volume_manager/fs/Ext4.cpp

/*
 * Copyright (C) 2012 The Android Open Source Project
 * Copyright (C) 2019 The LineageOS 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 <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <string>
#include <vector>

#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <linux/kdev_t.h>

#define LOG_TAG "Vold"
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <cutils/log.h>
#include <cutils/properties.h>
#include <logwrap/logwrap.h>
#include <private/android_filesystem_config.h>
#include <selinux/selinux.h>

#include "Ext4.h"
#include "Utils.h"

using android::base::StringPrintf;

namespace android {
namespace volmgr {
namespace ext4 {

static const char* kFsckPath = "/sbin/e2fsck";

bool IsSupported() {
    return access(kFsckPath, X_OK) == 0 && IsFilesystemSupported("ext4");
}

status_t Check(const std::string& source, const std::string& target, bool trusted) {
    // The following is shamelessly borrowed from fs_mgr.c, so it should be
    // kept in sync with any changes over there.

    const char* c_source = source.c_str();
    const char* c_target = target.c_str();

    int ret;
    long tmpmnt_flags = MS_NOATIME | MS_NOEXEC | MS_NOSUID;
    char* tmpmnt_opts = (char*)"nomblk_io_submit,errors=remount-ro";

    /*
     * First try to mount and unmount the filesystem.  We do this because
     * the kernel is more efficient than e2fsck in running the journal and
     * processing orphaned inodes, and on at least one device with a
     * performance issue in the emmc firmware, it can take e2fsck 2.5 minutes
     * to do what the kernel does in about a second.
     *
     * After mounting and unmounting the filesystem, run e2fsck, and if an
     * error is recorded in the filesystem superblock, e2fsck will do a full
     * check.  Otherwise, it does nothing.  If the kernel cannot mount the
     * filesytsem due to an error, e2fsck is still run to do a full check
     * fix the filesystem.
     */
    ret = mount(c_source, c_target, "ext4", tmpmnt_flags, tmpmnt_opts);
    if (!ret) {
        int i;
        for (i = 0; i < 5; i++) {
            // Try to umount 5 times before continuing on.
            // Should we try rebooting if all attempts fail?
            int result = umount(c_target);
            if (result == 0) {
                break;
            }
            ALOGW("%s(): umount(%s)=%d: %s\n", __func__, c_target, result, strerror(errno));
            sleep(1);
        }
    }

    /*
     * Some system images do not have e2fsck for licensing reasons
     * (e.g. recent SDK system images). Detect these and skip the check.
     */
    if (access(kFsckPath, X_OK)) {
        ALOGD("Not running %s on %s (executable not in system image)\n", kFsckPath, c_source);
    } else {
        ALOGD("Running %s on %s\n", kFsckPath, c_source);

        std::vector<std::string> cmd;
        cmd.push_back(kFsckPath);
        cmd.push_back("-y");
        cmd.push_back(c_source);

        return ForkExecvp(cmd, trusted ? sFsckContext : sFsckUntrustedContext);
    }

    return 0;
}

status_t Mount(const std::string& source, const std::string& target, bool ro, bool remount,
               bool executable, const std::string& opts /* = "" */, bool trusted, bool portable) {
    int rc;
    unsigned long flags;

    std::string data(opts);

    if (portable) {
        if (!data.empty()) {
            data += ",";
        }
        data += "context=u:object_r:sdcard_posix:s0";
    }
    const char* c_source = source.c_str();
    const char* c_target = target.c_str();
    const char* c_data = data.c_str();

    flags = MS_NOATIME | MS_NODEV | MS_NOSUID;

    // Only use MS_DIRSYNC if we're not mounting adopted storage
    if (!trusted) {
        flags |= MS_DIRSYNC;
    }

    flags |= (executable ? 0 : MS_NOEXEC);
    flags |= (ro ? MS_RDONLY : 0);
    flags |= (remount ? MS_REMOUNT : 0);

    rc = mount(c_source, c_target, "ext4", flags, c_data);
    if (portable && rc == 0) {
        chown(c_target, AID_MEDIA_RW, AID_MEDIA_RW);
        chmod(c_target, 0775);
    }

    if (rc && errno == EROFS) {
        SLOGE("%s appears to be a read only filesystem - retrying mount RO", c_source);
        flags |= MS_RDONLY;
        rc = mount(c_source, c_target, "ext4", flags, c_data);
    }

    return rc;
}

}  // namespace ext4
}  // namespace volmgr
}  // namespace android