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 17 /* 18 * Clone a new ns copying an original utsname, setting refcount to 1 19 * @old_ns: namespace to clone 20 * Return NULL on error (failure to kmalloc), new ns otherwise 21 */ 22 static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns) 23 { 24 struct uts_namespace *ns; 25 26 ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); 27 if (ns) { 28 memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); 29 kref_init(&ns->kref); 30 } 31 return ns; 32 } 33 34 /* 35 * Copy task tsk's utsname namespace, or clone it if flags 36 * specifies CLONE_NEWUTS. In latter case, changes to the 37 * utsname of this process won't be seen by parent, and vice 38 * versa. 39 */ 40 struct uts_namespace *copy_utsname(int flags, struct uts_namespace *old_ns) 41 { 42 struct uts_namespace *new_ns; 43 44 BUG_ON(!old_ns); 45 get_uts_ns(old_ns); 46 47 if (!(flags & CLONE_NEWUTS)) 48 return old_ns; 49 50 new_ns = clone_uts_ns(old_ns); 51 52 put_uts_ns(old_ns); 53 return new_ns; 54 } 55 56 void free_uts_ns(struct kref *kref) 57 { 58 struct uts_namespace *ns; 59 60 ns = container_of(kref, struct uts_namespace, kref); 61 kfree(ns); 62 } 63