Decide whether to use SSL flags based on runtime OpenSSL version. (1744e447) · Commits · David Goulet / Tor

ChangeLog

+6 −0

Original line number	Diff line number	Diff line
		@@ -8,6 +8,12 @@ Changes in version 0.2.1.23 - 2010-0?-??
		automatically discard guards picked using the old algorithm. Fixes
		bug 1217; bugfix on 0.2.1.3-alpha. Found by Mike Perry.

		o Minor bugfixes:
		- When deciding whether to use strange flags to turn TLS renegotiation
		on, detect the OpenSSL version at run-time, not compile time. We
		need to do this because Apple doesn't update its dev-tools headers
		when it updates its libraries in a security patch.

		o Minor features:
		- Avoid a mad rush at the beginning of each month when each client
		rotates half of its guards. Instead we spread the rotation out

src/common/tortls.c

+46 −15

Original line number	Diff line number	Diff line
		@@ -53,6 +53,24 @@

		#define ADDR(tls) (((tls) && (tls)->address) ? tls->address : "peer")

		/* 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.)
		*/
		#ifndef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
		#define SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION 0x00040000L
		#endif
		#ifndef SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
		#define SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION 0x0010
		#endif

		/** Does the run-time openssl version look like we need
		* SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION? */
		static int use_unsafe_renegotiation_op = 0;
		/** Does the run-time openssl version look like we need
		* SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION? */
		static int use_unsafe_renegotiation_flag = 0;

		/** Structure holding the TLS state for a single connection. */
		typedef struct tor_tls_context_t {
		int refcnt;
		@@ -309,9 +327,29 @@ static void
		tor_tls_init(void)
		{
		if (!tls_library_is_initialized) {
		long version;
		SSL_library_init();
		SSL_load_error_strings();
		crypto_global_init(-1);

		version = SSLeay();
		if (version >= 0x009070c0L && version < 0x00908000L) {
		log_notice(LD_GENERAL, "OpenSSL %s looks like version 0.9.7l or later; "
		"I will try SSL3_FLAGS and SSL3_OP to enable renegotation",
		SSLeay_version(SSLEAY_VERSION));
		use_unsafe_renegotiation_flag = 1;
		use_unsafe_renegotiation_op = 1;
		} else if (version >= 0x009080c0L) {
		log_notice(LD_GENERAL, "OpenSSL %s looks like version 0.9.8l or later; "
		"I will try SSL3_FLAGS and SSL_OP to enable renegotiation",
		SSLeay_version(SSLEAY_VERSION));
		use_unsafe_renegotiation_flag = 1;
		use_unsafe_renegotiation_op = 1;
		} else {
		log_info(LD_GENERAL, "OpenSSL %s has version %lx",
		SSLeay_version(SSLEAY_VERSION), version);
		}

		tls_library_is_initialized = 1;
		}
		}
		@@ -568,7 +606,6 @@ tor_tls_context_new(crypto_pk_env_t *identity, unsigned int key_lifetime)
		SSL_CTX_set_options(result->ctx,
		SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION);
		#endif
		#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
		/* Yes, we know what we are doing here. No, we do not treat a renegotiation
		* as authenticating any earlier-received data.
		*
		@@ -577,9 +614,10 @@ tor_tls_context_new(crypto_pk_env_t *identity, unsigned int key_lifetime)
		* seems) broke anything that used SSL3_FLAGS_* for the purpose. So we need
		* to do both.)
		*/
		if (use_unsafe_renegotiation_op) {
		SSL_CTX_set_options(result->ctx,
		SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION);
		#endif
		}
		/* Don't actually allow compression; it uses ram and time, but the data
		* we transmit is all encrypted anyway. */
		if (result->ctx->comp_methods)
		@@ -920,19 +958,16 @@ tor_tls_set_renegotiate_callback(tor_tls_t *tls,
		}

		/** If this version of openssl requires it, turn on renegotiation on
		* <b>tls</b>. (Our protocol never requires this for security, but it's nice
		* to use belt-and-suspenders here.)
		* <b>tls</b>.
		*/
		static void
		tor_tls_unblock_renegotiation(tor_tls_t *tls)
		{
		#ifdef SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
		/* Yes, we know what we are doing here. No, we do not treat a renegotiation
		* as authenticating any earlier-received data. */
		if (use_unsafe_renegotiation_flag) {
		tls->ssl->s3->flags \|= SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION;
		#else
		(void)tls;
		#endif
		}
		}

		/** If this version of openssl supports it, turn off renegotiation on
		@@ -942,11 +977,7 @@ tor_tls_unblock_renegotiation(tor_tls_t *tls)
		void
		tor_tls_block_renegotiation(tor_tls_t *tls)
		{
		#ifdef SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
		tls->ssl->s3->flags &= ~SSL3_FLAGS_ALLOW_UNSAFE_LEGACY_RENEGOTIATION;
		#else
		(void)tls;
		#endif
		}

		/** Return whether this tls initiated the connect (client) or