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Commit f48d5778 authored by Yi-Yo Chiang's avatar Yi-Yo Chiang
Browse files

remount: Check device mapper to see if verity is already disabled 

No matter verity is enabled or disabled, androidboot.veritymode is
always "enforcing" on emulator kernel cmdline.

This is a violation of the AVB contract:
https://cs.android.com/android/platform/superproject/+/master:external/avb/README.md#handling-dm-verity-errors

Before emulator can fix this, workaround this by checking the device
mapper table to see if verity is disabled or not.
If no "<partition>-verity" device is present, than assume verity is
already disabled.

Also log mountpoints that are successfully remounted.

Bug: 241688845
Bug: 259207493
Test: adb-remount-test
Test: Run adb remount on emulator
Change-Id: Id5767b05cbfb48adf2a8c372dfdad4d15b98e091
parent 4cdb6cf4

fs_mgr/fs_mgr_remount.cpp

+20 −13
Original line number Diff line number Diff line
@@ -386,15 +386,14 @@ bool RemountPartition(Fstab& fstab, Fstab& mounts, FstabEntry& entry) { 
    }



    // Now remount!

    if (::mount(blk_device.c_str(), mount_point.c_str(), entry.fs_type.c_str(), MS_REMOUNT,

    for (const auto& mnt_point : {mount_point, entry.mount_point}) {

        if (::mount(blk_device.c_str(), mnt_point.c_str(), entry.fs_type.c_str(), MS_REMOUNT,

                    nullptr) == 0) {

            LOG(INFO) << "Remounted " << mnt_point << " as RW";

            return true;

        }

    if ((errno == EINVAL) && (mount_point != entry.mount_point)) {

        mount_point = entry.mount_point;

        if (::mount(blk_device.c_str(), mount_point.c_str(), entry.fs_type.c_str(), MS_REMOUNT,

                    nullptr) == 0) {

            return true;

        if (errno != EINVAL || mount_point == entry.mount_point) {

            break;

        }

    }
@@ -484,8 +483,16 @@ bool do_remount(Fstab& fstab, const std::vector<std::string>& partition_args, 
        return false;

    }

    if (verity_result.want_reboot) {

        // TODO(b/259207493): emulator has incorrect androidboot.veritymode value, causing

        // .want_reboot to always be true. In order to workaround this, double check device mapper

        // to see if verity is already disabled.

        for (const auto& partition : partitions) {

            if (fs_mgr_is_verity_enabled(partition)) {

                check_result->reboot_later = true;

                check_result->disabled_verity = true;

                break;

            }

        }

    }



    // Optionally setup overlayfs backing.
@@ -660,10 +667,10 @@ int main(int argc, char* argv[]) { 
    } else if (check_result.setup_overlayfs) {

        LOG(INFO) << "Overlayfs enabled.";

    }

    if (remount_success) {

        LOG(INFO) << "remount succeeded";

    } else {

        LOG(ERROR) << "remount failed";

    if (remount_success && check_result.remounted_anything) {

        LOG(INFO) << "Remount succeeded";

    } else if (!remount_success) {

        LOG(ERROR) << "Remount failed";

    }

    if (check_result.reboot_later) {

        if (auto_reboot) {