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 "roots.h"

#include <ctype.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <cryptfs.h>
#include <ext4_utils/wipe.h>
#include <fs_mgr.h>

#include "common.h"
#include "mounts.h"

static struct fstab* fstab = nullptr;

extern struct selabel_handle* sehandle;

void load_volume_table() {
  fstab = fs_mgr_read_fstab_default();
  if (!fstab) {
    LOG(ERROR) << "Failed to read default fstab";
    return;
  }

  int ret = fs_mgr_add_entry(fstab, "/tmp", "ramdisk", "ramdisk");
  if (ret == -1) {
    LOG(ERROR) << "Failed to add /tmp entry to fstab";
    fs_mgr_free_fstab(fstab);
    fstab = nullptr;
    return;
  }

  printf("recovery filesystem table\n");
  printf("=========================\n");
  for (int i = 0; i < fstab->num_entries; ++i) {
    const 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);
}

// Mount the volume specified by path at the given mount_point.
int ensure_path_mounted_at(const char* path, const char* mount_point) {
  Volume* v = volume_for_path(path);
  if (v == nullptr) {
    LOG(ERROR) << "unknown volume for path [" << path << "]";
    return -1;
  }
  if (strcmp(v->fs_type, "ramdisk") == 0) {
    // The ramdisk is always mounted.
    return 0;
  }

  if (!scan_mounted_volumes()) {
    LOG(ERROR) << "Failed to scan mounted volumes";
    return -1;
  }

  if (!mount_point) {
    mount_point = v->mount_point;
  }

  const MountedVolume* mv = find_mounted_volume_by_mount_point(mount_point);
  if (mv != nullptr) {
    // Volume is already mounted.
    return 0;
  }

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

  if (strcmp(v->fs_type, "ext4") == 0 || strcmp(v->fs_type, "squashfs") == 0 ||
      strcmp(v->fs_type, "vfat") == 0) {
    int result = mount(v->blk_device, mount_point, v->fs_type, v->flags, v->fs_options);
    if (result == -1 && fs_mgr_is_formattable(v)) {
      PLOG(ERROR) << "Failed to mount " << mount_point << "; formatting";
      bool crypt_footer = fs_mgr_is_encryptable(v) && !strcmp(v->key_loc, "footer");
      if (fs_mgr_do_format(v, crypt_footer) == 0) {
        result = mount(v->blk_device, mount_point, v->fs_type, v->flags, v->fs_options);
      } else {
        PLOG(ERROR) << "Failed to format " << mount_point;
        return -1;
      }
    }

    if (result == -1) {
      PLOG(ERROR) << "Failed to mount " << mount_point;
      return -1;
    }
    return 0;
  }

  LOG(ERROR) << "unknown fs_type \"" << v->fs_type << "\" for " << mount_point;
  return -1;
}

int ensure_path_mounted(const char* path) {
  // Mount at the default mount point.
  return ensure_path_mounted_at(path, nullptr);
}

int ensure_path_unmounted(const char* path) {
  const Volume* v = volume_for_path(path);
  if (v == nullptr) {
    LOG(ERROR) << "unknown volume for path [" << path << "]";
    return -1;
  }
  if (strcmp(v->fs_type, "ramdisk") == 0) {
    // The ramdisk is always mounted; you can't unmount it.
    return -1;
  }

  if (!scan_mounted_volumes()) {
    LOG(ERROR) << "Failed to scan mounted volumes";
    return -1;
  }

  MountedVolume* mv = find_mounted_volume_by_mount_point(v->mount_point);
  if (mv == nullptr) {
    // 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(EXIT_FAILURE);
    }
    waitpid(child, &status, 0);
    if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
        LOG(ERROR) << path << " failed with status " << WEXITSTATUS(status);
    }
    return WEXITSTATUS(status);
}

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

    if (ensure_path_unmounted(volume) != 0) {
        LOG(ERROR) << "format_volume failed to unmount \"" << v->mount_point << "\"";
        return -1;
    }

