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  */
  69 static unsigned long mc_group_start = 0x1;
  70 static unsigned long *mc_groups = &mc_group_start;
  71 static unsigned long mc_groups_longs = 1;
  72
  73 static int genl_ctrl_event(int event, void *data);
  74
  75 static inline unsigned int genl_family_hash(unsigned int id)
  76 {
  77         return id & GENL_FAM_TAB_MASK;
  78 }
  79
  80 static inline struct list_head *genl_family_chain(unsigned int id)
  81 {
  82         return &family_ht[genl_family_hash(id)];
  83 }
  84
  85 static struct genl_family *genl_family_find_byid(unsigned int id)
  86 {
  87         struct genl_family *f;
  88
  89         list_for_each_entry(f, genl_family_chain(id), family_list)
  90                 if (f->id == id)
  91                         return f;
  92
  93         return NULL;
  94 }
  95
  96 static struct genl_family *genl_family_find_byname(char *name)
  97 {
  98         struct genl_family *f;
  99         int i;
 100
 101         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 102                 list_for_each_entry(f, genl_family_chain(i), family_list)
 103                         if (strcmp(f->name, name) == 0)
 104                                 return f;
 105
 106         return NULL;
 107 }
 108
 109 static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
 110 {
 111         int i;
 112
 113         for (i = 0; i < family->n_ops; i++)
 114                 if (family->ops[i].cmd == cmd)
 115                         return &family->ops[i];
 116
 117         return NULL;
 118 }
 119
 120 /* Of course we are going to have problems once we hit
 121  * 2^16 alive types, but that can only happen by year 2K
 122 */
 123 static u16 genl_generate_id(void)
 124 {
 125         static u16 id_gen_idx = GENL_MIN_ID;
 126         int i;
 127
 128         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 129                 if (!genl_family_find_byid(id_gen_idx))
 130                         return id_gen_idx;
 131                 if (++id_gen_idx > GENL_MAX_ID)
 132                         id_gen_idx = GENL_MIN_ID;
 133         }
 134
 135         return 0;
 136 }
 137
 138 static struct genl_multicast_group notify_grp;
 139
 140 /**
 141  * genl_register_mc_group - register a multicast group
 142  *
 143  * Registers the specified multicast group and notifies userspace
 144  * about the new group.
 145  *
 146  * Returns 0 on success or a negative error code.
 147  *
 148  * @family: The generic netlink family the group shall be registered for.
 149  * @grp: The group to register, must have a name.
 150  */
 151 int genl_register_mc_group(struct genl_family *family,
 152                            struct genl_multicast_group *grp)
 153 {
 154         int id;
 155         unsigned long *new_groups;
 156         int err = 0;
 157
 158         BUG_ON(grp->name[0] == '\0');
 159         BUG_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL);
 160
 161         genl_lock_all();
 162
 163         /* special-case our own group */
 164         if (grp == &notify_grp)
 165                 id = GENL_ID_CTRL;
 166         else
 167                 id = find_first_zero_bit(mc_groups,
 168                                          mc_groups_longs * BITS_PER_LONG);
 169
 170
 171         if (id >= mc_groups_longs * BITS_PER_LONG) {
 172                 size_t nlen = (mc_groups_longs + 1) * sizeof(unsigned long);
 173
 174                 if (mc_groups == &mc_group_start) {
 175                         new_groups = kzalloc(nlen, GFP_KERNEL);
 176                         if (!new_groups) {
 177                                 err = -ENOMEM;
 178                                 goto out;
 179                         }
 180                         mc_groups = new_groups;
 181                         *mc_groups = mc_group_start;
 182                 } else {
 183                         new_groups = krealloc(mc_groups, nlen, GFP_KERNEL);
 184                         if (!new_groups) {
 185                                 err = -ENOMEM;
 186                                 goto out;
 187                         }
 188                         mc_groups = new_groups;
 189                         mc_groups[mc_groups_longs] = 0;
 190                 }
 191                 mc_groups_longs++;
 192         }
 193
 194         if (family->netnsok) {
 195                 struct net *net;
 196
 197                 netlink_table_grab();
 198                 rcu_read_lock();
 199                 for_each_net_rcu(net) {
 200                         err = __netlink_change_ngroups(net->genl_sock,
 201                                         mc_groups_longs * BITS_PER_LONG);
 202                         if (err) {
 203                                 /*
 204                                  * No need to roll back, can only fail if
 205                                  * memory allocation fails and then the
 206                                  * number of _possible_ groups has been
 207                                  * increased on some sockets which is ok.
