freebsd-skq/sys/geom/part/g_part_mbr.c
Marcel Moolenaar 028de8786a Follow-up improvements to the handling of false positives: If the
partition table is empty, check to see if we have something that
looks sufficiently like a BPB. On non-i386 machines, the boot
sector typically doesn't contain boot code; the end of the boot
sector is all zeroes. This is also where the partition table is
for MBRs.
We only check the sector size and cluster size, as that seems to
be the most reliable across implementations, BPB versions and
platforms.
2008-02-29 22:41:36 +00:00

438 lines
12 KiB
C

/*-
* Copyright (c) 2007 Marcel Moolenaar
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/bio.h>
#include <sys/diskmbr.h>
#include <sys/endian.h>
#include <sys/kernel.h>
#include <sys/kobj.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/queue.h>
#include <sys/sbuf.h>
#include <sys/systm.h>
#include <geom/geom.h>
#include <geom/part/g_part.h>
#include "g_part_if.h"
#define MBRSIZE 512
struct g_part_mbr_table {
struct g_part_table base;
u_char mbr[MBRSIZE];
};
struct g_part_mbr_entry {
struct g_part_entry base;
struct dos_partition ent;
};
static int g_part_mbr_add(struct g_part_table *, struct g_part_entry *,
struct g_part_parms *);
static int g_part_mbr_create(struct g_part_table *, struct g_part_parms *);
static int g_part_mbr_destroy(struct g_part_table *, struct g_part_parms *);
static int g_part_mbr_dumpto(struct g_part_table *, struct g_part_entry *);
static int g_part_mbr_modify(struct g_part_table *, struct g_part_entry *,
struct g_part_parms *);
static char *g_part_mbr_name(struct g_part_table *, struct g_part_entry *,
char *, size_t);
static int g_part_mbr_probe(struct g_part_table *, struct g_consumer *);
static int g_part_mbr_read(struct g_part_table *, struct g_consumer *);
static const char *g_part_mbr_type(struct g_part_table *, struct g_part_entry *,
char *, size_t);
static int g_part_mbr_write(struct g_part_table *, struct g_consumer *);
static kobj_method_t g_part_mbr_methods[] = {
KOBJMETHOD(g_part_add, g_part_mbr_add),
KOBJMETHOD(g_part_create, g_part_mbr_create),
KOBJMETHOD(g_part_destroy, g_part_mbr_destroy),
KOBJMETHOD(g_part_dumpto, g_part_mbr_dumpto),
KOBJMETHOD(g_part_modify, g_part_mbr_modify),
KOBJMETHOD(g_part_name, g_part_mbr_name),
KOBJMETHOD(g_part_probe, g_part_mbr_probe),
KOBJMETHOD(g_part_read, g_part_mbr_read),
KOBJMETHOD(g_part_type, g_part_mbr_type),
KOBJMETHOD(g_part_write, g_part_mbr_write),
{ 0, 0 }
};
static struct g_part_scheme g_part_mbr_scheme = {
"MBR",
g_part_mbr_methods,
sizeof(struct g_part_mbr_table),
.gps_entrysz = sizeof(struct g_part_mbr_entry),
.gps_minent = NDOSPART,
.gps_maxent = NDOSPART,
};
G_PART_SCHEME_DECLARE(g_part_mbr_scheme);
static int
mbr_parse_type(const char *type, u_char *dp_typ)
{
const char *alias;
char *endp;
long lt;
if (type[0] == '!') {
lt = strtol(type + 1, &endp, 0);
if (type[1] == '\0' || *endp != '\0' || lt <= 0 || lt >= 256)
return (EINVAL);
*dp_typ = (u_char)lt;
return (0);
}
alias = g_part_alias_name(G_PART_ALIAS_FREEBSD);
if (!strcasecmp(type, alias)) {
*dp_typ = DOSPTYP_386BSD;
return (0);
}
return (EINVAL);
}
static int
mbr_probe_bpb(u_char *bpb)
{
uint16_t secsz;
uint8_t clstsz;
#define PO2(x) ((x & (x - 1)) == 0)
secsz = le16dec(bpb);
if (secsz < 512 || secsz > 4096 || !PO2(secsz))
return (0);
clstsz = bpb[2];
if (clstsz < 1 || clstsz > 128 || !PO2(clstsz))
return (0);
#undef PO2
return (1);
}
static void
mbr_set_chs(struct g_part_table *table, uint32_t lba, u_char *cylp, u_char *hdp,
u_char *secp)
{
uint32_t cyl, hd, sec;
sec = lba % table->gpt_sectors + 1;
lba /= table->gpt_sectors;
hd = lba % table->gpt_heads;
lba /= table->gpt_heads;
cyl = lba;
if (cyl > 1023)
sec = hd = cyl = ~0;
*cylp = cyl & 0xff;
*hdp = hd & 0xff;
*secp = (sec & 0x3f) | ((cyl >> 2) & 0xc0);
}
static int
