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
mount_via_fs_mgr(const char * mount_point,const char * blk_device)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
read_key(struct fstab_rec const * data_rec,bool create_if_absent,KeyBuffer * key)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
default_key_params(const std::string & real_blkdev,const KeyBuffer & key)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
get_number_of_sectors(const std::string & real_blkdev,uint64_t * nr_sec)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
dm_ioctl_init(char * buffer,size_t buffer_size,const std::string & dm_name)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
create_crypto_blk_dev(const std::string & dm_name,uint64_t nr_sec,const std::string & target_type,const KeyBuffer & crypt_params,std::string * crypto_blkdev)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
e4crypt_mount_metadata_encrypted(const std::string & mount_point,bool needs_encrypt)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