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
  86struct listeners {
  87        struct rcu_head         rcu;
  88        unsigned long           masks[0];
  89};
  90
  91#define NETLINK_KERNEL_SOCKET   0x1
  92#define NETLINK_RECV_PKTINFO    0x2
  93#define NETLINK_BROADCAST_SEND_ERROR    0x4
  94#define NETLINK_RECV_NO_ENOBUFS 0x8
  95
  96static inline struct netlink_sock *nlk_sk(struct sock *sk)
  97{
  98        return container_of(sk, struct netlink_sock, sk);
  99}
 100
 101static inline int netlink_is_kernel(struct sock *sk)
 102{
 103        return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET;
 104}
 105
 106struct nl_pid_hash {
 107        struct hlist_head *table;
 108        unsigned long rehash_time;
 109
 110        unsigned int mask;
 111        unsigned int shift;
 112
 113        unsigned int entries;
 114        unsigned int max_shift;
 115
 116        u32 rnd;
 117};
 118
 119struct netlink_table {
 120        struct nl_pid_hash hash;
 121        struct hlist_head mc_list;
 122        struct listeners __rcu *listeners;
 123        unsigned int nl_nonroot;
 124        unsigned int groups;
 125        struct mutex *cb_mutex;
 126        struct module *module;
 127        int registered;
 128};
 129
 130static struct netlink_table *nl_table;
 131
 132static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 133
 134static int netlink_dump(struct sock *sk);
 135static void netlink_destroy_callback(struct netlink_callback *cb);
 136
 137static DEFINE_RWLOCK(nl_table_lock);
 138static atomic_t nl_table_users = ATOMIC_INIT(0);
 139
 140static ATOMIC_NOTIFIER_HEAD(netlink_chain);
 141
 142static inline u32 netlink_group_mask(u32 group)
 143{
 144        return group ? 1 << (group - 1) : 0;
 145}
 146
 147static inline struct hlist_head *nl_pid_hashfn(struct nl_pid_hash *hash, u32 pid)
 148{
 149        return &hash->table[jhash_1word(pid, hash->rnd) & hash->mask];
 150}
 151
 152static void netlink_sock_destruct(struct sock *sk)
 153{
 154        struct netlink_sock *nlk = nlk_sk(sk);
 155
 156        if (nlk->cb) {
 157                if (nlk->cb->done)
 158                        nlk->cb->done(nlk->cb);
 159                netlink_destroy_callback(nlk->cb);
 160        }
 161
 162        skb_queue_purge(&sk->sk_receive_queue);
 163
 164        if (!sock_flag(sk, SOCK_DEAD)) {
 165                printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
 166                return;
 167        }
 168
 169        WARN_ON(atomic_read(&sk->sk_rmem_alloc));
 170        WARN_ON(atomic_read(&sk->sk_wmem_alloc));
 171        WARN_ON(nlk_sk(sk)->groups);
 172}
 173
 174/* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
 175 * SMP. Look, when several writers sleep and reader wakes them up, all but one
 176 * immediately hit write lock and grab all the cpus. Exclusive sleep solves
 177 * this, _but_ remember, it adds useless work on UP machines.
 178 */
 179
 180void netlink_table_grab(void)
 181        __acquires(nl_table_lock)
 182{
 183        might_sleep();
 184
 185        write_lock_irq(&nl_table_lock);
 186
 187        if (atomic_read(&nl_table_users)) {
 188                DECLARE_WAITQUEUE(wait, current);
 189
 190                add_wait_queue_exclusive(&nl_table_wait, &wait);
 191                for (;;) {
 192                        set_current_state(TASK_UNINTERRUPTIBLE);
 193                        if (atomic_read(&nl_table_users) == 0)
 194                                break;
 195                        write_unlock_irq(&nl_table_lock);
 196                        schedule();
 197                        write_lock_irq(&nl_table_lock);
 198                }
 199
 200                __set_current_state(TASK_RUNNING);
 201                remove_wait_queue(&nl_table_wait, &wait);
 202        }
 203}
 204
 205void netlink_table_ungrab(void)
 206        __releases(nl_table_lock)
 207{
 208        write_unlock_irq(&nl_table_lock);
 209        wake_up(&nl_table_wait);
 210}
 211
 212static inline void
 213netlink_lock_table(void)
 214{
 215        /* read_lock() synchronizes us to netlink_table_grab */
 216
 217        read_lock(&nl_table_lock);
 218        atomic_inc(&nl_table_users);
 219        read_unlock(&nl_table_lock);
 220}
 221
 222static inline void
 223netlink_unlock_table(void)
 224{
 225        if (atomic_dec_and_test(&nl_table_users))
 226                wake_up(&nl_table_wait);
 227}
 228
 229static struct sock *netlink_lookup(struct net *net, int protocol, u32 pid)
 230{
 231        struct nl_pid_hash *hash = &nl_table[protocol].hash;
 232        struct hlist_head *head;
 233        struct sock *sk;
 234        struct hlist_node *node;
 235
 236        read_lock(&nl_table_lock);
 237        head = nl_pid_hashfn(hash, pid);
 238        sk_for_each(sk, node, head) {
 239                if (net_eq(sock_net(sk), net) && (nlk_sk(sk)->pid == pid)) {
 240                        sock_hold(sk);
 241                        goto found;
 242                }
 243        }
 244        sk = NULL;
 245found:
 246        read_unlock(&nl_table_lock);
 247        return sk;
 248}
 249
 250static struct hlist_head *nl_pid_hash_zalloc(size_t size)
 251{
 252        if (size <= PAGE_SIZE)
 253                return kzalloc(size, GFP_ATOMIC);
 254        else
 255                return (struct hlist_head *)
 256                        __get_free_pages(GFP_ATOMIC | __GFP_ZERO,
 257                                         get_order(size));
 258}
 259
 260static void nl_pid_hash_free(struct hlist_head *table, size_t size)
 261{
 262        if (size <= PAGE_SIZE)
 263                kfree(table);
 264        else
 265                free_pages((unsigned long)table, get_order(size));
 266}
 267
 268static int nl_pid_hash_rehash(struct nl_pid_hash *hash, int grow)
 269{
 270        unsigned int omask, mask, shift;
 271        size_t osize, size;
 272        struct hlist_head *otable, *table;
 273        int i;
 274
 275        omask = mask = hash->mask;
 276        osize = size = (mask + 1) * sizeof(*table);
 277        shift = hash->shift;
 278
 279        if (grow) {
 280                if (++shift > hash->max_shift)
 281                        return 0;
 282                mask = mask * 2 + 1;
 283                size *= 2;
 284        }
 285
 286        table = nl_pid_hash_zalloc(size);
 287        if (!table)
 288                return 0;
 289
 290        otable = hash->table;
 291        hash->table = table;
 292        hash->mask = mask;
 293        hash->shift = shift;
 294        get_random_bytes(&hash->rnd, sizeof(hash->rnd));
 295
 296        for (i = 0; i <= omask; i++) {
 297                struct sock *sk;
 298                struct hlist_node *node, *tmp;
 299
 300                sk_for_each_safe(sk, node, tmp, &otable[i])
 301                        __sk_add_node(sk, nl_pid_hashfn(hash, nlk_sk(sk)->pid));
 302        }
 303
 304        nl_pid_hash_free(otable, osize);
 305        hash->rehash_time = jiffies + 10 * 60 * HZ;
 306        return 1;
 307}
 308
 309static inline int nl_pid_hash_dilute(struct nl_pid_hash *hash, int len)
 310{
 311        int avg = hash->entries >> hash->shift;
 312
 313        if (unlikely(avg > 1) && nl_pid_hash_rehash(hash, 1))
 314                return 1;
 315
 316        if (unlikely(len > avg) && time_after(jiffies, hash->rehash_time)) {
 317                nl_pid_hash_rehash(hash, 0);
 318                return 1;
 319        }
 320
 321        return 0;
 322}
 323
 324static const struct proto_ops netlink_ops;
 325
 326static void
 327netlink_update_listeners(struct sock *sk)
 328{
 329        struct netlink_table *tbl = &nl_table[sk->sk_protocol];
 330        struct hlist_node *node;
 331        unsigned long mask;
 332        unsigned int i;
 333
 334        for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
 335                mask = 0;
 336                sk_for_each_bound(sk, node, &tbl->mc_list) {
 337                        if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
 338                                mask |= nlk_sk(sk)->groups[i];
 339                }
 340                tbl->listeners->masks[i] = mask;
 341        }
 342        /* this function is only called with the netlink table "grabbed", which
 343         * makes sure updates are visible before bind or setsockopt return. */
 344}
 345
 346static int netlink_insert(struct sock *sk, struct net *net, u32 pid)
 347{
 348        struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash;
 349        struct hlist_head *head;
 350        int err = -EADDRINUSE;
 351        struct sock *osk;
 352        struct hlist_node *node;
 353        int len;
 354
 355        netlink_table_grab();
 356        head = nl_pid_hashfn(hash, pid);
 357        len = 0;
 358        sk_for_each(osk, node, head) {
 359                if (net_eq(sock_net(osk), net) && (nlk_sk(osk)->pid == pid))
 360                        break;
 361                len++;
 362        }
 363        if (node)
 364                goto err;
 365
 366        err = -EBUSY;
 367        if (nlk_sk(sk)->pid)
 368                goto err;
 369
 370        err = -ENOMEM;
 371        if (BITS_PER_LONG > 32 && unlikely(hash->entries >= UINT_MAX))
 372                goto err;
 373
 374        if (len && nl_pid_hash_dilute(hash, len))
