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 | { | |
a7c6d554 | 56 | return s ? container_of(s, struct dev_cgroup, css) : NULL; |
b66862f7 PE |
57 | } |
58 | ||
f92523e3 PM |
59 | static inline struct dev_cgroup *task_devcgroup(struct task_struct *task) |
60 | { | |
8af01f56 | 61 | return css_to_devcgroup(task_css(task, devices_subsys_id)); |
f92523e3 PM |
62 | } |
63 | ||
08ce5f16 SH |
64 | struct cgroup_subsys devices_subsys; |
65 | ||
08ce5f16 | 66 | /* |
b4046f00 | 67 | * called under devcgroup_mutex |
08ce5f16 | 68 | */ |
db9aeca9 | 69 | static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig) |
08ce5f16 | 70 | { |
db9aeca9 | 71 | struct dev_exception_item *ex, *tmp, *new; |
08ce5f16 | 72 | |
4b1c7840 TH |
73 | lockdep_assert_held(&devcgroup_mutex); |
74 | ||
db9aeca9 AR |
75 | list_for_each_entry(ex, orig, list) { |
76 | new = kmemdup(ex, sizeof(*ex), GFP_KERNEL); | |
08ce5f16 SH |
77 | if (!new) |
78 | goto free_and_exit; | |
08ce5f16 SH |
79 | list_add_tail(&new->list, dest); |
80 | } | |
81 | ||
82 | return 0; | |
83 | ||
84 | free_and_exit: | |
db9aeca9 AR |
85 | list_for_each_entry_safe(ex, tmp, dest, list) { |
86 | list_del(&ex->list); | |
87 | kfree(ex); | |
08ce5f16 SH |
88 | } |
89 | return -ENOMEM; | |
90 | } | |
91 | ||
08ce5f16 | 92 | /* |
b4046f00 | 93 | * called under devcgroup_mutex |
08ce5f16 | 94 | */ |
db9aeca9 AR |
95 | static int dev_exception_add(struct dev_cgroup *dev_cgroup, |
96 | struct dev_exception_item *ex) | |
08ce5f16 | 97 | { |
db9aeca9 | 98 | struct dev_exception_item *excopy, *walk; |
08ce5f16 | 99 | |
4b1c7840 TH |
100 | lockdep_assert_held(&devcgroup_mutex); |
101 | ||
db9aeca9 AR |
102 | excopy = kmemdup(ex, sizeof(*ex), GFP_KERNEL); |
103 | if (!excopy) | |
08ce5f16 SH |
104 | return -ENOMEM; |
105 | ||
db9aeca9 AR |
106 | list_for_each_entry(walk, &dev_cgroup->exceptions, list) { |
107 | if (walk->type != ex->type) | |
d1ee2971 | 108 | continue; |
db9aeca9 | 109 | if (walk->major != ex->major) |
d1ee2971 | 110 | continue; |
db9aeca9 | 111 | if (walk->minor != ex->minor) |
d1ee2971 PE |
112 | continue; |
113 | ||
db9aeca9 AR |
114 | walk->access |= ex->access; |
115 | kfree(excopy); | |
116 | excopy = NULL; | |
d1ee2971 PE |
117 | } |
118 | ||
db9aeca9 AR |
119 | if (excopy != NULL) |
120 | list_add_tail_rcu(&excopy->list, &dev_cgroup->exceptions); | |
08ce5f16 SH |
121 | return 0; |
122 | } | |
123 | ||
124 | /* | |
b4046f00 | 125 | * called under devcgroup_mutex |
08ce5f16 | 126 | */ |
db9aeca9 AR |
127 | static void dev_exception_rm(struct dev_cgroup *dev_cgroup, |
128 | struct dev_exception_item *ex) | |
08ce5f16 | 129 | { |
db9aeca9 | 130 | struct dev_exception_item *walk, *tmp; |
08ce5f16 | 131 | |
4b1c7840 TH |
132 | lockdep_assert_held(&devcgroup_mutex); |
133 | ||
db9aeca9 AR |
134 | list_for_each_entry_safe(walk, tmp, &dev_cgroup->exceptions, list) { |
135 | if (walk->type != ex->type) | |
08ce5f16 | 136 | continue; |
db9aeca9 | 137 | if (walk->major != ex->major) |
08ce5f16 | 138 | continue; |
db9aeca9 | 139 | if (walk->minor != ex->minor) |
08ce5f16 SH |
140 | continue; |
141 | ||
db9aeca9 | 142 | walk->access &= ~ex->access; |
08ce5f16 | 143 | if (!walk->access) { |
4efd1a1b | 144 | list_del_rcu(&walk->list); |
6034f7e6 | 145 | kfree_rcu(walk, rcu); |
