1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> 5 * Copyright (c) 2006 Tobias Reifenberger 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/kernel.h> 36 #include <sys/malloc.h> 37 38 #include <geom/geom.h> 39 #include <geom/geom_dbg.h> 40 #include <geom/label/g_label.h> 41 #include <geom/label/g_label_msdosfs.h> 42 43 #define LABEL_NO_NAME "NO NAME " 44 45 static void 46 g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size) 47 { 48 struct g_provider *pp; 49 FAT_BSBPB *pfat_bsbpb; 50 FAT32_BSBPB *pfat32_bsbpb; 51 FAT_DES *pfat_entry; 52 uint8_t *sector0, *sector; 53 size_t copysize; 54 55 g_topology_assert_not(); 56 pp = cp->provider; 57 sector0 = NULL; 58 sector = NULL; 59 bzero(label, size); 60 61 /* Check if the sector size of the medium is a valid FAT sector size. */ 62 switch(pp->sectorsize) { 63 case 512: 64 case 1024: 65 case 2048: 66 case 4096: 67 break; 68 default: 69 G_LABEL_DEBUG(1, "MSDOSFS: %s: sector size %d not compatible.", 70 pp->name, pp->sectorsize); 71 return; 72 } 73 74 /* Load 1st sector with boot sector and boot parameter block. */ 75 sector0 = (uint8_t *)g_read_data(cp, 0, pp->sectorsize, NULL); 76 if (sector0 == NULL) 77 return; 78 79 /* Check for the FAT boot sector signature. */ 80 if (sector0[510] != 0x55 || sector0[511] != 0xaa) { 81 G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT signature found.", 82 pp->name); 83 goto error; 84 } 85 86 /* 87 * Test if this is really a FAT volume and determine the FAT type. 88 */ 89 90 pfat_bsbpb = (FAT_BSBPB *)sector0; 91 pfat32_bsbpb = (FAT32_BSBPB *)sector0; 92 93 if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) { 94 /* 95 * If the BPB_FATSz16 field is not zero and the string "FAT" is 96 * at the right place, this should be a FAT12 or FAT16 volume. 97 */ 98 if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 99 G_LABEL_DEBUG(1, 100 "MSDOSFS: %s: FAT12/16 volume not valid.", 101 pp->name); 102 goto error; 103 } 104 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/FAT16 volume detected.", 105 pp->name); 106 107 /* A volume with no name should have "NO NAME " as label. */ 108 if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME, 109 sizeof(pfat_bsbpb->BS_VolLab)) == 0) { 110 G_LABEL_DEBUG(1, 111 "MSDOSFS: %s: FAT12/16 volume has no name.", 112 pp->name); 113 goto error; 114 } 115 copysize = MIN(size - 1, sizeof(pfat_bsbpb->BS_VolLab)); 116 memcpy(label, pfat_bsbpb->BS_VolLab, copysize); 117 label[copysize] = '\0'; 118 } else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) { 119 uint32_t fat_FirstDataSector, fat_BytesPerSector, offset; 120 121 /* 122 * If the BPB_FATSz32 field is not zero and the string "FAT" is 123 * at the right place, this should be a FAT32 volume. 124 */ 125 if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) { 126 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume not valid.", 127 pp->name); 128 goto error; 129 } 130 G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume detected.", 131 pp->name); 132 133 /* 134 * If the volume label is not "NO NAME " we're done. 135 */ 136 if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME, 137 sizeof(pfat32_bsbpb->BS_VolLab)) != 0) { 138 copysize = MIN(size - 1, 139 sizeof(pfat32_bsbpb->BS_VolLab)); 140 memcpy(label, pfat32_bsbpb->BS_VolLab, copysize); 141 label[copysize] = '\0'; 142 goto endofchecks; 143 } 144 145 /* 146 * If the volume label "NO NAME " is in the boot sector, the 147 * label of FAT32 volumes may be stored as a special entry in 148 * the root directory. 149 */ 150 fat_FirstDataSector = 151 UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) + 152 (pfat32_bsbpb->BPB_NumFATs * 153 UINT32BYTES(pfat32_bsbpb->BPB_FATSz32)); 154 fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec); 155 156 G_LABEL_DEBUG(2, 157 "MSDOSFS: FAT_FirstDataSector=0x%x, FAT_BytesPerSector=%d", 158 fat_FirstDataSector, fat_BytesPerSector); 159 if (fat_BytesPerSector == 0 || 160 fat_BytesPerSector % pp->sectorsize != 0) { 161 G_LABEL_DEBUG(1, "MSDOSFS: %s: corrupted BPB", 162 pp->name); 163 goto error; 164 } 165 166 for (offset = fat_BytesPerSector * fat_FirstDataSector;; 167 offset += fat_BytesPerSector) { 168 sector = (uint8_t *)g_read_data(cp, offset, 169 fat_BytesPerSector, NULL); 170 if (sector == NULL) 171 goto error; 172 173 pfat_entry = (FAT_DES *)sector; 174 do { 175 /* No more entries available. */ 176 if (pfat_entry->DIR_Name[0] == 0) { 177 G_LABEL_DEBUG(1, "MSDOSFS: %s: " 178 "FAT32 volume has no name.", 179 pp->name); 180 goto error; 181 } 182 183 /* Skip empty or long name entries. */ 184 if (pfat_entry->DIR_Name[0] == 0xe5 || 185 (pfat_entry->DIR_Attr & 186 FAT_DES_ATTR_LONG_NAME) == 187 FAT_DES_ATTR_LONG_NAME) { 188 continue; 189 } 190 191 /* 192 * The name of the entry is the volume label if 193 * ATTR_VOLUME_ID is set. 194 */ 195 if (pfat_entry->DIR_Attr & 196 FAT_DES_ATTR_VOLUME_ID) { 197 copysize = MIN(size - 1, 198 sizeof(pfat_entry->DIR_Name)); 199 memcpy(label, pfat_entry->DIR_Name, 200 copysize); 201 label[copysize] = '\0'; 202 goto endofchecks; 203 } 204 } while((uint8_t *)(++pfat_entry) < 205 (uint8_t *)(sector + fat_BytesPerSector)); 206 g_free(sector); 207 } 208 } else { 209 G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT volume detected.", 210 pp->name); 211 goto error; 212 } 213 214 endofchecks: 215 g_label_rtrim(label, size); 216 217 error: 218 if (sector0 != NULL) 219 g_free(sector0); 220 if (sector != NULL) 221 g_free(sector); 222 } 223 224 struct g_label_desc g_label_msdosfs = { 225 .ld_taste = g_label_msdosfs_taste, 226 .ld_dirprefix = "msdosfs/", 227 .ld_enabled = 1 228 }; 229 230 G_LABEL_INIT(msdosfs, g_label_msdosfs, "Create device nodes for MSDOSFS volumes"); 231