1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/proc/inode.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8 #include <linux/cache.h>
9 #include <linux/time.h>
10 #include <linux/proc_fs.h>
11 #include <linux/kernel.h>
12 #include <linux/pid_namespace.h>
13 #include <linux/mm.h>
14 #include <linux/string.h>
15 #include <linux/stat.h>
16 #include <linux/completion.h>
17 #include <linux/poll.h>
18 #include <linux/printk.h>
19 #include <linux/file.h>
20 #include <linux/limits.h>
21 #include <linux/init.h>
22 #include <linux/module.h>
23 #include <linux/sysctl.h>
24 #include <linux/seq_file.h>
25 #include <linux/slab.h>
26 #include <linux/mount.h>
27 #include <linux/bug.h>
28
29 #include "internal.h"
30
31 static void proc_evict_inode(struct inode *inode)
32 {
33 struct ctl_table_header *head;
34 struct proc_inode *ei = PROC_I(inode);
35
36 truncate_inode_pages_final(&inode->i_data);
37 clear_inode(inode);
38
39 /* Stop tracking associated processes */
40 if (ei->pid)
41 proc_pid_evict_inode(ei);
42
43 head = ei->sysctl;
44 if (head) {
45 RCU_INIT_POINTER(ei->sysctl, NULL);
46 proc_sys_evict_inode(inode, head);
47 }
48 }
49
50 static struct kmem_cache *proc_inode_cachep __ro_after_init;
51 static struct kmem_cache *pde_opener_cache __ro_after_init;
52
53 static struct inode *proc_alloc_inode(struct super_block *sb)
54 {
55 struct proc_inode *ei;
56
57 ei = alloc_inode_sb(sb, proc_inode_cachep, GFP_KERNEL);
58 if (!ei)
59 return NULL;
60 ei->pid = NULL;
61 ei->fd = 0;
62 ei->op.proc_get_link = NULL;
63 ei->pde = NULL;
64 ei->sysctl = NULL;
65 ei->sysctl_entry = NULL;
66 INIT_HLIST_NODE(&ei->sibling_inodes);
67 ei->ns_ops = NULL;
68 return &ei->vfs_inode;
69 }
70
71 static void proc_free_inode(struct inode *inode)
72 {
73 struct proc_inode *ei = PROC_I(inode);
74
75 if (ei->pid)
76 put_pid(ei->pid);
77 /* Let go of any associated proc directory entry */
78 if (ei->pde)
79 pde_put(ei->pde);
80 kmem_cache_free(proc_inode_cachep, PROC_I(inode));
81 }
82
83 static void init_once(void *foo)
84 {
85 struct proc_inode *ei = (struct proc_inode *) foo;
86
87 inode_init_once(&ei->vfs_inode);
88 }
89
90 void __init proc_init_kmemcache(void)
91 {
92 proc_inode_cachep = kmem_cache_create("proc_inode_cache",
93 sizeof(struct proc_inode),
94 0, (SLAB_RECLAIM_ACCOUNT|
95 SLAB_ACCOUNT|
96 SLAB_PANIC),
97 init_once);
98 pde_opener_cache =
99 kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
100 SLAB_ACCOUNT|SLAB_PANIC, NULL);
101 proc_dir_entry_cache = kmem_cache_create_usercopy(
102 "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
103 offsetof(struct proc_dir_entry, inline_name),
104 SIZEOF_PDE_INLINE_NAME, NULL);
105 BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
106 }
107
108 void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
109 {
110 struct hlist_node *node;
111 struct super_block *old_sb = NULL;
112
113 rcu_read_lock();
114 while ((node = hlist_first_rcu(inodes))) {
115 struct proc_inode *ei = hlist_entry(node, struct proc_inode, sibling_inodes);
116 struct super_block *sb;
117 struct inode *inode;
118
119 spin_lock(lock);
120 hlist_del_init_rcu(&ei->sibling_inodes);
121 spin_unlock(lock);
122
123 inode = &ei->vfs_inode;
124 sb = inode->i_sb;
125 if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
126 continue;
127 inode = igrab(inode);
128 rcu_read_unlock();
129 if (sb != old_sb) {
130 if (old_sb)
131 deactivate_super(old_sb);
132 old_sb = sb;
133 }
134 if (unlikely(!inode)) {
135 rcu_read_lock();
136 continue;
137 }
138
139 if (S_ISDIR(inode->i_mode)) {
140 struct dentry *dir = d_find_any_alias(inode);
141 if (dir) {
142 d_invalidate(dir);
143 dput(dir);
144 }
145 } else {
146 struct dentry *dentry;
