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 (!(ops->validate & GENL_DONT_VALIDATE_DUMP)) {
 540                         int hdrlen = GENL_HDRLEN + family->hdrsize;
 541
 542                         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 543                                 return -EINVAL;
 544
 545                         if (family->maxattr) {
 546                                 unsigned int validate = NL_VALIDATE_STRICT;
 547
 548                                 if (ops->validate &
 549                                     GENL_DONT_VALIDATE_DUMP_STRICT)
 550                                         validate = NL_VALIDATE_LIBERAL;
 551                                 rc = __nla_validate(nlmsg_attrdata(nlh, hdrlen),
 552                                                     nlmsg_attrlen(nlh, hdrlen),
 553                                                     family->maxattr,
 554                                                     family->policy,
 555                                                     validate, extack);
 556                                 if (rc)
 557                                         return rc;
 558                         }
 559                 }
 560
 561                 if (!family->parallel_ops) {
 562                         struct netlink_dump_control c = {
 563                                 .module = family->module,
 564                                 /* we have const, but the netlink API doesn't */
 565                                 .data = (void *)ops,
 566                                 .start = genl_lock_start,
 567                                 .dump = genl_lock_dumpit,
 568                                 .done = genl_lock_done,
 569                         };
 570
 571                         genl_unlock();
 572                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 573                         genl_lock();
 574
 575                 } else {
 576                         struct netlink_dump_control c = {
 577                                 .module = family->module,
 578                                 .start = ops->start,
 579                                 .dump = ops->dumpit,
 580                                 .done = ops->done,
 581                         };
 582
 583                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 584                 }
 585
 586                 return rc;
 587         }
 588
 589         if (ops->doit == NULL)
 590                 return -EOPNOTSUPP;
 591
 592         if (family->maxattr && family->parallel_ops) {
 593                 attrbuf = kmalloc_array(family->maxattr + 1,
 594                                         sizeof(struct nlattr *),
 595                                         GFP_KERNEL);
 596                 if (attrbuf == NULL)
 597                         return -ENOMEM;
 598         } else
 599                 attrbuf = family->attrbuf;
 600
 601         if (attrbuf) {
 602                 enum netlink_validation validate = NL_VALIDATE_STRICT;
 603
 604                 if (ops->validate & GENL_DONT_VALIDATE_STRICT)
 605                         validate = NL_VALIDATE_LIBERAL;
 606
 607                 err = __nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 608                                     family->policy, validate, extack);
 609                 if (err < 0)
 610                         goto out;
 611         }
 612
 613         info.snd_seq = nlh->nlmsg_seq;
 614         info.snd_portid = NETLINK_CB(skb).portid;
 615         info.nlhdr = nlh;
 616         info.genlhdr = nlmsg_data(nlh);
 617         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 618         info.attrs = attrbuf;
 619         info.extack = extack;
 620         genl_info_net_set(&info, net);
 621         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 622
 623         if (family->pre_doit) {
 624                 err = family->pre_doit(ops, skb, &info);
 625                 if (err)
 626                         goto out;
 627         }
 628
 629         err = ops->doit(skb, &info);
 630
 631         if (family->post_doit)
 632                 family->post_doit(ops, skb, &info);
 633
 634 out:
 635         if (family->parallel_ops)
 636                 kfree(attrbuf);
 637
 638         return err;
 639 }
 640
 641 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 642                         struct netlink_ext_ack *extack)
 643 {
 644         const struct genl_family *family;
 645         int err;
 646
 647         family = genl_family_find_byid(nlh->nlmsg_type);
 648         if (family == NULL)
 649                 return -ENOENT;
 650
 651         if (!family->parallel_ops)
 652                 genl_lock();
 653
 654         err = genl_family_rcv_msg(family, skb, nlh, extack);
 655
 656         if (!family->parallel_ops)
 657                 genl_unlock();
 658
 659         return err;
 660 }
 661
 662 static void genl_rcv(struct sk_buff *skb)
 663 {
 664         down_read(&cb_lock);
 665         netlink_rcv_skb(skb, &genl_rcv_msg);
 666         up_read(&cb_lock);
 667 }
 668
 669 /**************************************************************************
 670  * Controller
 671  **************************************************************************/
 672
 673 static struct genl_family genl_ctrl;
 674
 675 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 676                           u32 flags, struct sk_buff *skb, u8 cmd)
 677 {
 678         void *hdr;
 679
 680         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 681         if (hdr == NULL)
 682                 return -1;
 683
