commit db78fe45898a6d03727f8db68642bfebdfc10bf8 Author: Nick Mathewson <nickm@torproject.org> Date: Wed Jan 4 17:15:50 2012 -0500 Disable SSLv3 when using a not-up-to-date openssl This is to address bug 4822, and CVE-2011-4576. --- src/common/tortls.c | 31 ++++++++++++++++++++++++++++--- 1 files changed, 28 insertions(+), 3 deletions(-) diff --git a/src/common/tortls.c b/src/common/tortls.c index cc805f8..22b0e31 100644 --- a/src/common/tortls.c +++ b/src/common/tortls.c @@ -64,6 +64,16 @@ #define ADDR(tls) (((tls) && (tls)->address) ? tls->address : "peer") +#if (OPENSSL_VERSION_NUMBER < 0x0090813fL || \ + (OPENSSL_VERSION_NUMBER >= 0x00909000L && \ + OPENSSL_VERSION_NUMBER < 0x1000006fL)) +/* This is a version of OpenSSL before 0.9.8s/1.0.0f. It does not have + * the CVE-2011-4657 fix, and as such it can't use RELEASE_BUFFERS and + * SSL3 safely at the same time. + */ +#define DISABLE_SSL3_HANDSHAKE +#endif + /* We redefine these so that we can run correctly even if the vendor gives us * a version of OpenSSL that does not match its header files. (Apple: I am * looking at you.) @@ -739,16 +749,31 @@ tor_tls_context_new(crypto_pk_env_t *identity, unsigned int key_lifetime, result->key = crypto_pk_dup_key(rsa); } -#ifdef EVERYONE_HAS_AES - /* Tell OpenSSL to only use TLS1 */ +#if 0 + /* Tell OpenSSL to only use TLS1. This would actually break compatibility + * with clients that are configured to use SSLv23_method(), so we should + * probably never use it. + */ if (!(result->ctx = SSL_CTX_new(TLSv1_method()))) goto error; -#else +#endif + /* Tell OpenSSL to use SSL3 or TLS1 but not SSL2. */ if (!(result->ctx = SSL_CTX_new(SSLv23_method()))) goto error; SSL_CTX_set_options(result->ctx, SSL_OP_NO_SSLv2); + + if ( +#ifdef DISABLE_SSL3_HANDSHAKE + 1 || #endif + SSLeay() < 0x0090813fL || + (SSLeay() >= 0x00909000L && + SSLeay() < 0x1000006fL)) { + /* And not SSL3 if it's subject to CVE-2011-4657. */ + SSL_CTX_set_options(result->ctx, SSL_OP_NO_SSLv3); + } + SSL_CTX_set_options(result->ctx, SSL_OP_SINGLE_DH_USE); #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION