Don't store client-supported ECs in heap-allocated buffer
So far, the client-proposed list of elliptic curves was stored for the
duration of the entire handshake in a heap-allocated buffer referenced
from mbedtls_ssl_handshake_params::curves. It is used in the following
places:
1) When the server chooses a suitable ciphersuite, it checks that
it has a certificate matching the ciphersuite; in particular, if
the ciphersuite involves ECDHE, the server needs an EC certificate
with a curve suitable for the client.
2) When performing the ECDHE key exchange, the server choose one
curve among those proposed by the client which matches the server's
own supported curve configuration.
This commit removes the hold back the entire client-side curve list
during the handshake, by performing (1) and (2) on during ClientHello
parsing, and in case of (2) only remembering the curve chosen for ECDHE
within mbedtls_ssl_handshake_params.
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 74c9f1a..e9f3409 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -383,7 +383,7 @@
#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
#if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
- const mbedtls_ecp_curve_info **curves; /*!< Supported elliptic curves */
+ mbedtls_ecp_curve_info const *curve_info; /*!< Info for EC for ECDHE. */
#endif
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
unsigned char *psk; /*!< PSK from the callback */