5 SSL_CONF_cmd_value_type, SSL_CONF_finish,
6 SSL_CONF_cmd - send configuration command
10 #include <openssl/ssl.h>
12 int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value);
13 int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd);
14 int SSL_CONF_finish(SSL_CONF_CTX *cctx);
18 The function SSL_CONF_cmd() performs configuration operation B<cmd> with
19 optional parameter B<value> on B<ctx>. Its purpose is to simplify application
20 configuration of B<SSL_CTX> or B<SSL> structures by providing a common
21 framework for command line options or configuration files.
23 SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to.
25 The function SSL_CONF_finish() must be called after all configuration
26 operations have been completed. It is used to finalise any operations
27 or to process defaults.
29 =head1 SUPPORTED COMMAND LINE COMMANDS
31 Currently supported B<cmd> names for command lines (i.e. when the
32 flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names
33 are case sensitive. Unless otherwise stated commands can be used by
34 both clients and servers and the B<value> parameter is not used. The default
35 prefix for command line commands is B<-> and that is reflected below.
41 This sets the supported signature algorithms for TLS v1.2. For clients this
42 value is used directly for the supported signature algorithms extension. For
43 servers it is used to determine which signature algorithms to support.
45 The B<value> argument should be a colon separated list of signature algorithms
46 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
47 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
48 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
49 Note: algorithm and hash names are case sensitive.
51 If this option is not set then all signature algorithms supported by the
52 OpenSSL library are permissible.
54 =item B<-client_sigalgs>
56 This sets the supported signature algorithms associated with client
57 authentication for TLS v1.2. For servers the value is used in the supported
58 signature algorithms field of a certificate request. For clients it is
59 used to determine which signature algorithm to with the client certificate.
60 If a server does not request a certificate this option has no effect.
62 The syntax of B<value> is identical to B<-sigalgs>. If not set then
63 the value set for B<-sigalgs> will be used instead.
67 This sets the supported groups. For clients, the groups are
68 sent using the supported groups extension. For servers, it is used
69 to determine which group to use. This setting affects groups used for both
70 signatures and key exchange, if applicable. It also affects the preferred
71 key_share sent by a client in a TLSv1.3 compatible connection.
73 The B<value> argument is a colon separated list of groups. The group can be
74 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
75 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
76 names are case sensitive. The list should be in order of preference with the
77 most preferred group first. The first listed group will be the one used for a
78 key_share by a TLSv1.3 client.
82 This is a synonym for the "-groups" command.
87 This sets the temporary curve used for ephemeral ECDH modes. Only used by
90 The B<value> argument is a curve name or the special value B<auto> which
91 picks an appropriate curve based on client and server preferences. The curve
92 can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
93 (e.g B<prime256v1>). Curve names are case sensitive.
97 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
98 currently not performed unless a B<SSL> or B<SSL_CTX> structure is
99 associated with B<cctx>.
103 Attempts to use the file B<value> as the certificate for the appropriate
104 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
105 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
106 structure is set. This option is only supported if certificate operations
111 Attempts to use the file B<value> as the private key for the appropriate
112 context. This option is only supported if certificate operations
113 are permitted. Note: if no B<-key> option is set then a private key is
114 not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
118 Attempts to use the file B<value> as the set of temporary DH parameters for
119 the appropriate context. This option is only supported if certificate
120 operations are permitted.
122 =item B<-record_padding>
124 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
125 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
126 B<value> must be >1 or <=16384.
128 =item B<-min_protocol>, B<-max_protocol>
130 Sets the minimum and maximum supported protocol.
131 Currently supported protocol values are B<SSLv3>, B<TLSv1>,
132 B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
133 and B<None> for no limit.
134 If the either bound is not specified then only the other bound applies,
136 To restrict the supported protocol versions use these commands rather
137 than the deprecated alternative commands below.
