netdev - Re: [PATCH] gre: fix ToS/DiffServ inherit bug

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]

Date:	Tue, 14 Jul 2009 09:34:33 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	aj@...n.ch
Cc:	voyo@...ip.pl, netdev@...r.kernel.org, kuznet@....inr.ac.ru,
	kaber@...sh.net
Subject: Re: [PATCH] gre: fix ToS/DiffServ inherit bug

From: Andreas Jaggi <aj@...n.ch>
Date: Tue, 14 Jul 2009 17:36:48 +0200

> Fixes two bugs:
> - ToS/DiffServ inheritance was unintentionally activated when using impair fixed ToS values
> - ECN bit was lost during ToS/DiffServ inheritance
> 
> Signed-off-by: Andreas Jaggi <aj@...n.ch>
 ...
>  	tos = tiph->tos;
> -	if (tos&1) {
> +	if (tos == 1) {
> +		tos = 0;
>  		if (skb->protocol == htons(ETH_P_IP))
>  			tos = old_iph->tos;
> -		tos &= ~1;
>  	}

Note that this only works out because one wouldn't specify ECN
bits in the TOS to use for the tunnel.

But it demonstrates the outright danger of trying to use
"undefined" flag bits in protocol header fields to pass
private control flags into the driver from user interfaces.
--
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