1 /** 2 * bootsect.c - Boot sector handling code. Originated from the Linux-NTFS project. 3 * 4 * Copyright (c) 2000-2006 Anton Altaparmakov 5 * Copyright (c) 2003-2006 Szabolcs Szakacsits 6 * Copyright (c) 2005 Yura Pakhuchiy 7 * 8 * This program/include file is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License as published 10 * by the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program/include file is distributed in the hope that it will be 14 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty 15 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program (in the main directory of the NTFS-3G 20 * distribution in the file COPYING); if not, write to the Free Software 21 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 22 */ 23 24 #ifdef HAVE_CONFIG_H 25 #include "config.h" 26 #endif 27 28 #ifdef HAVE_STDIO_H 29 #include <stdio.h> 30 #endif 31 #ifdef HAVE_STDLIB_H 32 #include <stdlib.h> 33 #endif 34 #ifdef HAVE_STRING_H 35 #include <string.h> 36 #endif 37 #ifdef HAVE_ERRNO_H 38 #include <errno.h> 39 #endif 40 41 #include "compat.h" 42 #include "bootsect.h" 43 #include "debug.h" 44 #include "logging.h" 45 46 /** 47 * ntfs_boot_sector_is_ntfs - check if buffer contains a valid ntfs boot sector 48 * @b: buffer containing putative boot sector to analyze 49 * @silent: if zero, output progress messages to stderr 50 * 51 * Check if the buffer @b contains a valid ntfs boot sector. The buffer @b 52 * must be at least 512 bytes in size. 53 * 54 * If @silent is zero, output progress messages to stderr. Otherwise, do not 55 * output any messages (except when configured with --enable-debug in which 56 * case warning/debug messages may be displayed). 57 * 58 * Return TRUE if @b contains a valid ntfs boot sector and FALSE if not. 59 */ 60 BOOL ntfs_boot_sector_is_ntfs(NTFS_BOOT_SECTOR *b) 61 { 62 u32 i; 63 BOOL ret = FALSE; 64 65 ntfs_log_debug("Beginning bootsector check.\n"); 66 67 ntfs_log_debug("Checking OEMid, NTFS signature.\n"); 68 if (b->oem_id != cpu_to_le64(0x202020205346544eULL)) { /* "NTFS " */ 69 ntfs_log_error("NTFS signature is missing.\n"); 70 goto not_ntfs; 71 } 72 73 ntfs_log_debug("Checking bytes per sector.\n"); 74 if (le16_to_cpu(b->bpb.bytes_per_sector) < 256 || 75 le16_to_cpu(b->bpb.bytes_per_sector) > 4096) { 76 ntfs_log_error("Unexpected bytes per sector value (%d).\n", 77 le16_to_cpu(b->bpb.bytes_per_sector)); 78 goto not_ntfs; 79 } 80 81 ntfs_log_debug("Checking sectors per cluster.\n"); 82 switch (b->bpb.sectors_per_cluster) { 83 case 1: case 2: case 4: case 8: case 16: case 32: case 64: case 128: 84 break; 85 default: 86 ntfs_log_error("Unexpected sectors per cluster value (%d).\n", 87 b->bpb.sectors_per_cluster); 88 goto not_ntfs; 89 } 90 91 ntfs_log_debug("Checking cluster size.\n"); 92 i = (u32)le16_to_cpu(b->bpb.bytes_per_sector) * 93 b->bpb.sectors_per_cluster; 94 if (i > 65536) { 95 ntfs_log_error("Unexpected cluster size (%d).\n", i); 96 goto not_ntfs; 97 } 98 99 ntfs_log_debug("Checking reserved fields are zero.\n"); 100 if (le16_to_cpu(b->bpb.reserved_sectors) || 101 le16_to_cpu(b->bpb.root_entries) || 102 le16_to_cpu(b->bpb.sectors) || 103 le16_to_cpu(b->bpb.sectors_per_fat) || 104 le32_to_cpu(b->bpb.large_sectors) || 105 b->bpb.fats) { 106 ntfs_log_error("Reserved fields aren't zero " 107 "(%d, %d, %d, %d, %d, %d).