705 lines
26 KiB
Plaintext
705 lines
26 KiB
Plaintext
=pod
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=head1 NAME
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SSL_CONF_cmd_value_type,
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SSL_CONF_cmd - send configuration command
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value);
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int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd);
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=head1 DESCRIPTION
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The function SSL_CONF_cmd() performs configuration operation B<cmd> with
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optional parameter B<value> on B<ctx>. Its purpose is to simplify application
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configuration of B<SSL_CTX> or B<SSL> structures by providing a common
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framework for command line options or configuration files.
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SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to.
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=head1 SUPPORTED COMMAND LINE COMMANDS
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Currently supported B<cmd> names for command lines (i.e. when the
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flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names
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are case sensitive. Unless otherwise stated commands can be used by
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both clients and servers and the B<value> parameter is not used. The default
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prefix for command line commands is B<-> and that is reflected below.
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=over 4
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=item B<-sigalgs>
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This sets the supported signature algorithms for TLSv1.2 and TLSv1.3.
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For clients this
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value is used directly for the supported signature algorithms extension. For
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servers it is used to determine which signature algorithms to support.
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The B<value> argument should be a colon separated list of signature algorithms
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in order of decreasing preference of the form B<algorithm+hash> or
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B<signature_scheme>. B<algorithm>
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is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
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OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
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Note: algorithm and hash names are case sensitive.
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B<signature_scheme> is one of the signature schemes defined in TLSv1.3,
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specified using the IETF name, e.g., B<ecdsa_secp256r1_sha256>, B<ed25519>,
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or B<rsa_pss_pss_sha256>.
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If this option is not set then all signature algorithms supported by the
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OpenSSL library are permissible.
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Note: algorithms which specify a PKCS#1 v1.5 signature scheme (either by
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using B<RSA> as the B<algorithm> or by using one of the B<rsa_pkcs1_*>
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identifiers) are ignored in TLSv1.3 and will not be negotiated.
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=item B<-client_sigalgs>
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This sets the supported signature algorithms associated with client
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authentication for TLSv1.2 and TLSv1.3.
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For servers the value is used in the
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B<signature_algorithms> field of a B<CertificateRequest> message.
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For clients it is
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used to determine which signature algorithm to use with the client certificate.
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If a server does not request a certificate this option has no effect.
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The syntax of B<value> is identical to B<-sigalgs>. If not set then
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the value set for B<-sigalgs> will be used instead.
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=item B<-groups>
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This sets the supported groups. For clients, the groups are
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sent using the supported groups extension. For servers, it is used
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to determine which group to use. This setting affects groups used for
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signatures (in TLSv1.2 and earlier) and key exchange. The first group listed
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will also be used for the B<key_share> sent by a client in a TLSv1.3
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B<ClientHello>.
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The B<value> argument is a colon separated list of groups. The group can be
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either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
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applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g. B<prime256v1>). Group
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names are case sensitive. The list should be in order of preference with the
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most preferred group first.
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=item B<-curves>
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This is a synonym for the "-groups" command.
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=item B<-named_curve>
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This sets the temporary curve used for ephemeral ECDH modes. Only used by
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servers
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The B<value> argument is a curve name or the special value B<auto> which
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picks an appropriate curve based on client and server preferences. The curve
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can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
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(e.g. B<prime256v1>). Curve names are case sensitive.
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=item B<-cipher>
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Sets the TLSv1.2 and below ciphersuite list to B<value>. This list will be
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combined with any configured TLSv1.3 ciphersuites. Note: syntax checking
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of B<value> is currently not performed unless a B<SSL> or B<SSL_CTX> structure is
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associated with B<cctx>.
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=item B<-ciphersuites>
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Sets the available ciphersuites for TLSv1.3 to value. This is a simple colon
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(":") separated list of TLSv1.3 ciphersuite names in order of preference. This
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list will be combined any configured TLSv1.2 and below ciphersuites.
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See L<ciphers(1)> for more information.
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=item B<-cert>
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Attempts to use the file B<value> as the certificate for the appropriate
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context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
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structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
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structure is set. This option is only supported if certificate operations
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are permitted.
