nix-home/modules/cloud/mail/default.nix

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{ config, pkgs, lib, ... }:
with lib;
let
cfg = config.cloud.mail;
name = "maddy";
stateDir = "/var/lib/${name}";
runtimeDir = "/run/${name}";
smtpPort = 58787;
smtpsPort = 46565;
imapPort = 9333;
mtaStsPort = 8003;
in
{
options.cloud.mail = {
enable = mkEnableOption "Enable the email server";
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debug = mkEnableOption "Enable debugging";
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package = mkOption {
type = types.package;
default = pkgs.maddy;
};
hostname = mkOption {
type = types.str;
default = "mx1.nkagami.me";
description = "The hostname where the server is run on";
};
primaryDomain = mkOption {
type = types.str;
default = "nkagami.me";
description = "The primary email domain";
};
additionalDomains = mkOption {
type = types.listOf types.str;
default = [ ];
description = "Additional domain names to be used";
};
tls = {
certFile = mkOption {
type = types.str;
description = "Path to the certificate file.";
};
keyFile = mkOption {
type = types.str;
description = "Path to the key file.";
};
};
usersFile = mkOption {
type = types.path;
description = ''
The file containing user:hashed-password pairs to be used in the mail server.
Check `maddyctl hash` to generate hashed passwords.
'';
};
};
config =
let
configFile = pkgs.writeText "maddy.conf" ''
# Globals
state_dir ${stateDir}
runtime_dir ${runtimeDir}
# Base variables
$(hostname) = ${cfg.hostname}
$(primary_domain) = ${cfg.primaryDomain}
$(local_domains) = ${cfg.primaryDomain} ${lib.strings.concatStringsSep " " cfg.additionalDomains}
tls file "${cfg.tls.certFile}" "${cfg.tls.keyFile}"
# Authentication
auth.pass_table local_authdb {
table file ${cfg.usersFile}
}
# Local storage
storage.imapsql local_mailboxes {
driver "postgres"
dsn "dbname='${name}' user='${name}' host='/run/postgresql' sslmode=disable"
appendlimit 256M
}
# ----------------------------------------------------------------------------
# SMTP endpoints + message routing
hostname $(hostname)
msgpipeline local_routing {
# Insert handling for special-purpose local domains here.
# e.g.
# destination lists.example.org {
# deliver_to lmtp tcp://127.0.0.1:8024
# }
destination postmaster $(local_domains) {
modify {
replace_rcpt regexp "(.+)\+(.+)@(.+)" "$1@$3"
replace_rcpt file /etc/maddy/aliases
}
deliver_to &local_mailboxes
}
default_destination {
reject 550 5.1.1 "User doesn't exist"
}
}
smtp tcp://0.0.0.0:25 {
limits {
# Up to 20 msgs/sec across max. 10 SMTP connections.
all rate 20 1s
all concurrency 10
}
dmarc yes
check {
require_mx_record
dkim
spf
}
source $(local_domains) {
reject 501 5.1.8 "Use Submission for outgoing SMTP"
}
default_source {
destination postmaster $(local_domains) {
deliver_to &local_routing
}
default_destination {
reject 550 5.1.1 "User doesn't exist"
}
}
}
submission tcp://0.0.0.0:${toString smtpPort} tls://0.0.0.0:${toString smtpsPort} {
limits {
# Up to 50 msgs/sec across any amount of SMTP connections.
all rate 50 1s
}
auth &local_authdb
source $(local_domains) {
destination postmaster $(local_domains) {
deliver_to &local_routing
}
default_destination {
modify {
dkim $(primary_domain) $(local_domains) default
}
deliver_to &remote_queue
}
}
default_source {
reject 501 5.1.8 "Non-local sender domain"
