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 struct genl_dumpit_info *genl_dumpit_info_alloc(void)
 462 {
 463         return kmalloc(sizeof(struct genl_dumpit_info), GFP_KERNEL);
 464 }
 465
 466 static void genl_dumpit_info_free(const struct genl_dumpit_info *info)
 467 {
 468         kfree(info);
 469 }
 470
 471 static struct nlattr **
 472 genl_family_rcv_msg_attrs_parse(const struct genl_family *family,
 473                                 struct nlmsghdr *nlh,
 474                                 struct netlink_ext_ack *extack,
 475                                 const struct genl_ops *ops,
 476                                 int hdrlen,
 477                                 enum genl_validate_flags no_strict_flag,
 478                                 bool parallel)
 479 {
 480         enum netlink_validation validate = ops->validate & no_strict_flag ?
 481                                            NL_VALIDATE_LIBERAL :
 482                                            NL_VALIDATE_STRICT;
 483         struct nlattr **attrbuf;
 484         int err;
 485
 486         if (!family->maxattr)
 487                 return NULL;
 488
 489         if (parallel) {
 490                 attrbuf = kmalloc_array(family->maxattr + 1,
 491                                         sizeof(struct nlattr *), GFP_KERNEL);
 492                 if (!attrbuf)
 493                         return ERR_PTR(-ENOMEM);
 494         } else {
 495                 attrbuf = family->attrbuf;
 496         }
 497
 498         err = __nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 499                             family->policy, validate, extack);
 500         if (err && parallel) {
 501                 kfree(attrbuf);
 502                 return ERR_PTR(err);
 503         }
 504         return attrbuf;
 505 }
 506
 507 static void genl_family_rcv_msg_attrs_free(const struct genl_family *family,
 508                                            struct nlattr **attrbuf,
 509                                            bool parallel)
 510 {
 511         if (parallel)
 512                 kfree(attrbuf);
 513 }
 514
 515 static int genl_lock_start(struct netlink_callback *cb)
 516 {
 517         const struct genl_ops *ops = genl_dumpit_info(cb)->ops;
 518         int rc = 0;
 519
 520         if (ops->start) {
 521                 genl_lock();
 522                 rc = ops->start(cb);
 523                 genl_unlock();
 524         }
 525         return rc;
 526 }
 527
 528 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 529 {
 530         const struct genl_ops *ops = genl_dumpit_info(cb)->ops;
 531         int rc;
 532
 533         genl_lock();
 534         rc = ops->dumpit(skb, cb);
 535         genl_unlock();
 536         return rc;
 537 }
 538
 539 static int genl_lock_done(struct netlink_callback *cb)
 540 {
 541         const struct genl_dumpit_info *info = genl_dumpit_info(cb);
 542         const struct genl_ops *ops = info->ops;
 543         int rc = 0;
 544
 545         if (ops->done) {
 546                 genl_lock();
 547                 rc = ops->done(cb);
 548                 genl_unlock();
 549         }
 550         genl_family_rcv_msg_attrs_free(info->family, info->attrs, true);
 551         genl_dumpit_info_free(info);
 552         return rc;
 553 }
 554
 555 static int genl_parallel_done(struct netlink_callback *cb)
 556 {
 557         const struct genl_dumpit_info *info = genl_dumpit_info(cb);
 558         const struct genl_ops *ops = info->ops;
 559         int rc = 0;
 560
 561         if (ops->done)
 562                 rc = ops->done(cb);
 563         genl_family_rcv_msg_attrs_free(info->family, info->attrs, true);
 564         genl_dumpit_info_free(info);
 565         return rc;
 566 }
 567
 568 static int genl_family_rcv_msg_dumpit(const struct genl_family *family,
 569                                       struct sk_buff *skb,
 570                                       struct nlmsghdr *nlh,
 571                                       struct netlink_ext_ack *extack,
 572                                       const struct genl_ops *ops,
 573                                       int hdrlen, struct net *net)
 574 {
 575         struct genl_dumpit_info *info;
 576         struct nlattr **attrs = NULL;
 577         int err;
 578
 579         if (!ops->dumpit)
 580                 return -EOPNOTSUPP;
 581
 582         if (ops->validate & GENL_DONT_VALIDATE_DUMP)
 583                 goto no_attrs;
 584
 585         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 586                 return -EINVAL;
 587
 588         attrs = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
