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/** @file
Block group related routines
Copyright (c) 2021 Pedro Falcato All rights reserved.
Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "Ext4Dxe.h"
/**
Retrieves a block group descriptor of the ext4 filesystem.
@param[in] Partition Pointer to the opened ext4 partition.
@param[in] BlockGroup Block group number.
@return A pointer to the block group descriptor.
**/
EXT4_BLOCK_GROUP_DESC *
Ext4GetBlockGroupDesc (
IN EXT4_PARTITION *Partition,
IN UINT32 BlockGroup
)
{
// Maybe assert that the block group nr isn't a nonsense number?
return (EXT4_BLOCK_GROUP_DESC *)((CHAR8 *)Partition->BlockGroups + BlockGroup * Partition->DescSize);
}
/**
Reads an inode from disk.
@param[in] Partition Pointer to the opened partition.
@param[in] InodeNum Number of the desired Inode
@param[out] OutIno Pointer to where it will be stored a pointer to the read inode.
@return Status of the inode read.
**/
EFI_STATUS
Ext4ReadInode (
IN EXT4_PARTITION *Partition,
IN EXT4_INO_NR InodeNum,
OUT EXT4_INODE **OutIno
)
{
UINT64 InodeOffset;
UINT32 BlockGroupNumber;
EXT4_INODE *Inode;
EXT4_BLOCK_GROUP_DESC *BlockGroup;
EXT4_BLOCK_NR InodeTableStart;
EFI_STATUS Status;
if (!EXT4_IS_VALID_INODE_NR (Partition, InodeNum)) {
DEBUG ((DEBUG_ERROR, "[ext4] Error reading inode: inode number %lu isn't valid\n", InodeNum));
return EFI_VOLUME_CORRUPTED;
}
BlockGroupNumber = (UINT32)DivU64x64Remainder (
InodeNum - 1,
Partition->SuperBlock.s_inodes_per_group,
&InodeOffset
);
// Check for the block group number's correctness
if (BlockGroupNumber >= Partition->NumberBlockGroups) {
return EFI_VOLUME_CORRUPTED;
}
Inode = Ext4AllocateInode (Partition);
if (Inode == NULL) {
return EFI_OUT_OF_RESOURCES;
}
BlockGroup = Ext4GetBlockGroupDesc (Partition, BlockGroupNumber);
// Note: We'll need to check INODE_UNINIT and friends when/if we add write support
InodeTableStart = EXT4_BLOCK_NR_FROM_HALFS (
Partition,
BlockGroup->bg_inode_table_lo,
BlockGroup->bg_inode_table_hi
);
Status = Ext4ReadDiskIo (
Partition,
Inode,
Partition->InodeSize,
EXT4_BLOCK_TO_BYTES (Partition, InodeTableStart) + MultU64x32 (InodeOffset, Partition->InodeSize)
);
if (EFI_ERROR (Status)) {
DEBUG ((
DEBUG_ERROR,
"[ext4] Error reading inode: status %x; inode offset %lx"
" inode table start %lu block group %lu\n",
Status,
InodeOffset,
InodeTableStart,
BlockGroupNumber
));
FreePool (Inode);
return Status;
}
if (!Ext4CheckInodeChecksum (Partition, Inode, InodeNum)) {
DEBUG ((
DEBUG_ERROR,
"[ext4] Inode %llu has invalid checksum (calculated %x)\n",
InodeNum,
Ext4CalculateInodeChecksum (Partition, Inode, InodeNum)
));
FreePool (Inode);
return EFI_VOLUME_CORRUPTED;
}
*OutIno = Inode;
return EFI_SUCCESS;
}
/**
Calculates the checksum of the block group descriptor for METADATA_CSUM enabled filesystems.
@param[in] Partition Pointer to the opened EXT4 partition.
@param[in] BlockGroupDesc Pointer to the block group descriptor.
@param[in] BlockGroupNum Number of the block group.
