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 atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
  27 DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
  28
  29 void genl_lock(void)
  30 {
  31         mutex_lock(&genl_mutex);
  32 }
  33 EXPORT_SYMBOL(genl_lock);
  34
  35 void genl_unlock(void)
  36 {
  37         mutex_unlock(&genl_mutex);
  38 }
  39 EXPORT_SYMBOL(genl_unlock);
  40
  41 #ifdef CONFIG_LOCKDEP
  42 int lockdep_genl_is_held(void)
  43 {
  44         return lockdep_is_held(&genl_mutex);
  45 }
  46 EXPORT_SYMBOL(lockdep_genl_is_held);
  47 #endif
  48
  49 static void genl_lock_all(void)
  50 {
  51         down_write(&cb_lock);
  52         genl_lock();
  53 }
  54
  55 static void genl_unlock_all(void)
  56 {
  57         genl_unlock();
  58         up_write(&cb_lock);
  59 }
  60
  61 #define GENL_FAM_TAB_SIZE       16
  62 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
  63
  64 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
  65 /*
  66  * Bitmap of multicast groups that are currently in use.
  67  *
  68  * To avoid an allocation at boot of just one unsigned long,
  69  * declare it global instead.
  70  * Bit 0 is marked as already used since group 0 is invalid.
  71  * Bit 1 is marked as already used since the drop-monitor code
  72  * abuses the API and thinks it can statically use group 1.
  73  * That group will typically conflict with other groups that
  74  * any proper users use.
  75  * Bit 16 is marked as used since it's used for generic netlink
  76  * and the code no longer marks pre-reserved IDs as used.
  77  * Bit 17 is marked as already used since the VFS quota code
  78  * also abused this API and relied on family == group ID, we
  79  * cater to that by giving it a static family and group ID.
  80  * Bit 18 is marked as already used since the PMCRAID driver
  81  * did the same thing as the VFS quota code (maybe copied?)
  82  */
  83 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
  84                                       BIT(GENL_ID_VFS_DQUOT) |
  85                                       BIT(GENL_ID_PMCRAID);
  86 static unsigned long *mc_groups = &mc_group_start;
  87 static unsigned long mc_groups_longs = 1;
  88
  89 static int genl_ctrl_event(int event, struct genl_family *family,
  90                            const struct genl_multicast_group *grp,
  91                            int grp_id);
  92
  93 static inline unsigned int genl_family_hash(unsigned int id)
  94 {
  95         return id & GENL_FAM_TAB_MASK;
  96 }
  97
  98 static inline struct list_head *genl_family_chain(unsigned int id)
  99 {
 100         return &family_ht[genl_family_hash(id)];
 101 }
 102
 103 static struct genl_family *genl_family_find_byid(unsigned int id)
 104 {
 105         struct genl_family *f;
 106
 107         list_for_each_entry(f, genl_family_chain(id), family_list)
 108                 if (f->id == id)
 109                         return f;
 110
 111         return NULL;
 112 }
 113
 114 static struct genl_family *genl_family_find_byname(char *name)
 115 {
 116         struct genl_family *f;
 117         int i;
 118
 119         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 120                 list_for_each_entry(f, genl_family_chain(i), family_list)
 121                         if (strcmp(f->name, name) == 0)
 122                                 return f;
 123
 124         return NULL;
 125 }
 126
 127 static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
 128 {
 129         int i;
 130
 131         for (i = 0; i < family->n_ops; i++)
 132                 if (family->ops[i].cmd == cmd)
 133                         return &family->ops[i];
 134
 135         return NULL;
 136 }
 137
 138 /* Of course we are going to have problems once we hit
 139  * 2^16 alive types, but that can only happen by year 2K
 140 */
 141 static u16 genl_generate_id(void)
 142 {
 143         static u16 id_gen_idx = GENL_MIN_ID;
 144         int i;
 145
 146         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 147                 if (id_gen_idx != GENL_ID_VFS_DQUOT &&
 148                     id_gen_idx != GENL_ID_PMCRAID &&
 149                     !genl_family_find_byid(id_gen_idx))
 150                         return id_gen_idx;
 151                 if (++id_gen_idx > GENL_MAX_ID)
 152                         id_gen_idx = GENL_MIN_ID;
 153         }
 154
 155         return 0;
 156 }
 157
 158 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
 159 {
 160         unsigned long *new_groups;
 161         int start = 0;
 162         int i;
 163         int id;
 164         bool fits;
 165
 166         do {
 167                 if (start == 0)
 168                         id = find_first_zero_bit(mc_groups,
 169                                                  mc_groups_longs *
