SYSTEMD-MOUNTFSD.SERVICE(8)                           systemd-mountfsd.service

NAME
       systemd-mountfsd.service, systemd-mountfsd - Disk Image File System
       Mount Service

SYNOPSIS
       systemd-mountfsd.service

       /usr/lib/systemd/systemd-mountfsd

DESCRIPTION
       systemd-mountfsd is a system service that dissects disk images, and
       returns mount file descriptors for the file systems contained therein
       to clients, via a Varlink IPC API.

       The disk images provided must contain a raw file system image or must
       follow the Discoverable Partitions Specification[1]. Before mounting
       any file systems authenticity of the disk image is established in one
       or a combination of the following ways:

        1. If the disk image is located in a regular file in one of the
           directories /var/lib/machines/, /var/lib/portables/,
           /var/lib/extensions/, /var/lib/confexts/ or their counterparts in
           the /etc/, /run/, /usr/lib/ it is assumed to be trusted.

        2. If the disk image contains a Verity enabled disk image, along with
           a signature partition with a key in the kernel keyring or in
           /etc/verity.d/ (and related directories) the disk image is
           considered trusted.

       This service provides one Varlink[2] service:
       io.systemd.MountFileSystem which accepts a file descriptor to a regular
       file or block device, and returns a number of file descriptors
       referring to an fsmount() file descriptor the client may then attach to
       a path of their choice.

       The returned mounts are automatically allowlisted in the
       per-user-namespace allowlist maintained by systemd-
       nsresourced.service(8).

       The file systems are automatically fsck'ed before mounting.

SEE ALSO
       systemd(1), systemd-nsresourced.service(8)

NOTES
        1. Discoverable Partitions Specification
           https://uapi-
           group.org/specifications/specs/discoverable_partitions_specification/

        2. Varlink
           https://varlink.org/

systemd 256.7                                      SYSTEMD-MOUNTFSD.SERVICE(8)