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 65880EB64D9 for ; Wed, 28 Jun 2023 02:48:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230290AbjF1Csz (ORCPT ); Tue, 27 Jun 2023 22:48:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230059AbjF1Csu (ORCPT ); Tue, 27 Jun 2023 22:48:50 -0400 Received: from mail-qt1-x82b.google.com (mail-qt1-x82b.google.com [IPv6:2607:f8b0:4864:20::82b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C69E129 for ; Tue, 27 Jun 2023 19:48:49 -0700 (PDT) Received: by mail-qt1-x82b.google.com with SMTP id d75a77b69052e-3fddb0bd9e2so56576171cf.0 for ; Tue, 27 Jun 2023 19:48:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1687920528; x=1690512528; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=kVok7rzReJkeEE0XESE8noQp0aQi4RQQpEfbsHD9BtY=; b=mzGmJi6lVfSsOj7545pCntro7v3QarhrsIt+fs8v7HEBmtHW4nslN/9QUPmXfks8FK AIEaM393mwGtNY/kvI7av2GrIzhPWfUXFSgIO//osLPg7sUuqxTHlZtcfJrHZANNEXV4 KQ8LSrVzYRB4dQOWW9VQLL55LG1t8hyIwBMGw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687920528; x=1690512528; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=kVok7rzReJkeEE0XESE8noQp0aQi4RQQpEfbsHD9BtY=; b=EbjQtkIDL9KAnuJrnCloXAKRqM9OC8aNfVMOfDqMtgqq2cldGdVWnak/y3pYkscMHo 7AF4Q+BmwwW5NeHWfOA1RITtvKkS0kCfI0rUQhjCw80fMNNR3CK7m3olq07USwOdnaNi 5LooekS/0Q+402TM4KJVIHtbNTthRUX37d1F1NxG8RDBNLwzqTmTQ2sppl5T7mfb1rRA 1iB2C9Dfiiu7ovxMQ9Q4p5UWIqdiYMVfcrAFxGSbmQd6QlcZRCzWB6SiLQM111soZLGR dketp6cXRn18FSnQU1/82y7QdTdjSsK59lnrdFcnE49jvctGXtADyfVD4UvL6TmL0XXE 5UZA== X-Gm-Message-State: AC+VfDx1QN2Hbrn5aHbyA/cz4rtI9lj3/t+nRX6SZ5Ec2Os1S5lqmJzJ zvJEsONdCteHt950o9TdRIsHYQ== X-Google-Smtp-Source: ACHHUZ4LfA7Jds2Vd+EGmePW5lr5cWPorl/s8Xl9oAMCHfZ3GYdimTmA4yh7MXDmvsXUKDG28RMlxQ== X-Received: by 2002:a05:622a:178b:b0:3ff:33d6:da9f with SMTP id s11-20020a05622a178b00b003ff33d6da9fmr27306908qtk.49.1687920528214; Tue, 27 Jun 2023 19:48:48 -0700 (PDT) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id s17-20020a632c11000000b0053f2037d639sm6390668pgs.81.2023.06.27.19.48.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jun 2023 19:48:46 -0700 (PDT) Date: Tue, 27 Jun 2023 19:48:45 -0700 From: Kees Cook To: Samuel Thibault , Kees Cook , Greg Kroah-Hartman , Jiri Slaby , Simon Brand , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Dave@mielke.cc Subject: Re: [PATCH v3 2/2] tty: Allow TIOCSTI to be disabled Message-ID: <202306271944.E80E1D0@keescook> References: <20221022182828.give.717-kees@kernel.org> <20221022182949.2684794-2-keescook@chromium.org> <20221227234000.jgosvixx7eahqb3z@begin> <20221228205726.rfevry7ud6gmttg5@begin> <20230625155625.s4kvy7m2vw74ow4i@begin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230625155625.s4kvy7m2vw74ow4i@begin> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 25, 2023 at 05:56:25PM +0200, Samuel Thibault wrote: > > Can we perhaps just introduce a CAP_TIOCSTI that the brltty daemon would > > be able to use? We could even make it only allow TIOCSTI on the linux > > console (tty->ops == con_ops). Does brltty run with CAP_SYS_ADMIN? That seems a sensible exception to be made. > *Please* comment on this so we can progress. ATM people are > advising each other to set dev.tty.legacy_tiocsti=1, which is just > counter-productive in terms of security... So is there really no solution for brltty and TIOCSTI being disabled? What is FreeBSD doing? I imagine it's the same situation there too, though maybe there is just no support? https://www.mail-archive.com/brltty@brltty.app/msg02892.html > Really, this a serious regression for the people affected by this. Can you send a patch adding a CAP_SYS_ADMIN exception? -Kees -- Kees Cook