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((family->maxattr+1) * 356 sizeof(struct nlattr *), GFP_KERNEL); 357 if (family->attrbuf == NULL) { 358 err = -ENOMEM; 359 goto errout_locked; 360 } 361 } else 362 family->attrbuf = NULL; 363 364 family->id = idr_alloc(&genl_fam_idr, family, 365 start, end + 1, GFP_KERNEL); 366 if (family->id < 0) { 367 err = family->id; 368 goto errout_locked; 369 } 370 371 err = genl_validate_assign_mc_groups(family); 372 if (err) 373 goto errout_remove; 374 375 genl_unlock_all(); 376 377 /* send all events */ 378 genl_ctrl_event(CTRL_CMD_NEWFAMILY, family, NULL, 0); 379 for (i = 0; i < family->n_mcgrps; i++) 380 genl_ctrl_event(CTRL_CMD_NEWMCAST_GRP, family, 381 &family->mcgrps[i], family->mcgrp_offset + i); 382 383 return 0; 384 385 errout_remove: 386 idr_remove(&genl_fam_idr, family->id); 387 kfree(family->attrbuf); 388 errout_locked: 389 genl_unlock_all(); 390 return err; 391 } 392 EXPORT_SYMBOL(genl_register_family); 393 394 /** 395 * genl_unregister_family - unregister generic netlink family 396 * @family: generic netlink family 397 * 398 * Unregisters the specified family. 399 * 400 * Returns 0 on success or a negative error code. 401 */ 402 int genl_unregister_family(const struct genl_family *family) 403 { 404 genl_lock_all(); 405 406 if (!genl_family_find_byid(family->id)) { 407 genl_unlock_all(); 408 return -ENOENT; 409 } 410 411 genl_unregister_mc_groups(family); 412 413 idr_remove(&genl_fam_idr, family->id); 414 415 up_write(&cb_lock); 416 wait_event(genl_sk_destructing_waitq, 417 atomic_read(&genl_sk_destructing_cnt) == 0); 418 genl_unlock(); 419 420 kfree(family->attrbuf); 421 422 genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0); 423 424 return 0; 425 } 426 EXPORT_SYMBOL(genl_unregister_family); 427 428 /** 429 * genlmsg_put - Add generic netlink header to netlink message 430 * @skb: socket buffer holding the message 431 * @portid: netlink portid the message is addressed to 432 * @seq: sequence number (usually the one of the sender) 433 * @family: generic netlink family 434 * @flags: netlink message flags 435 * @cmd: generic netlink command 436 * 437 * Returns pointer to user specific header 438 */ 439 void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, 440 const struct genl_family *family, int flags, u8 cmd) 441 { 442 struct nlmsghdr *nlh; 443 struct genlmsghdr *hdr; 444 445 nlh = nlmsg_put(skb, portid, seq, family->id, GENL_HDRLEN + 446 family->hdrsize, flags); 447 if (nlh == NULL) 448 return NULL; 449 450 hdr = nlmsg_data(nlh); 451 hdr->cmd = cmd; 452 hdr->version = family->version; 453 hdr->reserved = 0; 454 455 return (char *) hdr + GENL_HDRLEN; 456 } 457 EXPORT_SYMBOL(genlmsg_put); 458 459 static int genl_lock_start(struct netlink_callback *cb) 460 { 461 /* our ops are always const - netlink API doesn't propagate that */ 462 const struct genl_ops *ops = cb->data; 463 int rc = 0; 464 465 if (ops->start) { 466 genl_lock(); 467 rc = ops->start(cb); 468 genl_unlock(); 469 } 470 return rc; 471 } 472 473 static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb) 474 { 475 /* our ops are always const - netlink API doesn't propagate that */ 476 const struct genl_ops *ops = cb->data; 477 int rc; 478 479 genl_lock(); 480 rc = ops->dumpit(skb, cb); 481 genl_unlock(); 482 return rc; 483 } 484 485 static int genl_lock_done(struct netlink_callback *cb) 486 { 487 /* our ops are always const - netlink API doesn't propagate that */ 488 const struct genl_ops *ops = cb->data; 489 int rc = 0; 490 491 if (ops->done) { 492 genl_lock(); 493 rc = ops->done(cb); 494 genl_unlock(); 495 } 496 return rc; 497 } 498 499 static int genl_family_rcv_msg(const struct genl_family *family, 500 struct sk_buff *skb, 501 struct nlmsghdr *nlh, 502 struct netlink_ext_ack *extack) 503 { 504 const struct genl_ops *ops; 505 struct net *net = sock_net(skb->sk); 506 struct genl_info info; 507 struct genlmsghdr *hdr = nlmsg_data(nlh); 508 struct nlattr **attrbuf; 509 int hdrlen, err; 510 511 /* this family doesn't exist in this netns */ 512 if (!family->netnsok && !net_eq(net, &init_net)) 513 return -ENOENT; 514 515 hdrlen = GENL_HDRLEN + family->hdrsize; 516 if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) 517 return -EINVAL; 518 519 ops = genl_get_cmd(hdr->cmd, family); 520 if (ops == NULL) 521 return -EOPNOTSUPP; 522 523 if ((ops->flags & GENL_ADMIN_PERM) && 524 !netlink_capable(skb, CAP_NET_ADMIN)) 525 return -EPERM; 526 527 if ((ops->flags & GENL_UNS_ADMIN_PERM) && 528 !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) 529 return -EPERM; 530 531 if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) { 532 int rc; 533 534 if (ops->dumpit == NULL) 535 return -EOPNOTSUPP; 536 537 if (!family->parallel_ops) { 538 struct netlink_dump_control c = { 539 .module = family->module, 540 /* we have const, but the netlink API doesn't */ 541 .data = (void *)ops, 542 .start = genl_lock_start, 543 .dump = genl_lock_dumpit, 544 .done = genl_lock_done, 545 }; 546 547 genl_unlock(); 548 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c); 549 genl_lock(); 550 551 } else { 552 struct netlink_dump_control c = { 553 .module = family->module, 554 .start = ops->start, 555 .dump = ops->dumpit, 556 .done = ops->done, 557 }; 558 559 rc = __netlink_dump_start(net->genl_sock, skb, nlh, &c); 560 } 561 562 return rc; 563 } 564 565 if (ops->doit == NULL) 566 return -EOPNOTSUPP; 567 568 if (family->maxattr && family->parallel_ops) { 569 attrbuf = kmalloc((family->maxattr+1) * 570 sizeof(struct nlattr *), GFP_KERNEL); 571 if (attrbuf == NULL) 572 return -ENOMEM; 573 } else 574 attrbuf = family->attrbuf; 575 576 if (attrbuf) { 577 err = nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr, 578 ops->policy, extack); 579 if (err < 0) 580 goto out; 581 } 582 583 info.snd_seq = nlh->nlmsg_seq; 584 info.snd_portid = NETLINK_CB(skb).portid; 585 info.nlhdr = nlh; 586 info.genlhdr = nlmsg_data(nlh); 587 info.userhdr = nlmsg_data(nlh) + GENL_HDRLEN; 588 info.attrs = attrbuf; 589 info.extack = extack; 590 genl_info_net_set(&info, net); 591 memset(&info.user_ptr, 0, sizeof(info.user_ptr)); 592 593 if (family->pre_doit) { 594 err = family->pre_doit(ops, skb, &info); 595 if (err) 596 goto out; 597 } 598 599 err = ops->doit(skb, &info); 600 601 if (family->post_doit) 602 family->post_doit(ops, skb, &info); 603 604 out: 605 if (family->parallel_ops) 606 kfree(attrbuf); 607 608 return err; 609 } 610 611 static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 612 struct