 375                head = nl_pid_hashfn(hash, pid);
 376        hash->entries++;
 377        nlk_sk(sk)->pid = pid;
 378        sk_add_node(sk, head);
 379        err = 0;
 380
 381err:
 382        netlink_table_ungrab();
 383        return err;
 384}
 385
 386static void netlink_remove(struct sock *sk)
 387{
 388        netlink_table_grab();
 389        if (sk_del_node_init(sk))
 390                nl_table[sk->sk_protocol].hash.entries--;
 391        if (nlk_sk(sk)->subscriptions)
 392                __sk_del_bind_node(sk);
 393        netlink_table_ungrab();
 394}
 395
 396static struct proto netlink_proto = {
 397        .name     = "NETLINK",
 398        .owner    = THIS_MODULE,
 399        .obj_size = sizeof(struct netlink_sock),
 400};
 401
 402static int __netlink_create(struct net *net, struct socket *sock,
 403                            struct mutex *cb_mutex, int protocol)
 404{
 405        struct sock *sk;
 406        struct netlink_sock *nlk;
 407
 408        sock->ops = &netlink_ops;
 409
 410        sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto);
 411        if (!sk)
 412                return -ENOMEM;
 413
 414        sock_init_data(sock, sk);
 415
 416        nlk = nlk_sk(sk);
 417        if (cb_mutex)
 418                nlk->cb_mutex = cb_mutex;
 419        else {
 420                nlk->cb_mutex = &nlk->cb_def_mutex;
 421                mutex_init(nlk->cb_mutex);
 422        }
 423        init_waitqueue_head(&nlk->wait);
 424
 425        sk->sk_destruct = netlink_sock_destruct;
 426        sk->sk_protocol = protocol;
 427        return 0;
 428}
 429
 430static int netlink_create(struct net *net, struct socket *sock, int protocol,
 431                          int kern)
 432{
 433        struct module *module = NULL;
 434        struct mutex *cb_mutex;
 435        struct netlink_sock *nlk;
 436        int err = 0;
 437
 438        sock->state = SS_UNCONNECTED;
 439
 440        if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
 441                return -ESOCKTNOSUPPORT;
 442
 443        if (protocol < 0 || protocol >= MAX_LINKS)
 444                return -EPROTONOSUPPORT;
 445
 446        netlink_lock_table();
 447#ifdef CONFIG_MODULES
 448        if (!nl_table[protocol].registered) {
 449                netlink_unlock_table();
 450                request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
 451                netlink_lock_table();
 452        }
 453#endif
 454        if (nl_table[protocol].registered &&
 455            try_module_get(nl_table[protocol].module))
 456                module = nl_table[protocol].module;
 457        else
 458                err = -EPROTONOSUPPORT;
 459        cb_mutex = nl_table[protocol].cb_mutex;
 460        netlink_unlock_table();
 461
 462        if (err < 0)
 463                goto out;
 464
 465        err = __netlink_create(net, sock, cb_mutex, protocol);
 466        if (err < 0)
 467                goto out_module;
 468
 469        local_bh_disable();
 470        sock_prot_inuse_add(net, &netlink_proto, 1);
 471        local_bh_enable();
 472
 473        nlk = nlk_sk(sock->sk);
 474        nlk->module = module;
 475out:
 476        return err;
 477
 478out_module:
 479        module_put(module);
 480        goto out;
 481}
 482
 483static int netlink_release(struct socket *sock)
 484{
 485        struct sock *sk = sock->sk;
 486        struct netlink_sock *nlk;
 487
 488        if (!sk)
 489                return 0;
 490
 491        netlink_remove(sk);
 492        sock_orphan(sk);
 493        nlk = nlk_sk(sk);
 494
 495        /*
 496         * OK. Socket is unlinked, any packets that arrive now
 497         * will be purged.
 498         */
 499
 500        sock->sk = NULL;
 501        wake_up_interruptible_all(&nlk->wait);
 502
 503        skb_queue_purge(&sk->sk_write_queue);
 504
 505        if (nlk->pid) {
 506                struct netlink_notify n = {
 507                                                .net = sock_net(sk),
 508                                                .protocol = sk->sk_protocol,
 509                                                .pid = nlk->pid,
 510                                          };
 511                atomic_notifier_call_chain(&netlink_chain,
 512                                NETLINK_URELEASE, &n);
 513        }
 514
 515        module_put(nlk->module);
 516
 517        netlink_table_grab();
 518        if (netlink_is_kernel(sk)) {
 519                BUG_ON(nl_table[sk->sk_protocol].registered == 0);
 520                if (--nl_table[sk->sk_protocol].registered == 0) {
 521                        kfree(nl_table[sk->sk_protocol].listeners);
 522                        nl_table[sk->sk_protocol].module = NULL;
 523                        nl_table[sk->sk_protocol].registered = 0;
 524                }
 525        } else if (nlk->subscriptions)
 526                netlink_update_listeners(sk);
 527        netlink_table_ungrab();
 528
 529        kfree(nlk->groups);
 530        nlk->groups = NULL;
 531
 532        local_bh_disable();
 533        sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
 534        local_bh_enable();
 535        sock_put(sk);
 536        return 0;
 537}
 538
 539static int netlink_autobind(struct socket *sock)
 540{
 541        struct sock *sk = sock->sk;
 542        struct net *net = sock_net(sk);
 543        struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash;
 544        struct hlist_head *head;
 545        struct sock *osk;
 546        struct hlist_node *node;
 547        s32 pid = task_tgid_vnr(current);
 548        int err;
 549        static s32 rover = -4097;
 550
 551retry:
 552        cond_resched();
 553        netlink_table_grab();
 554        head = nl_pid_hashfn(hash, pid);
 555        sk_for_each(osk, node, head) {
 556                if (!net_eq(sock_net(osk), net))
 557                        continue;
 558                if (nlk_sk(osk)->pid == pid) {
 559                        /* Bind collision, search negative pid values. */
 560                        pid = rover--;
 561                        if (rover > -4097)
 562                                rover = -4097;
 563                        netlink_table_ungrab();
 564                        goto retry;
 565                }
 566        }
 567        netlink_table_ungrab();
 568
 569        err = netlink_insert(sk, net, pid);
 570        if (err == -EADDRINUSE)
 571                goto retry;
 572
 573        /* If 2 threads race to autobind, that is fine.  */
 574        if (err == -EBUSY)
 575                err = 0;
 576
 577        return err;
 578}
 579
 580static inline int netlink_capable(const struct socket *sock, unsigned int flag)
 581{
 582        return (nl_table[sock->sk->sk_protocol].nl_nonroot & flag) ||
 583               capable(CAP_NET_ADMIN);
 584}
 585
 586static void
 587netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
 588{
 589        struct netlink_sock *nlk = nlk_sk(sk);
 590
 591        if (nlk->subscriptions && !subscriptions)
 592                __sk_del_bind_node(sk);
 593        else if (!nlk->subscriptions && subscriptions)
 594                sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
 595        nlk->subscriptions = subscriptions;
 596}
 597
 598static int netlink_realloc_groups(struct sock *sk)
 599{
 600        struct netlink_sock *nlk = nlk_sk(sk);
 601        unsigned int groups;
 602        unsigned long *new_groups;
 603        int err = 0;
 604
 605        netlink_table_grab();
 606
 607        groups = nl_table[sk->sk_protocol].groups;
 608        if (!nl_table[sk->sk_protocol].registered) {
 609                err = -ENOENT;
 610                goto out_unlock;
 611        }
 612
 613        if (nlk->ngroups >= groups)
 614                goto out_unlock;
 615
 616        new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
 617        if (new_groups == NULL) {
 618                err = -ENOMEM;
 619                goto out_unlock;
 620        }
 621        memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
 622               NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
 623
 624        nlk->groups = new_groups;
 625        nlk->ngroups = groups;
 626 out_unlock:
 627        netlink_table_ungrab();
 628        return err;
 629}
 630
 631static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 632                        int addr_len)
 633{
 634        struct sock *sk = sock->sk;
 635        struct net *net = sock_net(sk);
 636        struct netlink_sock *nlk = nlk_sk(sk);
 637        struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
 638        int err;
 639
 640        if (nladdr->nl_family != AF_NETLINK)
 641                return -EINVAL;
 642
 643        /* Only superuser is allowed to listen multicasts */
 644        if (nladdr->nl_groups) {
 645                if (!netlink_capable(sock, NL_NONROOT_RECV))
 646                        return -EPERM;
 647                err = netlink_realloc_groups(sk);
 648                if (err)
 649                        return err;
 650        }
 651
 652        if (nlk->pid) {
 653                if (nladdr->nl_pid != nlk->pid)
 654                        return -EINVAL;
 655        } else {
 656                err = nladdr->nl_pid ?
