Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
2b2af54a KS |
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 | |
e454cea2 | 10 | * filesystem. |
02fbe5e6 PK |
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. | |
2b2af54a KS |
14 | */ |
15 | ||
16 | #include <linux/kernel.h> | |
17 | #include <linux/syscalls.h> | |
18 | #include <linux/mount.h> | |
19 | #include <linux/device.h> | |
322cbb50 | 20 | #include <linux/blkdev.h> |
2b2af54a KS |
21 | #include <linux/namei.h> |
22 | #include <linux/fs.h> | |
23 | #include <linux/shmem_fs.h> | |
da5e4ef7 | 24 | #include <linux/ramfs.h> |
e454cea2 | 25 | #include <linux/sched.h> |
5a0e3ad6 | 26 | #include <linux/slab.h> |
2780f1ff | 27 | #include <linux/kthread.h> |
c60166f0 | 28 | #include <linux/init_syscalls.h> |
e262e32d | 29 | #include <uapi/linux/mount.h> |
c3a30420 | 30 | #include "base.h" |
2b2af54a | 31 | |
28f0c335 KC |
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 | ||
2780f1ff | 38 | static struct task_struct *thread; |
2b2af54a | 39 | |
fad1db8a | 40 | static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT); |
2b2af54a | 41 | |
2780f1ff AV |
42 | static DEFINE_SPINLOCK(req_lock); |
43 | ||
44 | static struct req { | |
45 | struct req *next; | |
46 | struct completion done; | |
47 | int err; | |
48 | const char *name; | |
2c9ede55 | 49 | umode_t mode; /* 0 => delete */ |
4e4098a3 GKH |
50 | kuid_t uid; |
51 | kgid_t gid; | |
2780f1ff AV |
52 | struct device *dev; |
53 | } *requests; | |
ed413ae6 | 54 | |
2b2af54a KS |
55 | static int __init mount_param(char *str) |
56 | { | |
fc14f2fe | 57 | mount_dev = simple_strtoul(str, NULL, 0); |
2b2af54a KS |
58 | return 1; |
59 | } | |
60 | __setup("devtmpfs.mount=", mount_param); | |
61 | ||
d401727e AV |
62 | static struct vfsmount *mnt; |
63 | ||
64 | static 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; | |
a6097180 N |
68 | int err; |
69 | ||
d401727e AV |
70 | atomic_inc(&s->s_active); |
71 | down_write(&s->s_umount); | |
a6097180 N |
72 | err = reconfigure_single(s, flags, data); |
73 | if (err < 0) { | |
74 | deactivate_locked_super(s); | |
75 | return ERR_PTR(err); | |
76 | } | |
d401727e AV |
77 | return dget(s->s_root); |
78 | } | |
79 | ||
f3235626 DH |
80 | static struct file_system_type internal_fs_type = { |
81 | .name = "devtmpfs", | |
da5e4ef7 | 82 | #ifdef CONFIG_TMPFS |
f3235626 | 83 | .init_fs_context = shmem_init_fs_context, |
da5e4ef7 | 84 | #else |
f3235626 | 85 | .init_fs_context = ramfs_init_fs_context, |
da5e4ef7 | 86 | #endif |
2b2af54a KS |
87 | .kill_sb = kill_litter_super, |
88 | }; | |
89 | ||
d401727e AV |
90 | static struct file_system_type dev_fs_type = { |
91 | .name = "devtmpfs", | |
92 | .mount = public_dev_mount, | |
93 | }; | |
94 | ||
2b2af54a KS |
95 | #ifdef CONFIG_BLOCK |
96 | static inline int is_blockdev(struct device *dev) | |
97 | { | |
98 | return dev->class == &block_class; | |
99 | } | |
100 | #else | |
101 | static inline int is_blockdev(struct device *dev) { return 0; } | |
102 | #endif | |
103 | ||
72a9cc95 RV |
104 | static 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 | ||
2780f1ff AV |
121 | int 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; | |
