/* $NetBSD: subr_disk_mbr.c,v 1.57.12.1 2025/02/22 11:47:15 martin Exp $ */
/*
* Copyright (c) 1982, 1986, 1988 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)ufs_disksubr.c 7.16 (Berkeley) 5/4/91
*/
/*
* Code to find a NetBSD label on a disk that contains an i386 style MBR.
* The first NetBSD label found in the 2nd sector of a NetBSD partition
* is used.
* If we don't find a label searching the MBR, we look at the start of the
* disk, if that fails then a label is faked up from the MBR.
*
* If there isn't a disklabel or anything in the MBR then the disc is searched
* for ecma-167/iso9660/udf style partition indicators.
* Useful for media or files that contain single filesystems (etc).
*
* This code will read host endian netbsd labels from little endian MBR.
*
* Based on the i386 disksubr.c
*
* Since the mbr only has 32bit fields for sector addresses, we do the same.
*
* XXX There are potential problems writing labels to disks where there
* is only space for 8 netbsd partitions but this code has been compiled
* with MAXPARTITIONS=16.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_disk_mbr.c,v 1.57.12.1 2025/02/22 11:47:15 martin Exp $");
#ifdef _KERNEL_OPT
#include "opt_mbr.h"
#include "opt_disklabel.h"
#endif /* _KERNEL_OPT */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/bootblock.h>
#include <sys/disklabel.h>
#include <sys/disk.h>
#include <sys/syslog.h>
#include <sys/vnode.h>
#include <sys/fcntl.h>
#include <sys/conf.h>
#include <sys/cdio.h>
#include <sys/dkbad.h>
#include <fs/udf/ecma167-udf.h>
#include <sys/kauth.h>
typedef struct mbr_partition mbr_partition_t;
/*
* We allocate a buffer 3 sectors large, and look in all....
* That means we find labels written by other ports with different offsets.
* LABELSECTOR and LABELOFFSET are only used if the disk doesn't have a label.
*/
#define SCANBLOCKS 3
#define DISKLABEL_SIZE 404
#if LABELSECTOR*DEV_BSIZE + LABELOFFSET > SCANBLOCKS*DEV_BSIZE - DISKLABEL_SIZE
#if _MACHINE != ews4800mips /* XXX: fail silently, ews4800mips LABELSECTOR */
#error Invalid LABELSECTOR or LABELOFFSET
#endif
#endif
#define MBR_LABELSECTOR 1
#define SCAN_CONTINUE 0
#define SCAN_FOUND 1
#define SCAN_ERROR 2
typedef struct mbr_args {
struct disklabel *lp;
void (*strat)(struct buf *);
struct buf *bp;
const char *msg;
int error;
int written; /* number of times we wrote label */
int found_mbr; /* set if disk has a valid mbr */
uint label_sector; /* where we found the label */
int action;
uint32_t secperunit;
#define READ_LABEL 1
#define UPDATE_LABEL 2
#define WRITE_LABEL 3
} mbr_args_t;
static int validate_label(mbr_args_t *, uint);
static int look_netbsd_part(mbr_args_t *, mbr_partition_t *, int, uint);
static int write_netbsd_label(mbr_args_t *, mbr_partition_t *, int, uint);
static int
read_sector(mbr_args_t *a, uint sector, int count)
{
int error;
error = disk_read_sectors(a->strat, a->lp, a->bp, sector, count);
if (error != 0)
a->error = error;
return error;
}
/*
* Scan MBR for partitions, call 'action' routine for each.
*/
static int
scan_mbr(mbr_args_t *a, int (*actn)(mbr_args_t *, mbr_partition_t *, int, uint))
{
mbr_partition_t ptns[MBR_PART_COUNT];
mbr_partition_t *dp;
struct mbr_sector *mbr;
uint ext_base, this_ext, next_ext;
int rval;
int i;
int j;
#ifdef COMPAT_386BSD_MBRPART
int dp_386bsd = -1;
int ap_386bsd = -1;
#endif
ext_base = 0;
this_ext = 0;
for (;;) {
if (read_sector(a, this_ext, 1)) {
a->msg = "dos partition I/O error";
return SCAN_ERROR;
}
/* Note: Magic number is little-endian. */
mbr = (void *)a->bp->b_data;
if (mbr->mbr_magic != htole16(MBR_MAGIC))
return SCAN_CONTINUE;
/*
* If this is a protective MBR, bail now.
*/
if (mbr->mbr_parts[0].mbrp_type == MBR_PTYPE_PMBR
&& mbr->mbr_parts[1].mbrp_type == MBR_PTYPE_UNUSED
&& mbr->mbr_parts[2].mbrp_type == MBR_PTYPE_UNUSED
&& mbr->mbr_parts[3].mbrp_type == MBR_PTYPE_UNUSED)
return SCAN_CONTINUE;
/* Copy data out of buffer so action can use bp */
memcpy(ptns, &mbr->mbr_parts, sizeof ptns);
/* Look for drivers and skip them */
if (ext_base == 0 && ptns[0].mbrp_type == MBR_PTYPE_DM6_DDO) {
/* We've found a DM6 DDO partition type (used by
* the Ontrack Disk Manager drivers).
*
* Ensure that there are no other partitions in the
* MBR and jump to the real partition table (stored
* in the first sector of the second track). */
bool ok = true;
for (i = 1; i < MBR_PART_COUNT; i++)
if (ptns[i].mbrp_type != MBR_PTYPE_UNUSED)
ok = false;
if (ok) {
this_ext = le32toh(a->lp->d_secpercyl /
a->lp->d_ntracks);
continue;
}
}
/* look for NetBSD partition */
next_ext = 0;
dp = ptns;
j = 0;
for (i = 0; i < MBR_PART_COUNT; i++, dp++) {
if (dp->mbrp_type == MBR_PTYPE_UNUSED)
continue;
/* Check end of partition is inside disk limits */
if ((uint64_t)ext_base + le32toh(dp->mbrp_start) +
le32toh(dp->mbrp_size) > a->lp->d_secperunit) {
/* This mbr doesn't look good.... */
a->msg = "mbr partition exceeds disk size";
/* ...but don't report this as an error (yet) */
return SCAN_CONTINUE;
}
a->found_mbr = 1;
if (MBR_IS_EXTENDED(dp->mbrp_type)) {
next_ext = le32toh(dp->mbrp_start);
continue;
}
#ifdef COMPAT_386BSD_MBRPART
if (dp->mbrp_type == MBR_PTYPE_386BSD) {
/*
* If more than one matches, take last,
* as NetBSD install tool does.
*/
if (this_ext == 0) {
dp_386bsd = i;
ap_386bsd = j;
}
continue;
}
#endif
rval = (*actn)(a, dp, j, this_ext);
if (rval != SCAN_CONTINUE)
return rval;
j++;
}
if (next_ext == 0)
break;
if (ext_base == 0) {
ext_base = next_ext;
next_ext = 0;
}
next_ext += ext_base;
if (next_ext <= this_ext)
break;
this_ext = next_ext;
}
#ifdef COMPAT_386BSD_MBRPART
if (this_ext == 0 && dp_386bsd != -1)
return (*actn)(a, &ptns[dp_386bsd], ap_386bsd, 0);
#endif
return SCAN_CONTINUE;
}
static void
scan_iso_vrs_session(mbr_args_t *a, uint32_t first_sector,
int *is_iso9660, int *is_udf)
{
struct vrs_desc *vrsd;
uint64_t vrs;
int sector_size;
int inc;
sector_size = a->lp->d_secsize;
inc = MAX(1, 2048 / sector_size);
/* by definition */
vrs = ((32*1024 + sector_size - 1) / sector_size)
+ first_sector;
/* read first vrs sector */
if (read_sector(a, vrs, 1))
return;
/* skip all CD001 records */
vrsd = a->bp->b_data;
/* printf("vrsd->identifier = `%s`\n", vrsd->identifier); */
while (memcmp(vrsd->identifier, "CD001", 5) == 0) {
/* for sure */
*is_iso9660 = first_sector;
vrs += inc;
if (read_sector(a, vrs, 1))
return;
}
/* search for BEA01 */
vrsd = a->bp->b_data;
/* printf("vrsd->identifier = `%s`\n", vrsd->identifier); */
if (memcmp(vrsd->identifier, "BEA01", 5))
return;
/* read successor */
vrs += inc;
if (read_sector(a, vrs, 1))
return;
/* check for NSR[23] */
vrsd = a->bp->b_data;
/* printf("vrsd->identifier = `%s`\n", vrsd->identifier); */
if (memcmp(vrsd->identifier, "NSR0", 4))
return;
*is_udf = first_sector;
}
/*
* Scan for ISO Volume Recognition Sequences
*/
static int
scan_iso_vrs(mbr_args_t *a)
{
struct mmc_discinfo di;
struct mmc_trackinfo ti;
dev_t dev;
uint64_t sector;
int is_iso9660, is_udf;
int tracknr, sessionnr;
int new_session, error;
is_iso9660 = is_udf = -1;
/* parse all sessions of disc if we're on a SCSI MMC device */
