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 Library
9 * General Public License, version 2.
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
ext2fs_group_desc_csum(ext2_filsys fs,dgrp_t group)32 __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
33 {
34 struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
35 group);
36 size_t size = EXT2_DESC_SIZE(fs->super);
37 size_t offset;
38 __u16 crc;
39
40 if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
41 size_t offset = offsetof(struct ext2_group_desc, bg_checksum);
42
43 #ifdef WORDS_BIGENDIAN
44 struct ext4_group_desc swabdesc;
45 size_t save_size = size;
46 const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
47 struct ext2_group_desc *save_desc = desc;
48
49 /* Have to swab back to little-endian to do the checksum */
50 if (size > ext4_bg_size)
51 size = ext4_bg_size;
52 memcpy(&swabdesc, desc, size);
53 ext2fs_swap_group_desc2(fs,
54 (struct ext2_group_desc *) &swabdesc);
55 desc = (struct ext2_group_desc *) &swabdesc;
56
57 group = ext2fs_swab32(group);
58 #endif
59 crc = ext2fs_crc16(~0, fs->super->s_uuid,
60 sizeof(fs->super->s_uuid));
61 crc = ext2fs_crc16(crc, &group, sizeof(group));
62 crc = ext2fs_crc16(crc, desc, offset);
63 offset += sizeof(desc->bg_checksum); /* skip checksum */
64 /* for checksum of struct ext4_group_desc do the rest...*/
65 if (offset < size) {
66 crc = ext2fs_crc16(crc, (char *)desc + offset,
67 size - offset);
68 }
69 #ifdef WORDS_BIGENDIAN
70 /*
71 * If the size of the bg descriptor is greater than 64
72 * bytes, which is the size of the traditional ext4 bg
73 * descriptor, checksum the rest of the descriptor here
74 */
75 if (save_size > ext4_bg_size)
76 crc = ext2fs_crc16(crc,
77 (char *)save_desc + ext4_bg_size,
78 save_size - ext4_bg_size);
79 #endif
80 }
81
82 return crc;
83 }
84
ext2fs_group_desc_csum_verify(ext2_filsys fs,dgrp_t group)85 int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
86 {
87 if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
88 EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
89 (ext2fs_bg_checksum(fs, group) !=
90 ext2fs_group_desc_csum(fs, group)))
91 return 0;
92
93 return 1;
94 }
95
ext2fs_group_desc_csum_set(ext2_filsys fs,dgrp_t group)96 void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
97 {
98 if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
99 EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
100 return;
101
102 /* ext2fs_bg_checksum_set() sets the actual checksum field but
103 * does not calculate the checksum itself. */
104 ext2fs_bg_checksum_set(fs, group, ext2fs_group_desc_csum(fs, group));
105 }
106
find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,__u32 inodes_per_grp,dgrp_t grp_no)107 static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
108 __u32 inodes_per_grp, dgrp_t grp_no)
109 {
110 ext2_ino_t i, start_ino, end_ino;
111
112 start_ino = grp_no * inodes_per_grp + 1;
113 end_ino = start_ino + inodes_per_grp - 1;
114
115 for (i = end_ino; i >= start_ino; i--) {
116 if (ext2fs_fast_test_inode_bitmap2(bitmap, i))
117 return i - start_ino + 1;
118 }
119 return inodes_per_grp;
120 }
121
122 /* update the bitmap flags, set the itable high watermark, and calculate
123 * checksums for the group descriptors */
ext2fs_set_gdt_csum(ext2_filsys fs)124 errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
125 {
126 struct ext2_super_block *sb = fs->super;
127 int dirty = 0;
128 dgrp_t i;
129
130 if (!fs->inode_map)
131 return EXT2_ET_NO_INODE_BITMAP;
132
133 if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
134 EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
135 return 0;
136
137 for (i = 0; i < fs->group_desc_count; i++) {
138 __u32 old_csum = ext2fs_bg_checksum(fs, i);
139 __u32 old_unused = ext2fs_bg_itable_unused(fs, i);
140 __u32 old_flags = ext2fs_bg_flags(fs, i);
141 __u32 old_free_inodes_count = ext2fs_bg_free_inodes_count(fs, i);
142
143 if (old_free_inodes_count == sb->s_inodes_per_group) {
144 ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT);
145 ext2fs_bg_itable_unused_set(fs, i, sb->s_inodes_per_group);
146 } else {
147 int unused =
148 sb->s_inodes_per_group -
149 find_last_inode_ingrp(fs->inode_map,
150 sb->s_inodes_per_group, i);
151
152 ext2fs_bg_flags_clear(fs, i, EXT2_BG_INODE_UNINIT);
153 ext2fs_bg_itable_unused_set(fs, i, unused);
154 }
155
156 ext2fs_group_desc_csum_set(fs, i);
157 if (old_flags != ext2fs_bg_flags(fs, i))
158 dirty = 1;
159 if (old_unused != ext2fs_bg_itable_unused(fs, i))
160 dirty = 1;
161 if (old_csum != ext2fs_bg_checksum(fs, i))
162 dirty = 1;
163 }
164 if (dirty)