netlink_ext_ack *extack) 613 { 614 const struct genl_family *family; 615 int err; 616 617 family = genl_family_find_byid(nlh->nlmsg_type); 618 if (family == NULL) 619 return -ENOENT; 620 621 if (!family->parallel_ops) 622 genl_lock(); 623 624 err = genl_family_rcv_msg(family, skb, nlh, extack); 625 626 if (!family->parallel_ops) 627 genl_unlock(); 628 629 return err; 630 } 631 632 static void genl_rcv(struct sk_buff *skb) 633 { 634 down_read(&cb_lock); 635 netlink_rcv_skb(skb, &genl_rcv_msg); 636 up_read(&cb_lock); 637 } 638 639 /************************************************************************** 640 * Controller 641 **************************************************************************/ 642 643 static struct genl_family genl_ctrl; 644 645 static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq, 646 u32 flags, struct sk_buff *skb, u8 cmd) 647 { 648 void *hdr; 649 650 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); 651 if (hdr == NULL) 652 return -1; 653 654 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) || 655 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id) || 656 nla_put_u32(skb, CTRL_ATTR_VERSION, family->version) || 657 nla_put_u32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize) || 658 nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr)) 659 goto nla_put_failure; 660 661 if (family->n_ops) { 662 struct nlattr *nla_ops; 663 int i; 664 665 nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS); 666 if (nla_ops == NULL) 667 goto nla_put_failure; 668 669 for (i = 0; i < family->n_ops; i++) { 670 struct nlattr *nest; 671 const struct genl_ops *ops = &family->ops[i]; 672 u32 op_flags = ops->flags; 673 674 if (ops->dumpit) 675 op_flags |= GENL_CMD_CAP_DUMP; 676 if (ops->doit) 677 op_flags |= GENL_CMD_CAP_DO; 678 if (ops->policy) 679 op_flags |= GENL_CMD_CAP_HASPOL; 680 681 nest = nla_nest_start(skb, i + 1); 682 if (nest == NULL) 683 goto nla_put_failure; 684 685 if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) || 686 nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags)) 687 goto nla_put_failure; 688 689 nla_nest_end(skb, nest); 690 } 691 692 nla_nest_end(skb, nla_ops); 693 } 694 695 if (family->n_mcgrps) { 696 struct nlattr *nla_grps; 697 int i; 698 699 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS); 700 if (nla_grps == NULL) 701 goto nla_put_failure; 702 703 for (i = 0; i < family->n_mcgrps; i++) { 704 struct nlattr *nest; 705 const struct genl_multicast_group *grp; 706 707 grp = &family->mcgrps[i]; 708 709 nest = nla_nest_start(skb, i + 1); 710 if (nest == NULL) 711 goto nla_put_failure; 712 713 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, 714 family->mcgrp_offset + i) || 715 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, 716 grp->name)) 717 goto nla_put_failure; 718 719 nla_nest_end(skb, nest); 720 } 721 nla_nest_end(skb, nla_grps); 722 } 723 724 genlmsg_end(skb, hdr); 725 return 0; 726 727 nla_put_failure: 728 genlmsg_cancel(skb, hdr); 729 return -EMSGSIZE; 730 } 731 732 static int ctrl_fill_mcgrp_info(const struct genl_family *family, 733 const struct genl_multicast_group *grp, 734 int grp_id, u32 portid, u32 seq, u32 flags, 735 struct sk_buff *skb, u8 cmd) 736 { 737 void *hdr; 738 struct nlattr *nla_grps; 739 struct nlattr *nest; 740 741 hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd); 742 if (hdr == NULL) 743 return -1; 744 745 if (nla_put_string(skb, CTRL_ATTR_FAMILY_NAME, family->name) || 746 nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, family->id)) 747 goto nla_put_failure; 748 749 nla_grps = nla_nest_start(skb, CTRL_ATTR_MCAST_GROUPS); 750 if (nla_grps == NULL) 751 goto nla_put_failure; 752 753 nest = nla_nest_start(skb, 1); 754 if (nest == NULL) 755 goto nla_put_failure; 756 757 if (nla_put_u32(skb, CTRL_ATTR_MCAST_GRP_ID, grp_id) || 758 nla_put_string(skb, CTRL_ATTR_MCAST_GRP_NAME, 759 grp->name)) 760 goto nla_put_failure; 761 762 nla_nest_end(skb, nest); 763 nla_nest_end(skb, nla_grps); 764 765 genlmsg_end(skb, hdr); 766 return 0; 767 768 nla_put_failure: 769 genlmsg_cancel(skb, hdr); 770 return -EMSGSIZE; 771 } 772 773 static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) 774 { 775 int n = 0; 776 struct genl_family *rt; 777 struct net *net = sock_net(skb->sk); 778 int fams_to_skip = cb->args[0]; 779 unsigned int id; 780 781 idr_for_each_entry(&genl_fam_idr, rt, id) { 782 if (!rt->netnsok && !net_eq(net, &init_net)) 783 continue; 784 785 if (n++ < fams_to_skip) 786 continue; 787 788 if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid, 789 cb->nlh->nlmsg_seq, NLM_F_MULTI, 790 skb, CTRL_CMD_NEWFAMILY) < 0) { 791 n--; 792 break; 793 } 794 } 795 796 cb->args[0] = n; 797 return skb->len; 798 } 799 800 static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family, 801 u32 portid, int seq, u8 cmd) 802 { 803 struct sk_buff *skb; 804 int err; 805 806 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 807 if (skb == NULL) 808 return ERR_PTR(-ENOBUFS); 809 810 err = ctrl_fill_info(family, portid, seq, 0, skb, cmd); 811 if (err < 0) { 812 nlmsg_free(skb); 813 return ERR_PTR(err); 814 } 815 816 return skb; 817 } 818 819 static struct sk_buff * 820 ctrl_build_mcgrp_msg(const struct genl_family *family, 821 const struct genl_multicast_group *grp, 822 int grp_id, u32 portid, int seq, u8 cmd) 823 { 824 struct sk_buff *skb; 825 int err; 826 827 skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); 828 if (skb == NULL) 829 return ERR_PTR(-ENOBUFS); 830 831 err = ctrl_fill_mcgrp_info(family, grp, grp_id, portid, 832 seq, 0, skb, cmd); 833 if (err < 0) { 834 nlmsg_free(skb); 835 return ERR_PTR(err); 836 } 837 838 return skb; 839 } 840 841 static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = { 842 [CTRL_ATTR_FAMILY_ID] = { .type = NLA_U16 }, 843 [CTRL_ATTR_FAMILY_NAME] = { .type = NLA_NUL_STRING, 844 .len = GENL_NAMSIZ - 1 }, 845 }; 846 847 static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info) 848 { 849 struct sk_buff *msg; 850 const struct genl_family *res = NULL; 851 int err = -EINVAL; 852 853 if (info->attrs[CTRL_ATTR_FAMILY_ID]) { 854 u16 id = nla_get_u16(info->attrs[CTRL_ATTR_FAMILY_ID]); 855 res = genl_family_find_byid(id); 856 err = -ENOENT; 857 } 858 859 if (info->attrs[CTRL_ATTR_FAMILY_NAME]) { 860 char *name; 861 862 name = nla_data(info->attrs[CTRL_ATTR_FAMILY_NAME]); 863 res = genl_family_find_byname(name); 864 #ifdef CONFIG_MODULES 865 if (res == NULL) { 866 genl_unlock(); 867 up_read(&cb_lock); 868 