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1/*
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
9 * filesystem.
10 * 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.
13 */
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>
23#include <linux/ramfs.h>
24#include <linux/sched.h>
25#include <linux/slab.h>
26#include <linux/kthread.h>
27#include "base.h"
28
29static struct task_struct *thread;
30
31#if defined CONFIG_DEVTMPFS_MOUNT
32static int mount_dev = 1;
33#else
34static int mount_dev;
35#endif
36
37static DEFINE_SPINLOCK(req_lock);
38
39static struct req {
40 struct req *next;
41 struct completion done;
42 int err;
43 const char *name;
44 umode_t mode; /* 0 => delete */
45 kuid_t uid;
46 kgid_t gid;
47 struct device *dev;
48} *requests;
49
50static int __init mount_param(char *str)
51{
52 mount_dev = simple_strtoul(str, NULL, 0);
53 return 1;
54}
55__setup("devtmpfs.mount=", mount_param);
56
57static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,
58 const char *dev_name, void *data)
59{
60#ifdef CONFIG_TMPFS
61 return mount_single(fs_type, flags, data, shmem_fill_super);
62#else
63 return mount_single(fs_type, flags, data, ramfs_fill_super);
64#endif
65}
66
67static struct file_system_type dev_fs_type = {
68 .name = "devtmpfs",
69 .mount = dev_mount,
70 .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
82int 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;
91 req.uid = GLOBAL_ROOT_UID;
92 req.gid = GLOBAL_ROOT_GID;
93 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
94 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
129 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
130 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
150static int dev_mkdir(const char *name, umode_t mode)
151{
152 struct dentry *dentry;
153 struct path path;
154 int err;
155
156 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
157 if (IS_ERR(dentry))
158 return PTR_ERR(dentry);
159
160 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;
164 done_path_create(&path, dentry);
165 return err;
166}
167
168static int create_path(const char *nodepath)
169{
170 char *path;
171 char *s;
172 int err = 0;
173
174 /* parent directories do not exist, create them */
175 path = kstrdup(nodepath, GFP_KERNEL);
176 if (!path)
177 return -ENOMEM;
178
179 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++;
190 }
191 kfree(path);
192 return err;
193}
194
195static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
196 kgid_t gid, struct device *dev)
197{
198 struct dentry *dentry;
199 struct path path;
200 int err;
201
202 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
203 if (dentry == ERR_PTR(-ENOENT)) {
204 create_path(nodename);
205 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
206 }
207 if (IS_ERR(dentry))
208 return PTR_ERR(dentry);
209
210 err = vfs_mknod(path.dentry->d_inode, dentry, mode, dev->devt);
211 if (!err) {
212 struct iattr newattrs;
213
214 newattrs.ia_mode = mode;
215 newattrs.ia_uid = uid;
216 newattrs.ia_gid = gid;
217 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
218 mutex_lock(&dentry->d_inode->i_mutex);
219 notify_change(dentry, &newattrs, NULL);
220 mutex_unlock(&dentry->d_inode->i_mutex);
221
222 /* mark as kernel-created inode */
223 dentry->d_inode->i_private = &thread;
224 }
225 done_path_create(&path, dentry);
226 return err;
227}
228
229static int dev_rmdir(const char *name)
230{
231 struct path parent;
232 struct dentry *dentry;
233 int err;
234
235 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;
243 } else {
244 err = -ENOENT;
245 }
246 dput(dentry);
247 mutex_unlock(&parent.dentry->d_inode->i_mutex);
248 path_put(&parent);
249 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
261 for (;;) {
262 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 */
280 if (inode->i_private != &thread)
281 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
298static int handle_remove(const char *nodename, struct device *dev)
299{
300 struct path parent;
301 struct dentry *dentry;
302 int deleted = 0;
303 int err;
304
305 dentry = kern_path_locked(nodename, &parent);
306 if (IS_ERR(dentry))
307 return PTR_ERR(dentry);
308
309 if (dentry->d_inode) {
310 struct kstat stat;
311 struct path p = {.mnt = parent.mnt, .dentry = dentry};
312 err = vfs_getattr(&p, &stat);
313 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 */
319 newattrs.ia_uid = GLOBAL_ROOT_UID;
320 newattrs.ia_gid = GLOBAL_ROOT_GID;
321 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);
325 notify_change(dentry, &newattrs, NULL);
326 mutex_unlock(&dentry->d_inode->i_mutex);
327 err = vfs_unlink(parent.dentry->d_inode, dentry, NULL);
328 if (!err || err == -ENOENT)
329 deleted = 1;
330 }
331 } else {
332 err = -ENOENT;
333 }
334 dput(dentry);
335 mutex_unlock(&parent.dentry->d_inode->i_mutex);
336
337 path_put(&parent);
338 if (deleted && strchr(nodename, '/'))
339 delete_path(nodename);
340 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 */
347int devtmpfs_mount(const char *mntdir)
348{
349 int err;
350
351 if (!mount_dev)
352 return 0;
353
354 if (!thread)
355 return 0;
356
357 err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
358 if (err)
359 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
360 else
361 printk(KERN_INFO "devtmpfs: mounted\n");
362 return err;
363}
364
365static DECLARE_COMPLETION(setup_done);
366
367static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
368 struct device *dev)
369{
370 if (mode)
371 return handle_create(name, mode, uid, gid, dev);
372 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) {
396 struct req *next = req->next;
397 req->err = handle(req->name, req->mode,
398 req->uid, req->gid, req->dev);
399 complete(&req->done);
400 req = next;
401 }
402 spin_lock(&req_lock);
403 }
404 __set_current_state(TASK_INTERRUPTIBLE);
405 spin_unlock(&req_lock);
406 schedule();
407 }
408 return 0;
409out:
410 complete(&setup_done);
411 return *err;
412}
413
414/*
415 * Create devtmpfs instance, driver-core devices will add their device
416 * nodes here.
