netdev - Re: [PATCH] MD5: don't warn when an unexpected signature is seen.

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Date:	Wed, 30 Jul 2008 11:45:50 +0300 (EEST)
From:	Pekka Savola <pekkas@...core.fi>
To:	Adam Langley <agl@...erialviolet.org>
cc:	davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH] MD5: don't warn when an unexpected signature is seen.

Just wondering.  If the warning is removed, should this be tracked 
somewhere else, e.g. 'netstat -s' TCP statistics?

On Tue, 29 Jul 2008, Adam Langley wrote:
> Currently, connecting to a listening socket with an MD5 signature option, when
> MD5 is not configured on the listening socket, will generate the following
> warning:
>  MD5 Hash NOT expected but found
>
> This is rate limited, but too verbose given that it can be induced with an
> unverified SYN packet.
>
> This patch removes the warning
>
> Signed-off-by: Adam Langley <agl@...erialviolet.org>
> ---
>
> net/ipv4/tcp_ipv4.c |    7 +------
> net/ipv6/tcp_ipv6.c |    7 -------
> 2 files changed, 1 insertions(+), 13 deletions(-)
>
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index a2b06d0..8cafa92 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -1123,13 +1123,8 @@ static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
> 		return 1;
> 	}
>
> -	if (!hash_expected && hash_location) {
> -		LIMIT_NETDEBUG(KERN_INFO "MD5 Hash NOT expected but found "
> -			       "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)\n",
> -			       NIPQUAD(iph->saddr), ntohs(th->source),
> -			       NIPQUAD(iph->daddr), ntohs(th->dest));
> +	if (!hash_expected && hash_location)
> 		return 1;
> -	}
>
> 	/* Okay, so this is hash_expected and hash_location -
> 	 * so we need to calculate the checksum.
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index cff778b..7bb588c 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -853,13 +853,6 @@ static int tcp_v6_inbound_md5_hash (struct sock *sk, struct sk_buff *skb)
> 	if (!hash_expected) {
> 		if (!hash_location)
> 			return 0;
> -		if (net_ratelimit()) {
> -			printk(KERN_INFO "MD5 Hash NOT expected but found "
> -			       "(" NIP6_FMT ", %u)->"
> -			       "(" NIP6_FMT ", %u)\n",
> -			       NIP6(ip6h->saddr), ntohs(th->source),
> -			       NIP6(ip6h->daddr), ntohs(th->dest));
> -		}
> 		return 1;
> 	}
>
> --
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-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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