uint16_t
dkcksum_target(struct disklabel *lp)
{
uint16_t npartitions;
if (lp->d_magic == DISKMAGIC)
npartitions = lp->d_npartitions;
else if (bswap32(lp->d_magic) == DISKMAGIC)
npartitions = bswap16(lp->d_npartitions);
else
npartitions = 0;
if (npartitions > maxpartitions)
npartitions = 0;
return dkcksum_sized(lp, npartitions);
}
/*
* Compute checksum for disk label.
*/
u_int
dkcksum(struct disklabel *lp)
{
return dkcksum_sized(lp, lp->d_npartitions);
}
static int
validate_label(mbr_args_t *a, daddr_t label_sector, size_t label_offset)
{
struct disklabel *lp;
void *lp_lim;
int error, swapped;
uint16_t npartitions;
error = dkwedge_read(a->pdk, a->vp, label_sector, a->buf, DEV_BSIZE);
if (error) {
aprint_error("%s: unable to read BSD disklabel @ %" PRId64
", error = %d\n", a->pdk->dk_name, label_sector, error);
a->error = error;
return (SCAN_ERROR);
}
/*
* We ignore label_offset; this seems to have not been used
* consistently in the old code, requiring us to do the search
* in the sector.
*/
lp = a->buf;
lp_lim = (char *)a->buf + DEV_BSIZE - DISKLABEL_MINSIZE;
for (;; lp = (void *)((char *)lp + sizeof(uint32_t))) {
if ((char *)lp > (char *)lp_lim)
return (SCAN_CONTINUE);
label_offset = (size_t)((char *)lp - (char *)a->buf);
if (lp->d_magic != DISKMAGIC || lp->d_magic2 != DISKMAGIC) {
if (lp->d_magic != bswap32(DISKMAGIC) ||
lp->d_magic2 != bswap32(DISKMAGIC))
continue;
/* Label is in the other byte order. */
swapped = 1;
} else
swapped = 0;
npartitions = (swapped) ? bswap16(lp->d_npartitions)
: lp->d_npartitions;
/* Validate label length. */
if ((char *)lp + DISKLABEL_SIZE(npartitions) >
(char *)a->buf + DEV_BSIZE) {
aprint_error("%s: BSD disklabel @ "
"%" PRId64 "+%zd has bogus partition count (%u)\n",
a->pdk->dk_name, label_sector, label_offset,
npartitions);
continue;
}
/*
* We have validated the partition count. Checksum it.
* Note that we purposefully checksum before swapping
* the byte order.
*/
if (dkcksum_sized(lp, npartitions) != 0) {
aprint_error("%s: BSD disklabel @ %" PRId64
"+%zd has bad checksum\n", a->pdk->dk_name,
label_sector, label_offset);
continue;
}
/* Put the disklabel in the right order. */
if (swapped)
swap_disklabel(lp);
addwedges(a, lp);
return (SCAN_FOUND);
}
}