\n", 108 le16_to_cpu(b->bpb.reserved_sectors), 109 le16_to_cpu(b->bpb.root_entries), 110 le16_to_cpu(b->bpb.sectors), 111 le16_to_cpu(b->bpb.sectors_per_fat), 112 le32_to_cpu(b->bpb.large_sectors), 113 b->bpb.fats); 114 goto not_ntfs; 115 } 116 117 ntfs_log_debug("Checking clusters per mft record.\n"); 118 if ((u8)b->clusters_per_mft_record < 0xe1 || 119 (u8)b->clusters_per_mft_record > 0xf7) { 120 switch (b->clusters_per_mft_record) { 121 case 1: case 2: case 4: case 8: case 0x10: case 0x20: case 0x40: 122 break; 123 default: 124 ntfs_log_error("Unexpected clusters per mft record " 125 "(%d).\n", b->clusters_per_mft_record); 126 goto not_ntfs; 127 } 128 } 129 130 ntfs_log_debug("Checking clusters per index block.\n"); 131 if ((u8)b->clusters_per_index_record < 0xe1 || 132 (u8)b->clusters_per_index_record > 0xf7) { 133 switch (b->clusters_per_index_record) { 134 case 1: case 2: case 4: case 8: case 0x10: case 0x20: case 0x40: 135 break; 136 default: 137 ntfs_log_error("Unexpected clusters per index record " 138 "(%d).\n", b->clusters_per_index_record); 139 goto not_ntfs; 140 } 141 } 142 143 if (b->end_of_sector_marker != cpu_to_le16(0xaa55)) 144 ntfs_log_debug("Warning: Bootsector has invalid end of sector " 145 "marker.\n"); 146 147 ntfs_log_debug("Bootsector check completed successfully.\n"); 148 149 ret = TRUE; 150 not_ntfs: 151 return ret; 152 } 153 154 /** 155 * ntfs_boot_sector_parse - setup an ntfs volume from an ntfs boot sector 156 * @vol: ntfs_volume to setup 157 * @bs: buffer containing ntfs boot sector to parse 158 * 159 * Parse the ntfs bootsector @bs and setup the ntfs volume @vol with the 160 * obtained values. 161 * 162 * Return 0 on success or -1 on error with errno set to the error code EINVAL. 163 */ 164 int ntfs_boot_sector_parse(ntfs_volume *vol, const NTFS_BOOT_SECTOR *bs) 165 { 166 s64 sectors; 167 u8 sectors_per_cluster; 168 s8 c; 169 170 /* We return -1 with errno = EINVAL on error. */ 171 errno = EINVAL; 172 173 vol->sector_size = le16_to_cpu(bs->bpb.bytes_per_sector); 174 vol->sector_size_bits = ffs(vol->sector_size) - 1; 175 ntfs_log_debug("SectorSize = 0x%x\n", vol->sector_size); 176 ntfs_log_debug("SectorSizeBits = %u\n", vol->sector_size_bits); 177 /* 178 * The bounds checks on mft_lcn and mft_mirr_lcn (i.e. them being 179 * below or equal the number_of_clusters) really belong in the 180 * ntfs_boot_sector_is_ntfs but in this way we can just do this once. 181 */ 182 sectors_per_cluster = bs->bpb.sectors_per_cluster; 183 ntfs_log_debug("SectorsPerCluster = 0x%x\n", sectors_per_cluster); 184 if (sectors_per_cluster & (sectors_per_cluster - 1)) { 185 ntfs_log_error("sectors_per_cluster (%d) is not a power of 2." 186 "\n", sectors_per_cluster); 187 return -1; 188 } 189 190 sectors = sle64_to_cpu(bs->number_of_sectors); 191 ntfs_log_debug("NumberOfSectors = %lld\n", sectors); 192 if (!sectors) { 193 ntfs_log_error("Volume size is set to zero.\n"); 194 return -1; 195 } 196 if (vol->dev->d_ops->seek(vol->dev, 197 (sectors - 1) << vol->sector_size_bits, 198 SEEK_SET) == -1) { 199 ntfs_log_perror("Failed to read last sector (%lld)", 200 (long long)sectors); 201 ntfs_log_error("Perhaps the volume is a RAID/LDM but it wasn't " 202 "setup yet, or the\nwrong device was used, " 203 "or the partition table is incorrect.