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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.
*/
#define TRACE_TAG ADB
#include "sysdeps.h"
#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 <android-base/properties.h>
#include "adb.h"
#include "adb_io.h"
#include "adb_utils.h"
#include "fs_mgr.h"
// Returns the device used to mount a directory in /proc/mounts.
static std::string find_proc_mount(const char* dir) {
std::unique_ptr<FILE, int(*)(FILE*)> fp(setmntent("/proc/mounts", "r"), endmntent);
if (!fp) {
return "";
}
mntent* e;
while ((e = getmntent(fp.get())) != nullptr) {
if (strcmp(dir, e->mnt_dir) == 0) {
return e->mnt_fsname;
}
}
return "";
}
// Returns the device used to mount a directory in the fstab.
static std::string find_fstab_mount(const char* dir) {
std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
fs_mgr_free_fstab);
struct fstab_rec* rec = fs_mgr_get_entry_for_mount_point(fstab.get(), dir);
return rec ? rec->blk_device : "";
}
// The proc entry for / is full of lies, so check fstab instead.
// /proc/mounts lists rootfs and /dev/root, neither of which is what we want.
static std::string find_mount(const char* dir) {
if (strcmp(dir, "/") == 0) {
return find_fstab_mount(dir);
} else {
return find_proc_mount(dir);
}
}
bool make_block_device_writable(const std::string& dev) {
int fd = unix_open(dev.c_str(), O_RDONLY | O_CLOEXEC);
if (fd == -1) {
return false;
}
int OFF = 0;
bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
unix_close(fd);
return result;
}
static bool remount_partition(int fd, const char* dir) {
if (!directory_exists(dir)) {
return true;
}
std::string dev = find_mount(dir);
if (dev.empty()) {
return true;
}
if (!make_block_device_writable(dev)) {
WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",
dir, dev.c_str(), strerror(errno));
return false;
}
if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {
WriteFdFmt(fd, "remount of %s failed: %s\n", dir, strerror(errno));
return false;
}
return true;
}
void remount_service(int fd, void* cookie) {
if (getuid() != 0) {
WriteFdExactly(fd, "Not running as root. Try \"adb root\" first.\n");
adb_close(fd);
return;
}
bool system_verified = !(android::base::GetProperty("partition.system.verified", "").empty());
bool vendor_verified = !(android::base::GetProperty("partition.vendor.verified", "").empty());
if (system_verified || vendor_verified) {
// Allow remount but warn of likely bad effects
bool both = system_verified && vendor_verified;
WriteFdFmt(fd,
"dm_verity is enabled on the %s%s%s partition%s.\n",
system_verified ? "system" : "",
both ? " and " : "",
vendor_verified ? "vendor" : "",
both ? "s" : "");
WriteFdExactly(fd,
"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");
}
bool success = true;
if (android::base::GetBoolProperty("ro.build.system_root_image", false)) {
success &= remount_partition(fd, "/");
} else {
success &= remount_partition(fd, "/system");
}
success &= remount_partition(fd, "/vendor");
success &= remount_partition(fd, "/oem");
WriteFdExactly(fd, success ? "remount succeeded\n" : "remount failed\n");
adb_close(fd);
}
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