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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 43A92C43381 for ; Thu, 21 Feb 2019 00:32:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF8EA2147A for ; Thu, 21 Feb 2019 00:32:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mit.edu header.i=@mit.edu header.b="cNK7eBvm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726941AbfBUAcb (ORCPT ); Wed, 20 Feb 2019 19:32:31 -0500 Received: from mail-eopbgr700117.outbound.protection.outlook.com ([40.107.70.117]:28256 "EHLO NAM04-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726090AbfBUAca (ORCPT ); Wed, 20 Feb 2019 19:32:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=CjYcX06eXsZbL9+qh4cvoFVYmikYN4bl6k4UStlm0SA=; b=cNK7eBvmB+GI04ksqNBeob59ksMj2/NZHdqK1ZwYifPW0LFqF7vsaBM1dcEskUukfDPst0imqZ5ui+0WeYFN8vrPZXSjSoPecFvruDSFq0jQehdT0saCUQGsvz7FJy1kf11Zwu90AZ4CtAMtMjwMYPlhA8pLdon63ttxmT6H+Ak= Received: from DM5PR0102CA0013.prod.exchangelabs.com (2603:10b6:4:9c::26) by BYAPR01MB4853.prod.exchangelabs.com (2603:10b6:a03:91::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1622.18; Thu, 21 Feb 2019 00:32:25 +0000 Received: from CO1NAM03FT006.eop-NAM03.prod.protection.outlook.com (2a01:111:f400:7e48::203) by DM5PR0102CA0013.outlook.office365.com (2603:10b6:4:9c::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.1622.16 via Frontend Transport; Thu, 21 Feb 2019 00:32:25 +0000 Authentication-Results: spf=pass (sender IP is 18.9.28.11) smtp.mailfrom=mit.edu; vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=bestguesspass action=none header.from=mit.edu; Received-SPF: Pass (protection.outlook.com: domain of mit.edu designates 18.9.28.11 as permitted sender) receiver=protection.outlook.com; client-ip=18.9.28.11; helo=outgoing.mit.edu; Received: from outgoing.mit.edu (18.9.28.11) by CO1NAM03FT006.mail.protection.outlook.com (10.152.80.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.1643.13 via Frontend Transport; Thu, 21 Feb 2019 00:32:24 +0000 Received: from callcc.thunk.org (guestnat-104-133-8-99.corp.google.com [104.133.8.99] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x1L0WLfh029161 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 Feb 2019 19:32:23 -0500 Received: by callcc.thunk.org (Postfix, from userid 15806) id 4CE037A3F7C; Wed, 20 Feb 2019 19:32:21 -0500 (EST) Date: Wed, 20 Feb 2019 19:32:21 -0500 From: "Theodore Y. Ts'o" To: Bernd Edlinger CC: Arnd Bergmann , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" Subject: Re: [PATCHv5] random: Make /dev/random wait for input_pool initializedy Message-ID: <20190221003221.GA4062@mit.edu> Mail-Followup-To: "Theodore Y. Ts'o" , Bernd Edlinger , Arnd Bergmann , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" References: <20190216182355.GE23000@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-EOPAttributedMessage: 0 X-Forefront-Antispam-Report: CIP:18.9.28.11;IPV:CAL;SCL:-1;CTRY:US;EFV:NLI;SFV:NSPM;SFS:(10019020)(346002)(39860400002)(396003)(376002)(136003)(2980300002)(199004)(189003)(14444005)(36756003)(446003)(316002)(33656002)(106466001)(97756001)(486006)(26005)(478600001)(8936002)(6246003)(46406003)(6266002)(42186006)(16586007)(103686004)(50466002)(2906002)(75432002)(8676002)(6916009)(36906005)(106002)(54906003)(93886005)(786003)(58126008)(47776003)(53546011)(23726003)(229853002)(86362001)(1076003)(356004)(11346002)(4326008)(476003)(305945005)(126002)(336012)(246002)(52956003)(88552002)(90966002)(26826003)(2616005)(186003)(76176011)(5660300002)(41600400003)(18370500001)(42866002);DIR:OUT;SFP:1102;SCL:1;SRVR:BYAPR01MB4853;H:outgoing.mit.edu;FPR:;SPF:Pass;LANG:en;PTR:outgoing-auth-1.mit.edu;A:1;MX:1; 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Please take a look and let me know what you think. There are some other auxiliary things that your patch is trying to do where I'm not sure what you're trying to doing and I'm not at all sure it's correct. Those things should really get separated out as a separate patches. > Another minor tweak this patch makes, is when the primary > CRNG is periodically reseeded, we reserve twice the amount > of read_wakeup_threshold for fairness reasons, to keep > /dev/random readable when it is not accessed by user mode. I'm not sure what you're trying to do/fix here. - Ted >From 9275727af22bc08958bad45d604038aa8e9b6766 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Wed, 20 Feb 2019 16:06:38 -0500 Subject: [PATCH] random: only read from /dev/random after its pool has received 128 bits Immediately after boot, we allow reads from /dev/random before its entropy pool has been fully initialized. Fix this so that we don't allow this until the blocking pool has received 128 bits. We do this by repurposing the initialized flag in the