From 779668450a990d402d316ffd9b7b103fbe5ab6f3 Mon Sep 17 00:00:00 2001
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Thu, 21 May 2015 10:57:12 -0300
Subject: [PATCH] netfilter: conntrack: warn the user if there is a better
helper to use
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>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
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 60865f1103099..2281be419a74b 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)
--
2.30.2