NetBSD/sys/kern/subr_disk_mbr.c

585 lines
15 KiB
C

/* $NetBSD: subr_disk_mbr.c,v 1.4 2003/10/08 04:25:46 lukem 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 partition a
* is set to cover the whole disk.
* Useful for 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 1.4 2003/10/08 04:25:46 lukem Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/disklabel.h>
#include <sys/disk.h>
#include <sys/syslog.h>
#include "opt_mbr.h"
#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 */
uint label_sector; /* where we found the label */
} mbr_args_t;
#define READ_LABEL 1
#define UPDATE_LABEL 2
#define WRITE_LABEL 3
static int validate_label(mbr_args_t *, uint, int);
static int look_netbsd_part(mbr_args_t *, struct mbr_partition *, int, uint);
static int write_netbsd_label(mbr_args_t *, struct mbr_partition *, int, uint);
static int
read_sector(mbr_args_t *a, uint sector)
{
struct buf *bp = a->bp;
int error;
bp->b_blkno = sector;
bp->b_bcount = a->lp->d_secsize;
bp->b_flags = (bp->b_flags & ~(B_WRITE | B_DONE)) | B_READ;
bp->b_cylinder = sector / a->lp->d_secpercyl;
(*a->strat)(bp);
error = biowait(bp);
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 *, struct mbr_partition *, int, uint))
{
struct mbr_partition ptns[MBR_PART_COUNT];
struct mbr_partition *dp;
struct mbr_sector *mbr;
uint ext_base, this_ext, next_ext;
int rval;
int i;
#ifdef COMPAT_386BSD_MBRPART
int dp_386bsd = -1;
#endif
ext_base = 0;
this_ext = 0;
for (;;) {
if (read_sector(a, this_ext)) {
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;
/* Copy data out of buffer so action can use bp */
memcpy(ptns, &mbr->mbr_parts, sizeof ptns);
/* look for NetBSD partition */
next_ext = 0;
dp = ptns;
for (i = 0; i < MBR_PART_COUNT; i++, dp++) {
if (dp->mbrp_type == 0)
continue;
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;
continue;
}
#endif
rval = (*actn)(a, dp, i, this_ext);
if (rval != SCAN_CONTINUE)
return rval;
}
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], dp_386bsd, 0);
#endif
return SCAN_CONTINUE;
}
/*
* 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, strat, lp, osdep)
dev_t dev;
void (*strat)(struct buf *);
struct disklabel *lp;
struct cpu_disklabel *osdep;
{
struct dkbad *bdp;
int rval;
int i;
mbr_args_t a;
memset(&a, 0, sizeof a);
a.lp = lp;
a.strat = strat;
/* 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;
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 = 0x1fffffff;
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 and initialize it */
a.bp = geteblk((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, LABELSECTOR, READ_LABEL);
if (LABELSECTOR != 0 && rval == SCAN_CONTINUE)
rval = validate_label(&a, 0, READ_LABEL);
}
#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 */
if (rval == SCAN_FOUND && osdep && (lp->d_flags & D_BADSECT)) {
struct dkbad *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)) {
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_flags & B_ERROR) && (i += 2) < 10 &&
i < lp->d_nsectors);
}
brelse(a.bp);
if (rval != SCAN_ERROR)
return NULL;
return a.msg;
}
static int
look_netbsd_part(mbr_args_t *a, struct mbr_partition *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 + MBR_LABELSECTOR, READ_LABEL);
/* Put actual location where we found the label into ptn 2 */
if (RAW_PART != 2 && (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;
}
/* 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;
}
static int
validate_label(mbr_args_t *a, uint label_sector, int action)
{
struct disklabel *dlp;
char *dlp_lim;
int error;
/* Next, dig out disk label */
if (read_sector(a, label_sector)) {
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;
if (action != WRITE_LABEL) {
dlp_lim = a->bp->b_data + a->lp->d_secsize - sizeof(*dlp);
for (;; dlp = (void *)((char *)dlp + sizeof(long))) {
if ((char *)dlp > dlp_lim)
return SCAN_CONTINUE;
if (dlp->d_magic != DISKMAGIC
|| dlp->d_magic2 != DISKMAGIC)
continue;
if (dlp->d_npartitions > MAXPARTITIONS
|| dkcksum(dlp) != 0) {
a->msg = "disk label corrupted";
continue;
}
break;
}
}
switch (action) {
case READ_LABEL:
*a->lp = *dlp;
a->label_sector = label_sector;
return SCAN_FOUND;
case UPDATE_LABEL:
case WRITE_LABEL:
*dlp = *a->lp;
a->bp->b_flags &= ~(B_READ|B_DONE);
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;
}
}
/*
* Check new disk label for sensibility
* before setting it.
