summaryrefslogtreecommitdiffstats
blob: 5a2dfc67aeb9010021f79bbad714fbb1e0d27416 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "libdm/dm.h"

#include <sys/ioctl.h>
#include <sys/types.h>

#include <android-base/macros.h>

namespace android {
namespace dm {

DeviceMapper& DeviceMapper::Instance() {
    static DeviceMapper instance;
    return instance;
}
// Creates a new device mapper device
bool DeviceMapper::CreateDevice(const std::string& name) {
    if (name.empty()) {
        LOG(ERROR) << "Unnamed device mapper device creation is not supported";
        return false;
    }

    if (name.size() >= DM_NAME_LEN) {
        LOG(ERROR) << "[" << name << "] is too long to be device mapper name";
        return false;
    }

    struct dm_ioctl io;
    InitIo(&io, name);

    if (ioctl(fd_, DM_DEV_CREATE, &io)) {
        PLOG(ERROR) << "DM_DEV_CREATE failed for [" << name << "]";
        return false;
    }

    // Check to make sure the newly created device doesn't already have targets
    // added or opened by someone
    CHECK(io.target_count == 0) << "Unexpected targets for newly created [" << name << "] device";
    CHECK(io.open_count == 0) << "Unexpected opens for newly created [" << name << "] device";

    // Creates a new device mapper device with the name passed in
    return true;
}

bool DeviceMapper::DeleteDevice(const std::string& name) {
    if (name.empty()) {
        LOG(ERROR) << "Unnamed device mapper device creation is not supported";
        return false;
    }

    if (name.size() >= DM_NAME_LEN) {
        LOG(ERROR) << "[" << name << "] is too long to be device mapper name";
        return false;
    }

    struct dm_ioctl io;
    InitIo(&io, name);

    if (ioctl(fd_, DM_DEV_REMOVE, &io)) {
        PLOG(ERROR) << "DM_DEV_REMOVE failed for [" << name << "]";
        return false;
    }

    // Check to make sure appropriate uevent is generated so ueventd will
    // do the right thing and remove the corresponding device node and symlinks.
    CHECK(io.flags & DM_UEVENT_GENERATED_FLAG)
            << "Didn't generate uevent for [" << name << "] removal";

    return true;
}

const std::unique_ptr<DmTable> DeviceMapper::table(const std::string& /* name */) const {
    // TODO(b/110035986): Return the table, as read from the kernel instead
    return nullptr;
}

DmDeviceState DeviceMapper::state(const std::string& /* name */) const {
    // TODO(b/110035986): Return the state, as read from the kernel instead
    return DmDeviceState::INVALID;
}

bool DeviceMapper::CreateDevice(const std::string& name, const DmTable& table) {
    if (!CreateDevice(name)) {
        return false;
    }
    if (!LoadTableAndActivate(name, table)) {
        DeleteDevice(name);
        return false;
    }
    return true;
}

bool DeviceMapper::LoadTableAndActivate(const std::string& name, const DmTable& table) {
    std::string ioctl_buffer(sizeof(struct dm_ioctl), 0);
    ioctl_buffer += table.Serialize();

    struct dm_ioctl* io = reinterpret_cast<struct dm_ioctl*>(&ioctl_buffer[0]);
    InitIo(io, name);
    io->data_size = ioctl_buffer.size();
    io->data_start = sizeof(struct dm_ioctl);
    io->target_count = static_cast<uint32_t>(table.num_targets());
    if (ioctl(fd_, DM_TABLE_LOAD, io)) {
        PLOG(ERROR) << "DM_TABLE_LOAD failed";
        return false;
    }

    InitIo(io, name);
    if (ioctl(fd_, DM_DEV_SUSPEND, io)) {
        PLOG(ERROR) << "DM_TABLE_SUSPEND resume failed";
        return false;
    }
    return true;
}

// Reads all the available device mapper targets and their corresponding
// versions from the kernel and returns in a vector
bool DeviceMapper::GetAvailableTargets(std::vector<DmTarget>* targets) {
    targets->clear();

    // calculate the space needed to read a maximum of kMaxPossibleDmTargets
    uint32_t payload_size = sizeof(struct dm_target_versions);
    payload_size += DM_MAX_TYPE_NAME;
    // device mapper wants every target spec to be aligned at 8-byte boundary
    payload_size = DM_ALIGN(payload_size);
    payload_size *= kMaxPossibleDmTargets;

    uint32_t data_size = sizeof(struct dm_ioctl) + payload_size;
    auto buffer = std::unique_ptr<void, void (*)(void*)>(calloc(1, data_size), free);
    if (buffer == nullptr) {
        LOG(ERROR) << "failed to allocate memory";
        return false;
    }

