pki: Fix accidental ECC switch case fallthroughs into ed25119 cases when built without ECC

Summary:
When ed25519 was introduced in commit 93c7b81b4ea1046bd2f65f4a510d5966786e8d3d,
the ed25519 case was added after the ecdsa case in src/pki.c. The ecdsa case seems to
have relied on falling through to report an error, when HAVE_ECC is not defined.
If HAVE_ECC is not defined, but ecdsa keys are used, with for example,
ssh_pki_import_pubkey_file, the code fallthroughs into the ed25519 case.

Signed-off-by: Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>

Test Plan: Unit tests passed. No memory leaks found with valgrind.

Reviewers: asn

Differential Revision: https://bugs.libssh.org/D13
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/pki.c

@@ -771,8 +771,8 @@ static int pki_import_pubkey_buffer(ssh_buffer buffer,
                 }
             }
             break;
-        case SSH_KEYTYPE_ECDSA:
 #ifdef HAVE_ECC
+        case SSH_KEYTYPE_ECDSA:
             {
                 ssh_string e;
                 ssh_string i;
@@ -1201,8 +1201,8 @@ int ssh_pki_generate(enum ssh_keytypes_e type, int parameter,
             if(rc == SSH_ERROR)
                 goto error;
             break;
-        case SSH_KEYTYPE_ECDSA:
 #ifdef HAVE_ECC
+        case SSH_KEYTYPE_ECDSA:
             rc = pki_key_generate_ecdsa(key, parameter);
             if (rc == SSH_ERROR) {
                 goto error;
@@ -1221,6 +1221,7 @@ int ssh_pki_generate(enum ssh_keytypes_e type, int parameter,
         case SSH_KEYTYPE_DSS_CERT01:
         case SSH_KEYTYPE_RSA_CERT01:
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             goto error;
     }
 

src/pki_crypto.c

@@ -697,8 +697,8 @@ ssh_string pki_private_key_to_pem(const ssh_key key,
                 goto err;
             }
             break;
-        case SSH_KEYTYPE_ECDSA:
 #ifdef HAVE_ECC
+        case SSH_KEYTYPE_ECDSA:
             if (passphrase == NULL) {
                 struct pem_get_password_struct pgp = { auth_fn, auth_data };
 
@@ -730,6 +730,7 @@ ssh_string pki_private_key_to_pem(const ssh_key key,
         case SSH_KEYTYPE_DSS_CERT01:
         case SSH_KEYTYPE_RSA_CERT01:
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             BIO_free(mem);
             SSH_LOG(SSH_LOG_WARN, "Unkown or invalid private key type %d", key->type);
             return NULL;