 684         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 685             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 686             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 687             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 688             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 689                 goto nla_put_failure;
 690
 691         if (family->n_ops) {
 692                 struct nlattr *nla_ops;
 693                 int i;
 694
 695                 nla_ops = nla_nest_start_noflag(skb, CTRL_ATTR_OPS);
 696                 if (nla_ops == NULL)
 697                         goto nla_put_failure;
 698
 699                 for (i = 0; i < family->n_ops; i++) {
 700                         struct nlattr *nest;
 701                         const struct genl_ops *ops = &family->ops[i];
 702                         u32 op_flags = ops->flags;
 703
 704                         if (ops->dumpit)
 705                                 op_flags |= GENL_CMD_CAP_DUMP;
 706                         if (ops->doit)
 707                                 op_flags |= GENL_CMD_CAP_DO;
 708                         if (family->policy)
 709                                 op_flags |= GENL_CMD_CAP_HASPOL;
 710
 711                         nest = nla_nest_start_noflag(skb, i + 1);
 712                         if (nest == NULL)
 713                                 goto nla_put_failure;
 714
 715                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 716                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 717                                 goto nla_put_failure;
 718
 719                         nla_nest_end(skb, nest);
 720                 }
 721
 722                 nla_nest_end(skb, nla_ops);
 723         }
 724
 725         if (family->n_mcgrps) {
 726                 struct nlattr *nla_grps;
 727                 int i;
 728
 729                 nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
 730                 if (nla_grps == NULL)
 731                         goto nla_put_failure;
 732
 733                 for (i = 0; i < family->n_mcgrps; i++) {
 734                         struct nlattr *nest;
 735                         const struct genl_multicast_group *grp;
 736
 737                         grp = &family->mcgrps[i];
 738
 739                         nest = nla_nest_start_noflag(skb, i + 1);
 740                         if (nest == NULL)
 741                                 goto nla_put_failure;
 742
 743                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 744                                         family->mcgrp_offset + i) ||
 745                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 746                                            grp->name))
 747                                 goto nla_put_failure;
 748
 749                         nla_nest_end(skb, nest);
 750                 }
 751                 nla_nest_end(skb, nla_grps);
 752         }
 753
 754         genlmsg_end(skb, hdr);
 755         return 0;
 756
 757 nla_put_failure:
 758         genlmsg_cancel(skb, hdr);
 759         return -EMSGSIZE;
 760 }
 761
 762 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
 763                                 const struct genl_multicast_group *grp,
 764                                 int grp_id, u32 portid, u32 seq, u32 flags,
 765                                 struct sk_buff *skb, u8 cmd)
 766 {
 767         void *hdr;
 768         struct nlattr *nla_grps;
 769         struct nlattr *nest;
 770
 771         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 772         if (hdr == NULL)
 773                 return -1;
 774
 775         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 776             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 777                 goto nla_put_failure;
 778
 779         nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
 780         if (nla_grps == NULL)
 781                 goto nla_put_failure;
 782
 783         nest = nla_nest_start_noflag(skb, 1);
 784         if (nest == NULL)
 785                 goto nla_put_failure;
 786
 787         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 788             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 789                            grp->name))
 790                 goto nla_put_failure;
 791
 792         nla_nest_end(skb, nest);
 793         nla_nest_end(skb, nla_grps);
 794
 795         genlmsg_end(skb, hdr);
 796         return 0;
 797
 798 nla_put_failure:
 799         genlmsg_cancel(skb, hdr);
 800         return -EMSGSIZE;
 801 }
 802
 803 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 804 {
 805         int n = 0;
 806         struct genl_family *rt;
 807         struct net *net = sock_net(skb->sk);
 808         int fams_to_skip = cb->args[0];
 809         unsigned int id;
 810
 811         idr_for_each_entry(&genl_fam_idr, rt, id) {
 812                 if (!rt->netnsok && !net_eq(net, &init_net))
 813                         continue;
 814
 815                 if (n++ < fams_to_skip)
 816                         continue;
 817
 818                 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 819                                    cb->nlh->nlmsg_seq, NLM_F_MULTI,
 820                                    skb, CTRL_CMD_NEWFAMILY) < 0) {
 821                         n--;
 822                         break;
 823                 }
 824         }
 825
 826         cb->args[0] = n;
 827         return skb->len;
 828 }
 829
 830 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
 831                                              u32 portid, int seq, u8 cmd)
 832 {
 833         struct sk_buff *skb;
 834         int err;
 835
 836         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 837         if (skb == NULL)