 589                                                 ops, hdrlen,
 590                                                 GENL_DONT_VALIDATE_DUMP_STRICT,
 591                                                 true);
 592         if (IS_ERR(attrs))
 593                 return PTR_ERR(attrs);
 594
 595 no_attrs:
 596         /* Allocate dumpit info. It is going to be freed by done() callback. */
 597         info = genl_dumpit_info_alloc();
 598         if (!info) {
 599                 genl_family_rcv_msg_attrs_free(family, attrs, true);
 600                 return -ENOMEM;
 601         }
 602
 603         info->family = family;
 604         info->ops = ops;
 605         info->attrs = attrs;
 606
 607         if (!family->parallel_ops) {
 608                 struct netlink_dump_control c = {
 609                         .module = family->module,
 610                         .data = info,
 611                         .start = genl_lock_start,
 612                         .dump = genl_lock_dumpit,
 613                         .done = genl_lock_done,
 614                 };
 615
 616                 genl_unlock();
 617                 err = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 618                 genl_lock();
 619
 620         } else {
 621                 struct netlink_dump_control c = {
 622                         .module = family->module,
 623                         .data = info,
 624                         .start = ops->start,
 625                         .dump = ops->dumpit,
 626                         .done = genl_parallel_done,
 627                 };
 628
 629                 err = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 630         }
 631
 632         return err;
 633 }
 634
 635 static int genl_family_rcv_msg_doit(const struct genl_family *family,
 636                                     struct sk_buff *skb,
 637                                     struct nlmsghdr *nlh,
 638                                     struct netlink_ext_ack *extack,
 639                                     const struct genl_ops *ops,
 640                                     int hdrlen, struct net *net)
 641 {
 642         struct nlattr **attrbuf;
 643         struct genl_info info;
 644         int err;
 645
 646         if (!ops->doit)
 647                 return -EOPNOTSUPP;
 648
 649         attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
 650                                                   ops, hdrlen,
 651                                                   GENL_DONT_VALIDATE_STRICT,
 652                                                   family->parallel_ops);
 653         if (IS_ERR(attrbuf))
 654                 return PTR_ERR(attrbuf);
 655
 656         info.snd_seq = nlh->nlmsg_seq;
 657         info.snd_portid = NETLINK_CB(skb).portid;
 658         info.nlhdr = nlh;
 659         info.genlhdr = nlmsg_data(nlh);
 660         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 661         info.attrs = attrbuf;
 662         info.extack = extack;
 663         genl_info_net_set(&info, net);
 664         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 665
 666         if (family->pre_doit) {
 667                 err = family->pre_doit(ops, skb, &info);
 668                 if (err)
 669                         goto out;
 670         }
 671
 672         err = ops->doit(skb, &info);
 673
 674         if (family->post_doit)
 675                 family->post_doit(ops, skb, &info);
 676
 677 out:
 678         genl_family_rcv_msg_attrs_free(family, attrbuf, family->parallel_ops);
 679
 680         return err;
 681 }
 682
 683 static int genl_family_rcv_msg(const struct genl_family *family,
 684                                struct sk_buff *skb,
 685                                struct nlmsghdr *nlh,
 686                                struct netlink_ext_ack *extack)
 687 {
 688         const struct genl_ops *ops;
 689         struct net *net = sock_net(skb->sk);
 690         struct genlmsghdr *hdr = nlmsg_data(nlh);
 691         int hdrlen;
 692
 693         /* this family doesn't exist in this netns */
 694         if (!family->netnsok && !net_eq(net, &init_net))
 695                 return -ENOENT;
 696
 697         hdrlen = GENL_HDRLEN + family->hdrsize;
 698         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 699                 return -EINVAL;
 700
 701         ops = genl_get_cmd(hdr->cmd, family);
 702         if (ops == NULL)
 703                 return -EOPNOTSUPP;
 704
 705         if ((ops->flags & GENL_ADMIN_PERM) &&
 706             !netlink_capable(skb, CAP_NET_ADMIN))
 707                 return -EPERM;
 708
