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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 "base.h"
29
30static struct task_struct *thread;
31
32#if defined CONFIG_DEVTMPFS_MOUNT
33static int mount_dev = 1;
34#else
35static int mount_dev;
36#endif
37
38static DEFINE_SPINLOCK(req_lock);
39
40static struct req {
41 struct req *next;
42 struct completion done;
43 int err;
44 const char *name;
45 umode_t mode;
46 kuid_t uid;
47 kgid_t gid;
48 struct device *dev;
49} *requests;
50
51static int __init mount_param(char *str)
52{
53 mount_dev = simple_strtoul(str, NULL, 0);
54 return 1;
55}
56__setup("devtmpfs.mount=", mount_param);
57
58static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,
59 const char *dev_name, void *data)
60{
61#ifdef CONFIG_TMPFS
62 return mount_single(fs_type, flags, data, shmem_fill_super);
63#else
64 return mount_single(fs_type, flags, data, ramfs_fill_super);
65#endif
66}
67
68static struct file_system_type dev_fs_type = {
69 .name = "devtmpfs",
70 .mount = dev_mount,
71 .kill_sb = kill_litter_super,
72};
73
74#ifdef CONFIG_BLOCK
75static inline int is_blockdev(struct device *dev)
76{
77 return dev->class == &block_class;
78}
79#else
80static inline int is_blockdev(struct device *dev) { return 0; }
81#endif
82
83int devtmpfs_create_node(struct device *dev)
84{
85 const char *tmp = NULL;
86 struct req req;
87
88 if (!thread)
89 return 0;
90
91 req.mode = 0;
92 req.uid = GLOBAL_ROOT_UID;
93 req.gid = GLOBAL_ROOT_GID;
94 req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
95 if (!req.name)
96 return -ENOMEM;
97
98 if (req.mode == 0)
99 req.mode = 0600;
100 if (is_blockdev(dev))
101 req.mode |= S_IFBLK;
102 else
103 req.mode |= S_IFCHR;
104
105 req.dev = dev;
106
107 init_completion(&req.done);
108
109 spin_lock(&req_lock);
110 req.next = requests;
111 requests = &req;
112 spin_unlock(&req_lock);
113
114 wake_up_process(thread);
115 wait_for_completion(&req.done);
116
117 kfree(tmp);
118
119 return req.err;
120}
121
122int devtmpfs_delete_node(struct device *dev)
123{
124 const char *tmp = NULL;
125 struct req req;
126
127 if (!thread)
128 return 0;
129
130 req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
131 if (!req.name)
132 return -ENOMEM;
133
134 req.mode = 0;
135 req.dev = dev;
136
137 init_completion(&req.done);
138
139 spin_lock(&req_lock);
140 req.next = requests;
141 requests = &req;
142 spin_unlock(&req_lock);
143
144 wake_up_process(thread);
145 wait_for_completion(&req.done);
146
147 kfree(tmp);
148 return req.err;
149}
150
151static int dev_mkdir(const char *name, umode_t mode)
152{
153 struct dentry *dentry;
154 struct path path;
155 int err;
156
157 dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
158 if (IS_ERR(dentry))
159 return PTR_ERR(dentry);
160
161 err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
162 if (!err)
163
164 d_inode(dentry)->i_private = &thread;
165 done_path_create(&path, dentry);
166 return err;
167}
168
169static int create_path(const char *nodepath)
170{
171 char *path;
172 char *s;
173 int err = 0;
174
175
176 path = kstrdup(nodepath, GFP_KERNEL);
177 if (!path)
178 return -ENOMEM;
179
180 s = path;
181 for (;;) {
182 s = strchr(s, '/');
183 if (!s)
184 break;
185 s[0] = '\0';
186 err = dev_mkdir(path, 0755);
187 if (err && err != -EEXIST)
188 break;
189 s[0] = '/';
190 s++;
191 }
192 kfree(path);
193 return err;
194}
195
196static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
197 kgid_t gid, struct device *dev)
198{
199 struct dentry *dentry;
200 struct path path;
201 int err;
202
203 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
204 if (dentry == ERR_PTR(-ENOENT)) {
205 create_path(nodename);
206 dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
207 }
208 if (IS_ERR(dentry))
209 return PTR_ERR(dentry);
210
211 err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
212 if (!err) {
213 struct iattr newattrs;
214
215 newattrs.ia_mode = mode;
216 newattrs.ia_uid = uid;
217 newattrs.ia_gid = gid;
218 newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
219 inode_lock(d_inode(dentry));
220 notify_change(dentry, &newattrs, NULL);
221 inode_unlock(d_inode(dentry));
222
223
224 d_inode(dentry)->i_private = &thread;
225 }
226 done_path_create(&path, dentry);
227 return err;
228}
229
230static int dev_rmdir(const char *name)
231{
232 struct path parent;
233 struct dentry *dentry;
234 int err;
235
236 dentry = kern_path_locked(name, &parent);
