/*
* 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 Public
* License.
* %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
STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
{
__u16 crc = 0;
struct ext2_group_desc *desc;
desc = &fs->group_desc[group];
if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
int offset = offsetof(struct ext2_group_desc, bg_checksum);
#ifdef WORDS_BIGENDIAN
struct ext2_group_desc swabdesc = *desc;
/* Have to swab back to little-endian to do the checksum */
ext2fs_swap_group_desc(&swabdesc);
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 */
assert(offset == sizeof(*desc));
/* for checksum of struct ext4_group_desc do the rest...*/
if (offset < fs->super->s_desc_size) {
crc = ext2fs_crc16(crc, (char *)desc + offset,
fs->super->s_desc_size - offset);
}
}
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) &&
(fs->group_desc[group].bg_checksum !=
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))
fs->group_desc[group].bg_checksum =
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_bitmap(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;
struct ext2_group_desc *bg = fs->group_desc;
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++, bg++) {
int old_csum = bg->bg_checksum;
int old_unused = bg->bg_itable_unused;
int old_flags = bg->bg_flags;
if (bg->bg_free_inodes_count == sb->s_inodes_per_group) {
bg->bg_flags |= EXT2_BG_INODE_UNINIT;
bg->bg_itable_unused = sb->s_inodes_per_group;
} else {
bg->bg_flags &= ~EXT2_BG_INODE_UNINIT;
bg->bg_itable_unused = sb->s_inodes_per_group -
find_last_inode_ingrp(fs->inode_map,
sb->s_inodes_per_group,i);
}
ext2fs_group_desc_csum_set(fs, i);
if (old_flags != bg->bg_flags)
dirty = 1;
if (old_unused != bg->bg_itable_unused)
dirty = 1;
if (old_csum != bg->bg_checksum)
dirty = 1;
}
if (dirty)
ext2fs_mark_super_dirty(fs);
return 0;
}
#ifdef DEBUG
void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
{
__u16 crc1, crc2, crc3;
dgrp_t swabgroup;
struct ext2_group_desc *desc = &fs->group_desc[group];
struct ext2_super_block *sb = fs->super;
#ifdef WORDS_BIGENDIAN
struct ext2_group_desc swabdesc = fs->group_desc[group];
/* Have to swab back to little-endian to do the checksum */
ext2fs_swap_group_desc(&swabdesc);
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,
offsetof(struct ext2_group_desc, bg_checksum));
printf("%s: UUID %016Lx%016Lx(%04x), grp %u(%04x): %04x=%04x\n",
msg, *(long long *)&sb->s_uuid, *(long long *)&sb->s_uuid[8],
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));
param.s_blocks_count = 32768;
retval = ext2fs_initialize("test fs", 0, ¶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++) {
fs->group_desc[i].bg_block_bitmap = 124;
fs->group_desc[i].bg_inode_bitmap = 125;
fs->group_desc[i].bg_inode_table = 126;
fs->group_desc[i].bg_free_blocks_count = 31119;
fs->group_desc[i].bg_free_inodes_count = 15701;
fs->group_desc[i].bg_used_dirs_count = 2;
fs->group_desc[i].bg_flags = 0;
};
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);
}
fs->group_desc[0].bg_checksum = 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 = fs->group_desc[0].bg_checksum = ext2fs_group_desc_csum(fs, 0);
print_csum("csum_new", fs, 0);
fs->group_desc[0].bg_free_blocks_count = 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