Re: [PATCH nf] netfilter: conntrack: warn the user if there is a better helper to use

[Marcelo Ricardo Leitner <mleitner@redhat.com>]

Ahm, ping? :)

On Thu, May 21, 2015 at 10:57:12AM -0300, Marcelo Ricardo Leitner wrote:
> From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> 
> After db29a9508a92 ("netfilter: conntrack: disable generic tracking for
> known protocols"), if the specific helper is built but not loaded
> (a standard for most distributions) systems with a restrictive firewall
> but weak configuration regarding netfilter modules to load, will
> silently stop working.
> 
> This patch then puts a warning message so the sysadmin knows where to
> start looking into. It's a pr_warn_once regardless of protocol itself
> but it should be enough to give a hint on where to look.
> 
> Cc: Florian Westphal <fw@strlen.de>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> ---
>  net/netfilter/nf_conntrack_proto_generic.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/nf_conntrack_proto_generic.c b/net/netfilter/nf_conntrack_proto_generic.c
> index 60865f1103099383c4263a1a56e691b3c86c3720..2281be419a74b6d8abe0fd7da8d7e8b35d304600 100644
> --- a/net/netfilter/nf_conntrack_proto_generic.c
> +++ b/net/netfilter/nf_conntrack_proto_generic.c
> @@ -90,7 +90,13 @@ static int generic_packet(struct nf_conn *ct,
>  static bool generic_new(struct nf_conn *ct, const struct sk_buff *skb,
>  			unsigned int dataoff, unsigned int *timeouts)
>  {
> -	return nf_generic_should_process(nf_ct_protonum(ct));
> +	bool ret;
> +
> +	ret = nf_generic_should_process(nf_ct_protonum(ct));
> +	if (!ret)
> +		pr_warn_once("conntrack: generic helper won't handle protocol %d. Please consider loading the specific helper module.\n",
> +			     nf_ct_protonum(ct));
> +	return ret;
>  }
>  
>  #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
> -- 
> 2.4.1
> 
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