net/netlink/genetlink.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * NETLINK      Generic Netlink Family
   4  *
   5  *              Authors:        Jamal Hadi Salim
   6  *                              Thomas Graf <tgraf@suug.ch>
   7  *                              Johannes Berg <johannes@sipsolutions.net>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/errno.h>
  14 #include <linux/types.h>
  15 #include <linux/socket.h>
  16 #include <linux/string.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/mutex.h>
  19 #include <linux/bitmap.h>
  20 #include <linux/rwsem.h>
  21 #include <linux/idr.h>
  22 #include <net/sock.h>
  23 #include <net/genetlink.h>
  24
  25 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
  26 static DECLARE_RWSEM(cb_lock);
  27
  28 atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
  29 DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
  30
  31 void genl_lock(void)
  32 {
  33         mutex_lock(&genl_mutex);
  34 }
  35 EXPORT_SYMBOL(genl_lock);
  36
  37 void genl_unlock(void)
  38 {
  39         mutex_unlock(&genl_mutex);
  40 }
  41 EXPORT_SYMBOL(genl_unlock);
  42
  43 #ifdef CONFIG_LOCKDEP
  44 bool lockdep_genl_is_held(void)
  45 {
  46         return lockdep_is_held(&genl_mutex);
  47 }
  48 EXPORT_SYMBOL(lockdep_genl_is_held);
  49 #endif
  50
  51 static void genl_lock_all(void)
  52 {
  53         down_write(&cb_lock);
  54         genl_lock();
  55 }
  56
  57 static void genl_unlock_all(void)
  58 {
  59         genl_unlock();
  60         up_write(&cb_lock);
  61 }
  62
  63 static DEFINE_IDR(genl_fam_idr);
  64
  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, const struct genl_family *family,
  90                            const struct genl_multicast_group *grp,
  91                            int grp_id);
  92
  93 static const struct genl_family *genl_family_find_byid(unsigned int id)
  94 {
  95         return idr_find(&genl_fam_idr, id);
  96 }
  97
  98 static const struct genl_family *genl_family_find_byname(char *name)
  99 {
 100         const struct genl_family *family;
 101         unsigned int id;
 102
 103         idr_for_each_entry(&genl_fam_idr, family, id)
 104                 if (strcmp(family->name, name) == 0)
 105                         return family;
 106
 107         return NULL;
 108 }
 109
 110 static const struct genl_ops *genl_get_cmd(u8 cmd,
 111                                            const struct genl_family *family)
 112 {
 113         int i;
 114
 115         for (i = 0; i < family->n_ops; i++)
 116                 if (family->ops[i].cmd == cmd)
 117                         return &family->ops[i];
 118
 119         return NULL;
 120 }
 121
 122 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
 123 {
 124         unsigned long *new_groups;
 125         int start = 0;
 126         int i;
 127         int id;
 128         bool fits;
 129
 130         do {
 131                 if (start == 0)
 132                         id = find_first_zero_bit(mc_groups,
 133                                                  mc_groups_longs *
 134                                                  BITS_PER_LONG);
 135                 else
 136                         id = find_next_zero_bit(mc_groups,
 137                                                 mc_groups_longs * BITS_PER_LONG,
 138                                                 start);
 139
 140                 fits = true;
 141                 for (i = id;
 142                      i < min_t(int, id + n_groups,
 143                                mc_groups_longs * BITS_PER_LONG);
 144                      i++) {
 145                         if (test_bit(i, mc_groups)) {
 146                                 start = i;
 147                                 fits = false;
 148                                 break;
 149                         }
 150                 }
 151
 152                 if (id + n_groups > mc_groups_longs * BITS_PER_LONG) {
 153                         unsigned long new_longs = mc_groups_longs +
 154                                                   BITS_TO_LONGS(n_groups);
 155                         size_t nlen = new_longs * sizeof(unsigned long);
 156
 157                         if (mc_groups == &mc_group_start) {
 158                                 new_groups = kzalloc(nlen, GFP_KERNEL);
 159                                 if (!new_groups)
 160                                         return -ENOMEM;
 161                                 mc_groups = new_groups;
 162                                 *mc_groups = mc_group_start;
 163                         } else {
 164                                 new_groups = krealloc(mc_groups, nlen,
 165                                                       GFP_KERNEL);
 166                                 if (!new_groups)
 167                                         return -ENOMEM;
 168                                 mc_groups = new_groups;
 169                                 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
 170                                         mc_groups[mc_groups_longs + i] = 0;
 171                         }
 172                         mc_groups_longs = new_longs;
 173                 }
 174         } while (!fits);
 175
