1UPDATE-CRYPTO-POLI(8) UPDATE-CRYPTO-POLI(8)
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6 update-crypto-policies - manage the policies available to the various
7 cryptographic back-ends.
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10 update-crypto-policies [COMMAND]
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13 update-crypto-policies(8) is used to set the policy applicable for the
14 various cryptographic back-ends, such as SSL/TLS libraries. The policy
15 aims to control the back-end default algorithm selections unless the
16 application user configures them otherwise.
17 The available policies are described in the crypto-policies(7) manual
19 page.
20 The desired system policy is selected in /etc/crypto-policies/config
22 and this tool will generate the individual policy requirements for all
23 back-ends that support such configuration. After this tool is called
24 and all the affected applications are restarted, the administrator is
25 assured that any application that utilizes the supported back-ends will
26 follow the specified policy.
27 Note that the above assurance does apply to the extent that
29 applications are configured to follow the default policy (the details
30 vary on the back-end, see below for more information).
31 The generated back-end policies will be placed in
33 /etc/crypto-policies/back-ends. Currently the supported back-ends (and
34 directive scopes they respect) are:
35 • GnuTLS library (GnuTLS, SSL, TLS)
37 • OpenSSL library (OpenSSL, SSL, TLS)
39 • NSS library (NSS, SSL, TLS)
41 • OpenJDK (java-tls, SSL, TLS)
43 • Libkrb5 (krb5, kerberos)
45 • BIND (BIND, DNSSec)
47 • OpenSSH (OpenSSH, SSH)
49 • Libreswan (libreswan, IKE, IPSec)
51 • libssh (libssh, SSH)
53 Applications and languages which rely on any of these back-ends will
55 follow the system policies as well. Examples are apache httpd, nginx,
56 php, and others.
57 In general after changing the system crypto policies with the
59 update-crypto-policies --set command it is recommended to restart the
60 system for the effect to fully take place as the policy configuration
61 files are loaded on application start-up. Otherwise applications
62 started before the command was run need to be restarted to load the
63 updated configuration.
64
66 The following commands are available in update-crypto-policies tool.
67 • --set: Sets the current policy and overwrites the config file.
69 • --show: Shows the currently applied crypto policy.
71 • --is-applied: Returns success if the currently configured policy in
73 the config file was applied by running the update-crypto-policies.
74 • --check: Returns success if freshly generated configuration files
76 match the current policy. The check will return failure if there is
77 a manual modification of the back-end configuration files or a
78 newer version of crypto-policies package is installed without
79 running update-crypto-policies. This should not happen with system
80 updates because update-crypto-policies is run implicitly there.
81
83 The following options are available in update-crypto-policies tool.
84 • --no-reload: By default this tool causes some running applications
86 to reload the configured policy. This option skips the reloading.
87
89 Applications in the operating system that provide a default
90 configuration file that includes a cryptographic policy string will be
91 modified gradually to support these policies.
92 When an application provides a configuration file, the changes needed
94 to utilize the system-wide policy are the following.
95 • Applications using OpenSSL: If an application allows the
97 configuration of ciphersuite string, the special cipher string
98 "PROFILE=SYSTEM" should replace any other cipher string.
99 Applications which use the default library settings automatically
100 adhere to the policy. Applications following the policy inherit the
101 settings for cipher suite preference. By default the OpenSSL
102 library reads a configuration file when it is initialized. If the
103 application does not override loading of the configuration file,
104 the policy also sets the minimum TLS protocol version and default
105 cipher suite preference via this file. If the application is
106 long-running such as the httpd server it has to be restarted to
107 reload the configuration file after policy is changed. Otherwise
108 the changed policy cannot take effect.
109 • Applications using GnuTLS: Applications using GnuTLS will load the
111 crypto policies by default. To prevent applications from adhering
112 to the policy the GNUTLS_SYSTEM_PRIORITY_FILE environment variable
113 must be set on an empty file (e.g., /dev/null). The policy covers
114 the settings for cipher suite preference, TLS and DTLS protocol
115 versions, allowed elliptic curves, and limits for cryptographic
116 keys.
117 • Applications using NSS: Applications using NSS will load the crypto
119 policies by default. They inherit the settings for cipher suite
120 preference, TLS and DTLS protocol versions, allowed elliptic
121 curves, and limits for cryptographic keys. To prevent applications
122 from adhering to the policy the NSS_IGNORE_SYSTEM_POLICY
123 environment variable must be set to 1 prior to executing that
124 application.
125 • Applications using Java: No special treatment is required.
127 Applications using Java will load the crypto policies by default.
128 These applications will then inherit the settings for allowed
129 cipher suites, allowed TLS and DTLS protocol versions, allowed
130 elliptic curves, and limits for cryptographic keys. To prevent
131 openjdk applications from adhering to the policy the
132 <java.home>/jre/lib/security/java.security file should be edited to
133 contain security.useSystemPropertiesFile=false or the system
134 property java.security.disableSystemPropertiesFile be set to true.
