net/netlink/genetlink.c

   1 /*
   2  * NETLINK      Generic Netlink Family
   3  *
   4  *              Authors:        Jamal Hadi Salim
   5  *                              Thomas Graf <tgraf@suug.ch>
   6  *                              Johannes Berg <johannes@sipsolutions.net>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/errno.h>
  13 #include <linux/types.h>
  14 #include <linux/socket.h>
  15 #include <linux/string.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/mutex.h>
  18 #include <linux/bitmap.h>
  19 #include <linux/rwsem.h>
  20 #include <linux/idr.h>
  21 #include <net/sock.h>
  22 #include <net/genetlink.h>
  23
  24 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
  25 static DECLARE_RWSEM(cb_lock);
  26
  27 atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
  28 DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
  29
  30 void genl_lock(void)
  31 {
  32         mutex_lock(&genl_mutex);
  33 }
  34 EXPORT_SYMBOL(genl_lock);
  35
  36 void genl_unlock(void)
  37 {
  38         mutex_unlock(&genl_mutex);
  39 }
  40 EXPORT_SYMBOL(genl_unlock);
  41
  42 #ifdef CONFIG_LOCKDEP
  43 bool lockdep_genl_is_held(void)
  44 {
  45         return lockdep_is_held(&genl_mutex);
  46 }
  47 EXPORT_SYMBOL(lockdep_genl_is_held);
  48 #endif
  49
  50 static void genl_lock_all(void)
  51 {
  52         down_write(&cb_lock);
  53         genl_lock();
  54 }
  55
  56 static void genl_unlock_all(void)
  57 {
  58         genl_unlock();
  59         up_write(&cb_lock);
  60 }
  61
  62 static DEFINE_IDR(genl_fam_idr);
  63
  64 /*
  65  * Bitmap of multicast groups that are currently in use.
  66  *
  67  * To avoid an allocation at boot of just one unsigned long,
  68  * declare it global instead.
  69  * Bit 0 is marked as already used since group 0 is invalid.
  70  * Bit 1 is marked as already used since the drop-monitor code
  71  * abuses the API and thinks it can statically use group 1.
  72  * That group will typically conflict with other groups that
  73  * any proper users use.
  74  * Bit 16 is marked as used since it's used for generic netlink
  75  * and the code no longer marks pre-reserved IDs as used.
  76  * Bit 17 is marked as already used since the VFS quota code
  77  * also abused this API and relied on family == group ID, we
  78  * cater to that by giving it a static family and group ID.
  79  * Bit 18 is marked as already used since the PMCRAID driver
  80  * did the same thing as the VFS quota code (maybe copied?)
  81  */
  82 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
  83                                       BIT(GENL_ID_VFS_DQUOT) |
  84                                       BIT(GENL_ID_PMCRAID);
  85 static unsigned long *mc_groups = &mc_group_start;
  86 static unsigned long mc_groups_longs = 1;
  87
  88 static int genl_ctrl_event(int event, const struct genl_family *family,
  89                            const struct genl_multicast_group *grp,
  90                            int grp_id);
  91
  92 static const struct genl_family *genl_family_find_byid(unsigned int id)
  93 {
  94         return idr_find(&genl_fam_idr, id);
  95 }
  96
  97 static const struct genl_family *genl_family_find_byname(char *name)
  98 {
  99         const struct genl_family *family;
 100         unsigned int id;
 101
 102         idr_for_each_entry(&genl_fam_idr, family, id)
 103                 if (strcmp(family->name, name) == 0)
 104                         return family;
 105
 106         return NULL;
 107 }
 108
 109 static const struct genl_ops *genl_get_cmd(u8 cmd,
 110                                            const struct genl_family *family)
 111 {
 112         int i;
 113
 114         for (i = 0; i < family->n_ops; i++)
 115                 if (family->ops[i].cmd == cmd)
 116                         return &family->ops[i];
 117
 118         return NULL;
 119 }
 120
 121 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
 122 {
 123         unsigned long *new_groups;
 124         int start = 0;
 125         int i;
 126         int id;
 127         bool fits;
 128
 129         do {
 130                 if (start == 0)
 131                         id = find_first_zero_bit(mc_groups,
 132                                                  mc_groups_longs *
 133                                                  BITS_PER_LONG);
 134                 else
 135                         id = find_next_zero_bit(mc_groups,
 136                                                 mc_groups_longs * BITS_PER_LONG,
 137                                                 start);
