A mailgate for Postfix to encrypt incoming and outgoing email with S/MIME and/or OpenPGP and decrypting OpenPGP encrypted emails https://lacre.io
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#!/usr/bin/python
from ConfigParser import RawConfigParser
import email, os, smtplib, sys, traceback, markdown, syslog, requests
from M2Crypto import BIO, Rand, SMIME, X509
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
# Read configuration from /etc/gpg-mailgate.conf
_cfg = RawConfigParser()
_cfg.read('/etc/gpg-mailgate.conf')
cfg = dict()
for sect in _cfg.sections():
cfg[sect] = dict()
for (name, value) in _cfg.items(sect):
cfg[sect][name] = value
def log(msg):
if cfg.has_key('logging') and cfg['logging'].has_key('file'):
if cfg['logging']['file'] == "syslog":
syslog.syslog(syslog.LOG_INFO | syslog.LOG_MAIL, msg)
else:
logfile = open(cfg['logging']['file'], 'a')
logfile.write(msg + "\n")
logfile.close()
CERT_PATH = cfg['smime']['cert_path']+"/"
def send_msg( message, from_addr, recipients = None ):
if 'relay' in cfg and 'host' in cfg['relay'] and 'enc_port' in cfg['relay']:
relay = (cfg['relay']['host'], int(cfg['relay']['enc_port']))
smtp = smtplib.SMTP(relay[0], relay[1])
smtp.sendmail( from_addr, recipients, message.as_string() )
else:
log("Could not send mail due to wrong configuration")
if __name__ == "__main__":
# try:
# Read e-mail from stdin
raw = sys.stdin.read()
register_msg = email.message_from_string( raw )
from_addr = email.utils.parseaddr(register_msg['From'])[1]
sign_part = None
for msg_part in register_msg.walk():
if msg_part.get_content_type().lower() == "application/pkcs7-signature" or msg_part.get_content_type().lower() == "application/x-pkcs7-signature":
sign_type = 'smime'
sign_part = msg_part
break
# This may cause that a non ASCII-armored key will be seen as valid. Other solution is not that efficient though
#elif msg_part.get_content_type().lower() == "application/pgp-keys":
# sign_type = 'pgp'
# sign_part = msg_part.get_payload()
# break
elif "-----BEGIN PGP PUBLIC KEY BLOCK-----" in msg_part.get_payload() and "-----END PGP PUBLIC KEY BLOCK-----" in msg_part.get_payload():
msg_content = msg_part.get_payload()
start = msg_content.find("-----BEGIN PGP PUBLIC KEY BLOCK-----")
end = msg_content.find("-----END PGP PUBLIC KEY BLOCK-----")
sign_type = 'pgp'
sign_part = msg_content[start:end + 34]
break
if sign_part == None:
log("Unable to find PKCS7 signature or public PGP key in registration email")
failure_msg = file( cfg['mailregister']['mail_templates'] + "/registrationError.md").read()
msg = MIMEMultipart("alternative")
msg["From"] = cfg['mailregister']['register_email']
msg["To"] = from_addr
msg["Subject"] = "S/MIME / OpenPGP registration failed"
msg.attach(MIMEText(failure_msg, 'plain'))
msg.attach(MIMEText(markdown.markdown(failure_msg), 'html'))
send_msg(msg, cfg['mailregister']['register_email'], [from_addr])
sys.exit(0)
if sign_type == 'smime':
raw_sig = sign_part.get_payload().replace("\n","")
# re-wrap signature so that it fits base64 standards
cooked_sig = '\n'.join(raw_sig[pos:pos+76] for pos in xrange(0, len(raw_sig), 76))
# now, wrap the signature in a PKCS7 block
sig = """
-----BEGIN PKCS7-----
%s
-----END PKCS7-----
""" % cooked_sig
# and load it into an SMIME p7 object through the BIO I/O buffer:
buf = BIO.MemoryBuffer(sig)
p7 = SMIME.load_pkcs7_bio(buf)
sk = X509.X509_Stack()
signers = p7.get0_signers(sk)
signing_cert = signers[0]
#Save certificate compatible to RFC 2821
splitted_from_addr = from_addr.split('@')
processed_from_addr = splitted_from_addr[0] + '@' + splitted_from_addr[1].lower()
signing_cert.save(os.path.join(CERT_PATH, processed_from_addr))
# format in user-specific data
# sending success mail only for S/MIME as GPGMW handles this on its own
success_msg = file(cfg['mailregister']['mail_templates']+"/registrationSuccess.md").read()
success_msg = success_msg.replace("[:FROMADDRESS:]",from_addr)
msg = MIMEMultipart("alternative")
msg["From"] = cfg['mailregister']['register_email']
msg["To"] = from_addr
msg["Subject"] = "S/MIME certificate registration succeeded"
msg.attach(MIMEText(success_msg, 'plain'))
msg.attach(MIMEText(markdown.markdown(success_msg), 'html'))
send_msg(msg, cfg['mailregister']['register_email'], [from_addr])
log("S/MIME Registration succeeded")
elif sign_type == 'pgp':
# send POST to gpg-mailgate webpanel
sig = sign_part
payload = {'email': from_addr, 'key': sig}
r = requests.post(cfg['mailregister']['webpanel_url'], data=payload)
if r.status_code != 200:
log("Could not hand registration over to GPGMW. Error: %s" % r.status_code)
error_msg = file(cfg['mailregister']['mail_templates']+"/gpgmwFailed.md").read()
error_msg = error_msg.replace("[:FROMADDRESS:]",from_addr)
msg = MIMEMultipart("alternative")
msg["From"] = cfg['mailregister']['register_email']
msg["To"] = from_addr
msg["Subject"] = "PGP key registration failed"
msg.attach(MIMEText(error_msg, 'plain'))
msg.attach(MIMEText(markdown.markdown(error_msg), 'html'))
send_msg(msg, cfg['mailregister']['register_email'], [from_addr])
else:
log("PGP registration is handed over to GPGMW")
# except:
# log("Registration exception")
# sys.exit(0)