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 child = d_alloc(dir, &qname); 631 if (child) { 632 inode = proc_sys_make_inode(dir->d_sb, head, table); 633 if (!inode) { 634 dput(child); 635 return false; 636 } else { 637 d_set_d_op(child, &proc_sys_dentry_operations); 638 d_add(child, inode); 639 } 640 } else { 641 return false; 642 } 643 } 644 inode = d_inode(child); 645 ino = inode->i_ino; 646 type = inode->i_mode >> 12; 647 dput(child); 648 return dir_emit(ctx, qname.name, qname.len, ino, type); 649 } 650 651 static bool proc_sys_link_fill_cache(struct file *file, 652 struct dir_context *ctx, 653 struct ctl_table_header *head, 654 struct ctl_table *table) 655 { 656 bool ret = true; 657 head = sysctl_head_grab(head); 658 659 if (S_ISLNK(table->mode)) { 660 /* It is not an error if we can not follow the link ignore it */ 661 int err = sysctl_follow_link(&head, &table, current->nsproxy); 662 if (err) 663 goto out; 664 } 665 666 ret = proc_sys_fill_cache(file, ctx, head, table); 667 out: 668 sysctl_head_finish(head); 669 return ret; 670 } 671 672 static int scan(struct ctl_table_header *head, struct ctl_table *table, 673 unsigned long *pos, struct file *file, 674 struct dir_context *ctx) 675 { 676 bool res; 677 678 if ((*pos)++ < ctx->pos) 679 return true; 680 681 if (unlikely(S_ISLNK(table->mode))) 682 res = proc_sys_link_fill_cache(file, ctx, head, table); 683 else 684 res = proc_sys_fill_cache(file, ctx, head, table); 685 686 if (res) 687 ctx->pos = *pos; 688 689 return res; 690 } 691 692 static int proc_sys_readdir(struct file *file, struct dir_context *ctx) 693 { 694 struct ctl_table_header *head = grab_header(file_inode(file)); 695 struct ctl_table_header *h = NULL; 696 struct ctl_table *entry; 697 struct ctl_dir *ctl_dir; 698 unsigned long pos; 699 700 if (IS_ERR(head)) 701 return PTR_ERR(head); 702 703 ctl_dir = container_of(head, struct ctl_dir, header); 704 705 if (!dir_emit_dots(file, ctx)) 706 return 0; 707 708 pos = 2; 709 710 for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) { 711 if (!scan(h, entry, &pos, file, ctx)) { 712 sysctl_head_finish(h); 713 break; 714 } 715 } 716 sysctl_head_finish(head); 717 return 0; 718 } 719 720 static int proc_sys_permission(struct inode *inode, int mask) 721 { 722 /* 723 * sysctl entries that are not writeable, 724 * are _NOT_ writeable, capabilities or not. 725 */ 726 struct ctl_table_header *head; 727 struct ctl_table *table; 728 int error; 729 730 /* Executable files are not allowed under /proc/sys/ */ 731 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) 732 return -EACCES; 733 734 head = grab_header(inode); 735 if (IS_ERR(head)) 736 return PTR_ERR(head); 737 738 table = PROC_I(inode)->sysctl_entry; 739 if (!table) /* global root - r-xr-xr-x */ 740 error = mask & MAY_WRITE ? -EACCES : 0; 741 else /* Use the permissions on the sysctl table entry */ 742 error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK); 743 744 sysctl_head_finish(head); 745 return error; 746 } 747 748 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr) 749 { 750 struct inode *inode = d_inode(dentry); 751 int error; 752 753 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) 754 return -EPERM; 755 756 error = inode_change_ok(inode, attr); 757 if (error) 758 return error; 759 760 setattr_copy(inode, attr); 761 mark_inode_dirty(inode); 762 return 0; 763 } 764 765 static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) 766 { 767 struct inode *inode = d_inode(dentry); 768 struct ctl_table_header *head = grab_header(inode); 769 