Commit 4d0e9df5 authored by Albert van der Linde's avatar Albert van der Linde Committed by Linus Torvalds
Browse files

lib, uaccess: add failure injection to usercopy functions 



To test fault-tolerance of user memory access functions, introduce fault
injection to usercopy functions.

If a failure is expected return either -EFAULT or the total amount of
bytes that were not copied.

Signed-off-by: default avatarAlbert van der Linde <alinde@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: default avatarAlexander Potapenko <glider@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20200831171733.955393-3-alinde@google.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2c739ced

include/linux/uaccess.h

+10 −1
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#ifndef __LINUX_UACCESS_H__

#define __LINUX_UACCESS_H__



#include <linux/fault-inject-usercopy.h>

#include <linux/instrumented.h>

#include <linux/minmax.h>

#include <linux/sched.h>
@@ -84,6 +85,8 @@ static __always_inline __must_check unsigned long 
__copy_from_user(void *to, const void __user *from, unsigned long n)

{

	might_fault();

	if (should_fail_usercopy())

		return n;

	instrument_copy_from_user(to, from, n);

	check_object_size(to, n, false);

	return raw_copy_from_user(to, from, n);
@@ -105,6 +108,8 @@ __copy_from_user(void *to, const void __user *from, unsigned long n) 
static __always_inline __must_check unsigned long

__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)

{

	if (should_fail_usercopy())

		return n;

	instrument_copy_to_user(to, from, n);

	check_object_size(from, n, true);

	return raw_copy_to_user(to, from, n);
@@ -114,6 +119,8 @@ static __always_inline __must_check unsigned long 
__copy_to_user(void __user *to, const void *from, unsigned long n)

{

	might_fault();

	if (should_fail_usercopy())

		return n;

	instrument_copy_to_user(to, from, n);

	check_object_size(from, n, true);

	return raw_copy_to_user(to, from, n);
@@ -125,7 +132,7 @@ _copy_from_user(void *to, const void __user *from, unsigned long n) 
{

	unsigned long res = n;

	might_fault();

	if (likely(access_ok(from, n))) {

	if (!should_fail_usercopy() && likely(access_ok(from, n))) {

		instrument_copy_from_user(to, from, n);

		res = raw_copy_from_user(to, from, n);

	}
@@ -143,6 +150,8 @@ static inline __must_check unsigned long 
_copy_to_user(void __user *to, const void *from, unsigned long n)

{

	might_fault();

	if (should_fail_usercopy())

		return n;

	if (access_ok(to, n)) {

		instrument_copy_to_user(to, from, n);

		n = raw_copy_to_user(to, from, n);

lib/iov_iter.c

+5 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#include <crypto/hash.h>

#include <linux/export.h>

#include <linux/bvec.h>

#include <linux/fault-inject-usercopy.h>

#include <linux/uio.h>

#include <linux/pagemap.h>

#include <linux/slab.h>
@@ -140,6 +141,8 @@ 


static int copyout(void __user *to, const void *from, size_t n)

{

	if (should_fail_usercopy())

		return n;

	if (access_ok(to, n)) {

		instrument_copy_to_user(to, from, n);

		n = raw_copy_to_user(to, from, n);
@@ -149,6 +152,8 @@ static int copyout(void __user *to, const void *from, size_t n) 


static int copyin(void *to, const void __user *from, size_t n)

{

	if (should_fail_usercopy())

		return n;

	if (access_ok(from, n)) {

		instrument_copy_from_user(to, from, n);

		n = raw_copy_from_user(to, from, n);

lib/strncpy_from_user.c

+3 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/compiler.h>

#include <linux/export.h>

#include <linux/fault-inject-usercopy.h>

#include <linux/kasan-checks.h>

#include <linux/thread_info.h>

#include <linux/uaccess.h>
@@ -99,6 +100,8 @@ long strncpy_from_user(char *dst, const char __user *src, long count) 
	unsigned long max_addr, src_addr;



	might_fault();

	if (should_fail_usercopy())

		return -EFAULT;

	if (unlikely(count <= 0))

		return 0;

lib/usercopy.c

+4 −1
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/bitops.h>

#include <linux/fault-inject-usercopy.h>

#include <linux/instrumented.h>

#include <linux/uaccess.h>
@@ -10,7 +11,7 @@ unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n 
{

	unsigned long res = n;

	might_fault();

	if (likely(access_ok(from, n))) {

	if (!should_fail_usercopy() && likely(access_ok(from, n))) {

		instrument_copy_from_user(to, from, n);

		res = raw_copy_from_user(to, from, n);

	}
@@ -25,6 +26,8 @@ EXPORT_SYMBOL(_copy_from_user); 
unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)

{

	might_fault();

	if (should_fail_usercopy())

		return n;

	if (likely(access_ok(to, n))) {

		instrument_copy_to_user(to, from, n);

		n = raw_copy_to_user(to, from, n);

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