147 while ((dentry = d_find_alias(inode))) {
148 d_invalidate(dentry);
149 dput(dentry);
150 }
151 }
152 iput(inode);
153
154 rcu_read_lock();
155 }
156 rcu_read_unlock();
157 if (old_sb)
158 deactivate_super(old_sb);
159 }
160
161 static inline const char *hidepid2str(enum proc_hidepid v)
162 {
163 switch (v) {
164 case HIDEPID_OFF: return "off";
165 case HIDEPID_NO_ACCESS: return "noaccess";
166 case HIDEPID_INVISIBLE: return "invisible";
167 case HIDEPID_NOT_PTRACEABLE: return "ptraceable";
168 }
169 WARN_ONCE(1, "bad hide_pid value: %d\n", v);
170 return "unknown";
171 }
172
173 static int proc_show_options(struct seq_file *seq, struct dentry *root)
174 {
175 struct proc_fs_info *fs_info = proc_sb_info(root->d_sb);
176
177 if (!gid_eq(fs_info->pid_gid, GLOBAL_ROOT_GID))
178 seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fs_info->pid_gid));
179 if (fs_info->hide_pid != HIDEPID_OFF)
180 seq_printf(seq, ",hidepid=%s", hidepid2str(fs_info->hide_pid));
181 if (fs_info->pidonly != PROC_PIDONLY_OFF)
182 seq_printf(seq, ",subset=pid");
183
184 return 0;
185 }
186
187 const struct super_operations proc_sops = {
188 .alloc_inode = proc_alloc_inode,
189 .free_inode = proc_free_inode,
190 .drop_inode = generic_delete_inode,
191 .evict_inode = proc_evict_inode,
192 .statfs = simple_statfs,
193 .show_options = proc_show_options,
194 };
195
196 enum {BIAS = -1U<<31};
197
198 static inline int use_pde(struct proc_dir_entry *pde)
199 {
200 return likely(atomic_inc_unless_negative(&pde->in_use));
201 }
202
203 static void unuse_pde(struct proc_dir_entry *pde)
204 {
205 if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
206 complete(pde->pde_unload_completion);
207 }
208
209 /*
210 * At most 2 contexts can enter this function: the one doing the last
211 * close on the descriptor and whoever is deleting PDE itself.
212 *
213 * First to enter calls ->proc_release hook and signals its completion
214 * to the second one which waits and then does nothing.
215 *
216 * PDE is locked on entry, unlocked on exit.
217 */
218 static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
219 __releases(&pde->pde_unload_lock)
220 {
221 /*
222 * close() (proc_reg_release()) can't delete an entry and proceed:
223 * ->release hook needs to be available at the right moment.
224 *
225 * rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
226 * "struct file" needs to be available at the right moment.
227 */
228 if (pdeo->closing) {
229 /* somebody else is doing that, just wait */
230 DECLARE_COMPLETION_ONSTACK(c);
231 pdeo->c = &c;
232 spin_unlock(&pde->pde_unload_lock);
233 wait_for_completion(&c);
234 } else {
235 struct file *file;
236 struct completion *c;
237
238 pdeo->closing = true;
239 spin_unlock(&pde->pde_unload_lock);
240
241 file = pdeo->file;
242 pde->proc_ops->proc_release(file_inode(file), file);
243
244 spin_lock(&pde->pde_unload_lock);
245 /* Strictly after ->proc_release, see above. */
246 list_del(&pdeo->lh);
247 c = pdeo->c;
248 spin_unlock(&pde->pde_unload_lock);
249 if (unlikely(c))
250 complete(c);
251 kmem_cache_free(pde_opener_cache, pdeo);
252 }
253 }
254
255 void proc_entry_rundown(struct proc_dir_entry *de)
256 {
257 DECLARE_COMPLETION_ONSTACK(c);
258 /* Wait until all existing callers into module are done. */
259 de->pde_unload_completion = &c;
260 if (atomic_add_return(BIAS, &de->in_use) != BIAS)
261 wait_for_completion(&c);
262
263 /* ->pde_openers list can't grow from now on. */
264
265 spin_lock(&de->pde_unload_lock);
266 while (!list_empty(&de->pde_openers)) {
267 struct pde_opener *pdeo;
268 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
269 close_pdeo(de, pdeo);
270 spin_lock(&de->pde_unload_lock);
271 }
272 spin_unlock(&de->pde_unload_lock);