 176         for (i = id; i < id + n_groups; i++)
 177                 set_bit(i, mc_groups);
 178         *first_id = id;
 179         return 0;
 180 }
 181
 182 static struct genl_family genl_ctrl;
 183
 184 static int genl_validate_assign_mc_groups(struct genl_family *family)
 185 {
 186         int first_id;
 187         int n_groups = family->n_mcgrps;
 188         int err = 0, i;
 189         bool groups_allocated = false;
 190
 191         if (!n_groups)
 192                 return 0;
 193
 194         for (i = 0; i < n_groups; i++) {
 195                 const struct genl_multicast_group *grp = &family->mcgrps[i];
 196
 197                 if (WARN_ON(grp->name[0] == '\0'))
 198                         return -EINVAL;
 199                 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
 200                         return -EINVAL;
 201         }
 202
 203         /* special-case our own group and hacks */
 204         if (family == &genl_ctrl) {
 205                 first_id = GENL_ID_CTRL;
 206                 BUG_ON(n_groups != 1);
 207         } else if (strcmp(family->name, "NET_DM") == 0) {
 208                 first_id = 1;
 209                 BUG_ON(n_groups != 1);
 210         } else if (family->id == GENL_ID_VFS_DQUOT) {
 211                 first_id = GENL_ID_VFS_DQUOT;
 212                 BUG_ON(n_groups != 1);
 213         } else if (family->id == GENL_ID_PMCRAID) {
 214                 first_id = GENL_ID_PMCRAID;
 215                 BUG_ON(n_groups != 1);
 216         } else {
 217                 groups_allocated = true;
 218                 err = genl_allocate_reserve_groups(n_groups, &first_id);
 219                 if (err)
 220                         return err;
 221         }
 222
 223         family->mcgrp_offset = first_id;
 224
 225         /* if still initializing, can't and don't need to to realloc bitmaps */
 226         if (!init_net.genl_sock)
 227                 return 0;
 228
 229         if (family->netnsok) {
 230                 struct net *net;
 231
 232                 netlink_table_grab();
 233                 rcu_read_lock();
 234                 for_each_net_rcu(net) {
 235                         err = __netlink_change_ngroups(net->genl_sock,
 236                                         mc_groups_longs * BITS_PER_LONG);
 237                         if (err) {
 238                                 /*
 239                                  * No need to roll back, can only fail if
 240                                  * memory allocation fails and then the
 241                                  * number of _possible_ groups has been
 242                                  * increased on some sockets which is ok.
 243                                  */
 244                                 break;
 245                         }
 246                 }
 247                 rcu_read_unlock();
 248                 netlink_table_ungrab();
 249         } else {
 250                 err = netlink_change_ngroups(init_net.genl_sock,
 251                                              mc_groups_longs * BITS_PER_LONG);
 252         }
 253
 254         if (groups_allocated && err) {
 255                 for (i = 0; i < family->n_mcgrps; i++)
 256                         clear_bit(family->mcgrp_offset + i, mc_groups);
 257         }
 258
 259         return err;
 260 }
 261
 262 static void genl_unregister_mc_groups(const struct genl_family *family)
 263 {
 264         struct net *net;
 265         int i;
 266
 267         netlink_table_grab();
 268         rcu_read_lock();
 269         for_each_net_rcu(net) {
 270                 for (i = 0; i < family->n_mcgrps; i++)
 271                         __netlink_clear_multicast_users(
 272                                 net->genl_sock, family->mcgrp_offset + i);
 273         }
 274         rcu_read_unlock();
 275         netlink_table_ungrab();
 276
 277         for (i = 0; i < family->n_mcgrps; i++) {
 278                 int grp_id = family->mcgrp_offset + i;
 279
 280                 if (grp_id != 1)
 281                         clear_bit(grp_id, mc_groups);
 282                 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
 283                                 &family->mcgrps[i], grp_id);
 284         }
 285 }
 286
 287 static int genl_validate_ops(const struct genl_family *family)
 288 {
 289         const struct genl_ops *ops = family->ops;
 290         unsigned int n_ops = family->n_ops;
 291         int i, j;
 292
 293         if (WARN_ON(n_ops && !ops))
 294                 return -EINVAL;
 295
 296         if (!n_ops)
 297                 return 0;
 298
 299         for (i = 0; i < n_ops; i++) {
 300                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 301                         return -EINVAL;
 302                 for (j = i + 1; j < n_ops; j++)
 303                         if (ops[i].cmd == ops[j].cmd)
 304                                 return -EINVAL;
 305         }
 306
 307         return 0;
 308 }
 309
 310 /**
 311  * genl_register_family - register a generic netlink family
 312  * @family: generic netlink family
 313  *
 314  * Registers the specified family after validating it first. Only one
 315  * family may be registered with the same family name or identifier.
