blob: d9d69e6930edf5266e1c2bc77fff39528fee5467 [file] [log] [blame]
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -07001/*
Lai Jiangshan47c59802008-10-18 20:28:07 -07002 * device_cgroup.c - device cgroup subsystem
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -07003 *
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090013#include <linux/slab.h>
Lai Jiangshan47c59802008-10-18 20:28:07 -070014#include <linux/rcupdate.h>
Li Zefanb4046f02009-04-02 16:57:32 -070015#include <linux/mutex.h>
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070016
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
Li Zefanb4046f02009-04-02 16:57:32 -070026static DEFINE_MUTEX(devcgroup_mutex);
27
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -050028enum devcg_behavior {
29 DEVCG_DEFAULT_NONE,
30 DEVCG_DEFAULT_ALLOW,
31 DEVCG_DEFAULT_DENY,
32};
33
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070034/*
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070035 * exception list locking rules:
Li Zefanb4046f02009-04-02 16:57:32 -070036 * hold devcgroup_mutex for update/read.
Lai Jiangshan47c59802008-10-18 20:28:07 -070037 * hold rcu_read_lock() for read.
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070038 */
39
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070040struct dev_exception_item {
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070041 u32 major, minor;
42 short type;
43 short access;
44 struct list_head list;
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -070045 struct rcu_head rcu;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070046};
47
48struct dev_cgroup {
49 struct cgroup_subsys_state css;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070050 struct list_head exceptions;
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -050051 enum devcg_behavior behavior;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070052};
53
Pavel Emelyanovb66862f2008-06-05 22:46:24 -070054static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
55{
Tejun Heoa7c6d552013-08-08 20:11:23 -040056 return s ? container_of(s, struct dev_cgroup, css) : NULL;
Pavel Emelyanovb66862f2008-06-05 22:46:24 -070057}
58
Paul Menagef92523e2008-07-25 01:47:03 -070059static inline struct dev_cgroup *task_devcgroup(struct task_struct *task)
60{
Tejun Heo073219e2014-02-08 10:36:58 -050061 return css_to_devcgroup(task_css(task, devices_cgrp_id));
Paul Menagef92523e2008-07-25 01:47:03 -070062}
63
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070064/*
Li Zefanb4046f02009-04-02 16:57:32 -070065 * called under devcgroup_mutex
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070066 */
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070067static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070068{
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070069 struct dev_exception_item *ex, *tmp, *new;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070070
Tejun Heo4b1c7842012-11-06 09:16:53 -080071 lockdep_assert_held(&devcgroup_mutex);
72
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070073 list_for_each_entry(ex, orig, list) {
74 new = kmemdup(ex, sizeof(*ex), GFP_KERNEL);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070075 if (!new)
76 goto free_and_exit;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070077 list_add_tail(&new->list, dest);
78 }
79
80 return 0;
81
82free_and_exit:
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070083 list_for_each_entry_safe(ex, tmp, dest, list) {
84 list_del(&ex->list);
85 kfree(ex);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070086 }
87 return -ENOMEM;
88}
89
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070090/*
Li Zefanb4046f02009-04-02 16:57:32 -070091 * called under devcgroup_mutex
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070092 */
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070093static int dev_exception_add(struct dev_cgroup *dev_cgroup,
94 struct dev_exception_item *ex)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070095{
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -070096 struct dev_exception_item *excopy, *walk;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070097
Tejun Heo4b1c7842012-11-06 09:16:53 -080098 lockdep_assert_held(&devcgroup_mutex);
99
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700100 excopy = kmemdup(ex, sizeof(*ex), GFP_KERNEL);
101 if (!excopy)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700102 return -ENOMEM;
103
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700104 list_for_each_entry(walk, &dev_cgroup->exceptions, list) {
105 if (walk->type != ex->type)
Pavel Emelyanovd1ee2972008-06-05 22:46:28 -0700106 continue;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700107 if (walk->major != ex->major)
Pavel Emelyanovd1ee2972008-06-05 22:46:28 -0700108 continue;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700109 if (walk->minor != ex->minor)
Pavel Emelyanovd1ee2972008-06-05 22:46:28 -0700110 continue;
111
