[deliverable/linux.git] / kernel / utsname.c

/*
 *  Copyright (C) 2004 IBM Corporation
 *
 *  Author: Serge Hallyn <serue@us.ibm.com>
 *
 *  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/export.h>
#include <linux/uts.h>
#include <linux/utsname.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>
#include <linux/proc_fs.h>

static struct uts_namespace *create_uts_ns(void)
{
	struct uts_namespace *uts_ns;

	uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
	if (uts_ns)
		kref_init(&uts_ns->kref);
	return uts_ns;
}

/*
 * Clone a new ns copying an original utsname, setting refcount to 1
 * @old_ns: namespace to clone
 * Return NULL on error (failure to kmalloc), new ns otherwise
 */
static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
					  struct uts_namespace *old_ns)
{
	struct uts_namespace *ns;

	ns = create_uts_ns();
	if (!ns)
		return ERR_PTR(-ENOMEM);

	down_read(&uts_sem);
	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
	ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
	up_read(&uts_sem);
	return ns;
}

/*
 * Copy task tsk's utsname namespace, or clone it if flags
 * specifies CLONE_NEWUTS.  In latter case, changes to the
 * utsname of this process won't be seen by parent, and vice
 * versa.
 */
struct uts_namespace *copy_utsname(unsigned long flags,
				   struct task_struct *tsk)
{
	struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
	struct uts_namespace *new_ns;

	BUG_ON(!old_ns);
	get_uts_ns(old_ns);

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

	new_ns = clone_uts_ns(tsk, old_ns);

	put_uts_ns(old_ns);
	return new_ns;
}

void free_uts_ns(struct kref *kref)
{
	struct uts_namespace *ns;

	ns = container_of(kref, struct uts_namespace, kref);
	put_user_ns(ns->user_ns);
	kfree(ns);
}

static void *utsns_get(struct task_struct *task)
{
	struct uts_namespace *ns = NULL;
	struct nsproxy *nsproxy;

	rcu_read_lock();
	nsproxy = task_nsproxy(task);
	if (nsproxy) {
		ns = nsproxy->uts_ns;
		get_uts_ns(ns);
	}
	rcu_read_unlock();

	return ns;
}

static void utsns_put(void *ns)
{
	put_uts_ns(ns);
}

static int utsns_install(struct nsproxy *nsproxy, void *ns)
{
	get_uts_ns(ns);
	put_uts_ns(nsproxy->uts_ns);
	nsproxy->uts_ns = ns;
	return 0;
}

const struct proc_ns_operations utsns_operations = {
	.name		= "uts",
	.type		= CLONE_NEWUTS,
	.get		= utsns_get,
	.put		= utsns_put,
	.install	= utsns_install,
};
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2004 IBM Corporation
	3	*
	4	* Author: Serge Hallyn <serue@us.ibm.com>
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License as
	8	* published by the Free Software Foundation, version 2 of the
	9	* License.
	10	*/
	11
	12	#include <linux/export.h>
	13	#include <linux/uts.h>
	14	#include <linux/utsname.h>
	15	#include <linux/err.h>
	16	#include <linux/slab.h>
	17	#include <linux/user_namespace.h>
	18	#include <linux/proc_fs.h>
	19
	20	static struct uts_namespace *create_uts_ns(void)
	21	{
	22	struct uts_namespace *uts_ns;
	23
	24	uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
	25	if (uts_ns)
	26	kref_init(&uts_ns->kref);
	27	return uts_ns;
	28	}
	29
	30	/*
	31	* Clone a new ns copying an original utsname, setting refcount to 1
	32	* @old_ns: namespace to clone
	33	* Return NULL on error (failure to kmalloc), new ns otherwise
	34	*/
	35	static struct uts_namespace clone_uts_ns(struct task_struct tsk,
	36	struct uts_namespace *old_ns)
	37	{
	38	struct uts_namespace *ns;
	39
	40	ns = create_uts_ns();
	41	if (!ns)
	42	return ERR_PTR(-ENOMEM);
	43
	44	down_read(&uts_sem);
	45	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
	46	ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
	47	up_read(&uts_sem);
	48	return ns;
	49	}
	50
	51	/*
	52	* Copy task tsk's utsname namespace, or clone it if flags
	53	* specifies CLONE_NEWUTS. In latter case, changes to the
	54	* utsname of this process won't be seen by parent, and vice
	55	* versa.
	56	*/
	57	struct uts_namespace *copy_utsname(unsigned long flags,
	58	struct task_struct *tsk)
	59	{
	60	struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
	61	struct uts_namespace *new_ns;
	62
	63	BUG_ON(!old_ns);
	64	get_uts_ns(old_ns);
	65
	66	if (!(flags & CLONE_NEWUTS))
	67	return old_ns;
	68
	69	new_ns = clone_uts_ns(tsk, old_ns);
	70
	71	put_uts_ns(old_ns);
	72	return new_ns;
	73	}
	74
	75	void free_uts_ns(struct kref *kref)
	76	{
	77	struct uts_namespace *ns;
	78
	79	ns = container_of(kref, struct uts_namespace, kref);
	80	put_user_ns(ns->user_ns);
	81	kfree(ns);
	82	}
	83
	84	static void utsns_get(struct task_struct task)
	85	{
	86	struct uts_namespace *ns = NULL;
	87	struct nsproxy *nsproxy;
	88
	89	rcu_read_lock();
	90	nsproxy = task_nsproxy(task);
	91	if (nsproxy) {
	92	ns = nsproxy->uts_ns;
	93	get_uts_ns(ns);
	94	}
	95	rcu_read_unlock();
	96
	97	return ns;
	98	}
	99
	100	static void utsns_put(void *ns)
	101	{
	102	put_uts_ns(ns);
	103	}
	104
	105	static int utsns_install(struct nsproxy nsproxy, void ns)
	106	{
	107	get_uts_ns(ns);
	108	put_uts_ns(nsproxy->uts_ns);
	109	nsproxy->uts_ns = ns;
	110	return 0;
	111	}
	112
	113	const struct proc_ns_operations utsns_operations = {
	114	.name = "uts",
	115	.type = CLONE_NEWUTS,
	116	.get = utsns_get,
	117	.put = utsns_put,
	118	.install = utsns_install,
	119	};
	120