net/netlink/genetlink.c

   1 /*
   2  * NETLINK      Generic Netlink Family
   3  *
   4  *              Authors:        Jamal Hadi Salim
   5  *                              Thomas Graf <tgraf@suug.ch>
   6  *                              Johannes Berg <johannes@sipsolutions.net>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/errno.h>
  13 #include <linux/types.h>
  14 #include <linux/socket.h>
  15 #include <linux/string.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/mutex.h>
  18 #include <linux/bitmap.h>
  19 #include <linux/rwsem.h>
  20 #include <net/sock.h>
  21 #include <net/genetlink.h>
  22
  23 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
  24 static DECLARE_RWSEM(cb_lock);
  25
  26 void genl_lock(void)
  27 {
  28         mutex_lock(&genl_mutex);
  29 }
  30 EXPORT_SYMBOL(genl_lock);
  31
  32 void genl_unlock(void)
  33 {
  34         mutex_unlock(&genl_mutex);
  35 }
  36 EXPORT_SYMBOL(genl_unlock);
  37
  38 #ifdef CONFIG_LOCKDEP
  39 int lockdep_genl_is_held(void)
  40 {
  41         return lockdep_is_held(&genl_mutex);
  42 }
  43 EXPORT_SYMBOL(lockdep_genl_is_held);
  44 #endif
  45
  46 static void genl_lock_all(void)
  47 {
  48         down_write(&cb_lock);
  49         genl_lock();
  50 }
  51
  52 static void genl_unlock_all(void)
  53 {
  54         genl_unlock();
  55         up_write(&cb_lock);
  56 }
  57
  58 #define GENL_FAM_TAB_SIZE       16
  59 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
  60
  61 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
  62 /*
  63  * Bitmap of multicast groups that are currently in use.
  64  *
  65  * To avoid an allocation at boot of just one unsigned long,
  66  * declare it global instead.
  67  * Bit 0 is marked as already used since group 0 is invalid.
  68  * Bit 1 is marked as already used since the drop-monitor code
  69  * abuses the API and thinks it can statically use group 1.
  70  * That group will typically conflict with other groups that
  71  * any proper users use.
  72  * Bit 16 is marked as used since it's used for generic netlink
  73  * and the code no longer marks pre-reserved IDs as used.
  74  * Bit 17 is marked as already used since the VFS quota code
  75  * also abused this API and relied on family == group ID, we
  76  * cater to that by giving it a static family and group ID.
  77  * Bit 18 is marked as already used since the PMCRAID driver
  78  * did the same thing as the VFS quota code (maybe copied?)
  79  */
  80 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
  81                                       BIT(GENL_ID_VFS_DQUOT) |
  82                                       BIT(GENL_ID_PMCRAID);
  83 static unsigned long *mc_groups = &mc_group_start;
  84 static unsigned long mc_groups_longs = 1;
  85
  86 static int genl_ctrl_event(int event, struct genl_family *family,
  87                            const struct genl_multicast_group *grp,
  88                            int grp_id);
  89
  90 static inline unsigned int genl_family_hash(unsigned int id)
  91 {
  92         return id & GENL_FAM_TAB_MASK;
  93 }
  94
  95 static inline struct list_head *genl_family_chain(unsigned int id)
  96 {
  97         return &family_ht[genl_family_hash(id)];
  98 }
  99
 100 static struct genl_family *genl_family_find_byid(unsigned int id)
 101 {
 102         struct genl_family *f;
 103
 104         list_for_each_entry(f, genl_family_chain(id), family_list)
 105                 if (f->id == id)
 106                         return f;
 107
 108         return NULL;
 109 }
 110
 111 static struct genl_family *genl_family_find_byname(char *name)
 112 {
 113         struct genl_family *f;
 114         int i;
 115
 116         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 117                 list_for_each_entry(f, genl_family_chain(i), family_list)
 118                         if (strcmp(f->name, name) == 0)
 119                                 return f;
 120
 121         return NULL;
 122 }
 123
 124 static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
 125 {
 126         int i;
 127
 128         for (i = 0; i < family->n_ops; i++)
 129                 if (family->ops[i].cmd == cmd)
 130                         return &family->ops[i];
 131
 132         return NULL;
 133 }
 134
 135 /* Of course we are going to have problems once we hit
 136  * 2^16 alive types, but that can only happen by year 2K
 137 */
 138 static u16 genl_generate_id(void)
 139 {
 140         static u16 id_gen_idx = GENL_MIN_ID;
 141         int i;
 142
 143         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 144                 if (id_gen_idx != GENL_ID_VFS_DQUOT &&
 145                     id_gen_idx != GENL_ID_PMCRAID &&
 146                     !genl_family_find_byid(id_gen_idx))
 147                         return id_gen_idx;
 148                 if (++id_gen_idx > GENL_MAX_ID)
 149                         id_gen_idx = GENL_MIN_ID;
 150         }
 151
 152         return 0;
 153 }
 154
 155 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
 156 {
 157         unsigned long *new_groups;
 158         int start = 0;
