Kernel log message corruption due to incomplete /proc separation

[Michael B. Trausch]

Binary package hint: lxc

When using LXC (linux containers), /proc/kmsg can be read in guest systems in their filtered view of /proc. This special file should never be present in guest systems, and if created within a guest system, it should be effectively using /dev/null as it's source. The effect of this bug ranges from simply annoying to potentially a security issue in that kernel messages are allowed to be destroyed and never fully logged on the host system, which could be used to cover evidence of some sort of attack on the system.

I'm adding the kernel team as well, as this could be an issue inside the kernel. I'm not sure if /proc filtration happens there or in the context of the lxc userland utilities.

[Michael B. Trausch (mtrausch)]

I should note that this is in Karmic, fully updated as of 05:19 on 26-Oct-2009, EDT (GMT-0400).

[Daniel Hahler (blueyed)]

hallyn talked on #lxcontainers about adding a "patch to define CAP_SYSLOG" and sent it to the mailinglist at https://lists.linux-foundation.org/pipermail/containers/2010-March/023364.html

[Serge Hallyn (serge-hallyn)]

(Note this will come after completion of user namespaces)

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 460925

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Stéphane Graber (stgraber)]

Added bot-stop-nagging.

[Serge Hallyn (serge-hallyn)]

Design notes are at http://wiki.ubuntu.com/LxcSyslogNs