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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 A2A4CC3A5A6 for ; Wed, 28 Aug 2019 17:36:42 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7A2D42173E for ; Wed, 28 Aug 2019 17:36:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="h1cx2kVC"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="MQgzrgND" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7A2D42173E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=fgDtiNQGSDeu/VlevZnxehKVMQj+SFxGXeWucGj4lb0=; b=h1cx2kVCSS6giE ocNlLzpwvSoMjseIlXWAxdYFAygMqUMhvY6zgONSjTR6VNwyLaNIf3DAL/IoBt1cnSzixIwTm74wn 6e+MK7OP58vZrx558zA/CwJnI5cjTXzUmA4gD/bqJhtu9gkYSy4+9JUZsJYpcwuOcxkIBfj3vP/A4 rLWZ3iUJ3exFVsgPSxtjKJtmtRGGLRJK6Hg8xwhsRVc0Onj5CI8Gj/PA7Hq++lxOT8RM+/Ff5BkC1 NlL4/Y+78/JrwjP5iwb+2H7Iizrzc3LFlN/W6CnT+FytoywiY/wfmJT5Ri+/sNTK3qcWwjRgC5GsR HYkqFhgwPp1ZKve7kdYQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i31s4-0001NM-07; Wed, 28 Aug 2019 17:36:36 +0000 Received: from mail-pl1-x641.google.com ([2607:f8b0:4864:20::641]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i31ry-0001Bh-By for linux-arm-kernel@lists.infradead.org; Wed, 28 Aug 2019 17:36:31 +0000 Received: by mail-pl1-x641.google.com with SMTP id z3so289232pln.6 for ; Wed, 28 Aug 2019 10:36:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=K9Vcpkp2bypd29OVATeo9h/LJsFxpySHevcb6WIs5vE=; b=MQgzrgNDOIFtpBwi2JiR/yV2K4DVgUfbIjFMe/5LzpIFiGRCYfdycLhr2q93aC79GX KCmUYDmIGohRCQRdj6lCvrdjQZySdQ8YqlEM6MpTlCVG9tUQrGYtOO785imr0EdqY8Lj P1bf/U7PCuRnr268FcPRN94qxbb22Wu5pp6Is= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=K9Vcpkp2bypd29OVATeo9h/LJsFxpySHevcb6WIs5vE=; b=Ks9/kTqo129Zm/y5G7HrZOSWfHP1QgnXc4KwLGf5am5LAwzrM8r/9xKPtqkPUYIBcB pG9mv7RW0Fr8OYH5LFVX984sFZUDgpKeef06BiUlSRTVSoc+vccfRI/boWcxGH1ul5vO c/GEonCpX9LphCMr0gZYqHyLK3TLt/zyGe/dO9v0vVB+LePCBteOSrTZPDFcDtWzSwYV WJO1C3M6ltcUgVKURTPx0gggXnCJDolN+vLnNURbfCJLuEeyjEf77k6ga69PahlVv310 CDlvkSuhMulnJjw2+adNKFFE5FuD2G3LbDbIpJ8zOkE2wKF5gRg5kAlRUbTK0xrc1BDJ ehNQ== X-Gm-Message-State: APjAAAUPXOyD+/ZvmukJlTcoFcTF+ufHSBFDnGyG1cfD5T7R2twpZjQM Iu5k4CGPaYx9WDk05Q/HPzVXKg== X-Google-Smtp-Source: APXvYqz9ae0cu+VdE0RNiwT4vlyIjt8eKlcChNjdACQB6lRil6fPEaexFwAdxBX5UoHB3qRxLLY+Bg== X-Received: by 2002:a17:902:a50b:: with SMTP id s11mr5686098plq.44.1567013789568; Wed, 28 Aug 2019 10:36:29 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id w207sm3831691pff.93.2019.08.28.10.36.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Aug 2019 10:36:24 -0700 (PDT) Date: Sat, 24 Aug 2019 12:04:01 -0700 From: Kees Cook To: Stephen Boyd Subject: Re: [PATCH v9 2/3] fdt: add support for rng-seed Message-ID: <201908241203.92CC0BE8@keescook> References: <20190822071522.143986-1-hsinyi@chromium.org> <20190822071522.143986-3-hsinyi@chromium.org> <5d5ed368.1c69fb81.419fc.0803@mx.google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5d5ed368.1c69fb81.419fc.0803@mx.google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190828_103630_406113_8665E2E6 X-CRM114-Status: GOOD ( 29.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kate Stewart , Peter Zijlstra , Catalin Marinas , Mukesh Ojha , Josh Poimboeuf , Grzegorz Halat , "H . Peter Anvin" , Guenter Roeck , Will Deacon , Marek Szyprowski , Rob Herring , Daniel Thompson , Anders Roxell , Yury Norov , Marc Zyngier , Russell King , Aaro Koskinen , Ingo Molnar , Viresh Kumar , Waiman Long , "Paul E . McKenney" , Wei Li , Alexey Dobriyan , Julien Thierry , Len Brown , Arnd Bergmann , Rik van Riel , Shaokun Zhang , Mike Rapoport , Borislav Petkov , Hsin-Yi Wang , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, "Theodore Y . Ts'o" , Greg Kroah-Hartman , Marcelo Tosatti , linux-kernel@vger.kernel.org, Armijn Hemel , Jiri Kosina , Mathieu Desnoyers , Andrew Morton , Tim Chen , "David S . Miller" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Aug 22, 2019 at 10:39:51AM -0700, Stephen Boyd wrote: > 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. > > > > 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. > > > > 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. > > > > 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(-) > > > > 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=on/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 to help > > + increase initial device randomness. Assume the entropy provided is > > + trustworthy, it would be regarded as true hardware RNGs and update 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 entropy. > > 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. Otherwise > > + * 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 Can this please be a boot param (with the default controlled by the CONFIG)? See how CONFIG_RANDOM_TRUST_CPU is wired up... -Kees > > + 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); > > > +} > > +EXPORT_SYMBOL_GPL(add_bootloader_randomness); > > \ No newline at end of file -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel