xref: /openbmc/linux/fs/proc/inode.c (revision 31e67366) 
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 <linux/uaccess.h>
30 
31 #include "internal.h"
32 
33 static void proc_evict_inode(struct inode *inode)
34 {
35 	struct proc_dir_entry *de;
36 	struct ctl_table_header *head;
37 	struct proc_inode *ei = PROC_I(inode);
38 
39 	truncate_inode_pages_final(&inode->i_data);
40 	clear_inode(inode);
41 
42 	/* Stop tracking associated processes */
43 	if (ei->pid) {
44 		proc_pid_evict_inode(ei);
45 		ei->pid = NULL;
46 	}
47 
48 	/* Let go of any associated proc directory entry */
49 	de = ei->pde;
50 	if (de) {
51 		pde_put(de);
52 		ei->pde = NULL;
53 	}
54 
55 	head = ei->sysctl;
56 	if (head) {
57 		RCU_INIT_POINTER(ei->sysctl, NULL);
58 		proc_sys_evict_inode(inode, head);
59 	}
60 }
61 
62 static struct kmem_cache *proc_inode_cachep __ro_after_init;
63 static struct kmem_cache *pde_opener_cache __ro_after_init;
64 
65 static struct inode *proc_alloc_inode(struct super_block *sb)
66 {
67 	struct proc_inode *ei;
68 
69 	ei = kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
70 	if (!ei)
71 		return NULL;
72 	ei->pid = NULL;
73 	ei->fd = 0;
74 	ei->op.proc_get_link = NULL;
75 	ei->pde = NULL;
76 	ei->sysctl = NULL;
77 	ei->sysctl_entry = NULL;
78 	INIT_HLIST_NODE(&ei->sibling_inodes);
79 	ei->ns_ops = NULL;
80 	return &ei->vfs_inode;
81 }
82 
83 static void proc_free_inode(struct inode *inode)
84 {
85 	kmem_cache_free(proc_inode_cachep, PROC_I(inode));
86 }
87 
88 static void init_once(void *foo)
89 {
90 	struct proc_inode *ei = (struct proc_inode *) foo;
91 
92 	inode_init_once(&ei->vfs_inode);
93 }
94 
95 void __init proc_init_kmemcache(void)
96 {
97 	proc_inode_cachep = kmem_cache_create("proc_inode_cache",
98 					     sizeof(struct proc_inode),
99 					     0, (SLAB_RECLAIM_ACCOUNT|
100 						SLAB_MEM_SPREAD|SLAB_ACCOUNT|
101 						SLAB_PANIC),
102 					     init_once);
103 	pde_opener_cache =
104 		kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
105 				  SLAB_ACCOUNT|SLAB_PANIC, NULL);
106 	proc_dir_entry_cache = kmem_cache_create_usercopy(
107 		"proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
108 		offsetof(struct proc_dir_entry, inline_name),
109 		SIZEOF_PDE_INLINE_NAME, NULL);
110 	BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
111 }
112 
113 void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
114 {
115 	struct inode *inode;
116 	struct proc_inode *ei;
117 	struct hlist_node *node;
118 	struct super_block *old_sb = NULL;
119 
120 	rcu_read_lock();
121 	for (;;) {
122 		struct super_block *sb;
123 		node = hlist_first_rcu(inodes);
124 		if (!node)
125 			break;
126 		ei = hlist_entry(node, struct proc_inode, sibling_inodes);
127 		spin_lock(lock);
128 		hlist_del_init_rcu(&ei->sibling_inodes);
129 		spin_unlock(lock);
130 
131 		inode = &ei->vfs_inode;
132 		sb = inode->i_sb;
133 		if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
134 			continue;
135 		inode = igrab(inode);
136 		rcu_read_unlock();
137 		if (sb != old_sb) {
138 			if (old_sb)
139 				deactivate_super(old_sb);
140 			old_sb = sb;
141 		}
142 		if (unlikely(!inode)) {
143 			rcu_read_lock();
144 			continue;
145 		}
146 
147 		if (S_ISDIR(inode->i_mode)) {
148 			struct dentry *dir = d_find_any_alias(inode);
149 			if (dir) {
150 				d_invalidate(dir);
151 				dput(dir);
152 			}
153 		} else {
154 			struct dentry *dentry;
155 			while ((dentry = d_find_alias(inode))) {
156 				d_invalidate(dentry);
157 				dput(dentry);
158 			}
159 		}
160 		iput(inode);
161 
162 		rcu_read_lock();
163 	}
164 	rcu_read_unlock();
165 	if (old_sb)
166 		deactivate_super(old_sb);
167 }
168 
