fix(wiki): close symlink TOCTOU and size-bypass in scan; single-read binary hash

mateclaw-server/src/main/java/vip/mate/wiki/service/WikiDirectoryScanService.java

@@ -148,14 +148,35 @@ public class WikiDirectoryScanService {
                     skipped++;
                     continue;
                 }
-                String absolutePath = file.toAbsolutePath().normalize().toString();
+                // From here on operate ONLY on the resolved real path, never the
+                // original entry. Reading `realFile` (a concrete, fully-resolved
+                // path) closes the TOCTOU window: swapping the symlink after
+                // resolution cannot redirect the read. The file name for the
+                // title still comes from the directory entry the user sees.
+                // Re-check the size on the resolved target — walkFileTree does
+                // not follow links, so a symlink's attribute size (the link
+                // length) can slip an oversized target past the visitFile gate.
+                long realSize;
+                try {
+                    realSize = Files.size(realFile);
+                } catch (IOException e) {
+                    errors.add("Failed to stat: " + file.getFileName() + " (" + e.getMessage() + ")");
+                    skipped++;
+                    continue;
+                }
+                if (realSize > properties.getMaxScanFileSize()) {
+                    errors.add("Skipped oversized file: " + file.getFileName() + " (" + realSize + " bytes)");
+                    skipped++;
+                    continue;
+                }
+                String absolutePath = realFile.toString();
                 String fileName = file.getFileName().toString();
                 String ext = getExtension(fileName);
 
                 if (TEXT_EXTENSIONS.contains(ext)) {
                     // Text files: dedup by content hash, so an unchanged file is
                     // skipped while a modified file (new hash) is re-ingested.
-                    String content = Files.readString(file, StandardCharsets.UTF_8);
+                    String content = Files.readString(realFile, StandardCharsets.UTF_8);
                     boolean fresh = rawService.ingestTextFileFromScan(kbId, fileName, absolutePath, content);
                     if (fresh) {
                         added++;
@@ -177,7 +198,7 @@ public class WikiDirectoryScanService {
                     default -> "text";
                 };
                 boolean freshBinary = rawService.ingestBinaryFileFromScan(
-                        kbId, fileName, sourceType, absolutePath, Files.size(file));
+                        kbId, fileName, sourceType, absolutePath, realSize);
                 if (freshBinary) {
                     added++;
                 } else {

mateclaw-server/src/main/java/vip/mate/wiki/service/WikiRawMaterialService.java

@@ -142,7 +142,8 @@ public class WikiRawMaterialService {
                 return false; // unchanged — addFile not called, avoids a second read
             }
         }
-        addFile(kbId, title, sourceType, absolutePath, fileSize);
+        // Pass the hash we already computed so addFile does not re-read the file.
+        addFile(kbId, title, sourceType, null, absolutePath, fileSize, hash);
         return true;
     }
 
@@ -227,6 +228,19 @@ public class WikiRawMaterialService {
     @Transactional
     public WikiRawMaterialEntity addFile(Long kbId, String title, String sourceType,
                                           String mimeType, String sourcePath, long fileSize) {
+        return addFile(kbId, title, sourceType, mimeType, sourcePath, fileSize, null);
+    }
+
+    /**
+     * As {@link #addFile(Long, String, String, String, String, long)}, but with
+     * an optional precomputed content hash so a caller that already read the
+     * file (e.g. the directory scan's change detection) does not pay a second
+     * full-file read to dedup.
+     */
+    @Transactional
+    public WikiRawMaterialEntity addFile(Long kbId, String title, String sourceType,
+                                          String mimeType, String sourcePath, long fileSize,
+                                          String precomputedHash) {
         WikiRawMaterialEntity entity = new WikiRawMaterialEntity();
         entity.setKbId(kbId);
         entity.setTitle(title);
@@ -240,11 +254,15 @@ public class WikiRawMaterialService {
         // directly — the previous `new String(bytes, UTF_8)` round-trip produced unstable
         // hashes for binary files (PDF/Office) because invalid UTF-8 sequences become
         // replacement characters, collapsing distinct files into the same hash.
-        try {
-            byte[] bytes = java.nio.file.Files.readAllBytes(java.nio.file.Paths.get(sourcePath));
-            entity.setContentHash(computeHashOfBytes(bytes));
-        } catch (Exception e) {
-            log.warn("[Wiki] Could not compute file hash for dedup: {}", e.getMessage());
+        if (precomputedHash != null) {
+            entity.setContentHash(precomputedHash);
+        } else {
+            try {
+                byte[] bytes = java.nio.file.Files.readAllBytes(java.nio.file.Paths.get(sourcePath));
+                entity.setContentHash(computeHashOfBytes(bytes));
+            } catch (Exception e) {
+                log.warn("[Wiki] Could not compute file hash for dedup: {}", e.getMessage());
+            }
         }
 
         // Dedup: reuse any existing row with the same hash in this KB (any status)

mateclaw-server/src/test/java/vip/mate/wiki/service/WikiScanSizeGuardE2ETest.java

@@ -0,0 +1,60 @@
+package vip.mate.wiki.service;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Verifies the scan re-checks the resolved target's size, so an oversized file
+ * reached through a symlink (whose own attribute size is just the link length)
+ * cannot slip past the max-scan-file-size gate.
+ */
+@SpringBootTest(
+        webEnvironment = SpringBootTest.WebEnvironment.NONE,
+        properties = {
+                "spring.flyway.enabled=true",
+                "spring.flyway.locations=classpath:db/migration/h2",
+                "mateclaw.feature-flag.refresh-ms=999999",
+                "mate.wiki.auto-process-on-upload=false",
+                "mate.wiki.max-scan-file-size=200"
+        }
+)
+class WikiScanSizeGuardE2ETest {
+
+    @Autowired
+    private WikiDirectoryScanService scanService;
+
+    private static final java.util.concurrent.atomic.AtomicLong SEQ =
+            new java.util.concurrent.atomic.AtomicLong(System.nanoTime());
+
+    @Test
+    void oversizedTargetReachedViaSymlink_isSkipped(@TempDir Path dir) throws IOException {
+        // 5000-byte file far exceeds the 200-byte cap; a RELATIVE symlink to it
+        // has a tiny attribute size (the short link path) that passes the
+        // visitFile gate, so only the resolved-target re-check can stop it.
+        Path big = dir.resolve("big.pdf");
+        Files.write(big, new byte[5000]);
+        Path link = dir.resolve("link.pdf");
+        try {
+            Files.createSymbolicLink(link, big.getFileName()); // relative -> "big.pdf"
+        } catch (UnsupportedOperationException | IOException e) {
+            return; // no symlink support — skip
+        }
+
+        WikiDirectoryScanService.ScanResult result =
+                scanService.scanDirectory(SEQ.incrementAndGet(), dir.toString());
+
+        // Neither the oversized file nor the symlink to it is ingested.
+        assertEquals(0, result.added(), "oversized target must not be ingested via a symlink");
+        assertTrue(result.errors().stream().anyMatch(e -> e.contains("oversized")),
+                "the resolved-target size check should report the oversized skip");
+    }
+}