1
2
3
4#include <linux/init.h>
5#include <linux/sysctl.h>
6#include <linux/proc_fs.h>
7#include <linux/security.h>
8#include "internal.h"
9
10static struct dentry_operations proc_sys_dentry_operations;
11static const struct file_operations proc_sys_file_operations;
12static const struct inode_operations proc_sys_inode_operations;
13static const struct file_operations proc_sys_dir_file_operations;
14static const struct inode_operations proc_sys_dir_operations;
15
16static struct inode *proc_sys_make_inode(struct super_block *sb,
17 struct ctl_table_header *head, struct ctl_table *table)
18{
19 struct inode *inode;
20 struct proc_inode *ei;
21
22 inode = new_inode(sb);
23 if (!inode)
24 goto out;
25
26 sysctl_head_get(head);
27 ei = PROC_I(inode);
28 ei->sysctl = head;
29 ei->sysctl_entry = table;
30
31 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
32 inode->i_flags |= S_PRIVATE;
33 inode->i_mode = table->mode;
34 inode->i_uid = inode->i_gid = 0;
35 if (!table->child) {
36 inode->i_mode |= S_IFREG;
37 inode->i_op = &proc_sys_inode_operations;
38 inode->i_fop = &proc_sys_file_operations;
39 } else {
40 inode->i_mode |= S_IFDIR;
41 inode->i_nlink = 0;
42 inode->i_op = &proc_sys_dir_operations;
43 inode->i_fop = &proc_sys_dir_file_operations;
44 }
45out:
46 return inode;
47}
48
49static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
50{
51 int len;
52 for ( ; p->ctl_name || p->procname; p++) {
53
54 if (!p->procname)
55 continue;
56
57 len = strlen(p->procname);
58 if (len != name->len)
59 continue;
60
61 if (memcmp(p->procname, name->name, len) != 0)
62 continue;
63
64
65 return p;
66 }
67 return NULL;
68}
69
70static struct ctl_table_header *grab_header(struct inode *inode)
71{
72 if (PROC_I(inode)->sysctl)
73 return sysctl_head_grab(PROC_I(inode)->sysctl);
74 else
75 return sysctl_head_next(NULL);
76}
77
78static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
79 struct nameidata *nd)
80{
81 struct ctl_table_header *head = grab_header(dir);
82 struct ctl_table *table = PROC_I(dir)->sysctl_entry;
83 struct ctl_table_header *h = NULL;
84 struct qstr *name = &dentry->d_name;
85 struct ctl_table *p;
86 struct inode *inode;
87 struct dentry *err = ERR_PTR(-ENOENT);
88
89 if (IS_ERR(head))
90 return ERR_CAST(head);
91
92 if (table && !table->child) {
93 WARN_ON(1);
94 goto out;
95 }
96
97 table = table ? table->child : head->ctl_table;
98
99 p = find_in_table(table, name);
100 if (!p) {
101 for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
102 if (h->attached_to != table)
103 continue;
104 p = find_in_table(h->attached_by, name);
105 if (p)
106 break;
107 }
108 }
109
110 if (!p)
111 goto out;
112
113 err = ERR_PTR(-ENOMEM);
114 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
115 if (h)
116 sysctl_head_finish(h);
117
118 if (!inode)
119 goto out;
120
121 err = NULL;
122 dentry->d_op = &proc_sys_dentry_operations;
123 d_add(dentry, inode);
124
125out:
126 sysctl_head_finish(head);
127 return err;
128}
129
130static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
131 size_t count, loff_t *ppos, int write)
132{
133 struct inode *inode = filp->f_path.dentry->d_inode;
134 struct ctl_table_header *head = grab_header(inode);
135 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
136 ssize_t error;
137 size_t res;
138
139 if (IS_ERR(head))
140 return PTR_ERR(head);
141
142
143
144
145
146 error = -EPERM;
147 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
148 goto out;
149
150
151 error = -EINVAL;
152 if (!table->proc_handler)
153 goto out;
154
155
156 res = count;
157 error = table->proc_handler(table, write, filp, buf, &res, ppos);
158 if (!error)
159 error = res;
160out:
161 sysctl_head_finish(head);
162
163 return error;
164}
165
166static ssize_t proc_sys_read(struct file *filp, char __user *buf,
167 size_t count, loff_t *ppos)
168{
169 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
170}
171
172static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
173 size_t count, loff_t *ppos)
174{
175 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
176}
177
178
179static int proc_sys_fill_cache(struct file *filp, void *dirent,
180 filldir_t filldir,
181 struct ctl_table_header *head,
182 struct ctl_table *table)
183{
184 struct dentry *child, *dir = filp->f_path.dentry;
185 struct inode *inode;
186 struct qstr qname;
187 ino_t ino = 0;
188 unsigned type = DT_UNKNOWN;
189
190 qname.name = table->procname;
191 qname.len = strlen(table->procname);
192 qname.hash = full_name_hash(qname.name, qname.len);
193
194 child = d_lookup(dir, &qname);
195 if (!child) {
196 child = d_alloc(dir, &qname);
197 if (child) {
198 inode = proc_sys_make_inode(dir->d_sb, head, table);
199 if (!inode) {
200 dput(child);
201 return -ENOMEM;
202 } else {
203 child->d_op = &proc_sys_dentry_operations;
204 d_add(child, inode);
205 }
206 } else {
207 return -ENOMEM;
208 }
209 }
210 inode = child->d_inode;
211 ino = inode->i_ino;
212 type = inode->i_mode >> 12;