 159         int i;
 160         int id;
 161         bool fits;
 162
 163         do {
 164                 if (start == 0)
 165                         id = find_first_zero_bit(mc_groups,
 166                                                  mc_groups_longs *
 167                                                  BITS_PER_LONG);
 168                 else
 169                         id = find_next_zero_bit(mc_groups,
 170                                                 mc_groups_longs * BITS_PER_LONG,
 171                                                 start);
 172
 173                 fits = true;
 174                 for (i = id;
 175                      i < min_t(int, id + n_groups,
 176                                mc_groups_longs * BITS_PER_LONG);
 177                      i++) {
 178                         if (test_bit(i, mc_groups)) {
 179                                 start = i;
 180                                 fits = false;
 181                                 break;
 182                         }
 183                 }
 184
 185                 if (id >= mc_groups_longs * BITS_PER_LONG) {
 186                         unsigned long new_longs = mc_groups_longs +
 187                                                   BITS_TO_LONGS(n_groups);
 188                         size_t nlen = new_longs * sizeof(unsigned long);
 189
 190                         if (mc_groups == &mc_group_start) {
 191                                 new_groups = kzalloc(nlen, GFP_KERNEL);
 192                                 if (!new_groups)
 193                                         return -ENOMEM;
 194                                 mc_groups = new_groups;
 195                                 *mc_groups = mc_group_start;
 196                         } else {
 197                                 new_groups = krealloc(mc_groups, nlen,
 198                                                       GFP_KERNEL);
 199                                 if (!new_groups)
 200                                         return -ENOMEM;
 201                                 mc_groups = new_groups;
 202                                 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
 203                                         mc_groups[mc_groups_longs + i] = 0;
 204                         }
 205                         mc_groups_longs = new_longs;
 206                 }
 207         } while (!fits);
 208
 209         for (i = id; i < id + n_groups; i++)
 210                 set_bit(i, mc_groups);
 211         *first_id = id;
 212         return 0;
 213 }
 214
 215 static struct genl_family genl_ctrl;
 216
 217 static int genl_validate_assign_mc_groups(struct genl_family *family)
 218 {
 219         int first_id;
 220         int n_groups = family->n_mcgrps;
 221         int err = 0, i;
 222         bool groups_allocated = false;
 223
 224         if (!n_groups)
 225                 return 0;
 226
 227         for (i = 0; i < n_groups; i++) {
 228                 const struct genl_multicast_group *grp = &family->mcgrps[i];
 229
 230                 if (WARN_ON(grp->name[0] == '\0'))
 231                         return -EINVAL;
 232                 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
 233                         return -EINVAL;
 234         }
 235
 236         /* special-case our own group and hacks */
 237         if (family == &genl_ctrl) {
 238                 first_id = GENL_ID_CTRL;
 239                 BUG_ON(n_groups != 1);
 240         } else if (strcmp(family->name, "NET_DM") == 0) {
 241                 first_id = 1;
 242                 BUG_ON(n_groups != 1);
 243         } else if (family->id == GENL_ID_VFS_DQUOT) {
 244                 first_id = GENL_ID_VFS_DQUOT;
 245                 BUG_ON(n_groups != 1);
 246         } else if (family->id == GENL_ID_PMCRAID) {
 247                 first_id = GENL_ID_PMCRAID;
 248                 BUG_ON(n_groups != 1);
 249         } else {
 250                 groups_allocated = true;
 251                 err = genl_allocate_reserve_groups(n_groups, &first_id);
 252                 if (err)
 253                         return err;
 254         }
 255
 256         family->mcgrp_offset = first_id;
 257
 258         /* if still initializing, can't and don't need to to realloc bitmaps */
 259         if (!init_net.genl_sock)
 260                 return 0;
 261
 262         if (family->netnsok) {
 263                 struct net *net;
 264
 265                 netlink_table_grab();
 266                 rcu_read_lock();
 267                 for_each_net_rcu(net) {
 268                         err = __netlink_change_ngroups(net->genl_sock,
 269                                         mc_groups_longs * BITS_PER_LONG);
 270                         if (err) {
 271                                 /*
 272                                  * No need to roll back, can only fail if
 273                                  * memory allocation fails and then the
 274                                  * number of _possible_ groups has been
 275                                  * increased on some sockets which is ok.
