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