1 /* 2 * /proc/sys support 3 */ 4 #include <linux/init.h> 5 #include <linux/sysctl.h> 6 #include <linux/poll.h> 7 #include <linux/proc_fs.h> 8 #include <linux/printk.h> 9 #include <linux/security.h> 10 #include <linux/sched.h> 11 #include <linux/namei.h> 12 #include <linux/mm.h> 13 #include <linux/module.h> 14 #include "internal.h" 15 16 static const struct dentry_operations proc_sys_dentry_operations; 17 static const struct file_operations proc_sys_file_operations; 18 static const struct inode_operations proc_sys_inode_operations; 19 static const struct file_operations proc_sys_dir_file_operations; 20 static const struct inode_operations proc_sys_dir_operations; 21 22 /* Support for permanently empty directories */ 23 24 struct ctl_table sysctl_mount_point[] = { 25 { } 26 }; 27 28 static bool is_empty_dir(struct ctl_table_header *head) 29 { 30 return head->ctl_table[0].child == sysctl_mount_point; 31 } 32 33 static void set_empty_dir(struct ctl_dir *dir) 34 { 35 dir->header.ctl_table[0].child = sysctl_mount_point; 36 } 37 38 static void clear_empty_dir(struct ctl_dir *dir) 39 40 { 41 dir->header.ctl_table[0].child = NULL; 42 } 43 44 void proc_sys_poll_notify(struct ctl_table_poll *poll) 45 { 46 if (!poll) 47 return; 48 49 atomic_inc(&poll->event); 50 wake_up_interruptible(&poll->wait); 51 } 52 53 static struct ctl_table root_table[] = { 54 { 55 .procname = "", 56 .mode = S_IFDIR|S_IRUGO|S_IXUGO, 57 }, 58 { } 59 }; 60 static struct ctl_table_root sysctl_table_root = { 61 .default_set.dir.header = { 62 {{.count = 1, 63 .nreg = 1, 64 .ctl_table = root_table }}, 65 .ctl_table_arg = root_table, 66 .root = &sysctl_table_root, 67 .set = &sysctl_table_root.default_set, 68 }, 69 }; 70 71 static DEFINE_SPINLOCK(sysctl_lock); 72 73 static void drop_sysctl_table(struct ctl_table_header *header); 74 static int sysctl_follow_link(struct ctl_table_header **phead, 75 struct ctl_table **pentry, struct nsproxy *namespaces); 76 static int insert_links(struct ctl_table_header *head); 77 static void put_links(struct ctl_table_header *header); 78 79 static void sysctl_print_dir(struct ctl_dir *dir) 80 { 81 if (dir->header.parent) 82 sysctl_print_dir(dir->header.parent); 83 pr_cont("%s/", dir->header.ctl_table[0].procname); 84 } 85 86 static int namecmp(const char *name1, int len1, const char *name2, int len2) 87 { 88 int minlen; 89 int cmp; 90 91 minlen = len1; 92 if (minlen > len2) 93 minlen = len2; 94 95 cmp = memcmp(name1, name2, minlen); 96 if (cmp == 0) 97 cmp = len1 - len2; 98 return cmp; 99 } 100 101 /* Called under sysctl_lock */ 102 static struct ctl_table *find_entry(struct ctl_table_header **phead, 103 struct ctl_dir *dir, const char *name, int namelen) 104 { 105 struct ctl_table_header *head; 106 struct ctl_table *entry; 107 struct rb_node *node = dir->root.rb_node; 108 109 while (node) 110 { 111 struct ctl_node *ctl_node; 112 const char *procname; 113 int cmp; 114 115 ctl_node = rb_entry(node, struct ctl_node, node); 116 head = ctl_node->header; 117 entry = &head->ctl_table[ctl_node - head->node]; 118 procname = entry->procname; 119 120 cmp = namecmp(name, namelen, procname, strlen(procname)); 121 if (cmp < 0) 122 node = node->rb_left; 123 else if (cmp > 0) 124 node = node->rb_right; 125 else { 126 *phead = head; 127 return entry; 128 } 129 } 130 return NULL; 131 } 132 133 static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry) 134 { 135 struct rb_node *node = &head->node[entry - head->ctl_table].node; 136 struct rb_node **p = &head->parent->root.rb_node; 137 struct rb_node *parent = NULL; 138 const char *name = entry->procname; 139 int namelen = strlen(name); 140 141 while (*p) { 142 struct ctl_table_header *parent_head; 143 struct ctl_table *parent_entry; 144 struct ctl_node *parent_node; 145 const char *parent_name; 146 int cmp; 147 148 parent = *p; 149 parent_node = rb_entry(parent, struct ctl_node, node); 150 parent_head = parent_node->header; 151 parent_entry = &parent_head->ctl_table[parent_node - parent_head->node]; 152 parent_name = parent_entry->procname; 153 154 cmp = namecmp(name, namelen, parent_name, strlen(parent_name)); 155 if (cmp < 0) 156 p = &(*p)->rb_left; 157 else if (cmp > 0) 158 p = &(*p)->rb_right; 159 else { 160 pr_err("sysctl duplicate entry: "); 161 sysctl_print_dir(head->parent); 162 pr_cont("/%s\n", entry->procname); 163 return -EEXIST; 164 } 165 } 166 167 rb_link_node(node, parent, p); 168 rb_insert_color(node, &head->parent->root); 169 return 0; 170 } 171 172 static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry) 173 { 174 struct rb_node *node = &head->node[entry - head->ctl_table].node; 175 176 rb_erase(node, &head->parent->root); 177 } 178 179 static void init_header(struct ctl_table_header *head, 180 struct ctl_table_root *root, struct ctl_table_set *set, 181 struct ctl_node *node, struct ctl_table *table) 182 { 183 head->ctl_table = table; 184 head->ctl_table_arg = table; 185 head->used = 0; 186 head->count = 1; 187 head->nreg = 1; 188 head->unregistering = NULL; 189 head->root = root; 190 head->set = set; 191 head->parent = NULL; 192 head->node = node; 193 if (node) { 194 struct ctl_table *entry; 195 for (entry = table; entry->procname; entry++, node++) 196 node->header = head; 197 } 198 } 199 200 static void erase_header(struct ctl_table_header *head) 201 { 202 struct ctl_table *entry; 203 for (entry = head->ctl_table; entry->procname; entry++) 204 erase_entry(head, entry); 205 } 206 207 static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header) 208 { 209 struct ctl_table *entry; 210 int err; 211 212 /* Is this a permanently empty