 276                                  */
 277                                 break;
 278                         }
 279                 }
 280                 rcu_read_unlock();
 281                 netlink_table_ungrab();
 282         } else {
 283                 err = netlink_change_ngroups(init_net.genl_sock,
 284                                              mc_groups_longs * BITS_PER_LONG);
 285         }
 286
 287         if (groups_allocated && err) {
 288                 for (i = 0; i < family->n_mcgrps; i++)
 289                         clear_bit(family->mcgrp_offset + i, mc_groups);
 290         }
 291
 292         return err;
 293 }
 294
 295 static void genl_unregister_mc_groups(struct genl_family *family)
 296 {
 297         struct net *net;
 298         int i;
 299
 300         netlink_table_grab();
 301         rcu_read_lock();
 302         for_each_net_rcu(net) {
 303                 for (i = 0; i < family->n_mcgrps; i++)
 304                         __netlink_clear_multicast_users(
 305                                 net->genl_sock, family->mcgrp_offset + i);
 306         }
 307         rcu_read_unlock();
 308         netlink_table_ungrab();
 309
 310         for (i = 0; i < family->n_mcgrps; i++) {
 311                 int grp_id = family->mcgrp_offset + i;
 312
 313                 if (grp_id != 1)
 314                         clear_bit(grp_id, mc_groups);
 315                 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
 316                                 &family->mcgrps[i], grp_id);
 317         }
 318 }
 319
 320 static int genl_validate_ops(struct genl_family *family)
 321 {
 322         const struct genl_ops *ops = family->ops;
 323         unsigned int n_ops = family->n_ops;
 324         int i, j;
 325
 326         if (WARN_ON(n_ops && !ops))
 327                 return -EINVAL;
 328
 329         if (!n_ops)
 330                 return 0;
 331
 332         for (i = 0; i < n_ops; i++) {
 333                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 334                         return -EINVAL;
 335                 for (j = i + 1; j < n_ops; j++)
 336                         if (ops[i].cmd == ops[j].cmd)
 337                                 return -EINVAL;
 338         }
 339
 340         /* family is not registered yet, so no locking needed */
 341         family->ops = ops;
 342         family->n_ops = n_ops;
 343
 344         return 0;
 345 }
 346
 347 /**
 348  * __genl_register_family - register a generic netlink family
 349  * @family: generic netlink family
 350  *
 351  * Registers the specified family after validating it first. Only one
 352  * family may be registered with the same family name or identifier.
 353  * The family id may equal GENL_ID_GENERATE causing an unique id to
 354  * be automatically generated and assigned.
 355  *
 356  * The family's ops array must already be assigned, you can use the
 357  * genl_register_family_with_ops() helper function.
 358  *
 359  * Return 0 on success or a negative error code.
