csum.c revision cf828f1a72ec1eb0c1e819307137879447c909b7
1/* 2 * csum.c --- checksumming of ext3 structures 3 * 4 * Copyright (C) 2006 Cluster File Systems, Inc. 5 * Copyright (C) 2006, 2007 by Andreas Dilger <adilger@clusterfs.com> 6 * 7 * %Begin-Header% 8 * This file may be redistributed under the terms of the GNU Public 9 * License. 10 * %End-Header% 11 */ 12 13#if HAVE_SYS_TYPES_H 14#include <sys/types.h> 15#endif 16 17#include "ext2_fs.h" 18#include "ext2fs.h" 19#include "crc16.h" 20#include <assert.h> 21 22#ifndef offsetof 23#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) 24#endif 25 26#ifdef DEBUG 27#define STATIC 28#else 29#define STATIC static 30#endif 31 32STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group) 33{ 34 __u16 crc = 0; 35 struct ext2_group_desc *desc; 36 37 desc = ext2fs_group_desc(fs, fs->group_desc, group); 38 39 if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) { 40 int offset = offsetof(struct ext2_group_desc, bg_checksum); 41 42#ifdef WORDS_BIGENDIAN 43 struct ext2_group_desc swabdesc = *desc; 44 45 /* Have to swab back to little-endian to do the checksum */ 46 ext2fs_swap_group_desc2(fs, &swabdesc); 47 desc = &swabdesc; 48 49 group = ext2fs_swab32(group); 50#endif 51 crc = ext2fs_crc16(~0, fs->super->s_uuid, 52 sizeof(fs->super->s_uuid)); 53 crc = ext2fs_crc16(crc, &group, sizeof(group)); 54 crc = ext2fs_crc16(crc, desc, offset); 55 offset += sizeof(desc->bg_checksum); /* skip checksum */ 56 /* for checksum of struct ext4_group_desc do the rest...*/ 57 if (offset < fs->super->s_desc_size) { 58 crc = ext2fs_crc16(crc, (char *)desc + offset, 59 fs->super->s_desc_size - offset); 60 } 61 } 62 63 return crc; 64} 65 66int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group) 67{ 68 if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super, 69 EXT4_FEATURE_RO_COMPAT_GDT_CSUM) && 70 (ext2fs_bg_checksum(fs, group) != 71 ext2fs_group_desc_csum(fs, group))) 72 return 0; 73 74 return 1; 75} 76 77void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group) 78{ 79 if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, 80 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) 81 return; 82 83 /* ext2fs_bg_checksum_set() sets the actual checksum field but 84 * does not calculate the checksum itself. */ 85 ext2fs_bg_checksum_set(fs, group, ext2fs_group_desc_csum(fs, group)); 86} 87 88static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap, 89 __u32 inodes_per_grp, dgrp_t grp_no) 90{ 91 ext2_ino_t i, start_ino, end_ino; 92 93 start_ino = grp_no * inodes_per_grp + 1; 94 end_ino = start_ino + inodes_per_grp - 1; 95 96 for (i = end_ino; i >= start_ino; i--) { 97 if (ext2fs_fast_test_inode_bitmap2(bitmap, i)) 98 return i - start_ino + 1; 99 } 100 return inodes_per_grp; 101} 102 103/* update the bitmap flags, set the itable high watermark, and calculate 104 * checksums for the group descriptors */ 105errcode_t ext2fs_set_gdt_csum(ext2_filsys fs) 106{ 107 struct ext2_super_block *sb = fs->super; 108 int dirty = 0; 109 dgrp_t i; 110 111 if (!fs->inode_map) 112 return EXT2_ET_NO_INODE_BITMAP; 113 114 if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, 115 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) 116 return 0; 117 118 for (i = 0; i < fs->group_desc_count; i++) { 119 unsigned int old_csum = ext2fs_bg_checksum(fs, i); 120 int old_unused = ext2fs_bg_itable_unused(fs, i); 121 unsigned int old_flags = ext2fs_bg_flags(fs, i); 122 int old_free_inodes_count = ext2fs_bg_free_inodes_count(fs, i); 123 124 if (old_free_inodes_count == sb->s_inodes_per_group) { 125 ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT); 126 ext2fs_bg_itable_unused_set(fs, i, sb->s_inodes_per_group); 127 } else { 128 int unused = 129 sb->s_inodes_per_group - 130 find_last_inode_ingrp(fs->inode_map, 131 sb->s_inodes_per_group, i); 132 133 ext2fs_bg_flags_clear(fs, i, EXT2_BG_INODE_UNINIT); 134 ext2fs_bg_itable_unused_set(fs, i, unused); 