Adding support for specific vendor HID command (0x41).

It is a self implementation, based on CBOR command.
data[0] conveys the command and the contents mapped in CBOR encoding.
The map uses the authConfig template, where the fist item in the map is the subcommand (enable/disable at this moment), the second is a map of the parameters, the third and fourth are the pinUvParam and pinUvProtocol.

With this format only a single vendor HID command is necessary (0x41), which will be used for all my own commands, by using the command id in data[0] like with CBOR.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>

src/fido/cbor_vendor.c

@@ -0,0 +1,121 @@
+/*
+ * This file is part of the Pico FIDO distribution (https://github.com/polhenarejos/pico-fido).
+ * Copyright (c) 2022 Pol Henarejos.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "ctap2_cbor.h"
+#include "fido.h"
+#include "ctap.h"
+#include "files.h"
+#include "apdu.h"
+#include "hsm.h"
+
+extern bool has_keydev_dec;
+
+int cbor_vendor_generic(uint8_t cmd, const uint8_t *data, size_t len) {
+    CborParser parser;
+    CborValue map;
+    CborError error = CborNoError;
+    CborByteString pinUvAuthParam = {0}, vendorParam = {0};
+    size_t resp_size = 0;
+    uint64_t vendorCmd = 0, pinUvAuthProtocol = 0;
+    CborEncoder encoder, mapEncoder;
+
+    CBOR_CHECK(cbor_parser_init(data, len, 0, &parser, &map));
+    uint64_t val_c = 1;
+    CBOR_PARSE_MAP_START(map, 1) {
+        uint64_t val_u = 0;
+        CBOR_FIELD_GET_UINT(val_u, 1);
+        if (val_c <= 1 && val_c != val_u)
+            CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
+        if (val_u < val_c)
+            CBOR_ERROR(CTAP2_ERR_INVALID_CBOR);
+        val_c = val_u + 1;
+        if (val_u == 0x01) {
+            CBOR_FIELD_GET_UINT(vendorCmd, 1);
+        }
+        else if (val_u == 0x02) {
+            uint64_t subpara = 0;
+            CBOR_PARSE_MAP_START(_f1, 2) {
+                CBOR_FIELD_GET_UINT(subpara, 2);
+                if (subpara == 0x01) {
+                    CBOR_FIELD_GET_BYTES(vendorParam, 2);
+                }
+                else
+                    CBOR_ADVANCE(2);
+            }
+            CBOR_PARSE_MAP_END(_f1, 2);
+        }
+        else if (val_u == 0x03) {
+            CBOR_FIELD_GET_UINT(pinUvAuthProtocol, 1);
+        }
+        else if (val_u == 0x04) {
+            CBOR_FIELD_GET_BYTES(pinUvAuthParam, 1);
+        }
+    }
+    CBOR_PARSE_MAP_END(map, 1);
+
+    cbor_encoder_init(&encoder, ctap_resp->init.data + 1, CTAP_MAX_PACKET_SIZE, 0);
+
+    if (cmd == CTAP_VENDOR_BACKUP) {
+        if (vendorCmd == 0x01) {
+            if (has_keydev_dec == false)
+                CBOR_ERROR(CTAP2_ERR_PIN_AUTH_INVALID);
+
+            CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, 1));
+            CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x01));
+
+            CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, file_get_data(ef_keydev_enc), file_get_size(ef_keydev_enc)));
+        }
+        else if (vendorCmd == 0x02) {
+            if (vendorParam.present == false)
+                    CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
+            uint8_t zeros[32];
+            memset(zeros, 0, sizeof(zeros));
+            flash_write_data_to_file(ef_keydev_enc, vendorParam.data, vendorParam.len);
+            flash_write_data_to_file(ef_keydev, zeros, file_get_size(ef_keydev)); // Overwrite ef with 0
+            flash_write_data_to_file(ef_keydev, NULL, 0); // Set ef to 0 bytes
+            low_flash_available();
+            goto err;
+        }
+        else {
+            CBOR_ERROR(CTAP2_ERR_INVALID_SUBCOMMAND);
+        }
+    }
+    else
+        CBOR_ERROR(CTAP2_ERR_UNSUPPORTED_OPTION);
+    CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder));
+    resp_size = cbor_encoder_get_buffer_size(&encoder, ctap_resp->init.data + 1);
+
+    err:
+    CBOR_FREE_BYTE_STRING(pinUvAuthParam);
+    CBOR_FREE_BYTE_STRING(vendorParam);
+
+    if (error != CborNoError) {
+        if (error == CborErrorImproperValue)
+            return CTAP2_ERR_CBOR_UNEXPECTED_TYPE;
+        return error;
+    }
+    res_APDU_size = resp_size;
+    return 0;
+}
+
+int cbor_vendor(const uint8_t *data, size_t len) {
+    if (len == 0)
+        return CTAP1_ERR_INVALID_LEN;
+    if (data[0] == CTAP_VENDOR_BACKUP)
+        return cbor_vendor_generic(data[0], data + 1, len - 1);
+    return CTAP2_ERR_INVALID_CBOR;
+}