 208                                  */
 209                                 rcu_read_unlock();
 210                                 netlink_table_ungrab();
 211                                 goto out;
 212                         }
 213                 }
 214                 rcu_read_unlock();
 215                 netlink_table_ungrab();
 216         } else {
 217                 err = netlink_change_ngroups(init_net.genl_sock,
 218                                              mc_groups_longs * BITS_PER_LONG);
 219                 if (err)
 220                         goto out;
 221         }
 222
 223         grp->id = id;
 224         set_bit(id, mc_groups);
 225         list_add_tail(&grp->list, &family->mcast_groups);
 226         grp->family = family;
 227
 228         genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, grp);
 229  out:
 230         genl_unlock_all();
 231         return err;
 232 }
 233 EXPORT_SYMBOL(genl_register_mc_group);
 234
 235 static void __genl_unregister_mc_group(struct genl_family *family,
 236                                        struct genl_multicast_group *grp)
 237 {
 238         struct net *net;
 239         BUG_ON(grp->family != family);
 240
 241         netlink_table_grab();
 242         rcu_read_lock();
 243         for_each_net_rcu(net)
 244                 __netlink_clear_multicast_users(net->genl_sock, grp->id);
 245         rcu_read_unlock();
 246         netlink_table_ungrab();
 247
 248         clear_bit(grp->id, mc_groups);
 249         list_del(&grp->list);
 250         genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, grp);
 251         grp->id = 0;
 252         grp->family = NULL;
 253 }
 254
 255 /**
 256  * genl_unregister_mc_group - unregister a multicast group
 257  *
 258  * Unregisters the specified multicast group and notifies userspace
 259  * about it. All current listeners on the group are removed.
 260  *
 261  * Note: It is not necessary to unregister all multicast groups before
 262  *       unregistering the family, unregistering the family will cause
 263  *       all assigned multicast groups to be unregistered automatically.
 264  *
 265  * @family: Generic netlink family the group belongs to.
 266  * @grp: The group to unregister, must have been registered successfully
 267  *       previously.
 268  */
 269 void genl_unregister_mc_group(struct genl_family *family,
 270                               struct genl_multicast_group *grp)
 271 {
 272         genl_lock_all();
 273         __genl_unregister_mc_group(family, grp);
 274         genl_unlock_all();
 275 }
 276 EXPORT_SYMBOL(genl_unregister_mc_group);
 277
 278 static void genl_unregister_mc_groups(struct genl_family *family)
 279 {
 280         struct genl_multicast_group *grp, *tmp;
 281
 282         list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
 283                 __genl_unregister_mc_group(family, grp);
 284 }
 285
 286 static int genl_validate_add_ops(struct genl_family *family,
 287                                  const struct genl_ops *ops,
 288                                  unsigned int n_ops)
 289 {
 290         int i, j;
 291
 292         for (i = 0; i < n_ops; i++) {
 293                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 294                         return -EINVAL;
 295                 for (j = i + 1; j < n_ops; j++)
 296                         if (ops[i].cmd == ops[j].cmd)
 297                                 return -EINVAL;
 298         }
 299
 300         /* family is not registered yet, so no locking needed */
 301         family->ops = ops;
 302         family->n_ops = n_ops;
 303
 304         return 0;
 305 }
 306
 307 /**
 308  * __genl_register_family - register a generic netlink family
 309  * @family: generic netlink family
 310  *
 311  * Registers the specified family after validating it first. Only one
 312  * family may be registered with the same family name or identifier.
 313  * The family id may equal GENL_ID_GENERATE causing an unique id to
 314  * be automatically generated and assigned.
 315  *
 316  * Return 0 on success or a negative error code.
