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[ts-7000] Re: TS7500 DIO control while user is not root

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Subject: [ts-7000] Re: TS7500 DIO control while user is not root
From: "frankvd99" <>
Date: Thu, 13 Jan 2011 19:19:04 -0000
Hi Jonatan, Jim,
Thanks for your feedback.

I've tried to do a chmod 666 on /dev/mem but that still does not solve the 
problem. Also when I reboot the system the properties are set back to 600

I find conflicting information when I google around on this topic. Some are 
saying /dev/mem will give access to the memory from the user space. Others are 
saying you need to create a driver to get access to it. 

To me it is strange that there are several examples from Technologic Systems 
available but there is never a notice that you should run it as root.
ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7500-linux/samples/dio.c

Are there other users of the TS7500 board who have different properties for 
/dev/mem? I've downloaded and installed debian linux from the Technologic FTP 
site a few weeks ago. Apart from some network settings I did not change a lot 
yet.

Frank


--- In  Jim Jackson <> wrote:
>
> 
> 
> 
> On Thu, 13 Jan 2011, frankvd99 wrote:
> 
> > I have a TS7500 board and trying to control the digital IO lines from 
> > Debian-linux on the sd-card.
> > 
> > When running the script below as user "root" it works fine. When doing 
> > the same thing as user eclipse (or any other user) I get below message.
> > 
> > 
> > #!/bin/sh
> > . /initrd/ts7500.subr
> > #
> > echo "IO value of pin 5:"
> > getdiopin 5
> > #
> > 
> > Response when user root:
> > IO value of pin 5:
> > 1
> > 
> > Response when user eclipse:
> > ts7500ctl: ts7500ctl.c: 771 main: Assertion 'dev/mem !=-1' failed
> > 
> > I've traced this back to the ts7500ctl.c file which is trying to open 
> > /dev/mem, which is not allowed.
> >
> > Is there another way how I can get this done. My goal is to run TS7500 
> > digital IO control from a CGI script in the Apache webserver. Apache does 
> > not allow you to run it as root, so that is not a workaround.
> 
> You need a setuid program - see [1] for an overview of permissions. I 
> believe you are not supposed to make scripts setuid, because of a possible 
> security hole, so you probably need a program "wrapper" for your script[2].
> 
> Jim
> 
> [1] http://www.zzee.com/solutions/linux-permissions.shtml
> [2] http://www.tuxation.com/setuid-on-shell-scripts.html
>




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