kernel: mtdsplit: Add support for D-link JBOOT

The D-Link devices with JBOOT bootloader use their own kernel
image header (stag + sch2 headers).

This driver find jImage header and set rootfs start after kernel file.

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>

3 files changed, 283 insertions, 0 deletions

diff --git a/target/linux/generic/files/drivers/mtd/mtdsplit/Kconfig b/target/linux/generic/files/drivers/mtd/mtdsplit/Kconfig
index 4a15d48..81ece43 100644
--- a/target/linux/generic/files/drivers/mtd/mtdsplit/Kconfig
+++ b/target/linux/generic/files/drivers/mtd/mtdsplit/Kconfig
@@ -69,3 +69,8 @@ config MTD_SPLIT_MINOR_FW
 	bool "Mikrotik NOR image based firmware partition parser"
 	depends on MTD_SPLIT_SUPPORT
 	select MTD_SPLIT
+
+config MTD_SPLIT_JIMAGE_FW
+	bool "JBOOT Image based firmware partition parser"
+	depends on MTD_SPLIT_SUPPORT
+	select MTD_SPLIT
diff --git a/target/linux/generic/files/drivers/mtd/mtdsplit/Makefile b/target/linux/generic/files/drivers/mtd/mtdsplit/Makefile
index fab85ca..206e754 100644
--- a/target/linux/generic/files/drivers/mtd/mtdsplit/Makefile
+++ b/target/linux/generic/files/drivers/mtd/mtdsplit/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_MTD_SPLIT_BRNIMAGE_FW) += mtdsplit_brnimage.o
 obj-$(CONFIG_MTD_SPLIT_EVA_FW) += mtdsplit_eva.o
 obj-$(CONFIG_MTD_SPLIT_WRGG_FW) += mtdsplit_wrgg.o
 obj-$(CONFIG_MTD_SPLIT_MINOR_FW) += mtdsplit_minor.o
+obj-$(CONFIG_MTD_SPLIT_JIMAGE_FW) += mtdsplit_jimage.o
diff --git a/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_jimage.c b/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_jimage.c
new file mode 100644
index 0000000..51544a7
--- /dev/null
+++ b/target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_jimage.c
@@ -0,0 +1,277 @@
+/*
+ *  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);