 317  */
 318 int __genl_register_family(struct genl_family *family)
 319 {
 320         int err = -EINVAL;
 321
 322         if (family->id && family->id < GENL_MIN_ID)
 323                 goto errout;
 324
 325         if (family->id > GENL_MAX_ID)
 326                 goto errout;
 327
 328         INIT_LIST_HEAD(&family->mcast_groups);
 329
 330         genl_lock_all();
 331
 332         if (genl_family_find_byname(family->name)) {
 333                 err = -EEXIST;
 334                 goto errout_locked;
 335         }
 336
 337         if (family->id == GENL_ID_GENERATE) {
 338                 u16 newid = genl_generate_id();
 339
 340                 if (!newid) {
 341                         err = -ENOMEM;
 342                         goto errout_locked;
 343                 }
 344
 345                 family->id = newid;
 346         } else if (genl_family_find_byid(family->id)) {
 347                 err = -EEXIST;
 348                 goto errout_locked;
 349         }
 350
 351         if (family->maxattr && !family->parallel_ops) {
 352                 family->attrbuf = kmalloc((family->maxattr+1) *
 353                                         sizeof(struct nlattr *), GFP_KERNEL);
 354                 if (family->attrbuf == NULL) {
 355                         err = -ENOMEM;
 356                         goto errout_locked;
 357                 }
 358         } else
 359                 family->attrbuf = NULL;
 360
 361         list_add_tail(&family->family_list, genl_family_chain(family->id));
 362         genl_unlock_all();
 363
 364         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family);
 365
 366         return 0;
 367
 368 errout_locked:
 369         genl_unlock_all();
 370 errout:
 371         return err;
 372 }
 373 EXPORT_SYMBOL(__genl_register_family);
 374
 375 /**
 376  * __genl_register_family_with_ops - register a generic netlink family
 377  * @family: generic netlink family
 378  * @ops: operations to be registered
 379  * @n_ops: number of elements to register
 380  *
 381  * Registers the specified family and operations from the specified table.
 382  * Only one family may be registered with the same family name or identifier.
 383  *
 384  * The family id may equal GENL_ID_GENERATE causing an unique id to
 385  * be automatically generated and assigned.
 386  *
 387  * Either a doit or dumpit callback must be specified for every registered
 388  * operation or the function will fail. Only one operation structure per
 389  * command identifier may be registered.
 390  *
 391  * See include/net/genetlink.h for more documenation on the operations
 392  * structure.
 393  *
 394  * Return 0 on success or a negative error code.
 395  */
 396 int __genl_register_family_with_ops(struct genl_family *family,
 397         const struct genl_ops *ops, size_t n_ops)
 398 {
 399         int err;
 400
 401         err = genl_validate_add_ops(family, ops, n_ops);
 402         if (err)
 403                 return err;
 404
 405         return __genl_register_family(family);
 406 }
 407 EXPORT_SYMBOL(__genl_register_family_with_ops);
 408
 409 /**
 410  * genl_unregister_family - unregister generic netlink family
 411  * @family: generic netlink family
 412  *
 413  * Unregisters the specified family.
 414  *
 415  * Returns 0 on success or a negative error code.
 416  */
 417 int genl_unregister_family(struct genl_family *family)
 418 {
 419         struct genl_family *rc;
 420
 421         genl_lock_all();
 422
 423         genl_unregister_mc_groups(family);
 424
 425         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 426                 if (family->id != rc->id || strcmp(rc->name, family->name))
 427                         continue;
 428
 429                 list_del(&rc->family_list);
 430                 family->n_ops = 0;
 431                 genl_unlock_all();
 432
 433                 kfree(family->attrbuf);
 434                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family);
 435                 return 0;
 436         }
 437
 438         genl_unlock_all();
 439
 440         return -ENOENT;
 441 }
 442 EXPORT_SYMBOL(genl_unregister_family);
 443
 444 /**
 445  * genlmsg_put - Add generic netlink header to netlink message
 446  * @skb: socket buffer holding the message
 447  * @portid: netlink portid the message is addressed to
 448  * @seq: sequence number (usually the one of the sender)
 449  * @family: generic netlink family
 450  * @flags: netlink message flags
 451  * @cmd: generic netlink command
 452  *
 453  * Returns pointer to user specific header
 454  */
 455 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 456                                 struct genl_family *family, int flags, u8 cmd)
 457 {
 458         struct nlmsghdr *nlh;
 459         struct genlmsghdr *hdr;
 460
 461         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 462                         family->hdrsize, flags);
 463         if (nlh == NULL)
 464                 return NULL;
 465
 466         hdr = nlmsg_data(nlh);