 657                        netlink_insert(sk, net, nladdr->nl_pid) :
 658                        netlink_autobind(sock);
 659                if (err)
 660                        return err;
 661        }
 662
 663        if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
 664                return 0;
 665
 666        netlink_table_grab();
 667        netlink_update_subscriptions(sk, nlk->subscriptions +
 668                                         hweight32(nladdr->nl_groups) -
 669                                         hweight32(nlk->groups[0]));
 670        nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
 671        netlink_update_listeners(sk);
 672        netlink_table_ungrab();
 673
 674        return 0;
 675}
 676
 677static int netlink_connect(struct socket *sock, struct sockaddr *addr,
 678                           int alen, int flags)
 679{
 680        int err = 0;
 681        struct sock *sk = sock->sk;
 682        struct netlink_sock *nlk = nlk_sk(sk);
 683        struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
 684
 685        if (alen < sizeof(addr->sa_family))
 686                return -EINVAL;
 687
 688        if (addr->sa_family == AF_UNSPEC) {
 689                sk->sk_state    = NETLINK_UNCONNECTED;
 690                nlk->dst_pid    = 0;
 691                nlk->dst_group  = 0;
 692                return 0;
 693        }
 694        if (addr->sa_family != AF_NETLINK)
 695                return -EINVAL;
 696
 697        /* Only superuser is allowed to send multicasts */
 698        if (nladdr->nl_groups && !netlink_capable(sock, NL_NONROOT_SEND))
 699                return -EPERM;
 700
 701        if (!nlk->pid)
 702                err = netlink_autobind(sock);
 703
 704        if (err == 0) {
 705                sk->sk_state    = NETLINK_CONNECTED;
 706                nlk->dst_pid    = nladdr->nl_pid;
 707                nlk->dst_group  = ffs(nladdr->nl_groups);
 708        }
 709
 710        return err;
 711}
 712
 713static int netlink_getname(struct socket *sock, struct sockaddr *addr,
 714                           int *addr_len, int peer)
 715{
 716        struct sock *sk = sock->sk;
 717        struct netlink_sock *nlk = nlk_sk(sk);
 718        DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
 719
 720        nladdr->nl_family = AF_NETLINK;
 721        nladdr->nl_pad = 0;
 722        *addr_len = sizeof(*nladdr);
 723
 724        if (peer) {
 725                nladdr->nl_pid = nlk->dst_pid;
 726                nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
 727        } else {
 728                nladdr->nl_pid = nlk->pid;
 729                nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
 730        }
 731        return 0;
 732}
 733
 734static void netlink_overrun(struct sock *sk)
 735{
 736        struct netlink_sock *nlk = nlk_sk(sk);
 737
 738        if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
 739                if (!test_and_set_bit(0, &nlk_sk(sk)->state)) {
 740                        sk->sk_err = ENOBUFS;
 741                        sk->sk_error_report(sk);
 742                }
 743        }
 744        atomic_inc(&sk->sk_drops);
 745}
 746
 747static struct sock *netlink_getsockbypid(struct sock *ssk, u32 pid)
 748{
 749        struct sock *sock;
 750        struct netlink_sock *nlk;
 751
 752        sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, pid);
 753        if (!sock)
 754                return ERR_PTR(-ECONNREFUSED);
 755
 756        /* Don't bother queuing skb if kernel socket has no input function */
 757        nlk = nlk_sk(sock);
 758        if (sock->sk_state == NETLINK_CONNECTED &&
 759            nlk->dst_pid != nlk_sk(ssk)->pid) {
 760                sock_put(sock);
 761                return ERR_PTR(-ECONNREFUSED);
 762        }
 763        return sock;
 764}
 765
 766struct sock *netlink_getsockbyfilp(struct file *filp)
 767{
 768        struct inode *inode = filp->f_path.dentry->d_inode;
 769        struct sock *sock;
 770
 771        if (!S_ISSOCK(inode->i_mode))
 772                return ERR_PTR(-ENOTSOCK);
 773
 774        sock = SOCKET_I(inode)->sk;
 775        if (sock->sk_family != AF_NETLINK)
 776                return ERR_PTR(-EINVAL);
 777
 778        sock_hold(sock);
 779        return sock;
 780}
 781
 782/*
 783 * Attach a skb to a netlink socket.
 784 * The caller must hold a reference to the destination socket. On error, the
 785 * reference is dropped. The skb is not send to the destination, just all
 786 * all error checks are performed and memory in the queue is reserved.
 787 * Return values:
 788 * < 0: error. skb freed, reference to sock dropped.
 789 * 0: continue
 790 * 1: repeat lookup - reference dropped while waiting for socket memory.
