/* *  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/module.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,};