Polkit (Русский)
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From polkit homepage:
- polkit это набор инструментальных средств уровня приложения для определения и обработки политики, которая позволяет непривилегированным процессам разговаривать с привилегированными процессами: это платформа для централизации процесса принятия решений в отношении предоставления доступа к привилегированным операциям для непривилегированных приложений.
Polkit используется для управления общесистемными привилегиями. Он обеспечивает организованный способ для непривилегированных процессов для связи с привилегированными. В отличие от систем, таких как sudo, он не предоставляет права root для всего процесса, а скорее позволяет более тонкий уровень управления централизованной политикой системы.
Polkit работает, ограничивая отдельные действия, например. Запуск GParted и разграничение пользователей по группам или по имени, например. Члены колесной группы. Затем он определяет, как, если это вообще возможно, эти пользователи разрешают эти действия, например. Путем идентификации в качестве членов группы, набрав их пароли.
Contents
Установка
Установите polkit пакет.
Агенты идентификации
Агент аутентификации используется для того, чтобы заставить пользователя сеанса доказать, что пользователь сеанса действительно является пользователем (путем аутентификации как пользователь) или административным пользователем (путем аутентификации в качестве администратора). Пакет polkit содержит текстовый агент проверки подлинности, называемый 'pkttyagent', который используется в качестве запасного варианта.
Если вы пользуетесь графической оболочкой убедитесь, что установлен графический агент аутентификации и что он автоматически запускается при входе в систему. If you are using a graphical environment, make sure that a graphical authentication agent is installed and autostarted on login.
Cinnamon, Deepin, GNOME, GNOME Flashback, KDE, LXDE, LXQt, MATE, theShell and Xfce have an authentication agent already. In other desktop environments, you have to choose one of the following implementations:
- lxqt-policykit, which provides
/usr/bin/lxqt-policykit-agent
- lxsession, which provides
/usr/bin/lxpolkit
- mate-polkit, which provides
/usr/lib/mate-polkit/polkit-mate-authentication-agent-1
- polkit-efl-gitAUR, which provides
/usr/bin/polkit-efl-authentication-agent-1
- polkit-gnome, which provides
/usr/lib/polkit-gnome/polkit-gnome-authentication-agent-1
- polkit-kde-agent, which provides
/usr/lib/polkit-kde/polkit-kde-authentication-agent-1
- ts-polkitagentAUR, which provides
/usr/lib/ts-polkitagent
- xfce-polkit-gitAUR, which provides
/usr/lib/xfce-polkit/xfce-polkit
Конфигурация
Polkit definitions can be divided into two kinds:
- Actions are defined in XML
.policy
files located in/usr/share/polkit-1/actions
. Each action has a set of default permissions attached to it (e.g. you need to identify as an administrator to use the GParted action). The defaults can be overruled but editing the actions files is NOT the correct way. -
Authorization rules are defined in JavaScript
.rules
files. They are found in two places: 3rd party packages can use/usr/share/polkit-1/rules.d
(though few if any do) and/etc/polkit-1/rules.d
is for local configuration.
Polkit operates on top of the existing permissions systems in Linux – group membership, administrator status – it does not replace them. The .rules files designate a subset of users, refer to one (or more) of the actions specified in the actions files and determine with what restrictions these actions can be taken by that/those user(s). As an example, a rules file could overrule the default requirement for all users to authenticate as an admin when using GParted, determining that some specific user doesn't need to. Or isn't allowed to use GParted at all.
Actions
The actions available to you via polkit will depend on the packages you have installed. Some are used in multiple desktop environments (org.freedesktop.*), some are DE-specific (org.gnome.*) and some are specific to a single program (org.archlinux.pkexec.gparted.policy). The command pkaction
lists all the actions defined in /usr/share/polkit-1/actions
for quick reference.
To get an idea of what polkit can do, here are a few commonly used groups of actions:
- systemd-logind (org.freedesktop.login1.policy) actions regulated by polkit include powering off, rebooting, suspending and hibernating the system, including when other users may still be logged in.
- udisks (org.freedesktop.udisks2.policy) actions regulated by polkit include mounting file systems and unlocking encrypted devices.
- NetworkManager (org.freedesktop.NetworkManager.policy) actions regulated by polkit include turning on and off the network, wifi or mobile broadband.
Each action is defined in an <action>
tag in a .policy file. The org.archlinux.pkexec.gparted.policy
contains a single action and looks like this:
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE policyconfig PUBLIC "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN" "http://www.freedesktop.org/software/polkit/policyconfig-1.dtd"> <policyconfig> <action id="org.archlinux.pkexec.gparted"> <message>Authentication is required to run the GParted Partition Editor</message> <icon_name>gparted</icon_name> <defaults> <allow_any>auth_admin</allow_any> <allow_inactive>auth_admin</allow_inactive> <allow_active>auth_admin</allow_active> </defaults> <annotate key="org.freedesktop.policykit.exec.path">/usr/bin/gparted</annotate> <annotate key="org.freedesktop.policykit.exec.allow_gui">true</annotate> </action> </policyconfig>
The attribute id is the actual command sent to D-Bus, the message tag is the explanation to the user when authentication is required and the icon_name is sort of obvious.
The defaults tag is where the permissions or lack thereof are located. It contains three settings: allow_any, allow_inactive, and allow_active. Inactive sessions are generally remote sessions (SSH, VNC, etc.) whereas active sessions are logged directly into the machine on a TTY or an X display. allow_any is the setting encompassing both scenarios.
For each of these settings the following options are available:
- no: The user is not authorized to carry out the action. There is therefore no need for authentication.
