1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * NETLINK Generic Netlink Family 4 * 5 * Authors: Jamal Hadi Salim 6 * Thomas Graf <tgraf@suug.ch> 7 * Johannes Berg <johannes@sipsolutions.net> 8 */ 9 10 #include <linux/module.h> 11 #include <linux/kernel.h> 12 #include <linux/slab.h> 13 #include <linux/errno.h> 14 #include <linux/types.h> 15 #include <linux/socket.h> 16 #include <linux/string.h> 17 #include <linux/skbuff.h> 18 #include <linux/mutex.h> 19 #include <linux/bitmap.h> 20 #include <linux/rwsem.h> 21 #include <linux/idr.h> 22 #include <net/sock.h> 23 #include <net/genetlink.h> 24 25 static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */ 26 static DECLARE_RWSEM(cb_lock); 27 28 atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0); 29 DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq); 30 31 void genl_lock(void) 32 { 33 mutex_lock(&genl_mutex); 34 } 35 EXPORT_SYMBOL(genl_lock); 36 37 void genl_unlock(void) 38 { 39 mutex_unlock(&genl_mutex); 40 } 41 EXPORT_SYMBOL(genl_unlock); 42 43 #ifdef CONFIG_LOCKDEP 44 bool lockdep_genl_is_held(void) 45 { 46 return lockdep_is_held(&genl_mutex); 47 } 48 EXPORT_SYMBOL(lockdep_genl_is_held); 49 #endif 50 51 static void genl_lock_all(void) 52 { 53 down_write(&cb_lock); 54 genl_lock(); 55 } 56 57 static void genl_unlock_all(void) 58 { 59 genl_unlock(); 60 up_write(&cb_lock); 61 } 62 63 static DEFINE_IDR(genl_fam_idr); 64 65 /* 66 * Bitmap of multicast groups that are currently in use. 67 * 68 * To avoid an allocation at boot of just one unsigned long, 69 * declare it global instead. 70 * Bit 0 is marked as already used since group 0 is invalid. 71 * Bit 1 is marked as already used since the drop-monitor code 72 * abuses the API and thinks it can statically use group 1. 73 * That group will typically conflict with other groups that 74 * any proper users use. 75 * Bit 16 is marked as used since it's used for generic netlink 76 * and the code no longer marks pre-reserved IDs as used. 77 * Bit 17 is marked as already used since the VFS quota code 78 * also abused this API and relied on family == group ID, we 79 * cater to that by giving it a static family and group ID. 80 * Bit 18 is marked as already used since the PMCRAID driver 81 * did the same thing as the VFS quota code (maybe copied?) 82 */ 83 static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) | 84 BIT(GENL_ID_VFS_DQUOT) | 85 BIT(GENL_ID_PMCRAID); 86 static unsigned long *mc_groups = &mc_group_start; 87 static unsigned long mc_groups_longs = 1; 88 89 static int genl_ctrl_event(int event, const struct genl_family *family, 90 const struct genl_multicast_group *grp, 91 int grp_id); 92 93 static const struct genl_family *genl_family_find_byid(unsigned int id) 94 { 95 return idr_find(&genl_fam_idr, id); 96 } 97 98 static const struct genl_family *genl_family_find_byname(char *name) 99 { 100 const struct genl_family *family; 101 unsigned int id; 102 103 idr_for_each_entry(&genl_fam_idr, family, id) 104 if (strcmp(family->name, name) == 0) 105 return family; 106 107 return NULL; 108 } 109 110 static const struct genl_ops *genl_get_cmd(u8 cmd, 111 const struct genl_family *family) 112 { 113 int i; 114 115 for (i = 0; i < family->n_ops; i++) 116 if (family->ops[i].cmd == cmd) 117 return &family->ops[i]; 118 119 return NULL; 120 } 121 122 static int genl_allocate_reserve_groups(int n_groups, int *first_id) 123 { 124 unsigned long *new_groups; 125 int start = 0; 126 int i; 127 int id; 128 bool fits; 129 130 do { 131 if (start == 0) 132 id = find_first_zero_bit(mc_groups, 133 mc_groups_longs * 134 BITS_PER_LONG); 135 else 136 id = find_next_zero_bit(mc_groups, 137 mc_groups_longs * BITS_PER_LONG, 138 start); 139 140 fits = true; 141 for (i = id; 142 i < min_t(int, id + n_groups, 143 mc_groups_longs * BITS_PER_LONG); 144 i++) { 145 if (test_bit(i, mc_groups)) { 146 start = i; 147 fits = false; 148 break; 149 } 150 } 151 152 if (id + n_groups > mc_groups_longs * BITS_PER_LONG) { 153 unsigned long new_longs = mc_groups_longs + 154 BITS_TO_LONGS(n_groups); 155 size_t nlen = new_longs * sizeof(unsigned long); 156 157 if (mc_groups == &mc_group_start) { 158 new_groups = kzalloc(nlen, GFP_KERNEL); 159 if (!new_groups) 160 return -ENOMEM; 161 mc_groups = new_groups; 162 *mc_groups = mc_group_start; 163 } else { 164 new_groups = krealloc(mc_groups, nlen, 165 GFP_KERNEL); 166 if (!new_groups) 167 return -ENOMEM; 168 mc_groups = new_groups; 169 for (i = 0; i < BITS_TO_LONGS(n_groups); i++) 170 mc_groups[mc_groups_longs + i] = 0; 171 } 172 mc_groups_longs = new_longs; 173 } 174 } while (!fits); 175 176 for (i = id; i < id + n_groups; i++) 177 set_bit(i, mc_groups); 178 *first_id = id; 179 return 0; 180 } 181 182 static struct genl_family genl_ctrl; 183 184 static int genl_validate_assign_mc_groups(struct genl_family *family) 185 { 186 int first_id; 187 int n_groups = family->n_mcgrps; 188 int err = 0, i; 189 bool groups_allocated = false; 190 191 if (!n_groups) 192 return 0; 193 194 for (i = 0; i < n_groups; i++) { 195 const struct genl_multicast_group *grp = &family->mcgrps[i]; 196 197 if (WARN_ON(grp->name[0] == '\0')) 198 return -EINVAL; 199 if (WARN_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL)) 200 return -EINVAL; 201 } 202 203 /* special-case our own group and hacks */ 204 if (family == &genl_ctrl) { 205 first_id = GENL_ID_CTRL; 206 BUG_ON(n_groups != 1); 207 } else if (strcmp(family->name, "NET_DM") == 0) { 208 first_id = 1; 209 BUG_ON(n_groups != 1); 210 } else if (family->id == GENL_ID_VFS_DQUOT) { 211 first_id = GENL_ID_VFS_DQUOT; 212 BUG_ON(n_groups != 1); 213 } else if (family->id == GENL_ID_PMCRAID) { 214 first_id = GENL_ID_PMCRAID; 215 BUG_ON(n_groups != 1); 216 } else { 217 groups_allocated = true; 218 err = genl_allocate_reserve_groups(n_groups, &first_id); 219 if (err) 220 return err; 221 } 222 223 family->mcgrp_offset = first_id; 224 225 /* if still initializing, can't and don't need to to realloc bitmaps */ 226 if (!init_net.genl_sock) 227 return 0; 228 229 if (family->netnsok) { 230 struct net *net; 231 232 netlink_table_grab(); 233 rcu_read_lock(); 234 for_each_net_rcu(net) { 235 err = __netlink_change_ngroups(net->genl_sock, 236 mc_groups_longs * BITS_PER_LONG); 237 if (err) { 238 /* 239 * No need to roll back, can only fail if 240 * memory allocation fails and then the 241 * number of _possible_ groups has been 242 * increased on some sockets which is ok. 243 */ 244 break; 245 } 246 } 247 rcu_read_unlock(); 248 netlink_table_ungrab(); 249 } else { 250 err = netlink_change_ngroups(init_net.genl_sock, 251 mc_groups_longs * BITS_PER_LONG); 252 } 253 254 if (groups_allocated && err) { 255 for (i = 0; i < family->n_mcgrps; i++) 256 clear_bit(family->mcgrp_offset + i, mc_groups); 257 } 258 259 return err; 260 } 261 262 static void genl_unregister_mc_groups(const struct genl_family *family) 263 { 264 struct net *net; 265 int i; 266 267 netlink_table_grab(); 268 rcu_read_lock(); 269 for_each_net_rcu(net) { 270 for (i = 0; i < family->n_mcgrps; i++) 271 __netlink_clear_multicast_users( 272 net->genl_sock, family->mcgrp_offset + i); 273 } 274 rcu_read_unlock(); 275 netlink_table_ungrab(); 276 277 for (i = 0; i < family->n_mcgrps; i++) { 278 int grp_id = family->mcgrp_offset + i; 279 