1 /* 2 * NETLINK Kernel-user communication protocol. 3 * 4 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk> 5 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> 6 * Patrick McHardy <kaber@trash.net> 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 * 13 * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith 14 * added netlink_proto_exit 15 * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br> 16 * use nlk_sk, as sk->protinfo is on a diet 8) 17 * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org> 18 * - inc module use count of module that owns 19 * the kernel socket in case userspace opens 20 * socket of same protocol 21 * - remove all module support, since netlink is 22 * mandatory if CONFIG_NET=y these days 23 */ 24 25 #include <linux/module.h> 26 27 #include <linux/capability.h> 28 #include <linux/kernel.h> 29 #include <linux/init.h> 30 #include <linux/signal.h> 31 #include <linux/sched.h> 32 #include <linux/errno.h> 33 #include <linux/string.h> 34 #include <linux/stat.h> 35 #include <linux/socket.h> 36 #include <linux/un.h> 37 #include <linux/fcntl.h> 38 #include <linux/termios.h> 39 #include <linux/sockios.h> 40 #include <linux/net.h> 41 #include <linux/fs.h> 42 #include <linux/slab.h> 43 #include <asm/uaccess.h> 44 #include <linux/skbuff.h> 45 #include <linux/netdevice.h> 46 #include <linux/rtnetlink.h> 47 #include <linux/proc_fs.h> 48 #include <linux/seq_file.h> 49 #include <linux/notifier.h> 50 #include <linux/security.h> 51 #include <linux/jhash.h> 52 #include <linux/jiffies.h> 53 #include <linux/random.h> 54 #include <linux/bitops.h> 55 #include <linux/mm.h> 56 #include <linux/types.h> 57 #include <linux/audit.h> 58 #include <linux/mutex.h> 59 #include <linux/vmalloc.h> 60 #include <linux/if_arp.h> 61 #include <linux/rhashtable.h> 62 #include <asm/cacheflush.h> 63 #include <linux/hash.h> 64 #include <linux/genetlink.h> 65 66 #include <net/net_namespace.h> 67 #include <net/sock.h> 68 #include <net/scm.h> 69 #include <net/netlink.h> 70 71 #include "af_netlink.h" 72 73 struct listeners { 74 struct rcu_head rcu; 75 unsigned long masks[0]; 76 }; 77 78 /* state bits */ 79 #define NETLINK_S_CONGESTED 0x0 80 81 /* flags */ 82 #define NETLINK_F_KERNEL_SOCKET 0x1 83 #define NETLINK_F_RECV_PKTINFO 0x2 84 #define NETLINK_F_BROADCAST_SEND_ERROR 0x4 85 #define NETLINK_F_RECV_NO_ENOBUFS 0x8 86 #define NETLINK_F_LISTEN_ALL_NSID 0x10 87 #define NETLINK_F_CAP_ACK 0x20 88 89 static inline int netlink_is_kernel(struct sock *sk) 90 { 91 return nlk_sk(sk)->flags & NETLINK_F_KERNEL_SOCKET; 92 } 93 94 struct netlink_table *nl_table __read_mostly; 95 EXPORT_SYMBOL_GPL(nl_table); 96 97 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait); 98 99 static int netlink_dump(struct sock *sk); 100 static void netlink_skb_destructor(struct sk_buff *skb); 101 102 /* nl_table locking explained: 103 * Lookup and traversal are protected with an RCU read-side lock. Insertion 104 * and removal are protected with per bucket lock while using RCU list 105 * modification primitives and may run in parallel to RCU protected lookups. 106 * Destruction of the Netlink socket may only occur *after* nl_table_lock has 107 * been acquired * either during or after the socket has been removed from 108 * the list and after an RCU grace period. 109 */ 110 DEFINE_RWLOCK(nl_table_lock); 111 EXPORT_SYMBOL_GPL(nl_table_lock); 112 static atomic_t nl_table_users = ATOMIC_INIT(0); 113 114 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock)); 115 116 static ATOMIC_NOTIFIER_HEAD(netlink_chain); 117 118 static DEFINE_SPINLOCK(netlink_tap_lock); 119 static struct list_head netlink_tap_all __read_mostly; 120 121 static const struct rhashtable_params netlink_rhashtable_params; 122 123 static inline u32 netlink_group_mask(u32 group) 124 { 125 return group ? 1 << (group - 1) : 0; 126 } 127 128 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb, 129 gfp_t gfp_mask) 130 { 131 unsigned int len = skb_end_offset(skb); 132 struct sk_buff *new; 133 134 new = alloc_skb(len, gfp_mask); 135 if (new == NULL) 136 return NULL; 137 138 NETLINK_CB(new).portid = NETLINK_CB(skb).portid; 139 NETLINK_CB(new).dst_group = NETLINK_CB(skb).dst_group; 140 NETLINK_CB(new).creds = NETLINK_CB(skb).creds; 141 142 memcpy(skb_put(new, len), skb->data, len); 143 return new; 144 } 145 146 int netlink_add_tap(struct netlink_tap *nt) 147 { 148 if (unlikely(nt->dev->type != ARPHRD_NETLINK)) 149 return -EINVAL; 150 151 spin_lock(&netlink_tap_lock); 152 list_add_rcu(&nt->list, &netlink_tap_all); 153 spin_unlock(&netlink_tap_lock); 154 155 __module_get(nt->module); 156 157 return 0; 158 } 159 EXPORT_SYMBOL_GPL(netlink_add_tap); 160 161 static int __netlink_remove_tap(struct netlink_tap *nt) 162 { 163 bool found = false; 164 struct netlink_tap *tmp; 165 166 spin_lock(&netlink_tap_lock); 167 168 list_for_each_entry(tmp, &netlink_tap_all, list) { 169 if (nt == tmp) { 170 list_del_rcu(&nt->list); 171 found = true; 172 goto out; 173 } 174 } 175 176 pr_warn("__netlink_remove_tap: %p not found\n", nt); 177 out: 178 spin_unlock(&netlink_tap_lock); 179 180 if (found) 181 module_put(nt->module); 182 183 return found ? 0 : -ENODEV; 184 } 185 186 int netlink_remove_tap(struct netlink_tap *nt) 187 { 188 int ret; 189 190 ret = __netlink_remove_tap(nt); 191 synchronize_net(); 192 193 return ret; 194 } 195 EXPORT_SYMBOL_GPL(netlink_remove_tap); 196 197 static bool netlink_filter_tap(const struct sk_buff *skb) 198 { 199 struct sock *sk = skb->sk; 200 201 /* We take the more conservative approach and 202 * whitelist socket protocols that may pass. 203 */ 204 switch (sk->sk_protocol) { 205 case NETLINK_ROUTE: 206 case NETLINK_USERSOCK: 207 case NETLINK_SOCK_DIAG: 208 case NETLINK_NFLOG: 209 case NETLINK_XFRM: 210 case NETLINK_FIB_LOOKUP: 211 case NETLINK_NETFILTER: 212 case NETLINK_GENERIC: 213 return true; 214 } 215 216 return false; 217 } 218 219 static int __netlink_deliver_tap_skb(struct sk_buff *skb, 220 struct net_device *dev) 221 { 222 struct sk_buff *nskb; 223 struct sock *sk = skb->sk; 224 int ret = -ENOMEM; 225 226 dev_hold(dev); 227 228 if (is_vmalloc_addr(skb->head)) 229 nskb = netlink_to_full_skb(skb, GFP_ATOMIC); 230 else 231 nskb = skb_clone(skb, GFP_ATOMIC); 232 if (nskb) { 233 nskb->dev = dev; 234 nskb->protocol = htons((u16) sk->sk_protocol); 235 nskb->pkt_type = netlink_is_kernel(sk) ? 236 PACKET_KERNEL : PACKET_USER; 237 skb_reset_network_header(nskb); 238 ret = dev_queue_xmit(nskb); 239 if (unlikely(ret > 0)) 240 ret = net_xmit_errno(ret); 241 } 242 243 dev_put(dev); 244 return ret; 245 } 246 247 static void __netlink_deliver_tap(struct sk_buff *skb) 248 { 249 int ret; 250 struct netlink_tap *tmp; 251 252 if (!netlink_filter_tap(skb)) 253 return; 254 255 list_for_each_entry_rcu(tmp, &netlink_tap_all, list) { 256 ret = __netlink_deliver_tap_skb(skb, tmp->dev); 257 if (unlikely(ret)) 258 break; 259 } 260 } 261 262 static void netlink_deliver_tap(struct sk_buff *skb) 263 { 264 rcu_read_lock(); 265 266 if (unlikely(!list_empty(&netlink_tap_all))) 267 __netlink_deliver_tap(skb); 268 269 rcu_read_unlock(); 270 } 271 272 static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src, 273 struct sk_buff *skb) 274 { 275 if (!(netlink_is_kernel(dst) && netlink_is_kernel(src))) 276 netlink_deliver_tap(skb); 277 } 278 279 static void netlink_overrun(struct sock *sk) 280 { 281 struct netlink_sock *nlk = nlk_sk(sk); 282 283 if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) { 284 if (!test_and_set_bit(NETLINK_S_CONGESTED, 285 &nlk_sk(sk)->state)) { 286 sk->sk_err = ENOBUFS; 287 sk->sk_error_report(sk); 288 } 289 } 290 atomic_inc(&sk->sk_drops); 291 } 292 293 static void netlink_rcv_wake(struct sock *sk) 294 { 295 struct netlink_sock *nlk = nlk_sk(sk); 296 297 if (skb_queue_empty(&sk->sk_receive_queue)) 298 clear_bit(NETLINK_S_CONGESTED, &nlk->state); 299 if (!test_bit(NETLINK_S_CONGESTED, &nlk->state)) 300 wake_up_interruptible(&nlk->wait); 301 } 302 303 static void netlink_skb_destructor(struct sk_buff *skb) 304 { 305 if (is_vmalloc_addr(skb->head)) { 306 if (!skb->cloned || 307 !atomic_dec_return(&(skb_shinfo(skb)->dataref))) 308 vfree(skb->head); 309 310 skb->head = NULL; 311 } 312 if (skb->sk != NULL) 313 sock_rfree(skb); 314 } 315 316 static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk) 317 { 318 WARN_ON(skb->sk != NULL); 319 skb->sk = sk; 320 skb->destructor = netlink_skb_destructor; 321 atomic_add(skb->truesize, &sk->sk_rmem_alloc); 322 sk_mem_charge(sk, skb->truesize); 323 } 324 325 static void netlink_sock_destruct(struct sock *sk) 326 { 327 struct netlink_sock *nlk = nlk_sk(sk); 328 329 if (nlk->cb_running) { 330 if (nlk->cb.done) 331 nlk->cb.done(&nlk->cb); 332 333 module_put(nlk->cb.module); 334 kfree_skb(nlk->cb.skb); 335 } 336 337 skb_queue_purge(&sk->sk_receive_queue); 338 339 if (!sock_flag(sk, SOCK_DEAD)) { 340 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk); 341 return; 342 } 343 344 WARN_ON(atomic_read(&sk->sk_rmem_alloc)); 345 WARN_ON(atomic_read(&sk->sk_wmem_alloc)); 346 WARN_ON(nlk_sk(sk)->groups); 347 } 348 349 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on 350 * SMP. Look, when several writers sleep and reader wakes them up, all but one 351 * immediately hit write lock and grab all the cpus. Exclusive sleep solves 352 * this, _but_ remember, it adds useless work on UP machines. 