1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * /proc/sys support |
4 | */ |
5 | #include <linux/init.h> |
6 | #include <linux/sysctl.h> |
7 | #include <linux/poll.h> |
8 | #include <linux/proc_fs.h> |
9 | #include <linux/printk.h> |
10 | #include <linux/security.h> |
11 | #include <linux/sched.h> |
12 | #include <linux/cred.h> |
13 | #include <linux/namei.h> |
14 | #include <linux/mm.h> |
15 | #include <linux/uio.h> |
16 | #include <linux/module.h> |
17 | #include <linux/bpf-cgroup.h> |
18 | #include <linux/mount.h> |
19 | #include <linux/kmemleak.h> |
20 | #include "internal.h" |
21 | |
22 | #define list_for_each_table_entry(entry, header) \ |
23 | entry = header->ctl_table; \ |
24 | for (size_t i = 0 ; i < header->ctl_table_size && entry->procname; ++i, entry++) |
25 | |
26 | static const struct dentry_operations proc_sys_dentry_operations; |
27 | static const struct file_operations proc_sys_file_operations; |
28 | static const struct inode_operations proc_sys_inode_operations; |
29 | static const struct file_operations proc_sys_dir_file_operations; |
30 | static const struct inode_operations proc_sys_dir_operations; |
31 | |
32 | /* Support for permanently empty directories */ |
33 | static struct ctl_table sysctl_mount_point[] = { |
34 | {.type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY } |
35 | }; |
36 | |
37 | /** |
38 | * register_sysctl_mount_point() - registers a sysctl mount point |
39 | * @path: path for the mount point |
40 | * |
41 | * Used to create a permanently empty directory to serve as mount point. |
42 | * There are some subtle but important permission checks this allows in the |
43 | * case of unprivileged mounts. |
44 | */ |
45 | struct ctl_table_header *register_sysctl_mount_point(const char *path) |
46 | { |
47 | return register_sysctl_sz(path, table: sysctl_mount_point, table_size: 0); |
48 | } |
49 | EXPORT_SYMBOL(register_sysctl_mount_point); |
50 | |
51 | #define sysctl_is_perm_empty_ctl_table(tptr) \ |
52 | (tptr[0].type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY) |
53 | #define (hptr) \ |
54 | (sysctl_is_perm_empty_ctl_table(hptr->ctl_table)) |
55 | #define (hptr) \ |
56 | (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY) |
57 | #define (hptr) \ |
58 | (hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_DEFAULT) |
59 | |
60 | void proc_sys_poll_notify(struct ctl_table_poll *poll) |
61 | { |
62 | if (!poll) |
63 | return; |
64 | |
65 | atomic_inc(v: &poll->event); |
66 | wake_up_interruptible(&poll->wait); |
67 | } |
68 | |
69 | static struct ctl_table root_table[] = { |
70 | { |
71 | .procname = "" , |
72 | .mode = S_IFDIR|S_IRUGO|S_IXUGO, |
73 | }, |
74 | { } |
75 | }; |
76 | static struct ctl_table_root sysctl_table_root = { |
77 | .default_set.dir.header = { |
78 | {{.count = 1, |
79 | .nreg = 1, |
80 | .ctl_table = root_table }}, |
81 | .ctl_table_arg = root_table, |
82 | .root = &sysctl_table_root, |
83 | .set = &sysctl_table_root.default_set, |
84 | }, |
85 | }; |
86 | |
87 | static DEFINE_SPINLOCK(sysctl_lock); |
88 | |
89 | static void drop_sysctl_table(struct ctl_table_header *); |
90 | static int sysctl_follow_link(struct ctl_table_header **phead, |
91 | struct ctl_table **pentry); |
92 | static int insert_links(struct ctl_table_header *head); |
93 | static void put_links(struct ctl_table_header *); |
94 | |
95 | static void sysctl_print_dir(struct ctl_dir *dir) |
96 | { |
97 | if (dir->header.parent) |
98 | sysctl_print_dir(dir: dir->header.parent); |
99 | pr_cont("%s/" , dir->header.ctl_table[0].procname); |
100 | } |
101 | |
102 | static int namecmp(const char *name1, int len1, const char *name2, int len2) |
103 | { |
104 | int cmp; |
105 | |
106 | cmp = memcmp(p: name1, q: name2, min(len1, len2)); |
107 | if (cmp == 0) |
108 | cmp = len1 - len2; |
109 | return cmp; |
110 | } |
111 | |
112 | /* Called under sysctl_lock */ |
113 | static struct ctl_table *find_entry(struct ctl_table_header **phead, |
114 | struct ctl_dir *dir, const char *name, int namelen) |
115 | { |
116 | struct ctl_table_header *head; |
117 | struct ctl_table *entry; |
118 | struct rb_node *node = dir->root.rb_node; |
119 | |
120 | while (node) |
121 | { |
122 | struct ctl_node *ctl_node; |
123 | const char *procname; |
124 | int cmp; |
125 | |
126 | ctl_node = rb_entry(node, struct ctl_node, node); |
127 | head = ctl_node->header; |
128 | entry = &head->ctl_table[ctl_node - head->node]; |
129 | procname = entry->procname; |
130 | |
131 | cmp = namecmp(name1: name, len1: namelen, name2: procname, strlen(procname)); |
132 | if (cmp < 0) |
133 | node = node->rb_left; |
134 | else if (cmp > 0) |
135 | node = node->rb_right; |
136 | else { |
137 | *phead = head; |
138 | return entry; |
139 | } |
140 | } |
141 | return NULL; |
142 | } |
143 | |
144 | static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry) |
145 | { |
146 | struct rb_node *node = &head->node[entry - head->ctl_table].node; |
147 | struct rb_node **p = &head->parent->root.rb_node; |
148 | struct rb_node *parent = NULL; |
149 | const char *name = entry->procname; |
150 | int namelen = strlen(name); |
151 | |
152 | while (*p) { |
153 | struct ctl_table_header *parent_head; |
154 | struct ctl_table *parent_entry; |
155 | struct ctl_node *parent_node; |
156 | const char *parent_name; |
157 | int cmp; |
158 | |
159 | parent = *p; |
160 | parent_node = rb_entry(parent, struct ctl_node, node); |
161 | parent_head = parent_node->header; |
162 | parent_entry = &parent_head->ctl_table[parent_node - parent_head->node]; |
163 | parent_name = parent_entry->procname; |
164 | |
165 | cmp = namecmp(name1: name, len1: namelen, name2: parent_name, strlen(parent_name)); |
166 | if (cmp < 0) |
167 | p = &(*p)->rb_left; |
168 | else if (cmp > 0) |
169 | p = &(*p)->rb_right; |
170 | else { |
171 | pr_err("sysctl duplicate entry: " ); |
172 | sysctl_print_dir(dir: head->parent); |
173 | pr_cont("%s\n" , entry->procname); |
174 | return -EEXIST; |
175 | } |
176 | } |
177 | |
178 | rb_link_node(node, parent, rb_link: p); |
179 | rb_insert_color(node, &head->parent->root); |
180 | return 0; |
181 | } |
182 | |
183 | static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry) |
184 | { |
185 | struct rb_node *node = &head->node[entry - head->ctl_table].node; |
186 | |
187 | rb_erase(node, &head->parent->root); |
188 | } |
189 | |
190 | static void (struct ctl_table_header *head, |
191 | struct ctl_table_root *root, struct ctl_table_set *set, |
192 | struct ctl_node *node, struct ctl_table *table, size_t table_size) |
193 | { |
194 | head->ctl_table = table; |
195 | head->ctl_table_size = table_size; |
196 | head->ctl_table_arg = table; |
197 | head->used = 0; |
198 | head->count = 1; |
199 | head->nreg = 1; |
200 | head->unregistering = NULL; |
201 | head->root = root; |
202 | head->set = set; |
203 | head->parent = NULL; |
204 | head->node = node; |
205 | INIT_HLIST_HEAD(&head->inodes); |
206 | if (node) { |
207 | struct ctl_table *entry; |
208 | |
209 | list_for_each_table_entry(entry, head) { |
210 | node->header = head; |
211 | node++; |
212 | } |
213 | } |
214 | } |
215 | |
216 | static void (struct ctl_table_header *head) |
217 | { |
218 | struct ctl_table *entry; |
219 | |
