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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#define pr_fmt(fmt) "devtmpfs: " fmt
17
18#include <linux/kernel.h>
19#include <linux/syscalls.h>
20#include <linux/mount.h>
21#include <linux/device.h>
22#include <linux/blkdev.h>
23#include <linux/namei.h>
24#include <linux/fs.h>
25#include <linux/shmem_fs.h>
26#include <linux/ramfs.h>
27#include <linux/sched.h>
28#include <linux/slab.h>
29#include <linux/kthread.h>
30#include <linux/init_syscalls.h>
31#include <uapi/linux/mount.h>
32#include "base.h"
33
34#ifdef CONFIG_DEVTMPFS_SAFE
35#define DEVTMPFS_MFLAGS (MS_SILENT | MS_NOEXEC | MS_NOSUID)
36#else
37#define DEVTMPFS_MFLAGS (MS_SILENT)
38#endif
39
40static struct task_struct *thread;
41
42static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
43
44static DEFINE_SPINLOCK(req_lock);
45
46static struct req {
47 struct req *next;
48 struct completion done;
49 int err;
50 const char *name;
51 umode_t mode; /* 0 => delete */
52 kuid_t uid;
53 kgid_t gid;
54 struct device *dev;
55} *requests;
56
57static int __init mount_param(char *str)
58{
59 mount_dev = simple_strtoul(str, NULL, 0);
60 return 1;
61}
62__setup("devtmpfs.mount=", mount_param);
63
64static struct vfsmount *mnt;
65
66static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
67 const char *dev_name, void *data)
68{
69 struct super_block *s = mnt->mnt_sb;
70 int err;
71
72 atomic_inc(&s->s_active);
73 down_write(&s->s_umount);
74 err = reconfigure_single(s, flags, data);
75 if (err < 0) {
76 deactivate_locked_super(s);
77 return ERR_PTR(err);
78 }
79 return dget(s->s_root);
80}
81
82static struct file_system_type internal_fs_type = {
83 .name = "devtmpfs",
84#ifdef CONFIG_TMPFS
85 .init_fs_context = shmem_init_fs_context,
86#else
87 .init_fs_context = ramfs_init_fs_context,
88#endif
89 .kill_sb = kill_litter_super,
90};
91
92static struct file_system_type dev_fs_type = {
93 .name = "devtmpfs",
94 .mount = public_dev_mount,
95};
96
97static int devtmpfs_submit_req(struct req *req, const char *tmp)
98{
99 init_completion(&req->done);
100
101 spin_lock(&req_lock);
102 req->next = requests;
103 requests = req;
104 spin_unlock(&req_lock);
105
106 wake_up_process(thread);
107 wait_for_completion(&req->done);
108
109 kfree(tmp);
110
111 return req->err;
112}
113
114int devtmpfs_create_node(struct device *dev)
115{
116 const char *tmp = NULL;
117 struct req req;
118
119 if (!thread)
120 return 0;
121
122 req.mode = 0;
123 req.uid = GLOBAL_ROOT_UID;
124 req.gid = GLOBAL_ROOT_GID;
125 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
126 if (!req.name)
127 return -ENOMEM;
128
129 if (req.mode == 0)
130 req.mode = 0600;
131 if (is_blockdev(dev))
132 req.mode |= S_IFBLK;
133 else
134 req.mode |= S_IFCHR;
135
136 req.dev = dev;
137
138 return devtmpfs_submit_req(&req, tmp);
139}
140
141int devtmpfs_delete_node(struct device *dev)
142{
143 const char *tmp = NULL;
144 struct req req;
145
146 if (!thread)
147 return 0;
148
149 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
150 if (!req.name)
151 return -ENOMEM;
152
153 req.mode = 0;
154 req.dev = dev;
155
156 return devtmpfs_submit_req(&req, tmp);
157}
158
159static int dev_mkdir(const char *name, umode_t mode)
160{
161 struct dentry *dentry;
162 struct path path;
163 int err;
164