 138
 139                 fits = true;
 140                 for (i = id;
 141                      i < min_t(int, id + n_groups,
 142                                mc_groups_longs * BITS_PER_LONG);
 143                      i++) {
 144                         if (test_bit(i, mc_groups)) {
 145                                 start = i;
 146                                 fits = false;
 147                                 break;
 148                         }
 149                 }
 150
 151                 if (id + n_groups > mc_groups_longs * BITS_PER_LONG) {
 152                         unsigned long new_longs = mc_groups_longs +
 153                                                   BITS_TO_LONGS(n_groups);
 154                         size_t nlen = new_longs * sizeof(unsigned long);
 155
 156                         if (mc_groups == &mc_group_start) {
 157                                 new_groups = kzalloc(nlen, GFP_KERNEL);
 158                                 if (!new_groups)
 159                                         return -ENOMEM;
 160                                 mc_groups = new_groups;
 161                                 *mc_groups = mc_group_start;
 162                         } else {
 163                                 new_groups = krealloc(mc_groups, nlen,
 164                                                       GFP_KERNEL);
 165                                 if (!new_groups)
 166                                         return -ENOMEM;
 167                                 mc_groups = new_groups;
 168                                 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
 169                                         mc_groups[mc_groups_longs + i] = 0;
 170                         }
 171                         mc_groups_longs = new_longs;
 172                 }
 173         } while (!fits);
 174
 175         for (i = id; i < id + n_groups; i++)
 176                 set_bit(i, mc_groups);
 177         *first_id = id;
 178         return 0;
 179 }
 180
 181 static struct genl_family genl_ctrl;
 182
 183 static int genl_validate_assign_mc_groups(struct genl_family *family)
 184 {
 185         int first_id;
 186         int n_groups = family->n_mcgrps;
 187         int err = 0, i;
 188         bool groups_allocated = false;
 189
 190         if (!n_groups)
 191                 return 0;
 192
 193         for (i = 0; i < n_groups; i++) {
 194                 const struct genl_multicast_group *grp = &family->mcgrps[i];
 195
 196                 if (WARN_ON(grp->name[0] == '\0'))
 197                         return -EINVAL;
 198                 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
 199                         return -EINVAL;
 200         }
 201
 202         /* special-case our own group and hacks */
 203         if (family == &genl_ctrl) {
 204                 first_id = GENL_ID_CTRL;
 205                 BUG_ON(n_groups != 1);
 206         } else if (strcmp(family->name, "NET_DM") == 0) {
 207                 first_id = 1;
 208                 BUG_ON(n_groups != 1);
 209         } else if (family->id == GENL_ID_VFS_DQUOT) {
 210                 first_id = GENL_ID_VFS_DQUOT;
 211                 BUG_ON(n_groups != 1);
 212         } else if (family->id == GENL_ID_PMCRAID) {
 213                 first_id = GENL_ID_PMCRAID;
 214                 BUG_ON(n_groups != 1);
 215         } else {
 216                 groups_allocated = true;
 217                 err = genl_allocate_reserve_groups(n_groups, &first_id);
 218                 if (err)
 219                         return err;
 220         }
 221
 222         family->mcgrp_offset = first_id;
 223
 224         /* if still initializing, can't and don't need to to realloc bitmaps */
 225         if (!init_net.genl_sock)
 226                 return 0;
 227
 228         if (family->netnsok) {
 229                 struct net *net;
 230
 231                 netlink_table_grab();
 232                 rcu_read_lock();
 233                 for_each_net_rcu(net) {
 234                         err = __netlink_change_ngroups(net->genl_sock,
 235                                         mc_groups_longs * BITS_PER_LONG);
 236                         if (err) {
 237                                 /*
 238                                  * No need to roll back, can only fail if
 239                                  * memory allocation fails and then the
 240                                  * number of _possible_ groups has been
 241                                  * increased on some sockets which is ok.
