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pk_wrap.c: tidy up signature extraction

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Add a sanity check for signature length, remove superfluous bounds check.
This commit is contained in:
Andrzej Kurek 2018-11-20 06:39:06 -05:00
parent e30ad542a1
commit 96cc1b3def
1 changed files with 10 additions and 11 deletions
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21
library/pk_wrap.c
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@ -523,14 +523,6 @@ static int extract_ecdsa_sig( unsigned char **p, const unsigned char *end,
int ret; int ret;
size_t tmp_size; size_t tmp_size;
if( ( end - *p ) < 1 )
{
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
}
if( sig == NULL )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
if( ( ret = mbedtls_asn1_get_tag( p, end, &tmp_size, if( ( ret = mbedtls_asn1_get_tag( p, end, &tmp_size,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
return( ret ); return( ret );
@ -562,7 +554,7 @@ static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
psa_algorithm_t psa_sig_md, psa_md; psa_algorithm_t psa_sig_md, psa_md;
psa_ecc_curve_t curve = mbedtls_psa_translate_ecc_group( psa_ecc_curve_t curve = mbedtls_psa_translate_ecc_group(
( (mbedtls_ecdsa_context *) ctx )->grp.id ); ( (mbedtls_ecdsa_context *) ctx )->grp.id );
size_t signature_part_size = ( ( (mbedtls_ecdsa_context *) ctx ) ->grp.nbits + 7 ) / 8; const size_t signature_part_size = ( ( (mbedtls_ecdsa_context *) ctx )->grp.nbits + 7 ) / 8;
if( curve == 0 ) if( curve == 0 )
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA ); return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
@ -599,19 +591,26 @@ static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
goto cleanup; goto cleanup;
} }
/* Reuse the buffer of an already imported key */ /* We don't need the exported key anymore and can
* reuse its buffer for signature extraction. */
if( 2 * signature_part_size > sizeof( buf ) ) if( 2 * signature_part_size > sizeof( buf ) )
{ {
ret = MBEDTLS_ERR_PK_BAD_INPUT_DATA; ret = MBEDTLS_ERR_PK_BAD_INPUT_DATA;
goto cleanup; goto cleanup;
} }
if( ( ret = extract_ecdsa_sig( &p, p + sig_len, buf, if( ( ret = extract_ecdsa_sig( &p, sig + sig_len, buf,
signature_part_size ) ) != 0 ) signature_part_size ) ) != 0 )
{ {
goto cleanup; goto cleanup;
} }
if( p != sig + sig_len )
{
ret = MBEDTLS_ERR_PK_SIG_LEN_MISMATCH;
goto cleanup;
}
if( psa_asymmetric_verify( key_slot, psa_sig_md, if( psa_asymmetric_verify( key_slot, psa_sig_md,
hash, hash_len, hash, hash_len,
buf, 2 * signature_part_size ) buf, 2 * signature_part_size )