Bugfix on Overlay Dracut module resilient without verity. (#8597)

Co-authored-by: lanzeliu <[email protected]>
microsoft · Apr 2, 2024 · 80d513e · 80d513e
1 parent d5689fc
commit 80d513e
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Showing 2 changed files with 44 additions and 5 deletions.
diff --git a/SPECS/dracut/20overlayfs/overlayfs-mount.sh b/SPECS/dracut/20overlayfs/overlayfs-mount.sh
@@ -30,8 +30,8 @@ parse_kernel_cmdline_args() {
     # Ensure that the 'dracut-lib' is present and loaded.
     type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 
-    VERITY_MOUNT="/mnt/verity_mnt_$$"
-    OVERLAY_MOUNT="/mnt/overlay_mnt_$$"
+    VERITY_MOUNT="/mnt/verity_mnt"
+    OVERLAY_MOUNT="/mnt/overlay_mnt"
     OVERLAY_MNT_OPTS="rw,nodev,nosuid,nouser,noexec"
 
     # Retrieve the verity root. It is expected to be predefined by the dracut cmdline module.
@@ -102,14 +102,19 @@ mount_overlayfs() {
     else
         echo "Mounting regular root"
         mkdir -p "${VERITY_MOUNT}"
-        mount -o ro,defaults "$root" "${VERITY_MOUNT}" || \
+        # Remove 'block:' prefix if present.
+        root_device=$(expand_persistent_dev "${root#block:}")
+        mount -o ro,defaults "$root_device" "${VERITY_MOUNT}" || \
             die "Failed to mount root"
     fi
 
     echo "Starting to create OverlayFS"
     for _group in ${overlayfs}; do
         IFS=',' read -r overlay upper work volume <<< "$_group"
 
+        # Resolve volume to its full device path.
+        volume=$(expand_persistent_dev "$volume")
+
         if [[ "$volume" == "" ]]; then
             overlay_mount_with_cnt="${OVERLAY_MOUNT}/${cnt}"
             mount_volatile_persistent_volume "volatile" $overlay_mount_with_cnt
@@ -135,5 +140,39 @@ mount_overlayfs() {
     mount --rbind "${VERITY_MOUNT}" "${NEWROOT}"
 }
 
+# Keep a copy of this function here from verity-read-only-root package.
+expand_persistent_dev() {
+    local _dev=$1
+
+    case "$_dev" in
+        LABEL=*)
+            _dev="/dev/disk/by-label/${_dev#LABEL=}"
+            ;;
+        UUID=*)
+            _dev="${_dev#UUID=}"
+            _dev="${_dev,,}"
+            _dev="/dev/disk/by-uuid/${_dev}"
+            ;;
+        PARTUUID=*)
+            _dev="${_dev#PARTUUID=}"
+            _dev="${_dev,,}"
+            _dev="/dev/disk/by-partuuid/${_dev}"
+            ;;
+        PARTLABEL=*)
+            _dev="/dev/disk/by-partlabel/${_dev#PARTLABEL=}"
+            ;;
+    esac
+    printf "%s" "$_dev"
+}
+
+# Parse kernel command line arguments to set environment variables.
+# This function populates variables based on the kernel command line, such as overlayfs.
 parse_kernel_cmdline_args
-mount_overlayfs
+
+# Check if the overlayfs variable is set, indicating that overlay filesystem parameters were found.
+# If not set, the process to enable and mount the overlay filesystem will be skipped.
+if [ -n "${overlayfs}" ]; then
+    mount_overlayfs
+else
+    echo "OverlayFS parameter not found in kernel cmdline, skipping mount_overlayfs."
+fi
diff --git a/SPECS/dracut/dracut.signatures.json b/SPECS/dracut/dracut.signatures.json
@@ -5,6 +5,6 @@
   "lgpl-2.1.txt": "dc626520dcd53a22f727af3ee42c770e56c97a64fe3adb063799d8ab032fe551",
   "megaraid.conf": "914824cdbe0c525b71efa05a75e453335b0068beb8bc28bef2a5866d74bf7dd4",
   "module-setup.sh": "330af5c105793fb37434730ce0ff59467a9cc60a81a5e32193dc53235e9744c1",
-  "overlayfs-mount.sh": "d6c064e383f00abae1ee621b9657e439e698dba5d49807e38c94fac795f45ea4"
+  "overlayfs-mount.sh": "e0d009b765fea58319f9b4b33f5399d6fea90f3ba98a4fdad43d80256e555027"
  }
 }