From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8EF1C433E1 for ; Mon, 18 May 2020 18:22:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE36F20643 for ; Mon, 18 May 2020 18:22:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589826131; bh=fE4l/YiFzGqBGD1qlBVhUzgpbiM6XFdUJWqpCgy6Krk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JPNQgoC4iPzxqhFARkBpvalLvKulBY5ZBdnaoip+ZBsDFZeufvnYicOOxDml2xCVo 5bd8P/gAYw2XL9u4VhT9xym1iuIDdIKDTwG4HXdnpbE7PWTWxe/HcMqJ3Mma/+Yzcq euYcZEfUUpvOawMVRfhT1UmM8AspnEtEIOlMtrRY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728939AbgERSWH (ORCPT ); Mon, 18 May 2020 14:22:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:53252 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730721AbgERRux (ORCPT ); Mon, 18 May 2020 13:50:53 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 26FE120826; Mon, 18 May 2020 17:50:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589824252; bh=fE4l/YiFzGqBGD1qlBVhUzgpbiM6XFdUJWqpCgy6Krk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dd7S/zyem6cQlEgG3GICtblWa3wrLNL3l7rMJ2VZRt0YP8GPS5sIzFHapJcTkd92X 8Uo4KL/k2j8u1FcbMYE4LfG39bQ3W8+JSZGQWaFYwzdDCSipsAu99nQQ35qRYAxriE MaFVPL2/Una8lhul1G2LZmrY6IdgdPWfnMlyqG14= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paolo Abeni , Jakub Kicinski , Colin Walters Subject: [PATCH 4.19 18/80] net: ipv4: really enforce backoff for redirects Date: Mon, 18 May 2020 19:36:36 +0200 Message-Id: <20200518173454.103849772@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200518173450.097837707@linuxfoundation.org> References: <20200518173450.097837707@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paolo Abeni [ Upstream commit 57644431a6c2faac5d754ebd35780cf43a531b1a ] In commit b406472b5ad7 ("net: ipv4: avoid mixed n_redirects and rate_tokens usage") I missed the fact that a 0 'rate_tokens' will bypass the backoff algorithm. Since rate_tokens is cleared after a redirect silence, and never incremented on redirects, if the host keeps receiving packets requiring redirect it will reply ignoring the backoff. Additionally, the 'rate_last' field will be updated with the cadence of the ingress packet requiring redirect. If that rate is high enough, that will prevent the host from generating any other kind of ICMP messages The check for a zero 'rate_tokens' value was likely a shortcut to avoid the more complex backoff algorithm after a redirect silence period. Address the issue checking for 'n_redirects' instead, which is incremented on successful redirect, and does not interfere with other ICMP replies. Fixes: b406472b5ad7 ("net: ipv4: avoid mixed n_redirects and rate_tokens usage") Reported-and-tested-by: Colin Walters Signed-off-by: Paolo Abeni Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv4/route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -906,7 +906,7 @@ void ip_rt_send_redirect(struct sk_buff /* Check for load limit; set rate_last to the latest sent * redirect. */ - if (peer->rate_tokens == 0 || + if (peer->n_redirects == 0 || time_after(jiffies, (peer->rate_last + (ip_rt_redirect_load << peer->n_redirects)))) {