Remove reuse of key_type during init of data channel auth and tls-auth

Prepare for using AEAD cipher modes + tls-auth, as tls-auth might want to
use an HMAC, while the data channel uses e.g. GCM tags.  This separates
the two initialisations.  Also, error out (and give a clear error message)
if a user specifies tls-auth but no valid auth algorithm, which makes no
sense at all.

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <1454874438-5081-3-git-send-email-steffan@karger.me>
URL: http://article.gmane.org/gmane.network.openvpn.devel/11073
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c
index c18d88bb22b329d5f5f8b89312358c5dc7a5bbb3..806a9950b71128462b4a98c6f336015316e2cd6d 100644 (file)
--- a/src/openvpn/crypto.c
+++ b/src/openvpn/crypto.c
@@ -751,13 +751,8 @@ get_tls_handshake_key (const struct key_type *key_type,
   if (passphrase_file && key_type->hmac_length)
     {
       struct key2 key2;
-      struct key_type kt = *key_type;
       struct key_direction_state kds;
 
-      /* for control channel we are only authenticating, not encrypting */
-      kt.cipher_length = 0;
-      kt.cipher = NULL;
-
       if (flags & GHK_INLINE)
        {
          /* key was specified inline, key text is in passphrase_file */
@@ -800,9 +795,9 @@ get_tls_handshake_key (const struct key_type *key_type,
 
       /* initialize hmac key in both directions */
 
-      init_key_ctx (&ctx->encrypt, &key2.keys[kds.out_key], &kt, OPENVPN_OP_ENCRYPT,
+      init_key_ctx (&ctx->encrypt, &key2.keys[kds.out_key], key_type, OPENVPN_OP_ENCRYPT,
                    "Outgoing Control Channel Authentication");
-      init_key_ctx (&ctx->decrypt, &key2.keys[kds.in_key], &kt, OPENVPN_OP_DECRYPT,
+      init_key_ctx (&ctx->decrypt, &key2.keys[kds.in_key], key_type, OPENVPN_OP_DECRYPT,
                    "Incoming Control Channel Authentication");
 
       CLEAR (key2);

diff --git a/src/openvpn/init.c b/src/openvpn/init.c
index d0020b76bb7970db32a6daa14b9b296cf71290f8..7e6e448101c6b1f7596653a80e74601113a53ce3 100644 (file)
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -2206,11 +2206,23 @@ do_init_crypto_tls_c1 (struct context *c)
              flags |= GHK_INLINE;
              file = options->tls_auth_file_inline;
            }
-         get_tls_handshake_key (&c->c1.ks.key_type,
-                                &c->c1.ks.tls_auth_key,
-                                file,
-                                options->key_direction,
-                                flags);
+
+         /* Initialize key_type for tls-auth with auth only */
+         CLEAR (c->c1.ks.tls_auth_key_type);
+         if (options->authname && options->authname_defined)
+           {
+             c->c1.ks.tls_auth_key_type.digest = md_kt_get (options->authname);
+             c->c1.ks.tls_auth_key_type.hmac_length =
+                 md_kt_size (c->c1.ks.tls_auth_key_type.digest);
+           }
+         else
+           {
+             msg (M_FATAL, "ERROR: tls-auth enabled, but no valid --auth "
+                 "algorithm specified ('%s')", options->authname);
+           }
+
+         get_tls_handshake_key (&c->c1.ks.tls_auth_key_type,
+             &c->c1.ks.tls_auth_key, file, options->key_direction, flags);
        }
 
 #if 0 /* was: #if ENABLE_INLINE_FILES --  Note that enabling this code will break restarts */
@@ -2375,7 +2387,7 @@ do_init_crypto_tls (struct context *c, const unsigned int flags)
       to.tls_auth.pid_persist = &c->c1.pid_persist;
       to.tls_auth.flags |= CO_PACKET_ID_LONG_FORM;
       crypto_adjust_frame_parameters (&to.frame,
-                                     &c->c1.ks.key_type,
+                                     &c->c1.ks.tls_auth_key_type,
                                      false, false, true, true);
     }
 
@@ -3758,6 +3770,7 @@ inherit_context_child (struct context *dest,
   /* inherit SSL context */
   dest->c1.ks.ssl_ctx = src->c1.ks.ssl_ctx;
   dest->c1.ks.tls_auth_key = src->c1.ks.tls_auth_key;
+  dest->c1.ks.tls_auth_key_type = src->c1.ks.tls_auth_key_type;
 #endif
 
   /* options */

diff --git a/src/openvpn/openvpn.h b/src/openvpn/openvpn.h
index 3f1df6ec44f7a0f221dd723ba7b66a3d910264ff..71adf4814e49571fe34aba18806bc3860f8b530c 100644 (file)
--- a/src/openvpn/openvpn.h
+++ b/src/openvpn/openvpn.h
@@ -66,6 +66,7 @@ struct key_schedule
   struct tls_root_ctx ssl_ctx;
 
   /* optional authentication HMAC key for TLS control channel */
+  struct key_type tls_auth_key_type;
   struct key_ctx_bi tls_auth_key;
 #else                          /* ENABLE_CRYPTO */
   int dummy;