net/netlink/genetlink.c

   1 /*
   2  * NETLINK      Generic Netlink Family
   3  *
   4  *              Authors:        Jamal Hadi Salim
   5  *                              Thomas Graf <tgraf@suug.ch>
   6  *                              Johannes Berg <johannes@sipsolutions.net>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/errno.h>
  13 #include <linux/types.h>
  14 #include <linux/socket.h>
  15 #include <linux/string.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/mutex.h>
  18 #include <linux/bitmap.h>
  19 #include <net/sock.h>
  20 #include <net/genetlink.h>
  21
  22 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
  23
  24 void genl_lock(void)
  25 {
  26         mutex_lock(&genl_mutex);
  27 }
  28 EXPORT_SYMBOL(genl_lock);
  29
  30 void genl_unlock(void)
  31 {
  32         mutex_unlock(&genl_mutex);
  33 }
  34 EXPORT_SYMBOL(genl_unlock);
  35
  36 #ifdef CONFIG_PROVE_LOCKING
  37 int lockdep_genl_is_held(void)
  38 {
  39         return lockdep_is_held(&genl_mutex);
  40 }
  41 EXPORT_SYMBOL(lockdep_genl_is_held);
  42 #endif
  43
  44 #define GENL_FAM_TAB_SIZE       16
  45 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
  46
  47 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
  48 /*
  49  * Bitmap of multicast groups that are currently in use.
  50  *
  51  * To avoid an allocation at boot of just one unsigned long,
  52  * declare it global instead.
  53  * Bit 0 is marked as already used since group 0 is invalid.
  54  */
  55 static unsigned long mc_group_start = 0x1;
  56 static unsigned long *mc_groups = &mc_group_start;
  57 static unsigned long mc_groups_longs = 1;
  58
  59 static int genl_ctrl_event(int event, void *data);
  60
  61 static inline unsigned int genl_family_hash(unsigned int id)
  62 {
  63         return id & GENL_FAM_TAB_MASK;
  64 }
  65
  66 static inline struct list_head *genl_family_chain(unsigned int id)
  67 {
  68         return &family_ht[genl_family_hash(id)];
  69 }
  70
  71 static struct genl_family *genl_family_find_byid(unsigned int id)
  72 {
  73         struct genl_family *f;
  74
  75         list_for_each_entry(f, genl_family_chain(id), family_list)
  76                 if (f->id == id)
  77                         return f;
  78
  79         return NULL;
  80 }
  81
  82 static struct genl_family *genl_family_find_byname(char *name)
  83 {
  84         struct genl_family *f;
  85         int i;
  86
  87         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
  88                 list_for_each_entry(f, genl_family_chain(i), family_list)
  89                         if (strcmp(f->name, name) == 0)
  90                                 return f;
  91
  92         return NULL;
  93 }
  94
  95 static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
  96 {
  97         struct genl_ops *ops;
  98
  99         list_for_each_entry(ops, &family->ops_list, ops_list)
 100                 if (ops->cmd == cmd)
 101                         return ops;
 102
 103         return NULL;
 104 }
 105
 106 /* Of course we are going to have problems once we hit
 107  * 2^16 alive types, but that can only happen by year 2K
 108 */
 109 static u16 genl_generate_id(void)
 110 {
 111         static u16 id_gen_idx = GENL_MIN_ID;
 112         int i;
 113
 114         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 115                 if (!genl_family_find_byid(id_gen_idx))
 116                         return id_gen_idx;
 117                 if (++id_gen_idx > GENL_MAX_ID)
 118                         id_gen_idx = GENL_MIN_ID;
 119         }
 120
 121         return 0;
 122 }
 123
 124 static struct genl_multicast_group notify_grp;
 125
 126 /**
 127  * genl_register_mc_group - register a multicast group
 128  *
 129  * Registers the specified multicast group and notifies userspace
 130  * about the new group.
 131  *
 132  * Returns 0 on success or a negative error code.
 133  *
 134  * @family: The generic netlink family the group shall be registered for.
 135  * @grp: The group to register, must have a name.
