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Diffstat (limited to 'openssl/doc/ssl/SSL_CONF_cmd.pod')
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diff --git a/openssl/doc/ssl/SSL_CONF_cmd.pod b/openssl/doc/ssl/SSL_CONF_cmd.pod new file mode 100755 index 000000000..6d073cb9f --- /dev/null +++ b/openssl/doc/ssl/SSL_CONF_cmd.pod @@ -0,0 +1,433 @@ +=pod + +=head1 NAME + +SSL_CONF_cmd - send configuration command + +=head1 SYNOPSIS + + #include <openssl/ssl.h> + + int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value); + int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd); + int SSL_CONF_finish(SSL_CONF_CTX *cctx); + +=head1 DESCRIPTION + +The function SSL_CONF_cmd() performs configuration operation B<cmd> with +optional parameter B<value> on B<ctx>. Its purpose is to simplify application +configuration of B<SSL_CTX> or B<SSL> structures by providing a common +framework for command line options or configuration files. + +SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to. + +The function SSL_CONF_finish() must be called after all configuration +operations have been completed. It is used to finalise any operations +or to process defaults. + +=head1 SUPPORTED COMMAND LINE COMMANDS + +Currently supported B<cmd> names for command lines (i.e. when the +flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names +are case sensitive. Unless otherwise stated commands can be used by +both clients and servers and the B<value> parameter is not used. The default +prefix for command line commands is B<-> and that is reflected below. + +=over 4 + +=item B<-sigalgs> + +This sets the supported signature algorithms for TLS v1.2. For clients this +value is used directly for the supported signature algorithms extension. For +servers it is used to determine which signature algorithms to support. + +The B<value> argument should be a colon separated list of signature algorithms +in order of decreasing preference of the form B<algorithm+hash>. B<algorithm> +is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm +OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>. +Note: algorithm and hash names are case sensitive. + +If this option is not set then all signature algorithms supported by the +OpenSSL library are permissible. + +=item B<-client_sigalgs> + +This sets the supported signature algorithms associated with client +authentication for TLS v1.2. For servers the value is used in the supported +signature algorithms field of a certificate request. For clients it is +used to determine which signature algorithm to with the client certificate. +If a server does not request a certificate this option has no effect. + +The syntax of B<value> is identical to B<-sigalgs>. If not set then +the value set for B<-sigalgs> will be used instead. + +=item B<-curves> + +This sets the supported elliptic curves. For clients the curves are +sent using the supported curves extension. For servers it is used +to determine which curve to use. This setting affects curves used for both +signatures and key exchange, if applicable. + +The B<value> argument is a colon separated list of curves. The curve can be +either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g +B<prime256v1>). Curve names are case sensitive. + +=item B<-named_curve> + +This sets the temporary curve used for ephemeral ECDH modes. Only used by +servers + +The B<value> argument is a curve name or the special value B<auto> which +picks an appropriate curve based on client and server preferences. The curve +can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name +(e.g B<prime256v1>). Curve names are case sensitive. + +=item B<-cipher> + +Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is +currently not performed unless a B<SSL> or B<SSL_CTX> structure is +associated with B<cctx>. + +=item B<-cert> + +Attempts to use the file B<value> as the certificate for the appropriate +context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX> +structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL> +structure is set. This option is only supported if certificate operations +are permitted. + +=item B<-key> + +Attempts to use the file B<value> as the private key for the appropriate +context. This option is only supported if certificate operations +are permitted. Note: if no B<-key> option is set then a private key is +not loaded: it does not currently use the B<-cert> file. + +=item B<-dhparam> + +Attempts to use the file B<value> as the set of temporary DH parameters for +the appropriate context. This option is only supported if certificate +operations are permitted. + +=item B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2> + +Disables protocol support for SSLv2, SSLv3, TLS 1.0, TLS 1.1 or TLS 1.2 +by setting the corresponding options B<SSL_OP_NO_SSL2>, B<SSL_OP_NO_SSL3>, +B<SSL_OP_NO_TLS1>, B<SSL_OP_NO_TLS1_1> and B<SSL_OP_NO_TLS1_2> respectively. + +=item B<-bugs> + +Various bug workarounds are set, same as setting B<SSL_OP_ALL>. + +=item B<-no_comp> + +Disables support for SSL/TLS compression, same as setting B<SSL_OP_NO_COMPRESS>. + +=item B<-no_ticket> + +Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>. + +=item B<-serverpref> + +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. + +=item B<-no_resumption_on_reneg> + +set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers. + +=item B<-legacyrenegotiation> + +permits the use of unsafe legacy renegotiation. Equivalent to setting +B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>. + +=item B<-legacy_server_connect>, B<-no_legacy_server_connect> + +permits or prohibits the use of unsafe legacy renegotiation for OpenSSL +clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>. +Set by default. + +=item B<-strict> + +enables strict mode protocol handling. Equivalent to setting +B<SSL_CERT_FLAG_TLS_STRICT>. + +=item B<-debug_broken_protocol> + +disables various checks and permits several kinds of broken protocol behaviour +for testing purposes: it should B<NEVER> be used in anything other than a test +environment. Only supported if OpenSSL is configured with +B<-DOPENSSL_SSL_DEBUG_BROKEN_PROTOCOL>. + +=back + +=head1 SUPPORTED CONFIGURATION FILE COMMANDS + +Currently supported B<cmd> names for configuration files (i.e. when the +flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file +B<cmd> names and are case insensitive so B<signaturealgorithms> is recognised +as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names +are also case insensitive. + +Note: the command prefix (if set) alters the recognised B<cmd> values. + +=over 4 + +=item B<CipherString> + +Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is +currently not performed unless an B<SSL> or B<SSL_CTX> structure is +associated with B<cctx>. + +=item B<Certificate> + +Attempts to use the file B<value> as the certificate for the appropriate +context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX> +structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL> +structure is set. This option is only supported if certificate operations +are permitted. + +=item B<PrivateKey> + +Attempts to use the file B<value> as the private key for the appropriate +context. This option is only supported if certificate operations +are permitted. Note: if no B<-key> option is set then a private key is +not loaded: it does not currently use the B<Certificate> file. + +=item B<DHParameters> + +Attempts to use the file B<value> as the set of temporary DH parameters for +the appropriate context. This option is only supported if certificate +operations are permitted. + +=item B<SignatureAlgorithms> + +This sets the supported signature algorithms for TLS v1.2. For clients this +value is used directly for the supported signature algorithms extension. For +servers it is used to determine which signature algorithms to support. + +The B<value> argument should be a colon separated list of signature algorithms +in order of decreasing preference of the form B<algorithm+hash>. B<algorithm> +is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm +OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>. +Note: algorithm and hash names are case sensitive. + +If this option is not set then all signature algorithms supported by the +OpenSSL library are permissible. + +=item B<ClientSignatureAlgorithms> + +This sets the supported signature algorithms associated with client +authentication for TLS v1.2. For servers the value is used in the supported +signature algorithms field of a certificate request. For clients it is +used to determine which signature algorithm to with the client certificate. + +The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then +the value set for B<SignatureAlgorithms> will be used instead. + +=item B<Curves> + +This sets the supported elliptic curves. For clients the curves are +sent using the supported curves extension. For servers it is used +to determine which curve to use. This setting affects curves used for both +signatures and key exchange, if applicable. + +The B<value> argument is a colon separated list of curves. The curve can be +either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g +B<prime256v1>). Curve names are case sensitive. + +=item B<ECDHParameters> + +This sets the temporary curve used for ephemeral ECDH modes. Only used by +servers + +The B<value> argument is a curve name or the special value B<Automatic> which +picks an appropriate curve based on client and server preferences. The curve +can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name +(e.g B<prime256v1>). Curve names are case sensitive. + +=item B<Protocol> + +The supported versions of the SSL or TLS protocol. + +The B<value> argument is a comma separated list of supported protocols to +enable or disable. If an protocol is preceded by B<-> that version is disabled. +All versions are enabled by default, though applications may choose to +explicitly disable some. Currently supported protocol values are B<SSLv2>, +B<SSLv3>, B<TLSv1>, B<TLSv1.1> and B<TLSv1.2>. The special value B<ALL> refers +to all supported versions. + +=item B<Options> + +The B<value> argument is a comma separated list of various flags to set. +If a flag string is preceded B<-> it is disabled. See the +B<SSL_CTX_set_options> function for more details of individual options. + +Each option is listed below. Where an operation is enabled by default +the B<-flag> syntax is needed to disable it. + +B<SessionTicket>: session ticket support, enabled by default. Inverse of +B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting +B<SSL_OP_NO_TICKET>. + +B<Compression>: SSL/TLS compression support, enabled by default. Inverse +of B<SSL_OP_NO_COMPRESSION>. + +B<EmptyFragments>: use empty fragments as a countermeasure against a +SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It +is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>. + +B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>. + +B<DHSingle>: enable single use DH keys, set by default. Inverse of +B<SSL_OP_DH_SINGLE>. Only used by servers. + +B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of +B<SSL_OP_ECDH_SINGLE>. Only used by servers. + +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<NoResumptionOnRenegotiation> set +B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers. + +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. + +=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 file name. + +=item B<SSL_CONF_TYPE_DIR> + +The value is a directory name. + +=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", "-SSLv2"); + SSL_CONF_cmd(ctx, userparam, uservalue); + +it will disable SSLv2 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", "-SSLv2"); + +SSLv2 is B<always> disabled and attempt to override this by the user are +ignored. + +By checking the return code of SSL_CTX_cmd() it is possible to query if a +given B<cmd> is recognised, this is useful is SSL_CTX_cmd() values are +mixed with additional application specific operations. + +For example an application might call SSL_CTX_cmd() and if it returns +-2 (unrecognised command) continue with processing of application specific +commands. + +Applications can also use SSL_CTX_cmd() to process command lines though the +utility function SSL_CTX_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_CTX_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 EXAMPLES + +Set supported signature algorithms: + + SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256"); + +Enable all protocols except SSLv3 and SSLv2: + + SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3,-SSLv2"); + +Only enable TLSv1.2: + + SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2"); + +Disable TLS session tickets: + + SSL_CONF_cmd(ctx, "Options", "-SessionTicket"); + +Set supported curves to P-256, P-384: + + SSL_CONF_cmd(ctx, "Curves", "P-256:P-384"); + +Set automatic support for any elliptic curve for key exchange: + + SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic"); + +=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. + +SSL_CONF_finish() returns 1 for success and 0 for failure. + +=head1 SEE ALSO + +L<SSL_CONF_CTX_new(3)|SSL_CONF_CTX_new(3)>, +L<SSL_CONF_CTX_set_flags(3)|SSL_CONF_CTX_set_flags(3)>, +L<SSL_CONF_CTX_set1_prefix(3)|SSL_CONF_CTX_set1_prefix(3)>, +L<SSL_CONF_CTX_set_ssl_ctx(3)|SSL_CONF_CTX_set_ssl_ctx(3)>, +L<SSL_CONF_cmd_argv(3)|SSL_CONF_cmd_argv(3)> + +=head1 HISTORY + +SSL_CONF_cmd() was first added to OpenSSL 1.0.2 + +=cut |