openssl/test/sm2_internal_test.c
Matt Caswell 36cf45ef3b Correctly calculate the length of SM2 plaintext given the ciphertext
Previously the length of the SM2 plaintext could be incorrectly calculated.
The plaintext length was calculated by taking the ciphertext length and
taking off an "overhead" value.

The overhead value was assumed to have a "fixed" element of 10 bytes.
This is incorrect since in some circumstances it can be more than 10 bytes.
Additionally the overhead included the length of two integers C1x and C1y,
which were assumed to be the same length as the field size (32 bytes for
the SM2 curve). However in some cases these integers can have an additional
padding byte when the msb is set, to disambiguate them from negative
integers. Additionally the integers can also be less than 32 bytes in
length in some cases.

If the calculated overhead is incorrect and larger than the actual value
this can result in the calculated plaintext length being too small.
Applications are likely to allocate buffer sizes based on this and therefore
a buffer overrun can occur.

CVE-2021-3711

Issue reported by John Ouyang.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
2021-08-24 14:22:07 +01:00

388 lines
12 KiB
C

/*
* Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* Low level APIs are deprecated for public use, but still ok for internal use.
*/
#include "internal/deprecated.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include "testutil.h"
#ifndef OPENSSL_NO_SM2
# include "crypto/sm2.h"
static fake_random_generate_cb get_faked_bytes;
static OSSL_PROVIDER *fake_rand = NULL;
static uint8_t *fake_rand_bytes = NULL;
static size_t fake_rand_bytes_offset = 0;
static size_t fake_rand_size = 0;
static int get_faked_bytes(unsigned char *buf, size_t num,
ossl_unused const char *name,
ossl_unused EVP_RAND_CTX *ctx)
{
if (!TEST_ptr(fake_rand_bytes) || !TEST_size_t_gt(fake_rand_size, 0))
return 0;
while (num-- > 0) {
if (fake_rand_bytes_offset >= fake_rand_size)
fake_rand_bytes_offset = 0;
*buf++ = fake_rand_bytes[fake_rand_bytes_offset++];
}
return 1;
}
static int start_fake_rand(const char *hex_bytes)
{
OPENSSL_free(fake_rand_bytes);
fake_rand_bytes_offset = 0;
fake_rand_size = strlen(hex_bytes) / 2;
if (!TEST_ptr(fake_rand_bytes = OPENSSL_hexstr2buf(hex_bytes, NULL)))
return 0;
/* use own random function */
fake_rand_set_public_private_callbacks(NULL, get_faked_bytes);
return 1;
}
static void restore_rand(void)
{
fake_rand_set_public_private_callbacks(NULL, NULL);
OPENSSL_free(fake_rand_bytes);
fake_rand_bytes = NULL;
fake_rand_bytes_offset = 0;
}
static EC_GROUP *create_EC_group(const char *p_hex, const char *a_hex,
const char *b_hex, const char *x_hex,
const char *y_hex, const char *order_hex,
const char *cof_hex)
{
BIGNUM *p = NULL;
BIGNUM *a = NULL;
BIGNUM *b = NULL;
BIGNUM *g_x = NULL;
BIGNUM *g_y = NULL;
BIGNUM *order = NULL;
BIGNUM *cof = NULL;
EC_POINT *generator = NULL;
EC_GROUP *group = NULL;
int ok = 0;
if (!TEST_true(BN_hex2bn(&p, p_hex))
|| !TEST_true(BN_hex2bn(&a, a_hex))
|| !TEST_true(BN_hex2bn(&b, b_hex)))
goto done;
group = EC_GROUP_new_curve_GFp(p, a, b, NULL);
if (!TEST_ptr(group))
goto done;
generator = EC_POINT_new(group);
if (!TEST_ptr(generator))
goto done;
if (!TEST_true(BN_hex2bn(&g_x, x_hex))
|| !TEST_true(BN_hex2bn(&g_y, y_hex))
|| !TEST_true(EC_POINT_set_affine_coordinates(group, generator, g_x,
g_y, NULL)))
goto done;
if (!TEST_true(BN_hex2bn(&order, order_hex))