417 */
418int __init devtmpfs_init(void)
419{
420 int err = register_filesystem(&dev_fs_type);
421 if (err) {
422 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
423 "type %i\n", err);
424 return err;
425 }
426
427 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) {
436 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
437 unregister_filesystem(&dev_fs_type);
438 return err;
439 }
440
441 printk(KERN_INFO "devtmpfs: initialized\n");
442 return 0;
443}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * devtmpfs - kernel-maintained tmpfs-based /dev
4 *
5 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
6 *
7 * During bootup, before any driver core device is registered,
8 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
9 * device which requests a device node, will add a node in this
10 * filesystem.
11 * By default, all devices are named after the name of the device,
12 * owned by root and have a default mode of 0600. Subsystems can
13 * overwrite the default setting if needed.
14 */
15
16#include <linux/kernel.h>
17#include <linux/syscalls.h>
18#include <linux/mount.h>
19#include <linux/device.h>
20#include <linux/blkdev.h>
21#include <linux/namei.h>
22#include <linux/fs.h>
23#include <linux/shmem_fs.h>
24#include <linux/ramfs.h>
25#include <linux/sched.h>
26#include <linux/slab.h>
27#include <linux/kthread.h>
28#include <linux/init_syscalls.h>
29#include <uapi/linux/mount.h>
30#include "base.h"
31
32#ifdef CONFIG_DEVTMPFS_SAFE
33#define DEVTMPFS_MFLAGS (MS_SILENT | MS_NOEXEC | MS_NOSUID)
34#else
35#define DEVTMPFS_MFLAGS (MS_SILENT)
36#endif
37
38static struct task_struct *thread;
39
40static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
41
42static DEFINE_SPINLOCK(req_lock);
43
44static struct req {
45 struct req *next;
46 struct completion done;
47 int err;
48 const char *name;
49 umode_t mode; /* 0 => delete */
50 kuid_t uid;
51 kgid_t gid;
52 struct device *dev;
53} *requests;
54
55static int __init mount_param(char *str)
56{
57 mount_dev = simple_strtoul(str, NULL, 0);
58 return 1;
59}
60__setup("devtmpfs.mount=", mount_param);
61
62static struct vfsmount *mnt;
63
64static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
65 const char *dev_name, void *data)
66{
67 struct super_block *s = mnt->mnt_sb;
68 int err;
69
70 atomic_inc(&s->s_active);
71 down_write(&s->s_umount);
72 err = reconfigure_single(s, flags, data);
73 if (err < 0) {
74 deactivate_locked_super(s);
75 return ERR_PTR(err);
76 }
77 return dget(s->s_root);
78}
79
80static struct file_system_type internal_fs_type = {
81 .name = "devtmpfs",
82#ifdef CONFIG_TMPFS
83 .init_fs_context = shmem_init_fs_context,
84#else
85 .init_fs_context = ramfs_init_fs_context,
86#endif
87 .kill_sb = kill_litter_super,
88};
89
90static struct file_system_type dev_fs_type = {
91 .name = "devtmpfs",
92 .mount = public_dev_mount,
93};
94
95#ifdef CONFIG_BLOCK
96static inline int is_blockdev(struct device *dev)
97{
98 return dev->class == &block_class;
99}
100#else
101static inline int is_blockdev(struct device *dev) { return 0; }
102#endif
103
104static int devtmpfs_submit_req(struct req *req, const char *tmp)
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_create_node(struct device *dev)
122{
123 const char *tmp = NULL;
124 struct req req;
125
126 if (!thread)
127 return 0;
128
129 req.mode = 0;
130 req.uid = GLOBAL_ROOT_UID;
131 req.gid = GLOBAL_ROOT_GID;
132 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
133 if (!req.name)
134 return -ENOMEM;
135
136 if (req.mode == 0)
137 req.mode = 0600;
138 if (is_blockdev(dev))
139 req.mode |= S_IFBLK;
140 else
141 req.mode |= S_IFCHR;
142
143 req.dev = dev;
144
145 return devtmpfs_submit_req(&req, tmp);
146}
147
148int devtmpfs_delete_node(struct device *dev)
149{
150 const char *tmp = NULL;
151 struct req req;
152
153 if (!thread)
154 return 0;
155
156 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
