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Date:   Wed, 27 Apr 2022 22:19:39 +0200
From:   Willy Tarreau <w@1wt.eu>
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     netdev@vger.kernel.org, David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Moshe Kol <moshe.kol@mail.huji.ac.il>,
        Yossi Gilad <yossi.gilad@mail.huji.ac.il>,
        Amit Klein <aksecurity@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net 1/7] secure_seq: return the full 64-bit of the siphash
Message-ID: <20220427201938.GC4326@1wt.eu>
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Hi Jason,

On Wed, Apr 27, 2022 at 07:18:48PM +0200, Jason A. Donenfeld wrote:
> Hi Willy,
> 
> On Wed, Apr 27, 2022 at 08:52:27AM +0200, Willy Tarreau wrote:
> > diff --git a/include/net/secure_seq.h b/include/net/secure_seq.h
> > index d7d2495f83c2..5cea9ed9c773 100644
> > --- a/include/net/secure_seq.h
> > +++ b/include/net/secure_seq.h
> > @@ -4,7 +4,7 @@
> >  
> >  #include <linux/types.h>
> >  
> > -u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
> > +u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
> >  u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
> >  			       __be16 dport);
> >  u32 secure_tcp_seq(__be32 saddr, __be32 daddr,
> > diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c
> > index 9b8443774449..2cdd43a63f64 100644
> > --- a/net/core/secure_seq.c
> > +++ b/net/core/secure_seq.c
> > @@ -142,7 +142,7 @@ u32 secure_tcp_seq(__be32 saddr, __be32 daddr,
> >  }
> >  EXPORT_SYMBOL_GPL(secure_tcp_seq);
> >  
> > -u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
> > +u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
> >  {
> >  	net_secret_init();
> >  	return siphash_3u32((__force u32)saddr, (__force u32)daddr,
> 
> Should you be doing the same with secure_ipv6_port_ephemeral() too? Why
> the asymmetry?

I remember not finding it in the similar code path, but maybe I missed
something. It's used by inet6_sk_port_offset() which also returns a u32,
itself used by inet6_hash_connect() and passed to __inet_hash_connect().

Hmmm the loop is now closed, I don't know how I missed it. So yes I
agree that it would definitely be needed. I'll update the patch, many
thanks!

Willy