Add additional validation for import, Enhanced ZIP extraction in importer

2026-10-16 01:33:18 +01:00 · 2026-09-16 14:45:26 +02:00
parent 5b12c09747
commit 70646a0dd4
11 changed files with 494 additions and 21 deletions
--- a/app/Service/Import/Importers/ZipImportHelper.php
+++ b/app/Service/Import/Importers/ZipImportHelper.php
@@ -0,0 +1,129 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service\Import\Importers;
+
+use ZipArchive;
+
+/**
+ * Extracts uploaded ZIP archives with limits on file count, total uncompressed
+ * size and entry paths, so a small malicious archive can not fill the disk
+ * (decompression bomb) or write outside the target directory (zip slip).
+ */
+class ZipImportHelper
+{
+    private const int CHUNK_SIZE = 1024 * 1024;
+
+    /**
+     * @throws ImportException
+     */
+    public function extract(string $zipPath, string $targetPath): void
+    {
+        $zip = new ZipArchive;
+        $res = $zip->open($zipPath, ZipArchive::RDONLY);
+        if ($res !== true) {
+            throw new ImportException('Invalid ZIP, error code: '.$res);
+        }
+
+        try {
+            $maxFiles = (int) config('import.zip_max_files');
+            $maxUncompressedSize = (int) config('import.zip_max_uncompressed_size');
+
+            if ($zip->numFiles > $maxFiles) {
+                throw new ImportException('ZIP contains too many files, maximum is '.$maxFiles);
+            }
+
+            // Check the sizes declared in the archive before writing anything to disk
+            $declaredSize = 0;
+            for ($index = 0; $index < $zip->numFiles; $index++) {
+                $stat = $zip->statIndex($index);
+                if ($stat === false) {
+                    throw new ImportException('Invalid ZIP entry');
+                }
+                $this->validateEntryName($stat['name']);
+                $declaredSize += $stat['size'];
+                if ($declaredSize > $maxUncompressedSize) {
+                    throw new ImportException('ZIP uncompressed size exceeds the maximum of '.$maxUncompressedSize.' bytes');
+                }
+            }
+
+            // The declared sizes can be forged, so the written bytes are counted as well
+            $writtenSize = 0;
+            for ($index = 0; $index < $zip->numFiles; $index++) {
+                $stat = $zip->statIndex($index);
+                if ($stat === false) {
+                    throw new ImportException('Invalid ZIP entry');
+                }
+                $name = $stat['name'];
+                $entryPath = $targetPath.DIRECTORY_SEPARATOR.$name;
+
+                if (str_ends_with($name, '/')) {
+                    $this->ensureDirectoryExists($entryPath);
+
+                    continue;
+                }
+                $this->ensureDirectoryExists(dirname($entryPath));
+
+                $stream = $zip->getStreamIndex($index);
+                if ($stream === false) {
+                    throw new ImportException('ZIP entry "'.$name.'" can not be read');
+                }
+                $target = fopen($entryPath, 'wb');
+                if ($target === false) {
+                    fclose($stream);
+                    throw new ImportException('ZIP entry "'.$name.'" can not be extracted');
+                }
+                try {
+                    while (! feof($stream)) {
+                        $chunk = fread($stream, self::CHUNK_SIZE);
+                        if ($chunk === false) {
+                            throw new ImportException('ZIP entry "'.$name.'" can not be read');
+                        }
+                        $writtenSize += strlen($chunk);
+                        if ($writtenSize > $maxUncompressedSize) {
+                            throw new ImportException('ZIP uncompressed size exceeds the maximum of '.$maxUncompressedSize.' bytes');
+                        }
+                        fwrite($target, $chunk);
+                    }
+                } finally {
+                    fclose($target);
+                    fclose($stream);
+                }
+            }
+        } finally {
+            $zip->close();
+        }
+    }
+
+    /**
+     * @throws ImportException
+     */
+    private function validateEntryName(string $name): void
+    {
+        if ($name === '' || str_contains($name, "\0") || str_contains($name, '\\') || str_starts_with($name, '/')) {
+            throw new ImportException('ZIP contains an invalid file path: "'.$name.'"');
+        }
+        if (preg_match('/^[a-zA-Z]:/', $name) === 1) {
+            throw new ImportException('ZIP contains an invalid file path: "'.$name.'"');
+        }
+        foreach (explode('/', rtrim($name, '/')) as $segment) {
+            if ($segment === '' || $segment === '..') {
+                throw new ImportException('ZIP contains an invalid file path: "'.$name.'"');
+            }
+        }
+    }
+
+    /**
+     * @throws ImportException
+     */
+    private function ensureDirectoryExists(string $path): void
+    {
+        if (is_dir($path)) {
+            return;
+        }
+        if (! mkdir($path, 0700, true) && ! is_dir($path)) {
+            throw new ImportException('Directory "'.$path.'" can not be created');
+        }
+    }
+}