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 atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
  27 DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
  28
  29 void genl_lock(void)
  30 {
  31         mutex_lock(&genl_mutex);
  32 }
  33 EXPORT_SYMBOL(genl_lock);
  34
  35 void genl_unlock(void)
  36 {
  37         mutex_unlock(&genl_mutex);
  38 }
  39 EXPORT_SYMBOL(genl_unlock);
  40
  41 #ifdef CONFIG_LOCKDEP
  42 bool lockdep_genl_is_held(void)
  43 {
  44         return lockdep_is_held(&genl_mutex);
  45 }
  46 EXPORT_SYMBOL(lockdep_genl_is_held);
  47 #endif
  48
  49 static void genl_lock_all(void)
  50 {
  51         down_write(&cb_lock);
  52         genl_lock();
  53 }
  54
  55 static void genl_unlock_all(void)
  56 {
  57         genl_unlock();
  58         up_write(&cb_lock);
  59 }
  60
  61 #define GENL_FAM_TAB_SIZE       16
  62 #define GENL_FAM_TAB_MASK       (GENL_FAM_TAB_SIZE - 1)
  63
  64 static struct list_head family_ht[GENL_FAM_TAB_SIZE];
  65 /*
  66  * Bitmap of multicast groups that are currently in use.
  67  *
  68  * To avoid an allocation at boot of just one unsigned long,
  69  * declare it global instead.
  70  * Bit 0 is marked as already used since group 0 is invalid.
  71  * Bit 1 is marked as already used since the drop-monitor code
  72  * abuses the API and thinks it can statically use group 1.
  73  * That group will typically conflict with other groups that
  74  * any proper users use.
  75  * Bit 16 is marked as used since it's used for generic netlink
  76  * and the code no longer marks pre-reserved IDs as used.
  77  * Bit 17 is marked as already used since the VFS quota code
  78  * also abused this API and relied on family == group ID, we
  79  * cater to that by giving it a static family and group ID.
  80  * Bit 18 is marked as already used since the PMCRAID driver
  81  * did the same thing as the VFS quota code (maybe copied?)
  82  */
  83 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) |
  84                                       BIT(GENL_ID_VFS_DQUOT) |
  85                                       BIT(GENL_ID_PMCRAID);
  86 static unsigned long *mc_groups = &mc_group_start;
  87 static unsigned long mc_groups_longs = 1;
  88
  89 static int genl_ctrl_event(int event, struct genl_family *family,
  90                            const struct genl_multicast_group *grp,
  91                            int grp_id);
  92
  93 static inline unsigned int genl_family_hash(unsigned int id)
  94 {
  95         return id & GENL_FAM_TAB_MASK;
  96 }
  97
  98 static inline struct list_head *genl_family_chain(unsigned int id)
  99 {
 100         return &family_ht[genl_family_hash(id)];
 101 }
 102
 103 static struct genl_family *genl_family_find_byid(unsigned int id)
 104 {
 105         struct genl_family *f;
 106
 107         list_for_each_entry(f, genl_family_chain(id), family_list)
 108                 if (f->id == id)
 109                         return f;
 110
 111         return NULL;
 112 }
 113
 114 static struct genl_family *genl_family_find_byname(char *name)
 115 {
 116         struct genl_family *f;
 117         int i;
 118
 119         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
 120                 list_for_each_entry(f, genl_family_chain(i), family_list)
 121                         if (strcmp(f->name, name) == 0)
 122                                 return f;
 123
 124         return NULL;
 125 }
 126
 127 static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family)
 128 {
 129         int i;
 130
 131         for (i = 0; i < family->n_ops; i++)
 132                 if (family->ops[i].cmd == cmd)
 133                         return &family->ops[i];
 134
 135         return NULL;
 136 }
 137
 138 /* Of course we are going to have problems once we hit
 139  * 2^16 alive types, but that can only happen by year 2K
 140 */
 141 static u16 genl_generate_id(void)
 142 {
 143         static u16 id_gen_idx = GENL_MIN_ID;
 144         int i;
 145
 146         for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
 147                 if (id_gen_idx != GENL_ID_VFS_DQUOT &&
 148                     id_gen_idx != GENL_ID_PMCRAID &&
 149                     !genl_family_find_byid(id_gen_idx))
 150                         return id_gen_idx;
 151                 if (++id_gen_idx > GENL_MAX_ID)
 152                         id_gen_idx = GENL_MIN_ID;
 153         }
 154
 155         return 0;
 156 }
 157
 158 static int genl_allocate_reserve_groups(int n_groups, int *first_id)
 159 {
 160         unsigned long *new_groups;
 161         int start = 0;
 162         int i;
 163         int id;
 164         bool fits;
 165
 166         do {
 167                 if (start == 0)
 168                         id = find_first_zero_bit(mc_groups,
 169                                                  mc_groups_longs *
