[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/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 descendant 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, bool threadgroup)
{
	if (current != task) {
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;

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

	if (!cgroup_is_descendant(new_cgroup, task))
		return -EPERM;

	if (threadgroup) {
		struct task_struct *c;
		rcu_read_lock();
		list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
			if (!cgroup_is_descendant(new_cgroup, c)) {
				rcu_read_unlock();
				return -EPERM;
			}
		}
		rcu_read_unlock();
	}

	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, current))
		return ERR_PTR(-EPERM);
	if (test_bit(CGRP_CLONE_CHILDREN, &cgroup->flags)) {
		printk("ns_cgroup can't be created with parent "
		       "'clone_children' set.\n");
		return ERR_PTR(-EINVAL);
	}

	printk_once("ns_cgroup deprecated: consider using the "
		    "'clone_children' flag without the ns_cgroup.\n");

	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:
313e924c	37	* 1. you can only enter a cgroup which is a descendant of your current
858d72ea SH	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	*/
be367d09 BB	45	static int ns_can_attach(struct cgroup_subsys ss, struct cgroup new_cgroup,
be367d09 BB	46	struct task_struct *task, bool threadgroup)
858d72ea	47	{
858d72ea SH	48	if (current != task) {
	49	if (!capable(CAP_SYS_ADMIN))
	50	return -EPERM;
	51
313e924c	52	if (!cgroup_is_descendant(new_cgroup, current))
858d72ea SH	53	return -EPERM;
	54	}
	55
313e924c	56	if (!cgroup_is_descendant(new_cgroup, task))
858d72ea SH	57	return -EPERM;
858d72ea SH	58
be367d09 BB	59	if (threadgroup) {
	60	struct task_struct *c;
	61	rcu_read_lock();
	62	list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
	63	if (!cgroup_is_descendant(new_cgroup, c)) {
	64	rcu_read_unlock();
	65	return -EPERM;
	66	}
	67	}
	68	rcu_read_unlock();
	69	}
	70
858d72ea SH	71	return 0;
	72	}
	73
	74	/*
	75	* Rules: you can only create a cgroup if
	76	* 1. you are capable(CAP_SYS_ADMIN)
	77	* 2. the target cgroup is a descendant of your own cgroup
	78	*/
	79	static struct cgroup_subsys_state ns_create(struct cgroup_subsys ss,
	80	struct cgroup *cgroup)
	81	{
	82	struct ns_cgroup *ns_cgroup;
	83
	84	if (!capable(CAP_SYS_ADMIN))
	85	return ERR_PTR(-EPERM);
313e924c	86	if (!cgroup_is_descendant(cgroup, current))
858d72ea	87	return ERR_PTR(-EPERM);
45531757 DL	88	if (test_bit(CGRP_CLONE_CHILDREN, &cgroup->flags)) {
	89	printk("ns_cgroup can't be created with parent "
	90	"'clone_children' set.\n");
	91	return ERR_PTR(-EINVAL);
	92	}
	93
	94	printk_once("ns_cgroup deprecated: consider using the "
	95	"'clone_children' flag without the ns_cgroup.\n");
858d72ea SH	96
	97	ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
	98	if (!ns_cgroup)
	99	return ERR_PTR(-ENOMEM);
858d72ea SH	100	return &ns_cgroup->css;
	101	}
	102
	103	static void ns_destroy(struct cgroup_subsys *ss,
	104	struct cgroup *cgroup)
	105	{
	106	struct ns_cgroup *ns_cgroup;
	107
	108	ns_cgroup = cgroup_to_ns(cgroup);
	109	kfree(ns_cgroup);
	110	}
	111
	112	struct cgroup_subsys ns_subsys = {
	113	.name = "ns",
	114	.can_attach = ns_can_attach,
	115	.create = ns_create,
	116	.destroy = ns_destroy,
	117	.subsys_id = ns_subsys_id,
	118	};