Commit | Line | Data |
---|---|---|
08ce5f16 | 1 | /* |
47c59803 | 2 | * device_cgroup.c - device cgroup subsystem |
08ce5f16 SH |
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> |
5a0e3ad6 | 13 | #include <linux/slab.h> |
47c59803 | 14 | #include <linux/rcupdate.h> |
b4046f00 | 15 | #include <linux/mutex.h> |
08ce5f16 SH |
16 | |
17 | #define ACC_MKNOD 1 | |
18 | #define ACC_READ 2 | |
19 | #define ACC_WRITE 4 | |
20 | #define ACC_MASK (ACC_MKNOD | ACC_READ | ACC_WRITE) | |
21 | ||
22 | #define DEV_BLOCK 1 | |
23 | #define DEV_CHAR 2 | |
24 | #define DEV_ALL 4 /* this represents all devices */ | |
25 | ||
b4046f00 LZ |
26 | static DEFINE_MUTEX(devcgroup_mutex); |
27 | ||
c39a2a30 AR |
28 | enum devcg_behavior { |
29 | DEVCG_DEFAULT_NONE, | |
30 | DEVCG_DEFAULT_ALLOW, | |
31 | DEVCG_DEFAULT_DENY, | |
32 | }; | |
33 | ||
08ce5f16 | 34 | /* |
db9aeca9 | 35 | * exception list locking rules: |
b4046f00 | 36 | * hold devcgroup_mutex for update/read. |
47c59803 | 37 | * hold rcu_read_lock() for read. |
08ce5f16 SH |
38 | */ |
39 | ||
db9aeca9 | 40 | struct dev_exception_item { |
08ce5f16 SH |
41 | u32 major, minor; |
42 | short type; | |
43 | short access; | |
44 | struct list_head list; | |
4efd1a1b | 45 | struct rcu_head rcu; |
08ce5f16 SH |
46 | }; |
47 | ||
48 | struct dev_cgroup { | |
49 | struct cgroup_subsys_state css; | |
db9aeca9 | 50 | struct list_head exceptions; |
c39a2a30 | 51 | enum devcg_behavior behavior; |
08ce5f16 SH |
52 | }; |
53 | ||
b66862f7 PE |
54 | static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s) |
55 | { | |
56 | return container_of(s, struct dev_cgroup, css); | |
57 | } | |
58 | ||
08ce5f16 SH |
59 | static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup) |
60 | { | |
b66862f7 | 61 | return css_to_devcgroup(cgroup_subsys_state(cgroup, devices_subsys_id)); |
08ce5f16 SH |
62 | } |
63 | ||
f92523e3 PM |
64 | static inline struct dev_cgroup *task_devcgroup(struct task_struct *task) |
65 | { | |
66 | return css_to_devcgroup(task_subsys_state(task, devices_subsys_id)); | |
67 | } | |
68 | ||
08ce5f16 SH |
69 | struct cgroup_subsys devices_subsys; |
70 | ||
761b3ef5 LZ |
71 | static int devcgroup_can_attach(struct cgroup *new_cgrp, |
72 | struct cgroup_taskset *set) | |
08ce5f16 | 73 | { |
2f7ee569 | 74 | struct task_struct *task = cgroup_taskset_first(set); |
08ce5f16 | 75 | |
2f7ee569 TH |
76 | if (current != task && !capable(CAP_SYS_ADMIN)) |
77 | return -EPERM; | |
08ce5f16 SH |
78 | return 0; |
79 | } | |
80 | ||
81 | /* | |
b4046f00 | 82 | * called under devcgroup_mutex |
08ce5f16 | 83 | */ |
db9aeca9 | 84 | static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig) |
08ce5f16 | 85 | { |
db9aeca9 | 86 | struct dev_exception_item *ex, *tmp, *new; |
08ce5f16 | 87 | |
4b1c7840 TH |
88 | lockdep_assert_held(&devcgroup_mutex); |
89 | ||
db9aeca9 AR |
90 | list_for_each_entry(ex, orig, list) { |
91 | new = kmemdup(ex, sizeof(*ex), GFP_KERNEL); | |
08ce5f16 SH |
92 | if (!new) |
93 | goto free_and_exit; | |
08ce5f16 SH |
94 | list_add_tail(&new->list, dest); |
95 | } | |
96 | ||
97 | return 0; | |
98 | ||
