From patchwork Mon May 18 17:35:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 225754 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,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 27109C433E0 for ; Mon, 18 May 2020 18:03:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0279C20885 for ; Mon, 18 May 2020 18:03:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589824986; bh=tehWF7fpkndSMrdZ/mvh2Ukdq+BeAudbWlSRcul9Fdg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=L4PUr9jIdkO8RDQ2E2V4DpLECFqiTwgF4RGr2x8kSu9JRLC+91QF44OSzjAGBNBoo vFEN6+GMaMh/3bOopEmaF8J2KinvhmGsHiF79UTXNzMCP91qJzRguNnkAqAm2oEckO Pv9f8ZvuqdXtqFuyCZcPNTZDMEctC/ZGKjFMj6/0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732604AbgERSDE (ORCPT ); Mon, 18 May 2020 14:03:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:48130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732600AbgERSDE (ORCPT ); Mon, 18 May 2020 14:03:04 -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 DAFC6207D3; Mon, 18 May 2020 18:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589824983; bh=tehWF7fpkndSMrdZ/mvh2Ukdq+BeAudbWlSRcul9Fdg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SEjHOZj80DggZ1usXq9144RvPp11wEHDbwRH8OvkM1ZtRDWJAGB2s0cYqoawQLfnr mBoATwBujsiEOvUKoauqQbqkmudcDQNgfqT2np27gbstR5z+QefMtqISy29gYxnjmr jumjAKAMBT0W6OgtNordkxcELlYsvW5i7uW8zui0= 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 5.6 044/194] net: ipv4: really enforce backoff for redirects Date: Mon, 18 May 2020 19:35:34 +0200 Message-Id: <20200518173535.436284069@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200518173531.455604187@linuxfoundation.org> References: <20200518173531.455604187@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 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 @@ -915,7 +915,7 @@ 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)))) {