net/netlink/genetlink.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * NETLINK      Generic Netlink Family
   4  *
   5  *              Authors:        Jamal Hadi Salim
   6  *                              Thomas Graf <tgraf@suug.ch>
   7  *                              Johannes Berg <johannes@sipsolutions.net>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/errno.h>
  14 #include <linux/types.h>
  15 #include <linux/socket.h>
  16 #include <linux/string.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/mutex.h>
  19 #include <linux/bitmap.h>
  20 #include <linux/rwsem.h>
  21 #include <linux/idr.h>
  22 #include <net/sock.h>
  23 #include <net/genetlink.h>
  24
  25 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
  26 static DECLARE_RWSEM(cb_lock);
  27
  28 atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
  29 DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
  30
  31 void genl_lock(void)
  32 {
  33         mutex_lock(&genl_mutex);
  34 }
  35 EXPORT_SYMBOL(genl_lock);
  36
  37 void genl_unlock(void)
  38 {
  39         mutex_unlock(&genl_mutex);
  40 }
  41 EXPORT_SYMBOL(genl_unlock);
  42
  43 #ifdef CONFIG_LOCKDEP
  44 bool lockdep_genl_is_held(void)
  45 {
  46         return lockdep_is_held(&genl_mutex);
  47 }
  48 EXPORT_SYMBOL(lockdep_genl_is_held);
  49 #endif
  50
  51 static void genl_lock_all(void)
  52 {
  53         down_write(&cb_lock);
  54         genl_lock();
  55 }
  56
  57 static void genl_unlock_all(void)
  58 {
  59         genl_unlock();
  60         up_write(&cb_lock);
  61 }
  62
  63 static DEFINE_IDR(genl_fam_idr);
  64
  65 /*
  66  * Bitmap of multicast groups that are currently in use.
  67  *
  68  * To avoid an allocation at boot of just one unsigned long,
  69  * declare it global instead.
  70  * Bit 0 is marked as already used since group 0 is invalid.
  71  * Bit 1 is marked as already used since the drop-monitor code
  72  * abuses the API and thinks it can statically use group 1.
  73  * That group will typically conflict with other groups that
  74  * any proper users use.
  75  * Bit 16 is marked as used since it's used for generic netlink
  76  * and the code no longer marks pre-reserved IDs as used.
  77  * Bit 17 is marked as already used since the VFS quota code
  78  * also abused this API and relied on family == group ID, we
  79  * cater to that by giving it a static family and group ID.
  80  * Bit 18 is marked as already used since the PMCRAID driver
  81  * did the same thing as the VFS quota code (maybe copied?)
  82  */
  83 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
  84                                       BIT(GENL_ID_VFS_DQUOT) |
  85                                       BIT(GENL_ID_PMCRAID);
  86 static unsigned long *mc_groups = &mc_group_start;
  87 static unsigned long mc_groups_longs = 1;
  88
  89 static int genl_ctrl_event(int event, const struct genl_family *family,
  90                            const struct genl_multicast_group *grp,
  91                            int grp_id);
  92
  93 static const struct genl_family *genl_family_find_byid(unsigned int id)
  94 {
  95         return idr_find(&genl_fam_idr, id);
  96 }
  97
  98 static const struct genl_family *genl_family_find_byname(char *name)
  99 {
 100         const struct genl_family *family;
 101         unsigned int id;
 102
 103         idr_for_each_entry(&genl_fam_idr, family, id)
 104                 if (strcmp(family->name, name) == 0)
 105                         return family;
 106
 107         return NULL;
 108 }
 109
 110 static const struct genl_ops *genl_get_cmd(u8 cmd,
 111                                            const struct genl_family *family)
 112 {
 113         int i;
 114
 115         for (i = 0; i < family->n_ops; i++)
 116                 if (family->ops[i].cmd == cmd)
 117                         return &family->ops[i];
 118
 119         return NULL;
 120 }
 121
 122 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
 123 {
 124         unsigned long *new_groups;
 125         int start = 0;
 126         int i;
 127         int id;
 128         bool fits;
 129
 130         do {
 131                 if (start == 0)
 132                         id = find_first_zero_bit(mc_groups,
 133                                                  mc_groups_longs *
 134                                                  BITS_PER_LONG);
 135                 else
 136                         id = find_next_zero_bit(mc_groups,
 137                                                 mc_groups_longs * BITS_PER_LONG,
 138                                                 start);