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700112 walk->access |= ex->access;
113 kfree(excopy);
114 excopy = NULL;
Pavel Emelyanovd1ee2972008-06-05 22:46:28 -0700115 }
116
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700117 if (excopy != NULL)
118 list_add_tail_rcu(&excopy->list, &dev_cgroup->exceptions);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700119 return 0;
120}
121
122/*
Li Zefanb4046f02009-04-02 16:57:32 -0700123 * called under devcgroup_mutex
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700124 */
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700125static void dev_exception_rm(struct dev_cgroup *dev_cgroup,
126 struct dev_exception_item *ex)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700127{
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700128 struct dev_exception_item *walk, *tmp;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700129
Tejun Heo4b1c7842012-11-06 09:16:53 -0800130 lockdep_assert_held(&devcgroup_mutex);
131
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700132 list_for_each_entry_safe(walk, tmp, &dev_cgroup->exceptions, list) {
133 if (walk->type != ex->type)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700134 continue;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700135 if (walk->major != ex->major)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700136 continue;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700137 if (walk->minor != ex->minor)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700138 continue;
139
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700140 walk->access &= ~ex->access;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700141 if (!walk->access) {
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700142 list_del_rcu(&walk->list);
Lai Jiangshan6034f7e2011-03-15 18:07:57 +0800143 kfree_rcu(walk, rcu);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700144 }
145 }
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700146}
147
Jerry Snitselaar53eb8c82013-02-21 16:41:31 -0800148static void __dev_exception_clean(struct dev_cgroup *dev_cgroup)
149{
150 struct dev_exception_item *ex, *tmp;
151
152 list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
153 list_del_rcu(&ex->list);
154 kfree_rcu(ex, rcu);
155 }
156}
157
Aristeu Rozanski868539a2012-10-04 17:15:15 -0700158/**
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700159 * dev_exception_clean - frees all entries of the exception list
160 * @dev_cgroup: dev_cgroup with the exception list to be cleaned
Aristeu Rozanski868539a2012-10-04 17:15:15 -0700161 *
162 * called under devcgroup_mutex
163 */
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700164static void dev_exception_clean(struct dev_cgroup *dev_cgroup)
Aristeu Rozanski868539a2012-10-04 17:15:15 -0700165{
Tejun Heo4b1c7842012-11-06 09:16:53 -0800166 lockdep_assert_held(&devcgroup_mutex);
167
Jerry Snitselaar53eb8c82013-02-21 16:41:31 -0800168 __dev_exception_clean(dev_cgroup);
Aristeu Rozanski868539a2012-10-04 17:15:15 -0700169}
170
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500171static inline bool is_devcg_online(const struct dev_cgroup *devcg)
172{
173 return (devcg->behavior != DEVCG_DEFAULT_NONE);
174}
175
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500176/**
177 * devcgroup_online - initializes devcgroup's behavior and exceptions based on
178 * parent's
Tejun Heoeb954192013-08-08 20:11:23 -0400179 * @css: css getting online
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500180 * returns 0 in case of success, error code otherwise
181 */
Tejun Heoeb954192013-08-08 20:11:23 -0400182static int devcgroup_online(struct cgroup_subsys_state *css)
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500183{
Tejun Heoeb954192013-08-08 20:11:23 -0400184 struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
Tejun Heo5c9d5352014-05-16 13:22:48 -0400185 struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css->parent);
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500186 int ret = 0;
187
188 mutex_lock(&devcgroup_mutex);
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500189
190 if (parent_dev_cgroup == NULL)
191 dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW;
192 else {
193 ret = dev_exceptions_copy(&dev_cgroup->exceptions,
194 &parent_dev_cgroup->exceptions);
195 if (!ret)
196 dev_cgroup->behavior = parent_dev_cgroup->behavior;
197 }
198 mutex_unlock(&devcgroup_mutex);
199
200 return ret;
201}
202
Tejun Heoeb954192013-08-08 20:11:23 -0400203static void devcgroup_offline(struct cgroup_subsys_state *css)
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500204{
Tejun Heoeb954192013-08-08 20:11:23 -0400205 struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500206
207 mutex_lock(&devcgroup_mutex);
208 dev_cgroup->behavior = DEVCG_DEFAULT_NONE;
209 mutex_unlock(&devcgroup_mutex);
210}
211
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700212/*
213 * called from kernel/cgroup.c with cgroup_lock() held.
