linux-kernel - Re: How do I make a clean mount namespace?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140424023925.GW18016@ZenIV.linux.org.uk>
Date:	Thu, 24 Apr 2014 03:39:25 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux FS Devel <linux-fsdevel@...r.kernel.org>
Subject: Re: How do I make a clean mount namespace?

On Tue, Apr 22, 2014 at 03:12:11PM -0700, Andy Lutomirski wrote:
> I want to set up a little container.  So I unshare the mount namespace
> and mount something somewhere (say /mnt) that I want to be my new
> root.  Now what?
> 
> pivot_root("/mnt", "/mnt/garbage") seems to frequently return -EBUSY.

RTFM.  Literally - man 2 pivot_root and look for the only place where
it mentions EBUSY.

If you get that error, check what you've got in /proc/mounts (in the
namespace your process is in, obviously) just before the syscall.
With these arguments you really want /mnt to be a mountpoint.  If your
new root really lives on the same fs as the old one, just do
mount --bind /mnt /mnt before any other mounts.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/