08ce5f16 SH |
146 | } |
147 | } | |
08ce5f16 SH |
148 | } |
149 | ||
53eb8c82 JS |
150 | static void __dev_exception_clean(struct dev_cgroup *dev_cgroup) |
151 | { | |
152 | struct dev_exception_item *ex, *tmp; | |
153 | ||
154 | list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { | |
155 | list_del_rcu(&ex->list); | |
156 | kfree_rcu(ex, rcu); | |
157 | } | |
158 | } | |
159 | ||
868539a3 | 160 | /** |
db9aeca9 AR |
161 | * dev_exception_clean - frees all entries of the exception list |
162 | * @dev_cgroup: dev_cgroup with the exception list to be cleaned | |
868539a3 AR |
163 | * |
164 | * called under devcgroup_mutex | |
165 | */ | |
db9aeca9 | 166 | static void dev_exception_clean(struct dev_cgroup *dev_cgroup) |
868539a3 | 167 | { |
4b1c7840 TH |
168 | lockdep_assert_held(&devcgroup_mutex); |
169 | ||
53eb8c82 | 170 | __dev_exception_clean(dev_cgroup); |
868539a3 AR |
171 | } |
172 | ||
bd2953eb AR |
173 | static inline bool is_devcg_online(const struct dev_cgroup *devcg) |
174 | { | |
175 | return (devcg->behavior != DEVCG_DEFAULT_NONE); | |
176 | } | |
177 | ||
1909554c AR |
178 | /** |
179 | * devcgroup_online - initializes devcgroup's behavior and exceptions based on | |
180 | * parent's | |
eb95419b | 181 | * @css: css getting online |
1909554c AR |
182 | * returns 0 in case of success, error code otherwise |
183 | */ | |
eb95419b | 184 | static int devcgroup_online(struct cgroup_subsys_state *css) |
1909554c | 185 | { |
eb95419b TH |
186 | struct dev_cgroup *dev_cgroup = css_to_devcgroup(css); |
187 | struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css_parent(css)); | |
1909554c AR |
188 | int ret = 0; |
189 | ||
190 | mutex_lock(&devcgroup_mutex); | |
1909554c AR |
191 | |
192 | if (parent_dev_cgroup == NULL) | |
193 | dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW; | |
194 | else { | |
195 | ret = dev_exceptions_copy(&dev_cgroup->exceptions, | |
196 | &parent_dev_cgroup->exceptions); | |
197 | if (!ret) | |
198 | dev_cgroup->behavior = parent_dev_cgroup->behavior; | |
199 | } | |
200 | mutex_unlock(&devcgroup_mutex); | |
201 | ||
202 | return ret; | |
203 | } | |
204 | ||
eb95419b | 205 | static void devcgroup_offline(struct cgroup_subsys_state *css) |
1909554c | 206 | { |
eb95419b | 207 | struct dev_cgroup *dev_cgroup = css_to_devcgroup(css); |
1909554c AR |
208 | |
209 | mutex_lock(&devcgroup_mutex); | |
210 | dev_cgroup->behavior = DEVCG_DEFAULT_NONE; | |
211 | mutex_unlock(&devcgroup_mutex); | |
212 | } | |
213 | ||
08ce5f16 SH |
214 | /* |
215 | * called from kernel/cgroup.c with cgroup_lock() held. | |
216 | */ | |
eb95419b TH |
217 | static struct cgroup_subsys_state * |
218 | devcgroup_css_alloc(struct cgroup_subsys_state *parent_css) | |
08ce5f16 | 219 | { |
1909554c | 220 | struct dev_cgroup *dev_cgroup; |
08ce5f16 SH |
221 | |
222 | dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL); | |
223 | if (!dev_cgroup) | |
224 | return ERR_PTR(-ENOMEM); | |
db9aeca9 | 225 | INIT_LIST_HEAD(&dev_cgroup->exceptions); |
1909554c | 226 | dev_cgroup->behavior = DEVCG_DEFAULT_NONE; |
08ce5f16 | 227 | |
08ce5f16 SH |
228 | return &dev_cgroup->css; |
229 | } | |
230 | ||
eb95419b | 231 | static void devcgroup_css_free(struct cgroup_subsys_state *css) |
