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update-crypto-policies(8)
=========================
:doctype: manpage
:man source: update-crypto-policies


NAME
----
update-crypto-policies - manage the policies available to the various
cryptographic back-ends.


SYNOPSIS
--------
*update-crypto-policies* ['COMMAND']


DESCRIPTION
-----------
*update-crypto-policies(8)* is used to set the policy applicable for the
various cryptographic back-ends, such as SSL/TLS libraries.
The policy aims to control the back-end default algorithm selections
unless the application user configures them otherwise.

The available policies are described in the *crypto-policies(7)* manual
page.

The desired system policy is selected in /etc/crypto-policies/config
and this tool will generate the individual policy requirements for
all back-ends that support such configuration. After this tool is called
and all the affected applications are restarted,
the administrator is assured that any application that utilizes the
supported back-ends will follow the specified policy.

Note that the above assurance does apply to the extent that applications
are configured to follow the default policy
(the details vary on the back-end, see below for more information).

The generated back-end policies will be placed in /etc/crypto-policies/back-ends.
Currently the supported back-ends (and directive scopes they respect) are:

* GnuTLS library (GnuTLS, SSL, TLS)

* OpenSSL library (OpenSSL, SSL, TLS)

* NSS library (NSS, SSL, TLS)

* OpenJDK (java-tls, SSL, TLS)

* Libkrb5 (krb5, kerberos)

* BIND (BIND, DNSSec)

* OpenSSH (OpenSSH, SSH)

* Libreswan (libreswan, IKE, IPSec)

* libssh (libssh, SSH)

Applications and languages which rely on any of these back-ends will follow
the system policies as well. Examples are apache httpd, nginx, php, and
others.

In general after changing the system crypto policies with the
`update-crypto-policies --set` command it is recommended to restart the
system for the effect to fully take place as the policy configuration
files are loaded on application start-up. Otherwise applications started
before the command was run need to be restarted to load the updated
configuration.

[[options]]
COMMANDS
-------

The following commands are available in update-crypto-policies tool.

* --set:        Sets the current policy and overwrites the config file.

* --show:       Shows the currently applied crypto policy.

* --is-applied: Returns success if the currently configured policy in
                the config file was applied by running the
                update-crypto-policies.

* --check:      Returns success if freshly generated configuration files match
                the current policy. The check will return failure if there
                is a manual modification of the back-end configuration files
                or a newer version of crypto-policies package is installed without
                running update-crypto-policies. This should not happen with
                system updates because update-crypto-policies is run implicitly
                there.


OPTIONS
-------

The following options are available in update-crypto-policies tool.

* --no-reload:  By default this tool causes some running applications to reload the
                configured policy. This option skips the reloading.


[[appsupport]]
APPLICATION SUPPORT
-------------------
Applications in the operating system that provide a default configuration file
that includes a cryptographic policy string will be modified gradually to
support these policies.

When an application provides a configuration file, the changes needed to
utilize the system-wide policy are the following.

* Applications using OpenSSL: If an application allows the configuration of
  ciphersuite string, the special cipher string "PROFILE=SYSTEM" should replace any other cipher string.
  Applications which use the default library settings automatically adhere to the policy.
  Applications following the policy inherit the settings for cipher suite preference.
  By default the OpenSSL library reads a configuration file when it is initialized. If
  the application does not override loading of the configuration file, the policy also
  sets the minimum TLS protocol version and default cipher suite preference via this
  file. If the application is long-running such as the httpd server it has to be restarted
  to reload the configuration file after policy is changed. Otherwise the changed policy
  cannot take effect.

* Applications using GnuTLS: Applications using GnuTLS will load the crypto policies
  by default. To prevent applications from adhering to the policy the GNUTLS_SYSTEM_PRIORITY_FILE
  environment variable must be set on an empty file (e.g., /dev/null).
  The policy covers the settings for cipher suite preference, TLS and DTLS
  protocol versions, allowed elliptic curves, and limits for cryptographic keys.

* Applications using NSS: Applications using NSS will load the crypto policies by
  default. They inherit the settings for cipher suite preference, TLS
  and DTLS protocol versions, allowed elliptic curves, and limits for
  cryptographic keys. To prevent applications from adhering
  to the policy the NSS_IGNORE_SYSTEM_POLICY environment variable must be set to 1
  prior to executing that application.

