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