353 */ 354 355 void netlink_table_grab(void) 356 __acquires(nl_table_lock) 357 { 358 might_sleep(); 359 360 write_lock_irq(&nl_table_lock); 361 362 if (atomic_read(&nl_table_users)) { 363 DECLARE_WAITQUEUE(wait, current); 364 365 add_wait_queue_exclusive(&nl_table_wait, &wait); 366 for (;;) { 367 set_current_state(TASK_UNINTERRUPTIBLE); 368 if (atomic_read(&nl_table_users) == 0) 369 break; 370 write_unlock_irq(&nl_table_lock); 371 schedule(); 372 write_lock_irq(&nl_table_lock); 373 } 374 375 __set_current_state(TASK_RUNNING); 376 remove_wait_queue(&nl_table_wait, &wait); 377 } 378 } 379 380 void netlink_table_ungrab(void) 381 __releases(nl_table_lock) 382 { 383 write_unlock_irq(&nl_table_lock); 384 wake_up(&nl_table_wait); 385 } 386 387 static inline void 388 netlink_lock_table(void) 389 { 390 /* read_lock() synchronizes us to netlink_table_grab */ 391 392 read_lock(&nl_table_lock); 393 atomic_inc(&nl_table_users); 394 read_unlock(&nl_table_lock); 395 } 396 397 static inline void 398 netlink_unlock_table(void) 399 { 400 if (atomic_dec_and_test(&nl_table_users)) 401 wake_up(&nl_table_wait); 402 } 403 404 struct netlink_compare_arg 405 { 406 possible_net_t pnet; 407 u32 portid; 408 }; 409 410 /* Doing sizeof directly may yield 4 extra bytes on 64-bit. */ 411 #define netlink_compare_arg_len \ 412 (offsetof(struct netlink_compare_arg, portid) + sizeof(u32)) 413 414 static inline int netlink_compare(struct rhashtable_compare_arg *arg, 415 const void *ptr) 416 { 417 const struct netlink_compare_arg *x = arg->key; 418 const struct netlink_sock *nlk = ptr; 419 420 return nlk->portid != x->portid || 421 !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet)); 422 } 423 424 static void netlink_compare_arg_init(struct netlink_compare_arg *arg, 425 struct net *net, u32 portid) 426 { 427 memset(arg, 0, sizeof(*arg)); 428 write_pnet(&arg->pnet, net); 429 arg->portid = portid; 430 } 431 432 static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid, 433 struct net *net) 434 { 435 struct netlink_compare_arg arg; 436 437 netlink_compare_arg_init(&arg, net, portid); 438 return rhashtable_lookup_fast(&table->hash, &arg, 439 netlink_rhashtable_params); 440 } 441 442 static int __netlink_insert(struct netlink_table *table, struct sock *sk) 443 { 444 struct netlink_compare_arg arg; 445 446 netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid); 447 return rhashtable_lookup_insert_key(&table->hash, &arg, 448 &nlk_sk(sk)->node, 449 netlink_rhashtable_params); 450 } 451 452 static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid) 453 { 454 struct netlink_table *table = &nl_table[protocol]; 455 struct sock *sk; 456 457 rcu_read_lock(); 458 sk = __netlink_lookup(table, portid, net); 459 if (sk) 460 sock_hold(sk); 461 rcu_read_unlock(); 462 463 return sk; 464 } 465 466 static const struct proto_ops netlink_ops; 467 468 static void 469 netlink_update_listeners(struct sock *sk) 470 { 471 struct netlink_table *tbl = &nl_table[sk->sk_protocol]; 472 unsigned long mask; 473 unsigned int i; 474 struct listeners *listeners; 475 476 listeners = nl_deref_protected(tbl->listeners); 477 if (!listeners) 478 return; 479 480 for (i = 0; i < NLGRPLONGS(tbl->groups); i++) { 481 mask = 0; 482 sk_for_each_bound(sk, &tbl->mc_list) { 483 if (i < NLGRPLONGS(nlk_sk(sk)->ngroups)) 484 mask |= nlk_sk(sk)->groups[i]; 485 } 486 listeners->masks[i] = mask; 487 } 488 /* this function is only called with the netlink table "grabbed", which 489 * makes sure updates are visible before bind or setsockopt return. */ 490 } 491 492 static int netlink_insert(struct sock *sk, u32 portid) 493 { 494 struct netlink_table *table = &nl_table[sk->sk_protocol]; 495 int err; 496 497 lock_sock(sk); 498 499 err = nlk_sk(sk)->portid == portid ? 0 : -EBUSY; 500 if (nlk_sk(sk)->bound) 501 goto err; 502 503 err = -ENOMEM; 504 if (BITS_PER_LONG > 32 && 505 unlikely(atomic_read(&table->hash.nelems) >= UINT_MAX)) 506 goto err; 507 508 nlk_sk(sk)->portid = portid; 509 sock_hold(sk); 510 511 err = __netlink_insert(table, sk); 512 if (err) { 513 /* In case the hashtable backend returns with -EBUSY 514 * from here, it must not escape to the caller. 515 */ 516 if (unlikely(err == -EBUSY)) 517 err = -EOVERFLOW; 518 if (err == -EEXIST) 519 err = -EADDRINUSE; 520 sock_put(sk); 521 goto err; 522 } 523 524 /* We need to ensure that the socket is hashed and visible. */ 525 smp_wmb(); 526 nlk_sk(sk)->bound = portid; 527 528 err: 529 release_sock(sk); 530 return err; 531 } 532 533 static void netlink_remove(struct sock *sk) 534 { 535 struct netlink_table *table; 536 537 table = &nl_table[sk->sk_protocol]; 538 if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node, 539 netlink_rhashtable_params)) { 540 WARN_ON(atomic_read(&sk->sk_refcnt) == 1); 541 __sock_put(sk); 542 } 543 544 netlink_table_grab(); 545 if (nlk_sk(sk)->subscriptions) { 546 __sk_del_bind_node(sk); 547 netlink_update_listeners(sk); 548 } 549 if (sk->sk_protocol == NETLINK_GENERIC) 550 atomic_inc(&genl_sk_destructing_cnt); 551 netlink_table_ungrab(); 552 } 553 554 static struct proto netlink_proto = { 555 .name = "NETLINK", 556 .owner = THIS_MODULE, 557 .obj_size = sizeof(struct netlink_sock), 558 }; 559 560 static int __netlink_create(struct net *net, struct socket *sock, 561 struct mutex *cb_mutex, int protocol, 562 int kern) 563 { 564 struct sock *sk; 565 struct netlink_sock *nlk; 566 567 sock->ops = &netlink_ops; 568 569 sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto, kern); 570 if (!sk) 571 return -ENOMEM; 572 573 sock_init_data(sock, sk); 574 575 nlk = nlk_sk(sk); 576 if (cb_mutex) { 577 nlk->cb_mutex = cb_mutex; 578 } else { 579 nlk->cb_mutex = &nlk->cb_def_mutex; 580 mutex_init(nlk->cb_mutex); 581 } 582 init_waitqueue_head(&nlk->wait); 583 584 sk->sk_destruct = netlink_sock_destruct; 585 sk->sk_protocol = protocol; 586 return 0; 587 } 588 589 static int netlink_create(struct net *net, struct socket *sock, int protocol, 590 int kern) 591 { 592 struct module *module = NULL; 593 struct mutex *cb_mutex; 594 struct netlink_sock *nlk; 595 int (*bind)(struct net *net, int group); 596 void (*unbind)(struct net *net, int group); 597 int err = 0; 598 599 sock->state = SS_UNCONNECTED; 600 601 if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM) 602 return -ESOCKTNOSUPPORT; 603 604 if (protocol < 0 || protocol >= MAX_LINKS) 605 return -EPROTONOSUPPORT; 606 607 netlink_lock_table(); 608 #ifdef CONFIG_MODULES 609 if (!nl_table[protocol].registered) { 610 netlink_unlock_table(); 611 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol); 612 netlink_lock_table(); 613 } 614 #endif 615 if (nl_table[protocol].registered && 616 try_module_get(nl_table[protocol].module)) 617 module = nl_table[protocol].module; 618 else 619 err = -EPROTONOSUPPORT; 620 cb_mutex = nl_table[protocol].cb_mutex; 621 bind = nl_table[protocol].bind; 622 unbind = nl_table[protocol].unbind; 623 netlink_unlock_table(); 624 625 if (err < 0) 626 goto out; 627 628 err = __netlink_create(net, sock, cb_mutex, protocol, kern); 629 if (err < 0) 630 goto out_module; 631 632 local_bh_disable(); 633 sock_prot_inuse_add(net, &netlink_proto, 1); 634 local_bh_enable(); 635 636 nlk = nlk_sk(sock->sk); 637 nlk->module = module; 638 nlk->netlink_bind = bind; 639 nlk->netlink_unbind = unbind; 640 out: 641 return err; 642 643 out_module: 644 module_put(module); 645 goto out; 646 } 647 648 static void deferred_put_nlk_sk(struct rcu_head *head) 649 { 650 struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu); 651 652 sock_put(&nlk->sk); 653 } 654 655 static int netlink_release(struct socket *sock) 656 { 657 struct sock *sk = sock->sk; 658 struct netlink_sock *nlk; 659 660 if (!sk) 661 return 0; 662 663 netlink_remove(sk); 664 sock_orphan(sk); 665 nlk = nlk_sk(sk); 666 667 /* 668 * OK. Socket is unlinked, any packets that arrive now 669 * will be purged. 