Ignore symbols of imported libs' dependencies

When a library is present in a namespace via the secondary_namespaces
list (i.e. the executable, LD_PRELOAD, DF_1_GLOBAL, or
android_create_namespace inheritance), then we want to search that
library's symbols, but not the symbols of its dependencies. Otherwise,
we want to search the dependencies to handle cross-NS dependency.

Bug: http://b/148569846
Test: bionic unit tests
Change-Id: If798d69de28ed5c0f1a155e4ff85c7e08934e531

linker/linker_namespaces.cpp

@@ -71,7 +71,7 @@ bool android_namespace_t::is_accessible(const std::string& file) {
 // Are symbols from this shared object accessible for symbol lookups in a library from this
 // namespace?
 bool android_namespace_t::is_accessible(soinfo* s) {
-  auto is_accessible_ftor = [this] (soinfo* si) {
+  auto is_accessible_ftor = [this] (soinfo* si, bool allow_secondary) {
     // This is workaround for apps hacking into soinfo list.
     // and inserting their own entries into it. (http://b/37191433)
     if (!si->has_min_version(3)) {
@@ -84,20 +84,37 @@ bool android_namespace_t::is_accessible(soinfo* s) {
       return true;
     }
 
-    const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
-    if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
-      return true;
+    // When we're looking up symbols, we want to search libraries from the same namespace (whether
+    // the namespace membership is primary or secondary), but we also want to search the immediate
+    // dependencies of libraries in our namespace. (e.g. Supposing that libapp.so -> libandroid.so
+    // crosses a namespace boundary, we want to search libandroid.so but not any of libandroid.so's
+    // dependencies).
+    //
+    // Some libraries may be present in this namespace via the secondary namespace list:
+    //  - the executable
+    //  - LD_PRELOAD and DF_1_GLOBAL libraries
+    //  - libraries inherited during dynamic namespace creation (e.g. because of
+    //    RTLD_GLOBAL / DF_1_GLOBAL / ANDROID_NAMESPACE_TYPE_SHARED)
+    //
+    // When a library's membership is secondary, we want to search its symbols, but not the symbols
+    // of its dependencies. The executable may depend on internal system libraries which should not
+    // be searched.
+    if (allow_secondary) {
+      const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
+      if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
+        return true;
+      }
     }
 
     return false;
   };
 
-  if (is_accessible_ftor(s)) {
+  if (is_accessible_ftor(s, true)) {
     return true;
   }
 
   return !s->get_parents().visit([&](soinfo* si) {
-    return !is_accessible_ftor(si);
+    return !is_accessible_ftor(si, false);
   });
 }
 

tests/Android.bp

@@ -722,6 +722,11 @@ cc_defaults {
         "libnstest_ns_a_public1_internal",
         "libnstest_ns_b_public2",
         "libnstest_ns_b_public3",
+        "ns_hidden_child_helper",
+        "libns_hidden_child_global",
+        "libns_hidden_child_internal",
+        "libns_hidden_child_public",
+        "libns_hidden_child_app",
         "libsegment_gap_inner",
         "libsegment_gap_outer",
         "ld_preload_test_helper",

tests/core_shared_libs.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#pragma once
+
+// A new namespace should have these libraries on a link to the default namespace.
+static constexpr const char* kCoreSharedLibs = "libc.so:libc++.so:libdl.so:libm.so";

tests/dlext_test.cpp

@@ -39,6 +39,7 @@
 #include <procinfo/process_map.h>
 #include <ziparchive/zip_archive.h>
 
+#include "core_shared_libs.h"
 #include "gtest_globals.h"
 #include "utils.h"
 #include "dlext_private.h"
@@ -713,7 +714,7 @@ std::string DlExtRelroSharingTest::FindMappingName(void* ptr) {
 static const char* g_public_lib = "libnstest_public.so";
 
 // These are libs shared with default namespace
-static const std::string g_core_shared_libs = "libc.so:libc++.so:libdl.so:libm.so";
+static const std::string g_core_shared_libs = kCoreSharedLibs;
 
 TEST(dlext, ns_smoke) {
   static const char* root_lib = "libnstest_root.so";
@@ -2055,6 +2056,23 @@ TEST(dlext, ns_anonymous) {
   ASSERT_TRUE(ns_get_dlopened_string_anon() != ns_get_dlopened_string_private());
 }
 
