blob: 25798db14553265e899257d8e13e53fc356e81bb [file] [log] [blame]
Kay Sievers2b2af542009-04-30 15:23:42 +02001/*
2 * devtmpfs - kernel-maintained tmpfs-based /dev
3 *
4 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
5 *
6 * During bootup, before any driver core device is registered,
7 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
8 * device which requests a device node, will add a node in this
Kay Sieverse454cea2009-09-18 23:01:12 +02009 * filesystem.
Peter Korsgaard02fbe5e2012-04-17 12:13:18 +020010 * By default, all devices are named after the name of the device,
11 * owned by root and have a default mode of 0600. Subsystems can
12 * overwrite the default setting if needed.
Kay Sievers2b2af542009-04-30 15:23:42 +020013 */
14
15#include <linux/kernel.h>
16#include <linux/syscalls.h>
17#include <linux/mount.h>
18#include <linux/device.h>
19#include <linux/genhd.h>
20#include <linux/namei.h>
21#include <linux/fs.h>
22#include <linux/shmem_fs.h>
Peter Korsgaardda5e4ef2010-03-16 21:55:21 +010023#include <linux/ramfs.h>
Kay Sieverse454cea2009-09-18 23:01:12 +020024#include <linux/sched.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090025#include <linux/slab.h>
Al Viro2780f1f2011-06-27 16:25:29 -040026#include <linux/kthread.h>
Greg Kroah-Hartmanc3a30422013-04-10 09:00:15 -070027#include "base.h"
Kay Sievers2b2af542009-04-30 15:23:42 +020028
Al Viro2780f1f2011-06-27 16:25:29 -040029static struct task_struct *thread;
Kay Sievers2b2af542009-04-30 15:23:42 +020030
31#if defined CONFIG_DEVTMPFS_MOUNT
Al Virofc14f2f2010-07-25 01:48:30 +040032static int mount_dev = 1;
Kay Sievers2b2af542009-04-30 15:23:42 +020033#else
Al Virofc14f2f2010-07-25 01:48:30 +040034static int mount_dev;
Kay Sievers2b2af542009-04-30 15:23:42 +020035#endif
36
Al Viro2780f1f2011-06-27 16:25:29 -040037static DEFINE_SPINLOCK(req_lock);
38
39static struct req {
40 struct req *next;
41 struct completion done;
42 int err;
43 const char *name;
Al Viro2c9ede52011-07-23 20:24:48 -040044 umode_t mode; /* 0 => delete */
Greg Kroah-Hartman4e4098a2013-04-11 11:43:29 -070045 kuid_t uid;
46 kgid_t gid;
Al Viro2780f1f2011-06-27 16:25:29 -040047 struct device *dev;
48} *requests;
Kay Sieversed413ae2009-10-28 19:51:06 +010049
Kay Sievers2b2af542009-04-30 15:23:42 +020050static int __init mount_param(char *str)
51{
Al Virofc14f2f2010-07-25 01:48:30 +040052 mount_dev = simple_strtoul(str, NULL, 0);
Kay Sievers2b2af542009-04-30 15:23:42 +020053 return 1;
54}
55__setup("devtmpfs.mount=", mount_param);
56
Al Virofc14f2f2010-07-25 01:48:30 +040057static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,
58 const char *dev_name, void *data)
Kay Sievers2b2af542009-04-30 15:23:42 +020059{
Peter Korsgaardda5e4ef2010-03-16 21:55:21 +010060#ifdef CONFIG_TMPFS
Al Virofc14f2f2010-07-25 01:48:30 +040061 return mount_single(fs_type, flags, data, shmem_fill_super);
Peter Korsgaardda5e4ef2010-03-16 21:55:21 +010062#else
Al Virofc14f2f2010-07-25 01:48:30 +040063 return mount_single(fs_type, flags, data, ramfs_fill_super);
Peter Korsgaardda5e4ef2010-03-16 21:55:21 +010064#endif
Kay Sievers2b2af542009-04-30 15:23:42 +020065}
66
67static struct file_system_type dev_fs_type = {
68 .name = "devtmpfs",
Al Virofc14f2f2010-07-25 01:48:30 +040069 .mount = dev_mount,
