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findfs: fix LUKS and FAT detection routines; do not exit if corrupted

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FAT fs makes us try to seek past volume

function                                             old     new   delta
volume_id_get_buffer                                 301     327     +26
volume_id_probe_luks                                  79      82      +3
get_attr_volume_id                                    73      65      -8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 29/-8)              Total: 21 bytes
This commit is contained in:
Denis Vlasenko 2008-10-12 11:17:49 +00:00
parent cdd1f732bc
commit d5e305944a
3 changed files with 111 additions and 82 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

128
util-linux/volume_id/fat.c
View File

@ -20,8 +20,11 @@
#include "volume_id_internal.h"
#define FAT12_MAX 0xff5
#define FAT16_MAX 0xfff5
/* linux/msdos_fs.h says: */
#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
@ -31,9 +34,9 @@
struct vfat_super_block {
uint8_t boot_jump[3];
uint8_t sysid[8];
uint16_t sector_size;
uint16_t sector_size_bytes;
uint8_t sectors_per_cluster;
uint16_t reserved;
uint16_t reserved_sct;
uint8_t fats;
uint16_t dir_entries;
uint16_t sectors;
@ -84,32 +87,30 @@ struct vfat_dir_entry {
uint32_t size;
} __attribute__((__packed__));
static uint8_t *get_attr_volume_id(struct vfat_dir_entry *dir, unsigned count)
static uint8_t *get_attr_volume_id(struct vfat_dir_entry *dir, int count)
{
unsigned i;
for (i = 0; i < count; i++) {
for (;--count >= 0; dir++) {
/* end marker */
if (dir[i].name[0] == 0x00) {
if (dir->name[0] == 0x00) {
dbg("end of dir");
break;
}
/* empty entry */
if (dir[i].name[0] == FAT_ENTRY_FREE)
if (dir->name[0] == FAT_ENTRY_FREE)
continue;
/* long name */
if ((dir[i].attr & FAT_ATTR_MASK) == FAT_ATTR_LONG_NAME)
if ((dir->attr & FAT_ATTR_MASK) == FAT_ATTR_LONG_NAME)
continue;
if ((dir[i].attr & (FAT_ATTR_VOLUME_ID | FAT_ATTR_DIR)) == FAT_ATTR_VOLUME_ID) {
if ((dir->attr & (FAT_ATTR_VOLUME_ID | FAT_ATTR_DIR)) == FAT_ATTR_VOLUME_ID) {
/* labels do not have file data */
if (dir[i].cluster_high != 0 || dir[i].cluster_low != 0)
if (dir->cluster_high != 0 || dir->cluster_low != 0)
continue;
dbg("found ATTR_VOLUME_ID id in root dir");
return dir[i].name;
return dir->name;
}
dbg("skip dir entry");
@ -118,31 +119,29 @@ static uint8_t *get_attr_volume_id(struct vfat_dir_entry *dir, unsigned count)
return NULL;
}
int volume_id_probe_vfat(struct volume_id *id, uint64_t off)
int volume_id_probe_vfat(struct volume_id *id, uint64_t fat_partition_off)
{
struct vfat_super_block *vs;
struct vfat_dir_entry *dir;
uint16_t sector_size;
uint16_t sector_size_bytes;
uint16_t dir_entries;
uint32_t sect_count;
uint16_t reserved;
uint32_t fat_size;
uint16_t reserved_sct;
uint32_t fat_size_sct;
uint32_t root_cluster;
uint32_t dir_size;
uint32_t dir_size_sct;
uint32_t cluster_count;
uint32_t fat_length;
uint64_t root_start;
uint32_t start_data_sect;
uint16_t root_dir_entries;
uint64_t root_start_off;
uint32_t start_data_sct;
uint8_t *buf;
uint32_t buf_size;
uint8_t *label = NULL;
uint32_t next;
uint32_t next_cluster;
int maxloop;
dbg("probing at offset 0x%llx", (unsigned long long) off);
dbg("probing at offset 0x%llx", (unsigned long long) fat_partition_off);
vs = volume_id_get_buffer(id, off, 0x200);
vs = volume_id_get_buffer(id, fat_partition_off, 0x200);
if (vs == NULL)
return -1;
@ -196,34 +195,34 @@ int volume_id_probe_vfat(struct volume_id *id, uint64_t off)
valid:
/* sector size check */
sector_size = le16_to_cpu(vs->sector_size);
if (sector_size != 0x200 && sector_size != 0x400 &&
sector_size != 0x800 && sector_size != 0x1000)
sector_size_bytes = le16_to_cpu(vs->sector_size_bytes);
if (sector_size_bytes != 0x200 && sector_size_bytes != 0x400 &&
sector_size_bytes != 0x800 && sector_size_bytes != 0x1000)
return -1;
dbg("sector_size 0x%x", sector_size);
dbg("sector_size_bytes 0x%x", sector_size_bytes);
dbg("sectors_per_cluster 0x%x", vs->sectors_per_cluster);
dir_entries = le16_to_cpu(vs->dir_entries);
reserved = le16_to_cpu(vs->reserved);
dbg("reserved 0x%x", reserved);
reserved_sct = le16_to_cpu(vs->reserved_sct);
dbg("reserved_sct 0x%x", reserved_sct);
