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pk: properly handle signatures in larger buffers when using PSA

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As stated in function documentation.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
This commit is contained in:
Andrzej Kurek 2022-02-16 06:13:35 -05:00
parent 8666df6f18
commit 4a953cdd9f
1 changed files with 9 additions and 2 deletions
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11
library/pk.c
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@ -379,7 +379,7 @@ int mbedtls_pk_verify_ext( mbedtls_pk_type_t type, const void *options,
/* see RSA_PUB_DER_MAX_BYTES in pkwrite.c */
unsigned char buf[ 38 + 2 * MBEDTLS_MPI_MAX_SIZE ];
unsigned char *p;
int key_len;
int key_len, signature_length;
psa_algorithm_t psa_md_alg = mbedtls_psa_translate_md( md_alg );
mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
@ -406,8 +406,15 @@ int mbedtls_pk_verify_ext( mbedtls_pk_type_t type, const void *options,
return( mbedtls_psa_err_translate_pk( status ) );
}
/* This function requires returning MBEDTLS_ERR_PK_SIG_LEN_MISMATCH
* on a valid signature with trailing data in a buffer, but
* mbedtls_psa_rsa_verify_hash requires the sig_len to be exact,
* so for this reason the passed sig_len is overwritten. Smaller
* signature lengths should not be accepted for verification. */
signature_length = sig_len > mbedtls_pk_get_len( ctx ) ?
mbedtls_pk_get_len( ctx ) : sig_len;
status = psa_verify_hash( key_id, psa_sig_alg, hash,
hash_len, sig, sig_len );
hash_len, sig, signature_length );
psa_destroy_key( key_id );
if( status == PSA_SUCCESS && sig_len > mbedtls_pk_get_len( ctx ) )