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=item B<-key>
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Attempts to use the file B<value> as the private key for the appropriate
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context. This option is only supported if certificate operations
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are permitted. Note: if no B<-key> option is set then a private key is
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not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
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=item B<-dhparam>
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Attempts to use the file B<value> as the set of temporary DH parameters for
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the appropriate context. This option is only supported if certificate
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operations are permitted.
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=item B<-record_padding>
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Attempts to pad TLSv1.3 records so that they are a multiple of B<value> in
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length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
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B<value> must be >1 or <=16384.
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=item B<-no_renegotiation>
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Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting
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B<SSL_OP_NO_RENEGOTIATION>.
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=item B<-min_protocol>, B<-max_protocol>
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Sets the minimum and maximum supported protocol.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
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B<TLSv1.2>, B<TLSv1.3> for TLS; B<DTLSv1>, B<DTLSv1.2> for DTLS, and B<None>
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for no limit.
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If either the lower or upper bound is not specified then only the other bound
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applies, if specified.
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If your application supports both TLS and DTLS you can specify any of these
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options twice, once with a bound for TLS and again with an appropriate bound
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for DTLS.
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To restrict the supported protocol versions use these commands rather than the
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deprecated alternative commands below.
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=item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
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Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by
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setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
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B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
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respectively. These options are deprecated, instead use B<-min_protocol> and
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B<-max_protocol>.
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=item B<-bugs>
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Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
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=item B<-comp>
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Enables support for SSL/TLS compression, same as clearing
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B<SSL_OP_NO_COMPRESSION>.
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This command was introduced in OpenSSL 1.1.0.
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As of OpenSSL 1.1.0, compression is off by default.
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=item B<-no_comp>
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Disables support for SSL/TLS compression, same as setting
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B<SSL_OP_NO_COMPRESSION>.
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As of OpenSSL 1.1.0, compression is off by default.
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=item B<-no_ticket>
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Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
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=item B<-serverpref>
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Use server and not client preference order when determining which cipher suite,
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signature algorithm or elliptic curve to use for an incoming connection.
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Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
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=item B<-prioritize_chacha>
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Prioritize ChaCha ciphers when the client has a ChaCha20 cipher at the top of
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its preference list. This usually indicates a client without AES hardware
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acceleration (e.g. mobile) is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>.
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Only used by servers. Requires B<-serverpref>.
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=item B<-no_resumption_on_reneg>
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set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
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=item B<-legacyrenegotiation>
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permits the use of unsafe legacy renegotiation. Equivalent to setting
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B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
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=item B<-legacy_server_connect>, B<-no_legacy_server_connect>
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permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
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clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
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Set by default.
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=item B<-allow_no_dhe_kex>
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In TLSv1.3 allow a non-(ec)dhe based key exchange mode on resumption. This means
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that there will be no forward secrecy for the resumed session.
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=item B<-strict>
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enables strict mode protocol handling. Equivalent to setting
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B<SSL_CERT_FLAG_TLS_STRICT>.
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=item B<-anti_replay>, B<-no_anti_replay>
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Switches replay protection, on or off respectively. With replay protection on,
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OpenSSL will automatically detect if a session ticket has been used more than
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once, TLSv1.3 has been negotiated, and early data is enabled on the server. A
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full handshake is forced if a session ticket is used a second or subsequent
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time. Anti-Replay is on by default unless overridden by a configuration file and
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is only used by servers. Anti-replay measures are required for compliance with
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the TLSv1.3 specification. Some applications may be able to mitigate the replay
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risks in other ways and in such cases the built-in OpenSSL functionality is not
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required. Switching off anti-replay is equivalent to B<SSL_OP_NO_ANTI_REPLAY>.
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=back
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=head1 SUPPORTED CONFIGURATION FILE COMMANDS
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Currently supported B<cmd> names for configuration files (i.e. when the
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flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
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B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
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as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
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are also case insensitive.
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Note: the command prefix (if set) alters the recognised B<cmd> values.