directory? */ 213 if (is_empty_dir(&dir->header)) 214 return -EROFS; 215 216 /* Am I creating a permanently empty directory? */ 217 if (header->ctl_table == sysctl_mount_point) { 218 if (!RB_EMPTY_ROOT(&dir->root)) 219 return -EINVAL; 220 set_empty_dir(dir); 221 } 222 223 dir->header.nreg++; 224 header->parent = dir; 225 err = insert_links(header); 226 if (err) 227 goto fail_links; 228 for (entry = header->ctl_table; entry->procname; entry++) { 229 err = insert_entry(header, entry); 230 if (err) 231 goto fail; 232 } 233 return 0; 234 fail: 235 erase_header(header); 236 put_links(header); 237 fail_links: 238 if (header->ctl_table == sysctl_mount_point) 239 clear_empty_dir(dir); 240 header->parent = NULL; 241 drop_sysctl_table(&dir->header); 242 return err; 243 } 244 245 /* called under sysctl_lock */ 246 static int use_table(struct ctl_table_header *p) 247 { 248 if (unlikely(p->unregistering)) 249 return 0; 250 p->used++; 251 return 1; 252 } 253 254 /* called under sysctl_lock */ 255 static void unuse_table(struct ctl_table_header *p) 256 { 257 if (!--p->used) 258 if (unlikely(p->unregistering)) 259 complete(p->unregistering); 260 } 261 262 /* called under sysctl_lock, will reacquire if has to wait */ 263 static void start_unregistering(struct ctl_table_header *p) 264 { 265 /* 266 * if p->used is 0, nobody will ever touch that entry again; 267 * we'll eliminate all paths to it before dropping sysctl_lock 268 */ 269 if (unlikely(p->used)) { 270 struct completion wait; 271 init_completion(&wait); 272 p->unregistering = &wait; 273 spin_unlock(&sysctl_lock); 274 wait_for_completion(&wait); 275 spin_lock(&sysctl_lock); 276 } else { 277 /* anything non-NULL; we'll never dereference it */ 278 p->unregistering = ERR_PTR(-EINVAL); 279 } 280 /* 281 * do not remove from the list until nobody holds it; walking the 282 * list in do_sysctl() relies on that. 283 */ 284 erase_header(p); 285 } 286 287 static void sysctl_head_get(struct ctl_table_header *head) 288 { 289 spin_lock(&sysctl_lock); 290 head->count++; 291 spin_unlock(&sysctl_lock); 292 } 293 294 void sysctl_head_put(struct ctl_table_header *head) 295 { 296 spin_lock(&sysctl_lock); 297 if (!--head->count) 298 kfree_rcu(head, rcu); 299 spin_unlock(&sysctl_lock); 300 } 301 302 static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head) 303 { 304 BUG_ON(!head); 305 spin_lock(&sysctl_lock); 306 if (!use_table(head)) 307 head = ERR_PTR(-ENOENT); 308 spin_unlock(&sysctl_lock); 309 return head; 310 } 311 312 static void sysctl_head_finish(struct ctl_table_header *head) 313 { 314 if (!head) 315 return; 316 spin_lock(&sysctl_lock); 317 unuse_table(head); 318 spin_unlock(&sysctl_lock); 319 } 320 321 static struct ctl_table_set * 322 lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces) 323 { 324 struct ctl_table_set *set = &root->default_set; 325 if (root->lookup) 326 set = root->lookup(root, namespaces); 327 return set; 328 } 329 330 static struct ctl_table *lookup_entry(struct ctl_table_header **phead, 331 struct ctl_dir *dir, 332 const char *name, int namelen) 333 { 334 struct ctl_table_header *head; 335 struct ctl_table *entry; 336 337 spin_lock(&sysctl_lock); 338 entry = find_entry(&head, dir, name, namelen); 339 if (entry && use_table(head)) 340 *phead = head; 341 else 342 entry = NULL; 343 spin_unlock(&sysctl_lock); 344 return entry; 345 } 346 347 static struct ctl_node *first_usable_entry(struct rb_node *node) 348 { 349 struct ctl_node *ctl_node; 350 351 for (;node; node = rb_next(node)) { 352 ctl_node = rb_entry(node, struct ctl_node, node); 353 if (use_table(ctl_node->header)) 354 return ctl_node; 355 } 356 return NULL; 357 } 358 359 static void first_entry(struct ctl_dir *dir, 360 struct ctl_table_header **phead, struct ctl_table **pentry) 361 { 362 struct ctl_table_header *head = NULL; 363 struct ctl_table *entry = NULL; 364 struct ctl_node *ctl_node; 365 366 spin_lock(&sysctl_lock); 367 ctl_node = first_usable_entry(rb_first(&dir->root)); 368 spin_unlock(&sysctl_lock); 369 if (ctl_node) { 370 head = ctl_node->header; 371 entry = &head->ctl_table[ctl_node - head->node]; 372 } 373 *phead = head; 374 *pentry = entry; 375 } 376 377 static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry) 378 { 379 struct ctl_table_header *head = *phead; 380 struct ctl_table *entry = *pentry; 381 struct ctl_node *ctl_node = &head->node[entry - head->ctl_table]; 382 383 spin_lock(&sysctl_lock); 384 unuse_table(head); 385 386 ctl_node = first_usable_entry(rb_next(&ctl_node->node)); 387 spin_unlock(&sysctl_lock); 388 head = NULL; 389 if (ctl_node) { 390 head = ctl_node->header; 391 entry = &head->ctl_table[ctl_node - head->node]; 392 } 393 *phead = head; 394 *pentry = entry; 395 } 396 397 void register_sysctl_root(struct ctl_table_root *root) 398 { 399 } 400 401 /* 402 * sysctl_perm does NOT grant the superuser all rights automatically, because 403 * some sysctl variables are readonly even to root. 404 */ 405 406 static int test_perm(int mode, int op) 407 { 408 if (uid_eq(current_euid(), GLOBAL_ROOT_UID)) 409 mode >>= 6; 410 else if (in_egroup_p(GLOBAL_ROOT_GID)) 411 mode >>= 3; 412 if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0) 413 return 0; 414 return -EACCES; 415 } 416 417 static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op) 418 { 419 struct ctl_table_root *root = head->root; 420 int mode; 421 422 if (root->permissions) 423 mode = root->permissions(head, table); 424 else 425 mode = table->mode; 426 427 return test_perm(mode, op); 428 } 429 430 static struct inode *proc_sys_make_inode(struct super_block *sb, 431 struct