Plugin: path

• infos = Information about path plugin is in keys below
• infos/author = Markus Raab elekt.nosp@m.ra@l.nosp@m.ibele.nosp@m.ktra.nosp@m..org
• infos/licence = BSD
• infos/placements = presetstorage
• infos/needs =
• infos/provides = check
• infos/status = maintained nodep libc
• infos/metadata = check/path check/path/mode check/path/user
• infos/description = Checks if keys enriched with appropriate metadata contain valid paths as values as well as correct permissions

Introduction

This plugin checks whether the value of a key is a valid file system path and optionally if correct permissions are set for a certain user.

Installation

See installation. The package is called libelektra5-extra.

Purpose

The motivation to write this plugin is given by the two paths that exist in /etc/fstab: the device file and the mountpoint. A missing file is not necessarily an error, because the device file may appear later when a device is plugged in and the mountpoint may be there when another subsequent mount was executed. So only warnings are yielded in that case. One situation, however, presents an error: Only an absolute path is allowed to occur for both device and mountpoint. When checking for relative files, it is not enough to look at the first character if it is a /, because remote file systems and some special names are valid, too.

If check/path/mode = <permission> is also present it will check for the correct permissions of the file/directory. Optionally, you can also add check/path/user = <user>" which then checks the permissions for the given user. When calling kdb set on the actual key, you have to run as root user or the file permissions cannot be checked (you will receive an error message). It is also possible to leave the check/path/user empty (just provide an empty string) which then takes the executing user as target to check. So for example sudo kdb set ... will check if root can access the target file/directory whereas kdb set ... will take the current executing process/user. If check/path/user is not given at all, the plugin will check accessibility for the root user only (which again requires sudo)

check/path/mode = rw and check/path/user = tomcat for example will check if the user tomcat has read and write access to the path which was set for the key. Please note that the file has to exist already and it is not checked if the user has the right to create a file in the directory.

Permissions available:

• r: **R**ead
• w: **W**rite
• x: e**X**ecute

Usage

If the metakey check/path is present, it is checked if the value is a valid absolute file system path. If a metavalue is present, an additional check will be done if it is a directory or device file.

Examples

An example on which the user should have no permission at all for the root directory.

sudo kdb mount test.dump user:/tests path dump
sudo kdb set user:/tests/path "$HOME"
sudo kdb meta-set user:/tests/path check/path ""
sudo kdb meta-set user:/tests/path check/path/user ""
sudo kdb meta-set user:/tests/path check/path/mode "rw"
 
# Standard users should not be able to read/write the root folder
[ $(id -u) = 0 ] && printf >&2 'User is root\n' || kdb set user:/tests/path "/root"
# STDERR: User is root|.*C03200.*
 
# Set something which the current user can access for sure
kdb set user:/tests/path "$HOME"
# STDOUT-REGEX: .*Set string to "/.*".*
 
#cleanup
sudo kdb rm -r user:/tests
sudo kdb umount user:/tests

An example where part of the permissions are missing for a tmp file

sudo kdb mount test.dump user:/tests path dump
sudo kdb set user:/tests/path "$HOME"
sudo kdb meta-set user:/tests/path check/path ""
sudo kdb meta-set user:/tests/path check/path/user ""
sudo kdb meta-set user:/tests/path check/path/mode "rwx"
 
# Standard users should not be able to read/write the root folder
kdb set user:/tests/path/tempfile $(mktemp)
chmod +rw `kdb get user:/tests/path/tempfile`
kdb set user:/tests/path `kdb get user:/tests/path/tempfile`
# ERROR:C03200
 
# Set something which the current user can access for sure
chmod +x `kdb get user:/tests/path/tempfile`
kdb set user:/tests/path `kdb get user:/tests/path/tempfile`
# STDOUT-REGEX: Set string to "/.*".*
 
#cleanup
sudo rm -rf `kdb get user:/tests/path/tempfile`
sudo kdb rm -r user:/tests
sudo kdb umount user:/tests

Future work

Add a check which ensures that the given path is a file/directory/symbolic link/hard link/etc.