struct ctl_table *table = PROC_I(inode)->sysctl_entry; 770 771 if (IS_ERR(head)) 772 return PTR_ERR(head); 773 774 generic_fillattr(inode, stat); 775 if (table) 776 stat->mode = (stat->mode & S_IFMT) | table->mode; 777 778 sysctl_head_finish(head); 779 return 0; 780 } 781 782 static const struct file_operations proc_sys_file_operations = { 783 .open = proc_sys_open, 784 .poll = proc_sys_poll, 785 .read = proc_sys_read, 786 .write = proc_sys_write, 787 .llseek = default_llseek, 788 }; 789 790 static const struct file_operations proc_sys_dir_file_operations = { 791 .read = generic_read_dir, 792 .iterate = proc_sys_readdir, 793 .llseek = generic_file_llseek, 794 }; 795 796 static const struct inode_operations proc_sys_inode_operations = { 797 .permission = proc_sys_permission, 798 .setattr = proc_sys_setattr, 799 .getattr = proc_sys_getattr, 800 }; 801 802 static const struct inode_operations proc_sys_dir_operations = { 803 .lookup = proc_sys_lookup, 804 .permission = proc_sys_permission, 805 .setattr = proc_sys_setattr, 806 .getattr = proc_sys_getattr, 807 }; 808 809 static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags) 810 { 811 if (flags & LOOKUP_RCU) 812 return -ECHILD; 813 return !PROC_I(d_inode(dentry))->sysctl->unregistering; 814 } 815 816 static int proc_sys_delete(const struct dentry *dentry) 817 { 818 return !!PROC_I(d_inode(dentry))->sysctl->unregistering; 819 } 820 821 static int sysctl_is_seen(struct ctl_table_header *p) 822 { 823 struct ctl_table_set *set = p->set; 824 int res; 825 spin_lock(&sysctl_lock); 826 if (p->unregistering) 827 res = 0; 828 else if (!set->is_seen) 829 res = 1; 830 else 831 res = set->is_seen(set); 832 spin_unlock(&sysctl_lock); 833 return res; 834 } 835 836 static int proc_sys_compare(const struct dentry *parent, const struct dentry *dentry, 837 unsigned int len, const char *str, const struct qstr *name) 838 { 839 struct ctl_table_header *head; 840 struct inode *inode; 841 842 /* Although proc doesn't have negative dentries, rcu-walk means 843 * that inode here can be NULL */ 844 /* AV: can it, indeed? */ 845 inode = d_inode_rcu(dentry); 846 if (!inode) 847 return 1; 848 if (name->len != len) 849 return 1; 850 if (memcmp(name->name, str, len)) 851 return 1; 852 head = rcu_dereference(PROC_I(inode)->sysctl); 853 return !head || !sysctl_is_seen(head); 854 } 855 856 static const struct dentry_operations proc_sys_dentry_operations = { 857 .d_revalidate = proc_sys_revalidate, 858 .d_delete = proc_sys_delete, 859 .d_compare = proc_sys_compare, 860 }; 861 862 static struct ctl_dir *find_subdir(struct ctl_dir *dir, 863 const char *name, int namelen) 864 { 865 struct ctl_table_header *head; 866 struct ctl_table *entry; 867 868 entry = find_entry(&head, dir, name, namelen); 869 if (!entry) 870 return ERR_PTR(-ENOENT); 871 if (!S_ISDIR(entry->mode)) 872 return ERR_PTR(-ENOTDIR); 873 return container_of(head, struct ctl_dir, header); 874 } 875 876 static struct ctl_dir *new_dir(struct ctl_table_set *set, 877 const char *name, int namelen) 878 { 879 struct ctl_table *table; 880 struct ctl_dir *new; 881 struct ctl_node *node; 882 char *new_name; 883 884 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) + 885 sizeof(struct ctl_table)*2 + namelen + 1, 886 GFP_KERNEL); 887 if (!new) 888 return NULL; 889 890 node = (struct ctl_node *)(new + 1); 891 table = (struct ctl_table *)(node + 1); 892 new_name = (char *)(table + 2); 893 memcpy(new_name, name, namelen); 894 new_name[namelen] = '\0'; 895 table[0].procname = new_name; 896 