Add basic support for none cipher and MACs

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

CMakeLists.txt

@@ -228,6 +228,7 @@ message(STATUS "SFTP support: ${WITH_SFTP}")
 message(STATUS "Server support : ${WITH_SERVER}")
 message(STATUS "GSSAPI support : ${WITH_GSSAPI}")
 message(STATUS "GEX support : ${WITH_GEX}")
+message(STATUS "Support insecure none cipher and MAC : ${WITH_INSECURE_NONE}")
 message(STATUS "Pcap debugging support : ${WITH_PCAP}")
 message(STATUS "Build shared library: ${BUILD_SHARED_LIBS}")
 message(STATUS "Unit testing: ${UNIT_TESTING}")

DefineOptions.cmake

@@ -21,7 +21,8 @@ option(WITH_NACL "Build with libnacl (curve25519)" ON)
 option(WITH_SYMBOL_VERSIONING "Build with symbol versioning" ON)
 option(WITH_ABI_BREAK "Allow ABI break" OFF)
 option(WITH_GEX "Enable DH Group exchange mechanisms" ON)
-option(FUZZ_TESTING "Build with fuzzer for the server" OFF)
+option(WITH_INSECURE_NONE "Enable insecure none cipher and MAC algorithms (not suitable for production!)" OFF)
+option(FUZZ_TESTING "Build with fuzzer for the server and client (automatically enables none cipher!)" OFF)
 option(PICKY_DEVELOPER "Build with picky developer flags" OFF)
 
 if (WITH_ZLIB)
@@ -54,3 +55,7 @@ endif (NOT GLOBAL_BIND_CONFIG)
 if (NOT GLOBAL_CLIENT_CONFIG)
   set(GLOBAL_CLIENT_CONFIG "/etc/ssh/ssh_config")
 endif (NOT GLOBAL_CLIENT_CONFIG)
+
+if (FUZZ_TESTING)
+  set(WITH_INSECURE_NONE ON)
+endif (FUZZ_TESTING)

config.h.cmake

@@ -269,6 +269,9 @@
 /* Define to 1 if you want to enable DH group exchange algorithms */
 #cmakedefine WITH_GEX 1
 
+/* Define to 1 if you want to enable none cipher and MAC */
+#cmakedefine WITH_INSECURE_NONE 1
+
 /* Define to 1 if you want to enable blowfish cipher support */
 #cmakedefine WITH_BLOWFISH_CIPHER 1
 

include/libssh/wrapper.h

@@ -42,7 +42,8 @@ enum ssh_hmac_e {
   SSH_HMAC_SHA512,
   SSH_HMAC_MD5,
   SSH_HMAC_AEAD_POLY1305,
-  SSH_HMAC_AEAD_GCM
+  SSH_HMAC_AEAD_GCM,
+  SSH_HMAC_NONE,
 };
 
 enum ssh_des_e {

src/kex.c

@@ -125,6 +125,12 @@
 #define DSA_PUBLIC_KEY_ALGORITHMS ""
 #endif
 
+#ifdef WITH_INSECURE_NONE
+#define NONE ",none"
+#else
+#define NONE
+#endif
+
 #define HOSTKEYS "ssh-ed25519," \
                  EC_HOSTKEYS \
                  "rsa-sha2-512," \
@@ -239,10 +245,10 @@ static const char *default_methods[] = {
 static const char *supported_methods[] = {
   KEY_EXCHANGE_SUPPORTED,
   PUBLIC_KEY_ALGORITHMS,
-  CHACHA20 AES BLOWFISH DES_SUPPORTED,
-  CHACHA20 AES BLOWFISH DES_SUPPORTED,
-  "hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1",
-  "hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1",
+  CHACHA20 AES BLOWFISH DES_SUPPORTED NONE,
+  CHACHA20 AES BLOWFISH DES_SUPPORTED NONE,
+  "hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1" NONE,
+  "hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1" NONE,
   ZLIB,
   ZLIB,
   "",

src/libcrypto.c

@@ -1275,6 +1275,17 @@ chacha20_poly1305_aead_encrypt(struct ssh_cipher_struct *cipher,
 }
 #endif /* defined(HAVE_OPENSSL_EVP_CHACHA20) && defined(HAVE_OPENSSL_EVP_POLY1305) */
 