 791 */
 792int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 793                      long *timeo, struct sock *ssk)
 794{
 795        struct netlink_sock *nlk;
 796
 797        nlk = nlk_sk(sk);
 798
 799        if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
 800            test_bit(0, &nlk->state)) {
 801                DECLARE_WAITQUEUE(wait, current);
 802                if (!*timeo) {
 803                        if (!ssk || netlink_is_kernel(ssk))
 804                                netlink_overrun(sk);
 805                        sock_put(sk);
 806                        kfree_skb(skb);
 807                        return -EAGAIN;
 808                }
 809
 810                __set_current_state(TASK_INTERRUPTIBLE);
 811                add_wait_queue(&nlk->wait, &wait);
 812
 813                if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
 814                     test_bit(0, &nlk->state)) &&
 815                    !sock_flag(sk, SOCK_DEAD))
 816                        *timeo = schedule_timeout(*timeo);
 817
 818                __set_current_state(TASK_RUNNING);
 819                remove_wait_queue(&nlk->wait, &wait);
 820                sock_put(sk);
 821
 822                if (signal_pending(current)) {
 823                        kfree_skb(skb);
 824                        return sock_intr_errno(*timeo);
 825                }
 826                return 1;
 827        }
 828        skb_set_owner_r(skb, sk);
 829        return 0;
 830}
 831
 832int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
 833{
 834        int len = skb->len;
 835
 836        skb_queue_tail(&sk->sk_receive_queue, skb);
 837        sk->sk_data_ready(sk, len);
 838        sock_put(sk);
 839        return len;
 840}
 841
 842void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
 843{
 844        kfree_skb(skb);
 845        sock_put(sk);
 846}
 847
 848static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
 849{
 850        int delta;
 851
 852        skb_orphan(skb);
 853
 854        delta = skb->end - skb->tail;
 855        if (delta * 2 < skb->truesize)
 856                return skb;
 857
 858        if (skb_shared(skb)) {
 859                struct sk_buff *nskb = skb_clone(skb, allocation);
 860                if (!nskb)
 861                        return skb;
 862                kfree_skb(skb);
 863                skb = nskb;
 864        }
 865
 866        if (!pskb_expand_head(skb, 0, -delta, allocation))
 867                skb->truesize -= delta;
 868
 869        return skb;
 870}
 871
 872static void netlink_rcv_wake(struct sock *sk)
 873{
 874        struct netlink_sock *nlk = nlk_sk(sk);
 875
 876        if (skb_queue_empty(&sk->sk_receive_queue))
 877                clear_bit(0, &nlk->state);
 878        if (!test_bit(0, &nlk->state))
 879                wake_up_interruptible(&nlk->wait);
 880}
 881
 882static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb)
 883{
 884        int ret;
 885        struct netlink_sock *nlk = nlk_sk(sk);
 886
 887        ret = -ECONNREFUSED;
 888        if (nlk->netlink_rcv != NULL) {
 889                ret = skb->len;
 890                skb_set_owner_r(skb, sk);
 891                nlk->netlink_rcv(skb);
 892        }
 893        kfree_skb(skb);
 894        sock_put(sk);
 895        return ret;
 896}
 897
 898int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
 899                    u32 pid, int nonblock)
 900{
 901        struct sock *sk;
 902        int err;
 903        long timeo;
 904
 905        skb = netlink_trim(skb, gfp_any());
 906
 907        timeo = sock_sndtimeo(ssk, nonblock);
 908retry:
 909        sk = netlink_getsockbypid(ssk, pid);
 910        if (IS_ERR(sk)) {
 911                kfree_skb(skb);
 912                return PTR_ERR(sk);
 913        }
 914        if (netlink_is_kernel(sk))
 915                return netlink_unicast_kernel(sk, skb);
 916
 917        if (sk_filter(sk, skb)) {
 918                err = skb->len;
 919                kfree_skb(skb);
 920                sock_put(sk);
 921                return err;
 922        }
 923
 924        err = netlink_attachskb(sk, skb, &timeo, ssk);
 925        if (err == 1)
 926                goto retry;
 927        if (err)
 928                return err;
 929
 930        return netlink_sendskb(sk, skb);
 931}
 932EXPORT_SYMBOL(netlink_unicast);
 933
 934int netlink_has_listeners(struct sock *sk, unsigned int group)
 935{
 936        int res = 0;
 937        struct listeners *listeners;
 938
 939        BUG_ON(!netlink_is_kernel(sk));
 940
 941        rcu_read_lock();
 942        listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
 943
 944        if (group - 1 < nl_table[sk->sk_protocol].groups)
 945                res = test_bit(group - 1, listeners->masks);
 946
 947        rcu_read_unlock();
 948
 949        return res;
 950}
 951EXPORT_SYMBOL_GPL(netlink_has_listeners);
 952
 953static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
 954{
 955        struct netlink_sock *nlk = nlk_sk(sk);
 956
 957        if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
 958            !test_bit(0, &nlk->state)) {
 959                skb_set_owner_r(skb, sk);
 960                skb_queue_tail(&sk->sk_receive_queue, skb);
 961                sk->sk_data_ready(sk, skb->len);
 962                return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
 963        }
 964        return -1;
 965}
 966
 967struct netlink_broadcast_data {
 968        struct sock *exclude_sk;
 969        struct net *net;
 970        u32 pid;
 971        u32 group;
 972        int failure;
 973        int delivery_failure;
 974        int congested;
 975        int delivered;
 976        gfp_t allocation;
 977        struct sk_buff *skb, *skb2;
 978        int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
 979        void *tx_data;
 980};
 981
 982static int do_one_broadcast(struct sock *sk,
 983                                   struct netlink_broadcast_data *p)
 984{
 985        struct netlink_sock *nlk = nlk_sk(sk);
 986        int val;
 987
 988        if (p->exclude_sk == sk)
 989                goto out;
 990
 991        if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
 992            !test_bit(p->group - 1, nlk->groups))
 993                goto out;
 994
 995        if (!net_eq(sock_net(sk), p->net))
 996                goto out;
 997
 998        if (p->failure) {
 999                netlink_overrun(sk);
1000                goto out;
1001        }
1002
1003        sock_hold(sk);
1004        if (p->skb2 == NULL) {
1005                if (skb_shared(p->skb)) {
1006                        p->skb2 = skb_clone(p->skb, p->allocation);
1007                } else {
1008                        p->skb2 = skb_get(p->skb);
1009                        /*
1010                         * skb ownership may have been set when
1011                         * delivered to a previous socket.
1012                         */
1013                        skb_orphan(p->skb2);
1014                }
1015        }
1016        if (p->skb2 == NULL) {
1017                netlink_overrun(sk);
1018                /* Clone failed. Notify ALL listeners. */
1019                p->failure = 1;
1020                if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
1021                        p->delivery_failure = 1;
1022        } else if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
1023                kfree_skb(p->skb2);
1024                p->skb2 = NULL;
1025        } else if (sk_filter(sk, p->skb2)) {
1026                kfree_skb(p->skb2);
1027                p->skb2 = NULL;
1028        } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {
1029                netlink_overrun(sk);
1030                if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
1031                        p->delivery_failure = 1;
1032        } else {
1033                p->congested |= val;
1034                p->delivered = 1;
1035                p->skb2 = NULL;
1036        }
1037        sock_put(sk);
1038
1039out:
1040        return 0;
1041}
1042
1043int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 pid,
1044        u32 group, gfp_t allocation,
1045        int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
1046        void *filter_data)
1047{
1048        struct net *net = sock_net(ssk);
1049        struct netlink_broadcast_data info;
1050        struct hlist_node *node;
1051        struct sock *sk;
1052
1053        skb = netlink_trim(skb, allocation);
1054
1055        info.exclude_sk = ssk;
1056        info.net = net;
1057        info.pid = pid;
1058        info.group = group;
1059        info.failure = 0;
1060        info.delivery_failure = 0;
1061        info.congested = 0;
1062        info.delivered = 0;
1063        info.allocation = allocation;
1064        info.skb = skb;
1065        info.skb2 = NULL;
1066        info.tx_filter = filter;
1067        info.tx_data = filter_data;
1068
1069        /* While we sleep in clone, do not allow to change socket list */
1070
1071        netlink_lock_table();
1072
1073        sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list)
1074                do_one_broadcast(sk, &info);
1075
1076        consume_skb(skb);
1077
1078        netlink_unlock_table();
1079
1080        if (info.delivery_failure) {
1081                kfree_skb(info.skb2);
1082                return -ENOBUFS;
1083        } else
1084                consume_skb(info.skb2);
1085
1086        if (info.delivered) {
1087                if (info.congested && (allocation & __GFP_WAIT))
1088                        yield();
1089                return 0;
1090        }
1091        return -ESRCH;
1092}
1093EXPORT_SYMBOL(netlink_broadcast_filtered);
1094
1095int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid,
1096                      u32 group, gfp_t allocation)
1097{
1098        return netlink_broadcast_filtered(ssk, skb, pid, group, allocation,
1099                NULL, NULL);
1100}
1101EXPORT_SYMBOL(netlink_broadcast);
1102
1103struct netlink_set_err_data {
1104        struct sock *exclude_sk;
1105        u32 pid;
1106        u32 group;
1107        int code;
1108};
1109
1110static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
1111{
1112        struct netlink_sock *nlk = nlk_sk(sk);
1113        int ret = 0;
1114
1115        if (sk == p->exclude_sk)
1116                goto out;
1117
1118        if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
1119                goto out;
1120
1121        if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
1122            !test_bit(p->group - 1, nlk->groups))
1123                goto out;
1124
1125        if (p->code == ENOBUFS && nlk->flags & NETLINK_RECV_NO_ENOBUFS) {
1126                ret = 1;
1127                goto out;
1128        }
1129
1130        sk->sk_err = p->code;
1131        sk->sk_error_report(sk);
1132out:
1133        return ret;
1134}
1135
1136/**
1137 * netlink_set_err - report error to broadcast listeners
1138 * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
1139 * @pid: the PID of a process that we want to skip (if any)
1140 * @groups: the broadcast group that will notice the error
1141 * @code: error code, must be negative (as usual in kernelspace)
1142 *
1143 * This function returns the number of broadcast listeners that have set the
1144 * NETLINK_RECV_NO_ENOBUFS socket option.
