Re: uid- task_struct --The results of the code sent by you

[sena]

Hi Robin,

What you say is very reasonable.

I will go bit further into this and come back to you.

What I am going to accomplish is:

At this stage Load Average is collected as a whole.
What I am trying to do is to collect it seperately under respective USERS.

This way load signal(Load average) can be connected to a perticular 
user. Then to user behaviour as well.

Thanks a lot for your time
Sena Seneviratne
Computer Engineering Lab
Sydney University



Robin Holt wrote:

> Telnet and login are always going to be uid 0.  The telnet
> process is handling socket IO and handling telnet escape
> sequences.  When the telnet process is started, the user
> isn't even known to the system.
>
> telnet forks and execs login.  Login does the password
> prompting and establishes a session.  The login process
> needs to stay around to cleanup the session when the user
> logs off.  Once the password is authenticated, login does
> a fork and the child execs the users shell.  They child
> is the first process which actually _SHOULD_ be not
> root.
>
> Everything is as you would expect.  Telnet will accumulate
> nearly no cpu time.  login will accumulate none until
> the user logs off.  These will not be significant in
> process accounting or load average.  You should be able
> to safely ignore them.
>
> Now, back to the original question.  What are you trying
> to accomplish?
>
> Thanks,
> Robin
>
> On Thu, Jan 08, 2004 at 04:16:20AM +1100, sena wrote:
>  
>
> > Hi Robin,
> >
> > (As previously I could not copy to linux-kernel I am sending it again)
> >
> > Thanks for your time.
> >
> > I have loaded the module sent with some changes and got some results.
> >
> > I got 2 people to login remotely using telnet.
> >
> > as herft and as herft1
> >
> > herft runs a small executable called ./myprog.
> >
> > The reseults I got is as follows in var/log/messages
> >
> > Jan 8 03:46:23 sena kernel: Pid 1193 uid 0 euid 0
> > Jan 8 03:46:23 sena kernel: Pid 1220 uid 0 euid 0
> > Jan 8 03:46:23 sena kernel: Pid 1251 uid 0 euid 0--->this is telnet
> > Jan 8 03:46:23 sena kernel: Pid 1252 uid 0 euid 0
> > Jan 8 03:46:23 sena kernel: Pid 1253 uid 500 euid 500 --->this is bash
> > Jan 8 03:46:23 sena kernel: Pid 1381 uid 500 euid 500--->This is exec
> > Jan 8 03:46:23 sena kernel: Pid 1383 uid 0 euid 0---->telnet
> > Jan 8 03:46:23 sena kernel: Pid 1384 uid 0 euid 0
> > Jan 8 03:46:23 sena kernel: Pid 1385 uid 501 euid 501---->This is bash
> > Jan 8 03:46:23 sena kernel: Pid 1417 uid 0 euid 0
> >
> >
> > Then I ps -ale
> >
> > The result is as follows
> > UID PID
> > 100 S 0 1251 638 0 69 0 - 426 do_sel ? 00:00:00 
> > in.telnetd-----------This is telnet
> > 100 S 0 1252 1251 0 69 0 - 599 wait4 ? 00:00:00 login
> > 100 S 500 1253 1252 0 69 0 - 1009 wait4 pts/4 00:00:00-------- bash
> > 000 S 500 1381 1253 0 69 0 - 309 nanosl pts/4 00:00:00----------- myprog
> > 100 S 0 1383 638 0 69 0 - 426 do_sel ? 00:00:00 in.telnetd----------This 
> > is telnet
> > 100 S 0 1384 1383 0 69 0 - 599 wait4 ? 00:00:00 login
> > 100 S 501 1385 1384 0 68 0 - 1009 read_c pts/5 00:00:00--------- bash
> > 100 R 0 1795 1220 0 74 0 - 762 - pts/3 00:00:00 ps
> >
> >
> >
> > I probably got the same thing as yours. This means task_struct uid has 
> > got its owners uids in the processes started through telnet. but telnet 
> > servers uid=0
> >
> > This means either I will have to consider telnet thing as root (though 
> > it is started by the user login)
> >
> > or
> >
> > What do you think Robin?
> >
> >
> > THE CODE:
> > // count_active_tasks.c -
> >
> > #include <linux/sched.h>
> > #include <linux/module.h> // Needed by all modules
> > #include <linux/kernel.h> // Needed for KERN_ALERT
> > #include <linux/init.h> // Needed for the macros
> >
> > #define DRIVER_AUTHOR "Sena Seneviratne/Robin Holt"
> >
> >
> > #define DRIVER_DESC "A sample Test driver"
> >
> > #define _LOOSE_KERNEL_NAMES
> > /* With some combinations of Linux and gcc, tty.h will not compile without
> > _LOOSE_KERNEL_NAMES.
> > */
> > #include <linux/tty.h> /* console_print() interface */
> >
> > static int
> > count_active_tasks_init(void)
> > {
> > struct task_struct *p;
> >
> > read_lock(&tasklist_lock);
> >
> > for_each_task(p) {
> > printk(KERN_EMERG "Pid %d uid %d euid %d\n",
> > p->pid, p->uid, p->euid);
> >
> > //console_print("Hellow");
> >
> > }
> > read_unlock(&tasklist_lock);
> > return 0;
> > }
> >
> > static void count_active_tasks_exit(void)
> > {
> > printk(KERN_ALERT "Goodbye, world 2\n");
> > }
> >
> > module_init(count_active_tasks_init);
> > module_exit(count_active_tasks_exit);
> >
> > MODULE_LICENSE("GPL");
> >
> > MODULE_AUTHOR(DRIVER_AUTHOR); // Robin/sena wrote this module
> > MODULE_DESCRIPTION(DRIVER_DESC); // What does this module do?
> >
> > MODULE_SUPPORTED_DEVICE("dummy testdevice");
> >
> > Thanks
> > Sena Seneviratne
> > Computer Engineering Lab
> > Sydney University
> >    
> -
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