vold: Add encrypted ASEC support via devmapper

- Supports up to 4096 containers
- Keys are now implemented - specifying a key of 'none' means no encryption.
  Otherwise, the key must be a string of 32 characters

Signed-off-by: San Mehat <san@google.com>

1 files changed, 210 insertions, 0 deletions

diff --git a/Devmapper.cpp b/Devmapper.cpp
new file mode 100644
index 0000000..2b7d9a0
--- /dev/null
+++ b/Devmapper.cpp
@@ -0,0 +1,210 @@
+/*
+ * Copyright (C) 2008 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 <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+
+#define LOG_TAG "Vold"
+
+#include <cutils/log.h>
+
+#include "Devmapper.h"
+
+void Devmapper::ioctlInit(struct dm_ioctl *io, size_t dataSize,
+                          const char *name, unsigned flags) {
+    memset(io, 0, dataSize);
+    io->data_size = dataSize;
+    io->data_start = sizeof(struct dm_ioctl);
+    io->version[0] = 4;
+    io->version[1] = 0;
+    io->version[2] = 0;
+    io->flags = flags;
+    strncpy(io->name, name, sizeof(io->name));
+}
+
+int Devmapper::lookupActive(const char *name, char *ubuffer, size_t len) {
+    char *buffer = (char *) malloc(4096);
+    if (!buffer) {
+        LOGE("Error allocating memory (%s)", strerror(errno));
+        return -1;
+    }
+
+    int fd;
+    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
+        LOGE("Error opening devmapper (%s)", strerror(errno));
+        free(buffer);
+        return -1;
+    }
+
+    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
+ 
+    ioctlInit(io, 4096, name, 0);
+    if (ioctl(fd, DM_DEV_STATUS, io)) {
+        if (errno != ENODEV) {
+            LOGE("Error retrieving device status (%s)", strerror(errno));
+        }
+        free(buffer);
+        close(fd);
+        return -1;
+    }
+    close(fd);
+
+    unsigned minor = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00);
+    free(buffer);
+    LOGD("Newly created devmapper instance minor = %d\n", minor);
+    snprintf(ubuffer, len, "/dev/block/dm-%u", minor);
+    return 0;
+}
+
+int Devmapper::create(const char *name, const char *loopFile, const char *key, int sizeMb,
+                      char *ubuffer, size_t len) {
+    char *buffer = (char *) malloc(4096);
+    if (!buffer) {
+        LOGE("Error allocating memory (%s)", strerror(errno));
+        return -1;
+    }
+
+    int fd;
+    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
+        LOGE("Error opening devmapper (%s)", strerror(errno));
+        free(buffer);
+        return -1;
+    }
+
+    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
+ 
+    // Create the DM device
+    ioctlInit(io, 4096, name, 0);
+
+    if (ioctl(fd, DM_DEV_CREATE, io)) {
+        LOGE("Error creating device mapping (%s)", strerror(errno));
+        free(buffer);
+        close(fd);
+        return -1;
+    }
+
+    // Set the legacy geometry
+    ioctlInit(io, 4096, name, 0);
+
+    char *geoParams = buffer + sizeof(struct dm_ioctl);
+    // 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
+    strcpy(geoParams, "0 64 63 0");
+    geoParams += strlen(geoParams) + 1;
+    geoParams = (char *) _align(geoParams, 8);
+    if (ioctl(fd, DM_DEV_SET_GEOMETRY, io)) {
+        LOGE("Error setting device geometry (%s)", strerror(errno));
+        free(buffer);
+        close(fd);
+        return -1;
+    }
+
+    // Retrieve the device number we were allocated
+    ioctlInit(io, 4096, name, 0);
+    if (ioctl(fd, DM_DEV_STATUS, io)) {
+        LOGE("Error retrieving device status (%s)", strerror(errno));
+        free(buffer);
+        close(fd);
+        return -1;
+    }
+
+    unsigned minor = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00);
+    LOGD("Newly created devmapper instance minor = %d\n", minor);
+    snprintf(ubuffer, len, "/dev/block/dm-%u", minor);
+
+    // Load the table
+    struct dm_target_spec *tgt;
+    tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)];
+
+    ioctlInit(io, 4096, name, DM_STATUS_TABLE_FLAG);
+    io->target_count = 1;
+    tgt->status = 0;
+    tgt->sector_start = 0;
+    tgt->length = (sizeMb * (1024 * 1024)) / 512;
+    strcpy(tgt->target_type, "crypt");
+
+    char *cryptParams = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec);
+    sprintf(cryptParams, "twofish %s 0 %s 0", key, loopFile);
+    cryptParams += strlen(cryptParams) + 1;
+    cryptParams = (char *) _align(cryptParams, 8);
+    tgt->next = cryptParams - buffer;
+
+    if (ioctl(fd, DM_TABLE_LOAD, io)) {
+        LOGE("Error loading mapping table (%s)", strerror(errno));
+        free(buffer);
+        close(fd);
+        return -1;
+    }
+
+    // Resume the new table
+    ioctlInit(io, 4096, name, 0);
+
+    if (ioctl(fd, DM_DEV_SUSPEND, io)) {
+        LOGE("Error Resuming (%s)", strerror(errno));
+        free(buffer);
+        close(fd);
+        return -1;
+    }
+
+    free(buffer);
+
+    return 0;
+}
+
+int Devmapper::destroy(const char *name) {
+    char *buffer = (char *) malloc(4096);
+    if (!buffer) {
+        LOGE("Error allocating memory (%s)", strerror(errno));
+        return -1;
+    }
+
+    int fd;
+    if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
+        LOGE("Error opening devmapper (%s)", strerror(errno));
+        free(buffer);
+        return -1;
+    }
+
+    struct dm_ioctl *io = (struct dm_ioctl *) buffer;
+ 
+    // Create the DM device
+    ioctlInit(io, 4096, name, 0);
+
+    if (ioctl(fd, DM_DEV_REMOVE, io)) {
+        LOGE("Error destroying device mapping (%s)", strerror(errno));
+        free(buffer);
+        close(fd);
+        return -1;
+    }
+
+    free(buffer);
+    close(fd);
+    return 0;
+}
+
+void *Devmapper::_align(void *ptr, unsigned int a)
+{
+        register unsigned long agn = --a;
+
+        return (void *) (((unsigned long) ptr + agn) & ~agn);
+}
+