670 */ 671 672 /* must not acquire netlink_table_lock in any way again before unbind 673 * and notifying genetlink is done as otherwise it might deadlock 674 */ 675 if (nlk->netlink_unbind) { 676 int i; 677 678 for (i = 0; i < nlk->ngroups; i++) 679 if (test_bit(i, nlk->groups)) 680 nlk->netlink_unbind(sock_net(sk), i + 1); 681 } 682 if (sk->sk_protocol == NETLINK_GENERIC && 683 atomic_dec_return(&genl_sk_destructing_cnt) == 0) 684 wake_up(&genl_sk_destructing_waitq); 685 686 sock->sk = NULL; 687 wake_up_interruptible_all(&nlk->wait); 688 689 skb_queue_purge(&sk->sk_write_queue); 690 691 if (nlk->portid) { 692 struct netlink_notify n = { 693 .net = sock_net(sk), 694 .protocol = sk->sk_protocol, 695 .portid = nlk->portid, 696 }; 697 atomic_notifier_call_chain(&netlink_chain, 698 NETLINK_URELEASE, &n); 699 } 700 701 module_put(nlk->module); 702 703 if (netlink_is_kernel(sk)) { 704 netlink_table_grab(); 705 BUG_ON(nl_table[sk->sk_protocol].registered == 0); 706 if (--nl_table[sk->sk_protocol].registered == 0) { 707 struct listeners *old; 708 709 old = nl_deref_protected(nl_table[sk->sk_protocol].listeners); 710 RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL); 711 kfree_rcu(old, rcu); 712 nl_table[sk->sk_protocol].module = NULL; 713 nl_table[sk->sk_protocol].bind = NULL; 714 nl_table[sk->sk_protocol].unbind = NULL; 715 nl_table[sk->sk_protocol].flags = 0; 716 nl_table[sk->sk_protocol].registered = 0; 717 } 718 netlink_table_ungrab(); 719 } 720 721 kfree(nlk->groups); 722 nlk->groups = NULL; 723 724 local_bh_disable(); 725 sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1); 726 local_bh_enable(); 727 call_rcu(&nlk->rcu, deferred_put_nlk_sk); 728 return 0; 729 } 730 731 static int netlink_autobind(struct socket *sock) 732 { 733 struct sock *sk = sock->sk; 734 struct net *net = sock_net(sk); 735 struct netlink_table *table = &nl_table[sk->sk_protocol]; 736 s32 portid = task_tgid_vnr(current); 737 int err; 738 s32 rover = -4096; 739 bool ok; 740 741 retry: 742 cond_resched(); 743 rcu_read_lock(); 744 ok = !__netlink_lookup(table, portid, net); 745 rcu_read_unlock(); 746 if (!ok) { 747 /* Bind collision, search negative portid values. */ 748 if (rover == -4096) 749 /* rover will be in range [S32_MIN, -4097] */ 750 rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN); 751 else if (rover >= -4096) 752 rover = -4097; 753 portid = rover--; 754 goto retry; 755 } 756 757 err = netlink_insert(sk, portid); 758 if (err == -EADDRINUSE) 759 goto retry; 760 761 /* If 2 threads race to autobind, that is fine. */ 762 if (err == -EBUSY) 763 err = 0; 764 765 return err; 766 } 767 768 /** 769 * __netlink_ns_capable - General netlink message capability test 770 * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace. 771 * @user_ns: The user namespace of the capability to use 772 * @cap: The capability to use 773 * 774 * Test to see if the opener of the socket we received the message 775 * from had when the netlink socket was created and the sender of the 776 * message has has the capability @cap in the user namespace @user_ns. 777 */ 778 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp, 779 struct user_namespace *user_ns, int cap) 780 { 781 return ((nsp->flags & NETLINK_SKB_DST) || 782 file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) && 783 ns_capable(user_ns, cap); 784 } 785 EXPORT_SYMBOL(__netlink_ns_capable); 786 787 /** 788 * netlink_ns_capable - General netlink message capability test 789 * @skb: socket buffer holding a netlink command from userspace 790 * @user_ns: The user namespace of the capability to use 791 * @cap: The capability to use 792 * 793 * Test to see if the opener of the socket we received the message 794 * from had when the netlink socket was created and the sender of the 795 * message has has the capability @cap in the user namespace @user_ns. 796 */ 797 bool netlink_ns_capable(const struct sk_buff *skb, 798 struct user_namespace *user_ns, int cap) 799 { 800 return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap); 801 } 802 EXPORT_SYMBOL(netlink_ns_capable); 803 804 /** 805 * netlink_capable - Netlink global message capability test 806 * @skb: socket buffer holding a netlink command from userspace 807 * @cap: The capability to use 808 * 809 * Test to see if the opener of the socket we received the message 810 * from had when the netlink socket was created and the sender of the 811 * message has has the capability @cap in all user namespaces. 812 */ 813 bool netlink_capable(const struct sk_buff *skb, int cap) 814 { 815 return netlink_ns_capable(skb, &init_user_ns, cap); 816 } 817 EXPORT_SYMBOL(netlink_capable); 818 819 /** 820 * netlink_net_capable - Netlink network namespace message capability test 821 * @skb: socket buffer holding a netlink command from userspace 822 * @cap: The capability to use 823 * 824 * Test to see if the opener of the socket we received the message 825 * from had when the netlink socket was created and the sender of the 826 * message has has the capability @cap over the network namespace of 827 * the socket we received the message from. 828 */ 829 bool netlink_net_capable(const struct sk_buff *skb, int cap) 830 { 831 return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap); 832 } 833 EXPORT_SYMBOL(netlink_net_capable); 834 835 static inline int netlink_allowed(const struct socket *sock, unsigned int flag) 836 { 837 return (nl_table[sock->sk->sk_protocol].flags & flag) || 838 ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN); 839 } 840 841 static void 842 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions) 843 { 844 struct netlink_sock *nlk = nlk_sk(sk); 845 846 if (nlk->subscriptions && !subscriptions) 847 __sk_del_bind_node(sk); 848 else if (!nlk->subscriptions && subscriptions) 849 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list); 850 nlk->subscriptions = subscriptions; 851 } 852 853 static int netlink_realloc_groups(struct sock *sk) 854 { 855 struct netlink_sock *nlk = nlk_sk(sk); 856 unsigned int groups; 857 unsigned long *new_groups; 858 int err = 0; 859 860 netlink_table_grab(); 861 862 groups = nl_table[sk->sk_protocol].groups; 863 if (!nl_table[sk->sk_protocol].registered) { 864 err = -ENOENT; 865 goto out_unlock; 866 } 867 868 if (nlk->ngroups >= groups) 869 goto out_unlock; 870 871 new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC); 872 if (new_groups == NULL) { 873 err = -ENOMEM; 874 goto out_unlock; 875 } 876 memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0, 877 NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups)); 878 879 nlk->groups = new_groups; 880 nlk->ngroups = groups; 881 out_unlock: 882 netlink_table_ungrab(); 883 return err; 884 } 885 886 static void netlink_undo_bind(int group, long unsigned int groups, 887 struct sock *sk) 888 { 889 struct netlink_sock *nlk = nlk_sk(sk); 890 int undo; 891 892 if (!nlk->netlink_unbind) 893 return; 894 895 for (undo = 0; undo < group; undo++) 896 if (test_bit(undo, &groups)) 897 nlk->netlink_unbind(sock_net(sk), undo + 1); 898 } 899 900 static int netlink_bind(struct socket *sock, struct sockaddr *addr, 901 int addr_len) 902 { 903 struct sock *sk = sock->sk; 904 struct net *net = sock_net(sk); 905 struct netlink_sock *nlk = nlk_sk(sk); 906 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; 907 int err; 908 long unsigned int groups = nladdr->nl_groups; 909 bool bound; 910 911 if (addr_len < sizeof(struct sockaddr_nl)) 912 return -EINVAL; 913 914 if (nladdr->nl_family != AF_NETLINK) 915 return -EINVAL; 916 917 /* Only superuser is allowed to listen multicasts */ 918 if (groups) { 919 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV)) 920 return -EPERM; 921 err = netlink_realloc_groups(sk); 922 if (err) 923 return err; 924 } 925 926 bound = nlk->bound; 927 if (bound) { 928 /* Ensure nlk->portid is up-to-date. */ 929 smp_rmb(); 930 931 if (nladdr->nl_pid != nlk->portid) 932 return -EINVAL; 933 } 934 935 if (nlk->netlink_bind && groups) { 936 int group; 937 938 for (group = 0; group < nlk->ngroups; group++) { 939 if (!test_bit(group, &groups)) 940 continue; 941 err = nlk->netlink_bind(net, group + 1); 942 if (!err) 943 continue; 944 netlink_undo_bind(group, groups, sk); 945 return err; 946 } 947 } 948 949 /* No need for barriers here as we return to user-space without 950 * using any of the bound attributes. 951 */ 952 if (!bound) { 953 err = nladdr->nl_pid ? 