ctl_table_header *head, struct ctl_table *table) 432 { 433 struct inode *inode; 434 struct proc_inode *ei; 435 436 inode = new_inode(sb); 437 if (!inode) 438 goto out; 439 440 inode->i_ino = get_next_ino(); 441 442 sysctl_head_get(head); 443 ei = PROC_I(inode); 444 ei->sysctl = head; 445 ei->sysctl_entry = table; 446 447 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 448 inode->i_mode = table->mode; 449 if (!S_ISDIR(table->mode)) { 450 inode->i_mode |= S_IFREG; 451 inode->i_op = &proc_sys_inode_operations; 452 inode->i_fop = &proc_sys_file_operations; 453 } else { 454 inode->i_mode |= S_IFDIR; 455 inode->i_op = &proc_sys_dir_operations; 456 inode->i_fop = &proc_sys_dir_file_operations; 457 if (is_empty_dir(head)) 458 make_empty_dir_inode(inode); 459 } 460 out: 461 return inode; 462 } 463 464 static struct ctl_table_header *grab_header(struct inode *inode) 465 { 466 struct ctl_table_header *head = PROC_I(inode)->sysctl; 467 if (!head) 468 head = &sysctl_table_root.default_set.dir.header; 469 return sysctl_head_grab(head); 470 } 471 472 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, 473 unsigned int flags) 474 { 475 struct ctl_table_header *head = grab_header(dir); 476 struct ctl_table_header *h = NULL; 477 struct qstr *name = &dentry->d_name; 478 struct ctl_table *p; 479 struct inode *inode; 480 struct dentry *err = ERR_PTR(-ENOENT); 481 struct ctl_dir *ctl_dir; 482 int ret; 483 484 if (IS_ERR(head)) 485 return ERR_CAST(head); 486 487 ctl_dir = container_of(head, struct ctl_dir, header); 488 489 p = lookup_entry(&h, ctl_dir, name->name, name->len); 490 if (!p) 491 goto out; 492 493 if (S_ISLNK(p->mode)) { 494 ret = sysctl_follow_link(&h, &p, current->nsproxy); 495 err = ERR_PTR(ret); 496 if (ret) 497 goto out; 498 } 499 500 err = ERR_PTR(-ENOMEM); 501 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); 502 if (!inode) 503 goto out; 504 505 err = NULL; 506 d_set_d_op(dentry, &proc_sys_dentry_operations); 507 d_add(dentry, inode); 508 509 out: 510 if (h) 511 sysctl_head_finish(h); 512 sysctl_head_finish(head); 513 return err; 514 } 515 516 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf, 517 size_t count, loff_t *ppos, int write) 518 { 519 struct inode *inode = file_inode(filp); 520 struct ctl_table_header *head = grab_header(inode); 521 struct ctl_table *table = PROC_I(inode)->sysctl_entry; 522 ssize_t error; 523 size_t res; 524 525 if (IS_ERR(head)) 526 return PTR_ERR(head); 527 528 /* 529 * At this point we know that the sysctl was not unregistered 530 * and won't be until we finish. 531 */ 532 error = -EPERM; 533 if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ)) 534 goto out; 535 536 /* if that can happen at all, it should be -EINVAL, not -EISDIR */ 537 error = -EINVAL; 538 if (!table->proc_handler) 539 goto out; 540 541 /* careful: calling conventions are nasty here */ 542 res = count; 543 error = table->proc_handler(table, write, buf, &res, ppos); 544 if (!error) 545 error = res; 546 out: 547 sysctl_head_finish(head); 548 549 return error; 550 } 551 552 static ssize_t proc_sys_read(struct file *filp, char __user *buf, 553 size_t count, loff_t *ppos) 554 { 555 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0); 556 } 557 558 static ssize_t proc_sys_write(struct file *filp, const char __user *buf, 559 size_t count, loff_t *ppos) 560 { 561 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1); 562 } 563 564 static int proc_sys_open(struct inode *inode, struct file *filp) 565 { 566 struct ctl_table_header *head = grab_header(inode); 567 struct ctl_table *table = PROC_I(inode)->sysctl_entry; 568 569 /* sysctl was unregistered */ 570 if (IS_ERR(head)) 571 return PTR_ERR(head); 572 573 if (table->poll) 574 filp->private_data = proc_sys_poll_event(table->poll); 575 576 sysctl_head_finish(head); 577 578 return 0; 579 } 580 581 static unsigned int proc_sys_poll(struct file *filp, poll_table *wait) 582 { 583 struct inode *inode = file_inode(filp); 584 struct ctl_table_header *head = grab_header(inode); 585 struct ctl_table *table = PROC_I(inode)->sysctl_entry; 586 unsigned int ret = DEFAULT_POLLMASK; 587 unsigned long event; 588 589 /* sysctl was unregistered */ 590 if (IS_ERR(head)) 591 return POLLERR | POLLHUP; 592 593 if (!table->proc_handler) 594 goto out; 595 596 if (!table->poll) 597 goto out; 598 599 event = (unsigned long)filp->private_data; 600 poll_wait(filp, &table->poll->wait, wait); 601 602 if (event != atomic_read(&table->poll->event)) { 603 filp->private_data = proc_sys_poll_event(table->poll); 604 ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI; 605 } 606 607 out: 608 sysctl_head_finish(head); 609 610 return ret; 611 } 612 613 static bool proc_sys_fill_cache(struct file *file, 614 struct dir_context *ctx, 615 struct ctl_table_header *head, 616 struct ctl_table *table) 617 { 618 struct dentry *child, *dir = file->f_path.dentry; 619 struct inode *inode; 620 struct qstr qname; 621 ino_t ino = 0; 622 unsigned type = DT_UNKNOWN; 623 624 qname.name = table->procname; 625 qname.len = strlen(table->procname); 626 qname.hash = full_name_hash(qname.name, qname.len); 627 628 child = d_lookup(dir, &qname); 629 if (!child) { 630 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 631 child = d_alloc_parallel(dir, &qname, &wq); 632 if (IS_ERR(child)) 633 return false; 634 if (d_in_lookup(child)) { 635 inode = proc_sys_make_inode(dir->d_sb, head, table); 636 if (!inode) { 637 d_lookup_done(child); 638 dput(child); 639 return false; 640 } 641 d_set_d_op(child, &proc_sys_dentry_operations); 642 d_add(child, inode); 643 } 644 } 645 inode = d_inode(child); 