/*
* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
/**
* @file
*
* El Torito bootable ISO image format
*
*/
#include <stdint.h>
#include <errno.h>
#include <assert.h>
#include <realmode.h>
#include <bootsector.h>
#include <int13.h>
#include <gpxe/uaccess.h>
#include <gpxe/image.h>
#include <gpxe/segment.h>
#include <gpxe/ramdisk.h>
#include <gpxe/init.h>
#define ISO9660_BLKSIZE 2048
#define ELTORITO_VOL_DESC_OFFSET ( 17 * ISO9660_BLKSIZE )
/** An El Torito Boot Record Volume Descriptor */
struct eltorito_vol_desc {
/** Boot record indicator; must be 0 */
uint8_t record_indicator;
/** ISO-9660 identifier; must be "CD001" */
uint8_t iso9660_id[5];
/** Version, must be 1 */
uint8_t version;
/** Boot system indicator; must be "EL TORITO SPECIFICATION" */
uint8_t system_indicator[32];
/** Unused */
uint8_t unused[32];
/** Boot catalog sector */
uint32_t sector;
} __attribute__ (( packed ));
/** An El Torito Boot Catalog Validation Entry */
struct eltorito_validation_entry {
/** Header ID; must be 1 */
uint8_t header_id;
/** Platform ID
*
* 0 = 80x86
* 1 = PowerPC
* 2 = Mac
*/
uint8_t platform_id;
/** Reserved */
uint16_t reserved;
/** ID string */
uint8_t id_string[24];
/** Checksum word */
uint16_t checksum;
/** Signature; must be 0xaa55 */
uint16_t signature;
} __attribute__ (( packed ));
/** A bootable entry in the El Torito Boot Catalog */
struct eltorito_boot_entry {
/** Boot indicator
*
* Must be @c ELTORITO_BOOTABLE for a bootable ISO image
*/
uint8_t indicator;
/** Media type
*
*/
uint8_t media_type;
/** Load segment */
uint16_t load_segment;
/** System type */
uint8_t filesystem;
/** Unused */
uint8_t reserved_a;
/** Sector count */
uint16_t length;
/** Starting sector */
uint32_t start;
/** Unused */
uint8_t reserved_b[20];
} __attribute__ (( packed ));
/** Boot indicator for a bootable ISO image */
#define ELTORITO_BOOTABLE 0x88
/** El Torito media types */
enum eltorito_media_type {
/** No emulation */
ELTORITO_NO_EMULATION = 0,
};
struct image_type eltorito_image_type __image_type ( PROBE_NORMAL );
/**
* Calculate 16-bit word checksum
*
* @v data Data to checksum
* @v len Length (in bytes, must be even)
* @ret sum Checksum
*/
static unsigned int word_checksum ( void *data, size_t len ) {
uint16_t *words;
uint16_t sum = 0;
for ( words = data ; len ; words++, len -= 2 ) {
sum += *words;
}
return sum;
}
/**
* Execute El Torito image
*
* @v image El Torito image
* @ret rc Return status code
*/
static int eltorito_exec ( struct image *image ) {
struct ramdisk ramdisk;
struct int13_drive int13_drive;
unsigned int load_segment = image->priv.ul;
unsigned int load_offset = ( load_segment ? 0 : 0x7c00 );
int rc;
memset ( &ramdisk, 0, sizeof ( ramdisk ) );
init_ramdisk ( &ramdisk, image->data, image->len, ISO9660_BLKSIZE );
memset ( &int13_drive, 0, sizeof ( int13_drive ) );
int13_drive.blockdev = &ramdisk.blockdev;
register_int13_drive ( &int13_drive );
if ( ( rc = call_bootsector ( load_segment, load_offset,
int13_drive.drive ) ) != 0 ) {
DBGC ( image, "ElTorito %p boot failed: %s\n",
image, strerror ( rc ) );
goto err;
}
rc = -ECANCELED; /* -EIMPOSSIBLE */
err:
unregister_int13_drive ( &int13_drive );
return rc;
}
/**
* Read and verify El Torito Boot Record Volume Descriptor
*
* @v image El Torito file
* @ret catalog_offset Offset of Boot Catalog
* @ret rc Return status code
*/
static int eltorito_read_voldesc ( struct image *image,
unsigned long *catalog_offset ) {
static const struct eltorito_vol_desc vol_desc_signature = {
.record_indicator = 0,
.iso9660_id = "CD001",
.version = 1,
.system_indicator = "EL TORITO SPECIFICATION",
};
struct eltorito_vol_desc vol_desc;
/* Sanity check */
if ( image->len < ( ELTORITO_VOL_DESC_OFFSET + ISO9660_BLKSIZE ) ) {
DBGC ( image, "ElTorito %p too short\n", image );
return -ENOEXEC;
}
/* Read and verify Boot Record Volume Descriptor */
copy_from_user ( &vol_desc, image->data, ELTORITO_VOL_DESC_OFFSET,
