/*
* csum.c --- checksumming of ext3 structures
*
* Copyright (C) 2006 Cluster File Systems, Inc.
* Copyright (C) 2006, 2007 by Andreas Dilger <adilger@clusterfs.com>
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include "ext2_fs.h"
#include "ext2fs.h"
#include "crc16.h"
#include <assert.h>
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif
#ifdef DEBUG
#define STATIC
#else
#define STATIC static
#endif
__u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
{
struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
group);
size_t size = EXT2_DESC_SIZE(fs->super);
size_t offset;
__u16 crc;
if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
size_t offset = offsetof(struct ext2_group_desc, bg_checksum);
#ifdef WORDS_BIGENDIAN
struct ext4_group_desc swabdesc;
size_t save_size = size;
const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
struct ext2_group_desc *save_desc = desc;
/* Have to swab back to little-endian to do the checksum */
if (size > ext4_bg_size)
size = ext4_bg_size;
memcpy(&swabdesc, desc, size);
ext2fs_swap_group_desc2(fs,
(struct ext2_group_desc *) &swabdesc);
desc = (struct ext2_group_desc *) &swabdesc;
group = ext2fs_swab32(group);
#endif
crc = ext2fs_crc16(~0, fs->super->s_uuid,
sizeof(fs->super->s_uuid));
crc = ext2fs_crc16(crc, &group, sizeof(group));
crc = ext2fs_crc16(crc, desc, offset);
offset += sizeof(desc->bg_checksum); /* skip checksum */
/* for checksum of struct ext4_group_desc do the rest...*/
if (offset < size) {
crc = ext2fs_crc16(crc, (char *)desc + offset,
size - offset);
}
#ifdef WORDS_BIGENDIAN
/*
* If the size of the bg descriptor is greater than 64
* bytes, which is the size of the traditional ext4 bg
* descriptor, checksum the rest of the descriptor here
*/
if (save_size > ext4_bg_size)
crc = ext2fs_crc16(crc,
(char *)save_desc + ext4_bg_size,
save_size - ext4_bg_size);
#endif
}
return crc;
}
int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
{
if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
(ext2fs_bg_checksum(fs, group) !=
ext2fs_group_desc_csum(fs, group)))
return 0;
return 1;
}
void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
{
if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
return;
/* ext2fs_bg_checksum_set() sets the actual checksum field but
* does not calculate the checksum itself. */
ext2fs_bg_checksum_set(fs, group, ext2fs_group_desc_csum(fs, group));
}
static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
__u32 inodes_per_grp, dgrp_t grp_no)
{
ext2_ino_t i, start_ino, end_ino;
start_ino = grp_no * inodes_per_grp + 1;
end_ino = start_ino + inodes_per_grp - 1;
for (i = end_ino; i >= start_ino; i--) {
if (ext2fs_fast_test_inode_bitmap2(bitmap, i))
return i - start_ino + 1;
}
return inodes_per_grp;
}
/* update the bitmap flags, set the itable high watermark, and calculate
* checksums for the group descriptors */
errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
{
struct ext2_super_block *sb = fs->super;
int dirty = 0;
dgrp_t i;
if (!fs->inode_map)
return EXT2_ET_NO_INODE_BITMAP;
if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
return 0;
for (i = 0; i < fs->group_desc_count; i++) {
__u32 old_csum = ext2fs_bg_checksum(fs, i);
__u32 old_unused = ext2fs_bg_itable_unused(fs, i);
__u32 old_flags = ext2fs_bg_flags(fs, i);
__u32 old_free_inodes_count = ext2fs_bg_free_inodes_count(fs, i);
if (old_free_inodes_count == sb->s_inodes_per_group) {
ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT);
ext2fs_bg_itable_unused_set(fs, i, sb->s_inodes_per_group);
} else {
int unused =
sb->s_inodes_per_group -
find_last_inode_ingrp(fs->inode_map,
sb->s_inodes_per_group, i);
ext2fs_bg_flags_clear(fs, i, EXT2_BG_INODE_UNINIT);
ext2fs_bg_itable_unused_set(fs, i, unused);
}
ext2fs_group_desc_csum_set(fs, i);
if (old_flags != ext2fs_bg_flags(fs, i))
dirty = 1;
if (old_unused != ext2fs_bg_itable_unused(fs, i))
dirty = 1;
