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 | ||
10 | static struct dentry_operations proc_sys_dentry_operations; | |
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 | 33 | inode->i_mode = table->mode; |
5c06fe77 | 34 | inode->i_uid = inode->i_gid = 0; |
9043476f AV |
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 | } | |
77b14db5 EB |
45 | out: |
46 | return inode; | |
47 | } | |
48 | ||
9043476f | 49 | static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name) |
77b14db5 EB |
50 | { |
51 | int len; | |
9043476f | 52 | for ( ; p->ctl_name || p->procname; p++) { |
77b14db5 | 53 | |
9043476f | 54 | if (!p->procname) |
77b14db5 EB |
55 | continue; |
56 | ||
9043476f | 57 | len = strlen(p->procname); |
77b14db5 EB |
58 | if (len != name->len) |
59 | continue; | |
60 | ||
9043476f | 61 | if (memcmp(p->procname, name->name, len) != 0) |
77b14db5 EB |
62 | continue; |
63 | ||
64 | /* I have a match */ | |
9043476f | 65 | return p; |
77b14db5 EB |
66 | } |
67 | return NULL; | |
68 | } | |
69 | ||
81324364 | 70 | static struct ctl_table_header *grab_header(struct inode *inode) |
77b14db5 | 71 | { |
9043476f AV |
72 | if (PROC_I(inode)->sysctl) |
73 | return sysctl_head_grab(PROC_I(inode)->sysctl); | |
74 | else | |
75 | return sysctl_head_next(NULL); | |
76 | } | |
77b14db5 | 77 | |
9043476f AV |
78 | static 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); | |
77b14db5 | 88 | |
9043476f AV |
89 | if (IS_ERR(head)) |
90 | return ERR_CAST(head); | |
77b14db5 | 91 | |
9043476f AV |
92 | if (table && !table->child) { |
93 | WARN_ON(1); | |
94 | goto out; | |
77b14db5 | 95 | } |
77b14db5 | 96 | |
9043476f | 97 | table = table ? table->child : head->ctl_table; |
77b14db5 | 98 | |
9043476f AV |
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 | } | |
77b14db5 | 108 | } |
77b14db5 | 109 | |
9043476f | 110 | if (!p) |
77b14db5 EB |
111 | goto out; |
112 | ||
113 | err = ERR_PTR(-ENOMEM); | |
9043476f AV |
114 | inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); |
115 | if (h) | |
116 | sysctl_head_finish(h); | |
117 | ||
77b14db5 EB |
118 | if (!inode) |
119 | goto out; | |
120 | ||
121 | err = NULL; | |
122 | dentry->d_op = &proc_sys_dentry_operations; | |
123 | d_add(dentry, inode); | |
124 | ||
125 | out: | |
126 | sysctl_head_finish(head); | |
127 | return err; | |
128 | } | |
129 | ||
7708bfb1 PE |
130 | static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf, |
131 | size_t count, loff_t *ppos, int write) | |
77b14db5 | 132 | { |
9043476f AV |
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; | |
2a2da53b DH |
136 | ssize_t error; |
137 | size_t res; | |
77b14db5 | 138 | |
9043476f AV |
139 | if (IS_ERR(head)) |
140 | return PTR_ERR(head); | |
77b14db5 EB |
141 | |
142 | /* | |
143 | * At this point we know that the sysctl was not unregistered | |
144 | * and won't be until we finish. | |
145 | */ | |
146 | error = -EPERM; | |
d7321cd6 | 147 | if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ)) |
77b14db5 EB |
148 | goto out; |
149 | ||
9043476f AV |
150 | /* if that can happen at all, it should be -EINVAL, not -EISDIR */ |
151 | error = -EINVAL; | |
152 | if (!table->proc_handler) | |
153 | goto out; | |
154 | ||
77b14db5 EB |
155 | /* careful: calling conventions are nasty here */ |
156 | res = count; | |
