dotfiles.nix/modules/darwin/security/pam.nix

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2022-01-23 01:32:58 +00:00
# Upstream PR: https://github.com/LnL7/nix-darwin/pull/228
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.security.pam;
# Implementation Notes
#
# We don't use `environment.etc` because this would require that the user manually delete
# `/etc/pam.d/sudo` which seems unwise given that applying the nix-darwin configuration requires
# sudo. We also can't use `system.patchs` since it only runs once, and so won't patch in the
# changes again after OS updates (which remove modifications to this file).
#
# As such, we resort to line addition/deletion in place using `sed`. We add a comment to the
# added line that includes the name of the option, to make it easier to identify the line that
# should be deleted when the option is disabled.
mkSudoTouchIdAuthScript = isEnabled:
let
file = "/etc/pam.d/sudo";
option = "security.pam.enableSudoTouchIdAuth";
in
''
${if isEnabled then ''
# Enable sudo Touch ID authentication, if not already enabled
if ! grep 'pam_tid.so' ${file} > /dev/null; then
sed -i "" '2i\
auth sufficient pam_tid.so # nix-darwin: ${option}
' ${file}
fi
'' else ''
# Disable sudo Touch ID authentication, if added by nix-darwin
if grep '${option}' ${file} > /dev/null; then
sed -i "" '/${option}/d' ${file}
fi
''}
'';
2022-01-23 01:32:58 +00:00
in
{
options = {
security.pam.enableSudoTouchIdAuth = mkEnableOption ''
Enable sudo authentication with Touch ID
When enabled, this option adds the following line to /etc/pam.d/sudo:
auth sufficient pam_tid.so
(Note that macOS resets this file when doing a system update. As such, sudo
authentication with Touch ID won't work after a system update until the nix-darwin
configuration is reapplied.)
'';
};
config = {
system.activationScripts.extraActivation.text = ''
# PAM settings
echo >&2 "setting up pam..."
${mkSudoTouchIdAuthScript cfg.enableSudoTouchIdAuth}
'';
};
}