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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 0926CC02196 for ; Fri, 7 Feb 2025 08:09:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:content-type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=SAfH8CaZcdNlX6bGu3s15qKUzaN5EneIuMEhM/Mtjyc=; b=Gye3JBGsYYBKhJ4C0QKJCwb1fC Ci8nr5hqartA7WosCbzXVpGDXXPZ8OPv8NQ6XpQ2Q+2bm1uzolWtD2kxIQEPTgvQfdHDDPotsYZgg OHmcO4+KLJVGHQOkurtmMUUaZblwH7HQBCBIOpUrSAkAxmry+kWposb3LjrX/Ck5psRFdDlnbQ5M8 rmchbAkx3c2tZiTPphdl6+tfWZj9anA2LcYtrgpCgKOzOXc82IOzH+xunpjWbFENq5u/nFR/MJDft 3YOF8wIwnt4CjztF2QP8vUk0LJX6Ffwbvczn7fu/B+338cMv3cdCoaGQxGvn1sjIn83CoAu8qp8xQ Gu/YMDXQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tgJQw-00000008l8p-33IW; Fri, 07 Feb 2025 08:09:54 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tgJPZ-00000008kat-46xA for kexec@lists.infradead.org; Fri, 07 Feb 2025 08:08:31 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738915709; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SAfH8CaZcdNlX6bGu3s15qKUzaN5EneIuMEhM/Mtjyc=; b=cEgYv4tuh7Z6TFtX1QMiUlLRETomrYRuSyXGdk8Z9lIBmb/1JyGQN/1Cc2egPjJ3RgD8sQ OdX9BA6AgwEJs7elIcjbDgOkDCVJ/BEVE49CKSAzWM6zlzWJooPptb2/b9FV55e5Bs9Exw klgDXpeQxtyJgPGfyV0X/P3OWY2C1WE= Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-586-uD7PR90tMe6IHu1FMBnxQA-1; Fri, 07 Feb 2025 03:08:28 -0500 X-MC-Unique: uD7PR90tMe6IHu1FMBnxQA-1 X-Mimecast-MFC-AGG-ID: uD7PR90tMe6IHu1FMBnxQA Received: by mail-pl1-f198.google.com with SMTP id d9443c01a7336-21f444af89fso18545175ad.1 for ; Fri, 07 Feb 2025 00:08:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738915706; x=1739520506; 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=SAfH8CaZcdNlX6bGu3s15qKUzaN5EneIuMEhM/Mtjyc=; b=ifarPe2yefIYMFHIkutQKOD6Ypb5aC2VQQ7qHsllNq+G5zdjT1ZXNld0cwR/FZPr5n 2xO9unUaUip8h6cwHc4Q+/nP8hmCz4YLrZ2YmhGibrXnv3dFiJqIJaC5T0/jwk94R6FR aXrhhsvjWkFtkef3/APYkmnoELjTjLISlyRIdHQMIO7TSrR4zoSgCOf61NxGYChNeuBP sNxQ1Q9L1w8ea2EgLgWHh4vmdgowzqAAXAbe5JjtrpO4ubXELNT9qNam7G31zrBEIxvH vPI/SYphzAY7kBL7qLuSQsjDNVWZgFjIVRjyCB1qouRob4C3HxvCGScxJCkwfSXBQiul 4EPA== X-Gm-Message-State: AOJu0YyjohSccxVrYTT+5hdXLijXSWyHSdnB3ymTqdfizmRkED526Oo9 a1nzgyo/xFZM00lWj6unvLegyjkW9j0BMxlWWiXAFyjdOa8H7ugLjlrG4CIxUwRP4B09D2Onw3X SizMLdwobLrAdelT6NJcg5ozOptcYd7omTf0XgmfKY1dhAv7hqwSkd1m/80PKUzidLG5/11op3g L2zu7pYLG6yX+vt6RdhGhrXHJDatJ+Q7TzO2DDfnQN6A== X-Gm-Gg: ASbGncta4BddC5PPHgJVTIdb1gDIizC9QUmYmdlv3GBbmhRXYKsLwkqUIL90xMnaCHe 1Fq/LGWE2tSfZwTS4Iz1kbQU9dXaomVPR3Th1jLa9U11uckgHSzyHWN5QwUeeQ52mDsmLaEuJq/ AmoI1KSxNZtKGyIjr58Zq7sYFNYYHRB+crNQyzuRTL54lXNGHM6/XpFczxitPORi/F0a8uu3cLf 7/Kkyr9ucpVwcpBJj9rg4q+i4mYFBd0ZsiGJZNbEz7wIVWrQi3i3qtmi+zo65AOTpuLQZBa X-Received: by 2002:a17:902:ef51:b0:215:6995:1ef3 with SMTP id d9443c01a7336-21f4e6a1125mr40433775ad.3.1738915706612; Fri, 07 Feb 2025 00:08:26 -0800 (PST) X-Google-Smtp-Source: AGHT+IEPE/gqMkWPnB/djnJNY/obb5cFGvAP4LjWDnm8O0PsSmswh+uBBdXKftkoZyy8le1irXB8Pg== X-Received: by 2002:a17:902:ef51:b0:215:6995:1ef3 with SMTP id d9443c01a7336-21f4e6a1125mr40433315ad.3.1738915706122; Fri, 07 Feb 2025 00:08:26 -0800 (PST) Received: from localhost ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21f3650ce21sm24790205ad.26.2025.02.07.00.08.