netdev - Re: [PATCH] netfilter: ctnetlink: Resolve conntrack L3-protocol flush regression

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Date:   Fri, 3 May 2019 19:05:10 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc:     Kristian Evensen <kristian.evensen@...il.com>,
        netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
        Florian Westphal <fw@...len.de>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH] netfilter: ctnetlink: Resolve conntrack L3-protocol
 flush regression

On Fri, May 03, 2019 at 07:02:54PM +0200, Nicolas Dichtel wrote:
> Please, keep in CC all involved people.
> 
> Le 03/05/2019 à 17:40, Kristian Evensen a écrit :
> > Commit 59c08c69c278 ("netfilter: ctnetlink: Support L3 protocol-filter
> > on flush") introduced a user-space regression when flushing connection
> > track entries. Before this commit, the nfgen_family field was not used
> > by the kernel and all entries were removed. Since this commit,
> > nfgen_family is used to filter out entries that should not be removed.
> > One example a broken tool is conntrack. conntrack always sets
> > nfgen_family to AF_INET, so after 59c08c69c278 only IPv4 entries were
> > removed with the -F parameter.
> > 
> > Pablo Neira Ayuso suggested using nfgenmsg->version to resolve the
> > regression, and this commit implements his suggestion. nfgenmsg->version
> > is so far set to zero, so it is well-suited to be used as a flag for
> > selecting old or new flush behavior. If version is 0, nfgen_family is
> > ignored and all entries are used. If user-space sets the version to one
> > (or any other value than 0), then the new behavior is used. As version
> > only can have two valid values, I chose not to add a new
> > NFNETLINK_VERSION-constant.
> > 
> > Fixes: 59c08c69c278 ("netfilter: ctnetlink: Support L3 protocol-filter
> > on flush")
> > 
> Please, don't break the fixes line and don't separate it from other tags with an
> empty line.

Will fix this before applying, no worries.

> > Reported-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
> > Suggested-by: Pablo Neira Ayuso <pablo@...filter.org>
> > Signed-off-by: Kristian Evensen <kristian.evensen@...il.com>
> Tested-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>