Revision d936eb23874433caa3e3d841cfa16f5434b85dcf authored by Linus Torvalds on 16 July 2021, 01:05:31 UTC, committed by Linus Torvalds on 16 July 2021, 01:05:31 UTC
This reverts commit b7eb335e26a9c7f258c96b3962c283c379d3ede0. It turns out that the problem with the clang -Wimplicit-fallthrough warning is not about the kernel source code, but about clang itself, and that the warning is unusable until clang fixes its broken ways. In particular, when you enable this warning for clang, you not only get warnings about implicit fallthroughs. You also get this: warning: fallthrough annotation in unreachable code [-Wimplicit-fallthrough] which is completely broken becasue it (a) doesn't even tell you where the problem is (seriously: no line numbers, no filename, no nothing). (b) is fundamentally broken anyway, because there are perfectly valid reasons to have a fallthrough statement even if it turns out that it can perhaps not be reached. In the kernel, an example of that second case is code in the scheduler: switch (state) { case cpuset: if (IS_ENABLED(CONFIG_CPUSETS)) { cpuset_cpus_allowed_fallback(p); state = possible; break; } fallthrough; case possible: where if CONFIG_CPUSETS is enabled you actually never hit the fallthrough case at all. But that in no way makes the fallthrough wrong. So the warning is completely broken, and enabling it for clang is a very bad idea. In the meantime, we can keep the gcc option enabled, and make the gcc build use -Wimplicit-fallthrough=5 which means that we will at least continue to require a proper fallthrough statement, and that gcc won't silently accept the magic comment versions. Because gcc does this all correctly, and while the odd "=5" part is kind of obscure, it's documented in [1]: "-Wimplicit-fallthrough=5 doesn’t recognize any comments as fallthrough comments, only attributes disable the warning" so if clang ever fixes its bad behavior we can try enabling it there again. Link: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html [1] Cc: Kees Cook <keescook@chromium.org> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 1013d4a
device_cgroup.c
// SPDX-License-Identifier: GPL-2.0
/*
* device_cgroup.c - device cgroup subsystem
*
* Copyright 2007 IBM Corp
*/
#include <linux/device_cgroup.h>
#include <linux/cgroup.h>
#include <linux/ctype.h>
#include <linux/list.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#ifdef CONFIG_CGROUP_DEVICE
static DEFINE_MUTEX(devcgroup_mutex);
enum devcg_behavior {
DEVCG_DEFAULT_NONE,
DEVCG_DEFAULT_ALLOW,
DEVCG_DEFAULT_DENY,
};
/*
* exception list locking rules:
* hold devcgroup_mutex for update/read.
* hold rcu_read_lock() for read.
*/
struct dev_exception_item {
u32 major, minor;
short type;
short access;
struct list_head list;
struct rcu_head rcu;
};
struct dev_cgroup {
struct cgroup_subsys_state css;
struct list_head exceptions;
enum devcg_behavior behavior;
};
static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
{
return s ? container_of(s, struct dev_cgroup, css) : NULL;
}
static inline struct dev_cgroup *task_devcgroup(struct task_struct *task)
{
return css_to_devcgroup(task_css(task, devices_cgrp_id));