Kay Sievers2b2af542009-04-30 15:23:42 +020070 .kill_sb = kill_litter_super,
71};
72
73#ifdef CONFIG_BLOCK
74static inline int is_blockdev(struct device *dev)
75{
76 return dev->class == &block_class;
77}
78#else
79static inline int is_blockdev(struct device *dev) { return 0; }
80#endif
81
Al Viro2780f1f2011-06-27 16:25:29 -040082int devtmpfs_create_node(struct device *dev)
83{
84 const char *tmp = NULL;
85 struct req req;
86
87 if (!thread)
88 return 0;
89
90 req.mode = 0;
Greg Kroah-Hartman4e4098a2013-04-11 11:43:29 -070091 req.uid = GLOBAL_ROOT_UID;
92 req.gid = GLOBAL_ROOT_GID;
Kay Sievers3c2670e2013-04-06 09:56:00 -070093 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
Al Viro2780f1f2011-06-27 16:25:29 -040094 if (!req.name)
95 return -ENOMEM;
96
97 if (req.mode == 0)
98 req.mode = 0600;
99 if (is_blockdev(dev))
100 req.mode |= S_IFBLK;
101 else
102 req.mode |= S_IFCHR;
103
104 req.dev = dev;
105
106 init_completion(&req.done);
107
108 spin_lock(&req_lock);
109 req.next = requests;
110 requests = &req;
111 spin_unlock(&req_lock);
112
113 wake_up_process(thread);
114 wait_for_completion(&req.done);
115
116 kfree(tmp);
117
118 return req.err;
119}
120
121int devtmpfs_delete_node(struct device *dev)
122{
123 const char *tmp = NULL;
124 struct req req;
125
126 if (!thread)
127 return 0;
128
Kay Sievers3c2670e2013-04-06 09:56:00 -0700129 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
Al Viro2780f1f2011-06-27 16:25:29 -0400130 if (!req.name)
131 return -ENOMEM;
132
133 req.mode = 0;
134 req.dev = dev;
135
136 init_completion(&req.done);
137
138 spin_lock(&req_lock);
139 req.next = requests;
140 requests = &req;
141 spin_unlock(&req_lock);
142
143 wake_up_process(thread);
144 wait_for_completion(&req.done);
145
146 kfree(tmp);
147 return req.err;
148}
149
Al Virofbd48a62011-07-24 10:47:56 -0400150static int dev_mkdir(const char *name, umode_t mode)
Kay Sievers2b2af542009-04-30 15:23:42 +0200151{
Kay Sievers2b2af542009-04-30 15:23:42 +0200152 struct dentry *dentry;
Al Viro69753a02011-06-27 16:35:45 -0400153 struct path path;
Kay Sievers2b2af542009-04-30 15:23:42 +0200154 int err;
155
Jeff Layton1ac12b42012-12-11 12:10:06 -0500156 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
Al Viro69753a02011-06-27 16:35:45 -0400157 if (IS_ERR(dentry))
158 return PTR_ERR(dentry);
Kay Sievers2b2af542009-04-30 15:23:42 +0200159
Al Viro69753a02011-06-27 16:35:45 -0400160 err = vfs_mkdir(path.dentry->d_inode, dentry, mode);
161 if (!err)
162 /* mark as kernel-created inode */
163 dentry->d_inode->i_private = &thread;
Al Viro921a1652012-07-20 01:15:31 +0400164 done_path_create(&path, dentry);
Kay Sievers2b2af542009-04-30 15:23:42 +0200165 return err;
166}
167
168static int create_path(const char *nodepath)
169{
Al Viro5da4e682011-06-27 16:37:12 -0400170 char *path;
171 char *s;
Al Viro9d108d22011-07-27 22:27:33 -0400172 int err = 0;
Kay Sievers2b2af542009-04-30 15:23:42 +0200173
Al Viro5da4e682011-06-27 16:37:12 -0400174 /* parent directories do not exist, create them */
175 path = kstrdup(nodepath, GFP_KERNEL);
176 if (!path)
177 return -ENOMEM;
Kay Sievers2b2af542009-04-30 15:23:42 +0200178
Al Viro5da4e682011-06-27 16:37:12 -0400179 s = path;
180 for (;;) {
181 s = strchr(s, '/');
182 if (!s)
183 break;
184 s[0] = '\0';
