Undo giving full access to system libs from other system libs.

Directly extending the search path to /system/${LIB} for system APKs
may result in system libs being loaded in an app classloader namespace
rather than the system namespace. If those libs then depend on other
non-public libraries, e.g. in APEXes, that are only accessible through
links from the system namespace, then those dependencies will fail to
load because the app classloader namespace doesn't have the same links.

This CL functionally undoes https://r.android.com/2211602, but only
disables tests that break, and adds some tests to exercise the
situation above.

Also change native libs in the test to use `min_sdk_version` rather
than `sdk_version`, because now when they contain code they need an
NDK, and one with exactly version 31 is normally not available in the
build. (Otoh, the java libraries with `product_specific: true` or
`vendor: true` aren't allowed to use `min_sdk_version`.)

Test: atest -a libnativeloader_test libnativeloader_lazy_test \
        libnativeloader_e2e_tests
Bug: 258340826
Bug: 237577392
Change-Id: I95a3fbc6c8021c037fffda1423aa90c62973ec89

1 files changed, 31 insertions, 0 deletions

diff --git a/libnativeloader/test/libsystem_testlib.cc b/libnativeloader/test/libsystem_testlib.cc
new file mode 100644
index 0000000000..97d32237b4
--- /dev/null
+++ b/libnativeloader/test/libsystem_testlib.cc
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <dlfcn.h>
+
+#include "log/log.h"
+
+static void __attribute__((constructor)) ctor() {
+  // Load a library that should be available to system libraries through a
+  // linked namespace (i.e. is not directly in /system/${LIB}), and that is not
+  // in public.libraries.txt. We use a real one to avoid having to set up an
+  // APEX test fixture and rerun linkerconfig.
+  void* h = dlopen("libandroidicu.so", RTLD_NOW);
+  if (h == nullptr) {
+    LOG_ALWAYS_FATAL("Failed to load dependency: %s", dlerror());
+  }
+  dlclose(h);
+}