Timer_Create for periodic tasks

Jan Kiszka jan.kiszka at siemens.com
Sun May 9 13:23:56 CEST 2021


[re-adding the list]

On 09.05.21 13:06, Marco Barletta wrote:
> Yes, of course.
> I attached "test3.c" that is a basic posix period task ripoff i found on
> the web by Marc Le Douarain. I couldn't test with smokey since at the
> best of my knowledge I realized it doesn't handles periodic tasks with
> timers.
> Then I launched Docker with "docker run -itd --name containerName
> --volume=/usr/xenomai:/usr/xenomai --volume=/[folder with
> proggrams]:/home/test --user 1000:1000 --device=/dev/rtdm:/dev/rtdm
> ubuntu /bin/bash" and then I run the periodic task in the container. It
> just blocks on waitsiginfo. Moreover I want to precise that adding
> --pid=host everything is fine, but it can be just a workaround due to
> security issues. I don't think you're also interesed in the server to
> translate pid in different namespaces, the syscall just fail, is a wrong
> way.
> It would be great to add namespace support, and I could contribute to
> it, although my experience limits.

You could already help with adding the information and test case to
https://gitlab.com/Xenomai/xenomai-hacker-space/-/issues/19 that i just
created.

One note, though, to avoid the illusion of security: You cannot confine
Xenomai by putting it into a namespace. It remains a set of privileged
service that can easily be used to lock up the system. Also, its APIs
are not consistently checked /wrt security loopholes that could be used
for privilege escalation. That's also why you need CAP_SYS_NICE as
caller or have to be in the 'allowed_group'.

However, I would still consider namespace support a valid feature in
order to use containers as deployment tool for Xenomai applications.

Jan

-- 
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Corporate Competence Center Embedded Linux



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