Devmapper.cpp revision fcf24fe62f98c5d44431aa575555569c2c7a29b0 
1/*
2 * Copyright (C) 2008 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 <stdio.h>
18#include <fcntl.h>
19#include <unistd.h>
20#include <errno.h>
21#include <string.h>
22
23#include <sys/types.h>
24#include <sys/ioctl.h>
25#include <sys/stat.h>
26
27#define LOG_TAG "Vold"
28
29#include <cutils/log.h>
30
31#include "Devmapper.h"
32
33void Devmapper::ioctlInit(struct dm_ioctl *io, size_t dataSize,
34                          const char *name, unsigned flags) {
35    memset(io, 0, dataSize);
36    io->data_size = dataSize;
37    io->data_start = sizeof(struct dm_ioctl);
38    io->version[0] = 4;
39    io->version[1] = 0;
40    io->version[2] = 0;
41    io->flags = flags;
42    strncpy(io->name, name, sizeof(io->name));
43}
44
45int Devmapper::lookupActive(const char *name, char *ubuffer, size_t len) {
46    char *buffer = (char *) malloc(4096);
47    if (!buffer) {
48        LOGE("Error allocating memory (%s)", strerror(errno));
49        return -1;
50    }
51
52    int fd;
53    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
54        LOGE("Error opening devmapper (%s)", strerror(errno));
55        free(buffer);
56        return -1;
57    }
58
59    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
60
61    ioctlInit(io, 4096, name, 0);
62    if (ioctl(fd, DM_DEV_STATUS, io)) {
63        if (errno != ENXIO) {
64            LOGE("DM_DEV_STATUS ioctl failed for lookup (%s)", strerror(errno));
65        }
66        free(buffer);
67        close(fd);
68        return -1;
69    }
70    close(fd);
71
72    unsigned minor = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00);
73    free(buffer);
74    snprintf(ubuffer, len, "/dev/block/dm-%u", minor);
75    return 0;
76}
77
78int Devmapper::create(const char *name, const char *loopFile, const char *key,
79                      unsigned int numSectors, char *ubuffer, size_t len) {
80    char *buffer = (char *) malloc(4096);
81    if (!buffer) {
82        LOGE("Error allocating memory (%s)", strerror(errno));
83        return -1;
84    }
85
86    int fd;
87    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
88        LOGE("Error opening devmapper (%s)", strerror(errno));
89        free(buffer);
90        return -1;
91    }
92
93    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
94
95    // Create the DM device
96    ioctlInit(io, 4096, name, 0);
97
98    if (ioctl(fd, DM_DEV_CREATE, io)) {
99        LOGE("Error creating device mapping (%s)", strerror(errno));
100        free(buffer);
101        close(fd);
102        return -1;
103    }
104
105    // Set the legacy geometry
106    ioctlInit(io, 4096, name, 0);
107
108    char *geoParams = buffer + sizeof(struct dm_ioctl);
109    // bps=512 spc=8 res=32 nft=2 sec=8190 mid=0xf0 spt=63 hds=64 hid=0 bspf=8 rdcl=2 infs=1 bkbs=2
110    strcpy(geoParams, "0 64 63 0");
111    geoParams += strlen(geoParams) + 1;
112    geoParams = (char *) _align(geoParams, 8);
113    if (ioctl(fd, DM_DEV_SET_GEOMETRY, io)) {
114        LOGE("Error setting device geometry (%s)", strerror(errno));
115        free(buffer);
116        close(fd);
117        return -1;
118    }
119
120    // Retrieve the device number we were allocated
121    ioctlInit(io, 4096, name, 0);
122    if (ioctl(fd, DM_DEV_STATUS, io)) {
123        LOGE("Error retrieving devmapper status (%s)", strerror(errno));
124        free(buffer);
125        close(fd);
126        return -1;
127    }
128
129    unsigned minor = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00);
130    snprintf(ubuffer, len, "/dev/block/dm-%u", minor);
131
132    // Load the table
133    struct dm_target_spec *tgt;
134    tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)];
135
136    ioctlInit(io, 4096, name, DM_STATUS_TABLE_FLAG);
137    io->target_count = 1;
138    tgt->status = 0;
139
140    tgt->sector_start = 0;
141    tgt->length = numSectors;
142
143    strcpy(tgt->target_type, "crypt");
144
145    char *cryptParams = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec);
146    sprintf(cryptParams, "twofish %s 0 %s 0", key, loopFile);
147    cryptParams += strlen(cryptParams) + 1;
148    cryptParams = (char *) _align(cryptParams, 8);
149    tgt->next = cryptParams - buffer;
150
151    if (ioctl(fd, DM_TABLE_LOAD, io)) {
152        LOGE("Error loading mapping table (%s)", strerror(errno));
153        free(buffer);
154        close(fd);
155        return -1;
156    }
157
158    // Resume the new table
159    ioctlInit(io, 4096, name, 0);
160
161    if (ioctl(fd, DM_DEV_SUSPEND, io)) {
162        LOGE("Error Resuming (%s)", strerror(errno));
163        free(buffer);
164        close(fd);
165        return -1;
166    }
167
168    free(buffer);
169
170    close(fd);
171    return 0;
172}
173
174int Devmapper::destroy(const char *name) {
175    char *buffer = (char *) malloc(4096);
176    if (!buffer) {
177        LOGE("Error allocating memory (%s)", strerror(errno));
178        return -1;
179    }
180
181    int fd;
182    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
183        LOGE("Error opening devmapper (%s)", strerror(errno));
184        free(buffer);
185        return -1;
186    }
187
188    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
189
190    // Create the DM device
191    ioctlInit(io, 4096, name, 0);
192
193    if (ioctl(fd, DM_DEV_REMOVE, io)) {
194        if (errno != ENXIO) {
195            LOGE("Error destroying device mapping (%s)", strerror(errno));
196        }
197        free(buffer);
198        close(fd);
199        return -1;
200    }
201
202    free(buffer);
203    close(fd);
204    return 0;
205}
206
207void *Devmapper::_align(void *ptr, unsigned int a)
208{
209        register unsigned long agn = --a;
210
211        return (void *) (((unsigned long) ptr + agn) & ~agn);
212}
213
214