 467         hdr->cmd = cmd;
 468         hdr->version = family->version;
 469         hdr->reserved = 0;
 470
 471         return (char *) hdr + GENL_HDRLEN;
 472 }
 473 EXPORT_SYMBOL(genlmsg_put);
 474
 475 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 476 {
 477         /* our ops are always const - netlink API doesn't propagate that */
 478         const struct genl_ops *ops = cb->data;
 479         int rc;
 480
 481         genl_lock();
 482         rc = ops->dumpit(skb, cb);
 483         genl_unlock();
 484         return rc;
 485 }
 486
 487 static int genl_lock_done(struct netlink_callback *cb)
 488 {
 489         /* our ops are always const - netlink API doesn't propagate that */
 490         const struct genl_ops *ops = cb->data;
 491         int rc = 0;
 492
 493         if (ops->done) {
 494                 genl_lock();
 495                 rc = ops->done(cb);
 496                 genl_unlock();
 497         }
 498         return rc;
 499 }
 500
 501 static int genl_family_rcv_msg(struct genl_family *family,
 502                                struct sk_buff *skb,
 503                                struct nlmsghdr *nlh)
 504 {
 505         const struct genl_ops *ops;
 506         struct net *net = sock_net(skb->sk);
 507         struct genl_info info;
 508         struct genlmsghdr *hdr = nlmsg_data(nlh);
 509         struct nlattr **attrbuf;
 510         int hdrlen, err;
 511
 512         /* this family doesn't exist in this netns */
 513         if (!family->netnsok && !net_eq(net, &init_net))
 514                 return -ENOENT;
 515
 516         hdrlen = GENL_HDRLEN + family->hdrsize;
 517         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 518                 return -EINVAL;
 519
 520         ops = genl_get_cmd(hdr->cmd, family);
 521         if (ops == NULL)
 522                 return -EOPNOTSUPP;
 523
 524         if ((ops->flags & GENL_ADMIN_PERM) &&
 525             !capable(CAP_NET_ADMIN))
 526                 return -EPERM;
 527
 528         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 529                 int rc;
 530
 531                 if (ops->dumpit == NULL)
 532                         return -EOPNOTSUPP;
 533
 534                 if (!family->parallel_ops) {
 535                         struct netlink_dump_control c = {
 536                                 .module = family->module,
 537                                 /* we have const, but the netlink API doesn't */
 538                                 .data = (void *)ops,
 539                                 .dump = genl_lock_dumpit,
 540                                 .done = genl_lock_done,
 541                         };
 542
 543                         genl_unlock();
 544                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 545                         genl_lock();
 546
 547                 } else {
 548                         struct netlink_dump_control c = {
 549                                 .module = family->module,
 550                                 .dump = ops->dumpit,
 551                                 .done = ops->done,
 552                         };
 553
 554                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 555                 }
 556
 557                 return rc;
 558         }
 559
 560         if (ops->doit == NULL)
 561                 return -EOPNOTSUPP;
 562
 563         if (family->maxattr && family->parallel_ops) {
 564                 attrbuf = kmalloc((family->maxattr+1) *
 565                                         sizeof(struct nlattr *), GFP_KERNEL);
 566                 if (attrbuf == NULL)
 567                         return -ENOMEM;
 568         } else
 569                 attrbuf = family->attrbuf;
 570
 571         if (attrbuf) {
 572                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 573                                   ops->policy);
 574                 if (err < 0)
 575                         goto out;
 576         }
 577
 578         info.snd_seq = nlh->nlmsg_seq;
 579         info.snd_portid = NETLINK_CB(skb).portid;
 580         info.nlhdr = nlh;
 581         info.genlhdr = nlmsg_data(nlh);
 582         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 583         info.attrs = attrbuf;
 584         genl_info_net_set(&info, net);
 585         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 586
 587         if (family->pre_doit) {
 588                 err = family->pre_doit(ops, skb, &info);
 589                 if (err)
 590                         goto out;
 591         }
 592
 593         err = ops->doit(skb, &info);
 594
 595         if (family->post_doit)
 596                 family->post_doit(ops, skb, &info);
 597
 598 out:
 599         if (family->parallel_ops)
 600                 kfree(attrbuf);
 601
 602         return err;
 603 }
 604
 605 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 606 {
 607         struct genl_family *family;
 608         int err;
 609
 610         family = genl_family_find_byid(nlh->nlmsg_type);
