungrab(); 623 return err; 624 } 625 626 static int netlink_bind(struct socket *sock, struct sockaddr *addr, 627 int addr_len) 628 { 629 struct sock *sk = sock->sk; 630 struct net *net = sock_net(sk); 631 struct netlink_sock *nlk = nlk_sk(sk); 632 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; 633 int err; 634 635 if (nladdr->nl_family != AF_NETLINK) 636 return -EINVAL; 637 638 /* Only superuser is allowed to listen multicasts */ 639 if (nladdr->nl_groups) { 640 if (!netlink_capable(sock, NL_NONROOT_RECV)) 641 return -EPERM; 642 err = netlink_realloc_groups(sk); 643 if (err) 644 return err; 645 } 646 647 if (nlk->pid) { 648 if (nladdr->nl_pid != nlk->pid) 649 return -EINVAL; 650 } else { 651 err = nladdr->nl_pid ? 652 netlink_insert(sk, net, nladdr->nl_pid) : 653 netlink_autobind(sock); 654 if (err) 655 return err; 656 } 657 658 if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0])) 659 return 0; 660 661 netlink_table_grab(); 662 netlink_update_subscriptions(sk, nlk->subscriptions + 663 hweight32(nladdr->nl_groups) - 664 hweight32(nlk->groups[0])); 665 nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups; 666 netlink_update_listeners(sk); 667 netlink_table_ungrab(); 668 669 return 0; 670 } 671 672 static int netlink_connect(struct socket *sock, struct sockaddr *addr, 673 int alen, int flags) 674 { 675 int err = 0; 676 struct sock *sk = sock->sk; 677 struct netlink_sock *nlk = nlk_sk(sk); 678 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; 679 680 if (addr->sa_family == AF_UNSPEC) { 681 sk->sk_state = NETLINK_UNCONNECTED; 682 nlk->dst_pid = 0; 683 nlk->dst_group = 0; 684 return 0; 685 } 686 if (addr->sa_family != AF_NETLINK) 687 return -EINVAL; 688 689 /* Only superuser is allowed to send multicasts */ 690 if (nladdr->nl_groups && !netlink_capable(sock, NL_NONROOT_SEND)) 691 return -EPERM; 692 693 if (!nlk->pid) 694 err = netlink_autobind(sock); 695 696 if (err == 0) { 697 sk->sk_state = NETLINK_CONNECTED; 698 nlk->dst_pid = nladdr->nl_pid; 699 nlk->dst_group = ffs(nladdr->nl_groups); 700 } 701 702 return err; 703 } 704 705 static int netlink_getname(struct socket *sock, struct sockaddr *addr, 706 int *addr_len, int peer) 707 { 708 struct sock *sk = sock->sk; 709 struct netlink_sock *nlk = nlk_sk(sk); 710 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; 711 712 nladdr->nl_family = AF_NETLINK; 713 nladdr->nl_pad = 0; 714 *addr_len = sizeof(*nladdr); 715 716 if (peer) { 717 nladdr->nl_pid = nlk->dst_pid; 718 nladdr->nl_groups = netlink_group_mask(nlk->dst_group); 719 } else { 720 nladdr->nl_pid = nlk->pid; 721 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0; 722 } 723 return 0; 724 } 725 726 static void netlink_overrun(struct sock *sk) 727 { 728 struct netlink_sock *nlk = nlk_sk(sk); 729 730 if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) { 731 if (!test_and_set_bit(0, &nlk_sk(sk)->state)) { 732 sk->sk_err = ENOBUFS; 733 sk->sk_error_report(sk); 734 } 735 } 736 atomic_inc(&sk->sk_drops); 737 } 738 739 static struct sock *netlink_getsockbypid(struct sock *ssk, u32 pid) 740 { 741 struct sock *sock; 742 struct netlink_sock *nlk; 743 744 sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, pid); 745 if (!sock) 746 return ERR_PTR(-ECONNREFUSED); 747 748 /* Don't bother queuing skb if kernel socket has no input function */ 749 nlk = nlk_sk(sock); 750 if (sock->sk_state == NETLINK_CONNECTED && 751 nlk->dst_pid != nlk_sk(ssk)->pid) { 752 sock_put(sock); 753 return ERR_PTR(-ECONNREFUSED); 754 } 755 return sock; 756 } 757 758 struct sock *netlink_getsockbyfilp(struct file *filp) 759 { 760 struct inode *inode = filp->f_path.dentry->d_inode; 761 struct sock *sock; 762 763 if (!S_ISSOCK(inode->i_mode)) 764 return ERR_PTR(-ENOTSOCK); 765 766 sock = SOCKET_I(inode)->sk; 767 if (sock->sk_family != AF_NETLINK) 768 return ERR_PTR(-EINVAL); 769 770 sock_hold(sock); 771 return sock; 772 } 773 774 /* 775 * Attach a skb to a netlink socket. 776 * The caller must hold a reference to the destination socket. On error, the 777 * reference is dropped. The skb is not send to the destination, just all 778 * all error checks are performed and memory in the queue is reserved. 779 * Return values: 780 * < 0: error. skb freed, reference to sock dropped. 781 * 0: continue 782 * 1: repeat lookup - reference dropped while waiting for socket memory. 783 */ 784 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 785 long *timeo, struct sock *ssk) 786 { 787 struct netlink_sock *nlk; 788 789 nlk = nlk_sk(sk); 790 791 if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || 792 test_bit(0, &nlk->state)) { 793 DECLARE_WAITQUEUE(wait, current); 794 if (!