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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B7AAAC3A5A1 for ; Thu, 22 Aug 2019 17:39:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 827DC20856 for ; Thu, 22 Aug 2019 17:39:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="MQnTqO/P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392762AbfHVRj5 (ORCPT ); Thu, 22 Aug 2019 13:39:57 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:40129 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388253AbfHVRjz (ORCPT ); Thu, 22 Aug 2019 13:39:55 -0400 Received: by mail-pf1-f193.google.com with SMTP id w16so4423600pfn.7 for ; Thu, 22 Aug 2019 10:39:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=message-id:mime-version:content-transfer-encoding:in-reply-to :references:cc:subject:to:from:user-agent:date; bh=/SKCVH1cP34M+EOCz1gwJK67tID4N48JyS6a43d2kiA=; b=MQnTqO/P5HLNo2wRx+4ovpS8Tl5NhKqP4yAwsm75fZBx/0HuNqZY6WQPFieLjqgL8Y y+7TnZh/GvrBXFZcy/IiflyoVVy1xtikmPc0Pxx8dgdn6LdnEUYZatahrFKCrA33+kgW K/BJVdJ8pwOuIsUYEHDW2kDhp2Dhiiku5TfCA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:mime-version :content-transfer-encoding:in-reply-to:references:cc:subject:to:from :user-agent:date; bh=/SKCVH1cP34M+EOCz1gwJK67tID4N48JyS6a43d2kiA=; b=TSgzS+NNvgePl/sHPIU/vQ+xo+qw3f4DHXLpq8ghp+gcPFsaPc2olGfo7aejIaroA+ OtfQCMUVhaLlK1Ab1vOE6u5h5QVnotNnWkCwi590cwQ+xxdIknhNFefblZRCnhnT04ch VbMnnCr/PEFEditQOublWxjucRsV6EckFi+NLF2vmUOsKXtlPYEAoglaPQlQsz10nWyi pBO+GXdnAAFERt07DyQ+jN9SUMFsDCD579Z8pRaP/PuQqAuuf8QRhtp0sbtA6pvtdMJh ycIx9ddrdGypyXtzSL9X7ibwek++WmhyX+r23PcPsBcp8YVH2PrBvbC3YJ7HscuRJnII z9pw== X-Gm-Message-State: APjAAAWrlsr5jJmbYlBlnzuXT95x+5TyMNHcDkh7KjxXWaHsH+iH/6mt thouPVFGrNYyYGbklEovul7tQA== X-Google-Smtp-Source: APXvYqyjCv+RfuDuHbk6B4dF6CbusPM8neaAWPdHZqiIQnf8Kr9Fc7sVfGImRfS+T0/lf0D9ZKqxww== X-Received: by 2002:a63:1918:: with SMTP id z24mr358999pgl.94.1566495594017; Thu, 22 Aug 2019 10:39:54 -0700 (PDT) Received: from chromium.org ([2620:15c:202:1:fa53:7765:582b:82b9]) by smtp.gmail.com with ESMTPSA id c2sm153607pjs.13.2019.08.22.10.39.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2019 10:39:52 -0700 (PDT) Message-ID: <5d5ed368.1c69fb81.419fc.0803@mx.google.com> Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable In-Reply-To: <20190822071522.143986-3-hsinyi@chromium.org> References: <20190822071522.143986-1-hsinyi@chromium.org> <20190822071522.143986-3-hsinyi@chromium.org> Cc: Russell King , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , "Paul E . McKenney" , Kate Stewart , "David S . Miller" , Viresh Kumar , Marek Szyprowski , Arnd Bergmann , Marc Zyngier , Julien Thierry , Greg Kroah-Hartman , Wei Li , Anders Roxell , Rob Herring , Aaro Koskinen , Daniel Thompson , Tim Chen , Rik van Riel , Waiman Long , Marcelo Tosatti , Peter Zijlstra , Armijn Hemel , Grzegorz Halat , Len Brown , Shaokun Zhang , Mike Rapoport , Kees Cook , Guenter Roeck , Andrew Morton , Mathieu Desnoyers , Alexey Dobriyan , Yury Norov , Josh Poimboeuf , Jiri Kosina , Mukesh Ojha , linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 2/3] fdt: add support for rng-seed To: "Theodore Y . Ts'o" , Hsin-Yi Wang , linux-arm-kernel@lists.infradead.org From: Stephen Boyd User-Agent: alot/0.8.1 Date: Thu, 22 Aug 2019 10:39:51 -0700 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Hsin-Yi Wang (2019-08-22 00:15:22) > Introducing a chosen