if (a->lp->d_flags & D_SCSI_MMC) {
/* get disc info */
dev = a->bp->b_dev;
error = bdev_ioctl(dev, MMCGETDISCINFO, &di, FKIOCTL, curlwp);
if (error)
goto notmmc;
/* go trough all (data) tracks */
sessionnr = -1;
for (tracknr = di.first_track;
tracknr <= di.first_track_last_session; tracknr++)
{
ti.tracknr = tracknr;
error = bdev_ioctl(dev, MMCGETTRACKINFO, &ti,
FKIOCTL, curlwp);
if (error)
goto notmmc;
new_session = (ti.sessionnr != sessionnr);
sessionnr = ti.sessionnr;
if (new_session) {
if (ti.flags & MMC_TRACKINFO_BLANK)
continue;
if (!(ti.flags & MMC_TRACKINFO_DATA))
continue;
sector = ti.track_start;
scan_iso_vrs_session(a, sector,
&is_iso9660, &is_udf);
}
}
} else {
notmmc:
/* try start of disc */
sector = 0;
scan_iso_vrs_session(a, sector, &is_iso9660, &is_udf);
}
if ((is_iso9660 < 0) && (is_udf < 0))
return SCAN_CONTINUE;
strncpy(a->lp->d_typename, "iso partition", 16);
/* adjust session information for iso9660 partition */
if (is_iso9660 >= 0) {
/* set 'a' partition to iso9660 */
a->lp->d_partitions[0].p_offset = 0;
a->lp->d_partitions[0].p_size = a->lp->d_secperunit;
a->lp->d_partitions[0].p_cdsession = is_iso9660;
a->lp->d_partitions[0].p_fstype = FS_ISO9660;
}
/* UDF doesn't care about the cd session specified here */
return SCAN_FOUND;
}
/*
* Attempt to read a disk label from a device
* using the indicated strategy routine.
* The label must be partly set up before this:
* secpercyl, secsize and anything required for a block i/o read
* operation in the driver's strategy/start routines
* must be filled in before calling us.
*
* If dos partition table requested, attempt to load it and
* find disklabel inside a DOS partition. Also, if bad block
* table needed, attempt to extract it as well. Return buffer
* for use in signalling errors if requested.
*
* Returns null on success and an error string on failure.
*/
const char *
readdisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
struct cpu_disklabel *osdep)
{
int rval;
int i;
mbr_args_t a;
memset(&a, 0, sizeof a);
a.lp = lp;
a.strat = strat;
a.action = READ_LABEL;
/* minimal requirements for architypal disk label */
if (lp->d_secsize == 0)
lp->d_secsize = DEV_BSIZE;
if (lp->d_secperunit == 0)
lp->d_secperunit = 0x1fffffff;
a.secperunit = lp->d_secperunit;
lp->d_npartitions = RAW_PART + 1;
for (i = 0; i < RAW_PART; i++) {
lp->d_partitions[i].p_size = 0;
lp->d_partitions[i].p_offset = 0;
}
if (lp->d_partitions[RAW_PART].p_size == 0)
lp->d_partitions[RAW_PART].p_size = lp->d_secperunit;
lp->d_partitions[RAW_PART].p_offset = 0;
/*
* Set partition 'a' to be the whole disk.
* Cleared if we find an mbr or a netbsd label.
*/
lp->d_partitions[0].p_size = lp->d_partitions[RAW_PART].p_size;
lp->d_partitions[0].p_fstype = FS_BSDFFS;
/*
* Get a buffer big enough to read a disklabel in and initialize it
* make it three sectors long for the validate_label(); see comment at
* start of file.
*/
a.bp = geteblk(SCANBLOCKS * (int)lp->d_secsize);
a.bp->b_dev = dev;
if (osdep)
/*
* Scan mbr searching for netbsd partition and saving
* bios partition information to use if the netbsd one
* is absent.
*/
rval = scan_mbr(&a, look_netbsd_part);
else
rval = SCAN_CONTINUE;
if (rval == SCAN_CONTINUE) {
/* Look at start of disk */
rval = validate_label(&a, 0);
}
if (rval == SCAN_CONTINUE) {
rval = scan_iso_vrs(&a);
}
#if 0
/*
* Save sector where we found the label for the 'don't overwrite
* the label' check in bounds_check_with_label.
