Reject unencrypted incoming mail (#538)

* draft blocking of incoming non-encrypted mail

* create a new enforceE2EE file in address dirs by default and only accept incoming cleartext file if the enforceE2EE file is missing

* Update cmdeploy/src/cmdeploy/service/filtermail.service.f

Co-authored-by: l <link2xt@testrun.org>

* fix benchmark so they setup encryption

* hack around limitations of aiosmtpd's handliung of RCPTO options

* add tests, and split incoming/outgoing handlers for clarity

* document mailbox directory structure, some streamlining of features/E2EE in intro

* use SMTP response code "523 Encryption Needed"

* filtermail: care for the case that the recipient does not exist


Co-authored-by: missytake <missytake@systemli.org>

* Update chatmaild/src/chatmaild/filtermail.py

Co-authored-by: l <link2xt@testrun.org>

* Update chatmaild/src/chatmaild/filtermail.py

Co-authored-by: l <link2xt@testrun.org>

* remove debug info print

* ensure multipart/report type for mailer-daemon messages

* Allow sending out Autocrypt Setup Messages

---------

Co-authored-by: l <link2xt@testrun.org>
Co-authored-by: missytake <missytake@systemli.org>

cmdeploy/src/cmdeploy/__init__.py

@@ -106,12 +106,14 @@ def _install_remote_venv_with_chatmaild(config) -> None:
     for fn in (
         "doveauth",
         "filtermail",
+        "filtermail-incoming",
         "echobot",
         "chatmail-metadata",
         "lastlogin",
     ):
+        execpath = fn if fn != "filtermail-incoming" else "filtermail"
         params = dict(
-            execpath=f"{remote_venv_dir}/bin/{fn}",
+            execpath=f"{remote_venv_dir}/bin/{execpath}",
             config_path=remote_chatmail_inipath,
             remote_venv_dir=remote_venv_dir,
             mail_domain=config.mail_domain,
@@ -541,7 +543,6 @@ def deploy_chatmail(config_path: Path, disable_mail: bool) -> None:
 
     server.group(name="Create vmail group", group="vmail", system=True)
     server.user(name="Create vmail user", user="vmail", group="vmail", system=True)
-    server.user(name="Create filtermail user", user="filtermail", system=True)
     server.group(name="Create opendkim group", group="opendkim", system=True)
     server.user(
         name="Create opendkim user",

cmdeploy/src/cmdeploy/postfix/master.cf.j2

@@ -14,7 +14,7 @@ smtp      inet  n       -       y       -       -       smtpd -v
 {%- else %}
 smtp      inet  n       -       y       -       -       smtpd 
 {%- endif %}
-  -o smtpd_milters=unix:opendkim/opendkim.sock
+  -o smtpd_proxy_filter=127.0.0.1:{{ config.filtermail_smtp_port_incoming }}
 submission inet n       -       y       -       5000    smtpd
   -o syslog_name=postfix/submission
   -o smtpd_tls_security_level=encrypt
@@ -76,12 +76,17 @@ anvil     unix  -       -       y       -       1       anvil
 scache    unix  -       -       y       -       1       scache
 postlog   unix-dgram n  -       n       -       1       postlogd
 filter    unix -        n       n       -       -       lmtp
-# Local SMTP server for reinjecting filered mail.
+# Local SMTP server for reinjecting outgoing filtered mail.
 localhost:{{ config.postfix_reinject_port }} inet  n       -       n       -       10      smtpd
   -o syslog_name=postfix/reinject
   -o smtpd_milters=unix:opendkim/opendkim.sock
   -o cleanup_service_name=authclean
 
+# Local SMTP server for reinjecting incoming filtered mail 
+localhost:{{ config.postfix_reinject_port_incoming }} inet  n       -       n       -       10      smtpd
+  -o syslog_name=postfix/reinject_incoming
+  -o smtpd_milters=unix:opendkim/opendkim.sock
+
 # Cleanup `Received` headers for authenticated mail
 # to avoid leaking client IP.
 #

cmdeploy/src/cmdeploy/service/filtermail-incoming.service.f

@@ -0,0 +1,12 @@
+[Unit]
+Description=Incoming Chatmail Postfix before queue filter 
+
+[Service]
+ExecStart={execpath} {config_path} incoming
+Restart=always
+RestartSec=30
+User=vmail
+
+[Install]
+WantedBy=multi-user.target
+

cmdeploy/src/cmdeploy/service/filtermail.service.f

@@ -1,11 +1,11 @@
 [Unit]
-Description=Chatmail Postfix before queue filter
+Description=Outgoing Chatmail Postfix before queue filter
 
 [Service]
-ExecStart={execpath} {config_path}
+ExecStart={execpath} {config_path} outgoing
 Restart=always
 RestartSec=30
-User=filtermail
+User=vmail
 
 [Install]
 WantedBy=multi-user.target

cmdeploy/src/cmdeploy/tests/online/benchmark.py

@@ -37,7 +37,7 @@ class TestDC:
 
     def test_ping_pong(self, benchmark, cmfactory):
         ac1, ac2 = cmfactory.get_online_accounts(2)
-        chat = cmfactory.get_accepted_chat(ac1, ac2)
+        chat = cmfactory.get_protected_chat(ac1, ac2)
 
         def dc_ping_pong():
             chat.send_text("ping")
@@ -49,7 +49,7 @@ class TestDC:
 
     def test_send_10_receive_10(self, benchmark, cmfactory, lp):
         ac1, ac2 = cmfactory.get_online_accounts(2)
-        chat = cmfactory.get_accepted_chat(ac1, ac2)
+        chat = cmfactory.get_protected_chat(ac1, ac2)
 
         def dc_send_10_receive_10():
             for i in range(10):

cmdeploy/src/cmdeploy/tests/online/test_2_deltachat.py

@@ -173,7 +173,7 @@ def test_echobot(cmfactory, chatmail_config, lp, sshdomain):
     ac._evtracker.wait_securejoin_joiner_progress(1000)
 
     # send message and check it gets replied back
-    lp.sec(f"Send message to echobot")
+    lp.sec("Send message to echobot")
     text = "hi, I hope you text me back"
     chat.send_text(text)
     lp.sec("Wait for reply from echobot")

cmdeploy/src/cmdeploy/tests/plugin.py

@@ -62,7 +62,7 @@ def sshdomain(maildomain):
 def maildomain2():
     domain = os.environ.get("CHATMAIL_DOMAIN2")
     if not domain:
-        pytest.skip("set CHATMAIL_DOMAIN2 to a ssh-reachable chatmail instance")
+        pytest.skip("set CHATMAIL_DOMAIN2 to a second chatmail server")
     return domain