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_free; 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 errout_free: 389 kfree(family->attrbuf); 390 errout_locked: 391 genl_unlock_all(); 392 return err; 393 } 394 EXPORT_SYMBOL(genl_register_family); 395 396 /** 397 * genl_unregister_family - unregister generic netlink family 398 * @family: generic netlink family 399 * 400 * Unregisters the specified family. 401 * 402 * Returns 0 on success or a negative error code. 403 */ 404 int genl_unregister_family(const struct genl_family *family) 405 { 406 genl_lock_all(); 407 408 if (!genl_family_find_byid(family->id)) { 409 genl_unlock_all(); 410 return -ENOENT; 411 } 412 413 genl_unregister_mc_groups(family); 414 415 idr_remove(&genl_fam_idr, family->id); 416 417 up_write(&cb_lock); 418 wait_event(genl_sk_destructing_waitq, 419 atomic_read(&genl_sk_destructing_cnt) == 0); 420 genl_unlock(); 421 422 kfree(family->attrbuf); 423 424 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0); 425 426 return 0; 427 } 428 EXPORT_SYMBOL(genl_unregister_family); 429 430 /** 431 * genlmsg_put - Add generic netlink header to netlink message 432 * @skb: socket buffer holding the message 433 * @portid: netlink portid the message is addressed to 434 * @seq: sequence number (usually the one of the sender) 435 * @family: generic netlink family 436 * @flags: netlink message flags 437 * @cmd: generic netlink command 438 * 439 * Returns pointer to user specific header 440 */ 441 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, 442 const struct genl_family *family, int flags, u8 cmd) 443 { 444 struct nlmsghdr *nlh; 445 struct genlmsghdr *hdr; 446 447 nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN + 448 family->hdrsize, flags); 449 if (nlh == NULL) 450 return NULL; 451 452 hdr = nlmsg_data(nlh); 453 hdr->cmd = cmd; 454 hdr->version = family->version; 455 hdr->reserved = 0; 456 457 return (char *) hdr + GENL_HDRLEN; 458 } 459 EXPORT_SYMBOL(genlmsg_put); 460 461 static int genl_lock_start(struct netlink_callback *cb) 462 { 463 /* our ops are always const - netlink API doesn't propagate that */ 464 const struct genl_ops *ops = cb->data; 465 int rc = 0; 466 467 if (ops->start) { 468 genl_lock(); 469 rc = ops->start(cb); 470 genl_unlock(); 471 } 472 return rc; 473 } 474 475 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb) 476 { 477 /* our ops are always const - netlink API doesn't propagate that */ 478 const struct genl_ops *ops = cb->data; 479 int rc; 480 481 genl_lock(); 482 rc = ops->dumpit(skb, cb); 483 genl_unlock(); 484 return rc; 485 } 486 487 static int genl_lock_done(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 = 0; 492 493 if (ops->done) { 494 genl_lock(); 495 rc = ops->done(cb); 496 genl_unlock(); 497 } 498 return rc; 499 } 500 501 static int genl_family_rcv_msg(const struct genl_family *family, 502 struct sk_buff *skb, 503 struct nlmsghdr *nlh, 504 struct netlink_ext_ack *extack) 505 { 506 const struct genl_ops *ops; 507 struct net *net = sock_net(skb->sk); 508 struct genl_info info; 509 struct genlmsghdr *hdr = nlmsg_data(nlh); 510 struct nlattr **attrbuf; 511 int hdrlen, err; 512 513 /* this family doesn't exist in this netns */ 514 if (!family->netnsok && !net_eq(net, &init_net)) 515 return -ENOENT; 516 517 hdrlen = GENL_HDRLEN + family->hdrsize; 518 if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) 519 return -EINVAL; 520 521 ops = genl_get_cmd(hdr->cmd, family); 522 if (ops == NULL) 523 return -EOPNOTSUPP; 524 525 if ((ops->flags & GENL_ADMIN_PERM) && 526 !netlink_capable(skb, CAP_NET_ADMIN)) 527 return -EPERM; 528 529 if ((ops->flags & GENL_UNS_ADMIN_PERM) && 530 !