From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202606 header.b=C2houG42; dkim-atps=neutral Received: from mail.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id 6F9045A0262 for ; Thu, 16 Jul 2026 06:53:42 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202606; t=1784177618; bh=sEhutQ+n6RNNPHp5W0IaPaH1dhs0Prrras4akprsTG4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C2houG42bI/vIMumLmryYDJ0sPKc8vVURht7csYu2uOdAooB0w8B0eDYbazuuo0JS KL8WdTvmhMU5x1lXa6cESBh9BW1nSpD3xgynFypz372dQO/JxOHg+rxEC7RvWl7nKb QF7HxCuRp4GmJZmD60luuT4TDokkkJBflWiIn61qZaQmFlm4+CLm+g2l9eDe+q/LYv YB8JceFzN9SKdy43lEQ+NOZMpymgy/fK2+D7mvm4oUcCyrRTfcFC/Lf0d+uyikTueV zi/uZUAh/RjbSawahzyfzi2RgTO3QEK6IEDaX37hzrc3KDxoJBhfN3m+j9Ny9XElE/ xMxJJGcNGzoRQ== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4h11025JQrz4w2B; Thu, 16 Jul 2026 14:53:38 +1000 (AEST) Date: Thu, 16 Jul 2026 13:31:13 +1000 From: David Gibson To: Stefano Brivio Subject: Re: [PATCH v2 1/5] fwd: Clarify semantics of --host-lo-to-ns-lo Message-ID: References: <20260713053856.1329271-1-david@gibson.dropbear.id.au> <20260713053856.1329271-2-david@gibson.dropbear.id.au> <20260715091129.282bbbf9@elisabeth> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="mvxCYp1sVDfaNv3W" Content-Disposition: inline In-Reply-To: <20260715091129.282bbbf9@elisabeth> Message-ID-Hash: XIDTFITJWYVDVPPT4WRT4SGSB2KRMYAT X-Message-ID-Hash: XIDTFITJWYVDVPPT4WRT4SGSB2KRMYAT X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --mvxCYp1sVDfaNv3W Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 15, 2026 at 09:11:30AM +0200, Stefano Brivio wrote: > On Mon, 13 Jul 2026 15:38:52 +1000 > David Gibson wrote: >=20 > > The semantics of --host-lo-to-ns-lo as described in the man page don't > > quite make sense: It says without the option forwarded packets will app= ear > > to come _from_ the guest's public address, which is not usually true. > > Instead the packets will arrive *to* the guest's public address. The e= xact > > semantics are also a bit confusing in general. > >=20 > > Rewrite both the man page and code to clarify this. The new rule is th= at > > it redirects connections addressed to a host loopback address to the sa= me > > loopback address in the guest. This is notionally different from what = we > > had in two ways: > > * We can now deliver to nonstandard loopback addresses within the gue= st, > > not just the default one. This is technically a behavioural change, > > but I think will be less surprising behaviour. > > * The decision is now made on the original _destination_ address, rat= her > > than source address. That's different theoretically, but not in > > practice, since loopback packets must have loopback addresses for b= oth > > source and destination. > >=20 > > We make it explicitly incompatible with --no-splice - previously it > > was allowed, but would have no effect in that case. > >=20 > > As well as being more precise right now, these semantics will intersect > > better with other upcoming changes to the forwarding logic. > >=20 > > Signed-off-by: David Gibson >=20 > I added: >=20 > Link: https://bugs.passt.top/show_bug.cgi?id=3D212 Thanks. Having fixed the bug before it was reported, I chose not to strain my powers of precognition by also predicting the bug number :). --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --mvxCYp1sVDfaNv3W Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmpYUHIACgkQzQJF27ox 2Gc42Q/7Bhc6V+DlVyRB3b8MMXOG92xFVKw8yQwbr7ixHkazXA9zBobWGuhOkzs+ +3wYjc0vF4Fizg57peF3zCWLCgwKhnl9viG/FmF4VuGRbsWGmmuOmxQGolv8SXYh CW2T+8zX76rimZgpk3Y1pvK9XRLBGm4Ge0BOdzvkergNR6zWbpAJlMuVxgaKSBvH 7ZBcZ/FnNPj6p9pO1FKWbu2C7FFdlbxxwmwYviBvIXyFtfv3tslNv9WMREnc3n+N pusogsVavVzkgegNX5ollScvEVtUXbw7TgGB+cSb4Y4FH5/ylTREw4bgQusiuaNB sw5SqLZ48g+Zr0mzwNsjIqlGh1vFuJnjwzj6WCNkdePmqHlenIxfwlXp0gVtBsCj uoLr2fl5NuXSmZrvEiyXXt+bgbd9I3IXzverk7FckSfqWK4DL4/bsbyNamNQH3b4 w7sVqP1ZAYIOjjO/z8mHGxylrXRcDKUE0NlEOxuV/w5X+ppbwyf6FJ+q1Ks5fznr OaTeXoGLDL0TXzPmphd1Xt9SiOzlgWIlf1PXLPjr6hoN+6BAZx0dvrsRDb/Z7VrD +KVGcWxq2LZw8hbytl4zoWy8R2SJq0XczFq0PR6qrdy5vjgdvOyQ65w3u1vkzFC/ kurcwUAi9IQoJVRS7kGSDfjpGErgnvCjMiZfrFJ/xFA3cpKsemU= =xCbo -----END PGP SIGNATURE----- --mvxCYp1sVDfaNv3W--