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11 changed files with 110 additions and 190 deletions

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@@ -2,13 +2,13 @@ import logging
import os
import sys
import json
import crypt
from socketserver import (
UnixStreamServer,
StreamRequestHandler,
ThreadingMixIn,
)
import pwd
import subprocess
from .database import Database
@@ -16,17 +16,9 @@ NOCREATE_FILE = "/etc/chatmail-nocreate"
def encrypt_password(password: str):
password = password.encode("ascii")
# https://doc.dovecot.org/configuration_manual/authentication/password_schemes/
process = subprocess.Popen(
["doveadm", "pw", "-s", "SHA512-CRYPT"],
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
)
stdout_data, _stderr_data = process.communicate(
input=password + b"\n" + password + b"\n"
)
return stdout_data.decode("ascii").strip()
passhash = crypt.crypt(password, crypt.METHOD_SHA512)
return "{SHA512-CRYPT}" + passhash
def create_user(db, user, password):

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@@ -1,10 +0,0 @@
[Unit]
Description=Chatmail Postfix AfterQueue filter
[Service]
ExecStart=/usr/local/bin/filtermail afterqueue /var/spool/postfix/private/filtermail-afterqueue
Restart=always
RestartSec=30
[Install]
WantedBy=multi-user.target

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@@ -7,9 +7,8 @@ from email.parser import BytesParser
from email import policy
from email.utils import parseaddr
from aiosmtpd.lmtp import LMTP
from aiosmtpd.smtp import SMTP
from aiosmtpd.controller import UnixSocketController, Controller
from aiosmtpd.controller import Controller
from smtplib import SMTP as SMTPClient
@@ -35,24 +34,71 @@ def check_encrypted(message):
return True
class SMTPController(Controller):
def factory(self):
return SMTP(self.handler, **self.SMTP_kwargs)
class BeforeQueueHandler:
def __init__(self):
self.send_rate_limiter = SendRateLimiter()
async def handle_MAIL(self, server, session, envelope, address, mail_options):
logging.info(f"handle_MAIL from {address}")
if self.send_rate_limiter.is_sending_allowed(address):
envelope.mail_from = address
return "250 OK"
return f"450 4.7.1: Too much mail from {address}"
envelope.mail_from = address
if not self.send_rate_limiter.is_sending_allowed(address):
return f"450 4.7.1: Too much mail from {address}"
parts = envelope.mail_from.split("@")
if len(parts) != 2:
return f"500 Invalid from address <{envelope.mail_from!r}>"
return "250 OK"
async def handle_DATA(self, server, session, envelope):
logging.info("handle_DATA before-queue: re-injecting the mail")
client = SMTPClient("localhost", "10026")
logging.info("handle_DATA before-queue")
error = check_DATA(envelope)
if error:
return error
logging.info("re-injecting the mail that passed checks")
client = SMTPClient("localhost", "10025")
client.sendmail(envelope.mail_from, envelope.rcpt_tos, envelope.content)
return "250 OK"
async def asyncmain_beforequeue(port):
Controller(BeforeQueueHandler(), hostname="127.0.0.1", port=port).start()
def check_DATA(envelope):
"""the central filtering function for e-mails."""
logging.info(f"Processing DATA message from {envelope.mail_from}")
message = BytesParser(policy=policy.default).parsebytes(envelope.content)
mail_encrypted = check_encrypted(message)
_, from_addr = parseaddr(message.get("from").strip())
logging.info(f"mime-from: {from_addr} envelope-from: {envelope.mail_from!r}")
if envelope.mail_from.lower() != from_addr.lower():
return f"500 Invalid FROM <{from_addr!r}> for <{envelope.mail_from!r}>"
envelope_from_domain = from_addr.split("@").pop()
for recipient in envelope.rcpt_tos:
if envelope.mail_from == recipient:
# Always allow sending emails to self.
continue
res = recipient.split("@")
if len(res) != 2:
return f"500 Invalid address <{recipient}>"
_recipient_addr, recipient_domain = res
is_outgoing = recipient_domain != envelope_from_domain
if is_outgoing and not mail_encrypted:
is_securejoin = message.get("secure-join") in ["vc-request", "vg-request"]
if not is_securejoin:
return f"500 Invalid unencrypted mail to <{recipient}>"
class SendRateLimiter:
MAX_USER_SEND_PER_MINUTE = 80
@@ -69,104 +115,12 @@ class SendRateLimiter:
return False
class AfterQueueHandler:
async def handle_RCPT(self, server, session, envelope, address, rcpt_options):
envelope.rcpt_tos.append(address)
return "250 OK"
async def handle_DATA(self, server, session, envelope):
valid_recipients, res = lmtp_handle_DATA(envelope)
# Reinject the mail back into Postfix.
if valid_recipients:
logging.info("afterqueue: re-injecting the mail")
client = SMTPClient("localhost", "10027")
client.sendmail(envelope.mail_from, valid_recipients, envelope.content)
else:
logging.info("no valid recipients, ignoring mail")
return "\r\n".join(res)
def lmtp_handle_DATA(envelope):
"""the central filtering function for e-mails."""
logging.info(f"Processing DATA message from {envelope.mail_from}")
message = BytesParser(policy=policy.default).parsebytes(envelope.content)
mail_encrypted = check_encrypted(message)
valid_recipients = []
res = []
for recipient in envelope.rcpt_tos:
my_local_domain = envelope.mail_from.split("@")
if len(my_local_domain) != 2:
res += [f"500 Invalid from address <{envelope.mail_from}>"]
continue
_, from_addr = parseaddr(message.get("from").strip())
logging.info(f"mime-from: {from_addr} envelope-from: {envelope.mail_from}")
if envelope.mail_from.lower() != from_addr.lower():
res += [f"500 Invalid FROM <{from_addr}> for <{envelope.mail_from}>"]
continue
if envelope.mail_from == recipient:
# Always allow sending emails to self.
valid_recipients += [recipient]
res += ["250 OK"]
continue
recipient_local_domain = recipient.split("@")
if len(recipient_local_domain) != 2:
res += [f"500 Invalid address <{recipient}>"]
continue
is_outgoing = recipient_local_domain[1] != my_local_domain[1]
if (
is_outgoing
and not mail_encrypted
and message.get("secure-join") != "vc-request"
and message.get("secure-join") != "vg-request"
):
res += ["500 Outgoing mail must be encrypted"]
continue
valid_recipients += [recipient]
res += ["250 OK"]
assert len(envelope.rcpt_tos) == len(res)
assert len(valid_recipients) <= len(res)
return valid_recipients, res
class UnixController(UnixSocketController):
def factory(self):
return LMTP(self.handler, **self.SMTP_kwargs)
class SMTPController(Controller):
def factory(self):
return SMTP(self.handler, **self.SMTP_kwargs)
async def asyncmain_afterqueue(loop, unix_socket_fn):
UnixController(AfterQueueHandler(), unix_socket=unix_socket_fn).start()
async def asyncmain_beforequeue(loop, port):
Controller(BeforeQueueHandler(), hostname="127.0.0.1", port=port).start()
def main():
args = sys.argv[1:]
assert len(args) == 2
assert len(args) == 1
logging.basicConfig(level=logging.INFO)
loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)
if args[0] == "afterqueue":
task = asyncmain_afterqueue(loop, args[1])
elif args[0] == "beforequeue":
task = asyncmain_beforequeue(loop, port=int(args[1]))
else:
raise SystemExit(1)
task = asyncmain_beforequeue(port=int(args[0]))
loop.create_task(task)
loop.run_forever()