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) 531 return -EPERM; 532 533 if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) { 534 int rc; 535 536 if (ops->dumpit == NULL) 537 return -EOPNOTSUPP; 538 539 if (!family->parallel_ops) { 540 struct netlink_dump_control c = { 541 .module = family->module, 542 /* we have const, but the netlink API doesn't */ 543 .data = (void *)ops, 544 .start = genl_lock_start, 545 .dump = genl_lock_dumpit, 546 .done = genl_lock_done, 547 }; 548 549 genl_unlock(); 550 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c); 551 genl_lock(); 552 553 } else { 554 struct netlink_dump_control c = { 555 .module = family->module, 556 .start = ops->start, 557 .dump = ops->dumpit, 558 .done = ops->done, 559 }; 560 561 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c); 562 } 563 564 return rc; 565 } 566 567 if (ops->doit == NULL) 568 return -EOPNOTSUPP; 569 570 if (family->maxattr && family->parallel_ops) { 571 attrbuf = kmalloc_array(family->maxattr + 1, 572 sizeof(struct nlattr *), 573 GFP_KERNEL); 574 if (attrbuf == NULL) 575 return -ENOMEM; 576 } else 577 attrbuf = family->attrbuf; 578 579 if (attrbuf) { 580 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr, 581 ops->policy, extack); 582 if (err < 0) 583 goto out; 584 } 585 586 info.snd_seq = nlh->nlmsg_seq; 587 info.snd_portid = NETLINK_CB(skb).portid; 588 info.nlhdr = nlh; 589 info.genlhdr = nlmsg_data(nlh); 590 info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN; 591 info.attrs = attrbuf; 592 info.extack = extack; 593 genl_info_net_set(&info, net); 594 memset(&info.user_ptr, 0, sizeof(info.user_ptr)); 595 596 if (family->pre_doit) { 597 err = family->pre_doit(ops, skb, &info); 598 if (err) 599 goto out; 600 } 601 602 err = ops->doit(skb, &info); 603 604 if (family->post_doit) 605 family->post_doit(ops, skb, &info); 606 607 out: 608 if (family->parallel_ops) 609 kfree(attrbuf); 610 611 return err; 612 } 613 614 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 615 struct netlink_ext_ack *extack) 616 { 617 const struct genl_family *family; 618 int err; 619 620 family = genl_family_find_byid(nlh->nlmsg_type); 621 if (family == NULL) 622 return -ENOENT; 623 624 if (!family->parallel_ops) 625 genl_lock(); 626 627 err = genl_family_rcv_msg(family, skb, nlh, extack); 628 629 if (!family->parallel_ops) 630 genl_unlock(); 631 632 return err; 633 } 634 635 static void genl_rcv(struct sk_buff *skb) 636 { 637 down_read(&cb_lock); 638 netlink_rcv_skb(skb, &genl_rcv_msg); 639 up_read(&cb_lock); 640 } 641 642 /************************************************************************** 643 * Controller 644 **************************************************************************/ 645 646 static struct genl_family genl_ctrl; 647 648 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq, 649 u32 flags, struct sk_buff *skb, u8 cmd) 650 { 651 void *hdr; 652 653 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); 654 if (hdr == NULL) 655 return -1; 656 657 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) || 658 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) || 659 nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) || 660 nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) || 661 nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr)) 662 goto nla_put_failure; 663 664 if (family->n_ops) { 665 struct nlattr *nla_ops; 666 int i; 667 668 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS); 669 if (nla_ops == NULL) 670 goto nla_put_failure; 671 672 for (i = 0; i < family->n_ops; i++) { 673 struct nlattr *nest; 674 const struct genl_ops *ops = &family->ops[i]; 675 u32 op_flags = ops->flags; 676 677 if (ops->dumpit) 678 op_flags |= GENL_CMD_CAP_DUMP; 679 if (ops->doit) 680 op_flags |= GENL_CMD_CAP_DO; 681 if (ops->policy) 682 op_flags |= GENL_CMD_CAP_HASPOL; 683 684 nest = nla_nest_start(skb, i + 