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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=no 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 ABBFDC3A59F for ; Fri, 30 Aug 2019 01:11:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71A5422CEA for ; Fri, 30 Aug 2019 01:11:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567127506; bh=cxG/Csv0dO0dzHh0hw8hEJaJviptwRvJ+VuvpnA+zQ4=; h=From:To:Cc:Subject:Date:List-ID:From; b=iN2NBT5LltB3xM45z6RHKhKdaAlEx9xdZjZbOdA8RMyYCObSV6udHVTVTQTFG9tqh e4PbHSqzVtFRYkLAqEet+n653xM+AaqGPRfb0yD4qL2NY0jFeAsArNdeAbuPDDD7wi W3K2Npaynmg3tQgJTD3/0shKBlBUL7sKzszKvlXo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727392AbfH3BLp (ORCPT ); Thu, 29 Aug 2019 21:11:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:58244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726825AbfH3BLp (ORCPT ); Thu, 29 Aug 2019 21:11:45 -0400 Received: from localhost (c-67-180-165-146.hsd1.ca.comcast.net [67.180.165.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 15A1021726; Fri, 30 Aug 2019 01:11:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567127504; bh=cxG/Csv0dO0dzHh0hw8hEJaJviptwRvJ+VuvpnA+zQ4=; h=From:To:Cc:Subject:Date:From; b=l/e54Qwqc4S7T7xLPRTF6aL4Jp+Ft+XfOURSQfTJJcFanYajZm4eXqJvTB/OWotdG e/Z4n40q+Lpn5mGyt7s9me5IKpUekh65VHkFqGcCsx0O7PwtDupXtBV+/1hsbyShOO lxQPHtbVUafs469dKHT7RY8OanI7Fq4cbzJy4+hM= From: Andy Lutomirski To: Theodore Tso Cc: LKML , Linux API , Kees Cook , "Jason A. Donenfeld" , Andy Lutomirski Subject: [PATCH 0/7] Rework random blocking Date: Thu, 29 Aug 2019 18:11:35 -0700 Message-Id: X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This makes two major semantic changes to Linux's random APIs: It adds getentropy(..., GRND_INSECURE). This causes getentropy to always return *something*. There is no guarantee whatsoever that the result will be cryptographically random or even unique, but the kernel will give the best quality random output it can. The name is a big hint: the resulting output is INSECURE. The purpose of this is to allow programs that genuinely want best-effort entropy to get it without resorting to /dev/urandom. Plenty of programs do this because they need to do *something* during boot and they can't afford to wait. Calling it "INSECURE" is probably the best we can do to discourage using this API for things that need security. This series also removes the blocking pool and makes /dev/random work just like getentropy(..., 0) and makes GRND_RANDOM a no-op. I believe that Linux's blocking pool has outlived its usefulness. Linux's CRNG generates output that is good enough to use even for key generation. The blocking pool is not stronger in any material way, and keeping it around requires a lot of infrastructure of dubious value. This series should not break any existing programs. /dev/urandom is unchanged. /dev/random will still block just after booting, but it will block less than it used to. getentropy() with existing flags will return output that is, for practical purposes, just as strong as before. Andy Lutomirski (7): random: Don't wake crng_init_wait when crng_init == 1 random: Add GRND_INSECURE to return best-effort non-cryptographic bytes random: Ignore GRND_RANDOM in getentropy(2) random: Make /dev/random be almost like /dev/urandom random: Remove the blocking pool random: Delete code to pull data into pools random: Remove kernel.random.read_wakeup_threshold drivers/char/random.c | 234 ++++-------------------------------- include/uapi/linux/random.h | 4 +- 2 files changed, 27 insertions(+), 211 deletions(-) -- 2.21.0