 360  */
 361 int __genl_register_family(struct genl_family *family)
 362 {
 363         int err = -EINVAL, i;
 364
 365         if (family->id && family->id < GENL_MIN_ID)
 366                 goto errout;
 367
 368         if (family->id > GENL_MAX_ID)
 369                 goto errout;
 370
 371         err = genl_validate_ops(family);
 372         if (err)
 373                 return err;
 374
 375         genl_lock_all();
 376
 377         if (genl_family_find_byname(family->name)) {
 378                 err = -EEXIST;
 379                 goto errout_locked;
 380         }
 381
 382         if (family->id == GENL_ID_GENERATE) {
 383                 u16 newid = genl_generate_id();
 384
 385                 if (!newid) {
 386                         err = -ENOMEM;
 387                         goto errout_locked;
 388                 }
 389
 390                 family->id = newid;
 391         } else if (genl_family_find_byid(family->id)) {
 392                 err = -EEXIST;
 393                 goto errout_locked;
 394         }
 395
 396         if (family->maxattr && !family->parallel_ops) {
 397                 family->attrbuf = kmalloc((family->maxattr+1) *
 398                                         sizeof(struct nlattr *), GFP_KERNEL);
 399                 if (family->attrbuf == NULL) {
 400                         err = -ENOMEM;
 401                         goto errout_locked;
 402                 }
 403         } else
 404                 family->attrbuf = NULL;
 405
 406         err = genl_validate_assign_mc_groups(family);
 407         if (err)
 408                 goto errout_locked;
 409
 410         list_add_tail(&family->family_list, genl_family_chain(family->id));
 411         genl_unlock_all();
 412
 413         /* send all events */
 414         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 415         for (i = 0; i < family->n_mcgrps; i++)
 416                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 417                                 &family->mcgrps[i], family->mcgrp_offset + i);
 418
 419         return 0;
 420
 421 errout_locked:
 422         genl_unlock_all();
 423 errout:
 424         return err;
 425 }
 426 EXPORT_SYMBOL(__genl_register_family);
 427
 428 /**
 429  * genl_unregister_family - unregister generic netlink family
 430  * @family: generic netlink family
 431  *
 432  * Unregisters the specified family.
 433  *
 434  * Returns 0 on success or a negative error code.
 435  */
 436 int genl_unregister_family(struct genl_family *family)
 437 {
 438         struct genl_family *rc;
 439
 440         genl_lock_all();
 441
 442         genl_unregister_mc_groups(family);
 443
 444         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 445                 if (family->id != rc->id || strcmp(rc->name, family->name))
 446                         continue;
 447
 448                 list_del(&rc->family_list);
 449                 family->n_ops = 0;
 450                 genl_unlock_all();
 451
 452                 kfree(family->attrbuf);
 453                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 454                 return 0;
 455         }
 456
 457         genl_unlock_all();
 458
 459         return -ENOENT;
 460 }
 461 EXPORT_SYMBOL(genl_unregister_family);
 462
 463 /**
 464  * genlmsg_new_unicast - Allocate generic netlink message for unicast
 465  * @payload: size of the message payload
 466  * @info: information on destination
 467  * @flags: the type of memory to allocate
 468  *
 469  * Allocates a new sk_buff large enough to cover the specified payload
 470  * plus required Netlink headers. Will check receiving socket for
 471  * memory mapped i/o capability and use it if enabled. Will fall back
 472  * to non-mapped skb if message size exceeds the frame size of the ring.
 473  */
 474 struct sk_buff *genlmsg_new_unicast(size_t payload, struct genl_info *info,
 475                                     gfp_t flags)
 476 {
 477         size_t len = nlmsg_total_size(genlmsg_total_size(payload));
 478
 479         return netlink_alloc_skb(info->dst_sk, len, info->snd_portid, flags);
 480 }
 481 EXPORT_SYMBOL_GPL(genlmsg_new_unicast);
 482
 483 /**
 484  * genlmsg_put - Add generic netlink header to netlink message
 485  * @skb: socket buffer holding the message
 486  * @portid: netlink portid the message is addressed to
 487  * @seq: sequence number (usually the one of the sender)
 488  * @family: generic netlink family
 489  * @flags: netlink message flags
 490  * @cmd: generic netlink command
 491  *
 492  * Returns pointer to user specific header
 493  */
 494 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 495                                 struct genl_family *family, int flags, u8 cmd)
 496 {
 497         struct nlmsghdr *nlh;
 498         struct genlmsghdr *hdr;
 499
 500         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 501                         family->hdrsize, flags);
 502         if (nlh == NULL)
 503                 return NULL;
 504
 505         hdr = nlmsg_data(nlh);
 506         hdr->cmd = cmd;
 507         hdr->version = family->version;
 508         hdr->reserved = 0;
 509
