Adding upstream version 5.6.0.upstream/5.6.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 65 insertions, 0 deletions

diff --git a/doc/config-no-systemd-privileges.rst b/doc/config-no-systemd-privileges.rst
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+.. SPDX-License-Identifier: GPL-3.0-or-later
+
+Privileges and capabilities
+===========================
+
+The kresd daemon requires privileges when it is configured to bind to
+well-known ports. There are multiple ways to achieve this.
+
+Using capabilities
+^^^^^^^^^^^^^^^^^^
+
+The most secure and recommended way is to use capabilities and execute kresd as
+an unprivileged user.
+
+* ``CAP_NET_BIND_SERVICE`` is required to bind to well-known ports.
+* ``CAP_SETPCAP`` when this capability is available, kresd drops any extra
+  capabilities after the daemon successfully starts when running as
+  a non-root user.
+
+Running as non-privileged user
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Another possibility is to start the process as privileged user and then switch
+to a non-privileged user after binding to network interfaces.
+
+.. function:: user(name, [group])
+
+   :param string name: user name
+   :param string group: group name (optional)
+   :return: boolean
+
+   Drop privileges and start running as given user (and group, if provided).
+
+   .. tip:: Note that you should bind to required network addresses before
+      changing user. At the same time, you should open the cache **AFTER** you
+      change the user (so it remains accessible). A good practice is to divide
+      configuration in two parts:
+
+      .. code-block:: lua
+
+         -- privileged
+         net.listen('127.0.0.1')
+         net.listen('::1')
+         user('knot-resolver', 'netgrp')
+         -- unprivileged
+         cache.size = 100*MB
+
+   Example output:
+
+   .. code-block:: lua
+
+      > user('baduser')
+      invalid user name
+      > user('knot-resolver', 'netgrp')
+      true
+      > user('root')
+      Operation not permitted
+
+Running as root
+^^^^^^^^^^^^^^^
+
+.. warning:: Executing processes as root is generally insecure, as these
+   processes have unconstrained access to the complete system at runtime.
+
+While not recommended, it is also possible to run kresd directly as root.