entropy pool struct, and use the initialized flag in the blocking pool to indicate whether it is safe to pull from the blocking pool. To do this, we needed to rework when we decide to push entropy from the input pool to the blocking pool, since the initialized flag for the input pool was used for this purpose. To simplify things, we no longer use the initialized flag for that purpose, nor do we use the entropy_total field any more. Signed-off-by: Theodore Ts'o --- drivers/char/random.c | 44 +++++++++++++++++------------------ include/trace/events/random.h | 13 ++++------- 2 files changed, 27 insertions(+), 30 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 47ac7cd20fb1..e247c45b2772 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -470,7 +470,6 @@ struct entropy_store { unsigned short add_ptr; unsigned short input_rotate; int entropy_count; - int entropy_total; unsigned int initialized:1; unsigned int last_data_init:1; __u8 last_data[EXTRACT_SIZE]; @@ -643,7 +642,7 @@ static void process_random_ready_list(void) */ static void credit_entropy_bits(struct entropy_store *r, int nbits) { - int entropy_count, orig; + int entropy_count, orig, has_initialized = 0; const int pool_size = r->poolinfo->poolfracbits; int nfrac = nbits << ENTROPY_SHIFT; @@ -698,23 +697,25 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits) entropy_count = 0; } else if (entropy_count > pool_size) entropy_count = pool_size; + if ((r == &blocking_pool) && !r->initialized && + (entropy_count >> ENTROPY_SHIFT) > 128) + has_initialized = 1; if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; - r->entropy_total += nbits; - if (!r->initialized && r->entropy_total > 128) { + if (has_initialized) r->initialized = 1; - r->entropy_total = 0; - } trace_credit_entropy_bits(r->name, nbits, - entropy_count >> ENTROPY_SHIFT, - r->entropy_total, _RET_IP_); + entropy_count >> ENTROPY_SHIFT, _RET_IP_); if (r == &input_pool) { int entropy_bits = entropy_count >> ENTROPY_SHIFT; + struct entropy_store *other = &blocking_pool; - if (crng_init < 2 && entropy_bits >= 128) { + if (crng_init < 2) { + if (entropy_bits < 128) + return; crng_reseed(&primary_crng, r); entropy_bits = r->entropy_count >> ENTROPY_SHIFT; } @@ -725,20 +726,14 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits) wake_up_interruptible(&random_read_wait); kill_fasync(&fasync, SIGIO, POLL_IN); } - /* If the input pool is getting full, send some - * entropy to the blocking pool until it is 75% full. + /* If the input pool is getting full, and the blocking + * pool has room, send some entropy to the blocking + * pool. */ - if (entropy_bits > random_write_wakeup_bits && - r->initialized && - r->entropy_total >= 2*random_read_wakeup_bits) { - struct entropy_store *other = &blocking_pool; - - if (other->entropy_count <= - 3 * other->poolinfo->poolfracbits / 4) { - schedule_work(&other->push_work); - r->entropy_total = 0; - } - } + if (!work_pending(&other->push_work) && + (ENTROPY_BITS(r) > 6 * r->poolinfo->poolbytes) && + (ENTROPY_BITS(other) <= 6 * other->poolinfo->poolbytes)) + schedule_work(&other->push_work); } } @@ -1553,6 +1548,11 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, int large_request = (nbytes > 256); trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_); + if (!r->initialized && r->pull) { + xfer_secondary_pool(r, ENTROPY_BITS(r->pull)/8); + if (!r->initialized) + return 0; + } xfer_secondary_pool(r, nbytes); nbytes = account(r, nbytes, 0, 0); diff --git a/include/trace/events/random.h b/include/trace/events/random.h index 0560dfc33f1c..32c10a515e2d 100644 --- a/include/trace/events/random.h +++ b/include/trace/events/random.h @@ -62,15 +62,14 @@ DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes_nolock, TRACE_EVENT(credit_entropy_bits, TP_PROTO(const char *pool_name, int bits, int entropy_count, - int entropy_total, unsigned long IP), + unsigned long IP), - TP_ARGS(pool_name, bits, entropy_count, entropy_total, IP), + TP_ARGS(pool_name, bits, entropy_count, IP), TP_STRUCT__entry( __field( const char *, pool_name ) __field( int, bits ) __field( int, entropy_count ) - __field( int, entropy_total ) __field(unsigned long, IP ) ), @@ -78,14 +77,12 @@ TRACE_EVENT(credit_entropy_bits, __entry->pool_name = pool_name; __entry->bits = bits; __entry->entropy_count = entropy_count; - __entry->entropy_total = entropy_total; __entry->IP = IP; ), - TP_printk("%s pool: bits %d entropy_count %d entropy_total %d " - "caller %pS", __entry->pool_name, __entry->bits, - __entry->entropy_count, __entry->entropy_total, - (void *)__entry->IP) + TP_printk("%s pool: bits %d entropy_count %d caller %pS", + __entry->pool_name, __entry->bits, + __entry->entropy_count, (void *)__entry->IP) ); TRACE_EVENT(push_to_pool, -- 2.19.1