220 | list_for_each_table_entry(entry, head) |
221 | erase_entry(head, entry); |
222 | } |
223 | |
224 | static int (struct ctl_dir *dir, struct ctl_table_header *) |
225 | { |
226 | struct ctl_table *entry; |
227 | struct ctl_table_header *dir_h = &dir->header; |
228 | int err; |
229 | |
230 | |
231 | /* Is this a permanently empty directory? */ |
232 | if (sysctl_is_perm_empty_ctl_header(dir_h)) |
233 | return -EROFS; |
234 | |
235 | /* Am I creating a permanently empty directory? */ |
236 | if (sysctl_is_perm_empty_ctl_table(header->ctl_table)) { |
237 | if (!RB_EMPTY_ROOT(&dir->root)) |
238 | return -EINVAL; |
239 | sysctl_set_perm_empty_ctl_header(dir_h); |
240 | } |
241 | |
242 | dir_h->nreg++; |
243 | header->parent = dir; |
244 | err = insert_links(head: header); |
245 | if (err) |
246 | goto fail_links; |
247 | list_for_each_table_entry(entry, header) { |
248 | err = insert_entry(head: header, entry); |
249 | if (err) |
250 | goto fail; |
251 | } |
252 | return 0; |
253 | fail: |
254 | erase_header(head: header); |
255 | put_links(header); |
256 | fail_links: |
257 | if (header->ctl_table == sysctl_mount_point) |
258 | sysctl_clear_perm_empty_ctl_header(dir_h); |
259 | header->parent = NULL; |
260 | drop_sysctl_table(header: dir_h); |
261 | return err; |
262 | } |
263 | |
264 | /* called under sysctl_lock */ |
265 | static int use_table(struct ctl_table_header *p) |
266 | { |
267 | if (unlikely(p->unregistering)) |
268 | return 0; |
269 | p->used++; |
270 | return 1; |
271 | } |
272 | |
273 | /* called under sysctl_lock */ |
274 | static void unuse_table(struct ctl_table_header *p) |
275 | { |
276 | if (!--p->used) |
277 | if (unlikely(p->unregistering)) |
278 | complete(p->unregistering); |
279 | } |
280 | |
281 | static void proc_sys_invalidate_dcache(struct ctl_table_header *head) |
282 | { |
283 | proc_invalidate_siblings_dcache(inodes: &head->inodes, lock: &sysctl_lock); |
284 | } |
285 | |
286 | /* called under sysctl_lock, will reacquire if has to wait */ |
287 | static void start_unregistering(struct ctl_table_header *p) |
288 | { |
289 | /* |
290 | * if p->used is 0, nobody will ever touch that entry again; |
291 | * we'll eliminate all paths to it before dropping sysctl_lock |
292 | */ |
293 | if (unlikely(p->used)) { |
294 | struct completion wait; |
295 | init_completion(x: &wait); |
296 | p->unregistering = &wait; |
297 | spin_unlock(lock: &sysctl_lock); |
298 | wait_for_completion(&wait); |
299 | } else { |
300 | /* anything non-NULL; we'll never dereference it */ |
301 | p->unregistering = ERR_PTR(error: -EINVAL); |
302 | spin_unlock(lock: &sysctl_lock); |
303 | } |
304 | /* |
305 | * Invalidate dentries for unregistered sysctls: namespaced sysctls |
306 | * can have duplicate names and contaminate dcache very badly. |
307 | */ |
308 | proc_sys_invalidate_dcache(head: p); |
309 | /* |
310 | * do not remove from the list until nobody holds it; walking the |
311 | * list in do_sysctl() relies on that. |
312 | */ |
313 | spin_lock(lock: &sysctl_lock); |
314 | erase_header(head: p); |
315 | } |
316 | |
317 | static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head) |
318 | { |
319 | BUG_ON(!head); |
320 | spin_lock(lock: &sysctl_lock); |
321 | if (!use_table(p: head)) |
322 | head = ERR_PTR(error: -ENOENT); |
323 | spin_unlock(lock: &sysctl_lock); |
324 | return head; |
325 | } |
326 | |
327 | static void sysctl_head_finish(struct ctl_table_header *head) |
328 | { |
329 | if (!head) |
330 | return; |
331 | spin_lock(lock: &sysctl_lock); |
332 | unuse_table(p: head); |
333 | spin_unlock(lock: &sysctl_lock); |
334 | } |
335 | |
336 | static struct ctl_table_set * |
337 | (struct ctl_table_root *root) |
338 | { |
339 | struct ctl_table_set *set = &root->default_set; |
340 | if (root->lookup) |
341 | set = root->lookup(root); |
342 | return set; |
343 | } |
344 | |
345 | static struct ctl_table *lookup_entry(struct ctl_table_header **phead, |
346 | struct ctl_dir *dir, |
347 | const char *name, int namelen) |
348 | { |
349 | struct ctl_table_header *head; |
350 | struct ctl_table *entry; |
351 | |
352 | spin_lock(lock: &sysctl_lock); |
353 | entry = find_entry(phead: &head, dir, name, namelen); |
354 | if (entry && use_table(p: head)) |
355 | *phead = head; |
356 | else |
357 | entry = NULL; |
358 | spin_unlock(lock: &sysctl_lock); |
359 | return entry; |
360 | } |
361 | |
362 | static struct ctl_node *first_usable_entry(struct rb_node *node) |
363 | { |
364 | struct ctl_node *ctl_node; |
365 | |
366 | for (;node; node = rb_next(node)) { |
367 | ctl_node = rb_entry(node, struct ctl_node, node); |
368 | if (use_table(p: ctl_node->header)) |
369 | return ctl_node; |
370 | } |
371 | return NULL; |
372 | } |
373 | |
374 | static void first_entry(struct ctl_dir *dir, |
375 | struct ctl_table_header **phead, struct ctl_table **pentry) |
376 | { |
377 | struct ctl_table_header *head = NULL; |
378 | struct ctl_table *entry = NULL; |
379 | struct ctl_node *ctl_node; |
380 | |
381 | spin_lock(lock: &sysctl_lock); |
382 | ctl_node = first_usable_entry(node: rb_first(&dir->root)); |
383 | spin_unlock(lock: &sysctl_lock); |
384 | if (ctl_node) { |
385 | head = ctl_node->header; |
386 | entry = &head->ctl_table[ctl_node - head->node]; |
387 | } |
388 | *phead = head; |
389 | *pentry = entry; |
390 | } |
391 | |
392 | static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry) |
393 | { |
394 | struct ctl_table_header *head = *phead; |
395 | struct ctl_table *entry = *pentry; |
396 | struct ctl_node *ctl_node = &head->node[entry - head->ctl_table]; |
397 | |
398 | spin_lock(lock: &sysctl_lock); |
399 | unuse_table(p: head); |
400 | |
401 | ctl_node = first_usable_entry(node: rb_next(&ctl_node->node)); |
402 | spin_unlock(lock: &sysctl_lock); |
403 | head = NULL; |
404 | if (ctl_node) { |
405 | head = ctl_node->header; |
406 | entry = &head->ctl_table[ctl_node - head->node]; |
407 | } |
408 | *phead = head; |
409 | *pentry = entry; |
410 | } |
411 | |
412 | /* |
413 | * sysctl_perm does NOT grant the superuser all rights automatically, because |
414 | * some sysctl variables are readonly even to root. |
415 | */ |
416 | |
417 | static int test_perm(int mode, int op) |
418 | { |
419 | if (uid_eq(current_euid(), GLOBAL_ROOT_UID)) |
420 | mode >>= 6; |
421 | else if (in_egroup_p(GLOBAL_ROOT_GID)) |
422 | mode >>= 3; |
423 | if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0) |
424 | return 0; |
425 | return -EACCES; |
426 | } |
427 | |
428 | static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op) |
429 | { |
430 | struct ctl_table_root *root = head->root; |
431 | int mode; |
432 | |
433 | if (root->permissions) |
434 | mode = root->permissions(head, table); |
435 | else |
436 | mode = table->mode; |
437 | |
438 | return test_perm(mode, op); |
439 | } |
440 | |
441 | static struct inode *proc_sys_make_inode(struct super_block *sb, |
442 | struct ctl_table_header *head, struct ctl_table *table) |
443 | { |
444 | struct ctl_table_root *root = head->root; |
445 | struct inode *inode; |
446 | struct proc_inode *ei; |
447 | |
448 | inode = new_inode(sb); |
449 | if (!inode) |
450 | return ERR_PTR(error: -ENOMEM); |
451 | |
452 | inode->i_ino = get_next_ino(); |
453 | |
454 | ei = PROC_I(inode); |
