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1 | /* |
2 | * linux/fs/proc/inode.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | */ |
6 | |
7 | #include <linux/time.h> |
8 | #include <linux/proc_fs.h> |
9 | #include <linux/kernel.h> |
10 | #include <linux/mm.h> |
11 | #include <linux/string.h> |
12 | #include <linux/stat.h> |
13 | #include <linux/completion.h> |
14 | #include <linux/poll.h> |
15 | #include <linux/file.h> |
16 | #include <linux/limits.h> |
17 | #include <linux/init.h> |
18 | #include <linux/module.h> |
19 | #include <linux/sysctl.h> |
20 | #include <linux/slab.h> |
21 | |
22 | #include <asm/system.h> |
23 | #include <asm/uaccess.h> |
24 | |
25 | #include "internal.h" |
26 | |
27 | static void proc_evict_inode(struct inode *inode) |
28 | { |
29 | struct proc_dir_entry *de; |
30 | struct ctl_table_header *head; |
31 | const struct proc_ns_operations *ns_ops; |
32 | |
33 | truncate_inode_pages(&inode->i_data, 0); |
34 | end_writeback(inode); |
35 | |
36 | /* Stop tracking associated processes */ |
37 | put_pid(PROC_I(inode)->pid); |
38 | |
39 | /* Let go of any associated proc directory entry */ |
40 | de = PROC_I(inode)->pde; |
41 | if (de) |
42 | pde_put(de); |
43 | head = PROC_I(inode)->sysctl; |
44 | if (head) { |
45 | rcu_assign_pointer(PROC_I(inode)->sysctl, NULL); |
46 | sysctl_head_put(head); |
47 | } |
48 | /* Release any associated namespace */ |
49 | ns_ops = PROC_I(inode)->ns_ops; |
50 | if (ns_ops && ns_ops->put) |
51 | ns_ops->put(PROC_I(inode)->ns); |
52 | } |
53 | |
54 | static struct kmem_cache * proc_inode_cachep; |
55 | |
56 | static struct inode *proc_alloc_inode(struct super_block *sb) |
57 | { |
58 | struct proc_inode *ei; |
59 | struct inode *inode; |
60 | |
61 | ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL); |
62 | if (!ei) |
63 | return NULL; |
64 | ei->pid = NULL; |
65 | ei->fd = 0; |
66 | ei->op.proc_get_link = NULL; |
67 | ei->pde = NULL; |
68 | ei->sysctl = NULL; |
69 | ei->sysctl_entry = NULL; |
70 | ei->ns = NULL; |
71 | ei->ns_ops = NULL; |
72 | inode = &ei->vfs_inode; |
73 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
74 | return inode; |
75 | } |
76 | |
77 | static void proc_i_callback(struct rcu_head *head) |
78 | { |
79 | struct inode *inode = container_of(head, struct inode, i_rcu); |
80 | INIT_LIST_HEAD(&inode->i_dentry); |
81 | kmem_cache_free(proc_inode_cachep, PROC_I(inode)); |
82 | } |
83 | |
84 | static void proc_destroy_inode(struct inode *inode) |
85 | { |
86 | call_rcu(&inode->i_rcu, proc_i_callback); |
87 | } |
88 | |
89 | static void init_once(void *foo) |
90 | { |
91 | struct proc_inode *ei = (struct proc_inode *) foo; |
92 | |
93 | inode_init_once(&ei->vfs_inode); |
94 | } |
95 | |
96 | void __init proc_init_inodecache(void) |
97 | { |
98 | proc_inode_cachep = kmem_cache_create("proc_inode_cache", |
99 | sizeof(struct proc_inode), |
100 | 0, (SLAB_RECLAIM_ACCOUNT| |
101 | SLAB_MEM_SPREAD|SLAB_PANIC), |
102 | init_once); |
103 | } |
104 | |
105 | static const struct super_operations proc_sops = { |
106 | .alloc_inode = proc_alloc_inode, |
107 | .destroy_inode = proc_destroy_inode, |
108 | .drop_inode = generic_delete_inode, |
109 | .evict_inode = proc_evict_inode, |
110 | .statfs = simple_statfs, |
111 | }; |
112 | |
113 | static void __pde_users_dec(struct proc_dir_entry *pde) |
114 | { |
115 | pde->pde_users--; |
116 | if (pde->pde_unload_completion && pde->pde_users == 0) |
117 | complete(pde->pde_unload_completion); |
118 | } |
119 | |
120 | void pde_users_dec(struct proc_dir_entry *pde) |
121 | { |
122 | spin_lock(&pde->pde_unload_lock); |
123 | __pde_users_dec(pde); |
124 | spin_unlock(&pde->pde_unload_lock); |
125 | } |
126 | |
127 | static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence) |
128 | { |
