Re: [PATCH 4/4] netfilter: Fix format string of nfnetlink_queue proc file

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Fri, Mar 13, 2015 at 02:43:54PM +0100, Richard Weinberger wrote:
> Am 13.03.2015 um 13:15 schrieb Pablo Neira Ayuso:
> > On Fri, Mar 13, 2015 at 12:31:16PM +0100, Richard Weinberger wrote:
> >> The printed values are all of type unsigned integer, therefore use
> >> %u instead of %d. Otherwise an user can face negative values.
> >>
> >> Fixes:
> >> $ cat /proc/net/netfilter/nfnetlink_queue
> >>     0  29508   278 2 65531     0 2004213241 -2129885586  1
> >>     1 -27747     0 2 65531     0     0        0  1
> >>     2 -27748     0 2 65531     0     0        0  1
> > 
> > I guess you want to access stats on dropped packets.
> 
> Correct. :)
> 
> > I prefer if you extend nfnetlink_queue to provide statistics through
> > nfnetlink_queue, so you don't have to manually parse this text-based
> > /proc entry and we can deprecate this interface. That shouldn't have
> > been there in first place.
> 
> You mean statistics via netlink attributes? I can add that!

Add a new NFQNL_CFG_CMD_STATS command to request the statistics. If
NLM_F_DUMP is set, then we'll basically provide the full list of
instances. Otherwise, in case you want to retrieve stats for a
specific netlink socket, you can use the netlink portID as index.
And you'll have to add attributes for this new command, yes.

> But I think we should also fix the format string of the proc file
> as the fix is easy and non-intrusive.

Unfortunately we don't know how many people are relying on that
output, I prefer to remain conservative and provide a proper netlink
interface for this.