Worked on format support #13

documentation/Extended File System (EXT).asciidoc

@@ -421,8 +421,9 @@ See section: <<checksum_types,checksum types>>
 Some versions of mkfs.ext set the file system creation time even for ext2 and
 when EXT3_FEATURE_COMPAT_HAS_JOURNAL is not set.
 
-The checksum, if checksum type is CRC-32C, contain a CRC-32 of data in the
-superblock before the checksum. The checksum is stored as 0xffffffff - CRC-32C.
+The checksum is calculated from the data in the superblock before the checksum.
+
+If checksum type is CRC-32C, the checksum is stored as 0xffffffff - CRC-32C.
 
 [yellow-background]*Is the only way to determine the file system version the
 compatibility and equivalent flags?*
@@ -641,8 +642,7 @@ Contains the lower 16-bit of the value if 64-bit support (EXT4_FEATURE_INCOMPAT_
 The checksum is a CRC-32C [yellow-background]*TODO: crc32c(s_uuid+grp_num+ibitmap)*
 | 28 | 2 | | Number of unused inodes +
 Contains the lower 16-bit of the value if 64-bit support (EXT4_FEATURE_INCOMPAT_64BIT) is enabled +
-| 30 | 2 | | Checksum +
-The checksum is a CRC-16 [yellow-background]*TODO: crc16(sb_uuid+group+desc)*
+| 30 | 2 | | Checksum
 4+| _If 64-bit support (EXT4_FEATURE_INCOMPAT_64BIT) is enabled and group descriptor size > 32_
 | 32 | 4 | | Block bitmap block number +
 Contains the upper 32-bit of the value +
@@ -674,6 +674,15 @@ The checksum is a CRC-32C [yellow-background]*TODO: crc32c(s_uuid+grp_num+ibitma
 | 64 | 4 | | [yellow-background]*Unknown (reserved)*
 |===
 
+The checksum is calculated from:
+
+* file system identifier in the superblock
+* group number
+* data of the group descriptor with the checksum set to 0-byte values.
+
+If checksum type is CRC-32C, the checksum is stored as the lower 16-bits of 0xffffffff
+- CRC-32C, otherwise the checksum is stored as CRC-16.
+
 === [[block_group_flags]]Block group flags
 
 *TODO: add description*
@@ -975,14 +984,14 @@ Contains the upper 16-bit of the checksum value
 For a character and block device the first 2 bytes of the array of direct
 block numbers contain the minor and major device number respectively.
 
-The checksum, if checksum type is CRC-32C, contain a CRC-32 of:
+The checksum is calculated from:
 
 * file system identifier in the superblock
 * inode number
 * NFS generation number in the inode
 * data of the inode with the lower and upper part of the checksum set to 0-byte values.
 
-The checksum is stored as 0xffffffff - CRC-32C.
+If checksum type is CRC-32C, the checksum is stored as 0xffffffff - CRC-32C.
 
 [yellow-background]*TODO describe extra precision*
 

libfsext/libfsext_group_descriptor.c

@@ -24,6 +24,7 @@
 #include <memory.h>
 #include <types.h>
 
+#include "libfsext_checksum.h"
 #include "libfsext_definitions.h"
 #include "libfsext_group_descriptor.h"
 #include "libfsext_io_handle.h"
@@ -146,14 +147,16 @@ int libfsext_group_descriptor_read_data(
      size_t data_size,
      libcerror_error_t **error )
 {
+	uint8_t checksum_data[ 4 ];
+	uint8_t empty_checksum_data[ 2 ]  = { 0, 0 };
+
 	static char *function             = "libfsext_group_descriptor_read_data";
 	size_t group_descriptor_data_size = 0;
 	uint64_t value_64bit              = 0;
+	uint32_t calculated_checksum      = 0;
+	uint32_t stored_checksum          = 0;
 	uint32_t value_32bit              = 0;
-
-#if defined( HAVE_DEBUG_OUTPUT )
 	uint16_t value_16bit              = 0;
-#endif
 
 	if( group_descriptor == NULL )
 	{
@@ -331,6 +334,12 @@ int libfsext_group_descriptor_read_data(
 		 ( (fsext_group_descriptor_ext4_t *) data )->number_of_unused_inodes_lower,
 		 group_descriptor->number_of_unused_inodes );
 