280 if (grp_id != 1) 281 clear_bit(grp_id, mc_groups); 282 genl_ctrl_event(CTRL_CMD_DELMCAST_GRP, family, 283 &family->mcgrps[i], grp_id); 284 } 285 } 286 287 static int genl_validate_ops(const struct genl_family *family) 288 { 289 const struct genl_ops *ops = family->ops; 290 unsigned int n_ops = family->n_ops; 291 int i, j; 292 293 if (WARN_ON(n_ops && !ops)) 294 return -EINVAL; 295 296 if (!n_ops) 297 return 0; 298 299 for (i = 0; i < n_ops; i++) { 300 if (ops[i].dumpit == NULL && ops[i].doit == NULL) 301 return -EINVAL; 302 for (j = i + 1; j < n_ops; j++) 303 if (ops[i].cmd == ops[j].cmd) 304 return -EINVAL; 305 } 306 307 return 0; 308 } 309 310 /** 311 * genl_register_family - register a generic netlink family 312 * @family: generic netlink family 313 * 314 * Registers the specified family after validating it first. Only one 315 * family may be registered with the same family name or identifier. 316 * 317 * The family's ops, multicast groups and module pointer must already 318 * be assigned. 319 * 320 * Return 0 on success or a negative error code. 321 */ 322 int genl_register_family(struct genl_family *family) 323 { 324 int err, i; 325 int start = GENL_START_ALLOC, end = GENL_MAX_ID; 326 327 err = genl_validate_ops(family); 328 if (err) 329 return err; 330 331 genl_lock_all(); 332 333 if (genl_family_find_byname(family->name)) { 334 err = -EEXIST; 335 goto errout_locked; 336 } 337 338 /* 339 * Sadly, a few cases need to be special-cased 340 * due to them having previously abused the API 341 * and having used their family ID also as their 342 * multicast group ID, so we use reserved IDs 343 * for both to be sure we can do that mapping. 344 */ 345 if (family == &genl_ctrl) { 346 /* and this needs to be special for initial family lookups */ 347 start = end = GENL_ID_CTRL; 348 } else if (strcmp(family->name, "pmcraid") == 0) { 349 start = end = GENL_ID_PMCRAID; 350 } else if (strcmp(family->name, "VFS_DQUOT") == 0) { 351 start = end = GENL_ID_VFS_DQUOT; 352 } 353 354 if (family->maxattr && !family->parallel_ops) { 355 family->attrbuf = kmalloc_array(family->maxattr + 1, 356 sizeof(struct nlattr *), 357 GFP_KERNEL); 358 if (family->attrbuf == NULL) { 359 err = -ENOMEM; 360 goto errout_locked; 361 } 362 } else 363 family->attrbuf = NULL; 364 365 family->id = idr_alloc(&genl_fam_idr, family, 366 start, end + 1, GFP_KERNEL); 367 if (family->id < 0) { 368 err = family->id; 369 goto errout_locked; 370 } 371 372 err = genl_validate_assign_mc_groups(family); 373 if (err) 374 goto errout_remove; 375 376 genl_unlock_all(); 377 378 /* send all events */ 379 genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0); 380 for (i = 0; i < family->n_mcgrps; i++) 381 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family, 382 &family->mcgrps[i], family->mcgrp_offset + i); 383 384 return 0; 385 386 errout_remove: 387 idr_remove(&genl_fam_idr, family->id); 388 kfree(family->attrbuf); 389 errout_locked: 390 genl_unlock_all(); 391 return err; 392 } 393 EXPORT_SYMBOL(genl_register_family); 394 395 /** 396 * genl_unregister_family - unregister generic netlink family 397 * @family: generic netlink family 398 * 399 * Unregisters the specified family. 