Merge pull request libgit2#6966 from libgit2/ethomson/tls

ssl: enforce TLS v1.2 (or better)

Author: ethomson

src/libgit2/streams/mbedtls.c

@@ -39,8 +39,8 @@
 
 #undef inline
 
-#define GIT_SSL_DEFAULT_CIPHERS "TLS1-3-AES-128-GCM-SHA256:TLS1-3-AES-256-GCM-SHA384:TLS1-3-CHACHA20-POLY1305-SHA256:TLS-ECDHE-ECDSA-WITH-AES-128-GCM-SHA256:TLS-ECDHE-RSA-WITH-AES-128-GCM-SHA256:TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384:TLS-ECDHE-RSA-WITH-AES-256-GCM-SHA384:TLS-ECDHE-ECDSA-WITH-CHACHA20-POLY1305-SHA256:TLS-ECDHE-RSA-WITH-CHACHA20-POLY1305-SHA256:TLS-DHE-RSA-WITH-AES-128-GCM-SHA256:TLS-DHE-RSA-WITH-AES-256-GCM-SHA384:TLS-DHE-RSA-WITH-CHACHA20-POLY1305-SHA256:TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA256:TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA256:TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA:TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA:TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA384:TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA384:TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA:TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA:TLS-DHE-RSA-WITH-AES-128-CBC-SHA256:TLS-DHE-RSA-WITH-AES-256-CBC-SHA256:TLS-RSA-WITH-AES-128-GCM-SHA256:TLS-RSA-WITH-AES-256-GCM-SHA384:TLS-RSA-WITH-AES-128-CBC-SHA256:TLS-RSA-WITH-AES-256-CBC-SHA256:TLS-RSA-WITH-AES-128-CBC-SHA:TLS-RSA-WITH-AES-256-CBC-SHA"
-#define GIT_SSL_DEFAULT_CIPHERS_COUNT 28
+#define GIT_SSL_DEFAULT_CIPHERS "TLS1-3-AES-128-GCM-SHA256:TLS1-3-AES-256-GCM-SHA384:TLS1-3-CHACHA20-POLY1305-SHA256:TLS-ECDHE-ECDSA-WITH-AES-128-GCM-SHA256:TLS-ECDHE-RSA-WITH-AES-128-GCM-SHA256:TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384:TLS-ECDHE-RSA-WITH-AES-256-GCM-SHA384:TLS-ECDHE-ECDSA-WITH-CHACHA20-POLY1305-SHA256:TLS-ECDHE-RSA-WITH-CHACHA20-POLY1305-SHA256:TLS-DHE-RSA-WITH-AES-128-GCM-SHA256:TLS-DHE-RSA-WITH-AES-256-GCM-SHA384:TLS-DHE-RSA-WITH-CHACHA20-POLY1305-SHA256"
+#define GIT_SSL_DEFAULT_CIPHERS_COUNT 12
 
 static int ciphers_list[GIT_SSL_DEFAULT_CIPHERS_COUNT];
 
@@ -94,9 +94,13 @@ int git_mbedtls_stream_global_init(void)
 		goto cleanup;
 	}
 
-	/* configure TLSv1.1 or better */
-#ifdef MBEDTLS_SSL_MINOR_VERSION_2
-	mbedtls_ssl_conf_min_version(&mbedtls_config, MBEDTLS_SSL_MAJOR_VERSION_3, MBEDTLS_SSL_MINOR_VERSION_2);
+	/*
+	 * Configure TLSv1.2 or better; if the minor version constant isn't
+	 * defined then this version of mbedTLS doesn't support such an old
+	 * version, so we need not do anything.
+	 */
+#ifdef MBEDTLS_SSL_MINOR_VERSION_3
+	mbedtls_ssl_conf_min_version(&mbedtls_config, MBEDTLS_SSL_MAJOR_VERSION_3, MBEDTLS_SSL_MINOR_VERSION_3);
 #endif
 
 	/* verify_server_cert is responsible for making the check.

src/libgit2/streams/openssl.c

@@ -40,7 +40,8 @@ extern char *git__ssl_ciphers;
 
 SSL_CTX *git__ssl_ctx;
 
-#define GIT_SSL_DEFAULT_CIPHERS "TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA256:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA"
+#define GIT_SSL_DEFAULT_CIPHERS "TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305"
+
 
 static BIO_METHOD *git_stream_bio_method;
 static int init_bio_method(void);
@@ -105,7 +106,10 @@ static void git_openssl_free(void *mem)
 
 static int openssl_init(void)
 {
-	long ssl_opts = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;
+	long ssl_opts = SSL_OP_NO_SSLv2 |
+	                SSL_OP_NO_SSLv3 |
+	                SSL_OP_NO_TLSv1 |
+	                SSL_OP_NO_TLSv1_1;
 	const char *ciphers = git__ssl_ciphers;
 #ifdef VALGRIND
 	static bool allocators_initialized = false;
@@ -136,7 +140,7 @@ static int openssl_init(void)
 	/*
 	 * Despite the name SSLv23_method, this is actually a version-
 	 * flexible context, which honors the protocol versions
-	 * specified in `ssl_opts`. So we only support TLSv1.0 and
+	 * specified in `ssl_opts`. So we only support TLSv1.2 and
 	 * higher.
 	 */
 	if (!(git__ssl_ctx = SSL_CTX_new(SSLv23_method())))

src/libgit2/streams/openssl_dynamic.h

@@ -182,6 +182,8 @@
 # define SSL_OP_NO_COMPRESSION        0x00020000L
 # define SSL_OP_NO_SSLv2              0x01000000L
 # define SSL_OP_NO_SSLv3              0x02000000L
+# define SSL_OP_NO_TLSv1              0x04000000L
+# define SSL_OP_NO_TLSv1_1            0x10000000L
 
 # define SSL_MODE_AUTO_RETRY          0x00000004L
 

src/libgit2/streams/stransport.c

@@ -331,8 +331,7 @@ static int stransport_wrap(
 	if ((ret = SSLSetIOFuncs(st->ctx, read_cb, write_cb)) != noErr ||
 	    (ret = SSLSetConnection(st->ctx, st)) != noErr ||
 	    (ret = SSLSetSessionOption(st->ctx, kSSLSessionOptionBreakOnServerAuth, true)) != noErr ||
-	    (ret = SSLSetProtocolVersionMin(st->ctx, kTLSProtocol1)) != noErr ||
-	    (ret = SSLSetProtocolVersionMax(st->ctx, kTLSProtocol12)) != noErr ||
+	    (ret = SSLSetProtocolVersionMin(st->ctx, kTLSProtocol12)) != noErr ||
 	    (ret = SSLSetPeerDomainName(st->ctx, host, strlen(host))) != noErr) {
 		CFRelease(st->ctx);
 		git__free(st);