214 */
Tejun Heoeb954192013-08-08 20:11:23 -0400215static struct cgroup_subsys_state *
216devcgroup_css_alloc(struct cgroup_subsys_state *parent_css)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700217{
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500218 struct dev_cgroup *dev_cgroup;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700219
220 dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL);
221 if (!dev_cgroup)
222 return ERR_PTR(-ENOMEM);
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700223 INIT_LIST_HEAD(&dev_cgroup->exceptions);
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500224 dev_cgroup->behavior = DEVCG_DEFAULT_NONE;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700225
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700226 return &dev_cgroup->css;
227}
228
Tejun Heoeb954192013-08-08 20:11:23 -0400229static void devcgroup_css_free(struct cgroup_subsys_state *css)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700230{
Tejun Heoeb954192013-08-08 20:11:23 -0400231 struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700232
Jerry Snitselaar53eb8c82013-02-21 16:41:31 -0800233 __dev_exception_clean(dev_cgroup);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700234 kfree(dev_cgroup);
235}
236
237#define DEVCG_ALLOW 1
238#define DEVCG_DENY 2
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700239#define DEVCG_LIST 3
240
Li Zefan17d213f2008-07-13 12:14:02 -0700241#define MAJMINLEN 13
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700242#define ACCLEN 4
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700243
244static void set_access(char *acc, short access)
245{
246 int idx = 0;
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700247 memset(acc, 0, ACCLEN);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700248 if (access & ACC_READ)
249 acc[idx++] = 'r';
250 if (access & ACC_WRITE)
251 acc[idx++] = 'w';
252 if (access & ACC_MKNOD)
253 acc[idx++] = 'm';
254}
255
256static char type_to_char(short type)
257{
258 if (type == DEV_ALL)
259 return 'a';
260 if (type == DEV_CHAR)
261 return 'c';
262 if (type == DEV_BLOCK)
263 return 'b';
264 return 'X';
265}
266
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700267static void set_majmin(char *str, unsigned m)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700268{
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700269 if (m == ~0)
Li Zefan7759fc92008-07-25 01:47:08 -0700270 strcpy(str, "*");
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700271 else
Li Zefan7759fc92008-07-25 01:47:08 -0700272 sprintf(str, "%u", m);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700273}
274
Tejun Heo2da8ca82013-12-05 12:28:04 -0500275static int devcgroup_seq_show(struct seq_file *m, void *v)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700276{
Tejun Heo2da8ca82013-12-05 12:28:04 -0500277 struct dev_cgroup *devcgroup = css_to_devcgroup(seq_css(m));
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700278 struct dev_exception_item *ex;
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700279 char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN];
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700280
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700281 rcu_read_lock();
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700282 /*
283 * To preserve the compatibility:
284 * - Only show the "all devices" when the default policy is to allow
285 * - List the exceptions in case the default policy is to deny
286 * This way, the file remains as a "whitelist of devices"
287 */
Aristeu Rozanski5b7aa7d2012-10-25 13:37:38 -0700288 if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700289 set_access(acc, ACC_MASK);
290 set_majmin(maj, ~0);
291 set_majmin(min, ~0);
292 seq_printf(m, "%c %s:%s %s\n", type_to_char(DEV_ALL),
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700293 maj, min, acc);
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700294 } else {
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700295 list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) {
296 set_access(acc, ex->access);
297 set_majmin(maj, ex->major);
298 set_majmin(min, ex->minor);
299 seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type),
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700300 maj, min, acc);
301 }
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700302 }
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700303 rcu_read_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700304
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700305 return 0;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700306}
307
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700308/**
Aristeu Rozanskif5f3cf6f2014-04-24 15:33:21 -0400309 * match_exception - iterates the exception list trying to find a complete match
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400310 * @exceptions: list of exceptions
311 * @type: device type (DEV_BLOCK or DEV_CHAR)
312 * @major: device file major number, ~0 to match all
313 * @minor: device file minor number, ~0 to match all
314 * @access: permission mask (ACC_READ, ACC_WRITE, ACC_MKNOD)
315 *
Aristeu Rozanskif5f3cf6f2014-04-24 15:33:21 -0400316 * It is considered a complete match if an exception is found that will
317 * contain the entire range of provided parameters.
