Class: Kubeseal

Inherits:
Object
  • Object
show all
Defined in:
lib/kubeseal.rb,
lib/kubeseal/version.rb

Defined Under Namespace

Classes: CLI

Constant Summary collapse

DEFAULT_KEY_FETCHER = 
lambda do |_|
  raise NotImplementedError, "no cluster key-fetcher passed"
end
VERSION = 
"0.1.6"

Instance Method Summary collapse

Constructor Details

#initialize(key_fetcher: nil, resealer: nil) ⇒ Kubeseal

Returns a new instance of Kubeseal.



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# File 'lib/kubeseal.rb', line 16

def initialize(key_fetcher: nil, resealer: nil)
  @cluster_sealer_key_fetcher = key_fetcher || DEFAULT_KEY_FETCHER
  @cluster_sealer_resealer = resealer
end

Instance Method Details

#cluster_sealer_private_keys ⇒ Object 



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# File 'lib/kubeseal.rb', line 25

def cluster_sealer_private_keys
  @cluster_sealer_private_keys ||= @cluster_sealer_key_fetcher.call(:private_keys)
end

#cluster_sealer_public_key ⇒ Object 



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# File 'lib/kubeseal.rb', line 21

def cluster_sealer_public_key
  @cluster_sealer_public_key ||= @cluster_sealer_key_fetcher.call(:public_key)
end

#reseal ⇒ Object 



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# File 'lib/kubeseal.rb', line 170

def reseal(...)
  if @cluster_sealer_resealer
    reseal_serverside(...)
  else
    reseal_clientside(...)
  end
end

#reseal_clientside(ciphertext, scope_label) ⇒ Object 



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# File 'lib/kubeseal.rb', line 178

def reseal_clientside(ciphertext, scope_label)
  plaintext = unseal(ciphertext, scope_label)
  seal(plaintext, scope_label)
end

#reseal_serverside(ciphertext, scope_label) ⇒ Object 



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# File 'lib/kubeseal.rb', line 183

def reseal_serverside(ciphertext, scope_label)
  rc_namespace, rc_name, scope =
    case scope_label.split('/', 2)
    in []
      ["dummy", "dummy", :"cluster-wide"]
    in [ns]
      [ns, "dummy", :"namespace-wide"]
    in [ns, name]
      [ns, name, :strict]
    end

  rc = build_sealed_secret_rc(
    rc_namespace,
    rc_name,
    'Opaque',
    armor({'dummy' => ciphertext}, strict: true)
  )
  rc = patch_with_scope(rc, scope)

  resealed_rc = reseal_wrapped_serverside(rc)

  Base64.decode64(resealed_rc.dig('spec', 'encryptedData', 'dummy'))
end

#reseal_wrapped_serverside(sealed_secret_rc) ⇒ Object 



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# File 'lib/kubeseal.rb', line 207

def reseal_wrapped_serverside(sealed_secret_rc)
  YAML.load(@cluster_sealer_resealer.call(sealed_secret_rc.to_yaml))
end

#seal(plaintext, scope_label) ⇒ Object 



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# File 'lib/kubeseal.rb', line 98

def seal(plaintext, scope_label)
  cs_pubkey = self.cluster_sealer_public_key

  session_key = SecureRandom.bytes(32)

  session_key_enc =
    cs_pubkey.public_encrypt_oaep(
      session_key,
      scope_label,
      OpenSSL::Digest::SHA256
    )

  aed_cipher = OpenSSL::Cipher.new("AES-256-GCM").encrypt
  aed_cipher.key = session_key
  aed_cipher.iv = AED_IV
  aed_cipher.auth_data = ""

  payload_enc =
    aed_cipher.update(plaintext) +
    aed_cipher.final +
    aed_cipher.auth_tag

  ciphertext_parts = [
    session_key_enc.length,
    session_key_enc,
    payload_enc
  ]

  ciphertext_parts.pack('S>A*A*')
end

#seal_and_wrap(secret_rc, scope: :strict) ⇒ Object 



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# File 'lib/kubeseal.rb', line 32

def seal_and_wrap(secret_rc, scope: :strict)
  rc_name = secret_rc.dig('metadata', 'name')
  rc_namespace = secret_rc.dig('metadata', 'namespace')
  rc_type = secret_rc['type'] || 'Opaque'
  scope_label = label_for(scope, rc_namespace, rc_name)

  raw_data =
    if secret_rc.has_key?('data')
      unarmor(secret_rc['data'])
    elsif secret_rc.has_key?('stringData')
      secret_rc['stringData']
    else
      {}
    end

  encrypted_data = raw_data.map do |key, plaintext|
    ciphertext = seal(plaintext, scope_label)
    [key, ciphertext]
  end.to_h

  secret_type = secret_rc['type'] || 'Opaque'

  sealed_secret_rc =
    build_sealed_secret_rc(
      rc_namespace,
      rc_name,
      secret_type,
      armor(encrypted_data)
    )

  patch_with_scope(sealed_secret_rc, scope)
end

#unseal(ciphertext, scope_label) ⇒ Object 



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# File 'lib/kubeseal.rb', line 129

def unseal(ciphertext, scope_label)
  cs_privkeys_to_try = self.cluster_sealer_private_keys.dup

  session_key_enc_len, ciphertext = ciphertext.unpack('S>A*')
  session_key_enc, ciphertext = ciphertext.unpack("A#{session_key_enc_len}A*")

  session_key = nil
  until session_key or cs_privkeys_to_try.empty?
    begin
      try_privkey = cs_privkeys_to_try.shift
      session_key = try_privkey.private_decrypt_oaep(
        session_key_enc,
        scope_label,
        OpenSSL::Digest::SHA256
      )
    rescue OpenSSL::PKey::RSAError => e
    end
  end

  unless session_key
    raise RuntimeError, "no keys from cluster were applicable to decrypting payload"
  end

  aed_decipher = OpenSSL::Cipher.new("AES-256-GCM").decrypt
  aed_decipher.key = session_key
  aed_decipher.iv = AED_IV

  auth_tag_len = 16
  auth_tag   = ciphertext[-auth_tag_len .. -1]
  ciphertext = ciphertext[0 ... -auth_tag_len]

  aed_decipher.auth_tag = auth_tag
  aed_decipher.auth_data = ""

  plaintext =
    aed_decipher.update(ciphertext) +
    aed_decipher.final

  plaintext
end

#unwrap_and_unseal(sealed_secret_rc, armor: true) ⇒ Object 



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# File 'lib/kubeseal.rb', line 65

def unwrap_and_unseal(sealed_secret_rc, armor: true)
  rc_name = sealed_secret_rc.dig('metadata', 'name')
  rc_namespace = sealed_secret_rc.dig('metadata', 'namespace')
  rc_type = sealed_secret_rc['type'] || 'Opaque'

  scope = scope_from_annotations(sealed_secret_rc.dig('metadata', 'annotations'))
  scope_label = label_for(scope, rc_namespace, rc_name)

  # decode data if encoded
  encrypted_data = unarmor(sealed_secret_rc.dig('spec', 'encryptedData'))

  string_data = encrypted_data.map do |key, ciphertext|
    plaintext = unseal(ciphertext, scope_label)
    [key, plaintext]
  end.to_h

  merge_part =
    if armor
      {'data' => armor(string_data)}
    else
      {'stringData' => string_data}
    end

  secret_type = sealed_secret_rc.dig('spec', 'template', 'type') || 'Opaque'

  build_secret_rc(
    rc_namespace,
    rc_name,
    secret_type,
    merge_part
  )
end