185 err = dev_mkdir(path, 0755);
186 if (err && err != -EEXIST)
187 break;
188 s[0] = '/';
189 s++;
Kay Sievers2b2af542009-04-30 15:23:42 +0200190 }
Al Viro5da4e682011-06-27 16:37:12 -0400191 kfree(path);
Kay Sievers2b2af542009-04-30 15:23:42 +0200192 return err;
193}
194
Greg Kroah-Hartman4e4098a2013-04-11 11:43:29 -0700195static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
196 kgid_t gid, struct device *dev)
Kay Sievers2b2af542009-04-30 15:23:42 +0200197{
Kay Sievers2b2af542009-04-30 15:23:42 +0200198 struct dentry *dentry;
Al Viro69753a02011-06-27 16:35:45 -0400199 struct path path;
Kay Sievers2b2af542009-04-30 15:23:42 +0200200 int err;
201
Al Viro69753a02011-06-27 16:35:45 -0400202 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
203 if (dentry == ERR_PTR(-ENOENT)) {
Kay Sievers2b2af542009-04-30 15:23:42 +0200204 create_path(nodename);
Al Viro69753a02011-06-27 16:35:45 -0400205 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
Kay Sievers2b2af542009-04-30 15:23:42 +0200206 }
Al Viro69753a02011-06-27 16:35:45 -0400207 if (IS_ERR(dentry))
208 return PTR_ERR(dentry);
Kay Sievers2b2af542009-04-30 15:23:42 +0200209
Kay Sievers3c2670e2013-04-06 09:56:00 -0700210 err = vfs_mknod(path.dentry->d_inode, dentry, mode, dev->devt);
Al Viro69753a02011-06-27 16:35:45 -0400211 if (!err) {
212 struct iattr newattrs;
Kay Sievers00926992009-10-28 19:50:57 +0100213
Al Viro69753a02011-06-27 16:35:45 -0400214 newattrs.ia_mode = mode;
Greg Kroah-Hartman4e4098a2013-04-11 11:43:29 -0700215 newattrs.ia_uid = uid;
216 newattrs.ia_gid = gid;
Kay Sievers3c2670e2013-04-06 09:56:00 -0700217 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
Al Viro69753a02011-06-27 16:35:45 -0400218 mutex_lock(&dentry->d_inode->i_mutex);
J. Bruce Fields27ac0ff2011-09-20 17:19:26 -0400219 notify_change(dentry, &newattrs, NULL);
Al Viro69753a02011-06-27 16:35:45 -0400220 mutex_unlock(&dentry->d_inode->i_mutex);
Kay Sievers00926992009-10-28 19:50:57 +0100221
Al Viro69753a02011-06-27 16:35:45 -0400222 /* mark as kernel-created inode */
223 dentry->d_inode->i_private = &thread;
Kay Sievers2b2af542009-04-30 15:23:42 +0200224 }
Al Viro921a1652012-07-20 01:15:31 +0400225 done_path_create(&path, dentry);
Kay Sievers2b2af542009-04-30 15:23:42 +0200226 return err;
227}
228
229static int dev_rmdir(const char *name)
230{
Al Viro79714f72012-06-15 03:01:42 +0400231 struct path parent;
Kay Sievers2b2af542009-04-30 15:23:42 +0200232 struct dentry *dentry;
233 int err;
234
Al Viro79714f72012-06-15 03:01:42 +0400235 dentry = kern_path_locked(name, &parent);
236 if (IS_ERR(dentry))
237 return PTR_ERR(dentry);
238 if (dentry->d_inode) {
239 if (dentry->d_inode->i_private == &thread)
240 err = vfs_rmdir(parent.dentry->d_inode, dentry);
241 else
242 err = -EPERM;
Kay Sievers2b2af542009-04-30 15:23:42 +0200243 } else {
Al Viro79714f72012-06-15 03:01:42 +0400244 err = -ENOENT;
Kay Sievers2b2af542009-04-30 15:23:42 +0200245 }
Al Viro79714f72012-06-15 03:01:42 +0400246 dput(dentry);
247 mutex_unlock(&parent.dentry->d_inode->i_mutex);
248 path_put(&parent);
Kay Sievers2b2af542009-04-30 15:23:42 +0200249 return err;
250}
251
252static int delete_path(const char *nodepath)
253{
254 const char *path;
255 int err = 0;
256
257 path = kstrdup(nodepath, GFP_KERNEL);
258 if (!path)
259 return -ENOMEM;