165 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
166 if (IS_ERR(dentry))
167 return PTR_ERR(dentry);
168
169 err = vfs_mkdir(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode);
170 if (!err)
171 /* mark as kernel-created inode */
172 d_inode(dentry)->i_private = &thread;
173 done_path_create(&path, dentry);
174 return err;
175}
176
177static int create_path(const char *nodepath)
178{
179 char *path;
180 char *s;
181 int err = 0;
182
183 /* parent directories do not exist, create them */
184 path = kstrdup(nodepath, GFP_KERNEL);
185 if (!path)
186 return -ENOMEM;
187
188 s = path;
189 for (;;) {
190 s = strchr(s, '/');
191 if (!s)
192 break;
193 s[0] = '\0';
194 err = dev_mkdir(path, 0755);
195 if (err && err != -EEXIST)
196 break;
197 s[0] = '/';
198 s++;
199 }
200 kfree(path);
201 return err;
202}
203
204static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
205 kgid_t gid, struct device *dev)
206{
207 struct dentry *dentry;
208 struct path path;
209 int err;
210
211 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
212 if (dentry == ERR_PTR(-ENOENT)) {
213 create_path(nodename);
214 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
215 }
216 if (IS_ERR(dentry))
217 return PTR_ERR(dentry);
218
219 err = vfs_mknod(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode,
220 dev->devt);
221 if (!err) {
222 struct iattr newattrs;
223
224 newattrs.ia_mode = mode;
225 newattrs.ia_uid = uid;
226 newattrs.ia_gid = gid;
227 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
228 inode_lock(d_inode(dentry));
229 notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
230 inode_unlock(d_inode(dentry));
231
232 /* mark as kernel-created inode */
233 d_inode(dentry)->i_private = &thread;
234 }
235 done_path_create(&path, dentry);
236 return err;
237}
238
239static int dev_rmdir(const char *name)
240{
241 struct path parent;
242 struct dentry *dentry;
243 int err;
244
245 dentry = kern_path_locked(name, &parent);
246 if (IS_ERR(dentry))
247 return PTR_ERR(dentry);
248 if (d_really_is_positive(dentry)) {
249 if (d_inode(dentry)->i_private == &thread)
250 err = vfs_rmdir(&nop_mnt_idmap, d_inode(parent.dentry),
251 dentry);
252 else
253 err = -EPERM;
254 } else {
255 err = -ENOENT;
256 }
257 dput(dentry);
258 inode_unlock(d_inode(parent.dentry));
259 path_put(&parent);
260 return err;
261}
262
263static int delete_path(const char *nodepath)
264{
265 char *path;
266 int err = 0;
267
268 path = kstrdup(nodepath, GFP_KERNEL);
269 if (!path)
270 return -ENOMEM;
271
272 for (;;) {
273 char *base;
274
275 base = strrchr(path, '/');
276 if (!base)
277 break;
278 base[0] = '\0';
279 err = dev_rmdir(path);
280 if (err)
281 break;
282 }
283
284 kfree(path);
285 return err;
286}
287
288static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
289{
290 /* did we create it */
291 if (inode->i_private != &thread)
292 return 0;
293
294 /* does the dev_t match */
295 if (is_blockdev(dev)) {
296 if (!S_ISBLK(stat->mode))
297 return 0;
298 } else {
299 if (!S_ISCHR(stat->mode))
300 return 0;
301 }
302 if (stat->rdev != dev->devt)
303 return 0;
304
305 /* ours */
306 return 1;
307}
308
309static int handle_remove(const char *nodename, struct device *dev)
310{
311 struct path parent;
312 struct dentry *dentry;
313 int deleted = 0;
314 int err;
315
