From patchwork Tue Sep 27 16:07:42 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: 12990997 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A4EABC6FA86 for ; Tue, 27 Sep 2022 17:13:28 +0000 (UTC) Received: from localhost ([::1]:37490 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1odE99-0002wg-Ju for qemu-devel@archiver.kernel.org; Tue, 27 Sep 2022 13:13:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51926) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1odD7s-0002s0-U2; Tue, 27 Sep 2022 12:08:06 -0400 Received: from ams.source.kernel.org ([145.40.68.75]:58202) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1odD7p-000312-Up; Tue, 27 Sep 2022 12:08:04 -0400 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 ams.source.kernel.org (Postfix) with ESMTPS id 836CFB819D6; Tue, 27 Sep 2022 16:07:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63F6BC43470; Tue, 27 Sep 2022 16:07:47 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="PbQ6ZR6O" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1664294865; 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; bh=AYXNAR/40rFqzW2vG8sAKK8tE30s5Xu8rSZ73wgd/NM=; b=PbQ6ZR6OOtkJdY5I04dKvl2ylvMYLb6x7dSj2Op4mFPUnTLm0o7pm50PEJTkNOcNffBS47 O4IHQBVszU70FJ3bEWM+oLtZQyeCoW3p2osmK1sDh4m7glFMjHcrq//Jgt3XY1+PdA1Cjo P8vIdnDPx/OdQen1B/9WfzUlGCVOfMQ= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 2a1565b1 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Tue, 27 Sep 2022 16:07:45 +0000 (UTC) From: "Jason A. Donenfeld" To: qemu-devel@nongnu.org, peter.maydell@linaro.org, qemu-arm@nongnu.org Cc: "Jason A. Donenfeld" Subject: [PATCH] arm: re-randomize rng-seed on reboot Date: Tue, 27 Sep 2022 18:07:42 +0200 Message-Id: <20220927160742.1773167-1-Jason@zx2c4.com> MIME-Version: 1.0 Received-SPF: pass client-ip=145.40.68.75; envelope-from=SRS0=O2ZR=Z6=zx2c4.com=Jason@kernel.org; helo=ams.source.kernel.org X-Spam_score_int: -67 X-Spam_score: -6.8 X-Spam_bar: ------ X-Spam_report: (-6.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" When the system reboots, the rng-seed that the FDT has should be re-randomized, so that the new boot gets a new seed. Since the FDT is in the ROM region at this point, we add a hook right after the ROM has been added, so that we have a pointer to that copy of the FDT. When the reboot happens, we then look for RNG seeds and replace their contents with new random data. Cc: Peter Maydell Signed-off-by: Jason A. Donenfeld --- hw/arm/boot.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/hw/arm/boot.c b/hw/arm/boot.c index ada2717f76..2836db4abb 100644 --- a/hw/arm/boot.c +++ b/hw/arm/boot.c @@ -25,6 +25,7 @@ #include "qemu/config-file.h" #include "qemu/option.h" #include "qemu/units.h" +#include "qemu/guest-random.h" /* Kernel boot protocol is specified in the kernel docs * Documentation/arm/Booting and Documentation/arm64/booting.txt @@ -529,6 +530,26 @@ static void fdt_add_psci_node(void *fdt) qemu_fdt_setprop_cell(fdt, "/psci", "migrate", migrate_fn); } +static void rerandomize_fdt_seeds(void *fdt) +{ + int noffset, poffset, len; + const char *name; + uint8_t *data; + + for (noffset = fdt_next_node(fdt, 0, NULL); + noffset >= 0; + noffset = fdt_next_node(fdt, noffset, NULL)) { + for (poffset = fdt_first_property_offset(fdt, noffset); + poffset >= 0; + poffset = fdt_next_property_offset(fdt, poffset)) { + data = (uint8_t *)fdt_getprop_by_offset(fdt, poffset, &name, &len); + if (!data || strcmp(name, "rng-seed")) + continue; + qemu_guest_getrandom_nofail(data, len); + } + } +} + int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo, hwaddr addr_limit, AddressSpace *as, MachineState *ms) { @@ -683,6 +704,7 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo, * the DTB is copied again upon reset, even if addr points into RAM. */ rom_add_blob_fixed_as("dtb", fdt, size, addr, as); + qemu_register_reset(rerandomize_fdt_seeds, rom_ptr_for_as(as, addr, size)); g_free(fdt);