1145 */
1146int netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
1147{
1148        struct netlink_set_err_data info;
1149        struct hlist_node *node;
1150        struct sock *sk;
1151        int ret = 0;
1152
1153        info.exclude_sk = ssk;
1154        info.pid = pid;
1155        info.group = group;
1156        /* sk->sk_err wants a positive error value */
1157        info.code = -code;
1158
1159        read_lock(&nl_table_lock);
1160
1161        sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list)
1162                ret += do_one_set_err(sk, &info);
1163
1164        read_unlock(&nl_table_lock);
1165        return ret;
1166}
1167EXPORT_SYMBOL(netlink_set_err);
1168
1169/* must be called with netlink table grabbed */
1170static void netlink_update_socket_mc(struct netlink_sock *nlk,
1171                                     unsigned int group,
1172                                     int is_new)
1173{
1174        int old, new = !!is_new, subscriptions;
1175
1176        old = test_bit(group - 1, nlk->groups);
1177        subscriptions = nlk->subscriptions - old + new;
1178        if (new)
1179                __set_bit(group - 1, nlk->groups);
1180        else
1181                __clear_bit(group - 1, nlk->groups);
1182        netlink_update_subscriptions(&nlk->sk, subscriptions);
1183        netlink_update_listeners(&nlk->sk);
1184}
1185
1186static int netlink_setsockopt(struct socket *sock, int level, int optname,
1187                              char __user *optval, unsigned int optlen)
1188{
1189        struct sock *sk = sock->sk;
1190        struct netlink_sock *nlk = nlk_sk(sk);
1191        unsigned int val = 0;
1192        int err;
1193
1194        if (level != SOL_NETLINK)
1195                return -ENOPROTOOPT;
1196
1197        if (optlen >= sizeof(int) &&
1198            get_user(val, (unsigned int __user *)optval))
1199                return -EFAULT;
1200
1201        switch (optname) {
1202        case NETLINK_PKTINFO:
1203                if (val)
1204                        nlk->flags |= NETLINK_RECV_PKTINFO;
1205                else
1206                        nlk->flags &= ~NETLINK_RECV_PKTINFO;
1207                err = 0;
1208                break;
1209        case NETLINK_ADD_MEMBERSHIP:
1210        case NETLINK_DROP_MEMBERSHIP: {
1211                if (!netlink_capable(sock, NL_NONROOT_RECV))
1212                        return -EPERM;
1213                err = netlink_realloc_groups(sk);
1214                if (err)
1215                        return err;
1216                if (!val || val - 1 >= nlk->ngroups)
1217                        return -EINVAL;
1218                netlink_table_grab();
1219                netlink_update_socket_mc(nlk, val,
1220                                         optname == NETLINK_ADD_MEMBERSHIP);
1221                netlink_table_ungrab();
1222                err = 0;
1223                break;
1224        }
1225        case NETLINK_BROADCAST_ERROR:
1226                if (val)
1227                        nlk->flags |= NETLINK_BROADCAST_SEND_ERROR;
1228                else
1229                        nlk->flags &= ~NETLINK_BROADCAST_SEND_ERROR;
1230                err = 0;
1231                break;
1232        case NETLINK_NO_ENOBUFS:
1233                if (val) {
1234                        nlk->flags |= NETLINK_RECV_NO_ENOBUFS;
1235                        clear_bit(0, &nlk->state);
1236                        wake_up_interruptible(&nlk->wait);
1237                } else
1238                        nlk->flags &= ~NETLINK_RECV_NO_ENOBUFS;
1239                err = 0;
1240                break;
1241        default:
1242                err = -ENOPROTOOPT;
1243        }
1244        return err;
1245}
1246
1247static int netlink_getsockopt(struct socket *sock, int level, int optname,
1248                              char __user *optval, int __user *optlen)
1249{
1250        struct sock *sk = sock->sk;
1251        struct netlink_sock *nlk = nlk_sk(sk);
1252        int len, val, err;
1253
1254        if (level != SOL_NETLINK)
1255                return -ENOPROTOOPT;
1256
1257        if (get_user(len, optlen))
1258                return -EFAULT;
1259        if (len < 0)
1260                return -EINVAL;
1261
1262        switch (optname) {
1263        case NETLINK_PKTINFO:
1264                if (len < sizeof(int))
1265                        return -EINVAL;
1266                len = sizeof(int);
1267                val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0;
1268                if (put_user(len, optlen) ||
1269                    put_user(val, optval))
1270                        return -EFAULT;
1271                err = 0;
1272                break;
1273        case NETLINK_BROADCAST_ERROR:
1274                if (len < sizeof(int))
1275                        return -EINVAL;
1276                len = sizeof(int);
1277                val = nlk->flags & NETLINK_BROADCAST_SEND_ERROR ? 1 : 0;
1278                if (put_user(len, optlen) ||
1279                    put_user(val, optval))
1280                        return -EFAULT;
1281                err = 0;
1282                break;
1283        case NETLINK_NO_ENOBUFS:
1284                if (len < sizeof(int))
1285                        return -EINVAL;
1286                len = sizeof(int);
1287                val = nlk->flags & NETLINK_RECV_NO_ENOBUFS ? 1 : 0;
1288                if (put_user(len, optlen) ||
1289                    put_user(val, optval))
1290                        return -EFAULT;
1291                err = 0;
1292                break;
1293        default:
1294                err = -ENOPROTOOPT;
1295        }
1296        return err;
1297}
1298
1299static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
1300{
1301        struct nl_pktinfo info;
1302
1303        info.group = NETLINK_CB(skb).dst_group;
1304        put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
1305}
1306
1307static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
1308                           struct msghdr *msg, size_t len)
1309{
1310        struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1311        struct sock *sk = sock->sk;
1312        struct netlink_sock *nlk = nlk_sk(sk);
1313        struct sockaddr_nl *addr = msg->msg_name;
1314        u32 dst_pid;
1315        u32 dst_group;
1316        struct sk_buff *skb;
1317        int err;
1318        struct scm_cookie scm;
1319
1320        if (msg->msg_flags&MSG_OOB)
1321                return -EOPNOTSUPP;
1322
1323        if (NULL == siocb->scm)
1324                siocb->scm = &scm;
1325
1326        err = scm_send(sock, msg, siocb->scm);
1327        if (err < 0)
1328                return err;
1329
1330        if (msg->msg_namelen) {
1331                err = -EINVAL;
1332                if (addr->nl_family != AF_NETLINK)
1333                        goto out;
1334                dst_pid = addr->nl_pid;
1335                dst_group = ffs(addr->nl_groups);
1336                err =  -EPERM;
1337                if (dst_group && !netlink_capable(sock, NL_NONROOT_SEND))
1338                        goto out;
1339        } else {
1340                dst_pid = nlk->dst_pid;
1341                dst_group = nlk->dst_group;
1342        }
1343
1344        if (!nlk->pid) {
1345                err = netlink_autobind(sock);
1346                if (err)
1347                        goto out;
1348        }
1349
1350        err = -EMSGSIZE;
1351        if (len > sk->sk_sndbuf - 32)
1352                goto out;
1353        err = -ENOBUFS;
1354        skb = alloc_skb(len, GFP_KERNEL);
1355        if (skb == NULL)
1356                goto out;
1357
1358        NETLINK_CB(skb).pid     = nlk->pid;
1359        NETLINK_CB(skb).dst_group = dst_group;
1360        memcpy(NETLINK_CREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
1361
1362        err = -EFAULT;
1363        if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
1364                kfree_skb(skb);
1365                goto out;
1366        }
1367
1368        err = security_netlink_send(sk, skb);
1369        if (err) {
1370                kfree_skb(skb);
1371                goto out;
1372        }
1373
1374        if (dst_group) {
1375                atomic_inc(&skb->users);
1376                netlink_broadcast(sk, skb, dst_pid, dst_group, GFP_KERNEL);
1377        }
1378        err = netlink_unicast(sk, skb, dst_pid, msg->msg_flags&MSG_DONTWAIT);
1379
1380out:
1381        scm_destroy(siocb->scm);
1382        return err;
1383}
1384
1385static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
1386                           struct msghdr *msg, size_t len,
1387                           int flags)
1388{
1389        struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1390        struct scm_cookie scm;
1391        struct sock *sk = sock->sk;
1392        struct netlink_sock *nlk = nlk_sk(sk);
1393        int noblock = flags&MSG_DONTWAIT;
1394        size_t copied;
1395        struct sk_buff *skb, *data_skb;
1396        int err, ret;
1397
1398        if (flags&MSG_OOB)
1399                return -EOPNOTSUPP;
1400
1401        copied = 0;
1402
1403        skb = skb_recv_datagram(sk, flags, noblock, &err);
1404        if (skb == NULL)
1405                goto out;
1406
1407        data_skb = skb;
1408
1409#ifdef CONFIG_COMPAT_NETLINK_MESSAGES
1410        if (unlikely(skb_shinfo(skb)->frag_list)) {
1411                /*
1412                 * If this skb has a frag_list, then here that means that we
1413                 * will have to use the frag_list skb's data for compat tasks
1414                 * and the regular skb's data for normal (non-compat) tasks.