 170                                                  BITS_PER_LONG);
 171                 else
 172                         id = find_next_zero_bit(mc_groups,
 173                                                 mc_groups_longs * BITS_PER_LONG,
 174                                                 start);
 175
 176                 fits = true;
 177                 for (i = id;
 178                      i < min_t(int, id + n_groups,
 179                                mc_groups_longs * BITS_PER_LONG);
 180                      i++) {
 181                         if (test_bit(i, mc_groups)) {
 182                                 start = i;
 183                                 fits = false;
 184                                 break;
 185                         }
 186                 }
 187
 188                 if (id >= mc_groups_longs * BITS_PER_LONG) {
 189                         unsigned long new_longs = mc_groups_longs +
 190                                                   BITS_TO_LONGS(n_groups);
 191                         size_t nlen = new_longs * sizeof(unsigned long);
 192
 193                         if (mc_groups == &mc_group_start) {
 194                                 new_groups = kzalloc(nlen, GFP_KERNEL);
 195                                 if (!new_groups)
 196                                         return -ENOMEM;
 197                                 mc_groups = new_groups;
 198                                 *mc_groups = mc_group_start;
 199                         } else {
 200                                 new_groups = krealloc(mc_groups, nlen,
 201                                                       GFP_KERNEL);
 202                                 if (!new_groups)
 203                                         return -ENOMEM;
 204                                 mc_groups = new_groups;
 205                                 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
 206                                         mc_groups[mc_groups_longs + i] = 0;
 207                         }
 208                         mc_groups_longs = new_longs;
 209                 }
 210         } while (!fits);
 211
 212         for (i = id; i < id + n_groups; i++)
 213                 set_bit(i, mc_groups);
 214         *first_id = id;
 215         return 0;
 216 }
 217
 218 static struct genl_family genl_ctrl;
 219
 220 static int genl_validate_assign_mc_groups(struct genl_family *family)
 221 {
 222         int first_id;
 223         int n_groups = family->n_mcgrps;
 224         int err = 0, i;
 225         bool groups_allocated = false;
 226
 227         if (!n_groups)
 228                 return 0;
 229
 230         for (i = 0; i < n_groups; i++) {
 231                 const struct genl_multicast_group *grp = &family->mcgrps[i];
 232
 233                 if (WARN_ON(grp->name[0] == '\0'))
 234                         return -EINVAL;
 235                 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
 236                         return -EINVAL;
 237         }
 238
 239         /* special-case our own group and hacks */
 240         if (family == &genl_ctrl) {
 241                 first_id = GENL_ID_CTRL;
 242                 BUG_ON(n_groups != 1);
 243         } else if (strcmp(family->name, "NET_DM") == 0) {
 244                 first_id = 1;
 245                 BUG_ON(n_groups != 1);
 246         } else if (family->id == GENL_ID_VFS_DQUOT) {
 247                 first_id = GENL_ID_VFS_DQUOT;
 248                 BUG_ON(n_groups != 1);
 249         } else if (family->id == GENL_ID_PMCRAID) {
 250                 first_id = GENL_ID_PMCRAID;
 251                 BUG_ON(n_groups != 1);
 252         } else {
 253                 groups_allocated = true;
 254                 err = genl_allocate_reserve_groups(n_groups, &first_id);
 255                 if (err)
 256                         return err;
 257         }
 258
 259         family->mcgrp_offset = first_id;
 260
 261         /* if still initializing, can't and don't need to to realloc bitmaps */
 262         if (!init_net.genl_sock)
 263                 return 0;
 264
 265         if (family->netnsok) {
 266                 struct net *net;
 267
 268                 netlink_table_grab();
 269                 rcu_read_lock();
 270                 for_each_net_rcu(net) {
 271                         err = __netlink_change_ngroups(net->genl_sock,
 272                                         mc_groups_longs * BITS_PER_LONG);
 273                         if (err) {
 274                                 /*
 275                                  * No need to roll back, can only fail if
 276                                  * memory allocation fails and then the
 277                                  * number of _possible_ groups has been
 278                                  * increased on some sockets which is ok.
