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Commit | Line | Data |
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08ce5f16 SH |
1 | /* |
2 | * dev_cgroup.c - device cgroup subsystem | |
3 | * | |
4 | * Copyright 2007 IBM Corp | |
5 | */ | |
6 | ||
7 | #include <linux/device_cgroup.h> | |
8 | #include <linux/cgroup.h> | |
9 | #include <linux/ctype.h> | |
10 | #include <linux/list.h> | |
11 | #include <linux/uaccess.h> | |
29486df3 | 12 | #include <linux/seq_file.h> |
08ce5f16 SH |
13 | |
14 | #define ACC_MKNOD 1 | |
15 | #define ACC_READ 2 | |
16 | #define ACC_WRITE 4 | |
17 | #define ACC_MASK (ACC_MKNOD | ACC_READ | ACC_WRITE) | |
18 | ||
19 | #define DEV_BLOCK 1 | |
20 | #define DEV_CHAR 2 | |
21 | #define DEV_ALL 4 /* this represents all devices */ | |
22 | ||
23 | /* | |
24 | * whitelist locking rules: | |
25 | * cgroup_lock() cannot be taken under dev_cgroup->lock. | |
26 | * dev_cgroup->lock can be taken with or without cgroup_lock(). | |
27 | * | |
28 | * modifications always require cgroup_lock | |
29 | * modifications to a list which is visible require the | |
30 | * dev_cgroup->lock *and* cgroup_lock() | |
31 | * walking the list requires dev_cgroup->lock or cgroup_lock(). | |
32 | * | |
33 | * reasoning: dev_whitelist_copy() needs to kmalloc, so needs | |
34 | * a mutex, which the cgroup_lock() is. Since modifying | |
35 | * a visible list requires both locks, either lock can be | |
36 | * taken for walking the list. | |
37 | */ | |
38 | ||
39 | struct dev_whitelist_item { | |
40 | u32 major, minor; | |
41 | short type; | |
42 | short access; | |
43 | struct list_head list; | |
4efd1a1b | 44 | struct rcu_head rcu; |
08ce5f16 SH |
45 | }; |
46 | ||
47 | struct dev_cgroup { | |
48 | struct cgroup_subsys_state css; | |
49 | struct list_head whitelist; | |
50 | spinlock_t lock; | |
51 | }; | |
52 | ||
b66862f7 PE |
53 | static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s) |
54 | { | |
55 | return container_of(s, struct dev_cgroup, css); | |
56 | } | |
57 | ||
08ce5f16 SH |
58 | static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup) |
59 | { | |
b66862f7 | 60 | return css_to_devcgroup(cgroup_subsys_state(cgroup, devices_subsys_id)); |
08ce5f16 SH |
61 | } |
62 | ||
f92523e3 PM |
63 | static inline struct dev_cgroup *task_devcgroup(struct task_struct *task) |
64 | { | |
65 | return css_to_devcgroup(task_subsys_state(task, devices_subsys_id)); | |
66 | } | |
67 | ||
08ce5f16 SH |
68 | struct cgroup_subsys devices_subsys; |
69 | ||
70 | static int devcgroup_can_attach(struct cgroup_subsys *ss, | |
71 | struct cgroup *new_cgroup, struct task_struct *task) | |
72 | { | |
73 | if (current != task && !capable(CAP_SYS_ADMIN)) | |
74 | return -EPERM; | |
75 | ||
76 | return 0; | |
77 | } | |
78 | ||
79 | /* | |
80 | * called under cgroup_lock() | |
81 | */ | |
82 | static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig) | |
83 | { | |
84 | struct dev_whitelist_item *wh, *tmp, *new; | |
85 | ||
86 | list_for_each_entry(wh, orig, list) { | |
87 | new = kmalloc(sizeof(*wh), GFP_KERNEL); | |
88 | if (!new) | |
89 | goto free_and_exit; | |
90 | new->major = wh->major; | |
91 | new->minor = wh->minor; | |