129 | struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); |
130 | loff_t rv = -EINVAL; |
131 | loff_t (*llseek)(struct file *, loff_t, int); |
132 | |
133 | spin_lock(&pde->pde_unload_lock); |
134 | /* |
135 | * remove_proc_entry() is going to delete PDE (as part of module |
136 | * cleanup sequence). No new callers into module allowed. |
137 | */ |
138 | if (!pde->proc_fops) { |
139 | spin_unlock(&pde->pde_unload_lock); |
140 | return rv; |
141 | } |
142 | /* |
143 | * Bump refcount so that remove_proc_entry will wail for ->llseek to |
144 | * complete. |
145 | */ |
146 | pde->pde_users++; |
147 | /* |
148 | * Save function pointer under lock, to protect against ->proc_fops |
149 | * NULL'ifying right after ->pde_unload_lock is dropped. |
150 | */ |
151 | llseek = pde->proc_fops->llseek; |
152 | spin_unlock(&pde->pde_unload_lock); |
153 | |
154 | if (!llseek) |
155 | llseek = default_llseek; |
156 | rv = llseek(file, offset, whence); |
157 | |
158 | pde_users_dec(pde); |
159 | return rv; |
160 | } |
161 | |
162 | static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) |
163 | { |
164 | struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); |
165 | ssize_t rv = -EIO; |
166 | ssize_t (*read)(struct file *, char __user *, size_t, loff_t *); |
167 | |
168 | spin_lock(&pde->pde_unload_lock); |
169 | if (!pde->proc_fops) { |
170 | spin_unlock(&pde->pde_unload_lock); |
171 | return rv; |
172 | } |
173 | pde->pde_users++; |
174 | read = pde->proc_fops->read; |
175 | spin_unlock(&pde->pde_unload_lock); |
176 | |
177 | if (read) |
178 | rv = read(file, buf, count, ppos); |
179 | |
180 | pde_users_dec(pde); |
181 | return rv; |
182 | } |
183 | |
184 | static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) |
185 | { |
186 | struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); |
187 | ssize_t rv = -EIO; |
188 | ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *); |
189 | |
190 | spin_lock(&pde->pde_unload_lock); |
191 | if (!pde->proc_fops) { |
192 | spin_unlock(&pde->pde_unload_lock); |
193 | return rv; |
194 | } |
195 | pde->pde_users++; |
196 | write = pde->proc_fops->write; |
197 | spin_unlock(&pde->pde_unload_lock); |
198 | |
199 | if (write) |
200 | rv = write(file, buf, count, ppos); |
201 | |
202 | pde_users_dec(pde); |
203 | return rv; |
204 | } |
205 | |
206 | static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts) |
207 | { |
208 | struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); |
209 | unsigned int rv = DEFAULT_POLLMASK; |
210 | unsigned int (*poll)(struct file *, struct poll_table_struct *); |
211 | |
212 | spin_lock(&pde->pde_unload_lock); |
213 | if (!pde->proc_fops) { |
214 | spin_unlock(&pde->pde_unload_lock); |
215 | return rv; |
216 | } |
217 | pde->pde_users++; |
218 | poll = pde->proc_fops->poll; |
219 | spin_unlock(&pde->pde_unload_lock); |
220 | |
221 | if (poll) |
222 | rv = poll(file, pts); |
223 | |
224 | pde_users_dec(pde); |
225 | return rv; |
226 | } |
227 | |
228 | static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
229 | { |
230 | struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); |
231 | long rv = -ENOTTY; |
232 | long (*ioctl)(struct file *, unsigned int, unsigned long); |
233 | |
234 | spin_lock(&pde->pde_unload_lock); |
235 | if (!pde->proc_fops) { |
236 | spin_unlock(&pde->pde_unload_lock); |
237 | return rv; |
238 | } |
239 | pde->pde_users++; |
240 | ioctl = pde->proc_fops->unlocked_ioctl; |
241 | spin_unlock(&pde->pde_unload_lock); |
242 | |
243 | if (ioctl) |
244 | rv = ioctl(file, cmd, arg); |
245 | |
246 | pde_users_dec(pde); |
247 | return rv; |
248 | } |
249 | |
250 | #ifdef CONFIG_COMPAT |
251 | static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
252 | { |
253 | struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); |
