From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>, Ingo Molnar <mingo@redhat.com>,
Baoquan He <bhe@redhat.com>, Yinghai Lu <yinghai@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
Vivek Goyal <vgoyal@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
lasse.collin@tukaani.org,
Andrew Morton <akpm@linux-foundation.org>,
Dave Young <dyoung@redhat.com>,
kernel-hardening@lists.openwall.com,
LKML <linux-kernel@vger.kernel.org>
Subject: [kernel-hardening] [PATCH v6 08/11] x86/KASLR: Clarify purpose of each get_random_long
Date: Thu, 5 May 2016 15:13:53 -0700 [thread overview]
Message-ID: <1462486436-3707-9-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1462486436-3707-1-git-send-email-keescook@chromium.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 <keescook@chromium.org>
---
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 05f564b6c70e..3672c7388e5a 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");
@@ -332,7 +333,7 @@ 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,
@@ -420,7 +421,7 @@ 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
next prev parent reply other threads:[~2016-05-05 22:13 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-05 22:13 [kernel-hardening] [PATCH v6 0/11] x86/KASLR: Randomize virtual address separately Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 01/11] x86/boot: Clean up pointer casting Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 02/11] x86/KASLR: Consolidate mem_avoid entries Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 03/11] x86/boot: Split out kernel_ident_mapping_init Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 04/11] x86/KASLR: Build identity mappings on demand Kees Cook
2016-05-06 7:00 ` [kernel-hardening] " Ingo Molnar
2016-05-06 17:44 ` Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 05/11] x86/KASLR: Add slot_area to manage random_addr slots Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 06/11] x86/KASLR: Return earliest overlap when avoiding regions Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 07/11] x86/KASLR: Add virtual address choosing function Kees Cook
2016-05-05 22:13 ` Kees Cook [this message]
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 09/11] x86/KASLR: Randomize virtual address separately Kees Cook
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 10/11] x86/KASLR: Add physical address randomization >4G Kees Cook
2016-05-06 8:27 ` [kernel-hardening] " Baoquan He
2016-05-06 15:31 ` Kees Cook
2016-05-08 9:17 ` Baoquan He
2016-05-05 22:13 ` [kernel-hardening] [PATCH v6 11/11] x86/KASLR: Allow randomization below load address Kees Cook
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