}
/*
* called under devcgroup_mutex
*/
static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig)
{
struct dev_exception_item *ex, *tmp, *new;
lockdep_assert_held(&devcgroup_mutex);
list_for_each_entry(ex, orig, list) {
new = kmemdup(ex, sizeof(*ex), GFP_KERNEL);
if (!new)
goto free_and_exit;
list_add_tail(&new->list, dest);
}
return 0;
free_and_exit:
list_for_each_entry_safe(ex, tmp, dest, list) {
list_del(&ex->list);
kfree(ex);
}
return -ENOMEM;
}
/*
* called under devcgroup_mutex
*/
static int dev_exception_add(struct dev_cgroup *dev_cgroup,
struct dev_exception_item *ex)
{
struct dev_exception_item *excopy, *walk;
lockdep_assert_held(&devcgroup_mutex);
excopy = kmemdup(ex, sizeof(*ex), GFP_KERNEL);
if (!excopy)
return -ENOMEM;
list_for_each_entry(walk, &dev_cgroup->exceptions, list) {
if (walk->type != ex->type)
continue;
if (walk->major != ex->major)
continue;
if (walk->minor != ex->minor)
continue;
walk->access |= ex->access;
kfree(excopy);
excopy = NULL;
}
if (excopy != NULL)
list_add_tail_rcu(&excopy->list, &dev_cgroup->exceptions);
return 0;
}
/*
* called under devcgroup_mutex
*/
static void dev_exception_rm(struct dev_cgroup *dev_cgroup,
struct dev_exception_item *ex)
{
struct dev_exception_item *walk, *tmp;
lockdep_assert_held(&devcgroup_mutex);
list_for_each_entry_safe(walk, tmp, &dev_cgroup->exceptions, list) {
if (walk->type != ex->type)
continue;
if (walk->major != ex->major)
continue;
if (walk->minor != ex->minor)
continue;
walk->access &= ~ex->access;
if (!walk->access) {
list_del_rcu(&walk->list);
kfree_rcu(walk, rcu);
}
}
}
static void __dev_exception_clean(struct dev_cgroup *dev_cgroup)
{
struct dev_exception_item *ex, *tmp;
list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
list_del_rcu(&ex->list);
kfree_rcu(ex, rcu);
}
}
/**
* dev_exception_clean - frees all entries of the exception list
* @dev_cgroup: dev_cgroup with the exception list to be cleaned
*
* called under devcgroup_mutex
*/
static void dev_exception_clean(struct dev_cgroup *dev_cgroup)
{
lockdep_assert_held(&devcgroup_mutex);
__dev_exception_clean(dev_cgroup);
}
static inline bool is_devcg_online(const struct dev_cgroup *devcg)
{
return (devcg->behavior != DEVCG_DEFAULT_NONE);
}
/**
* devcgroup_online - initializes devcgroup's behavior and exceptions based on
* parent's
* @css: css getting online
* returns 0 in case of success, error code otherwise
*/
static int devcgroup_online(struct cgroup_subsys_state *css)
{
struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css->parent);
int ret = 0;
mutex_lock(&devcgroup_mutex);
if (parent_dev_cgroup == NULL)
dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW;
else {
ret = dev_exceptions_copy(&dev_cgroup->exceptions,
&parent_dev_cgroup->exceptions);
if (!ret)
dev_cgroup->behavior = parent_dev_cgroup->behavior;
}
mutex_unlock(&devcgroup_mutex);
return ret;
}
static void devcgroup_offline(struct cgroup_subsys_state *css)
{
struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
mutex_lock(&devcgroup_mutex);
dev_cgroup->behavior = DEVCG_DEFAULT_NONE;
mutex_unlock(&devcgroup_mutex);
}
/*
* called from kernel/cgroup.c with cgroup_lock() held.