135 Note that the system property java.security.properties is loaded
136 with a lower preference than the crypto policies, so you can’t use
137 this property to override crypto policies without also preventing
138 openjdk applications from adhering to the policy.
139 • Applications using libkrb5: No special treatment is required.
141 Applications will follow the crypto policies by default. These
142 applications inherit the settings for the permitted encryption
143 types for tickets as well as the cryptographic key limits for the
144 PKINIT protocol. A system-wide opt-out is available by deleting the
145 /etc/krb5.conf.d/crypto-policies link.
146 • BIND: This application inherits the set of disabled algorithms. To
148 opt-out from the policy, remove the policy include directive in the
149 named.conf file.
150 • OpenSSH: Both server and client application inherits the cipher
152 preferences, the key exchange algorithms as well as the GSSAPI key
153 exchange algorithms. To opt-out from the policy for client,
154 override the global ssh_config with a user-specific configuration
155 in ~/.ssh/config. See ssh_config(5) for more information. To
156 override some configuration option in server, use a drop-in
157 directory /etc/ssh/sshd_config.d/ to create a file
158 lexicographically preceding 05-redhat.conf which is currently
159 including crypto policies configuration file.
160 • Libreswan: Both servers and clients inherit the ESP and IKE
162 preferences, if they are not overridden in the connection
163 configuration file. Note that due to limitations of libreswan,
164 crypto policies is restricted to supporting IKEv2. To opt-out from
165 the policy, comment the line including
166 /etc/crypto-policies/back-ends/libreswan.config from
167 /etc/ipsec.conf.
168 • Applications using libssh: Both client and server applications
170 using libssh will load the crypto policies by default. They inherit
171 the ciphers, key exchange, message authentication, and signature
172 algorithms preferences.
173
175 One of the supported policies should be set in
176 /etc/crypto-policies/config and this script should be run afterwards.
177 In case of a parsing error no policies will be updated.
179
181 The custom policies can take two forms. First form is a full custom
182 policy file which is supported by the update-crypto-policies tool in
183 the same way as the policies shipped along the tool in the package.
184 The second form can be called a subpolicy or policy modifier. This form
186 modifies aspects of any base policy file by removing or adding
187 algorithms or protocols. The subpolicies can be appended on the
188 update-crypto-policies --set command line to the base policy separated
189 by the : character. There can be multiple subpolicies appended. The
190 resulting configuration is the same as if the policy and subpolicies
191 were concatenated together.
192 Let’s suppose we have subpolicy NO-SHA1 that drops support for SHA1
194 hash and subpolicy GOST that enables support for the various algorithms
195 specified in Russian GOST standards. You can set the DEFAULT policy
196 with disabled SHA1 support and enabled GOST support by running the
197 following command:
198 update-crypto-policies --set DEFAULT:NO-SHA1:GOST
200 This command generates and applies configuration that will be
202 modification of the DEFAULT policy with changes specified in the
203 NO-SHA1 and GOST subpolicies.
204
206 /etc/crypto-policies/config
207 The file contains the system policy to be applied when
208 update-crypto-policies is run without any arguments. It should
209 contain a string of one of the policies listed in the
210 crypto-policies(7) page (e.g., DEFAULT) or any custom policy name
211 with subpolicies separated by the : character. The file is
212 overwritten when update-crypto-policies --set is executed.
213 /etc/crypto-policies/back-ends
215 Contains the generated policies in separated files, and in a format
216 readable by the supported back ends.
217 /etc/crypto-policies/local.d
219 Contains additional files to be appended to the generated policy
220 files. The files present must adhere to $app-XXX.config file
221 naming, where XXX is any arbitrary identifier. For example, to
222 append a line to GnuTLS' generated policy, create a
223 gnutls-extra-line.config file in local.d. This will be appended to
224 the generated gnutls.config during update-crypto-policies. Please
225 note that because the mechanism just appends a line to the back-end
226 configuration the effect varies among the back-ends. For some of
227 the back-ends the override fully replaces the original policy and
228 for other back-ends the override might not be effective at all.
229 /etc/crypto-policies/state/current
231 The file contains the current system policy name with eventual
232 subpolicies as of the last execution of the update-crypto-policies
233 command.
234 /etc/crypto-policies/state/CURRENT.pol
236 The file contains the current system policy definition with all the
237 modifications from eventual subpolicies applied and is written when
238 the update-crypto-policies command is executed.
239
241 crypto-policies(7), fips-mode-setup(8)
242
244 Written by Nikos Mavrogiannopoulos.
245update-crypto-policies 08/19/2021 UPDATE-CRYPTO-POLI(8)