/* * 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/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);