+#ifdef WITH_INSECURE_NONE
+static void
+none_crypt(UNUSED_PARAM(struct ssh_cipher_struct *cipher),
+           void *in,
+           void *out,
+           size_t len)
+{
+    memcpy(out, in, len);
+}
+#endif /* WITH_INSECURE_NONE */
+
 /*
  * The table of supported ciphers
  */
@@ -1463,6 +1474,15 @@ static struct ssh_cipher_struct ssh_ciphertab[] = {
     .name = "chacha20-poly1305@openssh.com"
 #endif /* defined(HAVE_OPENSSL_EVP_CHACHA20) && defined(HAVE_OPENSSL_EVP_POLY1305) */
   },
+#ifdef WITH_INSECURE_NONE
+  {
+    .name = "none",
+    .blocksize = 8,
+    .keysize = 0,
+    .encrypt = none_crypt,
+    .decrypt = none_crypt,
+  },
+#endif /* WITH_INSECURE_NONE */
   {
     .name = NULL
   }

src/libgcrypt.c

@@ -881,6 +881,17 @@ out:
 }
 #endif /* HAVE_GCRYPT_CHACHA_POLY */
 
+#ifdef WITH_INSECURE_NONE
+static void
+none_crypt(UNUSED_PARAM(struct ssh_cipher_struct *cipher),
+           void *in,
+           void *out,
+           size_t len)
+{
+    memcpy(out, in, len);
+}
+#endif /* WITH_INSECURE_NONE */
+
 /* the table of supported ciphers */
 static struct ssh_cipher_struct ssh_ciphertab[] = {
 #ifdef WITH_BLOWFISH_CIPHER
@@ -1020,6 +1031,15 @@ static struct ssh_cipher_struct ssh_ciphertab[] = {
     .name = "chacha20-poly1305@openssh.com"
 #endif
   },
+#ifdef WITH_INSECURE_NONE
+  {
+    .name            = "none",
+    .blocksize       = 8,
+    .keysize         = 0,
+    .encrypt         = none_crypt,
+    .decrypt         = none_crypt
+  },
+#endif /* WITH_INSECURE_NONE */
   {
     .name            = NULL,
     .blocksize       = 0,

src/libmbedcrypto.c

@@ -1216,6 +1216,17 @@ static void cipher_cleanup(struct ssh_cipher_struct *cipher)
 #endif /* MBEDTLS_GCM_C */
 }
 
+#ifdef WITH_INSECURE_NONE
+static void
+none_crypt(UNUSED_PARAM(struct ssh_cipher_struct *cipher),
+           void *in,
+           void *out,
+           size_t len)
+{
+    memcpy(out, in, len);
+}
+#endif /* WITH_INSECURE_NONE */
+
 static struct ssh_cipher_struct ssh_ciphertab[] = {
 #ifdef WITH_BLOWFISH_CIPHER
     {
@@ -1356,6 +1367,15 @@ static struct ssh_cipher_struct ssh_ciphertab[] = {
         .name = "chacha20-poly1305@openssh.com"
 #endif
     },
+#ifdef WITH_INSECURE_NONE
+    {
+        .name = "none",
+        .blocksize = 8,
+        .keysize = 0,
+        .encrypt = none_crypt,
+        .decrypt = none_crypt,
+    },
+#endif /* WITH_INSECURE_NONE */
     {
         .name = NULL,
         .blocksize = 0,

src/wrapper.c

@@ -66,6 +66,9 @@ static struct ssh_hmac_struct ssh_hmac_tab[] = {
   { "hmac-sha2-256-etm@openssh.com", SSH_HMAC_SHA256,        true  },
   { "hmac-sha2-512-etm@openssh.com", SSH_HMAC_SHA512,        true  },
   { "hmac-md5-etm@openssh.com",      SSH_HMAC_MD5,           true  },
+#ifdef WITH_INSECURE_NONE
+  { "none",                          SSH_HMAC_NONE,          false },
+#endif /* WITH_INSECURE_NONE */
   { NULL,                            0,                      false }
 };