Add better support for showing TLS 1.3 ciphersuites in --show-tls

--show-tls shows mixed TLS 1.3 and TLS 1.2 ciphers.  The listed ciphers
are only valid in either --tls-cipher or --tls-ciphersuites, but it's
not clear which is which. This is confusing and not really helpful.

This patch modifies show-tls to show separate lists for TLS 1.2 and
TLS 1.3.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <20181010153624.27957-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg17723.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/init.c b/src/openvpn/init.c
index 1b9f19d09cd7f56abdb32ac42966035cfe2fd877..e5e6e85f26820b3c99410f57b524e3f5c8c33012 100644 (file)
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -1034,6 +1034,7 @@ print_openssl_info(const struct options *options)
         if (options->show_tls_ciphers)
         {
             show_available_tls_ciphers(options->cipher_list,
+                                       options->cipher_list_tls13,
                                        options->tls_cert_profile);
         }
         if (options->show_curves)

diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index 4ec85f501748e95e2e3feec45dbe358aca106a66..52ed2ad5ba5da5faf58e21bfb79bf662d62f4e20 100644 (file)
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -4116,6 +4116,30 @@ tls_check_ncp_cipher_list(const char *list)
     return 0 < strlen(list) && !unsupported_cipher_found;
 }
 
+void
+show_available_tls_ciphers(const char *cipher_list,
+                           const char *cipher_list_tls13,
+                           const char *tls_cert_profile)
+{
+    printf("Available TLS Ciphers, listed in order of preference:\n");
+
+#if (ENABLE_CRYPTO_OPENSSL && OPENSSL_VERSION_NUMBER >= 0x1010100fL)
+    printf("\nFor TLS 1.3 and newer (--tls-ciphersuites):\n\n");
+    show_available_tls_ciphers_list(cipher_list_tls13, tls_cert_profile, true);
+#else
+    (void) cipher_list_tls13;  /* Avoid unused warning */
+#endif
+
+    printf("\nFor TLS 1.2 and older (--tls-cipher):\n\n");
+    show_available_tls_ciphers_list(cipher_list, tls_cert_profile, false);
+
+    printf("\n"
+    "Be aware that that whether a cipher suite in this list can actually work\n"
+    "depends on the specific setup of both peers. See the man page entries of\n"
+    "--tls-cipher and --show-tls for more details.\n\n"
+    );
+}
+
 /*
  * Dump a human-readable rendition of an openvpn packet
  * into a garbage collectable string which is returned.

diff --git a/src/openvpn/ssl.h b/src/openvpn/ssl.h
index e874519731d542f538a5489d3dbbf1fd57d816eb..d412dc0793fbc62f8f8b697b643261b45027c295 100644 (file)
--- a/src/openvpn/ssl.h
+++ b/src/openvpn/ssl.h
@@ -598,4 +598,18 @@ bool is_hard_reset(int op, int key_method);
 
 void delayed_auth_pass_purge(void);
 
+
+/*
+ * Show the TLS ciphers that are available for us to use in the SSL
+ * library with headers hinting their usage and warnings about usage.
+ *
+ * @param cipher_list       list of allowed TLS cipher, or NULL.
+ * @param cipher_list_tls13 list of allowed TLS 1.3+ cipher, or NULL
+ * @param tls_cert_profile  TLS certificate crypto profile name.
+ */
+void
+show_available_tls_ciphers(const char *cipher_list,
+                           const char *cipher_list_tls13,
+                           const char *tls_cert_profile);
+
 #endif /* ifndef OPENVPN_SSL_H */

diff --git a/src/openvpn/ssl_backend.h b/src/openvpn/ssl_backend.h
index 2ae3bcd7e50de135a9611a178d3c65f4f452edd0..1c244ece36a80abf288a7fa0ed0edce49ed4aa82 100644 (file)
--- a/src/openvpn/ssl_backend.h
+++ b/src/openvpn/ssl_backend.h
@@ -517,15 +517,19 @@ int key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf,
 void print_details(struct key_state_ssl *ks_ssl, const char *prefix);
 
