UPDATE-CA-TRUST(8) UPDATE-CA-TRUST(8)
NAME
update-ca-trust - manage consolidated and dynamic configuration of CA certificates and associated trust
SYNOPSIS
update-ca-trust [COMMAND]
DESCRIPTION
update-ca-trust(8) is used to manage a consolidated and dynamic configuration feature of Certificate Authority
(CA) certificates and associated trust.
The feature is available for new applications that read the consolidated configuration files found in the
/etc/pki/ca-trust/extracted directory or that load the PKCS#11 module p11-kit-trust.so
Parts of the new feature are also provided in a way to make it useful for legacy applications.
Many legacy applications expect CA certificates and trust configuration in a fixed location, contained in
files with particular path and name, or by referring to a classic PKCS#11 trust module provided by the NSS
cryptographic library.
The dynamic configuration feature provides functionally compatible replacements for classic configuration
files and for the classic NSS trust module named libnssckbi.
In order to enable legacy applications, that read the classic files or access the classic module, to make use
of the new consolidated and dynamic configuration feature, the classic filenames have been changed to symbolic
links. The symbolic links refer to dynamically created and consolidated output stored below the
/etc/pki/ca-trust/extracted directory hierarchy.
The output is produced using the update-ca-trust command (without parameters), or using the update-ca-trust
extract command. In order to produce the output, a flexible set of source configuration is read, as described
in section SOURCE CONFIGURATION.
In addition, the classic PKCS#11 module is replaced with a new PKCS#11 module (p11-kit-trust.so) that
dynamically reads the same source configuration.
SOURCE CONFIGURATION
The dynamic configuration feature uses several source directories that will be scanned for any number of
source files. It is important to select the correct subdirectory for adding files, as the subdirectory defines
how contained certificates will be trusted or distrusted, and which file formats are read.
Files in subdirectories below the directory hierarchy /usr/share/pki/ca-trust-source/ contain CA certificates
and trust settings in the PEM file format. The trust settings found here will be interpreted with a low
priority.
Files in subdirectories below the directory hierarchy /etc/pki/ca-trust/source/ contain CA certificates and
trust settings in the PEM file format. The trust settings found here will be interpreted with a high priority.
You may use the following rules of thumb to decide, whether your configuration files should be added to the
/etc or rather to the /usr directory hierarchy:
· If you are manually adding a configuration file to a system, you probably want it to override any other
default configuration, and you most likely should add it to the respective subdirectory in the /etc
hierarchy.
· If you are creating a package that provides additional root CA certificates, that is intended for
distribution to several computer systems, but you still want to allow the administrator to override your
list, then your package should add your files to the respective subdirectory in the /usr hierarchy.
QUICK HELP 2: If your certificate is in the extended BEGIN TRUSTED file format (which may contain
distrust/blacklist trust flags, or trust flags for usages other than TLS) then:
· add it as a new file to directory /etc/pki/ca-trust/source/
· run update-ca-trust extract
In order to offer simplicity and flexibility, the way certificate files are treated depends on the
subdirectory they are installed to.
· simple trust anchors subdirectory: /usr/share/pki/ca-trust-source/anchors/ or
/etc/pki/ca-trust/source/anchors/
· simple blacklist (distrust) subdirectory: /usr/share/pki/ca-trust-source/blacklist/ or
/etc/pki/ca-trust/source/blacklist/
· extended format directory: /usr/share/pki/ca-trust-source/ or /etc/pki/ca-trust/source/
In the main directories /usr/share/pki/ca-trust-source/ or /etc/pki/ca-trust/source/ you may install one or
multiple files in the following file formats:
· certificate files that include trust flags, in the BEGIN/END TRUSTED CERTIFICATE file format (any file
name), which have been created using the openssl x509 tool and the -addreject -addtrust options. Bundle
files with multiple certificates are supported.
· files in the p11-kit file format using the .p11-kit file name extension, which can (e.g.) be used to
distrust certificates based on serial number and issuer name, without having the full certificate
available. (This is currently an undocumented format, to be extended later. For examples of the supported
formats, see the files shipped with the ca-certificates package.)
· certificate files without trust flags in either the DER file format or in the PEM (BEGIN/END CERTIFICATE)
file format (any file name). Such files will be added with neutral trust, neither trusted nor distrusted.
