From nobody Sun Feb 8 17:37:30 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 EAA24C77B7A for ; Thu, 1 Jun 2023 07:25:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231189AbjFAHZt (ORCPT ); Thu, 1 Jun 2023 03:25:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231783AbjFAHZq (ORCPT ); Thu, 1 Jun 2023 03:25:46 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24179184 for ; Thu, 1 Jun 2023 00:24:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685604294; 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=AV8aUvr4ixGLZyIesmYQLsbGSBUr0/xlhliel/t7Lh8=; b=K9c8Zm6BwoJeB31EY74w3URzxj6zFDliZuWsim08otfp6MIJWyaGgiNGjp+dWv7TrLJPDR dCxy2nX/fGlCsZM8pVZ06mYTalwn9vVDEXI4R9NwXk1xVsu6CkX+akptNNzdu6+aVAeaB1 ti+KiOoPUMVY8pY0xSsycA2cjD6qCtQ= Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-486-oVvbfSETNHap7HRxXCrzfQ-1; Thu, 01 Jun 2023 03:24:53 -0400 X-MC-Unique: oVvbfSETNHap7HRxXCrzfQ-1 Received: by mail-pl1-f200.google.com with SMTP id d9443c01a7336-1b031a8fbe5so1757505ad.2 for ; Thu, 01 Jun 2023 00:24:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685604292; x=1688196292; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=AV8aUvr4ixGLZyIesmYQLsbGSBUr0/xlhliel/t7Lh8=; b=TYFVh+p2kDOM5KzD6LophXd19IFL0SDunKEiMcbETcJNVO2iPgF290I9FfT/lBYs4K q/kiQl3540xSgqeWiRp37jZTAxgdJTK3VSJf8LcQiQBbjxhiwlO2Vd0x84mcl2rsMixc 61p9R9NPtDR4Ht3TPtkqzP5Brkd8Udiw48+9etlBVkJNF+DI2vI+YiS+px6G9I5kasQN xrLj6Q7PJh8HGjyLzpw+6GTTmA9rpx28PJQRtG2AA9A2rcBmIYhrnUN0IHDJ3ez9QUxV 8Q/855cb8sRHbgRoljaXWxNpLAdFaN2QDVxFwTb3ddeZkFOZPQ4tT7eIf09gHiOYAhgx kMTg== X-Gm-Message-State: AC+VfDzi9gnLquowFEm/HF/QrL2nKD3eP5MaN1jTuBpqSFafmy+rJxc3 XyD+JiZY2/mSdtwPCkXhbtcr1YCxPX4Yvj7qExMYoxB2SAhkoNQ0lQuk40rn/3m/lz1C6lGa5hb dOU9fOyua3JkBTKjtkso5e3oP X-Received: by 2002:a17:902:e811:b0:1b0:5e97:ee2e with SMTP id u17-20020a170902e81100b001b05e97ee2emr6960535plg.19.1685604292000; Thu, 01 Jun 2023 00:24:52 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ662P0lLrFIg86H16E966109yZnfDIKygWQtWOgjwFAIugqodl1XMDNcj6+cm1VNgP+uGfilg== X-Received: by 2002:a17:902:e811:b0:1b0:5e97:ee2e with SMTP id u17-20020a170902e81100b001b05e97ee2emr6960516plg.19.1685604291629; Thu, 01 Jun 2023 00:24:51 -0700 (PDT) Received: from localhost ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id z15-20020a170903018f00b00199203a4fa3sm2666890plg.203.2023.06.01.00.24.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Jun 2023 00:24:51 -0700 (PDT) From: Coiby Xu To: kexec@lists.infradead.org Cc: Milan Broz , Thomas Staudt , Kairui Song , dm-devel@redhat.com, Jan Pazdziora , Pingfan Liu , Baoquan He , Dave Young , linux-kernel@vger.kernel.org, x86@kernel.org, Dave Hansen , Vitaly Kuznetsov , Eric Biederman Subject: [PATCH 1/5] kexec_file: allow to place kexec_buf randomly Date: Thu, 1 Jun 2023 15:24:40 +0800 Message-Id: <20230601072444.2033855-2-coxu@redhat.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230601072444.2033855-1-coxu@redhat.com> References: <20230601072444.2033855-1-coxu@redhat.com> 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" Currently, kexec_buf is placed in order which means for the same machine, the info in the kexec_buf is always located at the same position each time the machine is booted. This may cause a risk for sensitive information like LUKS volume key. Now struct kexec_buf has a new field random which indicates it's supposed to be placed in a random position. Suggested-by: Jan Pazdziora Signed-off-by: Coiby Xu --- include/linux/kexec.h | 2 ++ kernel/kexec_file.c | 15 +++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 22b5cd24f581..5b2440444112 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -172,6 +172,7 @@ int kexec_image_post_load_cleanup_default(struct kimage= *image); * @buf_min: The buffer can't be placed below this address. * @buf_max: The buffer can't be placed above this address. * @top_down: Allocate from top of memory. + * @random: Place the buffer at a random position. */ struct kexec_buf { struct kimage *image; @@ -183,6 +184,7 @@ struct kexec_buf { unsigned long buf_min; unsigned long buf_max; bool top_down; + bool random; }; =20 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf); diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index f989f5f1933b..5dbfc119eb6a 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include "kexec_internal.h" @@ -419,6 +420,16 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, = initrd_fd, return ret; } =20 +static unsigned long kexec_random_start(unsigned long start, unsigned long= end) +{ + unsigned long temp_start; + unsigned short i; + + get_random_bytes(&i, sizeof(unsigned short)); + temp_start =3D start + (end - start) / USHRT_MAX * i; + return temp_start; +} + static int locate_mem_hole_top_down(unsigned long start, unsigned long end, struct kexec_buf *kbuf) { @@ -427,6 +438,8 @@ static int locate_mem_hole_top_down(unsigned long start= , unsigned long end, =20 temp_end =3D min(end, kbuf->buf_max); temp_start =3D temp_end - kbuf->memsz; + if (kbuf->random) + temp_start =3D kexec_random_start(temp_start, temp_end); =20 do { /* align down start */ @@ -464,6 +477,8 @@ static int locate_mem_hole_bottom_up(unsigned long star= t, unsigned long end, unsigned long temp_start, temp_end; =20 temp_start =3D max(start, kbuf->buf_min); + if (kbuf->random) + temp_start =3D kexec_random_start(temp_start, end); =20 do { temp_start =3D ALIGN(temp_start, kbuf->buf_align); --=20 2.40.1