# systemd-validatefs@.service

## NAME



           systemd-validatefs@.service - Validate File System Mount
           Constraint Data
    


## SYNOPSIS



           systemd-validatefs@.service
    
           /usr/lib/systemd/systemd-validatefs [_DEVICE_]
    


## DESCRIPTION



           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't the service fails,
           which effects an immediate reboot.
    
           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 systemd-gpt-auto-generator(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.
    
           Specifically, the mount constraints are encoded in the following
           extended attributes on the root inode of the file systems:
    
            1. _user.validatefs.mount_point_ : 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.
    
            2. _user.validatefs.gpt_label_ : 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's 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.
    
            3. _user.validatefs.gpt_type_uuid_ : 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.
    
           The systemd-validatefs@.service unit is automatically pulled into
           the initial transaction by systemd-gpt-auto-generator(8) for all
           file systems it discovers and generates mounts for.
           systemd-fstab-generator(8) will do this for all mounts with the
           **x-systemd.validatefs** mount option in /etc/fstab.
    
           The systemd-repart(8) tool generates these extended attributes
           automatically for the file systems it puts together, which may be
           controlled with the _AddValidateFS=_ configuration option.
    


## OPTIONS



           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:
    
           **--root=**
               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.
    
               Added in version 258.
    
           **-h** , **--help**
               Print a short help text and exit.
    
           **--version**
               Print a short version string and exit.
    


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