From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.kundenserver.de ([212.227.126.131]:51621 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726244AbeJBREF (ORCPT ); Tue, 2 Oct 2018 13:04:05 -0400 From: Laurent Vivier To: linux-kernel@vger.kernel.org Cc: Dmitry Safonov , Andrei Vagin , Eric Biederman , Alexander Viro , James Bottomley , containers@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Laurent Vivier Subject: [RFC v2 v2 0/1] ns: introduce binfmt_misc namespace Date: Tue, 2 Oct 2018 12:20:53 +0200 Message-Id: <20181002102054.13245-1-laurent@vivier.eu> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: v2: no new namespace, binfmt_misc data are now part of the mount namespace I put this in mount namespace instead of user namespace because the mount namespace is already needed and I don't want to force to have the user namespace for that. As this is a filesystem, it seems logic to have it here. This allows to define a new interpreter for each new container. But the main goal is to be able to chroot to a directory using a binfmt_misc interpreter without being root. I have a modified version of unshare at: git@github.com:vivier/util-linux.git branch unshare-chroot with some new options to unshare binfmt_misc namespace and to chroot to a directory. If you have a directory /chroot/powerpc/jessie containing debian for powerpc binaries and a qemu-ppc interpreter, you can do for instance: $ uname -a Linux fedora28-wor-2 4.19.0-rc5+ #18 SMP Mon Oct 1 00:32:34 CEST 2018 x86_64 x86_64 x86_64 GNU/Linux $ ./unshare --map-root-user --fork --pid \ --load-interp ":qemu-ppc:M::\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x14:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff:/qemu-ppc:OC" \ --root=/chroot/powerpc/jessie /bin/bash -l # uname -a Linux fedora28-wor-2 4.19.0-rc5+ #18 SMP Mon Oct 1 00:32:34 CEST 2018 ppc GNU/Linux # id uid=0(root) gid=0(root) groups=0(root),65534(nogroup) # ls -l total 5940 drwxr-xr-x. 2 nobody nogroup 4096 Aug 12 00:58 bin drwxr-xr-x. 2 nobody nogroup 4096 Jun 17 20:26 boot drwxr-xr-x. 4 nobody nogroup 4096 Aug 12 00:08 dev drwxr-xr-x. 42 nobody nogroup 4096 Sep 28 07:25 etc drwxr-xr-x. 3 nobody nogroup 4096 Sep 28 07:25 home drwxr-xr-x. 9 nobody nogroup 4096 Aug 12 00:58 lib drwxr-xr-x. 2 nobody nogroup 4096 Aug 12 00:08 media drwxr-xr-x. 2 nobody nogroup 4096 Aug 12 00:08 mnt drwxr-xr-x. 3 nobody nogroup 4096 Aug 12 13:09 opt dr-xr-xr-x. 143 nobody nogroup 0 Sep 30 23:02 proc -rwxr-xr-x. 1 nobody nogroup 6009712 Sep 28 07:22 qemu-ppc drwx------. 3 nobody nogroup 4096 Aug 12 12:54 root drwxr-xr-x. 3 nobody nogroup 4096 Aug 12 00:08 run drwxr-xr-x. 2 nobody nogroup 4096 Aug 12 00:58 sbin drwxr-xr-x. 2 nobody nogroup 4096 Aug 12 00:08 srv drwxr-xr-x. 2 nobody nogroup 4096 Apr 6 2015 sys drwxrwxrwt. 2 nobody nogroup 4096 Sep 28 10:31 tmp drwxr-xr-x. 10 nobody nogroup 4096 Aug 12 00:08 usr drwxr-xr-x. 11 nobody nogroup 4096 Aug 12 00:08 var If you want to use the qemu binary provided by your distro, you can use --load-interp ":qemu-ppc:M::\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x14:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff:/bin/qemu-ppc-static:OCF" With the 'F' flag, qemu-ppc-static will be then loaded from the main root filesystem before switching to the chroot. Laurent Vivier (1): ns: add binfmt_misc to the mount namespace fs/binfmt_misc.c | 50 +++++++++++++++++++++++++----------------------- fs/mount.h | 8 ++++++++ fs/namespace.c | 6 ++++++ 3 files changed, 40 insertions(+), 24 deletions(-) -- 2.17.1