From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by passt.top (Postfix) with ESMTP id C309C5A026A for <passt-dev@passt.top>; Tue, 6 Dec 2022 07:45:52 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670309151; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1JKyA7z4rYC+ihya6P7LXa+k4g6AWN4H0B7WmzXPzWA=; b=MVEBWgkti1ND7XBtAZgdiNKBlcOnoA5Ij8VTxMJu/LA+rW6oCv9Kqj+9aa/UUkMYKQtU+V 91VxD4dH9pYq0BntZ0C6odgDa7hlu0CMK4EB9X79DqFog5CcxajMFl2wX1xm5Tb1NT+Qy/ 6PKrRGpVUzrjlrmHe9MMd5XdETLj9f8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-351-NDThkXM3OrSVdqGwomkjcg-1; Tue, 06 Dec 2022 01:45:42 -0500 X-MC-Unique: NDThkXM3OrSVdqGwomkjcg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E18D4802804; Tue, 6 Dec 2022 06:45:41 +0000 (UTC) Received: from maya.cloud.tilaa.com (ovpn-208-4.brq.redhat.com [10.40.208.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8434A1121325; Tue, 6 Dec 2022 06:45:41 +0000 (UTC) Date: Tue, 6 Dec 2022 07:45:38 +0100 From: Stefano Brivio <sbrivio@redhat.com> To: David Gibson <david@gibson.dropbear.id.au> Subject: Re: [PATCH v4 00/16] Simplify and correct handling of "spliced" UDP forwarding Message-ID: <20221206074538.7124ea93@elisabeth> In-Reply-To: <20221130041316.2539575-1-david@gibson.dropbear.id.au> References: <20221130041316.2539575-1-david@gibson.dropbear.id.au> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: S2HLC6ZXLZDWSGCZLF3IOJ6VV6ESM6UO X-Message-ID-Hash: S2HLC6ZXLZDWSGCZLF3IOJ6VV6ESM6UO X-MailFrom: sbrivio@redhat.com 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: 3.3.3 Precedence: list List-Id: Development discussion and patches for passt <passt-dev.passt.top> Archived-At: <https://archives.passt.top/passt-dev/20221206074538.7124ea93@elisabeth/> Archived-At: <https://passt.top/hyperkitty/list/passt-dev@passt.top/message/S2HLC6ZXLZDWSGCZLF3IOJ6VV6ESM6UO/> List-Archive: <https://archives.passt.top/passt-dev/> List-Archive: <https://passt.top/hyperkitty/list/passt-dev@passt.top/> List-Help: <mailto:passt-dev-request@passt.top?subject=help> List-Owner: <mailto:passt-dev-owner@passt.top> List-Post: <mailto:passt-dev@passt.top> List-Subscribe: <mailto:passt-dev-join@passt.top> List-Unsubscribe: <mailto:passt-dev-leave@passt.top> On Wed, 30 Nov 2022 15:13:00 +1100 David Gibson <david@gibson.dropbear.id.au> wrote: > The UDP "splicing" (forwarding packets from one L4 socket to another, > rather than via the tuntap device) code assumes that any given UDP > port in the init namespace will only communicate with a single port on > the ns side at a time, and vice versa. This will often be the case, > but since UDP is a connectionless protocol, it need not be. In fact > it is not the case in our existing UDP bandwidth checks, although the > specific configuration there means it's not harmful in that case. > > The failure mode in this case can be quite bad: we don't just fall > back to an unoptimized oath, or drop packets, we will misdirect > packets to the wrong destination. > > This series make some substantial simplifications to how we handle the > splice forwarding, then corrects it to handle the case of multiple > source ports sending to a single destination. Applied (and pushed :)). -- Stefano