table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO; 897 init_header(&new->header, set->dir.header.root, set, node, table); 898 899 return new; 900 } 901 902 /** 903 * get_subdir - find or create a subdir with the specified name. 904 * @dir: Directory to create the subdirectory in 905 * @name: The name of the subdirectory to find or create 906 * @namelen: The length of name 907 * 908 * Takes a directory with an elevated reference count so we know that 909 * if we drop the lock the directory will not go away. Upon success 910 * the reference is moved from @dir to the returned subdirectory. 911 * Upon error an error code is returned and the reference on @dir is 912 * simply dropped. 913 */ 914 static struct ctl_dir *get_subdir(struct ctl_dir *dir, 915 const char *name, int namelen) 916 { 917 struct ctl_table_set *set = dir->header.set; 918 struct ctl_dir *subdir, *new = NULL; 919 int err; 920 921 spin_lock(&sysctl_lock); 922 subdir = find_subdir(dir, name, namelen); 923 if (!IS_ERR(subdir)) 924 goto found; 925 if (PTR_ERR(subdir) != -ENOENT) 926 goto failed; 927 928 spin_unlock(&sysctl_lock); 929 new = new_dir(set, name, namelen); 930 spin_lock(&sysctl_lock); 931 subdir = ERR_PTR(-ENOMEM); 932 if (!new) 933 goto failed; 934 935 /* Was the subdir added while we dropped the lock? */ 936 subdir = find_subdir(dir, name, namelen); 937 if (!IS_ERR(subdir)) 938 goto found; 939 if (PTR_ERR(subdir) != -ENOENT) 940 goto failed; 941 942 /* Nope. Use the our freshly made directory entry. */ 943 err = insert_header(dir, &new->header); 944 subdir = ERR_PTR(err); 945 if (err) 946 goto failed; 947 subdir = new; 948 found: 949 subdir->header.nreg++; 950 failed: 951 if (unlikely(IS_ERR(subdir))) { 952 pr_err("sysctl could not get directory: "); 953 sysctl_print_dir(dir); 954 pr_cont("/%*.*s %ld\n", 955 namelen, namelen, name, PTR_ERR(subdir)); 956 } 957 drop_sysctl_table(&dir->header); 958 if (new) 959 drop_sysctl_table(&new->header); 960 spin_unlock(&sysctl_lock); 961 return subdir; 962 } 963 964 static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir) 965 { 966 struct ctl_dir *parent; 967 const char *procname; 968 if (!dir->header.parent) 969 return &set->dir; 970 parent = xlate_dir(set, dir->header.parent); 971 if (IS_ERR(parent)) 972 return parent; 973 procname = dir->header.ctl_table[0].procname; 974 return find_subdir(parent, procname, strlen(procname)); 975 } 976 977 static int sysctl_follow_link(struct ctl_table_header **phead, 978 struct ctl_table **pentry, struct nsproxy *namespaces) 979 { 980 struct ctl_table_header *head; 981 struct ctl_table_root *root; 982 struct ctl_table_set *set; 983 struct ctl_table *entry; 984 struct ctl_dir *dir; 985 int ret; 986 987 ret = 0; 988 spin_lock(&sysctl_lock); 989 root = (*pentry)->data; 990 set = lookup_header_set(root, namespaces); 991 dir = xlate_dir(set, (*phead)->parent); 992 if (IS_ERR(dir)) 993 ret = PTR_ERR(dir); 994 else { 995 const char *procname = (*pentry)->procname; 996 head = NULL; 997 entry = find_entry(&head, dir, procname, strlen(procname)); 998 ret = -ENOENT; 999 if (entry && use_table(head)) { 1000 unuse_table(*phead); 1001 *phead = head; 1002 *pentry = entry; 1003 ret = 0; 1004 } 1005 } 1006 1007 spin_unlock(&sysctl_lock); 1008 return ret; 1009 } 1010 1011 static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...) 