Commit | Line | Data |
---|---|---|
77b14db5 EB |
1 | /* |
2 | * /proc/sys support | |
3 | */ | |
1e0edd3f | 4 | #include <linux/init.h> |
77b14db5 EB |
5 | #include <linux/sysctl.h> |
6 | #include <linux/proc_fs.h> | |
7 | #include <linux/security.h> | |
8 | #include "internal.h" | |
9 | ||
d72f71eb | 10 | static const struct dentry_operations proc_sys_dentry_operations; |
77b14db5 | 11 | static const struct file_operations proc_sys_file_operations; |
03a44825 | 12 | static const struct inode_operations proc_sys_inode_operations; |
9043476f AV |
13 | static const struct file_operations proc_sys_dir_file_operations; |
14 | static const struct inode_operations proc_sys_dir_operations; | |
77b14db5 | 15 | |
9043476f AV |
16 | static struct inode *proc_sys_make_inode(struct super_block *sb, |
17 | struct ctl_table_header *head, struct ctl_table *table) | |
77b14db5 EB |
18 | { |
19 | struct inode *inode; | |
9043476f | 20 | struct proc_inode *ei; |
77b14db5 | 21 | |
9043476f | 22 | inode = new_inode(sb); |
77b14db5 EB |
23 | if (!inode) |
24 | goto out; | |
25 | ||
9043476f | 26 | sysctl_head_get(head); |
77b14db5 | 27 | ei = PROC_I(inode); |
9043476f AV |
28 | ei->sysctl = head; |
29 | ei->sysctl_entry = table; | |
30 | ||
77b14db5 | 31 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
86a71dbd | 32 | inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */ |
9043476f AV |
33 | inode->i_mode = table->mode; |
34 | if (!table->child) { | |
35 | inode->i_mode |= S_IFREG; | |
36 | inode->i_op = &proc_sys_inode_operations; | |
37 | inode->i_fop = &proc_sys_file_operations; | |
38 | } else { | |
39 | inode->i_mode |= S_IFDIR; | |
40 | inode->i_nlink = 0; | |
41 | inode->i_op = &proc_sys_dir_operations; | |
42 | inode->i_fop = &proc_sys_dir_file_operations; | |
43 | } | |
77b14db5 EB |
44 | out: |
45 | return inode; | |
46 | } | |
47 | ||
9043476f | 48 | static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name) |
77b14db5 EB |
49 | { |
50 | int len; | |
9043476f | 51 | for ( ; p->ctl_name || p->procname; p++) { |
77b14db5 | 52 | |
9043476f | 53 | if (!p->procname) |
77b14db5 EB |
54 | continue; |
55 | ||
9043476f | 56 | len = strlen(p->procname); |
77b14db5 EB |
57 | if (len != name->len) |
58 | continue; | |
59 | ||
9043476f | 60 | if (memcmp(p->procname, name->name, len) != 0) |
77b14db5 EB |
61 | continue; |
62 | ||
63 | /* I have a match */ | |
9043476f | 64 | return p; |
77b14db5 EB |
65 | } |
66 | return NULL; | |
67 | } | |
68 | ||
81324364 | 69 | static struct ctl_table_header *grab_header(struct inode *inode) |
77b14db5 | 70 | { |
9043476f AV |
71 | if (PROC_I(inode)->sysctl) |
72 | return sysctl_head_grab(PROC_I(inode)->sysctl); | |
73 | else | |
74 | return sysctl_head_next(NULL); | |
75 | } | |
77b14db5 | 76 | |
9043476f AV |
77 | static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, |
78 | struct nameidata *nd) | |
79 | { | |
80 | struct ctl_table_header *head = grab_header(dir); | |
81 | struct ctl_table *table = PROC_I(dir)->sysctl_entry; | |
82 | struct ctl_table_header *h = NULL; | |
83 | struct qstr *name = &dentry->d_name; | |
84 | struct ctl_table *p; | |
85 | struct inode *inode; | |
86 | struct dentry *err = ERR_PTR(-ENOENT); | |
77b14db5 | 87 | |
9043476f AV |
88 | if (IS_ERR(head)) |
89 | return ERR_CAST(head); | |
77b14db5 | 90 | |
9043476f AV |
91 | if (table && !table->child) { |
92 | WARN_ON(1); | |
93 | goto out; | |
77b14db5 | 94 | } |
77b14db5 | 95 | |
9043476f | 96 | table = table ? table->child : head->ctl_table; |
77b14db5 | 97 | |
9043476f AV |
98 | p = find_in_table(table, name); |
99 | if (!p) { | |
100 | for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { | |
101 | if (h->attached_to != table) | |
102 | continue; | |
103 | p = find_in_table(h->attached_by, name); | |
104 | if (p) | |
105 | break; | |
106 | } | |
77b14db5 | 107 | } |
77b14db5 | 108 | |
9043476f | 109 | if (!p) |
77b14db5 EB |
110 | goto out; |
111 | ||
112 | err = ERR_PTR(-ENOMEM); | |
9043476f AV |
113 | inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); |
114 | if (h) | |
115 | sysctl_head_finish(h); | |
116 | ||
77b14db5 EB |
117 | if (!inode) |
118 | goto out; | |
119 | ||
120 | err = NULL; | |
121 | dentry->d_op = &proc_sys_dentry_operations; | |
122 | d_add(dentry, inode); | |
123 | ||
124 | out: | |
125 | sysctl_head_finish(head); | |
126 | return err; | |
127 | } | |
128 | ||
7708bfb1 PE |
129 | static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf, |
130 | size_t count, loff_t *ppos, int write) | |
77b14db5 | 131 | { |
9043476f AV |
132 | struct inode *inode = filp->f_path.dentry->d_inode; |
133 | struct ctl_table_header *head = grab_header(inode); | |
134 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
2a2da53b DH |
135 | ssize_t error; |
136 | size_t res; | |
77b14db5 | 137 | |
9043476f AV |
138 | if (IS_ERR(head)) |
139 | return PTR_ERR(head); | |
77b14db5 EB |
140 | |
141 | /* | |
142 | * At this point we know that the sysctl was not unregistered | |
143 | * and won't be until we finish. | |
144 | */ | |
145 | error = -EPERM; | |
d7321cd6 | 146 | if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ)) |
77b14db5 EB |
147 | goto out; |
148 | ||
9043476f AV |
149 | /* if that can happen at all, it should be -EINVAL, not -EISDIR */ |
150 | error = -EINVAL; | |
151 | if (!table->proc_handler) | |
152 | goto out; | |
153 | ||
77b14db5 EB |
154 | /* careful: calling conventions are nasty here */ |
155 | res = count; | |
7708bfb1 | 156 | error = table->proc_handler(table, write, filp, buf, &res, ppos); |
77b14db5 EB |
157 | if (!error) |
158 | error = res; | |
159 | out: | |
160 | sysctl_head_finish(head); | |
161 | ||
162 | return error; | |
163 | } | |
164 | ||
7708bfb1 | 165 | static ssize_t proc_sys_read(struct file *filp, char __user *buf, |
77b14db5 EB |
166 | size_t count, loff_t *ppos) |
167 | { | |
7708bfb1 PE |
168 | return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0); |
169 | } | |
77b14db5 | 170 | |
7708bfb1 PE |
171 | static ssize_t proc_sys_write(struct file *filp, const char __user *buf, |
172 | size_t count, loff_t *ppos) | |
173 | { | |
174 | return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1); | |
77b14db5 EB |
175 | } |
176 | ||
177 | ||
178 | static int proc_sys_fill_cache(struct file *filp, void *dirent, | |
9043476f AV |
179 | filldir_t filldir, |
180 | struct ctl_table_header *head, | |
181 | struct ctl_table *table) | |
77b14db5 | 182 | { |
77b14db5 EB |
183 | struct dentry *child, *dir = filp->f_path.dentry; |
184 | struct inode *inode; | |
185 | struct qstr qname; | |
186 | ino_t ino = 0; | |
187 | unsigned type = DT_UNKNOWN; | |
77b14db5 EB |
188 | |
189 | qname.name = table->procname; | |
190 | qname.len = strlen(table->procname); | |
191 | qname.hash = full_name_hash(qname.name, qname.len); | |
192 | ||
77b14db5 EB |
193 | child = d_lookup(dir, &qname); |
194 | if (!child) { | |
9043476f AV |
195 | child = d_alloc(dir, &qname); |
196 | if (child) { | |
197 | inode = proc_sys_make_inode(dir->d_sb, head, table); | |
198 | if (!inode) { | |
199 | dput(child); | |
200 | return -ENOMEM; | |
201 | } else { | |
202 | child->d_op = &proc_sys_dentry_operations; | |
203 | d_add(child, inode); | |
77b14db5 | 204 | } |
9043476f AV |
205 | } else { |
206 | return -ENOMEM; | |
77b14db5 EB |