1); 685 if (nest == NULL) 686 goto nla_put_failure; 687 688 if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) || 689 nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags)) 690 goto nla_put_failure; 691 692 nla_nest_end(skb, nest); 693 } 694 695 nla_nest_end(skb, nla_ops); 696 } 697 698 if (family->n_mcgrps) { 699 struct nlattr *nla_grps; 700 int i; 701 702 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS); 703 if (nla_grps == NULL) 704 goto nla_put_failure; 705 706 for (i = 0; i < family->n_mcgrps; i++) { 707 struct nlattr *nest; 708 const struct genl_multicast_group *grp; 709 710 grp = &family->mcgrps[i]; 711 712 nest = nla_nest_start(skb, i + 1); 713 if (nest == NULL) 714 goto nla_put_failure; 715 716 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, 717 family->mcgrp_offset + i) || 718 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, 719 grp->name)) 720 goto nla_put_failure; 721 722 nla_nest_end(skb, nest); 723 } 724 nla_nest_end(skb, nla_grps); 725 } 726 727 genlmsg_end(skb, hdr); 728 return 0; 729 730 nla_put_failure: 731 genlmsg_cancel(skb, hdr); 732 return -EMSGSIZE; 733 } 734 735 static int ctrl_fill_mcgrp_info(const struct genl_family *family, 736 const struct genl_multicast_group *grp, 737 int grp_id, u32 portid, u32 seq, u32 flags, 738 struct sk_buff *skb, u8 cmd) 739 { 740 void *hdr; 741 struct nlattr *nla_grps; 742 struct nlattr *nest; 743 744 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); 745 if (hdr == NULL) 746 return -1; 747 748 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) || 749 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id)) 750 goto nla_put_failure; 751 752 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS); 753 if (nla_grps == NULL) 754 goto nla_put_failure; 755 756 nest = nla_nest_start(skb, 1); 757 if (nest == NULL) 758 goto nla_put_failure; 759 760 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) || 761 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, 762 grp->name)) 763 goto nla_put_failure; 764 765 nla_nest_end(skb, nest); 766 nla_nest_end(skb, nla_grps); 767 768 genlmsg_end(skb, hdr); 769 return 0; 770 771 nla_put_failure: 772 genlmsg_cancel(skb, hdr); 773 return -EMSGSIZE; 774 } 775 776 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) 777 { 778 int n = 0; 779 struct genl_family *rt; 780 struct net *net = sock_net(skb->sk); 781 int fams_to_skip = cb->args[0]; 782 unsigned int id; 783 784 idr_for_each_entry(&genl_fam_idr, rt, id) { 785 if (!rt->netnsok && !net_eq(net, &init_net)) 786 continue; 787 788 if (n++ < fams_to_skip) 789 continue; 790 791 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid, 792 cb->nlh->nlmsg_seq, NLM_F_MULTI, 793 skb, CTRL_CMD_NEWFAMILY) < 0) { 794 n--; 795 break; 796 } 797 } 798 799 cb->args[0] = n; 800 return skb->len; 801 } 802 803 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family, 804 u32 portid, int seq, u8 cmd) 805 { 806 struct sk_buff *skb; 807 int err; 808 809 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 810 if (skb == NULL) 811 return ERR_PTR(-ENOBUFS); 812 813 err = ctrl_fill_info(family, portid, seq, 0, skb, cmd); 814 if (err < 0) { 815 nlmsg_free(skb); 816 return ERR_PTR(err); 817 } 818 819 return skb; 820 } 821 822 static struct sk_buff * 823 ctrl_build_mcgrp_msg(const struct genl_family *family, 824 const struct genl_multicast_group *grp, 825 int grp_id, u32 portid, int seq, u8 cmd) 826 { 827 struct sk_buff *skb; 828 int err; 829 830 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 831 if (skb == NULL) 832 return ERR_PTR(-ENOBUFS); 833 834 err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid, 835 seq, 0, skb, cmd); 836 if (err < 0) { 837 nlmsg_free(skb); 838 return ERR_PTR(err); 839 } 840 841 return skb; 842 } 843 844 