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