From patchwork Tue Mar 6 19:13:18 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej S. Szmigiero" X-Patchwork-Id: 10262427 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7275E6055D for ; Tue, 6 Mar 2018 19:13:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 61B1C29138 for ; Tue, 6 Mar 2018 19:13:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 55DC72913C; Tue, 6 Mar 2018 19:13:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 75ABB29138 for ; Tue, 6 Mar 2018 19:13:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753043AbeCFTN2 (ORCPT ); Tue, 6 Mar 2018 14:13:28 -0500 Received: from vps-vb.mhejs.net ([37.28.154.113]:57048 "EHLO vps-vb.mhejs.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750836AbeCFTN1 (ORCPT ); Tue, 6 Mar 2018 14:13:27 -0500 Received: by vps-vb.mhejs.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.89) (envelope-from ) id 1etI1X-0001rh-Vb; Tue, 06 Mar 2018 20:13:20 +0100 From: "Maciej S. Szmigiero" Subject: [PATCH] X.509: unpack RSA signatureValue field from BIT STRING To: David Howells Cc: Herbert Xu , "David S. Miller" , Tom Lendacky , Gary Hook , keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <88da0c24-385c-64a9-6d56-36696d433bc7@maciej.szmigiero.name> Date: Tue, 6 Mar 2018 20:13:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 Content-Language: en-US Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The signatureValue field of a X.509 certificate is encoded as a BIT STRING. For RSA signatures this BIT STRING is of so-called primitive subtype, which contains a u8 prefix indicating a count of unused bits in the encoding. We have to strip this prefix from signature data, just as we already do for key data in x509_extract_key_data() function. This wasn't noticed earlier because this prefix byte is zero for RSA key sizes divisible by 8. Since BIT STRING is a big-endian encoding adding zero prefixes has no bearing on its value. The signature length, however was incorrect, which is a problem for RSA implementations that need it to be exactly correct (like AMD CCP). Signed-off-by: Maciej S. Szmigiero Fixes: c26fd69fa009 ("X.509: Add a crypto key parser for binary (DER) X.509 certificates") Cc: stable@vger.kernel.org --- This is a resend without changes of a patch that was previously submitted in one series with CCP driver changes since this particular patch should go through the security (rather than crypto) tree. crypto/asymmetric_keys/x509_cert_parser.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index ce2df8c9c583..88c26a4538ae 100644 --- a/crypto/asymmetric_keys/x509_cert_parser.c +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -249,6 +249,15 @@ int x509_note_signature(void *context, size_t hdrlen, return -EINVAL; } + if (!strcmp(ctx->cert->sig->pkey_algo, "rsa")) { + /* Discard the BIT STRING metadata */ + if (vlen < 1 || *(const u8 *)value != 0) + return -EBADMSG; + + value++; + vlen--; + } + ctx->cert->raw_sig = value; ctx->cert->raw_sig_size = vlen; return 0;