*timeo) { 795 if (!ssk || netlink_is_kernel(ssk)) 796 netlink_overrun(sk); 797 sock_put(sk); 798 kfree_skb(skb); 799 return -EAGAIN; 800 } 801 802 __set_current_state(TASK_INTERRUPTIBLE); 803 add_wait_queue(&nlk->wait, &wait); 804 805 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || 806 test_bit(0, &nlk->state)) && 807 !sock_flag(sk, SOCK_DEAD)) 808 *timeo = schedule_timeout(*timeo); 809 810 __set_current_state(TASK_RUNNING); 811 remove_wait_queue(&nlk->wait, &wait); 812 sock_put(sk); 813 814 if (signal_pending(current)) { 815 kfree_skb(skb); 816 return sock_intr_errno(*timeo); 817 } 818 return 1; 819 } 820 skb_set_owner_r(skb, sk); 821 return 0; 822 } 823 824 int netlink_sendskb(struct sock *sk, struct sk_buff *skb) 825 { 826 int len = skb->len; 827 828 skb_queue_tail(&sk->sk_receive_queue, skb); 829 sk->sk_data_ready(sk, len); 830 sock_put(sk); 831 return len; 832 } 833 834 void netlink_detachskb(struct sock *sk, struct sk_buff *skb) 835 { 836 kfree_skb(skb); 837 sock_put(sk); 838 } 839 840 static inline struct sk_buff *netlink_trim(struct sk_buff *skb, 841 gfp_t allocation) 842 { 843 int delta; 844 845 skb_orphan(skb); 846 847 delta = skb->end - skb->tail; 848 if (delta * 2 < skb->truesize) 849 return skb; 850 851 if (skb_shared(skb)) { 852 struct sk_buff *nskb = skb_clone(skb, allocation); 853 if (!nskb) 854 return skb; 855 kfree_skb(skb); 856 skb = nskb; 857 } 858 859 if (!pskb_expand_head(skb, 0, -delta, allocation)) 860 skb->truesize -= delta; 861 862 return skb; 863 } 864 865 static inline void netlink_rcv_wake(struct sock *sk) 866 { 867 struct netlink_sock *nlk = nlk_sk(sk); 868 869 if (skb_queue_empty(&sk->sk_receive_queue)) 870 clear_bit(0, &nlk->state); 871 if (!test_bit(0, &nlk->state)) 872 wake_up_interruptible(&nlk->wait); 873 } 874 875 static inline int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb) 876 { 877 int ret; 878 struct netlink_sock *nlk = nlk_sk(sk); 879 880 ret = -ECONNREFUSED; 881 if (nlk->netlink_rcv != NULL) { 882 ret = skb->len; 883 skb_set_owner_r(skb, sk); 884 nlk->netlink_rcv(skb); 885 } 886 kfree_skb(skb); 887 sock_put(sk); 888 return ret; 889 } 890 891 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, 892 u32 pid, int nonblock) 893 { 894 struct sock *sk; 895 int err; 896 long timeo; 897 898 skb = netlink_trim(skb, gfp_any()); 899 900 timeo = sock_sndtimeo(ssk, nonblock); 901 retry: 902 sk = netlink_getsockbypid(ssk, pid); 903 if (IS_ERR(sk)) { 904 kfree_skb(skb); 905 return PTR_ERR(sk); 906 } 907 if (netlink_is_kernel(sk)) 908 return netlink_unicast_kernel(sk, skb); 909 910 if (sk_filter(sk, skb)) { 911 err = skb->len; 912 kfree_skb(skb); 913 sock_put(sk); 914 return err; 915 } 916 917 err = netlink_attachskb(sk, skb, &timeo, ssk); 918 if (err == 1) 919 goto retry; 920 if (err) 921 return err; 922 923 return netlink_sendskb(sk, skb); 924 } 925 EXPORT_SYMBOL(netlink_unicast); 926 927 int netlink_has_listeners(struct sock *sk, unsigned int group) 928 { 929 int res = 0; 930 unsigned long *listeners; 931 932 BUG_ON(!netlink_is_kernel(sk)); 933 934 rcu_read_lock(); 935 listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners); 936 937 if (group - 1 < nl_table[sk->sk_protocol].groups) 938 res = test_bit(group - 1, listeners); 939 940 rcu_read_unlock(); 941 942 return res; 943 } 944 EXPORT_SYMBOL_GPL(netlink_has_listeners); 945 946 static inline int netlink_broadcast_deliver(struct sock *sk, 947 struct sk_buff *skb) 948 { 949 struct netlink_sock *nlk = nlk_sk(sk); 950 951 if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf && 952 !test_bit(0, &nlk->state)) { 953 skb_set_owner_r(skb, sk); 954 skb_queue_tail(&sk->sk_receive_queue, skb); 955 sk->sk_data_ready(sk, skb->len); 956 return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf; 957 } 958 return -1; 959 } 960 961 struct netlink_broadcast_data { 962 struct sock *exclude_sk; 963 struct net *net; 964 u32 pid; 965 u32 group; 966 int failure; 967 int delivery_failure; 968 int congested; 969 int delivered; 970 gfp_t allocation; 971 struct sk_buff *skb, *skb2; 972 }; 973 974 static inline int do_one_broadcast(struct sock *sk, 975 struct netlink_broadcast_data *p) 976 { 977 struct netlink_sock *nlk = nlk_sk(sk); 978 int val; 979 980 if (p->exclude_sk == sk) 981 goto out; 982 983 if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups || 984 !test_bit(p->group - 1, nlk->groups)) 985 goto out; 986 987 if (!net_eq(sock_net(sk), p->net)) 988 goto out; 989 990 if (p->failure) { 991 netlink_overrun(sk); 992 goto out; 993 } 994 995 sock_hold(sk); 996 if (p->skb2 == NULL) { 997 if (skb_shared(p->skb)) { 998 p->skb2 = skb_clone(p->skb, p->allocation); 999 } else { 1000 p->skb2 = skb_get(p->skb); 1001 /* 1002 * skb ownership may have been set when 1003 * delivered to a previous socket. 