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,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,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 2D70AC282C3 for ; Thu, 24 Jan 2019 19:55:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE725217D4 for ; Thu, 24 Jan 2019 19:55:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548359750; bh=x6cOL7hnnyCG1xE+OCy8P2o8FxLB1pzHKrOcNCr5yCw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=d4Li5Y6CldF6aafqzKsauAkrMTZoB7vl+ooJyDfcwuBPM+Dpe5f4tk22DFnPpSfIB ReRXQUqUpLRlSUOA/bUEhi9YHOA3u796wB1GU1/LEjPkjBznaTIEOjC90CuuotU3qd n1zOvvUPPvuqluk7+IS+3hE/AD/nkxFVtOduUc4w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731944AbfAXTgf (ORCPT ); Thu, 24 Jan 2019 14:36:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:36594 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732510AbfAXTge (ORCPT ); Thu, 24 Jan 2019 14:36:34 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 E8998218FC; Thu, 24 Jan 2019 19:36:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548358593; bh=x6cOL7hnnyCG1xE+OCy8P2o8FxLB1pzHKrOcNCr5yCw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LtGGA4gWD+YRJ3M85fQC5jacuGDc6/kbN4jeiWivotnfOkXqNy4ljhiErq8q1nrb1 ivZ+x9ESTNuhXSGOuwdm8rTQuY+U2d/65zhTR2NjKf7Zysmp+1Q5f2TSmRoJCiIHw4 yR9fYxTqohJE+yHwrjaw0RiyD5qUcAnmPLTFIoR8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitaly Chikunov , kernel-hardening@lists.openwall.com, Herbert Xu , Sasha Levin Subject: [PATCH 4.19 026/106] crypto: ecc - regularize scalar for scalar multiplication Date: Thu, 24 Jan 2019 20:19:43 +0100 Message-Id: <20190124190208.023634852@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190124190206.342411005@linuxfoundation.org> References: <20190124190206.342411005@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 3da2c1dfdb802b184eea0653d1e589515b52d74b ] ecc_point_mult is supposed to be used with a regularized scalar, otherwise, it's possible to deduce the position of the top bit of the scalar with timing attack. This is important when the scalar is a private key. ecc_point_mult is already using a regular algorithm (i.e. having an operation flow independent of the input scalar) but regularization step is not implemented. Arrange scalar to always have fixed top bit by adding a multiple of the curve order (n). References: The constant time regularization step is based on micro-ecc by Kenneth MacKay and also referenced in the literature (Bernstein, D. J., & Lange, T. (2017). Montgomery curves and the Montgomery ladder. (Cryptology ePrint Archive; Vol. 2017/293). s.l.: IACR. Chapter 4.6.2.) Signed-off-by: Vitaly Chikunov Cc: kernel-hardening@lists.openwall.com Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin --- crypto/ecc.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/crypto/ecc.c b/crypto/ecc.c index 8facafd67802..adcce310f646 100644 --- a/crypto/ecc.c +++ b/crypto/ecc.c @@ -842,15 +842,23 @@ static void xycz_add_c(u64 *x1, u64 *y1, u64 *x2, u64 *y2, u64 *curve_prime, static void ecc_point_mult(struct ecc_point *result, const struct ecc_point *point, const u64 *scalar, - u64 *initial_z, u64 *curve_prime, + u64 *initial_z, const struct ecc_curve *curve, unsigned int ndigits) { /* R0 and R1 */ u64 rx[2][ECC_MAX_DIGITS]; u64 ry[2][ECC_MAX_DIGITS]; u64 z[ECC_MAX_DIGITS]; + u64 sk[2][ECC_MAX_DIGITS]; + u64 *curve_prime = curve->p; int i, nb; - int num_bits = vli_num_bits(scalar, ndigits); + int num_bits; + int carry; + + carry = vli_add(sk[0], scalar, curve->n, ndigits); + vli_add(sk[1], sk[0], curve->n, ndigits); + scalar = sk[!carry]; + num_bits = sizeof(u64) * ndigits * 8 + 1; vli_set(rx[1], point->x, ndigits); vli_set(ry[1], point->y, ndigits); @@ -1004,7 +1012,7 @@ int ecc_make_pub_key(unsigned int curve_id, unsigned int ndigits, goto out; } - ecc_point_mult(pk, &curve->g, priv, NULL, curve->p, ndigits); + ecc_point_mult(pk, &curve->g, priv, NULL, curve, ndigits); if (ecc_point_is_zero(pk)) { ret = -EAGAIN; goto err_free_point; @@ -1090,7 +1098,7 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, goto err_alloc_product; } - ecc_point_mult(product, pk, priv, rand_z, curve->p, ndigits); + ecc_point_mult(product, pk, priv, rand_z, curve, ndigits); ecc_swap_digits(product->x, secret, ndigits); -- 2.19.1