Commit | Line | Data |
---|---|---|
77b14db5 EB |
1 | /* |
2 | * /proc/sys support | |
3 | */ | |
1e0edd3f | 4 | #include <linux/init.h> |
77b14db5 | 5 | #include <linux/sysctl.h> |
f1ecf068 | 6 | #include <linux/poll.h> |
77b14db5 EB |
7 | #include <linux/proc_fs.h> |
8 | #include <linux/security.h> | |
34286d66 | 9 | #include <linux/namei.h> |
77b14db5 EB |
10 | #include "internal.h" |
11 | ||
d72f71eb | 12 | static const struct dentry_operations proc_sys_dentry_operations; |
77b14db5 | 13 | static const struct file_operations proc_sys_file_operations; |
03a44825 | 14 | static const struct inode_operations proc_sys_inode_operations; |
9043476f AV |
15 | static const struct file_operations proc_sys_dir_file_operations; |
16 | static const struct inode_operations proc_sys_dir_operations; | |
77b14db5 | 17 | |
f1ecf068 LDM |
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 | ||
9043476f AV |
27 | static struct inode *proc_sys_make_inode(struct super_block *sb, |
28 | struct ctl_table_header *head, struct ctl_table *table) | |
77b14db5 EB |
29 | { |
30 | struct inode *inode; | |
9043476f | 31 | struct proc_inode *ei; |
77b14db5 | 32 | |
9043476f | 33 | inode = new_inode(sb); |
77b14db5 EB |
34 | if (!inode) |
35 | goto out; | |
36 | ||
85fe4025 CH |
37 | inode->i_ino = get_next_ino(); |
38 | ||
9043476f | 39 | sysctl_head_get(head); |
77b14db5 | 40 | ei = PROC_I(inode); |
9043476f AV |
41 | ei->sysctl = head; |
42 | ei->sysctl_entry = table; | |
43 | ||
77b14db5 | 44 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
9043476f AV |
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; | |
6d6b77f1 | 52 | clear_nlink(inode); |
9043476f AV |
53 | inode->i_op = &proc_sys_dir_operations; |
54 | inode->i_fop = &proc_sys_dir_file_operations; | |
55 | } | |
77b14db5 EB |
56 | out: |
57 | return inode; | |
58 | } | |
59 | ||
9043476f | 60 | static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name) |
77b14db5 EB |
61 | { |
62 | int len; | |
2315ffa0 | 63 | for ( ; p->procname; p++) { |
77b14db5 | 64 | |
9043476f | 65 | if (!p->procname) |
77b14db5 EB |
66 | continue; |
67 | ||
9043476f | 68 | len = strlen(p->procname); |
77b14db5 EB |
69 | if (len != name->len) |
70 | continue; | |
71 | ||
9043476f | 72 | if (memcmp(p->procname, name->name, len) != 0) |
77b14db5 EB |
73 | continue; |
74 | ||
75 | /* I have a match */ | |
9043476f | 76 | return p; |
77b14db5 EB |
77 | } |
78 | return NULL; | |
79 | } | |
80 | ||
81324364 | 81 | static struct ctl_table_header *grab_header(struct inode *inode) |
77b14db5 | 82 | { |
9043476f AV |
83 | if (PROC_I(inode)->sysctl) |
84 | return sysctl_head_grab(PROC_I(inode)->sysctl); | |
85 | else | |
86 | return sysctl_head_next(NULL); | |
87 | } | |
77b14db5 | 88 | |
9043476f AV |
89 | static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, |
90 | struct nameidata *nd) | |
91 | { | |
92 | struct ctl_table_header *head = grab_header(dir); | |
93 | struct ctl_table *table = PROC_I(dir)->sysctl_entry; | |
94 | struct ctl_table_header *h = NULL; | |
95 | struct qstr *name = &dentry->d_name; | |
96 | struct ctl_table *p; | |
97 | struct inode *inode; | |
98 | struct dentry *err = ERR_PTR(-ENOENT); | |
77b14db5 | 99 | |
9043476f AV |
100 | if (IS_ERR(head)) |
101 | return ERR_CAST(head); | |
77b14db5 | 102 | |
9043476f AV |
103 | if (table && !table->child) { |
