🔒 Limited permissions for uploaded files to 0644 (#21841)

Fixes
https://linear.app/ghost/issue/ENG-1010/uploaded-file-permission-security-improvement

- This commit ensures all files uploaded to Ghost via importer are set
with 0644 permissions to improve security.
- Uploaded files previously retained their original permissions, which
could leave them executable.
- This commit prevents files from being inadvertently executable.

ghost/core/core/server/data/importer/import-manager.js

@@ -225,6 +225,10 @@ class ImportManager {
 
         try {
             await extract(filePath, tmpDir);
+            
+            // Set permissions for all extracted files
+            const files = glob.sync('**/*', {cwd: tmpDir, nodir: true});
+            await Promise.all(files.map(file => fs.chmod(path.join(tmpDir, file), 0o644)));
         } catch (err) {
             if (err.message.startsWith('ENAMETOOLONG:')) {
                 // The file was probably zipped with MacOS zip utility. Which doesn't correctly set UTF-8 encoding flag.

ghost/core/test/unit/server/data/importer/import-manager.test.js

@@ -0,0 +1,25 @@
+const should = require('should');
+const fs = require('fs-extra');
+const path = require('path');
+const glob = require('glob');
+const importManager = require('../../../../../core/server/data/importer/import-manager');
+
+describe('Import Manager', function () {
+    describe('extractZip', function () {
+        it('extracts zip file and sets correct file permissions', async function () {
+            const zipPath = path.join(__dirname, '/test.zip');
+            const extractedPath = await importManager.extractZip(zipPath);
+            try {
+                const files = glob.sync('**/*', {cwd: extractedPath, nodir: true});
+                files.forEach((file) => {
+                    const filePath = path.join(extractedPath, file);
+                    const stats = fs.statSync(filePath);
+                    const fileMode = stats.mode & 0o777;
+                    should.equal(fileMode, 0o644, `File ${file} should have 0644 permissions`);
+                });
+            } finally {
+                await fs.remove(extractedPath);
+            }
+        });
+    });
+});