5 #include <linux/sysctl.h>
6 #include <linux/proc_fs.h>
7 #include <linux/security.h>
10 static struct dentry_operations proc_sys_dentry_operations;
11 static const struct file_operations proc_sys_file_operations;
12 static struct inode_operations proc_sys_inode_operations;
14 static void proc_sys_refresh_inode(struct inode *inode, struct ctl_table *table)
16 /* Refresh the cached information bits in the inode */
20 inode->i_mode = table->mode;
21 if (table->proc_handler) {
22 inode->i_mode |= S_IFREG;
25 inode->i_mode |= S_IFDIR;
26 inode->i_nlink = 0; /* It is too hard to figure out */
31 static struct inode *proc_sys_make_inode(struct inode *dir, struct ctl_table *table)
34 struct proc_inode *dir_ei, *ei;
37 inode = new_inode(dir->i_sb);
41 /* A directory is always one deeper than it's parent */
43 depth = dir_ei->fd + 1;
47 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
48 inode->i_op = &proc_sys_inode_operations;
49 inode->i_fop = &proc_sys_file_operations;
50 proc_sys_refresh_inode(inode, table);
55 static struct dentry *proc_sys_ancestor(struct dentry *dentry, int depth)
58 struct proc_inode *ei;
60 ei = PROC_I(dentry->d_inode);
64 dentry = dentry->d_parent;
69 static struct ctl_table *proc_sys_lookup_table_one(struct ctl_table *table,
73 for ( ; table->ctl_name || table->procname; table++) {
78 len = strlen(table->procname);
82 if (memcmp(table->procname, name->name, len) != 0)
91 static struct ctl_table *proc_sys_lookup_table(struct dentry *dentry,
92 struct ctl_table *table)
94 struct dentry *ancestor;
95 struct proc_inode *ei;
98 ei = PROC_I(dentry->d_inode);
104 for (i = 1; table && (i <= depth); i++) {
105 ancestor = proc_sys_ancestor(dentry, i);
106 table = proc_sys_lookup_table_one(table, &ancestor->d_name);
108 table = table->child;
113 static struct ctl_table *proc_sys_lookup_entry(struct dentry *dparent,
115 struct ctl_table *table)
117 table = proc_sys_lookup_table(dparent, table);
119 table = proc_sys_lookup_table_one(table, name);
123 static struct ctl_table *do_proc_sys_lookup(struct dentry *parent,
125 struct ctl_table_header **ptr)
127 struct ctl_table_header *head;
128 struct ctl_table *table = NULL;
130 for (head = sysctl_head_next(NULL); head;
131 head = sysctl_head_next(head)) {
132 table = proc_sys_lookup_entry(parent, name, head->ctl_table);
140 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
141 struct nameidata *nd)
143 struct ctl_table_header *head;
146 struct ctl_table *table;
148 err = ERR_PTR(-ENOENT);
149 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
153 err = ERR_PTR(-ENOMEM);
154 inode = proc_sys_make_inode(dir, table);
159 dentry->d_op = &proc_sys_dentry_operations;
160 d_add(dentry, inode);
163 sysctl_head_finish(head);
167 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
168 size_t count, loff_t *ppos)
170 struct dentry *dentry = filp->f_dentry;
171 struct ctl_table_header *head;
172 struct ctl_table *table;
175 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
176 /* Has the sysctl entry disappeared on us? */
181 /* Has the sysctl entry been replaced by a directory? */
183 if (!table->proc_handler)
187 * At this point we know that the sysctl was not unregistered
188 * and won't be until we finish.
191 if (sysctl_perm(table, MAY_READ))
194 /* careful: calling conventions are nasty here */
196 error = table->proc_handler(table, 0, filp, buf, &res, ppos);
200 sysctl_head_finish(head);
205 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
206 size_t count, loff_t *ppos)
208 struct dentry *dentry = filp->f_dentry;
209 struct ctl_table_header *head;
210 struct ctl_table *table;
213 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
214 /* Has the sysctl entry disappeared on us? */
219 /* Has the sysctl entry been replaced by a directory? */
221 if (!table->proc_handler)
225 * At this point we know that the sysctl was not unregistered
226 * and won't be until we finish.
229 if (sysctl_perm(table, MAY_WRITE))
232 /* careful: calling conventions are nasty here */
234 error = table->proc_handler(table, 1, filp, (char __user *)buf,
239 sysctl_head_finish(head);
245 static int proc_sys_fill_cache(struct file *filp, void *dirent,
246 filldir_t filldir, struct ctl_table *table)
248 struct ctl_table_header *head;
249 struct ctl_table *child_table = NULL;
250 struct dentry *child, *dir = filp->f_path.dentry;
254 unsigned type = DT_UNKNOWN;
257 qname.name = table->procname;
258 qname.len = strlen(table->procname);
259 qname.hash = full_name_hash(qname.name, qname.len);
261 /* Suppress duplicates.
