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module Gitlab
# The +otp_key_base+ param is used to encrypt the User#otp_secret attribute.
#
# When +otp_key_base+ is changed, it invalidates the current encrypted values
# of User#otp_secret. This class can be used to decrypt all the values with
# the old key, encrypt them with the new key, and and update the database
# with the new values.
#
# For persistence between runs, a CSV file is used with the following columns:
#
# user_id, old_value, new_value
#
# Only the encrypted values are stored in this file.
#
# As users may have their 2FA settings changed at any time, this is only
# guaranteed to be safe if run offline.
class OtpKeyRotator
HEADERS = %w[user_id old_value new_value].freeze
attr_reader :filename
# Create a new rotator. +filename+ is used to store values by +calculate!+,
# and to update the database with new and old values in +apply!+ and
# +rollback!+, respectively.
def initialize(filename)
@filename = filename
end
def rotate!(old_key:, new_key:)
old_key ||= Gitlab::Application.secrets.otp_key_base
raise ArgumentError.new("Old key is the same as the new key") if old_key == new_key
raise ArgumentError.new("New key is too short! Must be 256 bits") if new_key.size < 64
write_csv do |csv|
ActiveRecord::Base.transaction do
User.with_two_factor.in_batches do |relation|
rows = relation.pluck(:id, :encrypted_otp_secret, :encrypted_otp_secret_iv, :encrypted_otp_secret_salt)
rows.each do |row|
user = %i[id ciphertext iv salt].zip(row).to_h
new_value = reencrypt(user, old_key, new_key)
User.where(id: user[:id]).update_all(encrypted_otp_secret: new_value)
csv << [user[:id], user[:ciphertext], new_value]
end
end
end
end
end
def rollback!
ActiveRecord::Base.transaction do
CSV.foreach(filename, headers: HEADERS, return_headers: false) do |row|
User.where(id: row['user_id']).update_all(encrypted_otp_secret: row['old_value'])
end
end
end
private
attr_reader :old_key, :new_key
def otp_secret_settings
@otp_secret_settings ||= User.encrypted_attributes[:otp_secret]
end
def reencrypt(user, old_key, new_key)
original = user[:ciphertext].unpack("m").join
opts = {
iv: user[:iv].unpack("m").join,
salt: user[:salt].unpack("m").join,
algorithm: otp_secret_settings[:algorithm],
insecure_mode: otp_secret_settings[:insecure_mode]
}
decrypted = Encryptor.decrypt(original, opts.merge(key: old_key))
encrypted = Encryptor.encrypt(decrypted, opts.merge(key: new_key))
[encrypted].pack("m")
end
def write_csv(&blk)
File.open(filename, "w") do |file|
yield CSV.new(file, headers: HEADERS, write_headers: false)
end
end
end
end