 709         if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
 710             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 711                 return -EPERM;
 712
 713         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP)
 714                 return genl_family_rcv_msg_dumpit(family, skb, nlh, extack,
 715                                                   ops, hdrlen, net);
 716         else
 717                 return genl_family_rcv_msg_doit(family, skb, nlh, extack,
 718                                                 ops, hdrlen, net);
 719 }
 720
 721 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 722                         struct netlink_ext_ack *extack)
 723 {
 724         const struct genl_family *family;
 725         int err;
 726
 727         family = genl_family_find_byid(nlh->nlmsg_type);
 728         if (family == NULL)
 729                 return -ENOENT;
 730
 731         if (!family->parallel_ops)
 732                 genl_lock();
 733
 734         err = genl_family_rcv_msg(family, skb, nlh, extack);
 735
 736         if (!family->parallel_ops)
 737                 genl_unlock();
 738
 739         return err;
 740 }
 741
 742 static void genl_rcv(struct sk_buff *skb)
 743 {
 744         down_read(&cb_lock);
 745         netlink_rcv_skb(skb, &genl_rcv_msg);
 746         up_read(&cb_lock);
 747 }
 748
 749 /**************************************************************************
 750  * Controller
 751  **************************************************************************/
 752
 753 static struct genl_family genl_ctrl;
 754
 755 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 756                           u32 flags, struct sk_buff *skb, u8 cmd)
 757 {
 758         void *hdr;
 759
 760         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 761         if (hdr == NULL)
 762                 return -1;
 763
 764         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 765             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 766             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 767             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 768             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 769                 goto nla_put_failure;
 770
 771         if (family->n_ops) {
 772                 struct nlattr *nla_ops;
 773                 int i;
 774
 775                 nla_ops = nla_nest_start_noflag(skb, CTRL_ATTR_OPS);
 776                 if (nla_ops == NULL)
 777                         goto nla_put_failure;
 778
 779                 for (i = 0; i < family->n_ops; i++) {
 780                         struct nlattr *nest;
 781                         const struct genl_ops *ops = &family->ops[i];
 782                         u32 op_flags = ops->flags;
 783
 784                         if (ops->dumpit)
 785                                 op_flags |= GENL_CMD_CAP_DUMP;
 786                         if (ops->doit)
 787                                 op_flags |= GENL_CMD_CAP_DO;
 788                         if (family->policy)
 789                                 op_flags |= GENL_CMD_CAP_HASPOL;
 790
 791                         nest = nla_nest_start_noflag(skb, i + 1);
 792                         if (nest == NULL)
 793                                 goto nla_put_failure;
 794
 795                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 796                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 797                                 goto nla_put_failure;
 798
 799                         nla_nest_end(skb, nest);
 800                 }
 801
 802                 nla_nest_end(skb, nla_ops);
 803         }
 804
 805         if (family->n_mcgrps) {
 806                 struct nlattr *nla_grps;
 807                 int i;
 808
 809                 nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
 810                 if (nla_grps == NULL)
 811                         goto nla_put_failure;
 812
 813                 for (i = 0; i < family->n_mcgrps; i++) {
 814                         struct nlattr *nest;
 815                         const struct genl_multicast_group *grp;
 816
 817                         grp = &family->mcgrps[i];
 818
 819                         nest = nla_nest_start_noflag(skb, i + 1);
 820                         if (nest == NULL)
 821                                 goto nla_put_failure;
 822
 823                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 824                                         family->mcgrp_offset + i) ||
 825                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 826                                            grp->name))
