From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5261F83CB4 for ; Tue, 4 Jun 2024 07:41:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717486907; cv=none; b=WEeVVWsUyL1MVChuWO2NlJxIYaiQQjm9nguqZGoIq/srnxUETn2GguAoouPMyVWMOXOQS7CRma+W/RgIe0ht1n+pXaKxVJNkiq+6dY6dLjtS9QW4Tn1chcQe2qdl8rmC++znZMrab9WiVmIaol5poR7vS4ISQU/K1+qgdjhj7BA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717486907; c=relaxed/simple; bh=uqrD+mSTw2cbrHqixanYyy0kaU3D0TlQKJePcyo5e5E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oppBeDqHIqB3ApjhYbIzpXSalxXeNi1M/el2yvlAlHeYKwCcNrEp8BeUk0qOUD5uOtqSrsxI56Ri75jY9uGdHajsvYv0XhBOQBMMs9yNsYSL3lE4+piFkHIEOmzDISXGlWhkYsaLIQH10hYAm/7OvLkZILL8TdC5kKTdydauyS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KHLfYGrx; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KHLfYGrx" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1717486904; 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: in-reply-to:in-reply-to:references:references; bh=TsMImdYFRkA+pOndLmWX7p9H2qEq17QcVQSCTLk4QM0=; b=KHLfYGrxavJeB4PeX6w5j54jk8vFQ1+Lmt3RkpeI4ZRckXZWS+wXHZpJVRJweJaAbh3EcN bIcTbZWb++By278lW6bai3ejVNfM8ztK/ZSITchxHKwW+7rF8grzDtqb0A3I2APL1CsL8N h/aHfkMDMFqmMQkUhxBfEqNSR5zXiN4= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-515-SJikkqORMAqbpA2TenS47Q-1; Tue, 04 Jun 2024 03:41:40 -0400 X-MC-Unique: SJikkqORMAqbpA2TenS47Q-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 007853806620; Tue, 4 Jun 2024 07:41:40 +0000 (UTC) Received: from localhost (unknown [10.72.116.9]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B30C4492EE6; Tue, 4 Jun 2024 07:41:38 +0000 (UTC) Date: Tue, 4 Jun 2024 15:41:35 +0800 From: Baoquan He 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 , Dave Young , linux-kernel@vger.kernel.org, x86@kernel.org, Dave Hansen , Vitaly Kuznetsov , Eric Biederman Subject: Re: [PATCH v4 1/7] kexec_file: allow to place kexec_buf randomly Message-ID: References: <20240523050451.788754-1-coxu@redhat.com> <20240523050451.788754-2-coxu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240523050451.788754-2-coxu@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 On 05/23/24 at 01:04pm, 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 | 2 ++ > kernel/kexec_file.c | 15 +++++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index f0e9f8eda7a3..cc81b8a903ab 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 3d64290d24c9..06b77f9ac4cc 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" > @@ -437,6 +438,16 @@ 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) > { > @@ -445,6 +456,8 @@ 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 + 1; > + if (kbuf->random) > + temp_start = kexec_random_start(temp_start, temp_end); As we discussed before, this need be limited in kdump scope, seems v4 doesn't include the change. > > do { > /* align down start */ > @@ -482,6 +495,8 @@ 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); > -- > 2.45.0 >