 170                                                  BITS_PER_LONG);
 171                 else
 172                         id = find_next_zero_bit(mc_groups,
 173                                                 mc_groups_longs * BITS_PER_LONG,
 174                                                 start);
 175
 176                 fits = true;
 177                 for (i = id;
 178                      i < min_t(int, id + n_groups,
 179                                mc_groups_longs * BITS_PER_LONG);
 180                      i++) {
 181                         if (test_bit(i, mc_groups)) {
 182                                 start = i;
 183                                 fits = false;
 184                                 break;
 185                         }
 186                 }
 187
 188                 if (id + n_groups > mc_groups_longs * BITS_PER_LONG) {
 189                         unsigned long new_longs = mc_groups_longs +
 190                                                   BITS_TO_LONGS(n_groups);
 191                         size_t nlen = new_longs * sizeof(unsigned long);
 192
 193                         if (mc_groups == &mc_group_start) {
 194                                 new_groups = kzalloc(nlen, GFP_KERNEL);
 195                                 if (!new_groups)
 196                                         return -ENOMEM;
 197                                 mc_groups = new_groups;
 198                                 *mc_groups = mc_group_start;
 199                         } else {
 200                                 new_groups = krealloc(mc_groups, nlen,
 201                                                       GFP_KERNEL);
 202                                 if (!new_groups)
 203                                         return -ENOMEM;
 204                                 mc_groups = new_groups;
 205                                 for (i = 0; i < BITS_TO_LONGS(n_groups); i++)
 206                                         mc_groups[mc_groups_longs + i] = 0;
 207                         }
 208                         mc_groups_longs = new_longs;
 209                 }
 210         } while (!fits);
 211
 212         for (i = id; i < id + n_groups; i++)
 213                 set_bit(i, mc_groups);
 214         *first_id = id;
 215         return 0;
 216 }
 217
 218 static struct genl_family genl_ctrl;
 219
 220 static int genl_validate_assign_mc_groups(struct genl_family *family)
 221 {
 222         int first_id;
 223         int n_groups = family->n_mcgrps;
 224         int err = 0, i;
 225         bool groups_allocated = false;
 226
 227         if (!n_groups)
 228                 return 0;
 229
 230         for (i = 0; i < n_groups; i++) {
 231                 const struct genl_multicast_group *grp = &family->mcgrps[i];
 232
 233                 if (WARN_ON(grp->name[0] == '\0'))
 234                         return -EINVAL;
 235                 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL))
 236                         return -EINVAL;
 237         }
 238
 239         /* special-case our own group and hacks */
 240         if (family == &genl_ctrl) {
 241                 first_id = GENL_ID_CTRL;
 242                 BUG_ON(n_groups != 1);
 243         } else if (strcmp(family->name, "NET_DM") == 0) {
 244                 first_id = 1;
 245                 BUG_ON(n_groups != 1);
 246         } else if (family->id == GENL_ID_VFS_DQUOT) {
 247                 first_id = GENL_ID_VFS_DQUOT;
 248                 BUG_ON(n_groups != 1);
 249         } else if (family->id == GENL_ID_PMCRAID) {
 250                 first_id = GENL_ID_PMCRAID;
 251                 BUG_ON(n_groups != 1);
 252         } else {
 253                 groups_allocated = true;
 254                 err = genl_allocate_reserve_groups(n_groups, &first_id);
 255                 if (err)
 256                         return err;
 257         }
 258
 259         family->mcgrp_offset = first_id;
 260
 261         /* if still initializing, can't and don't need to to realloc bitmaps */
 262         if (!init_net.genl_sock)
 263                 return 0;
 264
 265         if (family->netnsok) {
 266                 struct net *net;
 267
 268                 netlink_table_grab();
 269                 rcu_read_lock();
 270                 for_each_net_rcu(net) {
 271                         err = __netlink_change_ngroups(net->genl_sock,
 272                                         mc_groups_longs * BITS_PER_LONG);
 273                         if (err) {
 274                                 /*
 275                                  * No need to roll back, can only fail if
 276                                  * memory allocation fails and then the
 277                                  * number of _possible_ groups has been
 278                                  * increased on some sockets which is ok.