165 ext2fs_mark_super_dirty(fs);
166 return 0;
167 }
168
169 #ifdef DEBUG
170 #include "e2p/e2p.h"
171
print_csum(const char * msg,ext2_filsys fs,dgrp_t group)172 void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
173 {
174 __u16 crc1, crc2, crc3;
175 dgrp_t swabgroup;
176 struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
177 group);
178 size_t size = EXT2_DESC_SIZE(fs->super);
179 struct ext2_super_block *sb = fs->super;
180 int offset = offsetof(struct ext2_group_desc, bg_checksum);
181 #ifdef WORDS_BIGENDIAN
182 struct ext4_group_desc swabdesc;
183 struct ext2_group_desc *save_desc = desc;
184 const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
185 size_t save_size = size;
186 #endif
187
188 #ifdef WORDS_BIGENDIAN
189 /* Have to swab back to little-endian to do the checksum */
190 if (size > ext4_bg_size)
191 size = ext4_bg_size;
192 memcpy(&swabdesc, desc, size);
193 ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
194 desc = (struct ext2_group_desc *) &swabdesc;
195
196 swabgroup = ext2fs_swab32(group);
197 #else
198 swabgroup = group;
199 #endif
200
201 crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
202 crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
203 crc3 = ext2fs_crc16(crc2, desc, offset);
204 offset += sizeof(desc->bg_checksum); /* skip checksum */
205 /* for checksum of struct ext4_group_desc do the rest...*/
206 if (offset < size)
207 crc3 = ext2fs_crc16(crc3, (char *)desc + offset, size - offset);
208 #ifdef WORDS_BIGENDIAN
209 if (save_size > ext4_bg_size)
210 crc3 = ext2fs_crc16(crc3, (char *)save_desc + ext4_bg_size,
211 save_size - ext4_bg_size);
212 #endif
213
214 printf("%s UUID %s=%04x, grp %u=%04x: %04x=%04x\n",
215 msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2, crc3,
216 ext2fs_group_desc_csum(fs, group));
217 }
218
219 unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
220 0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };
221
main(int argc,char ** argv)222 int main(int argc, char **argv)
223 {
224 struct ext2_super_block param;
225 errcode_t retval;
226 ext2_filsys fs;
227 int i;
228 __u16 csum1, csum2, csum_known = 0xd3a4;
229
230 memset(¶m, 0, sizeof(param));
231 ext2fs_blocks_count_set(¶m, 32768);
232 #if 0
233 param.s_feature_incompat |= EXT4_FEATURE_INCOMPAT_64BIT;
234 param.s_desc_size = 128;
235 csum_known = 0x5b6e;
236 #endif
237
238 retval = ext2fs_initialize("test fs", EXT2_FLAG_64BITS, ¶m,
239 test_io_manager, &fs);
240 if (retval) {
241 com_err("setup", retval,
242 "While initializing filesystem");
243 exit(1);
244 }
245 memcpy(fs->super->s_uuid, sb_uuid, 16);
246 fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;
247
248 for (i=0; i < fs->group_desc_count; i++) {
249 ext2fs_block_bitmap_loc_set(fs, i, 124);
250 ext2fs_inode_bitmap_loc_set(fs, i, 125);
251 ext2fs_inode_table_loc_set(fs, i, 126);
252 ext2fs_bg_free_blocks_count_set(fs, i, 31119);
253 ext2fs_bg_free_inodes_count_set(fs, i, 15701);
254 ext2fs_bg_used_dirs_count_set(fs, i, 2);
255 ext2fs_bg_flags_zap(fs, i);
256 };
257
258 csum1 = ext2fs_group_desc_csum(fs, 0);
259 print_csum("csum0000", fs, 0);
260
261 if (csum1 != csum_known) {
262 printf("checksum for group 0 should be %04x\n", csum_known);
263 exit(1);
264 }
265 csum2 = ext2fs_group_desc_csum(fs, 1);
266 print_csum("csum0001", fs, 1);
267 if (csum1 == csum2) {
268 printf("checksums for different groups shouldn't match\n");
269 exit(1);
270 }
271 csum2 = ext2fs_group_desc_csum(fs, 2);
272 print_csum("csumffff", fs, 2);
273 if (csum1 == csum2) {
274 printf("checksums for different groups shouldn't match\n");
275 exit(1);
276 }
277 ext2fs_bg_checksum_set(fs, 0, csum1);
278 csum2 = ext2fs_group_desc_csum(fs, 0);
279 print_csum("csum_set", fs, 0);
280 if (csum1 != csum2) {
281 printf("checksums should not depend on checksum field\n");
282 exit(1);
283 }
284 if (!ext2fs_group_desc_csum_verify(fs, 0)) {
285 printf("checksums should verify against gd_checksum\n");
286 exit(1);
287 }
288 memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
289 print_csum("new_uuid", fs, 0);
290 if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
291 printf("checksums for different filesystems shouldn't match\n");
292 exit(1);
293 }
294 csum1 = ext2fs_group_desc_csum(fs, 0);
295 ext2fs_bg_checksum_set(fs, 0, csum1);
296 print_csum("csum_new", fs, 0);
297 ext2fs_bg_free_blocks_count_set(fs, 0, 1);
298 csum2 = ext2fs_group_desc_csum(fs, 0);
299 print_csum("csum_blk", fs, 0);
300 if (csum1 == csum2) {
301 printf("checksums for different data shouldn't match\n");
302 exit(1);
303 }
304
305 return 0;
306 }
307 #endif
308