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 <linux/rwsem.h>
  20 #include <net/sock.h>
  21 #include <net/genetlink.h>
  22
  23 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
  24 static DECLARE_RWSEM(cb_lock);
  25
  26 void genl_lock(void)
  27 {
  28         mutex_lock(&genl_mutex);
  29 }
  30 EXPORT_SYMBOL(genl_lock);
  31
  32 void genl_unlock(void)
  33 {
  34         mutex_unlock(&genl_mutex);
  35 }
  36 EXPORT_SYMBOL(genl_unlock);
  37
  38 #ifdef CONFIG_LOCKDEP
  39 int lockdep_genl_is_held(void)
  40 {
  41         return lockdep_is_held(&genl_mutex);
  42 }
  43 EXPORT_SYMBOL(lockdep_genl_is_held);
  44 #endif
  45
  46 static void genl_lock_all(void)
  47 {
  48         down_write(&cb_lock);
  49         genl_lock();
  50 }
  51
  52 static void genl_unlock_all(void)
  53 {
  54         genl_unlock();
  55         up_write(&cb_lock);
  56 }
  57
  58 #define GENL_FAM_TAB_SIZE       16
  59 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
  60
  61 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
  62 /*
  63  * Bitmap of multicast groups that are currently in use.
  64  *
  65  * To avoid an allocation at boot of just one unsigned long,
  66  * declare it global instead.
  67  * Bit 0 is marked as already used since group 0 is invalid.
  68  * Bit 1 is marked as already used since the drop-monitor code
  69  * abuses the API and thinks it can statically use group 1.
  70  * That group will typically conflict with other groups that
  71  * any proper users use.
  72  * Bit 17 is marked as already used since the VFS quota code
  73  * also abused this API and relied on family == group ID, we
  74  * cater to that by giving it a static family and group ID.
  75  */
  76 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_VFS_DQUOT);
  77 static unsigned long *mc_groups = &mc_group_start;
  78 static unsigned long mc_groups_longs = 1;
  79
  80 static int genl_ctrl_event(int event, void *data);
  81
  82 static inline unsigned int genl_family_hash(unsigned int id)
  83 {
  84         return id & GENL_FAM_TAB_MASK;
  85 }
  86
  87 static inline struct list_head *genl_family_chain(unsigned int id)
  88 {
  89         return &family_ht[genl_family_hash(id)];
  90 }
  91
  92 static struct genl_family *genl_family_find_byid(unsigned int id)
  93 {
  94         struct genl_family *f;
  95
  96         list_for_each_entry(f, genl_family_chain(id), family_list)
  97                 if (f->id == id)
  98                         return f;
  99
 100         return NULL;
 101 }
 102
 103 static struct genl_family *genl_family_find_byname(char *name)
 104 {
 105         struct genl_family *f;
 106         int i;
 107
 108         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 109                 list_for_each_entry(f, genl_family_chain(i), family_list)
 110                         if (strcmp(f->name, name) == 0)
 111                                 return f;
 112
 113         return NULL;
 114 }
 115
 116 static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
 117 {
 118         int i;
 119
 120         for (i = 0; i < family->n_ops; i++)
 121                 if (family->ops[i].cmd == cmd)
 122                         return &family->ops[i];
 123
 124         return NULL;
 125 }
 126
 127 /* Of course we are going to have problems once we hit
 128  * 2^16 alive types, but that can only happen by year 2K
 129 */
 130 static u16 genl_generate_id(void)
 131 {
 132         static u16 id_gen_idx = GENL_MIN_ID;
 133         int i;
 134
 135         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 136                 if (id_gen_idx != GENL_ID_VFS_DQUOT &&
 137                     !genl_family_find_byid(id_gen_idx))
 138                         return id_gen_idx;
 139                 if (++id_gen_idx > GENL_MAX_ID)
 140                         id_gen_idx = GENL_MIN_ID;
 141         }
 142
 143         return 0;
 144 }
 145
 146 static struct genl_multicast_group notify_grp;
 147
 148 /**
 149  * genl_register_mc_group - register a multicast group
 150  *
 151  * Registers the specified multicast group and notifies userspace
 152  * about the new group.
