Subject: Re: [PATCH 5/9] tproxy: allow non-local binds of IPv6 sockets if IP_TRANSPARENT is enabled

From: YOSHIFUJI Hideaki <[email-masked]>
Date: Fri, 22 Oct 2010 06:24:12 +0900

Hello.

2010-10-20, Balazs Scheidler wrote:
> On Wed, 2010-10-20 at 21:45 +0900, YOSHIFUJI Hideaki wrote:
> > (2010/10/20 20:21), KOVACS Krisztian wrote:
> > > From: Balazs Scheidler<[email-masked]>
> > > 
> > > Signed-off-by: Balazs Scheidler<[email-masked]>
> > > Signed-off-by: KOVACS Krisztian<[email-masked]>
> > > ---
> > >   net/ipv6/af_inet6.c |    2 +-
> > >   1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
> > > index 6022098..9480572 100644
> > > --- a/net/ipv6/af_inet6.c
> > > +++ b/net/ipv6/af_inet6.c
> > > @@ -343,7 +343,7 @@ int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
> > >   			 */
> > >   			v4addr = LOOPBACK4_IPV6;
> > >   			if (!(addr_type&  IPV6_ADDR_MULTICAST))	{
> > > -				if (!ipv6_chk_addr(net,&addr->sin6_addr,
> > > +				if (!inet->transparent&&  !ipv6_chk_addr(net,&addr->sin6_addr,
> > >   						   dev, 0)) {
> > >   					err = -EADDRNOTAVAIL;
> > >   					goto out_unlock;
> > > 
> > > 
> > 
> > As I wrote before in other thread, this does not seem sufficient --
> > well, it is sufficient to allow non-local bind, but before we're
> > allowing this, we need add checks of source address in sending side.
> 
> Can you please elaborate or point us to the other thread? Is it some
> kind of address-type check that we miss?

Please see my comment at:
<http://kerneltrap.org/mailarchive/linux-netdev/2010/7/5/6280572>

This will result in allowing non-privileged users easily sending from
non-local / unauthorized address, which is not good, and which should
not be allowed from security aspects.

Regards,

--yoshfuji