 279                                  */
 280                                 break;
 281                         }
 282                 }
 283                 rcu_read_unlock();
 284                 netlink_table_ungrab();
 285         } else {
 286                 err = netlink_change_ngroups(init_net.genl_sock,
 287                                              mc_groups_longs * BITS_PER_LONG);
 288         }
 289
 290         if (groups_allocated && err) {
 291                 for (i = 0; i < family->n_mcgrps; i++)
 292                         clear_bit(family->mcgrp_offset + i, mc_groups);
 293         }
 294
 295         return err;
 296 }
 297
 298 static void genl_unregister_mc_groups(struct genl_family *family)
 299 {
 300         struct net *net;
 301         int i;
 302
 303         netlink_table_grab();
 304         rcu_read_lock();
 305         for_each_net_rcu(net) {
 306                 for (i = 0; i < family->n_mcgrps; i++)
 307                         __netlink_clear_multicast_users(
 308                                 net->genl_sock, family->mcgrp_offset + i);
 309         }
 310         rcu_read_unlock();
 311         netlink_table_ungrab();
 312
 313         for (i = 0; i < family->n_mcgrps; i++) {
 314                 int grp_id = family->mcgrp_offset + i;
 315
 316                 if (grp_id != 1)
 317                         clear_bit(grp_id, mc_groups);
 318                 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family,
 319                                 &family->mcgrps[i], grp_id);
 320         }
 321 }
 322
 323 static int genl_validate_ops(const struct genl_family *family)
 324 {
 325         const struct genl_ops *ops = family->ops;
 326         unsigned int n_ops = family->n_ops;
 327         int i, j;
 328
 329         if (WARN_ON(n_ops && !ops))
 330                 return -EINVAL;
 331
 332         if (!n_ops)
 333                 return 0;
 334
 335         for (i = 0; i < n_ops; i++) {
 336                 if (ops[i].dumpit == NULL && ops[i].doit == NULL)
 337                         return -EINVAL;
 338                 for (j = i + 1; j < n_ops; j++)
 339                         if (ops[i].cmd == ops[j].cmd)
 340                                 return -EINVAL;
 341         }
 342
 343         return 0;
 344 }
 345
 346 /**
 347  * genl_register_family - register a generic netlink family
 348  * @family: generic netlink family
 349  *
 350  * Registers the specified family after validating it first. Only one
 351  * family may be registered with the same family name or identifier.
 352  *
 353  * The family's ops, multicast groups and module pointer must already
 354  * be assigned.
 355  *
 356  * Return 0 on success or a negative error code.
 357  */
 358 int genl_register_family(struct genl_family *family)
 359 {
 360         int err, i;
 361
 362         err = genl_validate_ops(family);
 363         if (err)
 364                 return err;
 365
 366         genl_lock_all();
 367
 368         if (genl_family_find_byname(family->name)) {
 369                 err = -EEXIST;
 370                 goto errout_locked;
 371         }
 372
 373         if (family == &genl_ctrl) {
 374                 family->id = GENL_ID_CTRL;
 375         } else {
 376                 u16 newid;
 377
 378                 /* this should be left zero in the struct */
 379                 WARN_ON(family->id);
 380
 381                 /*
 382                  * Sadly, a few cases need to be special-cased
 383                  * due to them having previously abused the API
 384                  * and having used their family ID also as their
 385                  * multicast group ID, so we use reserved IDs
 386                  * for both to be sure we can do that mapping.
 387                  */
 388                 if (strcmp(family->name, "pmcraid") == 0)
 389                         newid = GENL_ID_PMCRAID;
 390                 else if (strcmp(family->name, "VFS_DQUOT") == 0)
 391                         newid = GENL_ID_VFS_DQUOT;
 392                 else
 393                         newid = genl_generate_id();
 394
 395                 if (!newid) {
 396                         err = -ENOMEM;
 397                         goto errout_locked;
 398                 }
 399
 400                 family->id = newid;
 401         }
 402
 403         if (family->maxattr && !family->parallel_ops) {
 404                 family->attrbuf = kmalloc((family->maxattr+1) *
 405                                         sizeof(struct nlattr *), GFP_KERNEL);
 406                 if (family->attrbuf == NULL) {
 407                         err = -ENOMEM;
 408                         goto errout_locked;
 409                 }
 410         } else
 411                 family->attrbuf = NULL;
 412
 413         err = genl_validate_assign_mc_groups(family);
 414         if (err)
 415                 goto errout_locked;
 416
 417         list_add_tail(&family->family_list, genl_family_chain(family->id));
 418         genl_unlock_all();
 419
 420         /* send all events */
 421         genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0);
 422         for (i = 0; i < family->n_mcgrps; i++)
 423                 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family,
 424                                 &family->mcgrps[i], family->mcgrp_offset + i);
 425
 426         return 0;
 427
 428 errout_locked:
 429         genl_unlock_all();
 430         return err;
 431 }
 432 EXPORT_SYMBOL(genl_register_family);
 433
 434 /**
 435  * genl_unregister_family - unregister generic netlink family
 436  * @family: generic netlink family
 437  *
 438  * Unregisters the specified family.
