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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A845C43334 for ; Thu, 16 Jun 2022 16:20:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377564AbiFPQU5 (ORCPT ); Thu, 16 Jun 2022 12:20:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377505AbiFPQU4 (ORCPT ); Thu, 16 Jun 2022 12:20:56 -0400 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD521433B0 for ; Thu, 16 Jun 2022 09:20:54 -0700 (PDT) Received: by mail-pf1-x431.google.com with SMTP id y196so1923313pfb.6 for ; Thu, 16 Jun 2022 09:20:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=y9i2UaKM9g/AdwlOLX3q72dPfl3fDu2HSqiXz/urf2k=; b=Y1JWTj2a8jakWuo8reBEFDWXyjspvcpnlZi9rK7Rp3nZYIx7Mo2Wq/OfqpcxmVSE3t ZrQ4rXWC8v14StGshqIDPL2V5O6VLZZIidiwRXns6uI/PHJ7O+3PAcK1A1XySsYYLiuq /sGld8Uay09+0nfdlDuRGn+p5waw+zOBiYr/s= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=y9i2UaKM9g/AdwlOLX3q72dPfl3fDu2HSqiXz/urf2k=; b=CfMbvj0gdCS73J9KBlGu+HCt9BhjSYAb48FzYX8tiB8nydVBj6etTvAxaDfgX6WPSY SaFazyU1NZYynstpDJTWOGiOYyvJJP2sE2RTGkmFOlFtgPV8xoUMiKHSzVZboTLC2OWc cYdQ1aeYLG1jl9+MSKfW7opqar82jd2dYTUw5SC99X49de0U1TAQl8rOwTMRXF1yKOF9 xHZ5hZyth8VKk3zRB9SCpXHDaKHc2XRONEkrF4UpUnOcu52UReX3bTlJnRxhXR1a15aG RM6MheTOzpWqjOHxcHncytH4Ndy5L+XeAU3WWU+0VyX5PIANfmLjRuUaCYieGpcBBNyy YkHA== X-Gm-Message-State: AJIora/2wvQOmR/VMT5Quxg4pbiGZy5KdsiMEU9wjJB4ShbwebTbFzc1 +ECpbe6kuFI2F9R9wO83sFA2UA== X-Google-Smtp-Source: AGRyM1vCjkA689i2XYRUWz7V9fwE8nRteMkFMgG1fZvk0aXO64dwkkuz3ZjGlHpXFpAb19FgEiKz6g== X-Received: by 2002:a63:4c1d:0:b0:3fd:9833:cdd9 with SMTP id z29-20020a634c1d000000b003fd9833cdd9mr5210207pga.103.1655396454160; Thu, 16 Jun 2022 09:20:54 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id mr11-20020a17090b238b00b001cd4989fec6sm3985726pjb.18.2022.06.16.09.20.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Jun 2022 09:20:53 -0700 (PDT) Date: Thu, 16 Jun 2022 09:20:52 -0700 From: Kees Cook To: Ard Biesheuvel Cc: linux-efi@vger.kernel.org, Matthew Garrett , Peter Jones , Tony Luck , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH 2/2] efi: remove deprecated 'efivars' sysfs interface Message-ID: <202206160919.360DB5F4@keescook> References: <20220616124740.580708-1-ardb@kernel.org> <20220616124740.580708-3-ardb@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220616124740.580708-3-ardb@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Thu, Jun 16, 2022 at 02:47:40PM +0200, Ard Biesheuvel wrote: > Commit 5d9db883761a ("efi: Add support for a UEFI variable filesystem") > dated Oct 5, 2012, introduced a new efivarfs pseudo-filesystem to > replace the efivars sysfs interface that was used up to that point to > expose EFI variables to user space. > > The main problem with the sysfs interface was that it only supported up > to 1024 bytes of payload per file, whereas the underlying variables > themselves are only bounded by a platform specific per-variable and > global limit that is typically much higher than 1024 bytes. > > The deprecated sysfs interface is only enabled on x86 and Itanium, other > EFI enabled architectures only support the efivarfs pseudo-filesystem. Does anything still use the sysfs interface? (e.g. do paths to it exist in anything meaningful in, say, a Debian code search?) -- Kees Cook