954 netlink_insert(sk, nladdr->nl_pid) : 955 netlink_autobind(sock); 956 if (err) { 957 netlink_undo_bind(nlk->ngroups, groups, sk); 958 return err; 959 } 960 } 961 962 if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0])) 963 return 0; 964 965 netlink_table_grab(); 966 netlink_update_subscriptions(sk, nlk->subscriptions + 967 hweight32(groups) - 968 hweight32(nlk->groups[0])); 969 nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups; 970 netlink_update_listeners(sk); 971 netlink_table_ungrab(); 972 973 return 0; 974 } 975 976 static int netlink_connect(struct socket *sock, struct sockaddr *addr, 977 int alen, int flags) 978 { 979 int err = 0; 980 struct sock *sk = sock->sk; 981 struct netlink_sock *nlk = nlk_sk(sk); 982 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; 983 984 if (alen < sizeof(addr->sa_family)) 985 return -EINVAL; 986 987 if (addr->sa_family == AF_UNSPEC) { 988 sk->sk_state = NETLINK_UNCONNECTED; 989 nlk->dst_portid = 0; 990 nlk->dst_group = 0; 991 return 0; 992 } 993 if (addr->sa_family != AF_NETLINK) 994 return -EINVAL; 995 996 if ((nladdr->nl_groups || nladdr->nl_pid) && 997 !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND)) 998 return -EPERM; 999 1000 /* No need for barriers here as we return to user-space without 1001 * using any of the bound attributes. 1002 */ 1003 if (!nlk->bound) 1004 err = netlink_autobind(sock); 1005 1006 if (err == 0) { 1007 sk->sk_state = NETLINK_CONNECTED; 1008 nlk->dst_portid = nladdr->nl_pid; 1009 nlk->dst_group = ffs(nladdr->nl_groups); 1010 } 1011 1012 return err; 1013 } 1014 1015 static int netlink_getname(struct socket *sock, struct sockaddr *addr, 1016 int *addr_len, int peer) 1017 { 1018 struct sock *sk = sock->sk; 1019 struct netlink_sock *nlk = nlk_sk(sk); 1020 DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr); 1021 1022 nladdr->nl_family = AF_NETLINK; 1023 nladdr->nl_pad = 0; 1024 *addr_len = sizeof(*nladdr); 1025 1026 if (peer) { 1027 nladdr->nl_pid = nlk->dst_portid; 1028 nladdr->nl_groups = netlink_group_mask(nlk->dst_group); 1029 } else { 1030 nladdr->nl_pid = nlk->portid; 1031 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0; 1032 } 1033 return 0; 1034 } 1035 1036 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid) 1037 { 1038 struct sock *sock; 1039 struct netlink_sock *nlk; 1040 1041 sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid); 1042 if (!sock) 1043 return ERR_PTR(-ECONNREFUSED); 1044 1045 /* Don't bother queuing skb if kernel socket has no input function */ 1046 nlk = nlk_sk(sock); 1047 if (sock->sk_state == NETLINK_CONNECTED && 1048 nlk->dst_portid != nlk_sk(ssk)->portid) { 1049 sock_put(sock); 1050 return ERR_PTR(-ECONNREFUSED); 1051 } 1052 return sock; 1053 } 1054 1055 struct sock *netlink_getsockbyfilp(struct file *filp) 1056 { 1057 struct inode *inode = file_inode(filp); 1058 struct sock *sock; 1059 1060 if (!S_ISSOCK(inode->i_mode)) 1061 return ERR_PTR(-ENOTSOCK); 1062 1063 sock = SOCKET_I(inode)->sk; 1064 if (sock->sk_family != AF_NETLINK) 1065 return ERR_PTR(-EINVAL); 1066 1067 sock_hold(sock); 1068 return sock; 1069 } 1070 1071 static struct sk_buff *netlink_alloc_large_skb(unsigned int size, 1072 int broadcast) 1073 { 1074 struct sk_buff *skb; 1075 void *data; 1076 1077 if (size <= NLMSG_GOODSIZE || broadcast) 1078 return alloc_skb(size, GFP_KERNEL); 1079 1080 size = SKB_DATA_ALIGN(size) + 1081 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); 1082 1083 data = vmalloc(size); 1084 if (data == NULL) 1085 return NULL; 1086 1087 skb = __build_skb(data, size); 1088 if (skb == NULL) 1089 vfree(data); 1090 else 1091 skb->destructor = netlink_skb_destructor; 1092 1093 return skb; 1094 } 1095 1096 /* 1097 * Attach a skb to a netlink socket. 1098 * The caller must hold a reference to the destination socket. On error, the 1099 * reference is dropped. The skb is not send to the destination, just all 1100 * all error checks are performed and memory in the queue is reserved. 1101 * Return values: 1102 * < 0: error. skb freed, reference to sock dropped. 1103 * 0: continue 1104 * 1: repeat lookup - reference dropped while waiting for socket memory. 1105 */ 1106 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, 1107 long *timeo, struct sock *ssk) 1108 { 1109 struct netlink_sock *nlk; 1110 1111 nlk = nlk_sk(sk); 1112 1113 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || 1114 test_bit(NETLINK_S_CONGESTED, &nlk->state))) { 1115 DECLARE_WAITQUEUE(wait, current); 1116 if (!*timeo) { 1117 if (!ssk || netlink_is_kernel(ssk)) 1118 netlink_overrun(sk); 1119 sock_put(sk); 1120 kfree_skb(skb); 1121 return -EAGAIN; 1122 } 1123 1124 __set_current_state(TASK_INTERRUPTIBLE); 1125 add_wait_queue(&nlk->wait, &wait); 1126 1127 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || 1128 test_bit(NETLINK_S_CONGESTED, &nlk->state)) && 1129 !sock_flag(sk, SOCK_DEAD)) 1130 *timeo = schedule_timeout(*timeo); 1131 1132 __set_current_state(TASK_RUNNING); 1133 remove_wait_queue(&nlk->wait, &wait); 1134 sock_put(sk); 1135 1136 if (signal_pending(current)) { 1137 kfree_skb(skb); 1138 return sock_intr_errno(*timeo); 1139 } 1140 return 1; 1141 } 1142 netlink_skb_set_owner_r(skb, sk); 1143 return 0; 1144 } 1145 1146 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb) 1147 { 1148 int len = skb->len; 1149 1150 netlink_deliver_tap(skb); 1151 1152 skb_queue_tail(&sk->sk_receive_queue, skb); 1153 sk->sk_data_ready(sk); 1154 return len; 1155 } 1156 1157 int netlink_sendskb(struct sock *sk, struct sk_buff *skb) 1158 { 1159 int len = __netlink_sendskb(sk, skb); 1160 1161 sock_put(sk); 1162 return len; 1163 } 1164 1165 void netlink_detachskb(struct sock *sk, struct sk_buff *skb) 1166 { 1167 kfree_skb(skb); 1168 sock_put(sk); 1169 } 1170 1171 static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation) 1172 { 1173 int delta; 1174 1175 WARN_ON(skb->sk != NULL); 1176 delta = skb->end - skb->tail; 1177 if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize) 1178 return skb; 1179 1180 if (skb_shared(skb)) { 1181 struct sk_buff *nskb = skb_clone(skb, allocation); 1182 if (!nskb) 1183 return skb; 1184 consume_skb(skb); 1185 skb = nskb; 1186 } 1187 1188 if (!pskb_expand_head(skb, 0, -delta, allocation)) 1189 skb->truesize -= delta; 1190 1191 return skb; 1192 } 1193 1194 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb, 1195 struct sock *ssk) 1196 { 1197 int ret; 1198 struct netlink_sock *nlk = nlk_sk(sk); 1199 1200 ret = -ECONNREFUSED; 1201 if (nlk->netlink_rcv != NULL) { 1202 ret = skb->len; 1203 netlink_skb_set_owner_r(skb, sk); 1204 NETLINK_CB(skb).sk = ssk; 1205 netlink_deliver_tap_kernel(sk, ssk, skb); 1206 nlk->netlink_rcv(skb); 1207 consume_skb(skb); 1208 } else { 1209 kfree_skb(skb); 1210 } 1211 sock_put(sk); 1212 return ret; 1213 } 1214 1215 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, 1216 u32 portid, int nonblock) 1217 { 1218 struct sock *sk; 1219 int err; 1220 long timeo; 1221 1222 skb = netlink_trim(skb, gfp_any()); 1223 1224 timeo = sock_sndtimeo(ssk, nonblock); 1225 retry: 1226 sk = netlink_getsockbyportid(ssk, portid); 1227 if (IS_ERR(sk)) { 1228 kfree_skb(skb); 1229 return PTR_ERR(sk); 1230 } 1231 if (netlink_is_kernel(sk)) 1232 return netlink_unicast_kernel(sk, skb, ssk); 1233 1234 if (sk_filter(sk, skb)) { 1235 err = skb->len; 1236 kfree_skb(skb); 1237 sock_put(sk); 1238 return err; 1239 } 1240 1241 err = netlink_attachskb(sk, skb, &timeo, ssk); 1242 if (err == 1) 1243 goto retry; 1244 if (err) 1245 return err; 1246 1247 return netlink_sendskb(sk, skb); 1248 } 1249 EXPORT_SYMBOL(netlink_unicast); 1250 1251 int netlink_has_listeners(struct sock *sk, unsigned int group) 1252 { 1253 int res = 0; 1254 struct listeners *listeners; 1255 1256 BUG_ON(!netlink_is_kernel(sk)); 1257 1258 rcu_read_lock(); 1259 listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners); 1260 1261 if (listeners && group - 1 < nl_table[sk->sk_protocol].groups) 1262 res = test_bit(group - 1, listeners->masks); 1263 1264 rcu_read_unlock(); 1265 1266 return res; 1267 } 1268 EXPORT_SYMBOL_GPL(netlink_has_listeners); 1269 1270 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb) 1271 { 1272 struct netlink_sock *nlk = nlk_sk(sk); 1273 1274 if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf && 1275 !test_bit(NETLINK_S_CONGESTED, &nlk->state)) { 1276 netlink_skb_set_owner_r(skb, sk); 1277 __netlink_sendskb(sk, skb); 1278 return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1); 1279 } 1280 return -1; 1281 } 1282 1283 struct netlink_broadcast_data { 1284 struct sock *exclude_sk; 1285 struct net *net; 1286 u32 portid; 1287 u32 group; 1288 int failure; 1289 int delivery_failure; 1290 int congested; 1291 int delivered; 1292 gfp_t allocation; 1293 struct sk_buff *skb, *skb2; 1294 int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data); 1295 void *tx_data; 1296 }; 1297 1298 static void do_one_broadcast(struct sock *sk, 1299 struct netlink_broadcast_data *p) 1300 { 1301 struct netlink_sock *nlk = nlk_sk(sk); 1302 int val; 1303 1304 if (p->exclude_sk == sk) 1305 return; 1306 1307 if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups || 1308 !test_bit(p->group - 1, nlk->groups)) 1309 return; 1310 1311 if (!net_eq(sock_net(sk), p->net)) { 1312 if (!