* Applications using Java: No special treatment is required. Applications using
  Java will load the crypto policies by default.
  These applications will then inherit the settings for allowed cipher suites,
  allowed TLS and DTLS protocol versions, allowed elliptic curves, and limits for
  cryptographic keys. To prevent openjdk applications from adhering
  to the policy the `<java.home>/jre/lib/security/java.security` file should
  be edited to contain `security.useSystemPropertiesFile=false` or the system
  property `java.security.disableSystemPropertiesFile` be set to `true`.
  Note that the system property `java.security.properties` is loaded with
  a lower preference than the crypto policies, so you can't use this property
  to override crypto policies without also preventing openjdk applications
  from adhering to the policy.

* Applications using libkrb5: No special treatment is required. Applications
  will follow the crypto policies by default. These applications inherit the
  settings for the permitted encryption types for tickets as well as the
  cryptographic key limits for the PKINIT protocol. A system-wide opt-out is
  available by deleting the /etc/krb5.conf.d/crypto-policies link.

 * BIND: This application inherits the set of disabled algorithms. To
   opt-out from the policy, remove the policy include directive in the
   named.conf file.

 * OpenSSH: Both server and client application inherits the cipher preferences,
   the key exchange algorithms as well as the GSSAPI key exchange algorithms.
   To opt-out from the policy for client, override the global ssh_config with a
   user-specific configuration in ~/.ssh/config. See ssh_config(5) for more
   information.
   To override some configuration option in server, use a drop-in directory
   /etc/ssh/sshd_config.d/ to create a file lexicographically preceding
   05-redhat.conf which is currently including crypto policies configuration
   file.

 * Libreswan: Both servers and clients inherit the ESP and IKE preferences,
   if they are not overridden in the connection configuration file. Note that
   due to limitations of libreswan, crypto policies is restricted to supporting IKEv2.
   To opt-out from the policy, comment the line including `/etc/crypto-policies/back-ends/libreswan.config`
   from `/etc/ipsec.conf`.

 * Applications using libssh: Both client and server applications using libssh
   will load the crypto policies by default. They inherit the ciphers, key
   exchange, message authentication, and signature algorithms preferences.

[[policyconfig]]
POLICY CONFIGURATION
--------------------
One of the supported policies should be set in /etc/crypto-policies/config
and this script should be run afterwards.

In case of a parsing error no policies will be updated.

CUSTOM POLICIES
---------------
The custom policies can take two forms. First form is a full custom policy file
which is supported by the update-crypto-policies tool in the same way as the
policies shipped along the tool in the package.

The second form can be called a subpolicy or policy modifier. This form modifies
aspects of any base policy file by removing or adding algorithms or protocols.
The subpolicies can be appended on the update-crypto-policies --set command
line to the base policy separated by the `:` character. There can be multiple
subpolicies appended.
The resulting configuration is the same as if the policy and subpolicies
were concatenated together.

Let's suppose we have subpolicy NO-SHA1 that drops support for SHA1 hash
and subpolicy GOST that enables support for the various algorithms specified
in Russian GOST standards. You can set the DEFAULT policy with disabled SHA1
support and enabled GOST support by running the following command:

`update-crypto-policies --set DEFAULT:NO-SHA1:GOST`

This command generates and applies configuration that will be modification of
the DEFAULT policy with changes specified in the NO-SHA1 and GOST subpolicies.

FILES
-----
/etc/crypto-policies/config::
	The file contains the system policy to be applied when
	`update-crypto-policies` is run without any arguments. It should
	contain a string of one of the policies listed in the
	*crypto-policies(7)* page (e.g., DEFAULT) or any custom policy
	name with subpolicies separated by the `:` character. The
	file is overwritten when `update-crypto-policies --set` is executed.

/etc/crypto-policies/back-ends::
	Contains the generated policies in separated files, and in a format readable
	by the supported back ends.

/etc/crypto-policies/local.d::
	Contains additional files to be appended to the generated policy
	files. The files present must adhere to $app-XXX.config file naming, where
	XXX is any arbitrary identifier. For example, to append a line to
	GnuTLS' generated policy, create a gnutls-extra-line.config file in
	local.d. This will be appended to the generated gnutls.config during
	update-crypto-policies. Please note that because the mechanism just appends
	a line to the back-end configuration the effect varies among the back-ends.
	For some of the back-ends the override fully replaces the original policy
	and for other back-ends the override might not be effective at all.

/etc/crypto-policies/state/current::
	The file contains the current system policy name with eventual subpolicies
	as of the last execution of the `update-crypto-policies` command.

/etc/crypto-policies/state/CURRENT.pol::
	The file contains the current system policy definition with all the
	modifications from eventual subpolicies applied and is written
	when the `update-crypto-policies` command is executed.

SEE ALSO
--------
crypto-policies(7), fips-mode-setup(8)

AUTHOR
------
Written by Nikos Mavrogiannopoulos.