 439  *
 440  * Returns 0 on success or a negative error code.
 441  */
 442 int genl_unregister_family(struct genl_family *family)
 443 {
 444         struct genl_family *rc;
 445
 446         genl_lock_all();
 447
 448         list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 449                 if (family->id != rc->id || strcmp(rc->name, family->name))
 450                         continue;
 451
 452                 genl_unregister_mc_groups(family);
 453
 454                 list_del(&rc->family_list);
 455                 up_write(&cb_lock);
 456                 wait_event(genl_sk_destructing_waitq,
 457                            atomic_read(&genl_sk_destructing_cnt) == 0);
 458                 genl_unlock();
 459
 460                 kfree(family->attrbuf);
 461                 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
 462                 return 0;
 463         }
 464
 465         genl_unlock_all();
 466
 467         return -ENOENT;
 468 }
 469 EXPORT_SYMBOL(genl_unregister_family);
 470
 471 /**
 472  * genlmsg_put - Add generic netlink header to netlink message
 473  * @skb: socket buffer holding the message
 474  * @portid: netlink portid the message is addressed to
 475  * @seq: sequence number (usually the one of the sender)
 476  * @family: generic netlink family
 477  * @flags: netlink message flags
 478  * @cmd: generic netlink command
 479  *
 480  * Returns pointer to user specific header
 481  */
 482 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
 483                                 struct genl_family *family, int flags, u8 cmd)
 484 {
 485         struct nlmsghdr *nlh;
 486         struct genlmsghdr *hdr;
 487
 488         nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN +
 489                         family->hdrsize, flags);
 490         if (nlh == NULL)
 491                 return NULL;
 492
 493         hdr = nlmsg_data(nlh);
 494         hdr->cmd = cmd;
 495         hdr->version = family->version;
 496         hdr->reserved = 0;
 497
 498         return (char *) hdr + GENL_HDRLEN;
 499 }
 500 EXPORT_SYMBOL(genlmsg_put);
 501
 502 static int genl_lock_start(struct netlink_callback *cb)
 503 {
 504         /* our ops are always const - netlink API doesn't propagate that */
 505         const struct genl_ops *ops = cb->data;
 506         int rc = 0;
 507
 508         if (ops->start) {
 509                 genl_lock();
 510                 rc = ops->start(cb);
 511                 genl_unlock();
 512         }
 513         return rc;
 514 }
 515
 516 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 517 {
 518         /* our ops are always const - netlink API doesn't propagate that */
 519         const struct genl_ops *ops = cb->data;
 520         int rc;
 521
 522         genl_lock();
 523         rc = ops->dumpit(skb, cb);
 524         genl_unlock();
 525         return rc;
 526 }
 527
 528 static int genl_lock_done(struct netlink_callback *cb)
 529 {
 530         /* our ops are always const - netlink API doesn't propagate that */
 531         const struct genl_ops *ops = cb->data;
 532         int rc = 0;
 533
 534         if (ops->done) {
 535                 genl_lock();
 536                 rc = ops->done(cb);
 537                 genl_unlock();
 538         }
 539         return rc;
 540 }
 541
 542 static int genl_family_rcv_msg(struct genl_family *family,
 543                                struct sk_buff *skb,
 544                                struct nlmsghdr *nlh)
 545 {
 546         const struct genl_ops *ops;
 547         struct net *net = sock_net(skb->sk);
 548         struct genl_info info;
 549         struct genlmsghdr *hdr = nlmsg_data(nlh);
 550         struct nlattr **attrbuf;
 551         int hdrlen, err;
 552
 553         /* this family doesn't exist in this netns */
 554         if (!family->netnsok && !net_eq(net, &init_net))
 555                 return -ENOENT;
 556
 557         hdrlen = GENL_HDRLEN + family->hdrsize;
 558         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
 559                 return -EINVAL;
 560
 561         ops = genl_get_cmd(hdr->cmd, family);
 562         if (ops == NULL)
 563                 return -EOPNOTSUPP;
 564
 565         if ((ops->flags & GENL_ADMIN_PERM) &&
 566             !netlink_capable(skb, CAP_NET_ADMIN))
 567                 return -EPERM;
 568
 569         if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
 570             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 571                 return -EPERM;
 572
 573         if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
 574                 int rc;
 575
 576                 if (ops->dumpit == NULL)
 577                         return -EOPNOTSUPP;
 578
 579                 if (!family->parallel_ops) {
 580                         struct netlink_dump_control c = {
 581                                 .module = family->module,
 582                                 /* we have const, but the netlink API doesn't */
 583                                 .data = (void *)ops,
 584                                 .start = genl_lock_start,
 585                                 .dump = genl_lock_dumpit,
 586                                 .done = genl_lock_done,
 587                         };
 588
 589                         genl_unlock();
