Hi, On 16-03-2021 13:44, Arne Schwabe wrote: > 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 <a...@rfc2549.org> > > Patch V2: Replace magic constant with proper define. Highlight more this > avoding generating unessary debug output than crash workaround. > --- > src/openvpn/options.c | 6 ++++++ > src/openvpn/ssl_common.h | 1 + > src/openvpn/ssl_mbedtls.c | 13 ++++++++++++- > 3 files changed, 19 insertions(+), 1 deletion(-) > > diff --git a/src/openvpn/options.c b/src/openvpn/options.c > index 0eb049d8..c4646d48 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 >= (D_TLS_DEBUG_MED & M_DEBUG_LEVEL)) > + { > + /* We pass this flag to the SSL library to avoid a > + * mbed TLS always generating debug level logging */
Typo: "a mbed TLS" -> "mbed TLS". > + 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 b493cbb7..2e3c98db 100644 > --- a/src/openvpn/ssl_common.h > +++ b/src/openvpn/ssl_common.h > @@ -352,6 +352,7 @@ 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..4626e983 100644 > --- a/src/openvpn/ssl_mbedtls.c > +++ b/src/openvpn/ssl_mbedtls.c > @@ -1058,7 +1058,18 @@ 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, > Otherwise, this now looks good me. Acked-by: Steffan Karger <stef...@karger.me> Thanks, -Steffan _______________________________________________ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