237 if (IS_ERR(dentry))
238 return PTR_ERR(dentry);
239 if (d_really_is_positive(dentry)) {
240 if (d_inode(dentry)->i_private == &thread)
241 err = vfs_rmdir(d_inode(parent.dentry), dentry);
242 else
243 err = -EPERM;
244 } else {
245 err = -ENOENT;
246 }
247 dput(dentry);
248 inode_unlock(d_inode(parent.dentry));
249 path_put(&parent);
250 return err;
251}
252
253static int delete_path(const char *nodepath)
254{
255 const char *path;
256 int err = 0;
257
258 path = kstrdup(nodepath, GFP_KERNEL);
259 if (!path)
260 return -ENOMEM;
261
262 for (;;) {
263 char *base;
264
265 base = strrchr(path, '/');
266 if (!base)
267 break;
268 base[0] = '\0';
269 err = dev_rmdir(path);
270 if (err)
271 break;
272 }
273
274 kfree(path);
275 return err;
276}
277
278static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
279{
280
281 if (inode->i_private != &thread)
282 return 0;
283
284
285 if (is_blockdev(dev)) {
286 if (!S_ISBLK(stat->mode))
287 return 0;
288 } else {
289 if (!S_ISCHR(stat->mode))
290 return 0;
291 }
292 if (stat->rdev != dev->devt)
293 return 0;
294
295
296 return 1;
297}
298
299static int handle_remove(const char *nodename, struct device *dev)
300{
301 struct path parent;
302 struct dentry *dentry;
303 int deleted = 0;
304 int err;
305
306 dentry = kern_path_locked(nodename, &parent);
307 if (IS_ERR(dentry))
308 return PTR_ERR(dentry);
309
310 if (d_really_is_positive(dentry)) {
311 struct kstat stat;
312 struct path p = {.mnt = parent.mnt, .dentry = dentry};
313 err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
314 AT_STATX_SYNC_AS_STAT);
315 if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
316 struct iattr newattrs;
317
318
319
320
321 newattrs.ia_uid = GLOBAL_ROOT_UID;
322 newattrs.ia_gid = GLOBAL_ROOT_GID;
323 newattrs.ia_mode = stat.mode & ~0777;
324 newattrs.ia_valid =
325 ATTR_UID|ATTR_GID|ATTR_MODE;
326 inode_lock(d_inode(dentry));
327 notify_change(dentry, &newattrs, NULL);
328 inode_unlock(d_inode(dentry));
329 err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
330 if (!err || err == -ENOENT)
331 deleted = 1;
332 }
333 } else {
334 err = -ENOENT;
335 }
336 dput(dentry);
337 inode_unlock(d_inode(parent.dentry));
338
339 path_put(&parent);
340 if (deleted && strchr(nodename, '/'))
341 delete_path(nodename);
342 return err;
343}
344
345
346
347
348
349int devtmpfs_mount(const char *mntdir)
350{
351 int err;
352
353 if (!mount_dev)
354 return 0;
355
356 if (!thread)
357 return 0;
358
359 err = ksys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT,
360 NULL);
361 if (err)
362 printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
363 else
364 printk(KERN_INFO "devtmpfs: mounted\n");
365 return err;
366}
367
368static DECLARE_COMPLETION(setup_done);
369
370static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
371 struct device *dev)
372{
373 if (mode)
374 return handle_create(name, mode, uid, gid, dev);
375 else
376 return handle_remove(name, dev);
377}
378
379static int devtmpfsd(void *p)
380{
381 char options[] = "mode=0755";
382 int *err = p;
383 *err = ksys_unshare(CLONE_NEWNS);
384 if (*err)
385 goto out;
386 *err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
387 if (*err)
388 goto out;
389 ksys_chdir("/..");
390 ksys_chroot(".");
391 complete(&setup_done);
392 while (1) {
393 spin_lock(&req_lock);
394 while (requests) {
395 struct req *req = requests;
396 requests = NULL;
397 spin_unlock(&req_lock);
398 while (req) {
399 struct req *next = req->next;
400 req->err = handle(req->name, req->mode,
401 req->uid, req->gid, req->dev);
402 complete(&req->done);
403 req = next;
404 }
405 spin_lock(&req_lock);
406 }
407 __set_current_state(TASK_INTERRUPTIBLE);
408 spin_unlock(&req_lock);
409 schedule();
410 }
411 return 0;
412out:
413 complete(&setup_done);
414 return *err;
415}
416
417
418
419
420
421int __init devtmpfs_init(void)
422{
423 int err = register_filesystem(&dev_fs_type);
424 if (err) {
425 printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
426 "type %i\n", err);
427 return err;
428 }
429
430 thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
431 if (!IS_ERR(thread)) {
432 wait_for_completion(&setup_done);
433 } else {
434 err = PTR_ERR(thread);
435 thread = NULL;
436 }
437
438 if (err) {
439 printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
440 unregister_filesystem(&dev_fs_type);
441 return err;
442 }
443
444 printk(KERN_INFO "devtmpfs: initialized\n");
445 return 0;
446}
447