455 | |
456 | spin_lock(lock: &sysctl_lock); |
457 | if (unlikely(head->unregistering)) { |
458 | spin_unlock(lock: &sysctl_lock); |
459 | iput(inode); |
460 | return ERR_PTR(error: -ENOENT); |
461 | } |
462 | ei->sysctl = head; |
463 | ei->sysctl_entry = table; |
464 | hlist_add_head_rcu(n: &ei->sibling_inodes, h: &head->inodes); |
465 | head->count++; |
466 | spin_unlock(lock: &sysctl_lock); |
467 | |
468 | simple_inode_init_ts(inode); |
469 | inode->i_mode = table->mode; |
470 | if (!S_ISDIR(table->mode)) { |
471 | inode->i_mode |= S_IFREG; |
472 | inode->i_op = &proc_sys_inode_operations; |
473 | inode->i_fop = &proc_sys_file_operations; |
474 | } else { |
475 | inode->i_mode |= S_IFDIR; |
476 | inode->i_op = &proc_sys_dir_operations; |
477 | inode->i_fop = &proc_sys_dir_file_operations; |
478 | if (sysctl_is_perm_empty_ctl_header(head)) |
479 | make_empty_dir_inode(inode); |
480 | } |
481 | |
482 | if (root->set_ownership) |
483 | root->set_ownership(head, table, &inode->i_uid, &inode->i_gid); |
484 | else { |
485 | inode->i_uid = GLOBAL_ROOT_UID; |
486 | inode->i_gid = GLOBAL_ROOT_GID; |
487 | } |
488 | |
489 | return inode; |
490 | } |
491 | |
492 | void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head) |
493 | { |
494 | spin_lock(lock: &sysctl_lock); |
495 | hlist_del_init_rcu(n: &PROC_I(inode)->sibling_inodes); |
496 | if (!--head->count) |
497 | kfree_rcu(head, rcu); |
498 | spin_unlock(lock: &sysctl_lock); |
499 | } |
500 | |
501 | static struct ctl_table_header *(struct inode *inode) |
502 | { |
503 | struct ctl_table_header *head = PROC_I(inode)->sysctl; |
504 | if (!head) |
505 | head = &sysctl_table_root.default_set.dir.header; |
506 | return sysctl_head_grab(head); |
507 | } |
508 | |
509 | static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, |
510 | unsigned int flags) |
511 | { |
512 | struct ctl_table_header *head = grab_header(inode: dir); |
513 | struct ctl_table_header *h = NULL; |
514 | const struct qstr *name = &dentry->d_name; |
515 | struct ctl_table *p; |
516 | struct inode *inode; |
517 | struct dentry *err = ERR_PTR(error: -ENOENT); |
518 | struct ctl_dir *ctl_dir; |
519 | int ret; |
520 | |
521 | if (IS_ERR(ptr: head)) |
522 | return ERR_CAST(ptr: head); |
523 | |
524 | ctl_dir = container_of(head, struct ctl_dir, header); |
525 | |
526 | p = lookup_entry(phead: &h, dir: ctl_dir, name: name->name, namelen: name->len); |
527 | if (!p) |
528 | goto out; |
529 | |
530 | if (S_ISLNK(p->mode)) { |
531 | ret = sysctl_follow_link(phead: &h, pentry: &p); |
532 | err = ERR_PTR(error: ret); |
533 | if (ret) |
534 | goto out; |
535 | } |
536 | |
537 | inode = proc_sys_make_inode(sb: dir->i_sb, head: h ? h : head, table: p); |
538 | if (IS_ERR(ptr: inode)) { |
539 | err = ERR_CAST(ptr: inode); |
540 | goto out; |
541 | } |
542 | |
543 | d_set_d_op(dentry, op: &proc_sys_dentry_operations); |
544 | err = d_splice_alias(inode, dentry); |
545 | |
546 | out: |
547 | if (h) |
548 | sysctl_head_finish(head: h); |
549 | sysctl_head_finish(head); |
550 | return err; |
551 | } |
552 | |
553 | static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter, |
554 | int write) |
555 | { |
556 | struct inode *inode = file_inode(f: iocb->ki_filp); |
557 | struct ctl_table_header *head = grab_header(inode); |
558 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; |
559 | size_t count = iov_iter_count(i: iter); |
560 | char *kbuf; |
561 | ssize_t error; |
562 | |
563 | if (IS_ERR(ptr: head)) |
564 | return PTR_ERR(ptr: head); |
565 | |
566 | /* |
567 | * At this point we know that the sysctl was not unregistered |
568 | * and won't be until we finish. |
569 | */ |
570 | error = -EPERM; |
571 | if (sysctl_perm(head, table, op: write ? MAY_WRITE : MAY_READ)) |
572 | goto out; |
573 | |
574 | /* if that can happen at all, it should be -EINVAL, not -EISDIR */ |
575 | error = -EINVAL; |
576 | if (!table->proc_handler) |
577 | goto out; |
578 | |
579 | /* don't even try if the size is too large */ |
580 | error = -ENOMEM; |
581 | if (count >= KMALLOC_MAX_SIZE) |
582 | goto out; |
583 | kbuf = kvzalloc(size: count + 1, GFP_KERNEL); |
584 | if (!kbuf) |
585 | goto out; |
586 | |
587 | if (write) { |
588 | error = -EFAULT; |
589 | if (!copy_from_iter_full(addr: kbuf, bytes: count, i: iter)) |
590 | goto out_free_buf; |
591 | kbuf[count] = '\0'; |
592 | } |
593 | |
594 | error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count, |
595 | &iocb->ki_pos); |
596 | if (error) |
597 | goto out_free_buf; |
598 | |
599 | /* careful: calling conventions are nasty here */ |
600 | error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos); |
601 | if (error) |
602 | goto out_free_buf; |
603 | |
604 | if (!write) { |
605 | error = -EFAULT; |
606 | if (copy_to_iter(addr: kbuf, bytes: count, i: iter) < count) |
607 | goto out_free_buf; |
608 | } |
609 | |
610 | error = count; |
611 | out_free_buf: |
612 | kvfree(addr: kbuf); |
613 | out: |
614 | sysctl_head_finish(head); |
615 | |
616 | return error; |
617 | } |
618 | |
619 | static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter) |
620 | { |
621 | return proc_sys_call_handler(iocb, iter, write: 0); |
622 | } |
623 | |
624 | static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter) |
625 | { |
626 | return proc_sys_call_handler(iocb, iter, write: 1); |
627 | } |
628 | |
629 | static int proc_sys_open(struct inode *inode, struct file *filp) |
630 | { |
631 | struct ctl_table_header *head = grab_header(inode); |
632 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; |
633 | |
634 | /* sysctl was unregistered */ |
635 | if (IS_ERR(ptr: head)) |
636 | return PTR_ERR(ptr: head); |
637 | |
638 | if (table->poll) |
639 | filp->private_data = proc_sys_poll_event(poll: table->poll); |
640 | |
641 | sysctl_head_finish(head); |
642 | |
643 | return 0; |
644 | } |
645 | |
646 | static __poll_t proc_sys_poll(struct file *filp, poll_table *wait) |
647 | { |
648 | struct inode *inode = file_inode(f: filp); |
649 | struct ctl_table_header *head = grab_header(inode); |
650 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; |
651 | __poll_t ret = DEFAULT_POLLMASK; |
652 | unsigned long event; |
653 | |
654 | /* sysctl was unregistered */ |
655 | if (IS_ERR(ptr: head)) |
656 | return EPOLLERR | EPOLLHUP; |
657 | |
658 | if (!table->proc_handler) |
659 | goto out; |
660 | |
661 | if (!table->poll) |
662 | goto out; |
663 | |
664 | event = (unsigned long)filp->private_data; |
665 | poll_wait(filp, wait_address: &table->poll->wait, p: wait); |
666 | |
667 | if (event != atomic_read(v: &table->poll->event)) { |
668 | filp->private_data = proc_sys_poll_event(poll: table->poll); |
669 | ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI; |
670 | } |
671 | |
672 | out: |
673 | sysctl_head_finish(head); |
674 | |
675 | return ret; |
676 | } |
677 | |
678 | static bool proc_sys_fill_cache(struct file *file, |
679 | struct dir_context *ctx, |
680 | struct ctl_table_header *head, |
681 | struct ctl_table *table) |
682 | { |
683 | struct dentry *child, *dir = file->f_path.dentry; |
684 | struct inode *inode; |
685 | struct qstr qname; |
686 | ino_t ino = 0; |
687 | unsigned type = DT_UNKNOWN; |
688 | |
689 | qname.name = table->procname; |