 611         if (family == NULL)
 612                 return -ENOENT;
 613
 614         if (!family->parallel_ops)
 615                 genl_lock();
 616
 617         err = genl_family_rcv_msg(family, skb, nlh);
 618
 619         if (!family->parallel_ops)
 620                 genl_unlock();
 621
 622         return err;
 623 }
 624
 625 static void genl_rcv(struct sk_buff *skb)
 626 {
 627         down_read(&cb_lock);
 628         netlink_rcv_skb(skb, &genl_rcv_msg);
 629         up_read(&cb_lock);
 630 }
 631
 632 /**************************************************************************
 633  * Controller
 634  **************************************************************************/
 635
 636 static struct genl_family genl_ctrl = {
 637         .id = GENL_ID_CTRL,
 638         .name = "nlctrl",
 639         .version = 0x2,
 640         .maxattr = CTRL_ATTR_MAX,
 641         .netnsok = true,
 642 };
 643
 644 static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
 645                           u32 flags, struct sk_buff *skb, u8 cmd)
 646 {
 647         void *hdr;
 648
 649         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 650         if (hdr == NULL)
 651                 return -1;
 652
 653         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 654             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 655             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 656             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 657             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 658                 goto nla_put_failure;
 659
 660         if (family->n_ops) {
 661                 struct nlattr *nla_ops;
 662                 int i;
 663
 664                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 665                 if (nla_ops == NULL)
 666                         goto nla_put_failure;
 667
 668                 for (i = 0; i < family->n_ops; i++) {
 669                         struct nlattr *nest;
 670                         const struct genl_ops *ops = &family->ops[i];
 671                         u32 flags = ops->flags;
 672
 673                         if (ops->dumpit)
 674                                 flags |= GENL_CMD_CAP_DUMP;
 675                         if (ops->doit)
 676                                 flags |= GENL_CMD_CAP_DO;
 677                         if (ops->policy)
 678                                 flags |= GENL_CMD_CAP_HASPOL;
 679
 680                         nest = nla_nest_start(skb, i + 1);
 681                         if (nest == NULL)
 682                                 goto nla_put_failure;
 683
 684                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 685                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, flags))
 686                                 goto nla_put_failure;
 687
 688                         nla_nest_end(skb, nest);
 689                 }
 690
 691                 nla_nest_end(skb, nla_ops);
 692         }
 693
 694         if (!list_empty(&family->mcast_groups)) {
 695                 struct genl_multicast_group *grp;
 696                 struct nlattr *nla_grps;
 697                 int idx = 1;
 698
 699                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 700                 if (nla_grps == NULL)
 701                         goto nla_put_failure;
 702
 703                 list_for_each_entry(grp, &family->mcast_groups, list) {
 704                         struct nlattr *nest;
 705
 706                         nest = nla_nest_start(skb, idx++);
 707                         if (nest == NULL)
 708                                 goto nla_put_failure;
 709
 710                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id) ||
 711                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 712                                            grp->name))
 713                                 goto nla_put_failure;
 714
 715                         nla_nest_end(skb, nest);
 716                 }
 717                 nla_nest_end(skb, nla_grps);
 718         }
 719
 720         return genlmsg_end(skb, hdr);
 721
 722 nla_put_failure:
 723         genlmsg_cancel(skb, hdr);
 724         return -EMSGSIZE;
 725 }
 726
 727 static int ctrl_fill_mcgrp_info(struct genl_multicast_group *grp, u32 portid,
 728                                 u32 seq, u32 flags, struct sk_buff *skb,
 729                                 u8 cmd)
 730 {
 731         void *hdr;
 732         struct nlattr *nla_grps;
 733         struct nlattr *nest;
 734
 735         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 736         if (hdr == NULL)
 737                 return -1;
 738
 739         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, grp->family->name) ||
 740             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, grp->family->id))
 741                 goto nla_put_failure;
 742
 743         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 744         if (nla_grps == NULL)