+TEST(dlext, ns_hidden_child) {
+  ExecTestHelper eth;
+
+  std::string helper = GetTestlibRoot() + "/ns_hidden_child_helper/ns_hidden_child_helper";
+  chmod(helper.c_str(), 0755); // TODO: "x" lost in CTS, b/34945607
+  std::string app_ns_dir = GetTestlibRoot() + "/ns_hidden_child_app";
+  eth.SetArgs({ helper.c_str(), app_ns_dir.c_str(), nullptr });
+
+  // Add the main libns_hidden_child_*.so libraries to the search path of the default namespace.
+  std::string env = "LD_LIBRARY_PATH=" + GetTestlibRoot();
+  eth.SetEnv({ env.c_str(), nullptr });
+
+  eth.Run([&]() { execve(helper.c_str(), eth.GetArgs(), eth.GetEnv()); }, 0,
+          "public_function is non-null\n"
+          "internal_function is null\n");
+}
+
 TEST(dlext, dlopen_handle_value_platform) {
   void* handle = dlopen("libtest_dlsym_from_this.so", RTLD_NOW | RTLD_LOCAL);
   ASSERT_TRUE((reinterpret_cast<uintptr_t>(handle) & 1) != 0)

tests/libs/Android.bp

@@ -468,6 +468,56 @@ cc_test_library {
     relative_install_path: "bionic-loader-test-libs/private_namespace_libs_external",
 }
 
+// -----------------------------------------------------------------------------
+// ns_hidden_child linker namespace test
+// -----------------------------------------------------------------------------
+
+cc_test {
+    name: "ns_hidden_child_helper",
+    host_supported: false,
+    defaults: ["bionic_testlib_defaults"],
+    srcs: ["ns_hidden_child_helper.cpp"],
+    shared_libs: [
+        "libns_hidden_child_internal",
+        "libns_hidden_child_global",
+        "libdl_android",
+    ],
+    ldflags: ["-Wl,--rpath,${ORIGIN}/.."],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_global",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_global.cpp"],
+    shared_libs: ["libns_hidden_child_internal"],
+    ldflags: ["-Wl,-z,global"],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_internal",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_internal.cpp"],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_public",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_public.cpp"],
+    shared_libs: ["libns_hidden_child_internal"],
+}
+
+cc_test_library {
+    name: "libns_hidden_child_app",
+    defaults: ["bionic_testlib_defaults"],
+    host_supported: false,
+    srcs: ["ns_hidden_child_app.cpp"],
+    shared_libs: ["libns_hidden_child_public"],
+    relative_install_path: "bionic-loader-test-libs/ns_hidden_child_app",
+}
+
 // -----------------------------------------------------------------------------
 // Build DT_RUNPATH test helper libraries
 //

tests/libs/ns_hidden_child_app.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+
+__attribute__((weak)) extern "C" void public_function();
+__attribute__((weak)) extern "C" void internal_function();
+
+extern "C" void app_function() {
+  printf("public_function is %s\n", public_function == nullptr ? "null" : "non-null");
+  printf("internal_function is %s\n", internal_function == nullptr ? "null" : "non-null");
+}

tests/libs/ns_hidden_child_global.cpp

@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+extern "C" void internal_function();
+
+extern "C" void global_function() {
+  internal_function();
+}

tests/libs/ns_hidden_child_helper.cpp

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <android/dlext.h>
+#include <dlfcn.h>
+#include <stdlib.h>
+
+#include <string>
+
+#include "../core_shared_libs.h"
+#include "../dlext_private.h"
+
+extern "C" void global_function();
+extern "C" void internal_function();
+
+int main(int argc, char* argv[]) {
+  if (argc != 2) {
+    fprintf(stderr, "usage: %s NS_PATH\n", argv[0]);
+    fprintf(stderr, "NS_PATH   path to the ns_hidden_child_app directory\n");
+    exit(1);
+  }
+
+  // Ensure that -Wl,--needed doesn't break the test by removing DT_NEEDED entries.
+  global_function();
+  internal_function();
+
+  const char* app_lib_dir = argv[1];
+  android_namespace_t* app_ns =
+      android_create_namespace("app", nullptr, app_lib_dir, ANDROID_NAMESPACE_TYPE_ISOLATED,
+                               nullptr, nullptr);
+  if (app_ns == nullptr) {
+    fprintf(stderr, "android_create_namespace failed: %s\n", dlerror());
+    exit(1);
+  }
+
+  std::string public_libs = std::string(kCoreSharedLibs) + ":libns_hidden_child_public.so";
+  if (!android_link_namespaces(app_ns, nullptr, public_libs.c_str())) {
+    fprintf(stderr, "android_link_namespaces failed: %s\n", dlerror());
+    exit(1);
+  }
+
+  android_dlextinfo ext = {
+    .flags = ANDROID_DLEXT_USE_NAMESPACE,
+    .library_namespace = app_ns,
+  };
+  void* app_lib = android_dlopen_ext("libns_hidden_child_app.so", RTLD_NOW | RTLD_LOCAL, &ext);
+  if (app_lib == nullptr) {
+    fprintf(stderr, "android_dlopen_ext failed: %s\n", dlerror());
+    exit(1);
+  }
+
+  auto app_function = reinterpret_cast<void(*)()>(dlsym(app_lib, "app_function"));
+  if (app_function == nullptr) {
+    fprintf(stderr, "dlsym failed to find app_function: %s\n", dlerror());
+    exit(1);
+  }
+
+  app_function();
+  return 0;
+}

tests/libs/ns_hidden_child_internal.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+extern "C" void internal_function() {}