690 | qname.len = strlen(table->procname); |
691 | qname.hash = full_name_hash(salt: dir, qname.name, qname.len); |
692 | |
693 | child = d_lookup(dir, &qname); |
694 | if (!child) { |
695 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); |
696 | child = d_alloc_parallel(dir, &qname, &wq); |
697 | if (IS_ERR(ptr: child)) |
698 | return false; |
699 | if (d_in_lookup(dentry: child)) { |
700 | struct dentry *res; |
701 | inode = proc_sys_make_inode(sb: dir->d_sb, head, table); |
702 | if (IS_ERR(ptr: inode)) { |
703 | d_lookup_done(dentry: child); |
704 | dput(child); |
705 | return false; |
706 | } |
707 | d_set_d_op(dentry: child, op: &proc_sys_dentry_operations); |
708 | res = d_splice_alias(inode, child); |
709 | d_lookup_done(dentry: child); |
710 | if (unlikely(res)) { |
711 | if (IS_ERR(ptr: res)) { |
712 | dput(child); |
713 | return false; |
714 | } |
715 | dput(child); |
716 | child = res; |
717 | } |
718 | } |
719 | } |
720 | inode = d_inode(dentry: child); |
721 | ino = inode->i_ino; |
722 | type = inode->i_mode >> 12; |
723 | dput(child); |
724 | return dir_emit(ctx, name: qname.name, namelen: qname.len, ino, type); |
725 | } |
726 | |
727 | static bool proc_sys_link_fill_cache(struct file *file, |
728 | struct dir_context *ctx, |
729 | struct ctl_table_header *head, |
730 | struct ctl_table *table) |
731 | { |
732 | bool ret = true; |
733 | |
734 | head = sysctl_head_grab(head); |
735 | if (IS_ERR(ptr: head)) |
736 | return false; |
737 | |
738 | /* It is not an error if we can not follow the link ignore it */ |
739 | if (sysctl_follow_link(phead: &head, pentry: &table)) |
740 | goto out; |
741 | |
742 | ret = proc_sys_fill_cache(file, ctx, head, table); |
743 | out: |
744 | sysctl_head_finish(head); |
745 | return ret; |
746 | } |
747 | |
748 | static int scan(struct ctl_table_header *head, struct ctl_table *table, |
749 | unsigned long *pos, struct file *file, |
750 | struct dir_context *ctx) |
751 | { |
752 | bool res; |
753 | |
754 | if ((*pos)++ < ctx->pos) |
755 | return true; |
756 | |
757 | if (unlikely(S_ISLNK(table->mode))) |
758 | res = proc_sys_link_fill_cache(file, ctx, head, table); |
759 | else |
760 | res = proc_sys_fill_cache(file, ctx, head, table); |
761 | |
762 | if (res) |
763 | ctx->pos = *pos; |
764 | |
765 | return res; |
766 | } |
767 | |
768 | static int proc_sys_readdir(struct file *file, struct dir_context *ctx) |
769 | { |
770 | struct ctl_table_header *head = grab_header(inode: file_inode(f: file)); |
771 | struct ctl_table_header *h = NULL; |
772 | struct ctl_table *entry; |
773 | struct ctl_dir *ctl_dir; |
774 | unsigned long pos; |
775 | |
776 | if (IS_ERR(ptr: head)) |
777 | return PTR_ERR(ptr: head); |
778 | |
779 | ctl_dir = container_of(head, struct ctl_dir, header); |
780 | |
781 | if (!dir_emit_dots(file, ctx)) |
782 | goto out; |
783 | |
784 | pos = 2; |
785 | |
786 | for (first_entry(dir: ctl_dir, phead: &h, pentry: &entry); h; next_entry(phead: &h, pentry: &entry)) { |
787 | if (!scan(head: h, table: entry, pos: &pos, file, ctx)) { |
788 | sysctl_head_finish(head: h); |
789 | break; |
790 | } |
791 | } |
792 | out: |
793 | sysctl_head_finish(head); |
794 | return 0; |
795 | } |
796 | |
797 | static int proc_sys_permission(struct mnt_idmap *idmap, |
798 | struct inode *inode, int mask) |
799 | { |
800 | /* |
801 | * sysctl entries that are not writeable, |
802 | * are _NOT_ writeable, capabilities or not. |
803 | */ |
804 | struct ctl_table_header *head; |
805 | struct ctl_table *table; |
806 | int error; |
807 | |
808 | /* Executable files are not allowed under /proc/sys/ */ |
809 | if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) |
810 | return -EACCES; |
811 | |
812 | head = grab_header(inode); |
813 | if (IS_ERR(ptr: head)) |
814 | return PTR_ERR(ptr: head); |
815 | |
816 | table = PROC_I(inode)->sysctl_entry; |
817 | if (!table) /* global root - r-xr-xr-x */ |
818 | error = mask & MAY_WRITE ? -EACCES : 0; |
819 | else /* Use the permissions on the sysctl table entry */ |
820 | error = sysctl_perm(head, table, op: mask & ~MAY_NOT_BLOCK); |
821 | |
822 | sysctl_head_finish(head); |
823 | return error; |
824 | } |
825 | |
826 | static int proc_sys_setattr(struct mnt_idmap *idmap, |
827 | struct dentry *dentry, struct iattr *attr) |
828 | { |
829 | struct inode *inode = d_inode(dentry); |
830 | int error; |
831 | |
832 | if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) |
833 | return -EPERM; |
834 | |
835 | error = setattr_prepare(&nop_mnt_idmap, dentry, attr); |
836 | if (error) |
837 | return error; |
838 | |
839 | setattr_copy(&nop_mnt_idmap, inode, attr); |
840 | return 0; |
841 | } |
842 | |
843 | static int proc_sys_getattr(struct mnt_idmap *idmap, |
844 | const struct path *path, struct kstat *stat, |
845 | u32 request_mask, unsigned int query_flags) |
846 | { |
847 | struct inode *inode = d_inode(dentry: path->dentry); |
848 | struct ctl_table_header *head = grab_header(inode); |
849 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; |
850 | |
851 | if (IS_ERR(ptr: head)) |
852 | return PTR_ERR(ptr: head); |
853 | |
854 | generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat); |
855 | if (table) |
856 | stat->mode = (stat->mode & S_IFMT) | table->mode; |
857 | |
858 | sysctl_head_finish(head); |
859 | return 0; |
860 | } |
861 | |
862 | static const struct file_operations proc_sys_file_operations = { |
863 | .open = proc_sys_open, |
864 | .poll = proc_sys_poll, |
865 | .read_iter = proc_sys_read, |
866 | .write_iter = proc_sys_write, |
867 | .splice_read = copy_splice_read, |
868 | .splice_write = iter_file_splice_write, |
869 | .llseek = default_llseek, |
870 | }; |
871 | |
872 | static const struct file_operations proc_sys_dir_file_operations = { |
873 | .read = generic_read_dir, |
874 | .iterate_shared = proc_sys_readdir, |
875 | .llseek = generic_file_llseek, |
876 | }; |
877 | |
878 | static const struct inode_operations proc_sys_inode_operations = { |
879 | .permission = proc_sys_permission, |
880 | .setattr = proc_sys_setattr, |
881 | .getattr = proc_sys_getattr, |
882 | }; |
883 | |
884 | static const struct inode_operations proc_sys_dir_operations = { |
885 | .lookup = proc_sys_lookup, |
886 | .permission = proc_sys_permission, |
887 | .setattr = proc_sys_setattr, |
888 | .getattr = proc_sys_getattr, |
889 | }; |
890 | |
891 | static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags) |
892 | { |
893 | if (flags & LOOKUP_RCU) |
894 | return -ECHILD; |
895 | return !PROC_I(inode: d_inode(dentry))->sysctl->unregistering; |
896 | } |
897 | |
898 | static int proc_sys_delete(const struct dentry *dentry) |
899 | { |
900 | return !!PROC_I(inode: d_inode(dentry))->sysctl->unregistering; |
901 | } |
902 | |
903 | static int sysctl_is_seen(struct ctl_table_header *p) |
904 | { |
905 | struct ctl_table_set *set = p->set; |
906 | int res; |
907 | spin_lock(lock: &sysctl_lock); |
908 | if (p->unregistering) |
909 | res = 0; |
910 | else if (!set->is_seen) |
911 | res = 1; |
912 | else |
913 | res = set->is_seen(set); |
914 | spin_unlock(lock: &sysctl_lock); |
915 | return res; |
916 | } |
917 | |
918 | static int proc_sys_compare(const struct dentry *dentry, |
