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=-6.9 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 67DACC2D0F9 for ; Wed, 13 May 2020 09:52:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4810923126 for ; Wed, 13 May 2020 09:52:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589363570; bh=57dvFvSjdaHFFUCUywJoU6nfomw//ZNIqcTjWzfo1e4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OSN9zoNUADzaicw6umUG81pV2BR03wHZxYDWbxPw1TsO5kdFzBbTrwtrhkLSgaKxl QQw4rdBim8X81eOmjpKsD09SUkEYQX6qgm00/IKtACPCUw8sOkm0/46lgomJaoKceT 4FhcxJs746Emf5FDeJBMXtNtMeAfNnKdw2P5lCpE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387834AbgEMJwp (ORCPT ); Wed, 13 May 2020 05:52:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:54138 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387815AbgEMJwj (ORCPT ); Wed, 13 May 2020 05:52:39 -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 AE60A20769; Wed, 13 May 2020 09:52:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589363558; bh=57dvFvSjdaHFFUCUywJoU6nfomw//ZNIqcTjWzfo1e4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jt+0NgGOvIrzSsck452HbjLou5dIbmclTFL3903q4Qr3PiR4/k+bY+pLroKcPcCZx bORlrPU1OwX+C17s2IiI0/ELEr/CdY3sYUgbcSntfs9W0sCuzmXup2iK/JxxTxDuIr VWx/gclegRFF5juNis7g1pBRE4ChgU9D99s8cA5M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Scott Dial , "David S. Miller" Subject: [PATCH 5.6 025/118] net: macsec: preserve ingress frame ordering Date: Wed, 13 May 2020 11:44:04 +0200 Message-Id: <20200513094419.863673154@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200513094417.618129545@linuxfoundation.org> References: <20200513094417.618129545@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Scott Dial [ Upstream commit ab046a5d4be4c90a3952a0eae75617b49c0cb01b ] MACsec decryption always occurs in a softirq context. Since the FPU may not be usable in the softirq context, the call to decrypt may be scheduled on the cryptd work queue. The cryptd work queue does not provide ordering guarantees. Therefore, preserving order requires masking out ASYNC implementations of gcm(aes). For instance, an Intel CPU with AES-NI makes available the generic-gcm-aesni driver from the aesni_intel module to implement gcm(aes). However, this implementation requires the FPU, so it is not always available to use from a softirq context, and will fallback to the cryptd work queue, which does not preserve frame ordering. With this change, such a system would select gcm_base(ctr(aes-aesni),ghash-generic). While the aes-aesni implementation prefers to use the FPU, it will fallback to the aes-asm implementation if unavailable. By using a synchronous version of gcm(aes), the decryption will complete before returning from crypto_aead_decrypt(). Therefore, the macsec_decrypt_done() callback will be called before returning from macsec_decrypt(). Thus, the order of calls to macsec_post_decrypt() for the frames is preserved. While it's presumable that the pure AES-NI version of gcm(aes) is more performant, the hybrid solution is capable of gigabit speeds on modest hardware. Regardless, preserving the order of frames is paramount for many network protocols (e.g., triggering TCP retries). Within the MACsec driver itself, the replay protection is tripped by the out-of-order frames, and can cause frames to be dropped. This bug has been present in this code since it was added in v4.6, however it may not have been noticed since not all CPUs have FPU offload available. Additionally, the bug manifests as occasional out-of-order packets that are easily misattributed to other network phenomena. When this code was added in v4.6, the crypto/gcm.c code did not restrict selection of the ghash function based on the ASYNC flag. For instance, x86 CPUs with PCLMULQDQ would select the ghash-clmulni driver instead of ghash-generic, which submits to the cryptd work queue if the FPU is busy. However, this bug was was corrected in v4.8 by commit b30bdfa86431afbafe15284a3ad5ac19b49b88e3, and was backported all the way back to the v3.14 stable branch, so this patch should be applicable back to the v4.6 stable branch. Signed-off-by: Scott Dial Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/macsec.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -1226,7 +1226,8 @@ static struct crypto_aead *macsec_alloc_ struct crypto_aead *tfm; int ret; - tfm = crypto_alloc_aead("gcm(aes)", 0, 0); + /* Pick a sync gcm(aes) cipher to ensure order is preserved. */ + tfm = crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC); if (IS_ERR(tfm)) return tfm;