Authenticate echobot by passing /run/echobot/password to doveauth

acmetool: accept new terms of services

.github/workflows/test-and-deploy.yaml

@@ -56,7 +56,7 @@ jobs:
           # restore acme & dkim state to staging.testrun.org
           rsync -avz acme-restore/acme/ root@staging.testrun.org:/var/lib/acme || true
           rsync -avz dkimkeys-restore/dkimkeys/ root@staging.testrun.org:/etc/dkimkeys || true
-          ssh -o StrictHostKeyChecking=accept-new -v root@staging.testrun.org chown root:root -R /var/lib/acme
+          ssh -o StrictHostKeyChecking=accept-new -v root@staging.testrun.org chown root:root -R /var/lib/acme || true
 
       - name: run formatting checks 
         run: cmdeploy fmt -v 

CHANGELOG.md

@@ -2,6 +2,15 @@
 
 ## untagged
 
+- Accept Let's Encrypt's new Terms of Services
+  ([#275](https://github.com/deltachat/chatmail/pull/276))
+
+- Reload Dovecot and Postfix when TLS certificate updates
+  ([#271](https://github.com/deltachat/chatmail/pull/271))
+
+- Use forked version of dovecot without hardcoded delays
+  ([#270](https://github.com/deltachat/chatmail/pull/270))
+
 ## 1.2.0 - 2024-04-04
 
 - Install dig on the server to resolve DNS records

README.md

@@ -159,4 +159,27 @@ While this file is present, account creation will be blocked.
 Delta Chat apps will, however, discover all ports and configurations
 automatically by reading the [autoconfig XML file](https://www.ietf.org/archive/id/draft-bucksch-autoconfig-00.html) from the chatmail service.
 
+## Email authentication
 
+chatmail servers rely on [DKIM](https://www.rfc-editor.org/rfc/rfc6376)
+to authenticate incoming emails.
+Incoming emails must have a valid DKIM signature with
+Signing Domain Identifier (SDID, `d=` parameter in the DKIM-Signature header)
+equal to the `From:` header domain.
+This property is checked by OpenDKIM screen policy script
+before validating the signatures.
+This correpsonds to strict [DMARC](https://www.rfc-editor.org/rfc/rfc7489) alignment (`adkim=s`),
+but chatmail does not rely on DMARC and does not consult the sender policy published in DMARC records.
+Other legacy authentication mechanisms such as [iprev](https://www.rfc-editor.org/rfc/rfc8601#section-2.7.3)
+and [SPF](https://www.rfc-editor.org/rfc/rfc7208) are also not taken into account.
+If there is no valid DKIM signature on the incoming email,
+the sender receives a "5.7.1 No valid DKIM signature found" error.
+
+Outgoing emails must be sent over authenticated connection
+with envelope MAIL FROM (return path) corresponding to the login.
+This is ensured by Postfix which maps login username
+to MAIL FROM with
+[`smtpd_sender_login_maps`](https://www.postfix.org/postconf.5.html#smtpd_sender_login_maps)
+and rejects incorrectly authenticated emails with [`reject_sender_login_mismatch`](reject_sender_login_mismatch) policy.
+`From:` header must correspond to envelope MAIL FROM,
+this is ensured by `filtermail` proxy.

chatmaild/src/chatmaild/doveauth.py

@@ -4,6 +4,7 @@ import time
 import sys
 import json
 import crypt
+from pathlib import Path
 from socketserver import (
     UnixStreamServer,
     StreamRequestHandler,
@@ -45,23 +46,32 @@ def is_allowed_to_create(config: Config, user, cleartext_password) -> bool:
         return False
     localpart, domain = parts
 
+    if localpart == "echo":
+        # echobot account should not be created in the database
+        return False
+
     if (
         len(localpart) > config.username_max_length
         or len(localpart) < config.username_min_length
     ):
-        if localpart != "echo":
         logging.warning(
             "localpart %s has to be between %s and %s chars long",
             localpart,
             config.username_min_length,
             config.username_max_length,
         )
-            return False
 
     return True
 
 
 def get_user_data(db, config: Config, user):
+    if user == f"echo@{config.mail_domain}":
+        return dict(
+            home=f"/home/vmail/mail/{config.mail_domain}/echo@{config.mail_domain}",
+            uid="vmail",
+            gid="vmail",
+        )
+
     with db.read_connection() as conn:
         result = conn.get_user(user)
     if result:
@@ -76,6 +86,21 @@ def lookup_userdb(db, config: Config, user):
 
 
 def lookup_passdb(db, config: Config, user, cleartext_password):
+    if user == f"echo@{config.mail_domain}":
+        # Echobot writes password it wants to log in with into /run/echobot/password
+        try:
+            password = Path("/run/echobot/password").read_text()
+        except Exception:
+            logging.exception("Exception when trying to read /run/echobot/password")
+            return None
+
+        return dict(
+            home=f"/home/vmail/mail/{config.mail_domain}/echo@{config.mail_domain}",
+            uid="vmail",
+            gid="vmail",
+            password=encrypt_password(password),
+        )
+
     with db.write_transaction() as conn:
         userdata = conn.get_user(user)
         if userdata:

chatmaild/src/chatmaild/echo.py

@@ -3,14 +3,17 @@
 
 it will echo back any message that has non-empty text and also supports the /help command.
 """
+
 import logging
 import os
 import sys
+import subprocess
 
 from deltachat_rpc_client import Bot, DeltaChat, EventType, Rpc, events
+from pathlib import Path
 