request_module("net-pf-%d-proto-%d-family-%s", 869 PF_NETLINK, NETLINK_GENERIC, name); 870 down_read(&cb_lock); 871 genl_lock(); 872 res = genl_family_find_byname(name); 873 } 874 #endif 875 err = -ENOENT; 876 } 877 878 if (res == NULL) 879 return err; 880 881 if (!res->netnsok && !net_eq(genl_info_net(info), &init_net)) { 882 /* family doesn't exist here */ 883 return -ENOENT; 884 } 885 886 msg = ctrl_build_family_msg(res, info->snd_portid, info->snd_seq, 887 CTRL_CMD_NEWFAMILY); 888 if (IS_ERR(msg)) 889 return PTR_ERR(msg); 890 891 return genlmsg_reply(msg, info); 892 } 893 894 static int genl_ctrl_event(int event, const struct genl_family *family, 895 const struct genl_multicast_group *grp, 896 int grp_id) 897 { 898 struct sk_buff *msg; 899 900 /* genl is still initialising */ 901 if (!init_net.genl_sock) 902 return 0; 903 904 switch (event) { 905 case CTRL_CMD_NEWFAMILY: 906 case CTRL_CMD_DELFAMILY: 907 WARN_ON(grp); 908 msg = ctrl_build_family_msg(family, 0, 0, event); 909 break; 910 case CTRL_CMD_NEWMCAST_GRP: 911 case CTRL_CMD_DELMCAST_GRP: 912 BUG_ON(!grp); 913 msg = ctrl_build_mcgrp_msg(family, grp, grp_id, 0, 0, event); 914 break; 915 default: 916 return -EINVAL; 917 } 918 919 if (IS_ERR(msg)) 920 return PTR_ERR(msg); 921 922 if (!family->netnsok) { 923 genlmsg_multicast_netns(&genl_ctrl, &init_net, msg, 0, 924 0, GFP_KERNEL); 925 } else { 926 rcu_read_lock(); 927 genlmsg_multicast_allns(&genl_ctrl, msg, 0, 928 0, GFP_ATOMIC); 929 rcu_read_unlock(); 930 } 931 932 return 0; 933 } 934 935 static const struct genl_ops genl_ctrl_ops[] = { 936 { 937 .cmd = CTRL_CMD_GETFAMILY, 938 .doit = ctrl_getfamily, 939 .dumpit = ctrl_dumpfamily, 940 .policy = ctrl_policy, 941 }, 942 }; 943 944 static const struct genl_multicast_group genl_ctrl_groups[] = { 945 { .name = "notify", }, 946 }; 947 948 static struct genl_family genl_ctrl __ro_after_init = { 949 .module = THIS_MODULE, 950 .ops = genl_ctrl_ops, 951 .n_ops = ARRAY_SIZE(genl_ctrl_ops), 952 .mcgrps = genl_ctrl_groups, 953 .n_mcgrps = ARRAY_SIZE(genl_ctrl_groups), 954 .id = GENL_ID_CTRL, 955 .name = "nlctrl", 956 .version = 0x2, 957 .maxattr = CTRL_ATTR_MAX, 958 .netnsok = true, 959 }; 960 961 static int genl_bind(struct net *net, int group) 962 { 963 struct genl_family *f; 964 int err = -ENOENT; 965 unsigned int id; 966 967 down_read(&cb_lock); 968 969 idr_for_each_entry(&genl_fam_idr, f, id) { 970 if (group >= f->mcgrp_offset && 971 group < f->mcgrp_offset + f->n_mcgrps) { 972 int fam_grp = group - f->mcgrp_offset; 973 974 if (!f->netnsok && net != &init_net) 975 err = -ENOENT; 976 else if (f->mcast_bind) 977 err = f->mcast_bind(net, fam_grp); 978 else 979 err = 0; 980 break; 981 } 982 } 983 up_read(&cb_lock); 984 985 return err; 986 } 987 988 static void genl_unbind(struct net *net, int group) 989 { 990 struct genl_family *f; 991 unsigned int id; 992 993 down_read(&cb_lock); 994 995 idr_for_each_entry(&genl_fam_idr, f, id) { 996 if (group >= f->mcgrp_offset && 997 group < f->mcgrp_offset + f->n_mcgrps) { 998 int fam_grp = group - f->mcgrp_offset; 999 1000 if (f->mcast_unbind) 1001 f->mcast_unbind(net, fam_grp); 1002 break; 1003 } 1004 } 1005 up_read(&cb_lock); 1006 } 1007 1008 static int __net_init genl_pernet_init(struct net *net) 1009 { 1010 struct netlink_kernel_cfg