318 *
319 * Return: true in case it matches an exception completely
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700320 */
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400321static bool match_exception(struct list_head *exceptions, short type,
322 u32 major, u32 minor, short access)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700323{
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700324 struct dev_exception_item *ex;
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400325
326 list_for_each_entry_rcu(ex, exceptions, list) {
327 if ((type & DEV_BLOCK) && !(ex->type & DEV_BLOCK))
328 continue;
329 if ((type & DEV_CHAR) && !(ex->type & DEV_CHAR))
330 continue;
331 if (ex->major != ~0 && ex->major != major)
332 continue;
333 if (ex->minor != ~0 && ex->minor != minor)
334 continue;
335 /* provided access cannot have more than the exception rule */
336 if (access & (~ex->access))
337 continue;
338 return true;
339 }
340 return false;
341}
342
343/**
Aristeu Rozanskif5f3cf6f2014-04-24 15:33:21 -0400344 * match_exception_partial - iterates the exception list trying to find a partial match
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400345 * @exceptions: list of exceptions
346 * @type: device type (DEV_BLOCK or DEV_CHAR)
347 * @major: device file major number, ~0 to match all
348 * @minor: device file minor number, ~0 to match all
349 * @access: permission mask (ACC_READ, ACC_WRITE, ACC_MKNOD)
350 *
Aristeu Rozanskif5f3cf6f2014-04-24 15:33:21 -0400351 * It is considered a partial match if an exception's range is found to
352 * contain *any* of the devices specified by provided parameters. This is
353 * used to make sure no extra access is being granted that is forbidden by
354 * any of the exception list.
355 *
356 * Return: true in case the provided range mat matches an exception completely
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400357 */
358static bool match_exception_partial(struct list_head *exceptions, short type,
359 u32 major, u32 minor, short access)
360{
361 struct dev_exception_item *ex;
362
363 list_for_each_entry_rcu(ex, exceptions, list) {
364 if ((type & DEV_BLOCK) && !(ex->type & DEV_BLOCK))
365 continue;
366 if ((type & DEV_CHAR) && !(ex->type & DEV_CHAR))
367 continue;
368 /*
369 * We must be sure that both the exception and the provided
370 * range aren't masking all devices
371 */
372 if (ex->major != ~0 && major != ~0 && ex->major != major)
373 continue;
374 if (ex->minor != ~0 && minor != ~0 && ex->minor != minor)
375 continue;
376 /*
377 * In order to make sure the provided range isn't matching
378 * an exception, all its access bits shouldn't match the
379 * exception's access bits
380 */
381 if (!(access & ex->access))
382 continue;
383 return true;
384 }
385 return false;
386}
387
388/**
Aristeu Rozanskif5f3cf6f2014-04-24 15:33:21 -0400389 * verify_new_ex - verifies if a new exception is allowed by parent cgroup's permissions
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400390 * @dev_cgroup: dev cgroup to be tested against
391 * @refex: new exception
392 * @behavior: behavior of the exception's dev_cgroup
Aristeu Rozanskif5f3cf6f2014-04-24 15:33:21 -0400393 *
394 * This is used to make sure a child cgroup won't have more privileges
395 * than its parent
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400396 */
397static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
398 struct dev_exception_item *refex,
399 enum devcg_behavior behavior)
400{
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700401 bool match = false;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700402
Tejun Heo4b1c7842012-11-06 09:16:53 -0800403 rcu_lockdep_assert(rcu_read_lock_held() ||
404 lockdep_is_held(&devcgroup_mutex),
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400405 "device_cgroup:verify_new_ex called without proper synchronization");
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700406
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -0500407 if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
408 if (behavior == DEVCG_DEFAULT_ALLOW) {
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400409 /*
410 * new exception in the child doesn't matter, only
411 * adding extra restrictions
412 */
Aristeu Rozanski26898fd2013-02-15 11:55:44 -0500413 return true;
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -0500414 } else {
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400415 /*
416 * new exception in the child will add more devices
417 * that can be acessed, so it can't match any of
418 * parent's exceptions, even slightly
419 */
420 match = match_exception_partial(&dev_cgroup->exceptions,
421 refex->type,
422 refex->major,
423 refex->minor,
424 refex->access);
425
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -0500426 if (match)
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -0500427 return false;
428 return true;
429 }
Aristeu Rozanski26898fd2013-02-15 11:55:44 -0500430 } else {
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400431 /*
432 * Only behavior == DEVCG_DEFAULT_DENY allowed here, therefore
433 * the new exception will add access to more devices and must
434 * be contained completely in an parent's exception to be
435 * allowed
436 */
437 match = match_exception(&dev_cgroup->exceptions, refex->type,
438 refex->major, refex->minor,
439 refex->access);
440
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -0500441 if (match)
442 /* parent has an exception that matches the proposed */
Aristeu Rozanski26898fd2013-02-15 11:55:44 -0500443 return true;
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -0500444 else
445 return false;
Aristeu Rozanski26898fd2013-02-15 11:55:44 -0500446 }
447 return false;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700448}
449
450/*
451 * parent_has_perm:
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700452 * when adding a new allow rule to a device exception list, the rule
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700453 * must be allowed in the parent device
454 */
Paul Menagef92523e2008-07-25 01:47:03 -0700455static int parent_has_perm(struct dev_cgroup *childcg,
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700456 struct dev_exception_item *ex)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700457{
Tejun Heo5c9d5352014-05-16 13:22:48 -0400458 struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700459
Tejun Heo63876982013-08-08 20:11:23 -0400460 if (!parent)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700461 return 1;
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400462 return verify_new_ex(parent, ex, childcg->behavior);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700463}
464
Aristeu Rozanski4cef7292012-10-25 13:37:45 -0700465/**
Aristeu Rozanskid2c2b112014-05-05 11:18:59 -0400466 * parent_allows_removal - verify if it's ok to remove an exception
467 * @childcg: child cgroup from where the exception will be removed
468 * @ex: exception being removed
469 *
470 * When removing an exception in cgroups with default ALLOW policy, it must
471 * be checked if removing it will give the child cgroup more access than the
472 * parent.
