From 378c18e5f024ac5a8aef4cb40d7c9aa9633d144c Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 16:30:35 +0200 Subject: Adding upstream version 2.38.1. Signed-off-by: Daniel Baumann --- libblkid/src/superblocks/vfat.c | 461 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 461 insertions(+) create mode 100644 libblkid/src/superblocks/vfat.c (limited to 'libblkid/src/superblocks/vfat.c') diff --git a/libblkid/src/superblocks/vfat.c b/libblkid/src/superblocks/vfat.c new file mode 100644 index 0000000..7181348 --- /dev/null +++ b/libblkid/src/superblocks/vfat.c @@ -0,0 +1,461 @@ +/* + * Copyright (C) 1999 by Andries Brouwer + * Copyright (C) 1999, 2000, 2003 by Theodore Ts'o + * Copyright (C) 2001 by Andreas Dilger + * Copyright (C) 2004 Kay Sievers + * Copyright (C) 2008 Karel Zak + * + * This file may be redistributed under the terms of the + * GNU Lesser General Public License. + */ +#include +#include +#include +#include +#include +#include +#include +#include + +#include "pt-mbr.h" +#include "superblocks.h" + +/* Yucky misaligned values */ +struct vfat_super_block { +/* 00*/ unsigned char vs_ignored[3]; +/* 03*/ unsigned char vs_sysid[8]; +/* 0b*/ unsigned char vs_sector_size[2]; +/* 0d*/ uint8_t vs_cluster_size; +/* 0e*/ uint16_t vs_reserved; +/* 10*/ uint8_t vs_fats; +/* 11*/ unsigned char vs_dir_entries[2]; +/* 13*/ unsigned char vs_sectors[2]; +/* 15*/ unsigned char vs_media; +/* 16*/ uint16_t vs_fat_length; +/* 18*/ uint16_t vs_secs_track; +/* 1a*/ uint16_t vs_heads; +/* 1c*/ uint32_t vs_hidden; +/* 20*/ uint32_t vs_total_sect; +/* 24*/ uint32_t vs_fat32_length; +/* 28*/ uint16_t vs_flags; +/* 2a*/ uint8_t vs_version[2]; +/* 2c*/ uint32_t vs_root_cluster; +/* 30*/ uint16_t vs_fsinfo_sector; +/* 32*/ uint16_t vs_backup_boot; +/* 34*/ uint16_t vs_reserved2[6]; +/* 40*/ unsigned char vs_drive_number; +/* 41*/ unsigned char vs_boot_flags; +/* 42*/ unsigned char vs_ext_boot_sign; /* 0x28 - without vs_label/vs_magic; 0x29 - with */ +/* 43*/ unsigned char vs_serno[4]; +/* 47*/ unsigned char vs_label[11]; +/* 52*/ unsigned char vs_magic[8]; +/* 5a*/ unsigned char vs_dummy2[0x1fe - 0x5a]; +/*1fe*/ unsigned char vs_pmagic[2]; +} __attribute__((packed)); + +/* Yucky misaligned values */ +struct msdos_super_block { +/* DOS 2.0 BPB */ +/* 00*/ unsigned char ms_ignored[3]; +/* 03*/ unsigned char ms_sysid[8]; +/* 0b*/ unsigned char ms_sector_size[2]; +/* 0d*/ uint8_t ms_cluster_size; +/* 0e*/ uint16_t ms_reserved; +/* 10*/ uint8_t ms_fats; +/* 11*/ unsigned char ms_dir_entries[2]; +/* 13*/ unsigned char ms_sectors[2]; /* =0 iff V3 or later */ +/* 15*/ unsigned char ms_media; +/* 16*/ uint16_t ms_fat_length; /* Sectors per FAT */ +/* DOS 3.0 BPB */ +/* 18*/ uint16_t ms_secs_track; +/* 1a*/ uint16_t ms_heads; +/* 1c*/ uint32_t ms_hidden; +/* DOS 3.31 BPB */ +/* 20*/ uint32_t ms_total_sect; /* iff ms_sectors == 0 */ +/* DOS 3.4 EBPB */ +/* 24*/ unsigned char ms_drive_number; +/* 25*/ unsigned char ms_boot_flags; +/* 26*/ unsigned char ms_ext_boot_sign; /* 0x28 - DOS 3.4 EBPB; 0x29 - DOS 4.0 EBPB */ +/* 27*/ unsigned char ms_serno[4]; +/* DOS 4.0 EBPB */ +/* 2b*/ unsigned char ms_label[11]; +/* 36*/ unsigned char ms_magic[8]; +/* padding */ +/* 3e*/ unsigned char ms_dummy2[0x1fe - 0x3e]; +/*1fe*/ unsigned char ms_pmagic[2]; +} __attribute__((packed)); + +struct vfat_dir_entry { + uint8_t name[11]; + uint8_t attr; + uint16_t time_creat; + uint16_t date_creat; + uint16_t time_acc; + uint16_t