 139
 140                 fits = true;
 141                 for (i = id;
 142                      i < min_t(int, id + n_groups,
 143                                mc_groups_longs * BITS_PER_LONG);
 144                      i++) {
 145                         if (test_bit(i, mc_groups)) {
 146                                 start = i;
 147                                 fits = false;
 148                                 break;
 149                         }
 150                 }
 151
 152                 if (id + n_groups > mc_groups_longs * BITS_PER_LONG) {
 153                         unsigned long new_longs = mc_groups_longs +
 154                                                   BITS_TO_LONGS(n_groups);
 155                         size_t nlen = new_longs * sizeof(unsigned long);
 156
 157                         if (mc_groups == &mc_group_start) {
 158                                 new_groups = kzalloc(nlen, GFP_KERNEL);
 159                                 if (!new_groups)
 160                                         return -ENOMEM;
 161                                 mc_groups = new_groups;
 162                                 *mc_groups = mc_group_start;
 163                         } else {
 164                                 new_groups = krealloc(mc_groups, nlen,
 165                                                       GFP_KERNEL);
 166                                 if (!new_groups)
 167                                         return -ENOMEM;
 168                                 mc_groups = new_groups;
 169                                 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
 170                                         mc_groups[mc_groups_longs + i] = 0;
 171                         }
 172                         mc_groups_longs = new_longs;
 173                 }
 174         } while (!fits);
 175
 176         for (i = id; i < id + n_groups; i++)
 177                 set_bit(i, mc_groups);
 178         *first_id = id;
 179         return 0;
 180 }
 181
 182 static struct genl_family genl_ctrl;
 183
 184 static int genl_validate_assign_mc_groups(struct genl_family *family)
 185 {
 186         int first_id;
 187         int n_groups = family->n_mcgrps;
 188         int err = 0, i;
 189         bool groups_allocated = false;
 190
 191         if (!n_groups)
 192                 return 0;
 193
 194         for (i = 0; i < n_groups; i++) {
 195                 const struct genl_multicast_group *grp = &family->mcgrps[i];
 196
 197                 if (WARN_ON(grp->name[0] == '\0'))
 198                         return -EINVAL;
 199                 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
 200                         return -EINVAL;
 201         }
 202
 203         /* special-case our own group and hacks */
 204         if (family == &genl_ctrl) {
 205                 first_id = GENL_ID_CTRL;
 206                 BUG_ON(n_groups != 1);
 207         } else if (strcmp(family->name, "NET_DM") == 0) {
 208                 first_id = 1;
 209                 BUG_ON(n_groups != 1);
 210         } else if (family->id == GENL_ID_VFS_DQUOT) {
 211                 first_id = GENL_ID_VFS_DQUOT;
 212                 BUG_ON(n_groups != 1);
 213         } else if (family->id == GENL_ID_PMCRAID) {
 214                 first_id = GENL_ID_PMCRAID;
 215                 BUG_ON(n_groups != 1);
 216         } else {
 217                 groups_allocated = true;
 218                 err = genl_allocate_reserve_groups(n_groups, &first_id);
 219                 if (err)
 220                         return err;
 221         }
 222
 223         family->mcgrp_offset = first_id;
 224
 225         /* if still initializing, can't and don't need to to realloc bitmaps */
 226         if (!init_net.genl_sock)
 227                 return 0;
 228
 229         if (family->netnsok) {
 230                 struct net *net;
 231
 232                 netlink_table_grab();
 233                 rcu_read_lock();
 234                 for_each_net_rcu(net) {
 235                         err = __netlink_change_ngroups(net->genl_sock,
 236                                         mc_groups_longs * BITS_PER_LONG);
 237                         if (err) {
 238                                 /*
 239                                  * No need to roll back, can only fail if
 240                                  * memory allocation fails and then the
 241                                  * number of _possible_ groups has been
 242                                  * increased on some sockets which is ok.
