From nobody Sat Apr 18 05:54:56 2026 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 DEAD6C433EF for ; Sun, 17 Jul 2022 21:53:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232987AbiGQVx6 (ORCPT ); Sun, 17 Jul 2022 17:53:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232806AbiGQVx5 (ORCPT ); Sun, 17 Jul 2022 17:53:57 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A15BCC7; Sun, 17 Jul 2022 14:53:56 -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 sin.source.kernel.org (Postfix) with ESMTPS id A5E97CE112B; Sun, 17 Jul 2022 21:53:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76D43C341C0; Sun, 17 Jul 2022 21:53:52 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="iEuuU2sQ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1658094830; 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=Ny84T9MsouS8xlPpZE0UKru4/DgwDfAXAKuzjKR6LbU=; b=iEuuU2sQnrUZVRJlvE+kuRoL7HDSk5iViUpaISQ5BIpdu1qTSay3i8KbOkdmV/fx1OQWUm OhN78RveXyQBlqelblWF7O/SPPmO3KVRkFsek/Tqp53Rb/HvznkQzxnsFd6gSl1Xhy0AOo 9pVGOGGl3qI/6ATbfPbTmzW8WqrRBmc= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id cf6e9676 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Sun, 17 Jul 2022 21:53:50 +0000 (UTC) From: "Jason A. Donenfeld" To: tglx@linutronix.de, linux-kernel@vger.kernel.org Cc: "Jason A. Donenfeld" , stable@vger.kernel.org, Eric Biggers Subject: [PATCH v4 RESEND] timekeeping: contribute wall clock to rng on time change Date: Sun, 17 Jul 2022 23:53:34 +0200 Message-Id: <20220717215334.221236-1-Jason@zx2c4.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Eric Biggers Signed-off-by: Jason A. Donenfeld Reviewed-by: Thomas Gleixner --- 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..f72b9f1de178 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -23,6 +23,7 @@ #include #include #include +#include =20 #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); =20 - if (!ret) + if (!ret) { audit_tk_injoffset(ts_delta); + add_device_randomness(ts, sizeof(*ts)); + } =20 return ret; } @@ -2430,6 +2433,7 @@ int do_adjtimex(struct __kernel_timex *txc) ret =3D timekeeping_validate_timex(txc); if (ret) return ret; + add_device_randomness(txc, sizeof(*txc)); =20 if (txc->modes & ADJ_SETOFFSET) { struct timespec64 delta; @@ -2447,6 +2451,7 @@ int do_adjtimex(struct __kernel_timex *txc) audit_ntp_init(&ad); =20 ktime_get_real_ts64(&ts); + add_device_randomness(&ts, sizeof(ts)); =20 raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&tk_core.seq); --=20 2.35.1