1012 { 1013 struct va_format vaf; 1014 va_list args; 1015 1016 va_start(args, fmt); 1017 vaf.fmt = fmt; 1018 vaf.va = &args; 1019 1020 pr_err("sysctl table check failed: %s/%s %pV\n", 1021 path, table->procname, &vaf); 1022 1023 va_end(args); 1024 return -EINVAL; 1025 } 1026 1027 static int sysctl_check_table(const char *path, struct ctl_table *table) 1028 { 1029 int err = 0; 1030 for (; table->procname; table++) { 1031 if (table->child) 1032 err = sysctl_err(path, table, "Not a file"); 1033 1034 if ((table->proc_handler == proc_dostring) || 1035 (table->proc_handler == proc_dointvec) || 1036 (table->proc_handler == proc_dointvec_minmax) || 1037 (table->proc_handler == proc_dointvec_jiffies) || 1038 (table->proc_handler == proc_dointvec_userhz_jiffies) || 1039 (table->proc_handler == proc_dointvec_ms_jiffies) || 1040 (table->proc_handler == proc_doulongvec_minmax) || 1041 (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) { 1042 if (!table->data) 1043 err = sysctl_err(path, table, "No data"); 1044 if (!table->maxlen) 1045 err = sysctl_err(path, table, "No maxlen"); 1046 } 1047 if (!table->proc_handler) 1048 err = sysctl_err(path, table, "No proc_handler"); 1049 1050 if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode) 1051 err = sysctl_err(path, table, "bogus .mode 0%o", 1052 table->mode); 1053 } 1054 return err; 1055 } 1056 1057 static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table, 1058 struct ctl_table_root *link_root) 1059 { 1060 struct ctl_table *link_table, *entry, *link; 1061 struct ctl_table_header *links; 1062 struct ctl_node *node; 1063 char *link_name; 1064 int nr_entries, name_bytes; 1065 1066 name_bytes = 0; 1067 nr_entries = 0; 1068 for (entry = table; entry->procname; entry++) { 1069 nr_entries++; 1070 name_bytes += strlen(entry->procname) + 1; 1071 } 1072 1073 links = kzalloc(sizeof(struct ctl_table_header) + 1074 sizeof(struct ctl_node)*nr_entries + 1075 sizeof(struct ctl_table)*(nr_entries + 1) + 1076 name_bytes, 1077 GFP_KERNEL); 1078 1079 if (!links) 1080 return NULL; 1081 1082 node = (struct ctl_node *)(links + 1); 1083 link_table = (struct ctl_table *)(node + nr_entries); 1084 link_name = (char *)&link_table[nr_entries + 1]; 1085 1086 for (link = link_table, entry = table; entry->procname; link++, entry++) { 1087 int len = strlen(entry->procname) + 1; 1088 memcpy(link_name, entry->procname, len); 1089 link->procname = link_name; 1090 link->mode = S_IFLNK|S_IRWXUGO; 1091 link->data = link_root; 1092 link_name += len; 1093 } 1094 init_header(links, dir->header.root, dir->header.set, node, link_table); 1095 links->nreg = nr_entries; 1096 1097 return links; 1098 } 1099 1100 static bool get_links(struct ctl_dir *dir, 1101 struct ctl_table *table, struct ctl_table_root *link_root) 1102 { 1103 struct ctl_table_header *head; 1104 struct ctl_table *entry, *link; 1105 1106 /* Are there links available for every entry in table? */ 1107 for (entry = table; entry->procname; entry++) { 1108 const char *procname = entry->procname; 1109 link = find_entry(&head, dir, procname, strlen(procname)); 1110 if (!link) 1111 return false; 1112 if (S_ISDIR(link->mode) && S_ISDIR(entry->mode)) 1113 continue; 1114 if (S_ISLNK(link->mode) && (link->data == link_root)) 1115 continue; 1116 return false; 1117 } 1118 1119 /* The checks passed. Increase the registration count on the links */ 1120 for (entry = table; entry->procname; entry++) { 1121 const char *procname = entry->procname; 1122 link = find_entry(&head, dir, procname, strlen(procname)); 1123 head->nreg++; 1124 } 1125 return true; 1126 } 1127 1128 static int insert_links(struct ctl_table_header *head) 1129 { 1130 struct ctl_table_set *root_set = &sysctl_table_root.default_set; 1131 struct ctl_dir *core_parent = NULL; 1132 struct