 136  */
 137 int genl_register_mc_group(struct genl_family *family,
 138                            struct genl_multicast_group *grp)
 139 {
 140         int id;
 141         unsigned long *new_groups;
 142         int err = 0;
 143
 144         BUG_ON(grp->name[0] == '\0');
 145
 146         genl_lock();
 147
 148         /* special-case our own group */
 149         if (grp == &notify_grp)
 150                 id = GENL_ID_CTRL;
 151         else
 152                 id = find_first_zero_bit(mc_groups,
 153                                          mc_groups_longs * BITS_PER_LONG);
 154
 155
 156         if (id >= mc_groups_longs * BITS_PER_LONG) {
 157                 size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
 158
 159                 if (mc_groups == &mc_group_start) {
 160                         new_groups = kzalloc(nlen, GFP_KERNEL);
 161                         if (!new_groups) {
 162                                 err = -ENOMEM;
 163                                 goto out;
 164                         }
 165                         mc_groups = new_groups;
 166                         *mc_groups = mc_group_start;
 167                 } else {
 168                         new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
 169                         if (!new_groups) {
 170                                 err = -ENOMEM;
 171                                 goto out;
 172                         }
 173                         mc_groups = new_groups;
 174                         mc_groups[mc_groups_longs] = 0;
 175                 }
 176                 mc_groups_longs++;
 177         }
 178
 179         if (family->netnsok) {
 180                 struct net *net;
 181
 182                 netlink_table_grab();
 183                 rcu_read_lock();
 184                 for_each_net_rcu(net) {
 185                         err = __netlink_change_ngroups(net->genl_sock,
 186                                         mc_groups_longs * BITS_PER_LONG);
 187                         if (err) {
 188                                 /*
 189                                  * No need to roll back, can only fail if
 190                                  * memory allocation fails and then the
 191                                  * number of _possible_ groups has been
 192                                  * increased on some sockets which is ok.
 193                                  */
 194                                 rcu_read_unlock();
 195                                 netlink_table_ungrab();
 196                                 goto out;
 197                         }
 198                 }
 199                 rcu_read_unlock();
 200                 netlink_table_ungrab();
 201         } else {
 202                 err = netlink_change_ngroups(init_net.genl_sock,
 203                                              mc_groups_longs * BITS_PER_LONG);
 204                 if (err)
 205                         goto out;
 206         }
 207
 208         grp->id = id;
 209         set_bit(id, mc_groups);
 210         list_add_tail(&grp->list, &family->mcast_groups);
 211         grp->family = family;
 212
 213         genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
 214  out:
 215         genl_unlock();
 216         return err;
 217 }
 218 EXPORT_SYMBOL(genl_register_mc_group);
 219
 220 static void __genl_unregister_mc_group(struct genl_family *family,
 221                                        struct genl_multicast_group *grp)
 222 {
 223         struct net *net;
 224         BUG_ON(grp->family != family);
 225
 226         netlink_table_grab();
 227         rcu_read_lock();
 228         for_each_net_rcu(net)
 229                 __netlink_clear_multicast_users(net->genl_sock, grp->id);
 230         rcu_read_unlock();
 231         netlink_table_ungrab();
 232
 233         clear_bit(grp->id, mc_groups);
 234         list_del(&grp->list);
 235         genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
 236         grp->id = 0;
 237         grp->family = NULL;
 238 }
 239
 240 /**
 241  * genl_unregister_mc_group - unregister a multicast group
 242  *
 243  * Unregisters the specified multicast group and notifies userspace
 244  * about it. All current listeners on the group are removed.
 245  *
 246  * Note: It is not necessary to unregister all multicast groups before
 247  *       unregistering the family, unregistering the family will cause
 248  *       all assigned multicast groups to be unregistered automatically.
 249  *
 250  * @family: Generic netlink family the group belongs to.
 251  * @grp: The group to unregister, must have been registered successfully
 252  *       previously.
 253  */
 254 void genl_unregister_mc_group(struct genl_family *family,
 255                               struct genl_multicast_group *grp)
 256 {
 257         genl_lock();
 258         __genl_unregister_mc_group(family, grp);
 259         genl_unlock();
 260 }
 261 EXPORT_SYMBOL(genl_unregister_mc_group);
 262
 263 static void genl_unregister_mc_groups(struct genl_family *family)
 264 {
 265         struct genl_multicast_group *grp, *tmp;
 266
 267         list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
 268                 __genl_unregister_mc_group(family, grp);
 269 }
 270
 271 /**
 272  * genl_register_ops - register generic netlink operations
 273  * @family: generic netlink family
 274  * @ops: operations to be registered
 275  *
 276  * Registers the specified operations and assigns them to the specified
 277  * family. Either a doit or dumpit callback must be specified or the
 278  * operation will fail. Only one operation structure per command
 279  * identifier may be registered.
