Hello everyone,
I have a problem where a physical hardware device passed through to an LXC
container cannot be read from or written to when I am connected via SSH.
The device node of my physical hardware device looks like this:
myuser@myhost:~$ ls -la /dev/usb/hiddev0
crw-rw-rw- 1 root root 180, 0 Jul 30 10:27 /dev/usb/hiddev0
This is how I create and start my container:
myuser@myhost:~$ sudo lxc-create -q -t debian -n mylxc -- -r stretch
myuser@myhost:~$ sudo lxc-start -n mylxc
Then I add the device node to the LXC:
myuser@myhost:~$ sudo lxc-device -n mylxc add /dev/usb/hiddev0
Afterwards the device is available in the LXC and I can read from it after
having attached to the LXC:
myuser@myhost:~$ sudo lxc-attach -n mylxc
root@mylxc:/# ls -la /dev/usb/hiddev0
crw-r--r-- 1 root root 180, 0 Aug 27 11:26 /dev/usb/hiddev0
root@mylxc:/# cat /dev/usb/hiddev0
����������^C
root@mylxc:/#
I then enable root access via SSH without a password:
myuser@myhost:~$ sudo lxc-attach -n mylxc
root@mylxc:/# sed -i 's/#\?PermitRootLogin.*/PermitRootLogin yes/g'
/etc/ssh/sshd_config
root@mylxc:/# sed -i 's/#\?PermitEmptyPasswords.*/PermitEmptyPasswords
yes/g' /etc/ssh/sshd_config
root@mylxc:/# sed -i 's/#\?UsePAM.*/UsePAM no/g' /etc/ssh/sshd_config
root@mylxc:/# passwd -d root
passwd: password expiry information changed.
root@mylxc:/# /etc/init.d/ssh restart
Restarting ssh (via systemctl): ssh.service.
root@mylxc:/# exit
When I connect via SSH now, the device node is there, but I cannot access it:
myuser@myhost:~$ ssh root@<lxc-ip-address>
root@mylxc:~# ls -la /dev/usb/hiddev0
crw-r--r-- 1 root root 180, 0 Aug 27 11:26 /dev/usb/hiddev0
root@mylxc:~# cat /dev/usb/hiddev0
cat: /dev/usb/hiddev0: Operation not permitted
In both cases (lxc-attach and ssh) I am the root user (verified via whoami), so
this cannot be the problem.
Why am I not allowed to access the device when I am connected via SSH?
Mit freundlichen Grüßen / Best regards
Tim Jaacks
DEVELOPMENT ENGINEER
Garz & Fricke GmbH
Schlachthofstrasse 20
21079 Hamburg
Direct: +49 40 791 899 - 183
Fax: +49 40 791899 - 39
tim.jaa...@garz-fricke.com
www.garz-fricke.com
WE MAKE IT YOURS!
Sitz der Gesellschaft: D-21079 Hamburg
Registergericht: Amtsgericht Hamburg, HRB 60514
Geschäftsführer: Matthias Fricke, Manfred Garz, Marc-Michael Braun
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