What Is KernelCare?

Tux the Penguin with Hotpatching (KernelCare)The concept of ‘Kernel hotpatching’, sometimes called live patching, was introduced to the Linux community around 2008. Soon after groups began developing differing implementations of the concept. KernelCare, one of the more popular implementations, was originally released in March 2014 by Cloud Linux, Inc.

So, what does hot patching do? (Or: Why do I want KernelCare?)

The basic concept of Linux kernel hot patching is pretty much the same not matter what it’s called. The goal is to only update the changes rather than the whole Kernel – which normally requires a reboot. It’s much harder than it sounds though since kernel updates come as complete packages and the system is running.

Imagine trying to do an oil change on your car while driving at highway speeds; that’s kernel hot patching in a nutshell.

With a KernelCare enabled kernel updates can be processed and then applied selectively to a running server. This can mean not needing to reboot for much longer than you would normally require to stay secure.

How do I check if I have KernelCare and is it working? (Or: Checking KernelCare version)

The best way to check if your server is running with KernelCare is to look for its main CLI tool. You can do this with the following linux command:

which kcarectl

If the CLI tool is found on the server you will see output like the following, or something very similar.

# which kcarectl
/usr/bin/kcarectl

If the CLI tool is not installed you will see the following:

# which kcarectl
#
When using the Linux `which` command you will get no results if the executable is not found. In this case that means KernelCare is likely not active or installed on the server.

Assuming the test above was successful, you’ll now want to check the status of KernelCare. This will help you determine if KernelCare is active and what the effective version is. You can do this with the following command:

/usr/bin/kcarectl --info

The results will look similar to the following:

[root@host ~]# /usr/bin/kcarectl –info
kpatch-state: patch is applied
kpatch-for: Linux version 3.10.0-327.36.3.el7.x86_64 (builder@kbuilder.dev.centos.org) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-4) (GCC) ) #1 SMP Mon Oct 24 16:09:20 UTC 2016
kpatch-build-time: Mon Nov 7 08:20:19 2016
kpatch-description: 2;3.10.0-327.36.3.el7.x86_64

As you can see the output provides various details about the KernelCare status. Looking at the kpatch-state we can see that hot patching is working and enabled.

Information on CVE-2015-5154

Overview

Information on CVE-2015-5154 was made public on July 27, 2015. The vulnerability is in QEMU, a generic and open source machine emulator and virtualizer that is utilized by Xen, KVM, and other modern hypervisors / virtualization platforms.

Impact

Specifically a flaw with how QEMU’s IDE subsystem handles buffer access while processing certain ATAPI commands, exploitation can allow for the execution of arbitrary code on the host with the privileges of the host’s QEMU process corresponding to the guest.

Summary

  • Made public on July 27, 2015
  • This flaw exploits QEMU, a generic and open source machine emulator.
  • Allows for an attacker to execute arbitrary code outside of their own virtual machine.

Resolution

A patch is available, and Liquid Web’s Heroic Support has proactively scheduled a reboot to patch all affected servers.

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Error: Login without a password is forbidden by configuration (see AllowNoPassword) [SOLVED]

This error relates to logging into phpMyAdmin, an open source tool used for the administration of MySQL.

Once in awhile, perhaps on a Development server, MySQL won’t be setup with a root password. The aforementioned configuration is generally thought of as against best practices however, if it is what you’re dealing with, then it could also interfere with phpMyAdmin.

Pre-Flight Check

  • These instructions are intended specifically for solving the error: Login without a password is forbidden by configuration (see AllowNoPassword).
  • I’ll be working from a Liquid Web Self Managed Ubuntu 15.04 server, and I’ll be logged in as root.

The Error

The error will read “Login without a password is forbidden by configuration (see AllowNoPassword)” as shown below.

Error Login without a password is forbidden by configuration (see AllowNoPassword) [SOLVED]

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Reminder: Fedora 20 Now End-of-Life (EOL)

Three versions of the Fedora OS are always kept active, at any given time, by The Fedora Project. These would be: 1. the current release, 2. the release before the current release, and 3. a new release that is in development. Last month saw the launch of Fedora 22 and Fedora 23 is in development, thus the time of Fedora 20 is over.

Fedora 20 has reached end-of-life as of June 23, 2015. This means that no additional security updates will be available from here forward.

Suggested Action

As of today, June 24, 2015, we suggest doing one of the following:

  • Upgrade to Fedora 21.
  • or Upgrade to Fedora 22.

Continue reading “Reminder: Fedora 20 Now End-of-Life (EOL)”

How to Stop and Disable Firewalld on Fedora 22

It is highly recommended that you have another firewall protecting your network or server before, or immediately after, disabling firewalld.

Pre-Flight Check

  • These instructions are intended specifically for stopping and disabling firewalld on Fedora 22.
  • I’ll be working from a Liquid Web Self Managed Fedora 22 server, and I’ll be logged in as root.

Continue reading “How to Stop and Disable Firewalld on Fedora 22”