400 * 401 * Returns 0 on success or a negative error code. 402 */ 403 int genl_unregister_family(const struct genl_family *family) 404 { 405 genl_lock_all(); 406 407 if (!genl_family_find_byid(family->id)) { 408 genl_unlock_all(); 409 return -ENOENT; 410 } 411 412 genl_unregister_mc_groups(family); 413 414 idr_remove(&genl_fam_idr, family->id); 415 416 up_write(&cb_lock); 417 wait_event(genl_sk_destructing_waitq, 418 atomic_read(&genl_sk_destructing_cnt) == 0); 419 genl_unlock(); 420 421 kfree(family->attrbuf); 422 423 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0); 424 425 return 0; 426 } 427 EXPORT_SYMBOL(genl_unregister_family); 428 429 /** 430 * genlmsg_put - Add generic netlink header to netlink message 431 * @skb: socket buffer holding the message 432 * @portid: netlink portid the message is addressed to 433 * @seq: sequence number (usually the one of the sender) 434 * @family: generic netlink family 435 * @flags: netlink message flags 436 * @cmd: generic netlink command 437 * 438 * Returns pointer to user specific header 439 */ 440 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, 441 const struct genl_family *family, int flags, u8 cmd) 442 { 443 struct nlmsghdr *nlh; 444 struct genlmsghdr *hdr; 445 446 nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN + 447 family->hdrsize, flags); 448 if (nlh == NULL) 449 return NULL; 450 451 hdr = nlmsg_data(nlh); 452 hdr->cmd = cmd; 453 hdr->version = family->version; 454 hdr->reserved = 0; 455 456 return (char *) hdr + GENL_HDRLEN; 457 } 458 EXPORT_SYMBOL(genlmsg_put); 459 460 static int genl_lock_start(struct netlink_callback *cb) 461 { 462 /* our ops are always const - netlink API doesn't propagate that */ 463 const struct genl_ops *ops = cb->data; 464 int rc = 0; 465 466 if (ops->start) { 467 genl_lock(); 468 rc = ops->start(cb); 469 genl_unlock(); 470 } 471 return rc; 472 } 473 474 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb) 475 { 476 /* our ops are always const - netlink API doesn't propagate that */ 477 const struct genl_ops *ops = cb->data; 478 int rc; 479 480 genl_lock(); 481 rc = ops->dumpit(skb, cb); 482 genl_unlock(); 483 return rc; 484 } 485 486 static int genl_lock_done(struct netlink_callback *cb) 487 { 488 /* our ops are always const - netlink API doesn't propagate that */ 489 const struct genl_ops *ops = cb->data; 490 int rc = 0; 491 492 if (ops->done) { 493 genl_lock(); 494 rc = ops->done(cb); 495 genl_unlock(); 496 } 497 return rc; 498 } 499 500 static int genl_family_rcv_msg(const struct genl_family *family, 501 struct sk_buff *skb, 502 struct nlmsghdr *nlh, 503 struct netlink_ext_ack *extack) 504 { 505 const struct genl_ops *ops; 506 struct net *net = sock_net(skb->sk); 507 struct genl_info info; 508 struct genlmsghdr *hdr = nlmsg_data(nlh); 509 struct nlattr **attrbuf; 510 int hdrlen, err; 511 512 /* this family doesn't exist in this netns */ 513 if (!family->netnsok && !net_eq(net, &init_net)) 514 return -ENOENT; 515 516 hdrlen = GENL_HDRLEN + family->hdrsize; 517 if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) 518 return -EINVAL; 519 520 ops = genl_get_cmd(hdr->cmd, family); 521 if (ops == NULL) 522 return -EOPNOTSUPP; 523 524 if ((ops->flags & GENL_ADMIN_PERM) && 525 !netlink_capable(skb, CAP_NET_ADMIN)) 526 return -EPERM; 527 528 if ((ops->flags & GENL_UNS_ADMIN_PERM) && 529 !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) 530 return -EPERM; 531 532 if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) { 533 int rc; 534 535 if (ops->dumpit == NULL) 536 return -EOPNOTSUPP; 537 538 if (!family->parallel_ops) { 539 struct netlink_dump_control c = { 540 .module = family->module, 541 /* we have const, but the netlink API doesn't */ 542 .data = (void *)ops, 543 .start = genl_lock_start, 544 .dump = genl_lock_dumpit, 545 .done = genl_lock_done, 546 }; 547 548 genl_unlock(); 549 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c); 550 genl_lock(); 551 552 } else { 553 struct netlink_dump_control c = { 554 .module = family->module, 555 .start = ops->start, 556 .dump = ops->dumpit, 557 .done = ops->done, 558 }; 559 560 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c); 561 } 562 563 return rc; 564 } 565 566 if (ops->doit == NULL) 567 return -EOPNOTSUPP; 568 569 if (family->maxattr && family->parallel_ops) { 570 attrbuf = kmalloc_array(family->maxattr + 1, 571 sizeof(struct nlattr *), 572 GFP_KERNEL); 573 if (attrbuf == NULL) 574 return -ENOMEM; 575 } else 576 attrbuf = family->attrbuf; 577 578 if (attrbuf) { 579 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr, 580 ops->policy, extack); 581 if (err < 0) 582 goto out; 583 } 584 585 info.snd_seq = nlh->nlmsg_seq; 586 info.snd_portid = NETLINK_CB(skb).portid; 587 info.nlhdr = nlh; 588 info.genlhdr = nlmsg_data(nlh); 589 info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN; 590 info.attrs = attrbuf; 591 info.extack = extack; 592 genl_info_net_set(&info, net); 593 memset(&info.user_ptr, 0, sizeof(info.user_ptr)); 594 595 if (family->pre_doit) { 596 err = family->pre_doit(ops, skb, &info); 597 if (err) 598 goto out; 599 } 600 601 err = ops->doit(skb, &info); 602 603 if (family->post_doit) 604 family->post_doit(ops, skb, &info); 605 606 out: 607 if (family->parallel_ops) 608 kfree(attrbuf); 609 610 return err; 611 } 612 613 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 614 struct netlink_ext_ack *extack) 615 { 616 const struct genl_family *family; 617 int err; 618 619 family = genl_family_find_byid(nlh->nlmsg_type); 620 if (family == NULL) 621 return -ENOENT; 622 623 if (!family->parallel_ops) 624 genl_lock(); 625 626 err = genl_family_rcv_msg(family, skb, nlh, extack); 627 628 if (!family->parallel_ops) 629 genl_unlock(); 630 631 return err; 632 } 633 634 static void genl_rcv(struct sk_buff *skb) 635 { 636 down_read(&cb_lock); 637 netlink_rcv_skb(skb, &genl_rcv_msg); 638 up_read(&cb_lock); 639 } 640 641 /************************************************************************** 642 * Controller 643 **************************************************************************/ 644 645 static struct genl_family genl_ctrl; 646 647 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq, 648 u32 flags, struct sk_buff *skb, u8 cmd) 649 { 650 void *hdr; 651 652 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); 653 if (hdr == NULL) 654 return -1; 655 656 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) || 657 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) || 658 nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) || 659 nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) || 660 nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr)) 661 goto nla_put_failure; 662 663 if (family->n_ops) { 664 struct nlattr *nla_ops; 665 int i; 666 667 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS); 668 if (nla_ops == NULL) 669 goto nla_put_failure; 670 671 for (i = 0; i < family->n_ops; i++) { 672 struct nlattr *nest; 673 const struct genl_ops *ops = &family->ops[i]; 674 u32 op_flags = ops->flags; 675 676 if (ops->dumpit) 677 op_flags |= GENL_CMD_CAP_DUMP; 678 if (ops->doit) 679 op_flags |= GENL_CMD_CAP_DO; 680 if (ops->policy) 681 op_flags |= GENL_CMD_CAP_HASPOL; 682 683 nest = nla_nest_start(skb, i + 1); 684 if (nest == NULL) 685 goto nla_put_failure; 686 687 if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) || 688 nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags)) 689 goto nla_put_failure; 690 691 nla_nest_end(skb, nest); 692 } 693 694 nla_nest_end(skb, nla_ops); 695 } 696 697 if (family->n_mcgrps) { 698 struct nlattr *nla_grps; 699 int i; 700 701 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS); 702 if (nla_grps == NULL) 703 goto nla_put_failure; 704 705 for (i = 0; i < family->n_mcgrps; i++) { 706 struct nlattr *nest; 707 const struct genl_multicast_group *grp; 708 709 grp = &family->mcgrps[i]; 710 711 nest = nla_nest_start(skb, i + 1); 712 if (nest == NULL) 713 goto nla_put_failure; 714 715 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, 716 family->mcgrp_offset + i) || 717 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, 718 grp->name)) 719 goto nla_put_failure; 720 721 nla_nest_end(skb, nest); 722 } 723 nla_nest_end(skb, nla_grps); 724 } 725 726 genlmsg_end(skb, hdr); 727 return 0; 728 729 nla_put_failure: 730 genlmsg_cancel(skb, hdr); 731 return -EMSGSIZE; 732 } 733 734 static int ctrl_fill_mcgrp_info(const struct genl_family *family, 735 const struct genl_multicast_group *grp, 736 int grp_id, u32 portid, u32 seq, u32 flags, 737 struct sk_buff *skb, u8 cmd) 738 { 739 void *hdr; 740 struct nlattr *nla_grps; 741 struct nlattr *nest; 742 743 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); 744 if (hdr == NULL) 745 return -1; 746 747 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) || 748 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id)) 749 goto nla_put_failure; 750 751 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS); 752 if (nla_grps == NULL) 753 goto nla_put_failure; 754 755 nest = nla_nest_start(skb, 1); 756 if (nest == NULL) 757 goto nla_put_failure; 758 759 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) || 760 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, 761 grp->name)) 762 goto nla_put_failure; 763 764 nla_nest_end(skb, nest); 765 nla_nest_end(skb, nla_grps); 766 767 genlmsg_end(skb, hdr); 768 return 0; 769 770 nla_put_failure: 771 genlmsg_cancel(skb, hdr); 772 return -EMSGSIZE; 773 } 774 775 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) 776 { 777 int n = 0; 778 struct genl_family *rt; 779 struct net *net = sock_net(skb->sk); 780 int fams_to_skip = cb->args[0]; 781 unsigned int id; 782 783 idr_for_each_entry(&genl_fam_idr, rt, id) { 784 if (!rt->netnsok && !net_eq(net, &init_net)) 785 continue; 786 787 if (n++ < fams_to_skip) 788 continue; 789 790 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid, 791 cb->nlh->nlmsg_seq, NLM_F_MULTI, 792 skb, CTRL_CMD_NEWFAMILY) < 0) { 793 n--; 794 break; 795 } 796 } 797 798 cb->args[0] = n; 799 return skb->len; 800 } 801 802 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family, 803 u32 portid, int seq, u8 cmd) 804 { 805 struct sk_buff *skb; 806 int err; 807 808 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 809 if (skb == NULL) 810 return ERR_PTR(-ENOBUFS); 811 812 err = ctrl_fill_info(family, portid, seq, 0, skb, cmd); 813 if (err < 0) { 814 nlmsg_free(skb); 815 return ERR_PTR(err); 816 } 817 818 return skb; 819 } 820 821 static struct sk_buff * 822 ctrl_build_mcgrp_msg(const struct genl_family *family, 823 const struct genl_multicast_group *grp, 824 int grp_id, u32 portid, int seq, u8 cmd) 825 { 826 struct sk_buff *skb; 827 int err; 828 829 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 830 if (skb == NULL) 831 return ERR_PTR(-ENOBUFS); 832 833 err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid, 834 seq, 0, skb, cmd); 835 if (err < 0) { 836 nlmsg_free(skb); 837 return ERR_PTR(err); 838 } 839 840 return skb; 841 } 842 843 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = { 844 [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 }, 845 [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING, 846 .len = GENL_NAMSIZ - 1 }, 847 }; 848 849 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info) 850 { 851 struct