policy: normalize local policy paths

build/policy_loader.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/docker/buildx/policy"
+	"github.com/docker/buildx/util/osutil"
 	"github.com/docker/buildx/util/sourcemeta"
 	"github.com/moby/buildkit/client/llb"
 	gwclient "github.com/moby/buildkit/frontend/gateway/client"
@@ -200,7 +201,7 @@ func (p *policyPathFSRef) resolve(name string) (fs.StatFS, string, error) {
 		if err != nil {
 			return nil, "", err
 		}
-		return cwd, filepath.Clean(v), nil
+		return cwd, osutil.SanitizePath(v), nil
 	}
 
 	contextFS, err := p.getContextFS()
@@ -278,11 +279,11 @@ func normalizeLocalPolicyPath(name, contextDir string) string {
 		if rel, err := filepath.Rel(contextDir, name); err == nil {
 			rel = filepath.Clean(rel)
 			if rel != ".." && !strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
-				return rel
+				return osutil.SanitizePath(rel)
 			}
 		}
 	}
-	return filepath.Clean(name)
+	return osutil.SanitizePath(name)
 }
 
 type memoizedPolicyFS struct {

build/policy_loader_test.go

@@ -11,6 +11,55 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestLoadPolicyDataLocalPaths(t *testing.T) {
+	dir := t.TempDir()
+	policyData := []byte("package docker\n")
+	policyRelPath := filepath.Join("policy", "allow.rego")
+	require.NoError(t, os.MkdirAll(filepath.Join(dir, "policy"), 0700))
+	require.NoError(t, os.WriteFile(filepath.Join(dir, policyRelPath), policyData, 0600))
+
+	t.Run("context-relative", func(t *testing.T) {
+		provider := newPolicyPathFS(context.Background(), nil, policyOpt{
+			ContextDir: dir,
+		})
+
+		dt, ok, err := loadPolicyData(provider, policyRelPath)
+		require.NoError(t, err)
+		require.True(t, ok)
+		require.Equal(t, policyData, dt)
+	})
+
+	t.Run("context-absolute", func(t *testing.T) {
+		provider := newPolicyPathFS(context.Background(), nil, policyOpt{
+			ContextDir: dir,
+		})
+
+		dt, ok, err := loadPolicyData(provider, filepath.Join(dir, policyRelPath))
+		require.NoError(t, err)
+		require.True(t, ok)
+		require.Equal(t, policyData, dt)
+	})
+
+	t.Run("cwd", func(t *testing.T) {
+		cwd, err := os.Getwd()
+		require.NoError(t, err)
+		require.NoError(t, os.Chdir(dir))
+		t.Cleanup(func() {
+			require.NoError(t, os.Chdir(cwd))
+		})
+
+		provider := newPolicyPathFS(context.Background(), nil, policyOpt{})
+		dt, ok, err := loadPolicyData(provider, "cwd://"+policyRelPath)
+		require.NoError(t, err)
+		require.True(t, ok)
+		require.Equal(t, policyData, dt)
+	})
+}
+
+func TestNormalizeLocalPolicyPath(t *testing.T) {
+	require.Equal(t, "policy/allow.rego", normalizeLocalPolicyPath(filepath.Join("policy", "allow.rego"), ""))
+}
+
 func TestMemoizedPolicyFSRefCountedClose(t *testing.T) {
 	var initCalls int
 	var closeCalls int