*/
static struct cgroup_subsys_state *
devcgroup_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct dev_cgroup *dev_cgroup;
dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL);
if (!dev_cgroup)
return ERR_PTR(-ENOMEM);
INIT_LIST_HEAD(&dev_cgroup->exceptions);
dev_cgroup->behavior = DEVCG_DEFAULT_NONE;
return &dev_cgroup->css;
}
static void devcgroup_css_free(struct cgroup_subsys_state *css)
{
struct dev_cgroup *dev_cgroup = css_to_devcgroup(css);
__dev_exception_clean(dev_cgroup);
kfree(dev_cgroup);
}
#define DEVCG_ALLOW 1
#define DEVCG_DENY 2
#define DEVCG_LIST 3
#define MAJMINLEN 13
#define ACCLEN 4
static void set_access(char *acc, short access)
{
int idx = 0;
memset(acc, 0, ACCLEN);
if (access & DEVCG_ACC_READ)
acc[idx++] = 'r';
if (access & DEVCG_ACC_WRITE)
acc[idx++] = 'w';
if (access & DEVCG_ACC_MKNOD)
acc[idx++] = 'm';
}
static char type_to_char(short type)
{
if (type == DEVCG_DEV_ALL)
return 'a';
if (type == DEVCG_DEV_CHAR)
return 'c';
if (type == DEVCG_DEV_BLOCK)
return 'b';
return 'X';
}
static void set_majmin(char *str, unsigned m)
{
if (m == ~0)
strcpy(str, "*");
else
sprintf(str, "%u", m);
}
static int devcgroup_seq_show(struct seq_file *m, void *v)
{
struct dev_cgroup *devcgroup = css_to_devcgroup(seq_css(m));
struct dev_exception_item *ex;
char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN];
rcu_read_lock();
/*
* To preserve the compatibility:
* - Only show the "all devices" when the default policy is to allow
* - List the exceptions in case the default policy is to deny
* This way, the file remains as a "whitelist of devices"
*/
if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
set_access(acc, DEVCG_ACC_MASK);
set_majmin(maj, ~0);
set_majmin(min, ~0);
seq_printf(m, "%c %s:%s %s\n", type_to_char(DEVCG_DEV_ALL),
maj, min, acc);
} else {
list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) {
set_access(acc, ex->access);
set_majmin(maj, ex->major);
set_majmin(min, ex->minor);
seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type),
maj, min, acc);
}
}
rcu_read_unlock();
return 0;
}
/**
* match_exception - iterates the exception list trying to find a complete match
* @exceptions: list of exceptions
* @type: device type (DEVCG_DEV_BLOCK or DEVCG_DEV_CHAR)
* @major: device file major number, ~0 to match all
* @minor: device file minor number, ~0 to match all
* @access: permission mask (DEVCG_ACC_READ, DEVCG_ACC_WRITE, DEVCG_ACC_MKNOD)
*
* It is considered a complete match if an exception is found that will
* contain the entire range of provided parameters.
*
* Return: true in case it matches an exception completely
*/
static bool match_exception(struct list_head *exceptions, short type,
u32 major, u32 minor, short access)
{
struct dev_exception_item *ex;
list_for_each_entry_rcu(ex, exceptions, list) {
if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK))
continue;
if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR))
continue;
if (ex->major != ~0 && ex->major != major)
continue;
if (ex->minor != ~0 && ex->minor != minor)
continue;
/* provided access cannot have more than the exception rule */
if (access & (~ex->access))
continue;
return true;
}
return false;
}
/**
* match_exception_partial - iterates the exception list trying to find a partial match
* @exceptions: list of exceptions
* @type: device type (DEVCG_DEV_BLOCK or DEVCG_DEV_CHAR)
* @major: device file major number, ~0 to match all
* @minor: device file minor number, ~0 to match all
* @access: permission mask (DEVCG_ACC_READ, DEVCG_ACC_WRITE, DEVCG_ACC_MKNOD)
*
* It is considered a partial match if an exception's range is found to
* contain *any* of the devices specified by provided parameters. This is
* used to make sure no extra access is being granted that is forbidden by
* any of the exception list.