 243                                  */
 244                                 break;
 245                         }
 246                 }
 247                 rcu_read_unlock();
 248                 netlink_table_ungrab();
 249         } else {
 250                 err = netlink_change_ngroups(init_net.genl_sock,
 251                                              mc_groups_longs * BITS_PER_LONG);
 252         }
 253
 254         if (groups_allocated && err) {
 255                 for (i = 0; i < family->n_mcgrps; i++)
 256                         clear_bit(family->mcgrp_offset + i, mc_groups);
 257         }
 258
 259         return err;
 260 }
 261
 262 static void genl_unregister_mc_groups(const struct genl_family *family)
 263 {
 264         struct net *net;
 265         int i;
 266
 267         netlink_table_grab();
 268         rcu_read_lock();
 269         for_each_net_rcu(net) {
 270                 for (i = 0; i < family->n_mcgrps; i++)
 271                         __netlink_clear_multicast_users(
 272                                 net->genl_sock, family->mcgrp_offset + i);
 273         }
 274         rcu_read_unlock();
 275         netlink_table_ungrab();
 276
 277         for (i = 0; i < family->n_mcgrps; i++) {
 278                 int grp_id = family->mcgrp_offset + i;
 279
 280                 if (grp_id != 1)
 281                         clear_bit(grp_id, mc_groups);
 282                 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
 283                                 &family->mcgrps[i], grp_id);
 284         }
 285 }
 286
 287 static int genl_validate_ops(const struct genl_family *family)
 288 {
 289         const struct genl_ops *ops = family->ops;
 290         unsigned int n_ops = family->n_ops;
 291         int i, j;
 292
 293         if (WARN_ON(n_ops && !ops))
 294                 return -EINVAL;
 295
 296         if (!n_ops)
 297                 return 0;
 298
 299         for (i = 0; i < n_ops; i++) {
 300                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 301                         return -EINVAL;
 302                 for (j = i + 1; j < n_ops; j++)
 303                         if (ops[i].cmd == ops[j].cmd)
 304                                 return -EINVAL;
 305         }
 306
 307         return 0;
 308 }
 309
 310 /**
 311  * genl_register_family - register a generic netlink family
 312  * @family: generic netlink family
 313  *
 314  * Registers the specified family after validating it first. Only one
 315  * family may be registered with the same family name or identifier.
 316  *
 317  * The family's ops, multicast groups and module pointer must already
 318  * be assigned.
 319  *
 320  * Return 0 on success or a negative error code.
 321  */
 322 int genl_register_family(struct genl_family *family)
 323 {
 324         int err, i;
 325         int start = GENL_START_ALLOC, end = GENL_MAX_ID;
 326
 327         err = genl_validate_ops(family);
 328         if (err)
 329                 return err;
 330
 331         genl_lock_all();
 332
 333         if (genl_family_find_byname(family->name)) {
 334                 err = -EEXIST;
 335                 goto errout_locked;
 336         }
 337
 338         /*
 339          * Sadly, a few cases need to be special-cased
 340          * due to them having previously abused the API
 341          * and having used their family ID also as their
 342          * multicast group ID, so we use reserved IDs
 343          * for both to be sure we can do that mapping.
 344          */
 345         if (family == &genl_ctrl) {
 346                 /* and this needs to be special for initial family lookups */
 347                 start = end = GENL_ID_CTRL;
 348         } else if (strcmp(family->name, "pmcraid") == 0) {
 349                 start = end = GENL_ID_PMCRAID;
 350         } else if (strcmp(family->name, "VFS_DQUOT") == 0) {
 351                 start = end = GENL_ID_VFS_DQUOT;
 352         }
 353
 354         if (family->maxattr && !family->parallel_ops) {
 355                 family->attrbuf = kmalloc((family->maxattr+1) *
 356                                         sizeof(struct nlattr *), GFP_KERNEL);
 357                 if (family->attrbuf == NULL) {
 358                         err = -ENOMEM;
 359                         goto errout_locked;
 360                 }
 361         } else
 362                 family->attrbuf = NULL;
 363
 364         family->id = idr_alloc(&genl_fam_idr, family,
 365                                start, end + 1, GFP_KERNEL);
 366         if (family->id < 0) {
 367                 err = family->id;
 368                 goto errout_free;
 369         }
 370
 371         err = genl_validate_assign_mc_groups(family);
 372         if (err)
 373                 goto errout_remove;
 374
 375         genl_unlock_all();
 376
 377         /* send all events */
 378         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 379         for (i = 0; i < family->n_mcgrps; i++)
 380                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 381                                 &family->mcgrps[i], family->mcgrp_offset + i);
 382
 383         return 0;
 384
 385 errout_remove:
 386         idr_remove(&genl_fam_idr, family->id);
 387 errout_free:
 388         kfree(family->attrbuf);
 389 errout_locked:
 390         genl_unlock_all();
 391         return err;
 392 }
 393 EXPORT_SYMBOL(genl_register_family);
 394
 395 /**
 396  * genl_unregister_family - unregister generic netlink family
 397  * @family: generic netlink family
 398  *
 399  * Unregisters the specified family.