104 | WARN_ON(1); | |
105 | goto out; | |
77b14db5 | 106 | } |
77b14db5 | 107 | |
9043476f | 108 | table = table ? table->child : head->ctl_table; |
77b14db5 | 109 | |
9043476f AV |
110 | p = find_in_table(table, name); |
111 | if (!p) { | |
112 | for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { | |
113 | if (h->attached_to != table) | |
114 | continue; | |
115 | p = find_in_table(h->attached_by, name); | |
116 | if (p) | |
117 | break; | |
118 | } | |
77b14db5 | 119 | } |
77b14db5 | 120 | |
9043476f | 121 | if (!p) |
77b14db5 EB |
122 | goto out; |
123 | ||
124 | err = ERR_PTR(-ENOMEM); | |
9043476f AV |
125 | inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); |
126 | if (h) | |
127 | sysctl_head_finish(h); | |
128 | ||
77b14db5 EB |
129 | if (!inode) |
130 | goto out; | |
131 | ||
132 | err = NULL; | |
fb045adb | 133 | d_set_d_op(dentry, &proc_sys_dentry_operations); |
77b14db5 EB |
134 | d_add(dentry, inode); |
135 | ||
136 | out: | |
137 | sysctl_head_finish(head); | |
138 | return err; | |
139 | } | |
140 | ||
7708bfb1 PE |
141 | static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf, |
142 | size_t count, loff_t *ppos, int write) | |
77b14db5 | 143 | { |
9043476f AV |
144 | struct inode *inode = filp->f_path.dentry->d_inode; |
145 | struct ctl_table_header *head = grab_header(inode); | |
146 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
2a2da53b DH |
147 | ssize_t error; |
148 | size_t res; | |
77b14db5 | 149 | |
9043476f AV |
150 | if (IS_ERR(head)) |
151 | return PTR_ERR(head); | |
77b14db5 EB |
152 | |
153 | /* | |
154 | * At this point we know that the sysctl was not unregistered | |
155 | * and won't be until we finish. | |
156 | */ | |
157 | error = -EPERM; | |
d7321cd6 | 158 | if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ)) |
77b14db5 EB |
159 | goto out; |
160 | ||
9043476f AV |
161 | /* if that can happen at all, it should be -EINVAL, not -EISDIR */ |
162 | error = -EINVAL; | |
163 | if (!table->proc_handler) | |
164 | goto out; | |
165 | ||
77b14db5 EB |
166 | /* careful: calling conventions are nasty here */ |
167 | res = count; | |
8d65af78 | 168 | error = table->proc_handler(table, write, buf, &res, ppos); |
77b14db5 EB |
169 | if (!error) |
170 | error = res; | |
171 | out: | |
172 | sysctl_head_finish(head); | |
173 | ||
174 | return error; | |
175 | } | |
176 | ||
7708bfb1 | 177 | static ssize_t proc_sys_read(struct file *filp, char __user *buf, |
77b14db5 EB |
178 | size_t count, loff_t *ppos) |
179 | { | |
7708bfb1 PE |
180 | return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0); |
181 | } | |
77b14db5 | 182 | |
7708bfb1 PE |
183 | static ssize_t proc_sys_write(struct file *filp, const char __user *buf, |
184 | size_t count, loff_t *ppos) | |
185 | { | |
186 | return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1); | |
77b14db5 EB |
187 | } |
188 | ||
f1ecf068 LDM |
189 | static int proc_sys_open(struct inode *inode, struct file *filp) |
190 | { | |
191 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
192 | ||
193 | if (table->poll) | |
194 | filp->private_data = proc_sys_poll_event(table->poll); | |
195 | ||
196 | return 0; | |
197 | } | |
198 | ||
199 | static unsigned int proc_sys_poll(struct file *filp, poll_table *wait) | |
200 | { | |
201 | struct inode *inode = filp->f_path.dentry->d_inode; | |
