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 | ||
08ce5f16 SH |
188 | /* |
189 | * called from kernel/cgroup.c with cgroup_lock() held. | |
190 | */ | |
92fb9748 | 191 | static struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup) |
08ce5f16 SH |
192 | { |
193 | struct dev_cgroup *dev_cgroup, *parent_dev_cgroup; | |
194 | struct cgroup *parent_cgroup; | |
195 | int ret; | |
196 | ||
197 | dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL); | |
198 | if (!dev_cgroup) | |
199 | return ERR_PTR(-ENOMEM); | |
db9aeca9 | 200 | INIT_LIST_HEAD(&dev_cgroup->exceptions); |
08ce5f16 SH |
201 | parent_cgroup = cgroup->parent; |
202 | ||
ad676077 | 203 | if (parent_cgroup == NULL) |
5b7aa7d5 | 204 | dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW; |
ad676077 | 205 | else { |
08ce5f16 | 206 | parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup); |
b4046f00 | 207 | mutex_lock(&devcgroup_mutex); |
db9aeca9 AR |
208 | ret = dev_exceptions_copy(&dev_cgroup->exceptions, |
209 | &parent_dev_cgroup->exceptions); | |
5b7aa7d5 | 210 | dev_cgroup->behavior = parent_dev_cgroup->behavior; |
b4046f00 | 211 | mutex_unlock(&devcgroup_mutex); |
08ce5f16 SH |
212 | if (ret) { |
213 | kfree(dev_cgroup); | |
214 | return ERR_PTR(ret); | |
215 | } | |
216 | } | |
217 | ||
08ce5f16 SH |
218 | return &dev_cgroup->css; |
219 | } | |
220 | ||
92fb9748 | 221 | static void devcgroup_css_free(struct cgroup *cgroup) |
08ce5f16 SH |
222 | { |
223 | struct dev_cgroup *dev_cgroup; | |
08ce5f16 SH |
224 | |
225 | dev_cgroup = cgroup_to_devcgroup(cgroup); | |
53eb8c82 | 226 | __dev_exception_clean(dev_cgroup); |
08ce5f16 SH |
227 | kfree(dev_cgroup); |
228 | } | |
229 | ||
230 | #define DEVCG_ALLOW 1 | |
231 | #define DEVCG_DENY 2 | |
29486df3 SH |
232 | #define DEVCG_LIST 3 |
233 | ||
17d213f8 | 234 | #define MAJMINLEN 13 |
29486df3 | 235 | #define ACCLEN 4 |
08ce5f16 SH |
236 | |
237 | static void set_access(char *acc, short access) | |
238 | { | |
239 | int idx = 0; | |
29486df3 | 240 | memset(acc, 0, ACCLEN); |
08ce5f16 SH |
241 | if (access & ACC_READ) |
242 | acc[idx++] = 'r'; | |
243 | if (access & ACC_WRITE) | |
244 | acc[idx++] = 'w'; | |
245 | if (access & ACC_MKNOD) | |
246 | acc[idx++] = 'm'; | |
247 | } | |
248 | ||
249 | static char type_to_char(short type) | |
250 | { | |
251 | if (type == DEV_ALL) | |
252 | return 'a'; | |
253 | if (type == DEV_CHAR) | |
254 | return 'c'; | |
255 | if (type == DEV_BLOCK) | |
256 | return 'b'; | |
257 | return 'X'; | |
258 | } | |
259 | ||
29486df3 | 260 | static void set_majmin(char *str, unsigned m) |
08ce5f16 | 261 | { |
08ce5f16 | 262 | if (m == ~0) |
7759fc9d | 263 | strcpy(str, "*"); |
08ce5f16 | 264 | else |
7759fc9d | 265 | sprintf(str, "%u", m); |
08ce5f16 SH |
266 | } |
267 | ||
29486df3 SH |
268 | static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft, |
269 | struct seq_file *m) | |
08ce5f16 | 270 | { |
29486df3 | 271 | struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup); |
db9aeca9 | 272 | struct dev_exception_item *ex; |
29486df3 | 273 | char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; |
08ce5f16 | 274 | |
4efd1a1b | 275 | rcu_read_lock(); |
ad676077 AR |
276 | /* |
277 | * To preserve the compatibility: | |
278 | * - Only show the "all devices" when the default policy is to allow | |
279 | * - List the exceptions in case the default policy is to deny | |
280 | * This way, the file remains as a "whitelist of devices" | |
281 | */ | |
5b7aa7d5 | 282 | if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
ad676077 AR |
