OpenSSL: Require TLS ≥ 1.2

TLS 1.2 was added in OpenSSL version 1.0.1,
which was our minimal supported openssl version for a long time:
so we can be sure that all clients and relays have it.

(I'd like to require TLS 1.3, but that would break everybody
who built with 1.0.1.)

Part of #41067.

diff --git a/changes/ticket41067 b/changes/ticket41067
new file mode 100644 (file)
index 0000000..0baa74b
--- /dev/null
+++ b/changes/ticket41067
@@ -0,0 +1,3 @@
+  o Minor features (security):
+    - Require TLS version 1.2 or later.  (Version 1.3 support will
+      be required in the near future.)  Part of ticket 41067.

diff --git a/src/lib/tls/tortls_openssl.c b/src/lib/tls/tortls_openssl.c
index 4c74085d64b87412e9036a3f9211bf3bbbdb851b..3e6948f9924263c24c3a8943d79477a90f8970c3 100644 (file)
--- a/src/lib/tls/tortls_openssl.c
+++ b/src/lib/tls/tortls_openssl.c
@@ -497,27 +497,17 @@ tor_tls_context_new(crypto_pk_t *identity, unsigned int key_lifetime,
     }
   }
 
-#if 0
-  /* Tell OpenSSL to only use TLS1.  This may have subtly different results
-   * from SSLv23_method() with SSLv2 and SSLv3 disabled, so we need to do some
-   * investigation before we consider adjusting it. It should be compatible
-   * with existing Tors. */
-  if (!(result->ctx = SSL_CTX_new(TLSv1_method())))
-    goto error;
-#endif /* 0 */
-
-  /* Tell OpenSSL to use TLS 1.0 or later but not SSL2 or SSL3. */
+  /* Tell OpenSSL to use TLS 1.2 or later. */
   if (!(result->ctx = SSL_CTX_new(TLS_method())))
     goto error;
+  if (!SSL_CTX_set_min_proto_version(result->ctx, TLS1_2_VERSION))
+    goto error;
 
 #ifdef HAVE_SSL_CTX_SET_SECURITY_LEVEL
   /* Level 1 re-enables RSA1024 and DH1024 for compatibility with old tors */
   SSL_CTX_set_security_level(result->ctx, 1);
 #endif
 
-  SSL_CTX_set_options(result->ctx, SSL_OP_NO_SSLv2);
-  SSL_CTX_set_options(result->ctx, SSL_OP_NO_SSLv3);
-
   /* Prefer the server's ordering of ciphers: the client's ordering has
   * historically been chosen for fingerprinting resistance. */
   SSL_CTX_set_options(result->ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);