1415                 *
1416                 * If we need to send the compat skb, assign it to the
1417                 * 'data_skb' variable so that it will be used below for data
1418                 * copying. We keep 'skb' for everything else, including
1419                 * freeing both later.
1420                 */
1421                if (flags & MSG_CMSG_COMPAT)
1422                        data_skb = skb_shinfo(skb)->frag_list;
1423        }
1424#endif
1425
1426        msg->msg_namelen = 0;
1427
1428        copied = data_skb->len;
1429        if (len < copied) {
1430                msg->msg_flags |= MSG_TRUNC;
1431                copied = len;
1432        }
1433
1434        skb_reset_transport_header(data_skb);
1435        err = skb_copy_datagram_iovec(data_skb, 0, msg->msg_iov, copied);
1436
1437        if (msg->msg_name) {
1438                struct sockaddr_nl *addr = (struct sockaddr_nl *)msg->msg_name;
1439                addr->nl_family = AF_NETLINK;
1440                addr->nl_pad    = 0;
1441                addr->nl_pid    = NETLINK_CB(skb).pid;
1442                addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
1443                msg->msg_namelen = sizeof(*addr);
1444        }
1445
1446        if (nlk->flags & NETLINK_RECV_PKTINFO)
1447                netlink_cmsg_recv_pktinfo(msg, skb);
1448
1449        if (NULL == siocb->scm) {
1450                memset(&scm, 0, sizeof(scm));
1451                siocb->scm = &scm;
1452        }
1453        siocb->scm->creds = *NETLINK_CREDS(skb);
1454        if (flags & MSG_TRUNC)
1455                copied = data_skb->len;
1456
1457        skb_free_datagram(sk, skb);
1458
1459        if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
1460                ret = netlink_dump(sk);
1461                if (ret) {
1462                        sk->sk_err = ret;
1463                        sk->sk_error_report(sk);
1464                }
1465        }
1466
1467        scm_recv(sock, msg, siocb->scm, flags);
1468out:
1469        netlink_rcv_wake(sk);
1470        return err ? : copied;
1471}
1472
1473static void netlink_data_ready(struct sock *sk, int len)
1474{
1475        BUG();
1476}
1477
1478/*
1479 *      We export these functions to other modules. They provide a
1480 *      complete set of kernel non-blocking support for message
1481 *      queueing.
1482 */
1483
1484struct sock *
1485netlink_kernel_create(struct net *net, int unit, unsigned int groups,
1486                      void (*input)(struct sk_buff *skb),
1487                      struct mutex *cb_mutex, struct module *module)
1488{
1489        struct socket *sock;
1490        struct sock *sk;
1491        struct netlink_sock *nlk;
1492        struct listeners *listeners = NULL;
1493
1494        BUG_ON(!nl_table);
1495
1496        if (unit < 0 || unit >= MAX_LINKS)
1497                return NULL;
1498
1499        if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
1500                return NULL;
1501
1502        /*
1503         * We have to just have a reference on the net from sk, but don't
1504         * get_net it. Besides, we cannot get and then put the net here.
1505         * So we create one inside init_net and the move it to net.
1506         */
1507
1508        if (__netlink_create(&init_net, sock, cb_mutex, unit) < 0)
1509                goto out_sock_release_nosk;
1510
1511        sk = sock->sk;
1512        sk_change_net(sk, net);
1513
1514        if (groups < 32)
1515                groups = 32;
1516
1517        listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
1518        if (!listeners)
1519                goto out_sock_release;
1520
1521        sk->sk_data_ready = netlink_data_ready;
1522        if (input)
1523                nlk_sk(sk)->netlink_rcv = input;
1524
1525        if (netlink_insert(sk, net, 0))
1526                goto out_sock_release;
1527
1528        nlk = nlk_sk(sk);
1529        nlk->flags |= NETLINK_KERNEL_SOCKET;
1530
1531        netlink_table_grab();
1532        if (!nl_table[unit].registered) {
1533                nl_table[unit].groups = groups;
1534                rcu_assign_pointer(nl_table[unit].listeners, listeners);
1535                nl_table[unit].cb_mutex = cb_mutex;
1536                nl_table[unit].module = module;
1537                nl_table[unit].registered = 1;
1538        } else {
1539                kfree(listeners);
1540                nl_table[unit].registered++;
1541        }
1542        netlink_table_ungrab();
1543        return sk;
1544
1545out_sock_release:
1546        kfree(listeners);
1547        netlink_kernel_release(sk);
1548        return NULL;
1549
1550out_sock_release_nosk:
1551        sock_release(sock);
1552        return NULL;
1553}
1554EXPORT_SYMBOL(netlink_kernel_create);
1555
1556
1557void
1558netlink_kernel_release(struct sock *sk)
1559{
1560        sk_release_kernel(sk);
1561}
1562EXPORT_SYMBOL(netlink_kernel_release);
1563
1564int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
1565{
1566        struct listeners *new, *old;
1567        struct netlink_table *tbl = &nl_table[sk->sk_protocol];
1568
1569        if (groups < 32)
1570                groups = 32;
1571
1572        if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
1573                new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
1574                if (!new)
1575                        return -ENOMEM;
1576                old = rcu_dereference_protected(tbl->listeners, 1);
1577                memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
1578                rcu_assign_pointer(tbl->listeners, new);
1579
1580                kfree_rcu(old, rcu);
1581        }
1582        tbl->groups = groups;
1583
1584        return 0;
1585}
1586
1587/**
1588 * netlink_change_ngroups - change number of multicast groups
1589 *
1590 * This changes the number of multicast groups that are available
1591 * on a certain netlink family. Note that it is not possible to
1592 * change the number of groups to below 32. Also note that it does
1593 * not implicitly call netlink_clear_multicast_users() when the
1594 * number of groups is reduced.
1595 *
1596 * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
1597 * @groups: The new number of groups.
1598 */
1599int netlink_change_ngroups(struct sock *sk, unsigned int groups)
1600{
1601        int err;
1602
1603        netlink_table_grab();
1604        err = __netlink_change_ngroups(sk, groups);
1605        netlink_table_ungrab();
1606
1607        return err;
1608}
1609
1610void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
1611{
1612        struct sock *sk;
1613        struct hlist_node *node;
1614        struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
1615
1616        sk_for_each_bound(sk, node, &tbl->mc_list)
1617                netlink_update_socket_mc(nlk_sk(sk), group, 0);
1618}
1619
1620/**
1621 * netlink_clear_multicast_users - kick off multicast listeners
1622 *
1623 * This function removes all listeners from the given group.
1624 * @ksk: The kernel netlink socket, as returned by
1625 *      netlink_kernel_create().
1626 * @group: The multicast group to clear.
1627 */
1628void netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
1629{
1630        netlink_table_grab();
1631        __netlink_clear_multicast_users(ksk, group);
1632        netlink_table_ungrab();
1633}
1634
1635void netlink_set_nonroot(int protocol, unsigned int flags)
1636{
1637        if ((unsigned int)protocol < MAX_LINKS)
1638                nl_table[protocol].nl_nonroot = flags;
1639}
1640EXPORT_SYMBOL(netlink_set_nonroot);
1641
1642static void netlink_destroy_callback(struct netlink_callback *cb)
1643{
1644        kfree_skb(cb->skb);
1645        kfree(cb);
1646}
1647
1648/*
1649 * It looks a bit ugly.