 153  *
 154  * Returns 0 on success or a negative error code.
 155  *
 156  * @family: The generic netlink family the group shall be registered for.
 157  * @grp: The group to register, must have a name.
 158  */
 159 int genl_register_mc_group(struct genl_family *family,
 160                            struct genl_multicast_group *grp)
 161 {
 162         int id;
 163         unsigned long *new_groups;
 164         int err = 0;
 165
 166         BUG_ON(grp->name[0] == '\0');
 167         BUG_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL);
 168
 169         genl_lock_all();
 170
 171         /* special-case our own group and hacks */
 172         if (grp == &notify_grp)
 173                 id = GENL_ID_CTRL;
 174         else if (strcmp(family->name, "NET_DM") == 0)
 175                 id = 1;
 176         else if (strcmp(family->name, "VFS_DQUOT") == 0)
 177                 id = GENL_ID_VFS_DQUOT;
 178         else
 179                 id = find_first_zero_bit(mc_groups,
 180                                          mc_groups_longs * BITS_PER_LONG);
 181
 182
 183         if (id >= mc_groups_longs * BITS_PER_LONG) {
 184                 size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
 185
 186                 if (mc_groups == &mc_group_start) {
 187                         new_groups = kzalloc(nlen, GFP_KERNEL);
 188                         if (!new_groups) {
 189                                 err = -ENOMEM;
 190                                 goto out;
 191                         }
 192                         mc_groups = new_groups;
 193                         *mc_groups = mc_group_start;
 194                 } else {
 195                         new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
 196                         if (!new_groups) {
 197                                 err = -ENOMEM;
 198                                 goto out;
 199                         }
 200                         mc_groups = new_groups;
 201                         mc_groups[mc_groups_longs] = 0;
 202                 }
 203                 mc_groups_longs++;
 204         }
 205
 206         if (family->netnsok) {
 207                 struct net *net;
 208
 209                 netlink_table_grab();
 210                 rcu_read_lock();
 211                 for_each_net_rcu(net) {
 212                         err = __netlink_change_ngroups(net->genl_sock,
 213                                         mc_groups_longs * BITS_PER_LONG);
 214                         if (err) {
 215                                 /*
 216                                  * No need to roll back, can only fail if
 217                                  * memory allocation fails and then the
 218                                  * number of _possible_ groups has been
 219                                  * increased on some sockets which is ok.
 220                                  */
 221                                 rcu_read_unlock();
 222                                 netlink_table_ungrab();
 223                                 goto out;
 224                         }
 225                 }
 226                 rcu_read_unlock();
 227                 netlink_table_ungrab();
 228         } else {
 229                 err = netlink_change_ngroups(init_net.genl_sock,
 230                                              mc_groups_longs * BITS_PER_LONG);
 231                 if (err)
 232                         goto out;
 233         }
 234
 235         grp->id = id;
 236         set_bit(id, mc_groups);
 237         list_add_tail(&grp->list, &family->mcast_groups);
 238         grp->family = family;
 239
 240         genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
 241  out:
 242         genl_unlock_all();
 243         return err;
 244 }
 245 EXPORT_SYMBOL(genl_register_mc_group);
 246
 247 static void __genl_unregister_mc_group(struct genl_family *family,
 248                                        struct genl_multicast_group *grp)
 249 {
 250         struct net *net;
 251         BUG_ON(grp->family != family);
 252
 253         netlink_table_grab();
 254         rcu_read_lock();
 255         for_each_net_rcu(net)
 256                 __netlink_clear_multicast_users(net->genl_sock, grp->id);
 257         rcu_read_unlock();
 258         netlink_table_ungrab();
 259
 260         if (grp->id != 1)
 261                 clear_bit(grp->id, mc_groups);
 262         list_del(&grp->list);
 263         genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
 264         grp->id = 0;
 265         grp->family = NULL;
 266 }
 267
 268 /**
 269  * genl_unregister_mc_group - unregister a multicast group
 270  *
 271  * Unregisters the specified multicast group and notifies userspace
 272  * about it. All current listeners on the group are removed.
