.\" $OpenBSD: openssl.cnf.5,v 1.10 2023/11/19 10:23:53 tb Exp $ .\" full merge up to: OpenSSL man5/config b53338cb Feb 28 12:30:28 2017 +0100 .\" selective merge up to: OpenSSL a8c5ed81 Jul 18 13:57:25 2017 -0400 .\" .\" This file was written by Dr. Stephen Henson . .\" Copyright (c) 1999, 2000, 2004, 2013, 2015, 2016, 2017 The OpenSSL Project. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. All advertising materials mentioning features or use of this .\" software must display the following acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" .\" .\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to .\" endorse or promote products derived from this software without .\" prior written permission. For written permission, please contact .\" openssl-core@openssl.org. .\" .\" 5. Products derived from this software may not be called "OpenSSL" .\" nor may "OpenSSL" appear in their names without prior written .\" permission of the OpenSSL Project. .\" .\" 6. Redistributions of any form whatsoever must retain the following .\" acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" .\" .\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY .\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: November 19 2023 $ .Dt OPENSSL.CNF 5 .Os .Sh NAME .Nm openssl.cnf .Nd OpenSSL configuration files .Sh DESCRIPTION The OpenSSL CONF library can be used to read configuration files; see .Xr CONF_modules_load_file 3 . It is used for the OpenSSL master configuration file .Pa /etc/ssl/openssl.cnf and in a few other places like .Sy SPKAC files and certificate extension files for the .Xr openssl 1 .Cm x509 utility. OpenSSL applications can also use the CONF library for their own purposes. .Pp A configuration file is divided into a number of sections. Each section starts with a line .Bq Ar section_name and ends when a new section is started or the end of the file is reached. A section name can consist of alphanumeric characters and underscores. .Pp The first section of a configuration file is special and is referred to as the .Dq default section . It is usually unnamed and extends from the start of file to the first named section. When a name is being looked up, it is first looked up in a named section (if any) and then in the default section. .Pp The environment is mapped onto a section called .Ic ENV . .Pp Comments can be included by preceding them with the .Ql # character. .Pp Each section in a configuration file consists of a number of name and value pairs of the form .Ar name Ns = Ns Ar value . .Pp The .Ar name string can contain any alphanumeric characters as well as a few punctuation symbols such as .Ql \&. .Ql \&, .Ql \&; and .Ql _ . .Pp The .Ar value string consists of the string following the .Ql = character until the end of the line with any leading and trailing whitespace removed. .Pp The value string undergoes variable expansion. This can be done by including substrings of the form .Pf $ Ar name or .Pf $ Brq Ar name : 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 .Pf $ Ar section Ns :: Ns Ar name or .Pf $ Brq Ar section Ns :: Ns Ar name . By using the form .Pf $ Ic ENV Ns :: Ns Ar name , environment variables can be substituted. It is also possible to assign values to environment variables by using the name .Ic ENV Ns :: Ns Ar name . This will work if the program looks up environment variables using the CONF library instead of calling .Xr getenv 3 directly. The value string must not exceed 64k in length after variable expansion or an error will occur. .Pp It is possible to escape certain characters by using any kind of quote or the .Ql \e character. By making the last character of a line a .Ql \e , a .Ar value string can be spread across multiple lines. In addition the sequences .Ql \en , .Ql \er , .Ql \eb , and .Ql \et are recognized. .Sh OPENSSL LIBRARY CONFIGURATION Applications can automatically configure certain aspects of OpenSSL using the master OpenSSL configuration file, or optionally an alternative configuration file. The .Xr openssl 1 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. .Pp To enable library configuration, the default section needs to contain an appropriate line which points to the main configuration section. The default name is .Ic openssl_conf , which is used by the .Xr openssl 1 utility. Other applications may use an alternative name such as .Sy myapplication_conf . All library configuration lines appear in the default section at the start of the configuration file. .Pp The configuration section should consist of a set of name value pairs which contain specific module configuration information. The .Ar name represents the name of the configuration module. The meaning of the .Ar value is module specific: it may, for example, represent a further configuration section containing configuration module specific information. For example: .Bd -literal -offset indent # The following line must be in the default section. openssl_conf = openssl_init [openssl_init] oid_section = new_oids [new_oids] \&... new oids here ... .Ed .Pp The features of each configuration module are described below. .Ss ASN1 Object Configuration Module This module has the name .Ic 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, and the value is the numerical form of the OID. Although some of the .Xr openssl 1 utility subcommands already have their own ASN1 OBJECT section functionality, not all do. By using the ASN1 OBJECT configuration module, all the .Xr openssl 1 utility subcommands can see the new objects as well as any compliant applications. For example: .Bd -literal -offset indent [new_oids] some_new_oid = 1.2.3.4 some_other_oid = 1.2.3.5 .Ed .Pp It is also possible to set the value to the long name followed by a comma and the numerical OID form. For example: .Pp .Dl shortName = some object long name, 1.2.3.4 .Sh FILES .Bl -tag -width /etc/ssl/openssl.cnf -compact .It Pa /etc/ssl/openssl.cnf standard configuration file .El .Sh EXAMPLES Here is a sample configuration file using some of the features mentioned above: .Bd -literal -offset indent # This is the default section. HOME=/temp RANDFILE= ${ENV::HOME}/.rnd configdir=$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 \e cover several lines \e by including \e\e characters message = Hello World\en [ section_two ] greeting = $section_one::message .Ed .Pp This next example shows how to expand environment variables safely. .Pp Suppose you want a variable called .Sy tmpfile to refer to a temporary filename. The directory it is placed in can determined by the .Ev TEMP or .Ev TMP environment variables but they may not be set to any value at all. If you just include the environment variable names and the variable doesn't exist then this will cause an error when an attempt is made to load the configuration file. By making use of the default section both values can be looked up with .Ev TEMP taking priority and .Pa /tmp used if neither is defined: .Bd -literal -offset indent TMP=/tmp # The above value is used if TMP isn't in the environment TEMP=$ENV::TMP # The above value is used if TEMP isn't in the environment tmpfile=${ENV::TEMP}/tmp.filename .Ed .Pp More complex OpenSSL library configuration. Add OID: .Bd -literal -offset indent # 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 oid_section = new_oids [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 .Ed .Pp The above examples can be used with any application supporting library configuration if "openssl_conf" is modified to match the appropriate "appname". .Pp For example if the second sample file above is saved to "example.cnf" then the command line: .Pp .Dl OPENSSL_CONF=example.cnf openssl asn1parse -genstr OID:1.2.3.4.1 .Pp will output: .Dl 0:d=0 hl=2 l= 4 prim: OBJECT :newoid1 .Pp showing that the OID "newoid1" has been added as "1.2.3.4.1". .Sh SEE ALSO .Xr openssl 1 , .Xr CONF_modules_load_file 3 , .Xr OPENSSL_config 3 , .Xr x509v3.cnf 5 .Sh CAVEATS 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 also 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 .Ev HOME which may not be defined on non Unix systems and would cause an error. .Pp 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 .Sx EXAMPLES section for an example of how to do this. .Pp If the same variable is defined more than once 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 .Ql \&. , for example: .Bd -literal -offset indent 1.OU="My first OU" 2.OU="My Second OU" .Ed .Sh BUGS Currently there is no way to include characters using the octal .Pf \e Ar nnn form. Strings are all NUL terminated, so NUL bytes cannot form part of the value. .Pp The escaping isn't quite right: if you want to use sequences like .Ql \en , you can't use any quote escaping on the same line. .Pp Files are loaded in a single pass. This means that a variable expansion will only work if the variables referenced are defined earlier in the file.