[deliverable/linux.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/slab.h>

struct ns_cgroup {
	struct cgroup_subsys_state css;
	spinlock_t lock;
};

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)
{
	return cgroup_clone(task, &ns_subsys);
}

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