nix-bitcoin/modules/onion-addresses.nix

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# This module enables unprivileged users to read onion addresses.
# By default, onion addresses in /var/lib/tor/onion are only readable by the
# tor user.
# The included service copies onion addresses to /var/lib/onion-addresses/<user>/
# and sets permissions according to option 'access'.
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.nix-bitcoin.onionAddresses;
inherit (config) nix-bitcoin-services;
dataDir = "/var/lib/onion-addresses/";
onion-addresses-script = pkgs.writeScript "onion-addresses.sh" ''
# wait until tor is up
until ls -l /var/lib/tor/state; do sleep 1; done
cd ${dataDir}
# Create directory for every user and set permissions
${ builtins.foldl'
(x: user: x +
''
mkdir -p -m 0700 ${user}
chown ${user} ${user}
# Copy onion hostnames into the user's directory
${ builtins.foldl'
(x: onion: x +
''
ONION_FILE=/var/lib/tor/onion/${onion}/hostname
if [ -e "$ONION_FILE" ]; then
cp $ONION_FILE ${user}/${onion}
chown ${user} ${user}/${onion}
fi
'')
""
(builtins.getAttr user cfg.access)
}
'')
""
(builtins.attrNames cfg.access)
}
'';
in {
options.nix-bitcoin.onionAddresses = {
enable = mkOption {
type = types.bool;
default = false;
description = ''
If enabled, the onion-addresses service will be installed.
'';
};
access = mkOption {
type = types.attrs;
default = {};
description = ''
This option controls who is allowed to access onion hostnames. For
example the following allows the user operator to access the bitcoind
and clightning onion.
{
"operator" = [ "bitcoind" "clightning" ];
};
The onion hostnames can then be read from
/var/lib/onion-addresses/<user>.
'';
};
};
config = mkIf cfg.enable {
systemd.services.onion-addresses = {
description = "Run onion-addresses";
wantedBy = [ "tor.service" ];
bindsTo = [ "tor.service" ];
after = [ "tor.service" ];
serviceConfig = nix-bitcoin-services.defaultHardening // {
ExecStart = "${pkgs.bash}/bin/bash ${onion-addresses-script}";
Type = "oneshot";
RemainAfterExit = true;
StateDirectory = "onion-addresses";
PrivateNetwork = "true"; # This service needs no network access
PrivateUsers = "false";
CapabilityBoundingSet = "CAP_CHOWN CAP_FSETID CAP_SETFCAP CAP_DAC_OVERRIDE CAP_DAC_READ_SEARCH CAP_FOWNER CAP_IPC_OWNER";
};
};
};
}