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openssl/crypto/rsa/rsa_ossl.c
Matt Caswell fd7d252060 Tighten up BN_with_flags usage and avoid a reachable assert 
The function rsa_ossl_mod_exp uses the function BN_with_flags to create a
temporary copy (local_r1) of a BIGNUM (r1) with modified flags. This
temporary copy shares some state with the original r1. If the state of r1
gets updated then local_r1's state will be stale. This was occurring in the
function so that when local_r1 was freed a call to bn_check_top was made
which failed an assert due to the stale state. To resolve this we must free
local_r1 immediately after we have finished using it and not wait until the
end of the function.

This problem prompted a review of all BN_with_flag usage within the
codebase. All other usage appears to be correct, although often not
obviously so. This commit refactors things to make it much clearer for
these other uses.

Reviewed-by: Emilia Käsper <emilia@openssl.org>
2015-11-26 10:20:36 +00:00

956 lines
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
/* ====================================================================
* Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
#include "internal/cryptlib.h"
#include "internal/bn_int.h"
#include <openssl/rsa.h>
#include <openssl/rand.h>
#ifndef RSA_NULL
static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa,
BN_CTX *ctx);
static int rsa_ossl_init(RSA *rsa);
static int rsa_ossl_finish(RSA *rsa);
static RSA_METHOD rsa_pkcs1_ossl_meth = {
"OpenSSL PKCS#1 RSA (from Eric Young)",
rsa_ossl_public_encrypt,
rsa_ossl_public_decrypt, /* signature verification */
rsa_ossl_private_encrypt, /* signing */
rsa_ossl_private_decrypt,
rsa_ossl_mod_exp,
BN_mod_exp_mont, /* XXX probably we should not use Montgomery
* if e == 3 */
rsa_ossl_init,
rsa_ossl_finish,
RSA_FLAG_FIPS_METHOD, /* flags */
NULL,
0, /* rsa_sign */
0, /* rsa_verify */
NULL /* rsa_keygen */
};
const RSA_METHOD *RSA_PKCS1_OpenSSL(void)
{
return &rsa_pkcs1_ossl_meth;
}
static int rsa_ossl_public_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
{
BIGNUM *f, *ret;
int i, j, k, num = 0, r = -1;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
return -1;
}
if (BN_ucmp(rsa->n, rsa->e) <= 0) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
return -1;
}
/* for large moduli, enforce exponent limit */
if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
return -1;
}
}
if ((ctx = BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
f = BN_CTX_get(ctx);
ret = BN_CTX_get(ctx);
num = BN_num_bytes(rsa->n);
buf = OPENSSL_malloc(num);
if (f == NULL || ret == NULL || buf == NULL) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
switch (padding) {
case RSA_PKCS1_PADDING:
i = RSA_padding_add_PKCS1_type_2(buf, num, from, flen);
break;
case RSA_PKCS1_OAEP_PADDING:
i = RSA_padding_add_PKCS1_OAEP(buf, num, from, flen, NULL, 0);
break;
case RSA_SSLV23_PADDING:
i = RSA_padding_add_SSLv23(buf, num, from, flen);
break;
case RSA_NO_PADDING:
i = RSA_padding_add_none(buf, num, from, flen);
break;
default:
RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
goto err;
}
if (i <= 0)
goto err;
if (BN_bin2bn(buf, num, f) == NULL)
goto err;
if (BN_ucmp(f, rsa->n) >= 0) {
/* usually the padding functions would catch this */
RSAerr(RSA_F_RSA_OSSL_PUBLIC_ENCRYPT,
RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
goto err;
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
if (!BN_MONT_CTX_set_locked
(&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
goto err;
if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
rsa->_method_mod_n))
goto err;
/*
* put in leading 0 bytes if the number is less than the length of the
* modulus
*/
j = BN_num_bytes(ret);
i = BN_bn2bin(ret, &(to[num - j]));
for (k = 0; k < (num - i); k++)
to[k] = 0;
r = num;
err:
if (ctx != NULL)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
OPENSSL_clear_free(buf, num);
return (r);
}
static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
{
BN_BLINDING *ret;
int got_write_lock = 0;
CRYPTO_THREADID cur;
CRYPTO_r_lock(CRYPTO_LOCK_RSA);
if (rsa->blinding == NULL) {
CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
CRYPTO_w_lock(CRYPTO_LOCK_RSA);
got_write_lock = 1;
if (rsa->blinding == NULL)
rsa->blinding = RSA_setup_blinding(rsa, ctx);
}
ret = rsa->blinding;
if (ret == NULL)
goto err;
CRYPTO_THREADID_current(&cur);
if (!CRYPTO_THREADID_cmp(&cur, BN_BLINDING_thread_id(ret))) {
/* rsa->blinding is ours! */
*local = 1;
} else {
/* resort to rsa->mt_blinding instead */
/*
* instructs rsa_blinding_convert(), rsa_blinding_invert() that the
* BN_BLINDING is shared, meaning that accesses require locks, and
* that the blinding factor must be stored outside the BN_BLINDING