 827                                 goto nla_put_failure;
 828
 829                         nla_nest_end(skb, nest);
 830                 }
 831                 nla_nest_end(skb, nla_grps);
 832         }
 833
 834         genlmsg_end(skb, hdr);
 835         return 0;
 836
 837 nla_put_failure:
 838         genlmsg_cancel(skb, hdr);
 839         return -EMSGSIZE;
 840 }
 841
 842 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
 843                                 const struct genl_multicast_group *grp,
 844                                 int grp_id, u32 portid, u32 seq, u32 flags,
 845                                 struct sk_buff *skb, u8 cmd)
 846 {
 847         void *hdr;
 848         struct nlattr *nla_grps;
 849         struct nlattr *nest;
 850
 851         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 852         if (hdr == NULL)
 853                 return -1;
 854
 855         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 856             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 857                 goto nla_put_failure;
 858
 859         nla_grps = nla_nest_start_noflag(skb, CTRL_ATTR_MCAST_GROUPS);
 860         if (nla_grps == NULL)
 861                 goto nla_put_failure;
 862
 863         nest = nla_nest_start_noflag(skb, 1);
 864         if (nest == NULL)
 865                 goto nla_put_failure;
 866
 867         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 868             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 869                            grp->name))
 870                 goto nla_put_failure;
 871
 872         nla_nest_end(skb, nest);
 873         nla_nest_end(skb, nla_grps);
 874
 875         genlmsg_end(skb, hdr);
 876         return 0;
 877
 878 nla_put_failure:
 879         genlmsg_cancel(skb, hdr);
 880         return -EMSGSIZE;
 881 }
 882
 883 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 884 {
 885         int n = 0;
 886         struct genl_family *rt;
 887         struct net *net = sock_net(skb->sk);
 888         int fams_to_skip = cb->args[0];
 889         unsigned int id;
 890
 891         idr_for_each_entry(&genl_fam_idr, rt, id) {
 892                 if (!rt->netnsok && !net_eq(net, &init_net))
 893                         continue;
 894
 895                 if (n++ < fams_to_skip)
 896                         continue;
 897
 898                 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 899                                    cb->nlh->nlmsg_seq, NLM_F_MULTI,
 900                                    skb, CTRL_CMD_NEWFAMILY) < 0) {
 901                         n--;
 902                         break;
 903                 }
 904         }
 905
 906         cb->args[0] = n;
 907         return skb->len;
 908 }
 909
 910 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
 911                                              u32 portid, int seq, u8 cmd)
 912 {
 913         struct sk_buff *skb;
 914         int err;
 915
 916         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 917         if (skb == NULL)
 918                 return ERR_PTR(-ENOBUFS);
 919
 920         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 921         if (err < 0) {
 922                 nlmsg_free(skb);
 923                 return ERR_PTR(err);
 924         }
 925
 926         return skb;
 927 }
 928
 929 static struct sk_buff *
 930 ctrl_build_mcgrp_msg(const struct genl_family *family,
 931                      const struct genl_multicast_group *grp,
 932                      int grp_id, u32 portid, int seq, u8 cmd)
 933 {
 934         struct sk_buff *skb;
 935         int err;
 936
 937         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 938         if (skb == NULL)
 939                 return ERR_PTR(-ENOBUFS);
 940
 941         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 942                                    seq, 0, skb, cmd);
 943         if (err < 0) {
 944                 nlmsg_free(skb);
 945                 return ERR_PTR(err);
 946         }
 947
 948         return skb;
 949 }
 950
 951 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 952         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 953         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 954                                     .len = GENL_NAMSIZ - 1 },
 955 };
 956
 957 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 958 {
 959         struct sk_buff *msg;
 960         const struct genl_family *res = NULL;
 961         int err = -EINVAL;
 962
 963         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 964                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 965                 res = genl_family_find_byid(id);
