blob: d167de365a8de0f52ae880e0b88c75750109d981 [file] [log] [blame]
Eric W. Biederman77b14db2007-02-14 00:34:12 -08001/*
2 * /proc/sys support
3 */
Alexey Dobriyan1e0edd32008-10-17 05:07:44 +04004#include <linux/init.h>
Eric W. Biederman77b14db2007-02-14 00:34:12 -08005#include <linux/sysctl.h>
6#include <linux/proc_fs.h>
7#include <linux/security.h>
Nick Piggin34286d62011-01-07 17:49:57 +11008#include <linux/namei.h>
Eric W. Biederman77b14db2007-02-14 00:34:12 -08009#include "internal.h"
10
Al Virod72f71e2009-02-20 05:58:47 +000011static const struct dentry_operations proc_sys_dentry_operations;
Eric W. Biederman77b14db2007-02-14 00:34:12 -080012static const struct file_operations proc_sys_file_operations;
Jan Engelhardt03a44822008-02-08 04:21:19 -080013static const struct inode_operations proc_sys_inode_operations;
Al Viro9043476f2008-07-15 08:54:06 -040014static const struct file_operations proc_sys_dir_file_operations;
15static const struct inode_operations proc_sys_dir_operations;
Eric W. Biederman77b14db2007-02-14 00:34:12 -080016
Al Viro9043476f2008-07-15 08:54:06 -040017static struct inode *proc_sys_make_inode(struct super_block *sb,
18 struct ctl_table_header *head, struct ctl_table *table)
Eric W. Biederman77b14db2007-02-14 00:34:12 -080019{
20 struct inode *inode;
Al Viro9043476f2008-07-15 08:54:06 -040021 struct proc_inode *ei;
Eric W. Biederman77b14db2007-02-14 00:34:12 -080022
Al Viro9043476f2008-07-15 08:54:06 -040023 inode = new_inode(sb);
Eric W. Biederman77b14db2007-02-14 00:34:12 -080024 if (!inode)
25 goto out;
26
Christoph Hellwig85fe4022010-10-23 11:19:54 -040027 inode->i_ino = get_next_ino();
28
Al Viro9043476f2008-07-15 08:54:06 -040029 sysctl_head_get(head);
Eric W. Biederman77b14db2007-02-14 00:34:12 -080030 ei = PROC_I(inode);
Al Viro9043476f2008-07-15 08:54:06 -040031 ei->sysctl = head;
32 ei->sysctl_entry = table;
33
Eric W. Biederman77b14db2007-02-14 00:34:12 -080034 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
Al Viro9043476f2008-07-15 08:54:06 -040035 inode->i_mode = table->mode;
36 if (!table->child) {
37 inode->i_mode |= S_IFREG;
38 inode->i_op = &proc_sys_inode_operations;
39 inode->i_fop = &proc_sys_file_operations;
40 } else {
41 inode->i_mode |= S_IFDIR;
42 inode->i_nlink = 0;
43 inode->i_op = &proc_sys_dir_operations;
44 inode->i_fop = &proc_sys_dir_file_operations;
45 }
Eric W. Biederman77b14db2007-02-14 00:34:12 -080046out:
47 return inode;
48}
49
Al Viro9043476f2008-07-15 08:54:06 -040050static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
Eric W. Biederman77b14db2007-02-14 00:34:12 -080051{
52 int len;
Eric W. Biederman2315ffa2009-04-03 03:18:02 -070053 for ( ; p->procname; p++) {
Eric W. Biederman77b14db2007-02-14 00:34:12 -080054
Al Viro9043476f2008-07-15 08:54:06 -040055 if (!p->procname)
Eric W. Biederman77b14db2007-02-14 00:34:12 -080056 continue;
57
Al Viro9043476f2008-07-15 08:54:06 -040058 len = strlen(p->procname);
Eric W. Biederman77b14db2007-02-14 00:34:12 -080059 if (len != name->len)
60 continue;
61
Al Viro9043476f2008-07-15 08:54:06 -040062 if (memcmp(p->procname, name->name, len) != 0)
Eric W. Biederman77b14db2007-02-14 00:34:12 -080063 continue;
64
65 /* I have a match */
Al Viro9043476f2008-07-15 08:54:06 -040066 return p;
Eric W. Biederman77b14db2007-02-14 00:34:12 -080067 }
68 return NULL;
69}
70
Adrian Bunk81324362008-10-03 00:33:54 +040071static struct ctl_table_header *grab_header(struct inode *inode)
Eric W. Biederman77b14db2007-02-14 00:34:12 -080072{
Al Viro9043476f2008-07-15 08:54:06 -040073 if (PROC_I(inode)->sysctl)
74 return sysctl_head_grab(PROC_I(inode)->sysctl);
75 else
76 return sysctl_head_next(NULL);
Eric W. Biederman77b14db2007-02-14 00:34:12 -080077}
78
79static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
80 struct nameidata *nd)
81{
Al Viro9043476f2008-07-15 08:54:06 -040082 struct ctl_table_header *head = grab_header(dir);
83 struct ctl_table *table = PROC_I(dir)->sysctl_entry;
84 struct ctl_table_header *h = NULL;
85 struct qstr *name = &dentry->d_name;
86 struct ctl_table *p;
Eric W. Biederman77b14db2007-02-14 00:34:12 -080087 struct inode *inode;
Al Viro9043476f2008-07-15 08:54:06 -040088 struct dentry *err = ERR_PTR(-ENOENT);
Eric W. Biederman77b14db2007-02-14 00:34:12 -080089
Al Viro9043476f2008-07-15 08:54:06 -040090 if (IS_ERR(head))
91 return ERR_CAST(head);
92
93 if (table && !table->child) {
94 WARN_ON(1);
95 goto out;
96 }
97
98 table = table ? table->child : head->ctl_table;
99
100 p = find_in_table(table, name);
101 if (!p) {
102 for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
