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9a70496d3c12bd414e838ac705f7ecfd2021a596
libisofs/libisofs/eltorito.c
Vreixo Formoso 9a70496d3c Fix serious bugs related with El-Torito.
2008-02-09 19:05:24 +01:00

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/*
* Copyright (c) 2007 Vreixo Formoso
*
* This file is part of the libisofs project; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation. See COPYING file for details.
*/
#include "eltorito.h"
#include "stream.h"
#include "fsource.h"
#include "filesrc.h"
#include "image.h"
#include "messages.h"
#include "writer.h"
#include <stdlib.h>
#include <string.h>
/**
* This table should be written with accuracy values at offset
* 8 of boot image, when used ISOLINUX boot loader
*/
struct boot_info_table {
uint8_t bi_pvd BP(1, 4); /* LBA of primary volume descriptor */
uint8_t bi_file BP(5, 8); /* LBA of boot file */
uint8_t bi_length BP(9, 12); /* Length of boot file */
uint8_t bi_csum BP(13, 16); /* Checksum of boot file */
uint8_t bi_reserved BP(17, 56); /* Reserved */
};
/**
* Structure for each one of the four entries in a partition table on a
* hard disk image.
*/
struct partition_desc {
uint8_t boot_ind;
uint8_t begin_chs[3];
uint8_t type;
uint8_t end_chs[3];
uint8_t start[4];
uint8_t size[4];
};
/**
* Structures for a Master Boot Record of a hard disk image.
*/
struct hard_disc_mbr {
uint8_t code_area[440];
uint8_t opt_disk_sg[4];
uint8_t pad[2];
struct partition_desc partition[4];
uint8_t sign1;
uint8_t sign2;
};
/**
* Sets the load segment for the initial boot image. This is only for
* no emulation boot images, and is a NOP for other image types.
*/
void el_torito_set_load_seg(ElToritoBootImage *bootimg, short segment)
{
if (bootimg->type != ELTORITO_NO_EMUL)
return;
bootimg->load_seg = segment;
}
/**
* Sets the number of sectors (512b) to be load at load segment during
* the initial boot procedure. This is only for no emulation boot images,
* and is a NOP for other image types.
*/
void el_torito_set_load_size(ElToritoBootImage *bootimg, short sectors)
{
if (bootimg->type != ELTORITO_NO_EMUL)
return;
bootimg->load_size = sectors;
}
/**
* Marks the specified boot image as not bootable
*/
void el_torito_set_no_bootable(ElToritoBootImage *bootimg)
{
bootimg->bootable = 0;
}
/**
* Specifies that this image needs to be patched. This involves the writting
* of a 56 bytes boot information table at offset 8 of the boot image file.
* The original boot image file won't be modified.
* This is needed for isolinux boot images.
*/
void el_torito_patch_isolinux_image(ElToritoBootImage *bootimg)
{
bootimg->isolinux = 1;
}
static
int iso_tree_add_boot_node(IsoDir *parent, const char *name, IsoBoot **boot)
{
IsoBoot *node;
IsoNode **pos;
time_t now;
if (parent == NULL || name == NULL || boot == NULL) {
return ISO_NULL_POINTER;
}
if (boot) {
*boot = NULL;
}
/* check if the name is valid */
if (!iso_node_is_valid_name(name)) {
return ISO_WRONG_ARG_VALUE;
}
/* find place where to insert */
pos = &(parent->children);
while (*pos != NULL && strcmp((*pos)->name, name) < 0) {
pos = &((*pos)->next);
}
if (*pos != NULL && !strcmp((*pos)->name, name)) {
/* a node with same name already exists */
return ISO_NODE_NAME_NOT_UNIQUE;
}
node = calloc(1, sizeof(IsoBoot));
if (node == NULL) {
return ISO_OUT_OF_MEM;
}
node->node.refcount = 1;
node->node.type = LIBISO_BOOT;
node->node.name = strdup(name);
if (node->node.name == NULL) {
free(node);
