blob: 7bd296cca041aaa7e62a3f923182ff7ac2adf5ef [file] [log] [blame]
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -07001/*
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>
Serge E. Hallyn29486df2008-04-29 01:00:14 -070012#include <linux/seq_file.h>
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070013
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
39struct dev_whitelist_item {
40 u32 major, minor;
41 short type;
42 short access;
43 struct list_head list;
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -070044 struct rcu_head rcu;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070045};
46
47struct dev_cgroup {
48 struct cgroup_subsys_state css;
49 struct list_head whitelist;
50 spinlock_t lock;
51};
52
Pavel Emelyanovb66862f2008-06-05 22:46:24 -070053static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
54{
55 return container_of(s, struct dev_cgroup, css);
56}
57
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070058static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup)
59{
Pavel Emelyanovb66862f2008-06-05 22:46:24 -070060 return css_to_devcgroup(cgroup_subsys_state(cgroup, devices_subsys_id));
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070061}
62
Paul Menagef92523e2008-07-25 01:47:03 -070063static 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
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070068struct cgroup_subsys devices_subsys;
69
70static 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 */
82static 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
99free_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 */
112static int dev_whitelist_add(struct dev_cgroup *dev_cgroup,
113 struct dev_whitelist_item *wh)
114{
Pavel Emelyanovd1ee2972008-06-05 22:46:28 -0700115 struct dev_whitelist_item *whcopy, *walk;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700116
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);
Pavel Emelyanovd1ee2972008-06-05 22:46:28 -0700123 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)
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700137 list_add_tail_rcu(&whcopy->list, &dev_cgroup->whitelist);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700138 spin_unlock(&dev_cgroup->lock);
139 return 0;
140}
141
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700142static 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
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700150/*
151 * called under cgroup_lock()
152 * since the list is visible to other tasks, we need the spinlock also
153 */
154static 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
170remove:
171 walk->access &= ~wh->access;
172 if (!walk->access) {
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700173 list_del_rcu(&walk->list);
174 call_rcu(&walk->rcu, whitelist_item_free);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700175 }
176 }
177 spin_unlock(&dev_cgroup->lock);
178}
179
180/*
181 * called from kernel/cgroup.c with cgroup_lock() held.
182 */
183static 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;
Li Zefan7759fc92008-07-25 01:47:08 -0700205 wh->access = ACC_MASK;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700206 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
221static 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
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700237#define DEVCG_LIST 3
238
Li Zefan17d213f2008-07-13 12:14:02 -0700239#define MAJMINLEN 13
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700240#define ACCLEN 4
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700241
242static void set_access(char *acc, short access)
243{
244 int idx = 0;
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700245 memset(acc, 0, ACCLEN);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700246 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
254static 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
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700265static void set_majmin(char *str, unsigned m)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700266{
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700267 if (m == ~0)
Li Zefan7759fc92008-07-25 01:47:08 -0700268 strcpy(str, "*");
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700269 else
Li Zefan7759fc92008-07-25 01:47:08 -0700270 sprintf(str, "%u", m);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700271}
272
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700273static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
274 struct seq_file *m)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700275{
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700276 struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700277 struct dev_whitelist_item *wh;
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700278 char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN];
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700279
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700280 rcu_read_lock();
281 list_for_each_entry_rcu(wh, &devcgroup->whitelist, list) {
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700282 set_access(acc, wh->access);
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700283 set_majmin(maj, wh->major);
284 set_majmin(min, wh->minor);
285 seq_printf(m, "%c %s:%s %s\n", type_to_char(wh->type),
286 maj, min, acc);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700287 }
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700288 rcu_read_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700289
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700290 return 0;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700291}
292
293/*
294 * may_access_whitelist:
295 * does the access granted to dev_cgroup c contain the access
296 * requested in whitelist item refwh.
297 * return 1 if yes, 0 if no.
