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 < 0) {
 366                 err = family->id;
 367                 goto errout_locked;
 368         }
 369
 370         err = genl_validate_assign_mc_groups(family);
 371         if (err)
 372                 goto errout_remove;
 373
 374         genl_unlock_all();
 375
 376         /* send all events */
 377         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 378         for (i = 0; i < family->n_mcgrps; i++)
 379                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 380                                 &family->mcgrps[i], family->mcgrp_offset + i);
 381
 382         return 0;
 383
 384 errout_remove:
 385         idr_remove(&genl_fam_idr, family->id);
 386         kfree(family->attrbuf);
 387 errout_locked:
 388         genl_unlock_all();
 389         return err;
 390 }
 391 EXPORT_SYMBOL(genl_register_family);
 392
 393 /**
 394  * genl_unregister_family - unregister generic netlink family
 395  * @family: generic netlink family
 396  *
 397  * Unregisters the specified family.
 398  *
 399  * Returns 0 on success or a negative error code.
 400  */
 401 int genl_unregister_family(const struct genl_family *family)
 402 {
 403         genl_lock_all();
 404
 405         if (!genl_family_find_byid(family->id)) {
 406                 genl_unlock_all();
 407                 return -ENOENT;
 408         }
 409
 410         genl_unregister_mc_groups(family);
 411
 412         idr_remove(&genl_fam_idr, family->id);
 413
 414         up_write(&cb_lock);
 415         wait_event(genl_sk_destructing_waitq,
 416                    atomic_read(&genl_sk_destructing_cnt) == 0);
 417         genl_unlock();
 418
 419         kfree(family->attrbuf);
 420
 421         genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 422
 423         return 0;
 424 }
 425 EXPORT_SYMBOL(genl_unregister_family);
 426
 427 /**
 428  * genlmsg_put - Add generic netlink header to netlink message
 429  * @skb: socket buffer holding the message
 430  * @portid: netlink portid the message is addressed to
 431  * @seq: sequence number (usually the one of the sender)
 432  * @family: generic netlink family
 433  * @flags: netlink message flags
 434  * @cmd: generic netlink command
 435  *
 436  * Returns pointer to user specific header
 437  */
 438 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 439                   const struct genl_family *family, int flags, u8 cmd)
 440 {
 441         struct nlmsghdr *nlh;
 442         struct genlmsghdr *hdr;
 443
 444         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 445                         family->hdrsize, flags);
 446         if (nlh == NULL)
 447                 return NULL;
 448
 449         hdr = nlmsg_data(nlh);
 450         hdr->cmd = cmd;
 451         hdr->version = family->version;
 452         hdr->reserved = 0;
 453
 454         return (char *) hdr + GENL_HDRLEN;
 455 }
 456 EXPORT_SYMBOL(genlmsg_put);
 457
 458 static int genl_lock_start(struct netlink_callback *cb)
 459 {
 460         /* our ops are always const - netlink API doesn't propagate that */
 461         const struct genl_ops *ops = cb->data;
 462         int rc = 0;
 463
 464         if (ops->start) {
 465                 genl_lock();
 466                 rc = ops->start(cb);
 467                 genl_unlock();
 468         }
 469         return rc;
 470 }
 471
 472 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 473 {
 474         /* our ops are always const - netlink API doesn't propagate that */
 475         const struct genl_ops *ops = cb->data;
 476         int rc;
 477
 478         genl_lock();
 479         rc = ops->dumpit(skb, cb);
 480         genl_unlock();
 481         return rc;
 482 }
 483
 484 static int genl_lock_done(struct netlink_callback *cb)
 485 {
 486         /* our ops are always const - netlink API doesn't propagate that */
 487         const struct genl_ops *ops = cb->data;
 488         int rc = 0;
 489
 490         if (ops->done) {
 491                 genl_lock();
 492                 rc = ops->done(cb);
 493                 genl_unlock();
 494         }
 495         return rc;
 496 }
 497
 498 static int genl_family_rcv_msg(const struct genl_family *family,
 499                                struct sk_buff *skb,
 500                                struct nlmsghdr *nlh)
 501 {
 502         const struct genl_ops *ops;
 503         struct net *net = sock_net(skb->sk);
 504         struct genl_info info;
 505         struct genlmsghdr *hdr = nlmsg_data(nlh);
 506         struct nlattr **attrbuf;
 507         int hdrlen, err;
 508
 509         /* this family doesn't exist in this netns */
 510         if (!family->netnsok && !net_eq(net, &init_net))
 511                 return -ENOENT;
 512
 513         hdrlen = GENL_HDRLEN + family->hdrsize;
 514         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 515                 return -EINVAL;
 516
 517         ops = genl_get_cmd(hdr->cmd, family);
 518         if (ops == NULL)
 519                 return -EOPNOTSUPP;
 520
 521         if ((ops->flags & GENL_ADMIN_PERM) &&
 522             !netlink_capable(skb, CAP_NET_ADMIN))
 523                 return -EPERM;
 524
 525         if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