return ISO_OUT_OF_MEM;
}
/* atributes from parent */
node->node.mode = S_IFREG | (parent->node.mode & 0444);
node->node.uid = parent->node.uid;
node->node.gid = parent->node.gid;
node->node.hidden = parent->node.hidden;
/* current time */
now = time(NULL);
node->node.atime = now;
node->node.ctime = now;
node->node.mtime = now;
/* add to dir */
node->node.parent = parent;
node->node.next = *pos;
*pos = (IsoNode*)node;
if (boot) {
*boot = node;
}
return ++parent->nchildren;
}
static
int create_image(IsoImage *image, const char *image_path,
enum eltorito_boot_media_type type,
struct el_torito_boot_image **bootimg)
{
int ret;
struct el_torito_boot_image *boot;
int boot_media_type = 0;
int load_sectors = 0; /* number of sector to load */
unsigned char partition_type = 0;
IsoNode *imgfile;
IsoStream *stream;
ret = iso_tree_path_to_node(image, image_path, &imgfile);
if (ret < 0) {
return ret;
}
if (ret == 0) {
return ISO_NODE_DOESNT_EXIST;
}
if (imgfile->type != LIBISO_FILE) {
return ISO_BOOT_IMAGE_NOT_VALID;
}
stream = ((IsoFile*)imgfile)->stream;
/* we need to read the image at least two times */
if (!iso_stream_is_repeatable(stream)) {
return ISO_BOOT_IMAGE_NOT_VALID;
}
switch (type) {
case ELTORITO_FLOPPY_EMUL:
switch (iso_stream_get_size(stream)) {
case 1200 * 1024:
boot_media_type = 1; /* 1.2 meg diskette */
break;
case 1440 * 1024:
boot_media_type = 2; /* 1.44 meg diskette */
break;
case 2880 * 1024:
boot_media_type = 3; /* 2.88 meg diskette */
break;
default:
iso_msg_submit(image->id, ISO_BOOT_IMAGE_NOT_VALID, 0,
"Invalid image size %d Kb. Must be one of 1.2, 1.44"
"or 2.88 Mb", iso_stream_get_size(stream) / 1024);
return ISO_BOOT_IMAGE_NOT_VALID;
break;
}
/* it seems that for floppy emulation we need to load
* a single sector (512b) */
load_sectors = 1;
break;
case ELTORITO_HARD_DISC_EMUL:
{
size_t i;
struct hard_disc_mbr mbr;
int used_partition;
/* read the MBR on disc and get the type of the partition */
ret = iso_stream_open(stream);
if (ret < 0) {
iso_msg_submit(image->id, ISO_BOOT_IMAGE_NOT_VALID, ret,
"Can't open image file.");
return ret;
}
ret = iso_stream_read(stream, &mbr, sizeof(mbr));
iso_stream_close(stream);
if (ret != sizeof(mbr)) {
iso_msg_submit(image->id, ISO_BOOT_IMAGE_NOT_VALID, 0,
"Can't read MBR from image file.");
return ret < 0 ? ret : ISO_FILE_READ_ERROR;
}
/* check valid MBR signature */
if ( mbr.sign1 != 0x55 || mbr.sign2 != 0xAA ) {
iso_msg_submit(image->id, ISO_BOOT_IMAGE_NOT_VALID, 0,
"Invalid MBR. Wrong signature.");
return ISO_BOOT_IMAGE_NOT_VALID;
}
/* ensure single partition */
used_partition = -1;
for (i = 0; i < 4; ++i) {
if (mbr.partition[i].type != 0) {
/* it's an used partition */
if (used_partition != -1) {
iso_msg_submit(image->id, ISO_BOOT_IMAGE_NOT_VALID, 0,
"Invalid MBR. At least 2 partitions: %d and "
"%d, are being used\n", used_partition, i);
return ISO_BOOT_IMAGE_NOT_VALID;
} else
used_partition = i;
}
}
partition_type = mbr.partition[used_partition].type;
}
boot_media_type = 4;
/* only load the MBR */
load_sectors = 1;
break;
case ELTORITO_NO_EMUL:
boot_media_type = 0;
break;
}
boot = calloc(1, sizeof(struct el_torito_boot_image));
if (boot == NULL) {
return ISO_OUT_OF_MEM;
}
boot->image = (IsoFile*)imgfile;
iso_node_ref(imgfile); /* get our ref */
boot->bootable = 1;
boot->type = boot_media_type;
boot->load_size = load_sectors;
boot->partition_type = partition_type;
if (bootimg) {
*bootimg = boot;
}
return ISO_SUCCESS;
}
