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