diff options
Diffstat (limited to 'kernel/user_namespace.c')
| -rw-r--r-- | kernel/user_namespace.c | 46 |
1 files changed, 45 insertions, 1 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 3d796420977..89a27e8b17f 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -21,6 +21,45 @@ EXPORT_SYMBOL_GPL(init_user_ns); #ifdef CONFIG_USER_NS +/* + * Clone a new ns copying an original user ns, setting refcount to 1 + * @old_ns: namespace to clone + * Return NULL on error (failure to kmalloc), new ns otherwise + */ +static struct user_namespace *clone_user_ns(struct user_namespace *old_ns) +{ + struct user_namespace *ns; + struct user_struct *new_user; + int n; + + ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL); + if (!ns) + return NULL; + + kref_init(&ns->kref); + + for (n = 0; n < UIDHASH_SZ; ++n) + INIT_LIST_HEAD(ns->uidhash_table + n); + + /* Insert new root user. */ + ns->root_user = alloc_uid(ns, 0); + if (!ns->root_user) { + kfree(ns); + return NULL; + } + + /* Reset current->user with a new one */ + new_user = alloc_uid(ns, current->uid); + if (!new_user) { + free_uid(ns->root_user); + kfree(ns); + return NULL; + } + + switch_uid(new_user); + return ns; +} + struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns) { struct user_namespace *new_ns; @@ -28,7 +67,12 @@ struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns) BUG_ON(!old_ns); get_user_ns(old_ns); - new_ns = old_ns; + if (!(flags & CLONE_NEWUSER)) + return old_ns; + + new_ns = clone_user_ns(old_ns); + + put_user_ns(old_ns); return new_ns; } |