metasploit-framework/plugins/alias.rb

##
# $Id$
# $Revision$
##

require 'rex/ui/text/table'

module Msf

class Plugin::Alias < Msf::Plugin
	class AliasCommandDispatcher
		include Msf::Ui::Console::CommandDispatcher

		attr_reader :aliases
		def initialize(driver)
			super(driver)
			@aliases = {}
		end

		def name
			"Alias"
		end

		@@alias_opts = Rex::Parser::Arguments.new(
			"-h" => [ false, "Help banner."                    ],
			"-c" => [ true, "Clear an alias (* to clear all)."],
			"-f" => [ true,  "Force an alias assignment."      ]
		)
		#
		# Returns the hash of commands supported by this dispatcher.
		#
		def commands # driver.dispatcher_stack[3].commands
			{
				"alias" => "create or view an alias."
	#			"alias_clear" => "clear an alias (or all aliases).",
	#			"alias_force" => "Force an alias (such as to override)"
			}.merge(aliases) # make aliased commands available as commands of their own
		end

		#
		# the main alias command handler
		#
		# usage: alias [options] [name [value]]
		def cmd_alias(*args)
			# we parse args manually instead of using @@alias.opts.parse to handle special cases
			case args.length
			when 0 # print the list of current aliases
				if @aliases.length == 0
					return print_status("No aliases currently defined")
				else
					tbl = Rex::Ui::Text::Table.new(
						'Header'  => "Current Aliases",
						'Prefix'  => "\n",
						'Postfix' => "\n",
						'Columns' => [ '', 'Alias Name', 'Alias Value' ]
					)
					# add 'alias' in front of each row so that the output can be copy pasted into an rc file if desired
					@aliases.each_pair do |key,val|
						tbl << ["alias",key,val]
					end
					return print(tbl.to_s)
				end
			when 1 # display the alias if one matches this name (or help)
				return cmd_alias_help if args[0] == "-h" or args[0] == "--help"
				if @aliases.keys.include?(args[0])
					print_status("\'#{args[0]}\' is aliased to \'#{@aliases[args[0]]}\'")
				else
					print_status("\'#{args[0]}\' is not currently aliased")
				end
			else # let's see if we can assign or clear the alias
				force = false
				clear = false
				# if using -f or -c, they must be the first arg, because -f/-c may also show up in the alias
				# value so we can't do something like if args.include("-f") or delete_if etc
				# we should never have to force and clear simultaneously.
				if args[0] == "-f"
					force = true
					args.shift
				elsif args[0] == "-c"
					clear = true
					args.shift
				end
				name = args.shift
				# alias name can NEVER be certain reserved words like 'alias', add any other reserved words here
				# We prevent the user from naming the alias "alias" cuz they could end up unable to clear the aliases,
				# for example you 'alias -f set unset and then 'alias -f alias sessions', now you're screwed.  The byproduct
				# of this is that it prevents you from aliasing 'alias' to 'alias -f' etc, but that's acceptable
				reserved_words = [/^alias$/i]
				reserved_words.each do |regex|
					if name =~ regex
						print_error "You cannot use #{name} as the name for an alias, sorry"
						return false
					end
				end

				if clear
					# clear all aliases if "*"
					if name == "*"
						@aliases.keys.each do |a|
							deregister_alias(a)
						end
						print_status "Cleared all aliases"
					else # clear the named alias if it exists
						if @aliases.keys.include?(name)
							deregister_alias(name)
							print_status "Cleared alias #{name}"
						else
							print_error("#{name} is not a currently active alias")
						end
					end
					return
				end
				# smash everything that's left together
				value = args.join(" ")
				value.strip!
				# value can NEVER be certain bad words like 'rm -rf /', add any other reserved words here
				# this is basic idiot protection, not meant to be impervious to subversive intentions
				reserved_words = [/^rm +(-rf|-r +-f|-f +-r) +\/.*$/]
				reserved_words.each do |regex|
					if value =~ regex
						print_error "You cannot use #{value} as the value for an alias, sorry"
						return false
					end
				end

				is_valid_alias = is_valid_alias?(name,value)
				#print_good "Alias validity = #{is_valid_alias.to_s}"
				is_sys_cmd = Rex::FileUtils.find_full_path(name)
				is_already_alias = @aliases.keys.include?(name)
				if is_valid_alias and not is_sys_cmd and not is_already_alias
					register_alias(name, value)
				elsif force
					if not is_valid_alias
						print_status "The alias failed validation, but force is set so we allow this.  This is often the case"
						print_status "when for instance 'exploit' is being overridden but msfconsole is not currently in the"
						print_status "exploit context (an exploit is not loaded), or you are overriding a system command"
					end
					register_alias(name, value)
				else
					print_error("#{name} already exists as a system command, use -f to force override") if is_sys_cmd
					print_error("#{name} is already an alias, use -f to force override") if is_already_alias
					if not is_valid_alias and not force
						print_error("\'#{name}\' is not a permitted name or \'#{value}\' is not valid/permitted")
						print_error("It's possible the responding dispatcher isn't loaded yet, try changing to the proper context or using -f to force")
					end
				end
			end
		end

		def cmd_alias_help
			print_line "Usage: alias [options] [name [value]]"
			print_line
			print(@@alias_opts.usage())
		end

		#
		# Tab completion for the alias command
		#
		def cmd_alias_tabs(str, words)
			if words.length <= 1
				#puts "1 word or less"
				return @@alias_opts.fmt.keys + tab_complete_aliases_and_commands
			else
				#puts "more than 1 word"
				return tab_complete_aliases_and_commands
			end
		end

		private
		#
		# do everything needed to add an alias of +name+ having the value +value+
		#
		def register_alias(name, value)
			#TODO:  begin rescue?
			#TODO:  security concerns since we are using eval