1004 */ 1005 skb_orphan(p->skb2); 1006 } 1007 } 1008 if (p->skb2 == NULL) { 1009 netlink_overrun(sk); 1010 /* Clone failed. Notify ALL listeners. */ 1011 p->failure = 1; 1012 if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR) 1013 p->delivery_failure = 1; 1014 } else if (sk_filter(sk, p->skb2)) { 1015 kfree_skb(p->skb2); 1016 p->skb2 = NULL; 1017 } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) { 1018 netlink_overrun(sk); 1019 if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR) 1020 p->delivery_failure = 1; 1021 } else { 1022 p->congested |= val; 1023 p->delivered = 1; 1024 p->skb2 = NULL; 1025 } 1026 sock_put(sk); 1027 1028 out: 1029 return 0; 1030 } 1031 1032 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid, 1033 u32 group, gfp_t allocation) 1034 { 1035 struct net *net = sock_net(ssk); 1036 struct netlink_broadcast_data info; 1037 struct hlist_node *node; 1038 struct sock *sk; 1039 1040 skb = netlink_trim(skb, allocation); 1041 1042 info.exclude_sk = ssk; 1043 info.net = net; 1044 info.pid = pid; 1045 info.group = group; 1046 info.failure = 0; 1047 info.delivery_failure = 0; 1048 info.congested = 0; 1049 info.delivered = 0; 1050 info.allocation = allocation; 1051 info.skb = skb; 1052 info.skb2 = NULL; 1053 1054 /* While we sleep in clone, do not allow to change socket list */ 1055 1056 netlink_lock_table(); 1057 1058 sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list) 1059 do_one_broadcast(sk, &info); 1060 1061 kfree_skb(skb); 1062 1063 netlink_unlock_table(); 1064 1065 kfree_skb(info.skb2); 1066 1067 if (info.delivery_failure) 1068 return -ENOBUFS; 1069 1070 if (info.delivered) { 1071 if (info.congested && (allocation & __GFP_WAIT)) 1072 yield(); 1073 return 0; 1074 } 1075 return -ESRCH; 1076 } 1077 EXPORT_SYMBOL(netlink_broadcast); 1078 1079 struct netlink_set_err_data { 1080 struct sock *exclude_sk; 1081 u32 pid; 1082 u32 group; 1083 int code; 1084 }; 1085 1086 static inline int do_one_set_err(struct sock *sk, 1087 struct netlink_set_err_data *p) 1088 { 1089 struct netlink_sock *nlk = nlk_sk(sk); 1090 1091 if (sk == p->exclude_sk) 1092 goto out; 1093 1094 if (sock_net(sk) != sock_net(p->exclude_sk)) 1095 goto out; 1096 1097 if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups || 1098 !test_bit(p->group - 1, nlk->groups)) 1099 goto out; 1100 1101 sk->sk_err = p->code; 1102 sk->sk_error_report(sk); 1103 out: 1104 return 0; 1105 } 1106 1107 /** 1108 * netlink_set_err - report error to broadcast listeners 1109 * @ssk: the kernel netlink socket, as returned by netlink_kernel_create() 1110 * @pid: the PID of a process that we want to skip (if any) 1111 * @groups: the broadcast group that will notice the error 1112 * @code: error code, must be negative (as usual in kernelspace) 1113 */ 1114 void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code) 1115 { 1116 struct netlink_set_err_data info; 1117 struct hlist_node *node; 1118 struct sock *sk; 1119 1120 info.exclude_sk = ssk; 1121 info.pid = pid; 1122 info.group = group; 1123 /* sk->sk_err wants a positive error value */ 1124 info.code = -code; 1125 1126 read_lock(&nl_table_lock); 1127 1128 sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list) 1129 do_one_set_err(sk, &info); 1130 1131 read_unlock(&nl_table_lock); 1132 } 1133 EXPORT_SYMBOL(netlink_set_err); 1134 1135 /* must be called with netlink table grabbed */ 1136 static void netlink_update_socket_mc(struct netlink_sock *nlk, 1137 unsigned int group, 1138 int is_new) 1139 { 1140 int old, new = !!is_new, subscriptions; 1141 1142 old = test_bit(group - 1, nlk->groups); 1143 subscriptions = nlk->subscriptions - old + new; 1144 if (new) 1145 __set_bit(group - 1, nlk->groups); 1146 else 1147 __clear_bit(group - 1, nlk->groups); 1148 netlink_update_subscriptions(&nlk->sk, subscriptions); 1149 netlink_update_listeners(&nlk->sk); 1150 } 1151 1152 static int netlink_setsockopt(struct socket *sock, int level, int optname, 1153 char __user *optval, unsigned int optlen) 1154 { 1155 struct sock *sk = sock->sk; 1156 struct netlink_sock *nlk = nlk_sk(sk); 1157 unsigned int val = 0; 1158 int err; 1159 1160 if (level != SOL_NETLINK) 1161 return -ENOPROTOOPT; 1162 1163 if (optlen >= sizeof(int) && 1164 get_user(val, (unsigned int __user *)optval)) 1165 return -EFAULT; 1166 1167 switch (optname) { 1168 case NETLINK_PKTINFO: 1169 if (val) 1170 nlk->flags |= NETLINK_RECV_PKTINFO; 1171 else 1172 nlk->flags &= ~NETLINK_RECV_PKTINFO; 1173 err = 0; 1174 break; 1175 case NETLINK_ADD_MEMBERSHIP: 1176 case NETLINK_DROP_MEMBERSHIP: { 1177 if (!netlink_capable(sock, NL_NONROOT_RECV)) 1178 return -EPERM; 1179 err = netlink_realloc_groups(sk); 1180 if (err) 1181 return err; 1182 if (!val || val - 1 >= nlk->ngroups) 1183 return -EINVAL; 1184 netlink_table_grab(); 1185 netlink_update_socket_mc(nlk, val, 1186 optname == NETLINK_ADD_MEMBERSHIP); 1187 netlink_table_ungrab(); 1188 err = 0; 1189 break; 1190 } 1191 case NETLINK_BROADCAST_ERROR: 1192 if (val) 1193 nlk->flags |= NETLINK_BROADCAST_SEND_ERROR; 1194 else 1195 nlk->flags &= ~NETLINK_BROADCAST_SEND_ERROR; 1196 err = 0; 1197 break; 1198 case NETLINK_NO_ENOBUFS: 1199 if (val) { 1200 nlk->flags |= NETLINK_RECV_NO_ENOBUFS; 1201 clear_bit(0, &nlk->state); 1202 wake_up_interruptible(&nlk->wait); 1203 } else 