Add output size parameter to signature functions
The functions mbedtls_pk_sign(), mbedtls_pk_sign_restartable(),
mbedtls_ecdsa_write_signature() and mbedtls_ecdsa_write_signature_restartable()
now take an extra parameter indicating the size of the output buffer for the
signature.
No change to RSA because for RSA, the output size is trivial to calculate.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/pk_wrap.c b/library/pk_wrap.c
index 864e495..0aa2357 100644
--- a/library/pk_wrap.c
+++ b/library/pk_wrap.c
@@ -108,7 +108,7 @@
static int rsa_sign_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
mbedtls_rsa_context * rsa = (mbedtls_rsa_context *) ctx;
@@ -119,6 +119,8 @@
#endif /* SIZE_MAX > UINT_MAX */
*sig_len = mbedtls_rsa_get_len( rsa );
+ if( sig_size < *sig_len )
+ return( MBEDTLS_ERR_PK_BUFFER_TOO_SMALL );
return( mbedtls_rsa_pkcs1_sign( rsa, f_rng, p_rng,
md_alg, (unsigned int) hash_len,
@@ -247,7 +249,7 @@
static int ecdsa_sign_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
static int eckey_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
@@ -269,7 +271,7 @@
static int eckey_sign_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
@@ -278,7 +280,8 @@
mbedtls_ecdsa_init( &ecdsa );
if( ( ret = mbedtls_ecdsa_from_keypair( &ecdsa, ctx ) ) == 0 )
- ret = ecdsa_sign_wrap( &ecdsa, md_alg, hash, hash_len, sig, sig_len,
+ ret = ecdsa_sign_wrap( &ecdsa, md_alg, hash, hash_len,
+ sig, sig_size, sig_len,
f_rng, p_rng );
mbedtls_ecdsa_free( &ecdsa );
@@ -295,7 +298,7 @@
static int ecdsa_sign_rs_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
void *rs_ctx );
@@ -367,7 +370,7 @@
static int eckey_sign_rs_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
void *rs_ctx )
{
@@ -383,7 +386,7 @@
MBEDTLS_MPI_CHK( mbedtls_ecdsa_from_keypair( &rs->ecdsa_ctx, ctx ) );
MBEDTLS_MPI_CHK( ecdsa_sign_rs_wrap( &rs->ecdsa_ctx, md_alg,
- hash, hash_len, sig, sig_len,
+ hash, hash_len, sig, sig_size, sig_len,
f_rng, p_rng, &rs->ecdsa_rs ) );
cleanup:
@@ -652,11 +655,13 @@
static int ecdsa_sign_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
return( mbedtls_ecdsa_write_signature( (mbedtls_ecdsa_context *) ctx,
- md_alg, hash, hash_len, sig, sig_len, f_rng, p_rng ) );
+ md_alg, hash, hash_len,
+ sig, sig_size, sig_len,
+ f_rng, p_rng ) );
}
#if defined(MBEDTLS_ECP_RESTARTABLE)
@@ -770,7 +775,7 @@
static int rsa_alt_sign_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
mbedtls_rsa_alt_context *rsa_alt = (mbedtls_rsa_alt_context *) ctx;
@@ -783,6 +788,8 @@
*sig_len = rsa_alt->key_len_func( rsa_alt->key );
if( *sig_len > MBEDTLS_PK_SIGNATURE_MAX_SIZE )
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
+ if( *sig_len > sig_size )
+ return( MBEDTLS_ERR_PK_BUFFER_TOO_SMALL );
return( rsa_alt->sign_func( rsa_alt->key, f_rng, p_rng,
md_alg, (unsigned int) hash_len, hash, sig ) );
@@ -822,7 +829,8 @@
if( ( ret = rsa_alt_sign_wrap( (void *) prv, MBEDTLS_MD_NONE,
hash, sizeof( hash ),
- sig, &sig_len, f_rng, p_rng ) ) != 0 )
+ sig, sizeof( sig ), &sig_len,
+ f_rng, p_rng ) ) != 0 )
{
return( ret );
}
@@ -1010,7 +1018,7 @@
static int pk_opaque_sign_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
- unsigned char *sig, size_t *sig_len,
+ unsigned char *sig, size_t sig_size, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
#if !defined(MBEDTLS_ECDSA_C)
@@ -1019,41 +1027,28 @@
((void) hash);
((void) hash_len);
((void) sig);
+ ((void) sig_size);
((void) sig_len);
((void) f_rng);
((void) p_rng);
return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );
#else /* !MBEDTLS_ECDSA_C */
const psa_key_id_t *key = (const psa_key_id_t *) ctx;
- psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
psa_algorithm_t alg = PSA_ALG_ECDSA( mbedtls_psa_translate_md( md_alg ) );
- size_t buf_len;
psa_status_t status;
/* PSA has its own RNG */
(void) f_rng;
(void) p_rng;
- /* PSA needs an output buffer of known size, but our API doesn't provide
- * that information. Assume that the buffer is large enough for a
- * maximal-length signature with that key (otherwise the application is
- * buggy anyway). */
- status = psa_get_key_attributes( *key, &attributes );
- if( status != PSA_SUCCESS )
- return( mbedtls_psa_err_translate_pk( status ) );
- buf_len = MBEDTLS_ECDSA_MAX_SIG_LEN( psa_get_key_bits( &attributes ) );
- psa_reset_key_attributes( &attributes );
- if( buf_len > MBEDTLS_PK_SIGNATURE_MAX_SIZE )
- return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
-
/* make the signature */
status = psa_sign_hash( *key, alg, hash, hash_len,
- sig, buf_len, sig_len );
+ sig, sig_size, sig_len );
if( status != PSA_SUCCESS )
return( mbedtls_psa_err_translate_pk( status ) );
/* transcode it to ASN.1 sequence */
- return( pk_ecdsa_sig_asn1_from_psa( sig, sig_len, buf_len ) );
+ return( pk_ecdsa_sig_asn1_from_psa( sig, sig_len, sig_size ) );
#endif /* !MBEDTLS_ECDSA_C */
}