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Revision 5425b3f0

Added by Marc Dequènes over 15 years ago

  • ID 5425b3f0470e93a44529f3100be771616135b530

[evol] separate signed mail processing from commands extracting, and improved order

View differences:

lib/cyborghood/mail.rb
# This class handles RFC3156 signed messages, validates them, and extract orders properly.
# Encrypted content are not implemented yet.
module CyborgHood
class Order
attr_accessor :ok, :message, :system_message, :user, :commands, :references
attr_writer = :warn_sender
def initialize(ok, message = nil, system_message = nil)
@ok = ok
@message = message
@system_message = system_message
end
def warn_sender
# send reply message if user is identified or in selected situations
# (@warn_sender acts as an override)
@warn_sender || @user
end
end
class Mail < Delegator
include ActionMailer::Quoting
include ActionMailer::Utils
MAX_DRIFT_TIME = 600
attr_accessor :user
def initialize(msg = nil)
@config = Config.instance
......
def parse
if is_marked?
logger.info "Replay detected"
return nil
return Order.new(false, "Replay detected.")
end
return parse_signed() if is_pgp_signed?
return parse_encrypted() if is_pgp_encrypted?
{:ok => false, :msg => "mail not RFC3156 compliant"}.to_ostruct
# don't parse commands if user is not identified
return parse_plain if self.user
Order.new(false, "Mail not RFC3156 compliant.")
end
def create_reply
......
tmail_reply.from_addrs = TMail::Address.parse(@config.mail.from_address || self.to.first)
reply = self.class.new(tmail_reply.to_s)
reply.set_custom_headers
reply.user = self.user
reply
end
......
relay.set_disposition("inline")
reply.quoted_printable_body = msg
reply.sign
reply.crypt(reply.user.keyFingerPrint) unless reply.user.nil?
reply
end
......
private
def parse_signed
order = {:ok => false, :msg => "mail not formatted correctly"}
def parse_plain
command_txt = nil
if multipart?
if parts[0].content_type == "text/plain"
command_txt = self.parts[0].body
refs = self.parts.collect{|p| p.dup }
end
else
command_txt = self.body if self.content_type == "text/plain"
refs = []
end
unless command_txt
order = Order.new(false, "Mail does not contain a proper text part for commands.")
order.user = self.user
return order
end
commands = []
command_txt.each_line do |line|
line.chomp!
sline = line.strip
# skip empty lines and comments
next if sline == "" or sline[0, 1] == "#"
# stop processing when detecting message signature
break if line == "-- "
commands << sline
end
logger.debug "Mail OK"
mark_processed(sig_check.timestamp)
order = Order.new(true)
order.user = self.user
order.commands = commands
order.refs = refs
end
def parse_signed
sigs_check = verify_pgp_signature()
return order.to_ostruct if sigs_check.nil? or sigs_check.size != 1
return Order.new(false, "mail not formatted correctly (signed part)") if sigs_check.nil? or sigs_check.size != 1
sig_check = sigs_check.first
if sig_check.status == 0
logger.info "Mail content was properly signed by key #{sig_check.fingerprint}"
user = Person.find_by_fingerprint(sig_check.fingerprint)
if user.nil?
logger.info "Mail is from an unknown person"
order[:msg] = "unknown user"
return Order.new(false, "Mail content tampered or badly signed: " + sig_check.to_s) unless sig_check.status == 0
logger.info "Mail content was properly signed by key #{sig_check.fingerprint}"
user = Person.find_by_fingerprint(sig_check.fingerprint)
if user.nil?
order = Order.new(false, "Mail is from an unknown person.")
order.warn_sender = true
return order
end
logger.info "Mail is from user #{user.uid} (#{user.cn})"
self.user = user
drift = Time.new.to_i - sig_check.timestamp.to_i
logger.debug "Signature drift time: #{drift}"
unless drift.abs < MAX_DRIFT_TIME
if drift > 0
order = Order.new(false, "The signature was made too long ago (check your system clock)." +
" Rejected message to avoid replay attacks.")
order.user = self.user
else
logger.info "Mail is from user #{user.uid} (#{user.cn})"
drift = Time.new.to_i - sig_check.timestamp.to_i
logger.debug "Signature drift time: #{drift}"