919 | unsigned int len, const char *str, const struct qstr *name) |
920 | { |
921 | struct ctl_table_header *head; |
922 | struct inode *inode; |
923 | |
924 | /* Although proc doesn't have negative dentries, rcu-walk means |
925 | * that inode here can be NULL */ |
926 | /* AV: can it, indeed? */ |
927 | inode = d_inode_rcu(dentry); |
928 | if (!inode) |
929 | return 1; |
930 | if (name->len != len) |
931 | return 1; |
932 | if (memcmp(p: name->name, q: str, size: len)) |
933 | return 1; |
934 | head = rcu_dereference(PROC_I(inode)->sysctl); |
935 | return !head || !sysctl_is_seen(p: head); |
936 | } |
937 | |
938 | static const struct dentry_operations proc_sys_dentry_operations = { |
939 | .d_revalidate = proc_sys_revalidate, |
940 | .d_delete = proc_sys_delete, |
941 | .d_compare = proc_sys_compare, |
942 | }; |
943 | |
944 | static struct ctl_dir *find_subdir(struct ctl_dir *dir, |
945 | const char *name, int namelen) |
946 | { |
947 | struct ctl_table_header *head; |
948 | struct ctl_table *entry; |
949 | |
950 | entry = find_entry(phead: &head, dir, name, namelen); |
951 | if (!entry) |
952 | return ERR_PTR(error: -ENOENT); |
953 | if (!S_ISDIR(entry->mode)) |
954 | return ERR_PTR(error: -ENOTDIR); |
955 | return container_of(head, struct ctl_dir, header); |
956 | } |
957 | |
958 | static struct ctl_dir *new_dir(struct ctl_table_set *set, |
959 | const char *name, int namelen) |
960 | { |
961 | struct ctl_table *table; |
962 | struct ctl_dir *new; |
963 | struct ctl_node *node; |
964 | char *new_name; |
965 | |
966 | new = kzalloc(size: sizeof(*new) + sizeof(struct ctl_node) + |
967 | sizeof(struct ctl_table)*2 + namelen + 1, |
968 | GFP_KERNEL); |
969 | if (!new) |
970 | return NULL; |
971 | |
972 | node = (struct ctl_node *)(new + 1); |
973 | table = (struct ctl_table *)(node + 1); |
974 | new_name = (char *)(table + 2); |
975 | memcpy(new_name, name, namelen); |
976 | table[0].procname = new_name; |
977 | table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO; |
978 | init_header(head: &new->header, root: set->dir.header.root, set, node, table, table_size: 1); |
979 | |
980 | return new; |
981 | } |
982 | |
983 | /** |
984 | * get_subdir - find or create a subdir with the specified name. |
985 | * @dir: Directory to create the subdirectory in |
986 | * @name: The name of the subdirectory to find or create |
987 | * @namelen: The length of name |
988 | * |
989 | * Takes a directory with an elevated reference count so we know that |
990 | * if we drop the lock the directory will not go away. Upon success |
991 | * the reference is moved from @dir to the returned subdirectory. |
992 | * Upon error an error code is returned and the reference on @dir is |
993 | * simply dropped. |
994 | */ |
995 | static struct ctl_dir *get_subdir(struct ctl_dir *dir, |
996 | const char *name, int namelen) |
997 | { |
998 | struct ctl_table_set *set = dir->header.set; |
999 | struct ctl_dir *subdir, *new = NULL; |
1000 | int err; |
1001 | |
1002 | spin_lock(lock: &sysctl_lock); |
1003 | subdir = find_subdir(dir, name, namelen); |
1004 | if (!IS_ERR(ptr: subdir)) |
1005 | goto found; |
1006 | if (PTR_ERR(ptr: subdir) != -ENOENT) |
1007 | goto failed; |
1008 | |
1009 | spin_unlock(lock: &sysctl_lock); |
1010 | new = new_dir(set, name, namelen); |
1011 | spin_lock(lock: &sysctl_lock); |
1012 | subdir = ERR_PTR(error: -ENOMEM); |
1013 | if (!new) |
1014 | goto failed; |
1015 | |
1016 | /* Was the subdir added while we dropped the lock? */ |
1017 | subdir = find_subdir(dir, name, namelen); |
1018 | if (!IS_ERR(ptr: subdir)) |
1019 | goto found; |
1020 | if (PTR_ERR(ptr: subdir) != -ENOENT) |
1021 | goto failed; |
1022 | |
1023 | /* Nope. Use the our freshly made directory entry. */ |
1024 | err = insert_header(dir, header: &new->header); |
1025 | subdir = ERR_PTR(error: err); |
1026 | if (err) |
1027 | goto failed; |
1028 | subdir = new; |
1029 | found: |
1030 | subdir->header.nreg++; |
1031 | failed: |
1032 | if (IS_ERR(ptr: subdir)) { |
1033 | pr_err("sysctl could not get directory: " ); |
1034 | sysctl_print_dir(dir); |
1035 | pr_cont("%*.*s %ld\n" , namelen, namelen, name, |
1036 | PTR_ERR(subdir)); |
1037 | } |
1038 | drop_sysctl_table(header: &dir->header); |
1039 | if (new) |
1040 | drop_sysctl_table(header: &new->header); |
1041 | spin_unlock(lock: &sysctl_lock); |
1042 | return subdir; |
1043 | } |
1044 | |
1045 | static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir) |
1046 | { |
1047 | struct ctl_dir *parent; |
1048 | const char *procname; |
1049 | if (!dir->header.parent) |
1050 | return &set->dir; |
1051 | parent = xlate_dir(set, dir: dir->header.parent); |
1052 | if (IS_ERR(ptr: parent)) |
1053 | return parent; |
1054 | procname = dir->header.ctl_table[0].procname; |
1055 | return find_subdir(dir: parent, name: procname, strlen(procname)); |
1056 | } |
1057 | |
1058 | static int sysctl_follow_link(struct ctl_table_header **phead, |
1059 | struct ctl_table **pentry) |
1060 | { |
1061 | struct ctl_table_header *head; |
1062 | struct ctl_table_root *root; |
1063 | struct ctl_table_set *set; |
1064 | struct ctl_table *entry; |
1065 | struct ctl_dir *dir; |
1066 | int ret; |
1067 | |
1068 | spin_lock(lock: &sysctl_lock); |
1069 | root = (*pentry)->data; |
1070 | set = lookup_header_set(root); |
1071 | dir = xlate_dir(set, dir: (*phead)->parent); |
1072 | if (IS_ERR(ptr: dir)) |
1073 | ret = PTR_ERR(ptr: dir); |
1074 | else { |
1075 | const char *procname = (*pentry)->procname; |
1076 | head = NULL; |
1077 | entry = find_entry(phead: &head, dir, name: procname, strlen(procname)); |
1078 | ret = -ENOENT; |
1079 | if (entry && use_table(p: head)) { |
1080 | unuse_table(p: *phead); |
1081 | *phead = head; |
1082 | *pentry = entry; |
1083 | ret = 0; |
1084 | } |
1085 | } |
1086 | |
1087 | spin_unlock(lock: &sysctl_lock); |
1088 | return ret; |
1089 | } |
1090 | |
1091 | static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...) |
1092 | { |
1093 | struct va_format vaf; |
1094 | va_list args; |
1095 | |
1096 | va_start(args, fmt); |
1097 | vaf.fmt = fmt; |
1098 | vaf.va = &args; |
1099 | |
1100 | pr_err("sysctl table check failed: %s/%s %pV\n" , |
1101 | path, table->procname, &vaf); |
1102 | |
1103 | va_end(args); |
1104 | return -EINVAL; |
1105 | } |
1106 | |
1107 | static int sysctl_check_table_array(const char *path, struct ctl_table *table) |
1108 | { |
1109 | int err = 0; |
1110 | |
1111 | if ((table->proc_handler == proc_douintvec) || |
1112 | (table->proc_handler == proc_douintvec_minmax)) { |
1113 | if (table->maxlen != sizeof(unsigned int)) |
1114 | err |= sysctl_err(path, table, fmt: "array not allowed" ); |
1115 | } |
1116 | |
1117 | if (table->proc_handler == proc_dou8vec_minmax) { |
1118 | if (table->maxlen != sizeof(u8)) |
1119 | err |= sysctl_err(path, table, fmt: "array not allowed" ); |
1120 | } |
1121 | |
1122 | if (table->proc_handler == proc_dobool) { |
1123 | if (table->maxlen != sizeof(bool)) |
1124 | err |= sysctl_err(path, table, fmt: "array not allowed" ); |
1125 | } |
1126 | |
1127 | return err; |
1128 | } |
1129 | |
1130 | static int sysctl_check_table(const char *path, struct ctl_table_header *) |
1131 | { |
1132 | struct ctl_table *entry; |
1133 | int err = 0; |
