This adds brnImage (used with the brnboot bootloader) firmware parsing support. brnboot verifies the integrity of the firmware stored on the "Code Image" partitions by looking at the 12 byte footer at the very end of the partition. This footer contains the checksum of the original brnImage (kernel + rootfs/squashfs) and must not be touched (by our JFFS2 rootfs_data - otherwise the image will not be bootable anymore). Big thanks to Mathias Kresin for analyzing the brnImage structure and finding out the information how to keep images valid even when adding a nested rootfs_data partition. Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> SVN-Revision: 48261master
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/*
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* Copyright (C) 2012 John Crispin <blogic@openwrt.org> |
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* Copyright (C) 2015 Martin Blumenstingl <martin.blumenstingl@googlemail.com> |
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* |
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* This program is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 as published |
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* by the Free Software Foundation. |
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* |
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*/ |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/slab.h> |
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#include <linux/mtd/mtd.h> |
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#include <linux/mtd/partitions.h> |
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#include <linux/byteorder/generic.h> |
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#include "mtdsplit.h" |
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#define BRNIMAGE_NR_PARTS 2 |
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#define BRNIMAGE_ALIGN_BYTES 0x400 |
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#define BRNIMAGE_FOOTER_SIZE 12 |
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#define BRNIMAGE_MIN_OVERHEAD (BRNIMAGE_FOOTER_SIZE) |
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#define BRNIMAGE_MAX_OVERHEAD (BRNIMAGE_ALIGN_BYTES + BRNIMAGE_FOOTER_SIZE) |
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static int mtdsplit_parse_brnimage(struct mtd_info *master, |
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struct mtd_partition **pparts, |
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struct mtd_part_parser_data *data) |
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{ |
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struct mtd_partition *parts; |
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uint32_t buf; |
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unsigned long rootfs_offset, rootfs_size, kernel_size; |
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size_t len; |
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int ret; |
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for (rootfs_offset = 0; rootfs_offset < master->size; |
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rootfs_offset += BRNIMAGE_ALIGN_BYTES) { |
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ret = mtd_check_rootfs_magic(master, rootfs_offset); |
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if (!ret) |
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break; |
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} |
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if (ret) |
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return ret; |
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if (rootfs_offset >= master->size) |
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return -EINVAL; |
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ret = mtd_read(master, rootfs_offset - BRNIMAGE_FOOTER_SIZE, 4, &len, |
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(void *)&buf); |
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if (ret) |
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return ret; |
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if (len != 4) |
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return -EIO; |
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kernel_size = le32_to_cpu(buf); |
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if (kernel_size > (rootfs_offset - BRNIMAGE_MIN_OVERHEAD)) |
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return -EINVAL; |
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if (kernel_size < (rootfs_offset - BRNIMAGE_MAX_OVERHEAD)) |
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return -EINVAL; |
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/*
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* The footer must be untouched as it contains the checksum of the |
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* original brnImage (kernel + squashfs)! |
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*/ |
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rootfs_size = master->size - rootfs_offset - BRNIMAGE_FOOTER_SIZE; |
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parts = kzalloc(BRNIMAGE_NR_PARTS * sizeof(*parts), GFP_KERNEL); |
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if (!parts) |
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return -ENOMEM; |
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parts[0].name = KERNEL_PART_NAME; |
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parts[0].offset = 0; |
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parts[0].size = kernel_size; |
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parts[1].name = ROOTFS_PART_NAME; |
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parts[1].offset = rootfs_offset; |
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parts[1].size = rootfs_size; |
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*pparts = parts; |
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return BRNIMAGE_NR_PARTS; |
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} |
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static struct mtd_part_parser mtdsplit_brnimage_parser = { |
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.owner = THIS_MODULE, |
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.name = "brnimage-fw", |
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.parse_fn = mtdsplit_parse_brnimage, |
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.type = MTD_PARSER_TYPE_FIRMWARE, |
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}; |
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static int __init mtdsplit_brnimage_init(void) |
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{ |
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register_mtd_parser(&mtdsplit_brnimage_parser); |
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return 0; |
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} |
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subsys_initcall(mtdsplit_brnimage_init); |
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