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_array(family->maxattr + 1,
 356                                                 sizeof(struct nlattr *),
 357                                                 GFP_KERNEL);
 358                 if (family->attrbuf == NULL) {
 359                         err = -ENOMEM;
 360                         goto errout_locked;
 361                 }
 362         } else
 363                 family->attrbuf = NULL;
 364
 365         family->id = idr_alloc_cyclic(&genl_fam_idr, family,
 366                                       start, end + 1, GFP_KERNEL);
 367         if (family->id < 0) {
 368                 err = family->id;
 369                 goto errout_free;
 370         }
 371
 372         err = genl_validate_assign_mc_groups(family);
 373         if (err)
 374                 goto errout_remove;
 375
 376         genl_unlock_all();
 377
 378         /* send all events */
 379         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 380         for (i = 0; i < family->n_mcgrps; i++)
 381                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 382                                 &family->mcgrps[i], family->mcgrp_offset + i);
 383
 384         return 0;
 385
 386 errout_remove:
 387         idr_remove(&genl_fam_idr, family->id);
 388 errout_free:
 389         kfree(family->attrbuf);
 390 errout_locked:
 391         genl_unlock_all();
 392         return err;
 393 }
 394 EXPORT_SYMBOL(genl_register_family);
 395
 396 /**
 397  * genl_unregister_family - unregister generic netlink family
 398  * @family: generic netlink family
 399  *
 400  * Unregisters the specified family.
 401  *
 402  * Returns 0 on success or a negative error code.
 403  */
 404 int genl_unregister_family(const struct genl_family *family)
 405 {
 406         genl_lock_all();
 407
 408         if (!genl_family_find_byid(family->id)) {
 409                 genl_unlock_all();
 410                 return -ENOENT;
 411         }
 412
 413         genl_unregister_mc_groups(family);
 414
 415         idr_remove(&genl_fam_idr, family->id);
 416
 417         up_write(&cb_lock);
 418         wait_event(genl_sk_destructing_waitq,
 419                    atomic_read(&genl_sk_destructing_cnt) == 0);
 420         genl_unlock();
 421
 422         kfree(family->attrbuf);
 423
 424         genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 425
 426         return 0;
 427 }
 428 EXPORT_SYMBOL(genl_unregister_family);
 429
 430 /**
 431  * genlmsg_put - Add generic netlink header to netlink message
 432  * @skb: socket buffer holding the message
 433  * @portid: netlink portid the message is addressed to
 434  * @seq: sequence number (usually the one of the sender)
 435  * @family: generic netlink family
 436  * @flags: netlink message flags
 437  * @cmd: generic netlink command
 438  *
 439  * Returns pointer to user specific header
 440  */
 441 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 442                   const struct genl_family *family, int flags, u8 cmd)
 443 {
 444         struct nlmsghdr *nlh;
 445         struct genlmsghdr *hdr;
 446
 447         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 448                         family->hdrsize, flags);
 449         if (nlh == NULL)
 450                 return NULL;
 451
 452         hdr = nlmsg_data(nlh);
 453         hdr->cmd = cmd;
 454         hdr->version = family->version;
 455         hdr->reserved = 0;
 456
 457         return (char *) hdr + GENL_HDRLEN;
 458 }
 459 EXPORT_SYMBOL(genlmsg_put);
 460
 461 static int genl_lock_start(struct netlink_callback *cb)
 462 {
 463         /* our ops are always const - netlink API doesn't propagate that */
 464         const struct genl_ops *ops = cb->data;
 465         int rc = 0;
 466
 467         if (ops->start) {
 468                 genl_lock();
 469                 rc = ops->start(cb);
 470                 genl_unlock();
 471         }
 472         return rc;
 473 }
 474
 475 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 476 {
 477         /* our ops are always const - netlink API doesn't propagate that */
 478         const struct genl_ops *ops = cb->data;
 479         int rc;
 480
 481         genl_lock();
 482         rc = ops->dumpit(skb, cb);
 483         genl_unlock();
 484         return rc;
 485 }
 486
 487 static int genl_lock_done(struct netlink_callback *cb)
 488 {
 489         /* our ops are always const - netlink API doesn't propagate that */
 490         const struct genl_ops *ops = cb->data;
 491         int rc = 0;
 492
 493         if (ops->done) {
 494                 genl_lock();