1134 | list_for_each_table_entry(entry, header) { |
1135 | if ((entry->proc_handler == proc_dostring) || |
1136 | (entry->proc_handler == proc_dobool) || |
1137 | (entry->proc_handler == proc_dointvec) || |
1138 | (entry->proc_handler == proc_douintvec) || |
1139 | (entry->proc_handler == proc_douintvec_minmax) || |
1140 | (entry->proc_handler == proc_dointvec_minmax) || |
1141 | (entry->proc_handler == proc_dou8vec_minmax) || |
1142 | (entry->proc_handler == proc_dointvec_jiffies) || |
1143 | (entry->proc_handler == proc_dointvec_userhz_jiffies) || |
1144 | (entry->proc_handler == proc_dointvec_ms_jiffies) || |
1145 | (entry->proc_handler == proc_doulongvec_minmax) || |
1146 | (entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) { |
1147 | if (!entry->data) |
1148 | err |= sysctl_err(path, table: entry, fmt: "No data" ); |
1149 | if (!entry->maxlen) |
1150 | err |= sysctl_err(path, table: entry, fmt: "No maxlen" ); |
1151 | else |
1152 | err |= sysctl_check_table_array(path, table: entry); |
1153 | } |
1154 | if (!entry->proc_handler) |
1155 | err |= sysctl_err(path, table: entry, fmt: "No proc_handler" ); |
1156 | |
1157 | if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode) |
1158 | err |= sysctl_err(path, table: entry, fmt: "bogus .mode 0%o" , |
1159 | entry->mode); |
1160 | } |
1161 | return err; |
1162 | } |
1163 | |
1164 | static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_header *head) |
1165 | { |
1166 | struct ctl_table *link_table, *entry, *link; |
1167 | struct ctl_table_header *links; |
1168 | struct ctl_node *node; |
1169 | char *link_name; |
1170 | int nr_entries, name_bytes; |
1171 | |
1172 | name_bytes = 0; |
1173 | nr_entries = 0; |
1174 | list_for_each_table_entry(entry, head) { |
1175 | nr_entries++; |
1176 | name_bytes += strlen(entry->procname) + 1; |
1177 | } |
1178 | |
1179 | links = kzalloc(size: sizeof(struct ctl_table_header) + |
1180 | sizeof(struct ctl_node)*nr_entries + |
1181 | sizeof(struct ctl_table)*(nr_entries + 1) + |
1182 | name_bytes, |
1183 | GFP_KERNEL); |
1184 | |
1185 | if (!links) |
1186 | return NULL; |
1187 | |
1188 | node = (struct ctl_node *)(links + 1); |
1189 | link_table = (struct ctl_table *)(node + nr_entries); |
1190 | link_name = (char *)&link_table[nr_entries + 1]; |
1191 | link = link_table; |
1192 | |
1193 | list_for_each_table_entry(entry, head) { |
1194 | int len = strlen(entry->procname) + 1; |
1195 | memcpy(link_name, entry->procname, len); |
1196 | link->procname = link_name; |
1197 | link->mode = S_IFLNK|S_IRWXUGO; |
1198 | link->data = head->root; |
1199 | link_name += len; |
1200 | link++; |
1201 | } |
1202 | init_header(head: links, root: dir->header.root, set: dir->header.set, node, table: link_table, |
1203 | table_size: head->ctl_table_size); |
1204 | links->nreg = nr_entries; |
1205 | |
1206 | return links; |
1207 | } |
1208 | |
1209 | static bool get_links(struct ctl_dir *dir, |
1210 | struct ctl_table_header *, |
1211 | struct ctl_table_root *link_root) |
1212 | { |
1213 | struct ctl_table_header *tmp_head; |
1214 | struct ctl_table *entry, *link; |
1215 | |
1216 | /* Are there links available for every entry in table? */ |
1217 | list_for_each_table_entry(entry, header) { |
1218 | const char *procname = entry->procname; |
1219 | link = find_entry(phead: &tmp_head, dir, name: procname, strlen(procname)); |
1220 | if (!link) |
1221 | return false; |
1222 | if (S_ISDIR(link->mode) && S_ISDIR(entry->mode)) |
1223 | continue; |
1224 | if (S_ISLNK(link->mode) && (link->data == link_root)) |
1225 | continue; |
1226 | return false; |
1227 | } |
1228 | |
1229 | /* The checks passed. Increase the registration count on the links */ |
1230 | list_for_each_table_entry(entry, header) { |
1231 | const char *procname = entry->procname; |
1232 | link = find_entry(phead: &tmp_head, dir, name: procname, strlen(procname)); |
1233 | tmp_head->nreg++; |
1234 | } |
1235 | return true; |
1236 | } |
1237 | |
1238 | static int insert_links(struct ctl_table_header *head) |
1239 | { |
1240 | struct ctl_table_set *root_set = &sysctl_table_root.default_set; |
1241 | struct ctl_dir *core_parent; |
1242 | struct ctl_table_header *links; |
1243 | int err; |
1244 | |
1245 | if (head->set == root_set) |
1246 | return 0; |
1247 | |
1248 | core_parent = xlate_dir(set: root_set, dir: head->parent); |
1249 | if (IS_ERR(ptr: core_parent)) |
1250 | return 0; |
1251 | |
1252 | if (get_links(dir: core_parent, header: head, link_root: head->root)) |
1253 | return 0; |
1254 | |
1255 | core_parent->header.nreg++; |
1256 | spin_unlock(lock: &sysctl_lock); |
1257 | |
1258 | links = new_links(dir: core_parent, head); |
1259 | |
1260 | spin_lock(lock: &sysctl_lock); |
1261 | err = -ENOMEM; |
1262 | if (!links) |
1263 | goto out; |
1264 | |
1265 | err = 0; |
1266 | if (get_links(dir: core_parent, header: head, link_root: head->root)) { |
1267 | kfree(objp: links); |
1268 | goto out; |
1269 | } |
1270 | |
1271 | err = insert_header(dir: core_parent, header: links); |
1272 | if (err) |
1273 | kfree(objp: links); |
1274 | out: |
1275 | drop_sysctl_table(header: &core_parent->header); |
1276 | return err; |
1277 | } |
1278 | |
1279 | /* Find the directory for the ctl_table. If one is not found create it. */ |
1280 | static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path) |
1281 | { |
1282 | const char *name, *nextname; |
1283 | |
1284 | for (name = path; name; name = nextname) { |
1285 | int namelen; |
1286 | nextname = strchr(name, '/'); |
1287 | if (nextname) { |
1288 | namelen = nextname - name; |
1289 | nextname++; |
1290 | } else { |
1291 | namelen = strlen(name); |
1292 | } |
1293 | if (namelen == 0) |
1294 | continue; |
1295 | |
1296 | /* |
1297 | * namelen ensures if name is "foo/bar/yay" only foo is |
1298 | * registered first. We traverse as if using mkdir -p and |
1299 | * return a ctl_dir for the last directory entry. |
1300 | */ |
1301 | dir = get_subdir(dir, name, namelen); |
1302 | if (IS_ERR(ptr: dir)) |
1303 | break; |
1304 | } |
1305 | return dir; |
1306 | } |
1307 | |
1308 | /** |
1309 | * __register_sysctl_table - register a leaf sysctl table |
1310 | * @set: Sysctl tree to register on |
1311 | * @path: The path to the directory the sysctl table is in. |
1312 | * @table: the top-level table structure without any child. This table |
1313 | * should not be free'd after registration. So it should not be |
1314 | * used on stack. It can either be a global or dynamically allocated |
1315 | * by the caller and free'd later after sysctl unregistration. |
1316 | * @table_size : The number of elements in table |
1317 | * |
1318 | * Register a sysctl table hierarchy. @table should be a filled in ctl_table |
1319 | * array. A completely 0 filled entry terminates the table. |
1320 | * |
1321 | * The members of the &struct ctl_table structure are used as follows: |
1322 | * |
1323 | * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not |
1324 | * enter a sysctl file |
1325 | * |
1326 | * data - a pointer to data for use by proc_handler |
1327 | * |
1328 | * maxlen - the maximum size in bytes of the data |
1329 | * |
1330 | * mode - the file permissions for the /proc/sys file |
1331 | * |
1332 | * child - must be %NULL. |
1333 | * |