 510         return (char *) hdr + GENL_HDRLEN;
 511 }
 512 EXPORT_SYMBOL(genlmsg_put);
 513
 514 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 515 {
 516         /* our ops are always const - netlink API doesn't propagate that */
 517         const struct genl_ops *ops = cb->data;
 518         int rc;
 519
 520         genl_lock();
 521         rc = ops->dumpit(skb, cb);
 522         genl_unlock();
 523         return rc;
 524 }
 525
 526 static int genl_lock_done(struct netlink_callback *cb)
 527 {
 528         /* our ops are always const - netlink API doesn't propagate that */
 529         const struct genl_ops *ops = cb->data;
 530         int rc = 0;
 531
 532         if (ops->done) {
 533                 genl_lock();
 534                 rc = ops->done(cb);
 535                 genl_unlock();
 536         }
 537         return rc;
 538 }
 539
 540 static int genl_family_rcv_msg(struct genl_family *family,
 541                                struct sk_buff *skb,
 542                                struct nlmsghdr *nlh)
 543 {
 544         const struct genl_ops *ops;
 545         struct net *net = sock_net(skb->sk);
 546         struct genl_info info;
 547         struct genlmsghdr *hdr = nlmsg_data(nlh);
 548         struct nlattr **attrbuf;
 549         int hdrlen, err;
 550
 551         /* this family doesn't exist in this netns */
 552         if (!family->netnsok && !net_eq(net, &init_net))
 553                 return -ENOENT;
 554
 555         hdrlen = GENL_HDRLEN + family->hdrsize;
 556         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 557                 return -EINVAL;
 558
 559         ops = genl_get_cmd(hdr->cmd, family);
 560         if (ops == NULL)
 561                 return -EOPNOTSUPP;
 562
 563         if ((ops->flags & GENL_ADMIN_PERM) &&
 564             !netlink_capable(skb, CAP_NET_ADMIN))
 565                 return -EPERM;
 566
 567         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 568                 int rc;
 569
 570                 if (ops->dumpit == NULL)
 571                         return -EOPNOTSUPP;
 572
 573                 if (!family->parallel_ops) {
 574                         struct netlink_dump_control c = {
 575                                 .module = family->module,
 576                                 /* we have const, but the netlink API doesn't */
 577                                 .data = (void *)ops,
 578                                 .dump = genl_lock_dumpit,
 579                                 .done = genl_lock_done,
 580                         };
 581
 582                         genl_unlock();
 583                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 584                         genl_lock();
 585
 586                 } else {
 587                         struct netlink_dump_control c = {
 588                                 .module = family->module,
 589                                 .dump = ops->dumpit,
 590                                 .done = ops->done,
 591                         };
 592
 593                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 594                 }
 595
 596                 return rc;
 597         }
 598
 599         if (ops->doit == NULL)
 600                 return -EOPNOTSUPP;
 601
 602         if (family->maxattr && family->parallel_ops) {
 603                 attrbuf = kmalloc((family->maxattr+1) *
 604                                         sizeof(struct nlattr *), GFP_KERNEL);
 605                 if (attrbuf == NULL)
 606                         return -ENOMEM;
 607         } else
 608                 attrbuf = family->attrbuf;
 609
 610         if (attrbuf) {
 611                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 612                                   ops->policy);
 613                 if (err < 0)
 614                         goto out;
 615         }
 616
 617         info.snd_seq = nlh->nlmsg_seq;
 618         info.snd_portid = NETLINK_CB(skb).portid;
 619         info.nlhdr = nlh;
 620         info.genlhdr = nlmsg_data(nlh);
 621         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 622         info.attrs = attrbuf;
 623         info.dst_sk = skb->sk;
 624         genl_info_net_set(&info, net);
 625         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 626
 627         if (family->pre_doit) {
 628                 err = family->pre_doit(ops, skb, &info);
 629                 if (err)
 630                         goto out;
 631         }
 632
 633         err = ops->doit(skb, &info);
 634
 635         if (family->post_doit)
 636                 family->post_doit(ops, skb, &info);
 637
 638 out:
 639         if (family->parallel_ops)
 640                 kfree(attrbuf);
 641
 642         return err;
 643 }
 644
 645 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 646 {
 647         struct genl_family *family;
 648         int err;
 649
 650         family = genl_family_find_byid(nlh->nlmsg_type);
 651         if (family == NULL)
 652                 return -ENOENT;
 653
 654         if (!family->parallel_ops)
 655                 genl_lock();
 656
 657         err = genl_family_rcv_msg(family, skb, nlh);
 658