92 | new->type = wh->type; | |
93 | new->access = wh->access; | |
94 | list_add_tail(&new->list, dest); | |
95 | } | |
96 | ||
97 | return 0; | |
98 | ||
99 | free_and_exit: | |
100 | list_for_each_entry_safe(wh, tmp, dest, list) { | |
101 | list_del(&wh->list); | |
102 | kfree(wh); | |
103 | } | |
104 | return -ENOMEM; | |
105 | } | |
106 | ||
107 | /* Stupid prototype - don't bother combining existing entries */ | |
108 | /* | |
109 | * called under cgroup_lock() | |
110 | * since the list is visible to other tasks, we need the spinlock also | |
111 | */ | |
112 | static int dev_whitelist_add(struct dev_cgroup *dev_cgroup, | |
113 | struct dev_whitelist_item *wh) | |
114 | { | |
d1ee2971 | 115 | struct dev_whitelist_item *whcopy, *walk; |
08ce5f16 SH |
116 | |
117 | whcopy = kmalloc(sizeof(*whcopy), GFP_KERNEL); | |
118 | if (!whcopy) | |
119 | return -ENOMEM; | |
120 | ||
121 | memcpy(whcopy, wh, sizeof(*whcopy)); | |
122 | spin_lock(&dev_cgroup->lock); | |
d1ee2971 PE |
123 | list_for_each_entry(walk, &dev_cgroup->whitelist, list) { |
124 | if (walk->type != wh->type) | |
125 | continue; | |
126 | if (walk->major != wh->major) | |
127 | continue; | |
128 | if (walk->minor != wh->minor) | |
129 | continue; | |
130 | ||
131 | walk->access |= wh->access; | |
132 | kfree(whcopy); | |
133 | whcopy = NULL; | |
134 | } | |
135 | ||
136 | if (whcopy != NULL) | |
4efd1a1b | 137 | list_add_tail_rcu(&whcopy->list, &dev_cgroup->whitelist); |
08ce5f16 SH |
138 | spin_unlock(&dev_cgroup->lock); |
139 | return 0; | |
140 | } | |
141 | ||
4efd1a1b PE |
142 | static void whitelist_item_free(struct rcu_head *rcu) |
143 | { | |
144 | struct dev_whitelist_item *item; | |
145 | ||
146 | item = container_of(rcu, struct dev_whitelist_item, rcu); | |
147 | kfree(item); | |
148 | } | |
149 | ||
08ce5f16 SH |
150 | /* |
151 | * called under cgroup_lock() | |
152 | * since the list is visible to other tasks, we need the spinlock also | |
153 | */ | |
154 | static void dev_whitelist_rm(struct dev_cgroup *dev_cgroup, | |
155 | struct dev_whitelist_item *wh) | |
156 | { | |
157 | struct dev_whitelist_item *walk, *tmp; | |
158 | ||
159 | spin_lock(&dev_cgroup->lock); | |
160 | list_for_each_entry_safe(walk, tmp, &dev_cgroup->whitelist, list) { | |
161 | if (walk->type == DEV_ALL) | |
162 | goto remove; | |
163 | if (walk->type != wh->type) | |
164 | continue; | |
165 | if (walk->major != ~0 && walk->major != wh->major) | |
166 | continue; | |
167 | if (walk->minor != ~0 && walk->minor != wh->minor) | |
168 | continue; | |
169 | ||
170 | remove: | |
171 | walk->access &= ~wh->access; | |
172 | if (!walk->access) { | |
4efd1a1b PE |
173 | list_del_rcu(&walk->list); |
174 | call_rcu(&walk->rcu, whitelist_item_free); | |
08ce5f16 SH |
175 | } |
176 | } | |
177 | spin_unlock(&dev_cgroup->lock); | |
178 | } | |
179 | ||
180 | /* | |
181 | * called from kernel/cgroup.c with cgroup_lock() held. | |
182 | */ | |
183 | static struct cgroup_subsys_state *devcgroup_create(struct cgroup_subsys *ss, | |
184 | struct cgroup *cgroup) | |
185 | { | |
186 | struct dev_cgroup *dev_cgroup, *parent_dev_cgroup; | |
187 | struct cgroup *parent_cgroup; | |
188 | int ret; | |
189 | ||
190 | dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL); | |
191 | if (!dev_cgroup) | |
192 | return ERR_PTR(-ENOMEM); | |
193 | INIT_LIST_HEAD(&dev_cgroup->whitelist); | |
194 | parent_cgroup = cgroup->parent; | |
195 | ||
196 | if (parent_cgroup == NULL) { | |
197 | struct dev_whitelist_item *wh; | |
198 | wh = kmalloc(sizeof(*wh), GFP_KERNEL); | |
199 | if (!wh) { | |
200 | kfree(dev_cgroup); | |
201 | return ERR_PTR(-ENOMEM); | |
202 | } | |
203 | wh->minor = wh->major = ~0; | |
204 | wh->type = DEV_ALL; | |
205 | wh->access = ACC_MKNOD | ACC_READ | ACC_WRITE; | |
206 | list_add(&wh->list, &dev_cgroup->whitelist); | |
207 | } else { | |
208 | parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup); | |
209 | ret = dev_whitelist_copy(&dev_cgroup->whitelist, | |
210 | &parent_dev_cgroup->whitelist); | |
211 | if (ret) { | |
212 | kfree(dev_cgroup); | |
213 | return ERR_PTR(ret); | |
214 | } | |
215 | } | |
216 | ||
217 | spin_lock_init(&dev_cgroup->lock); | |
218 | return &dev_cgroup->css; | |
219 | } | |
220 | ||
221 | static void devcgroup_destroy(struct cgroup_subsys *ss, | |
222 | struct cgroup *cgroup) | |
223 | { | |
224 | struct dev_cgroup *dev_cgroup; | |
225 | struct dev_whitelist_item *wh, *tmp; | |
226 | ||
227 | dev_cgroup = cgroup_to_devcgroup(cgroup); | |
228 | list_for_each_entry_safe(wh, tmp, &dev_cgroup->whitelist, list) { | |
229 | list_del(&wh->list); | |
230 | kfree(wh); | |
231 | } | |
232 | kfree(dev_cgroup); | |
233 | } | |
234 | ||
235 | #define DEVCG_ALLOW 1 | |
236 | #define DEVCG_DENY 2 | |
29486df3 SH |
237 | #define DEVCG_LIST 3 |
238 | ||
17d213f8 | 239 | #define MAJMINLEN 13 |
29486df3 | 240 | #define ACCLEN 4 |
08ce5f16 SH |
241 | |
242 | static void set_access(char *acc, short access) | |
243 | { | |
244 | int idx = 0; | |
29486df3 | 245 | memset(acc, 0, ACCLEN); |
08ce5f16 SH |
246 | if (access & ACC_READ) |
247 | acc[idx++] = 'r'; | |
248 | if (access & ACC_WRITE) | |
249 | acc[idx++] = 'w'; | |
250 | if (access & ACC_MKNOD) | |
251 | acc[idx++] = 'm'; | |
252 | } | |
253 | ||
254 | static char type_to_char(short type) | |
255 | { | |
256 | if (type == DEV_ALL) | |
257 | return 'a'; | |
258 | if (type == DEV_CHAR) | |
259 | return 'c'; | |
260 | if (type == DEV_BLOCK) | |
261 | return 'b'; | |
262 | return 'X'; | |
263 | } | |
264 | ||
29486df3 | 265 | static void set_majmin(char *str, unsigned m) |
08ce5f16 | 266 | { |
29486df3 | 267 | memset(str, 0, MAJMINLEN); |
08ce5f16 SH |
268 | if (m == ~0) |
269 | sprintf(str, "*"); | |
270 | else | |
17d213f8 | 271 | snprintf(str, MAJMINLEN, "%u", m); |
08ce5f16 SH |
272 | } |
273 | ||
29486df3 SH |
274 | static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft, |
275 | struct seq_file *m) | |
08ce5f16 | 276 | { |
29486df3 | 277 | struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup); |
08ce5f16 | 278 | struct dev_whitelist_item *wh; |
29486df3 | 279 | char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; |
08ce5f16 | 280 | |
4efd1a1b PE |
281 | rcu_read_lock(); |
282 | list_for_each_entry_rcu(wh, &devcgroup->whitelist, list) { | |
08ce5f16 | 283 | set_access(acc, wh->access); |
29486df3 SH |
284 | set_majmin(maj, wh->major); |
285 | set_majmin(min, wh->minor); | |