@return The checksum.
**/
STATIC
UINT16
Ext4CalculateBlockGroupDescChecksumMetadataCsum (
IN CONST EXT4_PARTITION *Partition,
IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
IN UINT32 BlockGroupNum
)
{
UINT32 Csum;
UINT16 Dummy;
Dummy = 0;
Csum = Ext4CalculateChecksum (Partition, &BlockGroupNum, sizeof (BlockGroupNum), Partition->InitialSeed);
Csum = Ext4CalculateChecksum (Partition, BlockGroupDesc, OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_checksum), Csum);
Csum = Ext4CalculateChecksum (Partition, &Dummy, sizeof (Dummy), Csum);
Csum =
Ext4CalculateChecksum (
Partition,
&BlockGroupDesc->bg_block_bitmap_hi,
Partition->DescSize - OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_block_bitmap_hi),
Csum
);
return (UINT16)Csum;
}
/**
Calculates the checksum of the block group descriptor for GDT_CSUM enabled filesystems.
@param[in] Partition Pointer to the opened EXT4 partition.
@param[in] BlockGroupDesc Pointer to the block group descriptor.
@param[in] BlockGroupNum Number of the block group.
@return The checksum.
**/
STATIC
UINT16
Ext4CalculateBlockGroupDescChecksumGdtCsum (
IN CONST EXT4_PARTITION *Partition,
IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
IN UINT32 BlockGroupNum
)
{
UINT16 Csum;
Csum = CalculateCrc16Ansi (Partition->SuperBlock.s_uuid, 16, CRC16ANSI_INIT);
Csum = CalculateCrc16Ansi (&BlockGroupNum, sizeof (BlockGroupNum), Csum);
Csum = CalculateCrc16Ansi (BlockGroupDesc, OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_checksum), Csum);
Csum =
CalculateCrc16Ansi (
&BlockGroupDesc->bg_block_bitmap_hi,
Partition->DescSize - OFFSET_OF (EXT4_BLOCK_GROUP_DESC, bg_block_bitmap_hi),
Csum
);
return Csum;
}
/**
Checks if the checksum of the block group descriptor is correct.
@param[in] Partition Pointer to the opened EXT4 partition.
@param[in] BlockGroupDesc Pointer to the block group descriptor.
@param[in] BlockGroupNum Number of the block group.
@return TRUE if checksum is correct, FALSE if there is corruption.
**/
BOOLEAN
Ext4VerifyBlockGroupDescChecksum (
IN CONST EXT4_PARTITION *Partition,
IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
IN UINT32 BlockGroupNum
)
{
if (!EXT4_HAS_METADATA_CSUM (Partition) && !EXT4_HAS_GDT_CSUM (Partition)) {
return TRUE;
}
return Ext4CalculateBlockGroupDescChecksum (Partition, BlockGroupDesc, BlockGroupNum) == BlockGroupDesc->bg_checksum;
}
/**
Calculates the checksum of the block group descriptor.
@param[in] Partition Pointer to the opened EXT4 partition.
@param[in] BlockGroupDesc Pointer to the block group descriptor.
@param[in] BlockGroupNum Number of the block group.
@return The checksum.
**/
UINT16
Ext4CalculateBlockGroupDescChecksum (
IN CONST EXT4_PARTITION *Partition,
IN CONST EXT4_BLOCK_GROUP_DESC *BlockGroupDesc,
IN UINT32 BlockGroupNum
)
{
if (EXT4_HAS_METADATA_CSUM (Partition)) {
return Ext4CalculateBlockGroupDescChecksumMetadataCsum (Partition, BlockGroupDesc, BlockGroupNum);
} else if (EXT4_HAS_GDT_CSUM (Partition)) {
return Ext4CalculateBlockGroupDescChecksumGdtCsum (Partition, BlockGroupDesc, BlockGroupNum);
}
return 0;
}
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