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tls: use already existing symbols to size the buffer for XXDḦ peer key

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Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
This commit is contained in:
Valerio Setti 2023-07-10 14:31:39 +02:00
parent aa7cbd619c
commit da403b749e
2 changed files with 4 additions and 26 deletions
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14
library/ssl_misc.h
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@ -757,24 +757,12 @@ struct mbedtls_ssl_handshake_params {
#endif /* !MBEDTLS_USE_PSA_CRYPTO &&
MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_1_2_ENABLED */
#if defined(PSA_WANT_ALG_ECDH) && defined(PSA_WANT_ALG_FFDH)
#if (MBEDTLS_PSA_MAX_FFDH_PUBKEY_LENGTH >= MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH)
#define SSL_XXDH_PSA_PEERKEY_SIZE MBEDTLS_PSA_MAX_FFDH_PUBKEY_LENGTH
#else
#define SSL_XXDH_PSA_PEERKEY_SIZE MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH
#endif
#elif defined(PSA_WANT_ALG_ECDH)
#define SSL_XXDH_PSA_PEERKEY_SIZE MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH
#else
#define SSL_XXDH_PSA_PEERKEY_SIZE MBEDTLS_PSA_MAX_FFDH_PUBKEY_LENGTH
#endif
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED)
psa_key_type_t xxdh_psa_type;
size_t xxdh_bits;
mbedtls_svc_key_id_t xxdh_psa_privkey;
uint8_t xxdh_psa_privkey_is_external;
unsigned char xxdh_psa_peerkey[SSL_XXDH_PSA_PEERKEY_SIZE];
unsigned char xxdh_psa_peerkey[PSA_EXPORT_PUBLIC_KEY_MAX_SIZE];
size_t xxdh_psa_peerkey_len;
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED */

16
library/ssl_tls12_client.c
View file

@ -1774,19 +1774,9 @@ static int ssl_parse_server_ecdh_params(mbedtls_ssl_context *ssl,
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
/* When FFDH is enabled, the array handshake->xxdh_psa_peer_key size takes into account
the sizes of the FFDH keys which are at least 2048 bits.
The size of the array is thus greater than 256 bytes which is greater than any
possible value of ecpoint_len (type uint8_t) and the check below can be skipped.*/
#if !defined(PSA_WANT_ALG_FFDH)
if (ecpoint_len > sizeof(handshake->xxdh_psa_peerkey)) {
return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
}
#else
MBEDTLS_STATIC_ASSERT(sizeof(handshake->xxdh_psa_peerkey) >= UINT8_MAX,
"peer key buffer too small");
#endif
/* xxdh_psa_peerkey is sized after maximum supported FFDH public key.
* PSA_VENDOR_FFDH_MAX_KEY_BITS is always larger than EC public key, so
* we can skip the buffer size check before the memcpy-ing data into it. */
memcpy(handshake->xxdh_psa_peerkey, *p, ecpoint_len);
handshake->xxdh_psa_peerkey_len = ecpoint_len;
*p += ecpoint_len;