286 | seq_printf(m, "%c %s:%s %s\n", type_to_char(wh->type), | |
287 | maj, min, acc); | |
08ce5f16 | 288 | } |
4efd1a1b | 289 | rcu_read_unlock(); |
08ce5f16 | 290 | |
29486df3 | 291 | return 0; |
08ce5f16 SH |
292 | } |
293 | ||
294 | /* | |
295 | * may_access_whitelist: | |
296 | * does the access granted to dev_cgroup c contain the access | |
297 | * requested in whitelist item refwh. | |
298 | * return 1 if yes, 0 if no. | |
299 | * call with c->lock held | |
300 | */ | |
301 | static int may_access_whitelist(struct dev_cgroup *c, | |
302 | struct dev_whitelist_item *refwh) | |
303 | { | |
304 | struct dev_whitelist_item *whitem; | |
305 | ||
306 | list_for_each_entry(whitem, &c->whitelist, list) { | |
307 | if (whitem->type & DEV_ALL) | |
308 | return 1; | |
309 | if ((refwh->type & DEV_BLOCK) && !(whitem->type & DEV_BLOCK)) | |
310 | continue; | |
311 | if ((refwh->type & DEV_CHAR) && !(whitem->type & DEV_CHAR)) | |
312 | continue; | |
313 | if (whitem->major != ~0 && whitem->major != refwh->major) | |
314 | continue; | |
315 | if (whitem->minor != ~0 && whitem->minor != refwh->minor) | |
316 | continue; | |
ec229e83 | 317 | if (refwh->access & (~whitem->access)) |
08ce5f16 SH |
318 | continue; |
319 | return 1; | |
320 | } | |
321 | return 0; | |
322 | } | |
323 | ||
324 | /* | |
325 | * parent_has_perm: | |
326 | * when adding a new allow rule to a device whitelist, the rule | |
327 | * must be allowed in the parent device | |
328 | */ | |
f92523e3 | 329 | static int parent_has_perm(struct dev_cgroup *childcg, |
08ce5f16 SH |
330 | struct dev_whitelist_item *wh) |
331 | { | |
f92523e3 | 332 | struct cgroup *pcg = childcg->css.cgroup->parent; |
08ce5f16 SH |
333 | struct dev_cgroup *parent; |
334 | int ret; | |
335 | ||
336 | if (!pcg) | |
337 | return 1; | |
338 | parent = cgroup_to_devcgroup(pcg); | |
339 | spin_lock(&parent->lock); | |
340 | ret = may_access_whitelist(parent, wh); | |
341 | spin_unlock(&parent->lock); | |
342 | return ret; | |
343 | } | |
344 | ||
345 | /* | |
346 | * Modify the whitelist using allow/deny rules. | |
347 | * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD | |
348 | * so we can give a container CAP_MKNOD to let it create devices but not | |
349 | * modify the whitelist. | |
350 | * It seems likely we'll want to add a CAP_CONTAINER capability to allow | |
351 | * us to also grant CAP_SYS_ADMIN to containers without giving away the | |
352 | * device whitelist controls, but for now we'll stick with CAP_SYS_ADMIN | |
353 | * | |
354 | * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting | |
355 | * new access is only allowed if you're in the top-level cgroup, or your | |
356 | * parent cgroup has the access you're asking for. | |
357 | */ | |
f92523e3 PM |
358 | static int devcgroup_update_access(struct dev_cgroup *devcgroup, |
359 | int filetype, const char *buffer) | |
08ce5f16 | 360 | { |
f92523e3 PM |
361 | struct dev_cgroup *cur_devcgroup; |
362 | const char *b; | |
08ce5f16 SH |
363 | int retval = 0, count; |
364 | struct dev_whitelist_item wh; | |
365 | ||
366 | if (!capable(CAP_SYS_ADMIN)) | |
367 | return -EPERM; | |
368 | ||
f92523e3 | 369 | cur_devcgroup = task_devcgroup(current); |
