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