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[2620:137:e000::1:20]) by mx.google.com with ESMTP id dn17-20020a17090794d100b007ae1052554esi5067346ejc.898.2022.11.04.04.39.48; Fri, 04 Nov 2022 04:40:18 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=bJqRPoj9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230205AbiKDLbV (ORCPT + 99 others); Fri, 4 Nov 2022 07:31:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229637AbiKDLbT (ORCPT ); Fri, 4 Nov 2022 07:31:19 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 810A625C7B for ; Fri, 4 Nov 2022 04:30:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667561423; 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=uJy9Oiy5cpKmClijTkDe6KXjFE6VRuxm2Fp2gVJ4PwQ=; b=bJqRPoj97lfwAH3FnNZ+rWUXDiD/3fFA1GuzCGLaFnFIsTAy1aXvMHf4D9eRkI7ReTxqDy q/tyAvq2fEdXvBV1KDfk0AtQLc3pzh2bHMNh1M6TvCck4qXal14g18aMRh26nWpK6gzqzO pTZWKFXiRDJT4/BpuQVFNh6P7FR2WUQ= 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_128_GCM_SHA256) id us-mta-623-yre60jxfOqymj_ahPo6OAA-1; Fri, 04 Nov 2022 07:30:20 -0400 X-MC-Unique: yre60jxfOqymj_ahPo6OAA-1 Received: by mail-pl1-f200.google.com with SMTP id x18-20020a170902ec9200b001869f20da7eso3425537plg.10 for ; Fri, 04 Nov 2022 04:30:20 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=uJy9Oiy5cpKmClijTkDe6KXjFE6VRuxm2Fp2gVJ4PwQ=; b=jSvhnX/ti1b3fC24Zs33lEVAEDAcNWa1cMzYUrl6dnBMPO8pse+kf7iAx/Lf2C3zXt 41SqcxViRrRKzJp5sq/qz/cFeZiGGzdT4/1qdcrjcKXVDM9F3PPBgsqfWD+DzcNk8lCD zcLJ0f5p7axhVxR6aqzW10oE0w6iAcjtpmmRdYIszBmc17Wue/AsFfMYFSvBYgFjiwYe ryyW68dHTbBbFQJ2JvteJfcKwPZs6lpsmI5VG86OuNvjaKqZ6jGjvl26mqBZ6wN+hE/1 a6izrOoJ+wSqJepGmL8mM8D5dXYAJxjfkullIa9cgYLhD7ppYfr1qxlq1kOTsaFzePNs rX4w== X-Gm-Message-State: ACrzQf1Mlz6A2OCHZmhf1RpA3xESKkXZQ9rVC3B153yz4glCd97FquVu 2bQ5yrqGD1BFfp3pBcDFWP4Rw1CaD1dXn2AkNnJ7TXYBDH5DKgerZiU3ibef8qBwKSeuBVP/tSX Bh3lfHyl7/ydv9OHpNjchMlMl X-Received: by 2002:a17:902:aa46:b0:186:e220:11d4 with SMTP id c6-20020a170902aa4600b00186e22011d4mr35254830plr.163.1667561419298; Fri, 04 Nov 2022 04:30:19 -0700 (PDT) X-Received: by 2002:a17:902:aa46:b0:186:e220:11d4 with SMTP id c6-20020a170902aa4600b00186e22011d4mr35254808plr.163.1667561419017; Fri, 04 Nov 2022 04:30:19 -0700 (PDT) Received: from localhost ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id f11-20020a170902684b00b0018855a22ccfsm2430982pln.91.2022.11.04.04.30.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Nov 2022 04:30:18 -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, Eric Biederman Subject: [RFC v2 1/5] kexec_file: allow to place kexec_buf randomly Date: Fri, 4 Nov 2022 19:29:56 +0800 Message-Id: <20221104113000.487098-2-coxu@redhat.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221104113000.487098-1-coxu@redhat.com> References: <20221104113000.487098-1-coxu@redhat.com> MIME-Version: 1.0 X-Spam-Status: No, score=-3.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1748565511466534819?= X-GMAIL-MSGID: =?utf-8?q?1748565511466534819?= 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 13e6c4b58f07..c0edb64bf6c4 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -171,6 +171,7 @@ 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; @@ -182,6 +183,7 @@ struct kexec_buf { unsigned long buf_min; unsigned long buf_max; bool top_down; + bool random; }; int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf); diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index a7b411c22f19..ed9fcc369312 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" @@ -412,6 +413,16 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, return ret; } +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 = 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) { @@ -420,6 +431,8 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end, temp_end = min(end, kbuf->buf_max); temp_start = temp_end - kbuf->memsz; + if (kbuf->random) + temp_start = kexec_random_start(temp_start, temp_end); do { /* align down start */ @@ -457,6 +470,8 @@ static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, unsigned long temp_start, temp_end; temp_start = max(start, kbuf->buf_min); + if (kbuf->random) + temp_start = kexec_random_start(temp_start, end); do { temp_start = ALIGN(temp_start, kbuf->buf_align);