fix(core): calculate image hash including padding between header and …

…code

[no changelog]

core/embed/projects/boardloader/main.c

@@ -181,14 +181,7 @@ static uint32_t check_sdcard(void) {
     _Static_assert(IMAGE_CHUNK_SIZE >= BOOTLOADER_MAXSIZE,
                    "BOOTLOADER IMAGE MAXSIZE too large for IMAGE_CHUNK_SIZE");
 
-    const uint32_t headers_end_offset = hdr->hdrlen;
-    const uint32_t code_start_offset = IMAGE_CODE_ALIGN(headers_end_offset);
-
-    for (uint32_t i = headers_end_offset; i < code_start_offset; i++) {
-      if (((uint8_t *)sdcard_buf)[i] != 0) {
-        return 0;
-      }
-    }
+    const uint32_t code_start_offset = hdr->hdrlen;
 
     if (sectrue !=
         (check_single_hash(hdr->hashes,

core/embed/projects/bootloader/messages.c

@@ -595,21 +595,6 @@ int process_msg_FirmwareUpload(uint8_t iface_num, uint32_t msg_size,
 
       memcpy(&hdr, received_hdr, sizeof(hdr));
 
-      size_t headers_end = IMAGE_HEADER_SIZE + vhdr.hdrlen;
-      size_t tmp_headers_offset =
-          IMAGE_CODE_ALIGN(IMAGE_HEADER_SIZE + vhdr.hdrlen);
-
-      // check padding between headers and the code
-      for (size_t i = headers_end; i < tmp_headers_offset; i++) {
-        if (CHUNK_BUFFER_PTR[i] != 0) {
-          MSG_SEND_INIT(Failure);
-          MSG_SEND_ASSIGN_VALUE(code, FailureType_Failure_ProcessError);
-          MSG_SEND_ASSIGN_STRING(message, "Invalid chunk padding");
-          MSG_SEND(Failure);
-          return UPLOAD_ERR_INVALID_CHUNK_PADDING;
-        }
-      }
-
       vendor_header current_vhdr;
 
       secbool is_new = secfalse;
@@ -727,7 +712,7 @@ int process_msg_FirmwareUpload(uint8_t iface_num, uint32_t msg_size,
         ensure(erase_storage(NULL), NULL);
       }
 
-      headers_offset = IMAGE_CODE_ALIGN(IMAGE_HEADER_SIZE + vhdr.hdrlen);
+      headers_offset = IMAGE_HEADER_SIZE + vhdr.hdrlen;
       read_offset = IMAGE_INIT_CHUNK_SIZE;
 
       // request the rest of the first chunk

core/embed/projects/bootloader_ci/messages.c

@@ -556,7 +556,7 @@ int process_msg_FirmwareUpload(uint8_t iface_num, uint32_t msg_size,
 
       // no user confirmations, go directly to upload
 
-      headers_offset = IMAGE_CODE_ALIGN(IMAGE_HEADER_SIZE + vhdr.hdrlen);
+      headers_offset = IMAGE_HEADER_SIZE + vhdr.hdrlen;
       read_offset = IMAGE_INIT_CHUNK_SIZE;
 
       // request the rest of the first chunk

core/embed/sys/linker/stm32u5g/bootloader.ld

@@ -55,13 +55,18 @@ _shutdown_clear_ram_2_end = MCU_SRAM6 + MCU_SRAM6_SIZE;
 _shutdown_clear_ram_3_start = MCU_SRAM4;
 _shutdown_clear_ram_3_end = MCU_SRAM4 + MCU_SRAM4_SIZE;
 
-_codelen = SIZEOF(.flash) + SIZEOF(.data) + SIZEOF(.confidential);
+_codelen = SIZEOF(.padding) + SIZEOF(.flash) + SIZEOF(.data) + SIZEOF(.confidential);
 
 SECTIONS {
   .header : ALIGN(4) {
     KEEP(*(.header));
   } >FLASH AT>FLASH
 
+  .padding : ALIGN(4) {
+    . = ALIGN(4);
+    . = ALIGN(CODE_ALIGNMENT);
+  } >FLASH AT>FLASH
+
   .flash : ALIGN(CODE_ALIGNMENT) {
     KEEP(*(.vector_table));
     . = ALIGN(4);

core/embed/sys/linker/stm32u5g/firmware.ld

@@ -24,7 +24,7 @@ confidential_lma = LOADADDR(.confidential);
 confidential_vma = ADDR(.confidential);
 confidential_size = SIZEOF(.confidential);
 