254 | long rv = -ENOTTY; |
255 | long (*compat_ioctl)(struct file *, unsigned int, unsigned long); |
256 | |
257 | spin_lock(&pde->pde_unload_lock); |
258 | if (!pde->proc_fops) { |
259 | spin_unlock(&pde->pde_unload_lock); |
260 | return rv; |
261 | } |
262 | pde->pde_users++; |
263 | compat_ioctl = pde->proc_fops->compat_ioctl; |
264 | spin_unlock(&pde->pde_unload_lock); |
265 | |
266 | if (compat_ioctl) |
267 | rv = compat_ioctl(file, cmd, arg); |
268 | |
269 | pde_users_dec(pde); |
270 | return rv; |
271 | } |
272 | #endif |
273 | |
274 | static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma) |
275 | { |
276 | struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); |
277 | int rv = -EIO; |
278 | int (*mmap)(struct file *, struct vm_area_struct *); |
279 | |
280 | spin_lock(&pde->pde_unload_lock); |
281 | if (!pde->proc_fops) { |
282 | spin_unlock(&pde->pde_unload_lock); |
283 | return rv; |
284 | } |
285 | pde->pde_users++; |
286 | mmap = pde->proc_fops->mmap; |
287 | spin_unlock(&pde->pde_unload_lock); |
288 | |
289 | if (mmap) |
290 | rv = mmap(file, vma); |
291 | |
292 | pde_users_dec(pde); |
293 | return rv; |
294 | } |
295 | |
296 | static int proc_reg_open(struct inode *inode, struct file *file) |
297 | { |
298 | struct proc_dir_entry *pde = PDE(inode); |
299 | int rv = 0; |
300 | int (*open)(struct inode *, struct file *); |
301 | int (*release)(struct inode *, struct file *); |
302 | struct pde_opener *pdeo; |
303 | |
304 | /* |
305 | * What for, you ask? Well, we can have open, rmmod, remove_proc_entry |
306 | * sequence. ->release won't be called because ->proc_fops will be |
307 | * cleared. Depending on complexity of ->release, consequences vary. |
308 | * |
309 | * We can't wait for mercy when close will be done for real, it's |
310 | * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release |
311 | * by hand in remove_proc_entry(). For this, save opener's credentials |
312 | * for later. |
313 | */ |
314 | pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL); |
315 | if (!pdeo) |
316 | return -ENOMEM; |
317 | |
318 | spin_lock(&pde->pde_unload_lock); |
319 | if (!pde->proc_fops) { |
320 | spin_unlock(&pde->pde_unload_lock); |
321 | kfree(pdeo); |
322 | return -EINVAL; |
323 | } |
324 | pde->pde_users++; |
325 | open = pde->proc_fops->open; |
326 | release = pde->proc_fops->release; |
327 | spin_unlock(&pde->pde_unload_lock); |
328 | |
329 | if (open) |
330 | rv = open(inode, file); |
331 | |
332 | spin_lock(&pde->pde_unload_lock); |
333 | if (rv == 0 && release) { |
334 | /* To know what to release. */ |
335 | pdeo->inode = inode; |
336 | pdeo->file = file; |
337 | /* Strictly for "too late" ->release in proc_reg_release(). */ |
338 | pdeo->release = release; |
339 | list_add(&pdeo->lh, &pde->pde_openers); |
340 | } else |
341 | kfree(pdeo); |
342 | __pde_users_dec(pde); |
343 | spin_unlock(&pde->pde_unload_lock); |
344 | return rv; |
345 | } |
346 | |
347 | static struct pde_opener *find_pde_opener(struct proc_dir_entry *pde, |
348 | struct inode *inode, struct file *file) |
349 | { |
350 | struct pde_opener *pdeo; |
351 | |
352 | list_for_each_entry(pdeo, &pde->pde_openers, lh) { |
353 | if (pdeo->inode == inode && pdeo->file == file) |
354 | return pdeo; |
355 | } |
356 | return NULL; |
357 | } |
358 | |
359 | static int proc_reg_release(struct inode *inode, struct file *file) |
360 | { |
361 | struct proc_dir_entry *pde = PDE(inode); |
362 | int rv = 0; |
363 | int (*release)(struct inode *, struct file *); |
364 | struct pde_opener *pdeo; |
365 | |
366 | spin_lock(&pde->pde_unload_lock); |
367 | pdeo = find_pde_opener(pde, inode, file); |
368 | if (!pde->proc_fops) { |
369 | /* |
370 | * Can't simply exit, __fput() will think that everything is OK, |
