| 1 | /* |
| 2 | * This program is free software; you can redistribute it and/or |
| 3 | * modify it under the terms of the GNU General Public License as |
| 4 | * published by the Free Software Foundation, version 2 of the |
| 5 | * License. |
| 6 | */ |
| 7 | |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/version.h> |
| 10 | #include <linux/nsproxy.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/user_namespace.h> |
| 13 | |
| 14 | /* |
| 15 | * Clone a new ns copying an original user ns, setting refcount to 1 |
| 16 | * @old_ns: namespace to clone |
| 17 | * Return NULL on error (failure to kmalloc), new ns otherwise |
| 18 | */ |
| 19 | static struct user_namespace *clone_user_ns(struct user_namespace *old_ns) |
| 20 | { |
| 21 | struct user_namespace *ns; |
| 22 | struct user_struct *new_user; |
| 23 | int n; |
| 24 | |
| 25 | ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL); |
| 26 | if (!ns) |
| 27 | return ERR_PTR(-ENOMEM); |
| 28 | |
| 29 | kref_init(&ns->kref); |
| 30 | |
| 31 | for (n = 0; n < UIDHASH_SZ; ++n) |
| 32 | INIT_HLIST_HEAD(ns->uidhash_table + n); |
| 33 | |
| 34 | /* Insert new root user. */ |
| 35 | ns->root_user = alloc_uid(ns, 0); |
| 36 | if (!ns->root_user) { |
| 37 | kfree(ns); |
| 38 | return ERR_PTR(-ENOMEM); |
| 39 | } |
| 40 | |
| 41 | /* Reset current->user with a new one */ |
| 42 | new_user = alloc_uid(ns, current->uid); |
| 43 | if (!new_user) { |
| 44 | free_uid(ns->root_user); |
| 45 | kfree(ns); |
| 46 | return ERR_PTR(-ENOMEM); |
| 47 | } |
| 48 | |
| 49 | switch_uid(new_user); |
| 50 | return ns; |
| 51 | } |
| 52 | |
| 53 | struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns) |
| 54 | { |
| 55 | struct user_namespace *new_ns; |
| 56 | |
| 57 | BUG_ON(!old_ns); |
| 58 | get_user_ns(old_ns); |
| 59 | |
| 60 | if (!(flags & CLONE_NEWUSER)) |
| 61 | return old_ns; |
| 62 | |
| 63 | new_ns = clone_user_ns(old_ns); |
| 64 | |
| 65 | put_user_ns(old_ns); |
| 66 | return new_ns; |
| 67 | } |
| 68 | |
| 69 | void free_user_ns(struct kref *kref) |
| 70 | { |
| 71 | struct user_namespace *ns; |
| 72 | |
| 73 | ns = container_of(kref, struct user_namespace, kref); |
| 74 | release_uids(ns); |
| 75 | kfree(ns); |
| 76 | } |
| 77 | EXPORT_SYMBOL(free_user_ns); |