-_codelen = SIZEOF(.flash) + SIZEOF(.data) + SIZEOF(.confidential);
+_codelen = SIZEOF(.padding) + SIZEOF(.flash) + SIZEOF(.data) + SIZEOF(.confidential);
 _flash_start = ORIGIN(FLASH);
 _flash_end = ORIGIN(FLASH) + LENGTH(FLASH);
 _heap_start = ADDR(.heap);
@@ -39,6 +39,11 @@ SECTIONS {
     KEEP(*(.header));
   } >FLASH AT>FLASH
 
+  .padding : ALIGN(4) {
+    . = ALIGN(4);
+    . = ALIGN(CODE_ALIGNMENT);
+  } >FLASH AT>FLASH
+
   .flash : ALIGN(CODE_ALIGNMENT) {
     KEEP(*(.kernel));
     . = ALIGN(COREAPP_ALIGNMENT);

core/embed/sys/linker/stm32u5g/prodtest.ld

@@ -56,7 +56,7 @@ _shutdown_clear_ram_3_start = MCU_SRAM4;
 _shutdown_clear_ram_3_end = MCU_SRAM4 + MCU_SRAM4_SIZE;
 
 
-_codelen = SIZEOF(.flash) + SIZEOF(.data) + SIZEOF(.confidential);
+_codelen = SIZEOF(.padding) + SIZEOF(.flash) + SIZEOF(.data) + SIZEOF(.confidential);
 _flash_start = ORIGIN(FLASH);
 _flash_end = ORIGIN(FLASH) + LENGTH(FLASH);
 
@@ -67,6 +67,10 @@ SECTIONS {
 
   .header : ALIGN(4) {
     KEEP(*(.header));
+  } >FLASH AT>FLASH
+
+  .padding : ALIGN(4) {
+    . = ALIGN(4);
     . = ALIGN(CODE_ALIGNMENT);
   } >FLASH AT>FLASH
 

core/embed/util/image/image.c

@@ -263,18 +263,11 @@ secbool check_image_contents(const image_header *const hdr, uint32_t firstskip,
   }
 
   // Check the firmware integrity, calculate and compare hashes
-  size_t offset = IMAGE_CODE_ALIGN(firstskip);
-  size_t end_offset = offset + hdr->codelen;
 
-  // Check area between headers and code
-  uint32_t padding_size = offset - firstskip;
-  const uint8_t *addr =
-      (uint8_t *)flash_area_get_address(area, firstskip, padding_size);
-  for (size_t i = 0; i < padding_size; i++) {
-    if (*addr++ != 0) {
-      return secfalse;
-    }
-  }
+  // check hashes of image chunks
+  // we hash the image including the padding to the end of the area
+  size_t offset = firstskip;
+  size_t end_offset = offset + hdr->codelen;
 
   while (offset < end_offset) {
     size_t bytes_to_check = MIN(IMAGE_CHUNK_SIZE - (offset % IMAGE_CHUNK_SIZE),

python/src/trezorlib/firmware/core.py

@@ -113,22 +113,11 @@ class FirmwareImage(Struct):
     SUBCON = c.Struct(
         "header" / FirmwareHeader.SUBCON,
         "_header_end" / c.Tell,
-        "padding"
-        / c.Padding(
-            lambda this: FirmwareImage.calc_padding(
-                this.header.hw_model, this._header_end
-            )
-        ),
         "_code_offset" / c.Tell,
         "code" / c.Bytes(c.this.header.code_length),
         c.Terminated,
     )
 
-    @staticmethod
-    def calc_padding(hw_model: bytes, len: int) -> int:
-        alignment = Model.from_hw_model(hw_model).code_alignment()
-        return ((len + alignment - 1) & ~(alignment - 1)) - len
-
     def get_hash_params(self) -> "util.FirmwareHashParameters":
         return Model.from_hw_model(self.header.hw_model).hash_params()
 

python/src/trezorlib/firmware/models.py

@@ -66,9 +66,6 @@ def model_keys(self, dev_keys: bool = False) -> "ModelKeys":
     def hash_params(self) -> "FirmwareHashParameters":
         return MODEL_HASH_PARAMS_MAP[self]
 
-    def code_alignment(self) -> int:
-        return MODEL_CODE_ALIGNMENT_MAP[self]
-
 
 @dataclass
 class ModelKeys:
@@ -368,18 +365,6 @@ class ModelKeys:
     Model.D002: D002_HASH_PARAMS,
 }
 
-
-MODEL_CODE_ALIGNMENT_MAP = {
-    Model.T1B1: 0x200,
-    Model.T2T1: 0x200,
-    Model.T2B1: 0x200,
-    Model.T3T1: 0x200,
-    Model.T3B1: 0x200,
-    Model.T3W1: 0x200,
-    Model.D001: 0x200,
-    Model.D002: 0x400,
-}
-
 # deprecated aliases -- don't add more
 
 TREZOR_ONE_V1V2 = LEGACY_V1V2