473 *
474 * Return: true if it's ok to remove exception, false otherwise
475 */
476static bool parent_allows_removal(struct dev_cgroup *childcg,
477 struct dev_exception_item *ex)
478{
Tejun Heo5c9d5352014-05-16 13:22:48 -0400479 struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent);
Aristeu Rozanskid2c2b112014-05-05 11:18:59 -0400480
481 if (!parent)
482 return true;
483
484 /* It's always allowed to remove access to devices */
485 if (childcg->behavior == DEVCG_DEFAULT_DENY)
486 return true;
487
488 /*
489 * Make sure you're not removing part or a whole exception existing in
490 * the parent cgroup
491 */
492 return !match_exception_partial(&parent->exceptions, ex->type,
493 ex->major, ex->minor, ex->access);
494}
495
496/**
Aristeu Rozanski4cef7292012-10-25 13:37:45 -0700497 * may_allow_all - checks if it's possible to change the behavior to
498 * allow based on parent's rules.
499 * @parent: device cgroup's parent
500 * returns: != 0 in case it's allowed, 0 otherwise
501 */
502static inline int may_allow_all(struct dev_cgroup *parent)
503{
Aristeu Rozanski64e10472012-11-06 07:25:04 -0800504 if (!parent)
505 return 1;
Aristeu Rozanski4cef7292012-10-25 13:37:45 -0700506 return parent->behavior == DEVCG_DEFAULT_ALLOW;
507}
508
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500509/**
510 * revalidate_active_exceptions - walks through the active exception list and
511 * revalidates the exceptions based on parent's
512 * behavior and exceptions. The exceptions that
513 * are no longer valid will be removed.
514 * Called with devcgroup_mutex held.
515 * @devcg: cgroup which exceptions will be checked
516 *
517 * This is one of the three key functions for hierarchy implementation.
518 * This function is responsible for re-evaluating all the cgroup's active
519 * exceptions due to a parent's exception change.
520 * Refer to Documentation/cgroups/devices.txt for more details.
521 */
522static void revalidate_active_exceptions(struct dev_cgroup *devcg)
523{
524 struct dev_exception_item *ex;
525 struct list_head *this, *tmp;
526
527 list_for_each_safe(this, tmp, &devcg->exceptions) {
528 ex = container_of(this, struct dev_exception_item, list);
529 if (!parent_has_perm(devcg, ex))
530 dev_exception_rm(devcg, ex);
531 }
532}
533
534/**
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500535 * propagate_exception - propagates a new exception to the children
536 * @devcg_root: device cgroup that added a new exception
537 * @ex: new exception to be propagated
538 *
539 * returns: 0 in case of success, != 0 in case of error
540 */
541static int propagate_exception(struct dev_cgroup *devcg_root,
542 struct dev_exception_item *ex)
543{
Tejun Heo492eb212013-08-08 20:11:25 -0400544 struct cgroup_subsys_state *pos;
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500545 int rc = 0;
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500546
Tejun Heod591fb52013-05-24 10:55:38 +0900547 rcu_read_lock();
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500548
Tejun Heo492eb212013-08-08 20:11:25 -0400549 css_for_each_descendant_pre(pos, &devcg_root->css) {
550 struct dev_cgroup *devcg = css_to_devcgroup(pos);
Tejun Heod591fb52013-05-24 10:55:38 +0900551
552 /*
553 * Because devcgroup_mutex is held, no devcg will become
554 * online or offline during the tree walk (see on/offline
555 * methods), and online ones are safe to access outside RCU
556 * read lock without bumping refcnt.
