- NAME
- DESCRIPTION
- PRAGMAS
- OPENSSL LIBRARY CONFIGURATION

- ASN1 Object Configuration Module
- Engine Configuration Module
- Provider Configuration Module
- EVP Configuration Module
- SSL Configuration Module

- NOTES
- EXAMPLES
- ENVIRONMENT
- BUGS
- HISTORY
- SEE ALSO
- COPYRIGHT

# NAME

config - OpenSSL CONF library configuration files

# DESCRIPTION

The OpenSSL CONF library can be used to read configuration files. It is used for the OpenSSL master configuration file openssl.cnf and in a few other places like SPKAC files and certificate extension files for the x509 utility. OpenSSL applications can also use the CONF library for their own purposes.

A configuration file is divided into a number of sections. Each section starts with a line `[section_name]` and ends when a new section is started or end of file is reached. A section name can consist of alphanumeric characters and underscores. The brackets are required.

The first section of a configuration file is special and is referred to as the default section. This section is usually unnamed and spans from the start of file until the first named section. When a name is being looked up it is first looked up in a named section (if any) and then the default section.

The environment is mapped onto a section called ENV.

Comments can be included by preceding them with the # character

Other files can be included using the .include directive followed by a path. If the path points to a directory all files with names ending with .cnf or .conf are included from the directory. Recursive inclusion of directories from files in such directory is not supported. That means the files in the included directory can also contain .include directives but only inclusion of regular files is supported there. The inclusion of directories is not supported on systems without POSIX IO support.

It is strongly recommended to use absolute paths with the .include directive. Relative paths are evaluated based on the application current working directory so unless the configuration file containing the .include directive is application specific the inclusion will not work as expected. The environment variable OPENSSL_CONF_INCLUDE can also be used to specify the path to prepend to all .include paths.

There can be optional = character and whitespace characters between .include directive and the path which can be useful in cases the configuration file needs to be loaded by old OpenSSL versions which do not support the .include syntax. They would bail out with error if the = character is not present but with it they just ignore the include.

Pragmas can be specified with the .pragma directive. See PRAGMAS for more information.

Each section in a configuration file consists of a number of name and value pairs of the form name=value

The name string can contain any alphanumeric characters as well as a few punctuation symbols such as . , ; and _.

The value string consists of the string following the = character until end of line with any leading and trailing white space removed.

The value string undergoes variable expansion. This can be done by including the form $var or ${var}: this will substitute the value of the named variable in the current section. It is also possible to substitute a value from another section using the syntax $section::name or ${section::name}. By using the form $ENV::name environment variables can be substituted. It is also possible to assign values to environment variables by using the name ENV::name, this will work if the program looks up environment variables using the CONF library instead of calling `getenv()` directly. The value string must not exceed 64k in length after variable expansion. Otherwise an error will occur.

It is possible to escape certain characters by using any kind of quote or the \ character. By making the last character of a line a \ a value string can be spread across multiple lines. In addition the sequences \n, \r, \b and \t are recognized.

All expansion and escape rules as described above that apply to value also apply to the path of the .include directive.

# PRAGMAS

Pragmas can be used to change the behavior of the configuration file parser, among others. Currently supported pragmas are:

.pragma dollarid:value

  value can be one of:

  "on" or "true"

    this signifies that dollar signs are considered an identity character from this point on and that variable expansion requires the use of braces or parentheses. In other words, `foo$bar` will be considered a name instead of `foo` followed by the expansion of the variable `bar`. This is suitable for platforms where the dollar sign is commonly used as part of names.

  "off" or "false"

    Turns this pragma off, i.e. `foo$bar` will be interpreted as `foo` followed by the expansion of the variable `bar`.

  By default, this pragma is turned off.

# OPENSSL LIBRARY CONFIGURATION

Applications can automatically configure certain aspects of OpenSSL using the master OpenSSL configuration file, or optionally an alternative configuration file. The openssl utility includes this functionality: any sub command uses the master OpenSSL configuration file unless an option is used in the sub command to use an alternative configuration file.

To enable library configuration the default section needs to contain an appropriate line which points to the main configuration section. The default name is openssl_conf which is used by the openssl utility. Other applications may use an alternative name such as myapplication_conf. All library configuration lines appear in the default section at the start of the configuration file.

The configuration section should consist of a set of name value pairs which contain specific module configuration information. The name represents the name of the configuration module. The meaning of the value is module specific: it may, for example, represent a further configuration section containing configuration module specific information. E.g.:

     # This must be in the default section
     openssl_conf = openssl_init

     [openssl_init]

     oid_section = new_oids
     engines = engine_section
     providers = provider_section

     [new_oids]

     ... new oids here ...

     [engine_section]

     ... engine stuff here ...

     [provider_section]

     ... provider stuff here ...

The features of each configuration module are described below.