371 | * and move on to freeing struct file. remove_proc_entry() will |
372 | * find slacker in opener's list and will try to do non-trivial |
373 | * things with struct file. Therefore, remove opener from list. |
374 | * |
375 | * But if opener is removed from list, who will ->release it? |
376 | */ |
377 | if (pdeo) { |
378 | list_del(&pdeo->lh); |
379 | spin_unlock(&pde->pde_unload_lock); |
380 | rv = pdeo->release(inode, file); |
381 | kfree(pdeo); |
382 | } else |
383 | spin_unlock(&pde->pde_unload_lock); |
384 | return rv; |
385 | } |
386 | pde->pde_users++; |
387 | release = pde->proc_fops->release; |
388 | if (pdeo) { |
389 | list_del(&pdeo->lh); |
390 | kfree(pdeo); |
391 | } |
392 | spin_unlock(&pde->pde_unload_lock); |
393 | |
394 | if (release) |
395 | rv = release(inode, file); |
396 | |
397 | pde_users_dec(pde); |
398 | return rv; |
399 | } |
400 | |
401 | static const struct file_operations proc_reg_file_ops = { |
402 | .llseek = proc_reg_llseek, |
403 | .read = proc_reg_read, |
404 | .write = proc_reg_write, |
405 | .poll = proc_reg_poll, |
406 | .unlocked_ioctl = proc_reg_unlocked_ioctl, |
407 | #ifdef CONFIG_COMPAT |
408 | .compat_ioctl = proc_reg_compat_ioctl, |
409 | #endif |
410 | .mmap = proc_reg_mmap, |
411 | .open = proc_reg_open, |
412 | .release = proc_reg_release, |
413 | }; |
414 | |
415 | #ifdef CONFIG_COMPAT |
416 | static const struct file_operations proc_reg_file_ops_no_compat = { |
417 | .llseek = proc_reg_llseek, |
418 | .read = proc_reg_read, |
419 | .write = proc_reg_write, |
420 | .poll = proc_reg_poll, |
421 | .unlocked_ioctl = proc_reg_unlocked_ioctl, |
422 | .mmap = proc_reg_mmap, |
423 | .open = proc_reg_open, |
424 | .release = proc_reg_release, |
425 | }; |
426 | #endif |
427 | |
428 | struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) |
429 | { |
430 | struct inode * inode; |
431 | |
432 | inode = iget_locked(sb, de->low_ino); |
433 | if (!inode) |
434 | return NULL; |
435 | if (inode->i_state & I_NEW) { |
436 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
437 | PROC_I(inode)->fd = 0; |
438 | PROC_I(inode)->pde = de; |
439 | |
440 | if (de->mode) { |
441 | inode->i_mode = de->mode; |
442 | inode->i_uid = de->uid; |
443 | inode->i_gid = de->gid; |
444 | } |
445 | if (de->size) |
446 | inode->i_size = de->size; |
447 | if (de->nlink) |
448 | inode->i_nlink = de->nlink; |
449 | if (de->proc_iops) |
450 | inode->i_op = de->proc_iops; |
451 | if (de->proc_fops) { |
452 | if (S_ISREG(inode->i_mode)) { |
453 | #ifdef CONFIG_COMPAT |
454 | if (!de->proc_fops->compat_ioctl) |
455 | inode->i_fop = |
456 | &proc_reg_file_ops_no_compat; |
457 | else |
458 | #endif |
459 | inode->i_fop = &proc_reg_file_ops; |
460 | } else { |
461 | inode->i_fop = de->proc_fops; |
462 | } |
463 | } |
464 | unlock_new_inode(inode); |
465 | } else |
466 | pde_put(de); |
467 | return inode; |
468 | } |
469 | |
470 | int proc_fill_super(struct super_block *s) |
471 | { |
472 | struct inode * root_inode; |
473 | |
474 | s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC; |
475 | s->s_blocksize = 1024; |
476 | s->s_blocksize_bits = 10; |
477 | s->s_magic = PROC_SUPER_MAGIC; |
478 | s->s_op = &proc_sops; |
479 | s->s_time_gran = 1; |
480 | |
481 | pde_get(&proc_root); |
482 | root_inode = proc_get_inode(s, &proc_root); |
483 | if (!root_inode) |
484 | goto out_no_root; |
485 | root_inode->i_uid = 0; |
486 | root_inode->i_gid = 0; |
487 | s->s_root = d_alloc_root(root_inode); |
488 | if (!s->s_root) |
489 | goto out_no_root; |
490 | return 0; |
491 | |
492 | out_no_root: |
493 | printk("proc_read_super: get root inode failed\n"); |
494 | iput(root_inode); |
495 | pde_put(&proc_root); |
496 | return -ENOMEM; |
497 | } |
498 |
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