fix: recursive check

fileutils/copy_test.go

@@ -0,0 +1,74 @@
+package fileutils
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+)
+
+// Copying an in-scope directory that contains a symlink whose target escapes
+// the user's scope must not dereference that symlink into the destination.
+// Otherwise a scoped user could exfiltrate out-of-scope file content via the
+// recursive copy path (GHSA-c2gv-wf5f-hjhh, an incomplete fix of
+// GHSA-239w-m3h6-ch8v).
+func TestCopyDoesNotDereferenceEscapingSymlink(t *testing.T) {
+	base := t.TempDir()
+	scope := filepath.Join(base, "scope")
+	if err := os.MkdirAll(filepath.Join(scope, "srcdir"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	// A secret living outside the scope.
+	secret := filepath.Join(base, "secret.txt")
+	if err := os.WriteFile(secret, []byte("OUT-OF-SCOPE-SECRET"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	// An escaping symlink planted inside the user's scope.
+	if err := os.Symlink(secret, filepath.Join(scope, "srcdir", "link.txt")); err != nil {
+		t.Skipf("cannot create symlink: %v", err)
+	}
+
+	afs := afero.NewBasePathFs(afero.NewOsFs(), scope)
+
+	err := Copy(afs, "/srcdir", "/dstdir", 0o644, 0o755)
+	if err == nil {
+		t.Fatal("expected copy of a directory containing an escaping symlink to fail")
+	}
+
+	// The escaping symlink's target content must not have landed in scope.
+	if data, readErr := afero.ReadFile(afs, "/dstdir/link.txt"); readErr == nil {
+		t.Fatalf("escaping symlink was dereferenced into scope: got %q", string(data))
+	}
+}
+
+// A symlink whose target stays within scope is legitimate and must still be
+// copied (dereferenced) so the fix does not over-block normal usage.
+func TestCopyAllowsInScopeSymlink(t *testing.T) {
+	scope := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(scope, "srcdir", "real"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(scope, "srcdir", "real", "f.txt"), []byte("in-scope"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink(filepath.Join(scope, "srcdir", "real", "f.txt"), filepath.Join(scope, "srcdir", "link.txt")); err != nil {
+		t.Skipf("cannot create symlink: %v", err)
+	}
+
+	afs := afero.NewBasePathFs(afero.NewOsFs(), scope)
+
+	if err := Copy(afs, "/srcdir", "/dstdir", 0o644, 0o755); err != nil {
+		t.Fatalf("expected copy of an in-scope symlink to succeed, got: %v", err)
+	}
+
+	data, err := afero.ReadFile(afs, "/dstdir/link.txt")
+	if err != nil {
+		t.Fatalf("expected in-scope symlink to be copied, got: %v", err)
+	}
+	if string(data) != "in-scope" {
+		t.Fatalf("unexpected copied content: %q", string(data))
+	}
+}

fileutils/dir.go

@@ -3,14 +3,24 @@ package fileutils
 import (
 	"errors"
 	"io/fs"
+	"os"
 
 	"github.com/spf13/afero"
+
+	"github.com/filebrowser/filebrowser/v2/files"
 )
 
 // CopyDir copies a directory from source to dest and all
 // of its sub-directories. It doesn't stop if it finds an error
 // during the copy. Returns an error if any.
 func CopyDir(afs afero.Fs, source, dest string, fileMode, dirMode fs.FileMode) error {
+	if ok, err := files.WithinScope(afs, source); err != nil || !ok {
+		if err != nil {
+			return err
+		}
+		return os.ErrPermission
+	}
+
 	// Get properties of source.
 	srcinfo, err := afs.Stat(source)
 	if err != nil {

fileutils/file.go

@@ -8,6 +8,8 @@ import (
 	"path/filepath"
 
 	"github.com/spf13/afero"
+
+	"github.com/filebrowser/filebrowser/v2/files"
 )
 
 // MoveFile moves file from src to dst.
@@ -32,6 +34,13 @@ func MoveFile(afs afero.Fs, src, dst string, fileMode, dirMode fs.FileMode) erro
 // CopyFile copies a file from source to dest and returns
 // an error if any.
 func CopyFile(afs afero.Fs, source, dest string, fileMode, dirMode fs.FileMode) error {
+	if ok, err := files.WithinScope(afs, source); err != nil || !ok {
+		if err != nil {
+			return err
+		}
+		return os.ErrPermission
+	}
+
 	// Open the source file.
 	src, err := afs.Open(source)
 	if err != nil {