mysuid.c

/*
 * setuid example by [email protected]
 * 
 * $gcc -o mysuid.exe mysuid.c
 * $sudo chown root.root mysuid.exe
 * $sudo chmod 4755 mysuid.exe
 *
 * Note: must be run in a filesystem mounted with no 'nosuid'
 * ex: /tmp
 *
 */


#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

int main(void)
{

   uid_t current_uid;
   printf("RUID=%d, EUID=%d, GID=%d\n", getuid(), geteuid(), getgid());
   system("cat /etc/shadow");
   if (setuid(0)){
      perror("setuid");
      return 1;
   }
   printf("RUID=%d, EUID=%d, GID=%d\n", getuid(), geteuid(), getgid());
   system("cat /etc/shadow");
   setuid(current_uid);
   printf("RUID=%d, EUID=%d, GID=%d\n", getuid(), geteuid(), getgid());
   system("cat /etc/shadow");
   return 0;
}