 273  *
 274  * Note: It is not necessary to unregister all multicast groups before
 275  *       unregistering the family, unregistering the family will cause
 276  *       all assigned multicast groups to be unregistered automatically.
 277  *
 278  * @family: Generic netlink family the group belongs to.
 279  * @grp: The group to unregister, must have been registered successfully
 280  *       previously.
 281  */
 282 void genl_unregister_mc_group(struct genl_family *family,
 283                               struct genl_multicast_group *grp)
 284 {
 285         genl_lock_all();
 286         __genl_unregister_mc_group(family, grp);
 287         genl_unlock_all();
 288 }
 289 EXPORT_SYMBOL(genl_unregister_mc_group);
 290
 291 static void genl_unregister_mc_groups(struct genl_family *family)
 292 {
 293         struct genl_multicast_group *grp, *tmp;
 294
 295         list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
 296                 __genl_unregister_mc_group(family, grp);
 297 }
 298
 299 static int genl_validate_ops(struct genl_family *family)
 300 {
 301         const struct genl_ops *ops = family->ops;
 302         unsigned int n_ops = family->n_ops;
 303         int i, j;
 304
 305         if (WARN_ON(n_ops && !ops))
 306                 return -EINVAL;
 307
 308         if (!n_ops)
 309                 return 0;
 310
 311         for (i = 0; i < n_ops; i++) {
 312                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 313                         return -EINVAL;
 314                 for (j = i + 1; j < n_ops; j++)
 315                         if (ops[i].cmd == ops[j].cmd)
 316                                 return -EINVAL;
 317         }
 318
 319         /* family is not registered yet, so no locking needed */
 320         family->ops = ops;
 321         family->n_ops = n_ops;
 322
 323         return 0;
 324 }
 325
 326 /**
 327  * __genl_register_family - register a generic netlink family
 328  * @family: generic netlink family
 329  *
 330  * Registers the specified family after validating it first. Only one
 331  * family may be registered with the same family name or identifier.
 332  * The family id may equal GENL_ID_GENERATE causing an unique id to
 333  * be automatically generated and assigned.
 334  *
 335  * The family's ops array must already be assigned, you can use the
 336  * genl_register_family_with_ops() helper function.
 337  *
 338  * Return 0 on success or a negative error code.
 339  */
 340 int __genl_register_family(struct genl_family *family)
 341 {
 342         int err = -EINVAL;
 343
 344         if (family->id && family->id < GENL_MIN_ID)
 345                 goto errout;
 346
 347         if (family->id > GENL_MAX_ID)
 348                 goto errout;
 349
 350         err = genl_validate_ops(family);
 351         if (err)
 352                 return err;
 353
 354         INIT_LIST_HEAD(&family->mcast_groups);
 355
 356         genl_lock_all();
 357
 358         if (genl_family_find_byname(family->name)) {
 359                 err = -EEXIST;
 360                 goto errout_locked;
 361         }
 362
 363         if (family->id == GENL_ID_GENERATE) {
 364                 u16 newid = genl_generate_id();
 365
 366                 if (!newid) {
 367                         err = -ENOMEM;
 368                         goto errout_locked;
 369                 }
 370
 371                 family->id = newid;
 372         } else if (genl_family_find_byid(family->id)) {
 373                 err = -EEXIST;
 374                 goto errout_locked;
 375         }
 376
 377         if (family->maxattr && !family->parallel_ops) {
 378                 family->attrbuf = kmalloc((family->maxattr+1) *
 379                                         sizeof(struct nlattr *), GFP_KERNEL);
 380                 if (family->attrbuf == NULL) {
 381                         err = -ENOMEM;
 382                         goto errout_locked;
 383                 }
 384         } else
 385                 family->attrbuf = NULL;
 386
 387         list_add_tail(&family->family_list, genl_family_chain(family->id));
 388         genl_unlock_all();
 389
 390         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
 391
 392         return 0;
 393
 394 errout_locked:
 395         genl_unlock_all();
 396 errout:
 397         return err;
 398 }
 399 EXPORT_SYMBOL(__genl_register_family);
 400
 401 /**
 402  * genl_unregister_family - unregister generic netlink family
 403  * @family: generic netlink family
 404  *
 405  * Unregisters the specified family.
