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/*
* 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;
struct cred *new;
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);
}
/* Install the new user */
new = prepare_creds();
if (!new) {
free_uid(new_user);
free_uid(ns->root_user);
kfree(ns);
}
free_uid(new->user);
new->user = new_user;
commit_creds(new);
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);
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