sect_count = le16_to_cpu(vs->sectors);
if (sect_count == 0)
sect_count = le32_to_cpu(vs->total_sect);
dbg("sect_count 0x%x", sect_count);
fat_length = le16_to_cpu(vs->fat_length);
if (fat_length == 0)
fat_length = le32_to_cpu(vs->type.fat32.fat32_length);
dbg("fat_length 0x%x", fat_length);
fat_size_sct = le16_to_cpu(vs->fat_length);
if (fat_size_sct == 0)
fat_size_sct = le32_to_cpu(vs->type.fat32.fat32_length);
fat_size_sct *= vs->fats;
dbg("fat_size_sct 0x%x", fat_size_sct);
fat_size = fat_length * vs->fats;
dir_size = ((dir_entries * sizeof(struct vfat_dir_entry)) +
(sector_size-1)) / sector_size;
dbg("dir_size 0x%x", dir_size);
dir_entries = le16_to_cpu(vs->dir_entries);
dir_size_sct = ((dir_entries * sizeof(struct vfat_dir_entry)) +
(sector_size_bytes-1)) / sector_size_bytes;
dbg("dir_size_sct 0x%x", dir_size_sct);
cluster_count = sect_count - (reserved + fat_size + dir_size);
cluster_count = sect_count - (reserved_sct + fat_size_sct + dir_size_sct);
cluster_count /= vs->sectors_per_cluster;
dbg("cluster_count 0x%x", cluster_count);
@ -239,21 +238,18 @@ int volume_id_probe_vfat(struct volume_id *id, uint64_t off)
goto fat32;
/* the label may be an attribute in the root directory */
root_start = (reserved + fat_size) * sector_size;
dbg("root dir start 0x%llx", (unsigned long long) root_start);
root_dir_entries = le16_to_cpu(vs->dir_entries);
dbg("expected entries 0x%x", root_dir_entries);
root_start_off = (reserved_sct + fat_size_sct) * sector_size_bytes;
dbg("root dir start 0x%llx", (unsigned long long) root_start_off);
dbg("expected entries 0x%x", dir_entries);
buf_size = root_dir_entries * sizeof(struct vfat_dir_entry);
buf = volume_id_get_buffer(id, off + root_start, buf_size);
buf_size = dir_entries * sizeof(struct vfat_dir_entry);
buf = volume_id_get_buffer(id, fat_partition_off + root_start_off, buf_size);
if (buf == NULL)
goto found;
dir = (struct vfat_dir_entry*) buf;
label = get_attr_volume_id((struct vfat_dir_entry*) buf, dir_entries);
label = get_attr_volume_id(dir, root_dir_entries);
vs = volume_id_get_buffer(id, off, 0x200);
vs = volume_id_get_buffer(id, fat_partition_off, 0x200);
if (vs == NULL)
return -1;
@ -269,26 +265,25 @@ int volume_id_probe_vfat(struct volume_id *id, uint64_t off)
fat32:
/* FAT32 root dir is a cluster chain like any other directory */
buf_size = vs->sectors_per_cluster * sector_size;
buf_size = vs->sectors_per_cluster * sector_size_bytes;
root_cluster = le32_to_cpu(vs->type.fat32.root_cluster);
dbg("root dir cluster %u", root_cluster);
start_data_sect = reserved + fat_size;
start_data_sct = reserved_sct + fat_size_sct;
next = root_cluster;
next_cluster = root_cluster;
maxloop = 100;
while (--maxloop) {
uint32_t next_sect_off;
uint32_t next_off_sct;
uint64_t next_off;
uint64_t fat_entry_off;
int count;
dbg("next cluster %u", next);
next_sect_off = (next - 2) * vs->sectors_per_cluster;
next_off = (start_data_sect + next_sect_off) * sector_size;
dbg("next_cluster 0x%x", (unsigned)next_cluster);
next_off_sct = (next_cluster - 2) * vs->sectors_per_cluster;
next_off = (start_data_sct + next_off_sct) * sector_size_bytes;
dbg("cluster offset 0x%llx", (unsigned long long) next_off);
/* get cluster */
buf = volume_id_get_buffer(id, off + next_off, buf_size);
buf = volume_id_get_buffer(id, fat_partition_off + next_off, buf_size);
if (buf == NULL)
goto found;
@ -301,20 +296,21 @@ int volume_id_probe_vfat(struct volume_id *id, uint64_t off)
break;
/* get FAT entry */
fat_entry_off = (reserved * sector_size) + (next * sizeof(uint32_t));
buf = volume_id_get_buffer(id, off + fat_entry_off, buf_size);
fat_entry_off = (reserved_sct * sector_size_bytes) + (next_cluster * sizeof(uint32_t));
dbg("fat_entry_off 0x%llx", (unsigned long long)fat_entry_off);
buf = volume_id_get_buffer(id, fat_partition_off + fat_entry_off, buf_size);
if (buf == NULL)
goto found;
/* set next cluster */
next = le32_to_cpu(*((uint32_t *) buf) & 0x0fffffff);
if (next == 0)
next_cluster = le32_to_cpu(*(uint32_t*)buf) & 0x0fffffff;
if (next_cluster < 2 || next_cluster > FAT32_MAX)
break;
}
if (maxloop == 0)
dbg("reached maximum follow count of root cluster chain, give up");
vs = volume_id_get_buffer(id, off, 0x200);
vs = volume_id_get_buffer(id, fat_partition_off, 0x200);
if (vs == NULL)
return -1;

