'\" t
.TH "SYSTEMD\-VALIDATEFS@\&.SERVICE" "8" "" "systemd 258" "systemd-validatefs@.service"
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.SH "NAME"
systemd-validatefs@.service \- Validate File System Mount Constraint Data
.SH "SYNOPSIS"
.PP
systemd\-validatefs@\&.service
.PP
/usr/lib/systemd/systemd\-validatefs
[\fIDEVICE\fR]
.SH "DESCRIPTION"
.PP
systemd\-validatefs@\&.service
is a system service template that can be instantiated for newly established mount points\&. It reads file system mount constraint data from the file system, and ensures the mount runtime setup matches it\&. If it doesn\*(Aqt the service fails, which effects an immediate reboot\&.
.PP
This functionality is supposed to ensure that trusted file systems cannot be used in a different context then what they were intended for\&. More specifically: in an
\fBsystemd-gpt-auto-generator\fR(8)
based environment the file systems to mount are largely auto\-discovered based on (unprotected) GPT partition table data\&. The mount constraint information can be used to validate the GPT partition data, based on the (protected) file system contents\&.
.PP
Specifically, the mount constraints are encoded in the following extended attributes on the root inode of the file systems:
.sp
.RS 4
.ie n \{\
\h'-04' 1.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  1." 4.2
.\}
\fIuser\&.validatefs\&.mount_point\fR: this extended attribute shall contain one or more absolute, normalized paths, separated by NUL bytes\&. If set and the specified file system is mounted to a location not matching any of the listed paths the validation check will fail\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 2.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  2." 4.2
.\}
\fIuser\&.validatefs\&.gpt_label\fR: this extended attribute may contain one or more free\-form strings, separated by NUL bytes\&. If set, all backing partitions of the file system are checked against this list, and if any backing partition\*(Aqs label is not listed, the validation will fail\&. Note that there may be multiple backing partition in case of Verity setups, which combines a data and a hash partition\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04' 3.\h'+01'\c
.\}
.el \{\
.sp -1
.IP "  3." 4.2
.\}
\fIuser\&.validatefs\&.gpt_type_uuid\fR: this extended attribute may contain one or more GPT partition type UUIDs, formatted as string, separated by NUL bytes\&. As above, all backing partitions of the file system are checked against this list, and if none is matching the validation will fail\&.
.RE
.PP
The
systemd\-validatefs@\&.service
unit is automatically pulled into the initial transaction by
\fBsystemd-gpt-auto-generator\fR(8)
for all file systems it discovers and generates mounts for\&.
\fBsystemd-fstab-generator\fR(8)
will do this for all mounts with the
\fBx\-systemd\&.validatefs\fR
mount option in
/etc/fstab\&.
.PP
The
\fBsystemd-repart\fR(8)
tool generates these extended attributes automatically for the file systems it puts together, which may be controlled with the
\fIAddValidateFS=\fR
configuration option\&.
.SH "OPTIONS"
.PP
The
/usr/lib/systemd/system\-validatefs
executable may also be invoked from the command line, where it expects a path to a mount and the following options:
.PP
\fB\-\-root=\fR
.RS 4
Takes an absolute path or the special string
"auto"\&. The specified path is removed as prefix from the specified mount point argument before the validation\&. If set to
"auto"
defaults to unspecified on the host and
/sysroot/
when run in initrd context, in order to validate the mount constraint data relative to the future file system root\&.
.sp
Added in version 258\&.
.RE
.PP
\fB\-h\fR, \fB\-\-help\fR
.RS 4
Print a short help text and exit\&.
.RE
.PP
\fB\-\-version\fR
.RS 4
Print a short version string and exit\&.
.RE
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1), \fBsystemd-gpt-auto-generator\fR(8), \fBsystemd-fstab-generator\fR(8), \fBsystemd-repart\fR(8)