08ce5f16 SH |
370 | |
371 | memset(&wh, 0, sizeof(wh)); | |
372 | b = buffer; | |
373 | ||
374 | switch (*b) { | |
375 | case 'a': | |
376 | wh.type = DEV_ALL; | |
377 | wh.access = ACC_MASK; | |
d823f6bf LZ |
378 | wh.major = ~0; |
379 | wh.minor = ~0; | |
08ce5f16 SH |
380 | goto handle; |
381 | case 'b': | |
382 | wh.type = DEV_BLOCK; | |
383 | break; | |
384 | case 'c': | |
385 | wh.type = DEV_CHAR; | |
386 | break; | |
387 | default: | |
f92523e3 | 388 | return -EINVAL; |
08ce5f16 SH |
389 | } |
390 | b++; | |
f92523e3 PM |
391 | if (!isspace(*b)) |
392 | return -EINVAL; | |
08ce5f16 SH |
393 | b++; |
394 | if (*b == '*') { | |
395 | wh.major = ~0; | |
396 | b++; | |
397 | } else if (isdigit(*b)) { | |
398 | wh.major = 0; | |
399 | while (isdigit(*b)) { | |
400 | wh.major = wh.major*10+(*b-'0'); | |
401 | b++; | |
402 | } | |
403 | } else { | |
f92523e3 | 404 | return -EINVAL; |
08ce5f16 | 405 | } |
f92523e3 PM |
406 | if (*b != ':') |
407 | return -EINVAL; | |
08ce5f16 SH |
408 | b++; |
409 | ||
410 | /* read minor */ | |
411 | if (*b == '*') { | |
412 | wh.minor = ~0; | |
413 | b++; | |
414 | } else if (isdigit(*b)) { | |
415 | wh.minor = 0; | |
416 | while (isdigit(*b)) { | |
417 | wh.minor = wh.minor*10+(*b-'0'); | |
418 | b++; | |
419 | } | |
420 | } else { | |
f92523e3 | 421 | return -EINVAL; |
08ce5f16 | 422 | } |
f92523e3 PM |
423 | if (!isspace(*b)) |
424 | return -EINVAL; | |
08ce5f16 SH |
425 | for (b++, count = 0; count < 3; count++, b++) { |
426 | switch (*b) { | |
427 | case 'r': | |
428 | wh.access |= ACC_READ; | |
429 | break; | |
430 | case 'w': | |
431 | wh.access |= ACC_WRITE; | |
432 | break; | |
433 | case 'm': | |
434 | wh.access |= ACC_MKNOD; | |
435 | break; | |
436 | case '\n': | |
437 | case '\0': | |
438 | count = 3; | |
439 | break; | |
440 | default: | |
f92523e3 | 441 | return -EINVAL; |
08ce5f16 SH |
442 | } |
443 | } | |
444 | ||
445 | handle: | |
446 | retval = 0; | |
447 | switch (filetype) { | |
448 | case DEVCG_ALLOW: | |
f92523e3 PM |
449 | if (!parent_has_perm(devcgroup, &wh)) |
450 | return -EPERM; | |
451 | return dev_whitelist_add(devcgroup, &wh); | |
08ce5f16 SH |
452 | case DEVCG_DENY: |
453 | dev_whitelist_rm(devcgroup, &wh); | |
454 | break; | |
455 | default: | |
f92523e3 | 456 | return -EINVAL; |
08ce5f16 | 457 | } |
f92523e3 PM |
458 | return 0; |
459 | } | |
08ce5f16 | 460 | |
f92523e3 PM |
461 | static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft, |
462 | const char *buffer) | |
463 | { | |
464 | int retval; | |
465 | if (!cgroup_lock_live_group(cgrp)) | |
466 | return -ENODEV; | |
467 | retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp), | |
468 | cft->private, buffer); | |
08ce5f16 | 469 | cgroup_unlock(); |
08ce5f16 SH |
470 | return retval; |
471 | } | |
472 | ||
473 | static struct cftype dev_cgroup_files[] = { | |
474 | { | |
475 | .name = "allow", | |
f92523e3 | 476 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
477 | .private = DEVCG_ALLOW, |
478 | }, | |
479 | { | |
480 | .name = "deny", | |
f92523e3 | 481 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
482 | .private = DEVCG_DENY, |
483 | }, | |
29486df3 SH |
484 | { |