int iso_image_set_boot_image(IsoImage *image, const char *image_path,
enum eltorito_boot_media_type type,
const char *catalog_path,
ElToritoBootImage **boot)
{
int ret;
struct el_torito_boot_catalog *catalog;
ElToritoBootImage *boot_image= NULL;
IsoBoot *cat_node= NULL;
if (image == NULL || image_path == NULL || catalog_path == NULL) {
return ISO_NULL_POINTER;
}
if (image->bootcat != NULL) {
return ISO_IMAGE_ALREADY_BOOTABLE;
}
/* create the node for the catalog */
{
IsoDir *parent;
char *catdir = NULL, *catname = NULL;
catdir = strdup(catalog_path);
if (catdir == NULL) {
return ISO_OUT_OF_MEM;
}
/* get both the dir and the name */
catname = strrchr(catdir, '/');
if (catname == NULL) {
free(catdir);
return ISO_WRONG_ARG_VALUE;
}
if (catname == catdir) {
/* we are apending catalog to root node */
parent = image->root;
} else {
IsoNode *p;
catname[0] = '\0';
ret = iso_tree_path_to_node(image, catdir, &p);
if (ret <= 0) {
free(catdir);
return ret < 0 ? ret : ISO_NODE_DOESNT_EXIST;
}
if (p->type != LIBISO_DIR) {
free(catdir);
return ISO_WRONG_ARG_VALUE;
}
parent = (IsoDir*)p;
}
catname++;
ret = iso_tree_add_boot_node(parent, catname, &cat_node);
free(catdir);
if (ret < 0) {
return ret;
}
}
/* create the boot image */
ret = create_image(image, image_path, type, &boot_image);
if (ret < 0) {
goto boot_image_cleanup;
}
/* creates the catalog with the given image */
catalog = malloc(sizeof(struct el_torito_boot_catalog));
if (catalog == NULL) {
ret = ISO_OUT_OF_MEM;
goto boot_image_cleanup;
}
catalog->image = boot_image;
catalog->node = cat_node;
iso_node_ref((IsoNode*)cat_node);
image->bootcat = catalog;
if (boot) {
*boot = boot_image;
}
return ISO_SUCCESS;
boot_image_cleanup:;
if (cat_node) {
iso_node_take((IsoNode*)cat_node);
iso_node_unref((IsoNode*)cat_node);
}
if (boot_image) {
iso_node_unref((IsoNode*)boot_image->image);
free(boot_image);
}
return ret;
}
/**
* Get El-Torito boot image of an ISO image, if any.
*
* This can be useful, for example, to check if a volume read from a previous
* session or an existing image is bootable. It can also be useful to get
* the image and catalog tree nodes. An application would want those, for
* example, to prevent the user removing it.
*
* Both nodes are owned by libisofs and should not be freed. You can get your
* own ref with iso_node_ref(). You can can also check if the node is already
* on the tree by getting its parent (note that when reading El-Torito info
* from a previous image, the nodes might not be on the tree even if you haven't
* removed them). Remember that you'll need to get a new ref
* (with iso_node_ref()) before inserting them again to the tree, and probably
* you will also need to set the name or permissions.
*
* @param image
* The image from which to get the boot image.
* @param boot
* If not NULL, it will be filled with a pointer to the boot image, if
* any. That object is owned by the IsoImage and should not be freed by
* the user, nor dereferenced once the last reference to the IsoImage was
* disposed via iso_image_unref().
* @param imgnode
* When not NULL, it will be filled with the image tree node. No extra ref
* is added, you can use iso_node_ref() to get one if you need it.
* @param catnode
* When not NULL, it will be filled with the catnode tree node. No extra
* ref is added, you can use iso_node_ref() to get one if you need it.
* @return
* 1 on success, 0 is the image is not bootable (i.e., it has no El-Torito
* image), < 0 error.