316 dentry = kern_path_locked(nodename, &parent);
317 if (IS_ERR(dentry))
318 return PTR_ERR(dentry);
319
320 if (d_really_is_positive(dentry)) {
321 struct kstat stat;
322 struct path p = {.mnt = parent.mnt, .dentry = dentry};
323 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
324 AT_STATX_SYNC_AS_STAT);
325 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
326 struct iattr newattrs;
327 /*
328 * before unlinking this node, reset permissions
329 * of possible references like hardlinks
330 */
331 newattrs.ia_uid = GLOBAL_ROOT_UID;
332 newattrs.ia_gid = GLOBAL_ROOT_GID;
333 newattrs.ia_mode = stat.mode & ~0777;
334 newattrs.ia_valid =
335 ATTR_UID|ATTR_GID|ATTR_MODE;
336 inode_lock(d_inode(dentry));
337 notify_change(&nop_mnt_idmap, dentry, &newattrs, NULL);
338 inode_unlock(d_inode(dentry));
339 err = vfs_unlink(&nop_mnt_idmap, d_inode(parent.dentry),
340 dentry, NULL);
341 if (!err || err == -ENOENT)
342 deleted = 1;
343 }
344 } else {
345 err = -ENOENT;
346 }
347 dput(dentry);
348 inode_unlock(d_inode(parent.dentry));
349
350 path_put(&parent);
351 if (deleted && strchr(nodename, '/'))
352 delete_path(nodename);
353 return err;
354}
355
356/*
357 * If configured, or requested by the commandline, devtmpfs will be
358 * auto-mounted after the kernel mounted the root filesystem.
359 */
360int __init devtmpfs_mount(void)
361{
362 int err;
363
364 if (!mount_dev)
365 return 0;
366
367 if (!thread)
368 return 0;
369
370 err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
371 if (err)
372 pr_info("error mounting %d\n", err);
373 else
374 pr_info("mounted\n");
375 return err;
376}
377
378static __initdata DECLARE_COMPLETION(setup_done);
379
380static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
381 struct device *dev)
382{
383 if (mode)
384 return handle_create(name, mode, uid, gid, dev);
385 else
386 return handle_remove(name, dev);
387}
388
389static void __noreturn devtmpfs_work_loop(void)
390{
391 while (1) {
392 spin_lock(&req_lock);
393 while (requests) {
394 struct req *req = requests;
395 requests = NULL;
396 spin_unlock(&req_lock);
397 while (req) {
398 struct req *next = req->next;
399 req->err = handle(req->name, req->mode,
400 req->uid, req->gid, req->dev);
401 complete(&req->done);
402 req = next;
403 }
404 spin_lock(&req_lock);
405 }
406 __set_current_state(TASK_INTERRUPTIBLE);
407 spin_unlock(&req_lock);
408 schedule();
409 }
410}
411
412static noinline int __init devtmpfs_setup(void *p)
413{
414 int err;
415
416 err = ksys_unshare(CLONE_NEWNS);
417 if (err)
418 goto out;
419 err = init_mount("devtmpfs", "/", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
420 if (err)
421 goto out;
422 init_chdir("/.."); /* will traverse into overmounted root */
423 init_chroot(".");
424out:
425 *(int *)p = err;
426 return err;
427}
428
429/*
430 * The __ref is because devtmpfs_setup needs to be __init for the routines it
431 * calls. That call is done while devtmpfs_init, which is marked __init,
432 * synchronously waits for it to complete.
433 */
434static int __ref devtmpfsd(void *p)
435{
436 int err = devtmpfs_setup(p);
437
438 complete(&setup_done);
439 if (err)
440 return err;
441 devtmpfs_work_loop();
442 return 0;
443}
444
445/*
446 * Create devtmpfs instance, driver-core devices will add their device
447 * nodes here.
