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 down_read(&uts_sem); 32 memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); 33 up_read(&uts_sem); 34 kref_init(&ns->kref); 35 return ns; 36 } 37 38 /* 39 * Copy task tsk's utsname namespace, or clone it if flags 40 * specifies CLONE_NEWUTS. In latter case, changes to the 41 * utsname of this process won't be seen by parent, and vice 42 * versa. 43 */ 44 struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns) 45 { 46 struct uts_namespace *new_ns; 47 48 BUG_ON(!old_ns); 49 get_uts_ns(old_ns); 50 51 if (!(flags & CLONE_NEWUTS)) 52 return old_ns; 53 54 new_ns = clone_uts_ns(old_ns); 55 56 put_uts_ns(old_ns); 57 return new_ns; 58 } 59 60 void free_uts_ns(struct kref *kref) 61 { 62 struct uts_namespace *ns; 63 64 ns = container_of(kref, struct uts_namespace, kref); 65 kfree(ns); 66 } 67