 406  *
 407  * Returns 0 on success or a negative error code.
 408  */
 409 int genl_unregister_family(struct genl_family *family)
 410 {
 411         struct genl_family *rc;
 412
 413         genl_lock_all();
 414
 415         genl_unregister_mc_groups(family);
 416
 417         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 418                 if (family->id != rc->id || strcmp(rc->name, family->name))
 419                         continue;
 420
 421                 list_del(&rc->family_list);
 422                 family->n_ops = 0;
 423                 genl_unlock_all();
 424
 425                 kfree(family->attrbuf);
 426                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
 427                 return 0;
 428         }
 429
 430         genl_unlock_all();
 431
 432         return -ENOENT;
 433 }
 434 EXPORT_SYMBOL(genl_unregister_family);
 435
 436 /**
 437  * genlmsg_put - Add generic netlink header to netlink message
 438  * @skb: socket buffer holding the message
 439  * @portid: netlink portid the message is addressed to
 440  * @seq: sequence number (usually the one of the sender)
 441  * @family: generic netlink family
 442  * @flags: netlink message flags
 443  * @cmd: generic netlink command
 444  *
 445  * Returns pointer to user specific header
 446  */
 447 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 448                                 struct genl_family *family, int flags, u8 cmd)
 449 {
 450         struct nlmsghdr *nlh;
 451         struct genlmsghdr *hdr;
 452
 453         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 454                         family->hdrsize, flags);
 455         if (nlh == NULL)
 456                 return NULL;
 457
 458         hdr = nlmsg_data(nlh);
 459         hdr->cmd = cmd;
 460         hdr->version = family->version;
 461         hdr->reserved = 0;
 462
 463         return (char *) hdr + GENL_HDRLEN;
 464 }
 465 EXPORT_SYMBOL(genlmsg_put);
 466
 467 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 468 {
 469         /* our ops are always const - netlink API doesn't propagate that */
 470         const struct genl_ops *ops = cb->data;
 471         int rc;
 472
 473         genl_lock();
 474         rc = ops->dumpit(skb, cb);
 475         genl_unlock();
 476         return rc;
 477 }
 478
 479 static int genl_lock_done(struct netlink_callback *cb)
 480 {
 481         /* our ops are always const - netlink API doesn't propagate that */
 482         const struct genl_ops *ops = cb->data;
 483         int rc = 0;
 484
 485         if (ops->done) {
 486                 genl_lock();
 487                 rc = ops->done(cb);
 488                 genl_unlock();
 489         }
 490         return rc;
 491 }
 492
 493 static int genl_family_rcv_msg(struct genl_family *family,
 494                                struct sk_buff *skb,
 495                                struct nlmsghdr *nlh)
 496 {
 497         const struct genl_ops *ops;
 498         struct net *net = sock_net(skb->sk);
 499         struct genl_info info;
 500         struct genlmsghdr *hdr = nlmsg_data(nlh);
 501         struct nlattr **attrbuf;
 502         int hdrlen, err;
 503
 504         /* this family doesn't exist in this netns */
 505         if (!family->netnsok && !net_eq(net, &init_net))
 506                 return -ENOENT;
 507
 508         hdrlen = GENL_HDRLEN + family->hdrsize;
 509         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 510                 return -EINVAL;
 511
 512         ops = genl_get_cmd(hdr->cmd, family);
 513         if (ops == NULL)
 514                 return -EOPNOTSUPP;
 515
 516         if ((ops->flags & GENL_ADMIN_PERM) &&
 517             !capable(CAP_NET_ADMIN))
 518                 return -EPERM;
 519
 520         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 521                 int rc;
 522
 523                 if (ops->dumpit == NULL)
 524                         return -EOPNOTSUPP;
 525
 526                 if (!family->parallel_ops) {
 527                         struct netlink_dump_control c = {
 528                                 .module = family->module,
 529                                 /* we have const, but the netlink API doesn't */
 530                                 .data = (void *)ops,
 531                                 .dump = genl_lock_dumpit,
 532                                 .done = genl_lock_done,
