122 lines
		
	
	
		
			3.0 KiB
		
	
	
	
		
			Ruby
		
	
	
	
			
		
		
	
	
			122 lines
		
	
	
		
			3.0 KiB
		
	
	
	
		
			Ruby
		
	
	
	
# frozen_string_literal: true
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module Gitlab
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  class EncryptedConfiguration
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    delegate :[], :fetch, to: :config
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    delegate_missing_to :options
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    attr_reader :content_path, :key, :previous_keys
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    CIPHER = "aes-256-gcm"
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    SALT = "GitLabEncryptedConfigSalt"
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    class MissingKeyError < RuntimeError
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      def initialize(msg = "Missing encryption key to encrypt/decrypt file with.")
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        super
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      end
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    end
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    class InvalidConfigError < RuntimeError
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      def initialize(msg = "Content was not a valid yml config file")
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        super
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      end
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    end
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    def self.generate_key(base_key)
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      # Because the salt is static, we want uniqueness to be coming from the base_key
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      # Error if the base_key is empty or suspiciously short
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      raise 'Base key too small' if base_key.blank? || base_key.length < 16
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      ActiveSupport::KeyGenerator.new(base_key).generate_key(SALT, ActiveSupport::MessageEncryptor.key_len(CIPHER))
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    end
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    def initialize(content_path: nil, base_key: nil, previous_keys: [])
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      @content_path = Pathname.new(content_path).yield_self { |path| path.symlink? ? path.realpath : path } if content_path
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      @key = self.class.generate_key(base_key) if base_key
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      @previous_keys = previous_keys
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    end
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    def active?
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      content_path&.exist?
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    end
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    def read
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      if active?
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        decrypt(content_path.binread)
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      else
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        ""
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      end
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    end
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    def write(contents)
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      # ensure contents are valid to deserialize before write
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      deserialize(contents)
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      temp_file = Tempfile.new(File.basename(content_path), File.dirname(content_path))
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      File.open(temp_file.path, 'wb') do |file|
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        file.write(encrypt(contents))
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      end
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      FileUtils.mv(temp_file.path, content_path)
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    ensure
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      temp_file&.unlink
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    end
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    def config
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      return @config if @config
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      contents = deserialize(read)
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      raise InvalidConfigError unless contents.is_a?(Hash)
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      @config = contents.deep_symbolize_keys
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    end
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    def change(&block)
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      writing(read, &block)
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    end
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    private
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    def writing(contents)
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      updated_contents = yield contents
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      write(updated_contents) if updated_contents != contents
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    end
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    def encrypt(contents)
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      handle_missing_key!
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      encryptor.encrypt_and_sign(contents)
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    end
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    def decrypt(contents)
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      handle_missing_key!
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      encryptor.decrypt_and_verify(contents)
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    end
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    def encryptor
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      return @encryptor if @encryptor
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      @encryptor = ActiveSupport::MessageEncryptor.new(key, cipher: CIPHER)
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      # Allow fallback to previous keys
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      @previous_keys.each do |key|
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        @encryptor.rotate(self.class.generate_key(key))
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      end
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      @encryptor
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    end
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    def options
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      # Allows top level keys to be referenced using dot syntax
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      @options ||= ActiveSupport::InheritableOptions.new(config)
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    end
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    def deserialize(contents)
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      YAML.safe_load(contents, permitted_classes: [Symbol]).presence || {}
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    end
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    def handle_missing_key!
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      raise MissingKeyError if @key.nil?
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    end
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  end
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end
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