From: Arne Schwabe Date: Tue, 16 Mar 2021 12:44:21 +0000 (+0100) Subject: Avoid generating unecessary mbed debug messages X-Git-Tag: v2.5.2~15 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=475d17a53eba85591f270008f8b583383a5b9afa;p=thirdparty%2Fopenvpn.git Avoid generating unecessary mbed debug messages The main motivation to make this change is to avoid a crash in mbed TLS 2.25 with --verb < 8. mbed TLS 2.25 has a nasty bug that the print function for Montgomery style EC curves (Curve25519 and Curve448) does segfault. See also the issue reported here: https://github.com/ARMmbed/mbedtls/issues/4208 We request always debug level 3 from mbed TLS but filter out any debug output of level 3 unless verb 8 or higher is set. This commeit sets the debug level to 2 to avoid this problem by makeing mbed TLS not generatin the problematic debug output. For the affected version to still use --verb 8 with mbed TLS 2.25 is to restrict the EC groups to ones that do not crash the print function like with '--tls-groups secp521r1:secp384r1:secp256r1'. This patch has no patch on user-visible behaviour on unaffected mbed TLS versions. Signed-off-by: Arne Schwabe Patch V2: Replace magic constant with proper define. Highlight more this avoding generating unessary debug output than crash workaround. Acked-by: Gert Doering Acked-by: Steffan Karger Message-Id: <20210316124421.1635-1-arne@rfc2549.org> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg21667.html Signed-off-by: Gert Doering (cherry picked from commit 4524feb2bbbb6d1bd463a0c5c2d53aae5bdf360a) --- diff --git a/src/openvpn/options.c b/src/openvpn/options.c index 23f7b3d76..620785bef 100644 --- a/src/openvpn/options.c +++ b/src/openvpn/options.c @@ -6008,6 +6008,12 @@ add_option(struct options *options, { VERIFY_PERMISSION(OPT_P_MESSAGES); options->verbosity = positive_atoi(p[1]); + if (options->verbosity >= (D_TLS_DEBUG_MED & M_DEBUG_LEVEL)) + { + /* We pass this flag to the SSL library to avoid + * mbed TLS always generating debug level logging */ + options->ssl_flags |= SSLF_TLS_DEBUG_ENABLED; + } #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 96897e48b..a703f97cd 100644 --- a/src/openvpn/ssl_common.h +++ b/src/openvpn/ssl_common.h @@ -347,6 +347,7 @@ 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 MANAGEMENT_DEF_AUTH diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c index 9c8747888..9da063145 100644 --- a/src/openvpn/ssl_mbedtls.c +++ b/src/openvpn/ssl_mbedtls.c @@ -1070,7 +1070,18 @@ 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); + /* We only want to have mbed TLS generate debug level logging when we would + * also display it. + * In fact mbed TLS 2.25.0 crashes generating debug log 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); + } + 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,