1204 nlk->flags &= ~NETLINK_RECV_NO_ENOBUFS; 1205 err = 0; 1206 break; 1207 default: 1208 err = -ENOPROTOOPT; 1209 } 1210 return err; 1211 } 1212 1213 static int netlink_getsockopt(struct socket *sock, int level, int optname, 1214 char __user *optval, int __user *optlen) 1215 { 1216 struct sock *sk = sock->sk; 1217 struct netlink_sock *nlk = nlk_sk(sk); 1218 int len, val, err; 1219 1220 if (level != SOL_NETLINK) 1221 return -ENOPROTOOPT; 1222 1223 if (get_user(len, optlen)) 1224 return -EFAULT; 1225 if (len < 0) 1226 return -EINVAL; 1227 1228 switch (optname) { 1229 case NETLINK_PKTINFO: 1230 if (len < sizeof(int)) 1231 return -EINVAL; 1232 len = sizeof(int); 1233 val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0; 1234 if (put_user(len, optlen) || 1235 put_user(val, optval)) 1236 return -EFAULT; 1237 err = 0; 1238 break; 1239 case NETLINK_BROADCAST_ERROR: 1240 if (len < sizeof(int)) 1241 return -EINVAL; 1242 len = sizeof(int); 1243 val = nlk->flags & NETLINK_BROADCAST_SEND_ERROR ? 1 : 0; 1244 if (put_user(len, optlen) || 1245 put_user(val, optval)) 1246 return -EFAULT; 1247 err = 0; 1248 break; 1249 case NETLINK_NO_ENOBUFS: 1250 if (len < sizeof(int)) 1251 return -EINVAL; 1252 len = sizeof(int); 1253 val = nlk->flags & NETLINK_RECV_NO_ENOBUFS ? 1 : 0; 1254 if (put_user(len, optlen) || 1255 put_user(val, optval)) 1256 return -EFAULT; 1257 err = 0; 1258 break; 1259 default: 1260 err = -ENOPROTOOPT; 1261 } 1262 return err; 1263 } 1264 1265 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb) 1266 { 1267 struct nl_pktinfo info; 1268 1269 info.group = NETLINK_CB(skb).dst_group; 1270 put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info); 1271 } 1272 1273 static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock, 1274 struct msghdr *msg, size_t len) 1275 { 1276 struct sock_iocb *siocb = kiocb_to_siocb(kiocb); 1277 struct sock *sk = sock->sk; 1278 struct netlink_sock *nlk = nlk_sk(sk); 1279 struct sockaddr_nl *addr = msg->msg_name; 1280 u32 dst_pid; 1281 u32 dst_group; 1282 struct sk_buff *skb; 1283 int err; 1284 struct scm_cookie scm; 1285 1286 if (msg->msg_flags&MSG_OOB) 1287 return -EOPNOTSUPP; 1288 1289 if (NULL == siocb->scm) 1290 siocb->scm = &scm; 1291 err = scm_send(sock, msg, siocb->scm); 1292 if (err < 0) 1293 return err; 1294 1295 if (msg->msg_namelen) { 1296 if (addr->nl_family != AF_NETLINK) 1297 return -EINVAL; 1298 dst_pid = addr->nl_pid; 1299 dst_group = ffs(addr->nl_groups); 1300 if (dst_group && !netlink_capable(sock, NL_NONROOT_SEND)) 1301 return -EPERM; 1302 } else { 1303 dst_pid = nlk->dst_pid; 1304 dst_group = nlk->dst_group; 1305 } 1306 1307 if (!nlk->pid) { 1308 err = netlink_autobind(sock); 1309 if (err) 1310 goto out; 1311 } 1312 1313 err = -EMSGSIZE; 1314 if (len > sk->sk_sndbuf - 32) 1315 goto out; 1316 err = -ENOBUFS; 1317 skb = alloc_skb(len, GFP_KERNEL); 1318 if (skb == NULL) 1319 goto out; 1320 1321 NETLINK_CB(skb).pid = nlk->pid; 1322 NETLINK_CB(skb).dst_group = dst_group; 1323 NETLINK_CB(skb).loginuid = audit_get_loginuid(current); 1324 NETLINK_CB(skb).sessionid = audit_get_sessionid(current); 1325 security_task_getsecid(current, &(NETLINK_CB(skb).sid)); 1326 memcpy(NETLINK_CREDS(skb), &siocb->scm->creds, sizeof(struct ucred)); 1327 1328 /* What can I do? Netlink is asynchronous, so that 1329 we will have to save current capabilities to 1330 check them, when this message will be delivered 1331 to corresponding kernel module. --ANK (980802) 1332 */ 1333 1334 err = -EFAULT; 1335 if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) { 1336 kfree_skb(skb); 1337 goto out; 1338 } 1339 1340 err = security_netlink_send(sk, skb); 1341 if (err) { 1342 kfree_skb(skb); 1343 goto out; 1344 } 1345 1346 if (dst_group) { 1347 atomic_inc(&skb->users); 1348 netlink_broadcast(sk, skb, dst_pid, dst_group, GFP_KERNEL); 1349 } 1350 err = netlink_unicast(sk, skb, dst_pid, msg->msg_flags&MSG_DONTWAIT); 1351 1352 out: 1353 return err; 1354 } 1355 1356 static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock, 1357 struct msghdr *msg, size_t len, 1358 int flags) 1359 { 1360 struct sock_iocb *siocb = kiocb_to_siocb(kiocb); 1361 struct scm_cookie scm; 1362 struct sock *sk = sock->sk; 1363 struct netlink_sock *nlk = nlk_sk(sk); 1364 int noblock = flags&MSG_DONTWAIT; 1365 size_t copied; 1366 struct sk_buff *skb, *frag __maybe_unused = NULL; 1367 int err; 1368 1369 if (flags&MSG_OOB) 1370 return -EOPNOTSUPP; 1371 1372 copied = 0; 1373 1374 skb = skb_recv_datagram(sk, flags, noblock, &err); 1375 if (skb == NULL) 1376 goto out; 1377 1378 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES 1379 if (unlikely(skb_shinfo(skb)->frag_list)) { 1380 bool need_compat = !!(flags & MSG_CMSG_COMPAT); 1381 1382 /* 1383 * If this skb has a frag_list, then here that means that 1384 * we will have to use the frag_list skb for compat tasks 1385 * and the regular skb for non-compat tasks. 