298 * call with c->lock held
299 */
300static int may_access_whitelist(struct dev_cgroup *c,
301 struct dev_whitelist_item *refwh)
302{
303 struct dev_whitelist_item *whitem;
304
305 list_for_each_entry(whitem, &c->whitelist, list) {
306 if (whitem->type & DEV_ALL)
307 return 1;
308 if ((refwh->type & DEV_BLOCK) && !(whitem->type & DEV_BLOCK))
309 continue;
310 if ((refwh->type & DEV_CHAR) && !(whitem->type & DEV_CHAR))
311 continue;
312 if (whitem->major != ~0 && whitem->major != refwh->major)
313 continue;
314 if (whitem->minor != ~0 && whitem->minor != refwh->minor)
315 continue;
Li Zefanec229e82008-07-13 12:14:04 -0700316 if (refwh->access & (~whitem->access))
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700317 continue;
318 return 1;
319 }
320 return 0;
321}
322
323/*
324 * parent_has_perm:
325 * when adding a new allow rule to a device whitelist, the rule
326 * must be allowed in the parent device
327 */
Paul Menagef92523e2008-07-25 01:47:03 -0700328static int parent_has_perm(struct dev_cgroup *childcg,
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700329 struct dev_whitelist_item *wh)
330{
Paul Menagef92523e2008-07-25 01:47:03 -0700331 struct cgroup *pcg = childcg->css.cgroup->parent;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700332 struct dev_cgroup *parent;
333 int ret;
334
335 if (!pcg)
336 return 1;
337 parent = cgroup_to_devcgroup(pcg);
338 spin_lock(&parent->lock);
339 ret = may_access_whitelist(parent, wh);
340 spin_unlock(&parent->lock);
341 return ret;
342}
343
344/*
345 * Modify the whitelist using allow/deny rules.
346 * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD
347 * so we can give a container CAP_MKNOD to let it create devices but not
348 * modify the whitelist.
349 * It seems likely we'll want to add a CAP_CONTAINER capability to allow
350 * us to also grant CAP_SYS_ADMIN to containers without giving away the
351 * device whitelist controls, but for now we'll stick with CAP_SYS_ADMIN
352 *
353 * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting
354 * new access is only allowed if you're in the top-level cgroup, or your
355 * parent cgroup has the access you're asking for.
356 */
Paul Menagef92523e2008-07-25 01:47:03 -0700357static int devcgroup_update_access(struct dev_cgroup *devcgroup,
358 int filetype, const char *buffer)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700359{
Paul Menagef92523e2008-07-25 01:47:03 -0700360 struct dev_cgroup *cur_devcgroup;
361 const char *b;
Li Zefan7759fc92008-07-25 01:47:08 -0700362 char *endp;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700363 int retval = 0, count;
364 struct dev_whitelist_item wh;
365
366 if (!capable(CAP_SYS_ADMIN))
367 return -EPERM;
368
Paul Menagef92523e2008-07-25 01:47:03 -0700369 cur_devcgroup = task_devcgroup(current);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700370
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;
Li Zefand823f6b2008-07-04 10:00:07 -0700378 wh.major = ~0;
379 wh.minor = ~0;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700380 goto handle;
381 case 'b':
382 wh.type = DEV_BLOCK;
383 break;
384 case 'c':
385 wh.type = DEV_CHAR;
386 break;
387 default:
Paul Menagef92523e2008-07-25 01:47:03 -0700388 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700389 }
390 b++;
Paul Menagef92523e2008-07-25 01:47:03 -0700391 if (!isspace(*b))
392 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700393 b++;
394 if (*b == '*') {
395 wh.major = ~0;
396 b++;
397 } else if (isdigit(*b)) {
Li Zefan7759fc92008-07-25 01:47:08 -0700398 wh.major = simple_strtoul(b, &endp, 10);
399 b = endp;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700400 } else {
Paul Menagef92523e2008-07-25 01:47:03 -0700401 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700402 }
Paul Menagef92523e2008-07-25 01:47:03 -0700403 if (*b != ':')
404 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700405 b++;
406
407 /* read minor */
408 if (*b == '*') {
409 wh.minor = ~0;
410 b++;
411 } else if (isdigit(*b)) {
Li Zefan7759fc92008-07-25 01:47:08 -0700412 wh.minor = simple_strtoul(b, &endp, 10);
413 b = endp;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700414 } else {
Paul Menagef92523e2008-07-25 01:47:03 -0700415 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700416 }
Paul Menagef92523e2008-07-25 01:47:03 -0700417 if (!isspace(*b))
418 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700419 for (b++, count = 0; count < 3; count++, b++) {
420 switch (*b) {
421 case 'r':
422 wh.access |= ACC_READ;
423 break;
424 case 'w':
425 wh.access |= ACC_WRITE;
426 break;
427 case 'm':
428 wh.access |= ACC_MKNOD;
429 break;
430 case '\n':
431 case '\0':
432 count = 3;
433 break;
434 default:
Paul Menagef92523e2008-07-25 01:47:03 -0700435 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700436 }
437 }
438
439handle:
440 retval = 0;
441 switch (filetype) {
442 case DEVCG_ALLOW:
Paul Menagef92523e2008-07-25 01:47:03 -0700443 if (!parent_has_perm(devcgroup, &wh))
444 return -EPERM;
445 return dev_whitelist_add(devcgroup, &wh);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700446 case DEVCG_DENY:
447 dev_whitelist_rm(devcgroup, &wh);
448 break;
449 default:
Paul Menagef92523e2008-07-25 01:47:03 -0700450 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700451 }
Paul Menagef92523e2008-07-25 01:47:03 -0700452 return 0;
453}
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700454
Paul Menagef92523e2008-07-25 01:47:03 -0700455static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft,
456 const char *buffer)
457{
458 int retval;
459 if (!cgroup_lock_live_group(cgrp))
460 return -ENODEV;
461 retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp),
462 cft->private, buffer);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700463 cgroup_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700464 return retval;
465}
466
467static struct cftype dev_cgroup_files[] = {
468 {
469 .name = "allow",
Paul Menagef92523e2008-07-25 01:47:03 -0700470 .write_string = devcgroup_access_write,
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700471 .private = DEVCG_ALLOW,
472 },
473 {
474 .name = "deny",
Paul Menagef92523e2008-07-25 01:47:03 -0700475 .write_string = devcgroup_access_write,
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700476 .private = DEVCG_DENY,
477 },
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700478 {
479 .name = "list",
480 .read_seq_string = devcgroup_seq_read,
481 .private = DEVCG_LIST,
482 },
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700483};
484
485static int devcgroup_populate(struct cgroup_subsys *ss,
486 struct cgroup *cgroup)
487{
488 return cgroup_add_files(cgroup, ss, dev_cgroup_files,
489 ARRAY_SIZE(dev_cgroup_files));
490}
491
492struct cgroup_subsys devices_subsys = {
493 .name = "devices",
494 .can_attach = devcgroup_can_attach,
495 .create = devcgroup_create,
496 .destroy = devcgroup_destroy,
497 .populate = devcgroup_populate,
498 .subsys_id = devices_subsys_id,
499};
500
501int devcgroup_inode_permission(struct inode *inode, int mask)
502{
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700503 struct dev_cgroup *dev_cgroup;
504 struct dev_whitelist_item *wh;
505
506 dev_t device = inode->i_rdev;
507 if (!device)
508 return 0;
509 if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode))
510 return 0;
Pavel Emelyanovcc9cb212008-06-05 22:46:26 -0700511 dev_cgroup = css_to_devcgroup(task_subsys_state(current,
512 devices_subsys_id));
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700513 if (!dev_cgroup)
514 return 0;
515
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700516 rcu_read_lock();
517 list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) {
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700518 if (wh->type & DEV_ALL)
519 goto acc_check;
520 if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode))
521 continue;
522 if ((wh->type & DEV_CHAR) && !S_ISCHR(inode->i_mode))
523 continue;
524 if (wh->major != ~0 && wh->major != imajor(inode))
525 continue;
526 if (wh->minor != ~0 && wh->minor != iminor(inode))
527 continue;
528acc_check:
529 if ((mask & MAY_WRITE) && !(wh->access & ACC_WRITE))
530 continue;
531 if ((mask & MAY_READ) && !(wh->access & ACC_READ))
532 continue;
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700533 rcu_read_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700534 return 0;
535 }
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700536 rcu_read_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700537
538 return -EPERM;
539}
540
541int devcgroup_inode_mknod(int mode, dev_t dev)
542{
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700543 struct dev_cgroup *dev_cgroup;
544 struct dev_whitelist_item *wh;
545
Pavel Emelyanovcc9cb212008-06-05 22:46:26 -0700546 dev_cgroup = css_to_devcgroup(task_subsys_state(current,
547 devices_subsys_id));
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700548 if (!dev_cgroup)
549 return 0;
550
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700551 rcu_read_lock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700552 list_for_each_entry(wh, &dev_cgroup->whitelist, list) {
553 if (wh->type & DEV_ALL)
554 goto acc_check;
555 if ((wh->type & DEV_BLOCK) && !S_ISBLK(mode))
556 continue;
557 if ((wh->type & DEV_CHAR) && !S_ISCHR(mode))
558 continue;
559 if (wh->major != ~0 && wh->major != MAJOR(dev))
560 continue;
561 if (wh->minor != ~0 && wh->minor != MINOR(dev))
562 continue;
563acc_check:
564 if (!(wh->access & ACC_MKNOD))
565 continue;
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700566 rcu_read_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700567 return 0;
568 }
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700569 rcu_read_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700570 return -EPERM;
571}