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=over 4
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=item B<CipherString>
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Sets the ciphersuite list for TLSv1.2 and below to B<value>. This list will be
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combined with any configured TLSv1.3 ciphersuites. Note: syntax
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checking of B<value> is currently not performed unless an B<SSL> or B<SSL_CTX>
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structure is associated with B<cctx>.
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=item B<Ciphersuites>
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Sets the available ciphersuites for TLSv1.3 to B<value>. This is a simple colon
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(":") separated list of TLSv1.3 ciphersuite names in order of preference. This
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list will be combined any configured TLSv1.2 and below ciphersuites.
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See L<ciphers(1)> for more information.
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=item B<Certificate>
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Attempts to use the file B<value> as the certificate for the appropriate
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context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
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structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
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structure is set. This option is only supported if certificate operations
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are permitted.
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=item B<PrivateKey>
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Attempts to use the file B<value> as the private key for the appropriate
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context. This option is only supported if certificate operations
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are permitted. Note: if no B<PrivateKey> option is set then a private key is
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not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
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=item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
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These options indicate a file or directory used for building certificate
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chains or verifying certificate chains. These options are only supported
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if certificate operations are permitted.
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=item B<RequestCAFile>
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This option indicates a file containing a set of certificates in PEM form.
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The subject names of the certificates are sent to the peer in the
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B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
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CertificateRequest) or in a certificate request for previous versions or
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TLS.
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=item B<ServerInfoFile>
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Attempts to use the file B<value> in the "serverinfo" extension using the
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function SSL_CTX_use_serverinfo_file.
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=item B<DHParameters>
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Attempts to use the file B<value> as the set of temporary DH parameters for
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the appropriate context. This option is only supported if certificate
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operations are permitted.
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=item B<RecordPadding>
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Attempts to pad TLSv1.3 records so that they are a multiple of B<value> in
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length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
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B<value> must be >1 or <=16384.
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=item B<SignatureAlgorithms>
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This sets the supported signature algorithms for TLSv1.2 and TLSv1.3.
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For clients this
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value is used directly for the supported signature algorithms extension. For
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servers it is used to determine which signature algorithms to support.
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The B<value> argument should be a colon separated list of signature algorithms
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in order of decreasing preference of the form B<algorithm+hash> or
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B<signature_scheme>. B<algorithm>
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is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
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OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
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Note: algorithm and hash names are case sensitive.
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B<signature_scheme> is one of the signature schemes defined in TLSv1.3,
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specified using the IETF name, e.g., B<ecdsa_secp256r1_sha256>, B<ed25519>,
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or B<rsa_pss_pss_sha256>.
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If this option is not set then all signature algorithms supported by the
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OpenSSL library are permissible.
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Note: algorithms which specify a PKCS#1 v1.5 signature scheme (either by
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using B<RSA> as the B<algorithm> or by using one of the B<rsa_pkcs1_*>
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identifiers) are ignored in TLSv1.3 and will not be negotiated.
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=item B<ClientSignatureAlgorithms>
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This sets the supported signature algorithms associated with client
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authentication for TLSv1.2 and TLSv1.3.
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For servers the value is used in the
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B<signature_algorithms> field of a B<CertificateRequest> message.
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For clients it is
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used to determine which signature algorithm to use with the client certificate.
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If a server does not request a certificate this option has no effect.
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The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
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the value set for B<SignatureAlgorithms> will be used instead.
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=item B<Groups>
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This sets the supported groups. For clients, the groups are
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sent using the supported groups extension. For servers, it is used
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to determine which group to use. This setting affects groups used for
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signatures (in TLSv1.2 and earlier) and key exchange. The first group listed
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will also be used for the B<key_share> sent by a client in a TLSv1.3
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B<ClientHello>.
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The B<value> argument is a colon separated list of groups. The group can be
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either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
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applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g. B<prime256v1>). Group
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names are case sensitive. The list should be in order of preference with the
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most preferred group first.
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=item B<Curves>
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This is a synonym for the "Groups" command.
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=item B<MinProtocol>
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This sets the minimum supported SSL, TLS or DTLS version.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
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B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>.
