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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 0CD27C433E0 for ; Thu, 14 May 2020 19:01:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB2302065F for ; Thu, 14 May 2020 19:01:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589482862; bh=sKKycsNvZwdMi/ig82103IsNNPEMODqd4qw0y2HS1+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=efoVPfs3Ej92qlVo4x3QEzeaZJHe+lfl5TmPd581rBjo1gMHVyP/R7ktMOqFYY4sc +NSAoXTQ4MM76VWS8CpPzWq/TpoXiV/FgWC3aonrr+aJSpqHXzQgtnbO8DFKiH1JWS hf0mZJaNA8lYHh3PvJp95FNAh5qwfFwOSCiT/rAc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729535AbgENTBC (ORCPT ); Thu, 14 May 2020 15:01:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:56182 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729403AbgENSze (ORCPT ); Thu, 14 May 2020 14:55:34 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 20F2F206DC; Thu, 14 May 2020 18:55:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589482533; bh=sKKycsNvZwdMi/ig82103IsNNPEMODqd4qw0y2HS1+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s9GcdBnYSNzElu/7Zdyf9AT7Shu4U6Cio8+64k7ZF/OUHgkd96zQhLO3mZfv6Y11G xZF+kzx2/3AS9NC76QFr84rqZ9CZ4JsYj90tHLJ6Ya1PKwbCkn7vgB9oC7HxBM34O1 t3HuZ2jItExr6j2T/jA+Pxq0ttxv4HNH5katmetM= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Scott Dial , "David S . Miller" , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 27/39] net: macsec: preserve ingress frame ordering Date: Thu, 14 May 2020 14:54:44 -0400 Message-Id: <20200514185456.21060-27-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200514185456.21060-1-sashal@kernel.org> References: <20200514185456.21060-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@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: Sasha Levin --- drivers/net/macsec.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c index 926e2eb528fd4..4a92160394c07 100644 --- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -1309,7 +1309,8 @@ static struct crypto_aead *macsec_alloc_tfm(char *key, int key_len, int icv_len) 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; -- 2.20.1