    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] == '/') {
            LOG(INFO) << "wiping " << v->key_loc;
            int fd = open(v->key_loc, O_WRONLY | O_CREAT, 0644);
            if (fd < 0) {
                LOG(ERROR) << "format_volume: failed to open " << 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) {
          static constexpr int block_size = 4096;
          int raid_stride = v->logical_blk_size / block_size;
          int raid_stripe_width = v->erase_blk_size / block_size;

          // stride should be the max of 8kb and logical block size
          if (v->logical_blk_size != 0 && v->logical_blk_size < 8192) {
            raid_stride = 8192 / block_size;
          }

          const char* mke2fs_argv[] = { "/sbin/mke2fs_static",
                                        "-F",
                                        "-t",
                                        "ext4",
                                        "-b",
                                        nullptr,
                                        nullptr,
                                        nullptr,
                                        nullptr,
                                        nullptr,
                                        nullptr };

          int i = 5;
          std::string block_size_str = std::to_string(block_size);
          mke2fs_argv[i++] = block_size_str.c_str();

          std::string ext_args;
          if (v->erase_blk_size != 0 && v->logical_blk_size != 0) {
            ext_args = android::base::StringPrintf("stride=%d,stripe-width=%d", raid_stride,
                                                   raid_stripe_width);
            mke2fs_argv[i++] = "-E";
            mke2fs_argv[i++] = ext_args.c_str();
          }

          mke2fs_argv[i++] = v->blk_device;

          std::string size_str = std::to_string(length / block_size);
          if (length != 0) {
            mke2fs_argv[i++] = size_str.c_str();
          }

          result = exec_cmd(mke2fs_argv[0], const_cast<char**>(mke2fs_argv));
          if (result == 0 && directory != nullptr) {
            const char* e2fsdroid_argv[] = { "/sbin/e2fsdroid_static",
                                             "-e",
                                             "-f",
                                             directory,
                                             "-a",
                                             volume,
                                             v->blk_device,
                                             nullptr };

            result = exec_cmd(e2fsdroid_argv[0], const_cast<char**>(e2fsdroid_argv));
          }
        } else {   /* Has to be f2fs because we checked earlier. */
            if (v->key_loc != NULL && strcmp(v->key_loc, "footer") == 0 && length < 0) {
                LOG(ERROR) << "format_volume: crypt footer + negative length (" << length
                           << ") not supported on " << v->fs_type;
                return -1;
            }
            if (length < 0) {
                LOG(ERROR) << "format_volume: negative length (" << length
                           << ") not supported on " << v->fs_type;
                return -1;
            }
            char *num_sectors = nullptr;
            if (length >= 512 && asprintf(&num_sectors, "%zd", length / 512) <= 0) {
                LOG(ERROR) << "format_volume: failed to create " << v->fs_type
                           << " command for " << v->blk_device;
                return -1;
            }
            const char *f2fs_path = "/sbin/mkfs.f2fs";
            const char* const f2fs_argv[] = {"mkfs.f2fs", "-t", "-d1", v->blk_device, num_sectors, nullptr};

            result = exec_cmd(f2fs_path, (char* const*)f2fs_argv);
            free(num_sectors);
        }
        if (result != 0) {
            PLOG(ERROR) << "format_volume: make " << v->fs_type << " failed on " << v->blk_device;
            return -1;
        }
        return 0;
    }

    LOG(ERROR) << "format_volume: fs_type \"" << v->fs_type << "\" unsupported";
    return -1;
}

int format_volume(const char* volume) {
  return format_volume(volume, nullptr);
}

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

    // We don't want to do anything with "/".
    if (strcmp(v->mount_point, "/") == 0) {
      continue;
    }

    if (strcmp(v->mount_point, "/tmp") == 0 || strcmp(v->mount_point, "/cache") == 0) {
      if (ensure_path_mounted(v->mount_point) != 0) {
        LOG(ERROR) << "Failed to mount " << v->mount_point;
        return -1;
      }
    } else {
      if (ensure_path_unmounted(v->mount_point) != 0) {
        LOG(ERROR) << "Failed to unmount " << v->mount_point;
        return -1;
      }
    }
  }
  return 0;
}