 495                 rc = ops->done(cb);
 496                 genl_unlock();
 497         }
 498         return rc;
 499 }
 500
 501 static int genl_family_rcv_msg(const struct genl_family *family,
 502                                struct sk_buff *skb,
 503                                struct nlmsghdr *nlh,
 504                                struct netlink_ext_ack *extack)
 505 {
 506         const struct genl_ops *ops;
 507         struct net *net = sock_net(skb->sk);
 508         struct genl_info info;
 509         struct genlmsghdr *hdr = nlmsg_data(nlh);
 510         struct nlattr **attrbuf;
 511         int hdrlen, err;
 512
 513         /* this family doesn't exist in this netns */
 514         if (!family->netnsok && !net_eq(net, &init_net))
 515                 return -ENOENT;
 516
 517         hdrlen = GENL_HDRLEN + family->hdrsize;
 518         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 519                 return -EINVAL;
 520
 521         ops = genl_get_cmd(hdr->cmd, family);
 522         if (ops == NULL)
 523                 return -EOPNOTSUPP;
 524
 525         if ((ops->flags & GENL_ADMIN_PERM) &&
 526             !netlink_capable(skb, CAP_NET_ADMIN))
 527                 return -EPERM;
 528
 529         if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
 530             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 531                 return -EPERM;
 532
 533         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 534                 int rc;
 535
 536                 if (ops->dumpit == NULL)
 537                         return -EOPNOTSUPP;
 538
 539                 if (!family->parallel_ops) {
 540                         struct netlink_dump_control c = {
 541                                 .module = family->module,
 542                                 /* we have const, but the netlink API doesn't */
 543                                 .data = (void *)ops,
 544                                 .start = genl_lock_start,
 545                                 .dump = genl_lock_dumpit,
 546                                 .done = genl_lock_done,
 547                         };
 548
 549                         genl_unlock();
 550                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 551                         genl_lock();
 552
 553                 } else {
 554                         struct netlink_dump_control c = {
 555                                 .module = family->module,
 556                                 .start = ops->start,
 557                                 .dump = ops->dumpit,
 558                                 .done = ops->done,
 559                         };
 560
 561                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 562                 }
 563
 564                 return rc;
 565         }
 566
 567         if (ops->doit == NULL)
 568                 return -EOPNOTSUPP;
 569
 570         if (family->maxattr && family->parallel_ops) {
 571                 attrbuf = kmalloc_array(family->maxattr + 1,
 572                                         sizeof(struct nlattr *),
 573                                         GFP_KERNEL);
 574                 if (attrbuf == NULL)
 575                         return -ENOMEM;
 576         } else
 577                 attrbuf = family->attrbuf;
 578
 579         if (attrbuf) {
 580                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 581                                   ops->policy, extack);
 582                 if (err < 0)
 583                         goto out;
 584         }
 585
 586         info.snd_seq = nlh->nlmsg_seq;
 587         info.snd_portid = NETLINK_CB(skb).portid;
 588         info.nlhdr = nlh;
 589         info.genlhdr = nlmsg_data(nlh);
 590         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 591         info.attrs = attrbuf;
 592         info.extack = extack;
 593         genl_info_net_set(&info, net);
 594         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 595
 596         if (family->pre_doit) {
 597                 err = family->pre_doit(ops, skb, &info);
 598                 if (err)
 599                         goto out;
 600         }
 601
 602         err = ops->doit(skb, &info);
 603
 604         if (family->post_doit)
 605                 family->post_doit(ops, skb, &info);
 606
 607 out:
 608         if (family->parallel_ops)
 609                 kfree(attrbuf);
 610
 611         return err;
 612 }
 613
 614 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 615                         struct netlink_ext_ack *extack)
 616 {