 533                         };
 534
 535                         genl_unlock();
 536                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 537                         genl_lock();
 538
 539                 } else {
 540                         struct netlink_dump_control c = {
 541                                 .module = family->module,
 542                                 .dump = ops->dumpit,
 543                                 .done = ops->done,
 544                         };
 545
 546                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 547                 }
 548
 549                 return rc;
 550         }
 551
 552         if (ops->doit == NULL)
 553                 return -EOPNOTSUPP;
 554
 555         if (family->maxattr && family->parallel_ops) {
 556                 attrbuf = kmalloc((family->maxattr+1) *
 557                                         sizeof(struct nlattr *), GFP_KERNEL);
 558                 if (attrbuf == NULL)
 559                         return -ENOMEM;
 560         } else
 561                 attrbuf = family->attrbuf;
 562
 563         if (attrbuf) {
 564                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 565                                   ops->policy);
 566                 if (err < 0)
 567                         goto out;
 568         }
 569
 570         info.snd_seq = nlh->nlmsg_seq;
 571         info.snd_portid = NETLINK_CB(skb).portid;
 572         info.nlhdr = nlh;
 573         info.genlhdr = nlmsg_data(nlh);
 574         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 575         info.attrs = attrbuf;
 576         genl_info_net_set(&info, net);
 577         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 578
 579         if (family->pre_doit) {
 580                 err = family->pre_doit(ops, skb, &info);
 581                 if (err)
 582                         goto out;
 583         }
 584
 585         err = ops->doit(skb, &info);
 586
 587         if (family->post_doit)
 588                 family->post_doit(ops, skb, &info);
 589
 590 out:
 591         if (family->parallel_ops)
 592                 kfree(attrbuf);
 593
 594         return err;
 595 }
 596
 597 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 598 {
 599         struct genl_family *family;
 600         int err;
 601
 602         family = genl_family_find_byid(nlh->nlmsg_type);
 603         if (family == NULL)
 604                 return -ENOENT;
 605
 606         if (!family->parallel_ops)
 607                 genl_lock();
 608
 609         err = genl_family_rcv_msg(family, skb, nlh);
 610
 611         if (!family->parallel_ops)
 612                 genl_unlock();
 613
 614         return err;
 615 }
 616
 617 static void genl_rcv(struct sk_buff *skb)
 618 {
 619         down_read(&cb_lock);
 620         netlink_rcv_skb(skb, &genl_rcv_msg);
 621         up_read(&cb_lock);
 622 }
 623
 624 /**************************************************************************
 625  * Controller
 626  **************************************************************************/
 627
 628 static struct genl_family genl_ctrl = {
 629         .id = GENL_ID_CTRL,
 630         .name = "nlctrl",
 631         .version = 0x2,
 632         .maxattr = CTRL_ATTR_MAX,
 633         .netnsok = true,
 634 };
 635
 636 static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
 637                           u32 flags, struct sk_buff *skb, u8 cmd)
 638 {
 639         void *hdr;
 640
 641         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 642         if (hdr == NULL)
 643                 return -1;
 644
 645         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 646             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 647             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 648             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 649             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 650                 goto nla_put_failure;
 651
 652         if (family->n_ops) {
 653                 struct nlattr *nla_ops;
 654                 int i;
 655
 656                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 657                 if (nla_ops == NULL)
 658                         goto nla_put_failure;
 659
 660                 for (i = 0; i < family->n_ops; i++) {