7708bfb1 | 157 | error = table->proc_handler(table, write, filp, buf, &res, ppos); |
77b14db5 EB |
158 | if (!error) |
159 | error = res; | |
160 | out: | |
161 | sysctl_head_finish(head); | |
162 | ||
163 | return error; | |
164 | } | |
165 | ||
7708bfb1 | 166 | static ssize_t proc_sys_read(struct file *filp, char __user *buf, |
77b14db5 EB |
167 | size_t count, loff_t *ppos) |
168 | { | |
7708bfb1 PE |
169 | return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0); |
170 | } | |
77b14db5 | 171 | |
7708bfb1 PE |
172 | static 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); | |
77b14db5 EB |
176 | } |
177 | ||
178 | ||
179 | static int proc_sys_fill_cache(struct file *filp, void *dirent, | |
9043476f AV |
180 | filldir_t filldir, |
181 | struct ctl_table_header *head, | |
182 | struct ctl_table *table) | |
77b14db5 | 183 | { |
77b14db5 EB |
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; | |
77b14db5 EB |
189 | |
190 | qname.name = table->procname; | |
191 | qname.len = strlen(table->procname); | |
192 | qname.hash = full_name_hash(qname.name, qname.len); | |
193 | ||
77b14db5 EB |
194 | child = d_lookup(dir, &qname); |
195 | if (!child) { | |
9043476f AV |
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); | |
77b14db5 | 205 | } |
9043476f AV |
206 | } else { |
207 | return -ENOMEM; | |
77b14db5 EB |
208 | } |
209 | } | |
77b14db5 | 210 | inode = child->d_inode; |
9043476f AV |
211 | ino = inode->i_ino; |
212 | type = inode->i_mode >> 12; | |
77b14db5 | 213 | dput(child); |
9043476f AV |
214 | return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type); |
215 | } | |
216 | ||
217 | static 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 | /* Can't do anything without a proc name */ | |
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; | |
77b14db5 EB |
239 | } |
240 | ||
241 | static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir) | |
242 | { | |
9043476f | 243 | struct dentry *dentry = filp->f_path.dentry; |
77b14db5 | 244 | struct inode *inode = dentry->d_inode; |
9043476f AV |
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; | |
77b14db5 | 248 | unsigned long pos; |
9043476f AV |
249 | int ret = -EINVAL; |
250 | ||
251 | if (IS_ERR(head)) | |
252 | return PTR_ERR(head); | |
77b14db5 | 253 | |
9043476f AV |
254 | if (table && !table->child) { |
255 | WARN_ON(1); | |
77b14db5 | 256 | goto out; |
9043476f AV |
257 | } |
258 | ||
259 | table = table ? table->child : head->ctl_table; | |
77b14db5 EB |
260 | |
261 | ret = 0; | |
262 | /* Avoid a switch here: arm builds fail with missing __cmpdi2 */ | |
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 | ||
9043476f AV |
277 | ret = scan(head, table, &pos, filp, dirent, filldir); |
278 | if (ret) | |
279 | goto out; | |
77b14db5 | 280 | |
9043476f AV |
281 | for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) { |
282 | if (h->attached_to != table) | |
77b14db5 | 283 | continue; |
9043476f AV |
284 | ret = scan(h, h->attached_by, &pos, filp, dirent, filldir); |
285 | if (ret) { | |
286 | sysctl_head_finish(h); | |
287 | break; | |
77b14db5 EB |
288 | } |
289 | } | |
290 | ret = 1; | |
291 | out: | |
292 | sysctl_head_finish(head); | |
293 | return ret; | |
294 | } | |
295 | ||
e6305c43 | 296 | static int proc_sys_permission(struct inode *inode, int mask) |
77b14db5 EB |
297 | { |
