xqrepack

These scripts allow you to modify the Xiaomi R3600 firmware image to make sure SSH and UART access is always enabled.

The default root password is password. Please remember to login to the router and change that after the upgrade. Your router settings like IP address and SSIDs are stored in the nvram and should stay the same.

The script also tries its best to remove or disable phone-home binaries, and also the smart controller (AIoT) parts, leaving you with a (close to) OpenWRT router that you can configure via UCI or /etc/config.

Note that in order to get SSH access to the router initially, you need to downgrade to version 1.0.17 and exploit it first. Once you have SSH, you can use this repacking method to maintain SSH access for newer versions.

Requirements

You will need to install the following tools:

• ubi_reader
• ubinize
• unsquashfs / mksquashfs
• fakeroot

Usage

1. Download the firmware from miwifi.com. It should be something like miwifi_r3600_firmware_xxx_yyy.bin.

2. Use the ubireader_extract_images utility from ubi_reader to unpack the UBI image from the firmware. Technically there's junk at the front, but the script will ignore it:

    ubireader_extract_images -w miwifi_r3600_firmware_xxx_yyy.bin
   

   The unpacked files will be in the ubifs-root/miwifi_r3600_firmware... directory.

3. Patch the rootfs using the repack-squashfs.sh script:

    fakeroot -- ./repack-squashfs.sh ubifs-root/miwifi_r3600_firmware.../img-264..._vol-ubi_rootfs.ubifs
   

   The script will create a new squashfs image with the .new suffix. You will need fakeroot in order to create files and devices as root. You could also run this script as root, but please don't.

4. Recombine the kernel and patched rootfs with ubinize.sh:

    ./ubinize.sh ubifs-root/miwifi_r3600_firmware.../...kernel.ubifs \
                 ubifs-root/miwifi_r3600_firmware.../...ubi_rootfs.ubifs.new
   

   Note the use of the .ubifs.new file. The combined output file will be r3600-raw-img.bin.

5. Flash this file directly into the router using SSH. You cannot use the web UI because this is a raw image, and more importantly has no signature.

   The R3600 firmware uses an A/B partition system, called rootfs and rootfs_1. This corresponds to mtd12 and mtd13. Find the partition that is not the one in use and use ubiformat to write the raw image onto the partition:

    ubiformat /dev/mtd12 -f /tmp/r3600-raw-img.bin -s 2048 -O 2048
   

6. Set the nvram variable to re-initialize /etc (and I think to switch partitions also):

    nvram set flag_ota_reboot=1
    nvram commit
    reboot
   

A/B Partitions

You can check the MTD partitions from /proc/mtd:

root@XiaoQiang:~# grep rootfs /proc/mtd
mtd12: 023c0000 00020000 "rootfs"
mtd13: 023c0000 00020000 "rootfs_1"
mtd17: 015cc000 0001f000 "ubi_rootfs"

root@XiaoQiang:~# nvram get flag_boot_rootfs
1

The flag_boot_rootfs nvram variable indicates which partition is booted, 0 or 1. You should pick the partition that is not in use, otherwise ubiformat will complain:

ubiformat: error!: please, first detach mtd13 (/dev/mtd13) from ubi0

License

xqrepack is licensed under the 3-clause ("modified") BSD License.

Copyright (C) 2020 Darell Tan

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.