 280  *
 281  * See include/net/genetlink.h for more documenation on the operations
 282  * structure.
 283  *
 284  * Returns 0 on success or a negative error code.
 285  */
 286 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
 287 {
 288         int err = -EINVAL;
 289
 290         if (ops->dumpit == NULL && ops->doit == NULL)
 291                 goto errout;
 292
 293         if (genl_get_cmd(ops->cmd, family)) {
 294                 err = -EEXIST;
 295                 goto errout;
 296         }
 297
 298         if (ops->dumpit)
 299                 ops->flags |= GENL_CMD_CAP_DUMP;
 300         if (ops->doit)
 301                 ops->flags |= GENL_CMD_CAP_DO;
 302         if (ops->policy)
 303                 ops->flags |= GENL_CMD_CAP_HASPOL;
 304
 305         genl_lock();
 306         list_add_tail(&ops->ops_list, &family->ops_list);
 307         genl_unlock();
 308
 309         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
 310         err = 0;
 311 errout:
 312         return err;
 313 }
 314 EXPORT_SYMBOL(genl_register_ops);
 315
 316 /**
 317  * genl_unregister_ops - unregister generic netlink operations
 318  * @family: generic netlink family
 319  * @ops: operations to be unregistered
 320  *
 321  * Unregisters the specified operations and unassigns them from the
 322  * specified family. The operation blocks until the current message
 323  * processing has finished and doesn't start again until the
 324  * unregister process has finished.
 325  *
 326  * Note: It is not necessary to unregister all operations before
 327  *       unregistering the family, unregistering the family will cause
 328  *       all assigned operations to be unregistered automatically.
 329  *
 330  * Returns 0 on success or a negative error code.
 331  */
 332 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
 333 {
 334         struct genl_ops *rc;
 335
 336         genl_lock();
 337         list_for_each_entry(rc, &family->ops_list, ops_list) {
 338                 if (rc == ops) {
 339                         list_del(&ops->ops_list);
 340                         genl_unlock();
 341                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
 342                         return 0;
 343                 }
 344         }
 345         genl_unlock();
 346
 347         return -ENOENT;
 348 }
 349 EXPORT_SYMBOL(genl_unregister_ops);
 350
 351 /**
 352  * genl_register_family - register a generic netlink family
 353  * @family: generic netlink family
 354  *
 355  * Registers the specified family after validating it first. Only one
 356  * family may be registered with the same family name or identifier.
 357  * The family id may equal GENL_ID_GENERATE causing an unique id to
 358  * be automatically generated and assigned.
 359  *
 360  * Return 0 on success or a negative error code.
 361  */
 362 int genl_register_family(struct genl_family *family)
 363 {
 364         int err = -EINVAL;
 365
 366         if (family->id && family->id < GENL_MIN_ID)
 367                 goto errout;
 368
 369         if (family->id > GENL_MAX_ID)
 370                 goto errout;
 371
 372         INIT_LIST_HEAD(&family->ops_list);
 373         INIT_LIST_HEAD(&family->mcast_groups);
 374
 375         genl_lock();
 376
 377         if (genl_family_find_byname(family->name)) {
 378                 err = -EEXIST;
 379                 goto errout_locked;
 380         }
 381
 382         if (family->id == GENL_ID_GENERATE) {
 383                 u16 newid = genl_generate_id();
 384
 385                 if (!newid) {
 386                         err = -ENOMEM;
 387                         goto errout_locked;
 388                 }
 389
 390                 family->id = newid;
 391         } else if (genl_family_find_byid(family->id)) {
 392                 err = -EEXIST;
 393                 goto errout_locked;
 394         }
 395
 396         if (family->maxattr) {
 397                 family->attrbuf = kmalloc((family->maxattr+1) *
 398                                         sizeof(struct nlattr *), GFP_KERNEL);
 399                 if (family->attrbuf == NULL) {
 400                         err = -ENOMEM;
 401                         goto errout_locked;
 402                 }
 403         } else
 404                 family->attrbuf = NULL;
 405
 406         list_add_tail(&family->family_list, genl_family_chain(family->id));
 407         genl_unlock();
 408
 409         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
 410
 411         return 0;
 412
 413 errout_locked:
 414         genl_unlock();
 415 errout:
 416         return err;
 417 }
 418 EXPORT_SYMBOL(genl_register_family);
 419
 420 /**
 421  * genl_register_family_with_ops - register a generic netlink family
 422  * @family: generic netlink family
 423  * @ops: operations to be registered
 424  * @n_ops: number of elements to register
 425  *
 426  * Registers the specified family and operations from the specified table.