1386 * 1387 * The skb might (and likely will) be cloned, so we can't 1388 * just reset frag_list and go on with things -- we need to 1389 * keep that. For the compat case that's easy -- simply get 1390 * a reference to the compat skb and free the regular one 1391 * including the frag. For the non-compat case, we need to 1392 * avoid sending the frag to the user -- so assign NULL but 1393 * restore it below before freeing the skb. 1394 */ 1395 if (need_compat) { 1396 struct sk_buff *compskb = skb_shinfo(skb)->frag_list; 1397 skb_get(compskb); 1398 kfree_skb(skb); 1399 skb = compskb; 1400 } else { 1401 frag = skb_shinfo(skb)->frag_list; 1402 skb_shinfo(skb)->frag_list = NULL; 1403 } 1404 } 1405 #endif 1406 1407 msg->msg_namelen = 0; 1408 1409 copied = skb->len; 1410 if (len < copied) { 1411 msg->msg_flags |= MSG_TRUNC; 1412 copied = len; 1413 } 1414 1415 skb_reset_transport_header(skb); 1416 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied); 1417 1418 if (msg->msg_name) { 1419 struct sockaddr_nl *addr = (struct sockaddr_nl *)msg->msg_name; 1420 addr->nl_family = AF_NETLINK; 1421 addr->nl_pad = 0; 1422 addr->nl_pid = NETLINK_CB(skb).pid; 1423 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group); 1424 msg->msg_namelen = sizeof(*addr); 1425 } 1426 1427 if (nlk->flags & NETLINK_RECV_PKTINFO) 1428 netlink_cmsg_recv_pktinfo(msg, skb); 1429 1430 if (NULL == siocb->scm) { 1431 memset(&scm, 0, sizeof(scm)); 1432 siocb->scm = &scm; 1433 } 1434 siocb->scm->creds = *NETLINK_CREDS(skb); 1435 if (flags & MSG_TRUNC) 1436 copied = skb->len; 1437 1438 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES 1439 skb_shinfo(skb)->frag_list = frag; 1440 #endif 1441 1442 skb_free_datagram(sk, skb); 1443 1444 if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) 1445 netlink_dump(sk); 1446 1447 scm_recv(sock, msg, siocb->scm, flags); 1448 out: 1449 netlink_rcv_wake(sk); 1450 return err ? : copied; 1451 } 1452 1453 static void netlink_data_ready(struct sock *sk, int len) 1454 { 1455 BUG(); 1456 } 1457 1458 /* 1459 * We export these functions to other modules. They provide a 1460 * complete set of kernel non-blocking support for message 1461 * queueing. 1462 */ 1463 1464 struct sock * 1465 netlink_kernel_create(struct net *net, int unit, unsigned int groups, 1466 void (*input)(struct sk_buff *skb), 1467 struct mutex *cb_mutex, struct module *module) 1468 { 1469 struct socket *sock; 1470 struct sock *sk; 1471 struct netlink_sock *nlk; 1472 unsigned long *listeners = NULL; 1473 1474 BUG_ON(!nl_table); 1475 1476 if (unit < 0 || unit >= MAX_LINKS) 1477 return NULL; 1478 1479 if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock)) 1480 return NULL; 1481 1482 /* 1483 * We have to just have a reference on the net from sk, but don't 1484 * get_net it. Besides, we cannot get and then put the net here. 1485 * So we create one inside init_net and the move it to net. 1486 */ 1487 1488 if (__netlink_create(&init_net, sock, cb_mutex, unit) < 0) 1489 goto out_sock_release_nosk; 1490 1491 sk = sock->sk; 1492 sk_change_net(sk, net); 1493 1494 if (groups < 32) 1495 groups = 32; 1496 1497 listeners = kzalloc(NLGRPSZ(groups) + sizeof(struct listeners_rcu_head), 1498 GFP_KERNEL); 1499 if (!listeners) 1500 goto out_sock_release; 1501 1502 sk->sk_data_ready = netlink_data_ready; 1503 if (input) 1504 nlk_sk(sk)->netlink_rcv = input; 1505 1506 if (netlink_insert(sk, net, 0)) 1507 goto out_sock_release; 1508 1509 nlk = nlk_sk(sk); 1510 nlk->flags |= NETLINK_KERNEL_SOCKET; 1511 1512 netlink_table_grab(); 1513 if (!nl_table[unit].registered) { 1514 nl_table[unit].groups = groups; 1515 nl_table[unit].listeners = listeners; 1516 nl_table[unit].cb_mutex = cb_mutex; 1517 nl_table[unit].module = module; 1518 nl_table[unit].registered = 1; 1519 } else { 1520 kfree(listeners); 1521 nl_table[unit].registered++; 1522 } 1523 netlink_table_ungrab(); 1524 return sk; 1525 1526 out_sock_release: 1527 kfree(listeners); 1528 netlink_kernel_release(sk); 1529 return NULL; 1530 1531 out_sock_release_nosk: 1532 sock_release(sock); 1533 return NULL; 1534 } 1535 EXPORT_SYMBOL(netlink_kernel_create); 1536 1537 1538 void 1539 netlink_kernel_release(struct sock *sk) 1540 { 1541 sk_release_kernel(sk); 1542 } 1543 EXPORT_SYMBOL(netlink_kernel_release); 1544 1545 1546 static void netlink_free_old_listeners(struct rcu_head *rcu_head) 1547 { 1548 struct listeners_rcu_head *lrh; 1549 1550 lrh = container_of(rcu_head, struct listeners_rcu_head, rcu_head); 1551 kfree(lrh->ptr); 1552 } 1553 1554 int __netlink_change_ngroups(struct sock *sk, unsigned int groups) 1555 { 1556 unsigned long *listeners, *old = NULL; 1557 struct listeners_rcu_head *old_rcu_head; 1558 struct netlink_table *tbl = &nl_table[sk->sk_protocol]; 1559 1560 if (groups < 32) 1561 groups = 32; 1562 1563 if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) { 1564 listeners = kzalloc(NLGRPSZ(groups) + 1565 