 526             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 527                 return -EPERM;
 528
 529         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 530                 int rc;
 531
 532                 if (ops->dumpit == NULL)
 533                         return -EOPNOTSUPP;
 534
 535                 if (!family->parallel_ops) {
 536                         struct netlink_dump_control c = {
 537                                 .module = family->module,
 538                                 /* we have const, but the netlink API doesn't */
 539                                 .data = (void *)ops,
 540                                 .start = genl_lock_start,
 541                                 .dump = genl_lock_dumpit,
 542                                 .done = genl_lock_done,
 543                         };
 544
 545                         genl_unlock();
 546                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 547                         genl_lock();
 548
 549                 } else {
 550                         struct netlink_dump_control c = {
 551                                 .module = family->module,
 552                                 .start = ops->start,
 553                                 .dump = ops->dumpit,
 554                                 .done = ops->done,
 555                         };
 556
 557                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 558                 }
 559
 560                 return rc;
 561         }
 562
 563         if (ops->doit == NULL)
 564                 return -EOPNOTSUPP;
 565
 566         if (family->maxattr && family->parallel_ops) {
 567                 attrbuf = kmalloc((family->maxattr+1) *
 568                                         sizeof(struct nlattr *), GFP_KERNEL);
 569                 if (attrbuf == NULL)
 570                         return -ENOMEM;
 571         } else
 572                 attrbuf = family->attrbuf;
 573
 574         if (attrbuf) {
 575                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 576                                   ops->policy);
 577                 if (err < 0)
 578                         goto out;
 579         }
 580
 581         info.snd_seq = nlh->nlmsg_seq;
 582         info.snd_portid = NETLINK_CB(skb).portid;
 583         info.nlhdr = nlh;
 584         info.genlhdr = nlmsg_data(nlh);
 585         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 586         info.attrs = attrbuf;
 587         genl_info_net_set(&info, net);
 588         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 589
 590         if (family->pre_doit) {
 591                 err = family->pre_doit(ops, skb, &info);
 592                 if (err)
 593                         goto out;
 594         }
 595
 596         err = ops->doit(skb, &info);
 597
 598         if (family->post_doit)
 599                 family->post_doit(ops, skb, &info);
 600
 601 out:
 602         if (family->parallel_ops)
 603                 kfree(attrbuf);
 604
 605         return err;
 606 }
 607
 608 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 609 {
 610         const struct genl_family *family;
 611         int err;
 612
 613         family = genl_family_find_byid(nlh->nlmsg_type);
 614         if (family == NULL)
 615                 return -ENOENT;
 616
 617         if (!family->parallel_ops)
 618                 genl_lock();
 619
 620         err = genl_family_rcv_msg(family, skb, nlh);
 621
 622         if (!family->parallel_ops)
 623                 genl_unlock();
 624
 625         return err;
 626 }
 627
 628 static void genl_rcv(struct sk_buff *skb)
 629 {
 630         down_read(&cb_lock);
 631         netlink_rcv_skb(skb, &genl_rcv_msg);
 632         up_read(&cb_lock);
 633 }
 634
 635 /**************************************************************************
 636  * Controller
 637  **************************************************************************/
 638
 639 static struct genl_family genl_ctrl;
 640
 641 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
 642                           u32 flags, struct sk_buff *skb, u8 cmd)
 643 {
 644         void *hdr;
 645
 646         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 647         if (hdr == NULL)
 648                 return -1;
 649
 650         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 651             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 652             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 653             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 654             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 655                 goto nla_put_failure;
 656
 657         if (family->n_ops) {
 658                 struct nlattr *nla_ops;
 659                 int i;
 660
 661                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 662                 if (nla_ops == NULL)
 663                         goto nla_put_failure;
 664
 665                 for (i = 0; i < family->n_ops; i++) {
 666                         struct nlattr *nest;
 667                         const struct genl_ops *ops = &family->ops[i];
 668                         u32 op_flags = ops->flags;
 669
 670                         if (ops->dumpit)
 671                                 op_flags |= GENL_CMD_CAP_DUMP;
 672                         if (ops->doit)
