Land #11050, Add protection checks to Msf::Post::Linux::Kernel lib

lib/msf/core/post/linux/kernel.rb

@@ -123,6 +123,18 @@ module Kernel
     raise 'Could not determine ASLR status'
   end
 
+  #
+  # Returns true if Exec-Shield is enabled
+  #
+  # @return [Boolean]
+  #
+  def exec_shield_enabled?
+    exec_shield = cmd_exec('cat /proc/sys/kernel/exec-shield').to_s.strip
+    (exec_shield.eql?('1') || exec_shield.eql?('2'))
+  rescue
+    raise 'Could not determine exec-shield status'
+  end
+
   #
   # Returns true if unprivileged bpf is disabled
   #
@@ -169,6 +181,24 @@ module Kernel
     raise 'Could not determine system mmap_min_addr'
   end
 
+  #
+  # Returns true if grsecurity is installed
+  #
+  def grsec_installed?
+    cmd_exec('test -c /dev/grsec && echo true').to_s.strip.include? 'true'
+  rescue
+    raise 'Could not determine grsecurity status'
+  end
+
+  #
+  # Returns true if PaX is installed
+  #
+  def pax_installed?
+    cmd_exec('test -x /sbin/paxctl && echo true').to_s.strip.include? 'true'
+  rescue
+    raise 'Could not determine PaX status'
+  end
+
   #
   # Returns true if SELinux is installed
   #