43 lines
		
	
	
		
			1.2 KiB
		
	
	
	
		
			Ruby
		
	
	
	
			
		
		
	
	
			43 lines
		
	
	
		
			1.2 KiB
		
	
	
	
		
			Ruby
		
	
	
	
# frozen_string_literal: true
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module Gitlab
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  module JwtAuthenticatable
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    # Supposedly the effective key size for HMAC-SHA256 is 256 bits, i.e. 32
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    # bytes https://tools.ietf.org/html/rfc4868#section-2.6
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    SECRET_LENGTH = 32
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    def self.included(base)
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      base.extend(ClassMethods)
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    end
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    module ClassMethods
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      include Gitlab::Utils::StrongMemoize
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      def decode_jwt_for_issuer(issuer, encoded_message)
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        JWT.decode(
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          encoded_message,
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          secret,
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          true,
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          { iss: issuer, verify_iss: true, algorithm: 'HS256' }
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        )
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      end
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      def secret
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        strong_memoize(:secret) do
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          Base64.strict_decode64(File.read(secret_path).chomp).tap do |bytes|
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            raise "#{secret_path} does not contain #{SECRET_LENGTH} bytes" if bytes.length != SECRET_LENGTH
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          end
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        end
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      end
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      def write_secret
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        bytes = SecureRandom.random_bytes(SECRET_LENGTH)
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        File.open(secret_path, 'w:BINARY', 0600) do |f|
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          f.chmod(0600) # If the file already existed, the '0600' passed to 'open' above was a no-op.
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          f.write(Base64.strict_encode64(bytes))
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        end
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      end
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    end
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  end
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end
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