*/
*local = 0;
if (rsa->mt_blinding == NULL) {
if (!got_write_lock) {
CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
CRYPTO_w_lock(CRYPTO_LOCK_RSA);
got_write_lock = 1;
}
if (rsa->mt_blinding == NULL)
rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
}
ret = rsa->mt_blinding;
}
err:
if (got_write_lock)
CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
else
CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
return ret;
}
static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
BN_CTX *ctx)
{
if (unblind == NULL)
/*
* Local blinding: store the unblinding factor in BN_BLINDING.
*/
return BN_BLINDING_convert_ex(f, NULL, b, ctx);
else {
/*
* Shared blinding: store the unblinding factor outside BN_BLINDING.
*/
int ret;
CRYPTO_w_lock(CRYPTO_LOCK_RSA_BLINDING);
ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
CRYPTO_w_unlock(CRYPTO_LOCK_RSA_BLINDING);
return ret;
}
}
static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
BN_CTX *ctx)
{
/*
* For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
* will use the unblinding factor stored in BN_BLINDING. If BN_BLINDING
* is shared between threads, unblind must be non-null:
* BN_BLINDING_invert_ex will then use the local unblinding factor, and
* will only read the modulus from BN_BLINDING. In both cases it's safe
* to access the blinding without a lock.
*/
return BN_BLINDING_invert_ex(f, unblind, b, ctx);
}
/* signing */
static int rsa_ossl_private_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
{
BIGNUM *f, *ret, *res;
int i, j, k, num = 0, r = -1;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
int local_blinding = 0;
/*
* Used only if the blinding structure is shared. A non-NULL unblind
* instructs rsa_blinding_convert() and rsa_blinding_invert() to store
* the unblinding factor outside the blinding structure.
*/
BIGNUM *unblind = NULL;
BN_BLINDING *blinding = NULL;
if ((ctx = BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
f = BN_CTX_get(ctx);
ret = BN_CTX_get(ctx);
num = BN_num_bytes(rsa->n);
buf = OPENSSL_malloc(num);
if (f == NULL || ret == NULL || buf == NULL) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
switch (padding) {
case RSA_PKCS1_PADDING:
i = RSA_padding_add_PKCS1_type_1(buf, num, from, flen);
break;
case RSA_X931_PADDING:
i = RSA_padding_add_X931(buf, num, from, flen);
break;
case RSA_NO_PADDING:
i = RSA_padding_add_none(buf, num, from, flen);
break;
case RSA_SSLV23_PADDING:
default:
RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
goto err;
}
if (i <= 0)
goto err;
if (BN_bin2bn(buf, num, f) == NULL)
goto err;
if (BN_ucmp(f, rsa->n) >= 0) {
/* usually the padding functions would catch this */
RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT,
RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
goto err;
}
if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
if (blinding == NULL) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
goto err;
}
}
if (blinding != NULL) {
if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!rsa_blinding_convert(blinding, f, unblind, ctx))
goto err;
}
if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
((rsa->p != NULL) &&
(rsa->q != NULL) &&
(rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
goto err;
} else {
BIGNUM *d = NULL, *local_d = NULL;
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
local_d = d = BN_new();
if (d == NULL) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
} else {
d = rsa->d;
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
if (!BN_MONT_CTX_set_locked
(&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx)) {
BN_free(local_d);
goto err;
}
if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
rsa->_method_mod_n)) {
BN_free(local_d);
goto err;
}
/* We MUST free local_d before any further use of rsa->d */
BN_free(local_d);
}
if (blinding)
if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
goto err;
if (padding == RSA_X931_PADDING) {
BN_sub(f, rsa->n, ret);
if (BN_cmp(ret, f) > 0)
res = f;
else
res = ret;
} else
res = ret;
/*
* put in leading 0 bytes if the number is less than the length of the
* modulus
*/
j = BN_num_bytes(res);
i = BN_bn2bin(res, &(to[num - j]));
for (k = 0; k < (num - i); k++)
to[k] = 0;
r = num;
err:
if (ctx != NULL)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
OPENSSL_clear_free(buf, num);
return (r);
}
static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
{
BIGNUM *f, *ret;
int j, num = 0, r = -1;
unsigned char *p;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
int local_blinding = 0;
/*
* Used only if the blinding structure is shared. A non-NULL unblind
* instructs rsa_blinding_convert() and rsa_blinding_invert() to store
* the unblinding factor outside the blinding structure.