 316  *
 317  * The family's ops, multicast groups and module pointer must already
 318  * be assigned.
 319  *
 320  * Return 0 on success or a negative error code.
 321  */
 322 int genl_register_family(struct genl_family *family)
 323 {
 324         int err, i;
 325         int start = GENL_START_ALLOC, end = GENL_MAX_ID;
 326
 327         err = genl_validate_ops(family);
 328         if (err)
 329                 return err;
 330
 331         genl_lock_all();
 332
 333         if (genl_family_find_byname(family->name)) {
 334                 err = -EEXIST;
 335                 goto errout_locked;
 336         }
 337
 338         /*
 339          * Sadly, a few cases need to be special-cased
 340          * due to them having previously abused the API
 341          * and having used their family ID also as their
 342          * multicast group ID, so we use reserved IDs
 343          * for both to be sure we can do that mapping.
 344          */
 345         if (family == &genl_ctrl) {
 346                 /* and this needs to be special for initial family lookups */
 347                 start = end = GENL_ID_CTRL;
 348         } else if (strcmp(family->name, "pmcraid") == 0) {
 349                 start = end = GENL_ID_PMCRAID;
 350         } else if (strcmp(family->name, "VFS_DQUOT") == 0) {
 351                 start = end = GENL_ID_VFS_DQUOT;
 352         }
 353
 354         if (family->maxattr && !family->parallel_ops) {
 355                 family->attrbuf = kmalloc((family->maxattr+1) *
 356                                         sizeof(struct nlattr *), GFP_KERNEL);
 357                 if (family->attrbuf == NULL) {
 358                         err = -ENOMEM;
 359                         goto errout_locked;
 360                 }
 361         } else
 362                 family->attrbuf = NULL;
 363
 364         family->id = idr_alloc(&genl_fam_idr, family,
 365                                start, end + 1, GFP_KERNEL);
 366         if (family->id < 0) {
 367                 err = family->id;
 368                 goto errout_locked;
 369         }
 370
 371         err = genl_validate_assign_mc_groups(family);
 372         if (err)
 373                 goto errout_remove;
 374
 375         genl_unlock_all();
 376
 377         /* send all events */
 378         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 379         for (i = 0; i < family->n_mcgrps; i++)
 380                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 381                                 &family->mcgrps[i], family->mcgrp_offset + i);
 382
 383         return 0;
 384
 385 errout_remove:
 386         idr_remove(&genl_fam_idr, family->id);
 387         kfree(family->attrbuf);
 388 errout_locked:
 389         genl_unlock_all();
 390         return err;
 391 }
 392 EXPORT_SYMBOL(genl_register_family);
 393
 394 /**
 395  * genl_unregister_family - unregister generic netlink family
 396  * @family: generic netlink family
 397  *
 398  * Unregisters the specified family.
 399  *
 400  * Returns 0 on success or a negative error code.
