feat(gopass): load SSH keys from gopass for git platforms

- Add security.gopass.ssh-agent.enable option
- Create gopass-ssh-load systemd oneshot service
- Remove identityFile and placeholder files from SSH git host configs
- Enable ssh-agent for the user

1 files changed, 53 insertions, 2 deletions

diff --git a/modules/security/gopass/default.nix b/modules/security/gopass/default.nix
index 19191ff..a121022 100644
--- a/modules/security/gopass/default.nix
+++ b/modules/security/gopass/default.nix
@@ -8,15 +8,16 @@
 {
   options.security.gopass = {
     enable = lib.mkEnableOption "Enables gopass.";
-
     package = lib.mkOption {
       type = lib.types.package;
       default = pkgs.gopass.override { passAlias = true; };
       defaultText = lib.literalExpression "pkgs.gopass.override { passAlias = true; }";
       description = "The gopass package to use.";
     };
+    ssh-agent = {
+      enable = lib.mkEnableOption "gopass-backed SSH keys for git";
+    };
   };
-
   config = lib.mkIf config.security.gopass.enable {
     programs.password-store = {
       enable = true;
@@ -25,5 +26,55 @@
         PASSWORD_STORE_DIR = "${config.home.homeDirectory}/.local/share/pass";
       };
     };
+    systemd.user.services.gopass-ssh-load = lib.mkIf config.security.gopass.ssh-agent.enable {
+      Unit = {
+        Description = "Load SSH keys from gopass into SSH agent for git";
+        After = [
+          "gpg-agent.socket"
+          "graphical-session.target"
+        ];
+        Requires = [
+          "gpg-agent.socket"
+        ];
+        PartOf = [
+          "graphical-session.target"
+        ];
+      };
+      Service = {
+        Type = "oneshot";
+        ExecStart = "${pkgs.writeShellScript "gopass-ssh-load" ''
+          export SSH_AUTH_SOCK="$(${pkgs.gnupg}/bin/gpgconf --list-dirs agent-ssh-socket)"
+
+          if [ -z "$SSH_AUTH_SOCK" ] || [ ! -S "$SSH_AUTH_SOCK" ]; then
+            exit 1
+          fi
+
+          for key in github gitlab bitbucket codeberg sourcehut; do
+            if ${config.security.gopass.package}/bin/gopass cat "ssh/$key" > /dev/null 2>&1; then
+              tmpdir=$(mktemp -d)
+              keyfile="$tmpdir/key"
+              ${config.security.gopass.package}/bin/gopass cat "ssh/$key" > "$keyfile" 2>/dev/null
+              chmod 600 "$keyfile"
+              if ! ${pkgs.openssh}/bin/ssh-add "$keyfile" 2>/dev/null; then
+                passphrase=$(${config.security.gopass.package}/bin/gopass cat "ssh/$key/passphrase" 2>/dev/null)
+                if [ -n "$passphrase" ]; then
+                  tmpcopy=$(mktemp)
+                  cp "$keyfile" "$tmpcopy"
+                  chmod 600 "$tmpcopy"
+                  if ${pkgs.openssh}/bin/ssh-keygen -p -P "$passphrase" -N "" -f "$tmpcopy" 2>/dev/null; then
+                    ${pkgs.openssh}/bin/ssh-add "$tmpcopy" 2>/dev/null
+                  fi
+                  rm -f "$tmpcopy"
+                fi
+              fi
+              rm -rf "$tmpdir"
+            fi
+          done
+        ''}";
+      };
+      Install = {
+        WantedBy = [ "graphical-session.target" ];
+      };
+    };
   };
 }