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         rcu_read_lock();
 224         for_each_net_rcu(net)
 225                 netlink_clear_multicast_users(net->genl_sock, grp->id);
 226         rcu_read_unlock();
 227
 228         clear_bit(grp->id, mc_groups);
 229         list_del(&grp->list);
 230         genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
 231         grp->id = 0;
 232         grp->family = NULL;
 233 }
 234
 235 /**
 236  * genl_unregister_mc_group - unregister a multicast group
 237  *
 238  * Unregisters the specified multicast group and notifies userspace
 239  * about it. All current listeners on the group are removed.
 240  *
 241  * Note: It is not necessary to unregister all multicast groups before
 242  *       unregistering the family, unregistering the family will cause
 243  *       all assigned multicast groups to be unregistered automatically.
 244  *
 245  * @family: Generic netlink family the group belongs to.
 246  * @grp: The group to unregister, must have been registered successfully
 247  *       previously.
 248  */
 249 void genl_unregister_mc_group(struct genl_family *family,
 250                               struct genl_multicast_group *grp)
 251 {
 252         genl_lock();
 253         __genl_unregister_mc_group(family, grp);
 254         genl_unlock();
 255 }
 256 EXPORT_SYMBOL(genl_unregister_mc_group);
 257
 258 static void genl_unregister_mc_groups(struct genl_family *family)
 259 {
 260         struct genl_multicast_group *grp, *tmp;
 261
 262         list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
 263                 __genl_unregister_mc_group(family, grp);
 264 }
 265
 266 /**
 267  * genl_register_ops - register generic netlink operations
 268  * @family: generic netlink family
 269  * @ops: operations to be registered
 270  *
 271  * Registers the specified operations and assigns them to the specified
 272  * family. Either a doit or dumpit callback must be specified or the
 273  * operation will fail. Only one operation structure per command
 274  * identifier may be registered.
 275  *
 276  * See include/net/genetlink.h for more documenation on the operations
 277  * structure.
 278  *
 279  * Returns 0 on success or a negative error code.
 280  */
 281 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
 282 {
 283         int err = -EINVAL;
 284
 285         if (ops->dumpit == NULL && ops->doit == NULL)
 286                 goto errout;
 287
 288         if (genl_get_cmd(ops->cmd, family)) {
 289                 err = -EEXIST;
 290                 goto errout;
 291         }
 292
 293         if (ops->dumpit)
 294                 ops->flags |= GENL_CMD_CAP_DUMP;
 295         if (ops->doit)
 296                 ops->flags |= GENL_CMD_CAP_DO;
 297         if (ops->policy)
 298                 ops->flags |= GENL_CMD_CAP_HASPOL;
 299
 300         genl_lock();
 301         list_add_tail(&ops->ops_list, &family->ops_list);
 302         genl_unlock();
 303
 304         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
 305         err = 0;
 306 errout:
 307         return err;
 308 }
 309
 310 /**
 311  * genl_unregister_ops - unregister generic netlink operations
 312  * @family: generic netlink family
 313  * @ops: operations to be unregistered
 314  *
 315  * Unregisters the specified operations and unassigns them from the
 316  * specified family. The operation blocks until the current message
 317  * processing has finished and doesn't start again until the
 318  * unregister process has finished.
 319  *
 320  * Note: It is not necessary to unregister all operations before
 321  *       unregistering the family, unregistering the family will cause
 322  *       all assigned operations to be unregistered automatically.
 323  *
 324  * Returns 0 on success or a negative error code.
 325  */
 326 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
 327 {
 328         struct genl_ops *rc;
 329
 330         genl_lock();
 331         list_for_each_entry(rc, &family->ops_list, ops_list) {
 332                 if (rc == ops) {
 333                         list_del(&ops->ops_list);
 334                         genl_unlock();
 335                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
 336                         return 0;
 337                 }
 338         }
 339         genl_unlock();
 340
 341         return -ENOENT;
 342 }
 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 (genl_family_find_byid(family->id)) {
 376                 err = -EEXIST;
 377                 goto errout_locked;
 378         }
 379
 380         if (family->id == GENL_ID_GENERATE) {
 381                 u16 newid = genl_generate_id();
 382
 383                 if (!newid) {
 384                         err = -ENOMEM;
 385                         goto errout_locked;
 386                 }
 387
 388                 family->id = newid;
 389         }
 390
 391         if (family->maxattr) {
 392                 family->attrbuf = kmalloc((family->maxattr+1) *
 393                                         sizeof(struct nlattr *), GFP_KERNEL);
 394                 if (family->attrbuf == NULL) {
 395                         err = -ENOMEM;
 396                         goto errout_locked;
 397                 }
 398         } else
 399                 family->attrbuf = NULL;
 400
 401         list_add_tail(&family->family_list, genl_family_chain(family->id));
 402         genl_unlock();
 403
 404         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
 405
 406         return 0;
 407
 408 errout_locked:
 409         genl_unlock();
 410 errout:
 411         return err;
 412 }
 413
 414 /**
 415  * genl_register_family_with_ops - register a generic netlink family
 416  * @family: generic netlink family
 417  * @ops: operations to be registered
 418  * @n_ops: number of elements to register
 419  *
 420  * Registers the specified family and operations from the specified table.
