xref: /linux/fs/proc/inode.c (revision 24bce201d79807b668bf9d9e0aca801c5c0d5f78) 
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 = alloc_inode_sb(sb, 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 proc_reg_llseek(struct file *file, loff_t offset, int whence)
277 {
278 	struct proc_dir_entry *pde = PDE(file_inode(file));
279 	loff_t rv = -EINVAL;
280 
281 	if (pde_is_permanent(pde)) {
282 		return pde->proc_ops->proc_lseek(file, offset, whence);
283 	} else if (use_pde(pde)) {
284 		rv = pde->proc_ops->proc_lseek(file, offset, whence);
285 		unuse_pde(pde);
286 	}
287 	return rv;
288 }
289 
290 static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
291 {
292 	struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
293 	ssize_t ret;
294 
295 	if (pde_is_permanent(pde))
296 		return pde->proc_ops->proc_read_iter(iocb, iter);
297 
298 	if (!use_pde(pde))
299 		return -EIO;
300 	ret = pde->proc_ops->proc_read_iter(iocb, iter);
301 	unuse_pde(pde);
302 	return ret;
303 }
304 
305 static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
306 {
307 	typeof_member(struct proc_ops, proc_read) read;
308 
309 	read = pde->proc_ops->proc_read;
310 	if (read)
311 		return read(file, buf, count, ppos);
312 	return -EIO;
313 }
314 
315 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
316 {
317 	struct proc_dir_entry *pde = PDE(file_inode(file));
318 	ssize_t rv = -EIO;
319 
320 	if (pde_is_permanent(pde)) {
321 		return pde_read(pde, file, buf, count, ppos);
322 	} else if (use_pde(pde)) {
323 		rv = pde_read(pde, file, buf, count, ppos);
324 		unuse_pde(pde);
325 	}
326 	return rv;
327 }
328 
329 static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
330 {
331 	typeof_member(struct proc_ops, proc_write) write;
332 
333 	write = pde->proc_ops->proc_write;
334 	if (write)
335 		return write(file, buf, count, ppos);
336 	return -EIO;
337 }
338 
339 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
340 {
341 	struct proc_dir_entry *pde = PDE(file_inode(file));
342 	ssize_t rv = -EIO;
343 
344 	if (pde_is_permanent(pde)) {
345 		return pde_write(pde, file, buf, count, ppos);
346 	} else if (use_pde(pde)) {
347 		rv = pde_write(pde, file, buf, count, ppos);
348 		unuse_pde(pde);
349 	}
350 	return rv;
351 }
352 
353 static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
354 {
355 	typeof_member(struct proc_ops, proc_poll) poll;
356 
357 	poll = pde->proc_ops->proc_poll;
358 	if (poll)
359 		return poll(file, pts);
360 	return DEFAULT_POLLMASK;
361 }
362 
363 static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
364 {
365 	struct proc_dir_entry *pde = PDE(file_inode(file));
366 	__poll_t rv = DEFAULT_POLLMASK;
367 
368 	if (pde_is_permanent(pde)) {
369 		return pde_poll(pde, file, pts);
370 	} else if (use_pde(pde)) {
371 		rv = pde_poll(pde, file, pts);
372 		unuse_pde(pde);
373 	}
374 	return rv;
375 }
376 
377 static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
378 {
379 	typeof_member(struct proc_ops, proc_ioctl) ioctl;
380 
381 	ioctl = pde->proc_ops->proc_ioctl;
382 	if (ioctl)
383 		return ioctl(file, cmd, arg);
384 	return -ENOTTY;
385 }
386 
387 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
388 {
389 	struct proc_dir_entry *pde = PDE(file_inode(file));
390 	long rv = -ENOTTY;
391 
392 	if (pde_is_permanent(pde)) {
393 		return pde_ioctl(pde, file, cmd, arg);
394 	} else if (use_pde(pde)) {
395 		rv = pde_ioctl(pde, file, cmd, arg);
396 		unuse_pde(pde);
397 	}
398 	return rv;
399 }
400 
401 #ifdef CONFIG_COMPAT
402 static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
403 {
404 	typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
405 
406 	compat_ioctl = pde->proc_ops->proc_compat_ioctl;
407 	if (compat_ioctl)
408 		return compat_ioctl(file, cmd, arg);
409 	return -ENOTTY;
410 }
411 
412 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
413 {
414 	struct proc_dir_entry *pde = PDE(file_inode(file));
415 	long rv = -ENOTTY;
416 	if (pde_is_permanent(pde)) {
417 		return pde_compat_ioctl(pde, file, cmd, arg);
418 	} else if (use_pde(pde)) {
419 		rv = pde_compat_ioctl(pde, file, cmd, arg);
420 		unuse_pde(pde);
421 	}
422 	return rv;
423 }
424 #endif
425 
426 static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
427 {
428 	typeof_member(struct proc_ops, proc_mmap) mmap;
429 
430 	mmap = pde->proc_ops->proc_mmap;
431 	if (mmap)
432 		return mmap(file, vma);
433 	return -EIO;
434 }
435 
436 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
437 {
438 	struct proc_dir_entry *pde = PDE(file_inode(file));
439 	int rv = -EIO;
440 
441 	if (pde_is_permanent(pde)) {
442 		return pde_mmap(pde, file, vma);
443 	} else if (use_pde(pde)) {
444 		rv = pde_mmap(pde, file, vma);
445 		unuse_pde(pde);
446 	}
447 	return rv;
448 }
449 
450 static unsigned long
451 pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
452 			   unsigned long len, unsigned long pgoff,
453 			   unsigned long flags)
454 {
455 	typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
456 
457 	get_area = pde->proc_ops->proc_get_unmapped_area;
458 #ifdef CONFIG_MMU
459 	if (!get_area)
460 		get_area = current->mm->get_unmapped_area;
461 #endif
462 	if (get_area)
463 		return get_area(file, orig_addr, len, pgoff, flags);
464 	return orig_addr;
465 }
466 
467 static unsigned long
468 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
469 			   unsigned long len, unsigned long pgoff,
470 			   unsigned long flags)
471 {
472 	struct proc_dir_entry *pde = PDE(file_inode(file));
473 	unsigned long rv = -EIO;
474 
475 	if (pde_is_permanent(pde)) {
476 		return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
477 	} else if (use_pde(pde)) {
478 		rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
479 		unuse_pde(pde);
480 	}
481 	return rv;
482 }
483 
484 static int proc_reg_open(struct inode *inode, struct file *file)
485 {
486 	struct proc_dir_entry *pde = PDE(inode);
487 	int rv = 0;
488 	typeof_member(struct proc_ops, proc_open) open;
489 	typeof_member(struct proc_ops, proc_release) release;
490 	struct pde_opener *pdeo;
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	= generic_file_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	= generic_file_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 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(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