-from chatmaild.newemail import create_newemail_dict
 from chatmaild.config import read_config
+from chatmaild.newemail import create_newemail_dict
 
 hooks = events.HookCollection()
 
@@ -75,9 +78,23 @@ def main():
         account = accounts[0] if accounts else deltachat.add_account()
 
         bot = Bot(account, hooks)
-        if not bot.is_configured():
+
         config = read_config(sys.argv[1])
-            password = create_newemail_dict(config).get("password")
+
+        # Create password file
+        if bot.is_configured():
+            password = bot.account.get_config("mail_pw")
+        else:
+            password = create_newemail_dict(config)["password"]
+        Path("/run/echobot/password").write_text(password)
+
+        # Give the user which doveauth runs as access to the password file.
+        subprocess.run(
+            ["/usr/bin/setfacl", "-m", "user:vmail:r", "/run/echobot/password"],
+            check=True,
+        )
+
+        if not bot.is_configured():
             email = "echo@" + config.mail_domain
             bot.configure(email, password)
         bot.run_forever()

cmdeploy/src/cmdeploy/__init__.py

@@ -477,12 +477,30 @@ def deploy_chatmail(config_path: Path) -> None:
         groups=["opendkim"],
         system=True,
     )
+    server.user(name="Create echobot user", user="echobot", system=True)
 
     server.shell(
         name="Fix file owner in /home/vmail",
         commands=["test -d /home/vmail && chown -R vmail:vmail /home/vmail"],
     )
 
+    # Add our OBS repository for dovecot_no_delay
+    files.put(
+        name = "Add Deltachat OBS GPG key to apt keyring",
+        src = importlib.resources.files(__package__).joinpath("obs-home-deltachat.gpg"),
+        dest = "/etc/apt/keyrings/obs-home-deltachat.gpg",
+        user="root",
+        group="root",
+        mode="644",
+    )
+
+    files.line(
+        name = "Add DeltaChat OBS home repository to sources.list",
+        path = "/etc/apt/sources.list",
+        line = "deb [signed-by=/etc/apt/keyrings/obs-home-deltachat.gpg] https://download.opensuse.org/repositories/home:/deltachat/Debian_12/ ./",
+        ensure_newline = True,
+    )
+
     apt.update(name="apt update", cache_time=24 * 3600)
 
     apt.packages(
@@ -513,7 +531,6 @@ def deploy_chatmail(config_path: Path) -> None:
 
     # Deploy acmetool to have TLS certificates.
     deploy_acmetool(
-        nginx_hook=True,
         domains=[mail_domain, f"mta-sts.{mail_domain}", f"www.{mail_domain}"],
     )
 

cmdeploy/src/cmdeploy/acmetool/__init__.py

@@ -5,7 +5,7 @@ from pyinfra import host
 from pyinfra.facts.systemd import SystemdStatus
 
 
-def deploy_acmetool(nginx_hook=False, email="", domains=[]):
+def deploy_acmetool(email="", domains=[]):
     """Deploy acmetool."""
     apt.packages(
         name="Install acmetool",
@@ -20,11 +20,8 @@ def deploy_acmetool(nginx_hook=False, email="", domains=[]):
         mode="644",
     )
 
-    if nginx_hook:
     files.put(
-            src=importlib.resources.files(__package__)
-            .joinpath("acmetool.hook")
-            .open("rb"),
+        src=importlib.resources.files(__package__).joinpath("acmetool.hook").open("rb"),
         dest="/usr/lib/acme/hooks/nginx",
         user="root",
         group="root",
@@ -74,5 +71,5 @@ def deploy_acmetool(nginx_hook=False, email="", domains=[]):
 
     server.shell(
         name=f"Request certificate for: { ', '.join(domains) }",
-        commands=[f"acmetool want { ' '.join(domains)}"],
+        commands=[f"acmetool want --xlog.severity=debug { ' '.join(domains)}"],
     )

cmdeploy/src/cmdeploy/acmetool/acmetool.hook

@@ -3,3 +3,5 @@ set -e
 EVENT_NAME="$1"
 [ "$EVENT_NAME" = "live-updated" ] || exit 42
 systemctl restart nginx.service
+systemctl reload dovecot.service
+systemctl reload postfix.service

cmdeploy/src/cmdeploy/acmetool/response-file.yaml.j2

@@ -1,2 +1,2 @@
 "acme-enter-email": "{{ email }}"
-"acme-agreement:https://letsencrypt.org/documents/LE-SA-v1.3-September-21-2022.pdf": true
+"acme-agreement:https://letsencrypt.org/documents/LE-SA-v1.4-April-3-2024.pdf": true

cmdeploy/src/cmdeploy/service/echobot.service.f

@@ -7,6 +7,20 @@ Environment="PATH={remote_venv_dir}:$PATH"
 Restart=always
 RestartSec=30
 
+User=echobot
+Group=echobot
+
+# Create /var/lib/echobot
+StateDirectory=echobot
+
+# Create /run/echobot
+#
+# echobot stores /run/echobot/password
+# with a password there, which doveauth then reads.
+RuntimeDirectory=echobot
+
+WorkingDirectory=/var/lib/echobot
+
 # Apply security restrictions suggested by
 #   systemd-analyze security echobot.service
 CapabilityBoundingSet=
@@ -16,7 +30,10 @@ NoNewPrivileges=true
 PrivateDevices=true
 PrivateMounts=true
 PrivateTmp=true
-PrivateUsers=true
+
+# We need to know about doveauth user to give it access to /run/echobot/password
+PrivateUsers=false
+
 ProtectClock=true
 ProtectControlGroups=true
 ProtectHostname=true