139 =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
141 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by
142 setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
143 B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
144 respectively. These options are deprecated, instead use B<-min_protocol> and
149 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
153 Enables support for SSL/TLS compression, same as clearing
154 B<SSL_OP_NO_COMPRESSION>.
155 This command was introduced in OpenSSL 1.1.0.
156 As of OpenSSL 1.1.0, compression is off by default.
160 Disables support for SSL/TLS compression, same as setting
161 B<SSL_OP_NO_COMPRESSION>.
162 As of OpenSSL 1.1.0, compression is off by default.
166 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
170 Use server and not client preference order when determining which cipher suite,
171 signature algorithm or elliptic curve to use for an incoming connection.
172 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
174 =item B<-no_resumption_on_reneg>
176 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
178 =item B<-legacyrenegotiation>
180 permits the use of unsafe legacy renegotiation. Equivalent to setting
181 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
183 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
185 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
186 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
191 enables strict mode protocol handling. Equivalent to setting
192 B<SSL_CERT_FLAG_TLS_STRICT>.
196 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
198 Currently supported B<cmd> names for configuration files (i.e. when the
199 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
200 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
201 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
202 are also case insensitive.
204 Note: the command prefix (if set) alters the recognised B<cmd> values.
208 =item B<CipherString>
210 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
211 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
212 associated with B<cctx>.
216 Attempts to use the file B<value> as the certificate for the appropriate
217 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
218 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
219 structure is set. This option is only supported if certificate operations
224 Attempts to use the file B<value> as the private key for the appropriate
225 context. This option is only supported if certificate operations
226 are permitted. Note: if no B<PrivateKey> option is set then a private key is
227 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
229 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
231 These options indicate a file or directory used for building certificate
232 chains or verifying certificate chains. These options are only supported
233 if certificate operations are permitted.
235 =item B<RequestCAFile>
237 This option indicates a file containing a set of certificates in PEM form.
238 The subject names of the certificates are sent to the peer in the
239 B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
240 CertificateRequest) or in a certificate request for previous versions or
243 =item B<ServerInfoFile>
245 Attempts to use the file B<value> in the "serverinfo" extension using the
246 function SSL_CTX_use_serverinfo_file.
248 =item B<DHParameters>
250 Attempts to use the file B<value> as the set of temporary DH parameters for
251 the appropriate context. This option is only supported if certificate
252 operations are permitted.
254 =item B<RecordPadding>
256 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
257 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
258 B<value> must be >1 or <=16384.
260 =item B<SignatureAlgorithms>
262 This sets the supported signature algorithms for TLS v1.2. For clients this
263 value is used directly for the supported signature algorithms extension. For
264 servers it is used to determine which signature algorithms to support.
266 The B<value> argument should be a colon separated list of signature algorithms
267 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
268 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
269 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
270 Note: algorithm and hash names are case sensitive.
272 If this option is not set then all signature algorithms supported by the
273 OpenSSL library are permissible.
275 =item B<ClientSignatureAlgorithms>
277 This sets the supported signature algorithms associated with client
278 authentication for TLS v1.2. For servers the value is used in the supported
279 signature algorithms field of a certificate request. For clients it is
280 used to determine which signature algorithm to with the client certificate.
282 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
283 the value set for B<SignatureAlgorithms> will be used instead.
287 This sets the supported groups. For clients, the groups are
288 sent using the supported groups extension. For servers, it is used
289 to determine which group to use. This setting affects groups used for both
290 signatures and key exchange, if applicable. It also affects the preferred
291 key_share sent by a client in a TLSv1.3 compatible connection.
293 The B<value> argument is a colon separated list of groups. The group can be
294 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
295 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
296 names are case sensitive. The list should be in order of preference with the
297 most preferred group first. The first listed group will be the one used for a
298 key_share by a TLSv1.3 client.
302 This is a synonym for the "Groups" command.
306 This sets the minimum supported SSL, TLS or DTLS version.
308 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
309 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
310 The value B<None> will disable the limit.
314 This sets the maximum supported SSL, TLS or DTLS version.
316 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
317 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
318 The value B<None> will disable the limit.
322 This can be used to enable or disable certain versions of the SSL,
323 TLS or DTLS protocol.
325 The B<value> argument is a comma separated list of supported protocols
326 to enable or disable.
