install: Add final SELinux relabel of the physical root filesystem

Perform a full SELinux relabel pass over the physical root filesystem as
the very last step before filesystem finalization. This ensures all files
on the physical root have SELinux labels.

Files that are already labeled (e.g. ostree deployment contents,
composefs objects) are skipped since the relabel only acts on unlabeled
files.

Assisted-by: OpenCode (claude-opus-4-6)
Signed-off-by: John Eckersberg <jeckersb@redhat.com>

Author: jeckersb

crates/lib/src/install.rs

@@ -1984,6 +1984,18 @@ async fn install_to_filesystem_impl(
         ostree_install(state, rootfs, cleanup).await?;
     }
 
+    // As the very last step before filesystem finalization, do a full SELinux
+    // relabel of the physical root filesystem.  Any files that are already
+    // labeled (e.g. ostree deployment contents, composefs objects) are skipped.
+    if let Some(policy) = state.load_policy()? {
+        tracing::info!("Performing final SELinux relabeling of physical root");
+        let mut path = Utf8PathBuf::from("");
+        crate::lsm::ensure_dir_labeled_recurse(&rootfs.physical_root, &mut path, &policy, None)
+            .context("Final SELinux relabeling of physical root")?;
+    } else {
+        tracing::debug!("Skipping final SELinux relabel (SELinux is disabled)");
+    }
+
     // Finalize mounted filesystems
     if !rootfs.skip_finalize {
         let bootfs = rootfs.boot.as_ref().map(|_| ("boot", "boot"));