1 /* 2 * Copyright (C) 2004 IBM Corporation 3 * 4 * Author: Serge Hallyn <serue@us.ibm.com> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation, version 2 of the 9 * License. 10 */ 11 12 #include <linux/module.h> 13 #include <linux/uts.h> 14 #include <linux/utsname.h> 15 #include <linux/version.h> 16 #include <linux/err.h> 17 18 /* 19 * Clone a new ns copying an original utsname, setting refcount to 1 20 * @old_ns: namespace to clone 21 * Return NULL on error (failure to kmalloc), new ns otherwise 22 */ 23 static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns) 24 { 25 struct uts_namespace *ns; 26 27 ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); 28 if (!ns) 29 return ERR_PTR(-ENOMEM); 30 31 memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); 32 kref_init(&ns->kref); 33 return ns; 34 } 35 36 /* 37 * Copy task tsk's utsname namespace, or clone it if flags 38 * specifies CLONE_NEWUTS. In latter case, changes to the 39 * utsname of this process won't be seen by parent, and vice 40 * versa. 41 */ 42 struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns) 43 { 44 struct uts_namespace *new_ns; 45 46 BUG_ON(!old_ns); 47 get_uts_ns(old_ns); 48 49 if (!(flags & CLONE_NEWUTS)) 50 return old_ns; 51 52 new_ns = clone_uts_ns(old_ns); 53 54 put_uts_ns(old_ns); 55 return new_ns; 56 } 57 58 void free_uts_ns(struct kref *kref) 59 { 60 struct uts_namespace *ns; 61 62 ns = container_of(kref, struct uts_namespace, kref); 63 kfree(ns); 64 } 65