From patchwork Thu Jun 23 19:12:49 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: 12893116 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 E92E0C433EF for ; Thu, 23 Jun 2022 19:33:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231523AbiFWTdU (ORCPT ); Thu, 23 Jun 2022 15:33:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232299AbiFWTcz (ORCPT ); Thu, 23 Jun 2022 15:32:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55DE011801; Thu, 23 Jun 2022 12:12:56 -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 dfw.source.kernel.org (Postfix) with ESMTPS id DBED360E9A; Thu, 23 Jun 2022 19:12:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B87CC341C0; Thu, 23 Jun 2022 19:12:54 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="nRsLdUeJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1656011572; 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=wn91beVIpJqcjS6OkGcXvZ64/XKHTsjaRxnq+PVXs/8=; b=nRsLdUeJuSmN2lu7ljc7LjGkyDyMhD94yTRJWdL2fyFvtfxvHNgiAsP/LINeQvHXp+by3B dBDNcrzybW4w6BQDyQhVBulH3jPXk+6k2v3TtkfKcqIaNRQxEmyP51EQmtTtPAL7GzmW+u qBbRtrJH+AfF87cIQvLhGPacF48mRAg= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 67e2eba3 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Thu, 23 Jun 2022 19:12:52 +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 v4] timekeeping: contribute wall clock to rng on time change Date: Thu, 23 Jun 2022 21:12:49 +0200 Message-Id: <20220623191249.1357363-1-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 Reviewed-by: Eric Biggers --- 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 #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);