From 73f03c2b4b527346778c711c2734dbff3442b139 Mon Sep 17 00:00:00 2001 From: Seth Forshee Date: Fri, 22 Dec 2017 15:32:33 +0100 Subject: fuse: Restrict allow_other to the superblock's namespace or a descendant Unprivileged users are normally restricted from mounting with the allow_other option by system policy, but this could be bypassed for a mount done with user namespace root permissions. In such cases allow_other should not allow users outside the userns to access the mount as doing so would give the unprivileged user the ability to manipulate processes it would otherwise be unable to manipulate. Restrict allow_other to apply to users in the same userns used at mount or a descendant of that namespace. Also export current_in_userns() for use by fuse when built as a module. Reviewed-by: Serge Hallyn Signed-off-by: Seth Forshee Signed-off-by: Dongsu Park Signed-off-by: Eric W. Biederman Signed-off-by: Miklos Szeredi --- kernel/user_namespace.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 246d4d4ce5c7..492c255e6c5a 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -1235,6 +1235,7 @@ bool current_in_userns(const struct user_namespace *target_ns) { return in_userns(target_ns, current_user_ns()); } +EXPORT_SYMBOL(current_in_userns); static inline struct user_namespace *to_user_ns(struct ns_common *ns) { -- cgit v1.2.3