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 = GENL_MIN_ID;
 101         int i;
 102
 103         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 104                 if (!genl_family_find_byid(id_gen_idx))
 105                         return id_gen_idx;
 106                 if (++id_gen_idx > GENL_MAX_ID)
 107                         id_gen_idx = GENL_MIN_ID;
 108         }
 109
 110         return 0;
 111 }
 112
 113 static struct genl_multicast_group notify_grp;
 114
 115 /**
 116  * genl_register_mc_group - register a multicast group
 117  *
 118  * Registers the specified multicast group and notifies userspace
 119  * about the new group.
 120  *
 121  * Returns 0 on success or a negative error code.
 122  *
 123  * @family: The generic netlink family the group shall be registered for.
 124  * @grp: The group to register, must have a name.
 125  */
 126 int genl_register_mc_group(struct genl_family *family,
 127                            struct genl_multicast_group *grp)
 128 {
 129         int id;
 130         unsigned long *new_groups;
 131         int err = 0;
 132
 133         BUG_ON(grp->name[0] == '\0');
 134
 135         genl_lock();
 136
 137         /* special-case our own group */
 138         if (grp == &notify_grp)
 139                 id = GENL_ID_CTRL;
 140         else
 141                 id = find_first_zero_bit(mc_groups,
 142                                          mc_groups_longs * BITS_PER_LONG);
 143
 144
 145         if (id >= mc_groups_longs * BITS_PER_LONG) {
 146                 size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
 147
 148                 if (mc_groups == &mc_group_start) {
 149                         new_groups = kzalloc(nlen, GFP_KERNEL);
 150                         if (!new_groups) {
 151                                 err = -ENOMEM;
 152                                 goto out;
 153                         }
 154                         mc_groups = new_groups;
 155                         *mc_groups = mc_group_start;
 156                 } else {
 157                         new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
 158                         if (!new_groups) {
 159                                 err = -ENOMEM;
 160                                 goto out;
 161                         }
 162                         mc_groups = new_groups;
 163                         mc_groups[mc_groups_longs] = 0;
 164                 }
 165                 mc_groups_longs++;
 166         }
 167
 168         if (family->netnsok) {
 169                 struct net *net;
 170
 171                 netlink_table_grab();
 172                 rcu_read_lock();
 173                 for_each_net_rcu(net) {
 174                         err = __netlink_change_ngroups(net->genl_sock,
 175                                         mc_groups_longs * BITS_PER_LONG);
 176                         if (err) {
 177                                 /*
 178                                  * No need to roll back, can only fail if
 179                                  * memory allocation fails and then the
 180                                  * number of _possible_ groups has been
 181                                  * increased on some sockets which is ok.
 182                                  */
 183                                 rcu_read_unlock();
 184                                 netlink_table_ungrab();
 185                                 goto out;
 186                         }
 187                 }
 188                 rcu_read_unlock();
 189                 netlink_table_ungrab();
 190         } else {
 191                 err = netlink_change_ngroups(init_net.genl_sock,
 192                                              mc_groups_longs * BITS_PER_LONG);
 193                 if (err)
 194                         goto out;
 195         }
 196
 197         grp->id = id;
 198         set_bit(id, mc_groups);
 199         list_add_tail(&grp->list, &family->mcast_groups);
 200         grp->family = family;
 201
 202         genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
 203  out:
 204         genl_unlock();
 205         return err;
 206 }
 207 EXPORT_SYMBOL(genl_register_mc_group);
 208
 209 static void __genl_unregister_mc_group(struct genl_family *family,
 210                                        struct genl_multicast_group *grp)
 211 {
 212         struct net *net;
 213         BUG_ON(grp->family != family);
 214
 215         netlink_table_grab();
 216         rcu_read_lock();
 217         for_each_net_rcu(net)
 218                 __netlink_clear_multicast_users(net->genl_sock, grp->id);
 219         rcu_read_unlock();
 220         netlink_table_ungrab();
 221
 222         clear_bit(grp->id, mc_groups);
 223         list_del(&grp->list);
 224         genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
 225         grp->id = 0;
 226         grp->family = NULL;
 227 }
 228
 229 /**
 230  * genl_unregister_mc_group - unregister a multicast group
 231  *
 232  * Unregisters the specified multicast group and notifies userspace
 233  * about it. All current listeners on the group are removed.
 234  *
 235  * Note: It is not necessary to unregister all multicast groups before
 236  *       unregistering the family, unregistering the family will cause
 237  *       all assigned multicast groups to be unregistered automatically.
