From owner-freebsd-fs@freebsd.org Wed Sep 5 03:13:45 2018 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9158DFE0BC6; Wed, 5 Sep 2018 03:13:45 +0000 (UTC) (envelope-from cse.cem@gmail.com) Received: from mail-it0-f44.google.com (mail-it0-f44.google.com [209.85.214.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 323318E058; Wed, 5 Sep 2018 03:13:45 +0000 (UTC) (envelope-from cse.cem@gmail.com) Received: by mail-it0-f44.google.com with SMTP id 139-v6so7681258itf.0; Tue, 04 Sep 2018 20:13:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:reply-to:in-reply-to:references :from:date:message-id:subject:to:cc; bh=afY1+KdvF0mIZrGupKYbJbDiULwpIROjdW15VeYOVZM=; b=tMApxOD1rLRqTzgBUFj3U5vjcboauemRlS1429JHYTN9sXobHj9xaY/d5OHHEu1Y8A wvovthN2uQeedNR9RTX69JIWJPt1FA3FI1APy4zl7oej4cEbD8ZaJDpxOLLUhfyGRb0G /fWntpmIFBU6K+144cG8dasT5uMSO3Y+hT+3kwcUuAxcA0vIpoHICuR3QRlDKsYAwgzD uFoiKbefriGj6JW+y1wD2EePVsyk3MkuVYiFlzX98ZhJFngUiO9NflC0S0xMUASeDtXG sIx7OlOSFFD430Iv8RY9N3Frr+DlFtlKz972URazKzEZk7iXUV/kaNMtetp1P84hiOto G1yw== X-Gm-Message-State: APzg51DqRJ3G8I+4yZ+f8DwW5NFuuT2SWxy4UD059jEIDDFF5d/1VP9F ih3IZtVemFT1vE7LeK1B08VlmgAV X-Google-Smtp-Source: ANB0VdZw1jGc5hMsLD9vnHaJ8zbV+tpRFEuyBIBum4IFMMaApmTbjIqnQbdm8lVhn3KaAvHRjJYYPw== X-Received: by 2002:a24:4a83:: with SMTP id k125-v6mr10011627itb.121.1536117223274; Tue, 04 Sep 2018 20:13:43 -0700 (PDT) Received: from mail-io0-f176.google.com (mail-io0-f176.google.com. [209.85.223.176]) by smtp.gmail.com with ESMTPSA id 137-v6sm476719itl.39.2018.09.04.20.13.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 04 Sep 2018 20:13:42 -0700 (PDT) Received: by mail-io0-f176.google.com with SMTP id w11-v6so4828456iob.2; Tue, 04 Sep 2018 20:13:42 -0700 (PDT) X-Received: by 2002:a6b:254e:: with SMTP id l75-v6mr23753191iol.47.1536117222414; Tue, 04 Sep 2018 20:13:42 -0700 (PDT) MIME-Version: 1.0 Reply-To: cem@freebsd.org Received: by 2002:a02:9542:0:0:0:0:0 with HTTP; Tue, 4 Sep 2018 20:13:41 -0700 (PDT) In-Reply-To: <774228883.20180905001035@serebryakov.spb.ru> References: <609400979.20180904230820@serebryakov.spb.ru> <1942661439.20180904235514@serebryakov.spb.ru> <774228883.20180905001035@serebryakov.spb.ru> From: Conrad Meyer Date: Tue, 4 Sep 2018 20:13:41 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: newfs silently fails if random is not ready (?) To: Lev Serebryakov Cc: FreeBSD Current , freebsd-fs , Xin LI Content-Type: text/plain; charset="UTF-8" X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Sep 2018 03:13:45 -0000 Hi Lev, I took a first attempt at reproducing this problem on a fast desktop-class system. First steps, give us a way to revert back to unseeded status: --- a/sys/dev/random/fortuna.c +++ b/sys/dev/random/fortuna.c @@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$"); #ifdef _KERNEL #include +#include #include #include #include @@ -384,6 +385,17 @@ random_fortuna_pre_read(void) return; } + /* + * When set, pretend we do not have enough entropy to reseed yet. + */ + KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_pre_read, { + if (RETURN_VALUE != 0) { + RANDOM_RESEED_UNLOCK(); + return; + } + }); + + #ifdef _KERNEL fortuna_state.fs_lasttime = now; #endif @@ -442,5 +454,11 @@ bool random_fortuna_seeded(void) { + /* When set, act as if we are not seeded. */ + KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_seeded, { + if (RETURN_VALUE != 0) + fortuna_state.fs_counter = UINT128_ZERO; + }); + return (!uint128_is_zero(fortuna_state.fs_counter)); } Second step, enable the failpoints and launch repro program: $ sudo sysctl debug.fail_point.random_fortuna_pre_read='return(1)' debug.fail_point.random_fortuna_pre_read: off -> return(1) $ sudo sysctl debug.fail_point.random_fortuna_seeded='return(1)' debug.fail_point.random_fortuna_seeded: off -> return(1) $ cat ./blocked_random_poc.c #include #include #include int main(int argc, char **argv) { printf("%x\n", arc4random()); return (0); } $ ./blocked_random_poc ... Third step, I looked at what that process was doing: Curiously, it is not in getrandom() at all, but instead the ARND sysctl fallback. I probably need to rebuild world (libc) to test this (new libc arc4random based on Chacha). $ procstat -kk 1196 PID TID COMM TDNAME KSTACK 1196 100435 blocked_random_poc - read_random+0x3d sysctl_kern_arnd+0x3a sysctl_root_handler_locked+0x89 sysctl_root.isra.8+0x167 userland_sysctl+0x126 sys___sysctl+0x7b amd64_syscall+0x940 fast_syscall_common+0x101 When I unblocked the failpoints, it completed successfully: $ sudo sysctl debug.fail_point.random_fortuna_pre_read='off' debug.fail_point.random_fortuna_pre_read: return(1) -> off $ sudo sysctl debug.fail_point.random_fortuna_seeded=off debug.fail_point.random_fortuna_seeded: return(1) -> off ... 9e5eb30f Best, Conrad