sizeof(struct listeners_rcu_head), 1566 GFP_ATOMIC); 1567 if (!listeners) 1568 return -ENOMEM; 1569 old = tbl->listeners; 1570 memcpy(listeners, old, NLGRPSZ(tbl->groups)); 1571 rcu_assign_pointer(tbl->listeners, listeners); 1572 /* 1573 * Free the old memory after an RCU grace period so we 1574 * don't leak it. We use call_rcu() here in order to be 1575 * able to call this function from atomic contexts. The 1576 * allocation of this memory will have reserved enough 1577 * space for struct listeners_rcu_head at the end. 1578 */ 1579 old_rcu_head = (void *)(tbl->listeners + 1580 NLGRPLONGS(tbl->groups)); 1581 old_rcu_head->ptr = old; 1582 call_rcu(&old_rcu_head->rcu_head, netlink_free_old_listeners); 1583 } 1584 tbl->groups = groups; 1585 1586 return 0; 1587 } 1588 1589 /** 1590 * netlink_change_ngroups - change number of multicast groups 1591 * 1592 * This changes the number of multicast groups that are available 1593 * on a certain netlink family. Note that it is not possible to 1594 * change the number of groups to below 32. Also note that it does 1595 * not implicitly call netlink_clear_multicast_users() when the 1596 * number of groups is reduced. 1597 * 1598 * @sk: The kernel netlink socket, as returned by netlink_kernel_create(). 1599 * @groups: The new number of groups. 1600 */ 1601 int netlink_change_ngroups(struct sock *sk, unsigned int groups) 1602 { 1603 int err; 1604 1605 netlink_table_grab(); 1606 err = __netlink_change_ngroups(sk, groups); 1607 netlink_table_ungrab(); 1608 1609 return err; 1610 } 1611 1612 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group) 1613 { 1614 struct sock *sk; 1615 struct hlist_node *node; 1616 struct netlink_table *tbl = &nl_table[ksk->sk_protocol]; 1617 1618 sk_for_each_bound(sk, node, &tbl->mc_list) 1619 netlink_update_socket_mc(nlk_sk(sk), group, 0); 1620 } 1621 1622 /** 1623 * netlink_clear_multicast_users - kick off multicast listeners 1624 * 1625 * This function removes all listeners from the given group. 1626 * @ksk: The kernel netlink socket, as returned by 1627 * netlink_kernel_create(). 1628 * @group: The multicast group to clear. 1629 */ 1630 void netlink_clear_multicast_users(struct sock *ksk, unsigned int group) 1631 { 1632 netlink_table_grab(); 1633 __netlink_clear_multicast_users(ksk, group); 1634 netlink_table_ungrab(); 1635 } 1636 1637 void netlink_set_nonroot(int protocol, unsigned int flags) 1638 { 1639 if ((unsigned int)protocol < MAX_LINKS) 1640 nl_table[protocol].nl_nonroot = flags; 1641 } 1642 EXPORT_SYMBOL(netlink_set_nonroot); 1643 1644 static void netlink_destroy_callback(struct netlink_callback *cb) 1645 { 1646 kfree_skb(cb->skb); 1647 kfree(cb); 1648 } 1649 1650 /* 1651 * It looks a bit ugly. 1652 * It would be better to create kernel thread. 1653 */ 1654 1655 static int netlink_dump(struct sock *sk) 1656 { 1657 struct netlink_sock *nlk = nlk_sk(sk); 1658 struct netlink_callback *cb; 1659 struct sk_buff *skb; 1660 struct nlmsghdr *nlh; 1661 int len, err = -ENOBUFS; 1662 1663 skb = sock_rmalloc(sk, NLMSG_GOODSIZE, 0, GFP_KERNEL); 1664 if (!skb) 1665 goto errout; 1666 1667 mutex_lock(nlk->cb_mutex); 1668 1669 cb = nlk->cb; 1670 if (cb == NULL) { 1671 err = -EINVAL; 1672 goto errout_skb; 1673 } 1674 1675 len = cb->dump(skb, cb); 1676 1677 if (len > 0) { 1678 mutex_unlock(nlk->cb_mutex); 1679 1680 if (sk_filter(sk, skb)) 1681 kfree_skb(skb); 1682 else { 1683 skb_queue_tail(&sk->sk_receive_queue, skb); 1684 sk->sk_data_ready(sk, skb->len); 1685 } 1686 return 0; 1687 } 1688 1689 nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI); 1690 if (!nlh) 1691 goto errout_skb; 1692 1693 memcpy(nlmsg_data(nlh), &len, sizeof(len)); 1694 1695 if (sk_filter(sk, skb)) 1696 kfree_skb(skb); 1697 else { 1698 skb_queue_tail(&sk->sk_receive_queue, skb); 1699 sk->sk_data_ready(sk, skb->len); 1700 } 1701 1702 if (cb->done) 1703 cb->done(cb); 1704 nlk->cb = NULL; 1705 mutex_unlock(nlk->cb_mutex); 1706 1707 netlink_destroy_callback(cb); 1708 return 0; 1709 1710 errout_skb: 1711 mutex_unlock(nlk->cb_mutex); 1712 kfree_skb(skb); 1713 errout: 1714 return err; 1715 } 1716 1717 int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 1718 const struct nlmsghdr *nlh, 1719 int (*dump)(struct sk_buff *skb, 1720 struct netlink_callback *), 1721 int (*done)(struct netlink_callback *)) 1722 { 1723 struct netlink_callback *cb; 1724 struct sock *sk; 1725 struct netlink_sock *nlk; 1726 1727 cb = kzalloc(sizeof(*cb), GFP_KERNEL); 1728 if (cb == NULL) 1729 return -ENOBUFS; 1730 1731 cb->dump = dump; 1732 cb->done = done; 1733 cb->nlh = nlh; 1734 atomic_inc(&skb->users); 1735 cb->skb = skb; 1736 1737 sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).pid); 1738 if (sk == NULL) { 1739 netlink_destroy_callback(cb); 1740 return -ECONNREFUSED; 1741 } 1742 nlk = nlk_sk(sk); 1743 /* A dump is in progress... */ 1744 mutex_lock(nlk->cb_mutex); 1745 if (nlk->cb) { 1746 mutex_unlock(nlk->cb_mutex); 1747 netlink_destroy_callback(cb); 1748 sock_put(sk); 1749 return -EBUSY; 1750 } 1751 nlk->cb = cb; 1752 mutex_unlock(nlk->cb_mutex); 1753 1754 netlink_dump(sk); 1755 sock_put(sk); 1756 1757 /* We successfully started a dump, by returning -EINTR we 1758 * signal not to send ACK even if it was requested. 