 /*
- * Show the TLS ciphers that are available for us to use in the OpenSSL
- * library.
+ * Show the TLS ciphers that are available for us to use in the
+ * library depending on the TLS version. This function prints
+ * a list of ciphers without headers/footers.
  *
  * @param cipher_list       list of allowed TLS cipher, or NULL.
  * @param tls_cert_profile  TLS certificate crypto profile name.
+ * @param tls13             Select if <=TLS1.2 or TLS1.3+ ciphers
+ *                          should be shown
  */
 void
-show_available_tls_ciphers(const char *cipher_list,
-                           const char *tls_cert_profile);
+show_available_tls_ciphers_list(const char *cipher_list,
+                                const char *tls_cert_profile,
+                                bool tls13);
 
 /*
  * Show the available elliptic curves in the crypto library

diff --git a/src/openvpn/ssl_common.h b/src/openvpn/ssl_common.h
index 919ec57c06424c39c8e5bb6b8e615f665f577a32..e5c28508d9aa79474da96aba4e3390b52908a80a 100644 (file)
--- a/src/openvpn/ssl_common.h
+++ b/src/openvpn/ssl_common.h
@@ -554,10 +554,4 @@ struct tls_multi
      *   sessions with the remote peer. */
 };
 
-
-#define SHOW_TLS_CIPHER_LIST_WARNING \
-    "Be aware that that whether a cipher suite in this list can actually work\n" \
-    "depends on the specific setup of both peers. See the man page entries of\n" \
-    "--tls-cipher and --show-tls for more details.\n\n"
-
 #endif /* SSL_COMMON_H_ */

diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
index cb71d55a3233ac0a11ae9d1d30e0908f8c2319c5..3a0b5641cfe1ef3e3dfb786592fc25168c2a7cb6 100644 (file)
--- a/src/openvpn/ssl_mbedtls.c
+++ b/src/openvpn/ssl_mbedtls.c
@@ -1340,9 +1340,15 @@ print_details(struct key_state_ssl *ks_ssl, const char *prefix)
 }
 
 void
-show_available_tls_ciphers(const char *cipher_list,
-                           const char *tls_cert_profile)
+show_available_tls_ciphers_list(const char *cipher_list,
+                                const char *tls_cert_profile,
+                                bool tls13)
 {
+    if (tls13)
+    {
+        /* mbed TLS has no TLS 1.3 support currently */
+        return;
+    }
     struct tls_root_ctx tls_ctx;
     const int *ciphers = mbedtls_ssl_list_ciphersuites();
 
@@ -1355,18 +1361,11 @@ show_available_tls_ciphers(const char *cipher_list,
         ciphers = tls_ctx.allowed_ciphers;
     }
 
-#ifndef ENABLE_SMALL
-    printf("Available TLS Ciphers,\n");
-    printf("listed in order of preference:\n\n");
-#endif
-
     while (*ciphers != 0)
     {
         printf("%s\n", mbedtls_ssl_get_ciphersuite_name(*ciphers));
         ciphers++;
     }
-    printf("\n" SHOW_TLS_CIPHER_LIST_WARNING);
-
     tls_ctx_free(&tls_ctx);
 }
 

diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
index ba0d13287e8aadc98edc12a765c8e40905b7e0d7..6717ded061bced774598bc4ddab374726dc87525 100644 (file)
--- a/src/openvpn/ssl_openssl.c
+++ b/src/openvpn/ssl_openssl.c
@@ -60,6 +60,7 @@
 #include <openssl/pkcs12.h>
 #include <openssl/rsa.h>
 #include <openssl/x509.h>
+#include <openssl/ssl.h>
 #ifndef OPENSSL_NO_EC
 #include <openssl/ec.h>
 #endif
@@ -428,7 +429,8 @@ tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers)
 }
 