 242                                  */
 243                                 break;
 244                         }
 245                 }
 246                 rcu_read_unlock();
 247                 netlink_table_ungrab();
 248         } else {
 249                 err = netlink_change_ngroups(init_net.genl_sock,
 250                                              mc_groups_longs * BITS_PER_LONG);
 251         }
 252
 253         if (groups_allocated && err) {
 254                 for (i = 0; i < family->n_mcgrps; i++)
 255                         clear_bit(family->mcgrp_offset + i, mc_groups);
 256         }
 257
 258         return err;
 259 }
 260
 261 static void genl_unregister_mc_groups(const struct genl_family *family)
 262 {
 263         struct net *net;
 264         int i;
 265
 266         netlink_table_grab();
 267         rcu_read_lock();
 268         for_each_net_rcu(net) {
 269                 for (i = 0; i < family->n_mcgrps; i++)
 270                         __netlink_clear_multicast_users(
 271                                 net->genl_sock, family->mcgrp_offset + i);
 272         }
 273         rcu_read_unlock();
 274         netlink_table_ungrab();
 275
 276         for (i = 0; i < family->n_mcgrps; i++) {
 277                 int grp_id = family->mcgrp_offset + i;
 278
 279                 if (grp_id != 1)
 280                         clear_bit(grp_id, mc_groups);
 281                 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
 282                                 &family->mcgrps[i], grp_id);
 283         }
 284 }
 285
 286 static int genl_validate_ops(const struct genl_family *family)
 287 {
 288         const struct genl_ops *ops = family->ops;
 289         unsigned int n_ops = family->n_ops;
 290         int i, j;
 291
 292         if (WARN_ON(n_ops && !ops))
 293                 return -EINVAL;
 294
 295         if (!n_ops)
 296                 return 0;
 297
 298         for (i = 0; i < n_ops; i++) {
 299                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 300                         return -EINVAL;
 301                 for (j = i + 1; j < n_ops; j++)
 302                         if (ops[i].cmd == ops[j].cmd)
 303                                 return -EINVAL;
 304         }
 305
 306         return 0;
 307 }
 308
 309 /**
 310  * genl_register_family - register a generic netlink family
 311  * @family: generic netlink family
 312  *
 313  * Registers the specified family after validating it first. Only one
 314  * family may be registered with the same family name or identifier.
 315  *
 316  * The family's ops, multicast groups and module pointer must already
 317  * be assigned.
 318  *
 319  * Return 0 on success or a negative error code.
 320  */
 321 int genl_register_family(struct genl_family *family)
 322 {
 323         int err, i;
 324         int start = GENL_START_ALLOC, end = GENL_MAX_ID;
 325
 326         err = genl_validate_ops(family);
 327         if (err)
 328                 return err;
 329
 330         genl_lock_all();
 331
 332         if (genl_family_find_byname(family->name)) {
 333                 err = -EEXIST;
 334                 goto errout_locked;
 335         }
 336
 337         /*
 338          * Sadly, a few cases need to be special-cased
 339          * due to them having previously abused the API
 340          * and having used their family ID also as their
 341          * multicast group ID, so we use reserved IDs
 342          * for both to be sure we can do that mapping.
 343          */
 344         if (family == &genl_ctrl) {
 345                 /* and this needs to be special for initial family lookups */
 346                 start = end = GENL_ID_CTRL;
 347         } else if (strcmp(family->name, "pmcraid") == 0) {
 348                 start = end = GENL_ID_PMCRAID;
 349         } else if (strcmp(family->name, "VFS_DQUOT") == 0) {
 350                 start = end = GENL_ID_VFS_DQUOT;
 351         }
 352
 353         if (family->maxattr && !family->parallel_ops) {
 354                 family->attrbuf = kmalloc((family->maxattr+1) *
 355                                         sizeof(struct nlattr *), GFP_KERNEL);
 356                 if (family->attrbuf == NULL) {
 357                         err = -ENOMEM;
 358                         goto errout_locked;
 359                 }
 360         } else
 361                 family->attrbuf = NULL;
 362
 363         family->id = idr_alloc(&genl_fam_idr, family,
 364                                start, end + 1, GFP_KERNEL);
 365         if (!family->id)
 366                 goto errout_locked;
 367
 368         err = genl_validate_assign_mc_groups(family);
 369         if (err)
 370                 goto errout_remove;
 371
 372         genl_unlock_all();
 373
 374         /* send all events */
 375         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 376         for (i = 0; i < family->n_mcgrps; i++)
 377                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 378                                 &family->mcgrps[i], family->mcgrp_offset + i);
 379
 380         return 0;
 381
 382 errout_remove:
 383         idr_remove(&genl_fam_idr, family->id);
 384 errout_locked:
 385         genl_unlock_all();
 386         return err;
 387 }
 388 EXPORT_SYMBOL(genl_register_family);
 389
 390 /**
 391  * genl_unregister_family - unregister generic netlink family
 392  * @family: generic netlink family
 393  *
 394  * Unregisters the specified family.
