From: Ben Hutchings <bhutchings@solarflare•com>
To: Adam Langley <agl@imperialviolet•org>
Cc: davem@davemloft•net, netdev@vger•kernel.org
Subject: Re: [PATCH] Fix corrupt TCP packets when options space overflows with MD5SIG enabled
Date: Fri, 30 May 2008 20:02:20 +0100 [thread overview]
Message-ID: <20080530190218.GD1743@solarflare.com> (raw)
In-Reply-To: <396556a20805301140x586093e5o92d44e38f7c2869a@mail.gmail.com>
Adam Langley wrote:
> When MD5 signatures are turned on we can end up with syntactically invalid
> packets with a header length < 20 bytes. This is because tcp_header_size
> overflows with 12 bytes of timestamp, 20 bytes of signature and > 8 bytes of
> SACK option.
[...]
> @@ -519,12 +529,23 @@ static int tcp_transmit_skb(struct sock *sk,
> struct sk_buff *skb, int clone_it,
> tcp_header_size += TCPOLEN_WSCALE_ALIGNED;
> sysctl_flags |= SYSCTL_FLAG_WSCALE;
> }
> - if (sysctl_tcp_sack) {
> + if (sysctl_tcp_sack
> +#ifdef CONFIG_TCP_MD5SIG
> + /* We don't include SACK options if we are going to
> + * include an MD5 signature because they can't fit
> + * in the options space */
> + && !md5
> +#endif
Putting an #ifdef..#endif in the middle of an if () is a bit nasty. Why not
define md5 and set it to 0 if CONFIG_TCP_MD5SIG is not set? The compiler
should be able to optimise it away if it's always initialised to 0.
Ben.
--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
next prev parent reply other threads:[~2008-05-30 19:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-30 18:40 [PATCH] Fix corrupt TCP packets when options space overflows with MD5SIG enabled Adam Langley
2008-05-30 19:02 ` Ben Hutchings [this message]
2008-05-30 19:11 ` Adam Langley
2008-05-30 19:17 ` Adam Langley
2008-05-30 20:32 ` Stephen Hemminger
2008-05-31 22:01 ` Adam Langley
2008-05-31 21:57 ` Adam Langley
2008-06-01 23:40 ` James Morris
2008-06-02 6:56 ` David Miller
2008-06-03 16:31 ` Adam Langley
2008-06-03 16:44 ` David Miller
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