4 #include <linux/init.h>
5 #include <linux/sysctl.h>
6 #include <linux/proc_fs.h>
7 #include <linux/security.h>
8 #include <linux/namei.h>
11 static const struct dentry_operations proc_sys_dentry_operations;
12 static const struct file_operations proc_sys_file_operations;
13 static const struct inode_operations proc_sys_inode_operations;
14 static const struct file_operations proc_sys_dir_file_operations;
15 static const struct inode_operations proc_sys_dir_operations;
17 static struct inode *proc_sys_make_inode(struct super_block *sb,
18 struct ctl_table_header *head, struct ctl_table *table)
21 struct proc_inode *ei;
23 inode = new_inode(sb);
27 inode->i_ino = get_next_ino();
29 sysctl_head_get(head);
32 ei->sysctl_entry = table;
34 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
35 inode->i_mode = table->mode;
37 inode->i_mode |= S_IFREG;
38 inode->i_op = &proc_sys_inode_operations;
39 inode->i_fop = &proc_sys_file_operations;
41 inode->i_mode |= S_IFDIR;
43 inode->i_op = &proc_sys_dir_operations;
44 inode->i_fop = &proc_sys_dir_file_operations;
50 static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
52 for ( ; p->procname; p++) {
53 if (strlen(p->procname) != name->len)
56 if (memcmp(p->procname, name->name, name->len) != 0)
65 static struct ctl_table_header *grab_header(struct inode *inode)
67 if (PROC_I(inode)->sysctl)
68 return sysctl_head_grab(PROC_I(inode)->sysctl);
70 return sysctl_head_next(NULL);
73 static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
76 struct ctl_table_header *head = grab_header(dir);
77 struct ctl_table *table = PROC_I(dir)->sysctl_entry;
78 struct ctl_table_header *h = NULL;
79 struct qstr *name = &dentry->d_name;
82 struct dentry *err = ERR_PTR(-ENOENT);
85 return ERR_CAST(head);
87 if (table && !table->child) {
92 table = table ? table->child : head->ctl_table;
94 p = find_in_table(table, name);
96 for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
97 if (h->attached_to != table)
99 p = find_in_table(h->attached_by, name);
108 err = ERR_PTR(-ENOMEM);
109 inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
111 sysctl_head_finish(h);
117 d_set_d_op(dentry, &proc_sys_dentry_operations);
118 d_add(dentry, inode);
121 sysctl_head_finish(head);
125 static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
126 size_t count, loff_t *ppos, int write)
128 struct inode *inode = filp->f_path.dentry->d_inode;
129 struct ctl_table_header *head = grab_header(inode);
130 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
135 return PTR_ERR(head);
138 * At this point we know that the sysctl was not unregistered
139 * and won't be until we finish.
142 if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
145 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
147 if (!table->proc_handler)
150 /* careful: calling conventions are nasty here */
152 error = table->proc_handler(table, write, buf, &res, ppos);
156 sysctl_head_finish(head);
161 static ssize_t proc_sys_read(struct file *filp, char __user *buf,
162 size_t count, loff_t *ppos)
164 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
167 static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
168 size_t count, loff_t *ppos)
170 return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
174 static int proc_sys_fill_cache(struct file *filp, void *dirent,
176 struct ctl_table_header *head,
177 struct ctl_table *table)
179 struct dentry *child, *dir = filp->f_path.dentry;
183 unsigned type = DT_UNKNOWN;
185 qname.name = table->procname;
186 qname.len = strlen(table->procname);
187 qname.hash = full_name_hash(qname.name, qname.len);
189 child = d_lookup(dir, &qname);
191 child = d_alloc(dir, &qname);
193 inode = proc_sys_make_inode(dir->d_sb, head, table);
198 d_set_d_op(child, &proc_sys_dentry_operations);
205 inode = child->d_inode;
207 type = inode->i_mode >> 12;
209 return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
212 static int scan(struct ctl_table_header *head, ctl_table *table,
213 unsigned long *pos, struct file *file,
214 void *dirent, filldir_t filldir)
217 for (; table->procname; table++, (*pos)++) {
220 if (*pos < file->f_pos)
223 res = proc_sys_fill_cache(file, dirent, filldir, head, table);
227 file->f_pos = *pos + 1;
232 static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
234 struct dentry *dentry = filp->f_path.dentry;
235 struct inode *inode = dentry->d_inode;
236 struct ctl_table_header *head = grab_header(inode);
237 struct ctl_table *table = PROC_I(inode)->sysctl_entry;
238 struct ctl_table_header *h = NULL;
243 return PTR_ERR(head);
245 if (table && !table->child) {
250 table = table ? table->child : head->ctl_table;
253 /* Avoid a switch here: arm builds fail with missing __cmpdi2 */
254 if (filp->f_pos == 0) {
255 if (filldir(dirent, ".", 1, filp->f_pos,
256 inode->i_ino, DT_DIR) < 0)
260 if (filp->f_pos == 1) {
261 if (filldir(dirent, "..", 2, filp->f_pos,
262 parent_ino(dentry), DT_DIR) < 0)
268 ret = scan(head, table, &pos, filp, dirent, filldir);
272 for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
273 if (h->attached_to != table)
275 ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
277 sysctl_head_finish(h);
283 sysctl_head_finish(head);
287 static int proc_sys_permission(struct inode *inode, int mask)
290 * sysctl entries that are not writeable,
291 * are _NOT_ writeable, capabilities or not.
