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/slab.h>
  12 #include <linux/errno.h>
  13 #include <linux/types.h>
  14 #include <linux/socket.h>
  15 #include <linux/string.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/mutex.h>
  18 #include <linux/bitmap.h>
  19 #include <net/sock.h>
  20 #include <net/genetlink.h>
  21
  22 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
  23
  24 void genl_lock(void)
  25 {
  26         mutex_lock(&genl_mutex);
  27 }
  28 EXPORT_SYMBOL(genl_lock);
  29
  30 void genl_unlock(void)
  31 {
  32         mutex_unlock(&genl_mutex);
  33 }
  34 EXPORT_SYMBOL(genl_unlock);
  35
  36 #define GENL_FAM_TAB_SIZE       16
  37 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
  38
  39 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
  40 /*
  41  * Bitmap of multicast groups that are currently in use.
  42  *
  43  * To avoid an allocation at boot of just one unsigned long,
  44  * declare it global instead.
  45  * Bit 0 is marked as already used since group 0 is invalid.
  46  */
  47 static unsigned long mc_group_start = 0x1;
  48 static unsigned long *mc_groups = &mc_group_start;
  49 static unsigned long mc_groups_longs = 1;
  50
  51 static int genl_ctrl_event(int event, void *data);
  52
  53 static inline unsigned int genl_family_hash(unsigned int id)
  54 {
  55         return id & GENL_FAM_TAB_MASK;
  56 }
  57
  58 static inline struct list_head *genl_family_chain(unsigned int id)
  59 {
  60         return &family_ht[genl_family_hash(id)];
  61 }
  62
  63 static struct genl_family *genl_family_find_byid(unsigned int id)
  64 {
  65         struct genl_family *f;
  66
  67         list_for_each_entry(f, genl_family_chain(id), family_list)
  68                 if (f->id == id)
  69                         return f;
  70
  71         return NULL;
  72 }
  73
  74 static struct genl_family *genl_family_find_byname(char *name)
  75 {
  76         struct genl_family *f;
  77         int i;
  78
  79         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
  80                 list_for_each_entry(f, genl_family_chain(i), family_list)
  81                         if (strcmp(f->name, name) == 0)
  82                                 return f;
  83
  84         return NULL;
  85 }
  86
  87 static struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
  88 {
  89         struct genl_ops *ops;
  90
  91         list_for_each_entry(ops, &family->ops_list, ops_list)
  92                 if (ops->cmd == cmd)
  93                         return ops;
  94
  95         return NULL;
  96 }
  97
  98 /* Of course we are going to have problems once we hit
  99  * 2^16 alive types, but that can only happen by year 2K
 100 */
 101 static inline u16 genl_generate_id(void)
 102 {
 103         static u16 id_gen_idx = GENL_MIN_ID;
 104         int i;
 105
 106         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 107                 if (!genl_family_find_byid(id_gen_idx))
 108                         return id_gen_idx;
 109                 if (++id_gen_idx > GENL_MAX_ID)
 110                         id_gen_idx = GENL_MIN_ID;
 111         }
 112
 113         return 0;
 114 }
 115
 116 static struct genl_multicast_group notify_grp;
 117
 118 /**
 119  * genl_register_mc_group - register a multicast group
 120  *
 121  * Registers the specified multicast group and notifies userspace
 122  * about the new group.
 123  *
 124  * Returns 0 on success or a negative error code.
 125  *
 126  * @family: The generic netlink family the group shall be registered for.
 127  * @grp: The group to register, must have a name.