202 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
203 | unsigned long event = (unsigned long)filp->private_data; | |
204 | unsigned int ret = DEFAULT_POLLMASK; | |
205 | ||
206 | if (!table->proc_handler) | |
207 | goto out; | |
208 | ||
209 | if (!table->poll) | |
210 | goto out; | |
211 | ||
212 | poll_wait(filp, &table->poll->wait, wait); | |
213 | ||
214 | if (event != atomic_read(&table->poll->event)) { | |
215 | filp->private_data = proc_sys_poll_event(table->poll); | |
216 | ret = POLLIN | POLLRDNORM | POLLERR | POLLPRI; | |
217 | } | |
218 | ||
219 | out: | |
220 | return ret; | |
221 | } | |
77b14db5 EB |
222 | |
223 | static int proc_sys_fill_cache(struct file *filp, void *dirent, | |
9043476f AV |
224 | filldir_t filldir, |
225 | struct ctl_table_header *head, | |
226 | struct ctl_table *table) | |
77b14db5 | 227 | { |
77b14db5 EB |
228 | struct dentry *child, *dir = filp->f_path.dentry; |
229 | struct inode *inode; | |
230 | struct qstr qname; | |
231 | ino_t ino = 0; | |
232 | unsigned type = DT_UNKNOWN; | |
77b14db5 EB |
233 | |
234 | qname.name = table->procname; | |
235 | qname.len = strlen(table->procname); | |
236 | qname.hash = full_name_hash(qname.name, qname.len); | |
237 | ||
77b14db5 EB |
238 | child = d_lookup(dir, &qname); |
239 | if (!child) { | |
9043476f AV |
240 | child = d_alloc(dir, &qname); |
241 | if (child) { | |
242 | inode = proc_sys_make_inode(dir->d_sb, head, table); | |
243 | if (!inode) { | |
244 | dput(child); | |
245 | return -ENOMEM; | |
246 | } else { | |
fb045adb | 247 | d_set_d_op(child, &proc_sys_dentry_operations); |
9043476f | 248 | d_add(child, inode); |
77b14db5 | 249 | } |
9043476f AV |
250 | } else { |
251 | return -ENOMEM; | |
77b14db5 EB |
252 | } |
253 | } | |
77b14db5 | 254 | inode = child->d_inode; |
9043476f AV |
255 | ino = inode->i_ino; |
256 | type = inode->i_mode >> 12; | |
77b14db5 | 257 | dput(child); |
9043476f AV |
258 | return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type); |
259 | } | |
260 | ||
261 | static int scan(struct ctl_table_header *head, ctl_table *table, | |
262 | unsigned long *pos, struct file *file, | |
263 | void *dirent, filldir_t filldir) | |
264 | { | |
265 | ||
2315ffa0 | 266 | for (; table->procname; table++, (*pos)++) { |
9043476f AV |
267 | int res; |
268 | ||
269 | /* Can't do anything without a proc name */ | |
270 | if (!table->procname) | |
271 | continue; | |
272 | ||
273 | if (*pos < file->f_pos) | |
274 | continue; | |
275 | ||
276 | res = proc_sys_fill_cache(file, dirent, filldir, head, table); | |
277 | if (res) | |
278 | return res; | |
279 | ||
280 | file->f_pos = *pos + 1; | |
281 | } | |
282 | return 0; | |
77b14db5 EB |
283 | } |
284 | ||
285 | static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir) | |
286 | { | |
9043476f | 287 | struct dentry *dentry = filp->f_path.dentry; |
77b14db5 | 288 | struct inode *inode = dentry->d_inode; |
9043476f AV |
289 | struct ctl_table_header *head = grab_header(inode); |
290 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
291 | struct ctl_table_header *h = NULL; | |
77b14db5 | 292 | unsigned long pos; |
9043476f AV |
293 | int ret = -EINVAL; |
294 | ||
295 | if (IS_ERR(head)) | |
296 | return PTR_ERR(head); | |
77b14db5 | 297 | |
9043476f AV |
298 | if (table && !table->child) { |
299 | WARN_ON(1); | |