207 | } |
208 | } | |
77b14db5 | 209 | inode = child->d_inode; |
9043476f AV |
210 | ino = inode->i_ino; |
211 | type = inode->i_mode >> 12; | |
77b14db5 | 212 | dput(child); |
9043476f AV |
213 | return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type); |
214 | } | |
215 | ||
216 | static int scan(struct ctl_table_header *head, ctl_table *table, | |
217 | unsigned long *pos, struct file *file, | |
218 | void *dirent, filldir_t filldir) | |
219 | { | |
220 | ||
221 | for (; table->ctl_name || table->procname; table++, (*pos)++) { | |
222 | int res; | |
223 | ||
224 | /* Can't do anything without a proc name */ | |
225 | if (!table->procname) | |
226 | continue; | |
227 | ||
228 | if (*pos < file->f_pos) | |
229 | continue; | |
230 | ||
231 | res = proc_sys_fill_cache(file, dirent, filldir, head, table); | |
232 | if (res) | |
233 | return res; | |
234 | ||
235 | file->f_pos = *pos + 1; | |
236 | } | |
237 | return 0; | |
77b14db5 EB |
238 | } |
239 | ||
240 | static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir) | |
241 | { | |
9043476f | 242 | struct dentry *dentry = filp->f_path.dentry; |
77b14db5 | 243 | struct inode *inode = dentry->d_inode; |
9043476f AV |
244 | struct ctl_table_header *head = grab_header(inode); |
245 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
246 | struct ctl_table_header *h = NULL; | |
77b14db5 | 247 | unsigned long pos; |
9043476f AV |
248 | int ret = -EINVAL; |
249 | ||
250 | if (IS_ERR(head)) | |
251 | return PTR_ERR(head); | |
77b14db5 | 252 | |
9043476f AV |
253 | if (table && !table->child) { |
254 | WARN_ON(1); | |
77b14db5 | 255 | goto out; |
9043476f AV |
256 | } |
257 | ||
258 | table = table ? table->child : head->ctl_table; | |
77b14db5 EB |
259 | |
260 | ret = 0; | |
261 | /* Avoid a switch here: arm builds fail with missing __cmpdi2 */ | |
262 | if (filp->f_pos == 0) { | |
263 | if (filldir(dirent, ".", 1, filp->f_pos, | |
264 | inode->i_ino, DT_DIR) < 0) | |
265 | goto out; | |
266 | filp->f_pos++; | |
267 | } | |
268 | if (filp->f_pos == 1) { | |
269 | if (filldir(dirent, "..", 2, filp->f_pos, | |
270 | parent_ino(dentry), DT_DIR) < 0) | |
271 | goto out; | |
272 | filp->f_pos++; | |
273 | } | |
274 | pos = 2; | |
275 | ||
9043476f AV |
276 | ret = scan(head, table, &pos, filp, dirent, filldir); |
277 | if (ret) | |
278 | goto out; | |
77b14db5 | 279 | |
9043476f AV |
280 | for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { |
281 | if (h->attached_to != table) | |
77b14db5 | 282 | continue; |
9043476f AV |
283 | ret = scan(h, h->attached_by, &pos, filp, dirent, filldir); |
284 | if (ret) { | |
285 | sysctl_head_finish(h); | |
286 | break; | |
77b14db5 EB |
287 | } |
288 | } | |
289 | ret = 1; | |
290 | out: | |
291 | sysctl_head_finish(head); | |
292 | return ret; | |
293 | } | |
294 | ||
e6305c43 | 295 | static int proc_sys_permission(struct inode *inode, int mask) |
77b14db5 EB |
296 | { |
297 | /* | |
298 | * sysctl entries that are not writeable, | |
299 | * are _NOT_ writeable, capabilities or not. | |
300 | */ | |
f696a365 MS |
301 | struct ctl_table_header *head; |
302 | struct ctl_table *table; | |
77b14db5 EB |
303 | int error; |
304 | ||
f696a365 MS |
305 | /* Executable files are not allowed under /proc/sys/ */ |
306 | if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) | |
307 | return -EACCES; | |
308 | ||
309 | head = grab_header(inode); | |
9043476f AV |
310 | if (IS_ERR(head)) |
311 | return PTR_ERR(head); | |
77b14db5 | 312 | |
f696a365 | 313 | table = PROC_I(inode)->sysctl_entry; |
9043476f AV |
314 | if (!table) /* global root - r-xr-xr-x */ |
315 | error = mask & MAY_WRITE ? -EACCES : 0; | |