 427  * Only one family may be registered with the same family name or identifier.
 428  *
 429  * The family id may equal GENL_ID_GENERATE causing an unique id to
 430  * be automatically generated and assigned.
 431  *
 432  * Either a doit or dumpit callback must be specified for every registered
 433  * operation or the function will fail. Only one operation structure per
 434  * command identifier may be registered.
 435  *
 436  * See include/net/genetlink.h for more documenation on the operations
 437  * structure.
 438  *
 439  * This is equivalent to calling genl_register_family() followed by
 440  * genl_register_ops() for every operation entry in the table taking
 441  * care to unregister the family on error path.
 442  *
 443  * Return 0 on success or a negative error code.
 444  */
 445 int genl_register_family_with_ops(struct genl_family *family,
 446         struct genl_ops *ops, size_t n_ops)
 447 {
 448         int err, i;
 449
 450         err = genl_register_family(family);
 451         if (err)
 452                 return err;
 453
 454         for (i = 0; i < n_ops; ++i, ++ops) {
 455                 err = genl_register_ops(family, ops);
 456                 if (err)
 457                         goto err_out;
 458         }
 459         return 0;
 460 err_out:
 461         genl_unregister_family(family);
 462         return err;
 463 }
 464 EXPORT_SYMBOL(genl_register_family_with_ops);
 465
 466 /**
 467  * genl_unregister_family - unregister generic netlink family
 468  * @family: generic netlink family
 469  *
 470  * Unregisters the specified family.
 471  *
 472  * Returns 0 on success or a negative error code.
 473  */
 474 int genl_unregister_family(struct genl_family *family)
 475 {
 476         struct genl_family *rc;
 477
 478         genl_lock();
 479
 480         genl_unregister_mc_groups(family);
 481
 482         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 483                 if (family->id != rc->id || strcmp(rc->name, family->name))
 484                         continue;
 485
 486                 list_del(&rc->family_list);
 487                 INIT_LIST_HEAD(&family->ops_list);
 488                 genl_unlock();
 489
 490                 kfree(family->attrbuf);
 491                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
 492                 return 0;
 493         }
 494
 495         genl_unlock();
 496
 497         return -ENOENT;
 498 }
 499 EXPORT_SYMBOL(genl_unregister_family);
 500
 501 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 502 {
 503         struct genl_ops *ops;
 504         struct genl_family *family;
 505         struct net *net = sock_net(skb->sk);
 506         struct genl_info info;
 507         struct genlmsghdr *hdr = nlmsg_data(nlh);
 508         int hdrlen, err;
 509
 510         family = genl_family_find_byid(nlh->nlmsg_type);
 511         if (family == NULL)
 512                 return -ENOENT;
 513
 514         /* this family doesn't exist in this netns */
 515         if (!family->netnsok && !net_eq(net, &init_net))
 516                 return -ENOENT;
 517
 518         hdrlen = GENL_HDRLEN + family->hdrsize;
 519         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 520                 return -EINVAL;
 521
 522         ops = genl_get_cmd(hdr->cmd, family);
 523         if (ops == NULL)
 524                 return -EOPNOTSUPP;
 525
 526         if ((ops->flags & GENL_ADMIN_PERM) &&
 527             security_netlink_recv(skb, CAP_NET_ADMIN))
 528                 return -EPERM;
 529
 530         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 531                 if (ops->dumpit == NULL)
 532                         return -EOPNOTSUPP;
 533
 534                 genl_unlock();
 535                 err = netlink_dump_start(net->genl_sock, skb, nlh,
 536                                          ops->dumpit, ops->done, 0);
 537                 genl_lock();
 538                 return err;
 539         }
 540
 541         if (ops->doit == NULL)
 542                 return -EOPNOTSUPP;
 543
 544         if (family->attrbuf) {
 545                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
 546                                   ops->policy);
 547                 if (err < 0)
 548                         return err;
 549         }
 550
 551         info.snd_seq = nlh->nlmsg_seq;
 552         info.snd_pid = NETLINK_CB(skb).pid;
 553         info.nlhdr = nlh;
 554         info.genlhdr = nlmsg_data(nlh);
 555         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 556         info.attrs = family->attrbuf;
 557         genl_info_net_set(&info, net);
 558         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 559
 560         if (family->pre_doit) {
