netdev - Re: [PATCH] [IPv6] Do not use loopback as source address on other interfaces

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Date:	Wed, 18 Jun 2008 18:11:42 +0200
From:	Karsten Keil <kkeil@...e.de>
To:	YOSHIFUJI Hideaki / 吉藤英明 
	<yoshfuji@...ux-ipv6.org>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	Mironov_Sergey@....com, akpm@...ux-foundation.org,
	torvalds@...ux-foundation.org
Subject: Re: [PATCH] [IPv6] Do not use loopback as source address on other interfaces

On Wed, Jun 18, 2008 at 11:36:07PM +0900, YOSHIFUJI Hideaki / 吉藤英明 wrote:
> In article <20080618140558.GB25004@...gi.kke.suse.de> (at Wed, 18 Jun 2008 16:05:58 +0200), Karsten Keil <kkeil@...e.de> says:
> 
> > On Wed, Jun 18, 2008 at 10:36:00PM +0900, YOSHIFUJI Hideaki / 吉藤英明 wrote:
> > > In article <20080618132312.GA25004@...gi.kke.suse.de> (at Wed, 18 Jun 2008 15:23:12 +0200), Karsten Keil <kkeil@...e.de> says:
> > > 
> > > > RFC 4291 forbit the use of the loopback address as source outside a node
> > > > (paragraph 2.5.3).
> > > > 
> > > > The latest TAHI test release 4.0.1 does have a check for this (ICMPv6 test
> > > > v6LC.5.1.2 Part F), so it fails currently on Linux.
> > > > 
> > > > Signed-off-by: Sergey Mironov <Mironov_Sergey@....com>
> > > > Signed-off-by: Karsten Keil <kkeil@...e.de>
> > > 
> > > I disagree this approach - too ad-hoc fix just to pass the tests.
> > > 
> > 
> > So you would prefer a more general test in some common place (like
> > __ip6_local_out() ) to avoid any packets with ::1 on other devices as
> > loopback ?
> 
> No, we should not even accept packets for ::1 from outside of the box.
> Something like this.
> 

Yes I was thinking about nearly the same patch now :-)

> ---
> ipv6: Drop packets for loopback address from outside of the box.
> 
> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
> 
> -- 
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> index e0a612b..f422f72 100644
> --- a/include/net/ipv6.h
> +++ b/include/net/ipv6.h
> @@ -367,6 +367,12 @@ static inline int ipv6_addr_any(const struct in6_addr *a)
>  		 a->s6_addr32[2] | a->s6_addr32[3] ) == 0); 
>  }
>  
> +static inline int ipv6_addr_loopback(const struct in6_addr *a)
> +{
> +	return ((a->s6_addr32[0] | a->s6_addr32[1] |
> +		 a->s6_addr32[2] | (a->s6_addr32[3] ^ htonl(1))) == 0);
> +}
> +
>  static inline int ipv6_addr_v4mapped(const struct in6_addr *a)
>  {
>  	return ((a->s6_addr32[0] | a->s6_addr32[1] |
> diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
> index 4e5c861..17eb48b 100644
> --- a/net/ipv6/ip6_input.c
> +++ b/net/ipv6/ip6_input.c
> @@ -102,6 +102,15 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt
>  	if (hdr->version != 6)
>  		goto err;
>  
> +	/*
> +	 * RFC4291 2.5.3
> +	 * A packet received on an interface with a destination address
> +	 * of loopback must be dropped.
> +	 */
> +	if (!(dev->flags & IFF_LOOPBACK) &&
> +	    ipv6_addr_loopback(&hdr->daddr))
> +		goto err;
> +
>  	skb->transport_header = skb->network_header + sizeof(*hdr);
>  	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
>  
> 
> 
> --yoshfuji

-- 
Karsten Keil
SuSE Labs
ISDN and VOIP development
SUSE LINUX Products GmbH, Maxfeldstr.5 90409 Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg)
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