448 */
449int __init devtmpfs_init(void)
450{
451 char opts[] = "mode=0755";
452 int err;
453
454 mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
455 if (IS_ERR(mnt)) {
456 pr_err("unable to create devtmpfs %ld\n", PTR_ERR(mnt));
457 return PTR_ERR(mnt);
458 }
459 err = register_filesystem(&dev_fs_type);
460 if (err) {
461 pr_err("unable to register devtmpfs type %d\n", err);
462 return err;
463 }
464
465 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
466 if (!IS_ERR(thread)) {
467 wait_for_completion(&setup_done);
468 } else {
469 err = PTR_ERR(thread);
470 thread = NULL;
471 }
472
473 if (err) {
474 pr_err("unable to create devtmpfs %d\n", err);
475 unregister_filesystem(&dev_fs_type);
476 thread = NULL;
477 return err;
478 }
479
480 pr_info("initialized\n");
481 return 0;
482}
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/genhd.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 <uapi/linux/mount.h>
29#include "base.h"
30
31static struct task_struct *thread;
32
33#if defined CONFIG_DEVTMPFS_MOUNT
34static int mount_dev = 1;
35#else
36static int mount_dev;
37#endif
38
39static DEFINE_SPINLOCK(req_lock);
40
41static struct req {
42 struct req *next;
43 struct completion done;
44 int err;
45 const char *name;
46 umode_t mode; /* 0 => delete */
47 kuid_t uid;
48 kgid_t gid;
49 struct device *dev;
50} *requests;
51
52static int __init mount_param(char *str)
53{
54 mount_dev = simple_strtoul(str, NULL, 0);
55 return 1;
56}
57__setup("devtmpfs.mount=", mount_param);
58
59static struct vfsmount *mnt;
60
61static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
62 const char *dev_name, void *data)
63{
64 struct super_block *s = mnt->mnt_sb;
65 atomic_inc(&s->s_active);
66 down_write(&s->s_umount);
67 return dget(s->s_root);
68}
69
70static struct file_system_type internal_fs_type = {
71 .name = "devtmpfs",
72#ifdef CONFIG_TMPFS
73 .init_fs_context = shmem_init_fs_context,
74 .parameters = &shmem_fs_parameters,
75#else
76 .init_fs_context = ramfs_init_fs_context,
77 .parameters = &ramfs_fs_parameters,
78#endif
79 .kill_sb = kill_litter_super,
80};
81
82static struct file_system_type dev_fs_type = {
83 .name = "devtmpfs",
84 .mount = public_dev_mount,
85};
86
87#ifdef CONFIG_BLOCK
88static inline int is_blockdev(struct device *dev)
89{
90 return dev->class == &block_class;
91}
92#else
93static inline int is_blockdev(struct device *dev) { return 0; }
94#endif
95
96int devtmpfs_create_node(struct device *dev)
97{
98 const char *tmp = NULL;
99 struct req req;
100
101 if (!thread)
102 return 0;
103
104 req.mode = 0;
105 req.uid = GLOBAL_ROOT_UID;
106 req.gid = GLOBAL_ROOT_GID;
107 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
108 if (!req.name)
109 return -ENOMEM;
110
111 if (req.mode == 0)
112 req.mode = 0600;
113 if (is_blockdev(dev))
114 req.mode |= S_IFBLK;
115 else
116 req.mode |= S_IFCHR;
117
118 req.dev = dev;
119
120 init_completion(&req.done);
121
122 spin_lock(&req_lock);
123 req.next = requests;
124 requests = &req;
125 spin_unlock(&req_lock);
126
127 wake_up_process(thread);
128 wait_for_completion(&req.done);
129
130 kfree(tmp);
131
132 return req.err;
133}
134
135int devtmpfs_delete_node(struct device *dev)
136{
137 const char *tmp = NULL;
138 struct req req;
139
140 if (!thread)
141 return 0;
142
143 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
144 if (!req.name)
145 return -ENOMEM;
146
147 req.mode = 0;
148 req.dev = dev;
149
150 init_completion(&req.done);
151
152 spin_lock(&req_lock);
153 req.next = requests;
154 requests = &req;
155 spin_unlock(&req_lock);
156