*/
BIGNUM *unblind = NULL;
BN_BLINDING *blinding = NULL;
if ((ctx = BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
f = BN_CTX_get(ctx);
ret = BN_CTX_get(ctx);
num = BN_num_bytes(rsa->n);
buf = OPENSSL_malloc(num);
if (f == NULL || ret == NULL || buf == NULL) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
/*
* This check was for equality but PGP does evil things and chops off the
* top '0' bytes
*/
if (flen > num) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
RSA_R_DATA_GREATER_THAN_MOD_LEN);
goto err;
}
/* make data into a big number */
if (BN_bin2bn(from, (int)flen, f) == NULL)
goto err;
if (BN_ucmp(f, rsa->n) >= 0) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT,
RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
goto err;
}
if (!(rsa->flags & RSA_FLAG_NO_BLINDING)) {
blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
if (blinding == NULL) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
goto err;
}
}
if (blinding != NULL) {
if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL)) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!rsa_blinding_convert(blinding, f, unblind, ctx))
goto err;
}
/* do the decrypt */
if ((rsa->flags & RSA_FLAG_EXT_PKEY) ||
((rsa->p != NULL) &&
(rsa->q != NULL) &&
(rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL))) {
if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx))
goto err;
} else {
BIGNUM *d = NULL, *local_d = NULL;
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
local_d = d = BN_new();
if (d == NULL) {
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
} else {
d = rsa->d;
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
if (!BN_MONT_CTX_set_locked
(&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx)) {
BN_free(local_d);
goto err;
}
if (!rsa->meth->bn_mod_exp(ret, f, d, rsa->n, ctx,
rsa->_method_mod_n)) {
BN_free(local_d);
goto err;
}
/* We MUST free local_d before any further use of rsa->d */
BN_free(local_d);
}
if (blinding)
if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
goto err;
p = buf;
j = BN_bn2bin(ret, p); /* j is only used with no-padding mode */
switch (padding) {
case RSA_PKCS1_PADDING:
r = RSA_padding_check_PKCS1_type_2(to, num, buf, j, num);
break;
case RSA_PKCS1_OAEP_PADDING:
r = RSA_padding_check_PKCS1_OAEP(to, num, buf, j, num, NULL, 0);
break;
case RSA_SSLV23_PADDING:
r = RSA_padding_check_SSLv23(to, num, buf, j, num);
break;
case RSA_NO_PADDING:
r = RSA_padding_check_none(to, num, buf, j, num);
break;
default:
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
goto err;
}
if (r < 0)
RSAerr(RSA_F_RSA_OSSL_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
err:
if (ctx != NULL)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
OPENSSL_clear_free(buf, num);
return (r);
}
/* signature verification */
static int rsa_ossl_public_decrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
{
BIGNUM *f, *ret;
int i, num = 0, r = -1;
unsigned char *p;
unsigned char *buf = NULL;
BN_CTX *ctx = NULL;
if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
return -1;
}
if (BN_ucmp(rsa->n, rsa->e) <= 0) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
return -1;
}
/* for large moduli, enforce exponent limit */
if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS) {
if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
return -1;
}
}
if ((ctx = BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
f = BN_CTX_get(ctx);
ret = BN_CTX_get(ctx);
