/* * csum.c --- checksumming of ext3 structures * * Copyright (C) 2006 Cluster File Systems, Inc. * Copyright (C) 2006, 2007 by Andreas Dilger * * %Begin-Header% * This file may be redistributed under the terms of the GNU Library * General Public License, version 2. * %End-Header% */ #include "config.h" #if HAVE_SYS_TYPES_H #include #endif #include "ext2_fs.h" #include "ext2fs.h" #include "crc16.h" #include #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); __u16 crc = 0; 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