 400  *
 401  * Returns 0 on success or a negative error code.
 402  */
 403 int genl_unregister_family(const struct genl_family *family)
 404 {
 405         genl_lock_all();
 406
 407         if (!genl_family_find_byid(family->id)) {
 408                 genl_unlock_all();
 409                 return -ENOENT;
 410         }
 411
 412         genl_unregister_mc_groups(family);
 413
 414         idr_remove(&genl_fam_idr, family->id);
 415
 416         up_write(&cb_lock);
 417         wait_event(genl_sk_destructing_waitq,
 418                    atomic_read(&genl_sk_destructing_cnt) == 0);
 419         genl_unlock();
 420
 421         kfree(family->attrbuf);
 422
 423         genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 424
 425         return 0;
 426 }
 427 EXPORT_SYMBOL(genl_unregister_family);
 428
 429 /**
 430  * genlmsg_put - Add generic netlink header to netlink message
 431  * @skb: socket buffer holding the message
 432  * @portid: netlink portid the message is addressed to
 433  * @seq: sequence number (usually the one of the sender)
 434  * @family: generic netlink family
 435  * @flags: netlink message flags
 436  * @cmd: generic netlink command
 437  *
 438  * Returns pointer to user specific header
 439  */
 440 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 441                   const struct genl_family *family, int flags, u8 cmd)
 442 {
 443         struct nlmsghdr *nlh;
 444         struct genlmsghdr *hdr;
 445
 446         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 447                         family->hdrsize, flags);
 448         if (nlh == NULL)
 449                 return NULL;
 450
 451         hdr = nlmsg_data(nlh);
 452         hdr->cmd = cmd;
 453         hdr->version = family->version;
 454         hdr->reserved = 0;
 455
 456         return (char *) hdr + GENL_HDRLEN;
 457 }
 458 EXPORT_SYMBOL(genlmsg_put);
 459
 460 static int genl_lock_start(struct netlink_callback *cb)
 461 {
 462         /* our ops are always const - netlink API doesn't propagate that */
 463         const struct genl_ops *ops = cb->data;
 464         int rc = 0;
 465
 466         if (ops->start) {
 467                 genl_lock();
 468                 rc = ops->start(cb);
 469                 genl_unlock();
 470         }
 471         return rc;
 472 }
 473
 474 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 475 {
 476         /* our ops are always const - netlink API doesn't propagate that */
 477         const struct genl_ops *ops = cb->data;
 478         int rc;
 479
 480         genl_lock();
 481         rc = ops->dumpit(skb, cb);
 482         genl_unlock();
 483         return rc;
 484 }
 485
 486 static int genl_lock_done(struct netlink_callback *cb)
 487 {
 488         /* our ops are always const - netlink API doesn't propagate that */
 489         const struct genl_ops *ops = cb->data;
 490         int rc = 0;
 491
 492         if (ops->done) {
 493                 genl_lock();
 494                 rc = ops->done(cb);
 495                 genl_unlock();
 496         }
 497         return rc;
 498 }
 499
 500 static int genl_family_rcv_msg(const struct genl_family *family,
 501                                struct sk_buff *skb,
 502                                struct nlmsghdr *nlh,
 503                                struct netlink_ext_ack *extack)
 504 {
 505         const struct genl_ops *ops;
 506         struct net *net = sock_net(skb->sk);
 507         struct genl_info info;
 508         struct genlmsghdr *hdr = nlmsg_data(nlh);
 509         struct nlattr **attrbuf;
 510         int hdrlen, err;
 511
 512         /* this family doesn't exist in this netns */
 513         if (!family->netnsok && !net_eq(net, &init_net))
 514                 return -ENOENT;
 515
 516         hdrlen = GENL_HDRLEN + family->hdrsize;
 517         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 518                 return -EINVAL;
 519
 520         ops = genl_get_cmd(hdr->cmd, family);
 521         if (ops == NULL)
 522                 return -EOPNOTSUPP;
 523
 524         if ((ops->flags & GENL_ADMIN_PERM) &&
 525             !netlink_capable(skb, CAP_NET_ADMIN))
 526                 return -EPERM;
 527
 528         if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
 529             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 530                 return -EPERM;
 531
 532         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 533                 int rc;
 534
 535                 if (ops->dumpit == NULL)
 536                         return -EOPNOTSUPP;
 537
 538                 if (!family->parallel_ops) {
 539                         struct netlink_dump_control c = {
 540                                 .module = family->module,
 541                                 /* we have const, but the netlink API doesn't */
