3 files changed, 109 insertions, 22 deletions

diff --git a/firmware/common/bootdata.c b/firmware/common/bootdata.c
new file mode 100644
index 0000000000..fa74c5fe91
--- /dev/null
+++ b/firmware/common/bootdata.c
@@ -0,0 +1,74 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ *
+ * Copyright (C) 2022 by Aidan MacDonald
+ *
+ * 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; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include "bootdata.h"
+#include "crc32.h"
+#include <stddef.h>
+
+#ifdef BOOTLOADER
+# error "not to be included in bootloader builds"
+#endif
+
+bool boot_data_valid;
+
+static bool verify_boot_data_v0(void) INIT_ATTR;
+static bool verify_boot_data_v0(void)
+{
+    /* validate protocol version */
+    if (boot_data.version != 0)
+        return false;
+
+    /* validate length */
+    if (boot_data.length != 4)
+        return false;
+
+    return true;
+}
+
+struct verify_bd_entry
+{
+    int version;
+    bool (*verify) (void);
+};
+
+static const struct verify_bd_entry verify_bd[] INITDATA_ATTR = {
+    { 0, verify_boot_data_v0 },
+};
+
+void verify_boot_data(void)
+{
+    /* verify payload with checksum - all protocol versions */
+    uint32_t crc = crc_32(boot_data.payload, boot_data.length, 0xffffffff);
+    if (crc != boot_data.crc)
+        return;
+
+    /* apply verification specific to the protocol version */
+    for (size_t i = 0; i < ARRAYLEN(verify_bd); ++i)
+    {
+        const struct verify_bd_entry *e = &verify_bd[i];
+        if (e->version == boot_data.version)
+        {
+            if (e->verify())
+                boot_data_valid = true;
+
+            return;
+        }
+    }
+}
diff --git a/firmware/common/multiboot.c b/firmware/common/multiboot.c
index c2cedc102d..c292aa1c30 100644
--- a/firmware/common/multiboot.c
+++ b/firmware/common/multiboot.c
@@ -26,44 +26,57 @@
 #include <string.h>
 #include <stdio.h>
 
+static void write_bootdata_v0(struct boot_data_t *data, unsigned int boot_volume)
+{
+    memset(data->payload, data->length, 0);
+
+    data->boot_volume = boot_volume;
+    data->version = 0;
+}
+
 /* Write bootdata into location in FIRMWARE marked by magic header
  * Assumes buffer is already loaded with the firmware image
  * We just need to find the location and write data into the
  * payload region along with the crc for later verification and use.
  * Returns payload len on success,
- * On error returns EKEY_NOT_FOUND
+ * On error returns false
  */
-int write_bootdata(unsigned char* buf, int len, unsigned int boot_volume)
+bool write_bootdata(unsigned char* buf, int len, unsigned int boot_volume)
 {
-    struct boot_data_t bl_boot_data;
-    struct boot_data_t *fw_boot_data = NULL;
     int search_len = MIN(len, BOOT_DATA_SEARCH_SIZE) - sizeof(struct boot_data_t);
-    int payload_len = EKEY_NOT_FOUND;
 
     /* search for boot data header prior to search_len */
     for(int i = 0; i < search_len; i++)
     {
-        fw_boot_data = (struct boot_data_t*) &buf[i];
-        if (fw_boot_data->magic[0] != BOOT_DATA_MAGIC0 ||
-            fw_boot_data->magic[1] != BOOT_DATA_MAGIC1)
+        struct boot_data_t *data = (struct boot_data_t *)&buf[i];
+        if (data->magic[0] != BOOT_DATA_MAGIC0 ||
+            data->magic[1] != BOOT_DATA_MAGIC1)
             continue;
 
-        memset(&bl_boot_data.payload, 0, BOOT_DATA_PAYLOAD_SIZE);
-        bl_boot_data.boot_volume = boot_volume;
+        /* Ignore it if the length extends past the end of the buffer. */
+        int data_len = offsetof(struct boot_data_t, payload) + data->length;
+        if (i + data_len > len)
+            continue;
+
+        /* Determine the maximum supported boot protocol version.
+         * Version 0 firmware may use 0 or 0xff, all other versions
+         * declare the highest supported version in the version byte. */
+        int proto_version = 0;
+        if (data->version < 0xff)
+            proto_version = MIN(BOOT_DATA_VERSION, data->version);
 
-        memset(fw_boot_data->payload, 0, fw_boot_data->length);
-        /* determine maximum bytes we can write to firmware
-           BOOT_DATA_PAYLOAD_SIZE is the size the bootloader expects */
-        payload_len = MIN(BOOT_DATA_PAYLOAD_SIZE, fw_boot_data->length);
-        fw_boot_data->length = payload_len;
-        /* copy data to FIRMWARE bootdata struct */
-        memcpy(fw_boot_data->payload, &bl_boot_data.payload, payload_len);
-        /* crc will be used within the firmware to check validity of bootdata */
-        fw_boot_data->crc = crc_32(fw_boot_data->payload, payload_len, 0xffffffff);
-        break;
+        /* Write boot data according to the selected protocol */
+        if (proto_version == 0)
+            write_bootdata_v0(data, boot_volume);
+        else
+            break;
 
+        /* Calculate payload CRC, used by all protocol versions. */
+        data->crc = crc_32(data->payload, data->length, 0xffffffff);
+        return true;
     }
-    return payload_len;
+
+    return false;
 }
 
 #ifdef HAVE_MULTIBOOT
diff --git a/firmware/common/rb-loader.c b/firmware/common/rb-loader.c
index 0256f21884..61d8b1ddd2 100644
--- a/firmware/common/rb-loader.c
+++ b/firmware/common/rb-loader.c
@@ -112,7 +112,7 @@ int load_firmware(unsigned char* buf, const char* firmware, int buffer_size)
             {
                 ret = load_firmware_filename(buf, filename, buffer_size);
             /* if firmware has no boot_data don't load from external drive */
-                if (write_bootdata(buf, ret, i) <= 0)
+                if (!write_bootdata(buf, ret, i))
                     ret = EKEY_NOT_FOUND;
             }
             /* if ret is valid breaks from loop to continue loading */