 617         const struct genl_family *family;
 618         int err;
 619
 620         family = genl_family_find_byid(nlh->nlmsg_type);
 621         if (family == NULL)
 622                 return -ENOENT;
 623
 624         if (!family->parallel_ops)
 625                 genl_lock();
 626
 627         err = genl_family_rcv_msg(family, skb, nlh, extack);
 628
 629         if (!family->parallel_ops)
 630                 genl_unlock();
 631
 632         return err;
 633 }
 634
 635 static void genl_rcv(struct sk_buff *skb)
 636 {
 637         down_read(&cb_lock);
 638         netlink_rcv_skb(skb, &genl_rcv_msg);
 639         up_read(&cb_lock);
 640 }
 641
 642 /**************************************************************************
 643  * Controller
 644  **************************************************************************/
 645
 646 static struct genl_family genl_ctrl;
 647
 648 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 649                           u32 flags, struct sk_buff *skb, u8 cmd)
 650 {
 651         void *hdr;
 652
 653         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 654         if (hdr == NULL)
 655                 return -1;
 656
 657         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 658             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 659             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 660             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 661             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 662                 goto nla_put_failure;
 663
 664         if (family->n_ops) {
 665                 struct nlattr *nla_ops;
 666                 int i;
 667
 668                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 669                 if (nla_ops == NULL)
 670                         goto nla_put_failure;
 671
 672                 for (i = 0; i < family->n_ops; i++) {
 673                         struct nlattr *nest;
 674                         const struct genl_ops *ops = &family->ops[i];
 675                         u32 op_flags = ops->flags;
 676
 677                         if (ops->dumpit)
 678                                 op_flags |= GENL_CMD_CAP_DUMP;
 679                         if (ops->doit)
 680                                 op_flags |= GENL_CMD_CAP_DO;
 681                         if (ops->policy)
 682                                 op_flags |= GENL_CMD_CAP_HASPOL;
 683
 684                         nest = nla_nest_start(skb, i + 1);
 685                         if (nest == NULL)
 686                                 goto nla_put_failure;
 687
 688                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 689                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 690                                 goto nla_put_failure;
 691
 692                         nla_nest_end(skb, nest);
 693                 }
 694
 695                 nla_nest_end(skb, nla_ops);
 696         }
 697
 698         if (family->n_mcgrps) {
 699                 struct nlattr *nla_grps;
 700                 int i;
 701
 702                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 703                 if (nla_grps == NULL)
 704                         goto nla_put_failure;
 705
 706                 for (i = 0; i < family->n_mcgrps; i++) {
 707                         struct nlattr *nest;
 708                         const struct genl_multicast_group *grp;
 709
 710                         grp = &family->mcgrps[i];
 711
 712                         nest = nla_nest_start(skb, i + 1);
 713                         if (nest == NULL)
 714                                 goto nla_put_failure;
 715
 716                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 717                                         family->mcgrp_offset + i) ||
 718                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 719                                            grp->name))
 720                                 goto nla_put_failure;
 721
 722                         nla_nest_end(skb, nest);
 723                 }
 724                 nla_nest_end(skb, nla_grps);
 725         }
 726
 727         genlmsg_end(skb, hdr);
 728         return 0;
 729
 730 nla_put_failure:
 731         genlmsg_cancel(skb, hdr);
 732         return -EMSGSIZE;
 733 }
 734
 735 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
 736                                 const struct genl_multicast_group *grp,
 737                                 int grp_id, u32 portid, u32 seq, u32 flags,
 738                                 struct sk_buff *skb, u8 cmd)