 279                                  */
 280                                 break;
 281                         }
 282                 }
 283                 rcu_read_unlock();
 284                 netlink_table_ungrab();
 285         } else {
 286                 err = netlink_change_ngroups(init_net.genl_sock,
 287                                              mc_groups_longs * BITS_PER_LONG);
 288         }
 289
 290         if (groups_allocated && err) {
 291                 for (i = 0; i < family->n_mcgrps; i++)
 292                         clear_bit(family->mcgrp_offset + i, mc_groups);
 293         }
 294
 295         return err;
 296 }
 297
 298 static void genl_unregister_mc_groups(struct genl_family *family)
 299 {
 300         struct net *net;
 301         int i;
 302
 303         netlink_table_grab();
 304         rcu_read_lock();
 305         for_each_net_rcu(net) {
 306                 for (i = 0; i < family->n_mcgrps; i++)
 307                         __netlink_clear_multicast_users(
 308                                 net->genl_sock, family->mcgrp_offset + i);
 309         }
 310         rcu_read_unlock();
 311         netlink_table_ungrab();
 312
 313         for (i = 0; i < family->n_mcgrps; i++) {
 314                 int grp_id = family->mcgrp_offset + i;
 315
 316                 if (grp_id != 1)
 317                         clear_bit(grp_id, mc_groups);
 318                 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
 319                                 &family->mcgrps[i], grp_id);
 320         }
 321 }
 322
 323 static int genl_validate_ops(const struct genl_family *family)
 324 {
 325         const struct genl_ops *ops = family->ops;
 326         unsigned int n_ops = family->n_ops;
 327         int i, j;
 328
 329         if (WARN_ON(n_ops && !ops))
 330                 return -EINVAL;
 331
 332         if (!n_ops)
 333                 return 0;
 334
 335         for (i = 0; i < n_ops; i++) {
 336                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 337                         return -EINVAL;
 338                 for (j = i + 1; j < n_ops; j++)
 339                         if (ops[i].cmd == ops[j].cmd)
 340                                 return -EINVAL;
 341         }
 342
 343         return 0;
 344 }
 345
 346 /**
 347  * __genl_register_family - register a generic netlink family
 348  * @family: generic netlink family
 349  *
 350  * Registers the specified family after validating it first. Only one
 351  * family may be registered with the same family name or identifier.
 352  * The family id may equal GENL_ID_GENERATE causing an unique id to
 353  * be automatically generated and assigned.
 354  *
 355  * The family's ops array must already be assigned, you can use the
 356  * genl_register_family_with_ops() helper function.
 357  *
 358  * Return 0 on success or a negative error code.
 359  */
 360 int __genl_register_family(struct genl_family *family)
 361 {
 362         int err = -EINVAL, i;
 363
 364         if (family->id && family->id < GENL_MIN_ID)
 365                 goto errout;
 366
 367         if (family->id > GENL_MAX_ID)
 368                 goto errout;
 369
 370         err = genl_validate_ops(family);
 371         if (err)
 372                 return err;
 373
 374         genl_lock_all();
 375
 376         if (genl_family_find_byname(family->name)) {
 377                 err = -EEXIST;
 378                 goto errout_locked;
 379         }
 380
 381         if (family->id == GENL_ID_GENERATE) {
 382                 u16 newid = genl_generate_id();
 383
 384                 if (!newid) {
 385                         err = -ENOMEM;
 386                         goto errout_locked;
 387                 }
 388
 389                 family->id = newid;
 390         } else if (genl_family_find_byid(family->id)) {
 391                 err = -EEXIST;
 392                 goto errout_locked;
 393         }
 394
 395         if (family->maxattr && !family->parallel_ops) {
 396                 family->attrbuf = kmalloc((family->maxattr+1) *
 397                                         sizeof(struct nlattr *), GFP_KERNEL);
 398                 if (family->attrbuf == NULL) {
 399                         err = -ENOMEM;
 400                         goto errout_locked;
 401                 }
 402         } else
 403                 family->attrbuf = NULL;
 404
 405         err = genl_validate_assign_mc_groups(family);
 406         if (err)
 407                 goto errout_locked;
 408
 409         list_add_tail(&family->family_list, genl_family_chain(family->id));
 410         genl_unlock_all();
 411
 412         /* send all events */
 413         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 414         for (i = 0; i < family->n_mcgrps; i++)
 415                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 416                                 &family->mcgrps[i], family->mcgrp_offset + i);
 417
 418         return 0;
 419
 420 errout_locked:
 421         genl_unlock_all();
 422 errout:
 423         return err;
 424 }
 425 EXPORT_SYMBOL(__genl_register_family);
 426
 427 /**
 428  * genl_unregister_family - unregister generic netlink family
 429  * @family: generic netlink family
 430  *
 431  * Unregisters the specified family.