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Feb 2025 00:08:25 -0800 (PST) From: Coiby Xu To: kexec@lists.infradead.org Cc: Ondrej Kozina , Milan Broz , Thomas Staudt , =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Kairui Song , Pingfan Liu , Baoquan He , Dave Young , linux-kernel@vger.kernel.org, x86@kernel.org, Dave Hansen , Vitaly Kuznetsov , Jan Pazdziora , Eric Biederman Subject: [PATCH v8 1/7] kexec_file: allow to place kexec_buf randomly Date: Fri, 7 Feb 2025 16:08:09 +0800 Message-ID: <20250207080818.129165-2-coxu@redhat.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250207080818.129165-1-coxu@redhat.com> References: <20250207080818.129165-1-coxu@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: e7iNLtnAUc3MggASx-8e0ylhMXU1ueCFHXXVm3rVPws_1738915707 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250207_000830_089507_C71FB73A X-CRM114-Status: GOOD ( 15.14 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org 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. Note this feature is enabled only when CONFIG_CRASH_DUMP is enabled. So it only takes effect for kdump and won't impact kexec reboot. Suggested-by: Jan Pazdziora Signed-off-by: Coiby Xu --- include/linux/kexec.h | 30 ++++++++++++++++++++++++++++++ kernel/kexec_file.c | 3 +++ 2 files changed, 33 insertions(+) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index f0e9f8eda7a3..61269e97502a 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -25,6 +25,10 @@ extern note_buf_t __percpu *crash_notes; +#ifdef CONFIG_CRASH_DUMP +#include +#endif + #ifdef CONFIG_KEXEC_CORE #include #include @@ -171,6 +175,7 @@ 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; @@ -182,8 +187,33 @@ struct kexec_buf { unsigned long buf_min; unsigned long buf_max; bool top_down; +#ifdef CONFIG_CRASH_DUMP + bool random; +#endif }; + +#ifdef CONFIG_CRASH_DUMP +static inline void kexec_random_range_start(unsigned long start, + unsigned long end, + struct kexec_buf *kbuf, + unsigned long *temp_start) +{ + unsigned short i; + + if (kbuf->random) { + get_random_bytes(&i, sizeof(unsigned short)); + *temp_start = start + (end - start) / USHRT_MAX * i; + } +} +#else +static inline void kexec_random_range_start(unsigned long start, + unsigned long end, + struct kexec_buf *kbuf, + unsigned long *temp_start) +{} +#endif + int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf); int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, void *buf, unsigned int size, diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 3eedb8c226ad..875fe108cc83 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -445,6 +445,7 @@ 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 + 1; + kexec_random_range_start(temp_start, temp_end, kbuf, &temp_start); do { /* align down start */ @@ -483,6 +484,8 @@ static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, temp_start = max(start, kbuf->buf_min); + kexec_random_range_start(temp_start, end, kbuf, &temp_start); + do { temp_start = ALIGN(temp_start, kbuf->buf_align); temp_end = temp_start + kbuf->memsz - 1; -- 2.48.1