169 static inline const char *hidepid2str(enum proc_hidepid v)
170 {
171 	switch (v) {
172 		case HIDEPID_OFF: return "off";
173 		case HIDEPID_NO_ACCESS: return "noaccess";
174 		case HIDEPID_INVISIBLE: return "invisible";
175 		case HIDEPID_NOT_PTRACEABLE: return "ptraceable";
176 	}
177 	WARN_ONCE(1, "bad hide_pid value: %d\n", v);
178 	return "unknown";
179 }
180 
181 static int proc_show_options(struct seq_file *seq, struct dentry *root)
182 {
183 	struct proc_fs_info *fs_info = proc_sb_info(root->d_sb);
184 
185 	if (!gid_eq(fs_info->pid_gid, GLOBAL_ROOT_GID))
186 		seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fs_info->pid_gid));
187 	if (fs_info->hide_pid != HIDEPID_OFF)
188 		seq_printf(seq, ",hidepid=%s", hidepid2str(fs_info->hide_pid));
189 	if (fs_info->pidonly != PROC_PIDONLY_OFF)
190 		seq_printf(seq, ",subset=pid");
191 
192 	return 0;
193 }
194 
195 const struct super_operations proc_sops = {
196 	.alloc_inode	= proc_alloc_inode,
197 	.free_inode	= proc_free_inode,
198 	.drop_inode	= generic_delete_inode,
199 	.evict_inode	= proc_evict_inode,
200 	.statfs		= simple_statfs,
201 	.show_options	= proc_show_options,
202 };
203 
204 enum {BIAS = -1U<<31};
205 
206 static inline int use_pde(struct proc_dir_entry *pde)
207 {
208 	return likely(atomic_inc_unless_negative(&pde->in_use));
209 }
210 
211 static void unuse_pde(struct proc_dir_entry *pde)
212 {
213 	if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
214 		complete(pde->pde_unload_completion);
215 }
216 
217 /* pde is locked on entry, unlocked on exit */
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 	 * Therefore, first process to enter this function does ->release() and
229 	 * signals its completion to the other process which does nothing.
230 	 */
231 	if (pdeo->closing) {
232 		/* somebody else is doing that, just wait */
233 		DECLARE_COMPLETION_ONSTACK(c);
234 		pdeo->c = &c;
235 		spin_unlock(&pde->pde_unload_lock);
236 		wait_for_completion(&c);
237 	} else {
238 		struct file *file;
239 		struct completion *c;
240 
241 		pdeo->closing = true;
242 		spin_unlock(&pde->pde_unload_lock);
243 		file = pdeo->file;
244 		pde->proc_ops->proc_release(file_inode(file), file);
245 		spin_lock(&pde->pde_unload_lock);
246 		/* After ->release. */
247 		list_del(&pdeo->lh);
248 		c = pdeo->c;
249 		spin_unlock(&pde->pde_unload_lock);
250 		if (unlikely(c))
251 			complete(c);
252 		kmem_cache_free(pde_opener_cache, pdeo);
253 	}
254 }
255 
256 void proc_entry_rundown(struct proc_dir_entry *de)
257 {
258 	DECLARE_COMPLETION_ONSTACK(c);
259 	/* Wait until all existing callers into module are done. */
260 	de->pde_unload_completion = &c;
261 	if (atomic_add_return(BIAS, &de->in_use) != BIAS)
262 		wait_for_completion(&c);
263 
264 	/* ->pde_openers list can't grow from now on. */
265 
266 	spin_lock(&de->pde_unload_lock);
267 	while (!list_empty(&de->pde_openers)) {
268 		struct pde_opener *pdeo;
269 		pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
270 		close_pdeo(de, pdeo);
271 		spin_lock(&de->pde_unload_lock);
272 	}
273 	spin_unlock(&de->pde_unload_lock);
274 }
275 
276 static loff_t pde_lseek(struct proc_dir_entry *pde, struct file *file, loff_t offset, int whence)
277 {
278 	typeof_member(struct proc_ops, proc_lseek) lseek;
279 
280 	lseek = pde->proc_ops->proc_lseek;
281 	if (!lseek)
282 		lseek = default_llseek;
283 	return lseek(file, offset, whence);
284 }
285 
286 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
287 {
288 	struct proc_dir_entry *pde = PDE(file_inode(file));
289 	loff_t rv = -EINVAL;
290 
291 	if (pde_is_permanent(pde)) {
292 		return pde_lseek(pde, file, offset, whence);
293 	} else if (use_pde(pde)) {