103 if (h->attached_to != table)
104 continue;
105 p = find_in_table(h->attached_by, name);
106 if (p)
107 break;
108 }
109 }
110
111 if (!p)
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800112 goto out;
113
114 err = ERR_PTR(-ENOMEM);
Al Viro9043476f2008-07-15 08:54:06 -0400115 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
116 if (h)
117 sysctl_head_finish(h);
118
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800119 if (!inode)
120 goto out;
121
122 err = NULL;
Nick Pigginfb045ad2011-01-07 17:49:55 +1100123 d_set_d_op(dentry, &proc_sys_dentry_operations);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800124 d_add(dentry, inode);
125
126out:
127 sysctl_head_finish(head);
128 return err;
129}
130
Pavel Emelyanov7708bfb2008-04-29 01:02:40 -0700131static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
132 size_t count, loff_t *ppos, int write)
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800133{
Al Viro9043476f2008-07-15 08:54:06 -0400134 struct inode *inode = filp->f_path.dentry->d_inode;
135 struct ctl_table_header *head = grab_header(inode);
136 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
David Howells2a2da532007-10-25 15:27:40 +0100137 ssize_t error;
138 size_t res;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800139
Al Viro9043476f2008-07-15 08:54:06 -0400140 if (IS_ERR(head))
141 return PTR_ERR(head);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800142
143 /*
144 * At this point we know that the sysctl was not unregistered
145 * and won't be until we finish.
146 */
147 error = -EPERM;
Pavel Emelyanovd7321cd2008-04-29 01:02:44 -0700148 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800149 goto out;
150
Al Viro9043476f2008-07-15 08:54:06 -0400151 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
152 error = -EINVAL;
153 if (!table->proc_handler)
154 goto out;
155
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800156 /* careful: calling conventions are nasty here */
157 res = count;
Alexey Dobriyan8d65af72009-09-23 15:57:19 -0700158 error = table->proc_handler(table, write, buf, &res, ppos);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800159 if (!error)
160 error = res;
161out:
162 sysctl_head_finish(head);
163
164 return error;
165}
166
Pavel Emelyanov7708bfb2008-04-29 01:02:40 -0700167static ssize_t proc_sys_read(struct file *filp, char __user *buf,
168 size_t count, loff_t *ppos)
169{
170 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
171}
172
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800173static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
174 size_t count, loff_t *ppos)
175{
Pavel Emelyanov7708bfb2008-04-29 01:02:40 -0700176 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800177}
178
179
180static int proc_sys_fill_cache(struct file *filp, void *dirent,
Al Viro9043476f2008-07-15 08:54:06 -0400181 filldir_t filldir,
182 struct ctl_table_header *head,
183 struct ctl_table *table)
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800184{
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800185 struct dentry *child, *dir = filp->f_path.dentry;
186 struct inode *inode;
187 struct qstr qname;
188 ino_t ino = 0;
189 unsigned type = DT_UNKNOWN;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800190
191 qname.name = table->procname;
192 qname.len = strlen(table->procname);
193 qname.hash = full_name_hash(qname.name, qname.len);
194
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800195 child = d_lookup(dir, &qname);
196 if (!child) {
Al Viro9043476f2008-07-15 08:54:06 -0400197 child = d_alloc(dir, &qname);
198 if (child) {
199 inode = proc_sys_make_inode(dir->d_sb, head, table);
200 if (!inode) {
201 dput(child);
202 return -ENOMEM;
203 } else {
Nick Pigginfb045ad2011-01-07 17:49:55 +1100204 d_set_d_op(child, &proc_sys_dentry_operations);
Al Viro9043476f2008-07-15 08:54:06 -0400205 d_add(child, inode);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800206 }
Al Viro9043476f2008-07-15 08:54:06 -0400207 } else {
208 return -ENOMEM;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800209 }
210 }
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800211 inode = child->d_inode;
Al Viro9043476f2008-07-15 08:54:06 -0400212 ino = inode->i_ino;
213 type = inode->i_mode >> 12;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800214 dput(child);
Al Viro9043476f2008-07-15 08:54:06 -0400215 return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
216}
217
218static int scan(struct ctl_table_header *head, ctl_table *table,
