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