 void
-convert_tls13_list_to_openssl(char* openssl_ciphers, size_t len, const char *ciphers)
+convert_tls13_list_to_openssl(char *openssl_ciphers, size_t len,
+                              const char *ciphers)
 {
     /*
      * OpenSSL (and official IANA) cipher names have _ in them. We
@@ -1984,14 +1986,11 @@ print_details(struct key_state_ssl *ks_ssl, const char *prefix)
 }
 
 void
-show_available_tls_ciphers(const char *cipher_list,
-                           const char *tls_cert_profile)
+show_available_tls_ciphers_list(const char *cipher_list,
+                                const char *tls_cert_profile,
+                                const bool tls13)
 {
     struct tls_root_ctx tls_ctx;
-    SSL *ssl;
-    const char *cipher_name;
-    const tls_cipher_name_pair *pair;
-    int priority = 0;
 
     tls_ctx.ctx = SSL_CTX_new(SSLv23_method());
     if (!tls_ctx.ctx)
@@ -1999,22 +1998,45 @@ show_available_tls_ciphers(const char *cipher_list,
         crypto_msg(M_FATAL, "Cannot create SSL_CTX object");
     }
 
-    ssl = SSL_new(tls_ctx.ctx);
-    if (!ssl)
+#if (OPENSSL_VERSION_NUMBER >= 0x1010100fL)
+    if (tls13)
     {
-        crypto_msg(M_FATAL, "Cannot create SSL object");
+        SSL_CTX_set_min_proto_version(tls_ctx.ctx, TLS1_3_VERSION);
+    }
+    else
+#endif
+    {
+        SSL_CTX_set_max_proto_version(tls_ctx.ctx, TLS1_2_VERSION);
     }
 
     tls_ctx_set_cert_profile(&tls_ctx, tls_cert_profile);
     tls_ctx_restrict_ciphers(&tls_ctx, cipher_list);
 
-    printf("Available TLS Ciphers,\n");
-    printf("listed in order of preference:\n\n");
-    while ((cipher_name = SSL_get_cipher_list(ssl, priority++)))
+    SSL *ssl = SSL_new(tls_ctx.ctx);
+    if (!ssl)
+    {
+        crypto_msg(M_FATAL, "Cannot create SSL object");
+    }
+
+#if (OPENSSL_VERSION_NUMBER < 0x1010000fL)
+    STACK_OF(SSL_CIPHER) *sk = SSL_get_ciphers(ssl);
+#else
+    STACK_OF(SSL_CIPHER) *sk = SSL_get1_supported_ciphers(ssl);
+#endif
+    for (int i=0;i < sk_SSL_CIPHER_num(sk);i++)
     {
-        pair = tls_get_cipher_name_pair(cipher_name, strlen(cipher_name));
+        const SSL_CIPHER *c = sk_SSL_CIPHER_value(sk, i);
+
+        const char *cipher_name = SSL_CIPHER_get_name(c);
+
+        const tls_cipher_name_pair *pair =
+            tls_get_cipher_name_pair(cipher_name, strlen(cipher_name));
 
-        if (NULL == pair)
+        if (tls13)
+        {
+              printf("%s\n", cipher_name);
+        }
+        else if (NULL == pair)
         {
             /* No translation found, print warning */
             printf("%s (No IANA name known to OpenVPN, use OpenSSL name.)\n", cipher_name);
@@ -2023,10 +2045,10 @@ show_available_tls_ciphers(const char *cipher_list,
         {
             printf("%s\n", pair->iana_name);
         }
-
     }
-    printf("\n" SHOW_TLS_CIPHER_LIST_WARNING);
-
+#if (OPENSSL_VERSION_NUMBER >= 0x1010000fL)
+    sk_SSL_CIPHER_free(sk);
+#endif
     SSL_free(ssl);
     SSL_CTX_free(tls_ctx.ctx);
 }