283 | set_access(acc, ACC_MASK); |
284 | set_majmin(maj, ~0); | |
285 | set_majmin(min, ~0); | |
286 | seq_printf(m, "%c %s:%s %s\n", type_to_char(DEV_ALL), | |
29486df3 | 287 | maj, min, acc); |
ad676077 | 288 | } else { |
db9aeca9 AR |
289 | list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) { |
290 | set_access(acc, ex->access); | |
291 | set_majmin(maj, ex->major); | |
292 | set_majmin(min, ex->minor); | |
293 | seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type), | |
ad676077 AR |
294 | maj, min, acc); |
295 | } | |
08ce5f16 | 296 | } |
4efd1a1b | 297 | rcu_read_unlock(); |
08ce5f16 | 298 | |
29486df3 | 299 | return 0; |
08ce5f16 SH |
300 | } |
301 | ||
ad676077 | 302 | /** |
db9aeca9 AR |
303 | * may_access - verifies if a new exception is part of what is allowed |
304 | * by a dev cgroup based on the default policy + | |
305 | * exceptions. This is used to make sure a child cgroup | |
306 | * won't have more privileges than its parent or to | |
307 | * verify if a certain access is allowed. | |
ad676077 | 308 | * @dev_cgroup: dev cgroup to be tested against |
db9aeca9 | 309 | * @refex: new exception |
c39a2a30 | 310 | * @behavior: behavior of the exception |
08ce5f16 | 311 | */ |
26898fdf | 312 | static bool may_access(struct dev_cgroup *dev_cgroup, |
c39a2a30 AR |
313 | struct dev_exception_item *refex, |
314 | enum devcg_behavior behavior) | |
08ce5f16 | 315 | { |
db9aeca9 | 316 | struct dev_exception_item *ex; |
ad676077 | 317 | bool match = false; |
08ce5f16 | 318 | |
4b1c7840 TH |
319 | rcu_lockdep_assert(rcu_read_lock_held() || |
320 | lockdep_is_held(&devcgroup_mutex), | |
321 | "device_cgroup::may_access() called without proper synchronization"); | |
322 | ||
201e72ac | 323 | list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) { |
db9aeca9 | 324 | if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) |
08ce5f16 | 325 | continue; |
db9aeca9 | 326 | if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR)) |
08ce5f16 | 327 | continue; |
db9aeca9 | 328 | if (ex->major != ~0 && ex->major != refex->major) |
08ce5f16 | 329 | continue; |
db9aeca9 | 330 | if (ex->minor != ~0 && ex->minor != refex->minor) |
08ce5f16 | 331 | continue; |
db9aeca9 | 332 | if (refex->access & (~ex->access)) |
08ce5f16 | 333 | continue; |
ad676077 AR |
334 | match = true; |
335 | break; | |
08ce5f16 | 336 | } |
ad676077 | 337 | |
c39a2a30 AR |
338 | if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
339 | if (behavior == DEVCG_DEFAULT_ALLOW) { | |
340 | /* the exception will deny access to certain devices */ | |
341 | return true; | |
342 | } else { | |
343 | /* the exception will allow access to certain devices */ | |
344 | if (match) | |
345 | /* | |
346 | * a new exception allowing access shouldn't | |
347 | * match an parent's exception | |
348 | */ | |
349 | return false; | |
26898fdf | 350 | return true; |
c39a2a30 | 351 | } |
26898fdf | 352 | } else { |
c39a2a30 AR |
353 | /* only behavior == DEVCG_DEFAULT_DENY allowed here */ |
354 | if (match) | |
355 | /* parent has an exception that matches the proposed */ | |
26898fdf | 356 | return true; |
c39a2a30 AR |
357 | else |
358 | return false; | |
26898fdf AR |
359 | } |
360 | return false; | |
08ce5f16 SH |
361 | } |
362 | ||
363 | /* | |
364 | * parent_has_perm: | |
db9aeca9 | 365 | * when adding a new allow rule to a device exception list, the rule |
08ce5f16 SH |
366 | * must be allowed in the parent device |
367 | */ | |
f92523e3 | 368 | static int parent_has_perm(struct dev_cgroup *childcg, |
db9aeca9 | 369 | struct dev_exception_item *ex) |