 561                 err = family->pre_doit(ops, skb, &info);
 562                 if (err)
 563                         return err;
 564         }
 565
 566         err = ops->doit(skb, &info);
 567
 568         if (family->post_doit)
 569                 family->post_doit(ops, skb, &info);
 570
 571         return err;
 572 }
 573
 574 static void genl_rcv(struct sk_buff *skb)
 575 {
 576         genl_lock();
 577         netlink_rcv_skb(skb, &genl_rcv_msg);
 578         genl_unlock();
 579 }
 580
 581 /**************************************************************************
 582  * Controller
 583  **************************************************************************/
 584
 585 static struct genl_family genl_ctrl = {
 586         .id = GENL_ID_CTRL,
 587         .name = "nlctrl",
 588         .version = 0x2,
 589         .maxattr = CTRL_ATTR_MAX,
 590         .netnsok = true,
 591 };
 592
 593 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
 594                           u32 flags, struct sk_buff *skb, u8 cmd)
 595 {
 596         void *hdr;
 597
 598         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 599         if (hdr == NULL)
 600                 return -1;
 601
 602         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
 603         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
 604         NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
 605         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
 606         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
 607
 608         if (!list_empty(&family->ops_list)) {
 609                 struct nlattr *nla_ops;
 610                 struct genl_ops *ops;
 611                 int idx = 1;
 612
 613                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 614                 if (nla_ops == NULL)
 615                         goto nla_put_failure;
 616
 617                 list_for_each_entry(ops, &family->ops_list, ops_list) {
 618                         struct nlattr *nest;
 619
 620                         nest = nla_nest_start(skb, idx++);
 621                         if (nest == NULL)
 622                                 goto nla_put_failure;
 623
 624                         NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
 625                         NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
 626
 627                         nla_nest_end(skb, nest);
 628                 }
 629
 630                 nla_nest_end(skb, nla_ops);
 631         }
 632
 633         if (!list_empty(&family->mcast_groups)) {
 634                 struct genl_multicast_group *grp;
 635                 struct nlattr *nla_grps;
 636                 int idx = 1;
 637
 638                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 639                 if (nla_grps == NULL)
 640                         goto nla_put_failure;
 641
 642                 list_for_each_entry(grp, &family->mcast_groups, list) {
 643                         struct nlattr *nest;
 644
 645                         nest = nla_nest_start(skb, idx++);
 646                         if (nest == NULL)
 647                                 goto nla_put_failure;
 648
 649                         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 650                         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 651                                        grp->name);
 652
 653                         nla_nest_end(skb, nest);
 654                 }
 655                 nla_nest_end(skb, nla_grps);
 656         }
 657
 658         return genlmsg_end(skb, hdr);
 659
 660 nla_put_failure:
 661         genlmsg_cancel(skb, hdr);
 662         return -EMSGSIZE;
 663 }
 664
 665 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
 666                                 u32 seq, u32 flags, struct sk_buff *skb,
 667                                 u8 cmd)
 668 {
 669         void *hdr;
 670         struct nlattr *nla_grps;
 671         struct nlattr *nest;
 672
 673         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 674         if (hdr == NULL)
 675                 return -1;
 676
 677         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
 678         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
 679
 680         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 681         if (nla_grps == NULL)
 682                 goto nla_put_failure;
 683
 684         nest = nla_nest_start(skb, 1);
 685         if (nest == NULL)
 686                 goto nla_put_failure;
 687
 688         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 689         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 690                        grp->name);
 691
 692         nla_nest_end(skb, nest);