08ce5f16 | 232 | { |
eb95419b | 233 | struct dev_cgroup *dev_cgroup = css_to_devcgroup(css); |
08ce5f16 | 234 | |
53eb8c82 | 235 | __dev_exception_clean(dev_cgroup); |
08ce5f16 SH |
236 | kfree(dev_cgroup); |
237 | } | |
238 | ||
239 | #define DEVCG_ALLOW 1 | |
240 | #define DEVCG_DENY 2 | |
29486df3 SH |
241 | #define DEVCG_LIST 3 |
242 | ||
17d213f8 | 243 | #define MAJMINLEN 13 |
29486df3 | 244 | #define ACCLEN 4 |
08ce5f16 SH |
245 | |
246 | static void set_access(char *acc, short access) | |
247 | { | |
248 | int idx = 0; | |
29486df3 | 249 | memset(acc, 0, ACCLEN); |
08ce5f16 SH |
250 | if (access & ACC_READ) |
251 | acc[idx++] = 'r'; | |
252 | if (access & ACC_WRITE) | |
253 | acc[idx++] = 'w'; | |
254 | if (access & ACC_MKNOD) | |
255 | acc[idx++] = 'm'; | |
256 | } | |
257 | ||
258 | static char type_to_char(short type) | |
259 | { | |
260 | if (type == DEV_ALL) | |
261 | return 'a'; | |
262 | if (type == DEV_CHAR) | |
263 | return 'c'; | |
264 | if (type == DEV_BLOCK) | |
265 | return 'b'; | |
266 | return 'X'; | |
267 | } | |
268 | ||
29486df3 | 269 | static void set_majmin(char *str, unsigned m) |
08ce5f16 | 270 | { |
08ce5f16 | 271 | if (m == ~0) |
7759fc9d | 272 | strcpy(str, "*"); |
08ce5f16 | 273 | else |
7759fc9d | 274 | sprintf(str, "%u", m); |
08ce5f16 SH |
275 | } |
276 | ||
2da8ca82 | 277 | static int devcgroup_seq_show(struct seq_file *m, void *v) |
08ce5f16 | 278 | { |
2da8ca82 | 279 | struct dev_cgroup *devcgroup = css_to_devcgroup(seq_css(m)); |
db9aeca9 | 280 | struct dev_exception_item *ex; |
29486df3 | 281 | char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; |
08ce5f16 | 282 | |
4efd1a1b | 283 | rcu_read_lock(); |
ad676077 AR |
284 | /* |
285 | * To preserve the compatibility: | |
286 | * - Only show the "all devices" when the default policy is to allow | |
287 | * - List the exceptions in case the default policy is to deny | |
288 | * This way, the file remains as a "whitelist of devices" | |
289 | */ | |
5b7aa7d5 | 290 | if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
ad676077 AR |
291 | set_access(acc, ACC_MASK); |
292 | set_majmin(maj, ~0); | |
293 | set_majmin(min, ~0); | |
294 | seq_printf(m, "%c %s:%s %s\n", type_to_char(DEV_ALL), | |
29486df3 | 295 | maj, min, acc); |
ad676077 | 296 | } else { |
db9aeca9 AR |
297 | list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) { |
298 | set_access(acc, ex->access); | |
299 | set_majmin(maj, ex->major); | |
300 | set_majmin(min, ex->minor); | |
301 | seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type), | |
ad676077 AR |
302 | maj, min, acc); |
303 | } | |
08ce5f16 | 304 | } |
4efd1a1b | 305 | rcu_read_unlock(); |
08ce5f16 | 306 | |
29486df3 | 307 | return 0; |
08ce5f16 SH |
308 | } |
309 | ||
ad676077 | 310 | /** |
db9aeca9 AR |
311 | * may_access - verifies if a new exception is part of what is allowed |
312 | * by a dev cgroup based on the default policy + | |
313 | * exceptions. This is used to make sure a child cgroup | |
314 | * won't have more privileges than its parent or to | |
315 | * verify if a certain access is allowed. | |
ad676077 | 316 | * @dev_cgroup: dev cgroup to be tested against |
db9aeca9 | 317 | * @refex: new exception |
c39a2a30 | 318 | * @behavior: behavior of the exception |