 590                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 591                         genl_lock();
 592
 593                 } else {
 594                         struct netlink_dump_control c = {
 595                                 .module = family->module,
 596                                 .start = ops->start,
 597                                 .dump = ops->dumpit,
 598                                 .done = ops->done,
 599                         };
 600
 601                         rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c);
 602                 }
 603
 604                 return rc;
 605         }
 606
 607         if (ops->doit == NULL)
 608                 return -EOPNOTSUPP;
 609
 610         if (family->maxattr && family->parallel_ops) {
 611                 attrbuf = kmalloc((family->maxattr+1) *
 612                                         sizeof(struct nlattr *), GFP_KERNEL);
 613                 if (attrbuf == NULL)
 614                         return -ENOMEM;
 615         } else
 616                 attrbuf = family->attrbuf;
 617
 618         if (attrbuf) {
 619                 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr,
 620                                   ops->policy);
 621                 if (err < 0)
 622                         goto out;
 623         }
 624
 625         info.snd_seq = nlh->nlmsg_seq;
 626         info.snd_portid = NETLINK_CB(skb).portid;
 627         info.nlhdr = nlh;
 628         info.genlhdr = nlmsg_data(nlh);
 629         info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN;
 630         info.attrs = attrbuf;
 631         genl_info_net_set(&info, net);
 632         memset(&info.user_ptr, 0, sizeof(info.user_ptr));
 633
 634         if (family->pre_doit) {
 635                 err = family->pre_doit(ops, skb, &info);
 636                 if (err)
 637                         goto out;
 638         }
 639
 640         err = ops->doit(skb, &info);
 641
 642         if (family->post_doit)
 643                 family->post_doit(ops, skb, &info);
 644
 645 out:
 646         if (family->parallel_ops)
 647                 kfree(attrbuf);
 648
 649         return err;
 650 }
 651
 652 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 653 {
 654         struct genl_family *family;
 655         int err;
 656
 657         family = genl_family_find_byid(nlh->nlmsg_type);
 658         if (family == NULL)
 659                 return -ENOENT;
 660
 661         if (!family->parallel_ops)
 662                 genl_lock();
 663
 664         err = genl_family_rcv_msg(family, skb, nlh);
 665
 666         if (!family->parallel_ops)
 667                 genl_unlock();
 668
 669         return err;
 670 }
 671
 672 static void genl_rcv(struct sk_buff *skb)
 673 {
 674         down_read(&cb_lock);
 675         netlink_rcv_skb(skb, &genl_rcv_msg);
 676         up_read(&cb_lock);
 677 }
 678
 679 /**************************************************************************
 680  * Controller
 681  **************************************************************************/
 682
 683 static struct genl_family genl_ctrl;
 684
 685 static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq,
 686                           u32 flags, struct sk_buff *skb, u8 cmd)
 687 {
 688         void *hdr;
 689
 690         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 691         if (hdr == NULL)
 692                 return -1;
 693
 694         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 695             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) ||
 696             nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) ||
 697             nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) ||
 698             nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
 699                 goto nla_put_failure;
 700
 701         if (family->n_ops) {
 702                 struct nlattr *nla_ops;
 703                 int i;
 704
 705                 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
 706                 if (nla_ops == NULL)
 707                         goto nla_put_failure;
 708
 709                 for (i = 0; i < family->n_ops; i++) {
 710                         struct nlattr *nest;
 711                         const struct genl_ops *ops = &family->ops[i];
 712                         u32 op_flags = ops->flags;
 713
 714                         if (ops->dumpit)
 715                                 op_flags |= GENL_CMD_CAP_DUMP;
 716                         if (ops->doit)
 717                                 op_flags |= GENL_CMD_CAP_DO;
 718                         if (ops->policy)
 719                                 op_flags |= GENL_CMD_CAP_HASPOL;
 720
 721                         nest = nla_nest_start(skb, i + 1);
 722                         if (nest == NULL)
 723                                 goto nla_put_failure;
 724
 725                         if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
 726                             nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
 727                                 goto nla_put_failure;
 728
 729                         nla_nest_end(skb, nest);
 730                 }
 731
 732                 nla_nest_end(skb, nla_ops);
 733         }
 734