 693         nla_nest_end(skb, nla_grps);
 694
 695         return genlmsg_end(skb, hdr);
 696
 697 nla_put_failure:
 698         genlmsg_cancel(skb, hdr);
 699         return -EMSGSIZE;
 700 }
 701
 702 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 703 {
 704
 705         int i, n = 0;
 706         struct genl_family *rt;
 707         struct net *net = sock_net(skb->sk);
 708         int chains_to_skip = cb->args[0];
 709         int fams_to_skip = cb->args[1];
 710
 711         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
 712                 n = 0;
 713                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 714                         if (!rt->netnsok && !net_eq(net, &init_net))
 715                                 continue;
 716                         if (++n < fams_to_skip)
 717                                 continue;
 718                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
 719                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 720                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 721                                 goto errout;
 722                 }
 723
 724                 fams_to_skip = 0;
 725         }
 726
 727 errout:
 728         cb->args[0] = i;
 729         cb->args[1] = n;
 730
 731         return skb->len;
 732 }
 733
 734 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 735                                              u32 pid, int seq, u8 cmd)
 736 {
 737         struct sk_buff *skb;
 738         int err;
 739
 740         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 741         if (skb == NULL)
 742                 return ERR_PTR(-ENOBUFS);
 743
 744         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
 745         if (err < 0) {
 746                 nlmsg_free(skb);
 747                 return ERR_PTR(err);
 748         }
 749
 750         return skb;
 751 }
 752
 753 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
 754                                             u32 pid, int seq, u8 cmd)
 755 {
 756         struct sk_buff *skb;
 757         int err;
 758
 759         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 760         if (skb == NULL)
 761                 return ERR_PTR(-ENOBUFS);
 762
 763         err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
 764         if (err < 0) {
 765                 nlmsg_free(skb);
 766                 return ERR_PTR(err);
 767         }
 768
 769         return skb;
 770 }
 771
 772 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 773         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 774         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 775                                     .len = GENL_NAMSIZ - 1 },
 776 };
 777
 778 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 779 {
 780         struct sk_buff *msg;
 781         struct genl_family *res = NULL;
 782         int err = -EINVAL;
 783
 784         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 785                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 786                 res = genl_family_find_byid(id);
 787                 err = -ENOENT;
 788         }
 789
 790         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 791                 char *name;
 792
 793                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 794                 res = genl_family_find_byname(name);
 795 #ifdef CONFIG_MODULES
 796                 if (res == NULL) {
 797                         genl_unlock();
 798                         request_module("net-pf-%d-proto-%d-type-%s",
 799                                        PF_NETLINK, NETLINK_GENERIC, name);
 800                         genl_lock();
 801                         res = genl_family_find_byname(name);
 802                 }
 803 #endif
 804                 err = -ENOENT;
 805         }
 806
 807         if (res == NULL)
 808                 return err;
 809
 810         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 811                 /* family doesn't exist here */
 812                 return -ENOENT;
 813         }
 814
 815         msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
 816                                     CTRL_CMD_NEWFAMILY);
 817         if (IS_ERR(msg))
 818                 return PTR_ERR(msg);
 819
 820         return genlmsg_reply(msg, info);
 821 }
 822
 823 static int genl_ctrl_event(int event, void *data)
 824 {
 825         struct sk_buff *msg;
 826         struct genl_family *family;
 827         struct genl_multicast_group *grp;
 828
 829         /* genl is still initialising */
 830         if (!init_net.genl_sock)
 831                 return 0;
 832
 833         switch (event) {
 834         case CTRL_CMD_NEWFAMILY:
 835         case CTRL_CMD_DELFAMILY:
 836                 family = data;
 837                 msg = ctrl_build_family_msg(family, 0, 0, event);
 838                 break;
 839         case CTRL_CMD_NEWMCAST_GRP:
 840         case CTRL_CMD_DELMCAST_GRP:
 841                 grp = data;
 842                 family = grp->family;
 843                 msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
 844                 break;
 845         default:
 846                 return -EINVAL;
 847         }
 848
 849         if (IS_ERR(msg))
 850                 return PTR_ERR(msg);
 851
 852         if (!family->netnsok) {
 853                 genlmsg_multicast_netns(&init_net, msg, 0,
 854                                         GENL_ID_CTRL, GFP_KERNEL);
 855         } else {
 856                 rcu_read_lock();
 857                 genlmsg_multicast_allns(msg, 0, GENL_ID_CTRL, GFP_ATOMIC);
 858                 rcu_read_unlock();
 859         }
 860
 861         return 0;
 862 }
 863
 864 static struct genl_ops genl_ctrl_ops = {
 865         .cmd            = CTRL_CMD_GETFAMILY,
 866         .doit           = ctrl_getfamily,
 867         .dumpit         = ctrl_dumpfamily,
 868         .policy         = ctrl_policy,
 869 };
 870
 871 static struct genl_multicast_group notify_grp = {
 872         .name           = "notify",
 873 };
 874
 875 static int __net_init genl_pernet_init(struct net *net)
 876 {
 877         /* we'll bump the group number right afterwards */
 878         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, 0,
 879                                                genl_rcv, &genl_mutex,
 880                                                THIS_MODULE);
 881
 882         if (!net->genl_sock && net_eq(net, &init_net))
 883                 panic("GENL: Cannot initialize generic netlink\n");
 884
 885         if (!net->genl_sock)
 886                 return -ENOMEM;
 887
 888         return 0;
 889 }
 890
 891 static void __net_exit genl_pernet_exit(struct net *net)
 892 {
 893         netlink_kernel_release(net->genl_sock);
 894         net->genl_sock = NULL;
 895 }
 896
 897 static struct pernet_operations genl_pernet_ops = {
 898         .init = genl_pernet_init,
 899         .exit = genl_pernet_exit,
 900 };
 901
 902 static int __init genl_init(void)
 903 {
 904         int i, err;
 905
 906         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 907                 INIT_LIST_HEAD(&family_ht[i]);
 908
 909         err = genl_register_family_with_ops(&genl_ctrl, &genl_ctrl_ops, 1);
 910         if (err < 0)
 911                 goto problem;
 912
 913         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
 914
 915         err = register_pernet_subsys(&genl_pernet_ops);
 916         if (err)
 917                 goto problem;
 918
 919         err = genl_register_mc_group(&genl_ctrl, &notify_grp);
 920         if (err < 0)
 921                 goto problem;
 922
 923         return 0;
 924
 925 problem:
 926         panic("GENL: Cannot register controller: %d\n", err);
 927 }
 928
 929 subsys_initcall(genl_init);
 930
 931 static int genlmsg_mcast(struct sk_buff *skb, u32 pid, unsigned long group,
 932                          gfp_t flags)
 933 {
 934         struct sk_buff *tmp;
 935         struct net *net, *prev = NULL;
 936         int err;
 937
 938         for_each_net_rcu(net) {
 939                 if (prev) {
 940                         tmp = skb_clone(skb, flags);
 941                         if (!tmp) {
 942                                 err = -ENOMEM;
 943                                 goto error;
 944                         }
 945                         err = nlmsg_multicast(prev->genl_sock, tmp,
 946                                               pid, group, flags);
 947                         if (err)
 948                                 goto error;
 949                 }
 950
 951                 prev = net;
 952         }
 953
 954         return nlmsg_multicast(prev->genl_sock, skb, pid, group, flags);
 955  error:
 956         kfree_skb(skb);
 957         return err;
 958 }
 959
 960 int genlmsg_multicast_allns(struct sk_buff *skb, u32 pid, unsigned int group,
 961                             gfp_t flags)
 962 {
 963         return genlmsg_mcast(skb, pid, group, flags);
 964 }
 965 EXPORT_SYMBOL(genlmsg_multicast_allns);
 966
 967 void genl_notify(struct sk_buff *skb, struct net *net, u32 pid, u32 group,
 968                  struct nlmsghdr *nlh, gfp_t flags)
 969 {
 970         struct sock *sk = net->genl_sock;
 971         int report = 0;
 972
 973         if (nlh)
 974                 report = nlmsg_report(nlh);
 975
 976         nlmsg_notify(sk, skb, pid, group, report, flags);
 977 }
 978 EXPORT_SYMBOL(genl_notify);