294 		rv = pde_lseek(pde, file, offset, whence);
295 		unuse_pde(pde);
296 	}
297 	return rv;
298 }
299 
300 static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
301 {
302 	struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
303 	ssize_t ret;
304 
305 	if (pde_is_permanent(pde))
306 		return pde->proc_ops->proc_read_iter(iocb, iter);
307 
308 	if (!use_pde(pde))
309 		return -EIO;
310 	ret = pde->proc_ops->proc_read_iter(iocb, iter);
311 	unuse_pde(pde);
312 	return ret;
313 }
314 
315 static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
316 {
317 	typeof_member(struct proc_ops, proc_read) read;
318 
319 	read = pde->proc_ops->proc_read;
320 	if (read)
321 		return read(file, buf, count, ppos);
322 	return -EIO;
323 }
324 
325 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
326 {
327 	struct proc_dir_entry *pde = PDE(file_inode(file));
328 	ssize_t rv = -EIO;
329 
330 	if (pde_is_permanent(pde)) {
331 		return pde_read(pde, file, buf, count, ppos);
332 	} else if (use_pde(pde)) {
333 		rv = pde_read(pde, file, buf, count, ppos);
334 		unuse_pde(pde);
335 	}
336 	return rv;
337 }
338 
339 static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
340 {
341 	typeof_member(struct proc_ops, proc_write) write;
342 
343 	write = pde->proc_ops->proc_write;
344 	if (write)
345 		return write(file, buf, count, ppos);
346 	return -EIO;
347 }
348 
349 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
350 {
351 	struct proc_dir_entry *pde = PDE(file_inode(file));
352 	ssize_t rv = -EIO;
353 
354 	if (pde_is_permanent(pde)) {
355 		return pde_write(pde, file, buf, count, ppos);
356 	} else if (use_pde(pde)) {
357 		rv = pde_write(pde, file, buf, count, ppos);
358 		unuse_pde(pde);
359 	}
360 	return rv;
361 }
362 
363 static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
364 {
365 	typeof_member(struct proc_ops, proc_poll) poll;
366 
367 	poll = pde->proc_ops->proc_poll;
368 	if (poll)
369 		return poll(file, pts);
370 	return DEFAULT_POLLMASK;
371 }
372 
373 static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
374 {
375 	struct proc_dir_entry *pde = PDE(file_inode(file));
376 	__poll_t rv = DEFAULT_POLLMASK;
377 
378 	if (pde_is_permanent(pde)) {
379 		return pde_poll(pde, file, pts);
380 	} else if (use_pde(pde)) {
381 		rv = pde_poll(pde, file, pts);
382 		unuse_pde(pde);
383 	}
384 	return rv;
385 }
386 
387 static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
388 {
389 	typeof_member(struct proc_ops, proc_ioctl) ioctl;
390 
391 	ioctl = pde->proc_ops->proc_ioctl;
392 	if (ioctl)
393 		return ioctl(file, cmd, arg);
394 	return -ENOTTY;
395 }
396 
397 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
398 {
399 	struct proc_dir_entry *pde = PDE(file_inode(file));
400 	long rv = -ENOTTY;
401 
402 	if (pde_is_permanent(pde)) {
403 		return pde_ioctl(pde, file, cmd, arg);
404 	} else if (use_pde(pde)) {
405 		rv = pde_ioctl(pde, file, cmd, arg);
406 		unuse_pde(pde);
407 	}
408 	return rv;
409 }
410 
411 #ifdef CONFIG_COMPAT
412 static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
413 {
414 	typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
415 
416 	compat_ioctl = pde->proc_ops->proc_compat_ioctl;
417 	if (compat_ioctl)
418 		return compat_ioctl(file, cmd, arg);
419 	return -ENOTTY;
420 }
421 
422 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
423 {
424 	struct proc_dir_entry *pde = PDE(file_inode(file));
425 	long rv = -ENOTTY;
426 	if (pde_is_permanent(pde)) {
427 		return pde_compat_ioctl(pde, file, cmd, arg);
428 	} else if (use_pde(pde)) {
429 		rv = pde_compat_ioctl(pde, file, cmd, arg);
430 		unuse_pde(pde);
431 	}