08ce5f16 | 370 | { |
f92523e3 | 371 | struct cgroup *pcg = childcg->css.cgroup->parent; |
08ce5f16 | 372 | struct dev_cgroup *parent; |
08ce5f16 SH |
373 | |
374 | if (!pcg) | |
375 | return 1; | |
376 | parent = cgroup_to_devcgroup(pcg); | |
c39a2a30 | 377 | return may_access(parent, ex, childcg->behavior); |
08ce5f16 SH |
378 | } |
379 | ||
4cef7299 AR |
380 | /** |
381 | * may_allow_all - checks if it's possible to change the behavior to | |
382 | * allow based on parent's rules. | |
383 | * @parent: device cgroup's parent | |
384 | * returns: != 0 in case it's allowed, 0 otherwise | |
385 | */ | |
386 | static inline int may_allow_all(struct dev_cgroup *parent) | |
387 | { | |
64e10477 AR |
388 | if (!parent) |
389 | return 1; | |
4cef7299 AR |
390 | return parent->behavior == DEVCG_DEFAULT_ALLOW; |
391 | } | |
392 | ||
08ce5f16 | 393 | /* |
db9aeca9 | 394 | * Modify the exception list using allow/deny rules. |
08ce5f16 SH |
395 | * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD |
396 | * so we can give a container CAP_MKNOD to let it create devices but not | |
db9aeca9 | 397 | * modify the exception list. |
08ce5f16 SH |
398 | * It seems likely we'll want to add a CAP_CONTAINER capability to allow |
399 | * us to also grant CAP_SYS_ADMIN to containers without giving away the | |
db9aeca9 | 400 | * device exception list controls, but for now we'll stick with CAP_SYS_ADMIN |
08ce5f16 SH |
401 | * |
402 | * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting | |
403 | * new access is only allowed if you're in the top-level cgroup, or your | |
404 | * parent cgroup has the access you're asking for. | |
405 | */ | |
f92523e3 PM |
406 | static int devcgroup_update_access(struct dev_cgroup *devcgroup, |
407 | int filetype, const char *buffer) | |
08ce5f16 | 408 | { |
f92523e3 | 409 | const char *b; |
26fd8405 | 410 | char temp[12]; /* 11 + 1 characters needed for a u32 */ |
c39a2a30 | 411 | int count, rc = 0; |
db9aeca9 | 412 | struct dev_exception_item ex; |
4cef7299 | 413 | struct cgroup *p = devcgroup->css.cgroup; |
64e10477 | 414 | struct dev_cgroup *parent = NULL; |
08ce5f16 SH |
415 | |
416 | if (!capable(CAP_SYS_ADMIN)) | |
417 | return -EPERM; | |
418 | ||
64e10477 AR |
419 | if (p->parent) |
420 | parent = cgroup_to_devcgroup(p->parent); | |
421 | ||
db9aeca9 | 422 | memset(&ex, 0, sizeof(ex)); |
08ce5f16 SH |
423 | b = buffer; |
424 | ||
425 | switch (*b) { | |
426 | case 'a': | |
ad676077 AR |
427 | switch (filetype) { |
428 | case DEVCG_ALLOW: | |
4cef7299 | 429 | if (!may_allow_all(parent)) |
ad676077 | 430 | return -EPERM; |
db9aeca9 | 431 | dev_exception_clean(devcgroup); |
64e10477 AR |
432 | devcgroup->behavior = DEVCG_DEFAULT_ALLOW; |
433 | if (!parent) | |
434 | break; | |
435 | ||
4cef7299 AR |
436 | rc = dev_exceptions_copy(&devcgroup->exceptions, |
437 | &parent->exceptions); | |
438 | if (rc) | |
439 | return rc; | |
ad676077 AR |
440 | break; |
441 | case DEVCG_DENY: | |
db9aeca9 | 442 | dev_exception_clean(devcgroup); |
5b7aa7d5 | 443 | devcgroup->behavior = DEVCG_DEFAULT_DENY; |
ad676077 AR |
444 | break; |
445 | default: | |
446 | return -EINVAL; | |
447 | } | |
448 | return 0; | |
08ce5f16 | 449 | case 'b': |
db9aeca9 | 450 | ex.type = DEV_BLOCK; |
08ce5f16 SH |
451 | break; |
452 | case 'c': | |
db9aeca9 | 453 | ex.type = DEV_CHAR; |
08ce5f16 SH |
454 | break; |
455 | default: | |
f92523e3 | 456 | return -EINVAL; |
08ce5f16 SH |
457 | } |
458 | b++; | |
f92523e3 PM |
459 | if (!isspace(*b)) |
460 | return -EINVAL; | |
08ce5f16 SH |
461 | b++; |
462 | if (*b == '*') { | |