 421  * Only one family may be registered with the same family name or identifier.
 422  *
 423  * The family id may equal GENL_ID_GENERATE causing an unique id to
 424  * be automatically generated and assigned.
 425  *
 426  * Either a doit or dumpit callback must be specified for every registered
 427  * operation or the function will fail. Only one operation structure per
 428  * command identifier may be registered.
 429  *
 430  * See include/net/genetlink.h for more documenation on the operations
 431  * structure.
 432  *
 433  * This is equivalent to calling genl_register_family() followed by
 434  * genl_register_ops() for every operation entry in the table taking
 435  * care to unregister the family on error path.
 436  *
 437  * Return 0 on success or a negative error code.
 438  */
 439 int genl_register_family_with_ops(struct genl_family *family,
 440         struct genl_ops *ops, size_t n_ops)
 441 {
 442         int err, i;
 443
 444         err = genl_register_family(family);
 445         if (err)
 446                 return err;
 447
 448         for (i = 0; i < n_ops; ++i, ++ops) {
 449                 err = genl_register_ops(family, ops);
 450                 if (err)
 451                         goto err_out;
 452         }
 453         return 0;
 454 err_out:
 455         genl_unregister_family(family);
 456         return err;
 457 }
 458 EXPORT_SYMBOL(genl_register_family_with_ops);
 459
 460 /**
 461  * genl_unregister_family - unregister generic netlink family
 462  * @family: generic netlink family
 463  *
 464  * Unregisters the specified family.
 465  *
 466  * Returns 0 on success or a negative error code.
 467  */
 468 int genl_unregister_family(struct genl_family *family)
 469 {
 470         struct genl_family *rc;
 471
 472         genl_lock();
 473
 474         genl_unregister_mc_groups(family);
 475
 476         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 477                 if (family->id != rc->id || strcmp(rc->name, family->name))
 478                         continue;
 479
 480                 list_del(&rc->family_list);
 481                 INIT_LIST_HEAD(&family->ops_list);
 482                 genl_unlock();
 483
 484                 kfree(family->attrbuf);
 485                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
 486                 return 0;
 487         }
 488
 489         genl_unlock();
 490
 491         return -ENOENT;
 492 }
 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);
 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
 552         return ops->doit(skb, &info);
 553 }
 554
 555 static void genl_rcv(struct sk_buff *skb)
 556 {
 557         genl_lock();
 558         netlink_rcv_skb(skb, &genl_rcv_msg);
 559         genl_unlock();
 560 }
 561
 562 /**************************************************************************
 563  * Controller
 564  **************************************************************************/
 565
 566 static struct genl_family genl_ctrl = {
 567         .id = GENL_ID_CTRL,
 568         .name = "nlctrl",
 569         .version = 0x2,
 570         .maxattr = CTRL_ATTR_MAX,
 571         .netnsok = true,
 572 };
 573
 574 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
 575                           u32 flags, struct sk_buff *skb, u8 cmd)
 576 {
 577         void *hdr;
 578
 579         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 580         if (hdr == NULL)
 581                 return -1;
 582
 583         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
 584         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
 585         NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
 586         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
 587         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
 588
 589         if (!list_empty(&family->ops_list)) {
 590                 struct nlattr *nla_ops;
 591                 struct genl_ops *ops;
 592                 int idx = 1;
 593
 594                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 595                 if (nla_ops == NULL)
 596                         goto nla_put_failure;
 597
 598                 list_for_each_entry(ops, &family->ops_list, ops_list) {
 599                         struct nlattr *nest;
 600
 601                         nest = nla_nest_start(skb, idx++);
 602                         if (nest == NULL)
 603                                 goto nla_put_failure;
 604
 605                         NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
 606                         NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
 607
 608                         nla_nest_end(skb, nest);
 609                 }
 610
 611                 nla_nest_end(skb, nla_ops);
 612         }
 613
 614         if (!list_empty(&family->mcast_groups)) {
 615                 struct genl_multicast_group *grp;
 616                 struct nlattr *nla_grps;
 617                 int idx = 1;
 618
 619                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 620                 if (nla_grps == NULL)
 621                         goto nla_put_failure;
 622
 623                 list_for_each_entry(grp, &family->mcast_groups, list) {
 624                         struct nlattr *nest;
 625
 626                         nest = nla_nest_start(skb, idx++);