77b14db5 | 300 | goto out; |
9043476f AV |
301 | } |
302 | ||
303 | table = table ? table->child : head->ctl_table; | |
77b14db5 EB |
304 | |
305 | ret = 0; | |
306 | /* Avoid a switch here: arm builds fail with missing __cmpdi2 */ | |
307 | if (filp->f_pos == 0) { | |
308 | if (filldir(dirent, ".", 1, filp->f_pos, | |
309 | inode->i_ino, DT_DIR) < 0) | |
310 | goto out; | |
311 | filp->f_pos++; | |
312 | } | |
313 | if (filp->f_pos == 1) { | |
314 | if (filldir(dirent, "..", 2, filp->f_pos, | |
315 | parent_ino(dentry), DT_DIR) < 0) | |
316 | goto out; | |
317 | filp->f_pos++; | |
318 | } | |
319 | pos = 2; | |
320 | ||
9043476f AV |
321 | ret = scan(head, table, &pos, filp, dirent, filldir); |
322 | if (ret) | |
323 | goto out; | |
77b14db5 | 324 | |
9043476f AV |
325 | for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { |
326 | if (h->attached_to != table) | |
77b14db5 | 327 | continue; |
9043476f AV |
328 | ret = scan(h, h->attached_by, &pos, filp, dirent, filldir); |
329 | if (ret) { | |
330 | sysctl_head_finish(h); | |
331 | break; | |
77b14db5 EB |
332 | } |
333 | } | |
334 | ret = 1; | |
335 | out: | |
336 | sysctl_head_finish(head); | |
337 | return ret; | |
338 | } | |
339 | ||
10556cb2 | 340 | static int proc_sys_permission(struct inode *inode, int mask) |
77b14db5 EB |
341 | { |
342 | /* | |
343 | * sysctl entries that are not writeable, | |
344 | * are _NOT_ writeable, capabilities or not. | |
345 | */ | |
f696a365 MS |
346 | struct ctl_table_header *head; |
347 | struct ctl_table *table; | |
77b14db5 EB |
348 | int error; |
349 | ||
f696a365 MS |
350 | /* Executable files are not allowed under /proc/sys/ */ |
351 | if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) | |
352 | return -EACCES; | |
353 | ||
354 | head = grab_header(inode); | |
9043476f AV |
355 | if (IS_ERR(head)) |
356 | return PTR_ERR(head); | |
77b14db5 | 357 | |
f696a365 | 358 | table = PROC_I(inode)->sysctl_entry; |
9043476f AV |
359 | if (!table) /* global root - r-xr-xr-x */ |
360 | error = mask & MAY_WRITE ? -EACCES : 0; | |
361 | else /* Use the permissions on the sysctl table entry */ | |
1fc0f78c | 362 | error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK); |
77b14db5 | 363 | |
77b14db5 EB |
364 | sysctl_head_finish(head); |
365 | return error; | |
366 | } | |
367 | ||
368 | static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr) | |
369 | { | |
370 | struct inode *inode = dentry->d_inode; | |
371 | int error; | |
372 | ||
373 | if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) | |
374 | return -EPERM; | |
375 | ||
376 | error = inode_change_ok(inode, attr); | |
1025774c CH |
377 | if (error) |
378 | return error; | |
379 | ||
380 | if ((attr->ia_valid & ATTR_SIZE) && | |
381 | attr->ia_size != i_size_read(inode)) { | |
382 | error = vmtruncate(inode, attr->ia_size); | |
383 | if (error) | |
384 | return error; | |
385 | } | |
77b14db5 | 386 | |
1025774c CH |
387 | setattr_copy(inode, attr); |
388 | mark_inode_dirty(inode); | |
389 | return 0; | |
77b14db5 EB |
390 | } |
391 | ||
9043476f AV |
392 | static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) |
393 | { | |
394 | struct inode *inode = dentry->d_inode; | |
395 | struct ctl_table_header *head = grab_header(inode); | |
396 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
397 | ||
398 | if (IS_ERR(head)) | |