485 | .name = "list", | |
486 | .read_seq_string = devcgroup_seq_read, | |
487 | .private = DEVCG_LIST, | |
488 | }, | |
08ce5f16 SH |
489 | }; |
490 | ||
491 | static int devcgroup_populate(struct cgroup_subsys *ss, | |
492 | struct cgroup *cgroup) | |
493 | { | |
494 | return cgroup_add_files(cgroup, ss, dev_cgroup_files, | |
495 | ARRAY_SIZE(dev_cgroup_files)); | |
496 | } | |
497 | ||
498 | struct cgroup_subsys devices_subsys = { | |
499 | .name = "devices", | |
500 | .can_attach = devcgroup_can_attach, | |
501 | .create = devcgroup_create, | |
502 | .destroy = devcgroup_destroy, | |
503 | .populate = devcgroup_populate, | |
504 | .subsys_id = devices_subsys_id, | |
505 | }; | |
506 | ||
507 | int devcgroup_inode_permission(struct inode *inode, int mask) | |
508 | { | |
08ce5f16 SH |
509 | struct dev_cgroup *dev_cgroup; |
510 | struct dev_whitelist_item *wh; | |
511 | ||
512 | dev_t device = inode->i_rdev; | |
513 | if (!device) | |
514 | return 0; | |
515 | if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) | |
516 | return 0; | |
cc9cb219 PE |
517 | dev_cgroup = css_to_devcgroup(task_subsys_state(current, |
518 | devices_subsys_id)); | |
08ce5f16 SH |
519 | if (!dev_cgroup) |
520 | return 0; | |
521 | ||
4efd1a1b PE |
522 | rcu_read_lock(); |
523 | list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) { | |
08ce5f16 SH |
524 | if (wh->type & DEV_ALL) |
525 | goto acc_check; | |
526 | if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode)) | |
527 | continue; | |
528 | if ((wh->type & DEV_CHAR) && !S_ISCHR(inode->i_mode)) | |
529 | continue; | |
530 | if (wh->major != ~0 && wh->major != imajor(inode)) | |
531 | continue; | |
532 | if (wh->minor != ~0 && wh->minor != iminor(inode)) | |
533 | continue; | |
534 | acc_check: | |
535 | if ((mask & MAY_WRITE) && !(wh->access & ACC_WRITE)) | |
536 | continue; | |
537 | if ((mask & MAY_READ) && !(wh->access & ACC_READ)) | |
538 | continue; | |
4efd1a1b | 539 | rcu_read_unlock(); |
08ce5f16 SH |
540 | return 0; |
541 | } | |
4efd1a1b | 542 | rcu_read_unlock(); |
08ce5f16 SH |
543 | |
544 | return -EPERM; | |
545 | } | |
546 | ||
547 | int devcgroup_inode_mknod(int mode, dev_t dev) | |
548 | { | |
08ce5f16 SH |
549 | struct dev_cgroup *dev_cgroup; |
550 | struct dev_whitelist_item *wh; | |
551 | ||
cc9cb219 PE |
552 | dev_cgroup = css_to_devcgroup(task_subsys_state(current, |
553 | devices_subsys_id)); | |
08ce5f16 SH |
554 | if (!dev_cgroup) |
555 | return 0; | |
556 | ||
4efd1a1b | 557 | rcu_read_lock(); |
08ce5f16 SH |
558 | list_for_each_entry(wh, &dev_cgroup->whitelist, list) { |
559 | if (wh->type & DEV_ALL) | |
560 | goto acc_check; | |
561 | if ((wh->type & DEV_BLOCK) && !S_ISBLK(mode)) | |
562 | continue; | |
563 | if ((wh->type & DEV_CHAR) && !S_ISCHR(mode)) | |
564 | continue; | |
565 | if (wh->major != ~0 && wh->major != MAJOR(dev)) | |
566 | continue; | |
567 | if (wh->minor != ~0 && wh->minor != MINOR(dev)) | |
568 | continue; | |
569 | acc_check: | |
570 | if (!(wh->access & ACC_MKNOD)) | |
571 | continue; | |
4efd1a1b | 572 | rcu_read_unlock(); |
08ce5f16 SH |
573 | return 0; |
574 | } | |
4efd1a1b | 575 | rcu_read_unlock(); |
08ce5f16 SH |
576 | return -EPERM; |
577 | } |