## ASN1 Object Configuration Module

This module has the name oid_section. The value of this variable points to a section containing name value pairs of OIDs: the name is the OID short and long name, the value is the numerical form of the OID. Although some of the openssl utility sub commands already have their own ASN1 OBJECT section functionality not all do. By using the ASN1 OBJECT configuration module all the openssl utility sub commands can see the new objects as well as any compliant applications. For example:

     [new_oids]

     some_new_oid = 1.2.3.4
     some_other_oid = 1.2.3.5

It is also possible to set the value to the long name followed by a comma and the numerical OID form. For example:

     shortName = some object long name, 1.2.3.4

## Engine Configuration Module

This ENGINE configuration module has the name engines. The value of this variable points to a section containing further ENGINE configuration information.

The section pointed to by engines is a table of engine names (though see engine_id below) and further sections containing configuration information specific to each ENGINE.

Each ENGINE specific section is used to set default algorithms, load dynamic, perform initialization and send ctrls. The actual operation performed depends on the command name which is the name of the name value pair. The currently supported commands are listed below.

For example:

     [engine_section]

     # Configure ENGINE named "foo"
     foo = foo_section
     # Configure ENGINE named "bar"
     bar = bar_section

     [foo_section]
     ... foo ENGINE specific commands ...

     [bar_section]
     ... "bar" ENGINE specific commands ...

The command engine_id is used to give the ENGINE name. If used this command must be first. For example:

     [engine_section]
     # This would normally handle an ENGINE named "foo"
     foo = foo_section

     [foo_section]
     # Override default name and use "myfoo" instead.
     engine_id = myfoo

The command dynamic_path loads and adds an ENGINE from the given path. It is equivalent to sending the ctrls SO_PATH with the path argument followed by LIST_ADD with value 2 and LOAD to the dynamic ENGINE. If this is not the required behaviour then alternative ctrls can be sent directly to the dynamic ENGINE using ctrl commands.

The command init determines whether to initialize the ENGINE. If the value is 0 the ENGINE will not be initialized, if 1 and attempt it made to initialized the ENGINE immediately. If the init command is not present then an attempt will be made to initialize the ENGINE after all commands in its section have been processed.

The command default_algorithms sets the default algorithms an ENGINE will supply using the functions `ENGINE_set_default_string()`.

If the name matches none of the above command names it is assumed to be a ctrl command which is sent to the ENGINE. The value of the command is the argument to the ctrl command. If the value is the string EMPTY then no value is sent to the command.

For example:

     [engine_section]

     # Configure ENGINE named "foo"
     foo = foo_section

     [foo_section]
     # Load engine from DSO
     dynamic_path = /some/path/fooengine.so
     # A foo specific ctrl.
     some_ctrl = some_value
     # Another ctrl that doesn't take a value.
     other_ctrl = EMPTY
     # Supply all default algorithms
     default_algorithms = ALL

## Provider Configuration Module

This provider configuration module has the name providers. The value of this variable points to a section containing further provider configuration information.

The section pointed to by providers is a table of provider names (though see identity below) and further sections containing configuration information specific to each provider module.

Each provider specific section is used to load its module, perform activation and set parameters to pass to the provider on demand. The actual operation performed depends on the name of the name value pair. The currently supported commands are listed below.

For example:

     [provider_section]

     # Configure provider named "foo"
     foo = foo_section
     # Configure provider named "bar"
     bar = bar_section

     [foo_section]
     ... "foo" provider specific parameters ...

     [bar_section]
     ... "bar" provider specific parameters ...

The command identity is used to give the provider name. For example:

     [provider_section]
     # This would normally handle a provider named "foo"
     foo = foo_section

     [foo_section]
     # Override default name and use "myfoo" instead.
     identity = myfoo

The parameter module loads and adds a provider module from the given module path. That path may be a simple filename, a relative path or an absolute path.

The parameter activate determines whether to activate the provider. The value has no importance, the presence of the parameter is enough for activation to take place.

All parameters in the section as well as sub-sections are made available to the provider.

## EVP Configuration Module

This module has the name alg_section which points to a section containing algorithm commands.

The supported algorithm commands are:

default_properties

  The value may be anything that is acceptable as a property query string for `EVP_set_default_properties()`.

fips_mode (deprecated)

  The value is a boolean that can be yes or no. If the value is yes, this is exactly equivalent to:

          default_properties = fips=yes

  If the value is no, nothing happens.

These two commands should not be used together, as there is no control over how they affect each other. The use of fips_mode is strongly discouraged and is only present for backward compatibility with earlier OpenSSL FIPS modules.

## SSL Configuration Module

This module has the name ssl_conf which points to a section containing SSL configurations.

Each line in the SSL configuration section contains the name of the configuration and the section containing it.

Each configuration section consists of command value pairs for SSL_CONF. Each pair will be passed to a SSL_CTX or SSL structure if it calls `SSL_CTX_config()` or `SSL_config()` with the appropriate configuration name.

Note: any characters before an initial dot in the configuration section are ignored so the same command can be used multiple times.

For example:

     ssl_conf = ssl_sect

     [ssl_sect]

     server = server_section

     [server_section]

     RSA.Certificate = server-rsa.pem
     ECDSA.Certificate = server-ecdsa.pem
     Ciphers = ALL:!RC4

The system default configuration with name system_default if present will be applied during any creation of the SSL_CTX structure.