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The SSL and TLS bounds apply only to TLS-based contexts, while the DTLS bounds
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apply only to DTLS-based contexts.
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The command can be repeated with one instance setting a TLS bound, and the
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other setting a DTLS bound.
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The value B<None> applies to both types of contexts and disables the limits.
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=item B<MaxProtocol>
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This sets the maximum supported SSL, TLS or DTLS version.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
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B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>.
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The SSL and TLS bounds apply only to TLS-based contexts, while the DTLS bounds
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apply only to DTLS-based contexts.
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The command can be repeated with one instance setting a TLS bound, and the
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other setting a DTLS bound.
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The value B<None> applies to both types of contexts and disables the limits.
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=item B<Protocol>
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This can be used to enable or disable certain versions of the SSL,
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TLS or DTLS protocol.
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The B<value> argument is a comma separated list of supported protocols
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to enable or disable.
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If a protocol is preceded by B<-> that version is disabled.
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All protocol versions are enabled by default.
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You need to disable at least one protocol version for this setting have any
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effect.
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Only enabling some protocol versions does not disable the other protocol
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versions.
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Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
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B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>.
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The special value B<ALL> refers to all supported versions.
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This can't enable protocols that are disabled using B<MinProtocol>
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or B<MaxProtocol>, but can disable protocols that are still allowed
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by them.
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The B<Protocol> command is fragile and deprecated; do not use it.
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Use B<MinProtocol> and B<MaxProtocol> instead.
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If you do use B<Protocol>, make sure that the resulting range of enabled
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protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
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sure to also leave TLS 1.1 enabled.
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=item B<Options>
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The B<value> argument is a comma separated list of various flags to set.
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If a flag string is preceded B<-> it is disabled.
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See the L<SSL_CTX_set_options(3)> function for more details of
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individual options.
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Each option is listed below. Where an operation is enabled by default
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the B<-flag> syntax is needed to disable it.
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B<SessionTicket>: session ticket support, enabled by default. Inverse of
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B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
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B<SSL_OP_NO_TICKET>.
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B<Compression>: SSL/TLS compression support, disabled by default. Inverse
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of B<SSL_OP_NO_COMPRESSION>.
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B<EmptyFragments>: use empty fragments as a countermeasure against a
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SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
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is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
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B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
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B<DHSingle>: enable single use DH keys, set by default. Inverse of
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B<SSL_OP_DH_SINGLE>. Only used by servers.
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B<ECDHSingle>: enable single use ECDH keys, set by default. Inverse of
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B<SSL_OP_ECDH_SINGLE>. Only used by servers.
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|
|
|
B<ServerPreference>: use server and not client preference order when
|
|
determining which cipher suite, signature algorithm or elliptic curve
|
|
to use for an incoming connection. Equivalent to
|
|
B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
|
|
|
|
B<PrioritizeChaCha>: prioritizes ChaCha ciphers when the client has a
|
|
ChaCha20 cipher at the top of its preference list. This usually indicates
|
|
a mobile client is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>.
|
|
Only used by servers.
|
|
|
|
B<NoResumptionOnRenegotiation>: set
|
|
B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
|
|
|
|
B<NoRenegotiation>: disables all attempts at renegotiation in TLSv1.2 and
|
|
earlier, same as setting B<SSL_OP_NO_RENEGOTIATION>.
|
|
|
|
B<UnsafeLegacyRenegotiation>: permits the use of unsafe legacy renegotiation.
|
|
Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
|
|
|
|
B<UnsafeLegacyServerConnect>: permits the use of unsafe legacy renegotiation
|
|
for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
|
|
Set by default.
|
|
|
|
B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
|
|
default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
|
|
B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
|
|
|
|
B<AllowNoDHEKEX>: In TLSv1.3 allow a non-(ec)dhe based key exchange mode on
|
|
resumption. This means that there will be no forward secrecy for the resumed
|
|
session. Equivalent to B<SSL_OP_ALLOW_NO_DHE_KEX>.
