[linux-2.6-block.git] / kernel / ns_cgroup.c

/*
 * ns_cgroup.c - namespace cgroup subsystem
 *
 * Copyright 2006, 2007 IBM Corp
 */

#include <linux/module.h>
#include <linux/cgroup.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>
#include <linux/nsproxy.h>

struct ns_cgroup {
	struct cgroup_subsys_state css;
};

struct cgroup_subsys ns_subsys;

static inline struct ns_cgroup *cgroup_to_ns(
		struct cgroup *cgroup)
{
	return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
			    struct ns_cgroup, css);
}

int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
{
	char name[PROC_NUMBUF];

	snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
	return cgroup_clone(task, &ns_subsys, name);
}

/*
 * Rules:
 *   1. you can only enter a cgroup which is a child of your current
 *     cgroup
 *   2. you can only place another process into a cgroup if
 *     a. you have CAP_SYS_ADMIN
 *     b. your cgroup is an ancestor of task's destination cgroup
 *       (hence either you are in the same cgroup as task, or in an
 *        ancestor cgroup thereof)
 */
static int ns_can_attach(struct cgroup_subsys *ss,
		struct cgroup *new_cgroup, struct task_struct *task)
{
	struct cgroup *orig;

	if (current != task) {
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;

		if (!cgroup_is_descendant(new_cgroup))
			return -EPERM;
	}

	if (atomic_read(&new_cgroup->count) != 0)
		return -EPERM;

	orig = task_cgroup(task, ns_subsys_id);
	if (orig && orig != new_cgroup->parent)
		return -EPERM;

	return 0;
}

/*
 * Rules: you can only create a cgroup if
 *     1. you are capable(CAP_SYS_ADMIN)
 *     2. the target cgroup is a descendant of your own cgroup
 */
static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
						struct cgroup *cgroup)
{
	struct ns_cgroup *ns_cgroup;

	if (!capable(CAP_SYS_ADMIN))
		return ERR_PTR(-EPERM);
	if (!cgroup_is_descendant(cgroup))
		return ERR_PTR(-EPERM);

	ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
	if (!ns_cgroup)
		return ERR_PTR(-ENOMEM);
	return &ns_cgroup->css;
}

static void ns_destroy(struct cgroup_subsys *ss,
			struct cgroup *cgroup)
{
	struct ns_cgroup *ns_cgroup;

	ns_cgroup = cgroup_to_ns(cgroup);
	kfree(ns_cgroup);
}

struct cgroup_subsys ns_subsys = {
	.name = "ns",
	.can_attach = ns_can_attach,
	.create = ns_create,
	.destroy  = ns_destroy,
	.subsys_id = ns_subsys_id,
};
Commit	Line	Data
858d72ea SH	1	/*
	2	* ns_cgroup.c - namespace cgroup subsystem
	3	*
	4	* Copyright 2006, 2007 IBM Corp
	5	*/
	6
	7	#include <linux/module.h>
	8	#include <linux/cgroup.h>
	9	#include <linux/fs.h>
e885dcde	10	#include <linux/proc_fs.h>
1aeb272c	11	#include <linux/slab.h>
3ff31d0c	12	#include <linux/nsproxy.h>
858d72ea SH	13
	14	struct ns_cgroup {
	15	struct cgroup_subsys_state css;
858d72ea SH	16	};
	17
	18	struct cgroup_subsys ns_subsys;
	19
	20	static inline struct ns_cgroup *cgroup_to_ns(
	21	struct cgroup *cgroup)
	22	{
	23	return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
	24	struct ns_cgroup, css);
	25	}
	26
e885dcde	27	int ns_cgroup_clone(struct task_struct task, struct pid pid)
858d72ea	28	{
e885dcde SH	29	char name[PROC_NUMBUF];
	30
	31	snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
	32	return cgroup_clone(task, &ns_subsys, name);
858d72ea SH	33	}
	34
	35	/*
	36	* Rules:
	37	* 1. you can only enter a cgroup which is a child of your current
	38	* cgroup
	39	* 2. you can only place another process into a cgroup if
	40	* a. you have CAP_SYS_ADMIN
	41	* b. your cgroup is an ancestor of task's destination cgroup
	42	* (hence either you are in the same cgroup as task, or in an
	43	* ancestor cgroup thereof)
	44	*/
	45	static int ns_can_attach(struct cgroup_subsys *ss,
	46	struct cgroup new_cgroup, struct task_struct task)
	47	{
	48	struct cgroup *orig;
	49
	50	if (current != task) {
	51	if (!capable(CAP_SYS_ADMIN))
	52	return -EPERM;
	53
	54	if (!cgroup_is_descendant(new_cgroup))
	55	return -EPERM;
	56	}
	57
	58	if (atomic_read(&new_cgroup->count) != 0)
	59	return -EPERM;
	60
	61	orig = task_cgroup(task, ns_subsys_id);
	62	if (orig && orig != new_cgroup->parent)
	63	return -EPERM;
	64
	65	return 0;
	66	}
	67
	68	/*
	69	* Rules: you can only create a cgroup if
	70	* 1. you are capable(CAP_SYS_ADMIN)
	71	* 2. the target cgroup is a descendant of your own cgroup
	72	*/
	73	static struct cgroup_subsys_state ns_create(struct cgroup_subsys ss,
	74	struct cgroup *cgroup)
	75	{
	76	struct ns_cgroup *ns_cgroup;
	77
	78	if (!capable(CAP_SYS_ADMIN))
	79	return ERR_PTR(-EPERM);
	80	if (!cgroup_is_descendant(cgroup))
	81	return ERR_PTR(-EPERM);
	82
	83	ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
	84	if (!ns_cgroup)
	85	return ERR_PTR(-ENOMEM);
858d72ea SH	86	return &ns_cgroup->css;
	87	}
	88
	89	static void ns_destroy(struct cgroup_subsys *ss,
	90	struct cgroup *cgroup)
	91	{
	92	struct ns_cgroup *ns_cgroup;
	93
	94	ns_cgroup = cgroup_to_ns(cgroup);
	95	kfree(ns_cgroup);
	96	}
	97
	98	struct cgroup_subsys ns_subsys = {
	99	.name = "ns",
	100	.can_attach = ns_can_attach,
	101	.create = ns_create,
	102	.destroy = ns_destroy,
	103	.subsys_id = ns_subsys_id,
	104	};