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

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

.SH "SYNOPSIS"

.PP systemd-mountfsd.service

.PP /usr/lib/systemd/systemd-mountfsd

.SH "DESCRIPTION"

.PP **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.

.PP The disk images provided must contain a raw file system image or must follow the **UAPI.2 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/\*.crt (and related directories) the disk image is considered trusted. Note that the GPT partition table of the disk image is parsed by the kernel to discover its contents and **systemd-mountfsd** assumes that the GPT parser is robust against malformed input and applies no security policies or checks around it.

.PP 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.

.PP The returned mounts are automatically allowlisted in the per-user-namespace allowlist maintained by [**systemd-nsresourced.service**(8)](/man/os/systemd/systemd-nsresourced.service.8).

.PP The file systems are automatically [**fsck**(8)](/man/os/systemd/fsck.8)'ed before mounting.

.SH "SEE ALSO"

.PP [**systemd**(1)](/man/os/systemd/systemd.1), [**systemd-nsresourced.service**(8)](/man/os/systemd/systemd-nsresourced.service.8)

# [NOTES](#NOTES)

1\.

UAPI.2 Discoverable Partitions Specification

https://uapi-group.org/specifications/specs/discoverable\_partitions\_specification/

2\.

Varlink

https://varlink.org/

systemd 262.2

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Document: systemd-mountfsd.service(8) from systemd 262.2-r1 (Chainguard OS)
Source: https://github.com/systemd/systemd