 739 {
 740         void *hdr;
 741         struct nlattr *nla_grps;
 742         struct nlattr *nest;
 743
 744         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 745         if (hdr == NULL)
 746                 return -1;
 747
 748         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 749             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 750                 goto nla_put_failure;
 751
 752         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 753         if (nla_grps == NULL)
 754                 goto nla_put_failure;
 755
 756         nest = nla_nest_start(skb, 1);
 757         if (nest == NULL)
 758                 goto nla_put_failure;
 759
 760         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 761             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 762                            grp->name))
 763                 goto nla_put_failure;
 764
 765         nla_nest_end(skb, nest);
 766         nla_nest_end(skb, nla_grps);
 767
 768         genlmsg_end(skb, hdr);
 769         return 0;
 770
 771 nla_put_failure:
 772         genlmsg_cancel(skb, hdr);
 773         return -EMSGSIZE;
 774 }
 775
 776 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 777 {
 778         int n = 0;
 779         struct genl_family *rt;
 780         struct net *net = sock_net(skb->sk);
 781         int fams_to_skip = cb->args[0];
 782         unsigned int id;
 783
 784         idr_for_each_entry(&genl_fam_idr, rt, id) {
 785                 if (!rt->netnsok && !net_eq(net, &init_net))
 786                         continue;
 787
 788                 if (n++ < fams_to_skip)
 789                         continue;
 790
 791                 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 792                                    cb->nlh->nlmsg_seq, NLM_F_MULTI,
 793                                    skb, CTRL_CMD_NEWFAMILY) < 0) {
 794                         n--;
 795                         break;
 796                 }
 797         }
 798
 799         cb->args[0] = n;
 800         return skb->len;
 801 }
 802
 803 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
 804                                              u32 portid, int seq, u8 cmd)
 805 {
 806         struct sk_buff *skb;
 807         int err;
 808
 809         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 810         if (skb == NULL)
 811                 return ERR_PTR(-ENOBUFS);
 812
 813         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 814         if (err < 0) {
 815                 nlmsg_free(skb);
 816                 return ERR_PTR(err);
 817         }
 818
 819         return skb;
 820 }
 821
 822 static struct sk_buff *
 823 ctrl_build_mcgrp_msg(const struct genl_family *family,
 824                      const struct genl_multicast_group *grp,
 825                      int grp_id, u32 portid, int seq, u8 cmd)
 826 {
 827         struct sk_buff *skb;
 828         int err;
 829
 830         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 831         if (skb == NULL)
 832                 return ERR_PTR(-ENOBUFS);
 833
 834         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 835                                    seq, 0, skb, cmd);
 836         if (err < 0) {
 837                 nlmsg_free(skb);
 838                 return ERR_PTR(err);
 839         }
 840
 841         return skb;
 842 }
 843
 844 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 845         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 846         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 847                                     .len = GENL_NAMSIZ - 1 },
 848 };
 849
 850 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 851 {
 852         struct sk_buff *msg;
 853         const struct genl_family *res = NULL;
 854         int err = -EINVAL;
 855
 856         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 857                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 858                 res = genl_family_find_byid(id);
 859                 err = -ENOENT;
 860         }
 861
 862         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 863                 char *name;
 864
 865                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 866                 res = genl_family_find_byname(name);
 867 #ifdef CONFIG_MODULES
 868                 if (res == NULL) {
 869                         genl_unlock();
 870                         up_read(&cb_lock);
 871                         request_module("net-pf-%d-proto-%d-family-%s",
 872                                        PF_NETLINK, NETLINK_GENERIC, name);