sk_buff *msg; 852 const struct genl_family *res = NULL; 853 int err = -EINVAL; 854 855 if (info->attrs[CTRL_ATTR_FAMILY_ID]) { 856 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]); 857 res = genl_family_find_byid(id); 858 err = -ENOENT; 859 } 860 861 if (info->attrs[CTRL_ATTR_FAMILY_NAME]) { 862 char *name; 863 864 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]); 865 res = genl_family_find_byname(name); 866 #ifdef CONFIG_MODULES 867 if (res == NULL) { 868 genl_unlock(); 869 up_read(&cb_lock); 870 request_module("net-pf-%d-proto-%d-family-%s", 871 PF_NETLINK, NETLINK_GENERIC, name); 872 down_read(&cb_lock); 873 genl_lock(); 874 res = genl_family_find_byname(name); 875 } 876 #endif 877 err = -ENOENT; 878 } 879 880 if (res == NULL) 881 return err; 882 883 if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) { 884 /* family doesn't exist here */ 885 return -ENOENT; 886 } 887 888 msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq, 889 CTRL_CMD_NEWFAMILY); 890 if (IS_ERR(msg)) 891 return PTR_ERR(msg); 892 893 return genlmsg_reply(msg, info); 894 } 895 896 static int genl_ctrl_event(int event, const struct genl_family *family, 897 const struct genl_multicast_group *grp, 898 int grp_id) 899 { 900 struct sk_buff *msg; 901 902 /* genl is still initialising */ 903 if (!init_net.genl_sock) 904 return 0; 905 906 switch (event) { 907 case CTRL_CMD_NEWFAMILY: 908 case CTRL_CMD_DELFAMILY: 909 WARN_ON(grp); 910 msg = ctrl_build_family_msg(family, 0, 0, event); 911 break; 912 case CTRL_CMD_NEWMCAST_GRP: 913 case CTRL_CMD_DELMCAST_GRP: 914 BUG_ON(!grp); 915 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event); 916 break; 917 default: 918 return -EINVAL; 919 } 920 921 if (IS_ERR(msg)) 922 return PTR_ERR(msg); 923 924 if (!family->netnsok) { 925 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0, 926 0, GFP_KERNEL); 927 } else { 928 rcu_read_lock(); 929 genlmsg_multicast_allns(&genl_ctrl, msg, 0, 930 0, GFP_ATOMIC); 931 rcu_read_unlock(); 932 } 933 934 return 0; 935 } 936 937 static const struct genl_ops genl_ctrl_ops[] = { 938 { 939 .cmd = CTRL_CMD_GETFAMILY, 940 .doit = ctrl_getfamily, 941 .dumpit = ctrl_dumpfamily, 942 .policy = ctrl_policy, 943 }, 944 }; 945 946 static const struct genl_multicast_group genl_ctrl_groups[] = { 947 { .name = "notify", }, 948 }; 949 950 static struct genl_family genl_ctrl __ro_after_init = { 951 .module = THIS_MODULE, 952 .ops = genl_ctrl_ops, 953 .n_ops = ARRAY_SIZE(genl_ctrl_ops), 954 .mcgrps = genl_ctrl_groups, 955 .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups), 956 .id = GENL_ID_CTRL, 957 .name = "nlctrl", 958 .version = 0x2, 959 .maxattr = CTRL_ATTR_MAX, 960 .netnsok = true, 961 }; 962 963 static int genl_bind(struct net *net, int group) 964 { 965 struct genl_family *f; 966 int err = -ENOENT; 967 unsigned int id; 968 969 down_read(&cb_lock); 970 971 idr_for_each_entry(&genl_fam_idr, f, id) { 972 if (group >= f->mcgrp_offset && 973 group < f->mcgrp_offset + f->n_mcgrps) { 974 int fam_grp = group - f->mcgrp_offset; 975 976 if (!f->netnsok && net != &init_net) 977 err = -ENOENT; 978 else if (f->mcast_bind) 979 err = f->mcast_bind(net, fam_grp); 980 else 981 err = 0; 982 break; 983 } 984 } 985 up_read(&cb_lock); 986 987 return err; 988 } 989 990 static void genl_unbind(struct net *net, int group) 991 { 992 struct genl_family *f; 993 unsigned int id; 994 995 down_read(&cb_lock); 996 997 idr_for_each_entry(&genl_fam_idr, f, id) { 998 if (group >= f->mcgrp_offset && 999 group < f->mcgrp_offset + f->n_mcgrps) { 1000 int fam_grp = group - f->mcgrp_offset; 1001 1002 if (f->mcast_unbind) 1003 