date_acc; + uint16_t cluster_high; + uint16_t time_write; + uint16_t date_write; + uint16_t cluster_low; + uint32_t size; +} __attribute__((packed)); + +struct fat32_fsinfo { + uint8_t signature1[4]; + uint32_t reserved1[120]; + uint8_t signature2[4]; + uint32_t free_clusters; + uint32_t next_cluster; + uint32_t reserved2[4]; +} __attribute__((packed)); + +/* maximum number of clusters */ +#define FAT12_MAX 0xFF4 +#define FAT16_MAX 0xFFF4 +#define FAT32_MAX 0x0FFFFFF6 + +#define FAT_ATTR_VOLUME_ID 0x08 +#define FAT_ATTR_DIR 0x10 +#define FAT_ATTR_LONG_NAME 0x0f +#define FAT_ATTR_MASK 0x3f +#define FAT_ENTRY_FREE 0xe5 + +static const char *no_name = "NO NAME "; + +#define unaligned_le16(x) \ + (((unsigned char *) x)[0] + (((unsigned char *) x)[1] << 8)) + +/* + * Look for LABEL (name) in the FAT root directory. + */ +static unsigned char *search_fat_label(blkid_probe pr, + uint64_t offset, uint32_t entries) +{ + struct vfat_dir_entry *ent, *dir = NULL; + uint32_t i; + + DBG(LOWPROBE, ul_debug("\tlook for label in root-dir " + "(entries: %"PRIu32", offset: %"PRIu64")", entries, offset)); + + if (!blkid_probe_is_tiny(pr)) { + /* large disk, read whole root directory */ + dir = (struct vfat_dir_entry *) + blkid_probe_get_buffer(pr, + offset, + (uint64_t) entries * + sizeof(struct vfat_dir_entry)); + if (!dir) + return NULL; + } + + for (i = 0; i < entries; i++) { + /* + * The root directory could be relatively large (4-16kB). + * Fortunately, the LABEL is usually the first entry in the + * directory. On tiny disks we call read() per entry. + */ + if (!dir) + ent = (struct vfat_dir_entry *) + blkid_probe_get_buffer(pr, + (uint64_t) offset + (i * + sizeof(struct vfat_dir_entry)), + sizeof(struct vfat_dir_entry)); + else + ent = &dir[i]; + + if (!ent || ent->name[0] == 0x00) + break; + + if ((ent->name[0] == FAT_ENTRY_FREE) || + (ent->cluster_high != 0 || ent->cluster_low != 0) || + ((ent->attr & FAT_ATTR_MASK) == FAT_ATTR_LONG_NAME)) + continue; + + if ((ent->attr & (FAT_ATTR_VOLUME_ID | FAT_ATTR_DIR)) == + FAT_ATTR_VOLUME_ID) { + DBG(LOWPROBE, ul_debug("\tfound fs LABEL at entry %d", i)); + if (ent->name[0] == 0x05) + ent->name[0] = 0xE5; + return ent->name; + } + } + return NULL; +} + +static int fat_valid_superblock(blkid_probe pr, + const struct blkid_idmag *mag, + struct msdos_super_block *ms, + struct vfat_super_block *vs, + uint32_t *cluster_count, uint32_t *fat_size) +{ + uint16_t sector_size, dir_entries, reserved; + uint32_t sect_count, __fat_size, dir_size, __cluster_count, fat_length; + uint32_t max_count; + + /* extra check for FATs without magic strings */ + if (mag->len <= 2) { + /* Old floppies have a valid MBR signature */ + if (ms->ms_pmagic[0] != 0x55 || ms->ms_pmagic[1] != 0xAA) + return 0; + + /* + * OS/2 and apparently DFSee will place a FAT12/16-like + * pseudo-superblock in the first 512 bytes of non-FAT + * filesystems --- at least JFS and HPFS, and possibly others. + * So we explicitly check for those filesystems at the + * FAT12/16 filesystem magic field identifier, and if they are + * present, we rule this out as a FAT filesystem, despite the + * FAT-like pseudo-header. + */ + if ((memcmp(ms->ms_magic, "JFS ", 8) == 0) || + (memcmp(ms->ms_magic, "HPFS ", 8) == 0)) { + DBG(LOWPROBE, ul_debug("\tJFS/HPFS detected")); + return 0; + } + } + + /* fat counts(Linux kernel expects at least 1 FAT table) */ + if (!ms->ms_fats) + return 0; + if (!ms->ms_reserved) + return 0; + if (!