 838                 return ERR_PTR(-ENOBUFS);
 839
 840         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 841         if (err < 0) {
 842                 nlmsg_free(skb);
 843                 return ERR_PTR(err);
 844         }
 845
 846         return skb;
 847 }
 848
 849 static struct sk_buff *
 850 ctrl_build_mcgrp_msg(const struct genl_family *family,
 851                      const struct genl_multicast_group *grp,
 852                      int grp_id, u32 portid, int seq, u8 cmd)
 853 {
 854         struct sk_buff *skb;
 855         int err;
 856
 857         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 858         if (skb == NULL)
 859                 return ERR_PTR(-ENOBUFS);
 860
 861         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 862                                    seq, 0, skb, cmd);
 863         if (err < 0) {
 864                 nlmsg_free(skb);
 865                 return ERR_PTR(err);
 866         }
 867
 868         return skb;
 869 }
 870
 871 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 872         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 873         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 874                                     .len = GENL_NAMSIZ - 1 },
 875 };
 876
 877 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 878 {
 879         struct sk_buff *msg;
 880         const struct genl_family *res = NULL;
 881         int err = -EINVAL;
 882
 883         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 884                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 885                 res = genl_family_find_byid(id);
 886                 err = -ENOENT;
 887         }
 888
 889         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 890                 char *name;
 891
 892                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 893                 res = genl_family_find_byname(name);
 894 #ifdef CONFIG_MODULES
 895                 if (res == NULL) {
 896                         genl_unlock();
 897                         up_read(&cb_lock);
 898                         request_module("net-pf-%d-proto-%d-family-%s",
 899                                        PF_NETLINK, NETLINK_GENERIC, name);
 900                         down_read(&cb_lock);
 901                         genl_lock();
 902                         res = genl_family_find_byname(name);
 903                 }
 904 #endif
 905                 err = -ENOENT;
 906         }
 907
 908         if (res == NULL)
 909                 return err;
 910
 911         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 912                 /* family doesn't exist here */
 913                 return -ENOENT;
 914         }
 915
 916         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 917                                     CTRL_CMD_NEWFAMILY);
 918         if (IS_ERR(msg))
 919                 return PTR_ERR(msg);
 920
 921         return genlmsg_reply(msg, info);
 922 }
 923
 924 static int genl_ctrl_event(int event, const struct genl_family *family,
 925                            const struct genl_multicast_group *grp,
 926                            int grp_id)
 927 {
 928         struct sk_buff *msg;
 929
 930         /* genl is still initialising */
 931         if (!init_net.genl_sock)
 932                 return 0;
 933
 934         switch (event) {
 935         case CTRL_CMD_NEWFAMILY:
 936         case CTRL_CMD_DELFAMILY:
 937                 WARN_ON(grp);
 938                 msg = ctrl_build_family_msg(family, 0, 0, event);
 939                 break;
 940         case CTRL_CMD_NEWMCAST_GRP:
 941         case CTRL_CMD_DELMCAST_GRP:
 942                 BUG_ON(!grp);
 943                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 944                 break;
 945         default:
 946                 return -EINVAL;
 947         }
 948
 949         if (IS_ERR(msg))
 950                 return PTR_ERR(msg);
 951
 952         if (!family->netnsok) {
 953                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 954                                         0, GFP_KERNEL);
 955         } else {
 956                 rcu_read_lock();
 957                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 958                                         0, GFP_ATOMIC);
 959                 rcu_read_unlock();
 960         }
 961
 962         return 0;
 963 }
 964
 965 static const struct genl_ops genl_ctrl_ops[] = {
 966         {
 967                 .cmd            = CTRL_CMD_GETFAMILY,
 968                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 969                 .doit           = ctrl_getfamily,
 970                 .dumpit         = ctrl_dumpfamily,
 971         },
 972 };
 973
 974 static const struct genl_multicast_group genl_ctrl_groups[] = {
 975         { .name = "notify", },
 976 };
 977
 978 static struct genl_family genl_ctrl __ro_after_init = {
 979         .module = THIS_MODULE,
 980         .ops = genl_ctrl_ops,
 981         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
 982         .mcgrps = genl_ctrl_groups,
 983         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
 984         .id = GENL_ID_CTRL,
 985         .name = "nlctrl",
 986         .version = 0x2,
 987         .maxattr = CTRL_ATTR_MAX,
 988         .policy = ctrl_policy,
 989         .netnsok = true,
 990 };
 991
 992 static int genl_bind(struct net *net, int group)
 993 {
 994         struct genl_family *f;
 995         int err = -ENOENT;
 996         unsigned int id;
 997
 998         down_read(&cb_lock);
 999
1000         idr_for_each_entry(&genl_fam_idr, f, id) {
1001                 if (group >= f->mcgrp_offset &&
1002                     group < f->mcgrp_offset + f->n_mcgrps) {