*
* Return: true in case the provided range mat matches an exception completely
*/
static bool match_exception_partial(struct list_head *exceptions, short type,
u32 major, u32 minor, short access)
{
struct dev_exception_item *ex;
list_for_each_entry_rcu(ex, exceptions, list,
lockdep_is_held(&devcgroup_mutex)) {
if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK))
continue;
if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR))
continue;
/*
* We must be sure that both the exception and the provided
* range aren't masking all devices
*/
if (ex->major != ~0 && major != ~0 && ex->major != major)
continue;
if (ex->minor != ~0 && minor != ~0 && ex->minor != minor)
continue;
/*
* In order to make sure the provided range isn't matching
* an exception, all its access bits shouldn't match the
* exception's access bits
*/
if (!(access & ex->access))
continue;
return true;
}
return false;
}
/**
* verify_new_ex - verifies if a new exception is allowed by parent cgroup's permissions
* @dev_cgroup: dev cgroup to be tested against
* @refex: new exception
* @behavior: behavior of the exception's dev_cgroup
*
* This is used to make sure a child cgroup won't have more privileges
* than its parent
*/
static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
struct dev_exception_item *refex,
enum devcg_behavior behavior)
{
bool match = false;
RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
!lockdep_is_held(&devcgroup_mutex),
"device_cgroup:verify_new_ex called without proper synchronization");
if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
if (behavior == DEVCG_DEFAULT_ALLOW) {
/*
* new exception in the child doesn't matter, only
* adding extra restrictions
*/
return true;
} else {
/*
* new exception in the child will add more devices
* that can be acessed, so it can't match any of
* parent's exceptions, even slightly
*/
match = match_exception_partial(&dev_cgroup->exceptions,
refex->type,
refex->major,
refex->minor,
refex->access);
if (match)
return false;
return true;
}
} else {
/*
* Only behavior == DEVCG_DEFAULT_DENY allowed here, therefore
* the new exception will add access to more devices and must
* be contained completely in an parent's exception to be
* allowed
*/
match = match_exception(&dev_cgroup->exceptions, refex->type,
refex->major, refex->minor,
refex->access);
if (match)
/* parent has an exception that matches the proposed */
return true;
else
return false;
}
return false;
}
/*
* parent_has_perm:
* when adding a new allow rule to a device exception list, the rule
* must be allowed in the parent device
*/
static int parent_has_perm(struct dev_cgroup *childcg,
struct dev_exception_item *ex)
{
struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent);
if (!parent)
return 1;
return verify_new_ex(parent, ex, childcg->behavior);
}
/**
* parent_allows_removal - verify if it's ok to remove an exception
* @childcg: child cgroup from where the exception will be removed
* @ex: exception being removed
*
* When removing an exception in cgroups with default ALLOW policy, it must
* be checked if removing it will give the child cgroup more access than the
* parent.
*
* Return: true if it's ok to remove exception, false otherwise
*/
static bool parent_allows_removal(struct dev_cgroup *childcg,
struct dev_exception_item *ex)
{
struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent);
if (!parent)
return true;
/* It's always allowed to remove access to devices */
if (childcg->behavior == DEVCG_DEFAULT_DENY)
return true;
/*
* Make sure you're not removing part or a whole exception existing in
* the parent cgroup
*/
return !match_exception_partial(&parent->exceptions, ex->type,
ex->major, ex->minor, ex->access);
}
/**
* may_allow_all - checks if it's possible to change the behavior to
* allow based on parent's rules.
* @parent: device cgroup's parent
* returns: != 0 in case it's allowed, 0 otherwise
*/
static inline int may_allow_all(struct dev_cgroup *parent)
{
if (!parent)
return 1;
return parent->behavior == DEVCG_DEFAULT_ALLOW;
}
/**
* revalidate_active_exceptions - walks through the active exception list and
* revalidates the exceptions based on parent's
* behavior and exceptions. The exceptions that
* are no longer valid will be removed.
* Called with devcgroup_mutex held.
* @devcg: cgroup which exceptions will be checked
*
* This is one of the three key functions for hierarchy implementation.
* This function is responsible for re-evaluating all the cgroup's active
* exceptions due to a parent's exception change.
* Refer to Documentation/admin-guide/cgroup-v1/devices.rst for more details.
*/
static void revalidate_active_exceptions(struct dev_cgroup *devcg)
{
struct dev_exception_item *ex;
struct list_head *this, *tmp;
list_for_each_safe(this, tmp, &devcg->exceptions) {
ex = container_of(this, struct dev_exception_item, list);
if (!parent_has_perm(devcg, ex))
dev_exception_rm(devcg, ex);
}
}
/**
* propagate_exception - propagates a new exception to the children
* @devcg_root: device cgroup that added a new exception
* @ex: new exception to be propagated
*
* returns: 0 in case of success, != 0 in case of error
*/
static int propagate_exception(struct dev_cgroup *devcg_root,
struct dev_exception_item *ex)
{
struct cgroup_subsys_state *pos;
int rc = 0;
rcu_read_lock();
css_for_each_descendant_pre(pos, &devcg_root->css) {
struct dev_cgroup *devcg = css_to_devcgroup(pos);
/*
* Because devcgroup_mutex is held, no devcg will become
* online or offline during the tree walk (see on/offline
* methods), and online ones are safe to access outside RCU
* read lock without bumping refcnt.
