Add Checksums to Firmware & External App images (#1809)

* Pad image to 1MB and add simple checksum

* Test code to verify firmware checksum

* Comment out unneeded zlib

* Add files via upload

* Print space remaining in ROM

* Append checksum to external apps too

* Check external app checksums when loading

* Is it 2024 already?!

* Validate firmware checksum before flashing

* Add files via upload

* Added flash error warning to nav screen

* Clang

* Replaced some hard-coded values with #defines

* Check FW checksum before USB serial flash too

* Add files via upload

firmware/application/apps/ui_flash_utility.cpp

@@ -30,6 +30,30 @@ static const char16_t* firmware_folder = u"/FIRMWARE";
 Thread* FlashUtilityView::thread{nullptr};
 static constexpr size_t max_filename_length = 26;
 
+bool valid_firmware_file(std::filesystem::path::string_type path) {
+    File firmware_file;
+    uint32_t read_buffer[128];
+    uint32_t checksum{1};
+
+    // test read of the whole file just to validate checksum (baseband flash code will re-read when flashing)
+    auto result = firmware_file.open(path.c_str());
+    if (!result.is_valid()) {
+        checksum = 0;
+        for (uint32_t i = FLASH_STARTING_ADDRESS; i < FLASH_ROM_SIZE / sizeof(read_buffer); i++) {
+            auto readResult = firmware_file.read(&read_buffer, sizeof(read_buffer));
+
+            // if file is smaller than 1MB, assume it's a downgrade to an old FW version and ignore the checksum
+            if ((!readResult) || (readResult.value() != sizeof(read_buffer))) {
+                checksum = FLASH_EXPECTED_CHECKSUM;
+                break;
+            }
+
+            checksum += simple_checksum((uint32_t)read_buffer, sizeof(read_buffer));
+        }
+    }
+    return (checksum == FLASH_EXPECTED_CHECKSUM);
+}
+
 FlashUtilityView::FlashUtilityView(NavigationView& nav)
     : nav_(nav) {
     add_children({&labels,
@@ -111,8 +135,11 @@ void FlashUtilityView::flash_firmware(std::filesystem::path::string_type path) {
     if (endsWith(path, u".tar")) {
         // extract, then update
         path = extract_tar(u'/' + path).native();
-        if (path.empty()) return;
     }
+
+    if (path.empty() || !valid_firmware_file(path.c_str()))
+        return;  // bad firmware image - just returning back to the file list
+
     ui::Painter painter;
     painter.fill_rectangle(
         {0, 0, portapack::display.width(), portapack::display.height()},

firmware/application/apps/ui_flash_utility.hpp

@@ -32,8 +32,14 @@
 #include "untar.hpp"
 #include <cstdint>
 
+#define FLASH_ROM_SIZE 1048576
+#define FLASH_STARTING_ADDRESS 0x00000000
+#define FLASH_EXPECTED_CHECKSUM 0x00000000
+
 namespace ui {
 
+bool valid_firmware_file(std::filesystem::path::string_type path);
+
 class FlashUtilityView : public View {
    public:
     FlashUtilityView(NavigationView& nav);

firmware/application/ui_external_items_menu_loader.cpp

@@ -107,6 +107,7 @@ namespace ui {
 
 /* static */ bool ExternalItemsMenuLoader::run_external_app(ui::NavigationView& nav, std::filesystem::path filePath) {
     File app;
+    uint32_t checksum{0};
 
     auto openError = app.open(filePath);
     if (openError)
@@ -115,7 +116,6 @@ namespace ui {
     application_information_t application_information = {};
 
     auto readResult = app.read(&application_information, sizeof(application_information_t));
-
     if (!readResult)
         return false;
 
@@ -135,6 +135,8 @@ namespace ui {
             if (!readResult)
                 return false;
 
+            checksum += simple_checksum((uint32_t)&application_information.memory_location[file_read_index], readResult.value());
+
             if (readResult.value() < std::filesystem::max_file_block_size)
                 break;
         }
@@ -156,6 +158,8 @@ namespace ui {
             if (!readResult)
                 return false;
 