 673                                 op_flags |= GENL_CMD_CAP_DO;
 674                         if (ops->policy)
 675                                 op_flags |= GENL_CMD_CAP_HASPOL;
 676
 677                         nest = nla_nest_start(skb, i + 1);
 678                         if (nest == NULL)
 679                                 goto nla_put_failure;
 680
 681                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 682                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 683                                 goto nla_put_failure;
 684
 685                         nla_nest_end(skb, nest);
 686                 }
 687
 688                 nla_nest_end(skb, nla_ops);
 689         }
 690
 691         if (family->n_mcgrps) {
 692                 struct nlattr *nla_grps;
 693                 int i;
 694
 695                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 696                 if (nla_grps == NULL)
 697                         goto nla_put_failure;
 698
 699                 for (i = 0; i < family->n_mcgrps; i++) {
 700                         struct nlattr *nest;
 701                         const struct genl_multicast_group *grp;
 702
 703                         grp = &family->mcgrps[i];
 704
 705                         nest = nla_nest_start(skb, i + 1);
 706                         if (nest == NULL)
 707                                 goto nla_put_failure;
 708
 709                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 710                                         family->mcgrp_offset + i) ||
 711                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 712                                            grp->name))
 713                                 goto nla_put_failure;
 714
 715                         nla_nest_end(skb, nest);
 716                 }
 717                 nla_nest_end(skb, nla_grps);
 718         }
 719
 720         genlmsg_end(skb, hdr);
 721         return 0;
 722
 723 nla_put_failure:
 724         genlmsg_cancel(skb, hdr);
 725         return -EMSGSIZE;
 726 }
 727
 728 static int ctrl_fill_mcgrp_info(const struct genl_family *family,
 729                                 const struct genl_multicast_group *grp,
 730                                 int grp_id, u32 portid, u32 seq, u32 flags,
 731                                 struct sk_buff *skb, u8 cmd)
 732 {
 733         void *hdr;
 734         struct nlattr *nla_grps;
 735         struct nlattr *nest;
 736
 737         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 738         if (hdr == NULL)
 739                 return -1;
 740
 741         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 742             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 743                 goto nla_put_failure;
 744
 745         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 746         if (nla_grps == NULL)
 747                 goto nla_put_failure;
 748
 749         nest = nla_nest_start(skb, 1);
 750         if (nest == NULL)
 751                 goto nla_put_failure;
 752
 753         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 754             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 755                            grp->name))
 756                 goto nla_put_failure;
 757
 758         nla_nest_end(skb, nest);
 759         nla_nest_end(skb, nla_grps);
 760
 761         genlmsg_end(skb, hdr);
 762         return 0;
 763
 764 nla_put_failure:
 765         genlmsg_cancel(skb, hdr);
 766         return -EMSGSIZE;
 767 }
 768
 769 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 770 {
 771         int n = 0;
 772         struct genl_family *rt;
 773         struct net *net = sock_net(skb->sk);
 774         int fams_to_skip = cb->args[0];
 775         unsigned int id;
 776
 777         idr_for_each_entry(&genl_fam_idr, rt, id) {
 778                 if (!rt->netnsok && !net_eq(net, &init_net))
 779                         continue;
 780
 781                 if (n++ < fams_to_skip)
 782                         continue;
 783
 784                 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 785                                    cb->nlh->nlmsg_seq, NLM_F_MULTI,
 786                                    skb, CTRL_CMD_NEWFAMILY) < 0) {
 787                         n--;
 788                         break;
 789                 }
 790         }
 791
 792         cb->args[0] = n;
 793         return skb->len;
 794 }
 795
 796 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family,
 797                                              u32 portid, int seq, u8 cmd)
 798 {
 799         struct sk_buff *skb;
 800         int err;
 801
 802         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 803         if (skb == NULL)
 804                 return ERR_PTR(-ENOBUFS);
 805
 806         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 807         if (err < 0) {
 808                 nlmsg_free(skb);
 809                 return ERR_PTR(err);
 810         }
 811
 812         return skb;
 813 }
 814
 815 static struct sk_buff *
 816 ctrl_build_mcgrp_msg(const struct genl_family *family,
 817                      const struct genl_multicast_group *grp,
 818                      int grp_id, u32 portid, int seq, u8 cmd)
 819 {
 820         struct sk_buff *skb;
