Re: Query: Real time process

[Sandeep K Sinha <sandeepksinha@xxxxxxxxx>]

On Sun, Mar 22, 2009 at 1:56 PM, Chetan Nanda <chetannanda@xxxxxxxxx> wrote:
>
>
> On Sun, Mar 22, 2009 at 1:48 PM, Sandeep K Sinha <sandeepksinha@xxxxxxxxx>
> wrote:
>>
>> On Sun, Mar 22, 2009 at 1:38 PM, Chetan Nanda <chetannanda@xxxxxxxxx>
>> wrote:
>> > Hi All,
>> >
>> > I am experimenting with real time process on kernel version 2.6.24
>> > (under
>> > UML) and having root privileges.
>> > I have written a simple code as follow:
>> >
>> > /*##############################*/
>> > int main()
>> > {
>> >     pid_t pid;
>> >     struct sched_param param;
>> >     pid = getpid();
>> >     memset((void *)&param, 0 , sizeof(struct sched_param));
>> >     param.sched_priority = 30;
>> >
>> >     /*change the priority to rt*/
>> >     sched_setscheduler(pid,SCHED_FIFO, &param);
>> >
>> >     while(1);
>> > }
>> > /*##############################*/
>> >
>> > On running this program cause system to hangs and this is as per the
>> > real
>> > time task implementation in the kernel.
>> > Which says a rt task with policy equal to 'SCHED_FIFO' will run till it
>> > voluntarily release CPU.
>> >
>> > Is there any way to kill such task? Isn't this kind of behavior
>> > compromising
>> > system security?
>> >
>>
>> AFAIK, No.
>>
>> And as far as the security is concerned, only a super user can run
>> this task. Meaning that the user has the authority to do such things.
>
> Suppose, If kernel is PID Namespace aware, and root user in one namespace
> run this kind of task then, (I think) whole system will come to halt. Is my
> understanding on this correct?
>

I just know of user/kernel space and any such process by root will
definitely cause the system to seize.

>>
>>
>>
>> > ~~
>> > Chetan Nanda
>> >
>>
>>
>>
>> --
>> Regards,
>> Sandeep.
>>
>>
>>
>>
>>
>>
>> “To learn is to change. Education is a process that changes the learner.”
>
>



-- 
Regards,
Sandeep.





 	
“To learn is to change. Education is a process that changes the learner.”

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