 873                         down_read(&cb_lock);
 874                         genl_lock();
 875                         res = genl_family_find_byname(name);
 876                 }
 877 #endif
 878                 err = -ENOENT;
 879         }
 880
 881         if (res == NULL)
 882                 return err;
 883
 884         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 885                 /* family doesn't exist here */
 886                 return -ENOENT;
 887         }
 888
 889         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 890                                     CTRL_CMD_NEWFAMILY);
 891         if (IS_ERR(msg))
 892                 return PTR_ERR(msg);
 893
 894         return genlmsg_reply(msg, info);
 895 }
 896
 897 static int genl_ctrl_event(int event, const struct genl_family *family,
 898                            const struct genl_multicast_group *grp,
 899                            int grp_id)
 900 {
 901         struct sk_buff *msg;
 902
 903         /* genl is still initialising */
 904         if (!init_net.genl_sock)
 905                 return 0;
 906
 907         switch (event) {
 908         case CTRL_CMD_NEWFAMILY:
 909         case CTRL_CMD_DELFAMILY:
 910                 WARN_ON(grp);
 911                 msg = ctrl_build_family_msg(family, 0, 0, event);
 912                 break;
 913         case CTRL_CMD_NEWMCAST_GRP:
 914         case CTRL_CMD_DELMCAST_GRP:
 915                 BUG_ON(!grp);
 916                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 917                 break;
 918         default:
 919                 return -EINVAL;
 920         }
 921
 922         if (IS_ERR(msg))
 923                 return PTR_ERR(msg);
 924
 925         if (!family->netnsok) {
 926                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 927                                         0, GFP_KERNEL);
 928         } else {
 929                 rcu_read_lock();
 930                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 931                                         0, GFP_ATOMIC);
 932                 rcu_read_unlock();
 933         }
 934
 935         return 0;
 936 }
 937
 938 static const struct genl_ops genl_ctrl_ops[] = {
 939         {
 940                 .cmd            = CTRL_CMD_GETFAMILY,
 941                 .doit           = ctrl_getfamily,
 942                 .dumpit         = ctrl_dumpfamily,
 943                 .policy         = ctrl_policy,
 944         },
 945 };
 946
 947 static const struct genl_multicast_group genl_ctrl_groups[] = {
 948         { .name = "notify", },
 949 };
 950
 951 static struct genl_family genl_ctrl __ro_after_init = {
 952         .module = THIS_MODULE,
 953         .ops = genl_ctrl_ops,
 954         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
 955         .mcgrps = genl_ctrl_groups,
 956         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
 957         .id = GENL_ID_CTRL,
 958         .name = "nlctrl",
 959         .version = 0x2,
 960         .maxattr = CTRL_ATTR_MAX,
 961         .netnsok = true,
 962 };
 963
 964 static int genl_bind(struct net *net, int group)
 965 {
 966         struct genl_family *f;
 967         int err = -ENOENT;
 968         unsigned int id;
 969
 970         down_read(&cb_lock);
 971
 972         idr_for_each_entry(&genl_fam_idr, f, id) {
 973                 if (group >= f->mcgrp_offset &&
 974                     group < f->mcgrp_offset + f->n_mcgrps) {
 975                         int fam_grp = group - f->mcgrp_offset;
 976
 977                         if (!f->netnsok && net != &init_net)
 978                                 err = -ENOENT;
 979                         else if (f->mcast_bind)
 980                                 err = f->mcast_bind(net, fam_grp);
 981                         else
 982                                 err = 0;
 983                         break;
 984                 }
 985         }
 986         up_read(&cb_lock);
 987
 988         return err;
 989 }
 990
 991 static void genl_unbind(struct net *net, int group)
 992 {
 993         struct genl_family *f;
 994         unsigned int id;
 995
 996         down_read(&cb_lock);
 997
 998         idr_for_each_entry(&genl_fam_idr, f, id) {
 999                 if (group >= f->mcgrp_offset &&
1000                     group < f->mcgrp_offset + f->n_mcgrps) {
1001                         int fam_grp = group - f->mcgrp_offset;
1002
1003                         if (f->mcast_unbind)
1004                                 f->mcast_unbind(net, fam_grp);
1005                         break;