08ce5f16 | 319 | */ |
26898fdf | 320 | static bool may_access(struct dev_cgroup *dev_cgroup, |
c39a2a30 AR |
321 | struct dev_exception_item *refex, |
322 | enum devcg_behavior behavior) | |
08ce5f16 | 323 | { |
db9aeca9 | 324 | struct dev_exception_item *ex; |
ad676077 | 325 | bool match = false; |
08ce5f16 | 326 | |
4b1c7840 TH |
327 | rcu_lockdep_assert(rcu_read_lock_held() || |
328 | lockdep_is_held(&devcgroup_mutex), | |
329 | "device_cgroup::may_access() called without proper synchronization"); | |
330 | ||
201e72ac | 331 | list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) { |
db9aeca9 | 332 | if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) |
08ce5f16 | 333 | continue; |
db9aeca9 | 334 | if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR)) |
08ce5f16 | 335 | continue; |
db9aeca9 | 336 | if (ex->major != ~0 && ex->major != refex->major) |
08ce5f16 | 337 | continue; |
db9aeca9 | 338 | if (ex->minor != ~0 && ex->minor != refex->minor) |
08ce5f16 | 339 | continue; |
db9aeca9 | 340 | if (refex->access & (~ex->access)) |
08ce5f16 | 341 | continue; |
ad676077 AR |
342 | match = true; |
343 | break; | |
08ce5f16 | 344 | } |
ad676077 | 345 | |
c39a2a30 AR |
346 | if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
347 | if (behavior == DEVCG_DEFAULT_ALLOW) { | |
348 | /* the exception will deny access to certain devices */ | |
349 | return true; | |
350 | } else { | |
351 | /* the exception will allow access to certain devices */ | |
352 | if (match) | |
353 | /* | |
354 | * a new exception allowing access shouldn't | |
355 | * match an parent's exception | |
356 | */ | |
357 | return false; | |
26898fdf | 358 | return true; |
c39a2a30 | 359 | } |
26898fdf | 360 | } else { |
c39a2a30 AR |
361 | /* only behavior == DEVCG_DEFAULT_DENY allowed here */ |
362 | if (match) | |
363 | /* parent has an exception that matches the proposed */ | |
26898fdf | 364 | return true; |
c39a2a30 AR |
365 | else |
366 | return false; | |
26898fdf AR |
367 | } |
368 | return false; | |
08ce5f16 SH |
369 | } |
370 | ||
371 | /* | |
372 | * parent_has_perm: | |
db9aeca9 | 373 | * when adding a new allow rule to a device exception list, the rule |
08ce5f16 SH |
374 | * must be allowed in the parent device |
375 | */ | |
f92523e3 | 376 | static int parent_has_perm(struct dev_cgroup *childcg, |
db9aeca9 | 377 | struct dev_exception_item *ex) |
08ce5f16 | 378 | { |
63876986 | 379 | struct dev_cgroup *parent = css_to_devcgroup(css_parent(&childcg->css)); |
08ce5f16 | 380 | |
63876986 | 381 | if (!parent) |
08ce5f16 | 382 | return 1; |
c39a2a30 | 383 | return may_access(parent, ex, childcg->behavior); |
08ce5f16 SH |
384 | } |
385 | ||
4cef7299 AR |
386 | /** |
387 | * may_allow_all - checks if it's possible to change the behavior to | |
388 | * allow based on parent's rules. | |
389 | * @parent: device cgroup's parent | |
390 | * returns: != 0 in case it's allowed, 0 otherwise | |
391 | */ | |
392 | static inline int may_allow_all(struct dev_cgroup *parent) | |
393 | { | |
64e10477 AR |
394 | if (!parent) |
395 | return 1; | |
4cef7299 AR |
396 | return parent->behavior == DEVCG_DEFAULT_ALLOW; |
397 | } | |
398 | ||
bd2953eb AR |
399 | /** |
400 | * revalidate_active_exceptions - walks through the active exception list and | |