if (old_csum != ext2fs_bg_checksum(fs, i))
dirty = 1;
}
if (dirty)
ext2fs_mark_super_dirty(fs);
return 0;
}
#ifdef DEBUG
#include "e2p/e2p.h"
void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
{
__u16 crc1, crc2, crc3;
dgrp_t swabgroup;
struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
group);
size_t size = EXT2_DESC_SIZE(fs->super);
struct ext2_super_block *sb = fs->super;
int offset = offsetof(struct ext2_group_desc, bg_checksum);
#ifdef WORDS_BIGENDIAN
struct ext4_group_desc swabdesc;
struct ext2_group_desc *save_desc = desc;
const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
size_t save_size = size;
#endif
#ifdef WORDS_BIGENDIAN
/* Have to swab back to little-endian to do the checksum */
if (size > ext4_bg_size)
size = ext4_bg_size;
memcpy(&swabdesc, desc, size);
ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
desc = (struct ext2_group_desc *) &swabdesc;
swabgroup = ext2fs_swab32(group);
#else
swabgroup = group;
#endif
crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
crc3 = ext2fs_crc16(crc2, desc, offset);
offset += sizeof(desc->bg_checksum); /* skip checksum */
/* for checksum of struct ext4_group_desc do the rest...*/
if (offset < size)
crc3 = ext2fs_crc16(crc3, (char *)desc + offset, size - offset);
#ifdef WORDS_BIGENDIAN
if (save_size > ext4_bg_size)
crc3 = ext2fs_crc16(crc3, (char *)save_desc + ext4_bg_size,
save_size - ext4_bg_size);
#endif
printf("%s UUID %s=%04x, grp %u=%04x: %04x=%04x\n",
msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2, crc3,
ext2fs_group_desc_csum(fs, group));
}
unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };
int main(int argc, char **argv)
{
struct ext2_super_block param;
errcode_t retval;
ext2_filsys fs;
int i;
__u16 csum1, csum2, csum_known = 0xd3a4;
memset(¶m, 0, sizeof(param));
ext2fs_blocks_count_set(¶m, 32768);
#if 0
param.s_feature_incompat |= EXT4_FEATURE_INCOMPAT_64BIT;
param.s_desc_size = 128;
csum_known = 0x5b6e;
#endif
retval = ext2fs_initialize("test fs", EXT2_FLAG_64BITS, ¶m,
test_io_manager, &fs);
if (retval) {
com_err("setup", retval,
"While initializing filesystem");
exit(1);
}
memcpy(fs->super->s_uuid, sb_uuid, 16);
fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;
for (i=0; i < fs->group_desc_count; i++) {
ext2fs_block_bitmap_loc_set(fs, i, 124);
ext2fs_inode_bitmap_loc_set(fs, i, 125);
ext2fs_inode_table_loc_set(fs, i, 126);
ext2fs_bg_free_blocks_count_set(fs, i, 31119);
ext2fs_bg_free_inodes_count_set(fs, i, 15701);
ext2fs_bg_used_dirs_count_set(fs, i, 2);
ext2fs_bg_flags_zap(fs, i);
};
csum1 = ext2fs_group_desc_csum(fs, 0);
print_csum("csum0000", fs, 0);
if (csum1 != csum_known) {
printf("checksum for group 0 should be %04x\n", csum_known);
exit(1);
}
csum2 = ext2fs_group_desc_csum(fs, 1);
print_csum("csum0001", fs, 1);
if (csum1 == csum2) {
printf("checksums for different groups shouldn't match\n");
exit(1);
}
csum2 = ext2fs_group_desc_csum(fs, 2);
print_csum("csumffff", fs, 2);
if (csum1 == csum2) {
printf("checksums for different groups shouldn't match\n");
exit(1);
}
ext2fs_bg_checksum_set(fs, 0, csum1);
csum2 = ext2fs_group_desc_csum(fs, 0);
print_csum("csum_set", fs, 0);
if (csum1 != csum2) {
printf("checksums should not depend on checksum field\n");
exit(1);
}
if (!ext2fs_group_desc_csum_verify(fs, 0)) {
printf("checksums should verify against gd_checksum\n");
exit(1);
}
memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
print_csum("new_uuid", fs, 0);
if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
printf("checksums for different filesystems shouldn't match\n");
exit(1);
}
csum1 = ext2fs_group_desc_csum(fs, 0);
ext2fs_bg_checksum_set(fs, 0, csum1);
print_csum("csum_new", fs, 0);
ext2fs_bg_free_blocks_count_set(fs, 0, 1);
csum2 = ext2fs_group_desc_csum(fs, 0);
print_csum("csum_blk", fs, 0);
if (csum1 == csum2) {
printf("checksums for different data shouldn't match\n");
exit(1);
}
return 0;
}
#endif