 735         if (family->n_mcgrps) {
 736                 struct nlattr *nla_grps;
 737                 int i;
 738
 739                 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 740                 if (nla_grps == NULL)
 741                         goto nla_put_failure;
 742
 743                 for (i = 0; i < family->n_mcgrps; i++) {
 744                         struct nlattr *nest;
 745                         const struct genl_multicast_group *grp;
 746
 747                         grp = &family->mcgrps[i];
 748
 749                         nest = nla_nest_start(skb, i + 1);
 750                         if (nest == NULL)
 751                                 goto nla_put_failure;
 752
 753                         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID,
 754                                         family->mcgrp_offset + i) ||
 755                             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 756                                            grp->name))
 757                                 goto nla_put_failure;
 758
 759                         nla_nest_end(skb, nest);
 760                 }
 761                 nla_nest_end(skb, nla_grps);
 762         }
 763
 764         genlmsg_end(skb, hdr);
 765         return 0;
 766
 767 nla_put_failure:
 768         genlmsg_cancel(skb, hdr);
 769         return -EMSGSIZE;
 770 }
 771
 772 static int ctrl_fill_mcgrp_info(struct genl_family *family,
 773                                 const struct genl_multicast_group *grp,
 774                                 int grp_id, u32 portid, u32 seq, u32 flags,
 775                                 struct sk_buff *skb, u8 cmd)
 776 {
 777         void *hdr;
 778         struct nlattr *nla_grps;
 779         struct nlattr *nest;
 780
 781         hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
 782         if (hdr == NULL)
 783                 return -1;
 784
 785         if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) ||
 786             nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id))
 787                 goto nla_put_failure;
 788
 789         nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS);
 790         if (nla_grps == NULL)
 791                 goto nla_put_failure;
 792
 793         nest = nla_nest_start(skb, 1);
 794         if (nest == NULL)
 795                 goto nla_put_failure;
 796
 797         if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) ||
 798             nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME,
 799                            grp->name))
 800                 goto nla_put_failure;
 801
 802         nla_nest_end(skb, nest);
 803         nla_nest_end(skb, nla_grps);
 804
 805         genlmsg_end(skb, hdr);
 806         return 0;
 807
 808 nla_put_failure:
 809         genlmsg_cancel(skb, hdr);
 810         return -EMSGSIZE;
 811 }
 812
 813 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
 814 {
 815
 816         int i, n = 0;
 817         struct genl_family *rt;
 818         struct net *net = sock_net(skb->sk);
 819         int chains_to_skip = cb->args[0];
 820         int fams_to_skip = cb->args[1];
 821
 822         for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) {
 823                 n = 0;
 824                 list_for_each_entry(rt, genl_family_chain(i), family_list) {
 825                         if (!rt->netnsok && !net_eq(net, &init_net))
 826                                 continue;
 827                         if (++n < fams_to_skip)
 828                                 continue;
 829                         if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
 830                                            cb->nlh->nlmsg_seq, NLM_F_MULTI,
 831                                            skb, CTRL_CMD_NEWFAMILY) < 0)
 832                                 goto errout;
 833                 }
 834
 835                 fams_to_skip = 0;
 836         }
 837
 838 errout:
 839         cb->args[0] = i;
 840         cb->args[1] = n;
 841
 842         return skb->len;
 843 }
 844
 845 static struct sk_buff *ctrl_build_family_msg(struct genl_family *family,
 846                                              u32 portid, int seq, u8 cmd)
 847 {
 848         struct sk_buff *skb;
 849         int err;
 850
 851         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 852         if (skb == NULL)
 853                 return ERR_PTR(-ENOBUFS);
 854
 855         err = ctrl_fill_info(family, portid, seq, 0, skb, cmd);
 856         if (err < 0) {
 857                 nlmsg_free(skb);
 858                 return ERR_PTR(err);
 859         }
 860
 861         return skb;
 862 }
 863
 864 static struct sk_buff *
 865 ctrl_build_mcgrp_msg(struct genl_family *family,
 866                      const struct genl_multicast_group *grp,
 867                      int grp_id, u32 portid, int seq, u8 cmd)
 868 {
 869         struct sk_buff *skb;
 870         int err;
 871
 872         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 873         if (skb == NULL)
 874                 return ERR_PTR(-ENOBUFS);
 875
 876         err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid,
 877                                    seq, 0, skb, cmd);
 878         if (err < 0) {
 879                 nlmsg_free(skb);
 880                 return ERR_PTR(err);