646 ino = inode->i_ino; 647 type = inode->i_mode >> 12; 648 dput(child); 649 return dir_emit(ctx, qname.name, qname.len, ino, type); 650 } 651 652 static bool proc_sys_link_fill_cache(struct file *file, 653 struct dir_context *ctx, 654 struct ctl_table_header *head, 655 struct ctl_table *table) 656 { 657 bool ret = true; 658 head = sysctl_head_grab(head); 659 660 if (S_ISLNK(table->mode)) { 661 /* It is not an error if we can not follow the link ignore it */ 662 int err = sysctl_follow_link(&head, &table, current->nsproxy); 663 if (err) 664 goto out; 665 } 666 667 ret = proc_sys_fill_cache(file, ctx, head, table); 668 out: 669 sysctl_head_finish(head); 670 return ret; 671 } 672 673 static int scan(struct ctl_table_header *head, struct ctl_table *table, 674 unsigned long *pos, struct file *file, 675 struct dir_context *ctx) 676 { 677 bool res; 678 679 if ((*pos)++ < ctx->pos) 680 return true; 681 682 if (unlikely(S_ISLNK(table->mode))) 683 res = proc_sys_link_fill_cache(file, ctx, head, table); 684 else 685 res = proc_sys_fill_cache(file, ctx, head, table); 686 687 if (res) 688 ctx->pos = *pos; 689 690 return res; 691 } 692 693 static int proc_sys_readdir(struct file *file, struct dir_context *ctx) 694 { 695 struct ctl_table_header *head = grab_header(file_inode(file)); 696 struct ctl_table_header *h = NULL; 697 struct ctl_table *entry; 698 struct ctl_dir *ctl_dir; 699 unsigned long pos; 700 701 if (IS_ERR(head)) 702 return PTR_ERR(head); 703 704 ctl_dir = container_of(head, struct ctl_dir, header); 705 706 if (!dir_emit_dots(file, ctx)) 707 return 0; 708 709 pos = 2; 710 711 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) { 712 if (!scan(h, entry, &pos, file, ctx)) { 713 sysctl_head_finish(h); 714 break; 715 } 716 } 717 sysctl_head_finish(head); 718 return 0; 719 } 720 721 static int proc_sys_permission(struct inode *inode, int mask) 722 { 723 /* 724 * sysctl entries that are not writeable, 725 * are _NOT_ writeable, capabilities or not. 726 */ 727 struct ctl_table_header *head; 728 struct ctl_table *table; 729 int error; 730 731 /* Executable files are not allowed under /proc/sys/ */ 732 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) 733 return -EACCES; 734 735 head = grab_header(inode); 736 if (IS_ERR(head)) 737 return PTR_ERR(head); 738 739 table = PROC_I(inode)->sysctl_entry; 740 if (!table) /* global root - r-xr-xr-x */ 741 error = mask & MAY_WRITE ? -EACCES : 0; 742 else /* Use the permissions on the sysctl table entry */ 743 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK); 744 745 sysctl_head_finish(head); 746 return error; 747 } 748 749 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr) 750 { 751 struct inode *inode = d_inode(dentry); 752 int error; 753 754 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) 755 return -EPERM; 756 757 error = inode_change_ok(inode, attr); 758 if (error) 759 return error; 760 761 setattr_copy(inode, attr); 762 mark_inode_dirty(inode); 763 return 0; 764 } 765 766 static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) 767 { 768 struct inode *inode = d_inode(dentry); 769 struct ctl_table_header *head = grab_header(inode); 770 struct ctl_table *table = PROC_I(inode)->sysctl_entry; 771 772 if (IS_ERR(head)) 773 return PTR_ERR(head); 774 775 generic_fillattr(inode, stat); 776 if (table) 777 stat->mode = (stat->mode & S_IFMT) | table->mode; 778 779 sysctl_head_finish(head); 780 return 0; 781 } 782 783 static const struct file_operations proc_sys_file_operations = { 784 .open = proc_sys_open, 785 .poll = proc_sys_poll, 786 .read = proc_sys_read, 787 .write = proc_sys_write, 788 .llseek = default_llseek, 789 }; 790 791 static const struct file_operations proc_sys_dir_file_operations = { 792 .read = generic_read_dir, 793 .iterate_shared = proc_sys_readdir, 794 .llseek = generic_file_llseek, 795 }; 796 797 static const struct inode_operations proc_sys_inode_operations = { 798 .permission = proc_sys_permission, 799 .setattr = proc_sys_setattr, 800 .getattr = proc_sys_getattr, 801 }; 802 803 static const struct inode_operations proc_sys_dir_operations = { 804 .lookup = proc_sys_lookup, 805 .permission = proc_sys_permission, 806 .setattr = proc_sys_setattr, 807 .getattr = proc_sys_getattr, 808 }; 809 810 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags) 811 { 812 if (flags & LOOKUP_RCU) 813 return -ECHILD; 814 return !PROC_I(d_inode(dentry))->sysctl->unregistering; 815 } 816 817 static int proc_sys_delete(const struct dentry *dentry) 818 { 819 return !!PROC_I(d_inode(dentry))->sysctl->unregistering; 820 } 821 822 static int sysctl_is_seen(struct ctl_table_header *p) 823 { 824 struct ctl_table_set *set = p->set; 825 int res; 826 spin_lock(&sysctl_lock); 827 if (p->unregistering) 828 res = 0; 829 else if (!set->is_seen) 830 res = 1; 831 else 832 res = set->is_seen(set); 833 spin_unlock(&sysctl_lock); 834 return res; 835 } 836 837 static int proc_sys_compare(const struct dentry *parent, const struct dentry *dentry, 838 unsigned int len, const char *str, const struct qstr *name) 839 { 840 struct ctl_table_header *head; 841 struct inode *inode; 842 843 /* Although proc doesn't have negative dentries, rcu-walk means 844 * that inode here can be NULL */ 845 /* AV: can it, indeed? */ 846 inode = d_inode_rcu(dentry); 847 if (!inode) 848 return 1; 849 if (name->len != len) 850 return 1; 851 if (memcmp(name->name, str, len)) 852 return 1; 853 head = rcu_dereference(PROC_I(inode)->sysctl); 854 return !head || !sysctl_is_seen(head); 855 } 856 857 static const struct dentry_operations proc_sys_dentry_operations = { 858 .d_revalidate = proc_sys_revalidate, 859 .d_delete = proc_sys_delete, 860 .d_compare = proc_sys_compare, 861 }; 862 863 static struct ctl_dir *find_subdir(struct ctl_dir *dir, 864 const char *name, int namelen) 865 { 866 struct ctl_table_header *head; 867 struct ctl_table *entry; 868 869 entry = find_entry(&head, dir, name, namelen); 870 if (!entry) 871 return ERR_PTR(-ENOENT); 872 if (!S_ISDIR(entry->mode)) 873 return ERR_PTR(-ENOTDIR); 874 return container_of(head, struct ctl_dir, header); 875 } 876 877 static struct ctl_dir *new_dir(struct ctl_table_set *set, 878 const char *name, int namelen) 879 { 880 struct ctl_table *table; 881 struct ctl_dir *new; 882 struct ctl_node *node; 883 char *new_name; 884 885 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) + 886 sizeof(struct ctl_table)*2 + namelen + 1, 887 GFP_KERNEL); 888 if (!new) 889 return NULL; 890 891 node = (struct ctl_node *)(new + 1); 892 table = (struct ctl_table *)(node + 1); 893 new_name = (char *)(table + 2); 894 memcpy(new_name, name, namelen); 895 new_name[namelen] = '\0'; 896 table[0].procname = new_name; 897 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO; 898 init_header(&new->header, set->dir.header.root, set, node, table); 899 900 return new; 901 } 902 903 /** 904 * get_subdir - find or create a subdir with the specified name. 905 * @dir: Directory to create the subdirectory in 906 * @name: The name of the subdirectory to find or create 907 * @namelen: The length of name 908 * 909 * Takes a directory with an elevated reference count so we know that 910 * if we drop the lock the directory will not go away. Upon success 911 * the reference is moved from @dir to the returned subdirectory. 912 * Upon error an error code is returned and the reference on @dir is 913 * simply dropped. 914 */ 915 static struct ctl_dir *get_subdir(struct ctl_dir *dir, 916 const char *name, int namelen) 917 { 918 struct ctl_table_set *set = dir->header.set; 919 struct ctl_dir *subdir, *new = NULL; 920 int err; 921 922 spin_lock(&sysctl_lock); 923 subdir = find_subdir(dir, name, namelen); 924 if (!IS_ERR(subdir)) 925 goto found; 926 if (PTR_ERR(subdir) != -ENOENT) 927 goto failed; 928 929 spin_unlock(&sysctl_lock); 930 new = new_dir(set, name, namelen); 931 spin_lock(&sysctl_lock); 932 subdir = ERR_PTR(-ENOMEM); 933 if (!new) 934 goto failed; 935 936 /* Was the subdir added while we dropped the lock? */ 937 subdir = find_subdir(dir, name, namelen); 938 if (!IS_ERR(subdir)) 939 goto found; 940 if (PTR_ERR(subdir) != -ENOENT) 941 goto failed; 942 943 /* Nope. Use the our freshly made directory entry. */ 944 err = insert_header(dir, &new->header); 945 subdir = ERR_PTR(err); 946 if (err) 947 goto failed; 948 subdir = new; 949 found: 950 subdir->header.nreg++; 951 failed: 952 if (IS_ERR(subdir)) { 953 pr_err("sysctl could not get directory: "); 954 sysctl_print_dir(dir); 955 pr_cont("/%*.*s %ld\n", 956 namelen, namelen, name, PTR_ERR(subdir)); 957 } 958 drop_sysctl_table(&dir->header); 959 if (new) 960 drop_sysctl_table(&new->header); 961 spin_unlock(&sysctl_lock); 962 return subdir; 963 } 964 965 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir) 966 { 967 struct ctl_dir *parent; 968 const char *procname; 969 if (!dir->header.parent) 970 return &set->dir; 971 parent = xlate_dir(set, dir->header.parent); 972 if (IS_ERR(parent)) 973 return parent; 974 procname = dir->header.ctl_table[0].procname; 975 return find_subdir(parent, procname, strlen(procname)); 976 } 977 978 static int sysctl_follow_link(struct ctl_table_header **phead, 979 struct ctl_table **pentry, struct nsproxy *namespaces) 980 { 981 struct ctl_table_header *head; 982 struct ctl_table_root *root; 983 struct ctl_table_set *set; 984 struct ctl_table *entry; 985 struct ctl_dir *dir; 986 int ret; 987 988 ret = 0; 989 spin_lock(&sysctl_lock); 990 root = (*pentry)->data; 991 set = lookup_header_set(root, namespaces); 992 dir = xlate_dir(set, (*phead)->parent); 993 if (IS_ERR(dir)) 994 ret = PTR_ERR(dir); 995 else { 996 const char *procname = (*pentry)->procname; 997 head = NULL; 998 entry = find_entry(&head, dir, procname, strlen(procname)); 999 ret = -ENOENT; 1000 if (entry && use_table(head)) { 1001 unuse_table(*phead); 1002 *phead = head; 1003 *pentry = entry; 1004 ret = 0; 1005 } 1006 } 1007 1008 spin_unlock(&sysctl_lock); 1009 return ret; 1010 } 1011 1012 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...) 1013 { 1014 struct va_format vaf; 1015 va_list args; 1016 1017 va_start(args, fmt); 1018 vaf.fmt = fmt; 1019 vaf.va = &args; 1020 1021 pr_err("sysctl table check failed: %s/%s %pV\n", 1022 path, table->procname, &vaf); 1023 1024 va_end(args); 1025 return -EINVAL; 1026 } 1027 1028 static int sysctl_check_table(const char *path, struct ctl_table *table) 1029 { 1030 int err = 0; 1031 for (; table->procname; table++) { 1032 if (table->child) 1033 err = sysctl_err(path, table, "Not a file"); 1034 1035 if ((table->proc_handler == proc_dostring) || 1036 (table->proc_handler == proc_dointvec) || 1037 (table->proc_handler == proc_dointvec_minmax) || 1038 (table->proc_handler == proc_dointvec_jiffies) || 1039 (table->proc_handler == proc_dointvec_userhz_jiffies) || 1040 (table->proc_handler == proc_dointvec_ms_jiffies) || 1041 (table->proc_handler == proc_doulongvec_minmax) || 1042 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) { 1043 if (!table->data) 1044 err = sysctl_err(path, table, "No data"); 1045 if (!table->maxlen) 1046 err = sysctl_err(path, table, "No maxlen"); 1047 } 1048 if (!table->proc_handler) 1049 err = sysctl_err(path, table, "No proc_handler"); 