 395  *
 396  * Returns 0 on success or a negative error code.
 397  */
 398 int genl_unregister_family(const struct genl_family *family)
 399 {
 400         genl_lock_all();
 401
 402         if (genl_family_find_byid(family->id)) {
 403                 genl_unlock_all();
 404                 return -ENOENT;
 405         }
 406
 407         genl_unregister_mc_groups(family);
 408
 409         idr_remove(&genl_fam_idr, family->id);
 410
 411         up_write(&cb_lock);
 412         wait_event(genl_sk_destructing_waitq,
 413                    atomic_read(&genl_sk_destructing_cnt) == 0);
 414         genl_unlock();
 415
 416         kfree(family->attrbuf);
 417
 418         genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 419
 420         return 0;
 421 }
 422 EXPORT_SYMBOL(genl_unregister_family);
 423
 424 /**
 425  * genlmsg_put - Add generic netlink header to netlink message
 426  * @skb: socket buffer holding the message
 427  * @portid: netlink portid the message is addressed to
 428  * @seq: sequence number (usually the one of the sender)
 429  * @family: generic netlink family
 430  * @flags: netlink message flags
 431  * @cmd: generic netlink command
 432  *
 433  * Returns pointer to user specific header
 434  */
 435 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 436                   const struct genl_family *family, int flags, u8 cmd)
 437 {
 438         struct nlmsghdr *nlh;
 439         struct genlmsghdr *hdr;
 440
 441         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 442                         family->hdrsize, flags);
 443         if (nlh == NULL)
 444                 return NULL;
 445
 446         hdr = nlmsg_data(nlh);
 447         hdr->cmd = cmd;
 448         hdr->version = family->version;
 449         hdr->reserved = 0;
 450
 451         return (char *) hdr + GENL_HDRLEN;
 452 }
 453 EXPORT_SYMBOL(genlmsg_put);
 454
 455 static int genl_lock_start(struct netlink_callback *cb)
 456 {
 457         /* our ops are always const - netlink API doesn't propagate that */
 458         const struct genl_ops *ops = cb->data;
 459         int rc = 0;
 460
 461         if (ops->start) {
 462                 genl_lock();
 463                 rc = ops->start(cb);
 464                 genl_unlock();
 465         }
 466         return rc;
 467 }
 468
 469 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 470 {
 471         /* our ops are always const - netlink API doesn't propagate that */
 472         const struct genl_ops *ops = cb->data;
 473         int rc;
 474
 475         genl_lock();
 476         rc = ops->dumpit(skb, cb);
 477         genl_unlock();
 478         return rc;
 479 }
 480
 481 static int genl_lock_done(struct netlink_callback *cb)
 482 {
 483         /* our ops are always const - netlink API doesn't propagate that */
 484         const struct genl_ops *ops = cb->data;
 485         int rc = 0;
 486
 487         if (ops->done) {
 488                 genl_lock();
 489                 rc = ops->done(cb);
 490                 genl_unlock();
 491         }
 492         return rc;
 493 }
 494
 495 static int genl_family_rcv_msg(const struct genl_family *family,
 496                                struct sk_buff *skb,
 497                                struct nlmsghdr *nlh)
 498 {
 499         const struct genl_ops *ops;
 500         struct net *net = sock_net(skb->sk);
 501         struct genl_info info;
 502         struct genlmsghdr *hdr = nlmsg_data(nlh);
 503         struct nlattr **attrbuf;
 504         int hdrlen, err;
 505
 506         /* this family doesn't exist in this netns */
 507         if (!family->netnsok && !net_eq(net, &init_net))
 508                 return -ENOENT;
 509
 510         hdrlen = GENL_HDRLEN + family->hdrsize;
 511         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 512                 return -EINVAL;
 513
 514         ops = genl_get_cmd(hdr->cmd, family);
 515         if (ops == NULL)
 516                 return -EOPNOTSUPP;
 517
 518         if ((ops->flags & GENL_ADMIN_PERM) &&
 519             !netlink_capable(skb, CAP_NET_ADMIN))
 520                 return -EPERM;
 521
 522         if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
 523             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 524                 return -EPERM;
 525
 526         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 527                 int rc;
 528
 529                 if (ops->dumpit == NULL)
 530                         return -EOPNOTSUPP;
 531
 532                 if (!family->parallel_ops) {
 533                         struct netlink_dump_control c = {
 534                                 .module = family->module,
 535                                 /* we have const, but the netlink API doesn't */
 536                                 .data = (void *)ops,
 537                                 .start = genl_lock_start,
 538                                 .dump = genl_lock_dumpit,
 539                                 .done = genl_lock_done,
 540                         };
 541
 542                         genl_unlock();
