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/err.h> 16 #include <linux/slab.h> 17 #include <linux/user_namespace.h> 18 19 static struct uts_namespace *create_uts_ns(void) 20 { 21 struct uts_namespace *uts_ns; 22 23 uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); 24 if (uts_ns) 25 kref_init(&uts_ns->kref); 26 return uts_ns; 27 } 28 29 /* 30 * Clone a new ns copying an original utsname, setting refcount to 1 31 * @old_ns: namespace to clone 32 * Return NULL on error (failure to kmalloc), new ns otherwise 33 */ 34 static struct uts_namespace *clone_uts_ns(struct task_struct *tsk, 35 struct uts_namespace *old_ns) 36 { 37 struct uts_namespace *ns; 38 39 ns = create_uts_ns(); 40 if (!ns) 41 return ERR_PTR(-ENOMEM); 42 43 down_read(&uts_sem); 44 memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); 45 ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns); 46 up_read(&uts_sem); 47 return ns; 48 } 49 50 /* 51 * Copy task tsk's utsname namespace, or clone it if flags 52 * specifies CLONE_NEWUTS. In latter case, changes to the 53 * utsname of this process won't be seen by parent, and vice 54 * versa. 55 */ 56 struct uts_namespace *copy_utsname(unsigned long flags, 57 struct task_struct *tsk) 58 { 59 struct uts_namespace *old_ns = tsk->nsproxy->uts_ns; 60 struct uts_namespace *new_ns; 61 62 BUG_ON(!old_ns); 63 get_uts_ns(old_ns); 64 65 if (!(flags & CLONE_NEWUTS)) 66 return old_ns; 67 68 new_ns = clone_uts_ns(tsk, old_ns); 69 70 put_uts_ns(old_ns); 71 return new_ns; 72 } 73 74 void free_uts_ns(struct kref *kref) 75 { 76 struct uts_namespace *ns; 77 78 ns = container_of(kref, struct uts_namespace, kref); 79 put_user_ns(ns->user_ns); 80 kfree(ns); 81 } 82