g_part_mbr_add(struct g_part_table *basetable, struct g_part_entry *baseentry,
struct g_part_parms *gpp)
{
struct g_part_mbr_entry *entry;
struct g_part_mbr_table *table;
uint32_t start, size, sectors;
if (gpp->gpp_parms & G_PART_PARM_LABEL)
return (EINVAL);
sectors = basetable->gpt_sectors;
entry = (struct g_part_mbr_entry *)baseentry;
table = (struct g_part_mbr_table *)basetable;
start = gpp->gpp_start;
size = gpp->gpp_size;
if (size < sectors)
return (EINVAL);
if (start % sectors) {
size = size - sectors + (start % sectors);
start = start - (start % sectors) + sectors;
}
if (size % sectors)
size = size - (size % sectors);
if (size < sectors)
return (EINVAL);
if (baseentry->gpe_deleted)
bzero(&entry->ent, sizeof(entry->ent));
KASSERT(baseentry->gpe_start <= start, (__func__));
KASSERT(baseentry->gpe_end >= start + size - 1, (__func__));
baseentry->gpe_start = start;
baseentry->gpe_end = start + size - 1;
entry->ent.dp_start = start;
entry->ent.dp_size = size;
mbr_set_chs(basetable, baseentry->gpe_start, &entry->ent.dp_scyl,
&entry->ent.dp_shd, &entry->ent.dp_ssect);
mbr_set_chs(basetable, baseentry->gpe_end, &entry->ent.dp_ecyl,
&entry->ent.dp_ehd, &entry->ent.dp_esect);
return (mbr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
}
static int
g_part_mbr_create(struct g_part_table *basetable, struct g_part_parms *gpp)
{
struct g_consumer *cp;
struct g_provider *pp;
struct g_part_mbr_table *table;
uint64_t msize;
pp = gpp->gpp_provider;
cp = LIST_FIRST(&pp->consumers);
if (pp->sectorsize < MBRSIZE)
return (ENOSPC);
msize = pp->mediasize / pp->sectorsize;
basetable->gpt_first = basetable->gpt_sectors;
basetable->gpt_last = msize - (msize % basetable->gpt_sectors) - 1;
table = (struct g_part_mbr_table *)basetable;
le16enc(table->mbr + DOSMAGICOFFSET, DOSMAGIC);
return (0);
}
static int
g_part_mbr_destroy(struct g_part_table *basetable, struct g_part_parms *gpp)
{
/* Wipe the first sector to clear the partitioning. */
basetable->gpt_smhead |= 1;
return (0);
}
static int
g_part_mbr_dumpto(struct g_part_table *table, struct g_part_entry *baseentry)
{
struct g_part_mbr_entry *entry;
/* Allow dumping to a FreeBSD partition only. */
entry = (struct g_part_mbr_entry *)baseentry;
return ((entry->ent.dp_typ == DOSPTYP_386BSD) ? 1 : 0);
}
static int
g_part_mbr_modify(struct g_part_table *basetable,
struct g_part_entry *baseentry, struct g_part_parms *gpp)
{
struct g_part_mbr_entry *entry;
if (gpp->gpp_parms & G_PART_PARM_LABEL)
return (EINVAL);
entry = (struct g_part_mbr_entry *)baseentry;
if (gpp->gpp_parms & G_PART_PARM_TYPE)
return (mbr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
return (0);
}
static char *
g_part_mbr_name(struct g_part_table *table, struct g_part_entry *baseentry,
char *buf, size_t bufsz)
{
snprintf(buf, bufsz, "s%d", baseentry->gpe_index);
return (buf);
}
static int
g_part_mbr_probe(struct g_part_table *table, struct g_consumer *cp)
{
struct g_provider *pp;
u_char *buf, *p;
int error, index, res, sum;
uint16_t magic;
pp = cp->provider;
/* Sanity-check the provider. */
if (pp->sectorsize < MBRSIZE || pp->mediasize < pp->sectorsize)
return (ENOSPC);
if (pp->sectorsize > 4096)
return (ENXIO);
/* Check that there's a MBR. */
buf = g_read_data(cp, 0L, pp->sectorsize, &error);
if (buf == NULL)
return (error);
/* We goto out on mismatch. */
res = ENXIO;
magic = le16dec(buf + DOSMAGICOFFSET);
if (magic != DOSMAGIC)
goto out;
for (index = 0; index < NDOSPART; index++) {
p = buf + DOSPARTOFF + index * DOSPARTSIZE;
if (p[0] != 0 && p[0] != 0x80)
goto out;
}
/*
* If the partition table does not consist of all zeroes,
* assume we have a MBR. If it's all zeroes, we could have
* a boot sector. For example, a boot sector that doesn't
* have boot code -- common on non-i386 hardware. In that
* case we check if we have a possible BPB. If so, then we
* assume we have a boot sector instead.
*/
sum = 0;
for (index = 0; index < NDOSPART * DOSPARTSIZE; index++)
sum += buf[DOSPARTOFF + index];
if (sum != 0 || !mbr_probe_bpb(buf + 0x0b))
res = G_PART_PROBE_PRI_NORM;
out:
g_free(buf);
return (res);
}
static int
g_part_mbr_read(struct g_part_table *basetable, struct g_consumer *cp)
{
struct dos_partition ent;
struct g_provider *pp;
struct g_part_mbr_table *table;
struct g_part_mbr_entry *entry;
u_char *buf, *p;
off_t chs, msize;
u_int sectors, heads;
int error, index;
pp = cp->provider;
table = (struct g_part_mbr_table *)basetable;
msize = pp->mediasize / pp->sectorsize;
buf = g_read_data(cp, 0L, pp->sectorsize, &error);
if (buf == NULL)
return (error);
bcopy(buf, table->mbr, sizeof(table->mbr));
for (index = NDOSPART - 1; index >= 0; index--) {
p = buf + DOSPARTOFF + index * DOSPARTSIZE;
ent.dp_flag = p[0];
ent.dp_shd = p[1];
ent.dp_ssect = p[2];
ent.dp_scyl = p[3];
ent.dp_typ = p[4];
ent.dp_ehd = p[5];
ent.dp_esect = p[6];
ent.dp_ecyl = p[7];
ent.dp_start = le32dec(p + 8);
ent.dp_size = le32dec(p + 12);
if (ent.dp_typ == 0 || ent.dp_typ == DOSPTYP_PMBR)
continue;
if (ent.dp_start == 0 || ent.dp_size == 0)
continue;
sectors = ent.dp_esect & 0x3f;
if (sectors > basetable->gpt_sectors &&
!basetable->gpt_fixgeom) {
g_part_geometry_heads(msize, sectors, &chs, &heads);
if (chs != 0) {
basetable->gpt_sectors = sectors;
basetable->gpt_heads = heads;
}
}
if ((ent.dp_start % basetable->gpt_sectors) != 0)
printf("GEOM: %s: partition %d does not start on a "
"track boundary.\n", pp->name, index + 1);
if ((ent.dp_size % basetable->gpt_sectors) != 0)
printf("GEOM: %s: partition %d does not end on a "
"track boundary.\n", pp->name, index + 1);
entry = (struct g_part_mbr_entry *)g_part_new_entry(basetable,
index + 1, ent.dp_start, ent.dp_start + ent.dp_size - 1);
entry->ent = ent;
}
basetable->gpt_entries = NDOSPART;
basetable->gpt_first = basetable->gpt_sectors;
basetable->gpt_last = msize - (msize % basetable->gpt_sectors) - 1;
return (0);
}
static const char *
g_part_mbr_type(struct g_part_table *basetable, struct g_part_entry *baseentry,
char *buf, size_t bufsz)
{
struct g_part_mbr_entry *entry;
int type;
entry = (struct g_part_mbr_entry *)baseentry;
type = entry->ent.dp_typ;
if (type == DOSPTYP_386BSD)
return (g_part_alias_name(G_PART_ALIAS_FREEBSD));
snprintf(buf, bufsz, "!%d", type);
return (buf);
}
static int
g_part_mbr_write(struct g_part_table *basetable, struct g_consumer *cp)
{
struct g_part_entry *baseentry;
struct g_part_mbr_entry *entry;
struct g_part_mbr_table *table;
u_char *p;
int error, index;
table = (struct g_part_mbr_table *)basetable;
baseentry = LIST_FIRST(&basetable->gpt_entry);
for (index = 1; index <= basetable->gpt_entries; index++) {
p = table->mbr + DOSPARTOFF + (index - 1) * DOSPARTSIZE;
entry = (baseentry != NULL && index == baseentry->gpe_index)
? (struct g_part_mbr_entry *)baseentry : NULL;
if (entry != NULL && !baseentry->gpe_deleted) {
p[0] = entry->ent.dp_flag;
p[1] = entry->ent.dp_shd;
p[2] = entry->ent.dp_ssect;
p[3] = entry->ent.dp_scyl;
p[4] = entry->ent.dp_typ;
p[5] = entry->ent.dp_ehd;
p[6] = entry->ent.dp_esect;
p[7] = entry->ent.dp_ecyl;
le32enc(p + 8, entry->ent.dp_start);
le32enc(p + 12, entry->ent.dp_size);
} else
bzero(p, DOSPARTSIZE);
if (entry != NULL)
baseentry = LIST_NEXT(baseentry, gpe_entry);
}
error = g_write_data(cp, 0, table->mbr, cp->provider->sectorsize);
return (error);
}