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 const 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 inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */
51 proc_sys_refresh_inode(inode, table);
56 static struct dentry *proc_sys_ancestor(struct dentry *dentry, int depth)
59 struct proc_inode *ei;
61 ei = PROC_I(dentry->d_inode);
65 dentry = dentry->d_parent;
70 static struct ctl_table *proc_sys_lookup_table_one(struct ctl_table *table,
74 for ( ; table->ctl_name || table->procname; table++) {
79 len = strlen(table->procname);
83 if (memcmp(table->procname, name->name, len) != 0)
92 static struct ctl_table *proc_sys_lookup_table(struct dentry *dentry,
93 struct ctl_table *table)
95 struct dentry *ancestor;
96 struct proc_inode *ei;
99 ei = PROC_I(dentry->d_inode);
105 for (i = 1; table && (i <= depth); i++) {
106 ancestor = proc_sys_ancestor(dentry, i);
107 table = proc_sys_lookup_table_one(table, &ancestor->d_name);
109 table = table->child;
114 static struct ctl_table *proc_sys_lookup_entry(struct dentry *dparent,
116 struct ctl_table *table)
118 table = proc_sys_lookup_table(dparent, table);
120 table = proc_sys_lookup_table_one(table, name);
124 static struct ctl_table *do_proc_sys_lookup(struct dentry *parent,
126 struct ctl_table_header **ptr)
128 struct ctl_table_header *head;
129 struct ctl_table *table = NULL;
131 for (head = sysctl_head_next(NULL); head;
132 head = sysctl_head_next(head)) {
133 table = proc_sys_lookup_entry(parent, name, head->ctl_table);
141 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
142 struct nameidata *nd)
144 struct ctl_table_header *head;
147 struct ctl_table *table;
149 err = ERR_PTR(-ENOENT);
150 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
154 err = ERR_PTR(-ENOMEM);
155 inode = proc_sys_make_inode(dir, table);
160 dentry->d_op = &proc_sys_dentry_operations;
161 d_add(dentry, inode);
164 sysctl_head_finish(head);
168 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
169 size_t count, loff_t *ppos, int write)
171 struct dentry *dentry = filp->f_dentry;
172 struct ctl_table_header *head;
173 struct ctl_table *table;
177 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
178 /* Has the sysctl entry disappeared on us? */
183 /* Has the sysctl entry been replaced by a directory? */
185 if (!table->proc_handler)
189 * At this point we know that the sysctl was not unregistered
190 * and won't be until we finish.
193 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
196 /* careful: calling conventions are nasty here */
198 error = table->proc_handler(table, write, filp, buf, &res, ppos);
202 sysctl_head_finish(head);
207 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
208 size_t count, loff_t *ppos)
210 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
213 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
214 size_t count, loff_t *ppos)
216 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
220 static int proc_sys_fill_cache(struct file *filp, void *dirent,
221 filldir_t filldir, struct ctl_table *table)
223 struct ctl_table_header *head;
224 struct ctl_table *child_table = NULL;
225 struct dentry *child, *dir = filp->f_path.dentry;
229 unsigned type = DT_UNKNOWN;
232 qname.name = table->procname;
233 qname.len = strlen(table->procname);
234 qname.hash = full_name_hash(qname.name, qname.len);
236 /* Suppress duplicates.
237 * Only fill a directory entry if it is the value that
238 * an ordinary lookup of that name returns. Hide all
241 * If we ever cache this translation in the dcache
242 * I should do a dcache lookup first. But for now
243 * it is just simpler not to.
246 child_table = do_proc_sys_lookup(dir, &qname, &head);
247 sysctl_head_finish(head);
248 if (child_table != table)
251 child = d_lookup(dir, &qname);
254 new = d_alloc(dir, &qname);
256 inode = proc_sys_make_inode(dir->d_inode, table);
258 child = ERR_PTR(-ENOMEM);
260 new->d_op = &proc_sys_dentry_operations;
269 if (!child || IS_ERR(child) || !child->d_inode)
270 goto end_instantiate;
271 inode = child->d_inode;
274 type = inode->i_mode >> 12;
279 ino= find_inode_number(dir, &qname);
282 return filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
285 static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
287 struct dentry *dentry = filp->f_dentry;
288 struct inode *inode = dentry->d_inode;
289 struct ctl_table_header *head = NULL;
290 struct ctl_table *table;
295 if (!S_ISDIR(inode->i_mode))
299 /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
300 if (filp->f_pos == 0) {
301 if (filldir(dirent, ".", 1, filp->f_pos,
302 inode->i_ino, DT_DIR) < 0)
306 if (filp->f_pos == 1) {
307 if (filldir(dirent, "..", 2, filp->f_pos,
308 parent_ino(dentry), DT_DIR) < 0)
314 /* - Find each instance of the directory
315 * - Read all entries in each instance
316 * - Before returning an entry to user space lookup the entry
317 * by name and if I find a different entry don't return
318 * this one because it means it is a buried dup.
319 * For sysctl this should only happen for directory entries.
321 for (head = sysctl_head_next(NULL); head; head = sysctl_head_next(head)) {
322 table = proc_sys_lookup_table(dentry, head->ctl_table);
327 for (; table->ctl_name || table->procname; table++, pos++) {
328 /* Can't do anything without a proc name */
329 if (!table->procname)
332 if (pos < filp->f_pos)
335 if (proc_sys_fill_cache(filp, dirent, filldir, table) < 0)
337 filp->f_pos = pos + 1;
342 sysctl_head_finish(head);
346 static int proc_sys_permission(struct inode *inode, int mask, struct nameidata *nd)
349 * sysctl entries that are not writeable,
350 * are _NOT_ writeable, capabilities or not.
352 struct ctl_table_header *head;
353 struct ctl_table *table;
354 struct dentry *dentry;
360 depth = PROC_I(inode)->fd;
362 /* First check the cached permissions, in case we don't have
363 * enough information to lookup the sysctl table entry.
366 mode = inode->i_mode;
368 if (current->euid == 0)
370 else if (in_group_p(0))
373 if ((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)
376 /* If we can't get a sysctl table entry the permission
377 * checks on the cached mode will have to be enough.
382 dentry = nd->path.dentry;
383 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
385 /* If the entry does not exist deny permission */
390 /* Use the permissions on the sysctl table entry */
391 error = sysctl_perm(head->root, table, mask);
393 sysctl_head_finish(head);
397 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
399 struct inode *inode = dentry->d_inode;
402 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
405 error = inode_change_ok(inode, attr);
407 error = inode_setattr(inode, attr);
412 /* I'm lazy and don't distinguish between files and directories,
415 static const struct file_operations proc_sys_file_operations = {
416 .read = proc_sys_read,
417 .write = proc_sys_write,
418 .readdir = proc_sys_readdir,
421 static const struct inode_operations proc_sys_inode_operations = {
422 .lookup = proc_sys_lookup,
423 .permission = proc_sys_permission,
424 .setattr = proc_sys_setattr,
427 static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
429 struct ctl_table_header *head;
430 struct ctl_table *table;
431 table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
432 proc_sys_refresh_inode(dentry->d_inode, table);
433 sysctl_head_finish(head);
437 static struct dentry_operations proc_sys_dentry_operations = {
438 .d_revalidate = proc_sys_revalidate,
441 static struct proc_dir_entry *proc_sys_root;
443 int proc_sys_init(void)
445 proc_sys_root = proc_mkdir("sys", NULL);
446 proc_sys_root->proc_iops = &proc_sys_inode_operations;
447 proc_sys_root->proc_fops = &proc_sys_file_operations;
448 proc_sys_root->nlink = 0;