 401  */
 402 int genl_unregister_family(const struct genl_family *family)
 403 {
 404         genl_lock_all();
 405
 406         if (!genl_family_find_byid(family->id)) {
 407                 genl_unlock_all();
 408                 return -ENOENT;
 409         }
 410
 411         genl_unregister_mc_groups(family);
 412
 413         idr_remove(&genl_fam_idr, family->id);
 414
 415         up_write(&cb_lock);
 416         wait_event(genl_sk_destructing_waitq,
 417                    atomic_read(&genl_sk_destructing_cnt) == 0);
 418         genl_unlock();
 419
 420         kfree(family->attrbuf);
 421
 422         genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 423
 424         return 0;
 425 }
 426 EXPORT_SYMBOL(genl_unregister_family);
 427
 428 /**
 429  * genlmsg_put - Add generic netlink header to netlink message
 430  * @skb: socket buffer holding the message
 431  * @portid: netlink portid the message is addressed to
 432  * @seq: sequence number (usually the one of the sender)
 433  * @family: generic netlink family
 434  * @flags: netlink message flags
 435  * @cmd: generic netlink command
 436  *
 437  * Returns pointer to user specific header
 438  */
 439 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 440                   const struct genl_family *family, int flags, u8 cmd)
 441 {
 442         struct nlmsghdr *nlh;
 443         struct genlmsghdr *hdr;
 444
 445         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 446                         family->hdrsize, flags);
 447         if (nlh == NULL)
 448                 return NULL;
 449
 450         hdr = nlmsg_data(nlh);
 451         hdr->cmd = cmd;
 452         hdr->version = family->version;
 453         hdr->reserved = 0;
 454
 455         return (char *) hdr + GENL_HDRLEN;
 456 }
 457 EXPORT_SYMBOL(genlmsg_put);
 458
 459 static int genl_lock_start(struct netlink_callback *cb)
 460 {
 461         /* our ops are always const - netlink API doesn't propagate that */
 462         const struct genl_ops *ops = cb->data;
 463         int rc = 0;
 464
 465         if (ops->start) {
 466                 genl_lock();
 467                 rc = ops->start(cb);
 468                 genl_unlock();
 469         }
 470         return rc;
 471 }
 472
 473 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 474 {
 475         /* our ops are always const - netlink API doesn't propagate that */
 476         const struct genl_ops *ops = cb->data;
 477         int rc;
 478
 479         genl_lock();
 480         rc = ops->dumpit(skb, cb);
 481         genl_unlock();
 482         return rc;
 483 }
 484
 485 static int genl_lock_done(struct netlink_callback *cb)
 486 {
 487         /* our ops are always const - netlink API doesn't propagate that */
 488         const struct genl_ops *ops = cb->data;
 489         int rc = 0;
 490
 491         if (ops->done) {
 492                 genl_lock();
 493                 rc = ops->done(cb);
 494                 genl_unlock();
 495         }
 496         return rc;
 497 }
 498
 499 static int genl_family_rcv_msg(const struct genl_family *family,
 500                                struct sk_buff *skb,
 501                                struct nlmsghdr *nlh,
 502                                struct netlink_ext_ack *extack)
 503 {
 504         const struct genl_ops *ops;
 505         struct net *net = sock_net(skb->sk);
 506         struct genl_info info;
 507         struct genlmsghdr *hdr = nlmsg_data(nlh);
 508         struct nlattr **attrbuf;
 509         int hdrlen, err;
 510
 511         /* this family doesn't exist in this netns */
 512         if (!family->netnsok && !net_eq(net, &init_net))
 513                 return -ENOENT;
 514
 515         hdrlen = GENL_HDRLEN + family->hdrsize;
 516         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 517                 return -EINVAL;
 518
 519         ops = genl_get_cmd(hdr->cmd, family);
 520         if (ops == NULL)
 521                 return -EOPNOTSUPP;
 522
 523         if ((ops->flags & GENL_ADMIN_PERM) &&
 524             !netlink_capable(skb, CAP_NET_ADMIN))
 525                 return -EPERM;
 526
 527         if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
 528             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 529                 return -EPERM;
 530
 531         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 532                 int rc;
 533
 534                 if (ops->dumpit == NULL)
 535                         return -EOPNOTSUPP;
 536
 537                 if (!family->parallel_ops) {
 538                         struct netlink_dump_control c = {
 539                                 .module = family->module,
 540                                 /* we have const, but the netlink API doesn't */
 541                                 .data = (void *)ops,
 542                                 .start = genl_lock_start,
 543                                 .dump = genl_lock_dumpit,
 544                                 .done = genl_lock_done,
 545                         };
 546
 547                         genl_unlock();
