- a hack for grahame to run dropbear with "none" cipher.

  DO NOT USE IF YOU DON'T KNOW THE CONSEQUENCES
  Here is your noose. Use it wisely.

4 files changed, 58 insertions, 18 deletions

diff --git a/cli-auth.c b/cli-auth.c
index 6a6d53a..c9aace1 100644
--- a/cli-auth.c
+++ b/cli-auth.c
@@ -251,7 +251,10 @@ void cli_auth_try() {
 #endif
 
 #ifdef ENABLE_CLI_INTERACT_AUTH
-	if (!finished && ses.authstate.authtypes & AUTH_TYPE_INTERACT) {
+	if (ses.keys->trans_algo_crypt->cipherdesc == NULL) {
+		fprintf(stderr, "Sorry, I won't let you use interactive auth unencrypted.\n");
+	}
+	else if (!finished && ses.authstate.authtypes & AUTH_TYPE_INTERACT) {
 		if (cli_ses.auth_interact_failed) {
 			finished = 0;
 		} else {
@@ -263,7 +266,10 @@ void cli_auth_try() {
 #endif
 
 #ifdef ENABLE_CLI_PASSWORD_AUTH
-	if (!finished && ses.authstate.authtypes & AUTH_TYPE_PASSWORD) {
+	if (ses.keys->trans_algo_crypt->cipherdesc == NULL) {
+		fprintf(stderr, "Sorry, I won't let you use password auth unencrypted.\n");
+	}
+	else if (!finished && ses.authstate.authtypes & AUTH_TYPE_PASSWORD) {
 		cli_auth_password();
 		finished = 1;
 		cli_ses.lastauthtype = AUTH_TYPE_PASSWORD;
diff --git a/common-algo.c b/common-algo.c
index 6ce1a37..8282360 100644
--- a/common-algo.c
+++ b/common-algo.c
@@ -103,6 +103,9 @@ algo_type sshciphers[] = {
 #ifdef DROPBEAR_BLOWFISH_CBC
 	{"blowfish-cbc", 0, (void*)&dropbear_blowfish, 1},
 #endif
+#ifdef DROPBEAR_NONE_CIPHER
+	{"none", 0, (void*)&dropbear_nocipher, 1},
+#endif
 	{NULL, 0, NULL, 0}
 };
 
@@ -116,6 +119,9 @@ algo_type sshhashes[] = {
 #ifdef DROPBEAR_MD5_HMAC
 	{"hmac-md5", 0, (void*)&dropbear_md5, 1},
 #endif
+#ifdef DROPBEAR_NONE_INTEGRITY
+	{"none", 0, (void*)&dropbear_nohash, 1},
+#endif
 	{NULL, 0, NULL, 0}
 };
 
diff --git a/common-kex.c b/common-kex.c
index f325329..ac48699 100644
--- a/common-kex.c
+++ b/common-kex.c
@@ -298,27 +298,35 @@ void gen_new_keys() {
 	hashkeys(C2S_key, C2S_keysize, &hs, 'C');
 	hashkeys(S2C_key, S2C_keysize, &hs, 'D');
 
-	if (cbc_start(
-		find_cipher(ses.newkeys->recv_algo_crypt->cipherdesc->name),
-			recv_IV, recv_key, 
-			ses.newkeys->recv_algo_crypt->keysize, 0, 
-			&ses.newkeys->recv_symmetric_struct) != CRYPT_OK) {
-		dropbear_exit("crypto error");
+	if (ses.newkeys->recv_algo_crypt->cipherdesc != NULL) {
+		if (cbc_start(
+			find_cipher(ses.newkeys->recv_algo_crypt->cipherdesc->name),
+				recv_IV, recv_key, 
+				ses.newkeys->recv_algo_crypt->keysize, 0, 
+				&ses.newkeys->recv_symmetric_struct) != CRYPT_OK) {
+			dropbear_exit("crypto error");
+		}
 	}
 