 432  *
 433  * Returns 0 on success or a negative error code.
 434  */
 435 int genl_unregister_family(struct genl_family *family)
 436 {
 437         struct genl_family *rc;
 438
 439         genl_lock_all();
 440
 441         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 442                 if (family->id != rc->id || strcmp(rc->name, family->name))
 443                         continue;
 444
 445                 genl_unregister_mc_groups(family);
 446
 447                 list_del(&rc->family_list);
 448                 family->n_ops = 0;
 449                 up_write(&cb_lock);
 450                 wait_event(genl_sk_destructing_waitq,
 451                            atomic_read(&genl_sk_destructing_cnt) == 0);
 452                 genl_unlock();
 453
 454                 kfree(family->attrbuf);
 455                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 456                 return 0;
 457         }
 458
 459         genl_unlock_all();
 460
 461         return -ENOENT;
 462 }
 463 EXPORT_SYMBOL(genl_unregister_family);
 464
 465 /**
 466  * genlmsg_new_unicast - Allocate generic netlink message for unicast
 467  * @payload: size of the message payload
 468  * @info: information on destination
 469  * @flags: the type of memory to allocate
 470  *
 471  * Allocates a new sk_buff large enough to cover the specified payload
 472  * plus required Netlink headers. Will check receiving socket for
 473  * memory mapped i/o capability and use it if enabled. Will fall back
 474  * to non-mapped skb if message size exceeds the frame size of the ring.
 475  */
 476 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
 477                                     gfp_t flags)
 478 {
 479         size_t len = nlmsg_total_size(genlmsg_total_size(payload));
 480
 481         return netlink_alloc_skb(info->dst_sk, len, info->snd_portid, flags);
 482 }
 483 EXPORT_SYMBOL_GPL(genlmsg_new_unicast);
 484
 485 /**
 486  * genlmsg_put - Add generic netlink header to netlink message
 487  * @skb: socket buffer holding the message
 488  * @portid: netlink portid the message is addressed to
 489  * @seq: sequence number (usually the one of the sender)
 490  * @family: generic netlink family
 491  * @flags: netlink message flags
 492  * @cmd: generic netlink command
 493  *
 494  * Returns pointer to user specific header
 495  */
 496 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 497                                 struct genl_family *family, int flags, u8 cmd)
 498 {
 499         struct nlmsghdr *nlh;
 500         struct genlmsghdr *hdr;
 501
 502         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 503                         family->hdrsize, flags);
 504         if (nlh == NULL)
 505                 return NULL;
 506
 507         hdr = nlmsg_data(nlh);
 508         hdr->cmd = cmd;
 509         hdr->version = family->version;
 510         hdr->reserved = 0;
 511
 512         return (char *) hdr + GENL_HDRLEN;
 513 }
 514 EXPORT_SYMBOL(genlmsg_put);
 515
 516 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 517 {
 518         /* our ops are always const - netlink API doesn't propagate that */
 519         const struct genl_ops *ops = cb->data;
 520         int rc;
 521
 522         genl_lock();
 523         rc = ops->dumpit(skb, cb);
 524         genl_unlock();
 525         return rc;
 526 }
 527
 528 static int genl_lock_done(struct netlink_callback *cb)
 529 {
 530         /* our ops are always const - netlink API doesn't propagate that */
 531         const struct genl_ops *ops = cb->data;
 532         int rc = 0;
 533
 534         if (ops->done) {
 535                 genl_lock();
 536                 rc = ops->done(cb);
 537                 genl_unlock();
 538         }
 539         return rc;
 540 }
 541
 542 static int genl_family_rcv_msg(struct genl_family *family,
 543                                struct sk_buff *skb,
 544                                struct nlmsghdr *nlh)
 545 {
 546         const struct genl_ops *ops;
 547         struct net *net = sock_net(skb->sk);
 548         struct genl_info info;
 549         struct genlmsghdr *hdr = nlmsg_data(nlh);
 550         struct nlattr **attrbuf;
 551         int hdrlen, err;
 552
 553         /* this family doesn't exist in this netns */
 554         if (!family->netnsok && !net_eq(net, &init_net))
 555                 return -ENOENT;
 556
 557         hdrlen = GENL_HDRLEN + family->hdrsize;
 558         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 559                 return -EINVAL;
 560
 561         ops = genl_get_cmd(hdr->cmd, family);
 562         if (ops == NULL)
 563                 return -EOPNOTSUPP;
 564
 565         if ((ops->flags & GENL_ADMIN_PERM) &&
 566             !netlink_capable(skb, CAP_NET_ADMIN))
 567                 return -EPERM;
 568
 569         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 570                 int rc;
 571
 572                 if (ops->dumpit == NULL)
 573                         return -EOPNOTSUPP;
 574
 575                 if (!family->parallel_ops) {
 576                         struct netlink_dump_control c = {
