From patchwork Thu Jan 19 16:42:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 645239 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CC10C00A5A for ; Thu, 19 Jan 2023 16:45:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230379AbjASQpw (ORCPT ); Thu, 19 Jan 2023 11:45:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230390AbjASQpu (ORCPT ); Thu, 19 Jan 2023 11:45:50 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F323C4E52D; Thu, 19 Jan 2023 08:45:48 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8FB3161CCD; Thu, 19 Jan 2023 16:45:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFE99C433EF; Thu, 19 Jan 2023 16:45:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674146748; bh=SynuDDILfehL2T8hvUkrH01rNlfRaPkey2aIBkXZnIs=; h=From:To:Cc:Subject:Date:From; b=iJ9DCWPjBFu5yEWCcak1CL+EvQGhTSwSldgFj5QwVliquZTANRSw0CJPZ0dFqMmlm x2ttvAu6Jy2sBJUe1EKKHQ0gFWIxHUqPNX4vmEuba4++L02zRzsMiEnWXUIv6F0QWw DPicR+diMSuXSLonCl3ZkbgLmtcX2Y4qnyHkYaYjWFl2LUuIICnlm+1lXcpSIJvv9F b62ggmHkAHEiDshlDaYITgY5inU1WnwIR4i8uDJNqbaiI9uwUknWsCkc290+7WOK9/ GpuOStTndQW1irU3aU5XJgZrHktrGDgg9q/sJ5MSPXWVauk79WtCrstyhvIKCJd136 y+6rzIY3Afekw== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1pIY3L-0007Mp-UA; Thu, 19 Jan 2023 17:46:16 +0100 From: Johan Hovold To: Ard Biesheuvel Cc: Matthew Garrett , Jeremy Kerr , Maximilian Luz , linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold Subject: [PATCH 0/4] efi: verify that variable services are supported Date: Thu, 19 Jan 2023 17:42:51 +0100 Message-Id: <20230119164255.28091-1-johan+linaro@kernel.org> X-Mailer: git-send-email 2.38.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org This series adds a sanity check to make sure that the variable services are actually available before registering the generic efivar ops. This is used to address some potential races with custom efivars implementation such as the Google SMI or upcoming Qualcomm SCM ones. Specifically, efivarfs currently requires that the efivar ops have been registered before module init time even though the Google driver can be built as a module. Instead, the driver has so far relied on the fact that the generic ops have been registered by efi core only to later be overridden by the custom implementation (or Google doesn't use efivarfs). Instead, let's move the efivars sanity check to mount time to allow for late registration of efivars. Note that requiring that all efivars implementation to always be built-in and registered before module init time could be an alternative, but we'd still need to make sure that the custom implementation is then not overridden by the default (broken) one. To avoid such init call games, allowing late registration seems preferable. This would however require any drivers that use efivars to probe defer until it becomes available, which is also unfortunate, but possibly still better than having generic kernels carry multiple built-in efivars implementations. Note that there are currently no such (efivars consumer) drivers in-tree except for the efivars_pstore driver, which currently do rely on efivarfs being available at module init time (and hence may fail to initialise with the custom efivar implementations). Johan Johan Hovold (4): efi: efivars: add efivars printk prefix efivarfs: always register filesystem efi: verify that variable services are supported efi: efivars: prevent double registration drivers/firmware/efi/efi.c | 22 ++++++++++++++++++++++ drivers/firmware/efi/vars.c | 17 ++++++++++++++--- fs/efivarfs/super.c | 6 +++--- 3 files changed, 39 insertions(+), 6 deletions(-)