99 | free_and_exit: | |
db9aeca9 AR |
100 | list_for_each_entry_safe(ex, tmp, dest, list) { |
101 | list_del(&ex->list); | |
102 | kfree(ex); | |
08ce5f16 SH |
103 | } |
104 | return -ENOMEM; | |
105 | } | |
106 | ||
08ce5f16 | 107 | /* |
b4046f00 | 108 | * called under devcgroup_mutex |
08ce5f16 | 109 | */ |
db9aeca9 AR |
110 | static int dev_exception_add(struct dev_cgroup *dev_cgroup, |
111 | struct dev_exception_item *ex) | |
08ce5f16 | 112 | { |
db9aeca9 | 113 | struct dev_exception_item *excopy, *walk; |
08ce5f16 | 114 | |
4b1c7840 TH |
115 | lockdep_assert_held(&devcgroup_mutex); |
116 | ||
db9aeca9 AR |
117 | excopy = kmemdup(ex, sizeof(*ex), GFP_KERNEL); |
118 | if (!excopy) | |
08ce5f16 SH |
119 | return -ENOMEM; |
120 | ||
db9aeca9 AR |
121 | list_for_each_entry(walk, &dev_cgroup->exceptions, list) { |
122 | if (walk->type != ex->type) | |
d1ee2971 | 123 | continue; |
db9aeca9 | 124 | if (walk->major != ex->major) |
d1ee2971 | 125 | continue; |
db9aeca9 | 126 | if (walk->minor != ex->minor) |
d1ee2971 PE |
127 | continue; |
128 | ||
db9aeca9 AR |
129 | walk->access |= ex->access; |
130 | kfree(excopy); | |
131 | excopy = NULL; | |
d1ee2971 PE |
132 | } |
133 | ||
db9aeca9 AR |
134 | if (excopy != NULL) |
135 | list_add_tail_rcu(&excopy->list, &dev_cgroup->exceptions); | |
08ce5f16 SH |
136 | return 0; |
137 | } | |
138 | ||
139 | /* | |
b4046f00 | 140 | * called under devcgroup_mutex |
08ce5f16 | 141 | */ |
db9aeca9 AR |
142 | static void dev_exception_rm(struct dev_cgroup *dev_cgroup, |
143 | struct dev_exception_item *ex) | |
08ce5f16 | 144 | { |
db9aeca9 | 145 | struct dev_exception_item *walk, *tmp; |
08ce5f16 | 146 | |
4b1c7840 TH |
147 | lockdep_assert_held(&devcgroup_mutex); |
148 | ||
db9aeca9 AR |
149 | list_for_each_entry_safe(walk, tmp, &dev_cgroup->exceptions, list) { |
150 | if (walk->type != ex->type) | |
08ce5f16 | 151 | continue; |
db9aeca9 | 152 | if (walk->major != ex->major) |
08ce5f16 | 153 | continue; |
db9aeca9 | 154 | if (walk->minor != ex->minor) |
08ce5f16 SH |
155 | continue; |
156 | ||
db9aeca9 | 157 | walk->access &= ~ex->access; |
08ce5f16 | 158 | if (!walk->access) { |
4efd1a1b | 159 | list_del_rcu(&walk->list); |
6034f7e6 | 160 | kfree_rcu(walk, rcu); |
08ce5f16 SH |
161 | } |
162 | } | |
08ce5f16 SH |
163 | } |
164 | ||
53eb8c82 JS |
165 | static void __dev_exception_clean(struct dev_cgroup *dev_cgroup) |
166 | { | |
167 | struct dev_exception_item *ex, *tmp; | |
168 | ||
169 | list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { | |
170 | list_del_rcu(&ex->list); | |
171 | kfree_rcu(ex, rcu); | |
172 | } | |
173 | } | |
174 | ||
868539a3 | 175 | /** |
db9aeca9 AR |
176 | * dev_exception_clean - frees all entries of the exception list |
177 | * @dev_cgroup: dev_cgroup with the exception list to be cleaned | |
868539a3 AR |
178 | * |
179 | * called under devcgroup_mutex | |
180 | */ | |
db9aeca9 | 181 | static void dev_exception_clean(struct dev_cgroup *dev_cgroup) |
868539a3 | 182 | { |
4b1c7840 TH |
183 | lockdep_assert_held(&devcgroup_mutex); |
184 | ||
53eb8c82 | 185 | __dev_exception_clean(dev_cgroup); |
868539a3 AR |