\n" ); 204 return -1; 205 } 206 207 vol->nr_clusters = sectors >> (ffs(sectors_per_cluster) - 1); 208 209 vol->mft_lcn = sle64_to_cpu(bs->mft_lcn); 210 vol->mftmirr_lcn = sle64_to_cpu(bs->mftmirr_lcn); 211 ntfs_log_debug("MFT LCN = 0x%llx\n", vol->mft_lcn); 212 ntfs_log_debug("MFTMirr LCN = 0x%llx\n", vol->mftmirr_lcn); 213 if (vol->mft_lcn > vol->nr_clusters || 214 vol->mftmirr_lcn > vol->nr_clusters) { 215 ntfs_log_error("$MFT LCN (%lld) or $MFTMirr LCN (%lld) is " 216 "greater than the number of clusters (%lld).\n", 217 (long long)vol->mft_lcn, (long long)vol->mftmirr_lcn, 218 (long long)vol->nr_clusters); 219 return -1; 220 } 221 222 vol->cluster_size = sectors_per_cluster * vol->sector_size; 223 if (vol->cluster_size & (vol->cluster_size - 1)) { 224 ntfs_log_error("cluster_size (%d) is not a power of 2.\n", 225 vol->cluster_size); 226 return -1; 227 } 228 vol->cluster_size_bits = ffs(vol->cluster_size) - 1; 229 /* 230 * Need to get the clusters per mft record and handle it if it is 231 * negative. Then calculate the mft_record_size. A value of 0x80 is 232 * illegal, thus signed char is actually ok! 233 */ 234 c = bs->clusters_per_mft_record; 235 ntfs_log_debug("ClusterSize = 0x%x\n", (unsigned)vol->cluster_size); 236 ntfs_log_debug("ClusterSizeBits = %u\n", vol->cluster_size_bits); 237 ntfs_log_debug("ClustersPerMftRecord = 0x%x\n", c); 238 /* 239 * When clusters_per_mft_record is negative, it means that it is to 240 * be taken to be the negative base 2 logarithm of the mft_record_size 241 * min bytes. Then: 242 * mft_record_size = 2^(-clusters_per_mft_record) bytes. 243 */ 244 if (c < 0) 245 vol->mft_record_size = 1 << -c; 246 else 247 vol->mft_record_size = c << vol->cluster_size_bits; 248 if (vol->mft_record_size & (vol->mft_record_size - 1)) { 249 ntfs_log_error("mft_record_size (%d) is not a power of 2.\n", 250 vol->mft_record_size); 251 return -1; 252 } 253 vol->mft_record_size_bits = ffs(vol->mft_record_size) - 1; 254 ntfs_log_debug("MftRecordSize = 0x%x\n", (unsigned)vol->mft_record_size); 255 ntfs_log_debug("MftRecordSizeBits = %u\n", vol->mft_record_size_bits); 256 /* Same as above for INDX record. */ 257 c = bs->clusters_per_index_record; 258 ntfs_log_debug("ClustersPerINDXRecord = 0x%x\n", c); 259 if (c < 0) 260 vol->indx_record_size = 1 << -c; 261 else 262 vol->indx_record_size = c << vol->cluster_size_bits; 263 vol->indx_record_size_bits = ffs(vol->indx_record_size) - 1; 264 ntfs_log_debug("INDXRecordSize = 0x%x\n", (unsigned)vol->indx_record_size); 265 ntfs_log_debug("INDXRecordSizeBits = %u\n", vol->indx_record_size_bits); 266 /* 267 * Work out the size of the MFT mirror in number of mft records. If the 268 * cluster size is less than or equal to the size taken by four mft 269 * records, the mft mirror stores the first four mft records. If the 270 * cluster size is bigger than the size taken by four mft records, the 271 * mft mirror contains as many mft records as will fit into one 272 * cluster. 273 */ 274 if (vol->cluster_size <= 4 * vol->mft_record_size) 275 vol->mftmirr_size = 4; 276 else 277 vol->mftmirr_size = vol->cluster_size / vol->mft_record_size; 278 return 0; 279 } 280 281