 577                                 .module = family->module,
 578                                 /* we have const, but the netlink API doesn't */
 579                                 .data = (void *)ops,
 580                                 .dump = genl_lock_dumpit,
 581                                 .done = genl_lock_done,
 582                         };
 583
 584                         genl_unlock();
 585                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 586                         genl_lock();
 587
 588                 } else {
 589                         struct netlink_dump_control c = {
 590                                 .module = family->module,
 591                                 .dump = ops->dumpit,
 592                                 .done = ops->done,
 593                         };
 594
 595                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 596                 }
 597
 598                 return rc;
 599         }
 600
 601         if (ops->doit == NULL)
 602                 return -EOPNOTSUPP;
 603
 604         if (family->maxattr && family->parallel_ops) {
 605                 attrbuf = kmalloc((family->maxattr+1) *
 606                                         sizeof(struct nlattr *), GFP_KERNEL);
 607                 if (attrbuf == NULL)
 608                         return -ENOMEM;
 609         } else
 610                 attrbuf = family->attrbuf;
 611
 612         if (attrbuf) {
 613                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 614                                   ops->policy);
 615                 if (err < 0)
 616                         goto out;
 617         }
 618
 619         info.snd_seq = nlh->nlmsg_seq;
 620         info.snd_portid = NETLINK_CB(skb).portid;
 621         info.nlhdr = nlh;
 622         info.genlhdr = nlmsg_data(nlh);
 623         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 624         info.attrs = attrbuf;
 625         info.dst_sk = skb->sk;
 626         genl_info_net_set(&info, net);
 627         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 628
 629         if (family->pre_doit) {
 630                 err = family->pre_doit(ops, skb, &info);
 631                 if (err)
 632                         goto out;
 633         }
 634
 635         err = ops->doit(skb, &info);
 636
 637         if (family->post_doit)
 638                 family->post_doit(ops, skb, &info);
 639
 640 out:
 641         if (family->parallel_ops)
 642                 kfree(attrbuf);
 643
 644         return err;
 645 }
 646
 647 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 648 {
 649         struct genl_family *family;
 650         int err;
 651
 652         family = genl_family_find_byid(nlh->nlmsg_type);
 653         if (family == NULL)
 654                 return -ENOENT;
 655
 656         if (!family->parallel_ops)
 657                 genl_lock();
 658
 659         err = genl_family_rcv_msg(family, skb, nlh);
 660
 661         if (!family->parallel_ops)
 662                 genl_unlock();
 663
 664         return err;
 665 }
 666
 667 static void genl_rcv(struct sk_buff *skb)
 668 {
 669         down_read(&cb_lock);
 670         netlink_rcv_skb(skb, &genl_rcv_msg);
 671         up_read(&cb_lock);
 672 }
 673
 674 /**************************************************************************
 675  * Controller
 676  **************************************************************************/
 677
 678 static struct genl_family genl_ctrl = {
 679         .id = GENL_ID_CTRL,
 680         .name = "nlctrl",
 681         .version = 0x2,
 682         .maxattr = CTRL_ATTR_MAX,
 683         .netnsok = true,
 684 };
 685
 686 static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
 687                           u32 flags, struct sk_buff *skb, u8 cmd)
 688 {
 689         void *hdr;
 690
 691         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 692         if (hdr == NULL)
 693                 return -1;
 694
 695         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 696             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 697             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 698             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 699             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 700                 goto nla_put_failure;
 701
 702         if (family->n_ops) {
 703                 struct nlattr *nla_ops;
 704                 int i;
 705
 706                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 707                 if (nla_ops == NULL)
 708                         goto nla_put_failure;
 709
 710                 for (i = 0; i < family->n_ops; i++) {
 711                         struct nlattr *nest;
 712                         const struct genl_ops *ops = &family->ops[i];
 713                         u32 op_flags = ops->flags;
 714
 715                         if (ops->dumpit)
 716                                 op_flags |= GENL_CMD_CAP_DUMP;
 717                         if (ops->doit)
 718                                 op_flags |= GENL_CMD_CAP_DO;