 548                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 549                         genl_lock();
 550
 551                 } else {
 552                         struct netlink_dump_control c = {
 553                                 .module = family->module,
 554                                 .start = ops->start,
 555                                 .dump = ops->dumpit,
 556                                 .done = ops->done,
 557                         };
 558
 559                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 560                 }
 561
 562                 return rc;
 563         }
 564
 565         if (ops->doit == NULL)
 566                 return -EOPNOTSUPP;
 567
 568         if (family->maxattr && family->parallel_ops) {
 569                 attrbuf = kmalloc((family->maxattr+1) *
 570                                         sizeof(struct nlattr *), GFP_KERNEL);
 571                 if (attrbuf == NULL)
 572                         return -ENOMEM;
 573         } else
 574                 attrbuf = family->attrbuf;
 575
 576         if (attrbuf) {
 577                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 578                                   ops->policy, extack);
 579                 if (err < 0)
 580                         goto out;
 581         }
 582
 583         info.snd_seq = nlh->nlmsg_seq;
 584         info.snd_portid = NETLINK_CB(skb).portid;
 585         info.nlhdr = nlh;
 586         info.genlhdr = nlmsg_data(nlh);
 587         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 588         info.attrs = attrbuf;
 589         info.extack = extack;
 590         genl_info_net_set(&info, net);
 591         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 592
 593         if (family->pre_doit) {
 594                 err = family->pre_doit(ops, skb, &info);
 595                 if (err)
 596                         goto out;
 597         }
 598
 599         err = ops->doit(skb, &info);
 600
 601         if (family->post_doit)
 602                 family->post_doit(ops, skb, &info);
 603
 604 out:
 605         if (family->parallel_ops)
 606                 kfree(attrbuf);
 607
 608         return err;
 609 }
 610
 611 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 612                         struct netlink_ext_ack *extack)
 613 {
 614         const struct genl_family *family;
 615         int err;
 616
 617         family = genl_family_find_byid(nlh->nlmsg_type);
 618         if (family == NULL)
 619                 return -ENOENT;
 620
 621         if (!family->parallel_ops)
 622                 genl_lock();
 623
 624         err = genl_family_rcv_msg(family, skb, nlh, extack);
 625
 626         if (!family->parallel_ops)
 627                 genl_unlock();
 628
 629         return err;
 630 }
 631
 632 static void genl_rcv(struct sk_buff *skb)
 633 {
 634         down_read(&cb_lock);
 635         netlink_rcv_skb(skb, &genl_rcv_msg);
 636         up_read(&cb_lock);
 637 }
 638
 639 /**************************************************************************
 640  * Controller
 641  **************************************************************************/
 642
 643 static struct genl_family genl_ctrl;
 644
 645 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 646                           u32 flags, struct sk_buff *skb, u8 cmd)
 647 {
 648         void *hdr;
 649
 650         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 651         if (hdr == NULL)
 652                 return -1;
 653
 654         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 655             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 656             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 657             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 658             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 659                 goto nla_put_failure;
 660
 661         if (family->n_ops) {
 662                 struct nlattr *nla_ops;
 663                 int i;
 664
 665                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 666                 if (nla_ops == NULL)
 667                         goto nla_put_failure;
 668
 669                 for (i = 0; i < family->n_ops; i++) {
 670                         struct nlattr *nest;
 671                         const struct genl_ops *ops = &family->ops[i];
 672                         u32 op_flags = ops->flags;
 673
 674                         if (ops->dumpit)
 675                                 op_flags |= GENL_CMD_CAP_DUMP;
 676                         if (ops->doit)
 677                                 op_flags |= GENL_CMD_CAP_DO;
 678                         if (ops->policy)
 679                                 op_flags |= GENL_CMD_CAP_HASPOL;
 680
 681                         nest = nla_nest_start(skb, i + 1);
 682                         if (nest == NULL)
 683                                 goto nla_put_failure;
 684
 685                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 686                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 687                                 goto nla_put_failure;