if drift.abs < MAX_DRIFT_TIME
signed_content = pgp_signed_part()
if signed_content.multipart?
if signed_content.parts[0].content_type == "text/plain"
command_txt = signed_content.parts[0].body
refs = signed_content.parts.collect{|p| p.dup }
end
else
command_txt = signed_content.body if signed_content.content_type == "text/plain"
refs = []
end
if command_txt
commands = []
command_txt.each_line do |line|
line.chomp!
sline = line.strip
# skip empty lines and comments
next if sline == "" or sline[0, 1] == "#"
# stop processing when detecting message signature
break if line == "-- "
commands << sline
end
logger.debug "Mail OK"
mark_processed(sig_check.timestamp)
order = {:ok => true, :user => user, :commands => commands, :refs => refs}
else
order[:user] = user
logger.info "Mail does not contain a proper MIME part for commands"
end
else
if drift > 0
logger.info "Mail rejected as it may be a replay (signature timestamp is too old)"
order = {:ok => false, :user => user, :msg => "The signature was made too long ago (perhaps your system clock is not up-to-date). Rejected message to avoid replay attacks."}
else
# mark message to prevent later replay of the message
mark_processed(sig_check.timestamp)
logger.info "Mail rejected as it is coming from the future (and may allow later replay)"
order = {:ok => false, :user => user, :msg => "The signature was made in the future (perhaps your system clock is not up-to-date). Rejected message to avoid replay attacks."}
end
end
# mark message to prevent later replay of the message
mark_processed(sig_check.timestamp)
order = Order.new(false, "The signature was made in the future (check your system clock)." +
" Rejected message to avoid replay attacks.")
order.user = self.user
end
else
logger.info "Mail content tampered or badly signed: " + sig_check.to_s
return nil
return order
end
order.to_ostruct
signed_content = pgp_signed_part()
# create a fake mail and chain parsing operations
plain_mail = self.class.new(signed_content)
plain_mail.user = self.user
# propagate message_id to be able to mark messages (replay protection)
plein_mail.message_id = @mail.message_id
return plain_mail.parse
end
def parse_encrypted
order = {:ok => false, :msg => "mail not formatted correctly"}
catch :notforme do
begin
# block is not passed to delegate (limitation ?)
......
# create a fake mail and chain parsing operations
clear_mail = self.class.new(clear_message)
clear_mail.user = self.user
# propagate message_id to be able to mark messages (replay protection)
clear_mail.message_id = @mail.message_id
return clear_mail.parse
......
end
end
order.to_ostruct
Order.new(false, "Mail not formatted correctly (encrypted part).")
end
def mark_dir
postman
when :ignorable
end
end
if order.nil?
logger.info "Mail is invalid, ignoring..."
msg.delete
next
elsif not order.ok
logger.info "Sending reply for rejected message (#{order.msg})"
mail_reply = mail.create_simple_reject_reply("A message (ID: #{mail.message_id}) apparently from you was rejected for the following reason:\n #{order.msg}")
mail_reply.crypt(order.user.keyFingerPrint) unless order.user.nil?
mail_reply.deliver
result_tag = order.ok ? "SUCCESS" : "FAILURE"
logger.info "Processing result: #{result_tag} (#{order.message})"
logger.info "Extra processing information: " + order.system_message if order.system_message
unless order.ok
if order.warn_sender
logger.info "Sending reply for rejected message"
mail_reply = mail.create_simple_reject_reply("A message (ID: #{mail.message_id}), apparently from you," +
" was rejected for the following reason:\n #{order.message}")
mail_reply.deliver
end
msg.delete
next
end
......
# create transcript
logger.debug "Preparing reply"
reply_txt = "Hello #{order.user.cn},\n\nFollows the transcript of your commands:\n"
reply_txt = "Hello #{order.user.cn},\n\n"
reply_txt += order.message + "\n\n" if order.message
reply_txt += "Follows the transcript of your commands:\n"
reply_attachments = []
result_list.each do |result|
reply_txt << "> #{result.cmd}\n"

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