From: Oleg Nesterov Date: Thu, 8 Aug 2013 16:55:32 +0000 (+0200) Subject: userns: limit the maximum depth of user_namespace->parent chain X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=8742f229b635bf1c1c84a3dfe5e47c814c20b5c8;p=deliverable%2Flinux.git userns: limit the maximum depth of user_namespace->parent chain Ensure that user_namespace->parent chain can't grow too much. Currently we use the hardroded 32 as limit. Reported-by: Andy Lutomirski Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds --- diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index b6b215f13b45..14105c26a836 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -23,6 +23,7 @@ struct user_namespace { struct uid_gid_map projid_map; atomic_t count; struct user_namespace *parent; + int level; kuid_t owner; kgid_t group; unsigned int proc_inum; diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 6e50a44610ee..9064b919a406 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -62,6 +62,9 @@ int create_user_ns(struct cred *new) kgid_t group = new->egid; int ret; + if (parent_ns->level > 32) + return -EUSERS; + /* * Verify that we can not violate the policy of which files * may be accessed that is specified by the root directory, @@ -92,6 +95,7 @@ int create_user_ns(struct cred *new) atomic_set(&ns->count, 1); /* Leave the new->user_ns reference with the new user namespace. */ ns->parent = parent_ns; + ns->level = parent_ns->level + 1; ns->owner = owner; ns->group = group;