*/
int iso_image_get_boot_image(IsoImage *image, ElToritoBootImage **boot,
IsoFile **imgnode, IsoBoot **catnode)
{
if (image == NULL) {
return ISO_NULL_POINTER;
}
if (image->bootcat == NULL) {
return 0;
}
/* ok, image is bootable */
if (boot) {
*boot = image->bootcat->image;
}
if (imgnode) {
*imgnode = image->bootcat->image->image;
}
if (catnode) {
*catnode = image->bootcat->node;
}
return ISO_SUCCESS;
}
/**
* Removes the El-Torito bootable image.
*
* The IsoBoot node that acts as placeholder for the catalog is also removed
* for the image tree, if there.
* If the image is not bootable (don't have el-torito boot image) this function
* just returns.
*/
void iso_image_remove_boot_image(IsoImage *image)
{
if (image == NULL || image->bootcat == NULL)
return;
/*
* remove catalog node from its parent
* (the reference will be disposed next)
*/
iso_node_take((IsoNode*)image->bootcat->node);
/* free boot catalog and image, including references to nodes */
el_torito_boot_catalog_free(image->bootcat);
image->bootcat = NULL;
}
void el_torito_boot_catalog_free(struct el_torito_boot_catalog *cat)
{
struct el_torito_boot_image *image;
if (cat == NULL) {
return;
}
image = cat->image;
iso_node_unref((IsoNode*)image->image);
free(image);
iso_node_unref((IsoNode*)cat->node);
free(cat);
}
/**
* Stream that generates the contents of a El-Torito catalog.
*/
struct catalog_stream
{
Ecma119Image *target;
uint8_t buffer[BLOCK_SIZE];
int offset; /* -1 if stream is not openned */
};
static void
write_validation_entry(uint8_t *buf)
{
size_t i;
int checksum;
struct el_torito_validation_entry *ve =
(struct el_torito_validation_entry*)buf;
ve->header_id[0] = 1;
ve->platform_id[0] = 0; /* 0: 80x86, 1: PowerPC, 2: Mac */
ve->key_byte1[0] = 0x55;
ve->key_byte2[0] = 0xAA;
/* calculate the checksum, to ensure sum of all words is 0 */
checksum = 0;
for (i = 0; i < sizeof(struct el_torito_validation_entry); i += 2) {
checksum -= (int16_t) ((buf[i+1] << 8) | buf[i]);
}
iso_lsb(ve->checksum, checksum, 2);
}
/**
* Write one section entry.
* Currently this is used only for default image (the only supported just now)
*/
static void
write_section_entry(uint8_t *buf, Ecma119Image *t)
{
struct el_torito_boot_image *img;
struct el_torito_section_entry *se =
(struct el_torito_section_entry*)buf;
img = t->catalog->image;
se->boot_indicator[0] = img->bootable ? 0x88 : 0x00;
se->boot_media_type[0] = img->type;
iso_lsb(se->load_seg, img->load_seg, 2);
se->system_type[0] = img->partition_type;
iso_lsb(se->sec_count, img->load_size, 2);
iso_lsb(se->block, t->bootimg->block, 4);
}
static
int catalog_open(IsoStream *stream)
{
struct catalog_stream *data;
if (stream == NULL) {
return ISO_NULL_POINTER;
}
data = stream->data;
if (data->offset != -1) {
return ISO_FILE_ALREADY_OPENNED;
}
memset(data->buffer, 0, BLOCK_SIZE);
/* fill the buffer with the catalog contents */
write_validation_entry(data->buffer);
/* write default entry */
write_section_entry(data->buffer + 32, data->target);
data->offset = 0;
return ISO_SUCCESS;
}
static
int catalog_close(IsoStream *stream)
{
struct catalog_stream *data;
if (stream == NULL) {
return ISO_NULL_POINTER;
}
data = stream->data;
if (data->offset == -1) {
return ISO_FILE_NOT_OPENNED;
}
data->offset = -1;
return ISO_SUCCESS;
}
static
off_t catalog_get_size(IsoStream *stream)
{
return BLOCK_SIZE;
}
static
int catalog_read(IsoStream *stream, void *buf, size_t count)
{
size_t len;
struct catalog_stream *data;
if (stream == NULL || buf == NULL) {
return ISO_NULL_POINTER;
}
if (count == 0) {
return ISO_WRONG_ARG_VALUE;
}
data = stream->data;
if (data->offset == -1) {
return ISO_FILE_NOT_OPENNED;
}
len = MIN(count, BLOCK_SIZE - data->offset);
memcpy(buf, data->buffer + data->offset, len);
return len;
}
static
int catalog_is_repeatable(IsoStream *stream)
{
return 1;
}
/**
* fs_id will be the id reserved for El-Torito
* dev_id will be 0 for catalog, 1 for boot image (if needed)
* we leave ino_id for future use when we support multiple boot images
*/
static
void catalog_get_id(IsoStream *stream, unsigned int *fs_id, dev_t *dev_id,
ino_t *ino_id)
{
*fs_id = ISO_ELTORITO_FS_ID;
*dev_id = 0;
*ino_id = 0;
}
static
char *catalog_get_name(IsoStream *stream)
{
return strdup("El-Torito Boot Catalog");
}
static
void catalog_free(IsoStream *stream)
{
free(stream->data);
}
IsoStreamIface catalog_stream_class = {
catalog_open,
catalog_close,
catalog_get_size,
catalog_read,
catalog_is_repeatable,
catalog_get_id,
catalog_get_name,
catalog_free
};
/**
* Create an IsoStream for writing El-Torito catalog for a given target.