			# define some class instance methods
			self.class_eval do
				# define a class instance method that will respond for the alias
				define_method "cmd_#{name}" do |*args|
					# just replace the alias w/the alias' value and run that
					driver.run_single("#{value} #{args.join(' ')}")
				end
				# define a class instance method that will tab complete the aliased command
				# we just proxy to the top-level tab complete function and let them handle it
				define_method "cmd_#{name}_tabs" do |str, words|
					# we need to repair the tab complete string/words and pass back
					# replace alias name with the root alias value
					value_words = value.split(/[\s\t\n]+/) # in case value is e.g. 'sessions -l'
					# valwords is now [sessions,-l]
					words[0] = value_words[0]
					# words[0] is now 'sessions' (was 'sue')
					value_words.shift # valwords is now ['-l']
					# insert any remaining parts of value and rebuild the line
					line = words.join(" ") + " " + value_words.join(" ") + " " + str

					#print_good "passing (#{line.strip}) back to tab_complete"
					# clear current tab_words
					driver.tab_words = []
					driver.tab_complete(line.strip)
				end
				# add a cmd_#{name}_help method
				define_method "cmd_#{name}_help" do |*args|
					driver.run_single("help #{value}")
				end
			end
			# add the alias to the list
			@aliases[name] = value
		end

		#
		# do everything required to remove an alias of name +name+
		#
		def deregister_alias(name)
			self.class_eval do
				# remove the class methods we created when the alias was registered
				remove_method("cmd_#{name}")
				remove_method("cmd_#{name}_tabs")
				remove_method("cmd_#{name}_help")
			end
			# remove the alias from the list of active aliases
			@aliases.delete(name)
		end

		#
		# Validate a proposed alias with the +name+ and having the value +value+
		#
		def is_valid_alias?(name,value)
			#print_good "Assessing validay for #{name} and #{value}"
			# we validate two things, the name and the value

			### name
			# we don't check if this alias name exists or if it's a console command already etc as -f can override
			# that so those need to be checked externally, we pretty much just check to see if the name is sane
			name.strip!
			bad_words = [/\*/] # add any additional "bad word" regexes here
			bad_words.each do |regex|
				# don't mess around, just return false in this case, prevents wasted processing
				return false if name =~ regex
			end

			### value
			# value is considered valid if it's a ref to a valid console cmd, a system executable, or an existing
			# alias AND isn't a "bad word"
			# Here we check for "bad words" to avoid for the value...value would have to NOT match these regexes
			# this is just basic idiot protection
			value.strip!
			bad_words = [/^msfconsole$/]
			bad_words.each do |regex|
				# don't mess around, just return false if we match
				return false if value =~ regex
			end

			# we're only gonna validate the first part of the cmd, e.g. just ls from "ls -lh"
			value = value.split(" ").first
			if @aliases.keys.include?(value)
				return true
			else
				[value, value+".exe"].each do |cmd|
					if Rex::FileUtils.find_full_path(cmd)
						return true
					end
				end
			end

			# gather all the current commands the driver's dispatcher's have & check 'em
			driver.dispatcher_stack.each do |dispatcher|
				next unless dispatcher.respond_to?(:commands)
				next if (dispatcher.commands.nil?)
				next if (dispatcher.commands.length == 0)

				if dispatcher.respond_to?("cmd_#{value.split(" ").first}")
					#print_status "Dispatcher (#{dispatcher.name}) responds to cmd_#{value.split(" ").first}"
					return true
				else
					#print_status "Dispatcher (#{dispatcher.name}) does not respond to cmd_#{value.split(" ").first}"
				end
			end

			return false
		end

		#
		# Provide tab completion list for aliases and commands
		#
		def tab_complete_aliases_and_commands
			items = []
			# gather all the current commands the driver's dispatcher's have
			driver.dispatcher_stack.each do |dispatcher|
				next unless dispatcher.respond_to?(:commands)
				next if (dispatcher.commands.nil? or dispatcher.commands.length == 0)
				items << dispatcher.commands.keys
			end
			# add all the current aliases to the list
			items.concat(@aliases.keys)
			return items
		end

	end # end AliasCommandDispatcher class

	#
	# The constructor is called when an instance of the plugin is created.  The
	# framework instance that the plugin is being associated with is passed in
	# the framework parameter.  Plugins should call the parent constructor when
	# inheriting from Msf::Plugin to ensure that the framework attribute on
	# their instance gets set.
	#
	def initialize(framework, opts)
		super

		## Register the commands above
		add_console_dispatcher(AliasCommandDispatcher)
	end


	#
	# The cleanup routine for plugins gives them a chance to undo any actions
	# they may have done to the framework.  For instance, if a console
	# dispatcher was added, then it should be removed in the cleanup routine.
	#
	def cleanup
		# If we had previously registered a console dispatcher with the console,
		# deregister it now.
		remove_console_dispatcher('Alias')

		# we don't need to remove class methods we added because they were added to
		# AliasCommandDispatcher class
	end

	#
	# This method returns a short, friendly name for the plugin.
	#
	def name
		"alias"
	end

	#
	# This method returns a brief description of the plugin.  It should be no
	# more than 60 characters, but there are no hard limits.
	#
	def desc
		"Adds the ability to alias console commands"
	end

end ## End Plugin Class
end ## End Module