-	if (cbc_start(
-		find_cipher(ses.newkeys->trans_algo_crypt->cipherdesc->name),
-			trans_IV, trans_key, 
-			ses.newkeys->trans_algo_crypt->keysize, 0, 
-			&ses.newkeys->trans_symmetric_struct) != CRYPT_OK) {
-		dropbear_exit("crypto error");
+	if (ses.newkeys->trans_algo_crypt->cipherdesc != NULL) {
+		if (cbc_start(
+			find_cipher(ses.newkeys->trans_algo_crypt->cipherdesc->name),
+				trans_IV, trans_key, 
+				ses.newkeys->trans_algo_crypt->keysize, 0, 
+				&ses.newkeys->trans_symmetric_struct) != CRYPT_OK) {
+			dropbear_exit("crypto error");
+		}
 	}
 	
 	/* MAC keys */
-	hashkeys(ses.newkeys->transmackey, 
-			ses.newkeys->trans_algo_mac->keysize, &hs, mactransletter);
-	hashkeys(ses.newkeys->recvmackey, 
-			ses.newkeys->recv_algo_mac->keysize, &hs, macrecvletter);
+	if (ses.newkeys->trans_algo_mac->hashdesc != NULL) {
+		hashkeys(ses.newkeys->transmackey, 
+				ses.newkeys->trans_algo_mac->keysize, &hs, mactransletter);
+	}
+	if (ses.newkeys->recv_algo_mac->hashdesc != NULL) {
+		hashkeys(ses.newkeys->recvmackey, 
+				ses.newkeys->recv_algo_mac->keysize, &hs, macrecvletter);
+	}
 
 #ifndef DISABLE_ZLIB
 	gen_new_zstreams();
diff --git a/options.h b/options.h
index 6285756..86d0518 100644
--- a/options.h
+++ b/options.h
@@ -65,12 +65,26 @@ etc) slower (perhaps by 50%). Recommended for most small systems. */
  * RFC Draft requires 3DES and recommends AES128 for interoperability.
  * Including multiple keysize variants the same cipher 
  * (eg AES256 as well as AES128) will result in a minimal size increase.*/
+/*
 #define DROPBEAR_AES128_CBC
 #define DROPBEAR_3DES_CBC
 #define DROPBEAR_AES256_CBC
 #define DROPBEAR_BLOWFISH_CBC
 #define DROPBEAR_TWOFISH256_CBC
 #define DROPBEAR_TWOFISH128_CBC
+*/
+
+/* You can compile with no encryption if you want. In some circumstances
+ * this could be safe securitywise, though make sure you know what
+ * you're doing. Anyone can see everything that goes over the wire, so
+ * the only safe auth method is public key. You'll have to disable all other
+ * ciphers above in the client if you want to use this, or implement cipher
+ * prioritisation in cli-runopts.
+ *
+ * The best way to do things is probably make normal compile of dropbear with all
+ * ciphers including "none" as the server, then recompile a special 
+ * "dbclient-insecure" client. */
+#define DROPBEAR_NONE_CIPHER
 
 /* Message Integrity - at least one required.
  * RFC Draft requires sha1 and recommends sha1-96.
@@ -88,6 +102,12 @@ etc) slower (perhaps by 50%). Recommended for most small systems. */
 #define DROPBEAR_SHA1_96_HMAC
 #define DROPBEAR_MD5_HMAC
 
+/* You can also disable integrity. Don't bother disabling this if you're
+ * still using a cipher, it's relatively cheap. Don't disable this if you're
+ * using 'none' cipher, since it's dead simple to run arbitrary commands
+ * on the remote host. Go ahead. Hang yourself with your own rope. */
+/*#define DROPBEAR_NONE_INTEGRITY*/
+
 /* Hostkey/public key algorithms - at least one required, these are used
  * for hostkey as well as for verifying signatures with pubkey auth.
  * Removing either of these won't save very much space.