Hi,
On 08/03/2021 15:21, Arne Schwabe wrote:
[cut]
> diff --git a/src/openvpn/options.c b/src/openvpn/options.c
> index 0eb049d8..6d908e15 100644
> --- a/src/openvpn/options.c
> +++ b/src/openvpn/options.c
> @@ -5883,6 +5883,12 @@ add_option(struct options *options,
> {
> VERIFY_PERMISSION(OPT_P_MESSAGES);
> options->verbosity = positive_atoi(p[1]);
> + if (options->verbosity > 7)
> + {
> + /* We pass this flag to the SSL library to avoid a bug
> + * in mbed TLS 2.5.0 with high log level */
> + options->ssl_flags |= SSLF_TLS_DEBUG_ENABLED;
> + }
(2.5.0 is probably a typ0?)
If we know that a certain combination of options + the right mbedTLS
version will lead to a crash, shouldn't we catch it here (or somewhere
else) and error out right away?
> #if !defined(ENABLE_DEBUG) && !defined(ENABLE_SMALL)
> /* Warn when a debug verbosity is supplied when built without debug
> support */
> if (options->verbosity >= 7)
> diff --git a/src/openvpn/ssl_common.h b/src/openvpn/ssl_common.h
> index bbb8135d..f821c654 100644
> --- a/src/openvpn/ssl_common.h
> +++ b/src/openvpn/ssl_common.h
> @@ -350,6 +350,7 @@ struct tls_options
> #define SSLF_TLS_VERSION_MIN_MASK 0xF /* (uses bit positions 6 to 9) */
> #define SSLF_TLS_VERSION_MAX_SHIFT 10
> #define SSLF_TLS_VERSION_MAX_MASK 0xF /* (uses bit positions 10 to 13)
> */
> +#define SSLF_TLS_DEBUG_ENABLED (1<<14)
> unsigned int ssl_flags;
>
> #ifdef ENABLE_MANAGEMENT
> diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
> index b30b6b9d..a7b6c2c6 100644
> --- a/src/openvpn/ssl_mbedtls.c
> +++ b/src/openvpn/ssl_mbedtls.c
> @@ -1058,7 +1058,16 @@ key_state_ssl_init(struct key_state_ssl *ks_ssl,
> mbedtls_ssl_config_defaults(ks_ssl->ssl_config, ssl_ctx->endpoint,
> MBEDTLS_SSL_TRANSPORT_STREAM,
> MBEDTLS_SSL_PRESET_DEFAULT);
> #ifdef MBEDTLS_DEBUG_C
> - mbedtls_debug_set_threshold(3);
> + /* This works around a crash in mbed TLS 2.25 if Curve25591 is selected
> + * for DH (https://github.com/ARMmbed/mbedtls/issues/4208)*/
> + if (session->opt->ssl_flags & SSLF_TLS_DEBUG_ENABLED)
> + {
> + mbedtls_debug_set_threshold(3);
If a user is on mbedTLS 2.25 and specifies verb = 8 we will then crash
(assuming the right combination of options was chosen).
Isn't it better to just always use 2 as threshold when the mbedTLS
version is known to be buggy (regardless of verb)?
An ifdef around this invocation would do it, without the need of
introducing another SSL flag.
> + }
> + else
> + {
> + mbedtls_debug_set_threshold(2);
> + }> #endif
> mbedtls_ssl_conf_dbg(ks_ssl->ssl_config, my_debug, NULL);
> mbedtls_ssl_conf_rng(ks_ssl->ssl_config, mbedtls_ctr_drbg_random,
>
my 2 cents
Cheers,
--
Antonio Quartulli
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