1050 1051 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode) 1052 err = sysctl_err(path, table, "bogus .mode 0%o", 1053 table->mode); 1054 } 1055 return err; 1056 } 1057 1058 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table, 1059 struct ctl_table_root *link_root) 1060 { 1061 struct ctl_table *link_table, *entry, *link; 1062 struct ctl_table_header *links; 1063 struct ctl_node *node; 1064 char *link_name; 1065 int nr_entries, name_bytes; 1066 1067 name_bytes = 0; 1068 nr_entries = 0; 1069 for (entry = table; entry->procname; entry++) { 1070 nr_entries++; 1071 name_bytes += strlen(entry->procname) + 1; 1072 } 1073 1074 links = kzalloc(sizeof(struct ctl_table_header) + 1075 sizeof(struct ctl_node)*nr_entries + 1076 sizeof(struct ctl_table)*(nr_entries + 1) + 1077 name_bytes, 1078 GFP_KERNEL); 1079 1080 if (!links) 1081 return NULL; 1082 1083 node = (struct ctl_node *)(links + 1); 1084 link_table = (struct ctl_table *)(node + nr_entries); 1085 link_name = (char *)&link_table[nr_entries + 1]; 1086 1087 for (link = link_table, entry = table; entry->procname; link++, entry++) { 1088 int len = strlen(entry->procname) + 1; 1089 memcpy(link_name, entry->procname, len); 1090 link->procname = link_name; 1091 link->mode = S_IFLNK|S_IRWXUGO; 1092 link->data = link_root; 1093 link_name += len; 1094 } 1095 init_header(links, dir->header.root, dir->header.set, node, link_table); 1096 links->nreg = nr_entries; 1097 1098 return links; 1099 } 1100 1101 static bool get_links(struct ctl_dir *dir, 1102 struct ctl_table *table, struct ctl_table_root *link_root) 1103 { 1104 struct ctl_table_header *head; 1105 struct ctl_table *entry, *link; 1106 1107 /* Are there links available for every entry in table? */ 1108 for (entry = table; entry->procname; entry++) { 1109 const char *procname = entry->procname; 1110 link = find_entry(&head, dir, procname, strlen(procname)); 1111 if (!link) 1112 return false; 1113 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode)) 1114 continue; 1115 if (S_ISLNK(link->mode) && (link->data == link_root)) 1116 continue; 1117 return false; 1118 } 1119 1120 /* The checks passed. Increase the registration count on the links */ 1121 for (entry = table; entry->procname; entry++) { 1122 const char *procname = entry->procname; 1123 link = find_entry(&head, dir, procname, strlen(procname)); 1124 head->nreg++; 1125 } 1126 return true; 1127 } 1128 1129 static int insert_links(struct ctl_table_header *head) 1130 { 1131 struct ctl_table_set *root_set = &sysctl_table_root.default_set; 1132 struct ctl_dir *core_parent = NULL; 1133 struct ctl_table_header *links; 1134 int err; 1135 1136 if (head->set == root_set) 1137 return 0; 1138 1139 core_parent = xlate_dir(root_set, head->parent); 1140 if (IS_ERR(core_parent)) 1141 return 0; 1142 1143 if (get_links(core_parent, head->ctl_table, head->root)) 1144 return 0; 1145 1146 core_parent->header.nreg++; 1147 spin_unlock(&sysctl_lock); 1148 1149 links = new_links(core_parent, head->ctl_table, head->root); 1150 1151 spin_lock(&sysctl_lock); 1152 err = -ENOMEM; 1153 if (!links) 1154 goto out; 1155 1156 err = 0; 1157 if (get_links(core_parent, head->ctl_table, head->root)) { 1158 kfree(links); 1159 goto out; 1160 } 1161 1162 err = insert_header(core_parent, links); 1163 if (err) 1164 kfree(links); 1165 out: 1166 drop_sysctl_table(&core_parent->header); 1167 return err; 1168 } 1169 1170 /** 1171 * __register_sysctl_table - register a leaf sysctl table 1172 * @set: Sysctl tree to register on 1173 * @path: The path to the directory the sysctl table is in. 1174 * @table: the top-level table structure 1175 * 1176 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1177 * array. A completely 0 filled entry terminates the table. 1178 * 1179 * The members of the &struct ctl_table structure are used as follows: 1180 * 1181 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not 1182 * enter a sysctl file 1183 * 1184 * data - a pointer to data for use by proc_handler 1185 * 1186 * maxlen - the maximum size in bytes of the data 1187 * 1188 * mode - the file permissions for the /proc/sys file 1189 * 1190 * child - must be %NULL. 1191 * 1192 * proc_handler - the text handler routine (described below) 1193 * 1194 * extra1, extra2 - extra pointers usable by the proc handler routines 1195 * 1196 * Leaf nodes in the sysctl tree will be represented by a single file 1197 * under /proc; non-leaf nodes will be represented by directories. 1198 * 1199 * There must be a proc_handler routine for any terminal nodes. 1200 * Several default handlers are available to cover common cases - 1201 * 1202 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(), 1203 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(), 1204 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax() 1205 * 1206 * It is the handler's job to read the input buffer from user memory 1207 * and process it. The handler should return 0 on success. 1208 * 1209 * This routine returns %NULL on a failure to register, and a pointer 1210 * to the table header on success. 