432 	return rv;
433 }
434 #endif
435 
436 static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
437 {
438 	typeof_member(struct proc_ops, proc_mmap) mmap;
439 
440 	mmap = pde->proc_ops->proc_mmap;
441 	if (mmap)
442 		return mmap(file, vma);
443 	return -EIO;
444 }
445 
446 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
447 {
448 	struct proc_dir_entry *pde = PDE(file_inode(file));
449 	int rv = -EIO;
450 
451 	if (pde_is_permanent(pde)) {
452 		return pde_mmap(pde, file, vma);
453 	} else if (use_pde(pde)) {
454 		rv = pde_mmap(pde, file, vma);
455 		unuse_pde(pde);
456 	}
457 	return rv;
458 }
459 
460 static unsigned long
461 pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
462 			   unsigned long len, unsigned long pgoff,
463 			   unsigned long flags)
464 {
465 	typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
466 
467 	get_area = pde->proc_ops->proc_get_unmapped_area;
468 #ifdef CONFIG_MMU
469 	if (!get_area)
470 		get_area = current->mm->get_unmapped_area;
471 #endif
472 	if (get_area)
473 		return get_area(file, orig_addr, len, pgoff, flags);
474 	return orig_addr;
475 }
476 
477 static unsigned long
478 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
479 			   unsigned long len, unsigned long pgoff,
480 			   unsigned long flags)
481 {
482 	struct proc_dir_entry *pde = PDE(file_inode(file));
483 	unsigned long rv = -EIO;
484 
485 	if (pde_is_permanent(pde)) {
486 		return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
487 	} else if (use_pde(pde)) {
488 		rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
489 		unuse_pde(pde);
490 	}
491 	return rv;
492 }
493 
494 static int proc_reg_open(struct inode *inode, struct file *file)
495 {
496 	struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb);
497 	struct proc_dir_entry *pde = PDE(inode);
498 	int rv = 0;
499 	typeof_member(struct proc_ops, proc_open) open;
500 	typeof_member(struct proc_ops, proc_release) release;
501 	struct pde_opener *pdeo;
502 
503 	if (pde_is_permanent(pde)) {
504 		open = pde->proc_ops->proc_open;
505 		if (open)
506 			rv = open(inode, file);
507 		return rv;
508 	}
509 
510 	if (fs_info->pidonly == PROC_PIDONLY_ON)
511 		return -ENOENT;
512 
513 	/*
514 	 * Ensure that
515 	 * 1) PDE's ->release hook will be called no matter what
516 	 *    either normally by close()/->release, or forcefully by
517 	 *    rmmod/remove_proc_entry.
518 	 *
519 	 * 2) rmmod isn't blocked by opening file in /proc and sitting on
520 	 *    the descriptor (including "rmmod foo </proc/foo" scenario).
521 	 *
522 	 * Save every "struct file" with custom ->release hook.
523 	 */
524 	if (!use_pde(pde))
525 		return -ENOENT;
526 
527 	release = pde->proc_ops->proc_release;
528 	if (release) {
529 		pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
530 		if (!pdeo) {
531 			rv = -ENOMEM;
532 			goto out_unuse;
533 		}
534 	}
535 
536 	open = pde->proc_ops->proc_open;
537 	if (open)
538 		rv = open(inode, file);
539 
540 	if (release) {
541 		if (rv == 0) {
542 			/* To know what to release. */
543 			pdeo->file = file;
544 			pdeo->closing = false;
545 			pdeo->c = NULL;
546 			spin_lock(&pde->pde_unload_lock);
547 			list_add(&pdeo->lh, &pde->pde_openers);
548 			spin_unlock(&pde->pde_unload_lock);
549 		} else
550 			kmem_cache_free(pde_opener_cache, pdeo);
551 	}
552 
553 out_unuse:
554 	unuse_pde(pde);
555 	return rv;
556 }
557 
558 static int proc_reg_release(struct inode *inode, struct file *file)
559 {
560 	struct proc_dir_entry *pde = PDE(inode);
561 	struct pde_opener *pdeo;
562 
563 	if (pde_is_permanent(pde)) {
564 		typeof_member(struct proc_ops, proc_release) release;
565 