 659         if (!family->parallel_ops)
 660                 genl_unlock();
 661
 662         return err;
 663 }
 664
 665 static void genl_rcv(struct sk_buff *skb)
 666 {
 667         down_read(&cb_lock);
 668         netlink_rcv_skb(skb, &genl_rcv_msg);
 669         up_read(&cb_lock);
 670 }
 671
 672 /**************************************************************************
 673  * Controller
 674  **************************************************************************/
 675
 676 static struct genl_family genl_ctrl = {
 677         .id = GENL_ID_CTRL,
 678         .name = "nlctrl",
 679         .version = 0x2,
 680         .maxattr = CTRL_ATTR_MAX,
 681         .netnsok = true,
 682 };
 683
 684 static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
 685                           u32 flags, struct sk_buff *skb, u8 cmd)
 686 {
 687         void *hdr;
 688
 689         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 690         if (hdr == NULL)
 691                 return -1;
 692
 693         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 694             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 695             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 696             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 697             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 698                 goto nla_put_failure;
 699
 700         if (family->n_ops) {
 701                 struct nlattr *nla_ops;
 702                 int i;
 703
 704                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 705                 if (nla_ops == NULL)
 706                         goto nla_put_failure;
 707
 708                 for (i = 0; i < family->n_ops; i++) {
 709                         struct nlattr *nest;
 710                         const struct genl_ops *ops = &family->ops[i];
 711                         u32 op_flags = ops->flags;
 712
 713                         if (ops->dumpit)
 714                                 op_flags |= GENL_CMD_CAP_DUMP;
 715                         if (ops->doit)
 716                                 op_flags |= GENL_CMD_CAP_DO;
 717                         if (ops->policy)
 718                                 op_flags |= GENL_CMD_CAP_HASPOL;
 719
 720                         nest = nla_nest_start(skb, i + 1);
 721                         if (nest == NULL)
 722                                 goto nla_put_failure;
 723
 724                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 725                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 726                                 goto nla_put_failure;
 727
 728                         nla_nest_end(skb, nest);
 729                 }
 730
 731                 nla_nest_end(skb, nla_ops);
 732         }
 733
 734         if (family->n_mcgrps) {
 735                 struct nlattr *nla_grps;
 736                 int i;
 737
 738                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 739                 if (nla_grps == NULL)
 740                         goto nla_put_failure;
 741
 742                 for (i = 0; i < family->n_mcgrps; i++) {
 743                         struct nlattr *nest;
 744                         const struct genl_multicast_group *grp;
 745
 746                         grp = &family->mcgrps[i];
 747
 748                         nest = nla_nest_start(skb, i + 1);
 749                         if (nest == NULL)
 750                                 goto nla_put_failure;
 751
 752                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 753                                         family->mcgrp_offset + i) ||
 754                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 755                                            grp->name))
 756                                 goto nla_put_failure;
 757
 758                         nla_nest_end(skb, nest);
 759                 }
 760                 nla_nest_end(skb, nla_grps);
 761         }
 762
 763         return genlmsg_end(skb, hdr);
 764
 765 nla_put_failure:
 766         genlmsg_cancel(skb, hdr);
 767         return -EMSGSIZE;
 768 }
 769
 770 static int ctrl_fill_mcgrp_info(struct genl_family *family,
 771                                 const struct genl_multicast_group *grp,
 772                                 int grp_id, u32 portid, u32 seq, u32 flags,
 773                                 struct sk_buff *skb, u8 cmd)
 774 {
 775         void *hdr;
 776         struct nlattr *nla_grps;
 777         struct nlattr *nest;
 778
 779         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 780         if (hdr == NULL)
 781                 return -1;
 782
 783         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 784             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 785                 goto nla_put_failure;
 786
 787         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 788         if (nla_grps == NULL)
 789                 goto nla_put_failure;
 790
 791         nest = nla_nest_start(skb, 1);
 792         if (nest == NULL)
 793                 goto nla_put_failure;
 794