135 } 136 137 ext2fs_group_desc_csum_set(fs, i); 138 if (old_flags != ext2fs_bg_flags(fs, i)) 139 dirty = 1; 140 if (old_unused != ext2fs_bg_itable_unused(fs, i)) 141 dirty = 1; 142 if (old_csum != ext2fs_bg_checksum(fs, i)) 143 dirty = 1; 144 } 145 if (dirty) 146 ext2fs_mark_super_dirty(fs); 147 return 0; 148} 149 150#ifdef DEBUG 151void print_csum(const char *msg, ext2_filsys fs, dgrp_t group) 152{ 153 __u16 crc1, crc2, crc3; 154 dgrp_t swabgroup; 155 struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc, group); 156 struct ext2_super_block *sb = fs->super; 157 158#ifdef WORDS_BIGENDIAN 159 struct ext2_group_desc swabdesc = fs->group_desc[group]; 160 161 /* Have to swab back to little-endian to do the checksum */ 162 ext2fs_swap_group_desc2(fs, fs->group_desc, &swabdesc); 163 desc = &swabdesc; 164 165 swabgroup = ext2fs_swab32(group); 166#else 167 swabgroup = group; 168#endif 169 170 crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid)); 171 crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup)); 172 crc3 = ext2fs_crc16(crc2, desc, 173 offsetof(struct ext2_group_desc, bg_checksum)); 174 printf("%s: UUID %016Lx%016Lx(%04x), grp %u(%04x): %04x=%04x\n", 175 msg, *(long long *)&sb->s_uuid, *(long long *)&sb->s_uuid[8], 176 crc1, group, crc2, crc3, ext2fs_group_desc_csum(fs, group)); 177} 178 179unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23, 180 0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb }; 181 182int main(int argc, char **argv) 183{ 184 struct ext2_super_block param; 185 errcode_t retval; 186 ext2_filsys fs; 187 int i; 188 __u16 csum1, csum2, csum_known = 0xd3a4; 189 190 memset(¶m, 0, sizeof(param)); 191 ext2fs_blocks_count_set(¶m, 32768); 192 193 retval = ext2fs_initialize("test fs", EXT2_FLAG_64BITS, ¶m, 194 test_io_manager, &fs); 195 if (retval) { 196 com_err("setup", retval, 197 "While initializing filesystem"); 198 exit(1); 199 } 200 memcpy(fs->super->s_uuid, sb_uuid, 16); 201 fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM; 202 203 for (i=0; i < fs->group_desc_count; i++) { 204 ext2fs_block_bitmap_loc_set(fs, i, 124); 205 ext2fs_inode_bitmap_loc_set(fs, i, 125); 206 ext2fs_inode_table_loc_set(fs, i, 126); 207 ext2fs_bg_free_blocks_count_set(fs, i, 31119); 208 ext2fs_bg_free_inodes_count_set(fs, i, 15701); 209 ext2fs_bg_used_dirs_count_set(fs, i, 2); 210 ext2fs_bg_flags_zap(fs, i); 211 }; 212 213 csum1 = ext2fs_group_desc_csum(fs, 0); 214 print_csum("csum0000", fs, 0); 215 216 if (csum1 != csum_known) { 217 printf("checksum for group 0 should be %04x\n", csum_known); 218 exit(1); 219 } 220 csum2 = ext2fs_group_desc_csum(fs, 1); 221 print_csum("csum0001", fs, 1); 222 if (csum1 == csum2) { 223 printf("checksums for different groups shouldn't match\n"); 224 exit(1); 225 } 226 csum2 = ext2fs_group_desc_csum(fs, 2); 227 print_csum("csumffff", fs, 2); 228 if (csum1 == csum2) { 229 printf("checksums for different groups shouldn't match\n"); 230 exit(1); 231 } 232 ext2fs_bg_checksum_set(fs, 0, csum1); 233 csum2 = ext2fs_group_desc_csum(fs, 0); 234 print_csum("csum_set", fs, 0); 235 if (csum1 != csum2) { 236 printf("checksums should not depend on checksum field\n"); 237 exit(1); 238 } 239 if (!ext2fs_group_desc_csum_verify(fs, 0)) { 240 printf("checksums should verify against gd_checksum\n"); 241 exit(1); 242 } 243 memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid)); 244 print_csum("new_uuid", fs, 0); 245 if (ext2fs_group_desc_csum_verify(fs, 0) != 0) { 246 printf("checksums for different filesystems shouldn't match\n"); 247 exit(1); 248 } 249 csum1 = ext2fs_group_desc_csum(fs, 0); 250 ext2fs_bg_checksum_set(fs, 0, csum1); 251 print_csum("csum_new", fs, 0); 252 ext2fs_bg_free_blocks_count_set(fs, 0, 1); 253 csum2 = ext2fs_group_desc_csum(fs, 0); 254 print_csum("csum_blk", fs, 0); 255 if (csum1 == csum2) { 256 printf("checksums for different data shouldn't match\n"); 257 exit(1); 258 } 259 260 return 0; 261} 262#endif 263