ctl_table_header *links; 1133 int err; 1134 1135 if (head->set == root_set) 1136 return 0; 1137 1138 core_parent = xlate_dir(root_set, head->parent); 1139 if (IS_ERR(core_parent)) 1140 return 0; 1141 1142 if (get_links(core_parent, head->ctl_table, head->root)) 1143 return 0; 1144 1145 core_parent->header.nreg++; 1146 spin_unlock(&sysctl_lock); 1147 1148 links = new_links(core_parent, head->ctl_table, head->root); 1149 1150 spin_lock(&sysctl_lock); 1151 err = -ENOMEM; 1152 if (!links) 1153 goto out; 1154 1155 err = 0; 1156 if (get_links(core_parent, head->ctl_table, head->root)) { 1157 kfree(links); 1158 goto out; 1159 } 1160 1161 err = insert_header(core_parent, links); 1162 if (err) 1163 kfree(links); 1164 out: 1165 drop_sysctl_table(&core_parent->header); 1166 return err; 1167 } 1168 1169 /** 1170 * __register_sysctl_table - register a leaf sysctl table 1171 * @set: Sysctl tree to register on 1172 * @path: The path to the directory the sysctl table is in. 1173 * @table: the top-level table structure 1174 * 1175 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1176 * array. A completely 0 filled entry terminates the table. 1177 * 1178 * The members of the &struct ctl_table structure are used as follows: 1179 * 1180 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not 1181 * enter a sysctl file 1182 * 1183 * data - a pointer to data for use by proc_handler 1184 * 1185 * maxlen - the maximum size in bytes of the data 1186 * 1187 * mode - the file permissions for the /proc/sys file 1188 * 1189 * child - must be %NULL. 1190 * 1191 * proc_handler - the text handler routine (described below) 1192 * 1193 * extra1, extra2 - extra pointers usable by the proc handler routines 1194 * 1195 * Leaf nodes in the sysctl tree will be represented by a single file 1196 * under /proc; non-leaf nodes will be represented by directories. 1197 * 1198 * There must be a proc_handler routine for any terminal nodes. 1199 * Several default handlers are available to cover common cases - 1200 * 1201 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(), 1202 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(), 1203 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax() 1204 * 1205 * It is the handler's job to read the input buffer from user memory 1206 * and process it. The handler should return 0 on success. 1207 * 1208 * This routine returns %NULL on a failure to register, and a pointer 1209 * to the table header on success. 1210 */ 1211 struct ctl_table_header *__register_sysctl_table( 1212 struct ctl_table_set *set, 1213 const char *path, struct ctl_table *table) 1214 { 1215 struct ctl_table_root *root = set->dir.header.root; 1216 struct ctl_table_header *header; 1217 const char *name, *nextname; 1218 struct ctl_dir *dir; 1219 struct ctl_table *entry; 1220 struct ctl_node *node; 1221 int nr_entries = 0; 1222 1223 for (entry = table; entry->procname; entry++) 1224 nr_entries++; 1225 1226 header = kzalloc(sizeof(struct ctl_table_header) + 1227 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL); 1228 if (!header) 1229 return NULL; 1230 1231 node = (struct ctl_node *)(header + 1); 1232 init_header(header, root, set, node, table); 1233 if (sysctl_check_table(path, table)) 1234 goto fail; 1235 1236 spin_lock(&sysctl_lock); 1237 dir = &set->dir; 1238 /* Reference moved down the diretory tree get_subdir */ 1239 dir->header.nreg++; 1240 spin_unlock(&sysctl_lock); 1241 1242 /* Find the directory for the ctl_table */ 1243 for (name = path; name; name = nextname) { 1244 int namelen; 1245 nextname = strchr(name, '/'); 1246 if (nextname) { 1247 namelen = nextname - name; 1248 nextname++; 1249 } else { 1250 namelen = strlen(name); 1251 } 1252 if (namelen == 0) 1253 continue; 1254 1255 dir = get_subdir(dir, name, namelen); 1256 if (IS_ERR(dir)) 1257 goto fail; 1258 } 1259 1260 spin_lock(&sysctl_lock); 1261 if (insert_header(dir, header)) 1262 goto fail_put_dir_locked; 1263 1264 drop_sysctl_table(&dir->header); 1265 spin_unlock(&sysctl_lock); 1266 1267 return header; 1268 1269 fail_put_dir_locked: 1270 drop_sysctl_table(&dir->header); 1271 spin_unlock(&sysctl_lock); 1272 fail: 1273 kfree(header); 1274 dump_stack(); 1275 return NULL; 1276 } 1277 1278 /** 1279 * register_sysctl - register a sysctl table 1280 * @path: The path to the directory the sysctl table is in. 1281 * @table: the table structure 1282 * 1283 * Register a sysctl table. @table should be a filled in ctl_table 1284 * array. A completely 0 filled entry terminates the table. 1285 * 1286 * See __register_sysctl_table for more details. 1287 */ 1288 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table) 1289 { 1290 return __register_sysctl_table(&sysctl_table_root.default_set, 1291 path, table); 1292 } 1293 EXPORT_SYMBOL(register_sysctl); 1294 1295 static char *append_path(const char *path, char *pos, const char *name) 1296 { 1297 int namelen; 1298 namelen = strlen(name); 1299 if (((pos - path) + namelen + 2) >= PATH_MAX) 1300 return NULL; 1301 memcpy(pos, name, namelen); 1302 pos[namelen] = '/'; 1303 pos[namelen + 1] = '\0'; 1304 pos += namelen + 1; 1305 return pos; 1306 } 1307 1308 static int count_subheaders(struct ctl_table *table) 1309 { 1310 int has_files = 0; 1311 int nr_subheaders = 0; 1312 struct ctl_table *entry; 1313 1314 /* special case: no directory and empty directory */ 1315 if (!table || !table->procname) 1316 return 1; 1317 1318 for (entry = table; entry->procname; entry++) { 1319 if (entry->child) 1320 nr_subheaders += count_subheaders(entry->child); 1321 else 1322 has_files = 1; 1323 } 1324 return nr_subheaders + has_files; 1325 } 1326 1327 static int register_leaf_sysctl_tables(const char *path, char *pos, 1328 struct ctl_table_header ***subheader, struct ctl_table_set *set, 1329 struct ctl_table *table) 1330 { 1331 struct ctl_table *ctl_table_arg = NULL; 1332 struct ctl_table *entry, *files; 1333 int nr_files = 0; 1334 int nr_dirs = 0; 1335 int err = -ENOMEM; 1336 1337 for (entry = table; entry->procname; entry++) { 1338 if (entry->child) 1339 nr_dirs++; 1340 else 1341 nr_files++; 1342 } 1343 1344 files = table; 1345 /* If there are mixed files and directories we need a new table */ 1346 if (nr_dirs && nr_files) { 1347 struct ctl_table *new; 1348 files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1), 1349 GFP_KERNEL); 1350 if (!files) 1351 goto out; 1352 1353 ctl_table_arg = files; 1354 for (new = files, entry = table; entry->procname; entry++) { 1355 if (entry->child) 1356 continue; 1357 *new = *entry; 1358 new++; 1359 } 1360 } 1361 1362 /* Register everything except a directory full of subdirectories */ 1363 if (nr_files || !nr_dirs) { 1364 struct ctl_table_header *header; 1365 header = __register_sysctl_table(set, path, files); 1366 if (!header) { 1367 kfree(ctl_table_arg); 1368 goto out; 1369 } 1370 1371 /* Remember if we need to free the file table */ 1372 header->ctl_table_arg = ctl_table_arg; 1373 **subheader = header; 1374 (*subheader)++; 1375 } 1376 1377 /* Recurse into the subdirectories. */ 1378 for (entry = table; entry->procname; entry++) { 1379 char *child_pos; 1380 1381 if (!entry->child) 1382 continue; 1383 1384 err = -ENAMETOOLONG; 1385 child_pos = append_path(path, pos, entry->procname); 1386 if (!child_pos) 1387 goto out; 1388 1389 err = register_leaf_sysctl_tables(path, child_pos, subheader, 1390 set, entry->child); 1391 pos[0] = '\0'; 1392 if (err) 1393 goto out; 1394 } 1395 err = 0; 1396 out: 1397 /* On failure our caller will unregister all registered subheaders */ 1398 return err; 1399 } 1400 1401 /** 1402 * __register_sysctl_paths - register a sysctl table hierarchy 1403 * @set: Sysctl tree to register on 1404 * @path: The path to the directory the sysctl table is in. 1405 * @table: the top-level table structure 1406 * 1407 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1408 * array. A completely 0 filled entry terminates the table. 1409 * 1410 * See __register_sysctl_table for more details. 1411 */ 1412 struct ctl_table_header *__register_sysctl_paths( 1413 struct ctl_table_set *set, 1414 const struct ctl_path *path, struct ctl_table *table) 1415 { 1416 struct ctl_table *ctl_table_arg = table; 1417 int nr_subheaders = count_subheaders(table); 1418 struct ctl_table_header *header = NULL, **subheaders, **subheader; 1419 const struct ctl_path *component; 1420 char *new_path, *pos; 1421 1422 pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL); 1423 if (!new_path) 1424 return NULL; 1425 1426 pos[0] = '\0'; 1427 for (component = path; component->procname; component++) { 1428 pos = append_path(new_path, pos, component->procname); 1429 if (!pos) 1430 goto out; 1431 } 1432 while (table->procname && table->child && !table[1].procname) { 1433 pos = append_path(new_path, pos, table->procname); 1434 if (!pos) 1435 goto out; 1436 table = table->child; 1437 } 1438 if (nr_subheaders == 1) { 1439 header = __register_sysctl_table(set, new_path, table); 1440 if (header) 1441 header->ctl_table_arg = ctl_table_arg; 1442 } else { 1443 header = kzalloc(sizeof(*header) + 1444 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL); 1445 if (!header) 1446 goto out; 1447 1448 subheaders = (struct ctl_table_header **) (header + 1); 1449 subheader = subheaders; 1450 header->ctl_table_arg = ctl_table_arg; 1451 1452 if (register_leaf_sysctl_tables(new_path, pos, &subheader, 1453 set, table)) 1454 goto err_register_leaves; 1455 } 1456 1457 out: 1458 kfree(new_path); 1459 return header; 1460 1461 err_register_leaves: 1462 while (subheader > subheaders) { 1463 struct ctl_table_header *subh = *(--subheader); 1464 struct ctl_table *table = subh->ctl_table_arg; 1465 unregister_sysctl_table(subh); 1466 kfree(table); 1467 } 1468 kfree(header); 1469 header = NULL; 1470 goto out; 1471 } 1472 1473 /** 1474 * register_sysctl_table_path - register a sysctl table hierarchy 1475 * @path: The path to the directory the sysctl table is in. 1476 * @table: the top-level table structure 1477 * 1478 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1479 * array. A completely 0 filled entry terminates the table. 1480 * 1481 * See __register_sysctl_paths for more details. 1482 */ 1483 struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path, 1484 struct ctl_table *table) 1485 { 1486 return __register_sysctl_paths(&sysctl_table_root.default_set, 1487 path, table); 1488 } 1489 EXPORT_SYMBOL(register_sysctl_paths); 1490 1491 /** 1492 * register_sysctl_table - register a sysctl table hierarchy 1493 * @table: the top-level table structure 1494 * 1495 * Register a sysctl table hierarchy. @table should be a filled in ctl_table 1496 * array. A completely 0 filled entry terminates the table. 