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 80F76C05024 for ; Wed, 20 Sep 2023 20:45:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229736AbjITUpe (ORCPT ); Wed, 20 Sep 2023 16:45:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229473AbjITUpc (ORCPT ); Wed, 20 Sep 2023 16:45:32 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF453BB; Wed, 20 Sep 2023 13:45:26 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45759C433C8; Wed, 20 Sep 2023 20:45:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695242726; bh=Hx+q61jajuliDCZJUgYhvKUrGKzfegjn/TP0h2Ov1Dg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KVm4FjIYgfM/qdkOdiTv2g5lm/WKMcQuw5C3HLtZS00D9g3EOUPRKRyPkIc1rmvPA qp1Hu5NYlj+VLN5u1PfY2OEUQOgL/cH5OCvtoQS+WPN2Z1hmWqfWD8lbhL+WhyLUrk I1fDWgDvk2z8qte6fXLOxCG/P6B0CxwmHVY9jWx5X8YpYFuHaG99xq2A25zq8aX1Gv /stmkEk4S0kyJDlQQqZfmE4D0qcWj4yzXuuxRO2o7hQECrxkrq+exmliMXugVGRrLz pkioCuqclAZ1tgjCV9u4/lyNaEjYI8FYZba8Wz/HEfCeWqnQjmerRJCOXZOLOP65fR +0nwx1zJqZh7Q== Date: Wed, 20 Sep 2023 13:45:24 -0700 From: Eric Biggers To: Linus Torvalds Cc: "Jason A. Donenfeld" , linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, Theodore Ts'o , Dominik Brodowski , Jann Horn Subject: Re: [RFC] Should writes to /dev/urandom immediately affect reads? Message-ID: <20230920204524.GD914@sol.localdomain> References: <20230920060615.GA2739@sol.localdomain> <20230920193203.GA914@sol.localdomain> <20230920202126.GC914@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 20, 2023 at 01:32:29PM -0700, Linus Torvalds wrote: > On Wed, 20 Sept 2023 at 13:21, Eric Biggers wrote: > > > > It seems that what you're claiming (in addition to the RNG always being > > initialized quickly on platforms that are "relevant", whatever that means) is > > that once the RNG is "initialized", there's no need to reseed it anymore. > > No. You are literally putting words in my mouth that I at no point > even implied. You're making up an argument. > > I *LITERALLY* am asking a very simple question: WHO DO YOU EVEN CARE > ABOUT THIS "IMMEDIATE" EFFECT. > > Give me a real reason. Give me *any* reason. > > Don't try to turn this into some other discussion. I'm asking WHY DOES > ANY OF THIS MATTER? > > The immediacy has changed several times, as you yourself lined up. And > as far as I can tell, none of this matter in the least. > > > The question is, given that, shouldn't the RNG also reseed right > > away when userspace explicitly adds something to it > > I don't see that there is any "given" at all. > > We do re-seed regularly. I'm not arguing against that. > > I'm literally arguing against applying random changes without giving > any actual reason for them. > > Which is why I'm asking "why do you care"? Give em a *reason*. Why > would a user space write matter at all? > > It was why I also asked about entropy. Because *if* you argue that the > user-space write contains entropy, then that would be a reason. > > You didn't. > > You argue that the current behavior hasn't been the universal behavior. I agree. > > But considering that we've switched behaviors apparently at least > three times, and at no point did it make any difference, my argument > is really that without a *REASON*, why would we switch behavior *four* > times? > > Is it just "four changes is better than three"? See my first email where I explained the problems with the current behavior. Especially the third paragraph. I'll just wait until Jason has a chance to reply. This discussion clearly isn't achieving anything with just us two. - Eric