 238  *
 239  * @family: Generic netlink family the group belongs to.
 240  * @grp: The group to unregister, must have been registered successfully
 241  *       previously.
 242  */
 243 void genl_unregister_mc_group(struct genl_family *family,
 244                               struct genl_multicast_group *grp)
 245 {
 246         genl_lock();
 247         __genl_unregister_mc_group(family, grp);
 248         genl_unlock();
 249 }
 250 EXPORT_SYMBOL(genl_unregister_mc_group);
 251
 252 static void genl_unregister_mc_groups(struct genl_family *family)
 253 {
 254         struct genl_multicast_group *grp, *tmp;
 255
 256         list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
 257                 __genl_unregister_mc_group(family, grp);
 258 }
 259
 260 /**
 261  * genl_register_ops - register generic netlink operations
 262  * @family: generic netlink family
 263  * @ops: operations to be registered
 264  *
 265  * Registers the specified operations and assigns them to the specified
 266  * family. Either a doit or dumpit callback must be specified or the
 267  * operation will fail. Only one operation structure per command
 268  * identifier may be registered.
 269  *
 270  * See include/net/genetlink.h for more documenation on the operations
 271  * structure.
 272  *
 273  * Returns 0 on success or a negative error code.
 274  */
 275 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
 276 {
 277         int err = -EINVAL;
 278
 279         if (ops->dumpit == NULL && ops->doit == NULL)
 280                 goto errout;
 281
 282         if (genl_get_cmd(ops->cmd, family)) {
 283                 err = -EEXIST;
 284                 goto errout;
 285         }
 286
 287         if (ops->dumpit)
 288                 ops->flags |= GENL_CMD_CAP_DUMP;
 289         if (ops->doit)
 290                 ops->flags |= GENL_CMD_CAP_DO;
 291         if (ops->policy)
 292                 ops->flags |= GENL_CMD_CAP_HASPOL;
 293
 294         genl_lock();
 295         list_add_tail(&ops->ops_list, &family->ops_list);
 296         genl_unlock();
 297
 298         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
 299         err = 0;
 300 errout:
 301         return err;
 302 }
 303
 304 /**
 305  * genl_unregister_ops - unregister generic netlink operations
 306  * @family: generic netlink family
 307  * @ops: operations to be unregistered
 308  *
 309  * Unregisters the specified operations and unassigns them from the
 310  * specified family. The operation blocks until the current message
 311  * processing has finished and doesn't start again until the
 312  * unregister process has finished.
 313  *
 314  * Note: It is not necessary to unregister all operations before
 315  *       unregistering the family, unregistering the family will cause
 316  *       all assigned operations to be unregistered automatically.
 317  *
 318  * Returns 0 on success or a negative error code.
 319  */
 320 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
 321 {
 322         struct genl_ops *rc;
 323
 324         genl_lock();
 325         list_for_each_entry(rc, &family->ops_list, ops_list) {
 326                 if (rc == ops) {
 327                         list_del(&ops->ops_list);
 328                         genl_unlock();
 329                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
 330                         return 0;
 331                 }
 332         }
 333         genl_unlock();
 334
 335         return -ENOENT;
 336 }
 337
 338 /**
 339  * genl_register_family - register a generic netlink family
 340  * @family: generic netlink family
 341  *
 342  * Registers the specified family after validating it first. Only one
 343  * family may be registered with the same family name or identifier.
 344  * The family id may equal GENL_ID_GENERATE causing an unique id to
 345  * be automatically generated and assigned.
 346  *
 347  * Return 0 on success or a negative error code.
