1
2
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
12static const struct dentry_operations proc_sys_dentry_operations;
13static const struct file_operations proc_sys_file_operations;
14static const struct inode_operations proc_sys_inode_operations;
15static const struct file_operations proc_sys_dir_file_operations;
16static const struct inode_operations proc_sys_dir_operations;
17
18void 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
27static 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 }
56out:
57 return inode;
58}
59
60static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
61{
62 int len;
63 for ( ; p->procname; p++) {
64
65 if (!p->procname)
66 continue;
67
68 len = strlen(p->procname);
69 if (len != name->len)
70 continue;
71
72 if (memcmp(p->procname, name->name, len) != 0)
73 continue;
74
75
76 return p;
77 }
78 return NULL;
79}
80
81static struct ctl_table_header *grab_header(struct inode *inode)
82{
83 if (PROC_I(inode)->sysctl)
84 return sysctl_head_grab(PROC_I(inode)->sysctl);
85 else
86 return sysctl_head_next(NULL);
87}
88
89static 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);
99
100 if (IS_ERR(head))
101 return ERR_CAST(head);
102
103 if (table && !table->child) {
104 WARN_ON(1);
105 goto out;
106 }
107
108 table = table ? table->child : head->ctl_table;
109
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 }
119 }
120
121 if (!p)
122 goto out;
123
124 err = ERR_PTR(-ENOMEM);
125 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
126 if (h)
127 sysctl_head_finish(h);
128
129 if (!inode)
130 goto out;
131
132 err = NULL;
133 d_set_d_op(dentry, &proc_sys_dentry_operations);
134 d_add(dentry, inode);
135
136out:
137 sysctl_head_finish(head);
138 return err;
139}
140
141static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
142 size_t count, loff_t *ppos, int write)
143{
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;
147 ssize_t error;
148 size_t res;
149
150 if (IS_ERR(head))
151 return PTR_ERR(head);
152
153
154
155
156
157 error = -EPERM;
158 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
159 goto out;
160
161
162 error = -EINVAL;
163 if (!table->proc_handler)
164 goto out;
165
166
167 res = count;
168 error = table->proc_handler(table, write, buf, &res, ppos);
169 if (!error)
170 error = res;
171out:
172 sysctl_head_finish(head);
173
174 return error;
175}
176
177static ssize_t proc_sys_read(struct file *filp, char __user *buf,
178 size_t count, loff_t *ppos)
179{
180 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
181}
182
183static 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);
187}
188
189static 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
199static 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
219out:
220 return ret;
221}
222
223static int proc_sys_fill_cache(struct file *filp, void *dirent,
224 filldir_t filldir,
225 struct ctl_table_header *head,
226 struct ctl_table *table)
227{
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;
233
234 qname.name = table->procname;
235 qname.len = strlen(table->procname);
236 qname.hash = full_name_hash(qname.name, qname.len);
237
238 child = d_lookup(dir, &qname);
239 if (!child) {
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 {
247 d_set_d_op(child, &proc_sys_dentry_operations);
248 d_add(child, inode);
249 }
250 } else {
251 return -ENOMEM;
252 }
253 }
254 inode = child->d_inode;
255 ino = inode->i_ino;
256 type = inode->i_mode >> 12;
257 dput(child);
258 return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
259}
260
261static 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
266 for (; table->procname; table++, (*pos)++) {
267 int res;
268
269
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;
283}
284
285static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
286{
287 struct dentry *dentry = filp->f_path.dentry;
288 struct inode *inode = dentry->d_inode;
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;
292 unsigned long pos;
293 int ret = -EINVAL;
294
295 if (IS_ERR(head))
296 return PTR_ERR(head);
297
298 if (table && !table->child) {
299 WARN_ON(1);
300 goto out;
301 }
302
303 table = table ? table->child : head->ctl_table;
304
305 ret = 0;
306
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
321 ret = scan(head, table, &pos, filp, dirent, filldir);
322 if (ret)
323 goto out;
324
325 for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
326 if (h->attached_to != table)
327 continue;
328 ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
329 if (ret) {
330 sysctl_head_finish(h);
331 break;
332 }
333 }
334 ret = 1;
335out:
336 sysctl_head_finish(head);
337 return ret;
338}
339
340static int proc_sys_permission(struct inode *inode, int mask)
341{
342
343
344
345
346 struct ctl_table_header *head;
347 struct ctl_table *table;
348 int error;
349
350
351 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
352 return -EACCES;
353
354 head = grab_header(inode);
355 if (IS_ERR(head))
356 return PTR_ERR(head);
357
358 table = PROC_I(inode)->sysctl_entry;
359 if (!table)
360 error = mask & MAY_WRITE ? -EACCES : 0;
361 else
362 error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK);
363
364 sysctl_head_finish(head);
365 return error;
366}
367
368static 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);
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 }
386
387 setattr_copy(inode, attr);
388 mark_inode_dirty(inode);
389 return 0;
390}
391
392static 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
409static const struct file_operations proc_sys_file_operations = {
410 .open = proc_sys_open,
411 .poll = proc_sys_poll,
412 .read = proc_sys_read,
413 .write = proc_sys_write,
414 .llseek = default_llseek,
415};
416
417static const struct file_operations proc_sys_dir_file_operations = {
418 .read = generic_read_dir,
419 .readdir = proc_sys_readdir,
420 .llseek = generic_file_llseek,
421};
422
423static const struct inode_operations proc_sys_inode_operations = {
424 .permission = proc_sys_permission,
425 .setattr = proc_sys_setattr,
426 .getattr = proc_sys_getattr,
427};
428
429static const struct inode_operations proc_sys_dir_operations = {
430 .lookup = proc_sys_lookup,
431 .permission = proc_sys_permission,
432 .setattr = proc_sys_setattr,
433 .getattr = proc_sys_getattr,
434};
435
436static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
437{
438 if (nd->flags & LOOKUP_RCU)
439 return -ECHILD;
440 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
441}
442
443static int proc_sys_delete(const struct dentry *dentry)
444{
445 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
446}
447
448static 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)
452{
453 struct ctl_table_header *head;
454
455
456
457 if (!inode)
458 return 1;
459 if (name->len != len)
460 return 1;
461 if (memcmp(name->name, str, len))
462 return 1;
463 head = rcu_dereference(PROC_I(inode)->sysctl);
464 return !head || !sysctl_is_seen(head);
465}
466
467static const struct dentry_operations proc_sys_dentry_operations = {
468 .d_revalidate = proc_sys_revalidate,
469 .d_delete = proc_sys_delete,
470 .d_compare = proc_sys_compare,
471};
472
473int __init proc_sys_init(void)
474{
475 struct proc_dir_entry *proc_sys_root;
476
477 proc_sys_root = proc_mkdir("sys", NULL);
478 proc_sys_root->proc_iops = &proc_sys_dir_operations;
479 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
480 proc_sys_root->nlink = 0;
481 return 0;
482}
483