219 unsigned long *pos, struct file *file,
220 void *dirent, filldir_t filldir)
221{
222
Eric W. Biederman2315ffa2009-04-03 03:18:02 -0700223 for (; table->procname; table++, (*pos)++) {
Al Viro9043476f2008-07-15 08:54:06 -0400224 int res;
225
226 /* Can't do anything without a proc name */
227 if (!table->procname)
228 continue;
229
230 if (*pos < file->f_pos)
231 continue;
232
233 res = proc_sys_fill_cache(file, dirent, filldir, head, table);
234 if (res)
235 return res;
236
237 file->f_pos = *pos + 1;
238 }
239 return 0;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800240}
241
242static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
243{
Al Viro9043476f2008-07-15 08:54:06 -0400244 struct dentry *dentry = filp->f_path.dentry;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800245 struct inode *inode = dentry->d_inode;
Al Viro9043476f2008-07-15 08:54:06 -0400246 struct ctl_table_header *head = grab_header(inode);
247 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
248 struct ctl_table_header *h = NULL;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800249 unsigned long pos;
Al Viro9043476f2008-07-15 08:54:06 -0400250 int ret = -EINVAL;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800251
Al Viro9043476f2008-07-15 08:54:06 -0400252 if (IS_ERR(head))
253 return PTR_ERR(head);
254
255 if (table && !table->child) {
256 WARN_ON(1);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800257 goto out;
Al Viro9043476f2008-07-15 08:54:06 -0400258 }
259
260 table = table ? table->child : head->ctl_table;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800261
262 ret = 0;
263 /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
264 if (filp->f_pos == 0) {
265 if (filldir(dirent, ".", 1, filp->f_pos,
266 inode->i_ino, DT_DIR) < 0)
267 goto out;
268 filp->f_pos++;
269 }
270 if (filp->f_pos == 1) {
271 if (filldir(dirent, "..", 2, filp->f_pos,
272 parent_ino(dentry), DT_DIR) < 0)
273 goto out;
274 filp->f_pos++;
275 }
276 pos = 2;
277
Al Viro9043476f2008-07-15 08:54:06 -0400278 ret = scan(head, table, &pos, filp, dirent, filldir);
279 if (ret)
280 goto out;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800281
Al Viro9043476f2008-07-15 08:54:06 -0400282 for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
283 if (h->attached_to != table)
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800284 continue;
Al Viro9043476f2008-07-15 08:54:06 -0400285 ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
286 if (ret) {
287 sysctl_head_finish(h);
288 break;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800289 }
290 }
291 ret = 1;
292out:
293 sysctl_head_finish(head);
294 return ret;
295}
296
Nick Pigginb74c79e2011-01-07 17:49:58 +1100297static int proc_sys_permission(struct inode *inode, int mask,unsigned int flags)
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800298{
299 /*
300 * sysctl entries that are not writeable,
301 * are _NOT_ writeable, capabilities or not.
302 */
Miklos Szeredif696a362008-07-31 13:41:58 +0200303 struct ctl_table_header *head;
304 struct ctl_table *table;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800305 int error;
306
Miklos Szeredif696a362008-07-31 13:41:58 +0200307 /* Executable files are not allowed under /proc/sys/ */
308 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
309 return -EACCES;
310
311 head = grab_header(inode);
Al Viro9043476f2008-07-15 08:54:06 -0400312 if (IS_ERR(head))
313 return PTR_ERR(head);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800314
Miklos Szeredif696a362008-07-31 13:41:58 +0200315 table = PROC_I(inode)->sysctl_entry;
Al Viro9043476f2008-07-15 08:54:06 -0400316 if (!table) /* global root - r-xr-xr-x */
317 error = mask & MAY_WRITE ? -EACCES : 0;
318 else /* Use the permissions on the sysctl table entry */
319 error = sysctl_perm(head->root, table, mask);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800320
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800321 sysctl_head_finish(head);
322 return error;
323}
324
325static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
326{
327 struct inode *inode = dentry->d_inode;
328 int error;
329
330 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
331 return -EPERM;
332
333 error = inode_change_ok(inode, attr);
Christoph Hellwig10257742010-06-04 11:30:02 +0200334 if (error)
335 return error;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800336
Christoph Hellwig10257742010-06-04 11:30:02 +0200337 if ((attr->ia_valid & ATTR_SIZE) &&
338 attr->ia_size != i_size_read(inode)) {
339 error = vmtruncate(inode, attr->ia_size);
