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