557 */
Tejun Heobd8815a2013-08-08 20:11:27 -0400558 if (pos == &devcg_root->css || !is_devcg_online(devcg))
Tejun Heod591fb52013-05-24 10:55:38 +0900559 continue;
560
561 rcu_read_unlock();
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500562
563 /*
564 * in case both root's behavior and devcg is allow, a new
565 * restriction means adding to the exception list
566 */
567 if (devcg_root->behavior == DEVCG_DEFAULT_ALLOW &&
568 devcg->behavior == DEVCG_DEFAULT_ALLOW) {
569 rc = dev_exception_add(devcg, ex);
570 if (rc)
571 break;
572 } else {
573 /*
574 * in the other possible cases:
575 * root's behavior: allow, devcg's: deny
576 * root's behavior: deny, devcg's: deny
577 * the exception will be removed
578 */
579 dev_exception_rm(devcg, ex);
580 }
581 revalidate_active_exceptions(devcg);
582
Tejun Heod591fb52013-05-24 10:55:38 +0900583 rcu_read_lock();
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500584 }
Tejun Heod591fb52013-05-24 10:55:38 +0900585
586 rcu_read_unlock();
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500587 return rc;
588}
589
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700590/*
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700591 * Modify the exception list using allow/deny rules.
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700592 * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD
593 * so we can give a container CAP_MKNOD to let it create devices but not
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700594 * modify the exception list.
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700595 * It seems likely we'll want to add a CAP_CONTAINER capability to allow
596 * us to also grant CAP_SYS_ADMIN to containers without giving away the
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700597 * device exception list controls, but for now we'll stick with CAP_SYS_ADMIN
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700598 *
599 * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting
600 * new access is only allowed if you're in the top-level cgroup, or your
601 * parent cgroup has the access you're asking for.
602 */
Paul Menagef92523e2008-07-25 01:47:03 -0700603static int devcgroup_update_access(struct dev_cgroup *devcgroup,
Tejun Heo4d3bb512014-03-19 10:23:54 -0400604 int filetype, char *buffer)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700605{
Paul Menagef92523e2008-07-25 01:47:03 -0700606 const char *b;
Aristeu Rozanski26fd8402012-10-25 13:37:41 -0700607 char temp[12]; /* 11 + 1 characters needed for a u32 */
Aristeu Rozanskic39a2a32013-02-15 11:55:45 -0500608 int count, rc = 0;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700609 struct dev_exception_item ex;
Tejun Heo5c9d5352014-05-16 13:22:48 -0400610 struct dev_cgroup *parent = css_to_devcgroup(devcgroup->css.parent);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700611
612 if (!capable(CAP_SYS_ADMIN))
613 return -EPERM;
614
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700615 memset(&ex, 0, sizeof(ex));
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700616 b = buffer;
617
618 switch (*b) {
619 case 'a':
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700620 switch (filetype) {
621 case DEVCG_ALLOW:
Tejun Heo7a3bb242014-05-16 13:22:52 -0400622 if (css_has_online_children(&devcgroup->css))
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500623 return -EINVAL;
624
Aristeu Rozanski4cef7292012-10-25 13:37:45 -0700625 if (!may_allow_all(parent))
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700626 return -EPERM;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700627 dev_exception_clean(devcgroup);
Aristeu Rozanski64e10472012-11-06 07:25:04 -0800628 devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
629 if (!parent)
630 break;
631
Aristeu Rozanski4cef7292012-10-25 13:37:45 -0700632 rc = dev_exceptions_copy(&devcgroup->exceptions,
633 &parent->exceptions);
634 if (rc)
635 return rc;
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700636 break;
637 case DEVCG_DENY:
Tejun Heo7a3bb242014-05-16 13:22:52 -0400638 if (css_has_online_children(&devcgroup->css))
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500639 return -EINVAL;
640
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700641 dev_exception_clean(devcgroup);
Aristeu Rozanski5b7aa7d2012-10-25 13:37:38 -0700642 devcgroup->behavior = DEVCG_DEFAULT_DENY;
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700643 break;
644 default:
645 return -EINVAL;
646 }
647 return 0;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700648 case 'b':
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700649 ex.type = DEV_BLOCK;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700650 break;
651 case 'c':
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700652 ex.type = DEV_CHAR;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700653 break;