|
|
|
|
B<MiddleboxCompat>: If set then dummy Change Cipher Spec (CCS) messages are sent
|
|
in TLSv1.3. This has the effect of making TLSv1.3 look more like TLSv1.2 so that
|
|
middleboxes that do not understand TLSv1.3 will not drop the connection. This
|
|
option is set by default. A future version of OpenSSL may not set this by
|
|
default. Equivalent to B<SSL_OP_ENABLE_MIDDLEBOX_COMPAT>.
|
|
|
|
B<AntiReplay>: If set then OpenSSL will automatically detect if a session ticket
|
|
has been used more than once, TLSv1.3 has been negotiated, and early data is
|
|
enabled on the server. A full handshake is forced if a session ticket is used a
|
|
second or subsequent time. This option is set by default and is only used by
|
|
servers. Anti-replay measures are required to comply with the TLSv1.3
|
|
specification. Some applications may be able to mitigate the replay risks in
|
|
other ways and in such cases the built-in OpenSSL functionality is not required.
|
|
Disabling anti-replay is equivalent to setting B<SSL_OP_NO_ANTI_REPLAY>.
|
|
|
|
=item B<VerifyMode>
|
|
|
|
The B<value> argument is a comma separated list of flags to set.
|
|
|
|
B<Peer> enables peer verification: for clients only.
|
|
|
|
B<Request> requests but does not require a certificate from the client.
|
|
Servers only.
|
|
|
|
B<Require> requests and requires a certificate from the client: an error
|
|
occurs if the client does not present a certificate. Servers only.
|
|
|
|
B<Once> requests a certificate from a client only on the initial connection:
|
|
not when renegotiating. Servers only.
|
|
|
|
B<RequestPostHandshake> configures the connection to support requests but does
|
|
not require a certificate from the client post-handshake. A certificate will
|
|
not be requested during the initial handshake. The server application must
|
|
provide a mechanism to request a certificate post-handshake. Servers only.
|
|
TLSv1.3 only.
|
|
|
|
B<RequiresPostHandshake> configures the connection to support requests and
|
|
requires a certificate from the client post-handshake: an error occurs if the
|
|
client does not present a certificate. A certificate will not be requested
|
|
during the initial handshake. The server application must provide a mechanism
|
|
to request a certificate post-handshake. Servers only. TLSv1.3 only.
|
|
|
|
=item B<ClientCAFile>, B<ClientCAPath>
|
|
|
|
A file or directory of certificates in PEM format whose names are used as the
|
|
set of acceptable names for client CAs. Servers only. This option is only
|
|
supported if certificate operations are permitted.
|
|
|
|
=back
|
|
|
|
=head1 SUPPORTED COMMAND TYPES
|
|
|
|
The function SSL_CONF_cmd_value_type() currently returns one of the following
|
|
types:
|
|
|
|
=over 4
|
|
|
|
=item B<SSL_CONF_TYPE_UNKNOWN>
|
|
|
|
The B<cmd> string is unrecognised, this return value can be use to flag
|
|
syntax errors.
|
|
|
|
=item B<SSL_CONF_TYPE_STRING>
|
|
|
|
The value is a string without any specific structure.
|
|
|
|
=item B<SSL_CONF_TYPE_FILE>
|
|
|
|
The value is a filename.
|
|
|
|
=item B<SSL_CONF_TYPE_DIR>
|
|
|
|
The value is a directory name.
|
|
|
|
=item B<SSL_CONF_TYPE_NONE>
|
|
|
|
The value string is not used e.g. a command line option which doesn't take an
|
|
argument.
|
|
|
|
=back
|
|
|
|
=head1 NOTES
|
|
|
|
The order of operations is significant. This can be used to set either defaults
|
|
or values which cannot be overridden. For example if an application calls:
|
|
|
|
SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
|
|
SSL_CONF_cmd(ctx, userparam, uservalue);
|
|
|
|
it will disable SSLv3 support by default but the user can override it. If
|
|
however the call sequence is:
|
|
|
|
SSL_CONF_cmd(ctx, userparam, uservalue);
|
|
SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
|
|
|
|
SSLv3 is B<always> disabled and attempt to override this by the user are
|
|
ignored.