*/
if (rval == SCAN_FOUND)
xxx->label_sector = a.label_sector;
#endif
/* Obtain bad sector table if requested and present */
#ifdef __HAVE_DISKLABEL_DKBAD
if (rval == SCAN_FOUND && osdep && (lp->d_flags & D_BADSECT)) {
struct dkbad *bdp, *db;
int blkno;
bdp = &osdep->bad;
i = 0;
rval = SCAN_ERROR;
do {
/* read a bad sector table */
blkno = lp->d_secperunit - lp->d_nsectors + i;
if (lp->d_secsize > DEV_BSIZE)
blkno *= lp->d_secsize / DEV_BSIZE;
else
blkno /= DEV_BSIZE / lp->d_secsize;
/* if successful, validate, otherwise try another */
if (read_sector(&a, blkno, 1)) {
a.msg = "bad sector table I/O error";
continue;
}
db = (struct dkbad *)(a.bp->b_data);
#define DKBAD_MAGIC 0x4321
if (db->bt_mbz != 0 || db->bt_flag != DKBAD_MAGIC) {
a.msg = "bad sector table corrupted";
continue;
}
rval = SCAN_FOUND;
*bdp = *db;
break;
} while (a.bp->b_error && (i += 2) < 10 &&
i < lp->d_nsectors);
}
#endif /* __HAVE_DISKLABEL_DKBAD */
brelse(a.bp, 0);
if (rval == SCAN_ERROR || rval == SCAN_CONTINUE)
return a.msg;
return NULL;
}
static int
look_netbsd_part(mbr_args_t *a, mbr_partition_t *dp, int slot, uint ext_base)
{
struct partition *pp;
int ptn_base = ext_base + le32toh(dp->mbrp_start);
int rval;
if (
#ifdef COMPAT_386BSD_MBRPART
dp->mbrp_type == MBR_PTYPE_386BSD ||
#endif
dp->mbrp_type == MBR_PTYPE_NETBSD) {
rval = validate_label(a, ptn_base);
#if RAW_PART == 3
/* Put actual location where we found the label into ptn 2 */
if (rval == SCAN_FOUND || a->lp->d_partitions[2].p_size == 0) {
a->lp->d_partitions[2].p_size = le32toh(dp->mbrp_size);
a->lp->d_partitions[2].p_offset = ptn_base;
}
#endif
/* If we got a netbsd label look no further */
if (rval == SCAN_FOUND)
return rval;
}
/* Install main partitions into e..h and extended into i+ */
if (ext_base == 0)
slot += 4;
else {
slot = 4 + MBR_PART_COUNT;
pp = &a->lp->d_partitions[slot];
for (; slot < MAXPARTITIONS; pp++, slot++) {
/* This gets called twice - avoid duplicates */
if (pp->p_offset == ptn_base &&
pp->p_size == le32toh(dp->mbrp_size))
break;
if (pp->p_size == 0)
break;
}
}
if (slot < MAXPARTITIONS) {
/* Stop 'a' being the entire disk */
a->lp->d_partitions[0].p_size = 0;
a->lp->d_partitions[0].p_fstype = 0;
/* save partition info */
pp = &a->lp->d_partitions[slot];
pp->p_offset = ptn_base;
pp->p_size = le32toh(dp->mbrp_size);
pp->p_fstype = xlat_mbr_fstype(dp->mbrp_type);
if (slot >= a->lp->d_npartitions)
a->lp->d_npartitions = slot + 1;
}
return SCAN_CONTINUE;
}
__noubsan
static bool
check_label_magic(const struct disklabel *dlp, uint32_t diskmagic)
{
return memcmp(&dlp->d_magic, &diskmagic, sizeof(diskmagic)) == 0 &&
memcmp(&dlp->d_magic2, &diskmagic, sizeof(diskmagic)) == 0;
}
#ifdef DISKLABEL_EI
/*
* - For read, convert a label to the native byte order.
* - For update or write, if a label already exists, keep its byte order.
* Otherwise, write a new label in the native byte order.
*/
#endif
static int
validate_label(mbr_args_t *a, uint label_sector)
{
struct disklabel *dlp;
char *dlp_lim, *dlp_byte;
int error;
#ifdef DISKLABEL_EI
int swapped = 0;
uint16_t npartitions;
#endif
/* Next, dig out disk label */
if (read_sector(a, label_sector, SCANBLOCKS)) {
a->msg = "disk label read failed";
return SCAN_ERROR;
}
/* Locate disk label within block and validate */
/*
* XXX (dsl) This search may be a waste of time, a lot of other i386
* code assumes the label is at offset LABELOFFSET (=0) in the sector.