186 | } |
187 | ||
1909554c AR |
188 | /** |
189 | * devcgroup_online - initializes devcgroup's behavior and exceptions based on | |
190 | * parent's | |
191 | * @cgroup: cgroup getting online | |
192 | * returns 0 in case of success, error code otherwise | |
193 | */ | |
194 | static int devcgroup_online(struct cgroup *cgroup) | |
195 | { | |
196 | struct dev_cgroup *dev_cgroup, *parent_dev_cgroup = NULL; | |
197 | int ret = 0; | |
198 | ||
199 | mutex_lock(&devcgroup_mutex); | |
200 | dev_cgroup = cgroup_to_devcgroup(cgroup); | |
201 | if (cgroup->parent) | |
202 | parent_dev_cgroup = cgroup_to_devcgroup(cgroup->parent); | |
203 | ||
204 | if (parent_dev_cgroup == NULL) | |
205 | dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW; | |
206 | else { | |
207 | ret = dev_exceptions_copy(&dev_cgroup->exceptions, | |
208 | &parent_dev_cgroup->exceptions); | |
209 | if (!ret) | |
210 | dev_cgroup->behavior = parent_dev_cgroup->behavior; | |
211 | } | |
212 | mutex_unlock(&devcgroup_mutex); | |
213 | ||
214 | return ret; | |
215 | } | |
216 | ||
217 | static void devcgroup_offline(struct cgroup *cgroup) | |
218 | { | |
219 | struct dev_cgroup *dev_cgroup = cgroup_to_devcgroup(cgroup); | |
220 | ||
221 | mutex_lock(&devcgroup_mutex); | |
222 | dev_cgroup->behavior = DEVCG_DEFAULT_NONE; | |
223 | mutex_unlock(&devcgroup_mutex); | |
224 | } | |
225 | ||
08ce5f16 SH |
226 | /* |
227 | * called from kernel/cgroup.c with cgroup_lock() held. | |
228 | */ | |
92fb9748 | 229 | static struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup) |
08ce5f16 | 230 | { |
1909554c | 231 | struct dev_cgroup *dev_cgroup; |
08ce5f16 | 232 | struct cgroup *parent_cgroup; |
08ce5f16 SH |
233 | |
234 | dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL); | |
235 | if (!dev_cgroup) | |
236 | return ERR_PTR(-ENOMEM); | |
db9aeca9 | 237 | INIT_LIST_HEAD(&dev_cgroup->exceptions); |
1909554c | 238 | dev_cgroup->behavior = DEVCG_DEFAULT_NONE; |
08ce5f16 SH |
239 | parent_cgroup = cgroup->parent; |
240 | ||
08ce5f16 SH |
241 | return &dev_cgroup->css; |
242 | } | |
243 | ||
92fb9748 | 244 | static void devcgroup_css_free(struct cgroup *cgroup) |
08ce5f16 SH |
245 | { |
246 | struct dev_cgroup *dev_cgroup; | |
08ce5f16 SH |
247 | |
248 | dev_cgroup = cgroup_to_devcgroup(cgroup); | |
53eb8c82 | 249 | __dev_exception_clean(dev_cgroup); |
08ce5f16 SH |
250 | kfree(dev_cgroup); |
251 | } | |
252 | ||
253 | #define DEVCG_ALLOW 1 | |
254 | #define DEVCG_DENY 2 | |
29486df3 SH |
255 | #define DEVCG_LIST 3 |
256 | ||
17d213f8 | 257 | #define MAJMINLEN 13 |
29486df3 | 258 | #define ACCLEN 4 |
08ce5f16 SH |
259 | |
260 | static void set_access(char *acc, short access) | |
261 | { | |
262 | int idx = 0; | |
29486df3 | 263 | memset(acc, 0, ACCLEN); |
08ce5f16 SH |
264 | if (access & ACC_READ) |
265 | acc[idx++] = 'r'; | |
266 | if (access & ACC_WRITE) | |
267 | acc[idx++] = 'w'; | |
268 | if (access & ACC_MKNOD) | |
269 | acc[idx++] = 'm'; | |
270 | } | |
271 | ||
272 | static char type_to_char(short type) | |
273 | { | |
274 | if (type == DEV_ALL) | |
275 | return 'a'; | |
276 | if (type == DEV_CHAR) | |