(0xf8 <= ms->ms_media || ms->ms_media == 0xf0)) + return 0; + if (!is_power_of_2(ms->ms_cluster_size)) + return 0; + + sector_size = unaligned_le16(&ms->ms_sector_size); + if (!is_power_of_2(sector_size) || + sector_size < 512 || sector_size > 4096) + return 0; + + dir_entries = unaligned_le16(&ms->ms_dir_entries); + reserved = le16_to_cpu(ms->ms_reserved); + sect_count = unaligned_le16(&ms->ms_sectors); + + if (sect_count == 0) + sect_count = le32_to_cpu(ms->ms_total_sect); + + fat_length = le16_to_cpu(ms->ms_fat_length); + if (fat_length == 0) + fat_length = le32_to_cpu(vs->vs_fat32_length); + + __fat_size = fat_length * ms->ms_fats; + dir_size = ((dir_entries * sizeof(struct vfat_dir_entry)) + + (sector_size-1)) / sector_size; + + __cluster_count = (sect_count - (reserved + __fat_size + dir_size)) / + ms->ms_cluster_size; + if (!ms->ms_fat_length && vs->vs_fat32_length) + max_count = FAT32_MAX; + else + max_count = __cluster_count > FAT12_MAX ? FAT16_MAX : FAT12_MAX; + + if (__cluster_count > max_count) + return 0; + + if (fat_size) + *fat_size = __fat_size; + if (cluster_count) + *cluster_count = __cluster_count; + + if (blkid_probe_is_bitlocker(pr)) + return 0; + + return 1; /* valid */ +} + +/* function prototype to avoid warnings (duplicate in partitions/dos.c) */ +extern int blkid_probe_is_vfat(blkid_probe pr); + +/* + * This function is used by MBR partition table parser to avoid + * misinterpretation of FAT filesystem. + */ +int blkid_probe_is_vfat(blkid_probe pr) +{ + struct vfat_super_block *vs; + struct msdos_super_block *ms; + const struct blkid_idmag *mag = NULL; + int rc; + + rc = blkid_probe_get_idmag(pr, &vfat_idinfo, NULL, &mag); + if (rc < 0) + return rc; /* error */ + if (rc != BLKID_PROBE_OK || !mag) + return 0; + + ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block); + if (!ms) + return errno ? -errno : 0; + vs = blkid_probe_get_sb(pr, mag, struct vfat_super_block); + if (!vs) + return errno ? -errno : 0; + + return fat_valid_superblock(pr, mag, ms, vs, NULL, NULL); +} + +/* FAT label extraction from the root directory taken from Kay + * Sievers's volume_id library */ +static int probe_vfat(blkid_probe pr, const struct blkid_idmag *mag) +{ + struct vfat_super_block *vs; + struct msdos_super_block *ms; + const unsigned char *vol_label = NULL; + const unsigned char *boot_label = NULL; + unsigned char *vol_serno = NULL, vol_label_buf[11]; + uint16_t sector_size = 0, reserved; + uint32_t cluster_count, fat_size; + const char *version = NULL; + + ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block); + if (!ms) + return errno ? -errno : 1; + + vs = blkid_probe_get_sb(pr, mag, struct vfat_super_block); + if (!vs) + return errno ? -errno : 1; + + if (!fat_valid_superblock(pr, mag, ms, vs, &cluster_count, &fat_size)) + return 1; + + sector_size = unaligned_le16(&ms->ms_sector_size); + reserved = le16_to_cpu(ms->ms_reserved); + + if (ms->ms_fat_length) { + /* the label may be an attribute in the root directory */ + uint32_t root_start = (reserved + fat_size) * sector_size; + uint32_t root_dir_entries = unaligned_le16(&vs->vs_dir_entries); + + vol_label = search_fat_label(pr, root_start, root_dir_entries); + if (vol_label) { + memcpy(vol_label_buf, vol_label, 11); + vol_label = vol_label_buf; + } + + if (ms->ms_ext_boot_sign == 0x29) + boot_label = ms->ms_label; + + if (ms->ms_ext_boot_sign == 0x28 || ms->ms_ext_boot_sign == 0x29) + vol_serno = ms->ms_serno; + + blkid_probe_set_value(pr, "SEC_TYPE", (unsigned char *) "msdos", + sizeof("msdos")); + + if (cluster_count < FAT12_MAX) + version = "FAT12"; + else if (cluster_count < FAT16_MAX) + version = "FAT16"; + + } else if (vs->vs_fat32_length) { + unsigned char *buf; + uint16_t fsinfo_sect; + int maxloop = 100; + + /* Search the FAT32 root dir for the label attribute */ + uint32_t buf_size = vs->vs_cluster_size * sector_size; + uint32_t start_data_sect = reserved + fat_size; + uint32_t entries = ((uint64_t) le32_to_cpu(vs->vs_fat32_length) + * sector_size) / sizeof(uint32_t); + uint32_t next = le32_to_cpu(vs->vs_root_cluster); + + while (next && next < entries && --maxloop) { + uint32_t next_sect_off; + uint64_t next_off, fat_entry_off; + int count; + + next_sect_off = (next - 2) * vs->vs_cluster_size; + next_off = (uint64_t)(start_data_sect + next_sect_off) * + sector_size; + + count = buf_size / sizeof(struct vfat_dir_entry); + + vol_label = search_fat_label(pr, next_off, count); + if (vol_label) { + memcpy(vol_label_buf, vol_label, 11); + vol_label = vol_label_buf; + break; + } + + /* get FAT entry */ + fat_entry_off = ((uint64_t) reserved * sector_size) + + (next * sizeof(uint32_t)); + buf = blkid_probe_get_buffer(pr, fat_entry_off, buf_size); + if (buf == NULL) + break; + + /* set next cluster */ + next = le32_to_cpu(*((uint32_t *) buf)) & 0x0fffffff; + } + + version = "FAT32"; + + if (vs->vs_ext_boot_sign == 0x29) + boot_label = vs->vs_label; + + vol_serno = vs->vs_serno; + + /* + * FAT32 should have a valid signature in the fsinfo block, + * but also allow all bytes set to '\0', because some volumes + * do not set the signature at all. + */ + fsinfo_sect = le16_to_cpu(vs->vs_fsinfo_sector); + if (fsinfo_sect) { + struct fat32_fsinfo *fsinfo; + + buf = blkid_probe_get_buffer(pr, + (uint64_t) fsinfo_sect * sector_size, + sizeof(struct fat32_fsinfo)); + if (buf == NULL) + return errno ? -errno : 1; + + fsinfo = (struct fat32_fsinfo *) buf; + if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0 && + memcmp(fsinfo->signature1, "\x52\x52\x64\x41", 4) != 0 && + memcmp(fsinfo->signature1, "\x00\x00\x00\x00", 4) != 0) + return 1; + if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0 && + memcmp(fsinfo->signature2, "\x00\x00\x00\x00", 4) != 0) + return 1; + } + } + + if (boot_label && memcmp(boot_label, no_name, 11) != 0) + blkid_probe_set_id_label(pr, "LABEL_FATBOOT", boot_label, 11); + + if (vol_label) + blkid_probe_set_label(pr, vol_label, 11); + + /* We can't just print them as %04X, because they are unaligned */ + if (vol_serno) + blkid_probe_sprintf_uuid(pr, vol_serno, 4, "%02X%02X-%02X%02X", + vol_serno[3], vol_serno[2], vol_serno[1], vol_serno[0]); + if (version) + blkid_probe_set_version(pr, version); + + blkid_probe_set_block_size(pr, sector_size); + + return 0; +} + + +const struct blkid_idinfo vfat_idinfo = +{ + .name = "vfat", + .usage = BLKID_USAGE_FILESYSTEM, + .probefunc = probe_vfat, + .magics = + { + { .magic = "MSWIN", .len = 5, .sboff = 0x52 }, + { .magic = "FAT32 ", .len = 8, .sboff = 0x52 }, + { .magic = "MSDOS", .len = 5, .sboff = 0x36 }, + { .magic = "FAT16 ", .len = 8, .sboff = 0x36 }, + { .magic = "FAT12 ", .len = 8, .sboff = 0x36 }, + { .magic = "FAT ", .len = 8, .sboff = 0x36 }, + { .magic = "\353", .len = 1, }, + { .magic = "\351", .len = 1, }, + { .magic = "\125\252", .len = 2, .sboff = 0x1fe }, + { NULL } + } +}; + -- cgit v1.2.3