1759 */ 1760 return -EINTR; 1761 } 1762 EXPORT_SYMBOL(netlink_dump_start); 1763 1764 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err) 1765 { 1766 struct sk_buff *skb; 1767 struct nlmsghdr *rep; 1768 struct nlmsgerr *errmsg; 1769 size_t payload = sizeof(*errmsg); 1770 1771 /* error messages get the original request appened */ 1772 if (err) 1773 payload += nlmsg_len(nlh); 1774 1775 skb = nlmsg_new(payload, GFP_KERNEL); 1776 if (!skb) { 1777 struct sock *sk; 1778 1779 sk = netlink_lookup(sock_net(in_skb->sk), 1780 in_skb->sk->sk_protocol, 1781 NETLINK_CB(in_skb).pid); 1782 if (sk) { 1783 sk->sk_err = ENOBUFS; 1784 sk->sk_error_report(sk); 1785 sock_put(sk); 1786 } 1787 return; 1788 } 1789 1790 rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq, 1791 NLMSG_ERROR, payload, 0); 1792 errmsg = nlmsg_data(rep); 1793 errmsg->error = err; 1794 memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh)); 1795 netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid, MSG_DONTWAIT); 1796 } 1797 EXPORT_SYMBOL(netlink_ack); 1798 1799 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *, 1800 struct nlmsghdr *)) 1801 { 1802 struct nlmsghdr *nlh; 1803 int err; 1804 1805 while (skb->len >= nlmsg_total_size(0)) { 1806 int msglen; 1807 1808 nlh = nlmsg_hdr(skb); 1809 err = 0; 1810 1811 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len) 1812 return 0; 1813 1814 /* Only requests are handled by the kernel */ 1815 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) 1816 goto ack; 1817 1818 /* Skip control messages */ 1819 if (nlh->nlmsg_type < NLMSG_MIN_TYPE) 1820 goto ack; 1821 1822 err = cb(skb, nlh); 1823 if (err == -EINTR) 1824 goto skip; 1825 1826 ack: 1827 if (nlh->nlmsg_flags & NLM_F_ACK || err) 1828 netlink_ack(skb, nlh, err); 1829 1830 skip: 1831 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 1832 if (msglen > skb->len) 1833 msglen = skb->len; 1834 skb_pull(skb, msglen); 1835 } 1836 1837 return 0; 1838 } 1839 EXPORT_SYMBOL(netlink_rcv_skb); 1840 1841 /** 1842 * nlmsg_notify - send a notification netlink message 1843 * @sk: netlink socket to use 1844 * @skb: notification message 1845 * @pid: destination netlink pid for reports or 0 1846 * @group: destination multicast group or 0 1847 * @report: 1 to report back, 0 to disable 1848 * @flags: allocation flags 1849 */ 1850 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid, 1851 unsigned int group, int report, gfp_t flags) 1852 { 1853 int err = 0; 1854 1855 if (group) { 1856 int exclude_pid = 0; 1857 1858 if (report) { 1859 atomic_inc(&skb->users); 1860 exclude_pid = pid; 1861 } 1862 1863 /* errors reported via destination sk->sk_err, but propagate 1864 * delivery errors if NETLINK_BROADCAST_ERROR flag is set */ 1865 err = nlmsg_multicast(sk, skb, exclude_pid, group, flags); 1866 } 1867 1868 if (report) { 1869 int err2; 1870 1871 err2 = nlmsg_unicast(sk, skb, pid); 1872 if (!err || err == -ESRCH) 1873 err = err2; 1874 } 1875 1876 return err; 1877 } 1878 EXPORT_SYMBOL(nlmsg_notify); 1879 1880 #ifdef CONFIG_PROC_FS 1881 struct nl_seq_iter { 1882 struct seq_net_private p; 1883 int link; 1884 int hash_idx; 1885 }; 1886 1887 static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos) 1888 { 1889 struct nl_seq_iter *iter = seq->private; 1890 int i, j; 1891 struct sock *s; 1892 struct hlist_node *node; 1893 loff_t off = 0; 1894 1895 for (i = 0; i < MAX_LINKS; i++) { 1896 struct nl_pid_hash *hash = &nl_table[i].hash; 1897 1898 for (j = 0; j <= hash->mask; j++) { 1899 sk_for_each(s, node, &hash->table[j]) { 1900 if (sock_net(s) != seq_file_net(seq)) 1901 continue; 1902 if (off == pos) { 1903 iter->link = i; 1904 iter->hash_idx = j; 1905 return s; 1906 } 1907 ++off; 1908 } 1909 } 1910 } 1911 return NULL; 1912 } 1913 1914 static void *netlink_seq_start(struct seq_file *seq, loff_t *pos) 1915 __acquires(nl_table_lock) 1916 { 1917 read_lock(&nl_table_lock); 1918 return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN; 1919 } 1920 1921 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) 1922 { 1923 struct sock *s; 1924 struct nl_seq_iter *iter; 1925 int i, j; 1926 1927 ++*pos; 1928 1929 if (v == SEQ_START_TOKEN) 1930 return netlink_seq_socket_idx(seq, 0); 1931 1932 iter = seq->private; 1933 s = v; 1934 do { 1935 s = sk_next(s); 1936 } while (s && sock_net(s) != seq_file_net(seq)); 1937 if (s) 1938 return s; 1939 1940 i = iter->link; 1941 j = iter->hash_idx + 1; 1942 1943 do { 1944 struct nl_pid_hash *hash = &nl_table[i].hash; 1945 1946 for (; j <= hash->mask; j++) { 1947 s = sk_head(&hash->table[j]); 1948 while (s && sock_net(s) != seq_file_net(seq)) 1949 s = sk_next(s); 1950 if (s) { 1951 iter->link = i; 1952 iter->hash_idx = j; 1953 return s; 1954 } 1955 } 1956 1957 j = 0; 1958 } while (++i < MAX_LINKS); 1959 1960 return NULL; 1961 } 1962 1963 static void netlink_seq_stop(struct seq_file *seq, void *v) 1964 __releases(nl_table_lock) 1965 { 1966 read_unlock(&nl_table_lock); 1967 } 1968 1969 1970 static int netlink_seq_show(struct seq_file *seq, void *v) 1971 { 1972 if (v == SEQ_START_TOKEN) 1973 seq_puts(seq, 1974 "sk Eth Pid Groups " 1975 "Rmem Wmem Dump Locks Drops\n"); 1976 else { 1977 struct sock *s = v; 1978 struct netlink_sock *nlk = nlk_sk(s); 1979 1980 seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %-8d %-8d\n", 1981 s, 1982 s->sk_protocol, 1983 nlk->pid, 1984 nlk->groups ? (u32)nlk->groups[0] : 0, 1985 sk_rmem_alloc_get(s), 1986 sk_wmem_alloc_get(s), 1987 nlk->cb, 1988 atomic_read(&s->sk_refcnt), 1989 atomic_read(&s->sk_drops) 1990 ); 1991 1992 } 1993 return 0; 1994 } 1995 1996 static const struct seq_operations netlink_seq_ops = { 1997 .start = netlink_seq_start, 1998 .next = netlink_seq_next, 1999 .stop = netlink_seq_stop, 2000 .show = netlink_seq_show, 2001 }; 2002 2003 2004 static int netlink_seq_open(struct inode *inode, struct file *file) 2005 { 2006 return seq_open_net(inode, file, &netlink_seq_ops, 2007 sizeof(struct nl_seq_iter)); 2008 } 2009 2010 static const struct file_operations netlink_seq_fops = { 2011 .owner = THIS_MODULE, 2012 .open = netlink_seq_open, 2013 .read = seq_read, 2014 .llseek = seq_lseek, 2015 .release = seq_release_net, 2016 }; 2017 2018 #endif 2019 2020 int netlink_register_notifier(struct notifier_block *nb) 2021 { 2022 return atomic_notifier_chain_register(&netlink_chain, nb); 2023 } 2024 EXPORT_SYMBOL(netlink_register_notifier); 2025 2026 int netlink_unregister_notifier(struct notifier_block *nb) 2027 { 2028 return atomic_notifier_chain_unregister(&netlink_chain, nb); 2029 } 2030 EXPORT_SYMBOL(netlink_unregister_notifier); 2031 2032 static const struct proto_ops netlink_ops = { 2033 .family = PF_NETLINK, 2034 .owner = THIS_MODULE, 2035 .release = netlink_release, 2036 .bind = netlink_bind, 2037 .connect = netlink_connect, 2038 .socketpair = sock_no_socketpair, 2039 .accept = sock_no_accept, 2040 .getname = netlink_getname, 2041 .poll = datagram_poll, 2042 .ioctl = sock_no_ioctl, 2043 .listen = sock_no_listen, 2044 .shutdown = sock_no_shutdown, 2045 .setsockopt = netlink_setsockopt, 2046 .getsockopt = netlink_getsockopt, 2047 .sendmsg = netlink_sendmsg, 2048 .recvmsg = netlink_recvmsg, 2049 .mmap = sock_no_mmap, 2050 .sendpage = sock_no_sendpage, 2051 }; 2052 2053 static struct net_proto_family netlink_family_ops = { 2054 .family = PF_NETLINK, 2055 .create = netlink_create, 2056 .owner = THIS_MODULE, /* for consistency 8) */ 2057 }; 2058 2059 static int __net_init netlink_net_init(struct net *net) 2060 { 2061 #ifdef CONFIG_PROC_FS 2062 if (!proc_net_fops_create(net, "netlink", 0, &netlink_seq_fops)) 2063 return -ENOMEM; 2064 #endif 2065 return 0; 2066 } 2067 2068 static void __net_exit netlink_net_exit(struct net *net) 2069 { 2070 #ifdef CONFIG_PROC_FS 2071 proc_net_remove(net, "netlink"); 2072 #endif 2073 } 2074 2075 static struct pernet_operations __net_initdata netlink_net_ops = { 2076 .init = netlink_net_init, 2077 .exit = netlink_net_exit, 2078 }; 2079 2080 static int __init netlink_proto_init(void) 2081 { 2082 struct sk_buff *dummy_skb; 2083 int i; 2084 unsigned long limit; 2085 unsigned int order; 2086 int err = proto_register(&netlink_proto, 0); 2087 2088 if (err != 0) 2089 goto out; 2090 2091 BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof(dummy_skb->cb)); 2092 2093 nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL); 2094 if (!nl_table) 2095 goto panic; 2096 2097 if (totalram_pages >= (128 * 1024)) 2098 limit = totalram_pages >> (21 - PAGE_SHIFT); 2099 else 2100 limit = totalram_pages >> (23 - PAGE_SHIFT); 2101 2102 order = get_bitmask_order(limit) - 1 + PAGE_SHIFT; 2103 limit = (1UL << order) / sizeof(struct hlist_head); 2104 order = get_bitmask_order(min(limit, (unsigned long)UINT_MAX)) - 1; 2105 2106 for (i = 0; i < MAX_LINKS; i++) { 2107 struct nl_pid_hash *hash = &nl_table[i].hash; 2108 2109 hash->table = nl_pid_hash_zalloc(1 * sizeof(*hash->table)); 2110 if (!hash->table) { 2111 while (i-- > 0) 2112 nl_pid_hash_free(nl_table[i].hash.table, 2113 1 * sizeof(*hash->table)); 2114 kfree(nl_table); 2115 goto panic; 2116 } 2117 hash->max_shift = order; 2118 hash->shift = 0; 2119 hash->mask = 0; 2120 hash->rehash_time = jiffies; 2121 } 2122 2123 sock_register(&netlink_family_ops); 2124 register_pernet_subsys(&netlink_net_ops); 2125 /* The netlink device handler may be needed early. */ 2126 rtnetlink_init(); 2127 out: 2128 return err; 2129 panic: 2130 panic("netlink_init: Cannot allocate nl_table\n"); 2131 } 2132 2133 core_initcall(netlink_proto_init); 2134