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From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>, Baoquan He <bhe@redhat.com>,
	Yinghai Lu <yinghai@kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Matt Redfearn <matt.redfearn@imgtec.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Ingo Molnar <mingo@redhat.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: [PATCH v5 17/21] x86, KASLR: Clarify purpose of each get_random_long
Date: Thu, 14 Apr 2016 15:29:10 -0700	[thread overview]
Message-ID: <1460672954-32567-18-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1460672954-32567-1-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 offset. With this, once the
virtual offset is separate, the report changes:

Before:
KASLR using RDTSC...
KASLR using RDTSC...

After:
Physical KASLR using RDTSC...
Virtual KASLR using RDTSC...

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/x86/boot/compressed/aslr.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index b527ff10372a..c58215d5a80d 100644
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -60,7 +60,7 @@ 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;
@@ -70,7 +70,8 @@ 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");
@@ -338,7 +339,7 @@ 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,
@@ -425,7 +426,7 @@ static unsigned long find_random_virt_offset(unsigned long minimum,
 	slots = (KERNEL_IMAGE_SIZE - minimum - image_size) /
 		 CONFIG_PHYSICAL_ALIGN + 1;
 
-	random = get_random_long() % slots;
+	random = get_random_long("Virtual") % slots;
 
 	return random * CONFIG_PHYSICAL_ALIGN + minimum;
 }
-- 
2.6.3

  parent reply	other threads:[~2016-04-14 22:30 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-14 22:28 [PATCH v5 00/21] x86, boot: KASLR cleanup and 64-bit improvements Kees Cook
2016-04-14 22:28 ` [PATCH v5 01/21] x86, KASLR: Remove unneeded boot_params argument Kees Cook
2016-04-15  7:29   ` Ingo Molnar
2016-04-15 18:55     ` Kees Cook
2016-04-14 22:28 ` [PATCH v5 02/21] x86, KASLR: Handle kernel relocation above 2G Kees Cook
2016-04-15  7:47   ` Ingo Molnar
2016-04-15 19:01     ` Kees Cook
2016-04-14 22:28 ` [PATCH v5 03/21] x86, KASLR: Drop CONFIG_RANDOMIZE_BASE_MAX_OFFSET Kees Cook
2016-04-15  8:07   ` Ingo Molnar
2016-04-15 19:12     ` Kees Cook
2016-04-16  8:42       ` Ingo Molnar
2016-04-14 22:28 ` [PATCH v5 04/21] x86, boot: Move compressed kernel to end of decompression buffer Kees Cook
2016-04-15  8:09   ` Ingo Molnar
2016-04-18 16:50     ` Kees Cook
2016-04-15  9:05   ` Ingo Molnar
2016-04-14 22:28 ` [PATCH v5 05/21] x86, boot: Calculate decompression size during boot not build Kees Cook
2016-04-15  8:12   ` Ingo Molnar
2016-04-15 19:14     ` Kees Cook
2016-04-14 22:28 ` [PATCH v5 06/21] x86, KASLR: Update description for decompressor worst case size Kees Cook
2016-04-15 16:17   ` Lasse Collin
2016-04-14 22:29 ` [PATCH v5 07/21] x86, boot: Fix run_size calculation Kees Cook
2016-04-15  8:31   ` Ingo Molnar
2016-04-15 19:26     ` Kees Cook
2016-04-16  9:00       ` Ingo Molnar
2016-04-14 22:29 ` [PATCH v5 08/21] x86, KASLR: Clean up unused code from old run_size Kees Cook
2016-04-14 22:29 ` [PATCH v5 09/21] x86, KASLR: Correctly bounds-check relocations Kees Cook
2016-04-14 22:29 ` [PATCH v5 10/21] x86, KASLR: Consolidate mem_avoid entries Kees Cook
2016-04-14 22:29 ` [PATCH v5 11/21] x86, boot: Split out kernel_ident_mapping_init Kees Cook
2016-04-14 22:29 ` [PATCH v5 12/21] x86, 64bit: Set ident_mapping for KASLR Kees Cook
2016-04-14 22:29 ` [PATCH v5 13/21] x86, boot: Report overlap failures in memcpy Kees Cook
2016-04-15 14:42   ` Lasse Collin
2016-04-15 19:28     ` Kees Cook
2016-04-14 22:29 ` [PATCH v5 14/21] x86, KASLR: Add slot_area to manage random slots Kees Cook
2016-04-14 22:29 ` [PATCH v5 15/21] x86, KASLR: Add slot_area support functions Kees Cook
2016-04-14 22:29 ` [PATCH v5 16/21] x86, KASLR: Add virtual address choosing function Kees Cook
2016-04-14 22:29 ` Kees Cook [this message]
2016-04-14 22:29 ` [PATCH v5 18/21] x86, KASLR: Randomize virtual address separately Kees Cook
2016-04-14 22:29 ` [PATCH v5 19/21] x86, KASLR: Add physical address randomization >4G Kees Cook
2016-04-14 22:29 ` [PATCH v5 20/21] x86, KASLR: Remove unused slot tracking code Kees Cook
2016-04-14 22:29 ` [PATCH v5 21/21] x86, KASLR: Allow randomization below load address Kees Cook

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