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Commit | Line | Data |
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1 | /* | |
2 | * /proc/sys support | |
3 | */ | |
4 | #include <linux/init.h> | |
5 | #include <linux/sysctl.h> | |
6 | #include <linux/poll.h> | |
7 | #include <linux/proc_fs.h> | |
8 | #include <linux/security.h> | |
9 | #include <linux/namei.h> | |
10 | #include "internal.h" | |
11 | ||
12 | static const struct dentry_operations proc_sys_dentry_operations; | |
13 | static const struct file_operations proc_sys_file_operations; | |
14 | static const struct inode_operations proc_sys_inode_operations; | |
15 | static const struct file_operations proc_sys_dir_file_operations; | |
16 | static const struct inode_operations proc_sys_dir_operations; | |
17 | ||
18 | void proc_sys_poll_notify(struct ctl_table_poll *poll) | |
19 | { | |
20 | if (!poll) | |
21 | return; | |
22 | ||
23 | atomic_inc(&poll->event); | |
24 | wake_up_interruptible(&poll->wait); | |
25 | } | |
26 | ||
27 | static struct inode *proc_sys_make_inode(struct super_block *sb, | |
28 | struct ctl_table_header *head, struct ctl_table *table) | |
29 | { | |
30 | struct inode *inode; | |
31 | struct proc_inode *ei; | |
32 | ||
33 | inode = new_inode(sb); | |
34 | if (!inode) | |
35 | goto out; | |
36 | ||
37 | inode->i_ino = get_next_ino(); | |
38 | ||
39 | sysctl_head_get(head); | |
40 | ei = PROC_I(inode); | |
41 | ei->sysctl = head; | |
42 | ei->sysctl_entry = table; | |
43 | ||
44 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
45 | inode->i_mode = table->mode; | |
46 | if (!table->child) { | |
47 | inode->i_mode |= S_IFREG; | |
48 | inode->i_op = &proc_sys_inode_operations; | |
49 | inode->i_fop = &proc_sys_file_operations; | |
50 | } else { | |
51 | inode->i_mode |= S_IFDIR; | |
52 | clear_nlink(inode); | |
53 | inode->i_op = &proc_sys_dir_operations; | |
54 | inode->i_fop = &proc_sys_dir_file_operations; | |
55 | } | |
56 | out: | |
57 | return inode; | |
58 | } | |
59 | ||
60 | static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name) | |
61 | { | |
62 | for ( ; p->procname; p++) { | |
63 | if (strlen(p->procname) != name->len) | |
64 | continue; | |
65 | ||
66 | if (memcmp(p->procname, name->name, name->len) != 0) | |
67 | continue; | |
68 | ||
69 | /* I have a match */ | |
70 | return p; | |
71 | } | |
72 | return NULL; | |
73 | } | |
74 | ||
75 | static struct ctl_table_header *grab_header(struct inode *inode) | |
76 | { | |
77 | if (PROC_I(inode)->sysctl) | |
78 | return sysctl_head_grab(PROC_I(inode)->sysctl); | |
79 | else | |
80 | return sysctl_head_next(NULL); | |
81 | } | |
82 | ||
83 | static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, | |
84 | struct nameidata *nd) | |
85 | { | |
86 | struct ctl_table_header *head = grab_header(dir); | |
87 | struct ctl_table *table = PROC_I(dir)->sysctl_entry; | |
88 | struct ctl_table_header *h = NULL; | |
89 | struct qstr *name = &dentry->d_name; | |
90 | struct ctl_table *p; | |
91 | struct inode *inode; | |
92 | struct dentry *err = ERR_PTR(-ENOENT); | |
93 | ||
94 | if (IS_ERR(head)) | |
95 | return ERR_CAST(head); | |
96 | ||
97 | if (table && !table->child) { | |
98 | WARN_ON(1); | |
99 | goto out; | |
100 | } | |
101 | ||
102 | table = table ? table->child : head->ctl_table; | |
103 | ||
104 | p = find_in_table(table, name); | |
105 | if (!p) { | |
106 | for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { | |
107 | if (h->attached_to != table) | |
108 | continue; | |
109 | p = find_in_table(h->attached_by, name); | |
110 | if (p) | |
111 | break; | |
112 | } | |
113 | } | |
114 | ||
115 | if (!p) | |
116 | goto out; | |
117 | ||
118 | err = ERR_PTR(-ENOMEM); | |
119 | inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); | |
