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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;
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(d_inode(path.dentry), dentry, mode);
161 if (!err)
162
163 d_inode(dentry)->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
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(d_inode(path.dentry), 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 inode_lock(d_inode(dentry));
219 notify_change(dentry, &newattrs, NULL);
220 inode_unlock(d_inode(dentry));
221
222
223 d_inode(dentry)->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 (d_really_is_positive(dentry)) {
239 if (d_inode(dentry)->i_private == &thread)
240 err = vfs_rmdir(d_inode(parent.dentry), dentry);
241 else
242 err = -EPERM;
243 } else {
244 err = -ENOENT;
245 }
246 dput(dentry);
247 inode_unlock(d_inode(parent.dentry));
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
280 if (inode->i_private != &thread)
281 return 0;
282
283
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
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 (d_really_is_positive(dentry)) {
310 struct kstat stat;
311 struct path p = {.mnt = parent.mnt, .dentry = dentry};
312 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
313 AT_STATX_SYNC_AS_STAT);
314 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
315 struct iattr newattrs;
316
317
318
319
320 newattrs.ia_uid = GLOBAL_ROOT_UID;
321 newattrs.ia_gid = GLOBAL_ROOT_GID;
322 newattrs.ia_mode = stat.mode & ~0777;
323 newattrs.ia_valid =
324 ATTR_UID|ATTR_GID|ATTR_MODE;
325 inode_lock(d_inode(dentry));
326 notify_change(dentry, &newattrs, NULL);
327 inode_unlock(d_inode(dentry));
328 err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
329 if (!err || err == -ENOENT)
330 deleted = 1;
331 }
332 } else {
333 err = -ENOENT;
334 }
335 dput(dentry);
336 inode_unlock(d_inode(parent.dentry));
337
338 path_put(&parent);
339 if (deleted && strchr(nodename, '/'))
340 delete_path(nodename);
341 return err;
342}
343
344
345
346
347
348int devtmpfs_mount(const char *mntdir)
349{
350 int err;
351
352 if (!mount_dev)
353 return 0;
354
355 if (!thread)
356 return 0;
357
358 err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
359 if (err)
360 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
361 else
362 printk(KERN_INFO "devtmpfs: mounted\n");
363 return err;
364}
365
366static DECLARE_COMPLETION(setup_done);
367
368static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
369 struct device *dev)
370{
371 if (mode)
372 return handle_create(name, mode, uid, gid, dev);
373 else
374 return handle_remove(name, dev);
375}
376
377static int devtmpfsd(void *p)
378{
379 char options[] = "mode=0755";
380 int *err = p;
381 *err = sys_unshare(CLONE_NEWNS);
382 if (*err)
383 goto out;
384 *err = sys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
385 if (*err)
386 goto out;
387 sys_chdir("/..");
388 sys_chroot(".");
389 complete(&setup_done);
390 while (1) {
391 spin_lock(&req_lock);
392 while (requests) {
393 struct req *req = requests;
394 requests = NULL;
395 spin_unlock(&req_lock);
396 while (req) {
397 struct req *next = req->next;
398 req->err = handle(req->name, req->mode,
399 req->uid, req->gid, req->dev);
400 complete(&req->done);
401 req = next;
402 }
403 spin_lock(&req_lock);
404 }
405 __set_current_state(TASK_INTERRUPTIBLE);
406 spin_unlock(&req_lock);
407 schedule();
408 }
409 return 0;
410out:
411 complete(&setup_done);
412 return *err;
413}
414
415
416
417
418
419int __init devtmpfs_init(void)
420{
421 int err = register_filesystem(&dev_fs_type);
422 if (err) {
423 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
424 "type %i\n", err);
425 return err;
426 }
427
428 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
429 if (!IS_ERR(thread)) {
430 wait_for_completion(&setup_done);
431 } else {
432 err = PTR_ERR(thread);
433 thread = NULL;
434 }
435
436 if (err) {
437 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
438 unregister_filesystem(&dev_fs_type);
439 return err;
440 }
441
442 printk(KERN_INFO "devtmpfs: initialized\n");
443 return 0;
444}
445