(nlk->flags & NETLINK_F_LISTEN_ALL_NSID)) 1313 return; 1314 1315 if (!peernet_has_id(sock_net(sk), p->net)) 1316 return; 1317 1318 if (!file_ns_capable(sk->sk_socket->file, p->net->user_ns, 1319 CAP_NET_BROADCAST)) 1320 return; 1321 } 1322 1323 if (p->failure) { 1324 netlink_overrun(sk); 1325 return; 1326 } 1327 1328 sock_hold(sk); 1329 if (p->skb2 == NULL) { 1330 if (skb_shared(p->skb)) { 1331 p->skb2 = skb_clone(p->skb, p->allocation); 1332 } else { 1333 p->skb2 = skb_get(p->skb); 1334 /* 1335 * skb ownership may have been set when 1336 * delivered to a previous socket. 1337 */ 1338 skb_orphan(p->skb2); 1339 } 1340 } 1341 if (p->skb2 == NULL) { 1342 netlink_overrun(sk); 1343 /* Clone failed. Notify ALL listeners. */ 1344 p->failure = 1; 1345 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR) 1346 p->delivery_failure = 1; 1347 goto out; 1348 } 1349 if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) { 1350 kfree_skb(p->skb2); 1351 p->skb2 = NULL; 1352 goto out; 1353 } 1354 if (sk_filter(sk, p->skb2)) { 1355 kfree_skb(p->skb2); 1356 p->skb2 = NULL; 1357 goto out; 1358 } 1359 NETLINK_CB(p->skb2).nsid = peernet2id(sock_net(sk), p->net); 1360 NETLINK_CB(p->skb2).nsid_is_set = true; 1361 val = netlink_broadcast_deliver(sk, p->skb2); 1362 if (val < 0) { 1363 netlink_overrun(sk); 1364 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR) 1365 p->delivery_failure = 1; 1366 } else { 1367 p->congested |= val; 1368 p->delivered = 1; 1369 p->skb2 = NULL; 1370 } 1371 out: 1372 sock_put(sk); 1373 } 1374 1375 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 portid, 1376 u32 group, gfp_t allocation, 1377 int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data), 1378 void *filter_data) 1379 { 1380 struct net *net = sock_net(ssk); 1381 struct netlink_broadcast_data info; 1382 struct sock *sk; 1383 1384 skb = netlink_trim(skb, allocation); 1385 1386 info.exclude_sk = ssk; 1387 info.net = net; 1388 info.portid = portid; 1389 info.group = group; 1390 info.failure = 0; 1391 info.delivery_failure = 0; 1392 info.congested = 0; 1393 info.delivered = 0; 1394 info.allocation = allocation; 1395 info.skb = skb; 1396 info.skb2 = NULL; 1397 info.tx_filter = filter; 1398 info.tx_data = filter_data; 1399 1400 /* While we sleep in clone, do not allow to change socket list */ 1401 1402 netlink_lock_table(); 1403 1404 sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list) 1405 do_one_broadcast(sk, &info); 1406 1407 consume_skb(skb); 1408 1409 netlink_unlock_table(); 1410 1411 if (info.delivery_failure) { 1412 kfree_skb(info.skb2); 1413 return -ENOBUFS; 1414 } 1415 consume_skb(info.skb2); 1416 1417 if (info.delivered) { 1418 if (info.congested && gfpflags_allow_blocking(allocation)) 1419 yield(); 1420 return 0; 1421 } 1422 return -ESRCH; 1423 } 1424 EXPORT_SYMBOL(netlink_broadcast_filtered); 1425 1426 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid, 1427 u32 group, gfp_t allocation) 1428 { 1429 return netlink_broadcast_filtered(ssk, skb, portid, group, allocation, 1430 NULL, NULL); 1431 } 1432 EXPORT_SYMBOL(netlink_broadcast); 1433 1434 struct netlink_set_err_data { 1435 struct sock *exclude_sk; 1436 u32 portid; 1437 u32 group; 1438 int code; 1439 }; 1440 1441 static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p) 1442 { 1443 struct netlink_sock *nlk = nlk_sk(sk); 1444 int ret = 0; 1445 1446 if (sk == p->exclude_sk) 1447 goto out; 1448 1449 if (!net_eq(sock_net(sk), sock_net(p->exclude_sk))) 1450 goto out; 1451 1452 if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups || 1453 !test_bit(p->group - 1, nlk->groups)) 1454 goto out; 1455 1456 if (p->code == ENOBUFS && nlk->flags & NETLINK_F_RECV_NO_ENOBUFS) { 1457 ret = 1; 1458 goto out; 1459 } 1460 1461 sk->sk_err = p->code; 1462 sk->sk_error_report(sk); 1463 out: 1464 return ret; 1465 } 1466 1467 /** 1468 * netlink_set_err - report error to broadcast listeners 1469 * @ssk: the kernel netlink socket, as returned by netlink_kernel_create() 1470 * @portid: the PORTID of a process that we want to skip (if any) 1471 * @group: the broadcast group that will notice the error 1472 * @code: error code, must be negative (as usual in kernelspace) 1473 * 1474 * This function returns the number of broadcast listeners that have set the 1475 * NETLINK_NO_ENOBUFS socket option. 1476 */ 1477 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code) 1478 { 1479 struct netlink_set_err_data info; 1480 struct sock *sk; 1481 int ret = 0; 1482 1483 info.exclude_sk = ssk; 1484 info.portid = portid; 1485 info.group = group; 1486 /* sk->sk_err wants a positive error value */ 1487 info.code = -code; 1488 1489 read_lock(&nl_table_lock); 1490 1491 sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list) 1492 ret += do_one_set_err(sk, &info); 1493 1494 read_unlock(&nl_table_lock); 1495 return ret; 1496 } 1497 EXPORT_SYMBOL(netlink_set_err); 1498 1499 /* must be called with netlink table grabbed */ 1500 static void netlink_update_socket_mc(struct netlink_sock *nlk, 1501 unsigned int group, 1502 int is_new) 1503 { 1504 int old, new = !!is_new, subscriptions; 1505 1506 old = test_bit(group - 1, nlk->groups); 1507 subscriptions = nlk->subscriptions - old + new; 1508 if (new) 1509 __set_bit(group - 1, nlk->groups); 1510 else 1511 __clear_bit(group - 1, nlk->groups); 1512 netlink_update_subscriptions(&nlk->sk, subscriptions); 1513 netlink_update_listeners(&nlk->sk); 1514 } 1515 1516 static int netlink_setsockopt(struct socket *sock, int level, int optname, 1517 char __user *optval, unsigned int optlen) 1518 { 1519 struct sock *sk = sock->sk; 1520 struct netlink_sock *nlk = nlk_sk(sk); 1521 unsigned int val = 0; 1522 int err; 1523 1524 if (level != SOL_NETLINK) 1525 return -ENOPROTOOPT; 1526 1527 if (optlen >= sizeof(int) && 1528 get_user(val, (unsigned int __user *)optval)) 1529 return -EFAULT; 1530 1531 switch (optname) { 1532 case NETLINK_PKTINFO: 1533 if (val) 1534 nlk->flags |= NETLINK_F_RECV_PKTINFO; 1535 else 1536 nlk->flags &= ~NETLINK_F_RECV_PKTINFO; 1537 err = 0; 1538 break; 1539 case NETLINK_ADD_MEMBERSHIP: 1540 case NETLINK_DROP_MEMBERSHIP: { 1541 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV)) 1542 return -EPERM; 1543 err = netlink_realloc_groups(sk); 1544 if (err) 1545 return err; 1546 if (!val || val - 1 >= nlk->ngroups) 1547 return -EINVAL; 1548 if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) { 1549 err = nlk->netlink_bind(sock_net(sk), val); 1550 if (err) 1551 return err; 1552 } 1553 netlink_table_grab(); 1554 netlink_update_socket_mc(nlk, val, 1555 optname == NETLINK_ADD_MEMBERSHIP); 1556 netlink_table_ungrab(); 1557 if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind) 1558 nlk->netlink_unbind(sock_net(sk), val); 1559 1560 err = 0; 1561 break; 1562 } 1563 case NETLINK_BROADCAST_ERROR: 1564 if (val) 1565 nlk->flags |= NETLINK_F_BROADCAST_SEND_ERROR; 1566 else 1567 nlk->flags &= ~NETLINK_F_BROADCAST_SEND_ERROR; 1568 err = 0; 1569 break; 1570 case NETLINK_NO_ENOBUFS: 1571 if (val) { 1572 nlk->flags |= NETLINK_F_RECV_NO_ENOBUFS; 1573 clear_bit(NETLINK_S_CONGESTED, &nlk->state); 1574 wake_up_interruptible(&nlk->wait); 1575 } else { 1576 nlk->flags &= ~NETLINK_F_RECV_NO_ENOBUFS; 1577 } 1578 err = 0; 1579 break; 1580 case NETLINK_LISTEN_ALL_NSID: 1581 if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST)) 1582 return -EPERM; 1583 1584 if (val) 1585 nlk->flags |= NETLINK_F_LISTEN_ALL_NSID; 1586 else 1587 nlk->flags &= ~NETLINK_F_LISTEN_ALL_NSID; 1588 err = 0; 1589 break; 1590 case NETLINK_CAP_ACK: 1591 if (val) 1592 nlk->flags |= NETLINK_F_CAP_ACK; 1593 else 1594 nlk->flags &= ~NETLINK_F_CAP_ACK; 1595 err = 0; 1596 break; 1597 default: 1598 err = -ENOPROTOOPT; 1599 } 1600 return err; 1601 } 1602 1603 static int netlink_getsockopt(struct socket *sock, int level, int optname, 1604 char __user *optval, int __user *optlen) 1605 { 1606 struct sock *sk = sock->sk; 1607 struct netlink_sock *nlk = nlk_sk(sk); 1608 int len, val, err; 1609 1610 if (level != SOL_NETLINK) 1611 return -ENOPROTOOPT; 1612 1613 if (get_user(len, optlen)) 1614 return -EFAULT; 1615 if (len < 0) 1616 return -EINVAL; 1617 1618 switch (optname) { 1619 case NETLINK_PKTINFO: 1620 if (len < sizeof(int)) 1621 return -EINVAL; 1622 len = sizeof(int); 1623 val = nlk->flags & NETLINK_F_RECV_PKTINFO ? 1 : 0; 1624 if (put_user(len, optlen) || 1625 put_user(val, optval)) 1626 return -EFAULT; 1627 err = 0; 1628 break; 1629 case NETLINK_BROADCAST_ERROR: 1630 if (len < sizeof(int)) 1631 return -EINVAL; 1632 len = sizeof(int); 1633 val = nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR ? 