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = { 845 [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 }, 846 [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING, 847 .len = GENL_NAMSIZ - 1 }, 848 }; 849 850 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info) 851 { 852 struct sk_buff *msg; 853 const struct genl_family *res = NULL; 854 int err = -EINVAL; 855 856 if (info->attrs[CTRL_ATTR_FAMILY_ID]) { 857 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]); 858 res = genl_family_find_byid(id); 859 err = -ENOENT; 860 } 861 862 if (info->attrs[CTRL_ATTR_FAMILY_NAME]) { 863 char *name; 864 865 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]); 866 res = genl_family_find_byname(name); 867 #ifdef CONFIG_MODULES 868 if (res == NULL) { 869 genl_unlock(); 870 up_read(&cb_lock); 871 request_module("net-pf-%d-proto-%d-family-%s", 872 PF_NETLINK, NETLINK_GENERIC, name); 873 down_read(&cb_lock); 874 genl_lock(); 875 res = genl_family_find_byname(name); 876 } 877 #endif 878 err = -ENOENT; 879 } 880 881 if (res == NULL) 882 return err; 883 884 if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) { 885 /* family doesn't exist here */ 886 return -ENOENT; 887 } 888 889 msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq, 890 CTRL_CMD_NEWFAMILY); 891 if (IS_ERR(msg)) 892 return PTR_ERR(msg); 893 894 return genlmsg_reply(msg, info); 895 } 896 897 static int genl_ctrl_event(int event, const struct genl_family *family, 898 const struct genl_multicast_group *grp, 899 int grp_id) 900 { 901 struct sk_buff *msg; 902 903 /* genl is still initialising */ 904 if (!init_net.genl_sock) 905 return 0; 906 907 switch (event) { 908 case CTRL_CMD_NEWFAMILY: 909 case CTRL_CMD_DELFAMILY: 910 WARN_ON(grp); 911 msg = ctrl_build_family_msg(family, 0, 0, event); 912 break; 913 case CTRL_CMD_NEWMCAST_GRP: 914 case CTRL_CMD_DELMCAST_GRP: 915 BUG_ON(!grp); 916 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event); 917 break; 918 default: 919 return -EINVAL; 920 } 921 922 if (IS_ERR(msg)) 923 return PTR_ERR(msg); 924 925 if (!family->netnsok) { 926 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0, 927 0, GFP_KERNEL); 928 } else { 929 rcu_read_lock(); 930 genlmsg_multicast_allns(&genl_ctrl, msg, 0, 931 0, GFP_ATOMIC); 932 rcu_read_unlock(); 933 } 934 935 return 0; 936 } 937 938 static const struct genl_ops genl_ctrl_ops[] = { 939 { 940 .cmd = CTRL_CMD_GETFAMILY, 941 .doit = ctrl_getfamily, 942 .dumpit = ctrl_dumpfamily, 943 .policy = ctrl_policy, 944 }, 945 }; 946 947 static const struct genl_multicast_group genl_ctrl_groups[] = { 948 { .name = "notify", }, 949 }; 950 951 static struct genl_family genl_ctrl __ro_after_init = { 952 .module = THIS_MODULE, 953 .ops = genl_ctrl_ops, 954 .n_ops = ARRAY_SIZE(genl_ctrl_ops), 955 .mcgrps = genl_ctrl_groups, 956 .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups), 957 .id = GENL_ID_CTRL, 958 .name = "nlctrl", 959 .version = 0x2, 960 .maxattr = CTRL_ATTR_MAX, 961 .netnsok = true, 962 }; 963 964 static int genl_bind(struct net *net, int group) 965 { 966 struct genl_family *f; 967 int err = -ENOENT; 968 unsigned int id; 969 970 down_read(&cb_lock); 971 972 idr_for_each_entry(&genl_fam_idr, f, id) { 973 if (group >= f->mcgrp_offset && 974 group < f->mcgrp_offset + f->n_mcgrps) { 975 int fam_grp = group - f->mcgrp_offset; 976 977 if (!f->netnsok && net != &init_net) 978 err = -ENOENT; 979 else if (f->mcast_bind) 980 err = f->mcast_bind(net, fam_grp); 981 else 982 err = 0; 983 break; 984 } 985 } 986 up_read(&cb_lock); 987 988 return err; 989 } 990 991 static void genl_unbind(struct net *net, int group) 992 { 993 struct genl_family *f; 994 unsigned int id; 995 996 down_read(&cb_lock); 997 998 idr_for_each_entry(&genl_fam_idr, f, id) { 999 if (group >= f->mcgrp_offset && 1000 group < f->mcgrp_offset + f->n_mcgrps) { 1001 int fam_grp = group - f->mcgrp_offset; 1002 1003 if (f->mcast_unbind) 1004 f->mcast_unbind(net, fam_grp); 1005 break; 1006 } 1007 } 1008 up_read(&cb_lock); 1009 } 1010 1011 static int __net_init genl_pernet_init(struct net *net) 1012 { 1013 struct netlink_kernel_cfg cfg = { 1014 .input = genl_rcv, 1015 .flags = NL_CFG_F_NONROOT_RECV, 1016 .bind = genl_bind, 1017 .unbind = genl_unbind, 1018 }; 1019 1020 /* we'll bump the group number right afterwards */ 1021 net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg); 1022 1023 if (!net->genl_sock && net_eq(net, &init_net)) 1024 panic("GENL: Cannot initialize generic netlink\n"); 1025 1026 if (!net->genl_sock) 1027 return -ENOMEM; 1028 1029 return 0; 1030 } 1031 1032 static void __net_exit genl_pernet_exit(struct net *net) 1033 { 1034 netlink_kernel_release(net->genl_sock); 1035 net->genl_sock = NULL; 1036 } 1037 1038 static struct pernet_operations genl_pernet_ops = { 1039 .init = genl_pernet_init, 1040 .exit = genl_pernet_exit, 1041 }; 1042 1043 static int __init genl_init(void) 1044 { 1045 int err; 1046 1047 err = genl_register_family(&genl_ctrl); 1048 if (err < 0) 1049 goto problem; 1050 1051 err = register_pernet_subsys(&genl_pernet_ops); 1052 if (err) 1053 goto problem; 1054 1055 return 0; 1056 1057 problem: 1058 panic("GENL: Cannot register controller: %d\n", err); 1059 } 1060 1061 subsys_initcall(genl_init); 1062 1063 /** 1064 * genl_family_attrbuf - return family's attrbuf 1065 * @family: the family 1066 * 1067 * Return the family's attrbuf, while validating that it's 1068 * actually valid to access it. 1069 * 1070 * You cannot use this function with a family that has parallel_ops 1071 * and you can only use it within (pre/post) doit/dumpit callbacks. 1072 */ 1073 struct nlattr **genl_family_attrbuf(const struct genl_family *family) 1074 { 1075 if (!WARN_ON(family->parallel_ops)) 1076 lockdep_assert_held(&genl_mutex); 1077 1078 return family->attrbuf; 1079 } 1080 EXPORT_SYMBOL(genl_family_attrbuf); 1081 1082 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group, 1083 gfp_t flags) 1084 { 1085 struct sk_buff *tmp; 1086 struct net *net, *prev = NULL; 1087 bool delivered = false; 1088 int err; 1089 1090 for_each_net_rcu(net) { 1091 if (prev) { 1092 tmp = skb_clone(skb, flags); 1093 if (!tmp) { 1094 err = -ENOMEM; 1095 goto error; 1096 } 1097 err = nlmsg_multicast(prev->genl_sock, tmp, 1098 portid, group, flags); 1099 if (!err) 1100 delivered = true; 1101 else if (err != -ESRCH) 1102 goto error; 1103 } 1104 1105 prev = net; 1106 } 1107 1108 err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags); 1109 if (!err) 1110 delivered = true; 1111 else if (err != -ESRCH) 1112 return err; 1113 return delivered ? 0 : -ESRCH; 1114 error: 1115 kfree_skb(skb); 1116 return err; 1117 } 1118 1119 int genlmsg_multicast_allns(const struct genl_family *family, 1120 struct sk_buff *skb, u32 portid, 1121 unsigned int group, gfp_t flags) 1122 { 1123 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 1124 return -EINVAL; 1125 group = family->mcgrp_offset + group; 1126 return genlmsg_mcast(skb, portid, group, flags); 1127 } 1128 EXPORT_SYMBOL(genlmsg_multicast_allns); 1129 1130 void genl_notify(const struct genl_family *family, struct sk_buff *skb, 1131 struct genl_info *info, u32 group, gfp_t flags) 1132 { 1133 struct net *net = genl_info_net(info); 1134 struct sock *sk = net->genl_sock; 1135 int report = 0; 1136 1137 if (info->nlhdr) 1138 report = nlmsg_report(info->nlhdr); 1139 1140 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 1141 return; 1142 group = family->mcgrp_offset + group; 1143 nlmsg_notify(sk, skb, info->snd_portid, group, report, flags); 1144 } 1145 EXPORT_SYMBOL(genl_notify); 1146