linux-kernel - RE: [PATCH 2/4] fs: define a firmware security filesystem named fwsecurityfs

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Date:   Mon, 21 Nov 2022 16:12:53 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'James Bottomley' <James.Bottomley@...senPartnership.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
CC:     Matthew Garrett <mjg59@...f.ucam.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        Nayna <nayna@...ux.vnet.ibm.com>,
        "Andrew Donnellan" <ajd@...ux.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "npiggin@...il.com" <npiggin@...il.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Dave Hansen <dave.hansen@...el.com>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        Paul Mackerras <paulus@...ba.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "George Wilson" <gcwilson@...ux.ibm.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        Stefan Berger <stefanb@...ux.ibm.com>
Subject: RE: [PATCH 2/4] fs: define a firmware security filesystem named
 fwsecurityfs

From: James Bottomley
> Sent: 21 November 2022 14:03
...
> > Then how does the networking code handle the namespace stuff in
> > sysfs?
> > That seems to work today, or am I missing something?
> 
> have you actually tried?
> 
> jejb@...grow:~> sudo unshare --net bash
> lingrow:/home/jejb # ls /sys/class/net/
> lo  tun0  tun10  wlan0
> lingrow:/home/jejb # ip link show
> 1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN mode DEFAULT group
> default qlen 1000
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> 
> So, as you see, I've entered a network namespace and ip link shows me
> the only interface I can see in that namespace (a down loopback) but
> sysfs shows me every interface on the system outside the namespace.

You have to remount /sys to get the restricted copy.
eg by running 'ip netns exec namespace command'.

	David

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