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Frederik Bayart | 25 Apr 2012 12:28

Xenomai: binding failed: Operation not permitted.

Hallo,

We are switching from linux 2.6.30.8 with xenomai 2.4.10  to linux 2.6.38.8 with xenomai 2.6.0 (stable release) on debian lenny.

In our daemon (with real pid root), we are setting effective pid and gid to 1000 and are calling popen to execute a shell command.
The popen succeeds, but when I try to read the output with fgets, I get the error :

Xenomai: binding failed: Operation not permitted.

I verified that the effective user for both commands is the same.

This was working on xenomai 2.4.10
I added the user with pid 1000 already to the xenomai group but this doesn't work.

Does anyone know what the problem could be ?


Frederik

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Gilles Chanteperdrix | 25 Apr 2012 12:43
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Re: Xenomai: binding failed: Operation not permitted.

On 04/25/2012 12:28 PM, Frederik Bayart wrote:
> Hallo,
> 
> We are switching from linux 2.6.30.8 with xenomai 2.4.10  to linux 2.6.38.8
> with xenomai 2.6.0 (stable release) on debian lenny.
> 
> In our daemon (with real pid root), we are setting effective pid and gid to
> 1000 and are calling popen to execute a shell command.
> The popen succeeds, but when I try to read the output with fgets, I get the
> error :
> 
> Xenomai: binding failed: Operation not permitted.
> 
> I verified that the effective user for both commands is the same.
> 
> This was working on xenomai 2.4.10
> I added the user with pid 1000 already to the xenomai group but this
> doesn't work.
> 
> Does anyone know what the problem could be ?

Quite frankly, the description is a bit vague. For instance, the
"binding failed: operation not permitted" message should happens as a
result of starting a program, or as a result of popen, not when calling
fgets. Anyway, please try and reduce the bug to a simple and minimal
test case which still causes the bug, and post the code here. A piece of
code is worth a thousand words, and this exercise may help you identify
which piece of the puzzle causes the bug.

--

-- 
                                                                Gilles.
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Gilles Chanteperdrix | 29 Apr 2012 17:56
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Re: Xenomai: binding failed: Operation not permitted.

On 04/25/2012 12:28 PM, Frederik Bayart wrote:
> Hallo,
> 
> We are switching from linux 2.6.30.8 with xenomai 2.4.10  to linux 2.6.38.8
> with xenomai 2.6.0 (stable release) on debian lenny.

If you are concerned with security (which seems to be the case since you
want to avoid running real-time programs as root):
- you should note that debian lenny is no longer maintained for security
update (since february actually), so, an upgrade to squeeze is
recommended. Chances are that it is possible to become root when running
as an ordinary user on a lenny system without too much trouble.
- it is entirely possible that it is possible to become root abusing
xenomai interfaces, xenomai interfaces are not implemented with security
in mind.

> 
> In our daemon (with real pid root), we are setting effective pid and gid to
> 1000 and are calling popen to execute a shell command.
> The popen succeeds, but when I try to read the output with fgets, I get the
> error :
> 
> Xenomai: binding failed: Operation not permitted.
> 
> I verified that the effective user for both commands is the same.
> 
> This was working on xenomai 2.4.10
> I added the user with pid 1000 already to the xenomai group but this
> doesn't work.

That is not enough, you should also do what is said here:
http://www.xenomai.org/index.php/Non-root_RT

--

-- 
                                                                Gilles.
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