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
50using android::vold::KeyBuffer;
51
52static const std::string kDmNameUserdata = "userdata";
53
54static 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
75static 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
92static 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
102static 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
120static 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
139static 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
206bool 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