 128  */
 129 int genl_register_mc_group(struct genl_family *family,
 130                            struct genl_multicast_group *grp)
 131 {
 132         int id;
 133         unsigned long *new_groups;
 134         int err = 0;
 135
 136         BUG_ON(grp->name[0] == '\0');
 137
 138         genl_lock();
 139
 140         /* special-case our own group */
 141         if (grp == &notify_grp)
 142                 id = GENL_ID_CTRL;
 143         else
 144                 id = find_first_zero_bit(mc_groups,
 145                                          mc_groups_longs * BITS_PER_LONG);
 146
 147
 148         if (id >= mc_groups_longs * BITS_PER_LONG) {
 149                 size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
 150
 151                 if (mc_groups == &mc_group_start) {
 152                         new_groups = kzalloc(nlen, GFP_KERNEL);
 153                         if (!new_groups) {
 154                                 err = -ENOMEM;
 155                                 goto out;
 156                         }
 157                         mc_groups = new_groups;
 158                         *mc_groups = mc_group_start;
 159                 } else {
 160                         new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
 161                         if (!new_groups) {
 162                                 err = -ENOMEM;
 163                                 goto out;
 164                         }
 165                         mc_groups = new_groups;
 166                         mc_groups[mc_groups_longs] = 0;
 167                 }
 168                 mc_groups_longs++;
 169         }
 170
 171         if (family->netnsok) {
 172                 struct net *net;
 173
 174                 netlink_table_grab();
 175                 rcu_read_lock();
 176                 for_each_net_rcu(net) {
 177                         err = __netlink_change_ngroups(net->genl_sock,
 178                                         mc_groups_longs * BITS_PER_LONG);
 179                         if (err) {
 180                                 /*
 181                                  * No need to roll back, can only fail if
 182                                  * memory allocation fails and then the
 183                                  * number of _possible_ groups has been
 184                                  * increased on some sockets which is ok.
 185                                  */
 186                                 rcu_read_unlock();
 187                                 netlink_table_ungrab();
 188                                 goto out;
 189                         }
 190                 }
 191                 rcu_read_unlock();
 192                 netlink_table_ungrab();
 193         } else {
 194                 err = netlink_change_ngroups(init_net.genl_sock,
 195                                              mc_groups_longs * BITS_PER_LONG);
 196                 if (err)
 197                         goto out;
 198         }
 199
 200         grp->id = id;
 201         set_bit(id, mc_groups);
 202         list_add_tail(&grp->list, &family->mcast_groups);
 203         grp->family = family;
 204
 205         genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
 206  out:
 207         genl_unlock();
 208         return err;
 209 }
 210 EXPORT_SYMBOL(genl_register_mc_group);
 211
 212 static void __genl_unregister_mc_group(struct genl_family *family,
 213                                        struct genl_multicast_group *grp)
 214 {
 215         struct net *net;
 216         BUG_ON(grp->family != family);
 217
 218         netlink_table_grab();
 219         rcu_read_lock();
 220         for_each_net_rcu(net)
 221                 __netlink_clear_multicast_users(net->genl_sock, grp->id);
 222         rcu_read_unlock();
 223         netlink_table_ungrab();
 224
 225         clear_bit(grp->id, mc_groups);
 226         list_del(&grp->list);
 227         genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
 228         grp->id = 0;
 229         grp->family = NULL;
 230 }
 231
 232 /**
 233  * genl_unregister_mc_group - unregister a multicast group
 234  *
 235  * Unregisters the specified multicast group and notifies userspace
 236  * about it. All current listeners on the group are removed.
 237  *
 238  * Note: It is not necessary to unregister all multicast groups before
 239  *       unregistering the family, unregistering the family will cause
 240  *       all assigned multicast groups to be unregistered automatically.
 241  *
 242  * @family: Generic netlink family the group belongs to.
 243  * @grp: The group to unregister, must have been registered successfully
 244  *       previously.
 245  */
 246 void genl_unregister_mc_group(struct genl_family *family,
 247                               struct genl_multicast_group *grp)
 248 {
 249         genl_lock();
 250         __genl_unregister_mc_group(family, grp);
 251         genl_unlock();
 252 }
 253 EXPORT_SYMBOL(genl_unregister_mc_group);
 254
 255 static void genl_unregister_mc_groups(struct genl_family *family)
 256 {
 257         struct genl_multicast_group *grp, *tmp;
 258
 259         list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
 260                 __genl_unregister_mc_group(family, grp);
 261 }
 262
 263 /**
 264  * genl_register_ops - register generic netlink operations
 265  * @family: generic netlink family
 266  * @ops: operations to be registered
 267  *
 268  * Registers the specified operations and assigns them to the specified
 269  * family. Either a doit or dumpit callback must be specified or the
 270  * operation will fail. Only one operation structure per command
 271  * identifier may be registered.