401 | * revalidates the exceptions based on parent's | |
402 | * behavior and exceptions. The exceptions that | |
403 | * are no longer valid will be removed. | |
404 | * Called with devcgroup_mutex held. | |
405 | * @devcg: cgroup which exceptions will be checked | |
406 | * | |
407 | * This is one of the three key functions for hierarchy implementation. | |
408 | * This function is responsible for re-evaluating all the cgroup's active | |
409 | * exceptions due to a parent's exception change. | |
410 | * Refer to Documentation/cgroups/devices.txt for more details. | |
411 | */ | |
412 | static void revalidate_active_exceptions(struct dev_cgroup *devcg) | |
413 | { | |
414 | struct dev_exception_item *ex; | |
415 | struct list_head *this, *tmp; | |
416 | ||
417 | list_for_each_safe(this, tmp, &devcg->exceptions) { | |
418 | ex = container_of(this, struct dev_exception_item, list); | |
419 | if (!parent_has_perm(devcg, ex)) | |
420 | dev_exception_rm(devcg, ex); | |
421 | } | |
422 | } | |
423 | ||
bd2953eb AR |
424 | /** |
425 | * propagate_exception - propagates a new exception to the children | |
426 | * @devcg_root: device cgroup that added a new exception | |
427 | * @ex: new exception to be propagated | |
428 | * | |
429 | * returns: 0 in case of success, != 0 in case of error | |
430 | */ | |
431 | static int propagate_exception(struct dev_cgroup *devcg_root, | |
432 | struct dev_exception_item *ex) | |
433 | { | |
492eb21b | 434 | struct cgroup_subsys_state *pos; |
bd2953eb | 435 | int rc = 0; |
bd2953eb | 436 | |
d591fb56 | 437 | rcu_read_lock(); |
bd2953eb | 438 | |
492eb21b TH |
439 | css_for_each_descendant_pre(pos, &devcg_root->css) { |
440 | struct dev_cgroup *devcg = css_to_devcgroup(pos); | |
d591fb56 TH |
441 | |
442 | /* | |
443 | * Because devcgroup_mutex is held, no devcg will become | |
444 | * online or offline during the tree walk (see on/offline | |
445 | * methods), and online ones are safe to access outside RCU | |
446 | * read lock without bumping refcnt. | |
447 | */ | |
bd8815a6 | 448 | if (pos == &devcg_root->css || !is_devcg_online(devcg)) |
d591fb56 TH |
449 | continue; |
450 | ||
451 | rcu_read_unlock(); | |
bd2953eb AR |
452 | |
453 | /* | |
454 | * in case both root's behavior and devcg is allow, a new | |
455 | * restriction means adding to the exception list | |
456 | */ | |
457 | if (devcg_root->behavior == DEVCG_DEFAULT_ALLOW && | |
458 | devcg->behavior == DEVCG_DEFAULT_ALLOW) { | |
459 | rc = dev_exception_add(devcg, ex); | |
460 | if (rc) | |
461 | break; | |
462 | } else { | |
463 | /* | |
464 | * in the other possible cases: | |
465 | * root's behavior: allow, devcg's: deny | |
466 | * root's behavior: deny, devcg's: deny | |
467 | * the exception will be removed | |
468 | */ | |
469 | dev_exception_rm(devcg, ex); | |
470 | } | |
471 | revalidate_active_exceptions(devcg); | |
472 | ||
d591fb56 | 473 | rcu_read_lock(); |
bd2953eb | 474 | } |
d591fb56 TH |
475 | |
476 | rcu_read_unlock(); | |
bd2953eb AR |
477 | return rc; |
478 | } | |
479 | ||
480 | static inline bool has_children(struct dev_cgroup *devcgroup) | |
481 | { | |
482 | struct cgroup *cgrp = devcgroup->css.cgroup; | |
483 | ||
484 | return !list_empty(&cgrp->children); | |
