fix(vm): create the jailer chroot base directory

Jailer 1.17 canonicalizes --chroot-base-dir and exits with 'Failed to
canonicalize path' when it does not exist, so every jailed VM failed to
boot on a fresh state directory. Create <state>/jail (0700) at driver
start. Found running the VM integration tests with the jailer as root.

commit: ed21f4fd1e3a994feba33bbdd2899648e63ec823
author: brice · 9d ago · 2026-10-12 21:09 UTC
parent: e917abe
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +22 -0

M internal/sandbox/vm/driver.go +5 -0


@@ -121,6 +121,11 @@ func New(ctx context.Context, cfg sandbox.Config, opt Options) (*Driver, error)
121	121		fail := func(err error) (*Driver, error) { _ = d.Close(); return nil, err }
122	122
123	123		if !cfg.JailerOff {
	124	+	// Jailer 1.17 canonicalizes --chroot-base-dir and fails when it does not
	125	+	// exist ("Failed to canonicalize path"); older releases created it.
	126	+	if err := os.MkdirAll(jailBase(cfg.StateDir), 0o700); err != nil {
	127	+	return fail(fmt.Errorf("jailer chroot base: %w", err))
	128	+	}
124	129		for _, p := range []string{cfg.KernelPath(), cfg.BaseImagePath()} {
125	130		if err := checkWorldReadable(p); err != nil {
126	131		return fail(err)


@@ -121,6 +121,11 @@ func New(ctx context.Context, cfg sandbox.Config, opt Options) (*Driver, error)
121	fail := func(err error) (*Driver, error) { _ = d.Close(); return nil, err }	121		fail := func(err error) (*Driver, error) { _ = d.Close(); return nil, err }
122		122
123	if !cfg.JailerOff {	123		if !cfg.JailerOff {
		124	+	// Jailer 1.17 canonicalizes --chroot-base-dir and fails when it does not
		125	+	// exist ("Failed to canonicalize path"); older releases created it.
		126	+	if err := os.MkdirAll(jailBase(cfg.StateDir), 0o700); err != nil {
		127	+	return fail(fmt.Errorf("jailer chroot base: %w", err))
		128	+	}
124	for _, p := range []string{cfg.KernelPath(), cfg.BaseImagePath()} {	129		for _, p := range []string{cfg.KernelPath(), cfg.BaseImagePath()} {
125	if err := checkWorldReadable(p); err != nil {	130		if err := checkWorldReadable(p); err != nil {
126	return fail(err)	131		return fail(err)

M internal/sandbox/vm/vm_test.go +17 -0


@@ -1022,3 +1022,20 @@ func TestRemoveCgroup(t *testing.T) {
1022	1022		t.Fatal("a non-empty cgroup cannot be removed and must be reported")
1023	1023		}
1024	1024		}
	1025	+
	1026	+	// Jailer 1.17 canonicalizes --chroot-base-dir and exits when it does not exist:
	1027	+	// the driver must create it (seen on a real host, invisible with the jailer off).
	1028	+	func TestNewCreatesTheJailerChrootBase(t *testing.T) {
	1029	+	e := newEnv(t, "ok")
	1030	+	e.cfg.JailerOff = false
	1031	+	e.cfg.Jailer = e.cfg.Firecracker // any executable: it is only resolved here
	1032	+	d, err := New(context.Background(), e.cfg, Options{Run: e.run, Net: e.plumb, BootTimeout: 5 * time.Second})
	1033	+	if err != nil {
	1034	+	t.Fatal(err)
	1035	+	}
	1036	+	defer func() { _ = d.Close() }()
	1037	+	st, err := os.Stat(jailBase(e.cfg.StateDir))
	1038	+	if err != nil \|\| !st.IsDir() {
	1039	+	t.Fatalf("jail base not created: %v", err)
	1040	+	}
	1041	+	}


@@ -1022,3 +1022,20 @@ func TestRemoveCgroup(t *testing.T) {
1022	t.Fatal("a non-empty cgroup cannot be removed and must be reported")	1022		t.Fatal("a non-empty cgroup cannot be removed and must be reported")
1023	}	1023		}
1024	}	1024		}
		1025	+
		1026	+	// Jailer 1.17 canonicalizes --chroot-base-dir and exits when it does not exist:
		1027	+	// the driver must create it (seen on a real host, invisible with the jailer off).
		1028	+	func TestNewCreatesTheJailerChrootBase(t *testing.T) {
		1029	+	e := newEnv(t, "ok")
		1030	+	e.cfg.JailerOff = false
		1031	+	e.cfg.Jailer = e.cfg.Firecracker // any executable: it is only resolved here
		1032	+	d, err := New(context.Background(), e.cfg, Options{Run: e.run, Net: e.plumb, BootTimeout: 5 * time.Second})
		1033	+	if err != nil {
		1034	+	t.Fatal(err)
		1035	+	}
		1036	+	defer func() { _ = d.Close() }()
		1037	+	st, err := os.Stat(jailBase(e.cfg.StateDir))
		1038	+	if err != nil \|\| !st.IsDir() {
		1039	+	t.Fatalf("jail base not created: %v", err)
		1040	+	}
		1041	+	}