*
* If we want to support disks from other netbsd ports, then the
* code should also allow for a shorter label nearer the end of
* the disk sector, and (IIRC) labels within 8k of the disk start.
*/
dlp = (void *)a->bp->b_data;
dlp_lim = (char *)a->bp->b_data + a->bp->b_bcount - sizeof *dlp;
for (;; dlp = (void *)((char *)dlp + sizeof(uint32_t))) {
if ((char *)dlp > dlp_lim) {
if (a->action != WRITE_LABEL)
return SCAN_CONTINUE;
/* Write at arch. dependent default location */
dlp_byte = (char *)a->bp->b_data + LABELOFFSET;
if (label_sector)
dlp_byte += MBR_LABELSECTOR * a->lp->d_secsize;
else
dlp_byte += LABELSECTOR * a->lp->d_secsize;
dlp = (void *)dlp_byte;
break;
}
if (!check_label_magic(dlp, DISKMAGIC))
#ifdef DISKLABEL_EI
{
if (!check_label_magic(dlp, bswap32(DISKMAGIC)))
continue;
/*
* The label is in the other byte order. We need to
* checksum before swapping the byte order.
*/
npartitions = bswap16(dlp->d_npartitions);
if (npartitions > MAXPARTITIONS ||
dkcksum_sized(dlp, npartitions) != 0)
goto corrupted;
swapped = 1;
}
#else
continue;
#endif
else if (dlp->d_npartitions > MAXPARTITIONS ||
dkcksum(dlp) != 0) {
#ifdef DISKLABEL_EI
corrupted:
#endif
a->msg = "disk label corrupted";
continue;
}
break;
}
switch (a->action) {
case READ_LABEL:
#ifdef DISKLABEL_EI
if (swapped)
disklabel_swap(a->lp, dlp);
else
*a->lp = *dlp;
#else
*a->lp = *dlp;
#endif
if ((a->msg = convertdisklabel(a->lp, a->strat, a->bp,
a->secperunit)) != NULL)
return SCAN_ERROR;
a->label_sector = label_sector;
return SCAN_FOUND;
case UPDATE_LABEL:
case WRITE_LABEL:
#ifdef DISKLABEL_EI
/* DO NOT swap a->lp itself for later references. */
if (swapped)
disklabel_swap(dlp, a->lp);
else
*dlp = *a->lp;
#else
*dlp = *a->lp;
#endif
a->bp->b_oflags &= ~BO_DONE;
a->bp->b_flags &= ~B_READ;
a->bp->b_flags |= B_WRITE;
(*a->strat)(a->bp);
error = biowait(a->bp);
if (error != 0) {
a->error = error;
a->msg = "disk label write failed";
return SCAN_ERROR;
}
a->written++;
/* Write label to all mbr partitions */
return SCAN_CONTINUE;
default:
return SCAN_ERROR;
}
}
/*
* Write disk label back to device after modification.
*/
int
writedisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
struct cpu_disklabel *osdep)
{
mbr_args_t a;
memset(&a, 0, sizeof a);
a.lp = lp;
a.strat = strat;
/* get a buffer and initialize it */
a.bp = geteblk(SCANBLOCKS * (int)lp->d_secsize);
a.bp->b_dev = dev;
/* osdep => we expect an mbr with label in netbsd ptn */
a.action = osdep != NULL ? WRITE_LABEL : UPDATE_LABEL;
/* Write/update the label to every netbsd mbr partition */
scan_mbr(&a, write_netbsd_label);
/* Old write the label at the start of the volume on disks that
* don't have a valid mbr (always update an existing one) */
a.action = a.found_mbr ? UPDATE_LABEL : WRITE_LABEL;
validate_label(&a, 0);
if (a.written == 0 && a.error == 0)
a.error = ESRCH;
brelse(a.bp, 0);
return a.error;
}
static int
write_netbsd_label(mbr_args_t *a, mbr_partition_t *dp, int slot, uint ext_base)
{
int ptn_base = ext_base + le32toh(dp->mbrp_start);
if (dp->mbrp_type != MBR_PTYPE_NETBSD)
return SCAN_CONTINUE;
return validate_label(a, ptn_base);
}