 272  *
 273  * See include/net/genetlink.h for more documenation on the operations
 274  * structure.
 275  *
 276  * Returns 0 on success or a negative error code.
 277  */
 278 int genl_register_ops(struct genl_family *family, struct genl_ops *ops)
 279 {
 280         int err = -EINVAL;
 281
 282         if (ops->dumpit == NULL && ops->doit == NULL)
 283                 goto errout;
 284
 285         if (genl_get_cmd(ops->cmd, family)) {
 286                 err = -EEXIST;
 287                 goto errout;
 288         }
 289
 290         if (ops->dumpit)
 291                 ops->flags |= GENL_CMD_CAP_DUMP;
 292         if (ops->doit)
 293                 ops->flags |= GENL_CMD_CAP_DO;
 294         if (ops->policy)
 295                 ops->flags |= GENL_CMD_CAP_HASPOL;
 296
 297         genl_lock();
 298         list_add_tail(&ops->ops_list, &family->ops_list);
 299         genl_unlock();
 300
 301         genl_ctrl_event(CTRL_CMD_NEWOPS, ops);
 302         err = 0;
 303 errout:
 304         return err;
 305 }
 306
 307 /**
 308  * genl_unregister_ops - unregister generic netlink operations
 309  * @family: generic netlink family
 310  * @ops: operations to be unregistered
 311  *
 312  * Unregisters the specified operations and unassigns them from the
 313  * specified family. The operation blocks until the current message
 314  * processing has finished and doesn't start again until the
 315  * unregister process has finished.
 316  *
 317  * Note: It is not necessary to unregister all operations before
 318  *       unregistering the family, unregistering the family will cause
 319  *       all assigned operations to be unregistered automatically.
 320  *
 321  * Returns 0 on success or a negative error code.
 322  */
 323 int genl_unregister_ops(struct genl_family *family, struct genl_ops *ops)
 324 {
 325         struct genl_ops *rc;
 326
 327         genl_lock();
 328         list_for_each_entry(rc, &family->ops_list, ops_list) {
 329                 if (rc == ops) {
 330                         list_del(&ops->ops_list);
 331                         genl_unlock();
 332                         genl_ctrl_event(CTRL_CMD_DELOPS, ops);
 333                         return 0;
 334                 }
 335         }
 336         genl_unlock();
 337
 338         return -ENOENT;
 339 }
 340
 341 /**
 342  * genl_register_family - register a generic netlink family
 343  * @family: generic netlink family
 344  *
 345  * Registers the specified family after validating it first. Only one
 346  * family may be registered with the same family name or identifier.
 347  * The family id may equal GENL_ID_GENERATE causing an unique id to
 348  * be automatically generated and assigned.
 349  *
 350  * Return 0 on success or a negative error code.
 351  */
 352 int genl_register_family(struct genl_family *family)
 353 {
 354         int err = -EINVAL;
 355
 356         if (family->id && family->id < GENL_MIN_ID)
 357                 goto errout;
 358
 359         if (family->id > GENL_MAX_ID)
 360                 goto errout;
 361
 362         INIT_LIST_HEAD(&family->ops_list);
 363         INIT_LIST_HEAD(&family->mcast_groups);
 364
 365         genl_lock();
 366
 367         if (genl_family_find_byname(family->name)) {
 368                 err = -EEXIST;
 369                 goto errout_locked;
 370         }
 371
 372         if (family->id == GENL_ID_GENERATE) {
 373                 u16 newid = genl_generate_id();
 374
 375                 if (!newid) {
 376                         err = -ENOMEM;
 377                         goto errout_locked;
 378                 }
 379
 380                 family->id = newid;
 381         } else if (genl_family_find_byid(family->id)) {
 382                 err = -EEXIST;
 383                 goto errout_locked;
 384         }
 385
 386         if (family->maxattr) {
 387                 family->attrbuf = kmalloc((family->maxattr+1) *
 388                                         sizeof(struct nlattr *), GFP_KERNEL);
 389                 if (family->attrbuf == NULL) {
 390                         err = -ENOMEM;
 391                         goto errout_locked;
 392                 }
 393         } else
 394                 family->attrbuf = NULL;
 395
 396         list_add_tail(&family->family_list, genl_family_chain(family->id));
 397         genl_unlock();
 398
 399         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
 400
 401         return 0;
 402
 403 errout_locked:
 404         genl_unlock();
 405 errout:
 406         return err;
 407 }
 408
 409 /**
 410  * genl_register_family_with_ops - register a generic netlink family
 411  * @family: generic netlink family
 412  * @ops: operations to be registered
 413  * @n_ops: number of elements to register
 414  *
 415  * Registers the specified family and operations from the specified table.
