From 55231d7f824f0d80af604ce4ce91746620796e1e Mon Sep 17 00:00:00 2001
From: tagadearpit <143588157+tagadearpit@users.noreply.github.com>
Date: Fri, 14 Aug 2026 13:36:18 +0000
Subject: [PATCH] fix(unikontainers): secure container state paths

Replace filepath.Join with SecureJoin for container state directories so symlinks cannot redirect state access outside the configured root. Add regression coverage for Get and harden the delete fallback path.

Fixes: #791
Signed-off-by: tagadearpit <143588157+tagadearpit@users.noreply.github.com>
---
 .github/contributors.yaml               |  3 ++
 cmd/urunc/delete.go                     | 11 +++--
 pkg/unikontainers/path_security_test.go | 57 +++++++++++++++++++++++++
 pkg/unikontainers/unikontainers.go      | 11 ++++-
 4 files changed, 77 insertions(+), 5 deletions(-)
 create mode 100644 pkg/unikontainers/path_security_test.go

diff --git a/.github/contributors.yaml b/.github/contributors.yaml
index 7f7307a3d..e1887e214 100644
--- a/.github/contributors.yaml
+++ b/.github/contributors.yaml
@@ -128,3 +128,6 @@ users:
   OdysseasKalaitsidis:
     name: Odysseas Kalaitsidis
     email: odysseaskalaitsides@gmail.com
+  tagadearpit:
+    name: Arpit Tagade
+    email: 143588157+tagadearpit@users.noreply.github.com
diff --git a/cmd/urunc/delete.go b/cmd/urunc/delete.go
index 7ba25ec00..2be67d67b 100644
--- a/cmd/urunc/delete.go
+++ b/cmd/urunc/delete.go
@@ -17,10 +17,11 @@ package main
 import (
 	"context"
 	"errors"
+	"fmt"
 	"os"
-	"path/filepath"
 	"runtime"
 
+	securejoin "github.com/cyphar/filepath-securejoin"
 	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli/v3"
 )
@@ -62,11 +63,15 @@ status of "ubuntu01" as "stopped" the following will delete resources held for
 					return ErrEmptyContainerID
 				}
 				rootDir := cmd.String("root")
-				containerDir := filepath.Join(rootDir, containerID)
-				e := os.RemoveAll(containerDir)
+				containerDir, e := securejoin.SecureJoin(rootDir, containerID)
+				if e != nil {
+					return fmt.Errorf("failed to resolve container directory: %w", e)
+				}
+				e = os.RemoveAll(containerDir)
 				if e != nil {
 					logrus.Errorf("remove %s: %v", containerDir, e)
 				}
+
 				if cmd.Bool("force") {
 					return nil
 				}
diff --git a/pkg/unikontainers/path_security_test.go b/pkg/unikontainers/path_security_test.go
new file mode 100644
index 000000000..77bd289dc
--- /dev/null
+++ b/pkg/unikontainers/path_security_test.go
@@ -0,0 +1,57 @@
+// Copyright (c) 2023-2026, Nubificus LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package unikontainers
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetRejectsContainerDirSymlink(t *testing.T) {
+	rootDir := t.TempDir()
+	outsideDir := t.TempDir()
+	bundleDir := t.TempDir()
+
+	spec := &specs.Spec{
+		Version: "1.0.2",
+		Linux:   &specs.Linux{},
+	}
+	specData, err := json.Marshal(spec)
+	require.NoError(t, err)
+	require.NoError(t, os.WriteFile(filepath.Join(bundleDir, configFilename), specData, 0o600))
+
+	state := &specs.State{
+		Version: "1.0.2",
+		ID:      "victim",
+		Bundle:  bundleDir,
+		Annotations: map[string]string{
+			annotType:       "linux",
+			annotHypervisor: "qemu",
+		},
+	}
+	stateData, err := json.Marshal(state)
+	require.NoError(t, err)
+	require.NoError(t, os.WriteFile(filepath.Join(outsideDir, stateFilename), stateData, 0o600))
+
+	require.NoError(t, os.Symlink(outsideDir, filepath.Join(rootDir, state.ID)))
+
+	_, err = Get(state.ID, rootDir)
+	require.ErrorIs(t, err, os.ErrNotExist)
+}
diff --git a/pkg/unikontainers/unikontainers.go b/pkg/unikontainers/unikontainers.go
index ad0bf2897..6f6412aac 100644
--- a/pkg/unikontainers/unikontainers.go
+++ b/pkg/unikontainers/unikontainers.go
@@ -29,6 +29,7 @@ import (
 	"sync"
 	"syscall"
 
+	securejoin "github.com/cyphar/filepath-securejoin"
 	"github.com/urunc-dev/urunc/pkg/network"
 	"github.com/urunc-dev/urunc/pkg/unikontainers/hypervisors"
 	"github.com/urunc-dev/urunc/pkg/unikontainers/types"
@@ -93,7 +94,10 @@ func New(bundlePath string, containerID string, rootDir string, cfg *UruncConfig
 	confMap := config.Map()
 
 	maps.Copy(confMap, cfg.Map())
-	containerDir := filepath.Join(rootDir, containerID)
+	containerDir, err := securejoin.SecureJoin(rootDir, containerID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve container directory: %w", err)
+	}
 	state := &specs.State{
 		Version:     spec.Version,
 		ID:          containerID,
@@ -114,7 +118,10 @@ func New(bundlePath string, containerID string, rootDir string, cfg *UruncConfig
 // Get retrieves unikernel data from disk to create a Unikontainer object
 func Get(containerID string, rootDir string) (*Unikontainer, error) {
 	u := &Unikontainer{}
-	containerDir := filepath.Join(rootDir, containerID)
+	containerDir, err := securejoin.SecureJoin(rootDir, containerID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve container directory: %w", err)
+	}
 	stateFilePath := filepath.Join(containerDir, stateFilename)
 	state, err := loadUnikontainerState(stateFilePath)
 	if err != nil {