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 603A3C433DF for ; Mon, 18 May 2020 18:26:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 420B32065F for ; Mon, 18 May 2020 18:26:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589826386; bh=YNrWYBeTxYdb0O+DbcPxCij4hDjcu6RrXCU7kSPbevw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=KlQoEB2ztGVNtzMDE1DuPv2jk1tb6gR2IGBo6QlOJKanjh3x5yoHnK4xrSHC4F40i GO8rC9/kQl0ZcmHiLf4nbUDHqCVPMu+uPyga1rIL+kKTikjD2E2K7NTrB21hIB4Q9S mIhZr0XfxL2HwxGW0KgrlizvwzcnmxDagoAEP2lk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729444AbgERS0U (ORCPT ); Mon, 18 May 2020 14:26:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:44578 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729973AbgERRph (ORCPT ); Mon, 18 May 2020 13:45:37 -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 DE6E620671; Mon, 18 May 2020 17:45:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589823937; bh=YNrWYBeTxYdb0O+DbcPxCij4hDjcu6RrXCU7kSPbevw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a1Gx3ZTN8SWf5lSY2NQjFYWsL00GpXLCSVb+W5oD80LjIyLz+mr6hqKH2jlAS6Tpx zgRyaz8e7QgZaXgf0h3QCd57O0Tf6Ihi4/hOfghxh1px44phYQsSSe6hKq9JHLMXZ1 vAyLUmSw6SU0/EyhyIO9LdZ2NKoRJ3OUkJ5lN4IM= 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 4.9 71/90] net: ipv4: really enforce backoff for redirects Date: Mon, 18 May 2020 19:36:49 +0200 Message-Id: <20200518173505.712038047@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200518173450.930655662@linuxfoundation.org> References: <20200518173450.930655662@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 @@ -898,7 +898,7 @@ 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)))) {