install: manually label {/etc/fstab,tmpfile.d/bootc-root-ssh.conf}

Right now bootc supports an experimental install from a non-selinux
host when using the `BOOTC_SKIP_SELINUX_HOST_CHECK=1` option.

This is nice and works relatively well. However files written
during the install like /etc/fstab or the tmpfiles.dfile
in /etc/tmpfile.d/bootc-root-ssh.conf must be labeled too.

This commit adds a (rather crude) manual way to do this.

Closes #362

lib/src/install.rs

@@ -644,8 +644,16 @@ async fn initialize_ostree_root_from_self(
     }
     f.flush()?;
 
+    let fstab_path = rootfs.join("etc/fstab");
+    state.lsm_label(&fstab_path, "/etc/fstab".into(), false)?;
+
     if let Some(contents) = state.root_ssh_authorized_keys.as_deref() {
-        osconfig::inject_root_ssh_authorized_keys(&root, contents)?;
+        let tmpf_path = osconfig::inject_root_ssh_authorized_keys(&root, contents)?;
+        state.lsm_label(
+            &rootfs.join(tmpf_path.clone()),
+            &Utf8PathBuf::from("/").join(tmpf_path),
+            false,
+        )?;
     }
 
     let uname = rustix::system::uname();

lib/src/install/osconfig.rs

@@ -1,5 +1,5 @@
 use anyhow::Result;
-use camino::Utf8Path;
+use camino::{Utf8Path, Utf8PathBuf};
 use cap_std::fs::Dir;
 use cap_std_ext::{cap_std, dirext::CapStdExtDirExt};
 use fn_error_context::context;
@@ -8,7 +8,7 @@ const ETC_TMPFILES: &str = "etc/tmpfiles.d";
 const ROOT_SSH_TMPFILE: &str = "bootc-root-ssh.conf";
 
 #[context("Injecting root authorized_keys")]
-pub(crate) fn inject_root_ssh_authorized_keys(root: &Dir, contents: &str) -> Result<()> {
+pub(crate) fn inject_root_ssh_authorized_keys(root: &Dir, contents: &str) -> Result<Utf8PathBuf> {
     // While not documented right now, this one looks like it does not newline wrap
     let b64_encoded = ostree_ext::glib::base64_encode(contents.as_bytes());
     // See the example in https://systemd.io/CREDENTIALS/
@@ -18,8 +18,10 @@ pub(crate) fn inject_root_ssh_authorized_keys(root: &Dir, contents: &str) -> Res
     root.create_dir_all(tmpfiles_dir)?;
     let target = tmpfiles_dir.join(ROOT_SSH_TMPFILE);
     root.atomic_write(&target, &tmpfiles_content)?;
+
+    let as_path = Utf8Path::new(ETC_TMPFILES).join(ROOT_SSH_TMPFILE);
     println!("Injected: {target}");
-    Ok(())
+    Ok(as_path)
 }
 
 #[test]