1 /*
2 * Copyright (C) 2021 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 #define LOG_TAG "apex_shared_libraries_test"
17
18 #include <android-base/logging.h>
19 #include <android-base/properties.h>
20 #include <android-base/scopeguard.h>
21 #include <android-base/strings.h>
22 #include <dlfcn.h>
23 #include <fstab/fstab.h>
24 #include <gtest/gtest.h>
25 #include <link.h>
26
27 #include <filesystem>
28 #include <fstream>
29 #include <string>
30
31 using android::base::GetBoolProperty;
32 using android::base::Split;
33 using android::base::StartsWith;
34 using android::fs_mgr::Fstab;
35 using android::fs_mgr::ReadFstabFromFile;
36
37 namespace fs = std::filesystem;
38
39 static constexpr const char* kApexRoot = "/apex";
40 static constexpr const char* kApexSharedLibsRoot = "/apex/sharedlibs";
41
TEST(apex_shared_libraries,symlink_libraries_loadable)42 TEST(apex_shared_libraries, symlink_libraries_loadable) {
43 if (!GetBoolProperty("ro.apex.updatable", false)) {
44 GTEST_SKIP() << "Skipping test because device doesn't support APEX";
45 }
46
47 Fstab fstab;
48 ASSERT_TRUE(ReadFstabFromFile("/proc/mounts", &fstab));
49
50 // Traverse mount points to identify apexs.
51 for (auto& entry : fstab) {
52 if (fs::path(entry.mount_point).parent_path() != kApexRoot) {
53 continue;
54 }
55
56 // Focus on "active" apexs.
57 if (entry.mount_point.find('@') != std::string::npos) {
58 continue;
59 }
60 std::string dev_file = fs::path(entry.blk_device).filename();
61
62 // Filter out any mount irrelevant (e.g. tmpfs)
63 if (!StartsWith(dev_file, "loop") && !StartsWith(dev_file, "dm-")) {
64 continue;
65 }
66
67 #if !defined(__LP64__)
68 auto lib = fs::path(entry.mount_point) / "lib";
69 #else // !__LP64__
70 auto lib = fs::path(entry.mount_point) / "lib64";
71 #endif // !__LP64__
72 if (!fs::is_directory(lib)) {
73 continue;
74 }
75 for (auto& p : fs::directory_iterator(lib)) {
76 std::error_code ec;
77 if (!fs::is_symlink(p, ec)) {
78 continue;
79 }
80
81 // We are only checking libraries pointing at a location inside
82 // /apex/sharedlibs.
83 auto target = fs::read_symlink(p.path(), ec);
84 if (ec || !StartsWith(target.string(), kApexSharedLibsRoot)) {
85 continue;
86 }
87
88 // Symlink validity check.
89 auto dest = fs::canonical(p.path(), ec);
90 EXPECT_FALSE(ec) << "Failed to resolve " << p.path() << " (symlink to "
91 << target << "): " << ec;
92 if (ec) {
93 continue;
94 }
95
96 // Library loading validity check.
97 dlerror(); // Clear any pending errors.
98 void* handle = dlopen(p.path().c_str(), RTLD_NOW);
99 EXPECT_TRUE(handle != nullptr) << dlerror();
100 if (handle == nullptr) {
101 continue;
102 }
103 auto guard = android::base::make_scope_guard([&]() { dlclose(handle); });
104
105 // Check that library is loaded and pointing to the realpath of the
106 // library.
107 auto dl_callback = [](dl_phdr_info* info, size_t /* size */, void* data) {
108 auto dest = *static_cast<fs::path*>(data);
109 if (info->dlpi_name == nullptr) {
110 // This is linker imposing as libdl.so - skip it
111 return 0;
112 }
113 int j;
114 for (j = 0; j < info->dlpi_phnum; j++) {
115 void* addr = (void*)(info->dlpi_addr + info->dlpi_phdr[j].p_vaddr);
116 Dl_info dl_info;
117 int rc = dladdr(addr, &dl_info);
118 if (rc == 0) {
119 continue;
120 }
121 if (dl_info.dli_fname) {
122 auto libpath = fs::path(dl_info.dli_fname);
123 if (libpath == dest) {
124 // Library found!
125 return 1;
126 }
127 }
128 }
129
130 return 0;
131 };
132 bool found = (dl_iterate_phdr(dl_callback, &dest) == 1);
133 EXPECT_TRUE(found) << "Error verifying library symlink " << p.path()
134 << " which points to " << target
135 << " which resolves to file " << dest;
136 if (found) {
137 LOG(INFO) << "Verified that " << p.path()
138 << " correctly loads as library " << dest;
139 }
140 }
141 }
142 }
143