1 : 0; 1634 if (put_user(len, optlen) || 1635 put_user(val, optval)) 1636 return -EFAULT; 1637 err = 0; 1638 break; 1639 case NETLINK_NO_ENOBUFS: 1640 if (len < sizeof(int)) 1641 return -EINVAL; 1642 len = sizeof(int); 1643 val = nlk->flags & NETLINK_F_RECV_NO_ENOBUFS ? 1 : 0; 1644 if (put_user(len, optlen) || 1645 put_user(val, optval)) 1646 return -EFAULT; 1647 err = 0; 1648 break; 1649 case NETLINK_LIST_MEMBERSHIPS: { 1650 int pos, idx, shift; 1651 1652 err = 0; 1653 netlink_lock_table(); 1654 for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) { 1655 if (len - pos < sizeof(u32)) 1656 break; 1657 1658 idx = pos / sizeof(unsigned long); 1659 shift = (pos % sizeof(unsigned long)) * 8; 1660 if (put_user((u32)(nlk->groups[idx] >> shift), 1661 (u32 __user *)(optval + pos))) { 1662 err = -EFAULT; 1663 break; 1664 } 1665 } 1666 if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen)) 1667 err = -EFAULT; 1668 netlink_unlock_table(); 1669 break; 1670 } 1671 case NETLINK_CAP_ACK: 1672 if (len < sizeof(int)) 1673 return -EINVAL; 1674 len = sizeof(int); 1675 val = nlk->flags & NETLINK_F_CAP_ACK ? 1 : 0; 1676 if (put_user(len, optlen) || 1677 put_user(val, optval)) 1678 return -EFAULT; 1679 err = 0; 1680 break; 1681 default: 1682 err = -ENOPROTOOPT; 1683 } 1684 return err; 1685 } 1686 1687 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb) 1688 { 1689 struct nl_pktinfo info; 1690 1691 info.group = NETLINK_CB(skb).dst_group; 1692 put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info); 1693 } 1694 1695 static void netlink_cmsg_listen_all_nsid(struct sock *sk, struct msghdr *msg, 1696 struct sk_buff *skb) 1697 { 1698 if (!NETLINK_CB(skb).nsid_is_set) 1699 return; 1700 1701 put_cmsg(msg, SOL_NETLINK, NETLINK_LISTEN_ALL_NSID, sizeof(int), 1702 &NETLINK_CB(skb).nsid); 1703 } 1704 1705 static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) 1706 { 1707 struct sock *sk = sock->sk; 1708 struct netlink_sock *nlk = nlk_sk(sk); 1709 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name); 1710 u32 dst_portid; 1711 u32 dst_group; 1712 struct sk_buff *skb; 1713 int err; 1714 struct scm_cookie scm; 1715 u32 netlink_skb_flags = 0; 1716 1717 if (msg->msg_flags&MSG_OOB) 1718 return -EOPNOTSUPP; 1719 1720 err = scm_send(sock, msg, &scm, true); 1721 if (err < 0) 1722 return err; 1723 1724 if (msg->msg_namelen) { 1725 err = -EINVAL; 1726 if (addr->nl_family != AF_NETLINK) 1727 goto out; 1728 dst_portid = addr->nl_pid; 1729 dst_group = ffs(addr->nl_groups); 1730 err = -EPERM; 1731 if ((dst_group || dst_portid) && 1732 !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND)) 1733 goto out; 1734 netlink_skb_flags |= NETLINK_SKB_DST; 1735 } else { 1736 dst_portid = nlk->dst_portid; 1737 dst_group = nlk->dst_group; 1738 } 1739 1740 if (!nlk->bound) { 1741 err = netlink_autobind(sock); 1742 if (err) 1743 goto out; 1744 } else { 1745 /* Ensure nlk is hashed and visible. */ 1746 smp_rmb(); 1747 } 1748 1749 err = -EMSGSIZE; 1750 if (len > sk->sk_sndbuf - 32) 1751 goto out; 1752 err = -ENOBUFS; 1753 skb = netlink_alloc_large_skb(len, dst_group); 1754 if (skb == NULL) 1755 goto out; 1756 1757 NETLINK_CB(skb).portid = nlk->portid; 1758 NETLINK_CB(skb).dst_group = dst_group; 1759 NETLINK_CB(skb).creds = scm.creds; 1760 NETLINK_CB(skb).flags = netlink_skb_flags; 1761 1762 err = -EFAULT; 1763 if (memcpy_from_msg(skb_put(skb, len), msg, len)) { 1764 kfree_skb(skb); 1765 goto out; 1766 } 1767 1768 err = security_netlink_send(sk, skb); 1769 if (err) { 1770 kfree_skb(skb); 1771 goto out; 1772 } 1773 1774 if (dst_group) { 1775 atomic_inc(&skb->users); 1776 netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL); 1777 } 1778 err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT); 1779 1780 out: 1781 scm_destroy(&scm); 1782 return err; 1783 } 1784 1785 static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, 1786 int flags) 1787 { 1788 struct scm_cookie scm; 1789 struct sock *sk = sock->sk; 1790 struct netlink_sock *nlk = nlk_sk(sk); 1791 int noblock = flags&MSG_DONTWAIT; 1792 size_t copied; 1793 struct sk_buff *skb, *data_skb; 1794 int err, ret; 1795 1796 if (flags&MSG_OOB) 1797 return -EOPNOTSUPP; 1798 1799 copied = 0; 1800 1801 skb = skb_recv_datagram(sk, flags, noblock, &err); 1802 if (skb == NULL) 1803 goto out; 1804 1805 data_skb = skb; 1806 1807 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES 1808 if (unlikely(skb_shinfo(skb)->frag_list)) { 1809 /* 1810 * If this skb has a frag_list, then here that means that we 1811 * will have to use the frag_list skb's data for compat tasks 1812 * and the regular skb's data for normal (non-compat) tasks. 1813 * 1814 * If we need to send the compat skb, assign it to the 1815 * 'data_skb' variable so that it will be used below for data 1816 * copying. We keep 'skb' for everything else, including 1817 * freeing both later. 1818 */ 1819 if (flags & MSG_CMSG_COMPAT) 1820 data_skb = skb_shinfo(skb)->frag_list; 1821 } 1822 #endif 1823 1824 /* Record the max length of recvmsg() calls for future allocations */ 1825 nlk->max_recvmsg_len = max(nlk->max_recvmsg_len, len); 1826 nlk->max_recvmsg_len = min_t(size_t, nlk->max_recvmsg_len, 1827 16384); 1828 1829 copied = data_skb->len; 1830 if (len < copied) { 1831 msg->msg_flags |= MSG_TRUNC; 1832 copied = len; 1833 } 1834 1835 skb_reset_transport_header(data_skb); 1836 err = skb_copy_datagram_msg(data_skb, 0, msg, copied); 1837 1838 if (msg->msg_name) { 1839 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name); 1840 addr->nl_family = AF_NETLINK; 1841 addr->nl_pad = 0; 1842 addr->nl_pid = NETLINK_CB(skb).portid; 1843 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group); 1844 msg->msg_namelen = sizeof(*addr); 1845 } 1846 1847 if (nlk->flags & NETLINK_F_RECV_PKTINFO) 1848 netlink_cmsg_recv_pktinfo(msg, skb); 1849 if (nlk->flags & NETLINK_F_LISTEN_ALL_NSID) 1850 netlink_cmsg_listen_all_nsid(sk, msg, skb); 1851 1852 memset(&scm, 0, sizeof(scm)); 1853 scm.creds = *NETLINK_CREDS(skb); 1854 if (flags & MSG_TRUNC) 1855 copied = data_skb->len; 1856 1857 skb_free_datagram(sk, skb); 1858 1859 if (nlk->cb_running && 1860 atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) { 1861 ret = netlink_dump(sk); 1862 if (ret) { 1863 sk->sk_err = -ret; 1864 sk->sk_error_report(sk); 1865 } 1866 } 1867 1868 scm_recv(sock, msg, &scm, flags); 1869 out: 1870 netlink_rcv_wake(sk); 1871 return err ? : copied; 1872 } 1873 1874 static void netlink_data_ready(struct sock *sk) 1875 { 1876 BUG(); 1877 } 1878 1879 /* 1880 * We export these functions to other modules. They provide a 1881 * complete set of kernel non-blocking support for message 1882 * queueing. 1883 */ 1884 1885 struct sock * 1886 __netlink_kernel_create(struct net *net, int unit, struct module *module, 1887 struct netlink_kernel_cfg *cfg) 1888 { 1889 struct socket *sock; 1890 struct sock *sk; 1891 struct netlink_sock *nlk; 1892 struct listeners *listeners = NULL; 1893 struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL; 1894 unsigned int groups; 1895 1896 BUG_ON(!nl_table); 1897 1898 if (unit < 0 || unit >= MAX_LINKS) 1899 return NULL; 1900 1901 if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock)) 1902 return NULL; 1903 1904 if (__netlink_create(net, sock, cb_mutex, unit, 1) < 0) 1905 goto out_sock_release_nosk; 1906 1907 sk = sock->sk; 1908 1909 if (!cfg || cfg->groups < 32) 1910 groups = 32; 1911 else 1912 groups = cfg->groups; 1913 1914 listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL); 1915 if (!listeners) 1916 goto out_sock_release; 1917 1918 sk->sk_data_ready = netlink_data_ready; 1919 if (cfg && cfg->input) 1920 nlk_sk(sk)->netlink_rcv = cfg->input; 1921 1922 if (netlink_insert(sk, 0)) 1923 goto out_sock_release; 1924 1925 nlk = nlk_sk(sk); 1926 nlk->flags |= NETLINK_F_KERNEL_SOCKET; 1927 1928 netlink_table_grab(); 1929 if (!nl_table[unit].registered) { 1930 nl_table[unit].groups = groups; 1931 rcu_assign_pointer(nl_table[unit].listeners, listeners); 1932 nl_table[unit].cb_mutex = cb_mutex; 1933 nl_table[unit].module = module; 1934 if (cfg) { 1935 nl_table[unit].bind = cfg->bind; 1936 nl_table[unit].unbind = cfg->unbind; 1937 nl_table[unit].flags = cfg->flags; 1938 if (cfg->compare) 1939 nl_table[unit].compare = cfg->compare; 1940 } 1941 nl_table[unit].registered = 1; 1942 } else { 1943 kfree(listeners); 1944 nl_table[unit].registered++; 1945 } 1946 netlink_table_ungrab(); 1947 return sk; 1948 1949 out_sock_release: 1950 kfree(listeners); 1951 netlink_kernel_release(sk); 1952 return NULL; 1953 1954 out_sock_release_nosk: 1955 sock_release(sock); 1956 return NULL; 1957 } 1958 