2 * csum.c --- checksumming of ext3 structures
4 * Copyright (C) 2006 Cluster File Systems, Inc.
5 * Copyright (C) 2006, 2007 by Andreas Dilger <adilger@clusterfs.com>
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
15 #include <sys/types.h>
24 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
33 __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
36 struct ext2_group_desc *desc;
39 size = fs->super->s_desc_size;
40 if (size < EXT2_MIN_DESC_SIZE)
41 size = EXT2_MIN_DESC_SIZE;
42 if (size > sizeof(struct ext4_group_desc)) {
43 printf("%s: illegal s_desc_size(%zd)\n", __func__, size);
44 size = sizeof(struct ext4_group_desc);
47 desc = ext2fs_group_desc(fs, fs->group_desc, group);
49 if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
50 size_t offset = offsetof(struct ext2_group_desc, bg_checksum);
52 #ifdef WORDS_BIGENDIAN
53 struct ext4_group_desc swabdesc;
55 /* Have to swab back to little-endian to do the checksum */
56 memcpy(&swabdesc, desc, size);
57 ext2fs_swap_group_desc2(fs,
58 (struct ext2_group_desc *) &swabdesc);
59 desc = (struct ext2_group_desc *) &swabdesc;
61 group = ext2fs_swab32(group);
63 crc = ext2fs_crc16(~0, fs->super->s_uuid,
64 sizeof(fs->super->s_uuid));
65 crc = ext2fs_crc16(crc, &group, sizeof(group));
66 crc = ext2fs_crc16(crc, desc, offset);
67 offset += sizeof(desc->bg_checksum); /* skip checksum */
68 /* for checksum of struct ext4_group_desc do the rest...*/
70 crc = ext2fs_crc16(crc, (char *)desc + offset,
78 int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
80 if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
81 EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
82 (ext2fs_bg_checksum(fs, group) !=
83 ext2fs_group_desc_csum(fs, group)))
89 void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
91 if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
92 EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
95 /* ext2fs_bg_checksum_set() sets the actual checksum field but
96 * does not calculate the checksum itself. */
97 ext2fs_bg_checksum_set(fs, group, ext2fs_group_desc_csum(fs, group));
100 static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
101 __u32 inodes_per_grp, dgrp_t grp_no)
103 ext2_ino_t i, start_ino, end_ino;
105 start_ino = grp_no * inodes_per_grp + 1;
106 end_ino = start_ino + inodes_per_grp - 1;
108 for (i = end_ino; i >= start_ino; i--) {
109 if (ext2fs_fast_test_inode_bitmap2(bitmap, i))
110 return i - start_ino + 1;
112 return inodes_per_grp;
115 /* update the bitmap flags, set the itable high watermark, and calculate
116 * checksums for the group descriptors */
117 errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
119 struct ext2_super_block *sb = fs->super;
124 return EXT2_ET_NO_INODE_BITMAP;
126 if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
127 EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
130 for (i = 0; i < fs->group_desc_count; i++) {
131 __u32 old_csum = ext2fs_bg_checksum(fs, i);
132 __u32 old_unused = ext2fs_bg_itable_unused(fs, i);
133 __u32 old_flags = ext2fs_bg_flags(fs, i);
134 __u32 old_free_inodes_count = ext2fs_bg_free_inodes_count(fs, i);
136 if (old_free_inodes_count == sb->s_inodes_per_group) {
137 ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT);
138 ext2fs_bg_itable_unused_set(fs, i, sb->s_inodes_per_group);
141 sb->s_inodes_per_group -
142 find_last_inode_ingrp(fs->inode_map,
143 sb->s_inodes_per_group, i);
145 ext2fs_bg_flags_clear(fs, i, EXT2_BG_INODE_UNINIT);
146 ext2fs_bg_itable_unused_set(fs, i, unused);
149 ext2fs_group_desc_csum_set(fs, i);
150 if (old_flags != ext2fs_bg_flags(fs, i))
152 if (old_unused != ext2fs_bg_itable_unused(fs, i))
154 if (old_csum != ext2fs_bg_checksum(fs, i))
