netdev - Re: [PATCH] netfilter/IPv6: initialize TOS field in REJECT target module

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Message-ID: <1303458454.9791.13.camel@nausicaa>
Date:	Fri, 22 Apr 2011 16:47:34 +0900
From:	Fernando Luis Vazquez Cao <fernando@....ntt.co.jp>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	yoshfuji@...ux-ipv6.org, jengelh@...ozas.de, davem@...emloft.net
Subject: Re: [PATCH] netfilter/IPv6:  initialize TOS field in REJECT target
 module

On Fri, 2011-04-22 at 09:34 +0200, Eric Dumazet wrote:
> Le vendredi 22 avril 2011 à 16:19 +0900, Fernando Luis Vazquez Cao a
> écrit :
> > The IPv6 header is not zeroed out in alloc_skb so we must initialize it
> > properly unless we want to see IPv6 packets with random TOS fields
> > floating around. The current implementation resets the flow label
> > but this could be changed if deemed necessary.
> > 
> > We stumbled upon this issue when trying to apply a mangle rule to
> > the RST packet generated by the REJECT target module.
> > 
> > Signed-off-by: Fernando Luis Vazquez Cao <fernando@....ntt.co.jp>
> > ---
> > 
> > diff -urNp linux-2.6.38.4-orig/net/ipv6/netfilter/ip6t_REJECT.c linux-2.6.38.4/net/ipv6/netfilter/ip6t_REJECT.c
> > --- linux-2.6.38.4-orig/net/ipv6/netfilter/ip6t_REJECT.c	2011-03-15 10:20:32.000000000 +0900
> > +++ linux-2.6.38.4/net/ipv6/netfilter/ip6t_REJECT.c	2011-04-22 15:00:30.695373543 +0900
> > @@ -45,6 +45,8 @@ static void send_reset(struct net *net,
> >  	int tcphoff, needs_ack;
> >  	const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
> >  	struct ipv6hdr *ip6h;
> > +#define DEFAULT_TOS_VALUE	0x0U
> > +	const __u8 tclass = DEFAULT_TOS_VALUE;
> >  	struct dst_entry *dst = NULL;
> >  	u8 proto;
> >  	struct flowi fl;
> > @@ -123,7 +125,7 @@ static void send_reset(struct net *net,
> >  	skb_put(nskb, sizeof(struct ipv6hdr));
> >  	skb_reset_network_header(nskb);
> >  	ip6h = ipv6_hdr(nskb);
> > -	ip6h->version = 6;
> > +	*(__be32 *)ip6h =  htonl(0x60000000 | (tclass << 20));
> 
> It seems fine but I am wondering where is payload_len set ?

Hi Eric,

Thank you for the review, I really appreciate it.

payload_len is set in __ip6_local_out() which is called from
ip6_local_out.

Could I get your acked-by for the two patches I sent?

Thanks,
Fernando

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