sizeof ( vol_desc ) );
if ( memcmp ( &vol_desc, &vol_desc_signature,
offsetof ( typeof ( vol_desc ), sector ) ) != 0 ) {
DBGC ( image, "ElTorito %p invalid Boot Record Volume "
"Descriptor\n", image );
return -ENOEXEC;
}
*catalog_offset = ( vol_desc.sector * ISO9660_BLKSIZE );
DBGC ( image, "ElTorito %p boot catalog at offset %#lx\n",
image, *catalog_offset );
return 0;
}
/**
* Read and verify El Torito Boot Catalog
*
* @v image El Torito file
* @v catalog_offset Offset of Boot Catalog
* @ret boot_entry El Torito boot entry
* @ret rc Return status code
*/
static int eltorito_read_catalog ( struct image *image,
unsigned long catalog_offset,
struct eltorito_boot_entry *boot_entry ) {
struct eltorito_validation_entry validation_entry;
/* Sanity check */
if ( image->len < ( catalog_offset + ISO9660_BLKSIZE ) ) {
DBGC ( image, "ElTorito %p bad boot catalog offset %#lx\n",
image, catalog_offset );
return -ENOEXEC;
}
/* Read and verify the Validation Entry of the Boot Catalog */
copy_from_user ( &validation_entry, image->data, catalog_offset,
sizeof ( validation_entry ) );
if ( word_checksum ( &validation_entry,
sizeof ( validation_entry ) ) != 0 ) {
DBGC ( image, "ElTorito %p bad Validation Entry checksum\n",
image );
return -ENOEXEC;
}
/* Read and verify the Initial/Default entry */
copy_from_user ( boot_entry, image->data,
( catalog_offset + sizeof ( validation_entry ) ),
sizeof ( *boot_entry ) );
if ( boot_entry->indicator != ELTORITO_BOOTABLE ) {
DBGC ( image, "ElTorito %p not bootable\n", image );
return -ENOEXEC;
}
if ( boot_entry->media_type != ELTORITO_NO_EMULATION ) {
DBGC ( image, "ElTorito %p cannot support media type %d\n",
image, boot_entry->media_type );
return -ENOTSUP;
}
DBGC ( image, "ElTorito %p media type %d segment %04x\n",
image, boot_entry->media_type, boot_entry->load_segment );
return 0;
}
/**
* Load El Torito virtual disk image into memory
*
* @v image El Torito file
* @v boot_entry El Torito boot entry
* @ret rc Return status code
*/
static int eltorito_load_disk ( struct image *image,
struct eltorito_boot_entry *boot_entry ) {
unsigned long start = ( boot_entry->start * ISO9660_BLKSIZE );
unsigned long length = ( boot_entry->length * ISO9660_BLKSIZE );
unsigned int load_segment;
userptr_t buffer;
int rc;
/* Sanity check */
if ( image->len < ( start + length ) ) {
DBGC ( image, "ElTorito %p virtual disk lies outside image\n",
image );
return -ENOEXEC;
}
DBGC ( image, "ElTorito %p virtual disk at %#lx+%#lx\n",
image, start, length );
/* Calculate load address */
load_segment = boot_entry->load_segment;
buffer = real_to_user ( load_segment, ( load_segment ? 0 : 0x7c00 ) );
/* Verify and prepare segment */
if ( ( rc = prep_segment ( buffer, length, length ) ) != 0 ) {
DBGC ( image, "ElTorito %p could not prepare segment: %s\n",
image, strerror ( rc ) );
return rc;
}
/* Copy image to segment */
memcpy_user ( buffer, 0, image->data, start, length );
return 0;
}
/**
* Load El Torito image into memory
*
* @v image El Torito file
* @ret rc Return status code
*/
static int eltorito_load ( struct image *image ) {
struct eltorito_boot_entry boot_entry;
unsigned long bootcat_offset;
int rc;
/* Read Boot Record Volume Descriptor, if present */
if ( ( rc = eltorito_read_voldesc ( image, &bootcat_offset ) ) != 0 )
return rc;
/* This is an El Torito image, valid or otherwise */
if ( ! image->type )
image->type = &eltorito_image_type;
/* Read Boot Catalog */
if ( ( rc = eltorito_read_catalog ( image, bootcat_offset,
&boot_entry ) ) != 0 )
return rc;
/* Load Virtual Disk image */
if ( ( rc = eltorito_load_disk ( image, &boot_entry ) ) != 0 )
return rc;
/* Record load segment in image private data field */
image->priv.ul = boot_entry.load_segment;
return 0;
}
/** El Torito image type */
struct image_type eltorito_image_type __image_type ( PROBE_NORMAL ) = {
.name = "El Torito",
.load = eltorito_load,
.exec = eltorito_exec,
};
