1 /*
2  * Copyright (C) 2020 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 
17 #include <dirent.h>
18 #include <sys/mount.h>
19 #include <sys/stat.h>
20 #include <sys/types.h>
21 #include <sys/utsname.h>
22 #include <sys/wait.h>
23 #include <unistd.h>
24 
25 #include <cstdlib>
26 #include <filesystem>
27 #include <fstream>
28 #include <iostream>
29 #include <memory>
30 #include <string>
31 #include <vector>
32 
33 #include <modprobe/modprobe.h>
34 
35 #include "android-base/logging.h"
36 #include "android-base/strings.h"
37 
38 using namespace android::base;
39 
40 static constexpr const char MODULE_BASE_DIR[] = "/lib/modules";
41 
42 bool LoadKernelModules() {
43     struct utsname uts;
44     if (uname(&uts)) {
45         LOG(ERROR) << "Failed to get kernel version.";
46         return false;
47     }
48     int major, minor;
49     if (sscanf(uts.release, "%d.%d", &major, &minor) != 2) {
50         LOG(ERROR) << "Failed to parse kernel version " << uts.release;
51         return false;
52     }
53 
54     std::unique_ptr<DIR, decltype(&closedir)> base_dir(opendir(MODULE_BASE_DIR), closedir);
55     if (!base_dir) {
56         LOG(ERROR) << "Unable to open /lib/modules, skipping module loading.";
57         return false;
58     }
59     dirent* entry;
60     std::vector<std::string> module_dirs;
61     while ((entry = readdir(base_dir.get()))) {
62         if (entry->d_type != DT_DIR) {
63             continue;
64         }
65         int dir_major, dir_minor;
66         if (sscanf(entry->d_name, "%d.%d", &dir_major, &dir_minor) != 2 || dir_major != major ||
67             dir_minor != minor) {
68             continue;
69         }
70         module_dirs.emplace_back(entry->d_name);
71     }
72 
73     // Sort the directories so they are iterated over during module loading
74     // in a consistent order. Alphabetical sorting is fine here because the
75     // kernel version at the beginning of the directory name must match the
76     // current kernel version, so the sort only applies to a label that
77     // follows the kernel version, for example /lib/modules/5.4 vs.
78     // /lib/modules/5.4-gki.
79     std::sort(module_dirs.begin(), module_dirs.end());
80 
81     for (const auto& module_dir : module_dirs) {
82         std::string dir_path(MODULE_BASE_DIR);
83         dir_path.append("/");
84         dir_path.append(module_dir);
85         Modprobe m({dir_path});
86         bool retval = m.LoadListedModules();
87         int modules_loaded = m.GetModuleCount();
88         if (modules_loaded > 0) {
89             return retval;
90         }
91     }
92 
93     Modprobe m({MODULE_BASE_DIR});
94     bool retval = m.LoadListedModules();
95     int modules_loaded = m.GetModuleCount();
96     if (modules_loaded > 0) {
97         return retval;
98     }
99 
100     return true;
101 }
102 
103 int main(int argc, const char* argv[]) {
104     SetLogger(StderrLogger);
105 
106     LOG(INFO) << "Guest VM init process";
107     LOG(INFO) << "Command line: " << Join(std::vector(argv, argv + argc), " ");
108 
109     if (clearenv() != EXIT_SUCCESS) {
110         PLOG(ERROR) << "clearenv";
111         return EXIT_FAILURE;
112     }
113 
114     LOG(INFO) << "Loading kernel modules...";
115     if (!LoadKernelModules()) {
116         LOG(ERROR) << "LoadKernelModules failed";
117         return EXIT_FAILURE;
118     }
119 
120     LOG(INFO) << "Executing test binary " << argv[1] << "...";
121     execv(argv[1], (char**)(argv + 1));
122 
123     PLOG(ERROR) << "execv";
124     return EXIT_FAILURE;
125 }
126