netdev - Re: [PATCH 2/2] ehea: Receive SKB Aggregation

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Date:	Thu, 31 May 2007 09:37:03 -0700
From:	Stephen Hemminger <shemminger@...ux-foundation.org>
To:	Thomas Klein <osstklei@...ibm.com>
Cc:	Jeff Garzik <jeff@...zik.org>,
	Christoph Raisch <raisch@...ibm.com>,
	"Jan-Bernd Themann" <ossthema@...ibm.com>,
	"Jan-Bernd Themann" <themann@...ibm.com>,
	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"linux-ppc" <linuxppc-dev@...abs.org>,
	Marcus Eder <meder@...ibm.com>,
	netdev <netdev@...r.kernel.org>,
	Thomas Klein <tklein@...ibm.com>,
	Stefan Roscher <ossrosch@...ux.vnet.ibm.com>
Subject: Re: [PATCH 2/2] ehea: Receive SKB Aggregation


> 
>  
> +static int try_get_ip_tcp_hdr(struct ehea_cqe *cqe, struct sk_buff *skb,
> +			      struct iphdr **iph, struct tcphdr **tcph)
> +{
> +	int ip_len;
> +
> +	/* non tcp/udp packets */
> +	if (!cqe->header_length)
> +		return -1;
> +
> +	/* non tcp packet */
> +	*iph = (struct iphdr *)(skb->data);

Why the indirection, copying of headers..

> +	if ((*iph)->protocol != IPPROTO_TCP)
> +		return -1;
> +
> +	ip_len = (u8)((*iph)->ihl);
> +	ip_len <<= 2;
> +	*tcph = (struct tcphdr *)(((u64)*iph) + ip_len);
> +
> +	return 0;
> +}
> +
> 

This code seems to be duplicating a lot  (but not all) of the TCP/IP
input path validation checks. This is a security problem if nothing else...

Also, how do you prevent DoS attacks from hostile TCP senders that send
huge number of back to back frames?

-- 
Stephen Hemminger <shemminger@...ux-foundation.org>
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