262 * Only fill a directory entry if it is the value that
263 * an ordinary lookup of that name returns. Hide all
266 * If we ever cache this translation in the dcache
267 * I should do a dcache lookup first. But for now
268 * it is just simpler not to.
271 child_table = do_proc_sys_lookup(dir, &qname, &head);
272 sysctl_head_finish(head);
273 if (child_table != table)
276 child = d_lookup(dir, &qname);
279 new = d_alloc(dir, &qname);
281 inode = proc_sys_make_inode(dir->d_inode, table);
283 child = ERR_PTR(-ENOMEM);
285 new->d_op = &proc_sys_dentry_operations;
294 if (!child || IS_ERR(child) || !child->d_inode)
295 goto end_instantiate;
296 inode = child->d_inode;
299 type = inode->i_mode >> 12;
304 ino= find_inode_number(dir, &qname);
307 return filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
310 static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
312 struct dentry *dentry = filp->f_dentry;
313 struct inode *inode = dentry->d_inode;
314 struct ctl_table_header *head = NULL;
315 struct ctl_table *table;
320 if (!S_ISDIR(inode->i_mode))
324 /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
325 if (filp->f_pos == 0) {
326 if (filldir(dirent, ".", 1, filp->f_pos,
327 inode->i_ino, DT_DIR) < 0)
331 if (filp->f_pos == 1) {
332 if (filldir(dirent, "..", 2, filp->f_pos,
333 parent_ino(dentry), DT_DIR) < 0)
339 /* - Find each instance of the directory
340 * - Read all entries in each instance
341 * - Before returning an entry to user space lookup the entry
342 * by name and if I find a different entry don't return
343 * this one because it means it is a buried dup.
344 * For sysctl this should only happen for directory entries.
346 for (head = sysctl_head_next(NULL); head; head = sysctl_head_next(head)) {
347 table = proc_sys_lookup_table(dentry, head->ctl_table);
352 for (; table->ctl_name || table->procname; table++, pos++) {
353 /* Can't do anything without a proc name */
354 if (!table->procname)
357 if (pos < filp->f_pos)
360 if (proc_sys_fill_cache(filp, dirent, filldir, table) < 0)
362 filp->f_pos = pos + 1;
367 sysctl_head_finish(head);
371 static int proc_sys_permission(struct inode *inode, int mask, struct nameidata *nd)
374 * sysctl entries that are not writeable,
375 * are _NOT_ writeable, capabilities or not.
377 struct ctl_table_header *head;
378 struct ctl_table *table;
379 struct dentry *dentry;
385 depth = PROC_I(inode)->fd;
387 /* First check the cached permissions, in case we don't have
388 * enough information to lookup the sysctl table entry.
391 mode = inode->i_mode;
393 if (current->euid == 0)
395 else if (in_group_p(0))
398 if ((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)
401 /* If we can't get a sysctl table entry the permission
402 * checks on the cached mode will have to be enough.
408 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
410 /* If the entry does not exist deny permission */
415 /* Use the permissions on the sysctl table entry */
416 error = sysctl_perm(table, mask);
418 sysctl_head_finish(head);
422 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
424 struct inode *inode = dentry->d_inode;
427 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
430 error = inode_change_ok(inode, attr);
432 error = security_inode_setattr(dentry, attr);
434 error = inode_setattr(inode, attr);
440 /* I'm lazy and don't distinguish between files and directories,
443 static const struct file_operations proc_sys_file_operations = {
444 .read = proc_sys_read,
445 .write = proc_sys_write,
446 .readdir = proc_sys_readdir,
449 static struct inode_operations proc_sys_inode_operations = {
450 .lookup = proc_sys_lookup,
451 .permission = proc_sys_permission,
452 .setattr = proc_sys_setattr,
455 static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
457 struct ctl_table_header *head;
458 struct ctl_table *table;
459 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
460 proc_sys_refresh_inode(dentry->d_inode, table);
461 sysctl_head_finish(head);
465 static struct dentry_operations proc_sys_dentry_operations = {
466 .d_revalidate = proc_sys_revalidate,
469 static struct proc_dir_entry *proc_sys_root;
471 int proc_sys_init(void)
473 proc_sys_root = proc_mkdir("sys", NULL);
474 proc_sys_root->proc_iops = &proc_sys_inode_operations;
475 proc_sys_root->proc_fops = &proc_sys_file_operations;
476 proc_sys_root->nlink = 0;