 966                 err = -ENOENT;
 967         }
 968
 969         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 970                 char *name;
 971
 972                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 973                 res = genl_family_find_byname(name);
 974 #ifdef CONFIG_MODULES
 975                 if (res == NULL) {
 976                         genl_unlock();
 977                         up_read(&cb_lock);
 978                         request_module("net-pf-%d-proto-%d-family-%s",
 979                                        PF_NETLINK, NETLINK_GENERIC, name);
 980                         down_read(&cb_lock);
 981                         genl_lock();
 982                         res = genl_family_find_byname(name);
 983                 }
 984 #endif
 985                 err = -ENOENT;
 986         }
 987
 988         if (res == NULL)
 989                 return err;
 990
 991         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 992                 /* family doesn't exist here */
 993                 return -ENOENT;
 994         }
 995
 996         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 997                                     CTRL_CMD_NEWFAMILY);
 998         if (IS_ERR(msg))
 999                 return PTR_ERR(msg);
1000
1001         return genlmsg_reply(msg, info);
1002 }
1003
1004 static int genl_ctrl_event(int event, const struct genl_family *family,
1005                            const struct genl_multicast_group *grp,
1006                            int grp_id)
1007 {
1008         struct sk_buff *msg;
1009
1010         /* genl is still initialising */
1011         if (!init_net.genl_sock)
1012                 return 0;
1013
1014         switch (event) {
1015         case CTRL_CMD_NEWFAMILY:
1016         case CTRL_CMD_DELFAMILY:
1017                 WARN_ON(grp);
1018                 msg = ctrl_build_family_msg(family, 0, 0, event);
1019                 break;
1020         case CTRL_CMD_NEWMCAST_GRP:
1021         case CTRL_CMD_DELMCAST_GRP:
1022                 BUG_ON(!grp);
1023                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
1024                 break;
1025         default:
1026                 return -EINVAL;
1027         }
1028
1029         if (IS_ERR(msg))
1030                 return PTR_ERR(msg);
1031
1032         if (!family->netnsok) {
1033                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
1034                                         0, GFP_KERNEL);
1035         } else {
1036                 rcu_read_lock();
1037                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
1038                                         0, GFP_ATOMIC);
1039                 rcu_read_unlock();
1040         }
1041
1042         return 0;
1043 }
1044
1045 static const struct genl_ops genl_ctrl_ops[] = {
1046         {
1047                 .cmd            = CTRL_CMD_GETFAMILY,
1048                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
1049                 .doit           = ctrl_getfamily,
1050                 .dumpit         = ctrl_dumpfamily,
1051         },
1052 };
1053
1054 static const struct genl_multicast_group genl_ctrl_groups[] = {
1055         { .name = "notify", },
1056 };
1057
1058 static struct genl_family genl_ctrl __ro_after_init = {
1059         .module = THIS_MODULE,
1060         .ops = genl_ctrl_ops,
1061         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
1062         .mcgrps = genl_ctrl_groups,
1063         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
1064         .id = GENL_ID_CTRL,
1065         .name = "nlctrl",
1066         .version = 0x2,
1067         .maxattr = CTRL_ATTR_MAX,
1068         .policy = ctrl_policy,
1069         .netnsok = true,
1070 };
1071
1072 static int genl_bind(struct net *net, int group)
1073 {
1074         struct genl_family *f;
1075         int err = -ENOENT;
1076         unsigned int id;
1077
1078         down_read(&cb_lock);
1079
1080         idr_for_each_entry(&genl_fam_idr, f, id) {
1081                 if (group >= f->mcgrp_offset &&
1082                     group < f->mcgrp_offset + f->n_mcgrps) {
1083                         int fam_grp = group - f->mcgrp_offset;
1084
1085                         if (!f->netnsok && net != &init_net)
1086                                 err = -ENOENT;
1087                         else if (f->mcast_bind)
1088                                 err = f->mcast_bind(net, fam_grp);
1089                         else
1090                                 err = 0;
1091                         break;