+		byte_stream_copy_to_uint16_little_endian(
+		 ( (fsext_group_descriptor_ext4_t *) data )->checksum,
+		 value_16bit );
+
+		stored_checksum = value_16bit;
+
 #if defined( HAVE_DEBUG_OUTPUT )
 		if( libcnotify_verbose != 0 )
 		{
@@ -587,21 +596,123 @@ int libfsext_group_descriptor_read_data(
 			 function,
 			 group_descriptor->number_of_unused_inodes );
 
-			libcnotify_printf(
-			 "%s: block bitmap checksum\t\t\t: 0x%04" PRIx32 "\n",
-			 function,
-			 group_descriptor->block_bitmap_checksum );
+			if( ( io_handle->read_only_compatible_features_flags & LIBFSEXT_READ_ONLY_COMPATIBLE_FEATURES_FLAG_METADATA_CHECKSUM ) != 0 )
+			{
+				libcnotify_printf(
+				 "%s: block bitmap checksum\t\t\t: 0x%08" PRIx32 "\n",
+				 function,
+				 group_descriptor->block_bitmap_checksum );
 
-			libcnotify_printf(
-			 "%s: inode bitmap checksum\t\t\t: 0x%04" PRIx32 "\n",
-			 function,
-			 group_descriptor->inode_bitmap_checksum );
+				libcnotify_printf(
+				 "%s: inode bitmap checksum\t\t\t: 0x%08" PRIx32 "\n",
+				 function,
+				 group_descriptor->inode_bitmap_checksum );
+			}
+			else
+			{
+				libcnotify_printf(
+				 "%s: block bitmap checksum\t\t\t: 0x%04" PRIx32 "\n",
+				 function,
+				 group_descriptor->block_bitmap_checksum );
 
+				libcnotify_printf(
+				 "%s: inode bitmap checksum\t\t\t: 0x%04" PRIx32 "\n",
+				 function,
+				 group_descriptor->inode_bitmap_checksum );
+			}
 			libcnotify_printf(
 			 "\n" );
 		}
 #endif /* defined( HAVE_DEBUG_OUTPUT ) */
 	}
+/* TODO add support for crc16 checksum */
+	if( ( io_handle->read_only_compatible_features_flags & LIBFSEXT_READ_ONLY_COMPATIBLE_FEATURES_FLAG_METADATA_CHECKSUM ) != 0 )
+	{
+		byte_stream_copy_from_uint32_little_endian(
+		 checksum_data,
+		 group_descriptor->group_number );
+
+		if( libfsext_checksum_calculate_crc32(
+		     &calculated_checksum,
+		     checksum_data,
+		     4,
+		     io_handle->metadata_checksum_seed,
+		     error ) != 1 )
+		{
+			libcerror_error_set(
+			 error,
+			 LIBCERROR_ERROR_DOMAIN_RUNTIME,
+			 LIBCERROR_RUNTIME_ERROR_SET_FAILED,
+			 "%s: unable to calculate CRC-32.",
+			 function );
+
+			return( -1 );
+		}
+		if( libfsext_checksum_calculate_crc32(
+		     &calculated_checksum,
+		     data,
+		     30,
+		     calculated_checksum,
+		     error ) != 1 )
+		{
+			libcerror_error_set(
+			 error,
+			 LIBCERROR_ERROR_DOMAIN_RUNTIME,
+			 LIBCERROR_RUNTIME_ERROR_SET_FAILED,
+			 "%s: unable to calculate CRC-32.",
+			 function );
+
+			return( -1 );
+		}
+		if( libfsext_checksum_calculate_crc32(
+		     &calculated_checksum,
+		     empty_checksum_data,
+		     2,
+		     calculated_checksum,
+		     error ) != 1 )
+		{
+			libcerror_error_set(
+			 error,
+			 LIBCERROR_ERROR_DOMAIN_RUNTIME,
+			 LIBCERROR_RUNTIME_ERROR_SET_FAILED,
+			 "%s: unable to calculate CRC-32.",
+			 function );
+
+			return( -1 );
+		}
+		if( libfsext_checksum_calculate_crc32(
+		     &calculated_checksum,
+		     &( data[ 32 ] ),
+		     data_size - 32,
+		     calculated_checksum,
+		     error ) != 1 )
+		{
+			libcerror_error_set(
+			 error,
+			 LIBCERROR_ERROR_DOMAIN_RUNTIME,
+			 LIBCERROR_RUNTIME_ERROR_SET_FAILED,
+			 "%s: unable to calculate CRC-32.",
+			 function );
+
+			return( -1 );
+		}
+		calculated_checksum = ( 0xffffffffUL - calculated_checksum ) & 0x0000ffffUL;
+
+		if( ( stored_checksum != 0 )
+		 && ( stored_checksum != calculated_checksum ) )
+		{
+#if defined( HAVE_DEBUG_OUTPUT )
+			if( libcnotify_verbose != 0 )
+			{
+				libcnotify_printf(
+				 "%s: mismatch in checksum ( 0x%08" PRIx32 " != 0x%08" PRIx32 " ).\n",
+				 function,
+				 stored_checksum,
+				 calculated_checksum );
+			}
+#endif
+		}
+	}
 	return( 1 );
 }
 