f->mcast_unbind(net, fam_grp); 1004 break; 1005 } 1006 } 1007 up_read(&cb_lock); 1008 } 1009 1010 static int __net_init genl_pernet_init(struct net *net) 1011 { 1012 struct netlink_kernel_cfg cfg = { 1013 .input = genl_rcv, 1014 .flags = NL_CFG_F_NONROOT_RECV, 1015 .bind = genl_bind, 1016 .unbind = genl_unbind, 1017 }; 1018 1019 /* we'll bump the group number right afterwards */ 1020 net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg); 1021 1022 if (!net->genl_sock && net_eq(net, &init_net)) 1023 panic("GENL: Cannot initialize generic netlink\n"); 1024 1025 if (!net->genl_sock) 1026 return -ENOMEM; 1027 1028 return 0; 1029 } 1030 1031 static void __net_exit genl_pernet_exit(struct net *net) 1032 { 1033 netlink_kernel_release(net->genl_sock); 1034 net->genl_sock = NULL; 1035 } 1036 1037 static struct pernet_operations genl_pernet_ops = { 1038 .init = genl_pernet_init, 1039 .exit = genl_pernet_exit, 1040 }; 1041 1042 static int __init genl_init(void) 1043 { 1044 int err; 1045 1046 err = genl_register_family(&genl_ctrl); 1047 if (err < 0) 1048 goto problem; 1049 1050 err = register_pernet_subsys(&genl_pernet_ops); 1051 if (err) 1052 goto problem; 1053 1054 return 0; 1055 1056 problem: 1057 panic("GENL: Cannot register controller: %d\n", err); 1058 } 1059 1060 subsys_initcall(genl_init); 1061 1062 /** 1063 * genl_family_attrbuf - return family's attrbuf 1064 * @family: the family 1065 * 1066 * Return the family's attrbuf, while validating that it's 1067 * actually valid to access it. 1068 * 1069 * You cannot use this function with a family that has parallel_ops 1070 * and you can only use it within (pre/post) doit/dumpit callbacks. 1071 */ 1072 struct nlattr **genl_family_attrbuf(const struct genl_family *family) 1073 { 1074 if (!WARN_ON(family->parallel_ops)) 1075 lockdep_assert_held(&genl_mutex); 1076 1077 return family->attrbuf; 1078 } 1079 EXPORT_SYMBOL(genl_family_attrbuf); 1080 1081 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group, 1082 gfp_t flags) 1083 { 1084 struct sk_buff *tmp; 1085 struct net *net, *prev = NULL; 1086 bool delivered = false; 1087 int err; 1088 1089 for_each_net_rcu(net) { 1090 if (prev) { 1091 tmp = skb_clone(skb, flags); 1092 if (!tmp) { 1093 err = -ENOMEM; 1094 goto error; 1095 } 1096 err = nlmsg_multicast(prev->genl_sock, tmp, 1097 portid, group, flags); 1098 if (!err) 1099 delivered = true; 1100 else if (err != -ESRCH) 1101 goto error; 1102 } 1103 1104 prev = net; 1105 } 1106 1107 err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags); 1108 if (!err) 1109 delivered = true; 1110 else if (err != -ESRCH) 1111 return err; 1112 return delivered ? 0 : -ESRCH; 1113 error: 1114 kfree_skb(skb); 1115 return err; 1116 } 1117 1118 int genlmsg_multicast_allns(const struct genl_family *family, 1119 struct sk_buff *skb, u32 portid, 1120 unsigned int group, gfp_t flags) 1121 { 1122 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 1123 return -EINVAL; 1124 group = family->mcgrp_offset + group; 1125 return genlmsg_mcast(skb, portid, group, flags); 1126 } 1127 EXPORT_SYMBOL(genlmsg_multicast_allns); 1128 1129 void genl_notify(const struct genl_family *family, struct sk_buff *skb, 1130 struct genl_info *info, u32 group, gfp_t flags) 1131 { 1132 struct net *net = genl_info_net(info); 1133 struct sock *sk = net->genl_sock; 1134 int report = 0; 1135 1136 if (info->nlhdr) 1137 report = nlmsg_report(info->nlhdr); 1138 1139 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 1140 return; 1141 group = family->mcgrp_offset + group; 1142 nlmsg_notify(sk, skb, info->snd_portid, group, report, flags); 1143 } 1144 EXPORT_SYMBOL(genl_notify); 1145