From 9b8265b2a5f4a19d844b4d0d474e079f3338f68a Mon Sep 17 00:00:00 2001 From: drebs Date: Thu, 7 Nov 2013 14:52:20 -0200 Subject: Do not encrypt already encrypted mails in SMTP relay. --- src/leap/mail/smtp/smtprelay.py | 60 +++++++++++++++++++++++++++-------------- 1 file changed, 40 insertions(+), 20 deletions(-) (limited to 'src/leap/mail/smtp') diff --git a/src/leap/mail/smtp/smtprelay.py b/src/leap/mail/smtp/smtprelay.py index 92a9f0e..14de849 100644 --- a/src/leap/mail/smtp/smtprelay.py +++ b/src/leap/mail/smtp/smtprelay.py @@ -284,7 +284,8 @@ class SMTPDelivery(object): # try to find recipient's public key try: address = validate_address(user.dest.addrstr) - pubkey = self._km.get_key(address, OpenPGPKey) + # verify if recipient key is available in keyring + self._km.get_key(address, OpenPGPKey) # might raise KeyNotFound log.msg("Accepting mail for %s..." % user.dest.addrstr) signal(proto.SMTP_RECIPIENT_ACCEPTED_ENCRYPTED, user.dest.addrstr) except KeyNotFound: @@ -510,15 +511,13 @@ class EncryptedMessage(object): @param signkey: The private key used to sign the message. @type signkey: leap.common.keymanager.openpgp.OpenPGPKey """ - # parse original message from received lines - origmsg = self.parseMessage() # create new multipart/encrypted message with 'pgp-encrypted' protocol newmsg = MultipartEncrypted('application/pgp-encrypted') # move (almost) all headers from original message to the new message - move_headers(origmsg, newmsg) + move_headers(self._origmsg, newmsg) # create 'application/octet-stream' encrypted message encmsg = MIMEApplication( - self._km.encrypt(origmsg.as_string(unixfrom=False), pubkey, + self._km.encrypt(self._origmsg.as_string(unixfrom=False), pubkey, sign=signkey), _subtype='octet-stream', _encoder=lambda x: x) encmsg.add_header('content-disposition', 'attachment', @@ -538,22 +537,20 @@ class EncryptedMessage(object): @param signkey: The private key used to sign the message. @type signkey: leap.common.keymanager.openpgp.OpenPGPKey """ - # parse original message from received lines - origmsg = self.parseMessage() # create new multipart/signed message newmsg = MultipartSigned('application/pgp-signature', 'pgp-sha512') # move (almost) all headers from original message to the new message - move_headers(origmsg, newmsg) + move_headers(self._origmsg, newmsg) # apply base64 content-transfer-encoding - encode_base64_rec(origmsg) + encode_base64_rec(self._origmsg) # get message text with headers and replace \n for \r\n fp = StringIO() g = RFC3156CompliantGenerator( fp, mangle_from_=False, maxheaderlen=76) - g.flatten(origmsg) + g.flatten(self._origmsg) msgtext = re.sub('\r?\n', '\r\n', fp.getvalue()) # make sure signed message ends with \r\n as per OpenPGP stantard. - if origmsg.is_multipart(): + if self._origmsg.is_multipart(): if not msgtext.endswith("\r\n"): msgtext += "\r\n" # calculate signature @@ -561,23 +558,46 @@ class EncryptedMessage(object): clearsign=False, detach=True, binary=False) sigmsg = PGPSignature(signature) # attach original message and signature to new message - newmsg.attach(origmsg) + newmsg.attach(self._origmsg) newmsg.attach(sigmsg) self._msg = newmsg def _maybe_encrypt_and_sign(self): """ - Encrypt the message body. + Attempt to encrypt and sign the outgoing message. - Fetch the recipient key and encrypt the content to the - recipient. If a key is not found, then the behaviour depends on the - configuration parameter ENCRYPTED_ONLY_KEY. If it is False, the message - is sent unencrypted and a warning is logged. If it is True, the - encryption fails with a KeyNotFound exception. + The behaviour of this method depends on: - @raise KeyNotFound: Raised when the recipient key was not found and - the ENCRYPTED_ONLY_KEY configuration parameter is set to True. + 1. the original message's content-type, and + 2. the availability of the recipient's public key. + + If the original message's content-type is "multipart/encrypted", then + the original message is not altered. For any other content-type, the + method attempts to fetch the recipient's public key. If the + recipient's public key is available, the message is encrypted and + signed; otherwise it is only signed. + + Note that, if the C{encrypted_only} configuration is set to True and + the recipient's public key is not available, then the recipient + address would have been rejected in SMTPDelivery.validateTo(). + + The following table summarizes the overall behaviour of the relay: + + +---------------------------------------------------+----------------+ + | content-type | rcpt pubkey | enforce encr. | action | + +---------------------+-------------+---------------+----------------+ + | multipart/encrypted | any | any | pass | + | other | available | any | encrypt + sign | + | other | unavailable | yes | reject | + | other | unavailable | no | sign | + +---------------------+-------------+---------------+----------------+ """ + # pass if the original message's content-type is "multipart/encrypted" + self._origmsg = self.parseMessage() + if self._origmsg.get_content_type() == 'multipart/encrypted': + self._msg = self._origmsg + return + from_address = validate_address(self._fromAddress.addrstr) signkey = self._km.get_key(from_address, OpenPGPKey, private=True) log.msg("Will sign the message with %s." % signkey.fingerprint) -- cgit v1.2.3