 542                                 .data = (void *)ops,
 543                                 .start = genl_lock_start,
 544                                 .dump = genl_lock_dumpit,
 545                                 .done = genl_lock_done,
 546                         };
 547
 548                         genl_unlock();
 549                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 550                         genl_lock();
 551
 552                 } else {
 553                         struct netlink_dump_control c = {
 554                                 .module = family->module,
 555                                 .start = ops->start,
 556                                 .dump = ops->dumpit,
 557                                 .done = ops->done,
 558                         };
 559
 560                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 561                 }
 562
 563                 return rc;
 564         }
 565
 566         if (ops->doit == NULL)
 567                 return -EOPNOTSUPP;
 568
 569         if (family->maxattr && family->parallel_ops) {
 570                 attrbuf = kmalloc((family->maxattr+1) *
 571                                         sizeof(struct nlattr *), GFP_KERNEL);
 572                 if (attrbuf == NULL)
 573                         return -ENOMEM;
 574         } else
 575                 attrbuf = family->attrbuf;
 576
 577         if (attrbuf) {
 578                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 579                                   ops->policy, extack);
 580                 if (err < 0)
 581                         goto out;
 582         }
 583
 584         info.snd_seq = nlh->nlmsg_seq;
 585         info.snd_portid = NETLINK_CB(skb).portid;
 586         info.nlhdr = nlh;
 587         info.genlhdr = nlmsg_data(nlh);
 588         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 589         info.attrs = attrbuf;
 590         info.extack = extack;
 591         genl_info_net_set(&info, net);
 592         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 593
 594         if (family->pre_doit) {
 595                 err = family->pre_doit(ops, skb, &info);
 596                 if (err)
 597                         goto out;
 598         }
 599
 600         err = ops->doit(skb, &info);
 601
 602         if (family->post_doit)
 603                 family->post_doit(ops, skb, &info);
 604
 605 out:
 606         if (family->parallel_ops)
 607                 kfree(attrbuf);
 608
 609         return err;
 610 }
 611
 612 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 613                         struct netlink_ext_ack *extack)
 614 {
 615         const struct genl_family *family;
 616         int err;
 617
 618         family = genl_family_find_byid(nlh->nlmsg_type);
 619         if (family == NULL)
 620                 return -ENOENT;
 621
 622         if (!family->parallel_ops)
 623                 genl_lock();
 624
 625         err = genl_family_rcv_msg(family, skb, nlh, extack);
 626
 627         if (!family->parallel_ops)
 628                 genl_unlock();
 629
 630         return err;
 631 }
 632
 633 static void genl_rcv(struct sk_buff *skb)
 634 {
 635         down_read(&cb_lock);
 636         netlink_rcv_skb(skb, &genl_rcv_msg);
 637         up_read(&cb_lock);
 638 }
 639
 640 /**************************************************************************
 641  * Controller
 642  **************************************************************************/
 643
 644 static struct genl_family genl_ctrl;
 645
 646 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 647                           u32 flags, struct sk_buff *skb, u8 cmd)
 648 {
 649         void *hdr;
 650
 651         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 652         if (hdr == NULL)
 653                 return -1;
 654
 655         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 656             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 657             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 658             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 659             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 660                 goto nla_put_failure;
 661
 662         if (family->n_ops) {
 663                 struct nlattr *nla_ops;
 664                 int i;
 665
 666                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 667                 if (nla_ops == NULL)
 668                         goto nla_put_failure;
 669
 670                 for (i = 0; i < family->n_ops; i++) {
 671                         struct nlattr *nest;
 672                         const struct genl_ops *ops = &family->ops[i];
 673                         u32 op_flags = ops->flags;
 674
 675                         if (ops->dumpit)
 676                                 op_flags |= GENL_CMD_CAP_DUMP;
