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rsa: introduce rsa_internal_rsassa_pss_sign_no_mode_check()

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And use it in the non-PSA version of mbedtls_pk_sign_ext()
to bypass checks that didn't succeed when used by TLS 1.3.

That is because in the failing scenarios the padding of
the RSA context is not set to PKCS_V21.

See the discussion on PR #7930 for more details.

Signed-off-by: Tomi Fontanilles <129057597+tomi-font@users.noreply.github.com>
This commit is contained in:
Tomi Fontanilles 2023-12-10 14:57:51 +02:00 committed by Tomi Fontanilles
parent 8174662b64
commit 573dc23141
4 changed files with 97 additions and 23 deletions
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5
library/pk.c
View file

@ -18,6 +18,9 @@
#if defined(MBEDTLS_RSA_C)
#include "mbedtls/rsa.h"
#if defined(MBEDTLS_PKCS1_V21) && !defined(MBEDTLS_USE_PSA_CRYPTO)
#include "rsa_internal.h"
#endif
#endif
#if defined(MBEDTLS_PK_HAVE_ECC_KEYS)
#include "mbedtls/ecp.h"
@ -728,7 +731,7 @@ int mbedtls_pk_sign_ext(mbedtls_pk_type_t pk_type,
mbedtls_rsa_context *const rsa_ctx = mbedtls_pk_rsa(*ctx);
const int ret = mbedtls_rsa_rsassa_pss_sign(rsa_ctx, f_rng, p_rng, md_alg,
const int ret = mbedtls_rsa_rsassa_pss_sign_no_mode_check(rsa_ctx, f_rng, p_rng, md_alg,
(unsigned int) hash_len, hash, sig);
if (ret == 0) {
*sig_len = rsa_ctx->len;

51
library/rsa.c
View file

@ -29,6 +29,7 @@
#include "mbedtls/rsa.h"
#include "rsa_alt_helpers.h"
#include "rsa_internal.h"
#include "mbedtls/oid.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
@ -1712,7 +1713,7 @@ int mbedtls_rsa_pkcs1_decrypt(mbedtls_rsa_context *ctx,
}
#if defined(MBEDTLS_PKCS1_V21)
static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
static int rsa_rsassa_pss_sign_no_mode_check(mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
mbedtls_md_type_t md_alg,
@ -1727,15 +1728,12 @@ static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
size_t slen, min_slen, hlen, offset = 0;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t msb;
mbedtls_md_type_t hash_id;
if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
}
if (ctx->padding != MBEDTLS_RSA_PKCS_V21) {
return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
}
if (f_rng == NULL) {
return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
}
@ -1754,7 +1752,11 @@ static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
}
}
hlen = mbedtls_md_get_size_from_type((mbedtls_md_type_t) ctx->hash_id);
hash_id = (mbedtls_md_type_t) ctx->hash_id;
if (hash_id == MBEDTLS_MD_NONE) {
hash_id = md_alg;
}
hlen = mbedtls_md_get_size_from_type(hash_id);
if (hlen == 0) {
return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
}
@ -1797,7 +1799,7 @@ static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
p += slen;
/* Generate H = Hash( M' ) */
ret = hash_mprime(hash, hashlen, salt, slen, p, (mbedtls_md_type_t) ctx->hash_id);
ret = hash_mprime(hash, hashlen, salt, slen, p, hash_id);
if (ret != 0) {
return ret;
}
@ -1808,8 +1810,7 @@ static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
}
/* maskedDB: Apply dbMask to DB */
ret = mgf_mask(sig + offset, olen - hlen - 1 - offset, p, hlen,
(mbedtls_md_type_t) ctx->hash_id);
ret = mgf_mask(sig + offset, olen - hlen - 1 - offset, p, hlen, hash_id);
if (ret != 0) {
return ret;
}
@ -1823,6 +1824,37 @@ static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
return mbedtls_rsa_private(ctx, f_rng, p_rng, sig, sig);
}
static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
int saltlen,
unsigned char *sig)
{
if (ctx->padding != MBEDTLS_RSA_PKCS_V21) {
return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
}
if (ctx->hash_id == MBEDTLS_MD_NONE) {
return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
}
return rsa_rsassa_pss_sign_no_mode_check(ctx, f_rng, p_rng, md_alg, hashlen, hash, saltlen,
sig);
}
int mbedtls_rsa_rsassa_pss_sign_no_mode_check(mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
unsigned char *sig)
{
return rsa_rsassa_pss_sign_no_mode_check(ctx, f_rng, p_rng, md_alg,
hashlen, hash, MBEDTLS_RSA_SALT_LEN_ANY, sig);
}
/*
* Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function with
* the option to pass in the salt length.
@ -1840,7 +1872,6 @@ int mbedtls_rsa_rsassa_pss_sign_ext(mbedtls_rsa_context *ctx,
hashlen, hash, saltlen, sig);
}
/*
* Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function
*/

6
library/rsa_alt_helpers.h
View file

@ -37,11 +37,9 @@
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*
*/
#ifndef MBEDTLS_RSA_INTERNAL_H
#define MBEDTLS_RSA_INTERNAL_H
#ifndef MBEDTLS_RSA_ALT_HELPERS_H
#define MBEDTLS_RSA_ALT_HELPERS_H
#include "mbedtls/build_info.h"

42
library/rsa_internal.h Normal file
View file

@ -0,0 +1,42 @@
/**
* \file rsa_internal.h
*
* \brief Internal-only RSA public-key cryptosystem API.
*
* This file declares RSA-related functions that are to be used
* only from within the Mbed TLS library itself.
*
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#ifndef MBEDTLS_RSA_INTERNAL_H
#define MBEDTLS_RSA_INTERNAL_H
#include "mbedtls/rsa.h"
#if defined(MBEDTLS_PKCS1_V21)
/**
* \brief This function is analogue to \c mbedtls_rsa_rsassa_pss_sign().
* The only difference between them is that this function is more flexible
* on the parameters of \p ctx that are set with \c mbedtls_rsa_set_padding().
*
* \note Compared to its counterpart, this function:
* - does not check the padding setting of \p ctx.
* - allows the hash_id of \p ctx to be MBEDTLS_MD_NONE,
* in which case it uses \p md_alg as the hash_id.
*
* \note Refer to \c mbedtls_rsa_rsassa_pss_sign() for a description
* of the functioning and parameters of this function.
*/
int mbedtls_rsa_rsassa_pss_sign_no_mode_check(mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
unsigned char *sig);
#endif /* MBEDTLS_PKCS1_V21 */
#endif /* rsa_internal.h */