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@@ -2,7 +2,7 @@
Description=Chatmail Postfix BeforeQeue filter
[Service]
ExecStart=/usr/local/bin/filtermail beforequeue 10080
ExecStart=/usr/local/bin/filtermail 10080
Restart=always
RestartSec=30

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@@ -1,4 +1,4 @@
from .filtermail import check_encrypted, lmtp_handle_DATA, SendRateLimiter
from .filtermail import check_encrypted, check_DATA, SendRateLimiter
from email.parser import BytesParser
from email import policy
import pytest
@@ -31,15 +31,12 @@ def test_reject_forged_from():
# test that the filter lets good mail through
envelope.content = makemail(envelope.mail_from).as_bytes()
valid_recipients, res = lmtp_handle_DATA(envelope=envelope)
assert valid_recipients == envelope.rcpt_tos
assert len(res) == 1 and "250" in res[0]
assert not check_DATA(envelope=envelope)
# test that the filter rejects forged mail
envelope.content = makemail("forged@c3.testrun.org").as_bytes()
valid_recipients, res = lmtp_handle_DATA(envelope=envelope)
assert not valid_recipients
assert len(res) == 1 and "500" in res[0]
error = check_DATA(envelope=envelope)
assert "500" in error
def test_filtermail():

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@@ -34,28 +34,12 @@ def _install_chatmaild() -> None:
commands=[f"pip install --break-system-packages {remote_path}"],
)
files.put(
name="upload doveauth-dictproxy.service",
src=importlib.resources.files("chatmaild")
.joinpath("doveauth-dictproxy.service")
.open("rb"),
dest="/etc/systemd/system/doveauth-dictproxy.service",
user="root",
group="root",
mode="644",
)
systemd.service(
name="Setup doveauth-dictproxy service",
service="doveauth-dictproxy.service",
running=True,
enabled=True,
restarted=True,
daemon_reload=True,
)
for fn in ("filtermail-after", "filtermail-before"):
for fn in (
"doveauth-dictproxy",
"filtermail",
):
files.put(
name=f"upload {fn}.service",
name=f"Upload {fn}.service",
src=importlib.resources.files("chatmaild")
.joinpath(f"{fn}.service")
.open("rb"),
@@ -293,6 +277,22 @@ def deploy_chatmail(mail_domain: str, mail_server: str, dkim_selector: str) -> N
commands=[f"echo {mail_domain} >/etc/mailname; chmod 644 /etc/mailname"],
)
journald_conf = files.put(
name="Configure journald",
src=importlib.resources.files(__package__).joinpath("journald.conf"),
dest="/etc/systemd/journald.conf",
user="root",
group="root",
mode="644",
)
systemd.service(
name="Start and enable journald",
service="systemd-journald.service",
running=True,
enabled=True,
restarted=journald_conf,
)
def callback():
result = server.shell(
commands=[

