[net-next-2.6.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;
	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, 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);
	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>
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;
	16	spinlock_t lock;
	17	};
	18
	19	struct cgroup_subsys ns_subsys;
	20
	21	static inline struct ns_cgroup *cgroup_to_ns(
	22	struct cgroup *cgroup)
	23	{
	24	return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
	25	struct ns_cgroup, css);
	26	}
	27
e885dcde	28	int ns_cgroup_clone(struct task_struct task, struct pid pid)
858d72ea	29	{
e885dcde SH	30	char name[PROC_NUMBUF];
	31
	32	snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
	33	return cgroup_clone(task, &ns_subsys, name);
858d72ea SH	34	}
	35
	36	/*
	37	* Rules:
	38	* 1. you can only enter a cgroup which is a child of your current
	39	* cgroup
	40	* 2. you can only place another process into a cgroup if
	41	* a. you have CAP_SYS_ADMIN
	42	* b. your cgroup is an ancestor of task's destination cgroup
	43	* (hence either you are in the same cgroup as task, or in an
	44	* ancestor cgroup thereof)
	45	*/
	46	static int ns_can_attach(struct cgroup_subsys *ss,
	47	struct cgroup new_cgroup, struct task_struct task)
	48	{
	49	struct cgroup *orig;
	50
	51	if (current != task) {
	52	if (!capable(CAP_SYS_ADMIN))
	53	return -EPERM;
	54
	55	if (!cgroup_is_descendant(new_cgroup))
	56	return -EPERM;
	57	}
	58
	59	if (atomic_read(&new_cgroup->count) != 0)
	60	return -EPERM;
	61
	62	orig = task_cgroup(task, ns_subsys_id);
	63	if (orig && orig != new_cgroup->parent)
	64	return -EPERM;
	65
	66	return 0;
	67	}
	68
	69	/*
	70	* Rules: you can only create a cgroup if
	71	* 1. you are capable(CAP_SYS_ADMIN)
	72	* 2. the target cgroup is a descendant of your own cgroup
	73	*/
	74	static struct cgroup_subsys_state ns_create(struct cgroup_subsys ss,
	75	struct cgroup *cgroup)
	76	{
	77	struct ns_cgroup *ns_cgroup;
	78
	79	if (!capable(CAP_SYS_ADMIN))
	80	return ERR_PTR(-EPERM);
	81	if (!cgroup_is_descendant(cgroup))
	82	return ERR_PTR(-EPERM);
	83
	84	ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
	85	if (!ns_cgroup)
	86	return ERR_PTR(-ENOMEM);
	87	spin_lock_init(&ns_cgroup->lock);
	88	return &ns_cgroup->css;
	89	}
	90
	91	static void ns_destroy(struct cgroup_subsys *ss,
	92	struct cgroup *cgroup)
	93	{
	94	struct ns_cgroup *ns_cgroup;
	95
	96	ns_cgroup = cgroup_to_ns(cgroup);
	97	kfree(ns_cgroup);
98	}
99
100	struct cgroup_subsys ns_subsys = {
101	.name = "ns",
102	.can_attach = ns_can_attach,
103	.create = ns_create,
104	.destroy = ns_destroy,
105	.subsys_id = ns_subsys_id,
106	};