 543                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 544                         genl_lock();
 545
 546                 } else {
 547                         struct netlink_dump_control c = {
 548                                 .module = family->module,
 549                                 .start = ops->start,
 550                                 .dump = ops->dumpit,
 551                                 .done = ops->done,
 552                         };
 553
 554                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 555                 }
 556
 557                 return rc;
 558         }
 559
 560         if (ops->doit == NULL)
 561                 return -EOPNOTSUPP;
 562
 563         if (family->maxattr && family->parallel_ops) {
 564                 attrbuf = kmalloc((family->maxattr+1) *
 565                                         sizeof(struct nlattr *), GFP_KERNEL);
 566                 if (attrbuf == NULL)
 567                         return -ENOMEM;
 568         } else
 569                 attrbuf = family->attrbuf;
 570
 571         if (attrbuf) {
 572                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 573                                   ops->policy);
 574                 if (err < 0)
 575                         goto out;
 576         }
 577
 578         info.snd_seq = nlh->nlmsg_seq;
 579         info.snd_portid = NETLINK_CB(skb).portid;
 580         info.nlhdr = nlh;
 581         info.genlhdr = nlmsg_data(nlh);
 582         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 583         info.attrs = attrbuf;
 584         genl_info_net_set(&info, net);
 585         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 586
 587         if (family->pre_doit) {
 588                 err = family->pre_doit(ops, skb, &info);
 589                 if (err)
 590                         goto out;
 591         }
 592
 593         err = ops->doit(skb, &info);
 594
 595         if (family->post_doit)
 596                 family->post_doit(ops, skb, &info);
 597
 598 out:
 599         if (family->parallel_ops)
 600                 kfree(attrbuf);
 601
 602         return err;
 603 }
 604
 605 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 606 {
 607         const struct genl_family *family;
 608         int err;
 609
 610         family = genl_family_find_byid(nlh->nlmsg_type);
 611         if (family == NULL)
 612                 return -ENOENT;
 613
 614         if (!family->parallel_ops)
 615                 genl_lock();
 616
 617         err = genl_family_rcv_msg(family, skb, nlh);
 618
 619         if (!family->parallel_ops)
 620                 genl_unlock();
 621
 622         return err;
 623 }
 624
 625 static void genl_rcv(struct sk_buff *skb)
 626 {
 627         down_read(&cb_lock);
 628         netlink_rcv_skb(skb, &genl_rcv_msg);
 629         up_read(&cb_lock);
 630 }
 631
 632 /**************************************************************************
 633  * Controller
 634  **************************************************************************/
 635
 636 static struct genl_family genl_ctrl;
 637
 638 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 639                           u32 flags, struct sk_buff *skb, u8 cmd)
 640 {
 641         void *hdr;
 642
 643         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 644         if (hdr == NULL)
 645                 return -1;
 646
 647         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 648             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 649             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 650             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 651             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 652                 goto nla_put_failure;
 653
 654         if (family->n_ops) {
 655                 struct nlattr *nla_ops;
 656                 int i;
 657
 658                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 659                 if (nla_ops == NULL)
 660                         goto nla_put_failure;
 661
 662                 for (i = 0; i < family->n_ops; i++) {
 663                         struct nlattr *nest;
 664                         const struct genl_ops *ops = &family->ops[i];
 665                         u32 op_flags = ops->flags;
 666
 667                         if (ops->dumpit)
 668                                 op_flags |= GENL_CMD_CAP_DUMP;
 669                         if (ops->doit)
 670                                 op_flags |= GENL_CMD_CAP_DO;
 671                         if (ops->policy)
 672                                 op_flags |= GENL_CMD_CAP_HASPOL;
 673
 674                         nest = nla_nest_start(skb, i + 1);
 675                         if (nest == NULL)
 676                                 goto nla_put_failure;
 677
 678                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 679                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 680                                 goto nla_put_failure;
 681
