| 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 (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 | } |