 661                         struct nlattr *nest;
 662                         const struct genl_ops *ops = &family->ops[i];
 663                         u32 op_flags = ops->flags;
 664
 665                         if (ops->dumpit)
 666                                 op_flags |= GENL_CMD_CAP_DUMP;
 667                         if (ops->doit)
 668                                 op_flags |= GENL_CMD_CAP_DO;
 669                         if (ops->policy)
 670                                 op_flags |= GENL_CMD_CAP_HASPOL;
 671
 672                         nest = nla_nest_start(skb, i + 1);
 673                         if (nest == NULL)
 674                                 goto nla_put_failure;
 675
 676                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 677                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 678                                 goto nla_put_failure;
 679
 680                         nla_nest_end(skb, nest);
 681                 }
 682
 683                 nla_nest_end(skb, nla_ops);
 684         }
 685
 686         if (!list_empty(&family->mcast_groups)) {
 687                 struct genl_multicast_group *grp;
 688                 struct nlattr *nla_grps;
 689                 int idx = 1;
 690
 691                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 692                 if (nla_grps == NULL)
 693                         goto nla_put_failure;
 694
 695                 list_for_each_entry(grp, &family->mcast_groups, list) {
 696                         struct nlattr *nest;
 697
 698                         nest = nla_nest_start(skb, idx++);
 699                         if (nest == NULL)
 700                                 goto nla_put_failure;
 701
 702                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id) ||
 703                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 704                                            grp->name))
 705                                 goto nla_put_failure;
 706
 707                         nla_nest_end(skb, nest);
 708                 }
 709                 nla_nest_end(skb, nla_grps);
 710         }
 711
 712         return genlmsg_end(skb, hdr);
 713
 714 nla_put_failure:
 715         genlmsg_cancel(skb, hdr);
 716         return -EMSGSIZE;
 717 }
 718
 719 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 portid,
 720                                 u32 seq, u32 flags, struct sk_buff *skb,
 721                                 u8 cmd)
 722 {
 723         void *hdr;
 724         struct nlattr *nla_grps;
 725         struct nlattr *nest;
 726
 727         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 728         if (hdr == NULL)
 729                 return -1;
 730
 731         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name) ||
 732             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id))
 733                 goto nla_put_failure;
 734
 735         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 736         if (nla_grps == NULL)
 737                 goto nla_put_failure;
 738
 739         nest = nla_nest_start(skb, 1);
 740         if (nest == NULL)
 741                 goto nla_put_failure;
 742
 743         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id) ||
 744             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 745                            grp->name))
 746                 goto nla_put_failure;
 747
 748         nla_nest_end(skb, nest);
 749         nla_nest_end(skb, nla_grps);
 750
 751         return genlmsg_end(skb, hdr);
 752
 753 nla_put_failure:
 754         genlmsg_cancel(skb, hdr);
 755         return -EMSGSIZE;
 756 }
 757
 758 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 759 {
 760
 761         int i, n = 0;
 762         struct genl_family *rt;
 763         struct net *net = sock_net(skb->sk);
 764         int chains_to_skip = cb->args[0];
 765         int fams_to_skip = cb->args[1];
 766
 767         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
 768                 n = 0;
 769                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 770                         if (!rt->netnsok && !net_eq(net, &init_net))
 771                                 continue;
 772                         if (++n < fams_to_skip)
 773                                 continue;