 881         }
 882
 883         return skb;
 884 }
 885
 886 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = {
 887         [CTRL_ATTR_FAMILY_ID]   = { .type = NLA_U16 },
 888         [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING,
 889                                     .len = GENL_NAMSIZ - 1 },
 890 };
 891
 892 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info)
 893 {
 894         struct sk_buff *msg;
 895         struct genl_family *res = NULL;
 896         int err = -EINVAL;
 897
 898         if (info->attrs[CTRL_ATTR_FAMILY_ID]) {
 899                 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]);
 900                 res = genl_family_find_byid(id);
 901                 err = -ENOENT;
 902         }
 903
 904         if (info->attrs[CTRL_ATTR_FAMILY_NAME]) {
 905                 char *name;
 906
 907                 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]);
 908                 res = genl_family_find_byname(name);
 909 #ifdef CONFIG_MODULES
 910                 if (res == NULL) {
 911                         genl_unlock();
 912                         up_read(&cb_lock);
 913                         request_module("net-pf-%d-proto-%d-family-%s",
 914                                        PF_NETLINK, NETLINK_GENERIC, name);
 915                         down_read(&cb_lock);
 916                         genl_lock();
 917                         res = genl_family_find_byname(name);
 918                 }
 919 #endif
 920                 err = -ENOENT;
 921         }
 922
 923         if (res == NULL)
 924                 return err;
 925
 926         if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) {
 927                 /* family doesn't exist here */
 928                 return -ENOENT;
 929         }
 930
 931         msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq,
 932                                     CTRL_CMD_NEWFAMILY);
 933         if (IS_ERR(msg))
 934                 return PTR_ERR(msg);
 935
 936         return genlmsg_reply(msg, info);
 937 }
 938
 939 static int genl_ctrl_event(int event, struct genl_family *family,
 940                            const struct genl_multicast_group *grp,
 941                            int grp_id)
 942 {
 943         struct sk_buff *msg;
 944
 945         /* genl is still initialising */
 946         if (!init_net.genl_sock)
 947                 return 0;
 948
 949         switch (event) {
 950         case CTRL_CMD_NEWFAMILY:
 951         case CTRL_CMD_DELFAMILY:
 952                 WARN_ON(grp);
 953                 msg = ctrl_build_family_msg(family, 0, 0, event);
 954                 break;
 955         case CTRL_CMD_NEWMCAST_GRP:
 956         case CTRL_CMD_DELMCAST_GRP:
 957                 BUG_ON(!grp);
 958                 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event);
 959                 break;
 960         default:
 961                 return -EINVAL;
 962         }
 963
 964         if (IS_ERR(msg))
 965                 return PTR_ERR(msg);
 966
 967         if (!family->netnsok) {
 968                 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0,
 969                                         0, GFP_KERNEL);
 970         } else {
 971                 rcu_read_lock();
 972                 genlmsg_multicast_allns(&genl_ctrl, msg, 0,
 973                                         0, GFP_ATOMIC);
 974                 rcu_read_unlock();
 975         }
 976
 977         return 0;
 978 }
 979
 980 static const struct genl_ops genl_ctrl_ops[] = {
 981         {
 982                 .cmd            = CTRL_CMD_GETFAMILY,
 983                 .doit           = ctrl_getfamily,
 984                 .dumpit         = ctrl_dumpfamily,
 985                 .policy         = ctrl_policy,
 986         },
 987 };
 988
 989 static const struct genl_multicast_group genl_ctrl_groups[] = {
 990         { .name = "notify", },
 991 };
 992
 993 static struct genl_family genl_ctrl = {
 994         .module = THIS_MODULE,
 995         .ops = genl_ctrl_ops,
 996         .n_ops = ARRAY_SIZE(genl_ctrl_ops),
 997         .mcgrps = genl_ctrl_groups,
 998         .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups),
 999         .id = GENL_ID_CTRL,
1000         .name = "nlctrl",
1001         .version = 0x2,
1002         .maxattr = CTRL_ATTR_MAX,
1003         .netnsok = true,
1004 };
1005
1006 static int genl_bind(struct net *net, int group)
1007 {
1008         int i, err = -ENOENT;
1009
1010         down_read(&cb_lock);
1011         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
1012                 struct genl_family *f;
1013
1014                 list_for_each_entry(f, genl_family_chain(i), family_list) {
1015                         if (group >= f->mcgrp_offset &&
1016                             group < f->mcgrp_offset + f->n_mcgrps) {
1017                                 int fam_grp = group - f->mcgrp_offset;
1018
1019                                 if (!f->netnsok && net != &init_net)
1020                                         err = -ENOENT;
1021                                 else if (f->mcast_bind)
1022                                         err = f->mcast_bind(net, fam_grp);
1023                                 else
1024                                         err = 0;