4e4098a3 GKH |
130 | req.uid = GLOBAL_ROOT_UID; |
131 | req.gid = GLOBAL_ROOT_GID; | |
3c2670e6 | 132 | req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp); |
2780f1ff AV |
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 | ||
72a9cc95 | 145 | return devtmpfs_submit_req(&req, tmp); |
2780f1ff AV |
146 | } |
147 | ||
148 | int devtmpfs_delete_node(struct device *dev) | |
149 | { | |
150 | const char *tmp = NULL; | |
151 | struct req req; | |
152 | ||
153 | if (!thread) | |
154 | return 0; | |
155 | ||
3c2670e6 | 156 | req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp); |
2780f1ff AV |
157 | if (!req.name) |
158 | return -ENOMEM; | |
159 | ||
160 | req.mode = 0; | |
161 | req.dev = dev; | |
162 | ||
72a9cc95 | 163 | return devtmpfs_submit_req(&req, tmp); |
2780f1ff AV |
164 | } |
165 | ||
fbd48a69 | 166 | static int dev_mkdir(const char *name, umode_t mode) |
2b2af54a | 167 | { |
2b2af54a | 168 | struct dentry *dentry; |
69753a0f | 169 | struct path path; |
2b2af54a KS |
170 | int err; |
171 | ||
1ac12b4b | 172 | dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY); |
69753a0f AV |
173 | if (IS_ERR(dentry)) |
174 | return PTR_ERR(dentry); | |
175 | ||
6521f891 | 176 | err = vfs_mkdir(&init_user_ns, d_inode(path.dentry), dentry, mode); |
69753a0f AV |
177 | if (!err) |
178 | /* mark as kernel-created inode */ | |
75c3cfa8 | 179 | d_inode(dentry)->i_private = &thread; |
921a1650 | 180 | done_path_create(&path, dentry); |
2b2af54a KS |
181 | return err; |
182 | } | |
183 | ||
184 | static int create_path(const char *nodepath) | |
185 | { | |
5da4e689 AV |
186 | char *path; |
187 | char *s; | |
9d108d25 | 188 | int err = 0; |
2b2af54a | 189 | |
5da4e689 AV |
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++; | |
2b2af54a | 206 | } |
5da4e689 | 207 | kfree(path); |
2b2af54a KS |
208 | return err; |
209 | } | |
210 | ||
4e4098a3 GKH |
211 | static int handle_create(const char *nodename, umode_t mode, kuid_t uid, |
212 | kgid_t gid, struct device *dev) | |
2b2af54a | 213 | { |
2b2af54a | 214 | struct dentry *dentry; |
69753a0f | 215 | struct path path; |
2b2af54a KS |
216 | int err; |
217 | ||
69753a0f AV |
218 | dentry = kern_path_create(AT_FDCWD, nodename, &path, 0); |
219 | if (dentry == ERR_PTR(-ENOENT)) { | |
2b2af54a | 220 | create_path(nodename); |
69753a0f | 221 | dentry = kern_path_create(AT_FDCWD, nodename, &path, 0); |
2b2af54a | 222 | } |
69753a0f AV |
223 | if (IS_ERR(dentry)) |
224 | return PTR_ERR(dentry); | |
225 | ||
6521f891 CB |
226 | err = vfs_mknod(&init_user_ns, d_inode(path.dentry), dentry, mode, |
227 | dev->devt); | |
69753a0f AV |
228 | if (!err) { |
229 | struct iattr newattrs; | |
230 | ||
69753a0f | 231 | newattrs.ia_mode = mode; |
4e4098a3 GKH |
232 | newattrs.ia_uid = uid; |
233 | newattrs.ia_gid = gid; | |
3c2670e6 | 234 | newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID; |
5955102c | 235 | inode_lock(d_inode(dentry)); |
2f221d6f | 236 | notify_change(&init_user_ns, dentry, &newattrs, NULL); |
5955102c | 237 | inode_unlock(d_inode(dentry)); |
69753a0f AV |
238 | |
239 | /* mark as kernel-created inode */ | |
75c3cfa8 | 240 | d_inode(dentry)->i_private = &thread; |
