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