 348  */
 349 int genl_register_family(struct genl_family *family)
 350 {
 351         int err = -EINVAL;
 352
 353         if (family->id && family->id < GENL_MIN_ID)
 354                 goto errout;
 355
 356         if (family->id > GENL_MAX_ID)
 357                 goto errout;
 358
 359         INIT_LIST_HEAD(&family->ops_list);
 360         INIT_LIST_HEAD(&family->mcast_groups);
 361
 362         genl_lock();
 363
 364         if (genl_family_find_byname(family->name)) {
 365                 err = -EEXIST;
 366                 goto errout_locked;
 367         }
 368
 369         if (family->id == GENL_ID_GENERATE) {
 370                 u16 newid = genl_generate_id();
 371
 372                 if (!newid) {
 373                         err = -ENOMEM;
 374                         goto errout_locked;
 375                 }
 376
 377                 family->id = newid;
 378         } else if (genl_family_find_byid(family->id)) {
 379                 err = -EEXIST;
 380                 goto errout_locked;
 381         }
 382
 383         if (family->maxattr) {
 384                 family->attrbuf = kmalloc((family->maxattr+1) *
 385                                         sizeof(struct nlattr *), GFP_KERNEL);
 386                 if (family->attrbuf == NULL) {
 387                         err = -ENOMEM;
 388                         goto errout_locked;
 389                 }
 390         } else
 391                 family->attrbuf = NULL;
 392
 393         list_add_tail(&family->family_list, genl_family_chain(family->id));
 394         genl_unlock();
 395
 396         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
 397
 398         return 0;
 399
 400 errout_locked:
 401         genl_unlock();
 402 errout:
 403         return err;
 404 }
 405
 406 /**
 407  * genl_register_family_with_ops - register a generic netlink family
 408  * @family: generic netlink family
 409  * @ops: operations to be registered
 410  * @n_ops: number of elements to register
 411  *
 412  * Registers the specified family and operations from the specified table.
 413  * Only one family may be registered with the same family name or identifier.
 414  *
 415  * The family id may equal GENL_ID_GENERATE causing an unique id to
 416  * be automatically generated and assigned.
 417  *
 418  * Either a doit or dumpit callback must be specified for every registered
 419  * operation or the function will fail. Only one operation structure per
 420  * command identifier may be registered.
 421  *
 422  * See include/net/genetlink.h for more documenation on the operations
 423  * structure.
 424  *
 425  * This is equivalent to calling genl_register_family() followed by
 426  * genl_register_ops() for every operation entry in the table taking
 427  * care to unregister the family on error path.
 428  *
 429  * Return 0 on success or a negative error code.
 430  */
 431 int genl_register_family_with_ops(struct genl_family *family,
 432         struct genl_ops *ops, size_t n_ops)
 433 {
 434         int err, i;
 435
 436         err = genl_register_family(family);
 437         if (err)
 438                 return err;
 439
 440         for (i = 0; i < n_ops; ++i, ++ops) {
 441                 err = genl_register_ops(family, ops);
 442                 if (err)
 443                         goto err_out;
 444         }
 445         return 0;
 446 err_out:
 447         genl_unregister_family(family);
 448         return err;
 449 }
 450 EXPORT_SYMBOL(genl_register_family_with_ops);
 451
 452 /**
 453  * genl_unregister_family - unregister generic netlink family
 454  * @family: generic netlink family
 455  *
 456  * Unregisters the specified family.
 457  *
 458  * Returns 0 on success or a negative error code.
 459  */
 460 int genl_unregister_family(struct genl_family *family)
 461 {
 462         struct genl_family *rc;
 463
 464         genl_lock();
 465
 466         genl_unregister_mc_groups(family);
 467
 468         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 469                 if (family->id != rc->id || strcmp(rc->name, family->name))
 470                         continue;
 471
 472                 list_del(&rc->family_list);
 473                 INIT_LIST_HEAD(&family->ops_list);
 474                 genl_unlock();
 475
 476                 kfree(family->attrbuf);
 477                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
 478                 return 0;
 479         }
 480
 481         genl_unlock();
 482
 483         return -ENOENT;
 484 }
 485
 486 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 487 {
 488         struct genl_ops *ops;
 489         struct genl_family *family;
 490         struct net *net = sock_net(skb->sk);
 491         struct genl_info info;
 492         struct genlmsghdr *hdr = nlmsg_data(nlh);
 493         int hdrlen, err;
 494
 495         family = genl_family_find_byid(nlh->nlmsg_type);
 496         if (family == NULL)
 497                 return -ENOENT;
 498
 499         /* this family doesn't exist in this netns */
 500         if (!family->netnsok && !net_eq(net, &init_net))
 501                 return -ENOENT;
 502
 503         hdrlen = GENL_HDRLEN + family->hdrsize;
 504         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 505                 return -EINVAL;
 506
 507         ops = genl_get_cmd(hdr->cmd, family);
 508         if (ops == NULL)
 509                 return -EOPNOTSUPP;
 510
 511         if ((ops->flags & GENL_ADMIN_PERM) &&
 512             security_netlink_recv(skb, CAP_NET_ADMIN))
 513                 return -EPERM;
 514
 515         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 516                 if (ops->dumpit == NULL)
 517                         return -EOPNOTSUPP;
 518
 519                 genl_unlock();
 520                 err = netlink_dump_start(net->genl_sock, skb, nlh,
 521                                          ops->dumpit, ops->done);