 795         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 796             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 797                            grp->name))
 798                 goto nla_put_failure;
 799
 800         nla_nest_end(skb, nest);
 801         nla_nest_end(skb, nla_grps);
 802
 803         return genlmsg_end(skb, hdr);
 804
 805 nla_put_failure:
 806         genlmsg_cancel(skb, hdr);
 807         return -EMSGSIZE;
 808 }
 809
 810 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 811 {
 812
 813         int i, n = 0;
 814         struct genl_family *rt;
 815         struct net *net = sock_net(skb->sk);
 816         int chains_to_skip = cb->args[0];
 817         int fams_to_skip = cb->args[1];
 818
 819         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
 820                 n = 0;
 821                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 822                         if (!rt->netnsok && !net_eq(net, &init_net))
 823                                 continue;
 824                         if (++n < fams_to_skip)
 825                                 continue;
 826                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 827                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 828                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 829                                 goto errout;
 830                 }
 831
 832                 fams_to_skip = 0;
 833         }
 834
 835 errout:
 836         cb->args[0] = i;
 837         cb->args[1] = n;
 838
 839         return skb->len;
 840 }
 841
 842 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 843                                              u32 portid, int seq, u8 cmd)
 844 {
 845         struct sk_buff *skb;
 846         int err;
 847
 848         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 849         if (skb == NULL)
 850                 return ERR_PTR(-ENOBUFS);
 851
 852         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 853         if (err < 0) {
 854                 nlmsg_free(skb);
 855                 return ERR_PTR(err);
 856         }
 857
 858         return skb;
 859 }
 860
 861 static struct sk_buff *
 862 ctrl_build_mcgrp_msg(struct genl_family *family,
 863                      const struct genl_multicast_group *grp,
 864                      int grp_id, u32 portid, int seq, u8 cmd)
 865 {
 866         struct sk_buff *skb;
 867         int err;
 868
 869         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 870         if (skb == NULL)
 871                 return ERR_PTR(-ENOBUFS);
 872
 873         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 874                                    seq, 0, skb, cmd);
 875         if (err < 0) {
 876                 nlmsg_free(skb);
 877                 return ERR_PTR(err);
 878         }
 879
 880         return skb;
 881 }
 882
 883 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 884         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 885         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 886                                     .len = GENL_NAMSIZ - 1 },
 887 };
 888
 889 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 890 {
 891         struct sk_buff *msg;
 892         struct genl_family *res = NULL;
 893         int err = -EINVAL;
 894
 895         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 896                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 897                 res = genl_family_find_byid(id);
 898                 err = -ENOENT;
 899         }
 900
 901         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 902                 char *name;
 903
 904                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 905                 res = genl_family_find_byname(name);
 906 #ifdef CONFIG_MODULES
 907                 if (res == NULL) {
 908                         genl_unlock();
 909                         up_read(&cb_lock);
 910                         request_module("net-pf-%d-proto-%d-family-%s",
 911                                        PF_NETLINK, NETLINK_GENERIC, name);
 912                         down_read(&cb_lock);
 913                         genl_lock();
 914                         res = genl_family_find_byname(name);
 915                 }
 916 #endif
 917                 err = -ENOENT;
 918         }
 919
 920         if (res == NULL)
 921                 return err;
 922
 923         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 924                 /* family doesn't exist here */
 925                 return -ENOENT;
 926         }
 927
 928         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 929                                     CTRL_CMD_NEWFAMILY);
 930         if (IS_ERR(msg))
 931                 return PTR_ERR(msg);
 932
 933         return genlmsg_reply(msg, info);
 934 }
 935
 936 static int genl_ctrl_event(int event, struct genl_family *family,
 937                            const struct genl_multicast_group *grp,
 938                            int grp_id)
 939 {
 940         struct sk_buff *msg;
 941
 942         /* genl is still initialising */
 943         if (!init_net.genl_sock)