213 dput(child);
214 return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
215}
216
217static int scan(struct ctl_table_header *head, ctl_table *table,
218 unsigned long *pos, struct file *file,
219 void *dirent, filldir_t filldir)
220{
221
222 for (; table->ctl_name || table->procname; table++, (*pos)++) {
223 int res;
224
225
226 if (!table->procname)
227 continue;
228
229 if (*pos < file->f_pos)
230 continue;
231
232 res = proc_sys_fill_cache(file, dirent, filldir, head, table);
233 if (res)
234 return res;
235
236 file->f_pos = *pos + 1;
237 }
238 return 0;
239}
240
241static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
242{
243 struct dentry *dentry = filp->f_path.dentry;
244 struct inode *inode = dentry->d_inode;
245 struct ctl_table_header *head = grab_header(inode);
246 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
247 struct ctl_table_header *h = NULL;
248 unsigned long pos;
249 int ret = -EINVAL;
250
251 if (IS_ERR(head))
252 return PTR_ERR(head);
253
254 if (table && !table->child) {
255 WARN_ON(1);
256 goto out;
257 }
258
259 table = table ? table->child : head->ctl_table;
260
261 ret = 0;
262
263 if (filp->f_pos == 0) {
264 if (filldir(dirent, ".", 1, filp->f_pos,
265 inode->i_ino, DT_DIR) < 0)
266 goto out;
267 filp->f_pos++;
268 }
269 if (filp->f_pos == 1) {
270 if (filldir(dirent, "..", 2, filp->f_pos,
271 parent_ino(dentry), DT_DIR) < 0)
272 goto out;
273 filp->f_pos++;
274 }
275 pos = 2;
276
277 ret = scan(head, table, &pos, filp, dirent, filldir);
278 if (ret)
279 goto out;
280
281 for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
282 if (h->attached_to != table)
283 continue;
284 ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
285 if (ret) {
286 sysctl_head_finish(h);
287 break;
288 }
289 }
290 ret = 1;
291out:
292 sysctl_head_finish(head);
293 return ret;
294}
295
296static int proc_sys_permission(struct inode *inode, int mask)
297{
298
299
300
301
302 struct ctl_table_header *head;
303 struct ctl_table *table;
304 int error;
305
306
307 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
308 return -EACCES;
309
310 head = grab_header(inode);
311 if (IS_ERR(head))
312 return PTR_ERR(head);
313
314 table = PROC_I(inode)->sysctl_entry;
315 if (!table)
316 error = mask & MAY_WRITE ? -EACCES : 0;
317 else
318 error = sysctl_perm(head->root, table, mask);
319
320 sysctl_head_finish(head);
321 return error;
322}
323
324static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
325{
326 struct inode *inode = dentry->d_inode;
327 int error;
328
329 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
330 return -EPERM;
331
332 error = inode_change_ok(inode, attr);
333 if (!error)
334 error = inode_setattr(inode, attr);
335
336 return error;
337}
338
339static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
340{
341 struct inode *inode = dentry->d_inode;
342 struct ctl_table_header *head = grab_header(inode);
343 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
344
345 if (IS_ERR(head))
346 return PTR_ERR(head);
347
348 generic_fillattr(inode, stat);
349 if (table)
350 stat->mode = (stat->mode & S_IFMT) | table->mode;
351
352 sysctl_head_finish(head);
353 return 0;
354}
355
356static const struct file_operations proc_sys_file_operations = {
357 .read = proc_sys_read,
358 .write = proc_sys_write,
359};
360
361static const struct file_operations proc_sys_dir_file_operations = {
362 .readdir = proc_sys_readdir,
363 .llseek = generic_file_llseek,
364};
365
366static const struct inode_operations proc_sys_inode_operations = {
367 .permission = proc_sys_permission,
368 .setattr = proc_sys_setattr,
369 .getattr = proc_sys_getattr,
370};
371
372static const struct inode_operations proc_sys_dir_operations = {
373 .lookup = proc_sys_lookup,
374 .permission = proc_sys_permission,
375 .setattr = proc_sys_setattr,
376 .getattr = proc_sys_getattr,
377};
378
379static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
380{
381 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
382}
383
384static int proc_sys_delete(struct dentry *dentry)
385{
386 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
387}
388
389static int proc_sys_compare(struct dentry *dir, struct qstr *qstr,
390 struct qstr *name)
391{
392 struct dentry *dentry = container_of(qstr, struct dentry, d_name);
393 if (qstr->len != name->len)
394 return 1;
395 if (memcmp(qstr->name, name->name, name->len))
396 return 1;
397 return !sysctl_is_seen(PROC_I(dentry->d_inode)->sysctl);
398}
399
400static struct dentry_operations proc_sys_dentry_operations = {
401 .d_revalidate = proc_sys_revalidate,
402 .d_delete = proc_sys_delete,
403 .d_compare = proc_sys_compare,
404};
405
406int __init proc_sys_init(void)
407{
408 struct proc_dir_entry *proc_sys_root;
409
410 proc_sys_root = proc_mkdir("sys", NULL);
411 proc_sys_root->proc_iops = &proc_sys_dir_operations;
412 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
413 proc_sys_root->nlink = 0;
414 return 0;
415}
416
