Re: task_struct and uid of a task

[sena <auntvini@sedal.usyd.edu.au>]

Hi Robin,

I have applied this to my local testing code and indendation is looking 
perfectly good.

indent -kr -i8 -psl -npcs -cp9 loadavg.c

Robin Thanks a lot for that.

Sena Seneviratne
Computer engineering Lab
Sydney University
Sydney



Robin Holt wrote:

>On Wed, Dec 31, 2003 at 07:06:52AM +1100, sena wrote:
>
>Sena,
>
>Why don't you pester me about this instead of bothering Rusty.
>
>What are you trying to accomplish?  Please be specific about what
>you are trying to find out and not how you are trying to do it.
>
>Another thing, I would _GREATLY_ appreciate code which has
>decent variable names and good indentation.  Assuming you are
>writing this on a Linux box with a standard development install,
>you should be able to do:
>
>indent -kr -i8 -psl -npcs -cp9 myfile.c
>
>and get very kernel-style code.  Won't fix the variable names, but
>at least braces will be indented.
>
>Thanks,
>Robin Holt
>
>  
>
>>Dear Rusty,
>>
>>Thank you for your previous reply. I feel like you would be able to 
>>assist me.
>>
>>Say a computer has 5 user logins name1(500), name2(501), 
>>name3(502).........name5(504) apart from root. If these 5 people 
>>remotely login and runs there jobs, then the user name of those jobs are 
>>name1,name2 and name3.
>>
>>Say if they use telnet to remotely login then those Tasks will be 
>>started under telnet server as children.
>>
>>As the children inherits uid, euid etc of the parents. That means telnet 
>>is run as root and it inherits uid<500.
>>
>>task_struct has uid and it is updated accordingly.
>>
>>
>>I have built the kernel 2.4.19sena1 successfully but this is my problem. 
>>The problem because child process inherits uid etc if I start any 
>>process through telnet
>>
>>My code is as follows:
>>
>>unsigned long a; //for root uid<500, I am getting this uidArray[0] is 
>>for storing uid (assumed 100 for all <500)
>>unsigned long b; //for 500
>>unsigned long c; //for 501
>>unsigned long d; //for 502
>>unsigned long e; //for 503
>>unsigned long f; // for 504
>>
>>unsigned int uidArray[7];
>>
>>static unsigned long count_active_tasks(void)
>>{
>>   struct task_struct *p;
>>   unsigned long nr = 0;
>>
>>   int s = 0;
>>  
>>   int i=0;
>>   int j=0;
>>   int k=0;
>>   int m=0;
>>
>>   a=b=c=d=e=f=0;
>>  
>>      read_lock(&tasklist_lock);
>>
>>   for_each_task(p)
>>   {
>>       if ((p->state == TASK_RUNNING ||
>>            (p->state & TASK_UNINTERRUPTIBLE)))
>>   {
>>
>>       nr += FIXED_1; //nr total tasks
>>      
>>       if(i==0)
>>       {
>>           uidArray[0] = 100;
>>
>>           if(p->uid < 500)
>>           {
>>          
>>           a += FIXED_1;
>>           }
>>           else
>>           {
>>           uidArray[1] = p->uid;
>>           b += FIXED_1;
>>           k++;
>>           }
>>        k++;
>>       }
>>       else
>>       {
>>          for(j=0; j < k ; j++)
>>          {
>>              
>>           if((j==0)&& (p->uid < 500) && (s==0))
>>           {
>>               a += FIXED_1;
>>               s = 1;
>>               break;
>>           }
>>           else if((uidArray[j] == p->uid) && s==0)
>>           {
>>               if(j==1){
>>               b += FIXED_1;}
>>               if(j==2){
>>               c += FIXED_1;}
>>               if(j==3){
>>               d += FIXED_1;}
>>               if(j==4){
>>               e += FIXED_1;}
>>               if(j==5){
>>               f += FIXED_1;}
>>               s=1;
>>               break;
>>           }
>>           }
>>  
>>           if(s==0)
>>           {
>>
>>           if(k < 6)
>>              {
>>               k++;
>>               j = k-1;
>>               uidArray[j] = p->uid;
>>               if(j==1){
>>               b += FIXED_1;}
>>               if(j==2){
>>               c += FIXED_1;}
>>               if(j==3){
>>               d += FIXED_1;}
>>               if(j==4){
>>               e += FIXED_1;}
>>               if(j==5){
>>               f += FIXED_1;}
>>              }
>>              
>>
>>           }
>>
>>       s=0;
>>         }
>>      
>>       i++;
>>  
>>   }
>>
>>   }
>>          
>>   read_unlock(&tasklist_lock);
>>   return nr;
>>
>>}
>>
>>unsigned long avenrun[6];
>>
>>unsigned long avenrunT;
>>
>>static inline void calc_load(unsigned long ticks)
>>{
>>   unsigned long active_tasks;  /*fixed-point */
>>   static int count = LOAD_FREQ;
>>
>>   count -= ticks;
>>   if (count < 0) {
>>       count += LOAD_FREQ;
>>       active_tasks = count_active_tasks();
>>
>>       CALC_LOAD(avenrunT, EXP_5, active_tasks);
>>       CALC_LOAD(avenrun[0], EXP_5, a);
>>       CALC_LOAD(avenrun[1], EXP_5, b);
>>       CALC_LOAD(avenrun[2], EXP_5, c);
>>       CALC_LOAD(avenrun[3], EXP_5, d);
>>       CALC_LOAD(avenrun[4], EXP_5, e);
>>       CALC_LOAD(avenrun[5], EXP_5, f);
>>      
>>   }
>>}
>>
>>I have updated all the other places(all .h and .c files) to suit this code.
>>
>>And the result is stored in    proc/loadavg as
>>
>>       0.21   0.21   100   0.00     0       0.00      0        0.00     
>>0        0.00     0            0.00        0
>>         T        a 1      uid     b1    500        c 1     501      d1 
>>    502      e1      503          f1         504
>>
>>T- for totall
>>a1- root or uid < 500
>>b1,c1,di etc for uid>=500
>>
>>In this perticular case I have login as root so that uid 100 is seen. 
>>There is no 500 or above. they are all 0.
>>
>>But even if I start login remotely those processors started through 
>>telnet inherits uid <500. Then they will be shown under a1
>>
>>I get uids from task_struct
>>
>>Thanks
>>Sena Seneviratne
>>Computer Engineering Lab
>>School of Electrical and Information Engineering
>>Sydney University
>>
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>>
>
>  
>