Commit e82e600d authored by Nick Mathewson's avatar Nick Mathewson 🌉
Browse files

Here is a test for memwipe.

It invokes undefined behavior, I'm afraid, since there's no other
c-legal way to test whether memwipe() works when we're not allowed to
look at it.

Closes ticket 15377.
parent 98c39421
o Testing:
- Add a test to verify that the compiler does not eliminate our
memwipe() implementation. Closes ticket 15377.
TESTS += src/test/test src/test/test-slow
TESTS += src/test/test src/test/test-slow src/test/test-memwipe
noinst_PROGRAMS+= src/test/bench
if UNITTESTS_ENABLED
noinst_PROGRAMS+= \
src/test/test \
src/test/test-slow \
src/test/test-memwipe \
src/test/test-child \
src/test/test_workqueue
endif
......@@ -73,6 +74,9 @@ src_test_test_slow_SOURCES = \
src/test/testing_common.c \
src/ext/tinytest.c
src_test_test_memwipe_SOURCES = \
src/test/test-memwipe.c
src_test_test_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
......@@ -100,6 +104,11 @@ src_test_test_slow_CFLAGS = $(src_test_test_CFLAGS)
src_test_test_slow_LDADD = $(src_test_test_LDADD)
src_test_test_slow_LDFLAGS = $(src_test_test_LDFLAGS)
src_test_test_memwipe_CPPFLAGS = $(src_test_test_CPPFLAGS)
src_test_test_memwipe_CFLAGS = $(src_test_test_CFLAGS)
src_test_test_memwipe_LDADD = $(src_test_test_LDADD)
src_test_test_memwipe_LDFLAGS = $(src_test_test_LDFLAGS)
src_test_bench_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \
@TOR_LDFLAGS_libevent@
src_test_bench_LDADD = src/or/libtor.a src/common/libor.a \
......
#include <string.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>
#include "crypto.h"
#include "compat.h"
#undef MIN
#define MIN(a,b) ( ((a)<(b)) ? (a) : (b) )
static unsigned fill_a_buffer_memset(void) __attribute__((noinline));
static unsigned fill_a_buffer_memwipe(void) __attribute__((noinline));
static unsigned fill_a_buffer_nothing(void) __attribute__((noinline));
static unsigned fill_heap_buffer_memset(void) __attribute__((noinline));
static unsigned fill_heap_buffer_memwipe(void) __attribute__((noinline));
static unsigned fill_heap_buffer_nothing(void) __attribute__((noinline));
static unsigned check_a_buffer(void) __attribute__((noinline));
const char *s = NULL;
#define FILL_BUFFER_IMPL() \
unsigned int i; \
unsigned sum = 0; \
\
/* Fill up a 1k buffer with a recognizable pattern. */ \
for (i = 0; i < 2048; i += strlen(s)) { \
memcpy(buf+i, s, MIN(strlen(s), 2048-i)); \
} \
\
/* Use the buffer as input to a computation so the above can't get */ \
/* optimized away. */ \
for (i = 0; i < 2048; ++i) { \
sum += (unsigned char)buf[i]; \
}
static unsigned
fill_a_buffer_memset(void)
{
char buf[2048];
FILL_BUFFER_IMPL()
memset(buf, 0, sizeof(buf));
return sum;
}
static unsigned
fill_a_buffer_memwipe(void)
{
char buf[2048];
FILL_BUFFER_IMPL()
memwipe(buf, 0, sizeof(buf));
return sum;
}
static unsigned
fill_a_buffer_nothing(void)
{
char buf[2048];
FILL_BUFFER_IMPL()
return sum;
}
static INLINE int
vmemeq(volatile char *a, const char *b, size_t n)
{
while (n--) {
if (*a++ != *b++)
return 0;
}
return 1;
}
static unsigned
check_a_buffer(void)
{
unsigned int i;
volatile char buf[1024];
unsigned sum = 0;
/* See if this buffer has the string in it.
YES, THIS DOES INVOKE UNDEFINED BEHAVIOR BY READING FROM AN UNINITIALIZED
BUFFER.
If you know a better way to figure out whether the compiler eliminated
the memset/memwipe calls or not, please let me know.
*/
for (i = 0; i < sizeof(buf); ++i) {
if (vmemeq(buf+i, s, strlen(s)))
++sum;
}
return sum;
}
static char *heap_buf = NULL;
static unsigned
fill_heap_buffer_memset(void)
{
char *buf = heap_buf = malloc(2048);
FILL_BUFFER_IMPL()
memset(buf, 0, 2048);
free(buf);
return sum;
}
static unsigned
fill_heap_buffer_memwipe(void)
{
char *buf = heap_buf = malloc(2048);
FILL_BUFFER_IMPL()
memwipe(buf, 0, 2048);
free(buf);
return sum;
}
static unsigned
fill_heap_buffer_nothing(void)
{
char *buf = heap_buf = malloc(2048);
FILL_BUFFER_IMPL()
free(buf);
return sum;
}
static unsigned
check_heap_buffer(void)
{
unsigned int i;
unsigned sum = 0;
volatile char *buf = heap_buf;
/* See if this buffer has the string in it.
YES, THIS DOES INVOKE UNDEFINED BEHAVIOR BY READING FROM A FREED BUFFER.
If you know a better way to figure out whether the compiler eliminated
the memset/memwipe calls or not, please let me know.
*/
for (i = 0; i < sizeof(buf); ++i) {
if (vmemeq(buf+i, s, strlen(s)))
++sum;
}
return sum;
}
static struct testcase {
const char *name;
unsigned (*fill_fn)(void);
unsigned (*check_fn)(void);
} testcases[] = {
{ "nil", fill_a_buffer_nothing, check_a_buffer },
{ "nil-heap", fill_heap_buffer_nothing, check_heap_buffer },
{ "memset", fill_a_buffer_memset, check_a_buffer },
{ "memset-heap", fill_heap_buffer_memset, check_heap_buffer },
{ "memwipe", fill_a_buffer_memwipe, check_a_buffer },
{ "memwipe-heap", fill_heap_buffer_memwipe, check_heap_buffer },
{ NULL, NULL, NULL }
};
int
main(int argc, char **argv)
{
unsigned x, x2;
int i;
int working = 1;
unsigned found[6];
(void) argc; (void) argv;
s = "squamous haberdasher gallimaufry";
memset(found, 0, sizeof(found));
for (i = 0; testcases[i].name; ++i) {
x = testcases[i].fill_fn();
found[i] = testcases[i].check_fn();
x2 = fill_a_buffer_nothing();
if (x != x2) {
working = 0;
}
}
if (!working || !found[0] || !found[1]) {
printf("It appears that this test case may not give you reliable "
"information. Sorry.\n");
}
if (!found[2] && !found[3]) {
printf("It appears that memset is good enough on this platform. Good.\n");
}
if (found[4] || found[5]) {
printf("ERROR: memwipe does not wipe data!\n");
return 1;
} else {
printf("OKAY: memwipe seems to work.");
return 0;
}
}
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