 522                 genl_lock();
 523                 return err;
 524         }
 525
 526         if (ops->doit == NULL)
 527                 return -EOPNOTSUPP;
 528
 529         if (family->attrbuf) {
 530                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
 531                                   ops->policy);
 532                 if (err < 0)
 533                         return err;
 534         }
 535
 536         info.snd_seq = nlh->nlmsg_seq;
 537         info.snd_pid = NETLINK_CB(skb).pid;
 538         info.nlhdr = nlh;
 539         info.genlhdr = nlmsg_data(nlh);
 540         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 541         info.attrs = family->attrbuf;
 542         genl_info_net_set(&info, net);
 543
 544         return ops->doit(skb, &info);
 545 }
 546
 547 static void genl_rcv(struct sk_buff *skb)
 548 {
 549         genl_lock();
 550         netlink_rcv_skb(skb, &genl_rcv_msg);
 551         genl_unlock();
 552 }
 553
 554 /**************************************************************************
 555  * Controller
 556  **************************************************************************/
 557
 558 static struct genl_family genl_ctrl = {
 559         .id = GENL_ID_CTRL,
 560         .name = "nlctrl",
 561         .version = 0x2,
 562         .maxattr = CTRL_ATTR_MAX,
 563         .netnsok = true,
 564 };
 565
 566 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
 567                           u32 flags, struct sk_buff *skb, u8 cmd)
 568 {
 569         void *hdr;
 570
 571         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 572         if (hdr == NULL)
 573                 return -1;
 574
 575         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
 576         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
 577         NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
 578         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
 579         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
 580
 581         if (!list_empty(&family->ops_list)) {
 582                 struct nlattr *nla_ops;
 583                 struct genl_ops *ops;
 584                 int idx = 1;
 585
 586                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 587                 if (nla_ops == NULL)
 588                         goto nla_put_failure;
 589
 590                 list_for_each_entry(ops, &family->ops_list, ops_list) {
 591                         struct nlattr *nest;
 592
 593                         nest = nla_nest_start(skb, idx++);
 594                         if (nest == NULL)
 595                                 goto nla_put_failure;
 596
 597                         NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
 598                         NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
 599
 600                         nla_nest_end(skb, nest);
 601                 }
 602
 603                 nla_nest_end(skb, nla_ops);
 604         }
 605
 606         if (!list_empty(&family->mcast_groups)) {
 607                 struct genl_multicast_group *grp;
 608                 struct nlattr *nla_grps;
 609                 int idx = 1;
 610
 611                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 612                 if (nla_grps == NULL)
 613                         goto nla_put_failure;
 614
 615                 list_for_each_entry(grp, &family->mcast_groups, list) {
 616                         struct nlattr *nest;
 617
 618                         nest = nla_nest_start(skb, idx++);
 619                         if (nest == NULL)
 620                                 goto nla_put_failure;
 621
 622                         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 623                         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 624                                        grp->name);
 625
 626                         nla_nest_end(skb, nest);
 627                 }
 628                 nla_nest_end(skb, nla_grps);
 629         }
 630
 631         return genlmsg_end(skb, hdr);
 632
 633 nla_put_failure:
 634         genlmsg_cancel(skb, hdr);
 635         return -EMSGSIZE;
 636 }
 637
 638 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
 639                                 u32 seq, u32 flags, struct sk_buff *skb,
 640                                 u8 cmd)
 641 {
 642         void *hdr;
 643         struct nlattr *nla_grps;
 644         struct nlattr *nest;
 645
 646         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 647         if (hdr == NULL)
 648                 return -1;
 649
 650         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
 651         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
 652
 653         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 654         if (nla_grps == NULL)
 655                 goto nla_put_failure;
 656
 657         nest = nla_nest_start(skb, 1);
 658         if (nest == NULL)
 659                 goto nla_put_failure;
 660
 661         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 662         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 663                        grp->name);
 664
 665         nla_nest_end(skb, nest);
 666         nla_nest_end(skb, nla_grps);
 667
 668         return genlmsg_end(skb, hdr);
 669
 670 nla_put_failure:
 671         genlmsg_cancel(skb, hdr);
 672         return -EMSGSIZE;
 673 }
 674
 675 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 676 {
 677
 678         int i, n = 0;
 679         struct genl_family *rt;
 680         struct net *net = sock_net(skb->sk);
 681         int chains_to_skip = cb->args[0];
 682         int fams_to_skip = cb->args[1];
 683
 684         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
 685                 if (i < chains_to_skip)
 686                         continue;
 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);