1003                         int fam_grp = group - f->mcgrp_offset;
1004
1005                         if (!f->netnsok && net != &init_net)
1006                                 err = -ENOENT;
1007                         else if (f->mcast_bind)
1008                                 err = f->mcast_bind(net, fam_grp);
1009                         else
1010                                 err = 0;
1011                         break;
1012                 }
1013         }
1014         up_read(&cb_lock);
1015
1016         return err;
1017 }
1018
1019 static void genl_unbind(struct net *net, int group)
1020 {
1021         struct genl_family *f;
1022         unsigned int id;
1023
1024         down_read(&cb_lock);
1025
1026         idr_for_each_entry(&genl_fam_idr, f, id) {
1027                 if (group >= f->mcgrp_offset &&
1028                     group < f->mcgrp_offset + f->n_mcgrps) {
1029                         int fam_grp = group - f->mcgrp_offset;
1030
1031                         if (f->mcast_unbind)
1032                                 f->mcast_unbind(net, fam_grp);
1033                         break;
1034                 }
1035         }
1036         up_read(&cb_lock);
1037 }
1038
1039 static int __net_init genl_pernet_init(struct net *net)
1040 {
1041         struct netlink_kernel_cfg cfg = {
1042                 .input          = genl_rcv,
1043                 .flags          = NL_CFG_F_NONROOT_RECV,
1044                 .bind           = genl_bind,
1045                 .unbind         = genl_unbind,
1046         };
1047
1048         /* we'll bump the group number right afterwards */
1049         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1050
1051         if (!net->genl_sock && net_eq(net, &init_net))
1052                 panic("GENL: Cannot initialize generic netlink\n");
1053
1054         if (!net->genl_sock)
1055                 return -ENOMEM;
1056
1057         return 0;
1058 }
1059
1060 static void __net_exit genl_pernet_exit(struct net *net)
1061 {
1062         netlink_kernel_release(net->genl_sock);
1063         net->genl_sock = NULL;
1064 }
1065
1066 static struct pernet_operations genl_pernet_ops = {
1067         .init = genl_pernet_init,
1068         .exit = genl_pernet_exit,
1069 };
1070
1071 static int __init genl_init(void)
1072 {
1073         int err;
1074
1075         err = genl_register_family(&genl_ctrl);
1076         if (err < 0)
1077                 goto problem;
1078
1079         err = register_pernet_subsys(&genl_pernet_ops);
1080         if (err)
1081                 goto problem;
1082
1083         return 0;
1084
1085 problem:
1086         panic("GENL: Cannot register controller: %d\n", err);
1087 }
1088
1089 subsys_initcall(genl_init);
1090
1091 /**
1092  * genl_family_attrbuf - return family's attrbuf
1093  * @family: the family
1094  *
1095  * Return the family's attrbuf, while validating that it's
1096  * actually valid to access it.
1097  *
1098  * You cannot use this function with a family that has parallel_ops
1099  * and you can only use it within (pre/post) doit/dumpit callbacks.
1100  */
1101 struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1102 {
1103         if (!WARN_ON(family->parallel_ops))
1104                 lockdep_assert_held(&genl_mutex);
1105
1106         return family->attrbuf;
1107 }
1108 EXPORT_SYMBOL(genl_family_attrbuf);
1109
1110 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1111                          gfp_t flags)
1112 {
1113         struct sk_buff *tmp;
1114         struct net *net, *prev = NULL;
1115         bool delivered = false;
1116         int err;
1117
1118         for_each_net_rcu(net) {
1119                 if (prev) {
1120                         tmp = skb_clone(skb, flags);
1121                         if (!tmp) {
1122                                 err = -ENOMEM;
1123                                 goto error;
1124                         }
1125                         err = nlmsg_multicast(prev->genl_sock, tmp,
1126                                               portid, group, flags);
1127                         if (!err)
1128                                 delivered = true;
1129                         else if (err != -ESRCH)
1130                                 goto error;
1131                 }
1132
1133                 prev = net;
1134         }
1135
1136         err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1137         if (!err)
1138                 delivered = true;
1139         else if (err != -ESRCH)
1140                 return err;
1141         return delivered ? 0 : -ESRCH;
1142  error:
1143         kfree_skb(skb);
1144         return err;
1145 }
1146
1147 int genlmsg_multicast_allns(const struct genl_family *family,
1148                             struct sk_buff *skb, u32 portid,
1149                             unsigned int group, gfp_t flags)
1150 {
1151         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1152                 return -EINVAL;
1153         group = family->mcgrp_offset + group;
1154         return genlmsg_mcast(skb, portid, group, flags);
1155 }
1156 EXPORT_SYMBOL(genlmsg_multicast_allns);
1157
1158 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1159                  struct genl_info *info, u32 group, gfp_t flags)
1160 {
1161         struct net *net = genl_info_net(info);
1162         struct sock *sk = net->genl_sock;
1163         int report = 0;
1164
1165         if (info->nlhdr)
1166                 report = nlmsg_report(info->nlhdr);
1167
1168         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1169                 return;
1170         group = family->mcgrp_offset + group;
1171         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1172 }
1173 EXPORT_SYMBOL(genl_notify);