1334 | * proc_handler - the text handler routine (described below) |
1335 | * |
1336 | * extra1, extra2 - extra pointers usable by the proc handler routines |
1337 | * XXX: we should eventually modify these to use long min / max [0] |
1338 | * [0] https://lkml.kernel.org/87zgpte9o4.fsf@email.froward.int.ebiederm.org |
1339 | * |
1340 | * Leaf nodes in the sysctl tree will be represented by a single file |
1341 | * under /proc; non-leaf nodes (where child is not NULL) are not allowed, |
1342 | * sysctl_check_table() verifies this. |
1343 | * |
1344 | * There must be a proc_handler routine for any terminal nodes. |
1345 | * Several default handlers are available to cover common cases - |
1346 | * |
1347 | * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(), |
1348 | * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(), |
1349 | * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax() |
1350 | * |
1351 | * It is the handler's job to read the input buffer from user memory |
1352 | * and process it. The handler should return 0 on success. |
1353 | * |
1354 | * This routine returns %NULL on a failure to register, and a pointer |
1355 | * to the table header on success. |
1356 | */ |
1357 | struct ctl_table_header *__register_sysctl_table( |
1358 | struct ctl_table_set *set, |
1359 | const char *path, struct ctl_table *table, size_t table_size) |
1360 | { |
1361 | struct ctl_table_root *root = set->dir.header.root; |
1362 | struct ctl_table_header *; |
1363 | struct ctl_dir *dir; |
1364 | struct ctl_node *node; |
1365 | |
1366 | header = kzalloc(size: sizeof(struct ctl_table_header) + |
1367 | sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT); |
1368 | if (!header) |
1369 | return NULL; |
1370 | |
1371 | node = (struct ctl_node *)(header + 1); |
1372 | init_header(head: header, root, set, node, table, table_size); |
1373 | if (sysctl_check_table(path, header)) |
1374 | goto fail; |
1375 | |
1376 | spin_lock(lock: &sysctl_lock); |
1377 | dir = &set->dir; |
1378 | /* Reference moved down the directory tree get_subdir */ |
1379 | dir->header.nreg++; |
1380 | spin_unlock(lock: &sysctl_lock); |
1381 | |
1382 | dir = sysctl_mkdir_p(dir, path); |
1383 | if (IS_ERR(ptr: dir)) |
1384 | goto fail; |
1385 | spin_lock(lock: &sysctl_lock); |
1386 | if (insert_header(dir, header)) |
1387 | goto fail_put_dir_locked; |
1388 | |
1389 | drop_sysctl_table(header: &dir->header); |
1390 | spin_unlock(lock: &sysctl_lock); |
1391 | |
1392 | return header; |
1393 | |
1394 | fail_put_dir_locked: |
1395 | drop_sysctl_table(header: &dir->header); |
1396 | spin_unlock(lock: &sysctl_lock); |
1397 | fail: |
1398 | kfree(objp: header); |
1399 | return NULL; |
1400 | } |
1401 | |
1402 | /** |
1403 | * register_sysctl_sz - register a sysctl table |
1404 | * @path: The path to the directory the sysctl table is in. If the path |
1405 | * doesn't exist we will create it for you. |
1406 | * @table: the table structure. The calller must ensure the life of the @table |
1407 | * will be kept during the lifetime use of the syctl. It must not be freed |
1408 | * until unregister_sysctl_table() is called with the given returned table |
1409 | * with this registration. If your code is non modular then you don't need |
1410 | * to call unregister_sysctl_table() and can instead use something like |
1411 | * register_sysctl_init() which does not care for the result of the syctl |
1412 | * registration. |
1413 | * @table_size: The number of elements in table. |
1414 | * |
1415 | * Register a sysctl table. @table should be a filled in ctl_table |
1416 | * array. A completely 0 filled entry terminates the table. |
1417 | * |
1418 | * See __register_sysctl_table for more details. |
1419 | */ |
1420 | struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table, |
1421 | size_t table_size) |
1422 | { |
1423 | return __register_sysctl_table(set: &sysctl_table_root.default_set, |
1424 | path, table, table_size); |
1425 | } |
1426 | EXPORT_SYMBOL(register_sysctl_sz); |
1427 | |
1428 | /** |
1429 | * __register_sysctl_init() - register sysctl table to path |
1430 | * @path: path name for sysctl base. If that path doesn't exist we will create |
1431 | * it for you. |
1432 | * @table: This is the sysctl table that needs to be registered to the path. |
1433 | * The caller must ensure the life of the @table will be kept during the |
1434 | * lifetime use of the sysctl. |
1435 | * @table_name: The name of sysctl table, only used for log printing when |
1436 | * registration fails |
1437 | * @table_size: The number of elements in table |
1438 | * |
1439 | * The sysctl interface is used by userspace to query or modify at runtime |
1440 | * a predefined value set on a variable. These variables however have default |
1441 | * values pre-set. Code which depends on these variables will always work even |
1442 | * if register_sysctl() fails. If register_sysctl() fails you'd just loose the |
1443 | * ability to query or modify the sysctls dynamically at run time. Chances of |
1444 | * register_sysctl() failing on init are extremely low, and so for both reasons |
1445 | * this function does not return any error as it is used by initialization code. |
1446 | * |
1447 | * Context: if your base directory does not exist it will be created for you. |
1448 | */ |
1449 | void __init __register_sysctl_init(const char *path, struct ctl_table *table, |
1450 | const char *table_name, size_t table_size) |
1451 | { |
1452 | struct ctl_table_header *hdr = register_sysctl_sz(path, table, table_size); |
1453 | |
1454 | if (unlikely(!hdr)) { |
1455 | pr_err("failed when register_sysctl_sz %s to %s\n" , table_name, path); |
1456 | return; |
1457 | } |
1458 | kmemleak_not_leak(ptr: hdr); |
1459 | } |
1460 | |
1461 | static void put_links(struct ctl_table_header *) |
1462 | { |
1463 | struct ctl_table_set *root_set = &sysctl_table_root.default_set; |
1464 | struct ctl_table_root *root = header->root; |
1465 | struct ctl_dir *parent = header->parent; |
1466 | struct ctl_dir *core_parent; |
1467 | struct ctl_table *entry; |
1468 | |
1469 | if (header->set == root_set) |
1470 | return; |
1471 | |
1472 | core_parent = xlate_dir(set: root_set, dir: parent); |
1473 | if (IS_ERR(ptr: core_parent)) |
1474 | return; |
1475 | |
1476 | list_for_each_table_entry(entry, header) { |
1477 | struct ctl_table_header *link_head; |
1478 | struct ctl_table *link; |
1479 | const char *name = entry->procname; |
1480 | |
1481 | link = find_entry(phead: &link_head, dir: core_parent, name, strlen(name)); |
1482 | if (link && |
1483 | ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) || |
1484 | (S_ISLNK(link->mode) && (link->data == root)))) { |
1485 | drop_sysctl_table(header: link_head); |
1486 | } |
1487 | else { |
1488 | pr_err("sysctl link missing during unregister: " ); |
1489 | sysctl_print_dir(dir: parent); |
1490 | pr_cont("%s\n" , name); |
1491 | } |
1492 | } |
1493 | } |
1494 | |
1495 | static void drop_sysctl_table(struct ctl_table_header *) |
1496 | { |
1497 | struct ctl_dir *parent = header->parent; |
1498 | |
1499 | if (--header->nreg) |
1500 | return; |
1501 | |
1502 | if (parent) { |
1503 | put_links(header); |
1504 | start_unregistering(p: header); |
1505 | } |
1506 | |