libfsext/libfsext_group_descriptor.h

@@ -37,6 +37,10 @@ typedef struct libfsext_group_descriptor libfsext_group_descriptor_t;
 
 struct libfsext_group_descriptor
 {
+	/* Group number
+	 */
+	uint32_t group_number;
+
 	/* Block bitmap block number
 	 */
 	uint64_t block_bitmap_block_number;

libfsext/libfsext_inode.c

@@ -406,7 +406,6 @@ int libfsext_inode_clone(
 int libfsext_inode_read_data(
      libfsext_inode_t *inode,
      libfsext_io_handle_t *io_handle,
-     uint32_t inode_number,
      const uint8_t *data,
      size_t data_size,
      libcerror_error_t **error )
@@ -1520,7 +1519,7 @@ int libfsext_inode_read_data(
 	{
 		byte_stream_copy_from_uint32_little_endian(
 		 checksum_data,
-		 inode_number + 1 );
+		 inode->inode_number );
 
 		if( libfsext_checksum_calculate_crc32(
 		     &calculated_checksum,
@@ -2562,7 +2561,7 @@ int libfsext_inode_read_element_data(
 	LIBFSEXT_UNREFERENCED_PARAMETER( element_flags )
 	LIBFSEXT_UNREFERENCED_PARAMETER( read_flags )
 
-	if( (uint64_t) element_index > (uint64_t) UINT32_MAX )
+	if( (uint64_t) element_index > (uint64_t) ( UINT32_MAX - 1 ) )
 	{
 		libcerror_error_set(
 		 error,
@@ -2642,10 +2641,11 @@ int libfsext_inode_read_element_data(
 
 		goto on_error;
 	}
+	inode->inode_number = (uint32_t) element_index + 1;
+
 	if( libfsext_inode_read_data(
 	     inode,
 	     io_handle,
-	     (uint32_t) element_index,
 	     data,
 	     (size_t) element_data_size,
 	     error ) != 1 )

libfsext/libfsext_inode.h

@@ -40,6 +40,10 @@ typedef struct libfsext_inode libfsext_inode_t;
 
 struct libfsext_inode
 {
+	/* Inode number
+	 */
+	uint32_t inode_number;
+
 	/* File mode
 	 */
 	uint16_t file_mode;
@@ -154,7 +158,6 @@ int libfsext_inode_clone(
 int libfsext_inode_read_data(
      libfsext_inode_t *inode,
      libfsext_io_handle_t *io_handle,
-     uint32_t inode_number,
      const uint8_t *data,
      size_t data_size,
      libcerror_error_t **error );

libfsext/libfsext_volume.c

@@ -1421,6 +1421,8 @@ int libfsext_internal_volume_read_block_groups(
 
 					goto on_error;
 				}
+				group_descriptor->group_number = group_descriptor_index;
+
 				if( libfsext_group_descriptor_read_file_io_handle(
 				     group_descriptor,
 				     internal_volume->io_handle,

tests/fsext_test_block_vector.c

@@ -173,7 +173,6 @@ int fsext_test_block_vector_initialize(
 	result = libfsext_inode_read_data(
 	          inode,
 	          io_handle,
-	          0,
 	          fsext_test_inode_data1,
 	          128,
 	          &error );
@@ -469,7 +468,6 @@ int fsext_test_block_vector_read_element_data(
 	result = libfsext_inode_read_data(
 	          inode,
 	          io_handle,
-	          0,
 	          fsext_test_inode_data1,
 	          128,
 	          &error );

tests/fsext_test_directory.c

@@ -470,7 +470,6 @@ int fsext_test_directory_read_file_io_handle(
 	result = libfsext_inode_read_data(
 	          inode,
 	          io_handle,
-	          0,
 	          fsext_test_inode_data1,
 	          128,
 	          &error );
@@ -1067,7 +1066,6 @@ int main(
 	result = libfsext_inode_read_data(
 	          inode,
 	          io_handle,
-	          0,
 	          fsext_test_inode_data1,
 	          128,
 	          &error );