Re: [PATCH nf-next] netfilter: allow logging from non-init namespaces

On Thu, May 12, 2016 at 11:57:26AM +0200, Pablo Neira Ayuso wrote:

Hi Michal,

On Wed, Apr 27, 2016 at 02:48:02PM +0200, Michal Kubecek wrote:

quoted

Commit 69b34fb996b2 ("netfilter: xt_LOG: add net namespace support for
xt_LOG") disabled logging packets using the LOG target from non-init
namespaces. The motivation was to prevent containers from flooding
kernel log of the host. The plan was to keep it that way until syslog
namespace implementation allows containers to log in a safe way.

However, the work on syslog namespace seems to have hit a dead end
somewhere in 2013 and there are users who want to use xt_LOG in all
network namespaces. This patch allows to do so by setting

I understand this stuff is tricky. Did you contact already namespace
folks to see if they plan any move on this?

Not yet. I'll contact the people involved in the discussion about the
serires submitted in 2013 to check what their plans are (and if there
are any).

quoted

  /proc/sys/net/netfilter/nf_log_all_netns

My only concern with this is that I don't see how users know what log
message has triggered from what container.

IMHO this is a more generic issue with containers: there is no (known to
me) link between userspace "containers" and kernel namespaces that could
be used in kernel log messages. In this case, --log-prefix can be used
in netfilter logging rules to identify the container messages belong to.

                                                          Michal Kubecek