misc_nixos-mailserver/mail-server/postfix.nix
Antoine Eiche 5f431207b3 postfix: forwarding emails of login accounts with keeping local copy
When a local account address is forwarded, the mails were not locally
kept. This was due to the way lookup tables were internally managed.

Instead of using lists to represent Postfix lookup tables, we now use
attribute sets: they can then be easily merged.

A regression test for
https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/issues/
has been added: it sets a forward on a local address and ensure an
email sent to this address is locally kept.

Fixes #205
2021-02-06 08:17:43 +00:00

262 lines
10 KiB
Nix

# nixos-mailserver: a simple mail server
# Copyright (C) 2016-2018 Robin Raymond
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>
{ config, pkgs, lib, ... }:
with (import ./common.nix { inherit config pkgs lib; });
let
inherit (lib.strings) concatStringsSep;
cfg = config.mailserver;
# Merge several lookup tables. A lookup table is a attribute set where
# - the key is an address (user@example.com) or a domain (@example.com)
# - the value is a list of addresses
mergeLookupTables = tables: lib.zipAttrsWith (n: v: lib.flatten v) tables;
# valiases_postfix :: Map String [String]
valiases_postfix = mergeLookupTables (lib.flatten (lib.mapAttrsToList
(name: value:
let to = name;
in map (from: {"${from}" = to;}) (value.aliases ++ lib.singleton name))
cfg.loginAccounts));
# catchAllPostfix :: Map String [String]
catchAllPostfix = mergeLookupTables (lib.flatten (lib.mapAttrsToList
(name: value:
let to = name;
in map (from: {"@${from}" = to;}) value.catchAll)
cfg.loginAccounts));
# all_valiases_postfix :: Map String [String]
all_valiases_postfix = mergeLookupTables [valiases_postfix extra_valiases_postfix];
# attrsToLookupTable :: Map String (Either String [ String ]) -> Map String [String]
attrsToLookupTable = aliases: let
lookupTables = lib.mapAttrsToList (from: to: {"${from}" = to;}) aliases;
in mergeLookupTables lookupTables;
# extra_valiases_postfix :: Map String [String]
extra_valiases_postfix = attrsToLookupTable cfg.extraVirtualAliases;
# forwards :: Map String [String]
forwards = attrsToLookupTable cfg.forwards;
# lookupTableToString :: Map String [String] -> String
lookupTableToString = attrs: let
valueToString = value: lib.concatStringsSep ", " value;
in lib.concatStringsSep "\n" (lib.mapAttrsToList (name: value: "${name} ${valueToString value}") attrs);
# valiases_file :: Path
valiases_file = let
content = lookupTableToString (mergeLookupTables [all_valiases_postfix catchAllPostfix]);
in builtins.toFile "valias" content;
# denied_recipients_postfix :: [ String ]
denied_recipients_postfix = (map
(acct: "${acct.name} REJECT ${acct.sendOnlyRejectMessage}")
(lib.filter (acct: acct.sendOnly) (lib.attrValues cfg.loginAccounts)));
denied_recipients_file = builtins.toFile "denied_recipients" (lib.concatStringsSep "\n" denied_recipients_postfix);
reject_senders_postfix = (map
(sender:
"${sender} REJECT")
(cfg.rejectSender));
reject_senders_file = builtins.toFile "reject_senders" (lib.concatStringsSep "\n" (reject_senders_postfix)) ;
reject_recipients_postfix = (map
(recipient:
"${recipient} REJECT")
(cfg.rejectRecipients));
# rejectRecipients :: [ Path ]
reject_recipients_file = builtins.toFile "reject_recipients" (lib.concatStringsSep "\n" (reject_recipients_postfix)) ;
# vhosts_file :: Path
vhosts_file = builtins.toFile "vhosts" (concatStringsSep "\n" cfg.domains);
# vaccounts_file :: Path
# see
# https://blog.grimneko.de/2011/12/24/a-bunch-of-tips-for-improving-your-postfix-setup/
# for details on how this file looks. By using the same file as valiases,
# every alias is owned (uniquely) by its user.
# The user's own address is already in all_valiases_postfix.
vaccounts_file = builtins.toFile "vaccounts" (lookupTableToString all_valiases_postfix);
submissionHeaderCleanupRules = pkgs.writeText "submission_header_cleanup_rules" (''
# Removes sensitive headers from mails handed in via the submission port.
# See https://thomas-leister.de/mailserver-debian-stretch/
# Uses "pcre" style regex.
/^Received:/ IGNORE
/^X-Originating-IP:/ IGNORE
/^X-Mailer:/ IGNORE
/^User-Agent:/ IGNORE
/^X-Enigmail:/ IGNORE
'' + lib.optionalString cfg.rewriteMessageId ''
# Replaces the user submitted hostname with the server's FQDN to hide the
# user's host or network.
/^Message-ID:\s+<(.*?)@.*?>/ REPLACE Message-ID: <$1@${cfg.fqdn}>
'');
inetSocket = addr: port: "inet:[${toString port}@${addr}]";
unixSocket = sock: "unix:${sock}";
smtpdMilters =
(lib.optional cfg.dkimSigning "unix:/run/opendkim/opendkim.sock")