They will simply be known to the system, which might be helpful to assist cryptographic software in
constructing chains of certificates. (If you want a CA certificate in these file formats to be trusted,
you should remove it from this directory and move it to the ./anchors subdirectory instead.)
In the anchors subdirectories /usr/share/pki/ca-trust-source/anchors/ or /etc/pki/ca-trust/source/anchors/ you
may install one or multiple certificates in either the DER file format or in the PEM (BEGIN/END CERTIFICATE)
file format. Each certificate will be treated as trusted for all purposes.
In the blacklist subdirectories /usr/share/pki/ca-trust-source/blacklist/ or
/etc/pki/ca-trust/source/blacklist/ you may install one or multiple certificates in either the DER file format
or in the PEM (BEGIN/END CERTIFICATE) file format. Each certificate will be treated as distrusted for all
purposes.
Please refer to the x509(1) manual page for the documentation of the BEGIN/END CERTIFICATE and BEGIN/END
TRUSTED CERTIFICATE file formats.
Applications that rely on a static file for a list of trusted CAs may load one of the files found in the
/etc/pki/ca-trust/extracted directory. After modifying any file in the /usr/share/pki/ca-trust-source/ or
/etc/pki/ca-trust/source/ directories or in any of their subdirectories, or after adding a file, it is
necessary to run the update-ca-trust extract command, in order to update the consolidated files in
/etc/pki/ca-trust/extracted/ .
Please never manually edit the files stored in this directory, because your changes will be lost and the files
automatically overwritten, each time the update-ca-trust extract command gets executed.
In order to install new trusted or distrusted certificates, please rather install them in the respective
subdirectory below the /usr/share/pki/ca-trust-source/ or /etc/pki/ca-trust/source/ directories, as described
in the SOURCE CONFIGURATION section.
The directory /etc/pki/ca-trust/extracted/java/ contains a CA certificate bundle in the java keystore file
format. Distrust information cannot be represented in this file format, and distrusted certificates are
missing from these files. File cacerts contains CA certificates trusted for TLS server authentication.
The directory /etc/pki/ca-trust/extracted/openssl/ contains CA certificate bundle files in the extended
BEGIN/END TRUSTED CERTIFICATE file format, as described in the x509(1) manual page. File ca-bundle.trust.crt
contains the full set of all trusted or distrusted certificates, including the associated trust flags.
The directory /etc/pki/ca-trust/extracted/pem/ contains CA certificate bundle files in the simple BEGIN/END
CERTIFICATE file format, as described in the x509(1) manual page. Distrust information cannot be represented
in this file format, and distrusted certificates are missing from these files. File tls-ca-bundle.pem contains
CA certificates trusted for TLS server authentication. File email-ca-bundle.pem contains CA certificates
trusted for E-Mail protection. File objsign-ca-bundle.pem contains CA certificates trusted for code signing.
COMMANDS
(absent/empty command)
Same as the extract command described below. (However, the command may print fewer warnings, as this
command is being run during rpm package installation, where non-fatal status output is undesired.)
extract
Instruct update-ca-trust to scan the SOURCE CONFIGURATION and produce updated versions of the consolidated
configuration files stored below the /etc/pki/ca-trust/extracted directory hierarchy.
FILES
/etc/pki/tls/certs/ca-bundle.crt
Classic filename, file contains a list of CA certificates trusted for TLS server authentication usage, in
the simple BEGIN/END CERTIFICATE file format, without distrust information. This file is a symbolic link
that refers to the consolidated output created by the update-ca-trust command.
/etc/pki/tls/certs/ca-bundle.trust.crt
Classic filename, file contains a list of CA certificates in the extended BEGIN/END TRUSTED CERTIFICATE
file format, which includes trust (and/or distrust) flags specific to certificate usage. This file is a
symbolic link that refers to the consolidated output created by the update-ca-trust command.
/etc/pki/java/cacerts
Classic filename, file contains a list of CA certificates trusted for TLS server authentication usage, in
the Java keystore file format, without distrust information. This file is a symbolic link that refers to
the consolidated output created by the update-ca-trust command.
/usr/share/pki/ca-trust-source
Contains multiple, low priority source configuration files as explained in section SOURCE CONFIGURATION.
Please pay attention to the specific meanings of the respective subdirectories.
/etc/pki/ca-trust/source
Contains multiple, high priority source configuration files as explained in section SOURCE CONFIGURATION.
Please pay attention to the specific meanings of the respective subdirectories.
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