157 if (!req.name)
158 return -ENOMEM;
159
160 req.mode = 0;
161 req.dev = dev;
162
163 return devtmpfs_submit_req(&req, tmp);
164}
165
166static int dev_mkdir(const char *name, umode_t mode)
167{
168 struct dentry *dentry;
169 struct path path;
170 int err;
171
172 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
173 if (IS_ERR(dentry))
174 return PTR_ERR(dentry);
175
176 err = vfs_mkdir(&init_user_ns, d_inode(path.dentry), dentry, mode);
177 if (!err)
178 /* mark as kernel-created inode */
179 d_inode(dentry)->i_private = &thread;
180 done_path_create(&path, dentry);
181 return err;
182}
183
184static int create_path(const char *nodepath)
185{
186 char *path;
187 char *s;
188 int err = 0;
189
190 /* parent directories do not exist, create them */
191 path = kstrdup(nodepath, GFP_KERNEL);
192 if (!path)
193 return -ENOMEM;
194
195 s = path;
196 for (;;) {
197 s = strchr(s, '/');
198 if (!s)
199 break;
200 s[0] = '\0';
201 err = dev_mkdir(path, 0755);
202 if (err && err != -EEXIST)
203 break;
204 s[0] = '/';
205 s++;
206 }
207 kfree(path);
208 return err;
209}
210
211static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
212 kgid_t gid, struct device *dev)
213{
214 struct dentry *dentry;
215 struct path path;
216 int err;
217
218 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
219 if (dentry == ERR_PTR(-ENOENT)) {
220 create_path(nodename);
221 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
222 }
223 if (IS_ERR(dentry))
224 return PTR_ERR(dentry);
225
226 err = vfs_mknod(&init_user_ns, d_inode(path.dentry), dentry, mode,
227 dev->devt);
228 if (!err) {
229 struct iattr newattrs;
230
231 newattrs.ia_mode = mode;
232 newattrs.ia_uid = uid;
233 newattrs.ia_gid = gid;
234 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
235 inode_lock(d_inode(dentry));
236 notify_change(&init_user_ns, dentry, &newattrs, NULL);
237 inode_unlock(d_inode(dentry));
238
239 /* mark as kernel-created inode */
240 d_inode(dentry)->i_private = &thread;
241 }
242 done_path_create(&path, dentry);
243 return err;
244}
245
246static int dev_rmdir(const char *name)
247{
248 struct path parent;
249 struct dentry *dentry;
250 int err;
251
252 dentry = kern_path_locked(name, &parent);
253 if (IS_ERR(dentry))
254 return PTR_ERR(dentry);
255 if (d_really_is_positive(dentry)) {
256 if (d_inode(dentry)->i_private == &thread)
257 err = vfs_rmdir(&init_user_ns, d_inode(parent.dentry),
258 dentry);
259 else
260 err = -EPERM;
261 } else {
262 err = -ENOENT;
263 }
264 dput(dentry);
265 inode_unlock(d_inode(parent.dentry));
266 path_put(&parent);
267 return err;
268}
269
270static int delete_path(const char *nodepath)
271{
272 char *path;
273 int err = 0;
274
275 path = kstrdup(nodepath, GFP_KERNEL);
276 if (!path)
277 return -ENOMEM;
278
279 for (;;) {
280 char *base;
281
282 base = strrchr(path, '/');
283 if (!base)
284 break;
285 base[0] = '\0';
286 err = dev_rmdir(path);
287 if (err)
288 break;
289 }
290
291 kfree(path);
292 return err;
293}
294
295static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
296{
297 /* did we create it */
298 if (inode->i_private != &thread)
299 return 0;
300
301 /* does the dev_t match */
302 if (is_blockdev(dev)) {
303 if (!S_ISBLK(stat->mode))
304 return 0;
305 } else {
306 if (!S_ISCHR(stat->mode))
307 return 0;
308 }
309 if (stat->rdev != dev->devt)
310 return 0;
311
312 /* ours */
313 return 1;
314}
315
316static int handle_remove(const char *nodename, struct device *dev)
317{
318 struct path parent;
319 struct dentry *dentry;
320 int deleted = 0;
321 int err;
322
323 dentry = kern_path_locked(nodename, &parent);
324 if (IS_ERR(dentry))
325 return PTR_ERR(dentry);
326
327 if (d_really_is_positive(dentry)) {
328 struct kstat stat;
329 struct path p = {.mnt = parent.mnt, .dentry = dentry};
330 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
331 AT_STATX_SYNC_AS_STAT);
