From d340e042668254aa4f4b3547c2967bd46894e81c Mon Sep 17 00:00:00 2001 From: Seth Forshee Date: Thu, 2 Oct 2014 15:34:45 -0500 Subject: [PATCH] UBUNTU: SAUCE: (namespace) 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. Acked-by: Serge Hallyn Acked-by: Miklos Szeredi Signed-off-by: Seth Forshee --- fs/fuse/dir.c | 2 +- kernel/user_namespace.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index ea24eae8a576..4c2d2cb1c1d5 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1034,7 +1034,7 @@ int fuse_allow_current_process(struct fuse_conn *fc) const struct cred *cred; if (fc->allow_other) - return 1; + return current_in_userns(fc->user_ns); cred = current_cred(); if (uid_eq(cred->euid, fc->user_id) && diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 7669f19a05ff..eca75f02403f 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -1003,6 +1003,7 @@ bool current_in_userns(const struct user_namespace *target_ns) } return false; } +EXPORT_SYMBOL(current_in_userns); static inline struct user_namespace *to_user_ns(struct ns_common *ns) { -- 2.39.2