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{ config, lib, pkgs, ... }:
with lib; let
cfg = config.local.mailHost;
imapHostname = config.local.domains.imap.main;
cert = config.security.acme.certs.${imapHostname}.directory;
inherit (config.local) users virtual;
in
{
options.local.mailHost = {
enable = mkEnableOption "mailbox host service";
mdaListen = mkOption {
type = types.str;
};
saslPort = mkOption {
type = types.port;
};
lmtpPort = mkOption {
type = types.port;
};
};
config = mkIf cfg.enable {
services = {
dovecot2 = {
enable = true;
enablePAM = false;
enableLmtp = true;
sslServerKey = "${cert}/key.pem";
sslServerCert = "${cert}/fullchain.pem";
modules = [ pkgs.dovecot_pigeonhole ];
mailUser = "vmail";
mailGroup = "vmail";
mailLocation = "maildir:~/mail";
mailPlugins.perProtocol.lmtp.enable = [ "sieve" ];
# https://github.com/NixOS/nixpkgs/issues/286859
sieve.extensions = [
"fileinto"
"mailbox"
];
extraConfig =
let
inherit (config.networking) domain;
# https://dovecot.org/list/dovecot/2019-March/115250.html
# Otra solución posible (https://serverfault.com/a/1062274/980378):
# auth_username_format = %{if;%d;eq;${domain};%Ln;%Lu}
localEntry = canonical: username: ''
${username}:::::::user=${canonical} nopassword userdb_user=${canonical}
'';
localMailboxes =
pkgs.writeText "local-mailboxes"
(concatStrings
(flatten (mapAttrsToList
(canonical: user:
map (localEntry canonical) ([ canonical ] ++ user.hardAliases))
users)));
localCerts =
flatten (mapAttrsToList
(canonical: user:
let
certNames = {
inherit canonical;
logins = [ canonical ] ++ user.hardAliases;
};
in
map (flip nameValuePair certNames) user.mail.certs)
users);
vmailCerts =
flatten (flatten (mapAttrsToList
(domain: virtual: mapAttrsToList
(username: user:
let
address = "${username}@${domain}";
certNames = {
canonical = address;
logins = [ address ];
};
in
map (flip nameValuePair certNames) user.mail.certs)
virtual.users)
virtual));
certLogins =
pkgs.writeText "cert-logins"
(concatLines (flatten (mapAttrsToList
(certPath: names: map
(addr: "${config.local.pki.byPath.${certPath}.commonName}@nodomain,${addr}:::::::user=${names.canonical}")
names.logins)
(listToAttrs (localCerts ++ vmailCerts)))));
vmailPath = "/var/lib/vmail/%{if;%d;ne;;%Ld;${domain}}";
in
''
auth_mechanisms = plain login external
ssl_ca = <${config.local.pki.ca.mail.fullchain}
ssl_require_crl = yes
ssl_verify_client_cert = yes
# Esto descarta @domain.tld de locales explícitos, pero lo exige para los demás.
# Implicación: locales implícitos sin dominio fallan en autenticar
auth_username_format = %{if;%Ld;eq;${domain};%Ln;%{if;%d;ne;;%Lu;%Ln@nodomain}}
auth_ssl_username_from_cert = yes
# TODO: los defaults de nixpkgs dejan los sockets bajo
# /run/dovecot2 con demasiados permisos rwx, arreglar
service auth {
inet_listener mta-sasl {
port = ${toString cfg.saslPort}
address = ${cfg.mdaListen}
}
}
service lmtp {
inet_listener mta-lmtp {
port = ${toString cfg.lmtpPort}
address = ${cfg.mdaListen}
}
}
# FIXME: Esta cadena de passdbs hace que 'doveadm user lookup'
# falle para usuarios locales, pero todo lo demás sirve. Parece
# ser debido a que pam no puede enumerar.
passdb {
driver = static
args = nopassword
master = yes
mechanisms = external
result_success = continue-fail
result_failure = return-fail
result_internalfail = return-fail
}
passdb {
driver = passwd-file
args = scheme=PLAIN username_format=%{master_user},%Lu ${certLogins}
mechanisms = external
override_fields = nopassword
result_failure = return-fail
result_internalfail = return-fail
}
passdb {
driver = passwd-file
args = username_format=%Ln ${vmailPath}/passwd
}
passdb {
driver = passwd-file
args = scheme=PLAIN ${localMailboxes}
# Esta es una forma de determinar si se encontró el usuario en
# el passwd-file por medio de nopassword sin realmente
# autenticarlo. Cuidado con result_success, porque si eso se
# configura mal se permite inicio de sesión con cualquier
# contraseña (!!!).
result_success = continue
result_failure = return-fail
result_internalfail = return-fail
username_filter = !*@*
}
passdb {
driver = pam
args = dovecot2
username_filter = !*@*
#TODO: algo como 'override_fields = allow_nets=...'
}
userdb {
driver = passwd-file
args = username_format=%Ln ${vmailPath}/passwd
override_fields = uid=vmail gid=vmail home=${vmailPath}/home/%Ln
}
userdb {
driver = passwd-file
args = ${localMailboxes}
result_success = continue-ok
result_internalfail = return-fail
skip = found
}
userdb {
driver = passwd
args = blocking=no
skip = notfound
}
'';
};
fail2ban.jails.dovecot.settings = {
filter = "dovecot[mode=aggressive]";
maxretry = 3;
};
};
security = {
# Necesario debido a 'enablePAM = false'
pam.services.dovecot2 = { };
acme.certs.${imapHostname} = {
inherit (config.services.dovecot2) group;
reloadServices = [ "dovecot2.service" ];
};
};
users = {
users.${config.services.dovecot2.mailUser}.uid = 995;
groups.${config.services.dovecot2.mailGroup}.gid = 993;
};
networking.firewall.allowedTCPPorts = [ 143 993 ];
local.certs.imap.enable = true;
};
}
|
