fix(browser): block upload symlink escapes (#21972)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 4381ef9a4d
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Reviewed-by: @mbelinky

src/browser/paths.ts

@@ -1,4 +1,5 @@
 import path from "node:path";
+import { SafeOpenError, openFileWithinRoot } from "../infra/fs-safe.js";
 import { resolvePreferredOpenClawTmpDir } from "../infra/tmp-openclaw-dir.js";
 
 export const DEFAULT_BROWSER_TMP_DIR = resolvePreferredOpenClawTmpDir();
@@ -47,3 +48,45 @@ export function resolvePathsWithinRoot(params: {
   }
   return { ok: true, paths: resolvedPaths };
 }
+
+export async function resolveExistingPathsWithinRoot(params: {
+  rootDir: string;
+  requestedPaths: string[];
+  scopeLabel: string;
+}): Promise<{ ok: true; paths: string[] } | { ok: false; error: string }> {
+  const resolvedPaths: string[] = [];
+  for (const raw of params.requestedPaths) {
+    const pathResult = resolvePathWithinRoot({
+      rootDir: params.rootDir,
+      requestedPath: raw,
+      scopeLabel: params.scopeLabel,
+    });
+    if (!pathResult.ok) {
+      return { ok: false, error: pathResult.error };
+    }
+
+    const rootDir = path.resolve(params.rootDir);
+    const relativePath = path.relative(rootDir, pathResult.path);
+    let opened: Awaited<ReturnType<typeof openFileWithinRoot>> | undefined;
+    try {
+      opened = await openFileWithinRoot({
+        rootDir,
+        relativePath,
+      });
+      resolvedPaths.push(opened.realPath);
+    } catch (err) {
+      if (err instanceof SafeOpenError && err.code === "not-found") {
+        // Preserve historical behavior for paths that do not exist yet.
+        resolvedPaths.push(pathResult.path);
+        continue;
+      }
+      return {
+        ok: false,
+        error: `Invalid path: must stay within ${params.scopeLabel} and be a regular non-symlink file`,
+      };
+    } finally {
+      await opened?.handle.close().catch(() => {});
+    }
+  }
+  return { ok: true, paths: resolvedPaths };
+}