 682                         nla_nest_end(skb, nest);
 683                 }
 684
 685                 nla_nest_end(skb, nla_ops);
 686         }
 687
 688         if (family->n_mcgrps) {
 689                 struct nlattr *nla_grps;
 690                 int i;
 691
 692                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 693                 if (nla_grps == NULL)
 694                         goto nla_put_failure;
 695
 696                 for (i = 0; i < family->n_mcgrps; i++) {
 697                         struct nlattr *nest;
 698                         const struct genl_multicast_group *grp;
 699
 700                         grp = &family->mcgrps[i];
 701
 702                         nest = nla_nest_start(skb, i + 1);
 703                         if (nest == NULL)
 704                                 goto nla_put_failure;
 705
 706                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 707                                         family->mcgrp_offset + i) ||
 708                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 709                                            grp->name))
 710                                 goto nla_put_failure;
 711
 712                         nla_nest_end(skb, nest);
 713                 }
 714                 nla_nest_end(skb, nla_grps);
 715         }
 716
 717         genlmsg_end(skb, hdr);
 718         return 0;
 719
 720 nla_put_failure:
 721         genlmsg_cancel(skb, hdr);
 722         return -EMSGSIZE;
 723 }
 724
 725 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
 726                                 const struct genl_multicast_group *grp,
 727                                 int grp_id, u32 portid, u32 seq, u32 flags,
 728                                 struct sk_buff *skb, u8 cmd)
 729 {
 730         void *hdr;
 731         struct nlattr *nla_grps;
 732         struct nlattr *nest;
 733
 734         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 735         if (hdr == NULL)
 736                 return -1;
 737
 738         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 739             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 740                 goto nla_put_failure;
 741
 742         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 743         if (nla_grps == NULL)
 744                 goto nla_put_failure;
 745
 746         nest = nla_nest_start(skb, 1);
 747         if (nest == NULL)
 748                 goto nla_put_failure;
 749
 750         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 751             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 752                            grp->name))
 753                 goto nla_put_failure;
 754
 755         nla_nest_end(skb, nest);
 756         nla_nest_end(skb, nla_grps);
 757
 758         genlmsg_end(skb, hdr);
 759         return 0;
 760
 761 nla_put_failure:
 762         genlmsg_cancel(skb, hdr);
 763         return -EMSGSIZE;
 764 }
 765
 766 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 767 {
 768         int n = 0;
 769         struct genl_family *rt;
 770         struct net *net = sock_net(skb->sk);
 771         int fams_to_skip = cb->args[0];
 772         unsigned int id;
 773
 774         idr_for_each_entry(&genl_fam_idr, rt, id) {
 775                 if (!rt->netnsok && !net_eq(net, &init_net))
 776                         continue;
 777
 778                 if (n++ < fams_to_skip)
 779                         continue;
 780
 781                 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 782                                    cb->nlh->nlmsg_seq, NLM_F_MULTI,
 783                                    skb, CTRL_CMD_NEWFAMILY) < 0)
 784                         break;
 785         }
 786
 787         cb->args[0] = n;
 788         return skb->len;
 789 }
 790
 791 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
 792                                              u32 portid, int seq, u8 cmd)
 793 {
 794         struct sk_buff *skb;
 795         int err;
 796
 797         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 798         if (skb == NULL)
 799                 return ERR_PTR(-ENOBUFS);
 800
 801         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 802         if (err < 0) {
 803                 nlmsg_free(skb);
 804                 return ERR_PTR(err);
 805         }
 806
 807         return skb;
 808 }
 809
 810 static struct sk_buff *
 811 ctrl_build_mcgrp_msg(const struct genl_family *family,
 812                      const struct genl_multicast_group *grp,
 813                      int grp_id, u32 portid, int seq, u8 cmd)
 814 {
 815         struct sk_buff *skb;
 816         int err;
 817
 818         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 819         if (skb == NULL)
 820                 return ERR_PTR(-ENOBUFS);
 821
 822         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 823                                    seq, 0, skb, cmd);
 824         if (err < 0) {
 825                 nlmsg_free(skb);
 826                 return ERR_PTR(err);
 827         }
