exec-shield incompatible with Oracle Linux UEK

[eyespies]

Describe the bug
Running this cookbook on Oracle Linux with UEK fails. According to the Oracle documentation, this feature (exec-shield) has been removed from UEK, including Oracle Linux 6 and 7. Details are available at https://support.oracle.com/epmos/faces/DocumentDisplay?_afrLoop=282729127294508&id=2334296.1&_afrWindowMode=0&_adf.ctrl-state=aqumhm587_4 for anyone (unfortunately) with an Oracle Linux support login.

Expected behavior
The cookbook should execute without error and

Actual behavior

         * sysctl[kernel.exec-shield] action apply


================================================================================
           Error executing action `apply` on resource 'sysctl[kernel.exec-shield]'
           ================================================================================
           
           Mixlib::ShellOut::ShellCommandFailed
           ------------------------------------
           Expected process to exit with [0], but received '255'
           ---- Begin output of sysctl -w "kernel.exec-shield=1" ----
           STDOUT: 
           STDERR: error: "kernel.exec-shield" is an unknown key
           ---- End output of sysctl -w "kernel.exec-shield=1" ----
           Ran sysctl -w "kernel.exec-shield=1" returned 255
           
           Resource Declaration:
           ---------------------
           # In /tmp/kitchen/cache/cookbooks/os-hardening/recipes/sysctl.rb
           
           133:     sysctl_param k do
           134:       value v
           135:     end
           136:   end
           
           Compiled Resource:
           ------------------
           # Declared in /tmp/kitchen/cache/cookbooks/os-hardening/recipes/sysctl.rb:133:in `block in from_file'
           
           sysctl("kernel.exec-shield") do
             action [:apply]
             default_guard_interpreter :default
             declared_type :sysctl_param
             cookbook_name "os-hardening"
             recipe_name "sysctl"
             value "1"
             key "kernel.exec-shield"
           end
           
           System Info:
           ------------
           chef_version=14.8.12
           platform=oracle
           platform_version=6.10
           ruby=ruby 2.5.3p105 (2018-10-18 revision 65156) [x86_64-linux]
           program_name=/opt/chef/bin/chef-client
           executable=/opt/chef/bin/chef-client

Example code

include_recipe 'os-hardening'

OS / Environment
Oracle Linux 6 with UEK. It should not affect Oracle Linux 7 since RHEL platform_family has been filtered for < 7 in the existing code.

Chef Version

[vagrant@standalone-server-nfs-oracle-610  ~] :( chef-client --version
Chef: 14.8.12

Cookbook Version

3.1.0

Additional context
I don't think any is required, but will provide anything requested.

[artem-sidorenko]

Resolved via #235