- yes: The user is authorized to carry out the action without any authentication.
- auth_self: Authentication is required but the user need not be an administrative user.
- auth_admin: Authentication as an administrative user is required.
- auth_self_keep: The same as auth_self but, like sudo, the authorization lasts a few minutes.
- auth_admin_keep: The same as auth_admin but, like sudo, the authorization lasts a few minutes.
These are default setting and unless overruled in later configuration will be valid for all users.
As can be seen from the GParted action, users are required to authenticate as administrators in order to use GParted, regardless of whether the session is active or inactive.
Правила авторизации
Authorization rules that overrule the default settings are laid out in a set of directories as described above. For all purposes relating to personal configuration of a single system, only /etc/polkit-1/rules.d
should be used.
The addRule()
method is used for adding a function that may be called whenever an authorization check for action and subject is performed. Functions are called in the order they have been added until one of the functions returns a value. Hence, to add an authorization rule that is processed before other rules, put it in a file in /etc/polkit-1/rules.d
with a name that sorts before other rules files, for example 00-early-checks.rules
.
The layout of the .rules files is fairly self-explanatory:
/* Allow users in admin group to run GParted without authentication */ polkit.addRule(function(action, subject) { if (action.id == "org.archlinux.pkexec.gparted" && subject.isInGroup("admin")) { return polkit.Result.YES; } });
Inside the function, we check for the specified action ID (org.archlinux.pkexec.gparted) and for the user's group (admin), then return a value "yes".
Administrator identities
The addAdminRule()
method is used for adding a function that may be called whenever administrator authentication is required. The function is used to specify what identities may be used for administrator authentication for the authorization check identified by action and subject. Functions added are called in the order they have been added until one of the functions returns a value.
The default configuration for administrator identities is contained in the file 50-default.rules
so any changes to that configuration should be made by copying the file to, say, 40-default.rules
and editing that file.
/etc/polkit-1/rules.d/50-default.rules
polkit.addAdminRule(function(action, subject) { return ["unix-group:wheel"]; });
The only part to edit (once copied) is the return array of the function: as whom should a user authenticate when asked to authenticate as an administrative user? If she herself is a member of the group designated as admins, she only need enter her own password. If some other user, e.g. root, is the only admin identity, she would need to enter in root's password. The format of the user identification is the same as the one used in designating authorities.
The Arch default is to make all members of the group wheel administrators. A rule like below will have polkit ask for the root password instead of the users password for Admin authentication.
/etc/polkit-1/rules.d/49-rootpw_global.rules
/* Always authenticate Admins by prompting for the root * password, similar to the rootpw option in sudo */ polkit.addAdminRule(function(action, subject) { return ["unix-user:root"]; });
Примеры
Debugging/logging
The following rule logs detailed information about any requested access.
/etc/polkit-1/rules.d/00-log-access.rules
polkit.addRule(function(action, subject) { polkit.log("action=" + action); polkit.log("subject=" + subject); });
Disable suspend and hibernate
The following rule disables suspend and hibernate for all users.
/etc/polkit-1/rules.d/10-disable-suspend.rules
polkit.addRule(function(action, subject) { if (action.id == "org.freedesktop.login1.suspend" || action.id == "org.freedesktop.login1.suspend-multiple-sessions" || action.id == "org.freedesktop.login1.hibernate" || action.id == "org.freedesktop.login1.hibernate-multiple-sessions") { return polkit.Result.NO; } });
Bypass password prompt
To achieve something similar to the sudo NOPASSWD
option and get authorized solely based on user/group identity, you can create custom rules in /etc/polkit-1/rules.d/
. This allows you to override password authentication either only for specific actions or globally. See [1] for an example rule set.
Globally
Create the following file as root:
/etc/polkit-1/rules.d/49-nopasswd_global.rules
/* Allow members of the wheel group to execute any actions * without password authentication, similar to "sudo NOPASSWD:" */ polkit.addRule(function(action, subject) { if (subject.isInGroup("wheel")) { return polkit.Result.YES; } });
Replace wheel
by any group of your preference.
This will result in automatic authentication for any action requiring admin rights via Polkit. As such, be careful with the group you choose to give such rights to.
For specific actions
Create the following file as root:
/etc/polkit-1/rules.d/49-nopasswd_limited.rules
/* Allow members of the wheel group to execute the defined actions * without password authentication, similar to "sudo NOPASSWD:" */ polkit.addRule(function(action, subject) { if ((action.id == "org.archlinux.pkexec.gparted" || action.id == "org.libvirt.unix.manage") && subject.isInGroup("wheel")) { return polkit.Result.YES; } });
The action.id
s selected here are just (working) examples for GParted and Libvirt, but you can replace them by any other of your liking as long as they exist (custom made or supplied by a package), and so can you define any group instead of wheel
.
The ||
operator is used to delimit actions (logical OR), and &&
means logical AND and must be kept as the last operator.
Udisks
File managers may ask for a password when trying to mount a storage device, or yield a Not authorized or similar error. See Udisks#Configuration for details.
Allow management of individual systemd units by regular users
By checking for certain values passed to the polkit policy check, you can give specific users or groups the ability to manage specific units. As an example, you might want regular users to start and stop wpa_supplicant:
/etc/polkit-1/rules.d/10-wifimanagement.rules
polkit.addRule(function(action, subject) { if (action.id == "org.freedesktop.systemd1.manage-units") { if (action.lookup("unit") == "wpa_supplicant.service") { var verb = action.lookup("verb"); if (verb == "start" || verb == "stop" || verb == "restart") { return polkit.Result.YES; } } } });