1025                                 break;
1026                         }
1027                 }
1028         }
1029         up_read(&cb_lock);
1030
1031         return err;
1032 }
1033
1034 static void genl_unbind(struct net *net, int group)
1035 {
1036         int i;
1037
1038         down_read(&cb_lock);
1039         for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
1040                 struct genl_family *f;
1041
1042                 list_for_each_entry(f, genl_family_chain(i), family_list) {
1043                         if (group >= f->mcgrp_offset &&
1044                             group < f->mcgrp_offset + f->n_mcgrps) {
1045                                 int fam_grp = group - f->mcgrp_offset;
1046
1047                                 if (f->mcast_unbind)
1048                                         f->mcast_unbind(net, fam_grp);
1049                                 break;
1050                         }
1051                 }
1052         }
1053         up_read(&cb_lock);
1054 }
1055
1056 static int __net_init genl_pernet_init(struct net *net)
1057 {
1058         struct netlink_kernel_cfg cfg = {
1059                 .input          = genl_rcv,
1060                 .flags          = NL_CFG_F_NONROOT_RECV,
1061                 .bind           = genl_bind,
1062                 .unbind         = genl_unbind,
1063         };
1064
1065         /* we'll bump the group number right afterwards */
1066         net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg);
1067
1068         if (!net->genl_sock && net_eq(net, &init_net))
1069                 panic("GENL: Cannot initialize generic netlink\n");
1070
1071         if (!net->genl_sock)
1072                 return -ENOMEM;
1073
1074         return 0;
1075 }
1076
1077 static void __net_exit genl_pernet_exit(struct net *net)
1078 {
1079         netlink_kernel_release(net->genl_sock);
1080         net->genl_sock = NULL;
1081 }
1082
1083 static struct pernet_operations genl_pernet_ops = {
1084         .init = genl_pernet_init,
1085         .exit = genl_pernet_exit,
1086 };
1087
1088 static int __init genl_init(void)
1089 {
1090         int i, err;
1091
1092         for (i = 0; i < GENL_FAM_TAB_SIZE; i++)
1093                 INIT_LIST_HEAD(&family_ht[i]);
1094
1095         err = genl_register_family(&genl_ctrl);
1096         if (err < 0)
1097                 goto problem;
1098
1099         err = register_pernet_subsys(&genl_pernet_ops);
1100         if (err)
1101                 goto problem;
1102
1103         return 0;
1104
1105 problem:
1106         panic("GENL: Cannot register controller: %d\n", err);
1107 }
1108
1109 subsys_initcall(genl_init);
1110
1111 /**
1112  * genl_family_attrbuf - return family's attrbuf
1113  * @family: the family
1114  *
1115  * Return the family's attrbuf, while validating that it's
1116  * actually valid to access it.
1117  *
1118  * You cannot use this function with a family that has parallel_ops
1119  * and you can only use it within (pre/post) doit/dumpit callbacks.
1120  */
1121 struct nlattr **genl_family_attrbuf(struct genl_family *family)
1122 {
1123         if (!WARN_ON(family->parallel_ops))
1124                 lockdep_assert_held(&genl_mutex);
1125
1126         return family->attrbuf;
1127 }
1128 EXPORT_SYMBOL(genl_family_attrbuf);
1129
1130 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
1131                          gfp_t flags)
1132 {
1133         struct sk_buff *tmp;
1134         struct net *net, *prev = NULL;
1135         int err;
1136
1137         for_each_net_rcu(net) {
1138                 if (prev) {
1139                         tmp = skb_clone(skb, flags);
1140                         if (!tmp) {
1141                                 err = -ENOMEM;
1142                                 goto error;
1143                         }
1144                         err = nlmsg_multicast(prev->genl_sock, tmp,
1145                                               portid, group, flags);
1146                         if (err)
1147                                 goto error;
1148                 }
1149
1150                 prev = net;
1151         }
1152
1153         return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
1154  error:
1155         kfree_skb(skb);
1156         return err;
1157 }
1158
1159 int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb,
1160                             u32 portid, unsigned int group, gfp_t flags)
1161 {
1162         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1163                 return -EINVAL;
1164         group = family->mcgrp_offset + group;
1165         return genlmsg_mcast(skb, portid, group, flags);
1166 }
1167 EXPORT_SYMBOL(genlmsg_multicast_allns);
1168
1169 void genl_notify(struct genl_family *family, struct sk_buff *skb,
1170                  struct genl_info *info, u32 group, gfp_t flags)
1171 {
1172         struct net *net = genl_info_net(info);
1173         struct sock *sk = net->genl_sock;
1174         int report = 0;
1175
1176         if (info->nlhdr)
1177                 report = nlmsg_report(info->nlhdr);
1178
1179         if (WARN_ON_ONCE(group >= family->n_mcgrps))
1180                 return;
1181         group = family->mcgrp_offset + group;
1182         nlmsg_notify(sk, skb, info->snd_portid, group, report, flags);
1183 }
1184 EXPORT_SYMBOL(genl_notify);