260
Kay Sieversed413ae2009-10-28 19:51:06 +0100261 for (;;) {
Kay Sievers2b2af542009-04-30 15:23:42 +0200262 char *base;
263
264 base = strrchr(path, '/');
265 if (!base)
266 break;
267 base[0] = '\0';
268 err = dev_rmdir(path);
269 if (err)
270 break;
271 }
272
273 kfree(path);
274 return err;
275}
276
277static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
278{
279 /* did we create it */
Al Viro2780f1f2011-06-27 16:25:29 -0400280 if (inode->i_private != &thread)
Kay Sievers2b2af542009-04-30 15:23:42 +0200281 return 0;
282
283 /* does the dev_t match */
284 if (is_blockdev(dev)) {
285 if (!S_ISBLK(stat->mode))
286 return 0;
287 } else {
288 if (!S_ISCHR(stat->mode))
289 return 0;
290 }
291 if (stat->rdev != dev->devt)
292 return 0;
293
294 /* ours */
295 return 1;
296}
297
Al Viro2780f1f2011-06-27 16:25:29 -0400298static int handle_remove(const char *nodename, struct device *dev)
Kay Sievers2b2af542009-04-30 15:23:42 +0200299{
Al Viro79714f72012-06-15 03:01:42 +0400300 struct path parent;
Kay Sievers2b2af542009-04-30 15:23:42 +0200301 struct dentry *dentry;
Axel Linfbde7c62013-11-16 16:15:23 +0800302 int deleted = 0;
Kay Sievers2b2af542009-04-30 15:23:42 +0200303 int err;
304
Al Viro79714f72012-06-15 03:01:42 +0400305 dentry = kern_path_locked(nodename, &parent);
306 if (IS_ERR(dentry))
307 return PTR_ERR(dentry);
Kay Sievers2b2af542009-04-30 15:23:42 +0200308
Al Viro79714f72012-06-15 03:01:42 +0400309 if (dentry->d_inode) {
310 struct kstat stat;
Al Viro3dadecc2013-01-24 02:18:08 -0500311 struct path p = {.mnt = parent.mnt, .dentry = dentry};
312 err = vfs_getattr(&p, &stat);
Al Viro79714f72012-06-15 03:01:42 +0400313 if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
314 struct iattr newattrs;
315 /*
316 * before unlinking this node, reset permissions
317 * of possible references like hardlinks
318 */
Eric W. Biederman91fa2cc2012-04-25 04:25:35 -0700319 newattrs.ia_uid = GLOBAL_ROOT_UID;
320 newattrs.ia_gid = GLOBAL_ROOT_GID;
Al Viro79714f72012-06-15 03:01:42 +0400321 newattrs.ia_mode = stat.mode & ~0777;
322 newattrs.ia_valid =
323 ATTR_UID|ATTR_GID|ATTR_MODE;
324 mutex_lock(&dentry->d_inode->i_mutex);
J. Bruce Fields27ac0ff2011-09-20 17:19:26 -0400325 notify_change(dentry, &newattrs, NULL);
Al Viro79714f72012-06-15 03:01:42 +0400326 mutex_unlock(&dentry->d_inode->i_mutex);
J. Bruce Fieldsb21996e2011-09-20 09:14:34 -0400327 err = vfs_unlink(parent.dentry->d_inode, dentry, NULL);
Al Viro79714f72012-06-15 03:01:42 +0400328 if (!err || err == -ENOENT)
329 deleted = 1;
Kay Sievers2b2af542009-04-30 15:23:42 +0200330 }
Kay Sievers2b2af542009-04-30 15:23:42 +0200331 } else {
Al Viro79714f72012-06-15 03:01:42 +0400332 err = -ENOENT;
Kay Sievers2b2af542009-04-30 15:23:42 +0200333 }
Al Viro79714f72012-06-15 03:01:42 +0400334 dput(dentry);
335 mutex_unlock(&parent.dentry->d_inode->i_mutex);
Kay Sievers2b2af542009-04-30 15:23:42 +0200336
Al Viro79714f72012-06-15 03:01:42 +0400337 path_put(&parent);
Kay Sievers2b2af542009-04-30 15:23:42 +0200338 if (deleted && strchr(nodename, '/'))
339 delete_path(nodename);
Kay Sievers2b2af542009-04-30 15:23:42 +0200340 return err;
341}
342
343/*
344 * If configured, or requested by the commandline, devtmpfs will be
345 * auto-mounted after the kernel mounted the root filesystem.