298 | /* | |
299 | * sysctl entries that are not writeable, | |
300 | * are _NOT_ writeable, capabilities or not. | |
301 | */ | |
f696a365 MS |
302 | struct ctl_table_header *head; |
303 | struct ctl_table *table; | |
77b14db5 EB |
304 | int error; |
305 | ||
f696a365 MS |
306 | /* Executable files are not allowed under /proc/sys/ */ |
307 | if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) | |
308 | return -EACCES; | |
309 | ||
310 | head = grab_header(inode); | |
9043476f AV |
311 | if (IS_ERR(head)) |
312 | return PTR_ERR(head); | |
77b14db5 | 313 | |
f696a365 | 314 | table = PROC_I(inode)->sysctl_entry; |
9043476f AV |
315 | if (!table) /* global root - r-xr-xr-x */ |
316 | error = mask & MAY_WRITE ? -EACCES : 0; | |
317 | else /* Use the permissions on the sysctl table entry */ | |
318 | error = sysctl_perm(head->root, table, mask); | |
77b14db5 | 319 | |
77b14db5 EB |
320 | sysctl_head_finish(head); |
321 | return error; | |
322 | } | |
323 | ||
324 | static 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); | |
9d0633cf JJ |
333 | if (!error) |
334 | error = inode_setattr(inode, attr); | |
77b14db5 EB |
335 | |
336 | return error; | |
337 | } | |
338 | ||
9043476f AV |
339 | static 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 | ||
77b14db5 EB |
356 | static const struct file_operations proc_sys_file_operations = { |
357 | .read = proc_sys_read, | |
358 | .write = proc_sys_write, | |
9043476f AV |
359 | }; |
360 | ||
361 | static const struct file_operations proc_sys_dir_file_operations = { | |
77b14db5 | 362 | .readdir = proc_sys_readdir, |
3222a3e5 | 363 | .llseek = generic_file_llseek, |
77b14db5 EB |
364 | }; |
365 | ||
03a44825 | 366 | static const struct inode_operations proc_sys_inode_operations = { |
9043476f AV |
367 | .permission = proc_sys_permission, |
368 | .setattr = proc_sys_setattr, | |
369 | .getattr = proc_sys_getattr, | |
370 | }; | |
371 | ||
372 | static const struct inode_operations proc_sys_dir_operations = { | |
77b14db5 EB |
373 | .lookup = proc_sys_lookup, |
374 | .permission = proc_sys_permission, | |
375 | .setattr = proc_sys_setattr, | |
9043476f | 376 | .getattr = proc_sys_getattr, |
77b14db5 EB |
377 | }; |
378 | ||
379 | static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd) | |
380 | { | |
9043476f AV |
381 | return !PROC_I(dentry->d_inode)->sysctl->unregistering; |
382 | } | |
383 | ||
384 | static int proc_sys_delete(struct dentry *dentry) | |
385 | { | |
386 | return !!PROC_I(dentry->d_inode)->sysctl->unregistering; | |
387 | } | |
388 | ||
389 | static 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); | |
77b14db5 EB |
398 | } |
399 | ||
400 | static struct dentry_operations proc_sys_dentry_operations = { | |
401 | .d_revalidate = proc_sys_revalidate, | |
9043476f AV |
402 | .d_delete = proc_sys_delete, |
403 | .d_compare = proc_sys_compare, | |
77b14db5 EB |
404 | }; |
405 | ||
1e0edd3f | 406 | int __init proc_sys_init(void) |
77b14db5 | 407 | { |
e1675231 AD |
408 | struct proc_dir_entry *proc_sys_root; |
409 | ||
77b14db5 | 410 | proc_sys_root = proc_mkdir("sys", NULL); |
9043476f AV |
411 | proc_sys_root->proc_iops = &proc_sys_dir_operations; |
412 | proc_sys_root->proc_fops = &proc_sys_dir_file_operations; | |
77b14db5 EB |
413 | proc_sys_root->nlink = 0; |
414 | return 0; | |
415 | } |