654 default:
Paul Menagef92523e2008-07-25 01:47:03 -0700655 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700656 }
657 b++;
Paul Menagef92523e2008-07-25 01:47:03 -0700658 if (!isspace(*b))
659 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700660 b++;
661 if (*b == '*') {
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700662 ex.major = ~0;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700663 b++;
664 } else if (isdigit(*b)) {
Aristeu Rozanski26fd8402012-10-25 13:37:41 -0700665 memset(temp, 0, sizeof(temp));
666 for (count = 0; count < sizeof(temp) - 1; count++) {
667 temp[count] = *b;
668 b++;
669 if (!isdigit(*b))
670 break;
671 }
672 rc = kstrtou32(temp, 10, &ex.major);
673 if (rc)
674 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700675 } else {
Paul Menagef92523e2008-07-25 01:47:03 -0700676 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700677 }
Paul Menagef92523e2008-07-25 01:47:03 -0700678 if (*b != ':')
679 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700680 b++;
681
682 /* read minor */
683 if (*b == '*') {
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700684 ex.minor = ~0;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700685 b++;
686 } else if (isdigit(*b)) {
Aristeu Rozanski26fd8402012-10-25 13:37:41 -0700687 memset(temp, 0, sizeof(temp));
688 for (count = 0; count < sizeof(temp) - 1; count++) {
689 temp[count] = *b;
690 b++;
691 if (!isdigit(*b))
692 break;
693 }
694 rc = kstrtou32(temp, 10, &ex.minor);
695 if (rc)
696 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700697 } else {
Paul Menagef92523e2008-07-25 01:47:03 -0700698 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700699 }
Paul Menagef92523e2008-07-25 01:47:03 -0700700 if (!isspace(*b))
701 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700702 for (b++, count = 0; count < 3; count++, b++) {
703 switch (*b) {
704 case 'r':
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700705 ex.access |= ACC_READ;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700706 break;
707 case 'w':
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700708 ex.access |= ACC_WRITE;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700709 break;
710 case 'm':
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700711 ex.access |= ACC_MKNOD;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700712 break;
713 case '\n':
714 case '\0':
715 count = 3;
716 break;
717 default:
Paul Menagef92523e2008-07-25 01:47:03 -0700718 return -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700719 }
720 }
721
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700722 switch (filetype) {
723 case DEVCG_ALLOW:
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700724 /*
725 * If the default policy is to allow by default, try to remove
726 * an matching exception instead. And be silent about it: we
727 * don't want to break compatibility
728 */
Aristeu Rozanski5b7aa7d2012-10-25 13:37:38 -0700729 if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
Aristeu Rozanskid2c2b112014-05-05 11:18:59 -0400730 /* Check if the parent allows removing it first */
731 if (!parent_allows_removal(devcgroup, &ex))
732 return -EPERM;
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700733 dev_exception_rm(devcgroup, &ex);
Aristeu Rozanskid2c2b112014-05-05 11:18:59 -0400734 break;
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700735 }
Aristeu Rozanskid2c2b112014-05-05 11:18:59 -0400736
737 if (!parent_has_perm(devcgroup, &ex))
738 return -EPERM;
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500739 rc = dev_exception_add(devcgroup, &ex);
740 break;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700741 case DEVCG_DENY:
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700742 /*
743 * If the default policy is to deny by default, try to remove
744 * an matching exception instead. And be silent about it: we
745 * don't want to break compatibility
746 */
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500747 if (devcgroup->behavior == DEVCG_DEFAULT_DENY)
Aristeu Rozanskidb9aeca2012-10-04 17:15:20 -0700748 dev_exception_rm(devcgroup, &ex);
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500749 else
750 rc = dev_exception_add(devcgroup, &ex);
751
752 if (rc)
753 break;
754 /* we only propagate new restrictions */
755 rc = propagate_exception(devcgroup, &ex);
756 break;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700757 default:
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500758 rc = -EINVAL;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700759 }
Aristeu Rozanskibd2953e2013-02-15 11:55:47 -0500760 return rc;
Paul Menagef92523e2008-07-25 01:47:03 -0700761}
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700762
Tejun Heo451af502014-05-13 12:16:21 -0400763static ssize_t devcgroup_access_write(struct kernfs_open_file *of,
