1 /*
2 ** Copyright 2016, 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 <linux/unistd.h>
18 #include <sys/mount.h>
19 #include <sys/wait.h>
20
21 #include <android-base/logging.h>
22 #include <android-base/macros.h>
23 #include <android-base/stringprintf.h>
24
25 #ifndef LOG_TAG
26 #define LOG_TAG "otapreopt"
27 #endif
28
29 using android::base::StringPrintf;
30
31 namespace android {
32 namespace installd {
33
otapreopt_chroot(const int argc,char ** arg)34 static int otapreopt_chroot(const int argc, char **arg) {
35 // We need to run the otapreopt tool from the postinstall partition. As such, set up a
36 // mount namespace and change root.
37
38 // Create our own mount namespace.
39 if (unshare(CLONE_NEWNS) != 0) {
40 PLOG(ERROR) << "Failed to unshare() for otapreopt.";
41 exit(200);
42 }
43
44 // Make postinstall private, so that our changes don't propagate.
45 if (mount("", "/postinstall", nullptr, MS_PRIVATE, nullptr) != 0) {
46 PLOG(ERROR) << "Failed to mount private.";
47 exit(201);
48 }
49
50 // Bind mount necessary directories.
51 constexpr const char* kBindMounts[] = {
52 "/data", "/dev", "/proc", "/sys"
53 };
54 for (size_t i = 0; i < arraysize(kBindMounts); ++i) {
55 std::string trg = StringPrintf("/postinstall%s", kBindMounts[i]);
56 if (mount(kBindMounts[i], trg.c_str(), nullptr, MS_BIND, nullptr) != 0) {
57 PLOG(ERROR) << "Failed to bind-mount " << kBindMounts[i];
58 exit(202);
59 }
60 }
61
62 // Chdir into /postinstall.
63 if (chdir("/postinstall") != 0) {
64 PLOG(ERROR) << "Unable to chdir into /postinstall.";
65 exit(203);
66 }
67
68 // Make /postinstall the root in our mount namespace.
69 if (chroot(".") != 0) {
70 PLOG(ERROR) << "Failed to chroot";
71 exit(204);
72 }
73
74 if (chdir("/") != 0) {
75 PLOG(ERROR) << "Unable to chdir into /.";
76 exit(205);
77 }
78
79 // Now go on and run otapreopt.
80
81 const char* argv[1 + 9 + 1];
82 CHECK_EQ(argc, 10);
83 argv[0] = "/system/bin/otapreopt";
84 for (size_t i = 1; i <= 9; ++i) {
85 argv[i] = arg[i];
86 }
87 argv[10] = nullptr;
88
89 execv(argv[0], (char * const *)argv);
90 PLOG(ERROR) << "execv(OTAPREOPT) failed.";
91 exit(99);
92 }
93
94 } // namespace installd
95 } // namespace android
96
main(const int argc,char * argv[])97 int main(const int argc, char *argv[]) {
98 return android::installd::otapreopt_chroot(argc, argv);
99 }
100