2b2af54a | 241 | } |
921a1650 | 242 | done_path_create(&path, dentry); |
2b2af54a KS |
243 | return err; |
244 | } | |
245 | ||
246 | static int dev_rmdir(const char *name) | |
247 | { | |
79714f72 | 248 | struct path parent; |
2b2af54a KS |
249 | struct dentry *dentry; |
250 | int err; | |
251 | ||
79714f72 AV |
252 | dentry = kern_path_locked(name, &parent); |
253 | if (IS_ERR(dentry)) | |
254 | return PTR_ERR(dentry); | |
75c3cfa8 DH |
255 | if (d_really_is_positive(dentry)) { |
256 | if (d_inode(dentry)->i_private == &thread) | |
6521f891 CB |
257 | err = vfs_rmdir(&init_user_ns, d_inode(parent.dentry), |
258 | dentry); | |
79714f72 AV |
259 | else |
260 | err = -EPERM; | |
2b2af54a | 261 | } else { |
79714f72 | 262 | err = -ENOENT; |
2b2af54a | 263 | } |
79714f72 | 264 | dput(dentry); |
5955102c | 265 | inode_unlock(d_inode(parent.dentry)); |
79714f72 | 266 | path_put(&parent); |
2b2af54a KS |
267 | return err; |
268 | } | |
269 | ||
270 | static int delete_path(const char *nodepath) | |
271 | { | |
be6b1dfe | 272 | char *path; |
2b2af54a KS |
273 | int err = 0; |
274 | ||
275 | path = kstrdup(nodepath, GFP_KERNEL); | |
276 | if (!path) | |
277 | return -ENOMEM; | |
278 | ||
ed413ae6 | 279 | for (;;) { |
2b2af54a KS |
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 | ||
295 | static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat) | |
296 | { | |
297 | /* did we create it */ | |
2780f1ff | 298 | if (inode->i_private != &thread) |
2b2af54a KS |
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 | ||
2780f1ff | 316 | static int handle_remove(const char *nodename, struct device *dev) |
2b2af54a | 317 | { |
79714f72 | 318 | struct path parent; |
2b2af54a | 319 | struct dentry *dentry; |
fbde7c61 | 320 | int deleted = 0; |
2b2af54a KS |
321 | int err; |
322 | ||
79714f72 AV |
323 | dentry = kern_path_locked(nodename, &parent); |
324 | if (IS_ERR(dentry)) | |
325 | return PTR_ERR(dentry); | |
326 | ||
75c3cfa8 | 327 | if (d_really_is_positive(dentry)) { |
79714f72 | 328 | struct kstat stat; |
3dadecce | 329 | struct path p = {.mnt = parent.mnt, .dentry = dentry}; |
a528d35e DH |
330 | err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE, |
331 | AT_STATX_SYNC_AS_STAT); | |
75c3cfa8 | 332 | if (!err && dev_mynode(dev, d_inode(dentry), &stat)) { |
79714f72 AV |
333 | struct iattr newattrs; |
334 | /* | |
335 | * before unlinking this node, reset permissions | |
336 | * of possible references like hardlinks | |
337 | */ | |
91fa2cca EB |
338 | newattrs.ia_uid = GLOBAL_ROOT_UID; |
339 | newattrs.ia_gid = GLOBAL_ROOT_GID; | |
79714f72 AV |
340 | newattrs.ia_mode = stat.mode & ~0777; |
341 | newattrs.ia_valid = | |
342 | ATTR_UID|ATTR_GID|ATTR_MODE; | |
5955102c | 343 | inode_lock(d_inode(dentry)); |
2f221d6f | 344 | notify_change(&init_user_ns, dentry, &newattrs, NULL); |
5955102c | 345 | inode_unlock(d_inode(dentry)); |
6521f891 CB |
346 | err = vfs_unlink(&init_user_ns, d_inode(parent.dentry), |
347 | dentry, NULL); | |
79714f72 AV |
348 | if (!err || err == -ENOENT) |
349 | deleted = 1; | |
2b2af54a | 350 | } |
2b2af54a | 351 | } else { |
79714f72 | 352 | err = -ENOENT; |
2b2af54a | 353 | } |
