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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 D97E7C43219 for ; Mon, 29 Apr 2019 07:49:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B202A2075E for ; Mon, 29 Apr 2019 07:49:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727533AbfD2Htl convert rfc822-to-8bit (ORCPT ); Mon, 29 Apr 2019 03:49:41 -0400 Received: from mga17.intel.com ([192.55.52.151]:24807 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726718AbfD2Htl (ORCPT ); Mon, 29 Apr 2019 03:49:41 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Apr 2019 00:49:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,408,1549958400"; d="scan'208";a="341727417" Received: from irsmsx103.ger.corp.intel.com ([163.33.3.157]) by fmsmga006.fm.intel.com with ESMTP; 29 Apr 2019 00:49:37 -0700 Received: from irsmsx102.ger.corp.intel.com ([169.254.2.21]) by IRSMSX103.ger.corp.intel.com ([169.254.3.30]) with mapi id 14.03.0415.000; Mon, 29 Apr 2019 08:49:36 +0100 From: "Reshetova, Elena" To: Theodore Ts'o CC: Eric Biggers , "ebiggers@google.com" , "herbert@gondor.apana.org.au" , David Laight , "Ingo Molnar" , 'Peter Zijlstra' , "keescook@chromium.org" , Daniel Borkmann , "luto@kernel.org" , "luto@amacapital.net" , "linux-kernel@vger.kernel.org" , "jpoimboe@redhat.com" , "jannh@google.com" , "Perla, Enrico" , "mingo@redhat.com" , "bp@alien8.de" , "tglx@linutronix.de" , "gregkh@linuxfoundation.org" , "Edgecombe, Rick P" Subject: RE: [PATCH] x86/entry/64: randomize kernel stack offset upon syscall Thread-Topic: [PATCH] x86/entry/64: randomize kernel stack offset upon syscall Thread-Index: AQHU81HQwzT9MH4dM0y/JZXnSwiYT6Y8wW2AgAAdM1CAAXexAIAANZ3ggAAW1gCAAApRgIAAMeKAgAAd+PCAAQuGgIAAYQuAgAAKhwCACsPi4IADJTwAgAAcagCABF9DMA== Date: Mon, 29 Apr 2019 07:49:36 +0000 Message-ID: <2236FBA76BA1254E88B949DDB74E612BA4C66AA0@IRSMSX102.ger.corp.intel.com> References: <2236FBA76BA1254E88B949DDB74E612BA4C51962@IRSMSX102.ger.corp.intel.com> <20190416120822.GV11158@hirez.programming.kicks-ass.net> <01914abbfc1a4053897d8d87a63e3411@AcuMS.aculab.com> <20190416154348.GB3004@mit.edu> <2236FBA76BA1254E88B949DDB74E612BA4C52338@IRSMSX102.ger.corp.intel.com> <9cf586757eb44f2c8f167abf078da921@AcuMS.aculab.com> <20190417151555.GG4686@mit.edu> <99e045427125403ba2b90c2707d74e02@AcuMS.aculab.com> <2236FBA76BA1254E88B949DDB74E612BA4C5E473@IRSMSX102.ger.corp.intel.com> <2236FBA76BA1254E88B949DDB74E612BA4C63E24@IRSMSX102.ger.corp.intel.com> <20190426140102.GA4922@mit.edu> In-Reply-To: <20190426140102.GA4922@mit.edu> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-version: 11.0.600.7 dlp-reaction: no-action x-ctpclassification: CTP_NT x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiNjk1M2FlY2UtNGNjNi00NGE3LTkyOGMtYWI0NjUxYWVmZmY1IiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX05UIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE3LjEwLjE4MDQuNDkiLCJUcnVzdGVkTGFiZWxIYXNoIjoicXh0RVBVY2VhQittUTM2UUNyblVEa1JtT2lFa0NaMzRmRExPMnRDOU05N0Fpc0NIVGEzTGkzQzVTSUpNRzlaYyJ9 x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Fri, Apr 26, 2019 at 11:33:09AM +0000, Reshetova, Elena wrote: > > Adding Eric and Herbert to continue discussion for the chacha part. > > So, as a short summary I am trying to find out a fast (fast enough to be used per > syscall > > invocation) source of random bits with good enough security properties. > > I started to look into chacha kernel implementation and while it seems that it is > designed to > > work with any number of rounds, it does not expose less than 12 rounds primitive. > > I guess this is done for security sake, since 12 is probably the lowest bound we > want people > > to use for the purpose of encryption/decryption, but if we are to build an efficient > RNG, > > chacha8 probably is a good tradeoff between security and speed. > > > > What are people's opinions/perceptions on this? Has it been considered before to > create a > > kernel RNG based on chacha? > > Well, sure. The get_random_bytes() kernel interface and the > getrandom(2) system call uses a CRNG based on chacha20. See > extract_crng() and crng_reseed() in drivers/char/random.c. Oh, indeed, I missed this link fully when was trying to trace chacha usages in kernel. I am not familiar with crypto kernel API and looks like my source code cross referencing failed here miserably. Only question left is how fast/slow is this... Best Regards, Elena.