 828
 829         return skb;
 830 }
 831
 832 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 833         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 834         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 835                                     .len = GENL_NAMSIZ - 1 },
 836 };
 837
 838 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 839 {
 840         struct sk_buff *msg;
 841         const struct genl_family *res = NULL;
 842         int err = -EINVAL;
 843
 844         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 845                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 846                 res = genl_family_find_byid(id);
 847                 err = -ENOENT;
 848         }
 849
 850         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 851                 char *name;
 852
 853                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 854                 res = genl_family_find_byname(name);
 855 #ifdef CONFIG_MODULES
 856                 if (res == NULL) {
 857                         genl_unlock();
 858                         up_read(&cb_lock);
 859                         request_module("net-pf-%d-proto-%d-family-%s",
 860                                        PF_NETLINK, NETLINK_GENERIC, name);
 861                         down_read(&cb_lock);
 862                         genl_lock();
 863                         res = genl_family_find_byname(name);
 864                 }
 865 #endif
 866                 err = -ENOENT;
 867         }
 868
 869         if (res == NULL)
 870                 return err;
 871
 872         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 873                 /* family doesn't exist here */
 874                 return -ENOENT;
 875         }
 876
 877         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 878                                     CTRL_CMD_NEWFAMILY);
 879         if (IS_ERR(msg))
 880                 return PTR_ERR(msg);
 881
 882         return genlmsg_reply(msg, info);
 883 }
 884
 885 static int genl_ctrl_event(int event, const struct genl_family *family,
 886                            const struct genl_multicast_group *grp,
 887                            int grp_id)
 888 {
 889         struct sk_buff *msg;
 890
 891         /* genl is still initialising */
 892         if (!init_net.genl_sock)
 893                 return 0;
 894
 895         switch (event) {
 896         case CTRL_CMD_NEWFAMILY:
 897         case CTRL_CMD_DELFAMILY:
 898                 WARN_ON(grp);
 899                 msg = ctrl_build_family_msg(family, 0, 0, event);
 900                 break;
 901         case CTRL_CMD_NEWMCAST_GRP:
 902         case CTRL_CMD_DELMCAST_GRP:
 903                 BUG_ON(!grp);
 904                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 905                 break;
 906         default:
 907                 return -EINVAL;
 908         }
 909
 910         if (IS_ERR(msg))
 911                 return PTR_ERR(msg);
 912
 913         if (!family->netnsok) {
 914                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 915                                         0, GFP_KERNEL);
 916         } else {
 917                 rcu_read_lock();
 918                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 919                                         0, GFP_ATOMIC);
 920                 rcu_read_unlock();
 921         }
 922
 923         return 0;
 924 }
 925
 926 static const struct genl_ops genl_ctrl_ops[] = {
 927         {
 928                 .cmd            = CTRL_CMD_GETFAMILY,
 929                 .doit           = ctrl_getfamily,
 930                 .dumpit         = ctrl_dumpfamily,
 931                 .policy         = ctrl_policy,
 932         },
 933 };
 934
 935 static const struct genl_multicast_group genl_ctrl_groups[] = {
 936         { .name = "notify", },
 937 };
 938
 939 static struct genl_family genl_ctrl = {
 940         .module = THIS_MODULE,
 941         .ops = genl_ctrl_ops,
 942         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
 943         .mcgrps = genl_ctrl_groups,
 944         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
 945         .id = GENL_ID_CTRL,
 946         .name = "nlctrl",
 947         .version = 0x2,
 948         .maxattr = CTRL_ATTR_MAX,
 949         .netnsok = true,
 950 };
 951
 952 static int genl_bind(struct net *net, int group)
 953 {
 954         struct genl_family *f;
 955         int err = -ENOENT;
 956         unsigned int id;
 957
 958         down_read(&cb_lock);
 959
 960         idr_for_each_entry(&genl_fam_idr, f, id) {
 961                 if (group >= f->mcgrp_offset &&
 962                     group < f->mcgrp_offset + f->n_mcgrps) {
 963                         int fam_grp = group - f->mcgrp_offset;
 964
 965                         if (!f->netnsok && net != &init_net)
 966                                 err = -ENOENT;
 967                         else if (f->mcast_bind)
 968                                 err = f->mcast_bind(net, fam_grp);