 944                 return 0;
 945
 946         switch (event) {
 947         case CTRL_CMD_NEWFAMILY:
 948         case CTRL_CMD_DELFAMILY:
 949                 WARN_ON(grp);
 950                 msg = ctrl_build_family_msg(family, 0, 0, event);
 951                 break;
 952         case CTRL_CMD_NEWMCAST_GRP:
 953         case CTRL_CMD_DELMCAST_GRP:
 954                 BUG_ON(!grp);
 955                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 956                 break;
 957         default:
 958                 return -EINVAL;
 959         }
 960
 961         if (IS_ERR(msg))
 962                 return PTR_ERR(msg);
 963
 964         if (!family->netnsok) {
 965                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 966                                         0, GFP_KERNEL);
 967         } else {
 968                 rcu_read_lock();
 969                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 970                                         0, GFP_ATOMIC);
 971                 rcu_read_unlock();
 972         }
 973
 974         return 0;
 975 }
 976
 977 static struct genl_ops genl_ctrl_ops[] = {
 978         {
 979                 .cmd            = CTRL_CMD_GETFAMILY,
 980                 .doit           = ctrl_getfamily,
 981                 .dumpit         = ctrl_dumpfamily,
 982                 .policy         = ctrl_policy,
 983         },
 984 };
 985
 986 static struct genl_multicast_group genl_ctrl_groups[] = {
 987         { .name = "notify", },
 988 };
 989
 990 static int __net_init genl_pernet_init(struct net *net)
 991 {
 992         struct netlink_kernel_cfg cfg = {
 993                 .input          = genl_rcv,
 994                 .flags          = NL_CFG_F_NONROOT_RECV,
 995         };
 996
 997         /* we'll bump the group number right afterwards */
 998         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
 999
1000         if (!net->genl_sock && net_eq(net, &init_net))
1001                 panic("GENL: Cannot initialize generic netlink\n");
1002
1003         if (!net->genl_sock)
1004                 return -ENOMEM;
1005
1006         return 0;
1007 }
1008
1009 static void __net_exit genl_pernet_exit(struct net *net)
1010 {
1011         netlink_kernel_release(net->genl_sock);
1012         net->genl_sock = NULL;
1013 }
1014
1015 static struct pernet_operations genl_pernet_ops = {
1016         .init = genl_pernet_init,
1017         .exit = genl_pernet_exit,
1018 };
1019
1020 static int __init genl_init(void)
1021 {
1022         int i, err;
1023
1024         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
1025                 INIT_LIST_HEAD(&family_ht[i]);
1026
1027         err = genl_register_family_with_ops_groups(&genl_ctrl, genl_ctrl_ops,
1028                                                    genl_ctrl_groups);
1029         if (err < 0)
1030                 goto problem;
1031
1032         err = register_pernet_subsys(&genl_pernet_ops);
1033         if (err)
1034                 goto problem;
1035
1036         return 0;
1037
1038 problem:
1039         panic("GENL: Cannot register controller: %d\n", err);
1040 }
1041
1042 subsys_initcall(genl_init);
1043
1044 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1045                          gfp_t flags)
1046 {
1047         struct sk_buff *tmp;
1048         struct net *net, *prev = NULL;
1049         int err;
1050
1051         for_each_net_rcu(net) {
1052                 if (prev) {
1053                         tmp = skb_clone(skb, flags);
1054                         if (!tmp) {
1055                                 err = -ENOMEM;
1056                                 goto error;
1057                         }
1058                         err = nlmsg_multicast(prev->genl_sock, tmp,
1059                                               portid, group, flags);
1060                         if (err)
1061                                 goto error;
1062                 }
1063
1064                 prev = net;
1065         }
1066
1067         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1068  error:
1069         kfree_skb(skb);
1070         return err;
1071 }
1072
1073 int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb,
1074                             u32 portid, unsigned int group, gfp_t flags)
1075 {
1076         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1077                 return -EINVAL;
1078         group = family->mcgrp_offset + group;
1079         return genlmsg_mcast(skb, portid, group, flags);
1080 }
1081 EXPORT_SYMBOL(genlmsg_multicast_allns);
1082
1083 void genl_notify(struct genl_family *family,
1084                  struct sk_buff *skb, struct net *net, u32 portid, u32 group,
1085                  struct nlmsghdr *nlh, gfp_t flags)
1086 {
1087         struct sock *sk = net->genl_sock;
1088         int report = 0;
1089
1090         if (nlh)
1091                 report = nlmsg_report(nlh);
1092
1093         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1094                 return;
1095         group = family->mcgrp_offset + group;
1096         nlmsg_notify(sk, skb, portid, group, report, flags);
1097 }
1098 EXPORT_SYMBOL(genl_notify);