 719                         if (ops->policy)
 720                                 op_flags |= GENL_CMD_CAP_HASPOL;
 721
 722                         nest = nla_nest_start(skb, i + 1);
 723                         if (nest == NULL)
 724                                 goto nla_put_failure;
 725
 726                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 727                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 728                                 goto nla_put_failure;
 729
 730                         nla_nest_end(skb, nest);
 731                 }
 732
 733                 nla_nest_end(skb, nla_ops);
 734         }
 735
 736         if (family->n_mcgrps) {
 737                 struct nlattr *nla_grps;
 738                 int i;
 739
 740                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 741                 if (nla_grps == NULL)
 742                         goto nla_put_failure;
 743
 744                 for (i = 0; i < family->n_mcgrps; i++) {
 745                         struct nlattr *nest;
 746                         const struct genl_multicast_group *grp;
 747
 748                         grp = &family->mcgrps[i];
 749
 750                         nest = nla_nest_start(skb, i + 1);
 751                         if (nest == NULL)
 752                                 goto nla_put_failure;
 753
 754                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 755                                         family->mcgrp_offset + i) ||
 756                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 757                                            grp->name))
 758                                 goto nla_put_failure;
 759
 760                         nla_nest_end(skb, nest);
 761                 }
 762                 nla_nest_end(skb, nla_grps);
 763         }
 764
 765         genlmsg_end(skb, hdr);
 766         return 0;
 767
 768 nla_put_failure:
 769         genlmsg_cancel(skb, hdr);
 770         return -EMSGSIZE;
 771 }
 772
 773 static int ctrl_fill_mcgrp_info(struct genl_family *family,
 774                                 const struct genl_multicast_group *grp,
 775                                 int grp_id, u32 portid, u32 seq, u32 flags,
 776                                 struct sk_buff *skb, u8 cmd)
 777 {
 778         void *hdr;
 779         struct nlattr *nla_grps;
 780         struct nlattr *nest;
 781
 782         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 783         if (hdr == NULL)
 784                 return -1;
 785
 786         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 787             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 788                 goto nla_put_failure;
 789
 790         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 791         if (nla_grps == NULL)
 792                 goto nla_put_failure;
 793
 794         nest = nla_nest_start(skb, 1);
 795         if (nest == NULL)
 796                 goto nla_put_failure;
 797
 798         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 799             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 800                            grp->name))
 801                 goto nla_put_failure;
 802
 803         nla_nest_end(skb, nest);
 804         nla_nest_end(skb, nla_grps);
 805
 806         genlmsg_end(skb, hdr);
 807         return 0;
 808
 809 nla_put_failure:
 810         genlmsg_cancel(skb, hdr);
 811         return -EMSGSIZE;
 812 }
 813
 814 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 815 {
 816
 817         int i, n = 0;
 818         struct genl_family *rt;
 819         struct net *net = sock_net(skb->sk);
 820         int chains_to_skip = cb->args[0];
 821         int fams_to_skip = cb->args[1];
 822
 823         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
 824                 n = 0;
 825                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 826                         if (!rt->netnsok && !net_eq(net, &init_net))
 827                                 continue;
 828                         if (++n < fams_to_skip)
 829                                 continue;
 830                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 831                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 832                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 833                                 goto errout;
 834                 }
 835
 836                 fams_to_skip = 0;
 837         }
 838
 839 errout:
 840         cb->args[0] = i;
 841         cb->args[1] = n;
 842
 843         return skb->len;
 844 }
 845
 846 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 847                                              u32 portid, int seq, u8 cmd)
 848 {
 849         struct sk_buff *skb;
 850         int err;
 851
 852         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 853         if (skb == NULL)
 854                 return ERR_PTR(-ENOBUFS);
 855
 856         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 857         if (err < 0) {
 858                 nlmsg_free(skb);
 859                 return ERR_PTR(err);
 860         }
