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