277 | return 'c'; | |
278 | if (type == DEV_BLOCK) | |
279 | return 'b'; | |
280 | return 'X'; | |
281 | } | |
282 | ||
29486df3 | 283 | static void set_majmin(char *str, unsigned m) |
08ce5f16 | 284 | { |
08ce5f16 | 285 | if (m == ~0) |
7759fc9d | 286 | strcpy(str, "*"); |
08ce5f16 | 287 | else |
7759fc9d | 288 | sprintf(str, "%u", m); |
08ce5f16 SH |
289 | } |
290 | ||
29486df3 SH |
291 | static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft, |
292 | struct seq_file *m) | |
08ce5f16 | 293 | { |
29486df3 | 294 | struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup); |
db9aeca9 | 295 | struct dev_exception_item *ex; |
29486df3 | 296 | char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; |
08ce5f16 | 297 | |
4efd1a1b | 298 | rcu_read_lock(); |
ad676077 AR |
299 | /* |
300 | * To preserve the compatibility: | |
301 | * - Only show the "all devices" when the default policy is to allow | |
302 | * - List the exceptions in case the default policy is to deny | |
303 | * This way, the file remains as a "whitelist of devices" | |
304 | */ | |
5b7aa7d5 | 305 | if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
ad676077 AR |
306 | set_access(acc, ACC_MASK); |
307 | set_majmin(maj, ~0); | |
308 | set_majmin(min, ~0); | |
309 | seq_printf(m, "%c %s:%s %s\n", type_to_char(DEV_ALL), | |
29486df3 | 310 | maj, min, acc); |
ad676077 | 311 | } else { |
db9aeca9 AR |
312 | list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) { |
313 | set_access(acc, ex->access); | |
314 | set_majmin(maj, ex->major); | |
315 | set_majmin(min, ex->minor); | |
316 | seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type), | |
ad676077 AR |
317 | maj, min, acc); |
318 | } | |
08ce5f16 | 319 | } |
4efd1a1b | 320 | rcu_read_unlock(); |
08ce5f16 | 321 | |
29486df3 | 322 | return 0; |
08ce5f16 SH |
323 | } |
324 | ||
ad676077 | 325 | /** |
db9aeca9 AR |
326 | * may_access - verifies if a new exception is part of what is allowed |
327 | * by a dev cgroup based on the default policy + | |
328 | * exceptions. This is used to make sure a child cgroup | |
329 | * won't have more privileges than its parent or to | |
330 | * verify if a certain access is allowed. | |
ad676077 | 331 | * @dev_cgroup: dev cgroup to be tested against |
db9aeca9 | 332 | * @refex: new exception |
c39a2a30 | 333 | * @behavior: behavior of the exception |
08ce5f16 | 334 | */ |
26898fdf | 335 | static bool may_access(struct dev_cgroup *dev_cgroup, |
c39a2a30 AR |
336 | struct dev_exception_item *refex, |
337 | enum devcg_behavior behavior) | |
08ce5f16 | 338 | { |
db9aeca9 | 339 | struct dev_exception_item *ex; |
ad676077 | 340 | bool match = false; |
08ce5f16 | 341 | |
4b1c7840 TH |
342 | rcu_lockdep_assert(rcu_read_lock_held() || |
343 | lockdep_is_held(&devcgroup_mutex), | |
344 | "device_cgroup::may_access() called without proper synchronization"); | |
345 | ||
201e72ac | 346 | list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) { |
db9aeca9 | 347 | if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) |
08ce5f16 | 348 | continue; |
db9aeca9 | 349 | if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR)) |