120 | if (h) | |
121 | sysctl_head_finish(h); | |
122 | ||
123 | if (!inode) | |
124 | goto out; | |
125 | ||
126 | err = NULL; | |
127 | d_set_d_op(dentry, &proc_sys_dentry_operations); | |
128 | d_add(dentry, inode); | |
129 | ||
130 | out: | |
131 | sysctl_head_finish(head); | |
132 | return err; | |
133 | } | |
134 | ||
135 | static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf, | |
136 | size_t count, loff_t *ppos, int write) | |
137 | { | |
138 | struct inode *inode = filp->f_path.dentry->d_inode; | |
139 | struct ctl_table_header *head = grab_header(inode); | |
140 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
141 | ssize_t error; | |
142 | size_t res; | |
143 | ||
144 | if (IS_ERR(head)) | |
145 | return PTR_ERR(head); | |
146 | ||
147 | /* | |
148 | * At this point we know that the sysctl was not unregistered | |
149 | * and won't be until we finish. | |
150 | */ | |
151 | error = -EPERM; | |
152 | if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ)) | |
153 | goto out; | |
154 | ||
155 | /* if that can happen at all, it should be -EINVAL, not -EISDIR */ | |
156 | error = -EINVAL; | |
157 | if (!table->proc_handler) | |
158 | goto out; | |
159 | ||
160 | /* careful: calling conventions are nasty here */ | |
161 | res = count; | |
162 | error = table->proc_handler(table, write, buf, &res, ppos); | |
163 | if (!error) | |
164 | error = res; | |
165 | out: | |
166 | sysctl_head_finish(head); | |
167 | ||
168 | return error; | |
169 | } | |
170 | ||
171 | static ssize_t proc_sys_read(struct file *filp, char __user *buf, | |
172 | size_t count, loff_t *ppos) | |
173 | { | |
174 | return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0); | |
175 | } | |
176 | ||
177 | static ssize_t proc_sys_write(struct file *filp, const char __user *buf, | |
178 | size_t count, loff_t *ppos) | |
179 | { | |
180 | return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1); | |
181 | } | |
182 | ||
183 | static int proc_sys_open(struct inode *inode, struct file *filp) | |
184 | { | |
185 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
186 | ||
187 | if (table->poll) | |
188 | filp->private_data = proc_sys_poll_event(table->poll); | |
189 | ||
190 | return 0; | |
191 | } | |
192 | ||
193 | static unsigned int proc_sys_poll(struct file *filp, poll_table *wait) | |
194 | { | |
195 | struct inode *inode = filp->f_path.dentry->d_inode; | |
196 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
197 | unsigned long event = (unsigned long)filp->private_data; | |
198 | unsigned int ret = DEFAULT_POLLMASK; | |
199 | ||
200 | if (!table->proc_handler) | |
201 | goto out; | |
202 | ||
203 | if (!table->poll) | |
204 | goto out; | |
205 | ||
206 | poll_wait(filp, &table->poll->wait, wait); | |
207 | ||
208 | if (event != atomic_read(&table->poll->event)) { | |
209 | filp->private_data = proc_sys_poll_event(table->poll); | |
210 | ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI; | |
211 | } | |
212 | ||
213 | out: | |
214 | return ret; | |
215 | } | |
216 | ||
217 | static int proc_sys_fill_cache(struct file *filp, void *dirent, | |
218 | filldir_t filldir, | |
219 | struct ctl_table_header *head, | |
220 | struct ctl_table *table) | |
221 | { | |
222 | struct dentry *child, *dir = filp->f_path.dentry; | |
223 | struct inode *inode; | |
224 | struct qstr qname; | |
225 | ino_t ino = 0; | |
226 | unsigned type = DT_UNKNOWN; | |
227 | ||
228 | qname.name = table->procname; | |
229 | qname.len = strlen(table->procname); | |
230 | qname.hash = full_name_hash(qname.name, qname.len); | |
231 | ||
232 | child = d_lookup(dir, &qname); | |
233 | if (!child) { | |
234 | child = d_alloc(dir, &qname); | |
235 | if (child) { | |
236 | inode = proc_sys_make_inode(dir->d_sb, head, table); | |
237 | if (!inode) { | |
