| 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 | |
| 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 | } |