    // Sets appropriate data size and data_start to make sure we tell kernel
    // about the total size of the buffer we are passing and where to start
    // writing the list of targets.
    struct dm_ioctl* io = reinterpret_cast<struct dm_ioctl*>(buffer.get());
    InitIo(io);
    io->data_size = data_size;
    io->data_start = sizeof(*io);

    if (ioctl(fd_, DM_LIST_VERSIONS, io)) {
        PLOG(ERROR) << "DM_LIST_VERSIONS failed";
        return false;
    }

    // If the provided buffer wasn't enough to list all targets, note that
    // any data beyond sizeof(*io) must not be read in this case
    if (io->flags & DM_BUFFER_FULL_FLAG) {
        LOG(INFO) << data_size << " is not enough memory to list all dm targets";
        return false;
    }

    // if there are no targets registered, return success with empty vector
    if (io->data_size == sizeof(*io)) {
        return true;
    }

    // Parse each target and list the name and version
    // TODO(b/110035986): Templatize this
    uint32_t next = sizeof(*io);
    data_size = io->data_size - next;
    struct dm_target_versions* vers =
            reinterpret_cast<struct dm_target_versions*>(static_cast<char*>(buffer.get()) + next);
    while (next && data_size) {
        targets->emplace_back((vers));
        if (vers->next == 0) {
            break;
        }
        next += vers->next;
        data_size -= vers->next;
        vers = reinterpret_cast<struct dm_target_versions*>(static_cast<char*>(buffer.get()) + next);
    }

    return true;
}

bool DeviceMapper::GetAvailableDevices(std::vector<DmBlockDevice>* devices) {
    devices->clear();

    // calculate the space needed to read a maximum of 256 targets, each with
    // name with maximum length of 16 bytes
    uint32_t payload_size = sizeof(struct dm_name_list);
    // 128-bytes for the name
    payload_size += DM_NAME_LEN;
    // dm wants every device spec to be aligned at 8-byte boundary
    payload_size = DM_ALIGN(payload_size);
    payload_size *= kMaxPossibleDmDevices;
    uint32_t data_size = sizeof(struct dm_ioctl) + payload_size;
    auto buffer = std::unique_ptr<void, void (*)(void*)>(calloc(1, data_size), free);
    if (buffer == nullptr) {
        LOG(ERROR) << "failed to allocate memory";
        return false;
    }

    // Sets appropriate data size and data_start to make sure we tell kernel
    // about the total size of the buffer we are passing and where to start
    // writing the list of targets.
    struct dm_ioctl* io = reinterpret_cast<struct dm_ioctl*>(buffer.get());
    InitIo(io);
    io->data_size = data_size;
    io->data_start = sizeof(*io);

    if (ioctl(fd_, DM_LIST_DEVICES, io)) {
        PLOG(ERROR) << "DM_LIST_DEVICES failed";
        return false;
    }

    // If the provided buffer wasn't enough to list all devices any data
    // beyond sizeof(*io) must not be read.
    if (io->flags & DM_BUFFER_FULL_FLAG) {
        LOG(INFO) << data_size << " is not enough memory to list all dm devices";
        return false;
    }

    // if there are no devices created yet, return success with empty vector
    if (io->data_size == sizeof(*io)) {
        return true;
    }

    // Parse each device and add a new DmBlockDevice to the vector
    // created from the kernel data.
    uint32_t next = sizeof(*io);
    data_size = io->data_size - next;
    struct dm_name_list* dm_dev =
            reinterpret_cast<struct dm_name_list*>(static_cast<char*>(buffer.get()) + next);

    while (next && data_size) {
        devices->emplace_back((dm_dev));
        if (dm_dev->next == 0) {
            break;
        }
        next += dm_dev->next;
        data_size -= dm_dev->next;
        dm_dev = reinterpret_cast<struct dm_name_list*>(static_cast<char*>(buffer.get()) + next);
    }

    return true;
}

// Accepts a device mapper device name (like system_a, vendor_b etc) and
// returns the path to it's device node (or symlink to the device node)
std::string DeviceMapper::GetDmDevicePathByName(const std::string& /* name */) {
    return "";
}

// private methods of DeviceMapper
void DeviceMapper::InitIo(struct dm_ioctl* io, const std::string& name) const {
    CHECK(io != nullptr) << "nullptr passed to dm_ioctl initialization";
    memset(io, 0, sizeof(*io));

    io->version[0] = DM_VERSION0;
    io->version[1] = DM_VERSION1;
    io->version[2] = DM_VERSION2;
    io->data_size = sizeof(*io);
    io->data_start = 0;
    if (!name.empty()) {
        strlcpy(io->name, name.c_str(), sizeof(io->name));
    }
}

}  // namespace dm
}  // namespace android