From patchwork Fri Apr 24 22:51:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Scott Dial X-Patchwork-Id: 220582 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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, 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 2328BC54FCB for ; Fri, 24 Apr 2020 22:51:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB16820767 for ; Fri, 24 Apr 2020 22:51:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=scottdial.com header.i=@scottdial.com header.b="fEUKyTUh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726107AbgDXWvL (ORCPT ); Fri, 24 Apr 2020 18:51:11 -0400 Received: from bert.scottdial.com ([104.237.142.221]:50476 "EHLO bert.scottdial.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725946AbgDXWvK (ORCPT ); Fri, 24 Apr 2020 18:51:10 -0400 Received: from mail.scottdial.com (mail.scottdial.com [10.8.0.6]) by bert.scottdial.com (Postfix) with ESMTP id A254D57189B for ; Fri, 24 Apr 2020 18:51:09 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.scottdial.com (Postfix) with ESMTP id 494E21111605 for ; Fri, 24 Apr 2020 18:51:09 -0400 (EDT) Received: from mail.scottdial.com ([127.0.0.1]) by localhost (mail.scottdial.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id o8qjQmzvU-Sg for ; Fri, 24 Apr 2020 18:51:08 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.scottdial.com (Postfix) with ESMTP id 486161111606 for ; Fri, 24 Apr 2020 18:51:08 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.scottdial.com 486161111606 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=scottdial.com; s=24B7B964-7506-11E8-A7D6-CF6FBF8C6FCF; t=1587768668; bh=cOkjeDgSn0IZpvq4yuZyE8b2PyETBgwgfX9nMn6TvSo=; h=From:To:Date:Message-Id:MIME-Version; b=fEUKyTUhPqhWqYnExofTshpk4TV9mFIkbEb13qk0VbvMrubaGa9kH7oMQEBYenF6o e6SIdKqGVfOlIu78GC9vWbAS8MhL67dEYdzRZATMl7zOkIXt8qHJmfh5ZV+pNUvdHI yfOcibbvxIB7h4Rl18Kw1xEZGL8uuJ5Ls1toOrJPvVbas9O+DLlZtI3j+MGQq4yKj1 SEIM1jE8041VbdR45dV0O8NWuglSGnSkYxusrqWMYyxGgRyYPs5jdM79ASyosM/Mon 1dFRM3/ptRQtsQbTx8CmdaRk5lGUZrKyYU/FOR/FkZ/UT/JsJ5B/rHTEvd4uTTIj/J fIMCzk6+sjArA== X-Virus-Scanned: amavisd-new at scottdial.com Received: from mail.scottdial.com ([127.0.0.1]) by localhost (mail.scottdial.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id s7GFFyUN2ZXs for ; Fri, 24 Apr 2020 18:51:08 -0400 (EDT) Received: from bruno.home.scottdial.com.home.scottdial.com (bruno.scottdial.com [172.17.1.8]) by mail.scottdial.com (Postfix) with ESMTP id 242C11111605 for ; Fri, 24 Apr 2020 18:51:08 -0400 (EDT) From: Scott Dial To: netdev@vger.kernel.org Subject: [PATCH net] net: macsec: preserve ingress frame ordering Date: Fri, 24 Apr 2020 18:51:08 -0400 Message-Id: <20200424225108.956252-1-scott@scottdial.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 --- 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 a183250ff66a..bce8b8fde400 100644 --- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -1305,7 +1305,8 @@ 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;