332 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
333 struct iattr newattrs;
334 /*
335 * before unlinking this node, reset permissions
336 * of possible references like hardlinks
337 */
338 newattrs.ia_uid = GLOBAL_ROOT_UID;
339 newattrs.ia_gid = GLOBAL_ROOT_GID;
340 newattrs.ia_mode = stat.mode & ~0777;
341 newattrs.ia_valid =
342 ATTR_UID|ATTR_GID|ATTR_MODE;
343 inode_lock(d_inode(dentry));
344 notify_change(&init_user_ns, dentry, &newattrs, NULL);
345 inode_unlock(d_inode(dentry));
346 err = vfs_unlink(&init_user_ns, d_inode(parent.dentry),
347 dentry, NULL);
348 if (!err || err == -ENOENT)
349 deleted = 1;
350 }
351 } else {
352 err = -ENOENT;
353 }
354 dput(dentry);
355 inode_unlock(d_inode(parent.dentry));
356
357 path_put(&parent);
358 if (deleted && strchr(nodename, '/'))
359 delete_path(nodename);
360 return err;
361}
362
363/*
364 * If configured, or requested by the commandline, devtmpfs will be
365 * auto-mounted after the kernel mounted the root filesystem.
366 */
367int __init devtmpfs_mount(void)
368{
369 int err;
370
371 if (!mount_dev)
372 return 0;
373
374 if (!thread)
375 return 0;
376
377 err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
378 if (err)
379 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
380 else
381 printk(KERN_INFO "devtmpfs: mounted\n");
382 return err;
383}
384
385static __initdata DECLARE_COMPLETION(setup_done);
386
387static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
388 struct device *dev)
389{
390 if (mode)
391 return handle_create(name, mode, uid, gid, dev);
392 else
393 return handle_remove(name, dev);
394}
395
396static void __noreturn devtmpfs_work_loop(void)
397{
398 while (1) {
399 spin_lock(&req_lock);
400 while (requests) {
401 struct req *req = requests;
402 requests = NULL;
403 spin_unlock(&req_lock);
404 while (req) {
405 struct req *next = req->next;
406 req->err = handle(req->name, req->mode,
407 req->uid, req->gid, req->dev);
408 complete(&req->done);
409 req = next;
410 }
411 spin_lock(&req_lock);
412 }
413 __set_current_state(TASK_INTERRUPTIBLE);
414 spin_unlock(&req_lock);
415 schedule();
416 }
417}
418
419static noinline int __init devtmpfs_setup(void *p)
420{
421 int err;
422
423 err = ksys_unshare(CLONE_NEWNS);
424 if (err)
425 goto out;
426 err = init_mount("devtmpfs", "/", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
427 if (err)
428 goto out;
429 init_chdir("/.."); /* will traverse into overmounted root */
430 init_chroot(".");
431out:
432 *(int *)p = err;
433 return err;
434}
435
436/*
437 * The __ref is because devtmpfs_setup needs to be __init for the routines it
438 * calls. That call is done while devtmpfs_init, which is marked __init,
439 * synchronously waits for it to complete.
440 */
441static int __ref devtmpfsd(void *p)
442{
443 int err = devtmpfs_setup(p);
444
445 complete(&setup_done);
446 if (err)
447 return err;
448 devtmpfs_work_loop();
449 return 0;
450}
451
452/*
453 * Create devtmpfs instance, driver-core devices will add their device
454 * nodes here.
455 */
456int __init devtmpfs_init(void)
457{
458 char opts[] = "mode=0755";
459 int err;
460
461 mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
462 if (IS_ERR(mnt)) {
463 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
464 PTR_ERR(mnt));
465 return PTR_ERR(mnt);
466 }
467 err = register_filesystem(&dev_fs_type);
468 if (err) {
469 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
470 "type %i\n", err);
471 return err;
472 }
473
474 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
475 if (!IS_ERR(thread)) {
476 wait_for_completion(&setup_done);
477 } else {
478 err = PTR_ERR(thread);
479 thread = NULL;
480 }
481
482 if (err) {
483 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
484 unregister_filesystem(&dev_fs_type);
485 thread = NULL;
486 return err;
487 }
488
489 printk(KERN_INFO "devtmpfs: initialized\n");
490 return 0;
491}