num = BN_num_bytes(rsa->n);
buf = OPENSSL_malloc(num);
if (f == NULL || ret == NULL || buf == NULL) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, ERR_R_MALLOC_FAILURE);
goto err;
}
/*
* This check was for equality but PGP does evil things and chops off the
* top '0' bytes
*/
if (flen > num) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_DATA_GREATER_THAN_MOD_LEN);
goto err;
}
if (BN_bin2bn(from, flen, f) == NULL)
goto err;
if (BN_ucmp(f, rsa->n) >= 0) {
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT,
RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
goto err;
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
if (!BN_MONT_CTX_set_locked
(&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
goto err;
if (!rsa->meth->bn_mod_exp(ret, f, rsa->e, rsa->n, ctx,
rsa->_method_mod_n))
goto err;
if ((padding == RSA_X931_PADDING) && ((bn_get_words(ret)[0] & 0xf) != 12))
if (!BN_sub(ret, rsa->n, ret))
goto err;
p = buf;
i = BN_bn2bin(ret, p);
switch (padding) {
case RSA_PKCS1_PADDING:
r = RSA_padding_check_PKCS1_type_1(to, num, buf, i, num);
break;
case RSA_X931_PADDING:
r = RSA_padding_check_X931(to, num, buf, i, num);
break;
case RSA_NO_PADDING:
r = RSA_padding_check_none(to, num, buf, i, num);
break;
default:
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
goto err;
}
if (r < 0)
RSAerr(RSA_F_RSA_OSSL_PUBLIC_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
err:
if (ctx != NULL)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
OPENSSL_clear_free(buf, num);
return (r);
}
static int rsa_ossl_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
{
BIGNUM *r1, *m1, *vrfy;
int ret = 0;
BN_CTX_start(ctx);
r1 = BN_CTX_get(ctx);
m1 = BN_CTX_get(ctx);
vrfy = BN_CTX_get(ctx);
{
BIGNUM *local_p = NULL, *local_q = NULL;
BIGNUM *p = NULL, *q = NULL;
/*
* Make sure BN_mod_inverse in Montgomery intialization uses the
* BN_FLG_CONSTTIME flag (unless RSA_FLAG_NO_CONSTTIME is set)
*/
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
local_p = p = BN_new();
if (p == NULL)
goto err;
BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
local_q = q = BN_new();
if (q == NULL) {
BN_free(local_p);
goto err;
}
BN_with_flags(q, rsa->q, BN_FLG_CONSTTIME);
} else {
p = rsa->p;
q = rsa->q;
}
if (rsa->flags & RSA_FLAG_CACHE_PRIVATE) {
if (!BN_MONT_CTX_set_locked
(&rsa->_method_mod_p, CRYPTO_LOCK_RSA, p, ctx)
|| !BN_MONT_CTX_set_locked(&rsa->_method_mod_q,
CRYPTO_LOCK_RSA, q, ctx)) {
BN_free(local_p);
BN_free(local_q);
goto err;
}
}
/*
* We MUST free local_p and local_q before any further use of rsa->p and
* rsa->q
*/
BN_free(local_p);
BN_free(local_q);
}
if (rsa->flags & RSA_FLAG_CACHE_PUBLIC)
if (!BN_MONT_CTX_set_locked
(&rsa->_method_mod_n, CRYPTO_LOCK_RSA, rsa->n, ctx))
goto err;
/* compute I mod q */
{
BIGNUM *local_c = NULL;
const BIGNUM *c;
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
local_c = BN_new();
if (local_c == NULL)
goto err;
BN_with_flags(local_c, I, BN_FLG_CONSTTIME);
c = local_c;
} else {
c = I;
}
if (!BN_mod(r1, c, rsa->q, ctx)) {
BN_free(local_c);
goto err;
}
{
BIGNUM *local_dmq1 = NULL, *dmq1;
/* compute r1^dmq1 mod q */
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
dmq1 = local_dmq1 = BN_new();
if (local_dmq1 == NULL) {
BN_free(local_c);
goto err;
}
BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
} else {
dmq1 = rsa->dmq1;
}
if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx,
rsa->_method_mod_q)) {
BN_free(local_c);