1497 * 1498 * See register_sysctl_paths for more details. 1499 */ 1500 struct ctl_table_header *register_sysctl_table(struct ctl_table *table) 1501 { 1502 static const struct ctl_path null_path[] = { {} }; 1503 1504 return register_sysctl_paths(null_path, table); 1505 } 1506 EXPORT_SYMBOL(register_sysctl_table); 1507 1508 static void put_links(struct ctl_table_header *header) 1509 { 1510 struct ctl_table_set *root_set = &sysctl_table_root.default_set; 1511 struct ctl_table_root *root = header->root; 1512 struct ctl_dir *parent = header->parent; 1513 struct ctl_dir *core_parent; 1514 struct ctl_table *entry; 1515 1516 if (header->set == root_set) 1517 return; 1518 1519 core_parent = xlate_dir(root_set, parent); 1520 if (IS_ERR(core_parent)) 1521 return; 1522 1523 for (entry = header->ctl_table; entry->procname; entry++) { 1524 struct ctl_table_header *link_head; 1525 struct ctl_table *link; 1526 const char *name = entry->procname; 1527 1528 link = find_entry(&link_head, core_parent, name, strlen(name)); 1529 if (link && 1530 ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) || 1531 (S_ISLNK(link->mode) && (link->data == root)))) { 1532 drop_sysctl_table(link_head); 1533 } 1534 else { 1535 pr_err("sysctl link missing during unregister: "); 1536 sysctl_print_dir(parent); 1537 pr_cont("/%s\n", name); 1538 } 1539 } 1540 } 1541 1542 static void drop_sysctl_table(struct ctl_table_header *header) 1543 { 1544 struct ctl_dir *parent = header->parent; 1545 1546 if (--header->nreg) 1547 return; 1548 1549 put_links(header); 1550 start_unregistering(header); 1551 if (!--header->count) 1552 kfree_rcu(header, rcu); 1553 1554 if (parent) 1555 drop_sysctl_table(&parent->header); 1556 } 1557 1558 /** 1559 * unregister_sysctl_table - unregister a sysctl table hierarchy 1560 * @header: the header returned from register_sysctl_table 1561 * 1562 * Unregisters the sysctl table and all children. proc entries may not 1563 * actually be removed until they are no longer used by anyone. 1564 */ 1565 void unregister_sysctl_table(struct ctl_table_header * header) 1566 { 1567 int nr_subheaders; 1568 might_sleep(); 1569 1570 if (header == NULL) 1571 return; 1572 1573 nr_subheaders = count_subheaders(header->ctl_table_arg); 1574 if (unlikely(nr_subheaders > 1)) { 1575 struct ctl_table_header **subheaders; 1576 int i; 1577 1578 subheaders = (struct ctl_table_header **)(header + 1); 1579 for (i = nr_subheaders -1; i >= 0; i--) { 1580 struct ctl_table_header *subh = subheaders[i]; 1581 struct ctl_table *table = subh->ctl_table_arg; 1582 unregister_sysctl_table(subh); 1583 kfree(table); 1584 } 1585 kfree(header); 1586 return; 1587 } 1588 1589 spin_lock(&sysctl_lock); 1590 drop_sysctl_table(header); 1591 spin_unlock(&sysctl_lock); 1592 } 1593 EXPORT_SYMBOL(unregister_sysctl_table); 1594 1595 void setup_sysctl_set(struct ctl_table_set *set, 1596 struct ctl_table_root *root, 1597 int (*is_seen)(struct ctl_table_set *)) 1598 { 1599 memset(set, 0, sizeof(*set)); 1600 set->is_seen = is_seen; 1601 init_header(&set->dir.header, root, set, NULL, root_table); 1602 } 1603 1604 void retire_sysctl_set(struct ctl_table_set *set) 1605 { 1606 WARN_ON(!RB_EMPTY_ROOT(&set->dir.root)); 1607 } 1608 1609 int __init proc_sys_init(void) 1610 { 1611 struct proc_dir_entry *proc_sys_root; 1612 1613 proc_sys_root = proc_mkdir("sys", NULL); 1614 proc_sys_root->proc_iops = &proc_sys_dir_operations; 1615 proc_sys_root->proc_fops = &proc_sys_dir_file_operations; 1616 proc_sys_root->nlink = 0; 1617 1618 return sysctl_init(); 1619 } 1620