1211 */ 1212 struct ctl_table_header *__register_sysctl_table( 1213 struct ctl_table_set *set, 1214 const char *path, struct ctl_table *table) 1215 { 1216 struct ctl_table_root *root = set->dir.header.root; 1217 struct ctl_table_header *header; 1218 const char *name, *nextname; 1219 struct ctl_dir *dir; 1220 struct ctl_table *entry; 1221 struct ctl_node *node; 1222 int nr_entries = 0; 1223 1224 for (entry = table; entry->procname; entry++) 1225 nr_entries++; 1226 1227 header = kzalloc(sizeof(struct ctl_table_header) + 1228 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL); 1229 if (!header) 1230 return NULL; 1231 1232 node = (struct ctl_node *)(header + 1); 1233 init_header(header, root, set, node, table); 1234 if (sysctl_check_table(path, table)) 1235 goto fail; 1236 1237 spin_lock(&sysctl_lock); 1238 dir = &set->dir; 1239 /* Reference moved down the diretory tree get_subdir */ 1240 dir->header.nreg++; 1241 spin_unlock(&sysctl_lock); 1242 1243 /* Find the directory for the ctl_table */ 1244 for (name = path; name; name = nextname) { 1245 int namelen; 1246 nextname = strchr(name, '/'); 1247 if (nextname) { 1248 namelen = nextname - name; 1249 nextname++; 1250 } else { 1251 namelen = strlen(name); 1252 } 1253 if (namelen == 0) 1254 continue; 1255 1256 dir = get_subdir(dir, name, namelen); 1257 if (IS_ERR(dir)) 1258 goto fail; 1259 } 1260 1261 spin_lock(&sysctl_lock); 1262 if (insert_header(dir, header)) 1263 goto fail_put_dir_locked; 1264 1265 drop_sysctl_table(&dir->header); 1266 spin_unlock(&sysctl_lock); 1267 1268 return header; 1269 1270 fail_put_dir_locked: 1271 drop_sysctl_table(&dir->header); 1272 spin_unlock(&sysctl_lock); 1273 fail: 1274 kfree(header); 1275 dump_stack(); 1276 return NULL; 1277 } 1278 1279 /** 1280 * register_sysctl - register a sysctl table 1281 * @path: The path to the directory the sysctl table is in. 1282 * @table: the table structure 1283 * 1284 * Register a sysctl table. @table should be a filled in ctl_table 1285 * array. A completely 0 filled entry terminates the table. 1286 * 1287 * See __register_sysctl_table for more details. 1288 */ 1289 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table) 1290 { 1291 return __register_sysctl_table(&sysctl_table_root.default_set, 1292 path, table); 1293 } 1294 EXPORT_SYMBOL(register_sysctl); 1295 1296 static char *append_path(const char *path, char *pos, const char *name) 1297 { 1298 int namelen; 1299 namelen = strlen(name); 1300 if (((pos - path) + namelen + 2) >= PATH_MAX) 1301 return NULL; 1302 memcpy(pos, name, namelen); 1303 pos[namelen] = '/'; 1304 pos[namelen + 1] = '\0'; 1305 pos += namelen + 1; 1306 return pos; 1307 } 1308 1309 static int count_subheaders(struct ctl_table *table) 1310 { 1311 int has_files = 0; 1312 int nr_subheaders = 0; 1313 struct ctl_table *entry; 1314 1315 /* special case: no directory and empty directory */ 1316 if (!table || !table->procname) 1317 return 1; 1318 1319 for (entry = table; entry->procname; entry++) { 1320 if (entry->child) 1321 nr_subheaders += count_subheaders(entry->child); 1322 else 1323 has_files = 1; 1324 } 1325 return nr_subheaders + has_files; 1326 } 1327 1328 static int register_leaf_sysctl_tables(const char *path, char *pos, 1329 struct ctl_table_header ***subheader, struct ctl_table_set *set, 1330 struct ctl_table *table) 1331 { 1332 struct ctl_table *ctl_table_arg = NULL; 1333 struct ctl_table *entry, *files; 1334 int nr_files = 0; 1335 int nr_dirs = 0; 1336 int err = -ENOMEM; 1337 1338 for (entry = table; entry->procname; entry++) { 1339 if (entry->child) 1340 nr_dirs++; 1341 else 1342 nr_files++; 1343 } 1344 1345 files = table; 1346 /* If there are mixed files and directories we need a new table */ 1347 if (nr_dirs && nr_files) { 1348 struct ctl_table *new; 1349 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1), 1350 GFP_KERNEL); 1351 if (!files) 1352 goto out; 1353 1354 ctl_table_arg = files; 1355 for (new = files, entry = table; entry->procname; entry++) { 1356 if (entry->child) 1357 continue; 1358 *new = *entry; 1359 new++; 1360 } 1361 } 1362 1363 /* Register everything except a directory full of subdirectories */ 1364 if (nr_files || !nr_dirs) { 1365 struct ctl_table_header *header; 1366 header = __register_sysctl_table(set, path, files); 1367 if (!header) { 1368 kfree(ctl_table_arg); 1369 goto out; 1370 } 1371 1372 /* Remember if we need to free the file table */ 1373 header->ctl_table_arg = ctl_table_arg; 1374 **subheader = header; 1375 (*subheader)++; 1376 } 1377 1378 /* Recurse into the subdirectories. */ 1379 for (entry = table; entry->procname; entry++) { 1380 char *child_pos; 1381 1382 if (!entry->child) 1383 continue; 1384 1385 err = -ENAMETOOLONG; 1386 child_pos = append_path(path, pos, entry->procname); 1387 if (!child_pos) 1388 goto out; 1389 1390 err = register_leaf_sysctl_tables(path, child_pos, subheader, 1391 set, entry->child); 1392 pos[0] = '\0'; 1393 if (err) 1394 goto out; 1395 } 1396 err = 0; 1397 out: 1398 /* On failure our caller will unregister all registered subheaders */ 1399 return err; 1400 } 1401 1402 /** 1403 * __register_sysctl_paths - register a sysctl table hierarchy 1404 * @set: Sysctl tree to register on 1405 * @path: The path to the directory the sysctl table is in. 1406 * @table: the top-level table structure 1407 * 1408 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1409 * array. A completely 0 filled entry terminates the table. 1410 * 1411 * See __register_sysctl_table for more details. 