293 struct ctl_table_header *head;
294 struct ctl_table *table;
297 /* Executable files are not allowed under /proc/sys/ */
298 if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
301 head = grab_header(inode);
303 return PTR_ERR(head);
305 table = PROC_I(inode)->sysctl_entry;
306 if (!table) /* global root - r-xr-xr-x */
307 error = mask & MAY_WRITE ? -EACCES : 0;
308 else /* Use the permissions on the sysctl table entry */
309 error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK);
311 sysctl_head_finish(head);
315 static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
317 struct inode *inode = dentry->d_inode;
320 if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
323 error = inode_change_ok(inode, attr);
327 if ((attr->ia_valid & ATTR_SIZE) &&
328 attr->ia_size != i_size_read(inode)) {
329 error = vmtruncate(inode, attr->ia_size);
334 setattr_copy(inode, attr);
335 mark_inode_dirty(inode);
339 static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
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;
346 return PTR_ERR(head);
348 generic_fillattr(inode, stat);
350 stat->mode = (stat->mode & S_IFMT) | table->mode;
352 sysctl_head_finish(head);
356 static const struct file_operations proc_sys_file_operations = {
357 .read = proc_sys_read,
358 .write = proc_sys_write,
359 .llseek = default_llseek,
362 static const struct file_operations proc_sys_dir_file_operations = {
363 .read = generic_read_dir,
364 .readdir = proc_sys_readdir,
365 .llseek = generic_file_llseek,
368 static const struct inode_operations proc_sys_inode_operations = {
369 .permission = proc_sys_permission,
370 .setattr = proc_sys_setattr,
371 .getattr = proc_sys_getattr,
374 static const struct inode_operations proc_sys_dir_operations = {
375 .lookup = proc_sys_lookup,
376 .permission = proc_sys_permission,
377 .setattr = proc_sys_setattr,
378 .getattr = proc_sys_getattr,
381 static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
383 if (nd->flags & LOOKUP_RCU)
385 return !PROC_I(dentry->d_inode)->sysctl->unregistering;
388 static int proc_sys_delete(const struct dentry *dentry)
390 return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
393 static int proc_sys_compare(const struct dentry *parent,
394 const struct inode *pinode,
395 const struct dentry *dentry, const struct inode *inode,
396 unsigned int len, const char *str, const struct qstr *name)
398 struct ctl_table_header *head;
399 /* Although proc doesn't have negative dentries, rcu-walk means
400 * that inode here can be NULL */
401 /* AV: can it, indeed? */
404 if (name->len != len)
406 if (memcmp(name->name, str, len))
408 head = rcu_dereference(PROC_I(inode)->sysctl);
409 return !head || !sysctl_is_seen(head);
412 static const struct dentry_operations proc_sys_dentry_operations = {
413 .d_revalidate = proc_sys_revalidate,
414 .d_delete = proc_sys_delete,
415 .d_compare = proc_sys_compare,
418 int __init proc_sys_init(void)
420 struct proc_dir_entry *proc_sys_root;
422 proc_sys_root = proc_mkdir("sys", NULL);
423 proc_sys_root->proc_iops = &proc_sys_dir_operations;
424 proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
425 proc_sys_root->nlink = 0;