*/
static
int catalog_stream_new(Ecma119Image *target, IsoStream **stream)
{
IsoStream *str;
struct catalog_stream *data;
if (target == NULL || stream == NULL || target->catalog == NULL) {
return ISO_NULL_POINTER;
}
str = malloc(sizeof(IsoStream));
if (str == NULL) {
return ISO_OUT_OF_MEM;
}
data = malloc(sizeof(struct catalog_stream));
if (str == NULL) {
free(str);
return ISO_OUT_OF_MEM;
}
/* fill data */
data->target = target;
data->offset = -1;
str->refcount = 1;
str->data = data;
str->class = &catalog_stream_class;
*stream = str;
return ISO_SUCCESS;
}
int el_torito_catalog_file_src_create(Ecma119Image *target, IsoFileSrc **src)
{
int ret;
IsoFileSrc *file;
IsoStream *stream;
if (target == NULL || src == NULL || target->catalog == NULL) {
return ISO_OUT_OF_MEM;
}
if (target->cat != NULL) {
/* catalog file src already created */
*src = target->cat;
return ISO_SUCCESS;
}
file = malloc(sizeof(IsoFileSrc));
if (file == NULL) {
return ISO_OUT_OF_MEM;
}
ret = catalog_stream_new(target, &stream);
if (ret < 0) {
free(file);
return ret;
}
/* fill fields */
file->prev_img = 0; /* TODO allow copy of old img catalog???? */
file->block = 0; /* to be filled later */
file->sort_weight = 1000; /* slightly high */
file->stream = stream;
ret = iso_file_src_add(target, file, src);
if (ret <= 0) {
iso_stream_unref(stream);
free(file);
} else {
target->cat = *src;
}
return ret;
}
/******************* EL-TORITO WRITER *******************************/
static
int eltorito_writer_compute_data_blocks(IsoImageWriter *writer)
{
/* nothing to do, the files are written by the file writer */
return ISO_SUCCESS;
}
/**
* Write the Boot Record Volume Descriptor (ECMA-119, 8.2)
*/
static
int eltorito_writer_write_vol_desc(IsoImageWriter *writer)
{
Ecma119Image *t;
struct el_torito_boot_catalog *cat;
struct ecma119_boot_rec_vol_desc vol;
if (writer == NULL) {
return ISO_NULL_POINTER;
}
t = writer->target;
cat = t->catalog;
iso_msg_debug(t->image->id, "Write El-Torito boot record");
memset(&vol, 0, sizeof(struct ecma119_boot_rec_vol_desc));
vol.vol_desc_type[0] = 0;
memcpy(vol.std_identifier, "CD001", 5);
vol.vol_desc_version[0] = 1;
memcpy(vol.boot_sys_id, "EL TORITO SPECIFICATION", 23);
iso_lsb(vol.boot_catalog, t->cat->block, 4);
return iso_write(t, &vol, sizeof(struct ecma119_boot_rec_vol_desc));
}
/**
* Patch an isolinux boot image.