 416  * Only one family may be registered with the same family name or identifier.
 417  *
 418  * The family id may equal GENL_ID_GENERATE causing an unique id to
 419  * be automatically generated and assigned.
 420  *
 421  * Either a doit or dumpit callback must be specified for every registered
 422  * operation or the function will fail. Only one operation structure per
 423  * command identifier may be registered.
 424  *
 425  * See include/net/genetlink.h for more documenation on the operations
 426  * structure.
 427  *
 428  * This is equivalent to calling genl_register_family() followed by
 429  * genl_register_ops() for every operation entry in the table taking
 430  * care to unregister the family on error path.
 431  *
 432  * Return 0 on success or a negative error code.
 433  */
 434 int genl_register_family_with_ops(struct genl_family *family,
 435         struct genl_ops *ops, size_t n_ops)
 436 {
 437         int err, i;
 438
 439         err = genl_register_family(family);
 440         if (err)
 441                 return err;
 442
 443         for (i = 0; i < n_ops; ++i, ++ops) {
 444                 err = genl_register_ops(family, ops);
 445                 if (err)
 446                         goto err_out;
 447         }
 448         return 0;
 449 err_out:
 450         genl_unregister_family(family);
 451         return err;
 452 }
 453 EXPORT_SYMBOL(genl_register_family_with_ops);
 454
 455 /**
 456  * genl_unregister_family - unregister generic netlink family
 457  * @family: generic netlink family
 458  *
 459  * Unregisters the specified family.
 460  *
 461  * Returns 0 on success or a negative error code.
 462  */
 463 int genl_unregister_family(struct genl_family *family)
 464 {
 465         struct genl_family *rc;
 466
 467         genl_lock();
 468
 469         genl_unregister_mc_groups(family);
 470
 471         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 472                 if (family->id != rc->id || strcmp(rc->name, family->name))
 473                         continue;
 474
 475                 list_del(&rc->family_list);
 476                 INIT_LIST_HEAD(&family->ops_list);
 477                 genl_unlock();
 478
 479                 kfree(family->attrbuf);
 480                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
 481                 return 0;
 482         }
 483
 484         genl_unlock();
 485
 486         return -ENOENT;
 487 }
 488
 489 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 490 {
 491         struct genl_ops *ops;
 492         struct genl_family *family;
 493         struct net *net = sock_net(skb->sk);
 494         struct genl_info info;
 495         struct genlmsghdr *hdr = nlmsg_data(nlh);
 496         int hdrlen, err;
 497
 498         family = genl_family_find_byid(nlh->nlmsg_type);
 499         if (family == NULL)
 500                 return -ENOENT;
 501
 502         /* this family doesn't exist in this netns */
 503         if (!family->netnsok && !net_eq(net, &init_net))
 504                 return -ENOENT;
 505
 506         hdrlen = GENL_HDRLEN + family->hdrsize;
 507         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 508                 return -EINVAL;
 509
 510         ops = genl_get_cmd(hdr->cmd, family);
 511         if (ops == NULL)
 512                 return -EOPNOTSUPP;
 513
 514         if ((ops->flags & GENL_ADMIN_PERM) &&
 515             security_netlink_recv(skb, CAP_NET_ADMIN))
 516                 return -EPERM;
 517
 518         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 519                 if (ops->dumpit == NULL)
 520                         return -EOPNOTSUPP;
 521
 522                 genl_unlock();
 523                 err = netlink_dump_start(net->genl_sock, skb, nlh,
 524                                          ops->dumpit, ops->done);
 525                 genl_lock();
 526                 return err;
 527         }
 528
 529         if (ops->doit == NULL)
 530                 return -EOPNOTSUPP;
 531
 532         if (family->attrbuf) {
 533                 err = nlmsg_parse(nlh, hdrlen, family->attrbuf, family->maxattr,
 534                                   ops->policy);
 535                 if (err < 0)
 536                         return err;
 537         }
 538
 539         info.snd_seq = nlh->nlmsg_seq;
 540         info.snd_pid = NETLINK_CB(skb).pid;
 541         info.nlhdr = nlh;
 542         info.genlhdr = nlmsg_data(nlh);
 543         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 544         info.attrs = family->attrbuf;