EXPORT_SYMBOL(__netlink_kernel_create); 1959 1960 void 1961 netlink_kernel_release(struct sock *sk) 1962 { 1963 if (sk == NULL || sk->sk_socket == NULL) 1964 return; 1965 1966 sock_release(sk->sk_socket); 1967 } 1968 EXPORT_SYMBOL(netlink_kernel_release); 1969 1970 int __netlink_change_ngroups(struct sock *sk, unsigned int groups) 1971 { 1972 struct listeners *new, *old; 1973 struct netlink_table *tbl = &nl_table[sk->sk_protocol]; 1974 1975 if (groups < 32) 1976 groups = 32; 1977 1978 if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) { 1979 new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC); 1980 if (!new) 1981 return -ENOMEM; 1982 old = nl_deref_protected(tbl->listeners); 1983 memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups)); 1984 rcu_assign_pointer(tbl->listeners, new); 1985 1986 kfree_rcu(old, rcu); 1987 } 1988 tbl->groups = groups; 1989 1990 return 0; 1991 } 1992 1993 /** 1994 * netlink_change_ngroups - change number of multicast groups 1995 * 1996 * This changes the number of multicast groups that are available 1997 * on a certain netlink family. Note that it is not possible to 1998 * change the number of groups to below 32. Also note that it does 1999 * not implicitly call netlink_clear_multicast_users() when the 2000 * number of groups is reduced. 2001 * 2002 * @sk: The kernel netlink socket, as returned by netlink_kernel_create(). 2003 * @groups: The new number of groups. 2004 */ 2005 int netlink_change_ngroups(struct sock *sk, unsigned int groups) 2006 { 2007 int err; 2008 2009 netlink_table_grab(); 2010 err = __netlink_change_ngroups(sk, groups); 2011 netlink_table_ungrab(); 2012 2013 return err; 2014 } 2015 2016 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group) 2017 { 2018 struct sock *sk; 2019 struct netlink_table *tbl = &nl_table[ksk->sk_protocol]; 2020 2021 sk_for_each_bound(sk, &tbl->mc_list) 2022 netlink_update_socket_mc(nlk_sk(sk), group, 0); 2023 } 2024 2025 struct nlmsghdr * 2026 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags) 2027 { 2028 struct nlmsghdr *nlh; 2029 int size = nlmsg_msg_size(len); 2030 2031 nlh = (struct nlmsghdr *)skb_put(skb, NLMSG_ALIGN(size)); 2032 nlh->nlmsg_type = type; 2033 nlh->nlmsg_len = size; 2034 nlh->nlmsg_flags = flags; 2035 nlh->nlmsg_pid = portid; 2036 nlh->nlmsg_seq = seq; 2037 if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0) 2038 memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size); 2039 return nlh; 2040 } 2041 EXPORT_SYMBOL(__nlmsg_put); 2042 2043 /* 2044 * It looks a bit ugly. 2045 * It would be better to create kernel thread. 2046 */ 2047 2048 static int netlink_dump(struct sock *sk) 2049 { 2050 struct netlink_sock *nlk = nlk_sk(sk); 2051 struct netlink_callback *cb; 2052 struct sk_buff *skb = NULL; 2053 struct nlmsghdr *nlh; 2054 int len, err = -ENOBUFS; 2055 int alloc_min_size; 2056 int alloc_size; 2057 2058 mutex_lock(nlk->cb_mutex); 2059 if (!nlk->cb_running) { 2060 err = -EINVAL; 2061 goto errout_skb; 2062 } 2063 2064 if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf) 2065 goto errout_skb; 2066 2067 /* NLMSG_GOODSIZE is small to avoid high order allocations being 2068 * required, but it makes sense to _attempt_ a 16K bytes allocation 2069 * to reduce number of system calls on dump operations, if user 2070 * ever provided a big enough buffer. 2071 */ 2072 cb = &nlk->cb; 2073 alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE); 2074 2075 if (alloc_min_size < nlk->max_recvmsg_len) { 2076 alloc_size = nlk->max_recvmsg_len; 2077 skb = alloc_skb(alloc_size, GFP_KERNEL | 2078 __GFP_NOWARN | __GFP_NORETRY); 2079 } 2080 if (!skb) { 2081 alloc_size = alloc_min_size; 2082 skb = alloc_skb(alloc_size, GFP_KERNEL); 2083 } 2084 if (!skb) 2085 goto errout_skb; 2086 2087 /* Trim skb to allocated size. User is expected to provide buffer as 2088 * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at 2089 * netlink_recvmsg())). dump will pack as many smaller messages as 2090 * could fit within the allocated skb. skb is typically allocated 2091 * with larger space than required (could be as much as near 2x the 2092 * requested size with align to next power of 2 approach). Allowing 2093 * dump to use the excess space makes it difficult for a user to have a 2094 * reasonable static buffer based on the expected largest dump of a 2095 * single netdev. The outcome is MSG_TRUNC error. 2096 */ 2097 skb_reserve(skb, skb_tailroom(skb) - alloc_size); 2098 netlink_skb_set_owner_r(skb, sk); 2099 2100 len = cb->dump(skb, cb); 2101 2102 if (len > 0) { 2103 mutex_unlock(nlk->cb_mutex); 2104 2105 if (sk_filter(sk, skb)) 2106 kfree_skb(skb); 2107 else 2108 __netlink_sendskb(sk, skb); 2109 return 0; 2110 } 2111 2112 nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI); 2113 if (!nlh) 2114 goto errout_skb; 2115 2116 nl_dump_check_consistent(cb, nlh); 2117 2118 memcpy(nlmsg_data(nlh), &len, sizeof(len)); 2119 2120 if (sk_filter(sk, skb)) 2121 kfree_skb(skb); 2122 else 2123 __netlink_sendskb(sk, skb); 2124 2125 if (cb->done) 2126 cb->done(cb); 2127 2128 nlk->cb_running = false; 2129 mutex_unlock(nlk->cb_mutex); 2130 module_put(cb->module); 2131 consume_skb(cb->skb); 2132 return 0; 2133 2134 errout_skb: 2135 mutex_unlock(nlk->cb_mutex); 2136 kfree_skb(skb); 2137 return err; 2138 } 2139 2140 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, 2141 const struct nlmsghdr *nlh, 2142 struct netlink_dump_control *control) 2143 { 2144 struct netlink_callback *cb; 2145 struct sock *sk; 2146 struct netlink_sock *nlk; 2147 int ret; 2148 2149 atomic_inc(&skb->users); 2150 2151 sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid); 2152 if (sk == NULL) { 2153 ret = -ECONNREFUSED; 2154 goto error_free; 2155 } 2156 2157 nlk = nlk_sk(sk); 2158 mutex_lock(nlk->cb_mutex); 2159 /* A dump is in progress... */ 2160 if (nlk->cb_running) { 2161 ret = -EBUSY; 2162 goto error_unlock; 2163 } 2164 /* add reference of module which cb->dump belongs to */ 2165 if (!try_module_get(control->module)) { 2166 ret = -EPROTONOSUPPORT; 2167 goto error_unlock; 2168 } 2169 2170 cb = &nlk->cb; 2171 memset(cb, 0, sizeof(*cb)); 2172 cb->start = control->start; 2173 cb->dump = control->dump; 2174 cb->done = control->done; 2175 cb->nlh = nlh; 2176 cb->data = control->data; 2177 cb->module = control->module; 2178 cb->min_dump_alloc = control->min_dump_alloc; 2179 cb->skb = skb; 2180 2181 nlk->cb_running = true; 2182 2183 mutex_unlock(nlk->cb_mutex); 2184 2185 if (cb->start) 2186 cb->start(cb); 2187 2188 ret = netlink_dump(sk); 2189 sock_put(sk); 2190 2191 if (ret) 2192 return ret; 2193 2194 /* We successfully started a dump, by returning -EINTR we 2195 * signal not to send ACK even if it was requested. 2196 */ 2197 return -EINTR; 2198 2199 error_unlock: 2200 sock_put(sk); 2201 mutex_unlock(nlk->cb_mutex); 2202 error_free: 2203 kfree_skb(skb); 2204 return ret; 2205 } 2206 EXPORT_SYMBOL(__netlink_dump_start); 2207 2208 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err) 2209 { 2210 struct sk_buff *skb; 2211 struct nlmsghdr *rep; 2212 struct nlmsgerr *errmsg; 2213 size_t payload = sizeof(*errmsg); 2214 struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk); 2215 2216 /* Error messages get the original request appened, unless the user 2217 * requests to cap the error message. 2218 */ 2219 if (!(nlk->flags & NETLINK_F_CAP_ACK) && err) 2220 payload += nlmsg_len(nlh); 2221 2222 skb = nlmsg_new(payload, GFP_KERNEL); 2223 if (!skb) { 2224 struct sock *sk; 2225 2226 sk = netlink_lookup(sock_net(in_skb->sk), 2227 in_skb->sk->sk_protocol, 2228 NETLINK_CB(in_skb).portid); 2229 if (sk) { 2230 sk->sk_err = ENOBUFS; 2231 sk->sk_error_report(sk); 2232 sock_put(sk); 2233 } 2234 return; 2235 } 2236 2237 rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq, 2238 NLMSG_ERROR, payload, 0); 2239 errmsg = nlmsg_data(rep); 2240 errmsg->error = err; 2241 memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh)); 2242 netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT); 2243 } 2244 EXPORT_SYMBOL(netlink_ack); 2245 2246 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *, 2247 struct nlmsghdr *)) 2248 { 2249 struct nlmsghdr *nlh; 2250 int err; 2251 2252 while (skb->len >= nlmsg_total_size(0)) { 2253 int msglen; 2254 2255 nlh = nlmsg_hdr(skb); 2256 err = 0; 2257 2258 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len) 2259 return 0; 2260 2261 /* Only requests are handled by the kernel */ 2262 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) 2263 goto ack; 2264 2265 /* Skip control messages */ 2266 if (nlh->nlmsg_type < NLMSG_MIN_TYPE) 2267 goto ack; 2268 2269 err = cb(skb, nlh); 2270 if (err == -EINTR) 2271 goto skip; 2272 2273 