485 | } | |
486 | ||
08ce5f16 | 487 | /* |
db9aeca9 | 488 | * Modify the exception list using allow/deny rules. |
08ce5f16 SH |
489 | * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD |
490 | * so we can give a container CAP_MKNOD to let it create devices but not | |
db9aeca9 | 491 | * modify the exception list. |
08ce5f16 SH |
492 | * It seems likely we'll want to add a CAP_CONTAINER capability to allow |
493 | * us to also grant CAP_SYS_ADMIN to containers without giving away the | |
db9aeca9 | 494 | * device exception list controls, but for now we'll stick with CAP_SYS_ADMIN |
08ce5f16 SH |
495 | * |
496 | * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting | |
497 | * new access is only allowed if you're in the top-level cgroup, or your | |
498 | * parent cgroup has the access you're asking for. | |
499 | */ | |
f92523e3 PM |
500 | static int devcgroup_update_access(struct dev_cgroup *devcgroup, |
501 | int filetype, const char *buffer) | |
08ce5f16 | 502 | { |
f92523e3 | 503 | const char *b; |
26fd8405 | 504 | char temp[12]; /* 11 + 1 characters needed for a u32 */ |
c39a2a30 | 505 | int count, rc = 0; |
db9aeca9 | 506 | struct dev_exception_item ex; |
63876986 | 507 | struct dev_cgroup *parent = css_to_devcgroup(css_parent(&devcgroup->css)); |
08ce5f16 SH |
508 | |
509 | if (!capable(CAP_SYS_ADMIN)) | |
510 | return -EPERM; | |
511 | ||
db9aeca9 | 512 | memset(&ex, 0, sizeof(ex)); |
08ce5f16 SH |
513 | b = buffer; |
514 | ||
515 | switch (*b) { | |
516 | case 'a': | |
ad676077 AR |
517 | switch (filetype) { |
518 | case DEVCG_ALLOW: | |
bd2953eb AR |
519 | if (has_children(devcgroup)) |
520 | return -EINVAL; | |
521 | ||
4cef7299 | 522 | if (!may_allow_all(parent)) |
ad676077 | 523 | return -EPERM; |
db9aeca9 | 524 | dev_exception_clean(devcgroup); |
64e10477 AR |
525 | devcgroup->behavior = DEVCG_DEFAULT_ALLOW; |
526 | if (!parent) | |
527 | break; | |
528 | ||
4cef7299 AR |
529 | rc = dev_exceptions_copy(&devcgroup->exceptions, |
530 | &parent->exceptions); | |
531 | if (rc) | |
532 | return rc; | |
ad676077 AR |
533 | break; |
534 | case DEVCG_DENY: | |
bd2953eb AR |
535 | if (has_children(devcgroup)) |
536 | return -EINVAL; | |
537 | ||
db9aeca9 | 538 | dev_exception_clean(devcgroup); |
5b7aa7d5 | 539 | devcgroup->behavior = DEVCG_DEFAULT_DENY; |
ad676077 AR |
540 | break; |
541 | default: | |
542 | return -EINVAL; | |
543 | } | |
544 | return 0; | |
08ce5f16 | 545 | case 'b': |
db9aeca9 | 546 | ex.type = DEV_BLOCK; |
08ce5f16 SH |
547 | break; |
548 | case 'c': | |
db9aeca9 | 549 | ex.type = DEV_CHAR; |
08ce5f16 SH |
550 | break; |
551 | default: | |
f92523e3 | 552 | return -EINVAL; |
08ce5f16 SH |
553 | } |
554 | b++; | |
f92523e3 PM |
555 | if (!isspace(*b)) |
556 | return -EINVAL; | |
08ce5f16 SH |
557 | b++; |
558 | if (*b == '*') { | |
db9aeca9 | 559 | ex.major = ~0; |
08ce5f16 SH |
560 | b++; |
561 | } else if (isdigit(*b)) { | |
26fd8405 AR |
562 | memset(temp, 0, sizeof(temp)); |
563 | for (count = 0; count < sizeof(temp) - 1; count++) { | |
564 | temp[count] = *b; | |
565 | b++; | |
566 | if (!isdigit(*b)) | |
567 | break; | |
568 | } | |
569 | rc = kstrtou32(temp, 10, &ex.major); | |
570 | if (rc) | |
571 | return -EINVAL; | |
08ce5f16 | 572 | } else { |
f92523e3 | 573 | return -EINVAL; |