*
* @return
* 1 on success, 0 error (but continue), < 0 error
*/
static
int patch_boot_image(uint8_t *buf, Ecma119Image *t, size_t imgsize)
{
struct boot_info_table *info;
uint32_t checksum;
size_t offset;
if (imgsize < 64) {
return iso_msg_submit(t->image->id, ISO_ISOLINUX_CANT_PATCH, 0,
"Isolinux image too small. We won't patch it.");
}
/* compute checksum, as the the sum of all 32 bit words in boot image
* from offset 64 */
checksum = 0;
offset = (size_t) 64;
while (offset <= imgsize - 4) {
checksum += iso_read_lsb(buf + offset, 4);
offset += 4;
}
if (offset != imgsize) {
/* file length not multiple of 4 */
return iso_msg_submit(t->image->id, ISO_ISOLINUX_CANT_PATCH, 0,
"Unexpected isolinux image length. Patch might not work.");
}
/* patch boot info table */
info = (struct boot_info_table*)(buf + 8);
/*memset(info, 0, sizeof(struct boot_info_table));*/
iso_lsb(info->bi_pvd, t->ms_block + 16, 4);
iso_lsb(info->bi_file, t->bootimg->block, 4);
iso_lsb(info->bi_length, imgsize, 4);
iso_lsb(info->bi_csum, checksum, 4);
return ISO_SUCCESS;
}
static
int eltorito_writer_write_data(IsoImageWriter *writer)
{
/*
* We have nothing to write, but if we need to patch an isolinux image,
* this is a good place to do so.
*/
Ecma119Image *t;
int ret;
if (writer == NULL) {
return ISO_NULL_POINTER;
}
t = writer->target;
if (t->catalog->image->isolinux) {
/* we need to patch the image */
size_t size;
uint8_t *buf;
IsoStream *new = NULL;
IsoStream *original = t->bootimg->stream;
size = (size_t) iso_stream_get_size(original);
buf = malloc(size);
if (buf == NULL) {
return ISO_OUT_OF_MEM;
}
ret = iso_stream_open(original);
if (ret < 0) {
return ret;
}
ret = iso_stream_read(original, buf, size);
iso_stream_close(original);
if (ret != size) {
return (ret < 0) ? ret : ISO_FILE_READ_ERROR;
}
/* ok, patch the read buffer */
ret = patch_boot_image(buf, t, size);
if (ret < 0) {
return ret;
}
/* replace the original stream with a memory stream that reads from
* the patched buffer */
ret = iso_memory_stream_new(buf, size, &new);
if (ret < 0) {
return ret;
}
t->bootimg->stream = new;
iso_stream_unref(original);
}
return ISO_SUCCESS;
}
static
int eltorito_writer_free_data(IsoImageWriter *writer)
{
/* nothing to do */
return ISO_SUCCESS;
}
int eltorito_writer_create(Ecma119Image *target)
{
int ret;
IsoImageWriter *writer;
IsoFile *bootimg;
IsoFileSrc *src;
writer = malloc(sizeof(IsoImageWriter));
if (writer == NULL) {
return ISO_OUT_OF_MEM;
}
writer->compute_data_blocks = eltorito_writer_compute_data_blocks;
writer->write_vol_desc = eltorito_writer_write_vol_desc;
writer->write_data = eltorito_writer_write_data;
writer->free_data = eltorito_writer_free_data;
writer->data = NULL;
writer->target = target;
/* add this writer to image */
target->writers[target->nwriters++] = writer;
/*
* get catalog and image file sources.
* Note that the catalog may be already added, when creating the low
* level ECMA-119 tree.
*/
if (target->cat == NULL) {
ret = el_torito_catalog_file_src_create(target, &src);
if (ret < 0) {
return ret;
}
}
bootimg = target->catalog->image->image;
ret = iso_file_src_create(target, bootimg, &src);
if (ret < 0) {
return ret;
}
target->bootimg = src;
/* if we have selected to patch the image, it needs to be copied always */
if (target->catalog->image->isolinux) {
src->prev_img = 0;
}
/* we need the bootable volume descriptor */
target->curblock++;
return ISO_SUCCESS;
}
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