++ [ "unix:/run/rspamd/rspamd-milter.sock" ];
policyd-spf = pkgs.writeText "policyd-spf.conf" cfg.policydSPFExtraConfig;
mappedFile = name: "hash:/var/lib/postfix/conf/${name}";
submissionOptions =
{
smtpd_tls_security_level = "encrypt";
smtpd_sasl_auth_enable = "yes";
smtpd_sasl_type = "dovecot";
smtpd_sasl_path = "/run/dovecot2/auth";
smtpd_sasl_security_options = "noanonymous";
smtpd_sasl_local_domain = "$myhostname";
smtpd_client_restrictions = "permit_sasl_authenticated,reject";
smtpd_sender_login_maps = "hash:/etc/postfix/vaccounts";
smtpd_sender_restrictions = "reject_sender_login_mismatch";
smtpd_recipient_restrictions = "reject_non_fqdn_recipient,reject_unknown_recipient_domain,permit_sasl_authenticated,reject";
cleanup_service_name = "submission-header-cleanup";
};
in
{
config = with cfg; lib.mkIf enable {
services.postfix = {
enable = true;
hostname = "${sendingFqdn}";
networksStyle = "host";
mapFiles."valias" = valiases_file;
mapFiles."vaccounts" = vaccounts_file;
mapFiles."denied_recipients" = denied_recipients_file;
mapFiles."reject_senders" = reject_senders_file;
mapFiles."reject_recipients" = reject_recipients_file;
sslCert = certificatePath;
sslKey = keyPath;
enableSubmission = cfg.enableSubmission;
enableSubmissions = cfg.enableSubmissionSsl;
virtual = lookupTableToString (mergeLookupTables [all_valiases_postfix catchAllPostfix forwards]);
config = {
# Extra Config
mydestination = "";
recipient_delimiter = "+";
smtpd_banner = "${fqdn} ESMTP NO UCE";
disable_vrfy_command = true;
message_size_limit = toString cfg.messageSizeLimit;
# virtual mail system
virtual_uid_maps = "static:5000";
virtual_gid_maps = "static:5000";
virtual_mailbox_base = mailDirectory;
virtual_mailbox_domains = vhosts_file;
virtual_mailbox_maps = mappedFile "valias";
virtual_transport = "lmtp:unix:/run/dovecot2/dovecot-lmtp";
# sasl with dovecot
smtpd_sasl_type = "dovecot";
smtpd_sasl_path = "/run/dovecot2/auth";
smtpd_sasl_auth_enable = true;
smtpd_relay_restrictions = [
"permit_mynetworks" "permit_sasl_authenticated" "reject_unauth_destination"
];
policy-spf_time_limit = "3600s";
# reject selected senders
smtpd_sender_restrictions = [
"check_sender_access ${mappedFile "reject_senders"}"
];
# quota and spf checking
smtpd_recipient_restrictions = [
"check_recipient_access ${mappedFile "denied_recipients"}"
"check_recipient_access ${mappedFile "reject_recipients"}"
"check_policy_service inet:localhost:12340"
"check_policy_service unix:private/policy-spf"
];
# TLS settings, inspired by https://github.com/jeaye/nix-files
# Submission by mail clients is handled in submissionOptions
smtpd_tls_security_level = "may";
# strong might suffice and is computationally less expensive
smtpd_tls_eecdh_grade = "ultra";
# Disable obselete protocols
smtpd_tls_protocols = "TLSv1.3, TLSv1.2, TLSv1.1, !TLSv1, !SSLv2, !SSLv3";
smtp_tls_protocols = "TLSv1.3, TLSv1.2, TLSv1.1, !TLSv1, !SSLv2, !SSLv3";
smtpd_tls_mandatory_protocols = "TLSv1.3, TLSv1.2, TLSv1.1, !TLSv1, !SSLv2, !SSLv3";
smtp_tls_mandatory_protocols = "TLSv1.3, TLSv1.2, TLSv1.1, !TLSv1, !SSLv2, !SSLv3";
smtp_tls_ciphers = "high";
smtpd_tls_ciphers = "high";
smtp_tls_mandatory_ciphers = "high";
smtpd_tls_mandatory_ciphers = "high";
# Disable deprecated ciphers
smtpd_tls_mandatory_exclude_ciphers = "MD5, DES, ADH, RC4, PSD, SRP, 3DES, eNULL, aNULL";
smtpd_tls_exclude_ciphers = "MD5, DES, ADH, RC4, PSD, SRP, 3DES, eNULL, aNULL";
smtp_tls_mandatory_exclude_ciphers = "MD5, DES, ADH, RC4, PSD, SRP, 3DES, eNULL, aNULL";
smtp_tls_exclude_ciphers = "MD5, DES, ADH, RC4, PSD, SRP, 3DES, eNULL, aNULL";
tls_preempt_cipherlist = true;
# Allowing AUTH on a non encrypted connection poses a security risk
smtpd_tls_auth_only = true;
# Log only a summary message on TLS handshake completion
smtpd_tls_loglevel = "1";
# Configure a non blocking source of randomness
tls_random_source = "dev:/dev/urandom";
smtpd_milters = smtpdMilters;
non_smtpd_milters = lib.mkIf cfg.dkimSigning ["unix:/run/opendkim/opendkim.sock"];
milter_protocol = "6";
milter_mail_macros = "i {mail_addr} {client_addr} {client_name} {auth_type} {auth_authen} {auth_author} {mail_addr} {mail_host} {mail_mailer}";
};
submissionOptions = submissionOptions;
submissionsOptions = submissionOptions;
masterConfig = {
"policy-spf" = {
type = "unix";
privileged = true;
chroot = false;
command = "spawn";
args = [ "user=nobody" "argv=${pkgs.pypolicyd-spf}/bin/policyd-spf" "${policyd-spf}"];
};
"submission-header-cleanup" = {
type = "unix";
private = false;
chroot = false;
maxproc = 0;
command = "cleanup";
args = ["-o" "header_checks=pcre:${submissionHeaderCleanupRules}"];
};
};
};
};
}