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 "installd_constants.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 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 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. 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 + cmd... + null | Incoming | = argc + 1 140 // Outgoing: cmd + target-slot + cmd... + null | Outgoing | = argc 141 const char** argv = new const char*[argc]; 142 143 argv[0] = "/system/bin/otapreopt"; 144 145 // The first parameter is the status file descriptor, skip. 146 for (size_t i = 2; i <= static_cast<size_t>(argc); ++i) { 147 argv[i - 1] = arg[i]; 148 } 149 150 execv(argv[0], static_cast<char * const *>(const_cast<char**>(argv))); 151 PLOG(ERROR) << "execv(OTAPREOPT) failed."; 152 exit(99); 153 } 154 155 } // namespace installd 156 } // namespace android 157 158 int main(const int argc, char *argv[]) { 159 return android::installd::otapreopt_chroot(argc, argv); 160 } 161