1650 * It would be better to create kernel thread.
1651 */
1652
1653static int netlink_dump(struct sock *sk)
1654{
1655        struct netlink_sock *nlk = nlk_sk(sk);
1656        struct netlink_callback *cb;
1657        struct sk_buff *skb = NULL;
1658        struct nlmsghdr *nlh;
1659        int len, err = -ENOBUFS;
1660        int alloc_size;
1661
1662        mutex_lock(nlk->cb_mutex);
1663
1664        cb = nlk->cb;
1665        if (cb == NULL) {
1666                err = -EINVAL;
1667                goto errout_skb;
1668        }
1669
1670        alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
1671
1672        skb = sock_rmalloc(sk, alloc_size, 0, GFP_KERNEL);
1673        if (!skb)
1674                goto errout_skb;
1675
1676        len = cb->dump(skb, cb);
1677
1678        if (len > 0) {
1679                mutex_unlock(nlk->cb_mutex);
1680
1681                if (sk_filter(sk, skb))
1682                        kfree_skb(skb);
1683                else {
1684                        skb_queue_tail(&sk->sk_receive_queue, skb);
1685                        sk->sk_data_ready(sk, skb->len);
1686                }
1687                return 0;
1688        }
1689
1690        nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
1691        if (!nlh)
1692                goto errout_skb;
1693
1694        nl_dump_check_consistent(cb, nlh);
1695
1696        memcpy(nlmsg_data(nlh), &len, sizeof(len));
1697
1698        if (sk_filter(sk, skb))
1699                kfree_skb(skb);
1700        else {
1701                skb_queue_tail(&sk->sk_receive_queue, skb);
1702                sk->sk_data_ready(sk, skb->len);
1703        }
1704
1705        if (cb->done)
1706                cb->done(cb);
1707        nlk->cb = NULL;
1708        mutex_unlock(nlk->cb_mutex);
1709
1710        netlink_destroy_callback(cb);
1711        return 0;
1712
1713errout_skb:
1714        mutex_unlock(nlk->cb_mutex);
1715        kfree_skb(skb);
1716        return err;
1717}
1718
1719int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
1720                       const struct nlmsghdr *nlh,
1721                       int (*dump)(struct sk_buff *skb,
1722                                   struct netlink_callback *),
1723                       int (*done)(struct netlink_callback *),
1724                       u16 min_dump_alloc)
1725{
1726        struct netlink_callback *cb;
1727        struct sock *sk;
1728        struct netlink_sock *nlk;
1729        int ret;
1730
1731        cb = kzalloc(sizeof(*cb), GFP_KERNEL);
1732        if (cb == NULL)
1733                return -ENOBUFS;
1734
1735        cb->dump = dump;
1736        cb->done = done;
1737        cb->nlh = nlh;
1738        cb->min_dump_alloc = min_dump_alloc;
1739        atomic_inc(&skb->users);
1740        cb->skb = skb;
1741
1742        sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).pid);
1743        if (sk == NULL) {
1744                netlink_destroy_callback(cb);
1745                return -ECONNREFUSED;
1746        }
1747        nlk = nlk_sk(sk);
1748        /* A dump is in progress... */
1749        mutex_lock(nlk->cb_mutex);
1750        if (nlk->cb) {
1751                mutex_unlock(nlk->cb_mutex);
1752                netlink_destroy_callback(cb);
1753                sock_put(sk);
1754                return -EBUSY;
1755        }
1756        nlk->cb = cb;
1757        mutex_unlock(nlk->cb_mutex);
1758
1759        ret = netlink_dump(sk);
1760
1761        sock_put(sk);
1762
1763        if (ret)
1764                return ret;
1765
1766        /* We successfully started a dump, by returning -EINTR we
1767         * signal not to send ACK even if it was requested.
1768         */
1769        return -EINTR;
1770}
1771EXPORT_SYMBOL(netlink_dump_start);
1772
1773void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
1774{
1775        struct sk_buff *skb;
1776        struct nlmsghdr *rep;
1777        struct nlmsgerr *errmsg;
1778        size_t payload = sizeof(*errmsg);
1779
1780        /* error messages get the original request appened */
1781        if (err)
1782                payload += nlmsg_len(nlh);
1783
1784        skb = nlmsg_new(payload, GFP_KERNEL);
1785        if (!skb) {
1786                struct sock *sk;
1787
1788                sk = netlink_lookup(sock_net(in_skb->sk),
1789                                    in_skb->sk->sk_protocol,
1790                                    NETLINK_CB(in_skb).pid);
1791                if (sk) {
1792                        sk->sk_err = ENOBUFS;
1793                        sk->sk_error_report(sk);
1794                        sock_put(sk);
1795                }
1796                return;
1797        }
1798
1799        rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq,
1800                          NLMSG_ERROR, payload, 0);
1801        errmsg = nlmsg_data(rep);
1802        errmsg->error = err;
1803        memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh));
1804        netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid, MSG_DONTWAIT);
1805}
1806EXPORT_SYMBOL(netlink_ack);
1807
1808int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
1809                                                     struct nlmsghdr *))
1810{
1811        struct nlmsghdr *nlh;
1812        int err;
1813
1814        while (skb->len >= nlmsg_total_size(0)) {
1815                int msglen;
1816
1817                nlh = nlmsg_hdr(skb);
1818                err = 0;
1819
1820                if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
1821                        return 0;
1822
1823                /* Only requests are handled by the kernel */
1824                if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
1825                        goto ack;
1826
1827                /* Skip control messages */
1828                if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
1829                        goto ack;
1830
1831                err = cb(skb, nlh);
1832                if (err == -EINTR)
1833                        goto skip;
1834
1835ack:
1836                if (nlh->nlmsg_flags & NLM_F_ACK || err)
1837                        netlink_ack(skb, nlh, err);
1838
1839skip:
1840                msglen = NLMSG_ALIGN(nlh->nlmsg_len);
1841                if (msglen > skb->len)
1842                        msglen = skb->len;
1843                skb_pull(skb, msglen);
1844        }
1845
1846        return 0;
1847}
1848EXPORT_SYMBOL(netlink_rcv_skb);
1849
1850/**
1851 * nlmsg_notify - send a notification netlink message
1852 * @sk: netlink socket to use
1853 * @skb: notification message
1854 * @pid: destination netlink pid for reports or 0
1855 * @group: destination multicast group or 0
1856 * @report: 1 to report back, 0 to disable
1857 * @flags: allocation flags
1858 */
1859int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid,
1860                 unsigned int group, int report, gfp_t flags)
1861{
1862        int err = 0;
1863
1864        if (group) {
1865                int exclude_pid = 0;
1866
1867                if (report) {
1868                        atomic_inc(&skb->users);
1869                        exclude_pid = pid;
1870                }
1871
1872                /* errors reported via destination sk->sk_err, but propagate
1873                 * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
1874                err = nlmsg_multicast(sk, skb, exclude_pid, group, flags);
1875        }
1876
1877        if (report) {
1878                int err2;
1879
1880                err2 = nlmsg_unicast(sk, skb, pid);
1881                if (!err || err == -ESRCH)
1882                        err = err2;
1883        }
1884
1885        return err;
1886}
1887EXPORT_SYMBOL(nlmsg_notify);
1888
1889#ifdef CONFIG_PROC_FS
1890struct nl_seq_iter {
1891        struct seq_net_private p;
1892        int link;
1893        int hash_idx;
1894};
1895
1896static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos)
1897{
1898        struct nl_seq_iter *iter = seq->private;
1899        int i, j;
1900        struct sock *s;
1901        struct hlist_node *node;
1902        loff_t off = 0;
1903
1904        for (i = 0; i < MAX_LINKS; i++) {
1905                struct nl_pid_hash *hash = &nl_table[i].hash;
1906
1907                for (j = 0; j <= hash->mask; j++) {
1908                        sk_for_each(s, node, &hash->table[j]) {
1909                                if (sock_net(s) != seq_file_net(seq))
1910                                        continue;
1911                                if (off == pos) {
1912                                        iter->link = i;