 627                         if (nest == NULL)
 628                                 goto nla_put_failure;
 629
 630                         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 631                         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 632                                        grp->name);
 633
 634                         nla_nest_end(skb, nest);
 635                 }
 636                 nla_nest_end(skb, nla_grps);
 637         }
 638
 639         return genlmsg_end(skb, hdr);
 640
 641 nla_put_failure:
 642         genlmsg_cancel(skb, hdr);
 643         return -EMSGSIZE;
 644 }
 645
 646 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
 647                                 u32 seq, u32 flags, struct sk_buff *skb,
 648                                 u8 cmd)
 649 {
 650         void *hdr;
 651         struct nlattr *nla_grps;
 652         struct nlattr *nest;
 653
 654         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 655         if (hdr == NULL)
 656                 return -1;
 657
 658         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
 659         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
 660
 661         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 662         if (nla_grps == NULL)
 663                 goto nla_put_failure;
 664
 665         nest = nla_nest_start(skb, 1);
 666         if (nest == NULL)
 667                 goto nla_put_failure;
 668
 669         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 670         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 671                        grp->name);
 672
 673         nla_nest_end(skb, nest);
 674         nla_nest_end(skb, nla_grps);
 675
 676         return genlmsg_end(skb, hdr);
 677
 678 nla_put_failure:
 679         genlmsg_cancel(skb, hdr);
 680         return -EMSGSIZE;
 681 }
 682
 683 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 684 {
 685
 686         int i, n = 0;
 687         struct genl_family *rt;
 688         struct net *net = sock_net(skb->sk);
 689         int chains_to_skip = cb->args[0];
 690         int fams_to_skip = cb->args[1];
 691
 692         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
 693                 if (i < chains_to_skip)
 694                         continue;
 695                 n = 0;
 696                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 697                         if (!rt->netnsok && !net_eq(net, &init_net))
 698                                 continue;
 699                         if (++n < fams_to_skip)
 700                                 continue;
 701                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
 702                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 703                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 704                                 goto errout;
 705                 }
 706
 707                 fams_to_skip = 0;
 708         }
 709
 710 errout:
 711         cb->args[0] = i;
 712         cb->args[1] = n;
 713
 714         return skb->len;
 715 }
 716
 717 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 718                                              u32 pid, int seq, u8 cmd)
 719 {
 720         struct sk_buff *skb;
 721         int err;
 722
 723         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 724         if (skb == NULL)
 725                 return ERR_PTR(-ENOBUFS);
 726
 727         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
 728         if (err < 0) {
 729                 nlmsg_free(skb);
 730                 return ERR_PTR(err);
 731         }
 732
 733         return skb;
 734 }
 735
 736 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
 737                                             u32 pid, int seq, u8 cmd)
 738 {
 739         struct sk_buff *skb;
 740         int err;
 741
 742         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 743         if (skb == NULL)
 744                 return ERR_PTR(-ENOBUFS);
 745
 746         err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
 747         if (err < 0) {
 748                 nlmsg_free(skb);
 749                 return ERR_PTR(err);
 750         }
 751
 752         return skb;
 753 }
 754
 755 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 756         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 757         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 758                                     .len = GENL_NAMSIZ - 1 },
 759 };
 760
 761 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 762 {
 763         struct sk_buff *msg;
 764         struct genl_family *res = NULL;
 765         int err = -EINVAL;
 766
 767         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 768                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 769                 res = genl_family_find_byid(id);
 770                 err = -ENOENT;
 771         }
 772
 773         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 774                 char *name;
 775
 776                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 777                 res = genl_family_find_byname(name);
 778                 err = -ENOENT;
 779         }
 780
 781         if (res == NULL)
 782                 return err;
 783
 784         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 785                 /* family doesn't exist here */