 688
 689                         nla_nest_end(skb, nest);
 690                 }
 691
 692                 nla_nest_end(skb, nla_ops);
 693         }
 694
 695         if (family->n_mcgrps) {
 696                 struct nlattr *nla_grps;
 697                 int i;
 698
 699                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 700                 if (nla_grps == NULL)
 701                         goto nla_put_failure;
 702
 703                 for (i = 0; i < family->n_mcgrps; i++) {
 704                         struct nlattr *nest;
 705                         const struct genl_multicast_group *grp;
 706
 707                         grp = &family->mcgrps[i];
 708
 709                         nest = nla_nest_start(skb, i + 1);
 710                         if (nest == NULL)
 711                                 goto nla_put_failure;
 712
 713                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 714                                         family->mcgrp_offset + i) ||
 715                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 716                                            grp->name))
 717                                 goto nla_put_failure;
 718
 719                         nla_nest_end(skb, nest);
 720                 }
 721                 nla_nest_end(skb, nla_grps);
 722         }
 723
 724         genlmsg_end(skb, hdr);
 725         return 0;
 726
 727 nla_put_failure:
 728         genlmsg_cancel(skb, hdr);
 729         return -EMSGSIZE;
 730 }
 731
 732 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
 733                                 const struct genl_multicast_group *grp,
 734                                 int grp_id, u32 portid, u32 seq, u32 flags,
 735                                 struct sk_buff *skb, u8 cmd)
 736 {
 737         void *hdr;
 738         struct nlattr *nla_grps;
 739         struct nlattr *nest;
 740
 741         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 742         if (hdr == NULL)
 743                 return -1;
 744
 745         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 746             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 747                 goto nla_put_failure;
 748
 749         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 750         if (nla_grps == NULL)
 751                 goto nla_put_failure;
 752
 753         nest = nla_nest_start(skb, 1);
 754         if (nest == NULL)
 755                 goto nla_put_failure;
 756
 757         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 758             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 759                            grp->name))
 760                 goto nla_put_failure;
 761
 762         nla_nest_end(skb, nest);
 763         nla_nest_end(skb, nla_grps);
 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_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 774 {
 775         int n = 0;
 776         struct genl_family *rt;
 777         struct net *net = sock_net(skb->sk);
 778         int fams_to_skip = cb->args[0];
 779         unsigned int id;
 780
 781         idr_for_each_entry(&genl_fam_idr, rt, id) {
 782                 if (!rt->netnsok && !net_eq(net, &init_net))
 783                         continue;
 784
 785                 if (n++ < fams_to_skip)
 786                         continue;
 787
 788                 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 789                                    cb->nlh->nlmsg_seq, NLM_F_MULTI,
 790                                    skb, CTRL_CMD_NEWFAMILY) < 0) {
 791                         n--;
 792                         break;
 793                 }
 794         }
 795
 796         cb->args[0] = n;
 797         return skb->len;
 798 }
 799
 800 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
 801                                              u32 portid, int seq, u8 cmd)
 802 {
 803         struct sk_buff *skb;
 804         int err;
 805
 806         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 807         if (skb == NULL)
 808                 return ERR_PTR(-ENOBUFS);
 809
 810         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 811         if (err < 0) {
 812                 nlmsg_free(skb);
 813                 return ERR_PTR(err);
 814         }
 815
 816         return skb;
 817 }
 818
 819 static struct sk_buff *
 820 ctrl_build_mcgrp_msg(const struct genl_family *family,
 821                      const struct genl_multicast_group *grp,
 822                      int grp_id, u32 portid, int seq, u8 cmd)
 823 {
 824         struct sk_buff *skb;
 825         int err;
 826
 827         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 828         if (skb == NULL)
 829                 return ERR_PTR(-ENOBUFS);
 830
 831         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 832                                    seq, 0, skb, cmd);
 833         if (err < 0) {
 834                 nlmsg_free(skb);
 835                 return ERR_PTR(err);
