From 30b97d7ccaf25324926301524d040c4524470046 Mon Sep 17 00:00:00 2001
From: "Dino A. Dai Zovi" <ddz@theta44.org>
Date: Mon, 5 Jul 2021 14:08:35 +0000
Subject: [PATCH] nixos/stage1: copy initrd secrets into place after special
 mounts

This modifies initialRamdiskSecretAppender to stage secrets in
/.initrd-secrets/ and stage-1-init to copy them into place after mounting
special file systems. This allows secrets to be copied into ramfs mounts
like /run/keys for use after stage-1 finishes without copying them to disk
(which would not be very secure).
---
 nixos/modules/system/boot/stage-1-init.sh | 12 ++++++++++++
 nixos/modules/system/boot/stage-1.nix     |  4 ++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/system/boot/stage-1-init.sh b/nixos/modules/system/boot/stage-1-init.sh
index ddaf985878e..82e39c96fac 100644
--- a/nixos/modules/system/boot/stage-1-init.sh
+++ b/nixos/modules/system/boot/stage-1-init.sh
@@ -119,6 +119,18 @@ specialMount() {
 }
 source @earlyMountScript@
 
+# Copy initrd secrets from /.initrd-secrets to their actual destinations
+if [ -d "/.initrd-secrets" ]; then
+    #
+    # Secrets are named by their full destination pathname and stored
+    # under /.initrd-secrets/
+    #
+    for secret in $(cd "/.initrd-secrets"; find . -type f); do
+        mkdir -p $(dirname "/$secret")
+        cp "/.initrd-secrets/$secret" "$secret"
+    done
+fi
+
 # Log the script output to /dev/kmsg or /run/log/stage-1-init.log.
 mkdir -p /tmp
 mkfifo /tmp/stage-1-init.log.fifo
diff --git a/nixos/modules/system/boot/stage-1.nix b/nixos/modules/system/boot/stage-1.nix
index d606d473d91..95c419deb70 100644
--- a/nixos/modules/system/boot/stage-1.nix
+++ b/nixos/modules/system/boot/stage-1.nix
@@ -380,8 +380,8 @@ let
         ${lib.concatStringsSep "\n" (mapAttrsToList (dest: source:
             let source' = if source == null then dest else toString source; in
               ''
-                mkdir -p $(dirname "$tmp/${dest}")
-                cp -a ${source'} "$tmp/${dest}"
+                mkdir -p $(dirname "$tmp/.initrd-secrets/${dest}")
+                cp -a ${source'} "$tmp/.initrd-secrets/${dest}"
               ''
           ) config.boot.initrd.secrets)
          }