 786                 return -ENOENT;
 787         }
 788
 789         msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
 790                                     CTRL_CMD_NEWFAMILY);
 791         if (IS_ERR(msg))
 792                 return PTR_ERR(msg);
 793
 794         return genlmsg_reply(msg, info);
 795 }
 796
 797 static int genl_ctrl_event(int event, void *data)
 798 {
 799         struct sk_buff *msg;
 800         struct genl_family *family;
 801         struct genl_multicast_group *grp;
 802
 803         /* genl is still initialising */
 804         if (!init_net.genl_sock)
 805                 return 0;
 806
 807         switch (event) {
 808         case CTRL_CMD_NEWFAMILY:
 809         case CTRL_CMD_DELFAMILY:
 810                 family = data;
 811                 msg = ctrl_build_family_msg(family, 0, 0, event);
 812                 break;
 813         case CTRL_CMD_NEWMCAST_GRP:
 814         case CTRL_CMD_DELMCAST_GRP:
 815                 grp = data;
 816                 family = grp->family;
 817                 msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
 818                 break;
 819         default:
 820                 return -EINVAL;
 821         }
 822
 823         if (IS_ERR(msg))
 824                 return PTR_ERR(msg);
 825
 826         if (!family->netnsok) {
 827                 genlmsg_multicast_netns(&init_net, msg, 0,
 828                                         GENL_ID_CTRL, GFP_KERNEL);
 829         } else {
 830                 rcu_read_lock();
 831                 genlmsg_multicast_allns(msg, 0, GENL_ID_CTRL, GFP_ATOMIC);
 832                 rcu_read_unlock();
 833         }
 834
 835         return 0;
 836 }
 837
 838 static struct genl_ops genl_ctrl_ops = {
 839         .cmd            = CTRL_CMD_GETFAMILY,
 840         .doit           = ctrl_getfamily,
 841         .dumpit         = ctrl_dumpfamily,
 842         .policy         = ctrl_policy,
 843 };
 844
 845 static struct genl_multicast_group notify_grp = {
 846         .name           = "notify",
 847 };
 848
 849 static int __net_init genl_pernet_init(struct net *net)
 850 {
 851         /* we'll bump the group number right afterwards */
 852         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, 0,
 853                                                genl_rcv, &genl_mutex,
 854                                                THIS_MODULE);
 855
 856         if (!net->genl_sock && net_eq(net, &init_net))
 857                 panic("GENL: Cannot initialize generic netlink\n");
 858
 859         if (!net->genl_sock)
 860                 return -ENOMEM;
 861
 862         return 0;
 863 }
 864
 865 static void __net_exit genl_pernet_exit(struct net *net)
 866 {
 867         netlink_kernel_release(net->genl_sock);
 868         net->genl_sock = NULL;
 869 }
 870
 871 static struct pernet_operations genl_pernet_ops = {
 872         .init = genl_pernet_init,
 873         .exit = genl_pernet_exit,
 874 };
 875
 876 static int __init genl_init(void)
 877 {
 878         int i, err;
 879
 880         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 881                 INIT_LIST_HEAD(&family_ht[i]);
 882
 883         err = genl_register_family(&genl_ctrl);
 884         if (err < 0)
 885                 goto problem;
 886
 887         err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
 888         if (err < 0)
 889                 goto problem;
 890
 891         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
 892
 893         err = register_pernet_subsys(&genl_pernet_ops);
 894         if (err)
 895                 goto problem;
 896
 897         err = genl_register_mc_group(&genl_ctrl, &notify_grp);
 898         if (err < 0)
 899                 goto problem;
 900
 901         return 0;
 902
 903 problem:
 904         panic("GENL: Cannot register controller: %d\n", err);
 905 }
 906
 907 subsys_initcall(genl_init);
 908
 909 EXPORT_SYMBOL(genl_register_ops);
 910 EXPORT_SYMBOL(genl_unregister_ops);
 911 EXPORT_SYMBOL(genl_register_family);
 912 EXPORT_SYMBOL(genl_unregister_family);
 913
 914 static int genlmsg_mcast(struct sk_buff *skb, u32 pid, unsigned long group,
 915                          gfp_t flags)
 916 {
 917         struct sk_buff *tmp;
 918         struct net *net, *prev = NULL;
 919         int err;
 920
 921         for_each_net_rcu(net) {
 922                 if (prev) {
 923                         tmp = skb_clone(skb, flags);
 924                         if (!tmp) {
 925                                 err = -ENOMEM;
 926                                 goto error;
 927                         }
 928                         err = nlmsg_multicast(prev->genl_sock, tmp,
 929                                               pid, group, flags);
 930                         if (err)
 931                                 goto error;
 932                 }
 933
 934                 prev = net;
 935         }
 936
 937         return nlmsg_multicast(prev->genl_sock, skb, pid, group, flags);
 938  error:
 939         kfree_skb(skb);
 940         return err;
 941 }
 942
 943 int genlmsg_multicast_allns(struct sk_buff *skb, u32 pid, unsigned int group,
 944                             gfp_t flags)
 945 {
 946         return genlmsg_mcast(skb, pid, group, flags);
 947 }
 948 EXPORT_SYMBOL(genlmsg_multicast_allns);