From patchwork Fri Apr 16 16:06:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 12208103 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=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 ADEA2C433B4 for ; Fri, 16 Apr 2021 16:06:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DC82611C2 for ; Fri, 16 Apr 2021 16:06:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239729AbhDPQHV (ORCPT ); Fri, 16 Apr 2021 12:07:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:37438 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239183AbhDPQHU (ORCPT ); Fri, 16 Apr 2021 12:07:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 24F9C6113D; Fri, 16 Apr 2021 16:06:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618589215; bh=rTkLI/G7keGXQVgDyrI7UE8GeDTwoxdlSggyy76+H4g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y6gVbgDxaz/ZztWn7rWw5DW6/Swqkno/dGBQ0fhO3aHMiuaY/kd/YOVkyCU4suAio fm6sZKg1DezRKaqo0OSX/WYpxo4nvopfoUd5t9BMaL34lQBU3EJy1bXzwRWPUJPnef 0xZ351NAknAzONLoPA/txYI2w2KytoQZ5W5WzMdHi+aph0HIuQZhAhpVdA0Y5JRos5 7LKTuoufSK7STg44rpcrOViMO67VolqQLpXli9poWOgm5FFrWeGlCV0PF+TqcsDfIT Uak50ip4IVV1EorGmBMESs02rndc2AnTQfIXAxWcgWPXIuRXSBe4W/Tu7wffRi2zUK Iihedt1/QqAEg== 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 Subject: [PATCH 2/2] fsverity: relax build time dependency on CRYPTO_SHA256 Date: Fri, 16 Apr 2021 18:06:42 +0200 Message-Id: <20210416160642.85387-3-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210416160642.85387-1-ardb@kernel.org> References: <20210416160642.85387-1-ardb@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@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. Signed-off-by: Ard Biesheuvel Acked-by: Eric Biggers --- 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