 774                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 775                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 776                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 777                                 goto errout;
 778                 }
 779
 780                 fams_to_skip = 0;
 781         }
 782
 783 errout:
 784         cb->args[0] = i;
 785         cb->args[1] = n;
 786
 787         return skb->len;
 788 }
 789
 790 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 791                                              u32 portid, int seq, u8 cmd)
 792 {
 793         struct sk_buff *skb;
 794         int err;
 795
 796         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 797         if (skb == NULL)
 798                 return ERR_PTR(-ENOBUFS);
 799
 800         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 801         if (err < 0) {
 802                 nlmsg_free(skb);
 803                 return ERR_PTR(err);
 804         }
 805
 806         return skb;
 807 }
 808
 809 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
 810                                             u32 portid, int seq, u8 cmd)
 811 {
 812         struct sk_buff *skb;
 813         int err;
 814
 815         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 816         if (skb == NULL)
 817                 return ERR_PTR(-ENOBUFS);
 818
 819         err = ctrl_fill_mcgrp_info(grp, portid, seq, 0, skb, cmd);
 820         if (err < 0) {
 821                 nlmsg_free(skb);
 822                 return ERR_PTR(err);
 823         }
 824
 825         return skb;
 826 }
 827
 828 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 829         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 830         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 831                                     .len = GENL_NAMSIZ - 1 },
 832 };
 833
 834 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 835 {
 836         struct sk_buff *msg;
 837         struct genl_family *res = NULL;
 838         int err = -EINVAL;
 839
 840         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 841                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 842                 res = genl_family_find_byid(id);
 843                 err = -ENOENT;
 844         }
 845
 846         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 847                 char *name;
 848
 849                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 850                 res = genl_family_find_byname(name);
 851 #ifdef CONFIG_MODULES
 852                 if (res == NULL) {
 853                         genl_unlock();
 854                         up_read(&cb_lock);
 855                         request_module("net-pf-%d-proto-%d-family-%s",
 856                                        PF_NETLINK, NETLINK_GENERIC, name);
 857                         down_read(&cb_lock);
 858                         genl_lock();
 859                         res = genl_family_find_byname(name);
 860                 }
 861 #endif
 862                 err = -ENOENT;
 863         }
 864
 865         if (res == NULL)
 866                 return err;
 867
 868         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 869                 /* family doesn't exist here */
 870                 return -ENOENT;
 871         }
 872
 873         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 874                                     CTRL_CMD_NEWFAMILY);
 875         if (IS_ERR(msg))
 876                 return PTR_ERR(msg);
 877
 878         return genlmsg_reply(msg, info);
 879 }
 880
 881 static int genl_ctrl_event(int event, void *data)
 882 {
 883         struct sk_buff *msg;
 884         struct genl_family *family;
 885         struct genl_multicast_group *grp;
 886
 887         /* genl is still initialising */
 888         if (!init_net.genl_sock)
 889                 return 0;
 890
 891         switch (event) {
 892         case CTRL_CMD_NEWFAMILY:
 893         case CTRL_CMD_DELFAMILY:
 894                 family = data;
 895                 msg = ctrl_build_family_msg(family, 0, 0, event);
 896                 break;
 897         case CTRL_CMD_NEWMCAST_GRP:
 898         case CTRL_CMD_DELMCAST_GRP:
 899                 grp = data;
 900                 family = grp->family;
 901                 msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
