Re: [PATCH 001/001] CHAR DRIVERS: a simple device to give daemonsa /sys-like interface

From: Bob Smith
Date: Wed Aug 07 2013 - 15:39:54 EST

Greg Kroah-Hartman wrote:
* sudo chmod 666 /dev/proxyout /dev/proxyctrl
That's mighty permissive :(
For a demo it might be OK.

BUT: I think I should modify the module to forward a close request
(write 0 bytes) only if the sender UID matched the proxy node's UID.
This might not be strictly required but is a security nice to have.

* gcc -o pxtest pxtest.c
* ./pxtest &
* cat /dev/proxyout # view the output
* (switch to another terminal window)
* cat /dev/proxyctrl # what is the offset?
* echo 2 > /dev/proxyctrl # set offset to 2

I really don't understand this, you just have two programs talking to
each other, passing the data blindly through the kernel. Again, we
already have over 10 different ways to do IPC these days, are you _sure_
that _none_ of them work for you like this? You have gone and looked at
them all, right?

All along I've had a clear goal. I want to configure a running program
the same way I configure the kernel. It is simple and I don't need any
language bindings.
cat /dev/proxyctrl # what is the offset?
echo 2 > /dev/proxyctrl # set offset to 2

Yes, I am sure that nothing else will do. A named pipe is the closest
but it has a buffer and is not bidirectional. I am also convinced that
there is no way to do what I want with fewer lines of code.

Bob Smith

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