92 lines
2.6 KiB
Ruby
92 lines
2.6 KiB
Ruby
# frozen_string_literal: true
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module Atlassian
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module JiraConnect
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module Jwt
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# See documentation about Atlassian asymmetric JWT verification:
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# https://developer.atlassian.com/cloud/jira/platform/understanding-jwt-for-connect-apps/#verifying-a-asymmetric-jwt-token-for-install-callbacks
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class Asymmetric
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include Gitlab::Utils::StrongMemoize
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KeyFetchError = Class.new(StandardError)
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ALGORITHM = 'RS256'
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DEFAULT_PUBLIC_KEY_CDN_URL = 'https://connect-install-keys.atlassian.com'
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PROXY_PUBLIC_KEY_PATH = '/-/jira_connect/public_keys'
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UUID4_REGEX = /\A[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\z/.freeze
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def initialize(token, verification_claims)
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@token = token
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@verification_claims = verification_claims
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end
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def valid?
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claims.present? && claims['qsh'] == verification_qsh
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end
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def iss_claim
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return unless claims
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claims['iss']
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end
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private
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def claims
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strong_memoize(:claims) do
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_, jwt_headers = decode_token
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public_key = retrieve_public_key(jwt_headers['kid'])
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decoded_claims(public_key)
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rescue JWT::DecodeError, OpenSSL::PKey::PKeyError, KeyFetchError
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end
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end
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def decoded_claims(public_key)
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decode_token(
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public_key,
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true,
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**relevant_claims,
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verify_aud: true,
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verify_iss: true,
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algorithm: ALGORITHM
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).first
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end
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def decode_token(key = nil, verify = false, **claims)
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Atlassian::Jwt.decode(@token, key, verify, **claims)
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end
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def retrieve_public_key(key_id)
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raise KeyFetchError unless UUID4_REGEX.match?(key_id)
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public_key = Gitlab::HTTP.try_get("#{public_key_cdn_url}/#{key_id}").try(:body)
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raise KeyFetchError if public_key.blank?
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OpenSSL::PKey.read(public_key)
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end
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def relevant_claims
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@verification_claims.slice(:aud, :iss)
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end
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def verification_qsh
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@verification_claims[:qsh]
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end
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def public_key_cdn_url
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public_key_cdn_url_setting.presence || DEFAULT_PUBLIC_KEY_CDN_URL
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end
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def public_key_cdn_url_setting
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@public_key_cdn_url_setting ||=
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if Gitlab::CurrentSettings.jira_connect_proxy_url
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Gitlab::Utils.append_path(Gitlab::CurrentSettings.jira_connect_proxy_url, PROXY_PUBLIC_KEY_PATH)
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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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end
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