[net-next-2.6.git] / kernel / user_namespace.c

/*
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation, version 2 of the
 *  License.
 */

#include <linux/module.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>

/*
 * Clone a new ns copying an original user ns, setting refcount to 1
 * @old_ns: namespace to clone
 * Return NULL on error (failure to kmalloc), new ns otherwise
 */
static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
{
	struct user_namespace *ns;
	struct user_struct *new_user;
	int n;

	ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
	if (!ns)
		return ERR_PTR(-ENOMEM);

	kref_init(&ns->kref);

	for (n = 0; n < UIDHASH_SZ; ++n)
		INIT_HLIST_HEAD(ns->uidhash_table + n);

	/* Insert new root user.  */
	ns->root_user = alloc_uid(ns, 0);
	if (!ns->root_user) {
		kfree(ns);
		return ERR_PTR(-ENOMEM);
	}

	/* Reset current->user with a new one */
	new_user = alloc_uid(ns, current->uid);
	if (!new_user) {
		free_uid(ns->root_user);
		kfree(ns);
		return ERR_PTR(-ENOMEM);
	}

	switch_uid(new_user);
	return ns;
}

struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
{
	struct user_namespace *new_ns;

	BUG_ON(!old_ns);
	get_user_ns(old_ns);

	if (!(flags & CLONE_NEWUSER))
		return old_ns;

	new_ns = clone_user_ns(old_ns);

	put_user_ns(old_ns);
	return new_ns;
}

void free_user_ns(struct kref *kref)
{
	struct user_namespace *ns;

	ns = container_of(kref, struct user_namespace, kref);
	release_uids(ns);
	kfree(ns);
}
EXPORT_SYMBOL(free_user_ns);
Commit	Line	Data
acce292c CLG	1	/*
	2	* This program is free software; you can redistribute it and/or
	3	* modify it under the terms of the GNU General Public License as
	4	* published by the Free Software Foundation, version 2 of the
	5	* License.
	6	*/
	7
	8	#include <linux/module.h>
acce292c	9	#include <linux/nsproxy.h>
1aeb272c	10	#include <linux/slab.h>
acce292c CLG	11	#include <linux/user_namespace.h>
acce292c CLG	12
77ec739d SH	13	/*
	14	* Clone a new ns copying an original user ns, setting refcount to 1
	15	* @old_ns: namespace to clone
	16	* Return NULL on error (failure to kmalloc), new ns otherwise
	17	*/
	18	static struct user_namespace clone_user_ns(struct user_namespace old_ns)
	19	{
	20	struct user_namespace *ns;
	21	struct user_struct *new_user;
	22	int n;
	23
	24	ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
	25	if (!ns)
467e9f4b	26	return ERR_PTR(-ENOMEM);
77ec739d SH	27
	28	kref_init(&ns->kref);
	29
	30	for (n = 0; n < UIDHASH_SZ; ++n)
735de223	31	INIT_HLIST_HEAD(ns->uidhash_table + n);
77ec739d SH	32
	33	/* Insert new root user. */
	34	ns->root_user = alloc_uid(ns, 0);
	35	if (!ns->root_user) {
	36	kfree(ns);
467e9f4b	37	return ERR_PTR(-ENOMEM);
77ec739d SH	38	}
	39
	40	/* Reset current->user with a new one */
	41	new_user = alloc_uid(ns, current->uid);
	42	if (!new_user) {
	43	free_uid(ns->root_user);
	44	kfree(ns);
467e9f4b	45	return ERR_PTR(-ENOMEM);
77ec739d SH	46	}
	47
	48	switch_uid(new_user);
	49	return ns;
	50	}
	51
acce292c CLG	52	struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
	53	{
	54	struct user_namespace *new_ns;
	55
	56	BUG_ON(!old_ns);
	57	get_user_ns(old_ns);
	58
77ec739d SH	59	if (!(flags & CLONE_NEWUSER))
	60	return old_ns;
	61
	62	new_ns = clone_user_ns(old_ns);
	63
	64	put_user_ns(old_ns);
acce292c CLG	65	return new_ns;
	66	}
	67
	68	void free_user_ns(struct kref *kref)
	69	{
	70	struct user_namespace *ns;
	71
	72	ns = container_of(kref, struct user_namespace, kref);
28f300d2	73	release_uids(ns);
acce292c CLG	74	kfree(ns);
acce292c CLG	75	}
6a3fd92e	76	EXPORT_SYMBOL(free_user_ns);