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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 for this modification is that IPS_HELPER_BIT is only set when
the conntrack helper is attached by explicit CT target.

However, in the case that a device enables conntrack helper via the other
ways (e.g., command "echo 1 > /proc/sys/net/netfilter/nf_conntrack_helper")
, the status of IPS_HELPER_BIT will not present any change. That means the
IPS_HELPER_BIT might lose the checking ability in the context.

Signed-off-by: HsiuWen Yen <y.hsiuwen@gmail.com>
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HenryHsiu authored and nbd168 committed Jan 31, 2019
1 parent 61e01f2 commit 33b690216e766f2157871aa64190f9bb72334049
Showing with 51 additions and 0 deletions.
  1. +51 −0 target/linux/generic/hack-4.14/941-fix-checking-method-of-conntrack-helper.patch
@@ -0,0 +1,51 @@
From addf8974ce9987e2946e04624fe806a98390786e Mon Sep 17 00:00:00 2001
From: HsiuWen Yen <y.hsiuwen@gmail.com>
Date: Wed, 30 Jan 2019 11:45:25 +0800
Subject: [PATCH] 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 for this modification is that IPS_HELPER_BIT is only set when
the conntrack helper is attached by explicit CT target.

However, in the case that a device enables conntrack helper via the other
ways (e.g., command "echo 1 > /proc/sys/net/netfilter/nf_conntrack_helper")
, the status of IPS_HELPER_BIT will not present any change. That means the
IPS_HELPER_BIT might lose the checking ability in the context.

Signed-off-by: HsiuWen Yen <y.hsiuwen@gmail.com>
---
net/netfilter/xt_FLOWOFFLOAD.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/netfilter/xt_FLOWOFFLOAD.c
+++ b/net/netfilter/xt_FLOWOFFLOAD.c
@@ -12,6 +12,7 @@
#include <net/ip.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_flow_table.h>
+#include <net/netfilter/nf_conntrack_helper.h>

static struct nf_flowtable nf_flowtable;
static HLIST_HEAD(hooks);
@@ -245,6 +246,7 @@ flowoffload_tg(struct sk_buff *skb, const struct xt_action_param *par)
struct nf_flow_route route;
struct flow_offload *flow;
struct nf_conn *ct;
+ const struct nf_conn_help *help;

if (xt_flowoffload_skip(skb))
return XT_CONTINUE;
@@ -264,7 +266,8 @@ flowoffload_tg(struct sk_buff *skb, const struct xt_action_param *par)
return XT_CONTINUE;
}

- if (test_bit(IPS_HELPER_BIT, &ct->status))
+ help = nfct_help(ct);
+ if (help)
return XT_CONTINUE;

if (ctinfo == IP_CT_NEW ||

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