vm/windows: Move creating SSH key into install/.

This SSH key is specifically only for accessing the installed Cygwin
within the Windows VM, so we only need to expose the private key. Yes,
you heard right, the private key. It's not security-relevant because the
machine is completely read-only, only exposed to the filesystem and
networking is not available.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/build-support/vm/windows/default.nix

@@ -11,7 +11,6 @@ let
   base = import ./install {
     isoFile = winISO;
     productKey = "XXX";
-    sshPublicKey = "${snakeOilSSH}/key.pub";
   };
 
   maybeKvm64 = lib.optional (stdenv.system == "x86_64-linux") "-cpu kvm64";
@@ -33,14 +32,6 @@ let
     rootModules = o.rootModules ++ lib.singleton "virtio_net";
   });
 
-  snakeOilSSH = stdenv.mkDerivation {
-    name = "snakeoil-ssh-cygwin";
-    buildCommand = ''
-      ensureDir "$out"
-      ${openssh}/bin/ssh-keygen -t ecdsa -f "$out/key" -N ""
-    '';
-  };
-
   controllerQemuArgs = cmd: let
     preInitScript = writeScript "preinit.sh" ''
       #!${vmTools.initrdUtils}/bin/ash -e
@@ -108,7 +99,7 @@ let
 
       ${samba}/sbin/nmbd -D
       ${samba}/sbin/smbd -D
-      ${coreutils}/bin/cp -L "${snakeOilSSH}/key" /ssh.key
+      ${coreutils}/bin/cp -L "${base.sshKey}" /ssh.key
       ${coreutils}/bin/chmod 600 /ssh.key
 
       echo -n "Waiting for Windows VM to become ready"

pkgs/build-support/vm/windows/install/default.nix

@@ -1,16 +1,15 @@
 { isoFile
 , productKey
-, sshPublicKey
 }:
 
 let
-  inherit (import <nixpkgs> {}) lib runCommand;
+  inherit (import <nixpkgs> {}) lib stdenv runCommand openssh;
 
   bootstrapAfterLogin = runCommand "bootstrap.sh" {} ''
     cat > "$out" <<EOF
     mkdir -p ~/.ssh
     cat > ~/.ssh/authorized_keys <<PUBKEY
-    $(cat "${sshPublicKey}")
+    $(cat "${cygwinSshKey}/key.pub")
     PUBKEY
     ssh-host-config -y -c 'binmode ntsec' -w dummy
     cygrunsrv -S sshd
@@ -21,6 +20,14 @@ let
     EOF
   '';
 
+  cygwinSshKey = stdenv.mkDerivation {
+    name = "snakeoil-ssh-cygwin";
+    buildCommand = ''
+      ensureDir "$out"
+      ${openssh}/bin/ssh-keygen -t ecdsa -f "$out/key" -N ""
+    '';
+  };
+
   packages = [ "openssh" ];
 
 in {
@@ -36,4 +43,6 @@ in {
     cygwinPackages = packages;
     inherit productKey;
   };
+
+  sshKey = "${cygwinSshKey}/key";
 }