566 		release = pde->proc_ops->proc_release;
567 		if (release) {
568 			return release(inode, file);
569 		}
570 		return 0;
571 	}
572 
573 	spin_lock(&pde->pde_unload_lock);
574 	list_for_each_entry(pdeo, &pde->pde_openers, lh) {
575 		if (pdeo->file == file) {
576 			close_pdeo(pde, pdeo);
577 			return 0;
578 		}
579 	}
580 	spin_unlock(&pde->pde_unload_lock);
581 	return 0;
582 }
583 
584 static const struct file_operations proc_reg_file_ops = {
585 	.llseek		= proc_reg_llseek,
586 	.read		= proc_reg_read,
587 	.write		= proc_reg_write,
588 	.poll		= proc_reg_poll,
589 	.unlocked_ioctl	= proc_reg_unlocked_ioctl,
590 	.mmap		= proc_reg_mmap,
591 	.get_unmapped_area = proc_reg_get_unmapped_area,
592 	.open		= proc_reg_open,
593 	.release	= proc_reg_release,
594 };
595 
596 static const struct file_operations proc_iter_file_ops = {
597 	.llseek		= proc_reg_llseek,
598 	.read_iter	= proc_reg_read_iter,
599 	.write		= proc_reg_write,
600 	.splice_read	= generic_file_splice_read,
601 	.poll		= proc_reg_poll,
602 	.unlocked_ioctl	= proc_reg_unlocked_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 #ifdef CONFIG_COMPAT
610 static const struct file_operations proc_reg_file_ops_compat = {
611 	.llseek		= proc_reg_llseek,
612 	.read		= proc_reg_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 
623 static const struct file_operations proc_iter_file_ops_compat = {
624 	.llseek		= proc_reg_llseek,
625 	.read_iter	= proc_reg_read_iter,
626 	.splice_read	= generic_file_splice_read,
627 	.write		= proc_reg_write,
628 	.poll		= proc_reg_poll,
629 	.unlocked_ioctl	= proc_reg_unlocked_ioctl,
630 	.compat_ioctl	= proc_reg_compat_ioctl,
631 	.mmap		= proc_reg_mmap,
632 	.get_unmapped_area = proc_reg_get_unmapped_area,
633 	.open		= proc_reg_open,
634 	.release	= proc_reg_release,
635 };
636 #endif
637 
638 static void proc_put_link(void *p)
639 {
640 	unuse_pde(p);
641 }
642 
643 static const char *proc_get_link(struct dentry *dentry,
644 				 struct inode *inode,
645 				 struct delayed_call *done)
646 {
647 	struct proc_dir_entry *pde = PDE(inode);
648 	if (!use_pde(pde))
649 		return ERR_PTR(-EINVAL);
650 	set_delayed_call(done, proc_put_link, pde);
651 	return pde->data;
652 }
653 
654 const struct inode_operations proc_link_inode_operations = {
655 	.get_link	= proc_get_link,
656 };
657 
658 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
659 {
660 	struct inode *inode = new_inode(sb);
661 
662 	if (!inode) {
663 		pde_put(de);
664 		return NULL;
665 	}
666 
667 	inode->i_ino = de->low_ino;
668 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
669 	PROC_I(inode)->pde = de;
670 	if (is_empty_pde(de)) {
671 		make_empty_dir_inode(inode);
672 		return inode;
673 	}
674 
675 	if (de->mode) {
676 		inode->i_mode = de->mode;
677 		inode->i_uid = de->uid;
678 		inode->i_gid = de->gid;
679 	}
680 	if (de->size)
681 		inode->i_size = de->size;
682 	if (de->nlink)
683 		set_nlink(inode, de->nlink);
684 
685 	if (S_ISREG(inode->i_mode)) {
686 		inode->i_op = de->proc_iops;
687 		if (de->proc_ops->proc_read_iter)
688 			inode->i_fop = &proc_iter_file_ops;
689 		else
690 			inode->i_fop = &proc_reg_file_ops;
691 #ifdef CONFIG_COMPAT
692 		if (de->proc_ops->proc_compat_ioctl) {
693 			if (de->proc_ops->proc_read_iter)
694 				inode->i_fop = &proc_iter_file_ops_compat;
695 			else
696 				inode->i_fop = &proc_reg_file_ops_compat;
697 		}
698 #endif
699 	} else if (S_ISDIR(inode->i_mode)) {
700 		inode->i_op = de->proc_iops;
701 		inode->i_fop = de->proc_dir_ops;
702 	} else if (S_ISLNK(inode->i_mode)) {
703 		inode->i_op = de->proc_iops;
704 		inode->i_fop = NULL;
705 	} else {
706 		BUG();
707 	}
708 	return inode;
709 }
710