 545         genl_info_net_set(&info, net);
 546
 547         return ops->doit(skb, &info);
 548 }
 549
 550 static void genl_rcv(struct sk_buff *skb)
 551 {
 552         genl_lock();
 553         netlink_rcv_skb(skb, &genl_rcv_msg);
 554         genl_unlock();
 555 }
 556
 557 /**************************************************************************
 558  * Controller
 559  **************************************************************************/
 560
 561 static struct genl_family genl_ctrl = {
 562         .id = GENL_ID_CTRL,
 563         .name = "nlctrl",
 564         .version = 0x2,
 565         .maxattr = CTRL_ATTR_MAX,
 566         .netnsok = true,
 567 };
 568
 569 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
 570                           u32 flags, struct sk_buff *skb, u8 cmd)
 571 {
 572         void *hdr;
 573
 574         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 575         if (hdr == NULL)
 576                 return -1;
 577
 578         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, family->name);
 579         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, family->id);
 580         NLA_PUT_U32(skb, CTRL_ATTR_VERSION, family->version);
 581         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
 582         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
 583
 584         if (!list_empty(&family->ops_list)) {
 585                 struct nlattr *nla_ops;
 586                 struct genl_ops *ops;
 587                 int idx = 1;
 588
 589                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 590                 if (nla_ops == NULL)
 591                         goto nla_put_failure;
 592
 593                 list_for_each_entry(ops, &family->ops_list, ops_list) {
 594                         struct nlattr *nest;
 595
 596                         nest = nla_nest_start(skb, idx++);
 597                         if (nest == NULL)
 598                                 goto nla_put_failure;
 599
 600                         NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
 601                         NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
 602
 603                         nla_nest_end(skb, nest);
 604                 }
 605
 606                 nla_nest_end(skb, nla_ops);
 607         }
 608
 609         if (!list_empty(&family->mcast_groups)) {
 610                 struct genl_multicast_group *grp;
 611                 struct nlattr *nla_grps;
 612                 int idx = 1;
 613
 614                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 615                 if (nla_grps == NULL)
 616                         goto nla_put_failure;
 617
 618                 list_for_each_entry(grp, &family->mcast_groups, list) {
 619                         struct nlattr *nest;
 620
 621                         nest = nla_nest_start(skb, idx++);
 622                         if (nest == NULL)
 623                                 goto nla_put_failure;
 624
 625                         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 626                         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 627                                        grp->name);
 628
 629                         nla_nest_end(skb, nest);
 630                 }
 631                 nla_nest_end(skb, nla_grps);
 632         }
 633
 634         return genlmsg_end(skb, hdr);
 635
 636 nla_put_failure:
 637         genlmsg_cancel(skb, hdr);
 638         return -EMSGSIZE;
 639 }
 640
 641 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 pid,
 642                                 u32 seq, u32 flags, struct sk_buff *skb,
 643                                 u8 cmd)
 644 {
 645         void *hdr;
 646         struct nlattr *nla_grps;
 647         struct nlattr *nest;
 648
 649         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
 650         if (hdr == NULL)
 651                 return -1;
 652
 653         NLA_PUT_STRING(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name);
 654         NLA_PUT_U16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id);
 655
 656         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 657         if (nla_grps == NULL)
 658                 goto nla_put_failure;
 659
 660         nest = nla_nest_start(skb, 1);
 661         if (nest == NULL)
 662                 goto nla_put_failure;
 663
 664         NLA_PUT_U32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id);
 665         NLA_PUT_STRING(skb, CTRL_ATTR_MCAST_GRP_NAME,
