/* * 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, };