ack: 2274 if (nlh->nlmsg_flags & NLM_F_ACK || err) 2275 netlink_ack(skb, nlh, err); 2276 2277 skip: 2278 msglen = NLMSG_ALIGN(nlh->nlmsg_len); 2279 if (msglen > skb->len) 2280 msglen = skb->len; 2281 skb_pull(skb, msglen); 2282 } 2283 2284 return 0; 2285 } 2286 EXPORT_SYMBOL(netlink_rcv_skb); 2287 2288 /** 2289 * nlmsg_notify - send a notification netlink message 2290 * @sk: netlink socket to use 2291 * @skb: notification message 2292 * @portid: destination netlink portid for reports or 0 2293 * @group: destination multicast group or 0 2294 * @report: 1 to report back, 0 to disable 2295 * @flags: allocation flags 2296 */ 2297 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid, 2298 unsigned int group, int report, gfp_t flags) 2299 { 2300 int err = 0; 2301 2302 if (group) { 2303 int exclude_portid = 0; 2304 2305 if (report) { 2306 atomic_inc(&skb->users); 2307 exclude_portid = portid; 2308 } 2309 2310 /* errors reported via destination sk->sk_err, but propagate 2311 * delivery errors if NETLINK_BROADCAST_ERROR flag is set */ 2312 err = nlmsg_multicast(sk, skb, exclude_portid, group, flags); 2313 } 2314 2315 if (report) { 2316 int err2; 2317 2318 err2 = nlmsg_unicast(sk, skb, portid); 2319 if (!err || err == -ESRCH) 2320 err = err2; 2321 } 2322 2323 return err; 2324 } 2325 EXPORT_SYMBOL(nlmsg_notify); 2326 2327 #ifdef CONFIG_PROC_FS 2328 struct nl_seq_iter { 2329 struct seq_net_private p; 2330 struct rhashtable_iter hti; 2331 int link; 2332 }; 2333 2334 static int netlink_walk_start(struct nl_seq_iter *iter) 2335 { 2336 int err; 2337 2338 err = rhashtable_walk_init(&nl_table[iter->link].hash, &iter->hti); 2339 if (err) { 2340 iter->link = MAX_LINKS; 2341 return err; 2342 } 2343 2344 err = rhashtable_walk_start(&iter->hti); 2345 return err == -EAGAIN ? 0 : err; 2346 } 2347 2348 static void netlink_walk_stop(struct nl_seq_iter *iter) 2349 { 2350 rhashtable_walk_stop(&iter->hti); 2351 rhashtable_walk_exit(&iter->hti); 2352 } 2353 2354 static void *__netlink_seq_next(struct seq_file *seq) 2355 { 2356 struct nl_seq_iter *iter = seq->private; 2357 struct netlink_sock *nlk; 2358 2359 do { 2360 for (;;) { 2361 int err; 2362 2363 nlk = rhashtable_walk_next(&iter->hti); 2364 2365 if (IS_ERR(nlk)) { 2366 if (PTR_ERR(nlk) == -EAGAIN) 2367 continue; 2368 2369 return nlk; 2370 } 2371 2372 if (nlk) 2373 break; 2374 2375 netlink_walk_stop(iter); 2376 if (++iter->link >= MAX_LINKS) 2377 return NULL; 2378 2379 err = netlink_walk_start(iter); 2380 if (err) 2381 return ERR_PTR(err); 2382 } 2383 } while (sock_net(&nlk->sk) != seq_file_net(seq)); 2384 2385 return nlk; 2386 } 2387 2388 static void *netlink_seq_start(struct seq_file *seq, loff_t *posp) 2389 { 2390 struct nl_seq_iter *iter = seq->private; 2391 void *obj = SEQ_START_TOKEN; 2392 loff_t pos; 2393 int err; 2394 2395 iter->link = 0; 2396 2397 err = netlink_walk_start(iter); 2398 if (err) 2399 return ERR_PTR(err); 2400 2401 for (pos = *posp; pos && obj && !IS_ERR(obj); pos--) 2402 obj = __netlink_seq_next(seq); 2403 2404 return obj; 2405 } 2406 2407 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) 2408 { 2409 ++*pos; 2410 return __netlink_seq_next(seq); 2411 } 2412 2413 static void netlink_seq_stop(struct seq_file *seq, void *v) 2414 { 2415 struct nl_seq_iter *iter = seq->private; 2416 2417 if (iter->link >= MAX_LINKS) 2418 return; 2419 2420 netlink_walk_stop(iter); 2421 } 2422 2423 2424 static int netlink_seq_show(struct seq_file *seq, void *v) 2425 { 2426 if (v == SEQ_START_TOKEN) { 2427 seq_puts(seq, 2428 "sk Eth Pid Groups " 2429 "Rmem Wmem Dump Locks Drops Inode\n"); 2430 } else { 2431 struct sock *s = v; 2432 struct netlink_sock *nlk = nlk_sk(s); 2433 2434 seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %d %-8d %-8d %-8lu\n", 2435 s, 2436 s->sk_protocol, 2437 nlk->portid, 2438 nlk->groups ? (u32)nlk->groups[0] : 0, 2439 sk_rmem_alloc_get(s), 2440 sk_wmem_alloc_get(s), 2441 nlk->cb_running, 2442 atomic_read(&s->sk_refcnt), 2443 atomic_read(&s->sk_drops), 2444 sock_i_ino(s) 2445 ); 2446 2447 } 2448 return 0; 2449 } 2450 2451 static const struct seq_operations netlink_seq_ops = { 2452 .start = netlink_seq_start, 2453 .next = netlink_seq_next, 2454 .stop = netlink_seq_stop, 2455 .show = netlink_seq_show, 2456 }; 2457 2458 2459 static int netlink_seq_open(struct inode *inode, struct file *file) 2460 { 2461 return seq_open_net(inode, file, &netlink_seq_ops, 2462 sizeof(struct nl_seq_iter)); 2463 } 2464 2465 static const struct file_operations netlink_seq_fops = { 2466 .owner = THIS_MODULE, 2467 .open = netlink_seq_open, 2468 .read = seq_read, 2469 .llseek = seq_lseek, 2470 .release = seq_release_net, 2471 }; 2472 2473 #endif 2474 2475 int netlink_register_notifier(struct notifier_block *nb) 2476 { 2477 return atomic_notifier_chain_register(&netlink_chain, nb); 2478 } 2479 EXPORT_SYMBOL(netlink_register_notifier); 2480 2481 int netlink_unregister_notifier(struct notifier_block *nb) 2482 { 2483 return atomic_notifier_chain_unregister(&netlink_chain, nb); 2484 } 2485 EXPORT_SYMBOL(netlink_unregister_notifier); 2486 2487 static const struct proto_ops netlink_ops = { 2488 .family = PF_NETLINK, 2489 .owner = THIS_MODULE, 2490 .release = netlink_release, 2491 .bind = netlink_bind, 2492 .connect = netlink_connect, 2493 .socketpair = sock_no_socketpair, 2494 .accept = sock_no_accept, 2495 .getname = netlink_getname, 2496 .poll = datagram_poll, 2497 .ioctl = sock_no_ioctl, 2498 .listen = sock_no_listen, 2499 .shutdown = sock_no_shutdown, 2500 .setsockopt = netlink_setsockopt, 2501 .getsockopt = netlink_getsockopt, 2502 .sendmsg = netlink_sendmsg, 2503 .recvmsg = netlink_recvmsg, 2504 .mmap = sock_no_mmap, 2505 .sendpage = sock_no_sendpage, 2506 }; 2507 2508 static const struct net_proto_family netlink_family_ops = { 2509 .family = PF_NETLINK, 2510 .create = netlink_create, 2511 .owner = THIS_MODULE, /* for consistency 8) */ 2512 }; 2513 2514 static int __net_init netlink_net_init(struct net *net) 2515 { 2516 #ifdef CONFIG_PROC_FS 2517 if (!proc_create("netlink", 0, net->proc_net, &netlink_seq_fops)) 2518 return -ENOMEM; 2519 #endif 2520 return 0; 2521 } 2522 2523 static void __net_exit netlink_net_exit(struct net *net) 2524 { 2525 #ifdef CONFIG_PROC_FS 2526 remove_proc_entry("netlink", net->proc_net); 2527 #endif 2528 } 2529 2530 static void __init netlink_add_usersock_entry(void) 2531 { 2532 struct listeners *listeners; 2533 int groups = 32; 2534 2535 listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL); 2536 if (!listeners) 2537 panic("netlink_add_usersock_entry: Cannot allocate listeners\n"); 2538 2539 netlink_table_grab(); 2540 2541 nl_table[NETLINK_USERSOCK].groups = groups; 2542 rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners); 2543 nl_table[NETLINK_USERSOCK].module = THIS_MODULE; 2544 nl_table[NETLINK_USERSOCK].registered = 1; 2545 nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND; 2546 2547 netlink_table_ungrab(); 2548 } 2549 2550 static struct pernet_operations __net_initdata netlink_net_ops = { 2551 .init = netlink_net_init, 2552 .exit = netlink_net_exit, 2553 }; 2554 2555 static inline u32 netlink_hash(const void *data, u32 len, u32 seed) 2556 { 2557 const struct netlink_sock *nlk = data; 2558 struct netlink_compare_arg arg; 2559 2560 netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid); 2561 return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed); 2562 } 2563 2564 static const struct rhashtable_params netlink_rhashtable_params = { 2565 .head_offset = offsetof(struct netlink_sock, node), 2566 .key_len = netlink_compare_arg_len, 2567 .obj_hashfn = netlink_hash, 2568 .obj_cmpfn = netlink_compare, 2569 .automatic_shrinking = true, 2570 }; 2571 2572 static int __init netlink_proto_init(void) 2573 { 2574 int i; 2575 int err = proto_register(&netlink_proto, 0); 2576 2577 if (err != 0) 2578 goto out; 2579 2580 BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb)); 2581 2582 nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL); 2583 if (!nl_table) 2584 goto panic; 2585 2586 for (i = 0; i < MAX_LINKS; i++) { 2587 if (rhashtable_init(&nl_table[i].hash, 2588 &netlink_rhashtable_params) < 0) { 2589 while (--i > 0) 2590 rhashtable_destroy(&nl_table[i].hash); 2591 kfree(nl_table); 2592 goto panic; 2593 } 2594 } 2595 2596 INIT_LIST_HEAD(&netlink_tap_all); 2597 2598 netlink_add_usersock_entry(); 2599 2600 sock_register(&netlink_family_ops); 2601 register_pernet_subsys(&netlink_net_ops); 2602 /* The netlink device handler may be needed early. */ 2603 rtnetlink_init(); 2604 out: 2605 return err; 2606 panic: 2607 panic("netlink_init: Cannot allocate nl_table\n"); 2608 } 2609 2610 core_initcall(netlink_proto_init); 2611