 677                         if (ops->doit)
 678                                 op_flags |= GENL_CMD_CAP_DO;
 679                         if (ops->policy)
 680                                 op_flags |= GENL_CMD_CAP_HASPOL;
 681
 682                         nest = nla_nest_start(skb, i + 1);
 683                         if (nest == NULL)
 684                                 goto nla_put_failure;
 685
 686                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 687                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 688                                 goto nla_put_failure;
 689
 690                         nla_nest_end(skb, nest);
 691                 }
 692
 693                 nla_nest_end(skb, nla_ops);
 694         }
 695
 696         if (family->n_mcgrps) {
 697                 struct nlattr *nla_grps;
 698                 int i;
 699
 700                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 701                 if (nla_grps == NULL)
 702                         goto nla_put_failure;
 703
 704                 for (i = 0; i < family->n_mcgrps; i++) {
 705                         struct nlattr *nest;
 706                         const struct genl_multicast_group *grp;
 707
 708                         grp = &family->mcgrps[i];
 709
 710                         nest = nla_nest_start(skb, i + 1);
 711                         if (nest == NULL)
 712                                 goto nla_put_failure;
 713
 714                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 715                                         family->mcgrp_offset + i) ||
 716                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 717                                            grp->name))
 718                                 goto nla_put_failure;
 719
 720                         nla_nest_end(skb, nest);
 721                 }
 722                 nla_nest_end(skb, nla_grps);
 723         }
 724
 725         genlmsg_end(skb, hdr);
 726         return 0;
 727
 728 nla_put_failure:
 729         genlmsg_cancel(skb, hdr);
 730         return -EMSGSIZE;
 731 }
 732
 733 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
 734                                 const struct genl_multicast_group *grp,
 735                                 int grp_id, u32 portid, u32 seq, u32 flags,
 736                                 struct sk_buff *skb, u8 cmd)
 737 {
 738         void *hdr;
 739         struct nlattr *nla_grps;
 740         struct nlattr *nest;
 741
 742         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 743         if (hdr == NULL)
 744                 return -1;
 745
 746         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 747             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 748                 goto nla_put_failure;
 749
 750         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 751         if (nla_grps == NULL)
 752                 goto nla_put_failure;
 753
 754         nest = nla_nest_start(skb, 1);
 755         if (nest == NULL)
 756                 goto nla_put_failure;
 757
 758         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 759             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 760                            grp->name))
 761                 goto nla_put_failure;
 762
 763         nla_nest_end(skb, nest);
 764         nla_nest_end(skb, nla_grps);
 765
 766         genlmsg_end(skb, hdr);
 767         return 0;
 768
 769 nla_put_failure:
 770         genlmsg_cancel(skb, hdr);
 771         return -EMSGSIZE;
 772 }
 773
 774 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 775 {
 776         int n = 0;
 777         struct genl_family *rt;
 778         struct net *net = sock_net(skb->sk);
 779         int fams_to_skip = cb->args[0];
 780         unsigned int id;
 781
 782         idr_for_each_entry(&genl_fam_idr, rt, id) {
 783                 if (!rt->netnsok && !net_eq(net, &init_net))
 784                         continue;
 785
 786                 if (n++ < fams_to_skip)
 787                         continue;
 788
 789                 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 790                                    cb->nlh->nlmsg_seq, NLM_F_MULTI,
 791                                    skb, CTRL_CMD_NEWFAMILY) < 0) {
 792                         n--;
 793                         break;
 794                 }
 795         }
 796
 797         cb->args[0] = n;
 798         return skb->len;
 799 }
 800
 801 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
 802                                              u32 portid, int seq, u8 cmd)
 803 {
 804         struct sk_buff *skb;
 805         int err;
 806
 807         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 808         if (skb == NULL)
 809                 return ERR_PTR(-ENOBUFS);
 810
