static int gpt_check_hdr_crc(const struct disk_info * const diskinfo, struct disk_gpt_header **_gh)
{
struct disk_gpt_header *gh = *_gh;
uint64_t lba_alt;
uint32_t hold_crc32;
hold_crc32 = gh->chksum;
gh->chksum = 0;
if (!valid_crc(hold_crc32, (const uint8_t *)gh, gh->hdr_size)) {
warn("Primary GPT header checksum invalid.");
/* retry with backup */
lba_alt = gh->lba_alt;
free(gh);
if (!(gh = *_gh = disk_read_sectors(diskinfo, lba_alt, 1))) {
error("Couldn't read backup GPT header.");
return -1;
}
hold_crc32 = gh->chksum;
gh->chksum = 0;
if (!valid_crc(hold_crc32, (const uint8_t *)gh, gh->hdr_size)) {
error("Secondary GPT header checksum invalid.");
return -1;
}
}
/* restore old checksum */
gh->chksum = hold_crc32;
return 0;
}
bool hdlc16::valid_frame( void )
{
size_t bitcnt = bitbuf.size();
//this can be extended to work for odd HDLC bitframes later
if( bitcnt % 8 != 0 )
{
return false;
}
if( bitcnt < 32 )
{
return false;
}
if( last_8_bits != HDLC_FRAMER )
{
return false;
}
if( !valid_crc() )
{
return false;
}
return true;
}
static struct disk_gpt_part_entry *try_gpt_list(const struct disk_info *di, const struct disk_gpt_header *gpth, int alt)
{
int pri = gpth->lba_cur < gpth->lba_alt;
const char *desc = alt ? "alternative" : "main";
struct disk_gpt_part_entry *gptl;
char errbuf[64];
uint64_t gpt_lsiz; /* size of GPT partition list in bytes */
uint64_t gpt_lcnt; /* size of GPT partition in sectors */
uint64_t gpt_loff; /* offset to GPT partition list in sectors */
gpt_lsiz = (uint64_t)gpth->part_size * gpth->part_count;
gpt_lcnt = (gpt_lsiz + di->bps - 1) / di->bps;
if (!alt) {
/* prefer header value for partition table if not asking for alternative */
gpt_loff = gpth->lba_table;
} else {
/* try to read alternative, we have to calculate its position */
if (!pri)
gpt_loff = gpth->lba_alt + 1;
else
gpt_loff = gpth->lba_alt - gpt_lcnt;
}
gptl = disk_read_sectors(di, gpt_loff, gpt_lcnt);
if (!gptl) {
sprintf(errbuf, "Unable to read %s GPT partition list.", desc);
try_gpt_we(errbuf, alt);
return NULL;
}
if (!valid_crc(gpth->table_chksum, (const uint8_t *)gptl, gpt_lsiz)) {
sprintf(errbuf, "Invalid checksum of %s GPT partition list.", desc);
try_gpt_we(errbuf, alt);
free(gptl);
return NULL;
}
return gptl;
}
/* pi_begin() - validate and and get proper iterator for a disk described by di */
struct part_iter *pi_begin(const struct disk_info *di, int flags)
{
int gptprot, ret = -1;
struct part_iter *iter;
struct disk_dos_mbr *mbr = NULL;
struct disk_gpt_header *gpth = NULL;
struct disk_gpt_part_entry *gptl = NULL;
/* Preallocate iterator */
if (!(iter = pi_alloc()))
goto bail;
/* Read MBR */
if (!(mbr = disk_read_sectors(di, 0, 1))) {
error("Couldn't read the first disk sector.");
goto bail;
}
/* Check for MBR magic */
if (mbr->sig != disk_mbr_sig_magic) {
warn("No MBR magic, treating disk as raw.");
/* looks like RAW */
ret = pi_ctor(iter, di, flags);
goto bail;
}
/* Check for GPT protective MBR */
gptprot = 0;
for (size_t i = 0; i < 4; i++)
gptprot |= (mbr->table[i].ostype == 0xEE);
if (gptprot && !(flags & PIF_PREFMBR)) {
if (!(gpth = disk_read_sectors(di, 1, 1))) {
error("Couldn't read potential GPT header.");
goto bail;
}
}
if (gpth && gpth->rev.uint32 == 0x00010000 &&
!memcmp(gpth->sig, disk_gpt_sig_magic, sizeof gpth->sig)) {
/* looks like GPT v1.0 */
uint64_t gpt_loff; /* offset to GPT partition list in sectors */
uint64_t gpt_lsiz; /* size of GPT partition list in bytes */
uint64_t gpt_lcnt; /* size of GPT partition in sectors */
#ifdef DEBUG
dprintf("Looks like a GPT v1.0 disk.\n");
disk_gpt_header_dump(gpth);
#endif
/* Verify checksum, fallback to backup, then bail if invalid */
if (gpt_check_hdr_crc(di, &gpth))
goto bail;
gpt_loff = gpth->lba_table;
gpt_lsiz = (uint64_t)gpth->part_size * gpth->part_count;
gpt_lcnt = (gpt_lsiz + di->bps - 1) / di->bps;
/*
* disk_read_sectors allows reading of max 255 sectors, so we use
* it as a sanity check base. EFI doesn't specify max (AFAIK).
* Apart from that, some extensive sanity checks.
*/
if (!(flags & PIF_RELAX) && (
!gpt_loff || !gpt_lsiz || gpt_lcnt > 255u ||
gpth->lba_first_usable > gpth->lba_last_usable ||
!sane(gpt_loff, gpt_lcnt) ||
gpt_loff + gpt_lcnt > gpth->lba_first_usable ||
!sane(gpth->lba_last_usable, gpt_lcnt) ||
gpth->lba_last_usable + gpt_lcnt >= gpth->lba_alt ||
gpth->lba_alt >= di->lbacnt ||
gpth->part_size < sizeof *gptl)) {
error("Invalid GPT header's values.");
goto bail;
}
if (!(gptl = disk_read_sectors(di, gpt_loff, gpt_lcnt))) {
error("Couldn't read GPT partition list.");
goto bail;
}
/* Check array checksum(s). */
if (!valid_crc(gpth->table_chksum, (const uint8_t *)gptl, (unsigned int)gpt_lsiz)) {
warn("Checksum of the main GPT partition list is invalid, trying backup.");
free(gptl);
/* secondary array directly precedes secondary header */
if (!(gptl = disk_read_sectors(di, gpth->lba_alt - gpt_lcnt, gpt_lcnt))) {
error("Couldn't read backup GPT partition list.");
goto bail;
}
if (!valid_crc(gpth->table_chksum, (const uint8_t *)gptl, gpt_lsiz)) {
error("Checksum of the backup GPT partition list is invalid, giving up.");
goto bail;
}
}
/* looks like GPT */
ret = pi_gpt_ctor(iter, di, flags, gpth, gptl);
} else {
/* looks like MBR */
ret = pi_dos_ctor(iter, di, flags, mbr);
}
bail:
if (ret < 0)
free(iter);
free(mbr);
free(gpth);
free(gptl);
return iter;
}