08ce5f16 | 350 | continue; |
db9aeca9 | 351 | if (ex->major != ~0 && ex->major != refex->major) |
08ce5f16 | 352 | continue; |
db9aeca9 | 353 | if (ex->minor != ~0 && ex->minor != refex->minor) |
08ce5f16 | 354 | continue; |
db9aeca9 | 355 | if (refex->access & (~ex->access)) |
08ce5f16 | 356 | continue; |
ad676077 AR |
357 | match = true; |
358 | break; | |
08ce5f16 | 359 | } |
ad676077 | 360 | |
c39a2a30 AR |
361 | if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
362 | if (behavior == DEVCG_DEFAULT_ALLOW) { | |
363 | /* the exception will deny access to certain devices */ | |
364 | return true; | |
365 | } else { | |
366 | /* the exception will allow access to certain devices */ | |
367 | if (match) | |
368 | /* | |
369 | * a new exception allowing access shouldn't | |
370 | * match an parent's exception | |
371 | */ | |
372 | return false; | |
26898fdf | 373 | return true; |
c39a2a30 | 374 | } |
26898fdf | 375 | } else { |
c39a2a30 AR |
376 | /* only behavior == DEVCG_DEFAULT_DENY allowed here */ |
377 | if (match) | |
378 | /* parent has an exception that matches the proposed */ | |
26898fdf | 379 | return true; |
c39a2a30 AR |
380 | else |
381 | return false; | |
26898fdf AR |
382 | } |
383 | return false; | |
08ce5f16 SH |
384 | } |
385 | ||
386 | /* | |
387 | * parent_has_perm: | |
db9aeca9 | 388 | * when adding a new allow rule to a device exception list, the rule |
08ce5f16 SH |
389 | * must be allowed in the parent device |
390 | */ | |
f92523e3 | 391 | static int parent_has_perm(struct dev_cgroup *childcg, |
db9aeca9 | 392 | struct dev_exception_item *ex) |
08ce5f16 | 393 | { |
f92523e3 | 394 | struct cgroup *pcg = childcg->css.cgroup->parent; |
08ce5f16 | 395 | struct dev_cgroup *parent; |
08ce5f16 SH |
396 | |
397 | if (!pcg) | |
398 | return 1; | |
399 | parent = cgroup_to_devcgroup(pcg); | |
c39a2a30 | 400 | return may_access(parent, ex, childcg->behavior); |
08ce5f16 SH |
401 | } |
402 | ||
4cef7299 AR |
403 | /** |
404 | * may_allow_all - checks if it's possible to change the behavior to | |
405 | * allow based on parent's rules. | |
406 | * @parent: device cgroup's parent | |
407 | * returns: != 0 in case it's allowed, 0 otherwise | |
408 | */ | |
409 | static inline int may_allow_all(struct dev_cgroup *parent) | |
410 | { | |
64e10477 AR |
411 | if (!parent) |
412 | return 1; | |
4cef7299 AR |
413 | return parent->behavior == DEVCG_DEFAULT_ALLOW; |
414 | } | |
415 | ||
08ce5f16 | 416 | /* |
db9aeca9 | 417 | * Modify the exception list using allow/deny rules. |
08ce5f16 SH |
418 | * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD |
419 | * so we can give a container CAP_MKNOD to let it create devices but not | |
db9aeca9 | 420 | * modify the exception list. |
08ce5f16 SH |
421 | * It seems likely we'll want to add a CAP_CONTAINER capability to allow |
422 | * us to also grant CAP_SYS_ADMIN to containers without giving away the | |
db9aeca9 | 423 | * device exception list controls, but for now we'll stick with CAP_SYS_ADMIN |
08ce5f16 SH |
424 | * |
425 | * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting | |
426 | * new access is only allowed if you're in the top-level cgroup, or your | |
427 | * parent cgroup has the access you're asking for. | |
428 | */ | |
f92523e3 PM |
429 | static int devcgroup_update_access(struct dev_cgroup *devcgroup, |
430 | int filetype, const char *buffer) | |
08ce5f16 | 431 | { |
f92523e3 | 432 | const char *b; |
26fd8405 | 433 | char temp[12]; /* 11 + 1 characters needed for a u32 */ |
c39a2a30 | 434 | int count, rc = 0; |
db9aeca9 | 435 | struct dev_exception_item ex; |
4cef7299 | 436 | struct cgroup *p = devcgroup->css.cgroup; |
64e10477 | 437 | struct dev_cgroup *parent = NULL; |
08ce5f16 SH |
438 | |
439 | if (!capable(CAP_SYS_ADMIN)) | |
440 | return -EPERM; | |
441 | ||
64e10477 AR |
442 | if (p->parent) |
443 | parent = cgroup_to_devcgroup(p->parent); | |
444 | ||
db9aeca9 | 445 | memset(&ex, 0, sizeof(ex)); |
08ce5f16 SH |
446 | b = buffer; |
447 | ||
448 | switch (*b) { | |
449 | case 'a': | |
ad676077 AR |
450 | switch (filetype) { |
451 | case DEVCG_ALLOW: | |
4cef7299 | 452 | if (!may_allow_all(parent)) |
ad676077 | 453 | return -EPERM; |
db9aeca9 | 454 | dev_exception_clean(devcgroup); |
64e10477 AR |
455 | devcgroup->behavior = DEVCG_DEFAULT_ALLOW; |
456 | if (!parent) | |
457 | break; | |
458 | ||
4cef7299 AR |
459 | rc = dev_exceptions_copy(&devcgroup->exceptions, |
460 | &parent->exceptions); | |
461 | if (rc) | |
462 | return rc; | |
ad676077 AR |
463 | break; |
464 | case DEVCG_DENY: | |
db9aeca9 | 465 | dev_exception_clean(devcgroup); |
5b7aa7d5 | 466 | devcgroup->behavior = DEVCG_DEFAULT_DENY; |
ad676077 AR |
467 | break; |
468 | default: | |
469 | return -EINVAL; | |
470 | } | |
471 | return 0; | |
08ce5f16 | 472 | case 'b': |
db9aeca9 | 473 | ex.type = DEV_BLOCK; |
08ce5f16 SH |
474 | break; |
475 | case 'c': | |
db9aeca9 | 476 | ex.type = DEV_CHAR; |
08ce5f16 SH |
477 | break; |
478 | default: | |
f92523e3 | 479 | return -EINVAL; |
08ce5f16 SH |
480 | } |
481 | b++; | |
f92523e3 PM |
482 | if (!isspace(*b)) |
483 | return -EINVAL; | |
08ce5f16 SH |
484 | b++; |
485 | if (*b == '*') { | |
db9aeca9 | 486 | ex.major = ~0; |
08ce5f16 SH |
487 | b++; |
488 | } else if (isdigit(*b)) { | |
26fd8405 AR |
489 | memset(temp, 0, sizeof(temp)); |
490 | for (count = 0; count < sizeof(temp) - 1; count++) { | |
491 | temp[count] = *b; | |
492 | b++; | |
493 | if (!isdigit(*b)) | |
494 | break; | |
495 | } | |
496 | rc = kstrtou32(temp, 10, &ex.major); | |
497 | if (rc) | |
498 | return -EINVAL; | |
08ce5f16 | 499 | } else { |
f92523e3 | 500 | return -EINVAL; |
08ce5f16 | 501 | } |
f92523e3 PM |
502 | if (*b != ':') |
503 | return -EINVAL; | |
08ce5f16 SH |
504 | b++; |
505 | ||
506 | /* read minor */ | |
507 | if (*b == '*') { | |
db9aeca9 | 508 | ex.minor = ~0; |
08ce5f16 SH |
509 | b++; |
510 | } else if (isdigit(*b)) { | |
26fd8405 AR |
511 | memset(temp, 0, sizeof(temp)); |
512 | for (count = 0; count < sizeof(temp) - 1; count++) { | |
513 | temp[count] = *b; | |
514 | b++; | |
515 | if (!isdigit(*b)) | |
516 | break; | |
517 | } | |
518 | rc = kstrtou32(temp, 10, &ex.minor); | |
519 | if (rc) | |