 811         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 812         if (err < 0) {
 813                 nlmsg_free(skb);
 814                 return ERR_PTR(err);
 815         }
 816
 817         return skb;
 818 }
 819
 820 static struct sk_buff *
 821 ctrl_build_mcgrp_msg(const struct genl_family *family,
 822                      const struct genl_multicast_group *grp,
 823                      int grp_id, u32 portid, int seq, u8 cmd)
 824 {
 825         struct sk_buff *skb;
 826         int err;
 827
 828         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 829         if (skb == NULL)
 830                 return ERR_PTR(-ENOBUFS);
 831
 832         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 833                                    seq, 0, skb, cmd);
 834         if (err < 0) {
 835                 nlmsg_free(skb);
 836                 return ERR_PTR(err);
 837         }
 838
 839         return skb;
 840 }
 841
 842 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 843         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 844         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 845                                     .len = GENL_NAMSIZ - 1 },
 846 };
 847
 848 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 849 {
 850         struct sk_buff *msg;
 851         const struct genl_family *res = NULL;
 852         int err = -EINVAL;
 853
 854         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 855                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 856                 res = genl_family_find_byid(id);
 857                 err = -ENOENT;
 858         }
 859
 860         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 861                 char *name;
 862
 863                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 864                 res = genl_family_find_byname(name);
 865 #ifdef CONFIG_MODULES
 866                 if (res == NULL) {
 867                         genl_unlock();
 868                         up_read(&cb_lock);
 869                         request_module("net-pf-%d-proto-%d-family-%s",
 870                                        PF_NETLINK, NETLINK_GENERIC, name);
 871                         down_read(&cb_lock);
 872                         genl_lock();
 873                         res = genl_family_find_byname(name);
 874                 }
 875 #endif
 876                 err = -ENOENT;
 877         }
 878
 879         if (res == NULL)
 880                 return err;
 881
 882         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 883                 /* family doesn't exist here */
 884                 return -ENOENT;
 885         }
 886
 887         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 888                                     CTRL_CMD_NEWFAMILY);
 889         if (IS_ERR(msg))
 890                 return PTR_ERR(msg);
 891
 892         return genlmsg_reply(msg, info);
 893 }
 894
 895 static int genl_ctrl_event(int event, const struct genl_family *family,
 896                            const struct genl_multicast_group *grp,
 897                            int grp_id)
 898 {
 899         struct sk_buff *msg;
 900
 901         /* genl is still initialising */
 902         if (!init_net.genl_sock)
 903                 return 0;
 904
 905         switch (event) {
 906         case CTRL_CMD_NEWFAMILY:
 907         case CTRL_CMD_DELFAMILY:
 908                 WARN_ON(grp);
 909                 msg = ctrl_build_family_msg(family, 0, 0, event);
 910                 break;
 911         case CTRL_CMD_NEWMCAST_GRP:
 912         case CTRL_CMD_DELMCAST_GRP:
 913                 BUG_ON(!grp);
 914                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 915                 break;
 916         default:
 917                 return -EINVAL;
 918         }
 919
 920         if (IS_ERR(msg))
 921                 return PTR_ERR(msg);
 922
 923         if (!family->netnsok) {
 924                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 925                                         0, GFP_KERNEL);
 926         } else {
 927                 rcu_read_lock();
 928                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 929                                         0, GFP_ATOMIC);
 930                 rcu_read_unlock();
 931         }
 932
 933         return 0;
 934 }
 935
 936 static const struct genl_ops genl_ctrl_ops[] = {
 937         {
 938                 .cmd            = CTRL_CMD_GETFAMILY,
 939                 .doit           = ctrl_getfamily,
 940                 .dumpit         = ctrl_dumpfamily,
 941                 .policy         = ctrl_policy,
 942         },
 943 };
 944
 945 static const struct genl_multicast_group genl_ctrl_groups[] = {
 946         { .name = "notify", },
 947 };
 948
 949 static struct genl_family genl_ctrl __ro_after_init = {