764 char *buf, size_t nbytes, loff_t off)
Paul Menagef92523e2008-07-25 01:47:03 -0700765{
766 int retval;
Li Zefanb4046f02009-04-02 16:57:32 -0700767
768 mutex_lock(&devcgroup_mutex);
Tejun Heo451af502014-05-13 12:16:21 -0400769 retval = devcgroup_update_access(css_to_devcgroup(of_css(of)),
770 of_cft(of)->private, strstrip(buf));
Li Zefanb4046f02009-04-02 16:57:32 -0700771 mutex_unlock(&devcgroup_mutex);
Tejun Heo451af502014-05-13 12:16:21 -0400772 return retval ?: nbytes;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700773}
774
775static struct cftype dev_cgroup_files[] = {
776 {
777 .name = "allow",
Tejun Heo451af502014-05-13 12:16:21 -0400778 .write = devcgroup_access_write,
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700779 .private = DEVCG_ALLOW,
780 },
781 {
782 .name = "deny",
Tejun Heo451af502014-05-13 12:16:21 -0400783 .write = devcgroup_access_write,
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700784 .private = DEVCG_DENY,
785 },
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700786 {
787 .name = "list",
Tejun Heo2da8ca82013-12-05 12:28:04 -0500788 .seq_show = devcgroup_seq_show,
Serge E. Hallyn29486df2008-04-29 01:00:14 -0700789 .private = DEVCG_LIST,
790 },
Tejun Heo4baf6e32012-04-01 12:09:55 -0700791 { } /* terminate */
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700792};
793
Tejun Heo073219e2014-02-08 10:36:58 -0500794struct cgroup_subsys devices_cgrp_subsys = {
Tejun Heo92fb9742012-11-19 08:13:38 -0800795 .css_alloc = devcgroup_css_alloc,
796 .css_free = devcgroup_css_free,
Aristeu Rozanski1909554c2013-02-15 11:55:46 -0500797 .css_online = devcgroup_online,
798 .css_offline = devcgroup_offline,
Tejun Heo4baf6e32012-04-01 12:09:55 -0700799 .base_cftypes = dev_cgroup_files,
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700800};
801
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700802/**
803 * __devcgroup_check_permission - checks if an inode operation is permitted
804 * @dev_cgroup: the dev cgroup to be tested against
805 * @type: device type
806 * @major: device major number
807 * @minor: device minor number
808 * @access: combination of ACC_WRITE, ACC_READ and ACC_MKNOD
809 *
810 * returns 0 on success, -EPERM case the operation is not permitted
811 */
Jiri Slaby8c9506d2012-10-25 13:37:34 -0700812static int __devcgroup_check_permission(short type, u32 major, u32 minor,
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700813 short access)
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700814{
Jiri Slaby8c9506d2012-10-25 13:37:34 -0700815 struct dev_cgroup *dev_cgroup;
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400816 bool rc;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700817
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700818 rcu_read_lock();
Jiri Slaby8c9506d2012-10-25 13:37:34 -0700819 dev_cgroup = task_devcgroup(current);
Aristeu Rozanski79d71972014-04-21 12:13:03 -0400820 if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW)
821 /* Can't match any of the exceptions, even partially */
822 rc = !match_exception_partial(&dev_cgroup->exceptions,
823 type, major, minor, access);
824 else
825 /* Need to match completely one exception to be allowed */
826 rc = match_exception(&dev_cgroup->exceptions, type, major,
827 minor, access);
Pavel Emelyanov4efd1a12008-07-25 01:47:07 -0700828 rcu_read_unlock();
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700829
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700830 if (!rc)
831 return -EPERM;
832
833 return 0;
834}
835
836int __devcgroup_inode_permission(struct inode *inode, int mask)
837{
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700838 short type, access = 0;
839
840 if (S_ISBLK(inode->i_mode))
841 type = DEV_BLOCK;
842 if (S_ISCHR(inode->i_mode))
843 type = DEV_CHAR;
844 if (mask & MAY_WRITE)
845 access |= ACC_WRITE;
846 if (mask & MAY_READ)
847 access |= ACC_READ;
848
Jiri Slaby8c9506d2012-10-25 13:37:34 -0700849 return __devcgroup_check_permission(type, imajor(inode), iminor(inode),
850 access);
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700851}
852
853int devcgroup_inode_mknod(int mode, dev_t dev)
854{
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700855 short type;
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700856
Serge E. Hallyn0b82ac32009-01-07 18:07:46 -0800857 if (!S_ISBLK(mode) && !S_ISCHR(mode))
858 return 0;
859
Aristeu Rozanskiad676072012-10-04 17:15:17 -0700860 if (S_ISBLK(mode))
861 type = DEV_BLOCK;
862 else
863 type = DEV_CHAR;
Li Zefan36fd71d2008-09-02 14:35:52 -0700864
Jiri Slaby8c9506d2012-10-25 13:37:34 -0700865 return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev),
866 ACC_MKNOD);
Li Zefan36fd71d2008-09-02 14:35:52 -0700867
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700868}