 745                 goto nla_put_failure;
 746
 747         nest = nla_nest_start(skb, 1);
 748         if (nest == NULL)
 749                 goto nla_put_failure;
 750
 751         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp->id) ||
 752             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 753                            grp->name))
 754                 goto nla_put_failure;
 755
 756         nla_nest_end(skb, nest);
 757         nla_nest_end(skb, nla_grps);
 758
 759         return genlmsg_end(skb, hdr);
 760
 761 nla_put_failure:
 762         genlmsg_cancel(skb, hdr);
 763         return -EMSGSIZE;
 764 }
 765
 766 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 767 {
 768
 769         int i, n = 0;
 770         struct genl_family *rt;
 771         struct net *net = sock_net(skb->sk);
 772         int chains_to_skip = cb->args[0];
 773         int fams_to_skip = cb->args[1];
 774
 775         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
 776                 n = 0;
 777                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 778                         if (!rt->netnsok && !net_eq(net, &init_net))
 779                                 continue;
 780                         if (++n < fams_to_skip)
 781                                 continue;
 782                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 783                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 784                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 785                                 goto errout;
 786                 }
 787
 788                 fams_to_skip = 0;
 789         }
 790
 791 errout:
 792         cb->args[0] = i;
 793         cb->args[1] = n;
 794
 795         return skb->len;
 796 }
 797
 798 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 799                                              u32 portid, int seq, u8 cmd)
 800 {
 801         struct sk_buff *skb;
 802         int err;
 803
 804         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 805         if (skb == NULL)
 806                 return ERR_PTR(-ENOBUFS);
 807
 808         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 809         if (err < 0) {
 810                 nlmsg_free(skb);
 811                 return ERR_PTR(err);
 812         }
 813
 814         return skb;
 815 }
 816
 817 static struct sk_buff *ctrl_build_mcgrp_msg(struct genl_multicast_group *grp,
 818                                             u32 portid, int seq, u8 cmd)
 819 {
 820         struct sk_buff *skb;
 821         int err;
 822
 823         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 824         if (skb == NULL)
 825                 return ERR_PTR(-ENOBUFS);
 826
 827         err = ctrl_fill_mcgrp_info(grp, portid, seq, 0, skb, cmd);
 828         if (err < 0) {
 829                 nlmsg_free(skb);
 830                 return ERR_PTR(err);
 831         }
 832
 833         return skb;
 834 }
 835
 836 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 837         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 838         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 839                                     .len = GENL_NAMSIZ - 1 },
 840 };
 841
 842 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 843 {
 844         struct sk_buff *msg;
 845         struct genl_family *res = NULL;
 846         int err = -EINVAL;
 847
 848         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 849                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 850                 res = genl_family_find_byid(id);
 851                 err = -ENOENT;
 852         }
 853
 854         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 855                 char *name;
 856
 857                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 858                 res = genl_family_find_byname(name);
 859 #ifdef CONFIG_MODULES
 860                 if (res == NULL) {
 861                         genl_unlock();
 862                         up_read(&cb_lock);
 863                         request_module("net-pf-%d-proto-%d-family-%s",
 864                                        PF_NETLINK, NETLINK_GENERIC, name);
 865                         down_read(&cb_lock);
 866                         genl_lock();
 867                         res = genl_family_find_byname(name);
 868                 }
 869 #endif
 870                 err = -ENOENT;
 871         }
 872
 873         if (res == NULL)
 874                 return err;
 875
 876         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 877                 /* family doesn't exist here */
 878                 return -ENOENT;
 879         }
 880
 881         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 882                                     CTRL_CMD_NEWFAMILY);
 883         if (IS_ERR(msg))
 884                 return PTR_ERR(msg);
 885
 886         return genlmsg_reply(msg, info);
 887 }
 888
 889 static int genl_ctrl_event(int event, void *data)
