From: Albert van der Linde <alinde@xxxxxxxxxx>
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.
Reviewed-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
Signed-off-by: Albert van der Linde <alinde@xxxxxxxxxx>
---
v2:
- removed partial failures
v3:
- adressed comments from Peter Zijlstra (fixed ordering with might_fault())
---
include/linux/uaccess.h | 11 ++++++++++-
lib/iov_iter.c | 5 +++++
lib/strncpy_from_user.c | 3 +++
lib/usercopy.c | 5 ++++-
4 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 94b285411659..e3968727e993 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -2,6 +2,7 @@
#ifndef __LINUX_UACCESS_H__
#define __LINUX_UACCESS_H__
+#include <linux/fault-inject-usercopy.h>
#include <linux/instrumented.h>
#include <linux/sched.h>
#include <linux/thread_info.h>
@@ -83,6 +84,8 @@ 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);
@@ -104,6 +107,8 @@ __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);
@@ -113,6 +118,8 @@ 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);
@@ -124,7 +131,7 @@ _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);
}
@@ -142,6 +149,8 @@ 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);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 5e40786c8f12..eeac08855b24 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -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>
@@ -139,6 +140,8 @@
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);
@@ -148,6 +151,8 @@ 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);
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 34696a348864..e6d5fcc2cdf3 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -1,6 +1,7 @@
// 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;
diff --git a/lib/usercopy.c b/lib/usercopy.c
index b26509f112f9..7413dd300516 100644
--- a/lib/usercopy.c
+++ b/lib/usercopy.c
@@ -1,5 +1,6 @@
// 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);
--
2.28.0.402.g5ffc5be6b7-goog