1507 | if (!--header->count) |
1508 | kfree_rcu(header, rcu); |
1509 | |
1510 | if (parent) |
1511 | drop_sysctl_table(header: &parent->header); |
1512 | } |
1513 | |
1514 | /** |
1515 | * unregister_sysctl_table - unregister a sysctl table hierarchy |
1516 | * @header: the header returned from register_sysctl or __register_sysctl_table |
1517 | * |
1518 | * Unregisters the sysctl table and all children. proc entries may not |
1519 | * actually be removed until they are no longer used by anyone. |
1520 | */ |
1521 | void unregister_sysctl_table(struct ctl_table_header * ) |
1522 | { |
1523 | might_sleep(); |
1524 | |
1525 | if (header == NULL) |
1526 | return; |
1527 | |
1528 | spin_lock(lock: &sysctl_lock); |
1529 | drop_sysctl_table(header); |
1530 | spin_unlock(lock: &sysctl_lock); |
1531 | } |
1532 | EXPORT_SYMBOL(unregister_sysctl_table); |
1533 | |
1534 | void setup_sysctl_set(struct ctl_table_set *set, |
1535 | struct ctl_table_root *root, |
1536 | int (*is_seen)(struct ctl_table_set *)) |
1537 | { |
1538 | memset(set, 0, sizeof(*set)); |
1539 | set->is_seen = is_seen; |
1540 | init_header(head: &set->dir.header, root, set, NULL, table: root_table, table_size: 1); |
1541 | } |
1542 | |
1543 | void retire_sysctl_set(struct ctl_table_set *set) |
1544 | { |
1545 | WARN_ON(!RB_EMPTY_ROOT(&set->dir.root)); |
1546 | } |
1547 | |
1548 | int __init proc_sys_init(void) |
1549 | { |
1550 | struct proc_dir_entry *proc_sys_root; |
1551 | |
1552 | proc_sys_root = proc_mkdir("sys" , NULL); |
1553 | proc_sys_root->proc_iops = &proc_sys_dir_operations; |
1554 | proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations; |
1555 | proc_sys_root->nlink = 0; |
1556 | |
1557 | return sysctl_init_bases(); |
1558 | } |
1559 | |
1560 | struct sysctl_alias { |
1561 | const char *kernel_param; |
1562 | const char *sysctl_param; |
1563 | }; |
1564 | |
1565 | /* |
1566 | * Historically some settings had both sysctl and a command line parameter. |
1567 | * With the generic sysctl. parameter support, we can handle them at a single |
1568 | * place and only keep the historical name for compatibility. This is not meant |
1569 | * to add brand new aliases. When adding existing aliases, consider whether |
1570 | * the possibly different moment of changing the value (e.g. from early_param |
1571 | * to the moment do_sysctl_args() is called) is an issue for the specific |
1572 | * parameter. |
1573 | */ |
1574 | static const struct sysctl_alias sysctl_aliases[] = { |
1575 | {"hardlockup_all_cpu_backtrace" , "kernel.hardlockup_all_cpu_backtrace" }, |
1576 | {"hung_task_panic" , "kernel.hung_task_panic" }, |
1577 | {"numa_zonelist_order" , "vm.numa_zonelist_order" }, |
1578 | {"softlockup_all_cpu_backtrace" , "kernel.softlockup_all_cpu_backtrace" }, |
1579 | { } |
1580 | }; |
1581 | |
1582 | static const char *sysctl_find_alias(char *param) |
1583 | { |
1584 | const struct sysctl_alias *alias; |
1585 | |
1586 | for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) { |
1587 | if (strcmp(alias->kernel_param, param) == 0) |
1588 | return alias->sysctl_param; |
1589 | } |
1590 | |
1591 | return NULL; |
1592 | } |
1593 | |
1594 | bool sysctl_is_alias(char *param) |
1595 | { |
1596 | const char *alias = sysctl_find_alias(param); |
1597 | |
1598 | return alias != NULL; |
1599 | } |
1600 | |
1601 | /* Set sysctl value passed on kernel command line. */ |
1602 | static int process_sysctl_arg(char *param, char *val, |
1603 | const char *unused, void *arg) |
1604 | { |
1605 | char *path; |
1606 | struct vfsmount **proc_mnt = arg; |
1607 | struct file_system_type *proc_fs_type; |
1608 | struct file *file; |
1609 | int len; |
1610 | int err; |
1611 | loff_t pos = 0; |
1612 | ssize_t wret; |
1613 | |
1614 | if (strncmp(param, "sysctl" , sizeof("sysctl" ) - 1) == 0) { |
1615 | param += sizeof("sysctl" ) - 1; |
1616 | |
1617 | if (param[0] != '/' && param[0] != '.') |
1618 | return 0; |
1619 | |
1620 | param++; |
1621 | } else { |
1622 | param = (char *) sysctl_find_alias(param); |
1623 | if (!param) |
1624 | return 0; |
1625 | } |
1626 | |
1627 | if (!val) |
1628 | return -EINVAL; |
1629 | len = strlen(val); |
1630 | if (len == 0) |
1631 | return -EINVAL; |
1632 | |
1633 | /* |
1634 | * To set sysctl options, we use a temporary mount of proc, look up the |
1635 | * respective sys/ file and write to it. To avoid mounting it when no |
1636 | * options were given, we mount it only when the first sysctl option is |
1637 | * found. Why not a persistent mount? There are problems with a |
1638 | * persistent mount of proc in that it forces userspace not to use any |
1639 | * proc mount options. |
1640 | */ |
1641 | if (!*proc_mnt) { |
1642 | proc_fs_type = get_fs_type(name: "proc" ); |
1643 | if (!proc_fs_type) { |
1644 | pr_err("Failed to find procfs to set sysctl from command line\n" ); |
1645 | return 0; |
1646 | } |
1647 | *proc_mnt = kern_mount(proc_fs_type); |
1648 | put_filesystem(fs: proc_fs_type); |
1649 | if (IS_ERR(ptr: *proc_mnt)) { |
1650 | pr_err("Failed to mount procfs to set sysctl from command line\n" ); |
1651 | return 0; |
1652 | } |
1653 | } |
1654 | |
1655 | path = kasprintf(GFP_KERNEL, fmt: "sys/%s" , param); |
1656 | if (!path) |
1657 | panic(fmt: "%s: Failed to allocate path for %s\n" , __func__, param); |
1658 | strreplace(str: path, old: '.', new: '/'); |
1659 | |
1660 | file = file_open_root_mnt(mnt: *proc_mnt, name: path, O_WRONLY, mode: 0); |
1661 | if (IS_ERR(ptr: file)) { |
1662 | err = PTR_ERR(ptr: file); |
1663 | if (err == -ENOENT) |
1664 | pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n" , |
1665 | param, val); |
1666 | else if (err == -EACCES) |
1667 | pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n" , |
1668 | param, val); |
1669 | else |
1670 | pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n" , |
1671 | file, param, val); |
1672 | goto out; |
1673 | } |
1674 | wret = kernel_write(file, val, len, &pos); |
1675 | if (wret < 0) { |
1676 | err = wret; |
1677 | if (err == -EINVAL) |
1678 | pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n" , |
1679 | param, val); |
1680 | else |
1681 | pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n" , |
1682 | ERR_PTR(err), param, val); |
1683 | } else if (wret != len) { |
1684 | pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n" , |
1685 | wret, len, path, param, val); |
1686 | } |
1687 | |
1688 | err = filp_close(file, NULL); |
1689 | if (err) |
1690 | pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n" , |
1691 | ERR_PTR(err), param, val); |
1692 | out: |
1693 | kfree(objp: path); |
1694 | return 0; |
1695 | } |
1696 | |
1697 | void do_sysctl_args(void) |
1698 | { |
1699 | char *command_line; |
1700 | struct vfsmount *proc_mnt = NULL; |
1701 | |
1702 | command_line = kstrdup(s: saved_command_line, GFP_KERNEL); |
1703 | if (!command_line) |
1704 | panic(fmt: "%s: Failed to allocate copy of command line\n" , __func__); |
1705 | |
1706 | parse_args(name: "Setting sysctl args" , args: command_line, |
1707 | NULL, num: 0, level_min: -1, level_max: -1, arg: &proc_mnt, unknown: process_sysctl_arg); |
1708 | |
1709 | if (proc_mnt) |
1710 | kern_unmount(mnt: proc_mnt); |
1711 | |
1712 | kfree(objp: command_line); |
1713 | } |
1714 | |