Re: [PATCH v5 3/4] fuse: Restrict allow_other to the superblock's namespace or a descendant

[Miklos Szeredi <miklos@szeredi.hu>]

On Wed, Oct 22, 2014 at 04:24:19PM -0500, Seth Forshee wrote:
> 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_oth er 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. Therefore access with allow_other should be
> restricted to users in the userns as the superblock or a
> descendant of that namespace.

Fine.

But aren't this kind of thing supposed to be prevented anyway by having private
mount namespace coupled with the pid-user-whatever namespace?

It seems like being a bit too careful (not to say that that's a bad thing).

Thanks,
Miklos