273 }
274
275 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
276 {
277 struct proc_dir_entry *pde = PDE(file_inode(file));
278 loff_t rv = -EINVAL;
279
280 if (pde_is_permanent(pde)) {
281 return pde->proc_ops->proc_lseek(file, offset, whence);
282 } else if (use_pde(pde)) {
283 rv = pde->proc_ops->proc_lseek(file, offset, whence);
284 unuse_pde(pde);
285 }
286 return rv;
287 }
288
289 static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
290 {
291 struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
292 ssize_t ret;
293
294 if (pde_is_permanent(pde))
295 return pde->proc_ops->proc_read_iter(iocb, iter);
296
297 if (!use_pde(pde))
298 return -EIO;
299 ret = pde->proc_ops->proc_read_iter(iocb, iter);
300 unuse_pde(pde);
301 return ret;
302 }
303
304 static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
305 {
306 typeof_member(struct proc_ops, proc_read) read;
307
308 read = pde->proc_ops->proc_read;
309 if (read)
310 return read(file, buf, count, ppos);
311 return -EIO;
312 }
313
314 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
315 {
316 struct proc_dir_entry *pde = PDE(file_inode(file));
317 ssize_t rv = -EIO;
318
319 if (pde_is_permanent(pde)) {
320 return pde_read(pde, file, buf, count, ppos);
321 } else if (use_pde(pde)) {
322 rv = pde_read(pde, file, buf, count, ppos);
323 unuse_pde(pde);
324 }
325 return rv;
326 }
327
328 static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
329 {
330 typeof_member(struct proc_ops, proc_write) write;
331
332 write = pde->proc_ops->proc_write;
333 if (write)
334 return write(file, buf, count, ppos);
335 return -EIO;
336 }
337
338 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
339 {
340 struct proc_dir_entry *pde = PDE(file_inode(file));
341 ssize_t rv = -EIO;
342
343 if (pde_is_permanent(pde)) {
344 return pde_write(pde, file, buf, count, ppos);
345 } else if (use_pde(pde)) {
346 rv = pde_write(pde, file, buf, count, ppos);
347 unuse_pde(pde);
348 }
349 return rv;
350 }
351
352 static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
353 {
354 typeof_member(struct proc_ops, proc_poll) poll;
355
356 poll = pde->proc_ops->proc_poll;
357 if (poll)
358 return poll(file, pts);
359 return DEFAULT_POLLMASK;
360 }
361
362 static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
363 {
364 struct proc_dir_entry *pde = PDE(file_inode(file));
365 __poll_t rv = DEFAULT_POLLMASK;
366
367 if (pde_is_permanent(pde)) {
368 return pde_poll(pde, file, pts);
369 } else if (use_pde(pde)) {
370 rv = pde_poll(pde, file, pts);
371 unuse_pde(pde);
372 }
373 return rv;
374 }
375
376 static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
377 {
378 typeof_member(struct proc_ops, proc_ioctl) ioctl;
379
380 ioctl = pde->proc_ops->proc_ioctl;
381 if (ioctl)
382 return ioctl(file, cmd, arg);
383 return -ENOTTY;
384 }
385
386 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
387 {
388 struct proc_dir_entry *pde = PDE(file_inode(file));
389 long rv = -ENOTTY;
390
391 if (pde_is_permanent(pde)) {
392 return pde_ioctl(pde, file, cmd, arg);
393 } else if (use_pde(pde)) {
394 rv = pde_ioctl(pde, file, cmd, arg);
395 unuse_pde(pde);
396 }
397 return rv;
398 }
399
400 #ifdef CONFIG_COMPAT
401 static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
402 {
403 typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
404
405 compat_ioctl = pde->proc_ops->proc_compat_ioctl;
406 if (compat_ioctl)
407 return compat_ioctl(file, cmd, arg);
408 return -ENOTTY;
409 }
410
411 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
412 {
413 struct proc_dir_entry *pde = PDE(file_inode(file));
414 long rv = -ENOTTY;
415 if (pde_is_permanent(pde)) {
416 return pde_compat_ioctl(pde, file, cmd, arg);