 890 {
 891         struct sk_buff *msg;
 892         struct genl_family *family;
 893         struct genl_multicast_group *grp;
 894
 895         /* genl is still initialising */
 896         if (!init_net.genl_sock)
 897                 return 0;
 898
 899         switch (event) {
 900         case CTRL_CMD_NEWFAMILY:
 901         case CTRL_CMD_DELFAMILY:
 902                 family = data;
 903                 msg = ctrl_build_family_msg(family, 0, 0, event);
 904                 break;
 905         case CTRL_CMD_NEWMCAST_GRP:
 906         case CTRL_CMD_DELMCAST_GRP:
 907                 grp = data;
 908                 family = grp->family;
 909                 msg = ctrl_build_mcgrp_msg(data, 0, 0, event);
 910                 break;
 911         default:
 912                 return -EINVAL;
 913         }
 914
 915         if (IS_ERR(msg))
 916                 return PTR_ERR(msg);
 917
 918         if (!family->netnsok) {
 919                 genlmsg_multicast_netns(&init_net, msg, 0,
 920                                         GENL_ID_CTRL, GFP_KERNEL);
 921         } else {
 922                 rcu_read_lock();
 923                 genlmsg_multicast_allns(msg, 0, GENL_ID_CTRL, GFP_ATOMIC);
 924                 rcu_read_unlock();
 925         }
 926
 927         return 0;
 928 }
 929
 930 static struct genl_ops genl_ctrl_ops = {
 931         .cmd            = CTRL_CMD_GETFAMILY,
 932         .doit           = ctrl_getfamily,
 933         .dumpit         = ctrl_dumpfamily,
 934         .policy         = ctrl_policy,
 935 };
 936
 937 static struct genl_multicast_group notify_grp = {
 938         .name           = "notify",
 939 };
 940
 941 static int __net_init genl_pernet_init(struct net *net)
 942 {
 943         struct netlink_kernel_cfg cfg = {
 944                 .input          = genl_rcv,
 945                 .flags          = NL_CFG_F_NONROOT_RECV,
 946         };
 947
 948         /* we'll bump the group number right afterwards */
 949         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
 950
 951         if (!net->genl_sock && net_eq(net, &init_net))
 952                 panic("GENL: Cannot initialize generic netlink\n");
 953
 954         if (!net->genl_sock)
 955                 return -ENOMEM;
 956
 957         return 0;
 958 }
 959
 960 static void __net_exit genl_pernet_exit(struct net *net)
 961 {
 962         netlink_kernel_release(net->genl_sock);
 963         net->genl_sock = NULL;
 964 }
 965
 966 static struct pernet_operations genl_pernet_ops = {
 967         .init = genl_pernet_init,
 968         .exit = genl_pernet_exit,
 969 };
 970
 971 static int __init genl_init(void)
 972 {
 973         int i, err;
 974
 975         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 976                 INIT_LIST_HEAD(&family_ht[i]);
 977
 978         err = genl_register_family_with_ops(&genl_ctrl, &genl_ctrl_ops, 1);
 979         if (err < 0)
 980                 goto problem;
 981
 982         err = register_pernet_subsys(&genl_pernet_ops);
 983         if (err)
 984                 goto problem;
 985
 986         err = genl_register_mc_group(&genl_ctrl, &notify_grp);
 987         if (err < 0)
 988                 goto problem;
 989
 990         return 0;
 991
 992 problem:
 993         panic("GENL: Cannot register controller: %d\n", err);
 994 }
 995
 996 subsys_initcall(genl_init);
 997
 998 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
 999                          gfp_t flags)
1000 {
1001         struct sk_buff *tmp;
1002         struct net *net, *prev = NULL;
1003         int err;
1004
1005         for_each_net_rcu(net) {
1006                 if (prev) {
1007                         tmp = skb_clone(skb, flags);
1008                         if (!tmp) {
1009                                 err = -ENOMEM;
1010                                 goto error;
1011                         }
1012                         err = nlmsg_multicast(prev->genl_sock, tmp,
1013                                               portid, group, flags);
1014                         if (err)
1015                                 goto error;
1016                 }
1017
1018                 prev = net;
1019         }
1020
1021         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1022  error:
1023         kfree_skb(skb);
1024         return err;
1025 }
1026
1027 int genlmsg_multicast_allns(struct sk_buff *skb, u32 portid, unsigned int group,
1028                             gfp_t flags)
1029 {
1030         return genlmsg_mcast(skb, portid, group, flags);
1031 }
1032 EXPORT_SYMBOL(genlmsg_multicast_allns);
1033
1034 void genl_notify(struct sk_buff *skb, struct net *net, u32 portid, u32 group,
1035                  struct nlmsghdr *nlh, gfp_t flags)
1036 {
1037         struct sock *sk = net->genl_sock;
1038         int report = 0;
1039
1040         if (nlh)
1041                 report = nlmsg_report(nlh);
1042
1043         nlmsg_notify(sk, skb, portid, group, report, flags);
1044 }
1045 EXPORT_SYMBOL(genl_notify);