From mboxrd@z Thu Jan 1 00:00:00 1970 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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 3EC73C433DF for ; Wed, 8 Jul 2020 13:51:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19BDE2078B for ; Wed, 8 Jul 2020 13:51:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594216303; bh=Fwt5Rp/zrxSRl2UwXuusY3rhdYoew/kfxO8pUURsyYE=; h=From:To:Cc:Subject:Date:List-ID:From; b=pePsLQ5p2IEIZS6QNLjiDhCXucNqIO6kO+0r2AkU/qEwB8FpEQVc9NsJRdiPIifhc 991a7MM7kOza2eWWoW9Hx4X4LTQeCR7wuNs8QviziyZi9jjSM1HBC8ls9jB4WuZuB1 Rx0xNHvh8onipTGWiV5GYbx9MCweOSDycTGCJFkU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729357AbgGHNvm (ORCPT ); Wed, 8 Jul 2020 09:51:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:43606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729288AbgGHNvm (ORCPT ); Wed, 8 Jul 2020 09:51:42 -0400 Received: from e123331-lin.nice.arm.com (adsl-70.109.242.21.tellas.gr [109.242.21.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 63DE6206E2; Wed, 8 Jul 2020 13:51:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594216301; bh=Fwt5Rp/zrxSRl2UwXuusY3rhdYoew/kfxO8pUURsyYE=; h=From:To:Cc:Subject:Date:From; b=C6O+pA8H4U3atv9ZVozgmumdAJHIJoGIvhtGgRbkUJ4G6qTjh5x8tENjYaexVzqrR ninxo5C1cPvasA7mYM15HGvEmLjqJtN+xxQGf3UsPye9sOpSIfL+KNLLa4oWfRBZft m8ZcPg7McKJ/PvPpPMavX1UHhoanP4u2irS6IJ4M= From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: xypron.glpk@gmx.de, Ard Biesheuvel , Ilias Apalodimas Subject: [PATCH v3] efi/efivars: Expose RT service availability via efivars abstraction Date: Wed, 8 Jul 2020 16:51:35 +0300 Message-Id: <20200708135135.11163-1-ardb@kernel.org> X-Mailer: git-send-email 2.17.1 Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Commit bf67fad19e493b ("efi: Use more granular check for availability for variable services") introduced a check into the efivarfs, efi-pstore and other drivers that aborts loading of the module if not all three variable runtime services (GetVariable, SetVariable and GetNextVariable) are supported. However, this results in efivarfs being unavailable entirely if only SetVariable support is missing, which is only needed if you want to make any modifications. Also, efi-pstore and the sysfs EFI variable interface could be backed by another implementation of the 'efivars' abstraction, in which case it is completely irrelevant which services are supported by the EFI firmware. So make the generic 'efivars' abstraction dependent on the availibility of the GetVariable and GetNextVariable EFI runtime services, and add a helper to find out whether the current 'efivars' abstraction supports writes (and wire it up to the availability of SetVariable for the generic one) Cc: Ilias Apalodimas Fixes: bf67fad19e493b ("efi: Use more granular check for availability for variable services") Reported-by: Heinrich Schuchardt Signed-off-by: Ard Biesheuvel --- v3 of [0], which fixed things at the wrong layer - efivarfs does not care about EFI firmware, it only talks to the lower 'efivars' layer, which can be implemented in various different ways. [0] https://lore.kernel.org/linux-efi/20200708111938.20948-1-ardb@kernel.org/ drivers/firmware/efi/efi-pstore.c | 5 +---- drivers/firmware/efi/efi.c | 12 ++++++++---- drivers/firmware/efi/efivars.c | 5 +---- drivers/firmware/efi/vars.c | 6 ++++++ fs/efivarfs/super.c | 6 +++--- include/linux/efi.h | 1 + 6 files changed, 20 insertions(+), 15 deletions(-) diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c index c2f1d4e6630b..feb7fe6f2da7 100644 --- a/drivers/firmware/efi/efi-pstore.c +++ b/drivers/firmware/efi/efi-pstore.c @@ -356,10 +356,7 @@ static struct pstore_info efi_pstore_info = { static __init int efivars_pstore_init(void) { - if (!efi_rt_services_supported(EFI_RT_SUPPORTED_VARIABLE_SERVICES)) - return 0; - - if (!efivars_kobject()) + if (!efivars_kobject() || !efivar_supports_writes()) return 0; if (efivars_pstore_disable) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 5114cae4ec97..fdd1db025dbf 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -176,11 +176,13 @@ static struct efivar_operations generic_ops; static int generic_ops_register(void) { generic_ops.get_variable = efi.get_variable; - generic_ops.set_variable = efi.set_variable; - generic_ops.set_variable_nonblocking = efi.set_variable_nonblocking; generic_ops.get_next_variable = efi.get_next_variable; generic_ops.query_variable_store = efi_query_variable_store; + if (efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE)) { + generic_ops.set_variable = efi.set_variable; + generic_ops.set_variable_nonblocking = efi.set_variable_nonblocking; + } return efivars_register(&generic_efivars, &generic_ops, efi_kobj); } @@ -382,7 +384,8 @@ static int __init efisubsys_init(void) return -ENOMEM; } - if (efi_rt_services_supported(EFI_RT_SUPPORTED_VARIABLE_SERVICES)) { + if (efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE | + EFI_RT_SUPPORTED_GET_NEXT_VARIABLE_NAME)) { efivar_ssdt_load(); error = generic_ops_register(); if (error) @@ -416,7 +419,8 @@ static int __init efisubsys_init(void) err_remove_group: sysfs_remove_group(efi_kobj, &efi_subsys_attr_group); err_unregister: - if (efi_rt_services_supported(EFI_RT_SUPPORTED_VARIABLE_SERVICES)) + if (efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE | + EFI_RT_SUPPORTED_GET_NEXT_VARIABLE_NAME)) generic_ops_unregister(); err_put: kobject_put(efi_kobj); diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c index 26528a46d99e..dcea137142b3 100644 --- a/drivers/firmware/efi/efivars.c +++ b/drivers/firmware/efi/efivars.c @@ -680,11 +680,8 @@ int efivars_sysfs_init(void) struct kobject *parent_kobj = efivars_kobject(); int error = 0; - if (!efi_rt_services_supported(EFI_RT_SUPPORTED_VARIABLE_SERVICES)) - return -ENODEV; - /* No efivars has been registered yet */ - if (!parent_kobj) + if (!parent_kobj || !efivar_supports_writes()) return 0; printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION, diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 5f2a4d162795..973eef234b36 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -1229,3 +1229,9 @@ int efivars_unregister(struct efivars *efivars) return rv; } EXPORT_SYMBOL_GPL(efivars_unregister); + +int efivar_supports_writes(void) +{ + return __efivars && __efivars->ops->set_variable; +} +EXPORT_SYMBOL_GPL(efivar_supports_writes); diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c index 12c66f5d92dd..28bb5689333a 100644 --- a/fs/efivarfs/super.c +++ b/fs/efivarfs/super.c @@ -201,6 +201,9 @@ static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_d_op = &efivarfs_d_ops; sb->s_time_gran = 1; + if (!efivar_supports_writes()) + sb->s_flags |= SB_RDONLY; + inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); if (!inode) return -ENOMEM; @@ -252,9 +255,6 @@ static struct file_system_type efivarfs_type = { static __init int efivarfs_init(void) { - if (!efi_rt_services_supported(EFI_RT_SUPPORTED_VARIABLE_SERVICES)) - return -ENODEV; - if (!efivars_kobject()) return -ENODEV; diff --git a/include/linux/efi.h b/include/linux/efi.h index bb35f3305e55..05c47f857383 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -994,6 +994,7 @@ int efivars_register(struct efivars *efivars, int efivars_unregister(struct efivars *efivars); struct kobject *efivars_kobject(void); +int efivar_supports_writes(void); int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *), void *data, bool duplicates, struct list_head *head); -- 2.17.1