399 | return PTR_ERR(head); | |
400 | ||
401 | generic_fillattr(inode, stat); | |
402 | if (table) | |
403 | stat->mode = (stat->mode & S_IFMT) | table->mode; | |
404 | ||
405 | sysctl_head_finish(head); | |
406 | return 0; | |
407 | } | |
408 | ||
77b14db5 | 409 | static const struct file_operations proc_sys_file_operations = { |
f1ecf068 LDM |
410 | .open = proc_sys_open, |
411 | .poll = proc_sys_poll, | |
77b14db5 EB |
412 | .read = proc_sys_read, |
413 | .write = proc_sys_write, | |
6038f373 | 414 | .llseek = default_llseek, |
9043476f AV |
415 | }; |
416 | ||
417 | static const struct file_operations proc_sys_dir_file_operations = { | |
887df078 | 418 | .read = generic_read_dir, |
77b14db5 | 419 | .readdir = proc_sys_readdir, |
3222a3e5 | 420 | .llseek = generic_file_llseek, |
77b14db5 EB |
421 | }; |
422 | ||
03a44825 | 423 | static const struct inode_operations proc_sys_inode_operations = { |
9043476f AV |
424 | .permission = proc_sys_permission, |
425 | .setattr = proc_sys_setattr, | |
426 | .getattr = proc_sys_getattr, | |
427 | }; | |
428 | ||
429 | static const struct inode_operations proc_sys_dir_operations = { | |
77b14db5 EB |
430 | .lookup = proc_sys_lookup, |
431 | .permission = proc_sys_permission, | |
432 | .setattr = proc_sys_setattr, | |
9043476f | 433 | .getattr = proc_sys_getattr, |
77b14db5 EB |
434 | }; |
435 | ||
436 | static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd) | |
437 | { | |
34286d66 NP |
438 | if (nd->flags & LOOKUP_RCU) |
439 | return -ECHILD; | |
9043476f AV |
440 | return !PROC_I(dentry->d_inode)->sysctl->unregistering; |
441 | } | |
442 | ||
fe15ce44 | 443 | static int proc_sys_delete(const struct dentry *dentry) |
9043476f AV |
444 | { |
445 | return !!PROC_I(dentry->d_inode)->sysctl->unregistering; | |
446 | } | |
447 | ||
621e155a NP |
448 | static int proc_sys_compare(const struct dentry *parent, |
449 | const struct inode *pinode, | |
450 | const struct dentry *dentry, const struct inode *inode, | |
451 | unsigned int len, const char *str, const struct qstr *name) | |
9043476f | 452 | { |
dfef6dcd | 453 | struct ctl_table_header *head; |
31e6b01f NP |
454 | /* Although proc doesn't have negative dentries, rcu-walk means |
455 | * that inode here can be NULL */ | |
dfef6dcd | 456 | /* AV: can it, indeed? */ |
31e6b01f | 457 | if (!inode) |
dfef6dcd | 458 | return 1; |
621e155a | 459 | if (name->len != len) |
9043476f | 460 | return 1; |
621e155a | 461 | if (memcmp(name->name, str, len)) |
9043476f | 462 | return 1; |
dfef6dcd AV |
463 | head = rcu_dereference(PROC_I(inode)->sysctl); |
464 | return !head || !sysctl_is_seen(head); | |
77b14db5 EB |
465 | } |
466 | ||
d72f71eb | 467 | static const struct dentry_operations proc_sys_dentry_operations = { |
77b14db5 | 468 | .d_revalidate = proc_sys_revalidate, |
9043476f AV |
469 | .d_delete = proc_sys_delete, |
470 | .d_compare = proc_sys_compare, | |
77b14db5 EB |
471 | }; |
472 | ||
1e0edd3f | 473 | int __init proc_sys_init(void) |
77b14db5 | 474 | { |
e1675231 AD |
475 | struct proc_dir_entry *proc_sys_root; |
476 | ||
77b14db5 | 477 | proc_sys_root = proc_mkdir("sys", NULL); |
9043476f AV |
478 | proc_sys_root->proc_iops = &proc_sys_dir_operations; |
479 | proc_sys_root->proc_fops = &proc_sys_dir_file_operations; | |
77b14db5 EB |
480 | proc_sys_root->nlink = 0; |
481 | return 0; | |
482 | } |