157 wake_up_process(thread);
158 wait_for_completion(&req.done);
159
160 kfree(tmp);
161 return req.err;
162}
163
164static int dev_mkdir(const char *name, umode_t mode)
165{
166 struct dentry *dentry;
167 struct path path;
168 int err;
169
170 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
171 if (IS_ERR(dentry))
172 return PTR_ERR(dentry);
173
174 err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
175 if (!err)
176 /* mark as kernel-created inode */
177 d_inode(dentry)->i_private = &thread;
178 done_path_create(&path, dentry);
179 return err;
180}
181
182static int create_path(const char *nodepath)
183{
184 char *path;
185 char *s;
186 int err = 0;
187
188 /* parent directories do not exist, create them */
189 path = kstrdup(nodepath, GFP_KERNEL);
190 if (!path)
191 return -ENOMEM;
192
193 s = path;
194 for (;;) {
195 s = strchr(s, '/');
196 if (!s)
197 break;
198 s[0] = '\0';
199 err = dev_mkdir(path, 0755);
200 if (err && err != -EEXIST)
201 break;
202 s[0] = '/';
203 s++;
204 }
205 kfree(path);
206 return err;
207}
208
209static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
210 kgid_t gid, struct device *dev)
211{
212 struct dentry *dentry;
213 struct path path;
214 int err;
215
216 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
217 if (dentry == ERR_PTR(-ENOENT)) {
218 create_path(nodename);
219 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
220 }
221 if (IS_ERR(dentry))
222 return PTR_ERR(dentry);
223
224 err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
225 if (!err) {
226 struct iattr newattrs;
227
228 newattrs.ia_mode = mode;
229 newattrs.ia_uid = uid;
230 newattrs.ia_gid = gid;
231 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
232 inode_lock(d_inode(dentry));
233 notify_change(dentry, &newattrs, NULL);
234 inode_unlock(d_inode(dentry));
235
236 /* mark as kernel-created inode */
237 d_inode(dentry)->i_private = &thread;
238 }
239 done_path_create(&path, dentry);
240 return err;
241}
242
243static int dev_rmdir(const char *name)
244{
245 struct path parent;
246 struct dentry *dentry;
247 int err;
248
249 dentry = kern_path_locked(name, &parent);
250 if (IS_ERR(dentry))
251 return PTR_ERR(dentry);
252 if (d_really_is_positive(dentry)) {
253 if (d_inode(dentry)->i_private == &thread)
254 err = vfs_rmdir(d_inode(parent.dentry), dentry);
255 else
256 err = -EPERM;
257 } else {
258 err = -ENOENT;
259 }
260 dput(dentry);
261 inode_unlock(d_inode(parent.dentry));
262 path_put(&parent);
263 return err;
264}
265
266static int delete_path(const char *nodepath)
267{
268 char *path;
269 int err = 0;
270
271 path = kstrdup(nodepath, GFP_KERNEL);
272 if (!path)
273 return -ENOMEM;
274
275 for (;;) {
276 char *base;
277
278 base = strrchr(path, '/');
279 if (!base)
280 break;
281 base[0] = '\0';
282 err = dev_rmdir(path);
283 if (err)
284 break;
285 }
286
287 kfree(path);
288 return err;
289}
290
291static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
292{
293 /* did we create it */
294 if (inode->i_private != &thread)
295 return 0;
296
297 /* does the dev_t match */
298 if (is_blockdev(dev)) {
299 if (!S_ISBLK(stat->mode))
300 return 0;
301 } else {
302 if (!S_ISCHR(stat->mode))
303 return 0;
304 }
305 if (stat->rdev != dev->devt)
306 return 0;
307
308 /* ours */
309 return 1;
310}
311
312static int handle_remove(const char *nodename, struct device *dev)
313{
314 struct path parent;
315 struct dentry *dentry;
316 int deleted = 0;
317 int err;
318
319 dentry = kern_path_locked(nodename, &parent);
320 if (IS_ERR(dentry))
321 return PTR_ERR(dentry);
322