417 } else if (use_pde(pde)) {
418 rv = pde_compat_ioctl(pde, file, cmd, arg);
419 unuse_pde(pde);
420 }
421 return rv;
422 }
423 #endif
424
425 static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
426 {
427 typeof_member(struct proc_ops, proc_mmap) mmap;
428
429 mmap = pde->proc_ops->proc_mmap;
430 if (mmap)
431 return mmap(file, vma);
432 return -EIO;
433 }
434
435 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
436 {
437 struct proc_dir_entry *pde = PDE(file_inode(file));
438 int rv = -EIO;
439
440 if (pde_is_permanent(pde)) {
441 return pde_mmap(pde, file, vma);
442 } else if (use_pde(pde)) {
443 rv = pde_mmap(pde, file, vma);
444 unuse_pde(pde);
445 }
446 return rv;
447 }
448
449 static unsigned long
450 pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
451 unsigned long len, unsigned long pgoff,
452 unsigned long flags)
453 {
454 if (pde->proc_ops->proc_get_unmapped_area)
455 return pde->proc_ops->proc_get_unmapped_area(file, orig_addr, len, pgoff, flags);
456
457 #ifdef CONFIG_MMU
458 return mm_get_unmapped_area(current->mm, file, orig_addr, len, pgoff, flags);
459 #endif
460
461 return orig_addr;
462 }
463
464 static unsigned long
465 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
466 unsigned long len, unsigned long pgoff,
467 unsigned long flags)
468 {
469 struct proc_dir_entry *pde = PDE(file_inode(file));
470 unsigned long rv = -EIO;
471
472 if (pde_is_permanent(pde)) {
473 return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
474 } else if (use_pde(pde)) {
475 rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
476 unuse_pde(pde);
477 }
478 return rv;
479 }
480
481 static int proc_reg_open(struct inode *inode, struct file *file)
482 {
483 struct proc_dir_entry *pde = PDE(inode);
484 int rv = 0;
485 typeof_member(struct proc_ops, proc_open) open;
486 typeof_member(struct proc_ops, proc_release) release;
487 struct pde_opener *pdeo;
488
489 if (!pde->proc_ops->proc_lseek)
490 file->f_mode &= ~FMODE_LSEEK;
491
492 if (pde_is_permanent(pde)) {
493 open = pde->proc_ops->proc_open;
494 if (open)
495 rv = open(inode, file);
496 return rv;
497 }
498
499 /*
500 * Ensure that
501 * 1) PDE's ->release hook will be called no matter what
502 * either normally by close()/->release, or forcefully by
503 * rmmod/remove_proc_entry.
504 *
505 * 2) rmmod isn't blocked by opening file in /proc and sitting on
506 * the descriptor (including "rmmod foo </proc/foo" scenario).
507 *
508 * Save every "struct file" with custom ->release hook.
509 */
510 if (!use_pde(pde))
511 return -ENOENT;
512
513 release = pde->proc_ops->proc_release;
514 if (release) {
515 pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
516 if (!pdeo) {
517 rv = -ENOMEM;
518 goto out_unuse;
519 }
520 }
521
522 open = pde->proc_ops->proc_open;
523 if (open)
524 rv = open(inode, file);
525
526 if (release) {
527 if (rv == 0) {
528 /* To know what to release. */
529 pdeo->file = file;
530 pdeo->closing = false;
531 pdeo->c = NULL;
532 spin_lock(&pde->pde_unload_lock);
533 list_add(&pdeo->lh, &pde->pde_openers);
534 spin_unlock(&pde->pde_unload_lock);
535 } else
536 kmem_cache_free(pde_opener_cache, pdeo);
537 }
538
539 out_unuse:
540 unuse_pde(pde);
541 return rv;
542 }
543
544 static int proc_reg_release(struct inode *inode, struct file *file)
545 {
546 struct proc_dir_entry *pde = PDE(inode);
547 struct pde_opener *pdeo;
548
549 if (pde_is_permanent(pde)) {
550 typeof_member(struct proc_ops, proc_release) release;
551
552 release = pde->proc_ops->proc_release;
553 if (release) {
554 return release(inode, file);
555 }
556 return 0;
557 }
558
559 spin_lock(&pde->pde_unload_lock);
560 list_for_each_entry(pdeo, &pde->pde_openers, lh) {