Example of a configuration with the system default:

     ssl_conf = ssl_sect

     [ssl_sect]

     system_default = system_default_sect

     [system_default_sect]

     MinProtocol = TLSv1.2

# NOTES

If a configuration file attempts to expand a variable that doesn't exist then an error is flagged and the file will not load. This can happen if an attempt is made to expand an environment variable that doesn't exist. For example in a previous version of OpenSSL the default OpenSSL master configuration file used the value of HOME which may not be defined on non Unix systems and would cause an error.

This can be worked around by including a default section to provide a default value: then if the environment lookup fails the default value will be used instead. For this to work properly the default value must be defined earlier in the configuration file than the expansion. See the EXAMPLES section for an example of how to do this.

If the same variable exists in the same section then all but the last value will be silently ignored. In certain circumstances such as with DNs the same field may occur multiple times. This is usually worked around by ignoring any characters before an initial . e.g.

     1.OU="My first OU"
     2.OU="My Second OU"

# EXAMPLES

Here is a sample configuration file using some of the features mentioned above.

     # This is the default section.

     HOME=/temp
     configdir=$ENV::HOME/config

     [ section_one ]

     # We are now in section one.

     # Quotes permit leading and trailing whitespace
     any = " any variable name "

     other = A string that can \
     cover several lines \
     by including \\ characters

     message = Hello World\n

     [ section_two ]

     greeting = $section_one::message

This next example shows how to expand environment variables safely.

Suppose you want a variable called tmpfile to refer to a temporary filename. The directory it is placed in can determined by the TEMP or TMP environment variables but they may not be set to any value at all. If you just include the environment variable names and the variable doesn't exist then this will cause an error when an attempt is made to load the configuration file. By making use of the default section both values can be looked up with TEMP taking priority and /tmp used if neither is defined:

     TMP=/tmp
     # The above value is used if TMP isn't in the environment
     TEMP=$ENV::TMP
     # The above value is used if TEMP isn't in the environment
     tmpfile=${ENV::TEMP}/tmp.filename

Simple OpenSSL library configuration example to enter FIPS mode:

     # Default appname: should match "appname" parameter (if any)
     # supplied to CONF_modules_load_file et al.
     openssl_conf = openssl_conf_section

     [openssl_conf_section]
     # Configuration module list
     alg_section = evp_sect

     [evp_sect]
     # Set to "yes" to enter FIPS mode if supported
     fips_mode = yes

Note: in the above example you will get an error in non FIPS capable versions of OpenSSL.

Simple OpenSSL library configuration to make TLS 1.3 the system-default minimum TLS version:

     # Toplevel section for openssl (including libssl)
     openssl_conf = default_conf_section

     [default_conf_section]
     # We only specify configuration for the "ssl module"
     ssl_conf = ssl_section

     [ssl_section]
     system_default = system_default_section

     [system_default_section]
     MinProtocol = TLSv1.3

More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:

     # Default appname: should match "appname" parameter (if any)
     # supplied to CONF_modules_load_file et al.
     openssl_conf = openssl_conf_section

     [openssl_conf_section]
     # Configuration module list
     alg_section = evp_sect
     oid_section = new_oids

     [evp_sect]
     # This will have no effect as FIPS mode is off by default.
     # Set to "yes" to enter FIPS mode, if supported
     fips_mode = no

     [new_oids]
     # New OID, just short name
     newoid1 = 1.2.3.4.1
     # New OID shortname and long name
     newoid2 = New OID 2 long name, 1.2.3.4.2

The above examples can be used with any application supporting library configuration if "openssl_conf" is modified to match the appropriate "appname".

For example if the second sample file above is saved to "example.cnf" then the command line:

     OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1

will output:

        0:d=0  hl=2 l=   4 prim: OBJECT            :newoid1

showing that the OID "newoid1" has been added as "1.2.3.4.1".

# ENVIRONMENT

OPENSSL_CONF

  The path to the config file. Ignored in set-user-ID and set-group-ID programs.

OPENSSL_ENGINES

  The path to the engines directory. Ignored in set-user-ID and set-group-ID programs.

OPENSSL_MODULES

  The path to the directory with OpenSSL modules, such as providers. Ignored in set-user-ID and set-group-ID programs.

OPENSSL_CONF_INCLUDE

  The optional path to prepend to all .include paths.

# BUGS

Currently there is no way to include characters using the octal \nnn form. Strings are all null terminated so nulls cannot form part of the value.

The escaping isn't quite right: if you want to use sequences like \n you can't use any quote escaping on the same line.

Files are loaded in a single pass. This means that an variable expansion will only work if the variables referenced are defined earlier in the file.

# HISTORY

An undocumented API, NCONF_WIN32(), used a slightly different set of parsing rules there were intended to be tailored to the Microsoft Windows platform. Specifically, the backslash character was not an escape character and could be used in pathnames, only the double-quote character was recognized, and comments began with a semi-colon. This function was deprecated in OpenSSL 3.0; applications with configuration files using that syntax will have to be modified.

# SEE ALSO

openssl-x509(1), openssl-req(1), openssl-ca(1), fips_config(5)

# COPYRIGHT

Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.