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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/version.h>

#include <linux/nsproxy.h>

#include <linux/user_namespace.h>

struct user_namespace init_user_ns = {

        .kref = {

                .refcount       = ATOMIC_INIT(2),

        },

        .root_user = &root_user,

};

EXPORT_SYMBOL_GPL(init_user_ns);

#ifdef CONFIG_USER_NS

/*

 * 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);

}

#endif /* CONFIG_USER_NS */