[PATCH] H.245 ALG dropping packets

[PATCH] H.245 ALG dropping packets

[Blair Steven]

We have a setup where two VoIP phones are communicating through a
router on a trusted LAN where the H.245 ALG is dropping some of the
traffic, so far as I can tell without good cause. These two devices
are configured differently, one with Fast Connect and one without -
this might be the reason, but from my (limited) understanding of ALGs
this isn't a good enough reason.

Does it ever make sense to drop packets in an ALG?

Blair Steven (1):
  Accept packets that the H.245 ALG can't process

 net/netfilter/nf_conntrack_h323_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

-- 
2.9.3

[PATCH] Accept packets that the H.245 ALG can't process

[Blair Steven]

When two VoIP end points are configured differently (fast connect /
not fast connect) the ALG was failing to find a matching expectation
and dropping packets in one direction.

Dropping packets not the job of an ALG, and as such the behaviour
has been changed to allow the packet to be send to the forwarding
engine.

Signed-off-by: Blair Steven <blair.steven@alliedtelesis.co.nz>
---
 net/netfilter/nf_conntrack_h323_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c
index 3bcdc71..6161375 100644
--- a/net/netfilter/nf_conntrack_h323_main.c
+++ b/net/netfilter/nf_conntrack_h323_main.c
@@ -625,7 +625,7 @@ static int h245_help(struct sk_buff *skb, unsigned int protoff,
       drop:
 	spin_unlock_bh(&nf_h323_lock);
 	nf_ct_helper_log(skb, ct, "cannot process H.245 message");
-	return NF_DROP;
+	return NF_ACCEPT;
 }
 
 /****************************************************************************/
@@ -1200,7 +1200,7 @@ static int q931_help(struct sk_buff *skb, unsigned int protoff,
       drop:
 	spin_unlock_bh(&nf_h323_lock);
 	nf_ct_helper_log(skb, ct, "cannot process Q.931 message");
-	return NF_DROP;
+	return NF_ACCEPT;
 }
 
 /****************************************************************************/
@@ -1785,7 +1785,7 @@ static int ras_help(struct sk_buff *skb, unsigned int protoff,
       drop:
 	spin_unlock_bh(&nf_h323_lock);
 	nf_ct_helper_log(skb, ct, "cannot process RAS message");
-	return NF_DROP;
+	return NF_ACCEPT;
 }
 
 /****************************************************************************/
-- 
2.9.3

Re: [PATCH] Accept packets that the H.245 ALG can't process

[Sergei Shtylyov]

Hello!

On 5/22/2017 5:07 AM, Blair Steven wrote:

> When two VoIP end points are configured differently (fast connect /
> not fast connect) the ALG was failing to find a matching expectation
> and dropping packets in one direction.
>
> Dropping packets not the job of an ALG, and as such the behaviour

    s/not/is not/. Perhaps could be fixed while applying...

> has been changed to allow the packet to be send to the forwarding
> engine.
>
> Signed-off-by: Blair Steven <blair.steven@alliedtelesis.co.nz>
[...]

MBR, Sergei