 950         .module = THIS_MODULE,
 951         .ops = genl_ctrl_ops,
 952         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
 953         .mcgrps = genl_ctrl_groups,
 954         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
 955         .id = GENL_ID_CTRL,
 956         .name = "nlctrl",
 957         .version = 0x2,
 958         .maxattr = CTRL_ATTR_MAX,
 959         .netnsok = true,
 960 };
 961
 962 static int __net_init genl_pernet_init(struct net *net)
 963 {
 964         struct netlink_kernel_cfg cfg = {
 965                 .input          = genl_rcv,
 966                 .flags          = NL_CFG_F_NONROOT_RECV,
 967         };
 968
 969         /* we'll bump the group number right afterwards */
 970         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
 971
 972         if (!net->genl_sock && net_eq(net, &init_net))
 973                 panic("GENL: Cannot initialize generic netlink\n");
 974
 975         if (!net->genl_sock)
 976                 return -ENOMEM;
 977
 978         return 0;
 979 }
 980
 981 static void __net_exit genl_pernet_exit(struct net *net)
 982 {
 983         netlink_kernel_release(net->genl_sock);
 984         net->genl_sock = NULL;
 985 }
 986
 987 static struct pernet_operations genl_pernet_ops = {
 988         .init = genl_pernet_init,
 989         .exit = genl_pernet_exit,
 990 };
 991
 992 static int __init genl_init(void)
 993 {
 994         int err;
 995
 996         err = genl_register_family(&genl_ctrl);
 997         if (err < 0)
 998                 goto problem;
 999
1000         err = register_pernet_subsys(&genl_pernet_ops);
1001         if (err)
1002                 goto problem;
1003
1004         return 0;
1005
1006 problem:
1007         panic("GENL: Cannot register controller: %d\n", err);
1008 }
1009
1010 subsys_initcall(genl_init);
1011
1012 /**
1013  * genl_family_attrbuf - return family's attrbuf
1014  * @family: the family
1015  *
1016  * Return the family's attrbuf, while validating that it's
1017  * actually valid to access it.
1018  *
1019  * You cannot use this function with a family that has parallel_ops
1020  * and you can only use it within (pre/post) doit/dumpit callbacks.
1021  */
1022 struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1023 {
1024         if (!WARN_ON(family->parallel_ops))
1025                 lockdep_assert_held(&genl_mutex);
1026
1027         return family->attrbuf;
1028 }
1029 EXPORT_SYMBOL(genl_family_attrbuf);
1030
1031 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1032                          gfp_t flags)
1033 {
1034         struct sk_buff *tmp;
1035         struct net *net, *prev = NULL;
1036         bool delivered = false;
1037         int err;
1038
1039         for_each_net_rcu(net) {
1040                 if (prev) {
1041                         tmp = skb_clone(skb, flags);
1042                         if (!tmp) {
1043                                 err = -ENOMEM;
1044                                 goto error;
1045                         }
1046                         err = nlmsg_multicast(prev->genl_sock, tmp,
1047                                               portid, group, flags);
1048                         if (!err)
1049                                 delivered = true;
1050                         else if (err != -ESRCH)
1051                                 goto error;
1052                 }
1053
1054                 prev = net;
1055         }
1056
1057         err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1058         if (!err)
1059                 delivered = true;
1060         else if (err != -ESRCH)
1061                 return err;
1062         return delivered ? 0 : -ESRCH;
1063  error:
1064         kfree_skb(skb);
1065         return err;
1066 }
1067
1068 int genlmsg_multicast_allns(const struct genl_family *family,
1069                             struct sk_buff *skb, u32 portid,
1070                             unsigned int group, gfp_t flags)
1071 {
1072         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1073                 return -EINVAL;
1074         group = family->mcgrp_offset + group;
1075         return genlmsg_mcast(skb, portid, group, flags);
1076 }
1077 EXPORT_SYMBOL(genlmsg_multicast_allns);
1078
1079 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1080                  struct genl_info *info, u32 group, gfp_t flags)
1081 {
1082         struct net *net = genl_info_net(info);
1083         struct sock *sk = net->genl_sock;
1084         int report = 0;
1085
1086         if (info->nlhdr)
1087                 report = nlmsg_report(info->nlhdr);
1088
1089         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1090                 return;
1091         group = family->mcgrp_offset + group;
1092         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1093 }
1094 EXPORT_SYMBOL(genl_notify);