340 if (error)
341 return error;
342 }
343
344 setattr_copy(inode, attr);
345 mark_inode_dirty(inode);
346 return 0;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800347}
348
Al Viro9043476f2008-07-15 08:54:06 -0400349static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
350{
351 struct inode *inode = dentry->d_inode;
352 struct ctl_table_header *head = grab_header(inode);
353 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
354
355 if (IS_ERR(head))
356 return PTR_ERR(head);
357
358 generic_fillattr(inode, stat);
359 if (table)
360 stat->mode = (stat->mode & S_IFMT) | table->mode;
361
362 sysctl_head_finish(head);
363 return 0;
364}
365
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800366static const struct file_operations proc_sys_file_operations = {
367 .read = proc_sys_read,
368 .write = proc_sys_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200369 .llseek = default_llseek,
Al Viro9043476f2008-07-15 08:54:06 -0400370};
371
372static const struct file_operations proc_sys_dir_file_operations = {
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800373 .readdir = proc_sys_readdir,
Christoph Hellwig3222a3e2008-09-03 21:53:01 +0200374 .llseek = generic_file_llseek,
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800375};
376
Jan Engelhardt03a44822008-02-08 04:21:19 -0800377static const struct inode_operations proc_sys_inode_operations = {
Al Viro9043476f2008-07-15 08:54:06 -0400378 .permission = proc_sys_permission,
379 .setattr = proc_sys_setattr,
380 .getattr = proc_sys_getattr,
381};
382
383static const struct inode_operations proc_sys_dir_operations = {
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800384 .lookup = proc_sys_lookup,
385 .permission = proc_sys_permission,
386 .setattr = proc_sys_setattr,
Al Viro9043476f2008-07-15 08:54:06 -0400387 .getattr = proc_sys_getattr,
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800388};
389
390static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
391{
Nick Piggin34286d62011-01-07 17:49:57 +1100392 if (nd->flags & LOOKUP_RCU)
393 return -ECHILD;
Al Viro9043476f2008-07-15 08:54:06 -0400394 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
395}
396
Nick Pigginfe15ce42011-01-07 17:49:23 +1100397static int proc_sys_delete(const struct dentry *dentry)
Al Viro9043476f2008-07-15 08:54:06 -0400398{
399 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
400}
401
Nick Piggin621e1552011-01-07 17:49:27 +1100402static int proc_sys_compare(const struct dentry *parent,
403 const struct inode *pinode,
404 const struct dentry *dentry, const struct inode *inode,
405 unsigned int len, const char *str, const struct qstr *name)
Al Viro9043476f2008-07-15 08:54:06 -0400406{
Al Virodfef6dcd32011-03-08 01:25:28 -0500407 struct ctl_table_header *head;
Nick Piggin31e6b012011-01-07 17:49:52 +1100408 /* Although proc doesn't have negative dentries, rcu-walk means
409 * that inode here can be NULL */
Al Virodfef6dcd32011-03-08 01:25:28 -0500410 /* AV: can it, indeed? */
Nick Piggin31e6b012011-01-07 17:49:52 +1100411 if (!inode)
Al Virodfef6dcd32011-03-08 01:25:28 -0500412 return 1;
Nick Piggin621e1552011-01-07 17:49:27 +1100413 if (name->len != len)
Al Viro9043476f2008-07-15 08:54:06 -0400414 return 1;
Nick Piggin621e1552011-01-07 17:49:27 +1100415 if (memcmp(name->name, str, len))
Al Viro9043476f2008-07-15 08:54:06 -0400416 return 1;
Al Virodfef6dcd32011-03-08 01:25:28 -0500417 head = rcu_dereference(PROC_I(inode)->sysctl);
418 return !head || !sysctl_is_seen(head);
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800419}
420
Al Virod72f71e2009-02-20 05:58:47 +0000421static const struct dentry_operations proc_sys_dentry_operations = {
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800422 .d_revalidate = proc_sys_revalidate,
Al Viro9043476f2008-07-15 08:54:06 -0400423 .d_delete = proc_sys_delete,
424 .d_compare = proc_sys_compare,
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800425};
426
Alexey Dobriyan1e0edd32008-10-17 05:07:44 +0400427int __init proc_sys_init(void)
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800428{
Alexey Dobriyane1675232008-10-03 00:23:32 +0400429 struct proc_dir_entry *proc_sys_root;
430
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800431 proc_sys_root = proc_mkdir("sys", NULL);
Al Viro9043476f2008-07-15 08:54:06 -0400432 proc_sys_root->proc_iops = &proc_sys_dir_operations;
433 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
Eric W. Biederman77b14db2007-02-14 00:34:12 -0800434 proc_sys_root->nlink = 0;
435 return 0;
436}