1092                 }
1093         }
1094         up_read(&cb_lock);
1095
1096         return err;
1097 }
1098
1099 static void genl_unbind(struct net *net, int group)
1100 {
1101         struct genl_family *f;
1102         unsigned int id;
1103
1104         down_read(&cb_lock);
1105
1106         idr_for_each_entry(&genl_fam_idr, f, id) {
1107                 if (group >= f->mcgrp_offset &&
1108                     group < f->mcgrp_offset + f->n_mcgrps) {
1109                         int fam_grp = group - f->mcgrp_offset;
1110
1111                         if (f->mcast_unbind)
1112                                 f->mcast_unbind(net, fam_grp);
1113                         break;
1114                 }
1115         }
1116         up_read(&cb_lock);
1117 }
1118
1119 static int __net_init genl_pernet_init(struct net *net)
1120 {
1121         struct netlink_kernel_cfg cfg = {
1122                 .input          = genl_rcv,
1123                 .flags          = NL_CFG_F_NONROOT_RECV,
1124                 .bind           = genl_bind,
1125                 .unbind         = genl_unbind,
1126         };
1127
1128         /* we'll bump the group number right afterwards */
1129         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1130
1131         if (!net->genl_sock && net_eq(net, &init_net))
1132                 panic("GENL: Cannot initialize generic netlink\n");
1133
1134         if (!net->genl_sock)
1135                 return -ENOMEM;
1136
1137         return 0;
1138 }
1139
1140 static void __net_exit genl_pernet_exit(struct net *net)
1141 {
1142         netlink_kernel_release(net->genl_sock);
1143         net->genl_sock = NULL;
1144 }
1145
1146 static struct pernet_operations genl_pernet_ops = {
1147         .init = genl_pernet_init,
1148         .exit = genl_pernet_exit,
1149 };
1150
1151 static int __init genl_init(void)
1152 {
1153         int err;
1154
1155         err = genl_register_family(&genl_ctrl);
1156         if (err < 0)
1157                 goto problem;
1158
1159         err = register_pernet_subsys(&genl_pernet_ops);
1160         if (err)
1161                 goto problem;
1162
1163         return 0;
1164
1165 problem:
1166         panic("GENL: Cannot register controller: %d\n", err);
1167 }
1168
1169 subsys_initcall(genl_init);
1170
1171 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1172                          gfp_t flags)
1173 {
1174         struct sk_buff *tmp;
1175         struct net *net, *prev = NULL;
1176         bool delivered = false;
1177         int err;
1178
1179         for_each_net_rcu(net) {
1180                 if (prev) {
1181                         tmp = skb_clone(skb, flags);
1182                         if (!tmp) {
1183                                 err = -ENOMEM;
1184                                 goto error;
1185                         }
1186                         err = nlmsg_multicast(prev->genl_sock, tmp,
1187                                               portid, group, flags);
1188                         if (!err)
1189                                 delivered = true;
1190                         else if (err != -ESRCH)
1191                                 goto error;
1192                 }
1193
1194                 prev = net;
1195         }
1196
1197         err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1198         if (!err)
1199                 delivered = true;
1200         else if (err != -ESRCH)
1201                 return err;
1202         return delivered ? 0 : -ESRCH;
1203  error:
1204         kfree_skb(skb);
1205         return err;
1206 }
1207
1208 int genlmsg_multicast_allns(const struct genl_family *family,
1209                             struct sk_buff *skb, u32 portid,
1210                             unsigned int group, gfp_t flags)
1211 {
1212         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1213                 return -EINVAL;
1214         group = family->mcgrp_offset + group;
1215         return genlmsg_mcast(skb, portid, group, flags);
1216 }
1217 EXPORT_SYMBOL(genlmsg_multicast_allns);
1218
1219 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1220                  struct genl_info *info, u32 group, gfp_t flags)
1221 {
1222         struct net *net = genl_info_net(info);
1223         struct sock *sk = net->genl_sock;
1224         int report = 0;
1225
1226         if (info->nlhdr)
1227                 report = nlmsg_report(info->nlhdr);
1228
1229         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1230                 return;
1231         group = family->mcgrp_offset + group;
1232         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1233 }
1234 EXPORT_SYMBOL(genl_notify);