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/*
* Copyright (C) 2014 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 "sysdeps.h"
#define TRACE_TAG TRACE_ADB
#include "adb.h"
#include <stdio.h>
#include <stdarg.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <inttypes.h>
#include "cutils/properties.h"
#include "ext4_sb.h"
#include <fs_mgr.h>
#define FSTAB_PREFIX "/fstab."
struct fstab *fstab;
__attribute__((__format__(printf, 2, 3))) __nonnull((2))
static void write_console(int fd, const char* format, ...)
{
char buffer[256];
va_list args;
va_start (args, format);
vsnprintf (buffer, sizeof(buffer), format, args);
va_end (args);
adb_write(fd, buffer, strnlen(buffer, sizeof(buffer)));
}
static int get_target_device_size(int fd, const char *blk_device,
uint64_t *device_size)
{
int data_device;
struct ext4_super_block sb;
struct fs_info info;
info.len = 0; /* Only len is set to 0 to ask the device for real size. */
data_device = adb_open(blk_device, O_RDONLY | O_CLOEXEC);
if (data_device < 0) {
write_console(fd, "Error opening block device (%s)\n", strerror(errno));
return -1;
}
if (lseek64(data_device, 1024, SEEK_SET) < 0) {
write_console(fd, "Error seeking to superblock\n");
adb_close(data_device);
return -1;
}
if (adb_read(data_device, &sb, sizeof(sb)) != sizeof(sb)) {
write_console(fd, "Error reading superblock\n");
adb_close(data_device);
return -1;
}
ext4_parse_sb(&sb, &info);
*device_size = info.len;
adb_close(data_device);
return 0;
}
static int disable_verity(int fd, const char *block_device,
const char* mount_point)
{
uint32_t magic_number;
const uint32_t voff = VERITY_METADATA_MAGIC_DISABLE;
uint64_t device_length;
int device;
int retval = -1;
device = adb_open(block_device, O_RDWR | O_CLOEXEC);
if (device == -1) {
write_console(fd, "Could not open block device %s (%s).\n",
block_device, strerror(errno));
write_console(fd, "Maybe run adb remount?\n");
goto errout;
}
// find the start of the verity metadata
if (get_target_device_size(fd, (char*)block_device, &device_length) < 0) {
write_console(fd, "Could not get target device size.\n");
goto errout;
}
if (lseek64(device, device_length, SEEK_SET) < 0) {
write_console(fd,
"Could not seek to start of verity metadata block.\n");
goto errout;
}
// check the magic number
if (adb_read(device, &magic_number, sizeof(magic_number))
!= sizeof(magic_number)) {
write_console(fd, "Couldn't read magic number!\n");
goto errout;
}
if (magic_number == VERITY_METADATA_MAGIC_DISABLE) {
write_console(fd, "Verity already disabled on %s\n", mount_point);
goto errout;
}
if (magic_number != VERITY_METADATA_MAGIC_NUMBER) {
write_console(fd,
"Couldn't find verity metadata at offset %"PRIu64"!\n",
device_length);
goto errout;
}
if (lseek64(device, device_length, SEEK_SET) < 0) {
write_console(fd,
"Could not seek to start of verity metadata block.\n");
goto errout;
}
if (adb_write(device, &voff, sizeof(voff)) != sizeof(voff)) {
write_console(fd, "Could not set verity disabled flag on device %s\n",
block_device);
goto errout;
}
write_console(fd, "Verity disabled on %s\n", mount_point);
retval = 0;
errout:
if (device != -1)
adb_close(device);
return retval;
}
void disable_verity_service(int fd, void* cookie)
{
#ifdef ALLOW_ADBD_DISABLE_VERITY
char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
char propbuf[PROPERTY_VALUE_MAX];
int i;
bool any_disabled = false;
property_get("ro.secure", propbuf, "0");
if (strcmp(propbuf, "1")) {
write_console(fd, "verity not enabled - ENG build\n");
goto errout;
}
property_get("ro.debuggable", propbuf, "0");
if (strcmp(propbuf, "1")) {
write_console(fd, "verity cannot be disabled - USER build\n");
goto errout;
}
property_get("ro.hardware", propbuf, "");
snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
fstab = fs_mgr_read_fstab(fstab_filename);
if (!fstab) {
write_console(fd, "Failed to open %s\nMaybe run adb root?\n",
fstab_filename);
goto errout;
}
/* Loop through entries looking for ones that vold manages */
for (i = 0; i < fstab->num_entries; i++) {
if(fs_mgr_is_verified(&fstab->recs[i])) {
if (!disable_verity(fd, fstab->recs[i].blk_device,
fstab->recs[i].mount_point)) {
any_disabled = true;
}
}
}
if (any_disabled) {
write_console(fd,
"Now reboot your device for settings to take effect\n");
}
#else
write_console(fd, "disable-verity only works for userdebug builds\n");
#endif
errout:
adb_close(fd);
}
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