08ce5f16 | 574 | } |
f92523e3 PM |
575 | if (*b != ':') |
576 | return -EINVAL; | |
08ce5f16 SH |
577 | b++; |
578 | ||
579 | /* read minor */ | |
580 | if (*b == '*') { | |
db9aeca9 | 581 | ex.minor = ~0; |
08ce5f16 SH |
582 | b++; |
583 | } else if (isdigit(*b)) { | |
26fd8405 AR |
584 | memset(temp, 0, sizeof(temp)); |
585 | for (count = 0; count < sizeof(temp) - 1; count++) { | |
586 | temp[count] = *b; | |
587 | b++; | |
588 | if (!isdigit(*b)) | |
589 | break; | |
590 | } | |
591 | rc = kstrtou32(temp, 10, &ex.minor); | |
592 | if (rc) | |
593 | return -EINVAL; | |
08ce5f16 | 594 | } else { |
f92523e3 | 595 | return -EINVAL; |
08ce5f16 | 596 | } |
f92523e3 PM |
597 | if (!isspace(*b)) |
598 | return -EINVAL; | |
08ce5f16 SH |
599 | for (b++, count = 0; count < 3; count++, b++) { |
600 | switch (*b) { | |
601 | case 'r': | |
db9aeca9 | 602 | ex.access |= ACC_READ; |
08ce5f16 SH |
603 | break; |
604 | case 'w': | |
db9aeca9 | 605 | ex.access |= ACC_WRITE; |
08ce5f16 SH |
606 | break; |
607 | case 'm': | |
db9aeca9 | 608 | ex.access |= ACC_MKNOD; |
08ce5f16 SH |
609 | break; |
610 | case '\n': | |
611 | case '\0': | |
612 | count = 3; | |
613 | break; | |
614 | default: | |
f92523e3 | 615 | return -EINVAL; |
08ce5f16 SH |
616 | } |
617 | } | |
618 | ||
08ce5f16 SH |
619 | switch (filetype) { |
620 | case DEVCG_ALLOW: | |
db9aeca9 | 621 | if (!parent_has_perm(devcgroup, &ex)) |
f92523e3 | 622 | return -EPERM; |
ad676077 AR |
623 | /* |
624 | * If the default policy is to allow by default, try to remove | |
625 | * an matching exception instead. And be silent about it: we | |
626 | * don't want to break compatibility | |
627 | */ | |
5b7aa7d5 | 628 | if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
db9aeca9 | 629 | dev_exception_rm(devcgroup, &ex); |
ad676077 AR |
630 | return 0; |
631 | } | |
bd2953eb AR |
632 | rc = dev_exception_add(devcgroup, &ex); |
633 | break; | |
08ce5f16 | 634 | case DEVCG_DENY: |
ad676077 AR |
635 | /* |
636 | * If the default policy is to deny by default, try to remove | |
637 | * an matching exception instead. And be silent about it: we | |
638 | * don't want to break compatibility | |
639 | */ | |
bd2953eb | 640 | if (devcgroup->behavior == DEVCG_DEFAULT_DENY) |
db9aeca9 | 641 | dev_exception_rm(devcgroup, &ex); |
bd2953eb AR |
642 | else |
643 | rc = dev_exception_add(devcgroup, &ex); | |
644 | ||
645 | if (rc) | |
646 | break; | |
647 | /* we only propagate new restrictions */ | |
648 | rc = propagate_exception(devcgroup, &ex); | |
649 | break; | |
08ce5f16 | 650 | default: |
bd2953eb | 651 | rc = -EINVAL; |
08ce5f16 | 652 | } |
bd2953eb | 653 | return rc; |
f92523e3 | 654 | } |
08ce5f16 | 655 | |
182446d0 TH |
656 | static int devcgroup_access_write(struct cgroup_subsys_state *css, |
657 | struct cftype *cft, const char *buffer) | |
f92523e3 PM |
658 | { |
659 | int retval; | |
b4046f00 LZ |
660 | |
661 | mutex_lock(&devcgroup_mutex); | |
182446d0 | 662 | retval = devcgroup_update_access(css_to_devcgroup(css), |
f92523e3 | 663 | cft->private, buffer); |
b4046f00 | 664 | mutex_unlock(&devcgroup_mutex); |
08ce5f16 SH |
665 | return retval; |
666 | } | |
667 | ||
668 | static struct cftype dev_cgroup_files[] = { | |
669 | { | |
670 | .name = "allow", | |
