netdev - Re: [RFC PATCH net-next v2 7/8] openvswitch: Delay conntrack helper call for new connections.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151109132601.GB8098@macbook.localdomain>
Date:	Mon, 9 Nov 2015 13:26:01 +0000
From:	Patrick McHardy <kaber@...sh.net>
To:	Jarno Rajahalme <jrajahalme@...ira.com>
Cc:	netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
	dev@...nvswitch.org
Subject: Re: [RFC PATCH net-next v2 7/8] openvswitch: Delay conntrack helper
 call for new connections.

On 06.11, Jarno Rajahalme wrote:
> There is no need to help connections that are not confirmed, so we can
> delay helping new connections to the time when they are confirmed.
> This change is needed for NAT support, and having this as a separate
> patch will make the following NAT patch a bit easier to review.

For the first packet a helper receives the connection is always unconfirmed.
It makes no sense to confirm it if the helper drops the packet.

> Signed-off-by: Jarno Rajahalme <jrajahalme@...ira.com>
> ---
>  net/openvswitch/conntrack.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> index 7aa38fa..ba44287 100644
> --- a/net/openvswitch/conntrack.c
> +++ b/net/openvswitch/conntrack.c
> @@ -458,6 +458,7 @@ static bool skb_nfct_cached(struct net *net,
>  /* Pass 'skb' through conntrack in 'net', using zone configured in 'info', if
>   * not done already.  Update key with new CT state after passing the packet
>   * through conntrack.
> + * Note that invalid packets are accepted while the skb->nfct remains unset!
>   */
>  static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
>  			   const struct ovs_conntrack_info *info,
> @@ -468,7 +469,11 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
>  	 * actually run the packet through conntrack twice unless it's for a
>  	 * different zone.
>  	 */
> -	if (!skb_nfct_cached(net, key, info, skb)) {
> +	bool cached = skb_nfct_cached(net, key, info, skb);
> +	enum ip_conntrack_info ctinfo;
> +	struct nf_conn *ct;
> +
> +	if (!cached) {
>  		struct nf_conn *tmpl = info->ct;
>  		int err;
>  
> @@ -491,11 +496,16 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
>  			return -ENOENT;
>  
>  		ovs_ct_update_key(skb, key, true);
> +	}
>  
> -		if (ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
> -			WARN_ONCE(1, "helper rejected packet");
> -			return -EINVAL;
> -		}
> +	/* Call the helper right after nf_conntrack_in() for confirmed
> +	 * connections, but only when commiting for unconfirmed connections.
> +	 */
> +	ct = nf_ct_get(skb, &ctinfo);
> +	if (ct && (nf_ct_is_confirmed(ct) ? !cached : info->commit)
> +	    && ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
> +		WARN_ONCE(1, "helper rejected packet");
> +		return -EINVAL;
>  	}
>  
>  	return 0;
> -- 
> 2.1.4
> 
> --
> To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html