Debian on WD My Cloud EX4

Hello again,

I had a bit of a boost in energy this evening and thought I would do some digging into the firmware, I found two binaries of interest, /usr/sbin/fan_control and /usr/sbin/led, "fan_control" controls the fan as you would expect you can turn it on and off and set speed and get the fan RPM, "led" allows me to set the power led status (on, off, blinking, red or blue) as well as each of the four hard drive LED's (again, red, blue, blinking, etc), I'll attach each binary as well as the help text for each, I looked at them in Ghidra (I am by no means good as reverse engineering haha) and from what I can see for the led control anyway it seems to directly set a CPU register of some sort, I don't know if that seems probable or not but that's my best guess, as for the LED screen on the front, that seems like a much bigger feat and I don't know if that would be possible to get working under debian but I'll keep looking to see how it's controlled in the stock firmware,

Thanks!

> I found two binaries of interest,
> /usr/sbin/fan_control and /usr/sbin/led,
> "fan_control" controls the fan as you would expect
> you can turn it on and off and set speed and get
> the fan RPM, "led" allows me to set the power led
> status (on, off, blinking, red or blue) as well as
> each of the four hard drive LED's (again, red,
> blue, blinking, etc), I'll attach each binary as
> well as the help text for each,

If these were scripts, it would be much more helpful. Binaries, not so much. So I would recommend searching the GPL source instead.

-bodhi
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Sadly the fan control and led tools are supplied in their binary form even in the GPL, there are no other references to led's or fan control anywhere else in the GPL so that may be a no go unfortunately.

> Sadly the fan control and led tools are supplied
> in their binary form even in the GPL, there are no
> other references to led's or fan control anywhere
> else in the GPL so that may be a no go
> unfortunately.

Sometime this happens with a company that intentionally implemented a malicious compliance to GPL. Instead of disclosing how they control a piece of hardware like everybody else, they close source that piece of code because they can and not violating GPL.

Normally LEDS and fan are controlled by GPIOs. In some cases, by serial TTY (like in some Synology NAS). Most comapanies provide patches (GPIOs) or scripts (TTYs) in their GPL sources.

We can just copy these binaries to the rootfs and run it. If those were static binary then there would be no problem. If these were dynamic binary then some old shared library on stock OS also need to be repackaged so we can run them in modern Debian system.

Find out what are they:

file <fancontrol binary>
file <LED control binary>

-bodhi
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They are dynamically linked

fan_control: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.3, for GNU/Linux 2.6.16, stripped
led:         ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.3, for GNU/Linux 2.6.16, stripped

@ConcentratedCancer,

Go ahead copy the fan_control and led binaries to your rootfs /tmp.

And try running it

cd /tmp
./fan_control
./led

-bodhi
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