BN_free(local_dmq1);
goto err;
}
/* We MUST free local_dmq1 before any further use of rsa->dmq1 */
BN_free(local_dmq1);
}
/* compute I mod p */
if (!BN_mod(r1, c, rsa->p, ctx)) {
BN_free(local_c);
goto err;
}
/* We MUST free local_c before any further use of I */
BN_free(local_c);
}
{
BIGNUM *local_dmp1 = NULL, *dmp1;
/* compute r1^dmp1 mod p */
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
dmp1 = local_dmp1 = BN_new();
if (local_dmp1 == NULL)
goto err;
BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
} else {
dmp1 = rsa->dmp1;
}
if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx,
rsa->_method_mod_p)) {
BN_free(local_dmp1);
goto err;
}
/* We MUST free local_dmp1 before any further use of rsa->dmp1 */
BN_free(local_dmp1);
}
if (!BN_sub(r0, r0, m1))
goto err;
/*
* This will help stop the size of r0 increasing, which does affect the
* multiply if it optimised for a power of 2 size
*/
if (BN_is_negative(r0))
if (!BN_add(r0, r0, rsa->p))
goto err;
if (!BN_mul(r1, r0, rsa->iqmp, ctx))
goto err;
{
BIGNUM *local_r1 = NULL, *pr1;
/* Turn BN_FLG_CONSTTIME flag on before division operation */
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
pr1 = local_r1 = BN_new();
if (local_r1 == NULL)
goto err;
BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
} else {
pr1 = r1;
}
if (!BN_mod(r0, pr1, rsa->p, ctx)) {
BN_free(local_r1);
goto err;
}
/* We MUST free local_r1 before any further use of r1 */
BN_free(local_r1);
}
/*
* If p < q it is occasionally possible for the correction of adding 'p'
* if r0 is negative above to leave the result still negative. This can
* break the private key operations: the following second correction
* should *always* correct this rare occurrence. This will *never* happen
* with OpenSSL generated keys because they ensure p > q [steve]
*/
if (BN_is_negative(r0))
if (!BN_add(r0, r0, rsa->p))
goto err;
if (!BN_mul(r1, r0, rsa->q, ctx))
goto err;
if (!BN_add(r0, r1, m1))
goto err;
if (rsa->e && rsa->n) {
if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx,
rsa->_method_mod_n))
goto err;
/*
* If 'I' was greater than (or equal to) rsa->n, the operation will
* be equivalent to using 'I mod n'. However, the result of the
* verify will *always* be less than 'n' so we don't check for
* absolute equality, just congruency.
*/
if (!BN_sub(vrfy, vrfy, I))
goto err;
if (!BN_mod(vrfy, vrfy, rsa->n, ctx))
goto err;
if (BN_is_negative(vrfy))
if (!BN_add(vrfy, vrfy, rsa->n))
goto err;
if (!BN_is_zero(vrfy)) {
/*
* 'I' and 'vrfy' aren't congruent mod n. Don't leak
* miscalculated CRT output, just do a raw (slower) mod_exp and
* return that instead.
*/
BIGNUM *local_d = NULL;
BIGNUM *d = NULL;
if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
local_d = d = BN_new();
if (d == NULL)
goto err;
BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
} else {
d = rsa->d;
}
if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx,
rsa->_method_mod_n)) {
BN_free(local_d);
goto err;
}
/* We MUST free local_d before any further use of rsa->d */
BN_free(local_d);
}
}
ret = 1;
err:
BN_CTX_end(ctx);
return (ret);
}
static int rsa_ossl_init(RSA *rsa)
{
rsa->flags |= RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE;
return (1);
}
static int rsa_ossl_finish(RSA *rsa)
{
BN_MONT_CTX_free(rsa->_method_mod_n);
BN_MONT_CTX_free(rsa->_method_mod_p);
BN_MONT_CTX_free(rsa->_method_mod_q);
return (1);
}
#endif
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