 902                 break;
 903         default:
 904                 return -EINVAL;
 905         }
 906
 907         if (IS_ERR(msg))
 908                 return PTR_ERR(msg);
 909
 910         if (!family->netnsok) {
 911                 genlmsg_multicast_netns(&init_net, msg, 0,
 912                                         GENL_ID_CTRL, GFP_KERNEL);
 913         } else {
 914                 rcu_read_lock();
 915                 genlmsg_multicast_allns(msg, 0, GENL_ID_CTRL, GFP_ATOMIC);
 916                 rcu_read_unlock();
 917         }
 918
 919         return 0;
 920 }
 921
 922 static struct genl_ops genl_ctrl_ops[] = {
 923         {
 924                 .cmd            = CTRL_CMD_GETFAMILY,
 925                 .doit           = ctrl_getfamily,
 926                 .dumpit         = ctrl_dumpfamily,
 927                 .policy         = ctrl_policy,
 928         },
 929 };
 930
 931 static struct genl_multicast_group notify_grp = {
 932         .name           = "notify",
 933 };
 934
 935 static int __net_init genl_pernet_init(struct net *net)
 936 {
 937         struct netlink_kernel_cfg cfg = {
 938                 .input          = genl_rcv,
 939                 .flags          = NL_CFG_F_NONROOT_RECV,
 940         };
 941
 942         /* we'll bump the group number right afterwards */
 943         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
 944
 945         if (!net->genl_sock && net_eq(net, &init_net))
 946                 panic("GENL: Cannot initialize generic netlink\n");
 947
 948         if (!net->genl_sock)
 949                 return -ENOMEM;
 950
 951         return 0;
 952 }
 953
 954 static void __net_exit genl_pernet_exit(struct net *net)
 955 {
 956         netlink_kernel_release(net->genl_sock);
 957         net->genl_sock = NULL;
 958 }
 959
 960 static struct pernet_operations genl_pernet_ops = {
 961         .init = genl_pernet_init,
 962         .exit = genl_pernet_exit,
 963 };
 964
 965 static int __init genl_init(void)
 966 {
 967         int i, err;
 968
 969         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 970                 INIT_LIST_HEAD(&family_ht[i]);
 971
 972         err = genl_register_family_with_ops(&genl_ctrl, genl_ctrl_ops);
 973         if (err < 0)
 974                 goto problem;
 975
 976         err = register_pernet_subsys(&genl_pernet_ops);
 977         if (err)
 978                 goto problem;
 979
 980         err = genl_register_mc_group(&genl_ctrl, &notify_grp);
 981         if (err < 0)
 982                 goto problem;
 983
 984         return 0;
 985
 986 problem:
 987         panic("GENL: Cannot register controller: %d\n", err);
 988 }
 989
 990 subsys_initcall(genl_init);
 991
 992 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
 993                          gfp_t flags)
 994 {
 995         struct sk_buff *tmp;
 996         struct net *net, *prev = NULL;
 997         int err;
 998
 999         for_each_net_rcu(net) {
1000                 if (prev) {
1001                         tmp = skb_clone(skb, flags);
1002                         if (!tmp) {
1003                                 err = -ENOMEM;
1004                                 goto error;
1005                         }
1006                         err = nlmsg_multicast(prev->genl_sock, tmp,
1007                                               portid, group, flags);
1008                         if (err)
1009                                 goto error;
1010                 }
1011
1012                 prev = net;
1013         }
1014
1015         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1016  error:
1017         kfree_skb(skb);
1018         return err;
1019 }
1020
1021 int genlmsg_multicast_allns(struct sk_buff *skb, u32 portid, unsigned int group,
1022                             gfp_t flags)
1023 {
1024         return genlmsg_mcast(skb, portid, group, flags);
1025 }
1026 EXPORT_SYMBOL(genlmsg_multicast_allns);
1027
1028 void genl_notify(struct sk_buff *skb, struct net *net, u32 portid, u32 group,
1029                  struct nlmsghdr *nlh, gfp_t flags)
1030 {
1031         struct sock *sk = net->genl_sock;
1032         int report = 0;
1033
1034         if (nlh)
1035                 report = nlmsg_report(nlh);
1036
1037         nlmsg_notify(sk, skb, portid, group, report, flags);
1038 }
1039 EXPORT_SYMBOL(genl_notify);