From patchwork Wed Apr 21 07:55:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 425358 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 8EF81C43470 for ; Wed, 21 Apr 2021 07:55:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 577A661434 for ; Wed, 21 Apr 2021 07:55:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235107AbhDUHz6 (ORCPT ); Wed, 21 Apr 2021 03:55:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:54784 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237503AbhDUHzz (ORCPT ); Wed, 21 Apr 2021 03:55:55 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 168806143A; Wed, 21 Apr 2021 07:55:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618991722; bh=Ckt8C8nl3QhgUfJhMmpZtLEs1VTyK1g47DgJO1qo5CI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qSvQ8qH+6Ef1OeqB7SaG0W6Kko1Utphhkn1DHCars7TQ/PmoCSauQYtb+bbu61gEd VpHHSm0oLfzcEv9Wjgv/ThfpmX2J0vpyTrNA2CGNEvXAtIiXXuJw2N2ZjkcHN+6/Ai X/1SedqFtDtfVxTCqNtIVUvaf1wJ3hgbRqSvpI1K3dMAM7W/MqsmBYoOinm6hXVTqS xuIOP/eM3aAcg2HyBNy9+/3Vy8NYmQb80IqrusSONYWxeNjkLiG5FjTxgLatjDghtu 0Haf5ESq202HOGnmpQeuDreg22L3cQngHeF+m8sfWmCiRzOQyRXV+/KAl4DiXqHGKE /VYqDBpsrJt5g== From: Ard Biesheuvel To: linux-crypto@vger.kernel.org Cc: linux-fscrypt@vger.kernel.org, Ard Biesheuvel , "Theodore Y. Ts'o" , Jaegeuk Kim , Eric Biggers , Eric Biggers Subject: [PATCH v2 2/2] fsverity: relax build time dependency on CRYPTO_SHA256 Date: Wed, 21 Apr 2021 09:55:11 +0200 Message-Id: <20210421075511.45321-3-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210421075511.45321-1-ardb@kernel.org> References: <20210421075511.45321-1-ardb@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org CONFIG_CRYPTO_SHA256 denotes the generic C implementation of the SHA-256 shash algorithm, which is selected as the default crypto shash provider for fsverity. However, fsverity has no strict link time dependency, and the same shash could be exposed by an optimized implementation, and arm64 has a number of those (scalar, NEON-based and one based on special crypto instructions). In such cases, it makes little sense to require that the generic C implementation is incorporated as well, given that it will never be called. To address this, relax the 'select' clause to 'imply' so that the generic driver can be omitted from the build if desired. Acked-by: Eric Biggers Signed-off-by: Ard Biesheuvel --- fs/verity/Kconfig | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/verity/Kconfig b/fs/verity/Kconfig index 88fb25119899..24d1b54de807 100644 --- a/fs/verity/Kconfig +++ b/fs/verity/Kconfig @@ -3,9 +3,13 @@ config FS_VERITY bool "FS Verity (read-only file-based authenticity protection)" select CRYPTO - # SHA-256 is selected as it's intended to be the default hash algorithm. + # SHA-256 is implied as it's intended to be the default hash algorithm. # To avoid bloat, other wanted algorithms must be selected explicitly. - select CRYPTO_SHA256 + # Note that CRYPTO_SHA256 denotes the generic C implementation, but + # some architectures provided optimized implementations of the same + # algorithm that may be used instead. In this case, CRYPTO_SHA256 may + # be omitted even if SHA-256 is being used. + imply CRYPTO_SHA256 help This option enables fs-verity. fs-verity is the dm-verity mechanism implemented at the file level. On supported