db9aeca9 | 463 | ex.major = ~0; |
08ce5f16 SH |
464 | b++; |
465 | } else if (isdigit(*b)) { | |
26fd8405 AR |
466 | memset(temp, 0, sizeof(temp)); |
467 | for (count = 0; count < sizeof(temp) - 1; count++) { | |
468 | temp[count] = *b; | |
469 | b++; | |
470 | if (!isdigit(*b)) | |
471 | break; | |
472 | } | |
473 | rc = kstrtou32(temp, 10, &ex.major); | |
474 | if (rc) | |
475 | return -EINVAL; | |
08ce5f16 | 476 | } else { |
f92523e3 | 477 | return -EINVAL; |
08ce5f16 | 478 | } |
f92523e3 PM |
479 | if (*b != ':') |
480 | return -EINVAL; | |
08ce5f16 SH |
481 | b++; |
482 | ||
483 | /* read minor */ | |
484 | if (*b == '*') { | |
db9aeca9 | 485 | ex.minor = ~0; |
08ce5f16 SH |
486 | b++; |
487 | } else if (isdigit(*b)) { | |
26fd8405 AR |
488 | memset(temp, 0, sizeof(temp)); |
489 | for (count = 0; count < sizeof(temp) - 1; count++) { | |
490 | temp[count] = *b; | |
491 | b++; | |
492 | if (!isdigit(*b)) | |
493 | break; | |
494 | } | |
495 | rc = kstrtou32(temp, 10, &ex.minor); | |
496 | if (rc) | |
497 | return -EINVAL; | |
08ce5f16 | 498 | } else { |
f92523e3 | 499 | return -EINVAL; |
08ce5f16 | 500 | } |
f92523e3 PM |
501 | if (!isspace(*b)) |
502 | return -EINVAL; | |
08ce5f16 SH |
503 | for (b++, count = 0; count < 3; count++, b++) { |
504 | switch (*b) { | |
505 | case 'r': | |
db9aeca9 | 506 | ex.access |= ACC_READ; |
08ce5f16 SH |
507 | break; |
508 | case 'w': | |
db9aeca9 | 509 | ex.access |= ACC_WRITE; |
08ce5f16 SH |
510 | break; |
511 | case 'm': | |
db9aeca9 | 512 | ex.access |= ACC_MKNOD; |
08ce5f16 SH |
513 | break; |
514 | case '\n': | |
515 | case '\0': | |
516 | count = 3; | |
517 | break; | |
518 | default: | |
f92523e3 | 519 | return -EINVAL; |
08ce5f16 SH |
520 | } |
521 | } | |
522 | ||
08ce5f16 SH |
523 | switch (filetype) { |
524 | case DEVCG_ALLOW: | |
db9aeca9 | 525 | if (!parent_has_perm(devcgroup, &ex)) |
f92523e3 | 526 | return -EPERM; |
ad676077 AR |
527 | /* |
528 | * If the default policy is to allow by default, try to remove | |
529 | * an matching exception instead. And be silent about it: we | |
530 | * don't want to break compatibility | |
531 | */ | |
5b7aa7d5 | 532 | if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { |
db9aeca9 | 533 | dev_exception_rm(devcgroup, &ex); |
ad676077 AR |
534 | return 0; |
535 | } | |
db9aeca9 | 536 | return dev_exception_add(devcgroup, &ex); |
08ce5f16 | 537 | case DEVCG_DENY: |
ad676077 AR |
538 | /* |
539 | * If the default policy is to deny by default, try to remove | |
540 | * an matching exception instead. And be silent about it: we | |
541 | * don't want to break compatibility | |
542 | */ | |
5b7aa7d5 | 543 | if (devcgroup->behavior == DEVCG_DEFAULT_DENY) { |
db9aeca9 | 544 | dev_exception_rm(devcgroup, &ex); |
ad676077 AR |
545 | return 0; |
546 | } | |
db9aeca9 | 547 | return dev_exception_add(devcgroup, &ex); |
08ce5f16 | 548 | default: |
f92523e3 | 549 | return -EINVAL; |
08ce5f16 | 550 | } |
f92523e3 PM |
551 | return 0; |
552 | } | |
08ce5f16 | 553 | |
f92523e3 PM |
554 | static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft, |
555 | const char *buffer) | |
556 | { | |
557 | int retval; | |
b4046f00 LZ |
558 | |
559 | mutex_lock(&devcgroup_mutex); | |
f92523e3 PM |
560 | retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp), |
561 | cft->private, buffer); | |
b4046f00 | 562 | mutex_unlock(&devcgroup_mutex); |
08ce5f16 SH |
563 | return retval; |
564 | } | |
565 | ||
566 | static struct cftype dev_cgroup_files[] = { | |
567 | { | |
568 | .name = "allow", | |
f92523e3 | 569 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