 836         }
 837
 838         return skb;
 839 }
 840
 841 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 842         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 843         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 844                                     .len = GENL_NAMSIZ - 1 },
 845 };
 846
 847 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 848 {
 849         struct sk_buff *msg;
 850         const struct genl_family *res = NULL;
 851         int err = -EINVAL;
 852
 853         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 854                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 855                 res = genl_family_find_byid(id);
 856                 err = -ENOENT;
 857         }
 858
 859         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 860                 char *name;
 861
 862                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 863                 res = genl_family_find_byname(name);
 864 #ifdef CONFIG_MODULES
 865                 if (res == NULL) {
 866                         genl_unlock();
 867                         up_read(&cb_lock);
 868                         request_module("net-pf-%d-proto-%d-family-%s",
 869                                        PF_NETLINK, NETLINK_GENERIC, name);
 870                         down_read(&cb_lock);
 871                         genl_lock();
 872                         res = genl_family_find_byname(name);
 873                 }
 874 #endif
 875                 err = -ENOENT;
 876         }
 877
 878         if (res == NULL)
 879                 return err;
 880
 881         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 882                 /* family doesn't exist here */
 883                 return -ENOENT;
 884         }
 885
 886         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 887                                     CTRL_CMD_NEWFAMILY);
 888         if (IS_ERR(msg))
 889                 return PTR_ERR(msg);
 890
 891         return genlmsg_reply(msg, info);
 892 }
 893
 894 static int genl_ctrl_event(int event, const struct genl_family *family,
 895                            const struct genl_multicast_group *grp,
 896                            int grp_id)
 897 {
 898         struct sk_buff *msg;
 899
 900         /* genl is still initialising */
 901         if (!init_net.genl_sock)
 902                 return 0;
 903
 904         switch (event) {
 905         case CTRL_CMD_NEWFAMILY:
 906         case CTRL_CMD_DELFAMILY:
 907                 WARN_ON(grp);
 908                 msg = ctrl_build_family_msg(family, 0, 0, event);
 909                 break;
 910         case CTRL_CMD_NEWMCAST_GRP:
 911         case CTRL_CMD_DELMCAST_GRP:
 912                 BUG_ON(!grp);
 913                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 914                 break;
 915         default:
 916                 return -EINVAL;
 917         }
 918
 919         if (IS_ERR(msg))
 920                 return PTR_ERR(msg);
 921
 922         if (!family->netnsok) {
 923                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 924                                         0, GFP_KERNEL);
 925         } else {
 926                 rcu_read_lock();
 927                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 928                                         0, GFP_ATOMIC);
 929                 rcu_read_unlock();
 930         }
 931
 932         return 0;
 933 }
 934
 935 static const struct genl_ops genl_ctrl_ops[] = {
 936         {
 937                 .cmd            = CTRL_CMD_GETFAMILY,
 938                 .doit           = ctrl_getfamily,
 939                 .dumpit         = ctrl_dumpfamily,
 940                 .policy         = ctrl_policy,
 941         },
 942 };
 943
 944 static const struct genl_multicast_group genl_ctrl_groups[] = {
 945         { .name = "notify", },
 946 };
 947
 948 static struct genl_family genl_ctrl __ro_after_init = {
 949         .module = THIS_MODULE,
 950         .ops = genl_ctrl_ops,
 951         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
 952         .mcgrps = genl_ctrl_groups,
 953         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
 954         .id = GENL_ID_CTRL,
 955         .name = "nlctrl",
 956         .version = 0x2,
 957         .maxattr = CTRL_ATTR_MAX,
 958         .netnsok = true,
 959 };
 960
 961 static int genl_bind(struct net *net, int group)
 962 {
 963         struct genl_family *f;
 964         int err = -ENOENT;
 965         unsigned int id;
 966
 967         down_read(&cb_lock);
 968
 969         idr_for_each_entry(&genl_fam_idr, f, id) {
 970                 if (group >= f->mcgrp_offset &&
 971                     group < f->mcgrp_offset + f->n_mcgrps) {
 972                         int fam_grp = group - f->mcgrp_offset;
 973
 974                         if (!f->netnsok && net != &init_net)
 975                                 err = -ENOENT;
 976                         else if (f->mcast_bind)
 977                                 err = f->mcast_bind(net, fam_grp);