 821         int err;
 822
 823         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 824         if (skb == NULL)
 825                 return ERR_PTR(-ENOBUFS);
 826
 827         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 828                                    seq, 0, skb, cmd);
 829         if (err < 0) {
 830                 nlmsg_free(skb);
 831                 return ERR_PTR(err);
 832         }
 833
 834         return skb;
 835 }
 836
 837 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 838         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 839         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 840                                     .len = GENL_NAMSIZ - 1 },
 841 };
 842
 843 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 844 {
 845         struct sk_buff *msg;
 846         const struct genl_family *res = NULL;
 847         int err = -EINVAL;
 848
 849         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 850                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 851                 res = genl_family_find_byid(id);
 852                 err = -ENOENT;
 853         }
 854
 855         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 856                 char *name;
 857
 858                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 859                 res = genl_family_find_byname(name);
 860 #ifdef CONFIG_MODULES
 861                 if (res == NULL) {
 862                         genl_unlock();
 863                         up_read(&cb_lock);
 864                         request_module("net-pf-%d-proto-%d-family-%s",
 865                                        PF_NETLINK, NETLINK_GENERIC, name);
 866                         down_read(&cb_lock);
 867                         genl_lock();
 868                         res = genl_family_find_byname(name);
 869                 }
 870 #endif
 871                 err = -ENOENT;
 872         }
 873
 874         if (res == NULL)
 875                 return err;
 876
 877         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 878                 /* family doesn't exist here */
 879                 return -ENOENT;
 880         }
 881
 882         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 883                                     CTRL_CMD_NEWFAMILY);
 884         if (IS_ERR(msg))
 885                 return PTR_ERR(msg);
 886
 887         return genlmsg_reply(msg, info);
 888 }
 889
 890 static int genl_ctrl_event(int event, const struct genl_family *family,
 891                            const struct genl_multicast_group *grp,
 892                            int grp_id)
 893 {
 894         struct sk_buff *msg;
 895
 896         /* genl is still initialising */
 897         if (!init_net.genl_sock)
 898                 return 0;
 899
 900         switch (event) {
 901         case CTRL_CMD_NEWFAMILY:
 902         case CTRL_CMD_DELFAMILY:
 903                 WARN_ON(grp);
 904                 msg = ctrl_build_family_msg(family, 0, 0, event);
 905                 break;
 906         case CTRL_CMD_NEWMCAST_GRP:
 907         case CTRL_CMD_DELMCAST_GRP:
 908                 BUG_ON(!grp);
 909                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 910                 break;
 911         default:
 912                 return -EINVAL;
 913         }
 914
 915         if (IS_ERR(msg))
 916                 return PTR_ERR(msg);
 917
 918         if (!family->netnsok) {
 919                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 920                                         0, GFP_KERNEL);
 921         } else {
 922                 rcu_read_lock();
 923                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 924                                         0, GFP_ATOMIC);
 925                 rcu_read_unlock();
 926         }
 927
 928         return 0;
 929 }
 930
 931 static const struct genl_ops genl_ctrl_ops[] = {
 932         {
 933                 .cmd            = CTRL_CMD_GETFAMILY,
 934                 .doit           = ctrl_getfamily,
 935                 .dumpit         = ctrl_dumpfamily,
 936                 .policy         = ctrl_policy,
 937         },
 938 };
 939
 940 static const struct genl_multicast_group genl_ctrl_groups[] = {
 941         { .name = "notify", },
 942 };
 943
 944 static struct genl_family genl_ctrl __ro_after_init = {
 945         .module = THIS_MODULE,
 946         .ops = genl_ctrl_ops,
 947         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
 948         .mcgrps = genl_ctrl_groups,
 949         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
 950         .id = GENL_ID_CTRL,
 951         .name = "nlctrl",
 952         .version = 0x2,
 953         .maxattr = CTRL_ATTR_MAX,
 954         .netnsok = true,
 955 };
 956
 957 static int genl_bind(struct net *net, int group)
 958 {
 959         struct genl_family *f;
 960         int err = -ENOENT;
 961         unsigned int id;
 962
 963         down_read(&cb_lock);
 964
 965         idr_for_each_entry(&genl_fam_idr, f, id) {
 966                 if (group >= f->mcgrp_offset &&
 967                     group < f->mcgrp_offset + f->n_mcgrps) {
 968                         int fam_grp = group - f->mcgrp_offset;
 969
 970                         if (!f->netnsok && net != &init_net)