|
|
|
|
By checking the return code of SSL_CONF_cmd() it is possible to query if a
|
|
given B<cmd> is recognised, this is useful if SSL_CONF_cmd() values are
|
|
mixed with additional application specific operations.
|
|
|
|
For example an application might call SSL_CONF_cmd() and if it returns
|
|
-2 (unrecognised command) continue with processing of application specific
|
|
commands.
|
|
|
|
Applications can also use SSL_CONF_cmd() to process command lines though the
|
|
utility function SSL_CONF_cmd_argv() is normally used instead. One way
|
|
to do this is to set the prefix to an appropriate value using
|
|
SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
|
|
following argument to B<value> (which may be NULL).
|
|
|
|
In this case if the return value is positive then it is used to skip that
|
|
number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
|
|
returned then B<cmd> is not recognised and application specific arguments
|
|
can be checked instead. If -3 is returned a required argument is missing
|
|
and an error is indicated. If 0 is returned some other error occurred and
|
|
this can be reported back to the user.
|
|
|
|
The function SSL_CONF_cmd_value_type() can be used by applications to
|
|
check for the existence of a command or to perform additional syntax
|
|
checking or translation of the command value. For example if the return
|
|
value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
|
|
pathname to an absolute pathname.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
|
|
B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
|
|
returns the number of arguments processed. This is useful when processing
|
|
command lines.
|
|
|
|
A return value of -2 means B<cmd> is not recognised.
|
|
|
|
A return value of -3 means B<cmd> is recognised and the command requires a
|
|
value but B<value> is NULL.
|
|
|
|
A return code of 0 indicates that both B<cmd> and B<value> are valid but an
|
|
error occurred attempting to perform the operation: for example due to an
|
|
error in the syntax of B<value> in this case the error queue may provide
|
|
additional information.
|
|
|
|
=head1 EXAMPLES
|
|
|
|
Set supported signature algorithms:
|
|
|
|
SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
|
|
|
|
There are various ways to select the supported protocols.
|
|
|
|
This set the minimum protocol version to TLSv1, and so disables SSLv3.
|
|
This is the recommended way to disable protocols.
|
|
|
|
SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
|
|
|
|
The following also disables SSLv3:
|
|
|
|
SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
|
|
|
|
The following will first enable all protocols, and then disable
|
|
SSLv3.
|
|
If no protocol versions were disabled before this has the same effect as
|
|
"-SSLv3", but if some versions were disables this will re-enable them before
|
|
disabling SSLv3.
|
|
|
|
SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
|
|
|
|
Only enable TLSv1.2:
|
|
|
|
SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
|
|
SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
|
|
|
|
This also only enables TLSv1.2:
|
|
|
|
SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
|
|
|
|
Disable TLS session tickets:
|
|
|
|
SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
|
|
|
|
Enable compression:
|
|
|
|
SSL_CONF_cmd(ctx, "Options", "Compression");
|
|
|
|
Set supported curves to P-256, P-384:
|
|
|
|
SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<SSL_CONF_CTX_new(3)>,
|
|
L<SSL_CONF_CTX_set_flags(3)>,
|
|
L<SSL_CONF_CTX_set1_prefix(3)>,
|
|
L<SSL_CONF_CTX_set_ssl_ctx(3)>,
|
|
L<SSL_CONF_cmd_argv(3)>,
|
|
L<SSL_CTX_set_options(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
The SSL_CONF_cmd() function was added in OpenSSL 1.0.2.
|
|
|
|
The B<SSL_OP_NO_SSL2> option doesn't have effect since 1.1.0, but the macro
|
|
is retained for backwards compatibility.
|
|
|
|
The B<SSL_CONF_TYPE_NONE> was added in OpenSSL 1.1.0. In earlier versions of
|
|
OpenSSL passing a command which didn't take an argument would return
|
|
B<SSL_CONF_TYPE_UNKNOWN>.
|
|
|
|
B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
|
|
|
|
B<AllowNoDHEKEX> and B<PrioritizeChaCha> were added in OpenSSL 1.1.1.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2012-2022 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the OpenSSL license (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
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|