561 if (pdeo->file == file) {
562 close_pdeo(pde, pdeo);
563 return 0;
564 }
565 }
566 spin_unlock(&pde->pde_unload_lock);
567 return 0;
568 }
569
570 static const struct file_operations proc_reg_file_ops = {
571 .llseek = proc_reg_llseek,
572 .read = proc_reg_read,
573 .write = proc_reg_write,
574 .poll = proc_reg_poll,
575 .unlocked_ioctl = proc_reg_unlocked_ioctl,
576 .mmap = proc_reg_mmap,
577 .get_unmapped_area = proc_reg_get_unmapped_area,
578 .open = proc_reg_open,
579 .release = proc_reg_release,
580 };
581
582 static const struct file_operations proc_iter_file_ops = {
583 .llseek = proc_reg_llseek,
584 .read_iter = proc_reg_read_iter,
585 .write = proc_reg_write,
586 .splice_read = copy_splice_read,
587 .poll = proc_reg_poll,
588 .unlocked_ioctl = proc_reg_unlocked_ioctl,
589 .mmap = proc_reg_mmap,
590 .get_unmapped_area = proc_reg_get_unmapped_area,
591 .open = proc_reg_open,
592 .release = proc_reg_release,
593 };
594
595 #ifdef CONFIG_COMPAT
596 static const struct file_operations proc_reg_file_ops_compat = {
597 .llseek = proc_reg_llseek,
598 .read = proc_reg_read,
599 .write = proc_reg_write,
600 .poll = proc_reg_poll,
601 .unlocked_ioctl = proc_reg_unlocked_ioctl,
602 .compat_ioctl = proc_reg_compat_ioctl,
603 .mmap = proc_reg_mmap,
604 .get_unmapped_area = proc_reg_get_unmapped_area,
605 .open = proc_reg_open,
606 .release = proc_reg_release,
607 };
608
609 static const struct file_operations proc_iter_file_ops_compat = {
610 .llseek = proc_reg_llseek,
611 .read_iter = proc_reg_read_iter,
612 .splice_read = copy_splice_read,
613 .write = proc_reg_write,
614 .poll = proc_reg_poll,
615 .unlocked_ioctl = proc_reg_unlocked_ioctl,
616 .compat_ioctl = proc_reg_compat_ioctl,
617 .mmap = proc_reg_mmap,
618 .get_unmapped_area = proc_reg_get_unmapped_area,
619 .open = proc_reg_open,
620 .release = proc_reg_release,
621 };
622 #endif
623
624 static void proc_put_link(void *p)
625 {
626 unuse_pde(p);
627 }
628
629 static const char *proc_get_link(struct dentry *dentry,
630 struct inode *inode,
631 struct delayed_call *done)
632 {
633 struct proc_dir_entry *pde = PDE(inode);
634 if (!use_pde(pde))
635 return ERR_PTR(-EINVAL);
636 set_delayed_call(done, proc_put_link, pde);
637 return pde->data;
638 }
639
640 const struct inode_operations proc_link_inode_operations = {
641 .get_link = proc_get_link,
642 };
643
644 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
645 {
646 struct inode *inode = new_inode(sb);
647
648 if (!inode) {
649 pde_put(de);
650 return NULL;
651 }
652
653 inode->i_private = de->data;
654 inode->i_ino = de->low_ino;
655 simple_inode_init_ts(inode);
656 PROC_I(inode)->pde = de;
657 if (is_empty_pde(de)) {
658 make_empty_dir_inode(inode);
659 return inode;
660 }
661
662 if (de->mode) {
663 inode->i_mode = de->mode;
664 inode->i_uid = de->uid;
665 inode->i_gid = de->gid;
666 }
667 if (de->size)
668 inode->i_size = de->size;
669 if (de->nlink)
670 set_nlink(inode, de->nlink);
671
672 if (S_ISREG(inode->i_mode)) {
673 inode->i_op = de->proc_iops;
674 if (de->proc_ops->proc_read_iter)
675 inode->i_fop = &proc_iter_file_ops;
676 else
677 inode->i_fop = &proc_reg_file_ops;
678 #ifdef CONFIG_COMPAT
679 if (de->proc_ops->proc_compat_ioctl) {
680 if (de->proc_ops->proc_read_iter)
681 inode->i_fop = &proc_iter_file_ops_compat;
682 else
683 inode->i_fop = &proc_reg_file_ops_compat;
684 }
685 #endif
686 } else if (S_ISDIR(inode->i_mode)) {
687 inode->i_op = de->proc_iops;
688 inode->i_fop = de->proc_dir_ops;
689 } else if (S_ISLNK(inode->i_mode)) {
690 inode->i_op = de->proc_iops;
691 inode->i_fop = NULL;
692 } else {
693 BUG();
694 }
695 return inode;
696 }
697
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