520 | return -EINVAL; | |
08ce5f16 | 521 | } else { |
f92523e3 | 522 | return -EINVAL; |
08ce5f16 | 523 | } |
f92523e3 PM |
524 | if (!isspace(*b)) |
525 | return -EINVAL; | |
08ce5f16 SH |
526 | for (b++, count = 0; count < 3; count++, b++) { |
527 | switch (*b) { | |
528 | case 'r': | |
db9aeca9 | 529 | ex.access |= ACC_READ; |
08ce5f16 SH |
530 | break; |
531 | case 'w': | |
db9aeca9 | 532 | ex.access |= ACC_WRITE; |
08ce5f16 SH |
533 | break; |
534 | case 'm': | |
db9aeca9 | 535 | ex.access |= ACC_MKNOD; |
08ce5f16 SH |
536 | break; |
537 | case '\n': | |
538 | case '\0': | |
539 | count = 3; | |
540 | break; | |
541 | default: | |
f92523e3 | 542 | return -EINVAL; |
08ce5f16 SH |
543 | } |
544 | } | |
545 | ||
08ce5f16 SH |
546 | switch (filetype) { |
547 | case DEVCG_ALLOW: | |
db9aeca9 | 548 | if (!parent_has_perm(devcgroup, &ex)) |
f92523e3 | 549 | return -EPERM; |
ad676077 AR |
550 | /* |
551 | * If the default policy is to allow by default, try to remove | |
552 | * an matching exception instead. And be silent about it: we | |
553 | * don't want to break compatibility | |
554 | */ | |
5b7aa7d5 | 555 | if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
db9aeca9 | 556 | dev_exception_rm(devcgroup, &ex); |
ad676077 AR |
557 | return 0; |
558 | } | |
db9aeca9 | 559 | return dev_exception_add(devcgroup, &ex); |
08ce5f16 | 560 | case DEVCG_DENY: |
ad676077 AR |
561 | /* |
562 | * If the default policy is to deny by default, try to remove | |
563 | * an matching exception instead. And be silent about it: we | |
564 | * don't want to break compatibility | |
565 | */ | |
5b7aa7d5 | 566 | if (devcgroup->behavior == DEVCG_DEFAULT_DENY) { |
db9aeca9 | 567 | dev_exception_rm(devcgroup, &ex); |
ad676077 AR |
568 | return 0; |
569 | } | |
db9aeca9 | 570 | return dev_exception_add(devcgroup, &ex); |
08ce5f16 | 571 | default: |
f92523e3 | 572 | return -EINVAL; |
08ce5f16 | 573 | } |
f92523e3 PM |
574 | return 0; |
575 | } | |
08ce5f16 | 576 | |
f92523e3 PM |
577 | static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft, |
578 | const char *buffer) | |
579 | { | |
580 | int retval; | |
b4046f00 LZ |
581 | |
582 | mutex_lock(&devcgroup_mutex); | |
f92523e3 PM |
583 | retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp), |
584 | cft->private, buffer); | |
b4046f00 | 585 | mutex_unlock(&devcgroup_mutex); |
08ce5f16 SH |
586 | return retval; |
587 | } | |
588 | ||
589 | static struct cftype dev_cgroup_files[] = { | |
590 | { | |
591 | .name = "allow", | |
f92523e3 | 592 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
593 | .private = DEVCG_ALLOW, |
594 | }, | |
595 | { | |
596 | .name = "deny", | |
f92523e3 | 597 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
598 | .private = DEVCG_DENY, |
599 | }, | |
29486df3 SH |
600 | { |
601 | .name = "list", | |
602 | .read_seq_string = devcgroup_seq_read, | |
603 | .private = DEVCG_LIST, | |
604 | }, | |
4baf6e33 | 605 | { } /* terminate */ |
08ce5f16 SH |
606 | }; |
607 | ||
08ce5f16 SH |
608 | struct cgroup_subsys devices_subsys = { |
609 | .name = "devices", | |
610 | .can_attach = devcgroup_can_attach, | |
