1 /* 2 * Copyright (C) 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 "KeyBuffer.h" 18 #include "MetadataCrypt.h" 19 20 #include <string> 21 #include <thread> 22 #include <vector> 23 #include <algorithm> 24 25 #include <fcntl.h> 26 #include <sys/ioctl.h> 27 #include <sys/param.h> 28 #include <sys/stat.h> 29 #include <sys/types.h> 30 31 #include <linux/dm-ioctl.h> 32 33 #include <android-base/logging.h> 34 #include <android-base/properties.h> 35 #include <android-base/unique_fd.h> 36 #include <cutils/fs.h> 37 #include <fs_mgr.h> 38 39 #include "EncryptInplace.h" 40 #include "KeyStorage.h" 41 #include "KeyUtil.h" 42 #include "secontext.h" 43 #include "Utils.h" 44 #include "VoldUtil.h" 45 46 #define DM_CRYPT_BUF_SIZE 4096 47 #define TABLE_LOAD_RETRIES 10 48 #define DEFAULT_KEY_TARGET_TYPE "default-key" 49 50 using android::vold::KeyBuffer; 51 52 static const std::string kDmNameUserdata = "userdata"; 53 54 static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) { 55 // fs_mgr_do_mount runs fsck. Use setexeccon to run trusted 56 // partitions in the fsck domain. 57 if (setexeccon(secontextFsck())) { 58 PLOG(ERROR) << "Failed to setexeccon"; 59 return false; 60 } 61 auto mount_rc = fs_mgr_do_mount(fstab_default, const_cast<char*>(mount_point), 62 const_cast<char*>(blk_device), nullptr); 63 if (setexeccon(nullptr)) { 64 PLOG(ERROR) << "Failed to clear setexeccon"; 65 return false; 66 } 67 if (mount_rc != 0) { 68 LOG(ERROR) << "fs_mgr_do_mount failed with rc " << mount_rc; 69 return false; 70 } 71 LOG(DEBUG) << "Mounted " << mount_point; 72 return true; 73 } 74 75 static bool read_key(struct fstab_rec const* data_rec, bool create_if_absent, KeyBuffer* key) { 76 if (!data_rec->key_dir) { 77 LOG(ERROR) << "Failed to get key_dir"; 78 return false; 79 } 80 std::string key_dir = data_rec->key_dir; 81 auto dir = key_dir + "/key"; 82 LOG(DEBUG) << "key_dir/key: " << dir; 83 if (fs_mkdirs(dir.c_str(), 0700)) { 84 PLOG(ERROR) << "Creating directories: " << dir; 85 return false; 86 } 87 auto temp = key_dir + "/tmp"; 88 if (!android::vold::retrieveKey(create_if_absent, dir, temp, key)) return false; 89 return true; 90 } 91 92 static KeyBuffer default_key_params(const std::string& real_blkdev, const KeyBuffer& key) { 93 KeyBuffer hex_key; 94 if (android::vold::StrToHex(key, hex_key) != android::OK) { 95 LOG(ERROR) << "Failed to turn key to hex"; 96 return KeyBuffer(); 97 } 98 auto res = KeyBuffer() + "AES-256-XTS " + hex_key + " " + real_blkdev.c_str() + " 0"; 99 return res; 100 } 101 102 static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t *nr_sec) { 103 android::base::unique_fd dev_fd(TEMP_FAILURE_RETRY(open( 104 real_blkdev.c_str(), O_RDONLY | O_CLOEXEC, 0))); 105 if (dev_fd == -1) { 106 PLOG(ERROR) << "Unable to open " << real_blkdev << " to measure size"; 107 return false; 108 } 109 unsigned long res; 110 // TODO: should use BLKGETSIZE64 111 get_blkdev_size(dev_fd.get(), &res); 112 if (res == 0) { 113 PLOG(ERROR) << "Unable to measure size of " << real_blkdev; 114 return false; 115 } 116 *nr_sec = res; 117 return true; 118 } 119 120 static struct dm_ioctl* dm_ioctl_init(char *buffer, size_t buffer_size, 121 const std::string& dm_name) { 122 if (buffer_size < sizeof(dm_ioctl)) { 123 LOG(ERROR) << "dm_ioctl buffer too small"; 124 return nullptr; 125 } 126 127 memset(buffer, 0, buffer_size); 128 struct dm_ioctl* io = (struct dm_ioctl*) buffer; 129 io->data_size = buffer_size; 130 io->data_start = sizeof(struct dm_ioctl); 131 io->version[0] = 4; 132 io->version[1] = 0; 133 io->version[2] = 0; 134 io->flags = 0; 135 dm_name.copy(io->name, sizeof(io->name)); 136 return io; 137 } 138 139 static bool create_crypto_blk_dev(const std::string& dm_name, uint64_t nr_sec, 140 const std::string& target_type, const KeyBuffer& crypt_params, 141 std::string* crypto_blkdev) { 142 android::base::unique_fd dm_fd(TEMP_FAILURE_RETRY(open( 143 "/dev/device-mapper", O_RDWR | O_CLOEXEC, 0))); 144 if (dm_fd == -1) { 145 PLOG(ERROR) << "Cannot open device-mapper"; 146 return false; 147 } 148 alignas(struct dm_ioctl) char buffer[DM_CRYPT_BUF_SIZE]; 149 auto io = dm_ioctl_init(buffer, sizeof(buffer), dm_name); 150 if (!io || ioctl(dm_fd.get(), DM_DEV_CREATE, io) != 0) { 151 PLOG(ERROR) << "Cannot create dm-crypt device " << dm_name; 152 return false; 153 } 154 155 // Get the device status, in particular, the name of its device file 156 io = dm_ioctl_init(buffer, sizeof(buffer), dm_name); 157 if (ioctl(dm_fd.get(), DM_DEV_STATUS, io) != 0) { 158 PLOG(ERROR) << "Cannot retrieve dm-crypt device status " << dm_name; 159 return false; 160 } 161 *crypto_blkdev = std::string() + "/dev/block/dm-" + std::to_string( 162 (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00)); 163 164 io = dm_ioctl_init(buffer, sizeof(buffer), dm_name); 165 size_t paramix = io->data_start + sizeof(struct dm_target_spec); 166 size_t nullix = paramix + crypt_params.size(); 167 size_t endix = (nullix + 1 + 7) & 8; // Add room for \0 and align to 8 byte boundary 168 169 if (endix > sizeof(buffer)) { 170 LOG(ERROR) << "crypt_params too big for DM_CRYPT_BUF_SIZE"; 171 return false; 172 } 173 174 io->target_count = 1; 175 auto tgt = (struct dm_target_spec *) (buffer + io->data_start); 176 tgt->status = 0; 177 tgt->sector_start = 0; 178 tgt->length = nr_sec; 179 target_type.copy(tgt->target_type, sizeof(tgt->target_type)); 180 memcpy(buffer + paramix, crypt_params.data(), 181 std::min(crypt_params.size(), sizeof(buffer) - paramix)); 182 buffer[nullix] = '\0'; 183 tgt->next = endix; 184 185 for (int i = 0; ; i++) { 186 if (ioctl(dm_fd.get(), DM_TABLE_LOAD, io) == 0) { 187 break; 188 } 189 if (i+1 >= TABLE_LOAD_RETRIES) { 190 PLOG(ERROR) << "DM_TABLE_LOAD ioctl failed"; 191 return false; 192 } 193 PLOG(INFO) << "DM_TABLE_LOAD ioctl failed, retrying"; 194 usleep(500000); 195 } 196 197 // Resume this device to activate it 198 io = dm_ioctl_init(buffer, sizeof(buffer), dm_name); 199 if (ioctl(dm_fd.get(), DM_DEV_SUSPEND, io)) { 200 PLOG(ERROR) << "Cannot resume dm-crypt device " << dm_name; 201 return false; 202 } 203 return true; 204 } 205 206 bool e4crypt_mount_metadata_encrypted(const std::string& mount_point, bool needs_encrypt) { 207 LOG(DEBUG) << "e4crypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt; 208 auto encrypted_state = android::base::GetProperty("ro.crypto.state", ""); 209 if (encrypted_state != "") { 210 LOG(DEBUG) << "e4crypt_enable_crypto got unexpected starting state: " << encrypted_state; 211 return false; 212 } 213 auto data_rec = fs_mgr_get_entry_for_mount_point(fstab_default, mount_point); 214 if (!data_rec) { 215 LOG(ERROR) << "Failed to get data_rec"; 216 return false; 217 } 218 KeyBuffer key; 219 if (!read_key(data_rec, needs_encrypt, &key)) return false; 220 uint64_t nr_sec; 221 if (!get_number_of_sectors(data_rec->blk_device, &nr_sec)) return false; 222 std::string crypto_blkdev; 223 if (!create_crypto_blk_dev(kDmNameUserdata, nr_sec, DEFAULT_KEY_TARGET_TYPE, 224 default_key_params(data_rec->blk_device, key), &crypto_blkdev)) 225 return false; 226 // FIXME handle the corrupt case 227 if (needs_encrypt) { 228 LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec; 229 off64_t size_already_done = 0; 230 auto rc = 231 cryptfs_enable_inplace(const_cast<char*>(crypto_blkdev.c_str()), data_rec->blk_device, 232 nr_sec, &size_already_done, nr_sec, 0, false); 233 if (rc != 0) { 234 LOG(ERROR) << "Inplace crypto failed with code: " << rc; 235 return false; 236 } 237 if (static_cast<uint64_t>(size_already_done) != nr_sec) { 238 LOG(ERROR) << "Inplace crypto only got up to sector: " << size_already_done; 239 return false; 240 } 241 LOG(INFO) << "Inplace encryption complete"; 242 } 243 244 LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point; 245 mount_via_fs_mgr(data_rec->mount_point, crypto_blkdev.c_str()); 246 return true; 247 } 248
