I wrote a small C utility called killSPR to kill the following processes on my RHEL box. The idea is for anyone who logs into this linux box to be able to use this utility to kill the below mentioned processes (which doesn't work - explained below).
cadmn@rhel /tmp > ps -eaf | grep -v grep | grep " SPR "
cadmn 5822 5821 99 17:19 ? 00:33:13 SPR 4 cadmn
cadmn 10466 10465 99 17:25 ? 00:26:34 SPR 4 cadmn
cadmn 13431 13430 99 17:32 ? 00:19:55 SPR 4 cadmn
cadmn 17320 17319 99 17:39 ? 00:13:04 SPR 4 cadmn
cadmn 20589 20588 99 16:50 ? 01:01:30 SPR 4 cadmn
cadmn 22084 22083 99 17:45 ? 00:06:34 SPR 4 cadmn
cadmn@rhel /tmp >
This utility is owned by the user cadmn (under which these processes run) and has the setuid flag set on it (shown below).
cadmn@rhel /tmp > ls -l killSPR
-rwsr-xr-x 1 cadmn cusers 9925 Dec 17 17:51 killSPR
cadmn@rhel /tmp >
The C code is given below:
/*
* Program Name: killSPR.c
* Description: A simple program that kills all SPR processes that
* run as user cadmn
*/
#include <stdio.h>
int main()
{
char *input;
printf("Before you proceed, find out under which ID I'm running. Hit enter when you are done...");
fgets(input, 2, stdin);
const char *killCmd = "kill -9 $(ps -eaf | grep -v grep | grep \" SPR \" | awk '{print $2}')";
system(killCmd);
return 0;
}
A user (pmn) different from cadmn tries to kill the above-mentioned processes with this utility and fails (shown below):
pmn@rhel /tmp > ./killSPR
Before you proceed, find out under which ID I'm running. Hit enter when you are done...
sh: line 0: kill: (5822) - Operation not permitted
sh: line 0: kill: (10466) - Operation not permitted
sh: line 0: kill: (13431) - Operation not permitted
sh: line 0: kill: (17320) - Operation not permitted
sh: line 0: kill: (20589) - Operation not permitted
sh: line 0: kill: (22084) - Operation not permitted
pmn@rhel /tmp >
While the user waits to hit enter above, the process killSPR is inspected and is seen to be running as the user cadmn (shown below) despite which killSPR is unable to terminate the processes.
cadmn@rhel /tmp > ps -eaf | grep -v grep | grep killSPR
cadmn 24851 22918 0 17:51 pts/36 00:00:00 ./killSPR
cadmn@rhel /tmp >
BTW, none of the main partitions have any nosuid on them
pmn@rhel /tmp > mount | grep nosuid
pmn@rhel /tmp >
The setuid flag on the executable doesn't seem to have the desired effect. What am I missing here? Have I misunderstood how setuid works?