323 if (d_really_is_positive(dentry)) {
324 struct kstat stat;
325 struct path p = {.mnt = parent.mnt, .dentry = dentry};
326 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
327 AT_STATX_SYNC_AS_STAT);
328 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
329 struct iattr newattrs;
330 /*
331 * before unlinking this node, reset permissions
332 * of possible references like hardlinks
333 */
334 newattrs.ia_uid = GLOBAL_ROOT_UID;
335 newattrs.ia_gid = GLOBAL_ROOT_GID;
336 newattrs.ia_mode = stat.mode & ~0777;
337 newattrs.ia_valid =
338 ATTR_UID|ATTR_GID|ATTR_MODE;
339 inode_lock(d_inode(dentry));
340 notify_change(dentry, &newattrs, NULL);
341 inode_unlock(d_inode(dentry));
342 err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
343 if (!err || err == -ENOENT)
344 deleted = 1;
345 }
346 } else {
347 err = -ENOENT;
348 }
349 dput(dentry);
350 inode_unlock(d_inode(parent.dentry));
351
352 path_put(&parent);
353 if (deleted && strchr(nodename, '/'))
354 delete_path(nodename);
355 return err;
356}
357
358/*
359 * If configured, or requested by the commandline, devtmpfs will be
360 * auto-mounted after the kernel mounted the root filesystem.
361 */
362int devtmpfs_mount(const char *mntdir)
363{
364 int err;
365
366 if (!mount_dev)
367 return 0;
368
369 if (!thread)
370 return 0;
371
372 err = ksys_mount("devtmpfs", mntdir, "devtmpfs", MS_SILENT, NULL);
373 if (err)
374 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
375 else
376 printk(KERN_INFO "devtmpfs: mounted\n");
377 return err;
378}
379
380static DECLARE_COMPLETION(setup_done);
381
382static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
383 struct device *dev)
384{
385 if (mode)
386 return handle_create(name, mode, uid, gid, dev);
387 else
388 return handle_remove(name, dev);
389}
390
391static int devtmpfsd(void *p)
392{
393 int *err = p;
394 *err = ksys_unshare(CLONE_NEWNS);
395 if (*err)
396 goto out;
397 *err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
398 if (*err)
399 goto out;
400 ksys_chdir("/.."); /* will traverse into overmounted root */
401 ksys_chroot(".");
402 complete(&setup_done);
403 while (1) {
404 spin_lock(&req_lock);
405 while (requests) {
406 struct req *req = requests;
407 requests = NULL;
408 spin_unlock(&req_lock);
409 while (req) {
410 struct req *next = req->next;
411 req->err = handle(req->name, req->mode,
412 req->uid, req->gid, req->dev);
413 complete(&req->done);
414 req = next;
415 }
416 spin_lock(&req_lock);
417 }
418 __set_current_state(TASK_INTERRUPTIBLE);
419 spin_unlock(&req_lock);
420 schedule();
421 }
422 return 0;
423out:
424 complete(&setup_done);
425 return *err;
426}
427
428/*
429 * Create devtmpfs instance, driver-core devices will add their device
430 * nodes here.
431 */
432int __init devtmpfs_init(void)
433{
434 char opts[] = "mode=0755";
435 int err;
436
437 mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
438 if (IS_ERR(mnt)) {
439 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
440 PTR_ERR(mnt));
441 return PTR_ERR(mnt);
442 }
443 err = register_filesystem(&dev_fs_type);
444 if (err) {
445 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
446 "type %i\n", err);
447 return err;
448 }
449
450 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
451 if (!IS_ERR(thread)) {
452 wait_for_completion(&setup_done);
453 } else {
454 err = PTR_ERR(thread);
455 thread = NULL;
456 }
457
458 if (err) {
459 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
460 unregister_filesystem(&dev_fs_type);
461 return err;
462 }
463
464 printk(KERN_INFO "devtmpfs: initialized\n");
465 return 0;
466}