roots.cpp

/*
 * Copyright (C) 2007 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 <stdlib.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <ctype.h>
#include <fcntl.h>

#include <fs_mgr.h>
#include "mtdutils/mtdutils.h"
#include "mtdutils/mounts.h"
#include "roots.h"
#include "common.h"
#include "make_ext4fs.h"
extern "C" {
#include "wipe.h"
#include "cryptfs.h"
}

static struct fstab *fstab = NULL;

extern struct selabel_handle *sehandle;

static const char* PERSISTENT_PATH = "/persistent";

void load_volume_table()
{
 int i;
 int ret;

 fstab = fs_mgr_read_fstab("/etc/recovery.fstab");
 if (!fstab) {
 LOGE("failed to read /etc/recovery.fstab\n");
 return;
 }

 ret = fs_mgr_add_entry(fstab, "/tmp", "ramdisk", "ramdisk");
 if (ret < 0 ) {
 LOGE("failed to add /tmp entry to fstab\n");
 fs_mgr_free_fstab(fstab);
 fstab = NULL;
 return;
 }

 printf("recovery filesystem table\n");
 printf("=========================\n");
 for (i = 0; i < fstab->num_entries; ++i) {
 Volume* v = &fstab->recs[i];
 printf(" %d %s %s %s %lld\n", i, v->mount_point, v->fs_type,
 v->blk_device, v->length);
 }
 printf("\n");
}

Volume* volume_for_path(const char* path) {
 return fs_mgr_get_entry_for_mount_point(fstab, path);
}

int ensure_path_mounted(const char* path) {
 Volume* v = volume_for_path(path);
 if (v == NULL) {
 LOGE("unknown volume for path [%s]\n", path);
 return -1;
 }
 if (strcmp(v->fs_type, "ramdisk") == 0) {
 // the ramdisk is always mounted.
 return 0;
 }

 int result;
 result = scan_mounted_volumes();
 if (result < 0) {
 LOGE("failed to scan mounted volumes\n");
 return -1;
 }

 const MountedVolume* mv =
 find_mounted_volume_by_mount_point(v->mount_point);
 if (mv) {
 // volume is already mounted
 return 0;
 }

 mkdir(v->mount_point, 0755); // in case it doesn't already exist

 if (strcmp(v->fs_type, "yaffs2") == 0) {
 // mount an MTD partition as a YAFFS2 filesystem.
 mtd_scan_partitions();
 const MtdPartition* partition;
 partition = mtd_find_partition_by_name(v->blk_device);
 if (partition == NULL) {
 LOGE("failed to find \"%s\" partition to mount at \"%s\"\n",
 v->blk_device, v->mount_point);
 return -1;
 }
 return mtd_mount_partition(partition, v->mount_point, v->fs_type, 0);
 } else if (strcmp(v->fs_type, "ext4") == 0 ||
 strcmp(v->fs_type, "vfat") == 0) {
 result = mount(v->blk_device, v->mount_point, v->fs_type,
 MS_NOATIME | MS_NODEV | MS_NODIRATIME, "");
 if (result == 0) return 0;

 LOGE("failed to mount %s (%s)\n", v->mount_point, strerror(errno));
 return -1;
 }

 LOGE("unknown fs_type \"%s\" for %s\n", v->fs_type, v->mount_point);
 return -1;
}

int ensure_path_unmounted(const char* path) {
 Volume* v = volume_for_path(path);
 if (v == NULL) {
 LOGE("unknown volume for path [%s]\n", path);
 return -1;
 }
 if (strcmp(v->fs_type, "ramdisk") == 0) {
 // the ramdisk is always mounted; you can't unmount it.
 return -1;
 }

 int result;
 result = scan_mounted_volumes();
 if (result < 0) {
 LOGE("failed to scan mounted volumes\n");
 return -1;
 }

 const MountedVolume* mv =
 find_mounted_volume_by_mount_point(v->mount_point);
 if (mv == NULL) {
 // volume is already unmounted
 return 0;
 }

 return unmount_mounted_volume(mv);
}

static int exec_cmd(const char* path, char* const argv[]) {
 int status;
 pid_t child;
 if ((child = vfork()) == 0) {
 execv(path, argv);
 _exit(-1);
 }
 waitpid(child, &status, 0);
 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 LOGE("%s failed with status %d\n", path, WEXITSTATUS(status));
 }
 return WEXITSTATUS(status);
}

int format_volume(const char* volume) {
 Volume* v = volume_for_path(volume);
 if (v == NULL) {
 LOGE("unknown volume \"%s\"\n", volume);
 return -1;
 }
 if (strcmp(v->fs_type, "ramdisk") == 0) {
 // you can't format the ramdisk.
 LOGE("can't format_volume \"%s\"", volume);
 return -1;
 }
 if (strcmp(v->mount_point, volume) != 0) {
 LOGE("can't give path \"%s\" to format_volume\n", volume);
 return -1;
 }

 if (ensure_path_unmounted(volume) != 0) {
 LOGE("format_volume failed to unmount \"%s\"\n", v->mount_point);
 return -1;
 }

 if (strcmp(v->fs_type, "yaffs2") == 0 || strcmp(v->fs_type, "mtd") == 0) {
 mtd_scan_partitions();
 const MtdPartition* partition = mtd_find_partition_by_name(v->blk_device);
 if (partition == NULL) {
 LOGE("format_volume: no MTD partition \"%s\"\n", v->blk_device);
 return -1;
 }