570 | .private = DEVCG_ALLOW, |
571 | }, | |
572 | { | |
573 | .name = "deny", | |
f92523e3 | 574 | .write_string = devcgroup_access_write, |
08ce5f16 SH |
575 | .private = DEVCG_DENY, |
576 | }, | |
29486df3 SH |
577 | { |
578 | .name = "list", | |
579 | .read_seq_string = devcgroup_seq_read, | |
580 | .private = DEVCG_LIST, | |
581 | }, | |
4baf6e33 | 582 | { } /* terminate */ |
08ce5f16 SH |
583 | }; |
584 | ||
08ce5f16 SH |
585 | struct cgroup_subsys devices_subsys = { |
586 | .name = "devices", | |
587 | .can_attach = devcgroup_can_attach, | |
92fb9748 TH |
588 | .css_alloc = devcgroup_css_alloc, |
589 | .css_free = devcgroup_css_free, | |
08ce5f16 | 590 | .subsys_id = devices_subsys_id, |
4baf6e33 | 591 | .base_cftypes = dev_cgroup_files, |
8c7f6edb TH |
592 | |
593 | /* | |
594 | * While devices cgroup has the rudimentary hierarchy support which | |
595 | * checks the parent's restriction, it doesn't properly propagates | |
596 | * config changes in ancestors to their descendents. A child | |
597 | * should only be allowed to add more restrictions to the parent's | |
598 | * configuration. Fix it and remove the following. | |
599 | */ | |
600 | .broken_hierarchy = true, | |
08ce5f16 SH |
601 | }; |
602 | ||
ad676077 AR |
603 | /** |
604 | * __devcgroup_check_permission - checks if an inode operation is permitted | |
605 | * @dev_cgroup: the dev cgroup to be tested against | |
606 | * @type: device type | |
607 | * @major: device major number | |
608 | * @minor: device minor number | |
609 | * @access: combination of ACC_WRITE, ACC_READ and ACC_MKNOD | |
610 | * | |
611 | * returns 0 on success, -EPERM case the operation is not permitted | |
612 | */ | |
8c9506d1 | 613 | static int __devcgroup_check_permission(short type, u32 major, u32 minor, |
ad676077 | 614 | short access) |
08ce5f16 | 615 | { |
8c9506d1 | 616 | struct dev_cgroup *dev_cgroup; |
db9aeca9 | 617 | struct dev_exception_item ex; |
ad676077 | 618 | int rc; |
36fd71d2 | 619 | |
db9aeca9 AR |
620 | memset(&ex, 0, sizeof(ex)); |
621 | ex.type = type; | |
622 | ex.major = major; | |
623 | ex.minor = minor; | |
624 | ex.access = access; | |
36fd71d2 | 625 | |
ad676077 | 626 | rcu_read_lock(); |
8c9506d1 | 627 | dev_cgroup = task_devcgroup(current); |
c39a2a30 | 628 | rc = may_access(dev_cgroup, &ex, dev_cgroup->behavior); |
ad676077 | 629 | rcu_read_unlock(); |
cd500819 | 630 | |
ad676077 AR |
631 | if (!rc) |
632 | return -EPERM; | |
36fd71d2 | 633 | |
ad676077 AR |
634 | return 0; |
635 | } | |
08ce5f16 | 636 | |
ad676077 AR |
637 | int __devcgroup_inode_permission(struct inode *inode, int mask) |
638 | { | |
ad676077 AR |
639 | short type, access = 0; |
640 | ||
641 | if (S_ISBLK(inode->i_mode)) | |
642 | type = DEV_BLOCK; | |
643 | if (S_ISCHR(inode->i_mode)) | |
644 | type = DEV_CHAR; | |
645 | if (mask & MAY_WRITE) | |
646 | access |= ACC_WRITE; | |
647 | if (mask & MAY_READ) | |
648 | access |= ACC_READ; | |
649 | ||
8c9506d1 JS |
650 | return __devcgroup_check_permission(type, imajor(inode), iminor(inode), |
651 | access); | |
08ce5f16 SH |
652 | } |
653 | ||
654 | int devcgroup_inode_mknod(int mode, dev_t dev) | |
655 | { | |
ad676077 | 656 | short type; |
08ce5f16 | 657 | |
0b82ac37 SH |
658 | if (!S_ISBLK(mode) && !S_ISCHR(mode)) |
659 | return 0; | |
660 | ||
ad676077 AR |
661 | if (S_ISBLK(mode)) |
662 | type = DEV_BLOCK; | |
663 | else | |
664 | type = DEV_CHAR; | |
36fd71d2 | 665 | |
8c9506d1 JS |
666 | return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev), |
667 | ACC_MKNOD); | |
36fd71d2 | 668 | |
08ce5f16 | 669 | } |