 861
 862         return skb;
 863 }
 864
 865 static struct sk_buff *
 866 ctrl_build_mcgrp_msg(struct genl_family *family,
 867                      const struct genl_multicast_group *grp,
 868                      int grp_id, u32 portid, int seq, u8 cmd)
 869 {
 870         struct sk_buff *skb;
 871         int err;
 872
 873         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 874         if (skb == NULL)
 875                 return ERR_PTR(-ENOBUFS);
 876
 877         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 878                                    seq, 0, skb, cmd);
 879         if (err < 0) {
 880                 nlmsg_free(skb);
 881                 return ERR_PTR(err);
 882         }
 883
 884         return skb;
 885 }
 886
 887 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 888         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 889         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 890                                     .len = GENL_NAMSIZ - 1 },
 891 };
 892
 893 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 894 {
 895         struct sk_buff *msg;
 896         struct genl_family *res = NULL;
 897         int err = -EINVAL;
 898
 899         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 900                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 901                 res = genl_family_find_byid(id);
 902                 err = -ENOENT;
 903         }
 904
 905         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 906                 char *name;
 907
 908                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 909                 res = genl_family_find_byname(name);
 910 #ifdef CONFIG_MODULES
 911                 if (res == NULL) {
 912                         genl_unlock();
 913                         up_read(&cb_lock);
 914                         request_module("net-pf-%d-proto-%d-family-%s",
 915                                        PF_NETLINK, NETLINK_GENERIC, name);
 916                         down_read(&cb_lock);
 917                         genl_lock();
 918                         res = genl_family_find_byname(name);
 919                 }
 920 #endif
 921                 err = -ENOENT;
 922         }
 923
 924         if (res == NULL)
 925                 return err;
 926
 927         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 928                 /* family doesn't exist here */
 929                 return -ENOENT;
 930         }
 931
 932         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 933                                     CTRL_CMD_NEWFAMILY);
 934         if (IS_ERR(msg))
 935                 return PTR_ERR(msg);
 936
 937         return genlmsg_reply(msg, info);
 938 }
 939
 940 static int genl_ctrl_event(int event, struct genl_family *family,
 941                            const struct genl_multicast_group *grp,
 942                            int grp_id)
 943 {
 944         struct sk_buff *msg;
 945
 946         /* genl is still initialising */
 947         if (!init_net.genl_sock)
 948                 return 0;
 949
 950         switch (event) {
 951         case CTRL_CMD_NEWFAMILY:
 952         case CTRL_CMD_DELFAMILY:
 953                 WARN_ON(grp);
 954                 msg = ctrl_build_family_msg(family, 0, 0, event);
 955                 break;
 956         case CTRL_CMD_NEWMCAST_GRP:
 957         case CTRL_CMD_DELMCAST_GRP:
 958                 BUG_ON(!grp);
 959                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 960                 break;
 961         default:
 962                 return -EINVAL;
 963         }
 964
 965         if (IS_ERR(msg))
 966                 return PTR_ERR(msg);
 967
 968         if (!family->netnsok) {
 969                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 970                                         0, GFP_KERNEL);
 971         } else {
 972                 rcu_read_lock();
 973                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 974                                         0, GFP_ATOMIC);
 975                 rcu_read_unlock();
 976         }
 977
 978         return 0;
 979 }
 980
 981 static struct genl_ops genl_ctrl_ops[] = {
 982         {
 983                 .cmd            = CTRL_CMD_GETFAMILY,
 984                 .doit           = ctrl_getfamily,
 985                 .dumpit         = ctrl_dumpfamily,
 986                 .policy         = ctrl_policy,
 987         },
 988 };
 989
 990 static struct genl_multicast_group genl_ctrl_groups[] = {
 991         { .name = "notify", },
 992 };
 993
 994 static int genl_bind(struct net *net, int group)
 995 {
 996         int i, err = -ENOENT;
 997
 998         down_read(&cb_lock);
 999         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
1000                 struct genl_family *f;
1001
1002                 list_for_each_entry(f, genl_family_chain(i), family_list) {
1003                         if (group >= f->mcgrp_offset &&
1004                             group < f->mcgrp_offset + f->n_mcgrps) {
1005                                 int fam_grp = group - f->mcgrp_offset;