158 ext2fs_mark_super_dirty(fs);
165 void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
167 __u16 crc1, crc2, crc3;
169 struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc, group);
171 struct ext2_super_block *sb = fs->super;
172 int offset = offsetof(struct ext2_group_desc, bg_checksum);
173 #ifdef WORDS_BIGENDIAN
174 struct ext4_group_desc swabdesc;
177 size = fs->super->s_desc_size;
178 if (size < EXT2_MIN_DESC_SIZE)
179 size = EXT2_MIN_DESC_SIZE;
180 if (size > sizeof(struct ext4_group_desc))
181 size = sizeof(struct ext4_group_desc);
182 #ifdef WORDS_BIGENDIAN
183 /* Have to swab back to little-endian to do the checksum */
184 memcpy(&swabdesc, desc, size);
185 ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
186 desc = (struct ext2_group_desc *) &swabdesc;
188 swabgroup = ext2fs_swab32(group);
193 crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
194 crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
195 crc3 = ext2fs_crc16(crc2, desc, offset);
196 offset += sizeof(desc->bg_checksum); /* skip checksum */
197 /* for checksum of struct ext4_group_desc do the rest...*/
199 crc3 = ext2fs_crc16(crc3, (char *)desc + offset, size - offset);
201 printf("%s: UUID %s(%04x), grp %u(%04x): %04x=%04x\n",
202 msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2, crc3,
203 ext2fs_group_desc_csum(fs, group));
206 unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
207 0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };
209 int main(int argc, char **argv)
211 struct ext2_super_block param;
215 __u16 csum1, csum2, csum_known = 0xd3a4;
217 memset(¶m, 0, sizeof(param));
218 ext2fs_blocks_count_set(¶m, 32768);
220 retval = ext2fs_initialize("test fs", EXT2_FLAG_64BITS, ¶m,
221 test_io_manager, &fs);
223 com_err("setup", retval,
224 "While initializing filesystem");
227 memcpy(fs->super->s_uuid, sb_uuid, 16);
228 fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;
230 for (i=0; i < fs->group_desc_count; i++) {
231 ext2fs_block_bitmap_loc_set(fs, i, 124);
232 ext2fs_inode_bitmap_loc_set(fs, i, 125);
233 ext2fs_inode_table_loc_set(fs, i, 126);
234 ext2fs_bg_free_blocks_count_set(fs, i, 31119);
235 ext2fs_bg_free_inodes_count_set(fs, i, 15701);
236 ext2fs_bg_used_dirs_count_set(fs, i, 2);
237 ext2fs_bg_flags_zap(fs, i);
240 csum1 = ext2fs_group_desc_csum(fs, 0);
241 print_csum("csum0000", fs, 0);
243 if (csum1 != csum_known) {
244 printf("checksum for group 0 should be %04x\n", csum_known);
247 csum2 = ext2fs_group_desc_csum(fs, 1);
248 print_csum("csum0001", fs, 1);
249 if (csum1 == csum2) {
250 printf("checksums for different groups shouldn't match\n");
253 csum2 = ext2fs_group_desc_csum(fs, 2);
254 print_csum("csumffff", fs, 2);
255 if (csum1 == csum2) {
256 printf("checksums for different groups shouldn't match\n");
259 ext2fs_bg_checksum_set(fs, 0, csum1);
260 csum2 = ext2fs_group_desc_csum(fs, 0);
261 print_csum("csum_set", fs, 0);
262 if (csum1 != csum2) {
263 printf("checksums should not depend on checksum field\n");
266 if (!ext2fs_group_desc_csum_verify(fs, 0)) {
267 printf("checksums should verify against gd_checksum\n");
270 memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
271 print_csum("new_uuid", fs, 0);
272 if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
273 printf("checksums for different filesystems shouldn't match\n");
276 csum1 = ext2fs_group_desc_csum(fs, 0);
277 ext2fs_bg_checksum_set(fs, 0, csum1);
278 print_csum("csum_new", fs, 0);
279 ext2fs_bg_free_blocks_count_set(fs, 0, 1);
280 csum2 = ext2fs_group_desc_csum(fs, 0);
281 print_csum("csum_blk", fs, 0);
282 if (csum1 == csum2) {
283 printf("checksums for different data shouldn't match\n");