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Commit ecf8fecb authored by Roman Gushchin's avatar Roman Gushchin Committed by David S. Miller
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device_cgroup: prepare code for bpf-based device controller 



This is non-functional change to prepare the device cgroup code
for adding eBPF-based controller for cgroups v2.

The patch performs the following changes:
1) __devcgroup_inode_permission() and devcgroup_inode_mknod()
   are moving to the device-cgroup.h and converting into static inline.
2) __devcgroup_check_permission() is exported.
3) devcgroup_check_permission() wrapper is introduced to be used
   by both existing and new bpf-based implementations.

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 67e306fd

include/linux/device_cgroup.h

+57 −4
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#include <linux/fs.h>



#define DEVCG_ACC_MKNOD 1

#define DEVCG_ACC_READ  2

#define DEVCG_ACC_WRITE 4

#define DEVCG_ACC_MASK (DEVCG_ACC_MKNOD | DEVCG_ACC_READ | DEVCG_ACC_WRITE)



#define DEVCG_DEV_BLOCK 1

#define DEVCG_DEV_CHAR  2

#define DEVCG_DEV_ALL   4  /* this represents all devices */



#ifdef CONFIG_CGROUP_DEVICE

extern int __devcgroup_check_permission(short type, u32 major, u32 minor,

					short access);

#else

static inline int __devcgroup_check_permission(short type, u32 major, u32 minor,

					       short access)

{ return 0; }

#endif



#ifdef CONFIG_CGROUP_DEVICE

extern int __devcgroup_inode_permission(struct inode *inode, int mask);

extern int devcgroup_inode_mknod(int mode, dev_t dev);

static inline int devcgroup_check_permission(short type, u32 major, u32 minor,

					     short access)

{

	return __devcgroup_check_permission(type, major, minor, access);

}



static inline int devcgroup_inode_permission(struct inode *inode, int mask)

{

	short type, access = 0;



	if (likely(!inode->i_rdev))

		return 0;

	if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode))



	if (S_ISBLK(inode->i_mode))

		type = DEVCG_DEV_BLOCK;

	else if (S_ISCHR(inode->i_mode))

		type = DEVCG_DEV_CHAR;

	else

		return 0;

	return __devcgroup_inode_permission(inode, mask);



	if (mask & MAY_WRITE)

		access |= DEVCG_ACC_WRITE;

	if (mask & MAY_READ)

		access |= DEVCG_ACC_READ;



	return devcgroup_check_permission(type, imajor(inode), iminor(inode),

					  access);

}



static inline int devcgroup_inode_mknod(int mode, dev_t dev)

{

	short type;



	if (!S_ISBLK(mode) && !S_ISCHR(mode))

		return 0;



	if (S_ISBLK(mode))

		type = DEVCG_DEV_BLOCK;

	else

		type = DEVCG_DEV_CHAR;



	return devcgroup_check_permission(type, MAJOR(dev), MINOR(dev),

					  DEVCG_ACC_MKNOD);

}



#else

static inline int devcgroup_inode_permission(struct inode *inode, int mask)

{ return 0; }

security/device_cgroup.c

+2 −45
Original line number Diff line number Diff line
@@ -15,15 +15,6 @@ 
#include <linux/rcupdate.h>

#include <linux/mutex.h>



#define DEVCG_ACC_MKNOD 1

#define DEVCG_ACC_READ  2

#define DEVCG_ACC_WRITE 4

#define DEVCG_ACC_MASK (DEVCG_ACC_MKNOD | DEVCG_ACC_READ | DEVCG_ACC_WRITE)



#define DEVCG_DEV_BLOCK 1

#define DEVCG_DEV_CHAR  2

#define DEVCG_DEV_ALL   4  /* this represents all devices */



static DEFINE_MUTEX(devcgroup_mutex);



enum devcg_behavior {
@@ -810,7 +801,7 @@ struct cgroup_subsys devices_cgrp_subsys = { 
 *

 * returns 0 on success, -EPERM case the operation is not permitted

 */

static int __devcgroup_check_permission(short type, u32 major, u32 minor,

int __devcgroup_check_permission(short type, u32 major, u32 minor,

				 short access)

{

	struct dev_cgroup *dev_cgroup;
@@ -833,37 +824,3 @@ static int __devcgroup_check_permission(short type, u32 major, u32 minor, 


	return 0;

}
 


int __devcgroup_inode_permission(struct inode *inode, int mask)

{

	short type, access = 0;



	if (S_ISBLK(inode->i_mode))

		type = DEVCG_DEV_BLOCK;

	if (S_ISCHR(inode->i_mode))

		type = DEVCG_DEV_CHAR;

	if (mask & MAY_WRITE)

		access |= DEVCG_ACC_WRITE;

	if (mask & MAY_READ)

		access |= DEVCG_ACC_READ;



	return __devcgroup_check_permission(type, imajor(inode), iminor(inode),

			access);

}



int devcgroup_inode_mknod(int mode, dev_t dev)

{

	short type;



	if (!S_ISBLK(mode) && !S_ISCHR(mode))

		return 0;



	if (S_ISBLK(mode))

		type = DEVCG_DEV_BLOCK;

	else

		type = DEVCG_DEV_CHAR;



	return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev),

			DEVCG_ACC_MKNOD);



}