}
}
target.remote outbound_delivery {
limits {
# Up to 20 msgs/sec across max. 10 SMTP connections
# for each recipient domain.
destination rate 20 1s
destination concurrency 10
}
mx_auth {
dane
mtasts {
cache fs
fs_dir mtasts_cache/
}
local_policy {
min_tls_level encrypted
min_mx_level none
}
}
}
target.queue remote_queue {
target &outbound_delivery
autogenerated_msg_domain $(primary_domain)
bounce {
destination postmaster $(local_domains) {
deliver_to &local_routing
}
default_destination {
reject 550 5.0.0 "Refusing to send DSNs to non-local addresses"
}
}
}
# ----------------------------------------------------------------------------
# IMAP endpoints
imap tls://0.0.0.0:${toString imapPort} {
auth &local_authdb
storage &local_mailboxes
}
'';
mtaStsDir = pkgs.writeTextDir ".well-known/mta-sts.txt" ''
version: STSv1
mode: enforce
max_age: 604800
mx: ${cfg.hostname}
'';
in
mkIf cfg.enable {
# users
users.users."${name}" = {
group = "${name}";
isSystemUser = true;
};
users.groups."${name}" = { };
# database
cloud.postgresql.databases = [ name ];
# MTA-STS server
services.nginx.enable = true;
services.nginx.virtualHosts.maddy-mta-sts = {
listen = [{ addr = "127.0.0.1"; port = mtaStsPort; }];
root = mtaStsDir;
};
# Firewall
networking.firewall.allowedTCPPorts = [ 25 ];
# traefik
cloud.traefik.hosts.maddy-smtp = {
protocol = "tcp";
port = smtpPort;
host = "mx1.nkagami.me";
tlsPassthrough = false;
entrypoints = [ "smtp-submission" ];
};
cloud.traefik.hosts.maddy-smtps = {
protocol = "tcp";
port = smtpsPort;
host = "mx1.nkagami.me";
entrypoints = [ "smtp-submission-ssl" ];
};
cloud.traefik.hosts.maddy-imap = {
protocol = "tcp";
port = imapPort;
host = "mx1.nkagami.me";
entrypoints = [ "imap" ];
};
cloud.traefik.hosts.maddy-mta-sts = {
port = mtaStsPort;
host = "mta-sts.nkagami.me";
};
# maddy itself
systemd.services."${name}" = {
after = [ "network.target" "traefik-certs-dumper.service" ];
wantedBy = [ "multi-user.target" ];
description = "maddy mail server";
documentation = [
"man:maddy(1)"
"man:maddy.conf(5)"
"https://maddy.email"
];
serviceConfig = {
Type = "notify";
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NotifyAccess = "exec";
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User = name;
Group = name;
WorkingDirectory = "/var/lib/${name}";
ConfigurationDirectory = name;
RuntimeDirectory = name;
StateDirectory = name;
LogsDirectory = name;
ReadOnlyPaths = "/usr/lib/${name} ${cfg.tls.keyFile} ${cfg.tls.certFile}";
ReadWritePaths = "/var/lib/${name}";
# Strict sandboxing. You have no reason to trust code written by strangers from GitHub.
PrivateTmp = true;
ProtectHome = true;
ProtectSystem = "strict";
ProtectKernelTunables = true;
ProtectHostname = true;
ProtectClock = true;
ProtectControlGroups = true;
RestrictAddressFamilies = "AF_UNIX AF_INET AF_INET6";
# Additional sandboxing. You need to disable all of these options
# for privileged helper binaries (for system auth) to work correctly.
NoNewPrivileges = true;
PrivateDevices = true;
DeviceAllow = "/dev/syslog";
RestrictSUIDSGID = true;
ProtectKernelModules = true;
MemoryDenyWriteExecute = true;
RestrictNamespaces = true;
RestrictRealtime = true;
LockPersonality = true;
# Graceful shutdown with a reasonable timeout.
TimeoutStopSec = "7s";
KillMode = "mixed";
KillSignal = "SIGTERM";
# Required to bind on ports lower than 1024.
AmbientCapabilities = "CAP_NET_BIND_SERVICE";
CapabilityBoundingSet = "CAP_NET_BIND_SERVICE";
# Bump FD limitations. Even idle mail server can have a lot of FDs open (think
# of idle IMAP connections, especially ones abandoned on the other end and
# slowly timing out).
LimitNOFILE = 131072;
# Limit processes count to something reasonable to
# prevent resources exhausting due to big amounts of helper
# processes launched.
LimitNPROC = 512;
# Restart server on any problem.
Restart = "on-failure";
# ... Unless it is a configuration problem.
RestartPreventExitStatus = 2;
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ExecStart = "${cfg.package}/bin/maddy ${if cfg.debug then "-debug " else ""}-config ${configFile}";
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};
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reload = ''
/bin/kill -USR1 $MAINPID
/bin/kill -USR2 $MAINPID
'';
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};
};
}