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 <fcntl.h>
18 #include <linux/unistd.h>
19 #include <sys/mount.h>
20 #include <sys/wait.h>
21
22 #include <sstream>
23
24 #include <android-base/logging.h>
25 #include <android-base/macros.h>
26 #include <android-base/stringprintf.h>
27
28 #include <commands.h>
29 #include <otapreopt_utils.h>
30
31 #ifndef LOG_TAG
32 #define LOG_TAG "otapreopt"
33 #endif
34
35 using android::base::StringPrintf;
36
37 namespace android {
38 namespace installd {
39
CloseDescriptor(int fd)40 static void CloseDescriptor(int fd) {
41 if (fd >= 0) {
42 int result = close(fd);
43 UNUSED(result); // Ignore result. Printing to logcat will open a new descriptor
44 // that we do *not* want.
45 }
46 }
47
CloseDescriptor(const char * descriptor_string)48 static void CloseDescriptor(const char* descriptor_string) {
49 int fd = -1;
50 std::istringstream stream(descriptor_string);
51 stream >> fd;
52 if (!stream.fail()) {
53 CloseDescriptor(fd);
54 }
55 }
56
57 // Entry for otapreopt_chroot. Expected parameters are:
58 // [cmd] [status-fd] [target-slot] "dexopt" [dexopt-params]
59 // The file descriptor denoted by status-fd will be closed. The rest of the parameters will
60 // be passed on to otapreopt in the chroot.
otapreopt_chroot(const int argc,char ** arg)61 static int otapreopt_chroot(const int argc, char **arg) {
62 // Close all file descriptors. They are coming from the caller, we do not want to pass them
63 // on across our fork/exec into a different domain.
64 // 1) Default descriptors.
65 CloseDescriptor(STDIN_FILENO);
66 CloseDescriptor(STDOUT_FILENO);
67 CloseDescriptor(STDERR_FILENO);
68 // 2) The status channel.
69 CloseDescriptor(arg[1]);
70
71 // We need to run the otapreopt tool from the postinstall partition. As such, set up a
72 // mount namespace and change root.
73
74 // Create our own mount namespace.
75 if (unshare(CLONE_NEWNS) != 0) {
76 PLOG(ERROR) << "Failed to unshare() for otapreopt.";
77 exit(200);
78 }
79
80 // Make postinstall private, so that our changes don't propagate.
81 if (mount("", "/postinstall", nullptr, MS_PRIVATE, nullptr) != 0) {
82 PLOG(ERROR) << "Failed to mount private.";
83 exit(201);
84 }
85
86 // Bind mount necessary directories.
87 constexpr const char* kBindMounts[] = {
88 "/data", "/dev", "/proc", "/sys"
89 };
90 for (size_t i = 0; i < arraysize(kBindMounts); ++i) {
91 std::string trg = StringPrintf("/postinstall%s", kBindMounts[i]);
92 if (mount(kBindMounts[i], trg.c_str(), nullptr, MS_BIND, nullptr) != 0) {
93 PLOG(ERROR) << "Failed to bind-mount " << kBindMounts[i];
94 exit(202);
95 }
96 }
97
98 // Try to mount the vendor partition. update_engine doesn't do this for us, but we
99 // want it for vendor APKs.
100 // Notes:
101 // 1) We pretty much guess a name here and hope to find the partition by name.
102 // It is just as complicated and brittle to scan /proc/mounts. But this requires
103 // validating the target-slot so as not to try to mount some totally random path.
104 // 2) We're in a mount namespace here, so when we die, this will be cleaned up.
105 // 3) Ignore errors. Printing anything at this stage will open a file descriptor
106 // for logging.
107 if (!ValidateTargetSlotSuffix(arg[2])) {
108 LOG(ERROR) << "Target slot suffix not legal: " << arg[2];
109 exit(207);
110 }
111 std::string vendor_partition = StringPrintf("/dev/block/bootdevice/by-name/vendor%s",
112 arg[2]);
113 int vendor_result = mount(vendor_partition.c_str(),
114 "/postinstall/vendor",
115 "ext4",
116 MS_RDONLY,
117 /* data */ nullptr);
118 UNUSED(vendor_result);
119
120 // Chdir into /postinstall.
121 if (chdir("/postinstall") != 0) {
122 PLOG(ERROR) << "Unable to chdir into /postinstall.";
123 exit(203);
124 }
125
126 // Make /postinstall the root in our mount namespace.
127 if (chroot(".") != 0) {
128 PLOG(ERROR) << "Failed to chroot";
129 exit(204);
130 }
131
132 if (chdir("/") != 0) {
133 PLOG(ERROR) << "Unable to chdir into /.";
134 exit(205);
135 }
136
137 // Now go on and run otapreopt.
138
139 // Incoming: cmd + status-fd + target-slot + "dexopt" + dexopt-params + null
140 // Outgoing: cmd + target-slot + "dexopt" + dexopt-params + null
141 constexpr size_t kInArguments = 1 // Binary name.
142 + 1 // status file descriptor.
143 + 1 // target-slot.
144 + 1 // "dexopt."
145 + DEXOPT_PARAM_COUNT // dexopt parameters.
146 + 1; // null termination.
147 constexpr size_t kOutArguments = 1 // Binary name.
148 + 1 // target-slot.
149 + 1 // "dexopt."
150 + DEXOPT_PARAM_COUNT // dexopt parameters.
151 + 1; // null termination.
152 const char* argv[kOutArguments];
153 if (static_cast<size_t>(argc) != kInArguments - 1 /* null termination */) {
154 LOG(ERROR) << "Unexpected argument size "
155 << argc
156 << " vs "
157 << (kInArguments - 1);
158 for (size_t i = 0; i < static_cast<size_t>(argc); ++i) {
159 if (arg[i] == nullptr) {
160 LOG(ERROR) << "(null)";
161 } else {
162 LOG(ERROR) << "\"" << arg[i] << "\"";
163 }
164 }
165 exit(206);
166 }
167 argv[0] = "/system/bin/otapreopt";
168
169 // The first parameter is the status file descriptor, skip.
170
171 for (size_t i = 1; i <= kOutArguments - 2 /* cmd + null */; ++i) {
172 argv[i] = arg[i + 1];
173 }
174 argv[kOutArguments - 1] = nullptr;
175
176 execv(argv[0], (char * const *)argv);
177 PLOG(ERROR) << "execv(OTAPREOPT) failed.";
178 exit(99);
179 }
180
181 } // namespace installd
182 } // namespace android
183
main(const int argc,char * argv[])184 int main(const int argc, char *argv[]) {
185 return android::installd::otapreopt_chroot(argc, argv);
186 }
187