55 lines
1.7 KiB
Ruby
55 lines
1.7 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(encoded_message, jwt_secret = secret, issuer: nil, iat_after: nil)
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options = { algorithm: 'HS256' }
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options = options.merge(iss: issuer, verify_iss: true) if issuer.present?
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options = options.merge(verify_iat: true) if iat_after.present?
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decoded_message = JWT.decode(encoded_message, jwt_secret, true, options)
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payload = decoded_message[0]
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if iat_after.present?
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raise JWT::DecodeError, "JWT iat claim is missing" if payload['iat'].blank?
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iat = payload['iat'].to_i
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raise JWT::ExpiredSignature, 'Token has expired' if iat < iat_after.to_i
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end
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decoded_message
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end
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def secret
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strong_memoize(:secret) do
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read_secret(secret_path)
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end
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end
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def read_secret(path)
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Base64.strict_decode64(File.read(path).chomp).tap do |bytes|
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raise "#{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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def write_secret(path = secret_path)
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bytes = SecureRandom.random_bytes(SECRET_LENGTH)
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File.open(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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