316 | else /* Use the permissions on the sysctl table entry */ | |
317 | error = sysctl_perm(head->root, table, mask); | |
77b14db5 | 318 | |
77b14db5 EB |
319 | sysctl_head_finish(head); |
320 | return error; | |
321 | } | |
322 | ||
323 | static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr) | |
324 | { | |
325 | struct inode *inode = dentry->d_inode; | |
326 | int error; | |
327 | ||
328 | if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) | |
329 | return -EPERM; | |
330 | ||
331 | error = inode_change_ok(inode, attr); | |
9d0633cf JJ |
332 | if (!error) |
333 | error = inode_setattr(inode, attr); | |
77b14db5 EB |
334 | |
335 | return error; | |
336 | } | |
337 | ||
9043476f AV |
338 | static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) |
339 | { | |
340 | struct inode *inode = dentry->d_inode; | |
341 | struct ctl_table_header *head = grab_header(inode); | |
342 | struct ctl_table *table = PROC_I(inode)->sysctl_entry; | |
343 | ||
344 | if (IS_ERR(head)) | |
345 | return PTR_ERR(head); | |
346 | ||
347 | generic_fillattr(inode, stat); | |
348 | if (table) | |
349 | stat->mode = (stat->mode & S_IFMT) | table->mode; | |
350 | ||
351 | sysctl_head_finish(head); | |
352 | return 0; | |
353 | } | |
354 | ||
77b14db5 EB |
355 | static const struct file_operations proc_sys_file_operations = { |
356 | .read = proc_sys_read, | |
357 | .write = proc_sys_write, | |
9043476f AV |
358 | }; |
359 | ||
360 | static const struct file_operations proc_sys_dir_file_operations = { | |
77b14db5 | 361 | .readdir = proc_sys_readdir, |
3222a3e5 | 362 | .llseek = generic_file_llseek, |
77b14db5 EB |
363 | }; |
364 | ||
03a44825 | 365 | static const struct inode_operations proc_sys_inode_operations = { |
9043476f AV |
366 | .permission = proc_sys_permission, |
367 | .setattr = proc_sys_setattr, | |
368 | .getattr = proc_sys_getattr, | |
369 | }; | |
370 | ||
371 | static const struct inode_operations proc_sys_dir_operations = { | |
77b14db5 EB |
372 | .lookup = proc_sys_lookup, |
373 | .permission = proc_sys_permission, | |
374 | .setattr = proc_sys_setattr, | |
9043476f | 375 | .getattr = proc_sys_getattr, |
77b14db5 EB |
376 | }; |
377 | ||
378 | static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd) | |
379 | { | |
9043476f AV |
380 | return !PROC_I(dentry->d_inode)->sysctl->unregistering; |
381 | } | |
382 | ||
383 | static int proc_sys_delete(struct dentry *dentry) | |
384 | { | |
385 | return !!PROC_I(dentry->d_inode)->sysctl->unregistering; | |
386 | } | |
387 | ||
388 | static int proc_sys_compare(struct dentry *dir, struct qstr *qstr, | |
389 | struct qstr *name) | |
390 | { | |
391 | struct dentry *dentry = container_of(qstr, struct dentry, d_name); | |
392 | if (qstr->len != name->len) | |
393 | return 1; | |
394 | if (memcmp(qstr->name, name->name, name->len)) | |
395 | return 1; | |
396 | return !sysctl_is_seen(PROC_I(dentry->d_inode)->sysctl); | |
77b14db5 EB |
397 | } |
398 | ||
d72f71eb | 399 | static const struct dentry_operations proc_sys_dentry_operations = { |
77b14db5 | 400 | .d_revalidate = proc_sys_revalidate, |
9043476f AV |
401 | .d_delete = proc_sys_delete, |
402 | .d_compare = proc_sys_compare, | |
77b14db5 EB |
403 | }; |
404 | ||
1e0edd3f | 405 | int __init proc_sys_init(void) |
77b14db5 | 406 | { |
e1675231 AD |
407 | struct proc_dir_entry *proc_sys_root; |
408 | ||
77b14db5 | 409 | proc_sys_root = proc_mkdir("sys", NULL); |
9043476f AV |
410 | proc_sys_root->proc_iops = &proc_sys_dir_operations; |
411 | proc_sys_root->proc_fops = &proc_sys_dir_file_operations; | |
77b14db5 EB |
412 | proc_sys_root->nlink = 0; |
413 | return 0; | |
414 | } |