1412 */ 1413 struct ctl_table_header *__register_sysctl_paths( 1414 struct ctl_table_set *set, 1415 const struct ctl_path *path, struct ctl_table *table) 1416 { 1417 struct ctl_table *ctl_table_arg = table; 1418 int nr_subheaders = count_subheaders(table); 1419 struct ctl_table_header *header = NULL, **subheaders, **subheader; 1420 const struct ctl_path *component; 1421 char *new_path, *pos; 1422 1423 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL); 1424 if (!new_path) 1425 return NULL; 1426 1427 pos[0] = '\0'; 1428 for (component = path; component->procname; component++) { 1429 pos = append_path(new_path, pos, component->procname); 1430 if (!pos) 1431 goto out; 1432 } 1433 while (table->procname && table->child && !table[1].procname) { 1434 pos = append_path(new_path, pos, table->procname); 1435 if (!pos) 1436 goto out; 1437 table = table->child; 1438 } 1439 if (nr_subheaders == 1) { 1440 header = __register_sysctl_table(set, new_path, table); 1441 if (header) 1442 header->ctl_table_arg = ctl_table_arg; 1443 } else { 1444 header = kzalloc(sizeof(*header) + 1445 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL); 1446 if (!header) 1447 goto out; 1448 1449 subheaders = (struct ctl_table_header **) (header + 1); 1450 subheader = subheaders; 1451 header->ctl_table_arg = ctl_table_arg; 1452 1453 if (register_leaf_sysctl_tables(new_path, pos, &subheader, 1454 set, table)) 1455 goto err_register_leaves; 1456 } 1457 1458 out: 1459 kfree(new_path); 1460 return header; 1461 1462 err_register_leaves: 1463 while (subheader > subheaders) { 1464 struct ctl_table_header *subh = *(--subheader); 1465 struct ctl_table *table = subh->ctl_table_arg; 1466 unregister_sysctl_table(subh); 1467 kfree(table); 1468 } 1469 kfree(header); 1470 header = NULL; 1471 goto out; 1472 } 1473 1474 /** 1475 * register_sysctl_table_path - register a sysctl table hierarchy 1476 * @path: The path to the directory the sysctl table is in. 1477 * @table: the top-level table structure 1478 * 1479 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1480 * array. A completely 0 filled entry terminates the table. 1481 * 1482 * See __register_sysctl_paths for more details. 1483 */ 1484 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, 1485 struct ctl_table *table) 1486 { 1487 return __register_sysctl_paths(&sysctl_table_root.default_set, 1488 path, table); 1489 } 1490 EXPORT_SYMBOL(register_sysctl_paths); 1491 1492 /** 1493 * register_sysctl_table - register a sysctl table hierarchy 1494 * @table: the top-level table structure 1495 * 1496 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1497 * array. A completely 0 filled entry terminates the table. 1498 * 1499 * See register_sysctl_paths for more details. 1500 */ 1501 struct ctl_table_header *register_sysctl_table(struct ctl_table *table) 1502 { 1503 static const struct ctl_path null_path[] = { {} }; 1504 1505 return register_sysctl_paths(null_path, table); 1506 } 1507 EXPORT_SYMBOL(register_sysctl_table); 1508 1509 static void put_links(struct ctl_table_header *header) 1510 { 1511 struct ctl_table_set *root_set = &sysctl_table_root.default_set; 1512 struct ctl_table_root *root = header->root; 1513 struct ctl_dir *parent = header->parent; 1514 struct ctl_dir *core_parent; 1515 struct ctl_table *entry; 1516 1517 if (header->set == root_set) 1518 return; 1519 1520 core_parent = xlate_dir(root_set, parent); 1521 if (IS_ERR(core_parent)) 1522 return; 1523 1524 for (entry = header->ctl_table; entry->procname; entry++) { 1525 struct ctl_table_header *link_head; 1526 struct ctl_table *link; 1527 const char *name = entry->procname; 1528 1529 link = find_entry(&link_head, core_parent, name, strlen(name)); 1530 if (link && 1531 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) || 1532 (S_ISLNK(link->mode) && (link->data == root)))) { 1533 drop_sysctl_table(link_head); 1534 } 1535 else { 1536 pr_err("sysctl link missing during unregister: "); 1537 sysctl_print_dir(parent); 1538 pr_cont("/%s\n", name); 1539 } 1540 } 1541 } 1542 1543 static void drop_sysctl_table(struct ctl_table_header *header) 1544 { 1545 struct ctl_dir *parent = header->parent; 1546 1547 if (--header->nreg) 1548 return; 1549 1550 put_links(header); 1551 start_unregistering(header); 1552 if (!--header->count) 1553 kfree_rcu(header, rcu); 1554 1555 if (parent) 1556 drop_sysctl_table(&parent->header); 1557 } 1558 1559 /** 1560 * unregister_sysctl_table - unregister a sysctl table hierarchy 1561 * @header: the header returned from register_sysctl_table 1562 * 1563 * Unregisters the sysctl table and all children. proc entries may not 1564 * actually be removed until they are no longer used by anyone. 1565 */ 1566 void unregister_sysctl_table(struct ctl_table_header * header) 1567 { 1568 int nr_subheaders; 1569 might_sleep(); 1570 1571 if (header == NULL) 1572 return; 1573 1574 nr_subheaders = count_subheaders(header->ctl_table_arg); 1575 if (unlikely(nr_subheaders > 1)) { 1576 struct ctl_table_header **subheaders; 1577 int i; 1578 1579 subheaders = (struct ctl_table_header **)(header + 1); 1580 for (i = nr_subheaders -1; i >= 0; i--) { 1581 struct ctl_table_header *subh = subheaders[i]; 1582 struct ctl_table *table = subh->ctl_table_arg; 1583 unregister_sysctl_table(subh); 1584 kfree(table); 1585 } 1586 kfree(header); 1587 return; 1588 } 1589 1590 spin_lock(&sysctl_lock); 1591 drop_sysctl_table(header); 1592 spin_unlock(&sysctl_lock); 1593 } 1594 EXPORT_SYMBOL(unregister_sysctl_table); 1595 1596 void setup_sysctl_set(struct ctl_table_set *set, 1597 struct ctl_table_root *root, 1598 int (*is_seen)(struct ctl_table_set *)) 1599 { 1600 memset(set, 0, sizeof(*set)); 1601 set->is_seen = is_seen; 1602 init_header(&set->dir.header, root, set, NULL, root_table); 1603 } 1604 1605 void retire_sysctl_set(struct ctl_table_set *set) 1606 { 1607 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root)); 1608 } 1609 1610 int __init proc_sys_init(void) 1611 { 1612 struct proc_dir_entry *proc_sys_root; 1613 1614 proc_sys_root = proc_mkdir("sys", NULL); 1615 proc_sys_root->proc_iops = &proc_sys_dir_operations; 1616 proc_sys_root->proc_fops = &proc_sys_dir_file_operations; 1617 proc_sys_root->nlink = 0; 1618 1619 return sysctl_init(); 1620 } 1621