 978                         else
 979                                 err = 0;
 980                         break;
 981                 }
 982         }
 983         up_read(&cb_lock);
 984
 985         return err;
 986 }
 987
 988 static void genl_unbind(struct net *net, int group)
 989 {
 990         struct genl_family *f;
 991         unsigned int id;
 992
 993         down_read(&cb_lock);
 994
 995         idr_for_each_entry(&genl_fam_idr, f, id) {
 996                 if (group >= f->mcgrp_offset &&
 997                     group < f->mcgrp_offset + f->n_mcgrps) {
 998                         int fam_grp = group - f->mcgrp_offset;
 999
1000                         if (f->mcast_unbind)
1001                                 f->mcast_unbind(net, fam_grp);
1002                         break;
1003                 }
1004         }
1005         up_read(&cb_lock);
1006 }
1007
1008 static int __net_init genl_pernet_init(struct net *net)
1009 {
1010         struct netlink_kernel_cfg cfg = {
1011                 .input          = genl_rcv,
1012                 .flags          = NL_CFG_F_NONROOT_RECV,
1013                 .bind           = genl_bind,
1014                 .unbind         = genl_unbind,
1015         };
1016
1017         /* we'll bump the group number right afterwards */
1018         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1019
1020         if (!net->genl_sock && net_eq(net, &init_net))
1021                 panic("GENL: Cannot initialize generic netlink\n");
1022
1023         if (!net->genl_sock)
1024                 return -ENOMEM;
1025
1026         return 0;
1027 }
1028
1029 static void __net_exit genl_pernet_exit(struct net *net)
1030 {
1031         netlink_kernel_release(net->genl_sock);
1032         net->genl_sock = NULL;
1033 }
1034
1035 static struct pernet_operations genl_pernet_ops = {
1036         .init = genl_pernet_init,
1037         .exit = genl_pernet_exit,
1038 };
1039
1040 static int __init genl_init(void)
1041 {
1042         int err;
1043
1044         err = genl_register_family(&genl_ctrl);
1045         if (err < 0)
1046                 goto problem;
1047
1048         err = register_pernet_subsys(&genl_pernet_ops);
1049         if (err)
1050                 goto problem;
1051
1052         return 0;
1053
1054 problem:
1055         panic("GENL: Cannot register controller: %d\n", err);
1056 }
1057
1058 subsys_initcall(genl_init);
1059
1060 /**
1061  * genl_family_attrbuf - return family's attrbuf
1062  * @family: the family
1063  *
1064  * Return the family's attrbuf, while validating that it's
1065  * actually valid to access it.
1066  *
1067  * You cannot use this function with a family that has parallel_ops
1068  * and you can only use it within (pre/post) doit/dumpit callbacks.
1069  */
1070 struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1071 {
1072         if (!WARN_ON(family->parallel_ops))
1073                 lockdep_assert_held(&genl_mutex);
1074
1075         return family->attrbuf;
1076 }
1077 EXPORT_SYMBOL(genl_family_attrbuf);
1078
1079 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1080                          gfp_t flags)
1081 {
1082         struct sk_buff *tmp;
1083         struct net *net, *prev = NULL;
1084         int err;
1085
1086         for_each_net_rcu(net) {
1087                 if (prev) {
1088                         tmp = skb_clone(skb, flags);
1089                         if (!tmp) {
1090                                 err = -ENOMEM;
1091                                 goto error;
1092                         }
1093                         err = nlmsg_multicast(prev->genl_sock, tmp,
1094                                               portid, group, flags);
1095                         if (err)
1096                                 goto error;
1097                 }
1098
1099                 prev = net;
1100         }
1101
1102         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1103  error:
1104         kfree_skb(skb);
1105         return err;
1106 }
1107
1108 int genlmsg_multicast_allns(const struct genl_family *family,
1109                             struct sk_buff *skb, u32 portid,
1110                             unsigned int group, gfp_t flags)
1111 {
1112         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1113                 return -EINVAL;
1114         group = family->mcgrp_offset + group;
1115         return genlmsg_mcast(skb, portid, group, flags);
1116 }
1117 EXPORT_SYMBOL(genlmsg_multicast_allns);
1118
1119 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1120                  struct genl_info *info, u32 group, gfp_t flags)
1121 {
1122         struct net *net = genl_info_net(info);
1123         struct sock *sk = net->genl_sock;
1124         int report = 0;
1125
1126         if (info->nlhdr)
1127                 report = nlmsg_report(info->nlhdr);
1128
1129         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1130                 return;
1131         group = family->mcgrp_offset + group;
1132         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1133 }
1134 EXPORT_SYMBOL(genl_notify);