*/
if (pos == &devcg_root->css || !is_devcg_online(devcg))
continue;
rcu_read_unlock();
/*
* in case both root's behavior and devcg is allow, a new
* restriction means adding to the exception list
*/
if (devcg_root->behavior == DEVCG_DEFAULT_ALLOW &&
devcg->behavior == DEVCG_DEFAULT_ALLOW) {
rc = dev_exception_add(devcg, ex);
if (rc)
return rc;
} else {
/*
* in the other possible cases:
* root's behavior: allow, devcg's: deny
* root's behavior: deny, devcg's: deny
* the exception will be removed
*/
dev_exception_rm(devcg, ex);
}
revalidate_active_exceptions(devcg);
rcu_read_lock();
}
rcu_read_unlock();
return rc;
}
/*
* Modify the exception list using allow/deny rules.
* CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD
* so we can give a container CAP_MKNOD to let it create devices but not
* modify the exception list.
* It seems likely we'll want to add a CAP_CONTAINER capability to allow
* us to also grant CAP_SYS_ADMIN to containers without giving away the
* device exception list controls, but for now we'll stick with CAP_SYS_ADMIN
*
* Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting
* new access is only allowed if you're in the top-level cgroup, or your
* parent cgroup has the access you're asking for.
*/
static int devcgroup_update_access(struct dev_cgroup *devcgroup,
int filetype, char *buffer)
{
const char *b;
char temp[12]; /* 11 + 1 characters needed for a u32 */
int count, rc = 0;
struct dev_exception_item ex;
struct dev_cgroup *parent = css_to_devcgroup(devcgroup->css.parent);
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
memset(&ex, 0, sizeof(ex));
b = buffer;
switch (*b) {
case 'a':
switch (filetype) {
case DEVCG_ALLOW:
if (css_has_online_children(&devcgroup->css))
return -EINVAL;
if (!may_allow_all(parent))
return -EPERM;
dev_exception_clean(devcgroup);
devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
if (!parent)
break;
rc = dev_exceptions_copy(&devcgroup->exceptions,
&parent->exceptions);
if (rc)
return rc;
break;
case DEVCG_DENY:
if (css_has_online_children(&devcgroup->css))
return -EINVAL;
dev_exception_clean(devcgroup);
devcgroup->behavior = DEVCG_DEFAULT_DENY;
break;
default:
return -EINVAL;
}
return 0;
case 'b':
ex.type = DEVCG_DEV_BLOCK;
break;
case 'c':
ex.type = DEVCG_DEV_CHAR;
break;
default:
return -EINVAL;
}
b++;
if (!isspace(*b))
return -EINVAL;
b++;
if (*b == '*') {
ex.major = ~0;
b++;
} else if (isdigit(*b)) {
memset(temp, 0, sizeof(temp));
for (count = 0; count < sizeof(temp) - 1; count++) {
temp[count] = *b;
b++;
if (!isdigit(*b))
break;
}
rc = kstrtou32(temp, 10, &ex.major);
if (rc)
return -EINVAL;
} else {
return -EINVAL;
}
if (*b != ':')
return -EINVAL;
b++;
/* read minor */
if (*b == '*') {
ex.minor = ~0;
b++;
} else if (isdigit(*b)) {
memset(temp, 0, sizeof(temp));
for (count = 0; count < sizeof(temp) - 1; count++) {
temp[count] = *b;
b++;
if (!isdigit(*b))
break;
}
rc = kstrtou32(temp, 10, &ex.minor);
if (rc)
return -EINVAL;
} else {
return -EINVAL;
}
if (!isspace(*b))
return -EINVAL;
for (b++, count = 0; count < 3; count++, b++) {
switch (*b) {
case 'r':
ex.access |= DEVCG_ACC_READ;
break;
case 'w':
ex.access |= DEVCG_ACC_WRITE;
break;
case 'm':
ex.access |= DEVCG_ACC_MKNOD;
break;
case '\n':
case '\0':
count = 3;
break;
default:
return -EINVAL;
}
}
switch (filetype) {