 971                                 err = -ENOENT;
 972                         else if (f->mcast_bind)
 973                                 err = f->mcast_bind(net, fam_grp);
 974                         else
 975                                 err = 0;
 976                         break;
 977                 }
 978         }
 979         up_read(&cb_lock);
 980
 981         return err;
 982 }
 983
 984 static void genl_unbind(struct net *net, int group)
 985 {
 986         struct genl_family *f;
 987         unsigned int id;
 988
 989         down_read(&cb_lock);
 990
 991         idr_for_each_entry(&genl_fam_idr, f, id) {
 992                 if (group >= f->mcgrp_offset &&
 993                     group < f->mcgrp_offset + f->n_mcgrps) {
 994                         int fam_grp = group - f->mcgrp_offset;
 995
 996                         if (f->mcast_unbind)
 997                                 f->mcast_unbind(net, fam_grp);
 998                         break;
 999                 }
1000         }
1001         up_read(&cb_lock);
1002 }
1003
1004 static int __net_init genl_pernet_init(struct net *net)
1005 {
1006         struct netlink_kernel_cfg cfg = {
1007                 .input          = genl_rcv,
1008                 .flags          = NL_CFG_F_NONROOT_RECV,
1009                 .bind           = genl_bind,
1010                 .unbind         = genl_unbind,
1011         };
1012
1013         /* we'll bump the group number right afterwards */
1014         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1015
1016         if (!net->genl_sock && net_eq(net, &init_net))
1017                 panic("GENL: Cannot initialize generic netlink\n");
1018
1019         if (!net->genl_sock)
1020                 return -ENOMEM;
1021
1022         return 0;
1023 }
1024
1025 static void __net_exit genl_pernet_exit(struct net *net)
1026 {
1027         netlink_kernel_release(net->genl_sock);
1028         net->genl_sock = NULL;
1029 }
1030
1031 static struct pernet_operations genl_pernet_ops = {
1032         .init = genl_pernet_init,
1033         .exit = genl_pernet_exit,
1034 };
1035
1036 static int __init genl_init(void)
1037 {
1038         int err;
1039
1040         err = genl_register_family(&genl_ctrl);
1041         if (err < 0)
1042                 goto problem;
1043
1044         err = register_pernet_subsys(&genl_pernet_ops);
1045         if (err)
1046                 goto problem;
1047
1048         return 0;
1049
1050 problem:
1051         panic("GENL: Cannot register controller: %d\n", err);
1052 }
1053
1054 subsys_initcall(genl_init);
1055
1056 /**
1057  * genl_family_attrbuf - return family's attrbuf
1058  * @family: the family
1059  *
1060  * Return the family's attrbuf, while validating that it's
1061  * actually valid to access it.
1062  *
1063  * You cannot use this function with a family that has parallel_ops
1064  * and you can only use it within (pre/post) doit/dumpit callbacks.
1065  */
1066 struct nlattr **genl_family_attrbuf(const struct genl_family *family)
1067 {
1068         if (!WARN_ON(family->parallel_ops))
1069                 lockdep_assert_held(&genl_mutex);
1070
1071         return family->attrbuf;
1072 }
1073 EXPORT_SYMBOL(genl_family_attrbuf);
1074
1075 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1076                          gfp_t flags)
1077 {
1078         struct sk_buff *tmp;
1079         struct net *net, *prev = NULL;
1080         int err;
1081
1082         for_each_net_rcu(net) {
1083                 if (prev) {
1084                         tmp = skb_clone(skb, flags);
1085                         if (!tmp) {
1086                                 err = -ENOMEM;
1087                                 goto error;
1088                         }
1089                         err = nlmsg_multicast(prev->genl_sock, tmp,
1090                                               portid, group, flags);
1091                         if (err)
1092                                 goto error;
1093                 }
1094
1095                 prev = net;
1096         }
1097
1098         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1099  error:
1100         kfree_skb(skb);
1101         return err;
1102 }
1103
1104 int genlmsg_multicast_allns(const struct genl_family *family,
1105                             struct sk_buff *skb, u32 portid,
1106                             unsigned int group, gfp_t flags)
1107 {
1108         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1109                 return -EINVAL;
1110         group = family->mcgrp_offset + group;
1111         return genlmsg_mcast(skb, portid, group, flags);
1112 }
1113 EXPORT_SYMBOL(genlmsg_multicast_allns);
1114
1115 void genl_notify(const struct genl_family *family, struct sk_buff *skb,
1116                  struct genl_info *info, u32 group, gfp_t flags)
1117 {
1118         struct net *net = genl_info_net(info);
1119         struct sock *sk = net->genl_sock;
1120         int report = 0;
1121
1122         if (info->nlhdr)
1123                 report = nlmsg_report(info->nlhdr);
1124
1125         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1126                 return;
1127         group = family->mcgrp_offset + group;
1128         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1129 }
1130 EXPORT_SYMBOL(genl_notify);