From patchwork Wed Jul 11 20:36:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10520459 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 5D1C0600CA for ; Wed, 11 Jul 2018 20:37:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 400D1298CD for ; Wed, 11 Jul 2018 20:37:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3D650298D4; Wed, 11 Jul 2018 20:37:11 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable 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 D3EC8298CD for ; Wed, 11 Jul 2018 20:37:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390299AbeGKUmi (ORCPT ); Wed, 11 Jul 2018 16:42:38 -0400 Received: from mail-pl0-f68.google.com ([209.85.160.68]:37519 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390247AbeGKUmh (ORCPT ); Wed, 11 Jul 2018 16:42:37 -0400 Received: by mail-pl0-f68.google.com with SMTP id 31-v6so9649730plc.4 for ; Wed, 11 Jul 2018 13:36:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=RbnyDvKBIakheoYpsZY1SkQ8eDkgkUn0mQTm59BWgpI=; b=Til3Ds6p/89vXGjTq9OxJtqDvG9E2VEKugAxy3s8uaeXBcw0cbCBkq08jT1QHV+rka s1ZBvvrW31hifjXAiMTCmFZBh8ZnUaGoQALm5AwOPNCKyDoaTNTsoFDNO/b3+XB5/dt+ KIZaiTTPxmJTmnryhnKxXcuhIXKYgWoj+m2RU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=RbnyDvKBIakheoYpsZY1SkQ8eDkgkUn0mQTm59BWgpI=; b=RKNdfI/3UMILlbqFkc3muYi74RzTE8KAr+JzsYK/6xLYcCXYeiBpdqEhk8oYje5Ufg FcdETQQ/L6mQpq+Vh6L6TEcogZeyIzsCVEPjnS8VEx1VDx8xs+2YGli0tmZ7X9/iz38q j7q+HaY9NbjpmmR8K17ACLRiMD7yXHg8tTPhN6MUtf2UtSf+fAur+3chWlmCOsxvjMPO +JgI7dfA3MsUGS3VunXU4zUq3ybnW3FR3NzPuajz+ex/XWiI9WUaywQHfNW/JKgDG/h1 OAiIr1Dqe1RIXAO7JklczqP4HPkAfsJs4W1+fyTbk9PZwFo1Nzt2MoUd1se7/2J8MgbK foZQ== X-Gm-Message-State: AOUpUlEtDp9kihjH0az/z/ItGJ/CpySyPnSgkJTLvFM208fNVTfU+pwU 6KnzVKnz7I7/yTcokjAV+voltw== X-Google-Smtp-Source: AAOMgpcnknvWW6bzJ4ndDLKTZOGHnmgdz2G76D3xhh0q+ppsk7E/rMkcB7NlAIzm+OZx455/BEBc3g== X-Received: by 2002:a17:902:9a06:: with SMTP id v6-v6mr132257plp.21.1531341394170; Wed, 11 Jul 2018 13:36:34 -0700 (PDT) Received: from www.outflux.net (173-164-112-133-Oregon.hfc.comcastbusiness.net. [173.164.112.133]) by smtp.gmail.com with ESMTPSA id k16-v6sm8477590pfb.93.2018.07.11.13.36.26 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 11 Jul 2018 13:36:28 -0700 (PDT) From: Kees Cook To: Herbert Xu Cc: Kees Cook , "Gustavo A. R. Silva" , Arnd Bergmann , Eric Biggers , Alasdair Kergon , Giovanni Cabiddu , Lars Persson , Mike Snitzer , Rabin Vincent , Tim Chen , "David S. Miller" , Masahiro Yamada , linux-crypto@vger.kernel.org, qat-linux@intel.com, dm-devel@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH v4 09/14] crypto: shash: Remove VLA usage in unaligned hashing Date: Wed, 11 Jul 2018 13:36:14 -0700 Message-Id: <20180711203619.1020-10-keescook@chromium.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180711203619.1020-1-keescook@chromium.org> References: <20180711203619.1020-1-keescook@chromium.org> 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 In the quest to remove all stack VLA usage from the kernel[1], this uses the newly defined max alignment to perform unaligned hashing to avoid VLAs, and drops the helper function while adding sanity checks on the resulting buffer sizes. Additionally, the __aligned_largest macro is removed since this helper was the only user. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook --- crypto/shash.c | 27 ++++++++++++++++----------- include/linux/compiler-gcc.h | 1 - 2 files changed, 16 insertions(+), 12 deletions(-) diff --git a/crypto/shash.c b/crypto/shash.c index ab6902c6dae7..8d4746b14dd5 100644 --- a/crypto/shash.c +++ b/crypto/shash.c @@ -73,13 +73,6 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key, } EXPORT_SYMBOL_GPL(crypto_shash_setkey); -static inline unsigned int shash_align_buffer_size(unsigned len, - unsigned long mask) -{ - typedef u8 __aligned_largest u8_aligned; - return len + (mask & ~(__alignof__(u8_aligned) - 1)); -} - static int shash_update_unaligned(struct shash_desc *desc, const u8 *data, unsigned int len) { @@ -88,11 +81,17 @@ static int shash_update_unaligned(struct shash_desc *desc, const u8 *data, unsigned long alignmask = crypto_shash_alignmask(tfm); unsigned int unaligned_len = alignmask + 1 - ((unsigned long)data & alignmask); - u8 ubuf[shash_align_buffer_size(unaligned_len, alignmask)] - __aligned_largest; + /* + * We cannot count on __aligned() working for large values: + * https://patchwork.kernel.org/patch/9507697/ + */ + u8 ubuf[MAX_ALGAPI_ALIGNMASK * 2]; u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1); int err; + if (WARN_ON(buf + unaligned_len > ubuf + sizeof(ubuf))) + return -EINVAL; + if (unaligned_len > len) unaligned_len = len; @@ -124,11 +123,17 @@ static int shash_final_unaligned(struct shash_desc *desc, u8 *out) unsigned long alignmask = crypto_shash_alignmask(tfm); struct shash_alg *shash = crypto_shash_alg(tfm); unsigned int ds = crypto_shash_digestsize(tfm); - u8 ubuf[shash_align_buffer_size(ds, alignmask)] - __aligned_largest; + /* + * We cannot count on __aligned() working for large values: + * https://patchwork.kernel.org/patch/9507697/ + */ + u8 ubuf[MAX_ALGAPI_ALIGNMASK + SHASH_MAX_DIGESTSIZE]; u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1); int err; + if (WARN_ON(buf + ds > ubuf + sizeof(ubuf))) + return -EINVAL; + err = shash->final(desc, buf); if (err) goto out; diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index f1a7492a5cc8..1f1cdef36a82 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -125,7 +125,6 @@ */ #define __pure __attribute__((pure)) #define __aligned(x) __attribute__((aligned(x))) -#define __aligned_largest __attribute__((aligned)) #define __printf(a, b) __attribute__((format(printf, a, b))) #define __scanf(a, b) __attribute__((format(scanf, a, b))) #define __attribute_const__ __attribute__((__const__))