Table of Contents

1. Challenge

   Enable kernel dumps.

   Note: The hypervisor used by EC2 prevents kdump from being engaged. Forcing a kernel crash will simply prevent you from logging back in for 3-4 miniutes. No crash will be present in /var/crash.

   ---

   Start and enable the kdump service:

   systemctl start kdump && systemctl enable kdump
   

   You'll notice kdump doesn't start. Install necessary packages:

   yum --enablerepo=rhel-7-server-rhui-debug-rpms install -y kexec-tools crash kernel-debug kernel-debuginfo-$(uname -r)
   

   Modify /etc/default/grub to set crash memory to 128M.

   Install the new Grub config:

   grub2-mkconfig -o /boot/grub2/grub.cfg
   

2. Challenge

   Permit cloud_user to run the example.stp via SystemTap.

   Install SystemTap:

   yum install -y systemtap kernel-devel-$(uname -r)
   

   Run the example script: /root/example.stp

   stap /root/example.stp
   

   Compile the script as a module:

   stap -p 4 -v -m stap_example example.stp
   

   Create a systemtap directory for the module:

   mkdir /lib/modules/$(uname -r)/systemtap
   

   Move the module into the new directory:

   mv stap_example.ko /lib/modules/`uname -r`/systemtap/
   

   Run the module:

   staprun stap_example
   

   Add cloud_user to the stapusr group:

   usermod -aG stapusr cloud_user
   

   Verify cloud_user can run the module:

   runuser -l cloud_user -c 'staprun stap_example'