netdev - Re: [iproute PATCH] lib/namespace: avoid double-mounting a /sys

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] [day] [month] [year] [list]

Date:   Fri, 27 Jul 2018 13:45:05 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Lubomir Rintel <lkundrak@...sk>
Cc:     netdev@...r.kernel.org, Phil Sutter <phil@....cc>
Subject: Re: [iproute PATCH] lib/namespace: avoid double-mounting a /sys

On Tue, 24 Jul 2018 19:26:38 +0200
Lubomir Rintel <lkundrak@...sk> wrote:

> This partly reverts 8f0807023d067e2bb585a2ae8da93e59689d10f1, bringing
> back the umount(/sys) attempt.
> 
> In a LXC container we're unable to umount the sysfs instance, nor mount
> a read-write one. We still are able to create a new read-only instance.
> 
> Nevertheless, it still makes sense to attempt the umount() even though
> the sysfs is mounted read-only. Otherwise we may end up attempting to
> mount a sysfs with the same flags as is already mounted, resulting in
> an EBUSY error (meaning "Already mounted").
> 
> Perhaps this is not a very likely scenario in real world, but we hit
> it in NetworkManager test suite and makes netns_switch() somewhat more
> robust. It also fixes the case, when /sys wasn't mounted at all.
> 
> Signed-off-by: Lubomir Rintel <lkundrak@...sk>

Makes sens applied.