Merge "linker: fix error message for inaccessible libs"

linker/linker.cpp

@@ -1433,6 +1433,8 @@ static bool find_library_internal(android_namespace_t* ns,
 
   if (search_linked_namespaces) {
     // if a library was not found - look into linked namespaces
+    // preserve current dlerror in the case it fails.
+    DlErrorRestorer dlerror_restorer;
     for (auto& linked_namespace : ns->linked_namespaces()) {
       if (find_library_in_linked_namespace(linked_namespace,
                                            task)) {

linker/linker_globals.h

@@ -32,6 +32,7 @@
 #include <link.h>
 #include <stddef.h>
 
+#include <string>
 #include <unordered_map>
 
 #include <async_safe/log.h>
@@ -39,7 +40,6 @@
 #define DL_ERR(fmt, x...) \
     do { \
       async_safe_format_buffer(linker_get_error_buffer(), linker_get_error_buffer_size(), fmt, ##x); \
-      /* If LD_DEBUG is set high enough, log every dlerror(3) message. */ \
     } while (false)
 
 #define DL_WARN(fmt, x...) \
@@ -75,4 +75,16 @@ extern std::unordered_map<uintptr_t, soinfo*> g_soinfo_handles_map;
 char* linker_get_error_buffer();
 size_t linker_get_error_buffer_size();
 
+class DlErrorRestorer {
+ public:
+  DlErrorRestorer() {
+    saved_error_msg_ = linker_get_error_buffer();
+  }
+  ~DlErrorRestorer() {
+    strlcpy(linker_get_error_buffer(), saved_error_msg_.c_str(), linker_get_error_buffer_size());
+  }
+ private:
+  std::string saved_error_msg_;
+};
+
 #endif  /* __LINKER_GLOBALS_H */

tests/dlext_test.cpp

@@ -1589,6 +1589,54 @@ TEST(dlext, ns_isolated_rtld_global) {
   ASSERT_STREQ("dlopen failed: library \"libnstest_public.so\" not found", dlerror());
 }
 
+TEST(dlext, ns_inaccessible_error_message) {
+  // We set up 2 namespaces (a and b) and link a->b with a shared library
+  // libtestshared.so. Then try to dlopen different library with the same
+  // name from in namespace a. Note that library should not be accessible
+  // in either namespace but since it's soname is in the list of shared libs
+  // the linker will attempt to find it in linked namespace.
+  //
+  // Check the error message and make sure it mentions correct namespace name.
+  ASSERT_TRUE(android_init_anonymous_namespace(g_core_shared_libs.c_str(), nullptr));
+
+  android_namespace_t* ns_a =
+          android_create_namespace("ns_a",
+                                   nullptr,
+                                   (get_testlib_root() + "/private_namespace_libs").c_str(),
+                                   ANDROID_NAMESPACE_TYPE_ISOLATED,
+                                   nullptr,
+                                   nullptr);
+  ASSERT_TRUE(ns_a != nullptr) << dlerror();
+  ASSERT_TRUE(android_link_namespaces(ns_a, nullptr, g_core_shared_libs.c_str())) << dlerror();
+
+  android_namespace_t* ns_b =
+          android_create_namespace("ns_b",
+                                   nullptr,
+                                   get_testlib_root().c_str(),
+                                   ANDROID_NAMESPACE_TYPE_ISOLATED,
+                                   nullptr,
+                                   nullptr);
+  ASSERT_TRUE(ns_b != nullptr) << dlerror();
+  ASSERT_TRUE(android_link_namespaces(ns_b, nullptr, g_core_shared_libs.c_str())) << dlerror();
+
+  ASSERT_TRUE(android_link_namespaces(ns_a, ns_b, "libtestshared.so")) << dlerror();
+
+  android_dlextinfo extinfo;
+  extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
+  extinfo.library_namespace = ns_a;
+
+  std::string library_path = get_testlib_root() + "/inaccessible_libs/libtestshared.so";
+
+  void* handle = android_dlopen_ext(library_path.c_str(), RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle == nullptr);
+  std::string expected_dlerror =
+      android::base::StringPrintf("dlopen failed: library \"%s\" needed or dlopened by \"%s\""
+                                  " is not accessible for the namespace \"ns_a\"",
+                                  library_path.c_str(),
+                                  get_executable_path().c_str());
+  ASSERT_EQ(expected_dlerror, dlerror());
+}
+
 TEST(dlext, ns_anonymous) {
   static const char* root_lib = "libnstest_root.so";
   std::string shared_libs = g_core_shared_libs + ":" + g_public_lib;

tests/libs/Android.bp

@@ -439,6 +439,16 @@ cc_test_library {
     srcs: ["empty.cpp"],
 }
 
+// -----------------------------------------------------------------------------
+// Library for inaccessible shared library test
+// -----------------------------------------------------------------------------
+cc_test_library {
+    name: "libtestshared",
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["empty.cpp"],
+    relative_install_path: "/inaccessible_libs",
+}
+
 // -----------------------------------------------------------------------------
 // Library with weak undefined function
 // -----------------------------------------------------------------------------