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 814E9C25B76 for ; Sat, 8 Jun 2024 09:12:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=5YEHfJQ8/Ydz+7yuu4ukqQGPSsNnLzEunsVJlNaG088=; b=p9PoYDDPHpc1Aq Xk7jizuQReyKa51OU1I2vi13EwgZCOw6NUPFCut9qwx9fqGxTlePXFV7lHZ6esuDCNh3xA8JGge2G sFTwUKZI17uBOpEUVTTmwXfy95GVw3nZt9m5LGZkD4GvPG/RS2+TGSoYrLfZkEacQqHGB/3oPgdu9 ZfwVMttXA3xCb6znpp+Be+s/eMS//YrXCUue7PgmvGnB2FYxQKWJx1fTcVYlsVKC2OU7nJMCnJiAy IHKe4oHC0qKe+wb0bXvkU5UAAZdPzYGcTWS7n+68biDaf8KZb4o7cpv6oKl/gIgfAARZxwdmsf2x7 C5xUl3eVXeBbkZZ/cJNA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sFs7P-0000000H40W-0Qwp; Sat, 08 Jun 2024 09:12:11 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sFs7N-0000000H409-1YlY for kexec@lists.infradead.org; Sat, 08 Jun 2024 09:12:10 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id D597160C63; Sat, 8 Jun 2024 09:12:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD50BC4AF07; Sat, 8 Jun 2024 09:12:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1717837926; bh=PEWh689hlcM34NTXM0E7lxhNvTQv48Khi94eV33CHc0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UIYrlXYz8yn2sxe7g5C7C5tbPRrdbybFeelFUwfVBb+7ZJ4ZeHZQiArKJeww7KO3U LwamX1kPtQ0mnjMWBvoPoBkFJXd+J6ac7Z/FWtpHDB6007cv+smcND0TIet14cEwpa fxgoctpduTvIcVZcW1Uv+7q9/Hg9hTCWtnVwJaG8= Date: Sat, 8 Jun 2024 11:12:02 +0200 From: Greg KH To: Coiby Xu Cc: kexec@lists.infradead.org, Ondrej Kozina , Milan Broz , Thomas Staudt , Daniel P =?iso-8859-1?Q?=2E_Berrang=E9?= , Kairui Song , Jan Pazdziora , Pingfan Liu , Baoquan He , Dave Young , linux-kernel@vger.kernel.org, x86@kernel.org, Dave Hansen , Vitaly Kuznetsov , Eric Biederman Subject: Re: [PATCH v5 1/7] kexec_file: allow to place kexec_buf randomly Message-ID: <2024060842-entryway-gurgle-4ae2@gregkh> References: <20240607122622.167228-1-coxu@redhat.com> <20240607122622.167228-2-coxu@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240607122622.167228-2-coxu@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240608_021209_498975_BD76C3BC X-CRM114-Status: GOOD ( 22.83 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Fri, Jun 07, 2024 at 08:26:11PM +0800, Coiby Xu wrote: > 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 | 4 ++++ > kernel/kexec_file.c | 21 +++++++++++++++++++++ > 2 files changed, 25 insertions(+) > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index f0e9f8eda7a3..c45bfc727737 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 +183,9 @@ struct kexec_buf { > unsigned long buf_min; > unsigned long buf_max; > bool top_down; > +#ifdef CONFIG_CRASH_DUMP > + bool random; > +#endif Why is the ifdef needed? > }; > > int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf); > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 3d64290d24c9..f7538d8f67e0 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -25,6 +25,9 @@ > #include > #include > #include > +#ifdef CONFIG_CRASH_DUMP > +#include > +#endif No ifdef in .c files please. This should not be an issue. > #include > #include > #include "kexec_internal.h" > @@ -437,6 +440,18 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, > return ret; > } > > +#ifdef CONFIG_CRASH_DUMP > +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; > +} > +#endif This #ifdef should be handled properly in the .h file. > + > static int locate_mem_hole_top_down(unsigned long start, unsigned long end, > struct kexec_buf *kbuf) > { > @@ -445,6 +460,10 @@ 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; > +#ifdef CONFIG_CRASH_DUMP > + if (kbuf->random) > + temp_start = kexec_random_start(temp_start, temp_end); > +#endif Same with this. And why do you need the boolean at all, why not just have kexec_random_start() handle this properly for you? thanks, greg k-h _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec