fix: constrain preview page and agent parameters to safe scalar values

server/src/main/java/cn/keking/web/controller/OnlinePreviewController.java

@@ -86,8 +86,8 @@ public class OnlinePreviewController {
 
         highlightall= KkFileUtils.htmlEscape(highlightall);
         model.addAttribute("highlightall", highlightall);
-        model.addAttribute("page", page);
+        model.addAttribute("page", normalizePage(page));
-        model.addAttribute("kkagent", kkagent);
+        model.addAttribute("kkagent", Boolean.toString(Boolean.parseBoolean(kkagent)));
         model.addAttribute("file", fileAttribute);
         FilePreview filePreview = previewFactory.get(fileAttribute);
         logger.info("预览文件url：{}，previewType：{}", fileUrl, fileAttribute.getType());
@@ -98,6 +98,17 @@ public class OnlinePreviewController {
         return filePreview.filePreviewHandle(fileUrl, model, fileAttribute);  //统一在这里处理 url
     }
 
+    private static String normalizePage(String page) {
+        if (page != null && page.matches("[0-9]{1,10}")) {
+            try {
+                return Integer.toString(Integer.parseInt(page));
+            } catch (NumberFormatException ignored) {
+                // Out-of-range values use the same default as missing values.
+            }
+        }
+        return "0";
+    }
+
     @GetMapping( "/picturesPreview")
     public String picturesPreview(@RequestParam String urls,
                                   @RequestParam(required = false) String key,

server/src/test/java/cn/keking/web/controller/PreviewParameterSecurityTests.java

@@ -0,0 +1,84 @@
+package cn.keking.web.controller;
+
+import cn.keking.config.ConfigConstants;
+import cn.keking.model.FileAttribute;
+import cn.keking.service.FileHandlerService;
+import cn.keking.service.FilePreview;
+import cn.keking.service.FilePreviewFactory;
+import freemarker.template.Configuration;
+import jakarta.servlet.http.HttpServletRequest;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.ui.ExtendedModelMap;
+
+import java.io.StringWriter;
+import java.util.Base64;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PreviewParameterSecurityTests {
+    private String previousKey;
+    @BeforeEach void setup() {
+        previousKey = ConfigConstants.getKey();
+        ConfigConstants.setKeyValue("false");
+    }
+    @AfterEach void restore() { ConfigConstants.setKeyValue(previousKey); }
+
+    private ExtendedModelMap preview(String page, String agent) {
+        FileHandlerService handler = new FileHandlerService(null) {
+            @Override public FileAttribute getFileAttribute(String url, HttpServletRequest request) {
+                FileAttribute file = new FileAttribute();
+                file.setName("document.pdf");
+                file.setSuffix("pdf");
+                return file;
+            }
+        };
+        FilePreviewFactory factory = new FilePreviewFactory(null) {
+            @Override public FilePreview get(FileAttribute file) {
+                return (url, model, attribute) -> {
+                    model.addAttribute("pdfUrl", url);
+                    return "pdf";
+                };
+            }
+        };
+        ExtendedModelMap model = new ExtendedModelMap();
+        OnlinePreviewController controller = new OnlinePreviewController(factory, handler, null, null);
+        String url = Base64.getEncoder().encodeToString("https://files.example/document.pdf".getBytes());
+        assertEquals("pdf", controller.onlinePreview(url, null, null, "false", page, agent,
+                model, new MockHttpServletRequest()));
+        return model;
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"';alert(1);//", "\";alert(1);//", "1</script><script>alert(1)</script>",
+            "1;alert(1)", "-1", "2147483648", "999999999999999999999"})
+    void rendersOnlySafeScalarValuesThroughControllerAndPdfTemplate(String payload) throws Exception {
+        ExtendedModelMap model = preview(payload, payload);
+        assertEquals("0", model.get("page"));
+        assertEquals("false", model.get("kkagent"));
+        model.put("baseUrl", "https://preview.example/");
+        for (String name : new String[]{"watermarkXSpace", "watermarkYSpace", "watermarkAlpha",
+                "watermarkWidth", "watermarkHeight", "watermarkAngle"}) {
+            model.put(name, "0");
+        }
+        Configuration cfg = new Configuration(Configuration.VERSION_2_3_32);
+        cfg.setClassForTemplateLoading(getClass(), "/web");
+        cfg.setClassicCompatible(true);
+        StringWriter output = new StringWriter();
+        cfg.getTemplate("pdf.ftl").process(model, output);
+        String html = output.toString();
+        assertTrue(html.contains("var kkagent = 'false';"));
+        assertTrue(html.contains("#page=0"));
+        assertFalse(html.contains("alert(1)"));
+    }
+
+    @Test void preservesSupportedValues() {
+        assertEquals("12", preview("0012", "false").get("page"));
+        assertEquals("2147483647", preview("2147483647", "true").get("page"));
+        assertEquals("true", preview("1", "true").get("kkagent"));
+    }
+}