From 6c60a37e8acec9bc72f15e33943cbfa4deed7bf2 Mon Sep 17 00:00:00 2001
From: Szczepan Zalega <szczepan@nitrokey.com>
Date: Tue, 20 Aug 2019 11:19:22 +0200
Subject: [PATCH] Add initial STATE migration code

---
 fido2/data_migration.c | 87 ++++++++++++++++++++++++++++++++++++++++++
 fido2/data_migration.h | 15 ++++++++
 2 files changed, 102 insertions(+)
 create mode 100644 fido2/data_migration.c
 create mode 100644 fido2/data_migration.h

diff --git a/fido2/data_migration.c b/fido2/data_migration.c
new file mode 100644
index 0000000..e4cbcf1
--- /dev/null
+++ b/fido2/data_migration.c
@@ -0,0 +1,87 @@
+// Copyright 2019 SoloKeys Developers
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. This file may not be
+// copied, modified, or distributed except according to those terms.
+
+#include "data_migration.h"
+#include "log.h"
+#include "device.h"
+#include "crypto.h"
+
+// TODO move from macro to function/assert for better readability?
+#define check(x) assert(state_prev_0xff->x == state_tmp_ptr->x);
+#define check_buf(x) assert(memcmp(state_prev_0xff->x, state_tmp_ptr->x, sizeof(state_tmp_ptr->x)) == 0);
+
+bool migrate_from_FF_to_01(AuthenticatorState* state_previous_ptr, AuthenticatorState* state_tmp_ptr){
+    // Calculate PIN hash, and replace PIN raw storage with it; add version to structure
+    // other ingredients do not change
+    if (state_tmp_ptr->data_version != 0xFF)
+        return false;
+
+    static_assert(sizeof(AuthenticatorState_0xFF) <= sizeof(AuthenticatorState), "New state structure is smaller, than current one, which is not handled");
+
+    AuthenticatorState_0xFF* state_prev_0xff = (AuthenticatorState_0xFF *) state_previous_ptr;
+
+    if (ctap_generate_rng(state_tmp_ptr->PIN_SALT, sizeof(state_tmp_ptr->PIN_SALT)) != 1) {
+        printf2(TAG_ERR, "Error, rng failed\n");
+        return false;
+    }
+    if (state_prev_0xff->is_pin_set){
+        crypto_sha256_init();
+        crypto_sha256_update(state_prev_0xff->pin_code, state_prev_0xff->pin_code_length);
+        uint8_t intermediateHash[32];
+        crypto_sha256_final(intermediateHash);
+
+        crypto_sha256_init();
+        crypto_sha256_update(intermediateHash, 16);
+        memset(intermediateHash, 0, sizeof(intermediateHash));
+        crypto_sha256_update(state_tmp_ptr->PIN_SALT, sizeof(state_tmp_ptr->PIN_SALT));
+        crypto_sha256_final(state_tmp_ptr->PIN_CODE_HASH);
+    }
+
+    state_tmp_ptr->_reserved = 0xFF;
+    state_tmp_ptr->data_version = 1;
+
+    check(is_pin_set);
+    check(rk_stored);
+    check(remaining_tries);
+    check_buf(key_lens);
+    check_buf(key_space);
+
+    return true;
+}
+
+void save_migrated_state(AuthenticatorState *state_tmp_ptr) {
+    memmove(&STATE, state_tmp_ptr, sizeof(AuthenticatorState));
+    authenticator_write_state(state_tmp_ptr, 0);
+    authenticator_write_state(state_tmp_ptr, 1);
+}
+
+void do_migration_if_required(AuthenticatorState* state_current){
+    // Currently handles only state structures with the same size, or bigger
+    // FIXME rework to raw buffers with fixed size to allow state structure size decrease
+    if(!state_current->is_initialized)
+        return;
+
+    AuthenticatorState state_tmp;
+    AuthenticatorState state_previous;
+    authenticator_read_state(&state_previous);
+    authenticator_read_state(&state_tmp);
+    if(state_current->data_version == 0xFF){
+        printf2(TAG_ERR, "Running migration\n");
+        bool success = migrate_from_FF_to_01(&state_previous, &state_tmp);
+        if (!success){
+            printf2(TAG_ERR, "Failed migration from 0xFF to 1\n");
+            // FIXME discuss migration failure behavior
+            goto return_cleanup;
+        }
+        dump_hex1(TAG_ERR, (void*)&state_tmp, sizeof(state_tmp));
+        dump_hex1(TAG_ERR, (void*)&state_previous, sizeof(state_previous));
+        save_migrated_state(&state_tmp);
+    }
+    return_cleanup:
+    memset(&state_tmp, 0, sizeof(AuthenticatorState));
+    memset(&state_previous, 0, sizeof(AuthenticatorState));
+}
diff --git a/fido2/data_migration.h b/fido2/data_migration.h
new file mode 100644
index 0000000..ffdd9b7
--- /dev/null
+++ b/fido2/data_migration.h
@@ -0,0 +1,15 @@
+// Copyright 2019 SoloKeys Developers
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. This file may not be
+// copied, modified, or distributed except according to those terms.
+
+#ifndef FIDO2_PR_DATA_MIGRATION_H
+#define FIDO2_PR_DATA_MIGRATION_H
+
+#include "storage.h"
+
+void do_migration_if_required(AuthenticatorState* state_current);
+
+#endif //FIDO2_PR_DATA_MIGRATION_H