netdev - [PATCH] netfilter: fix checking method of conntrack helper

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Date:   Mon, 14 Jan 2019 17:59:43 +0800
From:   Henry Yen <henry.yen@...iatek.com>
To:     Pablo Neira Ayuso <pablo@...filter.org>,
        "David S. Miller" <davem@...emloft.net>
CC:     Ryder Lee <ryder.lee@...iatek.com>,
        Sean Wang <sean.wang@...nel.org>,
        Weijie Gao <weijie.gao@...iatek.com>,
        <netfilter-devel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        Henry Yen <henry.yen@...iatek.com>
Subject: [PATCH] netfilter: fix checking method of conntrack helper

This patch uses nfct_help() to detect whether an
established connection needs conntrack helper instead of using
test_bit(IPS_HELPER_BIT, &ct->status).

The reason is that IPS_HELPER_BIT is only set when using explicit
CT target.

However, in the case that a device enables conntrack helper via
command "echo 1 > /proc/sys/net/netfilter/nf_conntrack_helper",
the status of IPS_HELPER_BIT will not present any change, and
consequently it loses the checking ability in the context.

Signed-off-by: Henry Yen <henry.yen@...iatek.com>
Reviewed-by: Ryder Lee <ryder.lee@...iatek.com>
---
 net/netfilter/nft_flow_offload.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index 974525eb92df..de4684cc4633 100644
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -12,6 +12,7 @@
 #include <net/netfilter/nf_conntrack_core.h>
 #include <linux/netfilter/nf_conntrack_common.h>
 #include <net/netfilter/nf_flow_table.h>
+#include <net/netfilter/nf_conntrack_helper.h>
 
 struct nft_flow_offload {
 	struct nft_flowtable	*flowtable;
@@ -71,6 +72,7 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
 	struct flow_offload *flow;
 	enum ip_conntrack_dir dir;
 	struct nf_conn *ct;
+	const struct nf_conn_help *help;
 	int ret;
 
 	if (nft_flow_offload_skip(pkt->skb))
@@ -88,7 +90,8 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
 		goto out;
 	}
 
-	if (test_bit(IPS_HELPER_BIT, &ct->status))
+	help = nfct_help(ct);
+	if (help)
 		goto out;
 
 	if (ctinfo == IP_CT_NEW ||
-- 
2.17.1