f92523e3 | 671 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
672 | .private = DEVCG_ALLOW, |
673 | }, | |
674 | { | |
675 | .name = "deny", | |
f92523e3 | 676 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
677 | .private = DEVCG_DENY, |
678 | }, | |
29486df3 SH |
679 | { |
680 | .name = "list", | |
2da8ca82 | 681 | .seq_show = devcgroup_seq_show, |
29486df3 SH |
682 | .private = DEVCG_LIST, |
683 | }, | |
4baf6e33 | 684 | { } /* terminate */ |
08ce5f16 SH |
685 | }; |
686 | ||
08ce5f16 SH |
687 | struct cgroup_subsys devices_subsys = { |
688 | .name = "devices", | |
92fb9748 TH |
689 | .css_alloc = devcgroup_css_alloc, |
690 | .css_free = devcgroup_css_free, | |
1909554c AR |
691 | .css_online = devcgroup_online, |
692 | .css_offline = devcgroup_offline, | |
08ce5f16 | 693 | .subsys_id = devices_subsys_id, |
4baf6e33 | 694 | .base_cftypes = dev_cgroup_files, |
08ce5f16 SH |
695 | }; |
696 | ||
ad676077 AR |
697 | /** |
698 | * __devcgroup_check_permission - checks if an inode operation is permitted | |
699 | * @dev_cgroup: the dev cgroup to be tested against | |
700 | * @type: device type | |
701 | * @major: device major number | |
702 | * @minor: device minor number | |
703 | * @access: combination of ACC_WRITE, ACC_READ and ACC_MKNOD | |
704 | * | |
705 | * returns 0 on success, -EPERM case the operation is not permitted | |
706 | */ | |
8c9506d1 | 707 | static int __devcgroup_check_permission(short type, u32 major, u32 minor, |
ad676077 | 708 | short access) |
08ce5f16 | 709 | { |
8c9506d1 | 710 | struct dev_cgroup *dev_cgroup; |
db9aeca9 | 711 | struct dev_exception_item ex; |
ad676077 | 712 | int rc; |
36fd71d2 | 713 | |
db9aeca9 AR |
714 | memset(&ex, 0, sizeof(ex)); |
715 | ex.type = type; | |
716 | ex.major = major; | |
717 | ex.minor = minor; | |
718 | ex.access = access; | |
36fd71d2 | 719 | |
ad676077 | 720 | rcu_read_lock(); |
8c9506d1 | 721 | dev_cgroup = task_devcgroup(current); |
c39a2a30 | 722 | rc = may_access(dev_cgroup, &ex, dev_cgroup->behavior); |
ad676077 | 723 | rcu_read_unlock(); |
cd500819 | 724 | |
ad676077 AR |
725 | if (!rc) |
726 | return -EPERM; | |
36fd71d2 | 727 | |
ad676077 AR |
728 | return 0; |
729 | } | |
08ce5f16 | 730 | |
ad676077 AR |
731 | int __devcgroup_inode_permission(struct inode *inode, int mask) |
732 | { | |
ad676077 AR |
733 | short type, access = 0; |
734 | ||
735 | if (S_ISBLK(inode->i_mode)) | |
736 | type = DEV_BLOCK; | |
737 | if (S_ISCHR(inode->i_mode)) | |
738 | type = DEV_CHAR; | |
739 | if (mask & MAY_WRITE) | |
740 | access |= ACC_WRITE; | |
741 | if (mask & MAY_READ) | |
742 | access |= ACC_READ; | |
743 | ||
8c9506d1 JS |
744 | return __devcgroup_check_permission(type, imajor(inode), iminor(inode), |
745 | access); | |
08ce5f16 SH |
746 | } |
747 | ||
748 | int devcgroup_inode_mknod(int mode, dev_t dev) | |
749 | { | |
ad676077 | 750 | short type; |
08ce5f16 | 751 | |
0b82ac37 SH |
752 | if (!S_ISBLK(mode) && !S_ISCHR(mode)) |
753 | return 0; | |
754 | ||
ad676077 AR |
755 | if (S_ISBLK(mode)) |
756 | type = DEV_BLOCK; | |
757 | else | |
758 | type = DEV_CHAR; | |
36fd71d2 | 759 | |
8c9506d1 JS |
760 | return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev), |
761 | ACC_MKNOD); | |
36fd71d2 | 762 | |
08ce5f16 | 763 | } |