1913                                        iter->hash_idx = j;
1914                                        return s;
1915                                }
1916                                ++off;
1917                        }
1918                }
1919        }
1920        return NULL;
1921}
1922
1923static void *netlink_seq_start(struct seq_file *seq, loff_t *pos)
1924        __acquires(nl_table_lock)
1925{
1926        read_lock(&nl_table_lock);
1927        return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN;
1928}
1929
1930static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1931{
1932        struct sock *s;
1933        struct nl_seq_iter *iter;
1934        int i, j;
1935
1936        ++*pos;
1937
1938        if (v == SEQ_START_TOKEN)
1939                return netlink_seq_socket_idx(seq, 0);
1940
1941        iter = seq->private;
1942        s = v;
1943        do {
1944                s = sk_next(s);
1945        } while (s && sock_net(s) != seq_file_net(seq));
1946        if (s)
1947                return s;
1948
1949        i = iter->link;
1950        j = iter->hash_idx + 1;
1951
1952        do {
1953                struct nl_pid_hash *hash = &nl_table[i].hash;
1954
1955                for (; j <= hash->mask; j++) {
1956                        s = sk_head(&hash->table[j]);
1957                        while (s && sock_net(s) != seq_file_net(seq))
1958                                s = sk_next(s);
1959                        if (s) {
1960                                iter->link = i;
1961                                iter->hash_idx = j;
1962                                return s;
1963                        }
1964                }
1965
1966                j = 0;
1967        } while (++i < MAX_LINKS);
1968
1969        return NULL;
1970}
1971
1972static void netlink_seq_stop(struct seq_file *seq, void *v)
1973        __releases(nl_table_lock)
1974{
1975        read_unlock(&nl_table_lock);
1976}
1977
1978
1979static int netlink_seq_show(struct seq_file *seq, void *v)
1980{
1981        if (v == SEQ_START_TOKEN)
1982                seq_puts(seq,
1983                         "sk       Eth Pid    Groups   "
1984                         "Rmem     Wmem     Dump     Locks     Drops     Inode\n");
1985        else {
1986                struct sock *s = v;
1987                struct netlink_sock *nlk = nlk_sk(s);
1988
1989                seq_printf(seq, "%pK %-3d %-6d %08x %-8d %-8d %pK %-8d %-8d %-8lu\n",
1990                           s,
1991                           s->sk_protocol,
1992                           nlk->pid,
1993                           nlk->groups ? (u32)nlk->groups[0] : 0,
1994                           sk_rmem_alloc_get(s),
1995                           sk_wmem_alloc_get(s),
1996                           nlk->cb,
1997                           atomic_read(&s->sk_refcnt),
1998                           atomic_read(&s->sk_drops),
1999                           sock_i_ino(s)
2000                        );
2001
2002        }
2003        return 0;
2004}
2005
2006static const struct seq_operations netlink_seq_ops = {
2007        .start  = netlink_seq_start,
2008        .next   = netlink_seq_next,
2009        .stop   = netlink_seq_stop,
2010        .show   = netlink_seq_show,
2011};
2012
2013
2014static int netlink_seq_open(struct inode *inode, struct file *file)
2015{
2016        return seq_open_net(inode, file, &netlink_seq_ops,
2017                                sizeof(struct nl_seq_iter));
2018}
2019
2020static const struct file_operations netlink_seq_fops = {
2021        .owner          = THIS_MODULE,
2022        .open           = netlink_seq_open,
2023        .read           = seq_read,
2024        .llseek         = seq_lseek,
2025        .release        = seq_release_net,
2026};
2027
2028#endif
2029
2030int netlink_register_notifier(struct notifier_block *nb)
2031{
2032        return atomic_notifier_chain_register(&netlink_chain, nb);
2033}
2034EXPORT_SYMBOL(netlink_register_notifier);
2035
2036int netlink_unregister_notifier(struct notifier_block *nb)
2037{
2038        return atomic_notifier_chain_unregister(&netlink_chain, nb);
2039}
2040EXPORT_SYMBOL(netlink_unregister_notifier);
2041
2042static const struct proto_ops netlink_ops = {
2043        .family =       PF_NETLINK,
2044        .owner =        THIS_MODULE,
2045        .release =      netlink_release,
2046        .bind =         netlink_bind,
2047        .connect =      netlink_connect,
2048        .socketpair =   sock_no_socketpair,
2049        .accept =       sock_no_accept,
2050        .getname =      netlink_getname,
2051        .poll =         datagram_poll,
2052        .ioctl =        sock_no_ioctl,
2053        .listen =       sock_no_listen,
2054        .shutdown =     sock_no_shutdown,
2055        .setsockopt =   netlink_setsockopt,
2056        .getsockopt =   netlink_getsockopt,
2057        .sendmsg =      netlink_sendmsg,
2058        .recvmsg =      netlink_recvmsg,
2059        .mmap =         sock_no_mmap,
2060        .sendpage =     sock_no_sendpage,
2061};
2062
2063static const struct net_proto_family netlink_family_ops = {
2064        .family = PF_NETLINK,
2065        .create = netlink_create,
2066        .owner  = THIS_MODULE,  /* for consistency 8) */
2067};
2068
2069static int __net_init netlink_net_init(struct net *net)
2070{
2071#ifdef CONFIG_PROC_FS
2072        if (!proc_net_fops_create(net, "netlink", 0, &netlink_seq_fops))
2073                return -ENOMEM;
2074#endif
2075        return 0;
2076}
2077
2078static void __net_exit netlink_net_exit(struct net *net)
2079{
2080#ifdef CONFIG_PROC_FS
2081        proc_net_remove(net, "netlink");
2082#endif
2083}
2084
2085static void __init netlink_add_usersock_entry(void)
2086{
2087        struct listeners *listeners;
2088        int groups = 32;
2089
2090        listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2091        if (!listeners)
2092                panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
2093
2094        netlink_table_grab();
2095
2096        nl_table[NETLINK_USERSOCK].groups = groups;
2097        rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
2098        nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
2099        nl_table[NETLINK_USERSOCK].registered = 1;
2100
2101        netlink_table_ungrab();
2102}
2103
2104static struct pernet_operations __net_initdata netlink_net_ops = {
2105        .init = netlink_net_init,
2106        .exit = netlink_net_exit,
2107};
2108
2109static int __init netlink_proto_init(void)
2110{
2111        struct sk_buff *dummy_skb;
2112        int i;
2113        unsigned long limit;
2114        unsigned int order;
2115        int err = proto_register(&netlink_proto, 0);
2116
2117        if (err != 0)
2118                goto out;
2119
2120        BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof(dummy_skb->cb));
2121
2122        nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
2123        if (!nl_table)
2124                goto panic;
2125
2126        if (totalram_pages >= (128 * 1024))
2127                limit = totalram_pages >> (21 - PAGE_SHIFT);
2128        else
2129                limit = totalram_pages >> (23 - PAGE_SHIFT);
2130
2131        order = get_bitmask_order(limit) - 1 + PAGE_SHIFT;
2132        limit = (1UL << order) / sizeof(struct hlist_head);
2133        order = get_bitmask_order(min(limit, (unsigned long)UINT_MAX)) - 1;
2134
2135        for (i = 0; i < MAX_LINKS; i++) {
2136                struct nl_pid_hash *hash = &nl_table[i].hash;
2137
2138                hash->table = nl_pid_hash_zalloc(1 * sizeof(*hash->table));
2139                if (!hash->table) {
2140                        while (i-- > 0)
2141                                nl_pid_hash_free(nl_table[i].hash.table,
2142                                                 1 * sizeof(*hash->table));
2143                        kfree(nl_table);
2144                        goto panic;
2145                }
2146                hash->max_shift = order;
2147                hash->shift = 0;
2148                hash->mask = 0;
2149                hash->rehash_time = jiffies;
2150        }
2151
2152        netlink_add_usersock_entry();
2153
2154        sock_register(&netlink_family_ops);
2155        register_pernet_subsys(&netlink_net_ops);
2156        /* The netlink device handler may be needed early. */
2157        rtnetlink_init();
2158out:
2159        return err;
2160panic:
2161        panic("netlink_init: Cannot allocate nl_table\n");
2162}
2163
2164core_initcall(netlink_proto_init);
2165
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