*/
int
setdisklabel(olp, nlp, openmask, osdep)
struct disklabel *olp, *nlp;
u_long openmask;
struct cpu_disklabel *osdep;
{
int i;
struct partition *opp, *npp;
/* sanity clause */
if (nlp->d_secpercyl == 0 || nlp->d_secsize == 0
|| (nlp->d_secsize % DEV_BSIZE) != 0)
return (EINVAL);
/* special case to allow disklabel to be invalidated */
if (nlp->d_magic == 0xffffffff) {
*olp = *nlp;
return (0);
}
if (nlp->d_magic != DISKMAGIC || nlp->d_magic2 != DISKMAGIC ||
dkcksum(nlp) != 0)
return (EINVAL);
/* XXX missing check if other dos partitions will be overwritten */
while (openmask != 0) {
i = ffs(openmask) - 1;
openmask &= ~(1 << i);
if (i > nlp->d_npartitions)
return (EBUSY);
opp = &olp->d_partitions[i];
npp = &nlp->d_partitions[i];
/*
* Copy internally-set partition information
* if new label doesn't include it. XXX
*/
if (npp->p_fstype == FS_UNUSED && opp->p_fstype != FS_UNUSED) {
*npp = *opp;
continue;
}
if (npp->p_offset != opp->p_offset || npp->p_size < opp->p_size)
return (EBUSY);
}
nlp->d_checksum = 0;
nlp->d_checksum = dkcksum(nlp);
*olp = *nlp;
return (0);
}
/*
* Write disk label back to device after modification.
*/
int
writedisklabel(dev, strat, lp, osdep)
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((int)lp->d_secsize);
a.bp->b_dev = dev;
if (osdep)
/* Write the label to every netbsd mbr partition */
scan_mbr(&a, write_netbsd_label);
/* and overwrite any label at the start of the volume */
validate_label(&a, LABELSECTOR, UPDATE_LABEL);
if (LABELSECTOR != 0)
validate_label(&a, 0, UPDATE_LABEL);
if (a.written == 0 && a.error == 0)
a.error = ESRCH;
brelse(a.bp);
return a.error;
}
static int
write_netbsd_label(mbr_args_t *a, struct mbr_partition *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 + MBR_LABELSECTOR, WRITE_LABEL);
}
/*
* Determine the size of the transfer, and make sure it is
* within the boundaries of the partition. Adjust transfer
* if needed, and signal errors or early completion.
*/
int
bounds_check_with_label(dk, bp, wlabel)
struct disk *dk;
struct buf *bp;
int wlabel;
{
struct disklabel *lp = dk->dk_label;
struct partition *p = lp->d_partitions + DISKPART(bp->b_dev);
int labelsector = lp->d_partitions[2].p_offset + LABELSECTOR;
int sz;
sz = howmany(bp->b_bcount, lp->d_secsize);
if (bp->b_blkno + sz > p->p_size) {
sz = p->p_size - bp->b_blkno;
if (sz == 0) {
/* If exactly at end of disk, return EOF. */
bp->b_resid = bp->b_bcount;
return (0);
}
if (sz < 0) {
/* If past end of disk, return EINVAL. */
bp->b_error = EINVAL;
goto bad;
}
/* Otherwise, truncate request. */
bp->b_bcount = sz << DEV_BSHIFT;
}
/* Overwriting disk label? */
if (bp->b_blkno + p->p_offset <= labelsector &&
bp->b_blkno + p->p_offset + sz > labelsector &&
(bp->b_flags & B_READ) == 0 && !wlabel) {
bp->b_error = EROFS;
goto bad;
}
/* calculate cylinder for disksort to order transfers with */
bp->b_cylinder = (bp->b_blkno + p->p_offset) /
(lp->d_secsize / DEV_BSIZE) / lp->d_secpercyl;
return (1);
bad:
bp->b_flags |= B_ERROR;
return (-1);
}