79714f72 | 354 | dput(dentry); |
5955102c | 355 | inode_unlock(d_inode(parent.dentry)); |
2b2af54a | 356 | |
79714f72 | 357 | path_put(&parent); |
2b2af54a KS |
358 | if (deleted && strchr(nodename, '/')) |
359 | delete_path(nodename); | |
2b2af54a KS |
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 | */ | |
fad1db8a | 367 | int __init devtmpfs_mount(void) |
2b2af54a | 368 | { |
2b2af54a KS |
369 | int err; |
370 | ||
fc14f2fe | 371 | if (!mount_dev) |
2b2af54a KS |
372 | return 0; |
373 | ||
2780f1ff | 374 | if (!thread) |
2b2af54a KS |
375 | return 0; |
376 | ||
28f0c335 | 377 | err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL); |
2b2af54a KS |
378 | if (err) |
379 | printk(KERN_INFO "devtmpfs: error mounting %i\n", err); | |
380 | else | |
381 | printk(KERN_INFO "devtmpfs: mounted\n"); | |
2b2af54a KS |
382 | return err; |
383 | } | |
384 | ||
01085e24 | 385 | static __initdata DECLARE_COMPLETION(setup_done); |
2780f1ff | 386 | |
4e4098a3 | 387 | static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid, |
3c2670e6 | 388 | struct device *dev) |
2780f1ff AV |
389 | { |
390 | if (mode) | |
3c2670e6 | 391 | return handle_create(name, mode, uid, gid, dev); |
2780f1ff AV |
392 | else |
393 | return handle_remove(name, dev); | |
394 | } | |
395 | ||
bcbacc49 CH |
396 | static 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 | ||
01085e24 | 419 | static noinline int __init devtmpfs_setup(void *p) |
2780f1ff | 420 | { |
c9d6b287 RV |
421 | int err; |
422 | ||
423 | err = ksys_unshare(CLONE_NEWNS); | |
424 | if (err) | |
2780f1ff | 425 | goto out; |
28f0c335 | 426 | err = init_mount("devtmpfs", "/", "devtmpfs", DEVTMPFS_MFLAGS, NULL); |
c9d6b287 | 427 | if (err) |
2780f1ff | 428 | goto out; |
db63f1e3 | 429 | init_chdir("/.."); /* will traverse into overmounted root */ |
4b7ca501 | 430 | init_chroot("."); |
0ff0e95e RV |
431 | out: |
432 | *(int *)p = err; | |
0ff0e95e RV |
433 | return err; |
434 | } | |
435 | ||
bcbacc49 CH |
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 | */ | |
441 | static int __ref devtmpfsd(void *p) | |
0ff0e95e RV |
442 | { |
443 | int err = devtmpfs_setup(p); | |
444 | ||
38f087de | 445 | complete(&setup_done); |
0ff0e95e RV |
446 | if (err) |
447 | return err; | |
bcbacc49 | 448 | devtmpfs_work_loop(); |
2780f1ff | 449 | return 0; |
2780f1ff AV |
450 | } |
451 | ||
2b2af54a KS |
452 | /* |
453 | * Create devtmpfs instance, driver-core devices will add their device | |
454 | * nodes here. | |
455 | */ | |
456 | int __init devtmpfs_init(void) | |
457 | { | |
d401727e AV |
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); | |
2b2af54a KS |
468 | if (err) { |
469 | printk(KERN_ERR "devtmpfs: unable to register devtmpfs " | |
470 | "type %i\n", err); | |
471 | return err; | |
472 | } | |
473 | ||
2780f1ff AV |
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) { | |
2b2af54a KS |
483 | printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err); |
484 | unregister_filesystem(&dev_fs_type); | |
31c779f2 | 485 | thread = NULL; |
2b2af54a KS |
486 | return err; |
487 | } | |
2b2af54a KS |
488 | |
489 | printk(KERN_INFO "devtmpfs: initialized\n"); | |
490 | return 0; | |
491 | } |