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/*
* 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 <errno.h>
#include <fcntl.h>
#include <mntent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <unistd.h>
#include <string>
#include "sysdeps.h"
#define TRACE_TAG TRACE_ADB
#include "adb.h"
#include "adb_io.h"
#include "cutils/properties.h"
static int system_ro = 1;
static int vendor_ro = 1;
static int oem_ro = 1;
/* Returns the device used to mount a directory in /proc/mounts */
static std::string find_mount(const char *dir) {
FILE* fp;
struct mntent* mentry;
char* device = NULL;
if ((fp = setmntent("/proc/mounts", "r")) == NULL) {
return NULL;
}
while ((mentry = getmntent(fp)) != NULL) {
if (strcmp(dir, mentry->mnt_dir) == 0) {
device = mentry->mnt_fsname;
break;
}
}
endmntent(fp);
return device;
}
static bool has_partition(const char* path) {
struct stat sb;
return (lstat(path, &sb) == 0 && S_ISDIR(sb.st_mode));
}
int make_block_device_writable(const std::string& dev) {
int fd = unix_open(dev.c_str(), O_RDONLY | O_CLOEXEC);
if (fd == -1) {
return -1;
}
int result = -1;
int OFF = 0;
if (!ioctl(fd, BLKROSET, &OFF)) {
result = 0;
}
adb_close(fd);
return result;
}
// Init mounts /system as read only, remount to enable writes.
static int remount(const char* dir, int* dir_ro) {
std::string dev(find_mount(dir));
if (dev.empty() || make_block_device_writable(dev)) {
return -1;
}
int rc = mount(dev.c_str(), dir, "none", MS_REMOUNT, NULL);
*dir_ro = rc;
return rc;
}
static bool remount_partition(int fd, const char* partition, int* ro) {
if (!has_partition(partition)) {
return true;
}
if (remount(partition, ro)) {
char buf[200];
snprintf(buf, sizeof(buf), "remount of %s failed: %s\n", partition, strerror(errno));
WriteStringFully(fd, buf);
return false;
}
return true;
}
void remount_service(int fd, void* cookie) {
char prop_buf[PROPERTY_VALUE_MAX];
if (getuid() != 0) {
WriteStringFully(fd, "Not running as root. Try \"adb root\" first.\n");
adb_close(fd);
return;
}
bool system_verified = false, vendor_verified = false;
property_get("partition.system.verified", prop_buf, "0");
if (!strcmp(prop_buf, "1")) {
system_verified = true;
}
property_get("partition.vendor.verified", prop_buf, "0");
if (!strcmp(prop_buf, "1")) {
vendor_verified = true;
}
if (system_verified || vendor_verified) {
// Allow remount but warn of likely bad effects
bool both = system_verified && vendor_verified;
char buffer[200];
snprintf(buffer, sizeof(buffer),
"dm_verity is enabled on the %s%s%s partition%s.\n",
system_verified ? "system" : "",
both ? " and " : "",
vendor_verified ? "vendor" : "",
both ? "s" : "");
WriteStringFully(fd, buffer);
snprintf(buffer, sizeof(buffer),
"Use \"adb disable-verity\" to disable verity.\n"
"If you do not, remount may succeed, however, you will still "
"not be able to write to these volumes.\n");
WriteStringFully(fd, buffer);
}
bool success = true;
success &= remount_partition(fd, "/system", &system_ro);
success &= remount_partition(fd, "/vendor", &vendor_ro);
success &= remount_partition(fd, "/oem", &oem_ro);
WriteStringFully(fd, success ? "remount succeeded\n" : "remount failed\n");
adb_close(fd);
}
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