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Thu, 6 Oct 2022 18:50:54 +0000 (UTC) X-FDA: 79991416428.09.4188BC5 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf17.hostedemail.com (Postfix) with ESMTP id 5961840019 for ; Thu, 6 Oct 2022 18:50:54 +0000 (UTC) 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 18CF761A66; Thu, 6 Oct 2022 18:50:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91689C433D6; Thu, 6 Oct 2022 18:50:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1665082252; bh=AGnaOsCZJB2D12fIhHy6tdcZWEtEWaGlKpZIQ+DL/bI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cUIJwKsq7bClVzGiRmW5rpzBZ8wyXxXV76CAkIxeLxec40X5Vtjk6vT+2r7DW0Nx7 yZb6toL1wruJgIHaRrLqSrpdeqO7ZD/zUqr7aKpNOHcjmx/oLirEAVRATqNGBfd1vS wiI4yiJWXdSfw21Qyb50R2AjH4zkdhdQEMa4+Yo0xkgWdkkLy1ursPzT7TQt6mX96L c3AXWzTVSOxggtPlKPvuWrLoV1QXtYui5575fLqMCbUCfs3b+UxdIGVenet9JGTYgb +hZgAOAgjDgLtzzzZvL0pZ1edFp3t+7oVw4ivAxymvcdohOxuGIxmD+wyBoKBHThH6 hflmjmfQYFAPg== Date: Thu, 6 Oct 2022 21:50:28 +0300 From: Mike Rapoport To: "Edgecombe, Rick P" Cc: "keescook@chromium.org" , "bsingharora@gmail.com" , "hpa@zytor.com" , "Syromiatnikov, Eugene" , "peterz@infradead.org" , "rdunlap@infradead.org" , "dave.hansen@linux.intel.com" , "kirill.shutemov@linux.intel.com" , "Eranian, Stephane" , "linux-mm@kvack.org" , "fweimer@redhat.com" , "nadav.amit@gmail.com" , "jannh@google.com" , "dethoma@microsoft.com" , "linux-arch@vger.kernel.org" , "kcc@google.com" , "bp@alien8.de" , "oleg@redhat.com" , "hjl.tools@gmail.com" , "Yang, Weijiang" , "Lutomirski, Andy" , "pavel@ucw.cz" , "arnd@arndb.de" , "Moreira, Joao" , "tglx@linutronix.de" , "mike.kravetz@oracle.com" , "x86@kernel.org" , "linux-doc@vger.kernel.org" , "jamorris@linux.microsoft.com" , "john.allen@amd.com" , "mingo@redhat.com" , "Shankar, Ravi V" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" , "gorcunov@gmail.com" Subject: Re: [PATCH v2 23/39] x86: Introduce userspace API for CET enabling Message-ID: References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-24-rick.p.edgecombe@intel.com> <202210031141.0E0DE2CAEE@keescook> <8d453bb86cfe45125f2c9f2dba273d1f45d33638.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8d453bb86cfe45125f2c9f2dba273d1f45d33638.camel@intel.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665082254; a=rsa-sha256; cv=none; b=zEjvg/MpUrymJIBkfAM5XXklrn9VUJ8u+MWqAj1zmMcpwDZmR9IXhP+CBXgGRN5grTmEo5 ZwWMC9++RZi1XTddTiuHmJNunSg5Yq4zcpyarppbJSQPbyaMDmTEMwb6KG6ZbIdrdPIkYt aJ+Pf2A39u+zkiEKwjkf5aRHM/CROUY= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=cUIJwKsq; spf=pass (imf17.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665082254; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=yzHRPZdvAOX6gKEst0mcONazW7aEXQyBKxnBxsPuhaM=; b=LOr2v1pLZgOXk3sdEVgGRKdmpk5PCdnrgjcxIFqSS3hEfdnSVrwiq2clfEASRu1gMs9HmM NygG6QxpEynJaO4iOa/Z+SXbhuXkmzhcG4k8t2NMcPd39ziZUXku/3IMw8pdZPsT53yIme YzAXyf4CQMqVkXgn0xoinT7NitSFrZE= X-Rspam-User: Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=cUIJwKsq; spf=pass (imf17.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Stat-Signature: qide67n3kdbro75dq4s35ue9nnwsscb3 X-Rspamd-Queue-Id: 5961840019 X-Rspamd-Server: rspam01 X-HE-Tag: 1665082254-69036 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Oct 03, 2022 at 10:51:02PM +0000, Edgecombe, Rick P wrote: > CC Mike about ptrace/CRIU question. > > On Mon, 2022-10-03 at 12:01 -0700, Kees Cook wrote: > > On Thu, Sep 29, 2022 at 03:29:20PM -0700, Rick Edgecombe wrote: > > > From: "Kirill A. Shutemov" > > > > > > Add three new arch_prctl() handles: > > > > > > - ARCH_CET_ENABLE/DISABLE enables or disables the specified > > > feature. Returns 0 on success or an error. > > > > > > - ARCH_CET_LOCK prevents future disabling or enabling of the > > > specified feature. Returns 0 on success or an error > > > > > > The features are handled per-thread and inherited over > > > fork(2)/clone(2), > > > but reset on exec(). ... > > > +#include > > > +#include > > > +#include > > > + > > > +long cet_prctl(struct task_struct *task, int option, unsigned long > > > features) > > > +{ > > > + if (option == ARCH_CET_LOCK) { > > > + task->thread.features_locked |= features; > > > + return 0; > > > + } > > > + > > > + /* Don't allow via ptrace */ > > > + if (task != current) > > > + return -EINVAL; > > > > ... but locking _is_ allowed via ptrace? If that intended, it should > > be > > explicitly mentioned in the commit log and in a comment here. > > I believe CRIU needs to lock via ptrace as well. Maybe Mike can > confirm. Actually, I didn't use ptrace for locking, I did it with "plain" arch_prctl(). I still can't say for sure CRIU won't need this, I didn't have time yet to have a closer look at this set. -- Sincerely yours, Mike.