238 | dput(child); | |
239 | return -ENOMEM; | |
240 | } else { | |
241 | d_set_d_op(child, &proc_sys_dentry_operations); | |
242 | d_add(child, inode); | |
243 | } | |
244 | } else { | |
245 | return -ENOMEM; | |
246 | } | |
247 | } | |
248 | inode = child->d_inode; | |
249 | ino = inode->i_ino; | |
250 | type = inode->i_mode >> 12; | |
251 | dput(child); | |
252 | return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type); | |
253 | } | |
254 | ||
255 | static int scan(struct ctl_table_header *head, ctl_table *table, | |
256 | unsigned long *pos, struct file *file, | |
257 | void *dirent, filldir_t filldir) | |
258 | { | |
259 | ||
260 | for (; table->procname; table++, (*pos)++) { | |
261 | int res; | |
262 | ||
263 | if (*pos < file->f_pos) | |
264 | continue; | |
265 | ||
266 | res = proc_sys_fill_cache(file, dirent, filldir, head, table); | |
267 | if (res) | |
268 | return res; | |
269 | ||
270 | file->f_pos = *pos + 1; | |
271 | } | |
272 | return 0; | |
273 | } | |
274 | ||
275 | static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir) | |
276 | { | |
277 | struct dentry *dentry = filp->f_path.dentry; | |
278 | struct inode *inode = dentry->d_inode; | |
279 | struct ctl_table_header *head = grab_header(inode); | |
280 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
281 | struct ctl_table_header *h = NULL; | |
282 | unsigned long pos; | |
283 | int ret = -EINVAL; | |
284 | ||
285 | if (IS_ERR(head)) | |
286 | return PTR_ERR(head); | |
287 | ||
288 | if (table && !table->child) { | |
289 | WARN_ON(1); | |
290 | goto out; | |
291 | } | |
292 | ||
293 | table = table ? table->child : head->ctl_table; | |
294 | ||
295 | ret = 0; | |
296 | /* Avoid a switch here: arm builds fail with missing __cmpdi2 */ | |
297 | if (filp->f_pos == 0) { | |
298 | if (filldir(dirent, ".", 1, filp->f_pos, | |
299 | inode->i_ino, DT_DIR) < 0) | |
300 | goto out; | |
301 | filp->f_pos++; | |
302 | } | |
303 | if (filp->f_pos == 1) { | |
304 | if (filldir(dirent, "..", 2, filp->f_pos, | |
305 | parent_ino(dentry), DT_DIR) < 0) | |
306 | goto out; | |
307 | filp->f_pos++; | |
308 | } | |
309 | pos = 2; | |
310 | ||
311 | ret = scan(head, table, &pos, filp, dirent, filldir); | |
312 | if (ret) | |
313 | goto out; | |
314 | ||
315 | for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { | |
316 | if (h->attached_to != table) | |
317 | continue; | |
318 | ret = scan(h, h->attached_by, &pos, filp, dirent, filldir); | |
319 | if (ret) { | |
320 | sysctl_head_finish(h); | |
321 | break; | |
322 | } | |
323 | } | |
324 | ret = 1; | |
325 | out: | |
326 | sysctl_head_finish(head); | |
327 | return ret; | |
328 | } | |
329 | ||
330 | static int proc_sys_permission(struct inode *inode, int mask) | |
331 | { | |
332 | /* | |
333 | * sysctl entries that are not writeable, | |
334 | * are _NOT_ writeable, capabilities or not. | |
335 | */ | |
336 | struct ctl_table_header *head; | |
337 | struct ctl_table *table; | |
338 | int error; | |
339 | ||
340 | /* Executable files are not allowed under /proc/sys/ */ | |
341 | if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) | |
342 | return -EACCES; | |
343 | ||
344 | head = grab_header(inode); | |
345 | if (IS_ERR(head)) | |
346 | return PTR_ERR(head); | |
347 | ||
348 | table = PROC_I(inode)->sysctl_entry; | |
349 | if (!table) /* global root - r-xr-xr-x */ | |
350 | error = mask & MAY_WRITE ? -EACCES : 0; | |
351 | else /* Use the permissions on the sysctl table entry */ | |
352 | error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK); | |
353 | ||
354 | sysctl_head_finish(head); | |
355 | return error; | |
356 | } | |
357 | ||
358 | static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr) | |
359 | { | |
360 | struct inode *inode = dentry->d_inode; | |
