mbedtls/tests/suites/test_suite_constant_time.function

/* BEGIN_HEADER */
/** \file test_suite_constant_time.function
 *
 * Functional testing of functions in the constant_time module.
 *
 * The tests are instrumented with #TEST_CF_SECRET and #TEST_CF_PUBLIC
 * (see tests/include/test/constant_flow.h) so that running the tests
 * under MSan or Valgrind will detect a non-constant-time implementation.
 */

#include <mbedtls/constant_time.h>
#include <constant_time_internal.h>
#include <constant_time_invasive.h>

#include <test/constant_flow.h>
/* END_HEADER */

/* BEGIN_CASE */
void mbedtls_ct_memcmp_null()
{
    uint32_t x;
    TEST_ASSERT(mbedtls_ct_memcmp(&x, NULL, 0) == 0);
    TEST_ASSERT(mbedtls_ct_memcmp(NULL, &x, 0) == 0);
    TEST_ASSERT(mbedtls_ct_memcmp(NULL, NULL, 0) == 0);
}
/* END_CASE */

/* BEGIN_CASE */
void mbedtls_ct_memcmp(int same, int size, int offset)
{
    uint8_t *a = NULL, *b = NULL;
    ASSERT_ALLOC(a, size + offset);
    ASSERT_ALLOC(b, size + offset);

    TEST_CF_SECRET(a + offset, size);
    TEST_CF_SECRET(b + offset, size);

    /* Construct data that matches, if same == -1, otherwise
     * same gives the number of bytes (after the initial offset)
     * that will match; after that it will differ.
     */
    for (int i = 0; i < size + offset; i++) {
        a[i] = i & 0xff;
        if (same == -1 || (i - offset) < same) {
            b[i] = a[i];
        } else {
            b[i] = (i + 1) & 0xff;
        }
    }

    int reference = memcmp(a + offset, b + offset, size);
    int actual = mbedtls_ct_memcmp(a + offset, b + offset, size);
    TEST_CF_PUBLIC(a + offset, size);
    TEST_CF_PUBLIC(b + offset, size);

    if (same == -1 || same >= size) {
        TEST_ASSERT(reference == 0);
        TEST_ASSERT(actual == 0);
    } else {
        TEST_ASSERT(reference != 0);
        TEST_ASSERT(actual != 0);
    }
exit:
    mbedtls_free(a);
    mbedtls_free(b);
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_SSL_SOME_SUITES_USE_MAC */
void mbedtls_ct_memcpy_if_eq(int eq, int size, int offset)
{
    uint8_t *src = NULL, *result = NULL, *expected = NULL;
    ASSERT_ALLOC(src, size + offset);
    ASSERT_ALLOC(result, size + offset);
    ASSERT_ALLOC(expected, size + offset);

    for (int i = 0; i < size + offset; i++) {
        src[i]    = 1;
        result[i] = 0xff;
        expected[i] = eq ? 1 : 0xff;
    }

    mbedtls_ct_memcpy_if_eq(result + offset, src, size, eq, 1);
    ASSERT_COMPARE(expected, size, result + offset, size);

    for (int i = 0; i < size + offset; i++) {
        src[i]    = 1;
        result[i] = 0xff;
        expected[i] = eq ? 1 : 0xff;
    }
    mbedtls_ct_memcpy_if_eq(result, src + offset, size, eq, 1);
    ASSERT_COMPARE(expected, size, result, size);

exit:
    mbedtls_free(src);
    mbedtls_free(result);
    mbedtls_free(expected);
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC:MBEDTLS_TEST_HOOKS */
void ssl_cf_memcpy_offset(int offset_min, int offset_max, int len)
{
    unsigned char *dst = NULL;
    unsigned char *src = NULL;
    size_t src_len = offset_max + len;
    size_t secret;

    ASSERT_ALLOC(dst, len);
    ASSERT_ALLOC(src, src_len);

    /* Fill src in a way that we can detect if we copied the right bytes */
    mbedtls_test_rnd_std_rand(NULL, src, src_len);

    for (secret = offset_min; secret <= (size_t) offset_max; secret++) {
        mbedtls_test_set_step((int) secret);

        TEST_CF_SECRET(&secret, sizeof(secret));
        mbedtls_ct_memcpy_offset(dst, src, secret,
                                 offset_min, offset_max, len);
        TEST_CF_PUBLIC(&secret, sizeof(secret));
        TEST_CF_PUBLIC(dst, len);

        ASSERT_COMPARE(dst, len, src + secret, len);
    }

exit:
    mbedtls_free(dst);
    mbedtls_free(src);
}
/* END_CASE */