node, rng-seed, which is an entropy that can be > passed to kernel called very early to increase initial device > randomness. Bootloader should provide this entropy and the value is > read from /chosen/rng-seed in DT. >=20 > Obtain of_fdt_crc32 for CRC check after early_init_dt_scan_nodes(), > since early_init_dt_scan_chosen() would modify fdt to erase rng-seed. >=20 > Add a new interface add_bootloader_randomness() for rng-seed use case. > Depends on whether the seed is trustworthy, rng seed would be passed to > add_hwgenerator_randomness(). Otherwise it would be passed to > add_device_randomness(). Decision is controlled by kernel config > RANDOM_TRUST_BOOTLOADER. >=20 > Signed-off-by: Hsin-Yi Wang > Reviewed-by: Stephen Boyd > Reviewed-by: Rob Herring > --- > Change from v8: > * Add a new interface add_bootloader_randomness > * Add a new kernel config > --- > drivers/char/Kconfig | 10 ++++++++++ > drivers/char/random.c | 15 +++++++++++++++ > drivers/of/fdt.c | 14 ++++++++++++-- > include/linux/random.h | 1 + > 4 files changed, 38 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig > index 96156c729a31..5974a5906fd0 100644 > --- a/drivers/char/Kconfig > +++ b/drivers/char/Kconfig > @@ -551,3 +551,13 @@ config RANDOM_TRUST_CPU > has not installed a hidden back door to compromise the CPU's > random number generation facilities. This can also be configured > at boot with "random.trust_cpu=3Don/off". > + > +config RANDOM_TRUST_BOOTLOADER > + bool "Trust the bootloader to initialize Linux's CRNG" > + default n You can drop the default. > + help > + Bootloader could provide rng-seed set in /chosen/rng-seed in DT t= o help > + increase initial device randomness. Assume the entropy provided is > + trustworthy, it would be regarded as true hardware RNGs and updat= e the > + entropy estimate. Otherwise it would be regarded as device input = that > + could help mix the entropy pool, but won't be added to actual ent= ropy. Maybe reword this to something like: Some bootloaders can provide entropy to increase the kernel's initial device randomness. Say Y here to assume the entropy provided by the booloader is trustworthy so it will be added to the kernel's entropy pool. Otherwise, say N here so it will be regarded as device input that only mixes the entropy pool. > \ No newline at end of file > diff --git a/drivers/char/random.c b/drivers/char/random.c > index 5d5ea4ce1442..29d3ff3de1e1 100644 > --- a/drivers/char/random.c > +++ b/drivers/char/random.c > @@ -2445,3 +2445,18 @@ void add_hwgenerator_randomness(const char *buffer= , size_t count, > credit_entropy_bits(poolp, entropy); > } > EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); > + > +/* Handle random seed passed by bootloader. > + * If the seed is trustworthy, it would be regarded as hardware RNGs. Ot= herwise > + * it would be regarded as device data. > + * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. > + */ > +void add_bootloader_randomness(const void *buf, unsigned int size) > +{ > +#ifdef CONFIG_RANDOM_TRUST_BOOTLOADER > + add_hwgenerator_randomness(buf, size, size * 8); > +#else > + add_device_randomness(buf, size); > +#endif Maybe use if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) add_hwgenerator_randomness(buf, size, size * 8); else add_device_randomness(buf, size); =09 > +} > +EXPORT_SYMBOL_GPL(add_bootloader_randomness); > \ No newline at end of file