361 | int error; | |
362 | ||
363 | if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) | |
364 | return -EPERM; | |
365 | ||
366 | error = inode_change_ok(inode, attr); | |
367 | if (error) | |
368 | return error; | |
369 | ||
370 | if ((attr->ia_valid & ATTR_SIZE) && | |
371 | attr->ia_size != i_size_read(inode)) { | |
372 | error = vmtruncate(inode, attr->ia_size); | |
373 | if (error) | |
374 | return error; | |
375 | } | |
376 | ||
377 | setattr_copy(inode, attr); | |
378 | mark_inode_dirty(inode); | |
379 | return 0; | |
380 | } | |
381 | ||
382 | static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) | |
383 | { | |
384 | struct inode *inode = dentry->d_inode; | |
385 | struct ctl_table_header *head = grab_header(inode); | |
386 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
387 | ||
388 | if (IS_ERR(head)) | |
389 | return PTR_ERR(head); | |
390 | ||
391 | generic_fillattr(inode, stat); | |
392 | if (table) | |
393 | stat->mode = (stat->mode & S_IFMT) | table->mode; | |
394 | ||
395 | sysctl_head_finish(head); | |
396 | return 0; | |
397 | } | |
398 | ||
399 | static const struct file_operations proc_sys_file_operations = { | |
400 | .open = proc_sys_open, | |
401 | .poll = proc_sys_poll, | |
402 | .read = proc_sys_read, | |
403 | .write = proc_sys_write, | |
404 | .llseek = default_llseek, | |
405 | }; | |
406 | ||
407 | static const struct file_operations proc_sys_dir_file_operations = { | |
408 | .read = generic_read_dir, | |
409 | .readdir = proc_sys_readdir, | |
410 | .llseek = generic_file_llseek, | |
411 | }; | |
412 | ||
413 | static const struct inode_operations proc_sys_inode_operations = { | |
414 | .permission = proc_sys_permission, | |
415 | .setattr = proc_sys_setattr, | |
416 | .getattr = proc_sys_getattr, | |
417 | }; | |
418 | ||
419 | static const struct inode_operations proc_sys_dir_operations = { | |
420 | .lookup = proc_sys_lookup, | |
421 | .permission = proc_sys_permission, | |
422 | .setattr = proc_sys_setattr, | |
423 | .getattr = proc_sys_getattr, | |
424 | }; | |
425 | ||
426 | static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd) | |
427 | { | |
428 | if (nd->flags & LOOKUP_RCU) | |
429 | return -ECHILD; | |
430 | return !PROC_I(dentry->d_inode)->sysctl->unregistering; | |
431 | } | |
432 | ||
433 | static int proc_sys_delete(const struct dentry *dentry) | |
434 | { | |
435 | return !!PROC_I(dentry->d_inode)->sysctl->unregistering; | |
436 | } | |
437 | ||
438 | static int proc_sys_compare(const struct dentry *parent, | |
439 | const struct inode *pinode, | |
440 | const struct dentry *dentry, const struct inode *inode, | |
441 | unsigned int len, const char *str, const struct qstr *name) | |
442 | { | |
443 | struct ctl_table_header *head; | |
444 | /* Although proc doesn't have negative dentries, rcu-walk means | |
445 | * that inode here can be NULL */ | |
446 | /* AV: can it, indeed? */ | |
447 | if (!inode) | |
448 | return 1; | |
449 | if (name->len != len) | |
450 | return 1; | |
451 | if (memcmp(name->name, str, len)) | |
452 | return 1; | |
453 | head = rcu_dereference(PROC_I(inode)->sysctl); | |
454 | return !head || !sysctl_is_seen(head); | |
455 | } | |
456 | ||
457 | static const struct dentry_operations proc_sys_dentry_operations = { | |
458 | .d_revalidate = proc_sys_revalidate, | |
459 | .d_delete = proc_sys_delete, | |
460 | .d_compare = proc_sys_compare, | |
461 | }; | |
462 | ||
463 | int __init proc_sys_init(void) | |
464 | { | |
465 | struct proc_dir_entry *proc_sys_root; | |
466 | ||
467 | proc_sys_root = proc_mkdir("sys", NULL); | |
468 | proc_sys_root->proc_iops = &proc_sys_dir_operations; | |
469 | proc_sys_root->proc_fops = &proc_sys_dir_file_operations; | |
470 | proc_sys_root->nlink = 0; | |
471 | return 0; | |
472 | } |