346 */
Kay Sievers073120c2009-10-28 19:51:17 +0100347int devtmpfs_mount(const char *mntdir)
Kay Sievers2b2af542009-04-30 15:23:42 +0200348{
Kay Sievers2b2af542009-04-30 15:23:42 +0200349 int err;
350
Al Virofc14f2f2010-07-25 01:48:30 +0400351 if (!mount_dev)
Kay Sievers2b2af542009-04-30 15:23:42 +0200352 return 0;
353
Al Viro2780f1f2011-06-27 16:25:29 -0400354 if (!thread)
Kay Sievers2b2af542009-04-30 15:23:42 +0200355 return 0;
356
Kay Sievers073120c2009-10-28 19:51:17 +0100357 err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
Kay Sievers2b2af542009-04-30 15:23:42 +0200358 if (err)
359 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
360 else
361 printk(KERN_INFO "devtmpfs: mounted\n");
Kay Sievers2b2af542009-04-30 15:23:42 +0200362 return err;
363}
364
Arnaud Lacombef9e0b152011-07-21 13:16:19 -0400365static DECLARE_COMPLETION(setup_done);
Al Viro2780f1f2011-06-27 16:25:29 -0400366
Greg Kroah-Hartman4e4098a2013-04-11 11:43:29 -0700367static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
Kay Sievers3c2670e2013-04-06 09:56:00 -0700368 struct device *dev)
Al Viro2780f1f2011-06-27 16:25:29 -0400369{
370 if (mode)
Kay Sievers3c2670e2013-04-06 09:56:00 -0700371 return handle_create(name, mode, uid, gid, dev);
Al Viro2780f1f2011-06-27 16:25:29 -0400372 else
373 return handle_remove(name, dev);
374}
375
376static int devtmpfsd(void *p)
377{
378 char options[] = "mode=0755";
379 int *err = p;
380 *err = sys_unshare(CLONE_NEWNS);
381 if (*err)
382 goto out;
383 *err = sys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
384 if (*err)
385 goto out;
386 sys_chdir("/.."); /* will traverse into overmounted root */
387 sys_chroot(".");
388 complete(&setup_done);
389 while (1) {
390 spin_lock(&req_lock);
391 while (requests) {
392 struct req *req = requests;
393 requests = NULL;
394 spin_unlock(&req_lock);
395 while (req) {
Al Viroe13889b2011-07-25 14:15:50 -0400396 struct req *next = req->next;
Kay Sievers3c2670e2013-04-06 09:56:00 -0700397 req->err = handle(req->name, req->mode,
398 req->uid, req->gid, req->dev);
Al Viro2780f1f2011-06-27 16:25:29 -0400399 complete(&req->done);
Al Viroe13889b2011-07-25 14:15:50 -0400400 req = next;
Al Viro2780f1f2011-06-27 16:25:29 -0400401 }
402 spin_lock(&req_lock);
403 }
Kautuk Consul65e67572011-11-15 14:52:34 -0800404 __set_current_state(TASK_INTERRUPTIBLE);
Al Viro2780f1f2011-06-27 16:25:29 -0400405 spin_unlock(&req_lock);
406 schedule();
Al Viro2780f1f2011-06-27 16:25:29 -0400407 }
408 return 0;
409out:
410 complete(&setup_done);
411 return *err;
412}
413
Kay Sievers2b2af542009-04-30 15:23:42 +0200414/*
415 * Create devtmpfs instance, driver-core devices will add their device
416 * nodes here.
417 */
418int __init devtmpfs_init(void)
419{
Al Viro2780f1f2011-06-27 16:25:29 -0400420 int err = register_filesystem(&dev_fs_type);
Kay Sievers2b2af542009-04-30 15:23:42 +0200421 if (err) {
422 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
423 "type %i\n", err);
424 return err;
425 }
426
Al Viro2780f1f2011-06-27 16:25:29 -0400427 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
428 if (!IS_ERR(thread)) {
429 wait_for_completion(&setup_done);
430 } else {
431 err = PTR_ERR(thread);
432 thread = NULL;
433 }
434
435 if (err) {
Kay Sievers2b2af542009-04-30 15:23:42 +0200436 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
437 unregister_filesystem(&dev_fs_type);
438 return err;
439 }
Kay Sievers2b2af542009-04-30 15:23:42 +0200440
441 printk(KERN_INFO "devtmpfs: initialized\n");
442 return 0;
443}