 666                        grp->name);
 667
 668         nla_nest_end(skb, nest);
 669         nla_nest_end(skb, nla_grps);
 670
 671         return genlmsg_end(skb, hdr);
 672
 673 nla_put_failure:
 674         genlmsg_cancel(skb, hdr);
 675         return -EMSGSIZE;
 676 }
 677
 678 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 679 {
 680
 681         int i, n = 0;
 682         struct genl_family *rt;
 683         struct net *net = sock_net(skb->sk);
 684         int chains_to_skip = cb->args[0];
 685         int fams_to_skip = cb->args[1];
 686
 687         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
 688                 n = 0;
 689                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 690                         if (!rt->netnsok && !net_eq(net, &init_net))
 691                                 continue;
 692                         if (++n < fams_to_skip)
 693                                 continue;
 694                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).pid,
 695                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 696                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 697                                 goto errout;
 698                 }
 699
 700                 fams_to_skip = 0;
 701         }
 702
 703 errout:
 704         cb->args[0] = i;
 705         cb->args[1] = n;
 706
 707         return skb->len;
 708 }
 709
 710 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 711                                              u32 pid, int seq, u8 cmd)
 712 {
 713         struct sk_buff *skb;
 714         int err;
 715
 716         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 717         if (skb == NULL)
 718                 return ERR_PTR(-ENOBUFS);
 719
 720         err = ctrl_fill_info(family, pid, seq, 0, skb, cmd);
 721         if (err < 0) {
 722                 nlmsg_free(skb);
 723                 return ERR_PTR(err);
 724         }
 725
 726         return skb;
 727 }
 728
 729 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
 730                                             u32 pid, int seq, u8 cmd)
 731 {
 732         struct sk_buff *skb;
 733         int err;
 734
 735         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 736         if (skb == NULL)
 737                 return ERR_PTR(-ENOBUFS);
 738
 739         err = ctrl_fill_mcgrp_info(grp, pid, seq, 0, skb, cmd);
 740         if (err < 0) {
 741                 nlmsg_free(skb);
 742                 return ERR_PTR(err);
 743         }
 744
 745         return skb;
 746 }
 747
 748 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 749         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 750         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 751                                     .len = GENL_NAMSIZ - 1 },
 752 };
 753
 754 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 755 {
 756         struct sk_buff *msg;
 757         struct genl_family *res = NULL;
 758         int err = -EINVAL;
 759
 760         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 761                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 762                 res = genl_family_find_byid(id);
 763                 err = -ENOENT;
 764         }
 765
 766         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 767                 char *name;
 768
 769                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 770                 res = genl_family_find_byname(name);
 771                 err = -ENOENT;
 772         }
 773
 774         if (res == NULL)
 775                 return err;
 776
 777         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 778                 /* family doesn't exist here */
 779                 return -ENOENT;
 780         }
 781
 782         msg = ctrl_build_family_msg(res, info->snd_pid, info->snd_seq,
 783                                     CTRL_CMD_NEWFAMILY);
 784         if (IS_ERR(msg))
 785                 return PTR_ERR(msg);
 786
 787         return genlmsg_reply(msg, info);
 788 }
 789
 790 static int genl_ctrl_event(int event, void *data)
 791 {
 792         struct sk_buff *msg;
 793         struct genl_family *family;
 794         struct genl_multicast_group *grp;
 795
 796         /* genl is still initialising */
 797         if (!init_net.genl_sock)
 798                 return 0;
 799
 800         switch (event) {
 801         case CTRL_CMD_NEWFAMILY:
 802         case CTRL_CMD_DELFAMILY:
 803                 family = data;