38
util-linux/volume_id/luks.c
View File

@ -20,9 +20,8 @@
#include "volume_id_internal.h"
#define SECTOR_SHIFT 9
#define SECTOR_SIZE (1 << SECTOR_SHIFT)
#define LUKS_MAGIC_L 6
#define UUID_STRING_L 40
#define LUKS_CIPHERNAME_L 32
#define LUKS_CIPHERMODE_L 32
#define LUKS_HASHSPEC_L 32
@ -31,9 +30,6 @@
#define LUKS_NUMKEYS 8
static const uint8_t LUKS_MAGIC[] = { 'L','U','K','S', 0xba, 0xbe };
#define LUKS_MAGIC_L 6
#define LUKS_PHDR_SIZE (sizeof(struct luks_phdr)/SECTOR_SIZE+1)
#define UUID_STRING_L 40
struct luks_phdr {
uint8_t magic[LUKS_MAGIC_L];
@ -56,11 +52,39 @@ struct luks_phdr {
} keyblock[LUKS_NUMKEYS];
};
enum {
EXPECTED_SIZE_luks_phdr = 0
+ 1 * LUKS_MAGIC_L
+ 2
+ 1 * LUKS_CIPHERNAME_L
+ 1 * LUKS_CIPHERMODE_L
+ 1 * LUKS_HASHSPEC_L
+ 4
+ 4
+ 1 * LUKS_DIGESTSIZE
+ 1 * LUKS_SALTSIZE
+ 4
+ 1 * UUID_STRING_L
+ LUKS_NUMKEYS * (0
+ 4
+ 4
+ 1 * LUKS_SALTSIZE
+ 4
+ 4
)
};
struct BUG_bad_size_luks_phdr {
char BUG_bad_size_luks_phdr[
sizeof(struct luks_phdr) == EXPECTED_SIZE_luks_phdr ?
1 : -1];
};
int volume_id_probe_luks(struct volume_id *id, uint64_t off)
{
struct luks_phdr *header;
header = volume_id_get_buffer(id, off, LUKS_PHDR_SIZE);
header = volume_id_get_buffer(id, off, sizeof(*header));
if (header == NULL)
return -1;

13
util-linux/volume_id/util.c
View File

@ -190,6 +190,9 @@ set:
}
}
/* Do not use xlseek here. With it, single corrupted filesystem
* may result in attempt to seek past device -> exit.
* It's better to ignore such fs and continue. */
void *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
{
ssize_t buf_len;
@ -204,7 +207,10 @@ void *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
/* check if we need to read */
if ((off + len) > id->sbbuf_len) {
dbg("read sbbuf len:0x%llx", (unsigned long long) (off + len));
xlseek(id->fd, 0, SEEK_SET);
if (lseek(id->fd, 0, SEEK_SET) != 0) {
dbg("seek(0) failed");
return NULL;
}
buf_len = full_read(id->fd, id->sbbuf, off + len);
if (buf_len < 0) {
dbg("read failed (%s)", strerror(errno));
@ -234,7 +240,10 @@ void *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
/* check if we need to read */
if ((off < id->seekbuf_off) || ((off + len) > (id->seekbuf_off + id->seekbuf_len))) {
dbg("read seekbuf off:0x%llx len:0x%zx", (unsigned long long) off, len);
xlseek(id->fd, off, SEEK_SET);
if (lseek(id->fd, off, SEEK_SET) != off) {
dbg("seek(0x%llx) failed", (unsigned long long) off);
return NULL;
}
buf_len = full_read(id->fd, id->seekbuf, len);
if (buf_len < 0) {
dbg("read failed (%s)", strerror(errno));