case DEVCG_ALLOW:
/*
* If the default policy is to allow by default, try to remove
* an matching exception instead. And be silent about it: we
* don't want to break compatibility
*/
if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
/* Check if the parent allows removing it first */
if (!parent_allows_removal(devcgroup, &ex))
return -EPERM;
dev_exception_rm(devcgroup, &ex);
break;
}
if (!parent_has_perm(devcgroup, &ex))
return -EPERM;
rc = dev_exception_add(devcgroup, &ex);
break;
case DEVCG_DENY:
/*
* If the default policy is to deny by default, try to remove
* an matching exception instead. And be silent about it: we
* don't want to break compatibility
*/
if (devcgroup->behavior == DEVCG_DEFAULT_DENY)
dev_exception_rm(devcgroup, &ex);
else
rc = dev_exception_add(devcgroup, &ex);
if (rc)
break;
/* we only propagate new restrictions */
rc = propagate_exception(devcgroup, &ex);
break;
default:
rc = -EINVAL;
}
return rc;
}
static ssize_t devcgroup_access_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
int retval;
mutex_lock(&devcgroup_mutex);
retval = devcgroup_update_access(css_to_devcgroup(of_css(of)),
of_cft(of)->private, strstrip(buf));
mutex_unlock(&devcgroup_mutex);
return retval ?: nbytes;
}
static struct cftype dev_cgroup_files[] = {
{
.name = "allow",
.write = devcgroup_access_write,
.private = DEVCG_ALLOW,
},
{
.name = "deny",
.write = devcgroup_access_write,
.private = DEVCG_DENY,
},
{
.name = "list",
.seq_show = devcgroup_seq_show,
.private = DEVCG_LIST,
},
{ } /* terminate */
};
struct cgroup_subsys devices_cgrp_subsys = {
.css_alloc = devcgroup_css_alloc,
.css_free = devcgroup_css_free,
.css_online = devcgroup_online,
.css_offline = devcgroup_offline,
.legacy_cftypes = dev_cgroup_files,
};
/**
* devcgroup_legacy_check_permission - checks if an inode operation is permitted
* @dev_cgroup: the dev cgroup to be tested against
* @type: device type
* @major: device major number
* @minor: device minor number
* @access: combination of DEVCG_ACC_WRITE, DEVCG_ACC_READ and DEVCG_ACC_MKNOD
*
* returns 0 on success, -EPERM case the operation is not permitted
*/
static int devcgroup_legacy_check_permission(short type, u32 major, u32 minor,
short access)
{
struct dev_cgroup *dev_cgroup;
bool rc;
rcu_read_lock();
dev_cgroup = task_devcgroup(current);
if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW)
/* Can't match any of the exceptions, even partially */
rc = !match_exception_partial(&dev_cgroup->exceptions,
type, major, minor, access);
else
/* Need to match completely one exception to be allowed */
rc = match_exception(&dev_cgroup->exceptions, type, major,
minor, access);
rcu_read_unlock();
if (!rc)
return -EPERM;
return 0;
}
#endif /* CONFIG_CGROUP_DEVICE */
#if defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF)
int devcgroup_check_permission(short type, u32 major, u32 minor, short access)
{
int rc = BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access);
if (rc)
return -EPERM;
#ifdef CONFIG_CGROUP_DEVICE
return devcgroup_legacy_check_permission(type, major, minor, access);
#else /* CONFIG_CGROUP_DEVICE */
return 0;
#endif /* CONFIG_CGROUP_DEVICE */
}
EXPORT_SYMBOL(devcgroup_check_permission);
#endif /* defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF) */
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