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
29using android::base::StringPrintf;
30
31namespace android {
32namespace installd {
33
34static 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
97int main(const int argc, char *argv[]) {
98    return android::installd::otapreopt_chroot(argc, argv);
99}
100