 969                         else
 970                                 err = 0;
 971                         break;
 972                 }
 973         }
 974         up_read(&cb_lock);
 975
 976         return err;
 977 }
 978
 979 static void genl_unbind(struct net *net, int group)
 980 {
 981         struct genl_family *f;
 982         unsigned int id;
 983
 984         down_read(&cb_lock);
 985
 986         idr_for_each_entry(&genl_fam_idr, f, id) {
 987                 if (group >= f->mcgrp_offset &&
 988                     group < f->mcgrp_offset + f->n_mcgrps) {
 989                         int fam_grp = group - f->mcgrp_offset;
 990
 991                         if (f->mcast_unbind)
 992                                 f->mcast_unbind(net, fam_grp);
 993                         break;
 994                 }
 995         }
 996         up_read(&cb_lock);
 997 }
 998
 999 static int __net_init genl_pernet_init(struct net *net)
1000 {
1001         struct netlink_kernel_cfg cfg = {
1002                 .input          = genl_rcv,
1003                 .flags          = NL_CFG_F_NONROOT_RECV,
1004                 .bind           = genl_bind,
1005                 .unbind         = genl_unbind,
1006         };
1007
1008         /* we'll bump the group number right afterwards */
1009         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1010
1011         if (!net->genl_sock && net_eq(net, &init_net))
1012                 panic("GENL: Cannot initialize generic netlink\n");
1013
1014         if (!net->genl_sock)
1015                 return -ENOMEM;
1016
1017         return 0;
1018 }
1019
1020 static void __net_exit genl_pernet_exit(struct net *net)
1021 {
1022         netlink_kernel_release(net->genl_sock);
1023         net->genl_sock = NULL;
1024 }
1025
1026 static struct pernet_operations genl_pernet_ops = {
1027         .init = genl_pernet_init,
1028         .exit = genl_pernet_exit,
1029 };
1030
1031 static int __init genl_init(void)
1032 {
1033         int err;
1034
1035         err = genl_register_family(&genl_ctrl);
1036         if (err < 0)
1037                 goto problem;
1038
1039         err = register_pernet_subsys(&genl_pernet_ops);
1040         if (err)
1041                 goto problem;
1042
1043         return 0;
1044
1045 problem:
1046         panic("GENL: Cannot register controller: %d\n", err);
1047 }
1048
1049 subsys_initcall(genl_init);
1050
1051 /**
1052  * genl_family_attrbuf - return family's attrbuf
1053  * @family: the family
1054  *
1055  * Return the family's attrbuf, while validating that it's
1056  * actually valid to access it.
1057  *
1058  * You cannot use this function with a family that has parallel_ops
1059  * and you can only use it within (pre/post) doit/dumpit callbacks.
1060  */
1061 struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1062 {
1063         if (!WARN_ON(family->parallel_ops))
1064                 lockdep_assert_held(&genl_mutex);
1065
1066         return family->attrbuf;
1067 }
1068 EXPORT_SYMBOL(genl_family_attrbuf);
1069
1070 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1071                          gfp_t flags)
1072 {
1073         struct sk_buff *tmp;
1074         struct net *net, *prev = NULL;
1075         int err;
1076
1077         for_each_net_rcu(net) {
1078                 if (prev) {
1079                         tmp = skb_clone(skb, flags);
1080                         if (!tmp) {
1081                                 err = -ENOMEM;
1082                                 goto error;
1083                         }
1084                         err = nlmsg_multicast(prev->genl_sock, tmp,
1085                                               portid, group, flags);
1086                         if (err)
1087                                 goto error;
1088                 }
1089
1090                 prev = net;
1091         }
1092
1093         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1094  error:
1095         kfree_skb(skb);
1096         return err;
1097 }
1098
1099 int genlmsg_multicast_allns(const struct genl_family *family,
1100                             struct sk_buff *skb, u32 portid,
1101                             unsigned int group, gfp_t flags)
1102 {
1103         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1104                 return -EINVAL;
1105         group = family->mcgrp_offset + group;
1106         return genlmsg_mcast(skb, portid, group, flags);
1107 }
1108 EXPORT_SYMBOL(genlmsg_multicast_allns);
1109
1110 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1111                  struct genl_info *info, u32 group, gfp_t flags)
1112 {
1113         struct net *net = genl_info_net(info);
1114         struct sock *sk = net->genl_sock;
1115         int report = 0;
1116
1117         if (info->nlhdr)
1118                 report = nlmsg_report(info->nlhdr);
1119
1120         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1121                 return;
1122         group = family->mcgrp_offset + group;
1123         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1124 }
1125 EXPORT_SYMBOL(genl_notify);