OpenWrt – Rev 3
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/*
* Copyright (C) 2018 Paweł Dembicki <paweldembicki@gmail.com>
*
* Based on: mtdsplit_uimage.c
* Copyright (C) 2013 Gabor Juhos <juhosg@openwrt.org>
*
* This program is free software; 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.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/byteorder/generic.h>
#include "mtdsplit.h"
#define MAX_HEADER_LEN ( STAG_SIZE + SCH2_SIZE )
#define STAG_SIZE 16
#define STAG_ID 0x04
#define STAG_MAGIC 0x2B24
#define SCH2_SIZE 40
#define SCH2_MAGIC 0x2124
#define SCH2_VER 0x02
/*
* Jboot image header,
* all data in little endian.
*/
struct jimage_header //stag + sch2 jboot joined headers
{
uint8_t stag_cmark; // in factory 0xFF , in sysupgrade must be the same as stag_id
uint8_t stag_id; // 0x04
uint16_t stag_magic; //magic 0x2B24
uint32_t stag_time_stamp; // timestamp calculated in jboot way
uint32_t stag_image_length; // lentgh of kernel + sch2 header
uint16_t stag_image_checksum; // negated jboot_checksum of sch2 + kernel
uint16_t stag_tag_checksum; // negated jboot_checksum of stag header data
uint16_t sch2_magic; // magic 0x2124
uint8_t sch2_cp_type; // 0x00 for flat, 0x01 for jz, 0x02 for gzip, 0x03 for lzma
uint8_t sch2_version; // 0x02 for sch2
uint32_t sch2_ram_addr; // ram entry address
uint32_t sch2_image_len; // kernel image length
uint32_t sch2_image_crc32; // kernel image crc
uint32_t sch2_start_addr; // ram start address
uint32_t sch2_rootfs_addr; // rootfs flash address
uint32_t sch2_rootfs_len; // rootfls length
uint32_t sch2_rootfs_crc32; // rootfs crc32
uint32_t sch2_header_crc32; // sch2 header crc32, durring calculation this area is replaced by zero
uint16_t sch2_header_length; // sch2 header length: 0x28
uint16_t sch2_cmd_line_length; // cmd line length, known zeros
};
static int
read_jimage_header(struct mtd_info *mtd, size_t offset, u_char *buf,
size_t header_len)
{
size_t retlen;
int ret;
ret = mtd_read(mtd, offset, header_len, &retlen, buf);
if (ret) {
pr_debug("read error in \"%s\"\n", mtd->name);
return ret;
}
if (retlen != header_len) {
pr_debug("short read in \"%s\"\n", mtd->name);
return -EIO;
}
return 0;
}
/**
* __mtdsplit_parse_jimage - scan partition and create kernel + rootfs parts
*
* @find_header: function to call for a block of data that will return offset
* of a valid jImage header if found
*/
static int __mtdsplit_parse_jimage(struct mtd_info *master,
const struct mtd_partition **pparts,
struct mtd_part_parser_data *data,
ssize_t (*find_header)(u_char *buf, size_t len))
{
struct mtd_partition *parts;
u_char *buf;
int nr_parts;
size_t offset;
size_t jimage_offset;
size_t jimage_size = 0;
size_t rootfs_offset;
size_t rootfs_size = 0;
int jimage_part, rf_part;
int ret;
enum mtdsplit_part_type type;
nr_parts = 2;
parts = kzalloc(nr_parts * sizeof(*parts), GFP_KERNEL);
if (!parts)
return -ENOMEM;
buf = vmalloc(MAX_HEADER_LEN);
if (!buf) {
ret = -ENOMEM;
goto err_free_parts;
}
/* find jImage on erase block boundaries */
for (offset = 0; offset < master->size; offset += master->erasesize) {
struct jimage_header *header;
jimage_size = 0;
ret = read_jimage_header(master, offset, buf, MAX_HEADER_LEN);
if (ret)
continue;