 804                 msg = ctrl_build_family_msg(family, 0, 0, event);
 805                 break;
 806         case CTRL_CMD_NEWMCAST_GRP:
 807         case CTRL_CMD_DELMCAST_GRP:
 808                 grp = data;
 809                 family = grp->family;
 810                 msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
 811                 break;
 812         default:
 813                 return -EINVAL;
 814         }
 815
 816         if (IS_ERR(msg))
 817                 return PTR_ERR(msg);
 818
 819         if (!family->netnsok) {
 820                 genlmsg_multicast_netns(&init_net, msg, 0,
 821                                         GENL_ID_CTRL, GFP_KERNEL);
 822         } else {
 823                 rcu_read_lock();
 824                 genlmsg_multicast_allns(msg, 0, GENL_ID_CTRL, GFP_ATOMIC);
 825                 rcu_read_unlock();
 826         }
 827
 828         return 0;
 829 }
 830
 831 static struct genl_ops genl_ctrl_ops = {
 832         .cmd            = CTRL_CMD_GETFAMILY,
 833         .doit           = ctrl_getfamily,
 834         .dumpit         = ctrl_dumpfamily,
 835         .policy         = ctrl_policy,
 836 };
 837
 838 static struct genl_multicast_group notify_grp = {
 839         .name           = "notify",
 840 };
 841
 842 static int __net_init genl_pernet_init(struct net *net)
 843 {
 844         /* we'll bump the group number right afterwards */
 845         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, 0,
 846                                                genl_rcv, &genl_mutex,
 847                                                THIS_MODULE);
 848
 849         if (!net->genl_sock && net_eq(net, &init_net))
 850                 panic("GENL: Cannot initialize generic netlink\n");
 851
 852         if (!net->genl_sock)
 853                 return -ENOMEM;
 854
 855         return 0;
 856 }
 857
 858 static void __net_exit genl_pernet_exit(struct net *net)
 859 {
 860         netlink_kernel_release(net->genl_sock);
 861         net->genl_sock = NULL;
 862 }
 863
 864 static struct pernet_operations genl_pernet_ops = {
 865         .init = genl_pernet_init,
 866         .exit = genl_pernet_exit,
 867 };
 868
 869 static int __init genl_init(void)
 870 {
 871         int i, err;
 872
 873         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 874                 INIT_LIST_HEAD(&family_ht[i]);
 875
 876         err = genl_register_family(&genl_ctrl);
 877         if (err < 0)
 878                 goto problem;
 879
 880         err = genl_register_ops(&genl_ctrl, &genl_ctrl_ops);
 881         if (err < 0)
 882                 goto problem;
 883
 884         netlink_set_nonroot(NETLINK_GENERIC, NL_NONROOT_RECV);
 885
 886         err = register_pernet_subsys(&genl_pernet_ops);
 887         if (err)
 888                 goto problem;
 889
 890         err = genl_register_mc_group(&genl_ctrl, &notify_grp);
 891         if (err < 0)
 892                 goto problem;
 893
 894         return 0;
 895
 896 problem:
 897         panic("GENL: Cannot register controller: %d\n", err);
 898 }
 899
 900 subsys_initcall(genl_init);
 901
 902 EXPORT_SYMBOL(genl_register_ops);
 903 EXPORT_SYMBOL(genl_unregister_ops);
 904 EXPORT_SYMBOL(genl_register_family);
 905 EXPORT_SYMBOL(genl_unregister_family);
 906
 907 static int genlmsg_mcast(struct sk_buff *skb, u32 pid, unsigned long group,
 908                          gfp_t flags)
 909 {
 910         struct sk_buff *tmp;
 911         struct net *net, *prev = NULL;
 912         int err;
 913
 914         for_each_net_rcu(net) {
 915                 if (prev) {
 916                         tmp = skb_clone(skb, flags);
 917                         if (!tmp) {
 918                                 err = -ENOMEM;
 919                                 goto error;
 920                         }
 921                         err = nlmsg_multicast(prev->genl_sock, tmp,
 922                                               pid, group, flags);
 923                         if (err)
 924                                 goto error;
 925                 }
 926
 927                 prev = net;
 928         }
 929
 930         return nlmsg_multicast(prev->genl_sock, skb, pid, group, flags);
 931  error:
 932         kfree_skb(skb);
 933         return err;
 934 }
 935
 936 int genlmsg_multicast_allns(struct sk_buff *skb, u32 pid, unsigned int group,
 937                             gfp_t flags)
 938 {
 939         return genlmsg_mcast(skb, pid, group, flags);
 940 }
 941 EXPORT_SYMBOL(genlmsg_multicast_allns);