92fb9748 TH |
611 | .css_alloc = devcgroup_css_alloc, |
612 | .css_free = devcgroup_css_free, | |
1909554c AR |
613 | .css_online = devcgroup_online, |
614 | .css_offline = devcgroup_offline, | |
08ce5f16 | 615 | .subsys_id = devices_subsys_id, |
4baf6e33 | 616 | .base_cftypes = dev_cgroup_files, |
8c7f6edb TH |
617 | |
618 | /* | |
619 | * While devices cgroup has the rudimentary hierarchy support which | |
620 | * checks the parent's restriction, it doesn't properly propagates | |
621 | * config changes in ancestors to their descendents. A child | |
622 | * should only be allowed to add more restrictions to the parent's | |
623 | * configuration. Fix it and remove the following. | |
624 | */ | |
625 | .broken_hierarchy = true, | |
08ce5f16 SH |
626 | }; |
627 | ||
ad676077 AR |
628 | /** |
629 | * __devcgroup_check_permission - checks if an inode operation is permitted | |
630 | * @dev_cgroup: the dev cgroup to be tested against | |
631 | * @type: device type | |
632 | * @major: device major number | |
633 | * @minor: device minor number | |
634 | * @access: combination of ACC_WRITE, ACC_READ and ACC_MKNOD | |
635 | * | |
636 | * returns 0 on success, -EPERM case the operation is not permitted | |
637 | */ | |
8c9506d1 | 638 | static int __devcgroup_check_permission(short type, u32 major, u32 minor, |
ad676077 | 639 | short access) |
08ce5f16 | 640 | { |
8c9506d1 | 641 | struct dev_cgroup *dev_cgroup; |
db9aeca9 | 642 | struct dev_exception_item ex; |
ad676077 | 643 | int rc; |
36fd71d2 | 644 | |
db9aeca9 AR |
645 | memset(&ex, 0, sizeof(ex)); |
646 | ex.type = type; | |
647 | ex.major = major; | |
648 | ex.minor = minor; | |
649 | ex.access = access; | |
36fd71d2 | 650 | |
ad676077 | 651 | rcu_read_lock(); |
8c9506d1 | 652 | dev_cgroup = task_devcgroup(current); |
c39a2a30 | 653 | rc = may_access(dev_cgroup, &ex, dev_cgroup->behavior); |
ad676077 | 654 | rcu_read_unlock(); |
cd500819 | 655 | |
ad676077 AR |
656 | if (!rc) |
657 | return -EPERM; | |
36fd71d2 | 658 | |
ad676077 AR |
659 | return 0; |
660 | } | |
08ce5f16 | 661 | |
ad676077 AR |
662 | int __devcgroup_inode_permission(struct inode *inode, int mask) |
663 | { | |
ad676077 AR |
664 | short type, access = 0; |
665 | ||
666 | if (S_ISBLK(inode->i_mode)) | |
667 | type = DEV_BLOCK; | |
668 | if (S_ISCHR(inode->i_mode)) | |
669 | type = DEV_CHAR; | |
670 | if (mask & MAY_WRITE) | |
671 | access |= ACC_WRITE; | |
672 | if (mask & MAY_READ) | |
673 | access |= ACC_READ; | |
674 | ||
8c9506d1 JS |
675 | return __devcgroup_check_permission(type, imajor(inode), iminor(inode), |
676 | access); | |
08ce5f16 SH |
677 | } |
678 | ||
679 | int devcgroup_inode_mknod(int mode, dev_t dev) | |
680 | { | |
ad676077 | 681 | short type; |
08ce5f16 | 682 | |
0b82ac37 SH |
683 | if (!S_ISBLK(mode) && !S_ISCHR(mode)) |
684 | return 0; | |
685 | ||
ad676077 AR |
686 | if (S_ISBLK(mode)) |
687 | type = DEV_BLOCK; | |
688 | else | |
689 | type = DEV_CHAR; | |
36fd71d2 | 690 | |
8c9506d1 JS |
691 | return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev), |
692 | ACC_MKNOD); | |
36fd71d2 | 693 | |
08ce5f16 | 694 | } |