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@@ -0,0 +1,2 @@
[Journal]
MaxRetentionSec=3d

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@@ -33,7 +33,6 @@ submission inet n - y - - smtpd
-o smtpd_relay_restrictions=permit_sasl_authenticated,reject
-o milter_macro_daemon_name=ORIGINATING
-o smtpd_proxy_filter=127.0.0.1:10080
-o content_filter=filter:unix:private/filtermail-afterqueue
smtps inet n - y - - smtpd
-o syslog_name=postfix/smtps
-o smtpd_tls_wrappermode=yes
@@ -77,7 +76,5 @@ scache unix - - y - 1 scache
postlog unix-dgram n - n - 1 postlogd
filter unix - n n - - lmtp
# Local SMTP server for reinjecting filered mail.
localhost:10026 inet n - n - 10 smtpd
-o content_filter=filter:unix:private/filtermail-afterqueue
localhost:10027 inet n - n - 10 smtpd
-o content_filter=
localhost:10025 inet n - n - 10 smtpd
-o syslog_name=postfix/reinject

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@@ -20,7 +20,7 @@ def test_use_two_chatmailservers(cmfactory, maildomain2):
@pytest.mark.parametrize("forgeaddr", ["internal", "someone@example.org"])
def test_reject_forged_from(cmsetup, mailgen, lp, remote, forgeaddr):
def test_reject_forged_from(cmsetup, mailgen, lp, forgeaddr):
user1, user3 = cmsetup.gen_users(2)
lp.sec("send encrypted message with forged from")
@@ -36,17 +36,25 @@ def test_reject_forged_from(cmsetup, mailgen, lp, remote, forgeaddr):
print(f" {line}")
lp.sec("Send forged mail and check remote postfix lmtp processing result")
remote_log = remote.iter_output("journalctl -t postfix/lmtp")
user1.smtp.sendmail(from_addr=user1.addr, to_addrs=[user3.addr], msg=msg)
for line in remote_log:
# print(line)
if "500 invalid from" in line and user3.addr in line:
break
else:
pytest.fail("remote postfix/filtermail failed to reject message")
with pytest.raises(smtplib.SMTPException) as e:
user1.smtp.sendmail(from_addr=user1.addr, to_addrs=[user3.addr], msg=msg)
assert "500" in str(e.value)
# check that the logged in user (who sent the forged msg) got a non-delivery notice
for message in user1.imap.fetch_all_messages():
if "Invalid FROM" in message and addr_to_forge in message:
@pytest.mark.slow
def test_exceed_rate_limit(cmsetup, gencreds, mailgen):
"""Test that the per-account send-mail limit is exceeded."""
user1, user2 = cmsetup.gen_users(2)
mail = mailgen.get_encrypted(user1.addr, user2.addr)
for i in range(100):
print("Sending mail", str(i))
try:
user1.smtp.sendmail(user1.addr, [user2.addr], mail)
except smtplib.SMTPException as e:
if i < 80:
pytest.fail(f"rate limit was exceeded too early with msg {i}")
outcome = e.recipients[user2.addr]
assert outcome[0] == 450
assert b'4.7.1: Too much mail from' in outcome[1]
return
pytest.fail(f"forged From={addr_to_forge} did not cause non-delivery notice")
pytest.fail("Rate limit was not exceeded")

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@@ -35,22 +35,3 @@ def test_login_same_password(imap_or_smtp, gencreds):
imap_or_smtp.login(user1, password1)
imap_or_smtp.connect()
imap_or_smtp.login(user2, password1)
@pytest.mark.slow
def test_exceed_rate_limit(cmsetup, gencreds, mailgen):
"""Test that the per-account send-mail limit is exceeded."""
user1, user2 = cmsetup.gen_users(2)
mail = mailgen.get_encrypted(user1.addr, user2.addr)
for i in range(100):
print("Sending mail", str(i))
try:
user1.smtp.sendmail(user1.addr, [user2.addr], mail)
except smtplib.SMTPException as e:
if i < 80:
pytest.fail(f"rate limit was exceeded too early with msg {i}")
outcome = e.recipients[user2.addr]
assert outcome[0] == 450
assert b'4.7.1: Too much mail from' in outcome[1]
return
pytest.fail("Rate limit was not exceeded")

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@@ -6,7 +6,6 @@ deploy-chatmail/venv/bin/pip install -e deploy-chatmail
deploy-chatmail/venv/bin/pip install -e chatmaild
python3 -m venv chatmaild/venv
sudo apt install -y dovecot-core && sudo systemctl disable --now dovecot
chatmaild/venv/bin/pip install --upgrade pytest build 'setuptools>=68'
chatmaild/venv/bin/pip install -e chatmaild