1006
1007                                 if (!f->netnsok && net != &init_net)
1008                                         err = -ENOENT;
1009                                 else if (f->mcast_bind)
1010                                         err = f->mcast_bind(net, fam_grp);
1011                                 else
1012                                         err = 0;
1013                                 break;
1014                         }
1015                 }
1016         }
1017         up_read(&cb_lock);
1018
1019         return err;
1020 }
1021
1022 static void genl_unbind(struct net *net, int group)
1023 {
1024         int i;
1025
1026         down_read(&cb_lock);
1027         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
1028                 struct genl_family *f;
1029
1030                 list_for_each_entry(f, genl_family_chain(i), family_list) {
1031                         if (group >= f->mcgrp_offset &&
1032                             group < f->mcgrp_offset + f->n_mcgrps) {
1033                                 int fam_grp = group - f->mcgrp_offset;
1034
1035                                 if (f->mcast_unbind)
1036                                         f->mcast_unbind(net, fam_grp);
1037                                 break;
1038                         }
1039                 }
1040         }
1041         up_read(&cb_lock);
1042 }
1043
1044 static int __net_init genl_pernet_init(struct net *net)
1045 {
1046         struct netlink_kernel_cfg cfg = {
1047                 .input          = genl_rcv,
1048                 .flags          = NL_CFG_F_NONROOT_RECV,
1049                 .bind           = genl_bind,
1050                 .unbind         = genl_unbind,
1051         };
1052
1053         /* we'll bump the group number right afterwards */
1054         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1055
1056         if (!net->genl_sock && net_eq(net, &init_net))
1057                 panic("GENL: Cannot initialize generic netlink\n");
1058
1059         if (!net->genl_sock)
1060                 return -ENOMEM;
1061
1062         return 0;
1063 }
1064
1065 static void __net_exit genl_pernet_exit(struct net *net)
1066 {
1067         netlink_kernel_release(net->genl_sock);
1068         net->genl_sock = NULL;
1069 }
1070
1071 static struct pernet_operations genl_pernet_ops = {
1072         .init = genl_pernet_init,
1073         .exit = genl_pernet_exit,
1074 };
1075
1076 static int __init genl_init(void)
1077 {
1078         int i, err;
1079
1080         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
1081                 INIT_LIST_HEAD(&family_ht[i]);
1082
1083         err = genl_register_family_with_ops_groups(&genl_ctrl, genl_ctrl_ops,
1084                                                    genl_ctrl_groups);
1085         if (err < 0)
1086                 goto problem;
1087
1088         err = register_pernet_subsys(&genl_pernet_ops);
1089         if (err)
1090                 goto problem;
1091
1092         return 0;
1093
1094 problem:
1095         panic("GENL: Cannot register controller: %d\n", err);
1096 }
1097
1098 subsys_initcall(genl_init);
1099
1100 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1101                          gfp_t flags)
1102 {
1103         struct sk_buff *tmp;
1104         struct net *net, *prev = NULL;
1105         int err;
1106
1107         for_each_net_rcu(net) {
1108                 if (prev) {
1109                         tmp = skb_clone(skb, flags);
1110                         if (!tmp) {
1111                                 err = -ENOMEM;
1112                                 goto error;
1113                         }
1114                         err = nlmsg_multicast(prev->genl_sock, tmp,
1115                                               portid, group, flags);
1116                         if (err)
1117                                 goto error;
1118                 }
1119
1120                 prev = net;
1121         }
1122
1123         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1124  error:
1125         kfree_skb(skb);
1126         return err;
1127 }
1128
1129 int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb,
1130                             u32 portid, unsigned int group, gfp_t flags)
1131 {
1132         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1133                 return -EINVAL;
1134         group = family->mcgrp_offset + group;
1135         return genlmsg_mcast(skb, portid, group, flags);
1136 }
1137 EXPORT_SYMBOL(genlmsg_multicast_allns);
1138
1139 void genl_notify(struct genl_family *family,
1140                  struct sk_buff *skb, struct net *net, u32 portid, u32 group,
1141                  struct nlmsghdr *nlh, gfp_t flags)
1142 {
1143         struct sock *sk = net->genl_sock;
1144         int report = 0;
1145
1146         if (nlh)
1147                 report = nlmsg_report(nlh);
1148
1149         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1150                 return;
1151         group = family->mcgrp_offset + group;
1152         nlmsg_notify(sk, skb, portid, group, report, flags);
1153 }
1154 EXPORT_SYMBOL(genl_notify);