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x86/mm: Refactor KASLR entropy functions 

Move the KASLR entropy functions into arch/x86/lib to be used in early
kernel boot for KASLR memory randomization.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1466556426-32664-2-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Thomas Garnier 2016-06-21 17:46:58 -07:00 committed by Ingo Molnar
parent 9e7f7f5425
commit d899a7d146
4 changed files with 102 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
arch/x86/boot/compressed/kaslr.c
View File

@ -12,10 +12,6 @@
#include "misc.h"
#include "error.h"
#include <asm/msr.h>
#include <asm/archrandom.h>
#include <asm/e820.h>
#include <generated/compile.h>
#include <linux/module.h>
#include <linux/uts.h>
@ -26,26 +22,6 @@
static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
#define I8254_PORT_CONTROL 0x43
#define I8254_PORT_COUNTER0 0x40
#define I8254_CMD_READBACK 0xC0
#define I8254_SELECT_COUNTER0 0x02
#define I8254_STATUS_NOTREADY 0x40
static inline u16 i8254(void)
{
u16 status, timer;
do {
outb(I8254_PORT_CONTROL,
I8254_CMD_READBACK | I8254_SELECT_COUNTER0);
status = inb(I8254_PORT_COUNTER0);
timer = inb(I8254_PORT_COUNTER0);
timer |= inb(I8254_PORT_COUNTER0) << 8;
} while (status & I8254_STATUS_NOTREADY);
return timer;
}
static unsigned long rotate_xor(unsigned long hash, const void *area,
size_t size)
{
@ -62,7 +38,7 @@ static unsigned long rotate_xor(unsigned long hash, const void *area,
}
/* Attempt to create a simple but unpredictable starting entropy. */
static unsigned long get_random_boot(void)
static unsigned long get_boot_seed(void)
{
unsigned long hash = 0;
@ -72,50 +48,8 @@ static unsigned long get_random_boot(void)
return hash;
}
static unsigned long get_random_long(const char *purpose)
{
#ifdef CONFIG_X86_64
const unsigned long mix_const = 0x5d6008cbf3848dd3UL;
#else
const unsigned long mix_const = 0x3f39e593UL;
#endif
unsigned long raw, random = get_random_boot();
bool use_i8254 = true;
debug_putstr(purpose);
debug_putstr(" KASLR using");
if (has_cpuflag(X86_FEATURE_RDRAND)) {
debug_putstr(" RDRAND");
if (rdrand_long(&raw)) {
random ^= raw;
use_i8254 = false;
}
}
if (has_cpuflag(X86_FEATURE_TSC)) {
debug_putstr(" RDTSC");
raw = rdtsc();
random ^= raw;
use_i8254 = false;
}
if (use_i8254) {
debug_putstr(" i8254");
random ^= i8254();
}
/* Circular multiply for better bit diffusion */
asm("mul %3"
: "=a" (random), "=d" (raw)
: "a" (random), "rm" (mix_const));
random += raw;
debug_putstr("...\n");
return random;
}
#define KASLR_COMPRESSED_BOOT
#include "../../lib/kaslr.c"
struct mem_vector {
unsigned long start;
@ -349,7 +283,7 @@ static unsigned long slots_fetch_random(void)
if (slot_max == 0)
return 0;
slot = get_random_long("Physical") % slot_max;
slot = kaslr_get_random_long("Physical") % slot_max;
for (i = 0; i < slot_area_index; i++) {
if (slot >= slot_areas[i].num) {
@ -479,7 +413,7 @@ 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("Virtual") % slots;
random_addr = kaslr_get_random_long("Virtual") % slots;
return random_addr * CONFIG_PHYSICAL_ALIGN + minimum;
}

6
arch/x86/include/asm/kaslr.h Normal file
View File

@ -0,0 +1,6 @@
#ifndef _ASM_KASLR_H_
#define _ASM_KASLR_H_
unsigned long kaslr_get_random_long(const char *purpose);
#endif

1
arch/x86/lib/Makefile
View File

@ -24,6 +24,7 @@ lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
lib-y += memcpy_$(BITS).o
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
obj-y += msr.o msr-reg.o msr-reg-export.o

90
arch/x86/lib/kaslr.c Normal file
View File

@ -0,0 +1,90 @@
/*
* Entropy functions used on early boot for KASLR base and memory
* randomization. The base randomization is done in the compressed
* kernel and memory randomization is done early when the regular
* kernel starts. This file is included in the compressed kernel and
* normally linked in the regular.
*/
#include <asm/kaslr.h>
#include <asm/msr.h>
#include <asm/archrandom.h>
#include <asm/e820.h>
#include <asm/io.h>
/*
* When built for the regular kernel, several functions need to be stubbed out
* or changed to their regular kernel equivalent.
*/
#ifndef KASLR_COMPRESSED_BOOT
#include <asm/cpufeature.h>
#include <asm/setup.h>
#define debug_putstr(v) early_printk(v)
#define has_cpuflag(f) boot_cpu_has(f)
#define get_boot_seed() kaslr_offset()
#endif
#define I8254_PORT_CONTROL 0x43
#define I8254_PORT_COUNTER0 0x40
#define I8254_CMD_READBACK 0xC0
#define I8254_SELECT_COUNTER0 0x02
#define I8254_STATUS_NOTREADY 0x40
static inline u16 i8254(void)
{
u16 status, timer;
do {
outb(I8254_PORT_CONTROL,
I8254_CMD_READBACK | I8254_SELECT_COUNTER0);
status = inb(I8254_PORT_COUNTER0);
timer = inb(I8254_PORT_COUNTER0);
timer |= inb(I8254_PORT_COUNTER0) << 8;
} while (status & I8254_STATUS_NOTREADY);
return timer;
}
unsigned long kaslr_get_random_long(const char *purpose)
{
#ifdef CONFIG_X86_64
const unsigned long mix_const = 0x5d6008cbf3848dd3UL;
#else
const unsigned long mix_const = 0x3f39e593UL;
#endif
unsigned long raw, random = get_boot_seed();
bool use_i8254 = true;
debug_putstr(purpose);
debug_putstr(" KASLR using");
if (has_cpuflag(X86_FEATURE_RDRAND)) {
debug_putstr(" RDRAND");
if (rdrand_long(&raw)) {
random ^= raw;
use_i8254 = false;
}
}
if (has_cpuflag(X86_FEATURE_TSC)) {
debug_putstr(" RDTSC");
raw = rdtsc();
random ^= raw;
use_i8254 = false;
}
if (use_i8254) {
debug_putstr(" i8254");
random ^= i8254();
}
/* Circular multiply for better bit diffusion */
asm("mul %3"
: "=a" (random), "=d" (raw)
: "a" (random), "rm" (mix_const));
random += raw;
debug_putstr("...\n");
return random;
}