cfg = { 1011 .input = genl_rcv, 1012 .flags = NL_CFG_F_NONROOT_RECV, 1013 .bind = genl_bind, 1014 .unbind = genl_unbind, 1015 }; 1016 1017 /* we'll bump the group number right afterwards */ 1018 net->genl_sock = netlink_kernel_create(net, NETLINK_GENERIC, &cfg); 1019 1020 if (!net->genl_sock && net_eq(net, &init_net)) 1021 panic("GENL: Cannot initialize generic netlink\n"); 1022 1023 if (!net->genl_sock) 1024 return -ENOMEM; 1025 1026 return 0; 1027 } 1028 1029 static void __net_exit genl_pernet_exit(struct net *net) 1030 { 1031 netlink_kernel_release(net->genl_sock); 1032 net->genl_sock = NULL; 1033 } 1034 1035 static struct pernet_operations genl_pernet_ops = { 1036 .init = genl_pernet_init, 1037 .exit = genl_pernet_exit, 1038 }; 1039 1040 static int __init genl_init(void) 1041 { 1042 int err; 1043 1044 err = genl_register_family(&genl_ctrl); 1045 if (err < 0) 1046 goto problem; 1047 1048 err = register_pernet_subsys(&genl_pernet_ops); 1049 if (err) 1050 goto problem; 1051 1052 return 0; 1053 1054 problem: 1055 panic("GENL: Cannot register controller: %d\n", err); 1056 } 1057 1058 subsys_initcall(genl_init); 1059 1060 /** 1061 * genl_family_attrbuf - return family's attrbuf 1062 * @family: the family 1063 * 1064 * Return the family's attrbuf, while validating that it's 1065 * actually valid to access it. 1066 * 1067 * You cannot use this function with a family that has parallel_ops 1068 * and you can only use it within (pre/post) doit/dumpit callbacks. 1069 */ 1070 struct nlattr **genl_family_attrbuf(const struct genl_family *family) 1071 { 1072 if (!WARN_ON(family->parallel_ops)) 1073 lockdep_assert_held(&genl_mutex); 1074 1075 return family->attrbuf; 1076 } 1077 EXPORT_SYMBOL(genl_family_attrbuf); 1078 1079 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group, 1080 gfp_t flags) 1081 { 1082 struct sk_buff *tmp; 1083 struct net *net, *prev = NULL; 1084 int err; 1085 1086 for_each_net_rcu(net) { 1087 if (prev) { 1088 tmp = skb_clone(skb, flags); 1089 if (!tmp) { 1090 err = -ENOMEM; 1091 goto error; 1092 } 1093 err = nlmsg_multicast(prev->genl_sock, tmp, 1094 portid, group, flags); 1095 if (err) 1096 goto error; 1097 } 1098 1099 prev = net; 1100 } 1101 1102 return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags); 1103 error: 1104 kfree_skb(skb); 1105 return err; 1106 } 1107 1108 int genlmsg_multicast_allns(const struct genl_family *family, 1109 struct sk_buff *skb, u32 portid, 1110 unsigned int group, gfp_t flags) 1111 { 1112 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 1113 return -EINVAL; 1114 group = family->mcgrp_offset + group; 1115 return genlmsg_mcast(skb, portid, group, flags); 1116 } 1117 EXPORT_SYMBOL(genlmsg_multicast_allns); 1118 1119 void genl_notify(const struct genl_family *family, struct sk_buff *skb, 1120 struct genl_info *info, u32 group, gfp_t flags) 1121 { 1122 struct net *net = genl_info_net(info); 1123 struct sock *sk = net->genl_sock; 1124 int report = 0; 1125 1126 if (info->nlhdr) 1127 report = nlmsg_report(info->nlhdr); 1128 1129 if (WARN_ON_ONCE(group >= family->n_mcgrps)) 1130 return; 1131 group = family->mcgrp_offset + group; 1132 nlmsg_notify(sk, skb, info->snd_portid, group, report, flags); 1133 } 1134 EXPORT_SYMBOL(genl_notify); 1135