+            checksum += simple_checksum((uint32_t)target_memory, readResult.value());
+
             if (readResult.value() != bytes_to_read)
                 break;
         }
@@ -168,11 +172,16 @@ namespace ui {
             if (!readResult)
                 return false;
 
+            checksum += simple_checksum((uint32_t)&application_information.memory_location[file_read_index], readResult.value());
+
             if (readResult.value() < std::filesystem::max_file_block_size)
                 break;
         }
     }
 
+    if (checksum != EXT_APP_EXPECTED_CHECKSUM)
+        return false;
+
     application_information.externalAppEntry(nav);
     return true;
 }

firmware/application/ui_external_items_menu_loader.hpp

@@ -29,6 +29,8 @@
 
 #include "file.hpp"
 
+#define EXT_APP_EXPECTED_CHECKSUM 0x00000000
+
 namespace ui {
 
 template <size_t Width, size_t Height>

firmware/application/ui_navigation.cpp

@@ -503,8 +503,8 @@ void SystemStatusView::rtc_battery_workaround() {
             month = (timestamp.FAT_date >> 5) & 0xF;
             day = timestamp.FAT_date & 0x1F;
 
-            // bump to next month at 28 days for simplicity
-            if (++day > 28) {
+            // bump to next month
+            if (++day > rtc_time::days_per_month(year, month)) {
                 day = 1;
                 if (++month > 12) {
                     month = 1;
@@ -547,16 +547,16 @@ InformationView::InformationView(
                   &ltime});
 
 #if GCC_VERSION_MISMATCH
-    static constexpr Style style_gcc_warning{
-        .font = font::fixed_8x16,
-        .background = {33, 33, 33},
-        .foreground = Color::yellow(),
-    };
-    version.set_style(&style_gcc_warning);
+    version.set_style(&Styles::yellow);
 #else
     version.set_style(&style_infobar);
 #endif
 
+    if (firmware_checksum_error()) {
+        version.set("FLASH ERROR");
+        version.set_style(&Styles::red);
+    }
+
     ltime.set_style(&style_infobar);
     refresh();
     set_dirty();
@@ -568,6 +568,17 @@ void InformationView::refresh() {
     ltime.set_date_enabled(pmem::clock_with_date());
 }
 
+bool InformationView::firmware_checksum_error() {
+    static bool fw_checksum_checked{false};
+    static bool fw_checksum_error{false};
+
+    // only checking firmware checksum once per boot
+    if (!fw_checksum_checked) {
+        fw_checksum_error = (simple_checksum(FLASH_STARTING_ADDRESS, FLASH_ROM_SIZE) != FLASH_EXPECTED_CHECKSUM);
+    }
+    return fw_checksum_error;
+}
+
 /* Navigation ************************************************************/
 
 bool NavigationView::is_top() const {

firmware/application/ui_navigation.hpp

@@ -286,6 +286,7 @@ class InformationView : public View {
    public:
     InformationView(NavigationView& nav);
     void refresh();
+    bool firmware_checksum_error();
 
    private:
     // static constexpr auto version_string = "v1.4.4"; // This is commented out as we are now setting the version via ENV (VERSION_STRING=v1.0.0)

firmware/application/usb_serial_shell.cpp

@@ -41,6 +41,7 @@
 #include "chprintf.h"
 #include "chqueues.h"
 #include "ui_external_items_menu_loader.hpp"
+#include "ui_flash_utility.hpp"
 #include "untar.hpp"
 #include "ui_widget.hpp"
 
@@ -170,7 +171,13 @@ static void cmd_flash(BaseSequentialStream* chp, int argc, char* argv[]) {
     } else if (strEndsWith(path.native(), u".bin")) {
         // nothing to do for this case yet.
     } else {
-        chprintf(chp, "error only .bin or .ppfw.tar files canbe flashed.\r\n");
+        chprintf(chp, "error only .bin or .ppfw.tar files can be flashed.\r\n");
+        nav->pop();
+        return;
+    }
+
+    if (!ui::valid_firmware_file(path.native().c_str())) {
+        chprintf(chp, "error corrupt firmware file.\r\n");
         nav->pop();
         return;
     }