 MtdWriteContext *write = mtd_write_partition(partition);
 if (write == NULL) {
 LOGW("format_volume: can't open MTD \"%s\"\n", v->blk_device);
 return -1;
 } else if (mtd_erase_blocks(write, -1) == (off_t) -1) {
 LOGW("format_volume: can't erase MTD \"%s\"\n", v->blk_device);
 mtd_write_close(write);
 return -1;
 } else if (mtd_write_close(write)) {
 LOGW("format_volume: can't close MTD \"%s\"\n", v->blk_device);
 return -1;
 }
 return 0;
 }

 if (strcmp(v->fs_type, "ext4") == 0 || strcmp(v->fs_type, "f2fs") == 0) {
 // if there's a key_loc that looks like a path, it should be a
 // block device for storing encryption metadata. wipe it too.
 if (v->key_loc != NULL && v->key_loc[0] == '/') {
 LOGI("wiping %s\n", v->key_loc);
 int fd = open(v->key_loc, O_WRONLY | O_CREAT, 0644);
 if (fd < 0) {
 LOGE("format_volume: failed to open %s\n", v->key_loc);
 return -1;
 }
 wipe_block_device(fd, get_file_size(fd));
 close(fd);
 }

 ssize_t length = 0;
 if (v->length != 0) {
 length = v->length;
 } else if (v->key_loc != NULL && strcmp(v->key_loc, "footer") == 0) {
 length = -CRYPT_FOOTER_OFFSET;
 }
 int result;
 if (strcmp(v->fs_type, "ext4") == 0) {
 result = make_ext4fs(v->blk_device, length, volume, sehandle);
 } else { /* Has to be f2fs because we checked earlier. */
 char bytes_reserved[10] = {0};
 if (v->key_loc != NULL && strcmp(v->key_loc, "footer") == 0) {
 snprintf(bytes_reserved, sizeof(bytes_reserved), "%d", CRYPT_FOOTER_OFFSET);
 }
 char *num_sectors;
 if (asprintf(&num_sectors, "%zd", length / 512) <= 0) {
 LOGE("format_volume: failed to create %s command for %s\n", v->fs_type, v->blk_device);
 return -1;
 }
 const char *f2fs_path = "/sbin/mkfs.f2fs";
 const char* const f2fs_argv[] = {"mkfs.f2fs", "-t", "-d1", "-r",
 bytes_reserved, v->blk_device, NULL};

 result = exec_cmd(f2fs_path, (char* const*)f2fs_argv);
 free(num_sectors);
 }
 if (result != 0) {
 LOGE("format_volume: make %s failed on %s with %d(%s)\n", v->fs_type, v->blk_device, result, strerror(errno));
 return -1;
 }
 return 0;
 }

 LOGE("format_volume: fs_type \"%s\" unsupported\n", v->fs_type);
 return -1;
}

int erase_persistent_partition() {
 Volume *v = volume_for_path(PERSISTENT_PATH);
 if (v == NULL) {
 // most devices won't have /persistent, so this is not an error.
 return 0;
 }

 int fd = open(v->blk_device, O_RDWR);
 uint64_t size = get_file_size(fd);
 if (size == 0) {
 LOGE("failed to stat size of /persistent\n");
 close(fd);
 return -1;
 }

 char oem_unlock_enabled;
 lseek(fd, size - 1, SEEK_SET);
 read(fd, &oem_unlock_enabled, 1);

 if (oem_unlock_enabled) {
 if (wipe_block_device(fd, size)) {
 LOGE("error wiping /persistent: %s\n", strerror(errno));
 close(fd);
 return -1;
 }

 lseek(fd, size - 1, SEEK_SET);
 write(fd, &oem_unlock_enabled, 1);
 }

 close(fd);

 return (int) oem_unlock_enabled;
}

int setup_install_mounts() {
 if (fstab == NULL) {
 LOGE("can't set up install mounts: no fstab loaded\n");
 return -1;
 }
 for (int i = 0; i < fstab->num_entries; ++i) {
 Volume* v = fstab->recs + i;

 if (strcmp(v->mount_point, "/tmp") == 0 ||
 strcmp(v->mount_point, "/cache") == 0) {
 if (ensure_path_mounted(v->mount_point) != 0) {
 LOGE("failed to mount %s\n", v->mount_point);
 return -1;
 }

 } else {
 if (ensure_path_unmounted(v->mount_point) != 0) {
 LOGE("failed to unmount %s\n", v->mount_point);
 return -1;
 }
 }
 }
 return 0;
}