ret = find_header(buf, MAX_HEADER_LEN);
if (ret < 0) {
pr_debug("no valid jImage found in \"%s\" at offset %llx\n",
master->name, (unsigned long long) offset);
continue;
}
header = (struct jimage_header *)(buf + ret);
jimage_size = sizeof(*header) + header->sch2_image_len + ret;
if ((offset + jimage_size) > master->size) {
pr_debug("jImage exceeds MTD device \"%s\"\n",
master->name);
continue;
}
break;
}
if (jimage_size == 0) {
pr_debug("no jImage found in \"%s\"\n", master->name);
ret = -ENODEV;
goto err_free_buf;
}
jimage_offset = offset;
if (jimage_offset == 0) {
jimage_part = 0;
rf_part = 1;
/* find the roots after the jImage */
ret = mtd_find_rootfs_from(master, jimage_offset + jimage_size,
master->size, &rootfs_offset, &type);
if (ret) {
pr_debug("no rootfs after jImage in \"%s\"\n",
master->name);
goto err_free_buf;
}
rootfs_size = master->size - rootfs_offset;
jimage_size = rootfs_offset - jimage_offset;
} else {
rf_part = 0;
jimage_part = 1;
/* check rootfs presence at offset 0 */
ret = mtd_check_rootfs_magic(master, 0, &type);
if (ret) {
pr_debug("no rootfs before jImage in \"%s\"\n",
master->name);
goto err_free_buf;
}
rootfs_offset = 0;
rootfs_size = jimage_offset;
}
if (rootfs_size == 0) {
pr_debug("no rootfs found in \"%s\"\n", master->name);
ret = -ENODEV;
goto err_free_buf;
}
parts[jimage_part].name = KERNEL_PART_NAME;
parts[jimage_part].offset = jimage_offset;
parts[jimage_part].size = jimage_size;
if (type == MTDSPLIT_PART_TYPE_UBI)
parts[rf_part].name = UBI_PART_NAME;
else
parts[rf_part].name = ROOTFS_PART_NAME;
parts[rf_part].offset = rootfs_offset;
parts[rf_part].size = rootfs_size;
vfree(buf);
*pparts = parts;
return nr_parts;
err_free_buf:
vfree(buf);
err_free_parts:
kfree(parts);
return ret;
}
static ssize_t jimage_verify_default(u_char *buf, size_t len)
{
struct jimage_header *header = (struct jimage_header *)buf;
/* default sanity checks */
if (header->stag_magic != STAG_MAGIC) {
pr_debug("invalid jImage stag header magic: %04x\n",
header->stag_magic);
return -EINVAL;
}
if (header->sch2_magic != SCH2_MAGIC) {
pr_debug("invalid jImage sch2 header magic: %04x\n",
header->stag_magic);
return -EINVAL;
}
if (header->stag_cmark != header->stag_id) {
pr_debug("invalid jImage stag header cmark: %02x\n",
header->stag_magic);
return -EINVAL;
}
if (header->stag_id != STAG_ID) {
pr_debug("invalid jImage stag header id: %02x\n",
header->stag_magic);
return -EINVAL;
}
if (header->sch2_version != SCH2_VER) {
pr_debug("invalid jImage sch2 header version: %02x\n",
header->stag_magic);
return -EINVAL;
}
return 0;
}
static int
mtdsplit_jimage_parse_generic(struct mtd_info *master,
const struct mtd_partition **pparts,
struct mtd_part_parser_data *data)
{
return __mtdsplit_parse_jimage(master, pparts, data,
jimage_verify_default);
}
static struct mtd_part_parser jimage_generic_parser = {
.owner = THIS_MODULE,
.name = "jimage-fw",
.parse_fn = mtdsplit_jimage_parse_generic,
.type = MTD_PARSER_TYPE_FIRMWARE,
};
/**************************************************
* Init
**************************************************/
static int __init mtdsplit_jimage_init(void)
{
register_mtd_parser(&jimage_generic_parser);
return 0;
}
module_init(mtdsplit_jimage_init);