From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752882AbcEIUYR (ORCPT ); Mon, 9 May 2016 16:24:17 -0400 Received: from mail-pf0-f179.google.com ([209.85.192.179]:32895 "EHLO mail-pf0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751580AbcEIUWT (ORCPT ); Mon, 9 May 2016 16:22:19 -0400 From: Kees Cook To: Ingo Molnar Cc: Kees Cook , Borislav Petkov , Baoquan He , Yinghai Lu , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Vivek Goyal , Andy Lutomirski , lasse.collin@tukaani.org, Andrew Morton , Dave Young , kernel-hardening@lists.openwall.com, LKML Subject: [PATCH v7 6/9] x86/KASLR: Clarify purpose of each get_random_long() Date: Mon, 9 May 2016 13:22:09 -0700 Message-Id: <1462825332-10505-7-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1462825332-10505-1-git-send-email-keescook@chromium.org> References: <1462825332-10505-1-git-send-email-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KASLR will be calling get_random_long() twice, but the debug output won't distinguishing between them. This patch adds a report on when it is fetching the physical vs virtual address. With this, once the virtual offset is separate, the report changes from: KASLR using RDTSC... KASLR using RDTSC... into: Physical KASLR using RDTSC... Virtual KASLR using RDTSC... Signed-off-by: Kees Cook --- arch/x86/boot/compressed/kaslr.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 82d00282df3f..c4b1e4b05cb6 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -72,7 +72,7 @@ static unsigned long get_random_boot(void) return hash; } -static unsigned long get_random_long(void) +static unsigned long get_random_long(const char *purpose) { #ifdef CONFIG_X86_64 const unsigned long mix_const = 0x5d6008cbf3848dd3UL; @@ -82,7 +82,8 @@ static unsigned long get_random_long(void) unsigned long raw, random = get_random_boot(); bool use_i8254 = true; - debug_putstr("KASLR using"); + debug_putstr(purpose); + debug_putstr(" KASLR using"); if (has_cpuflag(X86_FEATURE_RDRAND)) { debug_putstr(" RDRAND"); @@ -365,7 +366,7 @@ static unsigned long slots_fetch_random(void) if (slot_max == 0) return 0; - return slots[get_random_long() % slot_max]; + return slots[get_random_long("Physical") % slot_max]; } static void process_e820_entry(struct e820entry *entry, @@ -453,7 +454,7 @@ static unsigned long find_random_virt_addr(unsigned long minimum, slots = (KERNEL_IMAGE_SIZE - minimum - image_size) / CONFIG_PHYSICAL_ALIGN + 1; - random_addr = get_random_long() % slots; + random_addr = get_random_long("Virtual") % slots; return random_addr * CONFIG_PHYSICAL_ALIGN + minimum; } -- 2.6.3