gpxe/src/arch/i386/image/eltorito.c - platform/external/syslinux - Git at Google

 /*
  * 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,
 };
	/*
	* 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,
	};