|| !TEST_true(BN_hex2bn(&cof, cof_hex))
|| !TEST_true(EC_GROUP_set_generator(group, generator, order, cof)))
goto done;
ok = 1;
done:
BN_free(p);
BN_free(a);
BN_free(b);
BN_free(g_x);
BN_free(g_y);
EC_POINT_free(generator);
BN_free(order);
BN_free(cof);
if (!ok) {
EC_GROUP_free(group);
group = NULL;
}
return group;
}
static int test_sm2_crypt(const EC_GROUP *group,
const EVP_MD *digest,
const char *privkey_hex,
const char *message,
const char *k_hex, const char *ctext_hex)
{
const size_t msg_len = strlen(message);
BIGNUM *priv = NULL;
EC_KEY *key = NULL;
EC_POINT *pt = NULL;
unsigned char *expected = OPENSSL_hexstr2buf(ctext_hex, NULL);
size_t ctext_len = 0;
size_t ptext_len = 0;
uint8_t *ctext = NULL;
uint8_t *recovered = NULL;
size_t recovered_len = msg_len;
int rc = 0;
if (!TEST_ptr(expected)
|| !TEST_true(BN_hex2bn(&priv, privkey_hex)))
goto done;
key = EC_KEY_new();
if (!TEST_ptr(key)
|| !TEST_true(EC_KEY_set_group(key, group))
|| !TEST_true(EC_KEY_set_private_key(key, priv)))
goto done;
pt = EC_POINT_new(group);
if (!TEST_ptr(pt)
|| !TEST_true(EC_POINT_mul(group, pt, priv, NULL, NULL, NULL))
|| !TEST_true(EC_KEY_set_public_key(key, pt))
|| !TEST_true(ossl_sm2_ciphertext_size(key, digest, msg_len,
&ctext_len)))
goto done;
ctext = OPENSSL_zalloc(ctext_len);
if (!TEST_ptr(ctext))
goto done;
start_fake_rand(k_hex);
if (!TEST_true(ossl_sm2_encrypt(key, digest,
(const uint8_t *)message, msg_len,
ctext, &ctext_len))) {
restore_rand();
goto done;
}
restore_rand();
if (!TEST_mem_eq(ctext, ctext_len, expected, ctext_len))
goto done;
if (!TEST_true(ossl_sm2_plaintext_size(ctext, ctext_len, &ptext_len))
|| !TEST_int_eq(ptext_len, msg_len))
goto done;
recovered = OPENSSL_zalloc(ptext_len);
if (!TEST_ptr(recovered)
|| !TEST_true(ossl_sm2_decrypt(key, digest, ctext, ctext_len,
recovered, &recovered_len))
|| !TEST_int_eq(recovered_len, msg_len)
|| !TEST_mem_eq(recovered, recovered_len, message, msg_len))
goto done;
rc = 1;
done:
BN_free(priv);
EC_POINT_free(pt);
OPENSSL_free(ctext);
OPENSSL_free(recovered);
OPENSSL_free(expected);
EC_KEY_free(key);
return rc;
}
static int sm2_crypt_test(void)
{
int testresult = 0;
EC_GROUP *test_group =
create_EC_group
("8542D69E4C044F18E8B92435BF6FF7DE457283915C45517D722EDB8B08F1DFC3",
"787968B4FA32C3FD2417842E73BBFEFF2F3C848B6831D7E0EC65228B3937E498",
"63E4C6D3B23B0C849CF84241484BFE48F61D59A5B16BA06E6E12D1DA27C5249A",
"421DEBD61B62EAB6746434EBC3CC315E32220B3BADD50BDC4C4E6C147FEDD43D",
"0680512BCBB42C07D47349D2153B70C4E5D7FDFCBFA36EA1A85841B9E46E09A2",
"8542D69E4C044F18E8B92435BF6FF7DD297720630485628D5AE74EE7C32E79B7",
"1");
if (!TEST_ptr(test_group))
goto done;
if (!test_sm2_crypt(
test_group,
EVP_sm3(),
"1649AB77A00637BD5E2EFE283FBF353534AA7F7CB89463F208DDBC2920BB0DA0",
"encryption standard",
"004C62EEFD6ECFC2B95B92FD6C3D9575148AFA17425546D49018E5388D49DD7B4F"
"0092e8ff62146873c258557548500ab2df2a365e0609ab67640a1f6d57d7b17820"
"008349312695a3e1d2f46905f39a766487f2432e95d6be0cb009fe8c69fd8825a7",
"307B0220245C26FB68B1DDDDB12C4B6BF9F2B6D5FE60A383B0D18D1C4144ABF1"
"7F6252E7022076CB9264C2A7E88E52B19903FDC47378F605E36811F5C07423A2"
"4B84400F01B804209C3D7360C30156FAB7C80A0276712DA9D8094A634B766D3A"
"285E07480653426D0413650053A89B41C418B0C3AAD00D886C00286467"))
goto done;
/* Same test as above except using SHA-256 instead of SM3 */
if (!test_sm2_crypt(
test_group,
EVP_sha256(),
"1649AB77A00637BD5E2EFE283FBF353534AA7F7CB89463F208DDBC2920BB0DA0",
