From d2d3462f9f08da364c8fbd41e8e32229d610d49d Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Mon, 9 May 2016 13:22:09 -0700
Subject: x86/KASLR: Clarify purpose of each get_random_long()
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>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: lasse.collin@tukaani.org
Link: http://lkml.kernel.org/r/1462825332-10505-7-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/boot/compressed/kaslr.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
(limited to 'arch/x86/boot/compressed/kaslr.c')
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 016a4f48b19e..cfeb0259ed81 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;
}
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