Re: [RFC 1/1] shiftfs: uid/gid shifting bind mount

From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Djalal Harouni <tixxdz@gmail.com>, Chris Mason <clm@fb.com>,
	tytso@mit.edu, Serge Hallyn <serge.hallyn@canonical.com>,
	Josh Triplett <josh@joshtriplett.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Andy Lutomirski <luto@kernel.org>,
	Seth Forshee <seth.forshee@canonical.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	Dongsu Park <dongsu@endocode.com>,
	David Herrmann <dh.herrmann@googlemail.com>,
	Miklos Szeredi <mszeredi@redhat.com>,
	Alban Crequy <alban.crequy@gmail.com>,
	Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [RFC 1/1] shiftfs: uid/gid shifting bind mount
Date: Mon, 16 May 2016 22:28:32 -0400	[thread overview]
Message-ID: <1463452112.4101.25.camel@HansenPartnership.com> (raw)
In-Reply-To: <20160516194117.GA29354@ubuntumail>

On Mon, 2016-05-16 at 19:41 +0000, Serge Hallyn wrote:
> Hey James,
> 
> I probably did something wrong - but i applied your patch onto 4.6,
> compiled in shiftfs, did
> 
> mount -t shiftfs -o uidmap=0:100000:65536,gidmap=0:100000:65536
> /home/ubuntu /mnt
> 
> and ls segfaults and gives me kernel syslog msgs like:

Hm, it looks to be something IMA related, since the SUSE default is no
IMA and this BUG in the filesystem is to do with the IMA version of
i_readcount_dec.  I'll recompile my kernel to see if I can reproduce. 
 Just in case, what's the underlying filesystem on /home/ubuntu?

Thanks,

James