"encryption standard",
"004C62EEFD6ECFC2B95B92FD6C3D9575148AFA17425546D49018E5388D49DD7B4F"
"003da18008784352192d70f22c26c243174a447ba272fec64163dd4742bae8bc98"
"00df17605cf304e9dd1dfeb90c015e93b393a6f046792f790a6fa4228af67d9588",
"307B0220245C26FB68B1DDDDB12C4B6BF9F2B6D5FE60A383B0D18D1C4144ABF17F"
"6252E7022076CB9264C2A7E88E52B19903FDC47378F605E36811F5C07423A24B84"
"400F01B80420BE89139D07853100EFA763F60CBE30099EA3DF7F8F364F9D10A5E9"
"88E3C5AAFC0413229E6C9AEE2BB92CAD649FE2C035689785DA33"))
goto done;
testresult = 1;
done:
EC_GROUP_free(test_group);
return testresult;
}
static int test_sm2_sign(const EC_GROUP *group,
const char *userid,
const char *privkey_hex,
const char *message,
const char *k_hex,
const char *r_hex,
const char *s_hex)
{
const size_t msg_len = strlen(message);
int ok = 0;
BIGNUM *priv = NULL;
EC_POINT *pt = NULL;
EC_KEY *key = NULL;
ECDSA_SIG *sig = NULL;
const BIGNUM *sig_r = NULL;
const BIGNUM *sig_s = NULL;
BIGNUM *r = NULL;
BIGNUM *s = NULL;
if (!TEST_true(BN_hex2bn(&priv, privkey_hex)))
goto done;
key = EC_KEY_new();
if (!TEST_ptr(key)
|| !TEST_true(EC_KEY_set_group(key, group))
|| !TEST_true(EC_KEY_set_private_key(key, priv)))
goto done;
pt = EC_POINT_new(group);
if (!TEST_ptr(pt)
|| !TEST_true(EC_POINT_mul(group, pt, priv, NULL, NULL, NULL))
|| !TEST_true(EC_KEY_set_public_key(key, pt)))
goto done;
start_fake_rand(k_hex);
sig = ossl_sm2_do_sign(key, EVP_sm3(), (const uint8_t *)userid,
strlen(userid), (const uint8_t *)message, msg_len);
if (!TEST_ptr(sig)) {
restore_rand();
goto done;
}
restore_rand();
ECDSA_SIG_get0(sig, &sig_r, &sig_s);
if (!TEST_true(BN_hex2bn(&r, r_hex))
|| !TEST_true(BN_hex2bn(&s, s_hex))
|| !TEST_BN_eq(r, sig_r)
|| !TEST_BN_eq(s, sig_s))
goto done;
ok = ossl_sm2_do_verify(key, EVP_sm3(), sig, (const uint8_t *)userid,
strlen(userid), (const uint8_t *)message, msg_len);
/* We goto done whether this passes or fails */
TEST_true(ok);
done:
ECDSA_SIG_free(sig);
EC_POINT_free(pt);
EC_KEY_free(key);
BN_free(priv);
BN_free(r);
BN_free(s);
return ok;
}
static int sm2_sig_test(void)
{
int testresult = 0;
/* From draft-shen-sm2-ecdsa-02 */
EC_GROUP *test_group =
create_EC_group
("8542D69E4C044F18E8B92435BF6FF7DE457283915C45517D722EDB8B08F1DFC3",
"787968B4FA32C3FD2417842E73BBFEFF2F3C848B6831D7E0EC65228B3937E498",
"63E4C6D3B23B0C849CF84241484BFE48F61D59A5B16BA06E6E12D1DA27C5249A",
"421DEBD61B62EAB6746434EBC3CC315E32220B3BADD50BDC4C4E6C147FEDD43D",
"0680512BCBB42C07D47349D2153B70C4E5D7FDFCBFA36EA1A85841B9E46E09A2",
"8542D69E4C044F18E8B92435BF6FF7DD297720630485628D5AE74EE7C32E79B7",
"1");
if (!TEST_ptr(test_group))
goto done;
if (!TEST_true(test_sm2_sign(
test_group,
"ALICE123@YAHOO.COM",
"128B2FA8BD433C6C068C8D803DFF79792A519A55171B1B650C23661D15897263",
"message digest",
"006CB28D99385C175C94F94E934817663FC176D925DD72B727260DBAAE1FB2F96F"
"007c47811054c6f99613a578eb8453706ccb96384fe7df5c171671e760bfa8be3a",
"40F1EC59F793D9F49E09DCEF49130D4194F79FB1EED2CAA55BACDB49C4E755D1",
"6FC6DAC32C5D5CF10C77DFB20F7C2EB667A457872FB09EC56327A67EC7DEEBE7")))
goto done;
testresult = 1;
done:
EC_GROUP_free(test_group);
return testresult;
}
#endif
int setup_tests(void)
{
#ifdef OPENSSL_NO_SM2
TEST_note("SM2 is disabled.");
#else
fake_rand = fake_rand_start(NULL);
if (fake_rand == NULL)
return 0;
ADD_TEST(sm2_crypt_test);
ADD_TEST(sm2_sig_test);
#endif
return 1;
}
void cleanup_tests(void)
{
#ifndef OPENSSL_NO_SM2
fake_rand_finish(fake_rand);
#endif
}