From patchwork Thu Jun 23 19:00:14 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 12893114 X-Patchwork-Delegate: herbert@gondor.apana.org.au 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 9AEE2C433EF for ; Thu, 23 Jun 2022 19:30:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230440AbiFWTaI (ORCPT ); Thu, 23 Jun 2022 15:30:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230404AbiFWT3r (ORCPT ); Thu, 23 Jun 2022 15:29:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AAF0192165; Thu, 23 Jun 2022 12:00:48 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 426066204E; Thu, 23 Jun 2022 19:00:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D8957C385A5; Thu, 23 Jun 2022 19:00:46 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="DKaP5cLV" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1656010844; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uHbpMQwSks9DdyosMLJPVgMFE8w2HV6p9LXgCU/ez2I=; b=DKaP5cLVMGerAWGQhWujF+XFk6oZj6WHtrY3Hfo8wP+FmWzVDnA1S4nxfthTvFWif4rl5h dJR4scinnoQ9L8wsrLSUo/QOngPG95RKlEYYU5RGU3pO1A1HpgEMXs9K36oakGK29RxspX c5aMjPZt8nhHdMSq9an4G5qzb51KF4E= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id dac9ca19 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Thu, 23 Jun 2022 19:00:44 +0000 (UTC) From: "Jason A. Donenfeld" To: Eric Biggers , LKML , Thomas Gleixner , Linux Crypto Mailing List Cc: "Jason A. Donenfeld" , stable@vger.kernel.org Subject: [PATCH v3] timekeeping: contribute wall clock to rng on time change Date: Thu, 23 Jun 2022 21:00:14 +0200 Message-Id: <20220623190014.1355583-1-Jason@zx2c4.com> In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org The rng's random_init() function contributes the real time to the rng at boot time, so that events can at least start in relation to something particular in the real world. But this clock might not yet be set that point in boot, so nothing is contributed. In addition, the relation between minor clock changes from, say, NTP, and the cycle counter is potentially useful entropic data. This commit addresses this by mixing in a time stamp on calls to settimeofday and adjtimex. No entropy is credited in doing so, so it doesn't make initialization faster, but it is still useful input to have. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld --- kernel/time/timekeeping.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 8e4b3c32fcf9..49ee8ef16544 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -23,6 +23,7 @@ #include #include #include +#include #include "tick-internal.h" #include "ntp_internal.h" @@ -1343,8 +1344,10 @@ int do_settimeofday64(const struct timespec64 *ts) /* Signal hrtimers about time change */ clock_was_set(CLOCK_SET_WALL); - if (!ret) + if (!ret) { audit_tk_injoffset(ts_delta); + add_device_randomness(&ts, sizeof(ts)); + } return ret; } @@ -2430,6 +2433,7 @@ int do_adjtimex(struct __kernel_timex *txc) ret = timekeeping_validate_timex(txc); if (ret) return ret; + add_device_randomness(txc, sizeof(*txc)); if (txc->modes & ADJ_SETOFFSET) { struct timespec64 delta; @@ -2447,6 +2451,7 @@ int do_adjtimex(struct __kernel_timex *txc) audit_ntp_init(&ad); ktime_get_real_ts64(&ts); + add_device_randomness(&ts, sizeof(ts)); raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&tk_core.seq);