linux-kernel - Re: batman-adv: design suggestions

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Date:	Mon, 9 Aug 2010 22:53:58 +0200
From:	Sven Eckelmann <sven.eckelmann@....de>
To:	Vasiliy Kulikov <segooon@...il.com>
Cc:	"Greg Kroah-Hartman" <gregkh@...e.de>,
	Andrew Lunn <andrew@...n.ch>,
	Marek Lindner <lindner_marek@...oo.de>,
	Simon Wunderlich <siwu@....tu-chemnitz.de>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	Linus Lüssing <linus.luessing@....de>
Subject: Re: batman-adv: design suggestions

Vasiliy Kulikov wrote:
> Hi folks,
> 
> I was reading batman-adv sources and noted:

Thanks a lot.


> 1) Some incoming packets may cause a storm of error logs, such as at
> routing.c:862
> 
> 
> 	if (icmp_packet->msg_type != ECHO_REQUEST) {
> 		pr_warning("Warning - can't forward icmp packet from %pM to "
> 			   "%pM: ttl exceeded\n", icmp_packet->orig,
> 			   icmp_packet->dst);
> 
>   Any flooding bad guy is able to fill our disks with logs.
>   This should be logged only at some slow rate (e.g. 5 logs/sec) or as
>   pr_debug().

Correct. So you would prefer pr_warn_ratelimited?


> 2) It seems to me that NF_HOOK() at hard-interface.c:458 is misused:
> 
>     ...
> 	ret = NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, dev, NULL,
> 		      batman_skb_recv_finish);
> 	if (ret != 1)
> 		goto err_out;
> 
> 	/* packet should hold at least type and version */
> 	if (unlikely(skb_headlen(skb) < 2))
> 		goto err_free;
> 
> 	/* expect a valid ethernet header here. */
> 	if (unlikely(skb->mac_len != sizeof(struct ethhdr)
> 
> 				|| !skb_mac_header(skb)))
> 
> 		goto err_free;
>     ...
> 
>     static int batman_skb_recv_finish(struct sk_buff *skb)
>     {
>         return NF_ACCEPT;
>     }
> 
>   As I understand, if there is any hook that returns NF_STOLEN, then skb
>   is leaked.

@Linus Luessing: Could you please check that.

thanks,
	Sven

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