1006                 }
1007         }
1008         up_read(&cb_lock);
1009 }
1010
1011 static int __net_init genl_pernet_init(struct net *net)
1012 {
1013         struct netlink_kernel_cfg cfg = {
1014                 .input          = genl_rcv,
1015                 .flags          = NL_CFG_F_NONROOT_RECV,
1016                 .bind           = genl_bind,
1017                 .unbind         = genl_unbind,
1018         };
1019
1020         /* we'll bump the group number right afterwards */
1021         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1022
1023         if (!net->genl_sock && net_eq(net, &init_net))
1024                 panic("GENL: Cannot initialize generic netlink\n");
1025
1026         if (!net->genl_sock)
1027                 return -ENOMEM;
1028
1029         return 0;
1030 }
1031
1032 static void __net_exit genl_pernet_exit(struct net *net)
1033 {
1034         netlink_kernel_release(net->genl_sock);
1035         net->genl_sock = NULL;
1036 }
1037
1038 static struct pernet_operations genl_pernet_ops = {
1039         .init = genl_pernet_init,
1040         .exit = genl_pernet_exit,
1041 };
1042
1043 static int __init genl_init(void)
1044 {
1045         int err;
1046
1047         err = genl_register_family(&genl_ctrl);
1048         if (err < 0)
1049                 goto problem;
1050
1051         err = register_pernet_subsys(&genl_pernet_ops);
1052         if (err)
1053                 goto problem;
1054
1055         return 0;
1056
1057 problem:
1058         panic("GENL: Cannot register controller: %d\n", err);
1059 }
1060
1061 subsys_initcall(genl_init);
1062
1063 /**
1064  * genl_family_attrbuf - return family's attrbuf
1065  * @family: the family
1066  *
1067  * Return the family's attrbuf, while validating that it's
1068  * actually valid to access it.
1069  *
1070  * You cannot use this function with a family that has parallel_ops
1071  * and you can only use it within (pre/post) doit/dumpit callbacks.
1072  */
1073 struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1074 {
1075         if (!WARN_ON(family->parallel_ops))
1076                 lockdep_assert_held(&genl_mutex);
1077
1078         return family->attrbuf;
1079 }
1080 EXPORT_SYMBOL(genl_family_attrbuf);
1081
1082 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1083                          gfp_t flags)
1084 {
1085         struct sk_buff *tmp;
1086         struct net *net, *prev = NULL;
1087         bool delivered = false;
1088         int err;
1089
1090         for_each_net_rcu(net) {
1091                 if (prev) {
1092                         tmp = skb_clone(skb, flags);
1093                         if (!tmp) {
1094                                 err = -ENOMEM;
1095                                 goto error;
1096                         }
1097                         err = nlmsg_multicast(prev->genl_sock, tmp,
1098                                               portid, group, flags);
1099                         if (!err)
1100                                 delivered = true;
1101                         else if (err != -ESRCH)
1102                                 goto error;
1103                 }
1104
1105                 prev = net;
1106         }
1107
1108         err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1109         if (!err)
1110                 delivered = true;
1111         else if (err != -ESRCH)
1112                 return err;
1113         return delivered ? 0 : -ESRCH;
1114  error:
1115         kfree_skb(skb);
1116         return err;
1117 }
1118
1119 int genlmsg_multicast_allns(const struct genl_family *family,
1120                             struct sk_buff *skb, u32 portid,
1121                             unsigned int group, gfp_t flags)
1122 {
1123         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1124                 return -EINVAL;
1125         group = family->mcgrp_offset + group;
1126         return genlmsg_mcast(skb, portid, group, flags);
1127 }
1128 EXPORT_SYMBOL(genlmsg_multicast_allns);
1129
1130 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1131                  struct genl_info *info, u32 group, gfp_t flags)
1132 {
1133         struct net *net = genl_info_net(info);
1134         struct sock *sk = net->genl_sock;
1135         int report = 0;
1136
1137         if (info->nlhdr)
1138                 report = nlmsg_report(info->nlhdr);
1139
1140         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1141                 return;
1142         group = family->mcgrp_offset + group;
1143         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1144 }
1145 EXPORT_SYMBOL(genl_notify);