327 If a protocol is preceded by B<-> that version is disabled.
329 All protocol versions are enabled by default.
330 You need to disable at least one protocol version for this setting have any
332 Only enabling some protocol versions does not disable the other protocol
335 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
336 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
337 The special value B<ALL> refers to all supported versions.
339 This can't enable protocols that are disabled using B<MinProtocol>
340 or B<MaxProtocol>, but can disable protocols that are still allowed
343 The B<Protocol> command is fragile and deprecated; do not use it.
344 Use B<MinProtocol> and B<MaxProtocol> instead.
345 If you do use B<Protocol>, make sure that the resulting range of enabled
346 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
347 sure to also leave TLS 1.1 enabled.
351 The B<value> argument is a comma separated list of various flags to set.
352 If a flag string is preceded B<-> it is disabled.
353 See the L<SSL_CTX_set_options(3)> function for more details of
356 Each option is listed below. Where an operation is enabled by default
357 the B<-flag> syntax is needed to disable it.
359 B<SessionTicket>: session ticket support, enabled by default. Inverse of
360 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
363 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
364 of B<SSL_OP_NO_COMPRESSION>.
366 B<EmptyFragments>: use empty fragments as a countermeasure against a
367 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
368 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
370 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
372 B<DHSingle>: enable single use DH keys, set by default. Inverse of
373 B<SSL_OP_DH_SINGLE>. Only used by servers.
375 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
376 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
378 B<ServerPreference> use server and not client preference order when
379 determining which cipher suite, signature algorithm or elliptic curve
380 to use for an incoming connection. Equivalent to
381 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
383 B<NoResumptionOnRenegotiation> set
384 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
386 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
387 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
389 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
390 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
393 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
394 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
395 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
399 The B<value> argument is a comma separated list of flags to set.
401 B<Peer> enables peer verification: for clients only.
403 B<Request> requests but does not require a certificate from the client.
406 B<Require> requests and requires a certificate from the client: an error
407 occurs if the client does not present a certificate. Servers only.
409 B<Once> requests a certificate from a client only on the initial connection:
410 not when renegotiating. Servers only.
412 =item B<ClientCAFile>, B<ClientCAPath>
414 A file or directory of certificates in PEM format whose names are used as the
415 set of acceptable names for client CAs. Servers only. This option is only
416 supported if certificate operations are permitted.
420 =head1 SUPPORTED COMMAND TYPES
422 The function SSL_CONF_cmd_value_type() currently returns one of the following
427 =item B<SSL_CONF_TYPE_UNKNOWN>
429 The B<cmd> string is unrecognised, this return value can be use to flag
432 =item B<SSL_CONF_TYPE_STRING>
434 The value is a string without any specific structure.
436 =item B<SSL_CONF_TYPE_FILE>
438 The value is a file name.
440 =item B<SSL_CONF_TYPE_DIR>
442 The value is a directory name.
444 =item B<SSL_CONF_TYPE_NONE>
446 The value string is not used e.g. a command line option which doesn't take an
453 The order of operations is significant. This can be used to set either defaults
454 or values which cannot be overridden. For example if an application calls:
456 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
457 SSL_CONF_cmd(ctx, userparam, uservalue);
459 it will disable SSLv3 support by default but the user can override it. If
460 however the call sequence is:
462 SSL_CONF_cmd(ctx, userparam, uservalue);
463 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
465 SSLv3 is B<always> disabled and attempt to override this by the user are
468 By checking the return code of SSL_CONF_cmd() it is possible to query if a
469 given B<cmd> is recognised, this is useful is SSL_CONF_cmd() values are
470 mixed with additional application specific operations.
472 For example an application might call SSL_CONF_cmd() and if it returns
473 -2 (unrecognised command) continue with processing of application specific
476 Applications can also use SSL_CONF_cmd() to process command lines though the
477 utility function SSL_CONF_cmd_argv() is normally used instead. One way
478 to do this is to set the prefix to an appropriate value using
479 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
480 following argument to B<value> (which may be NULL).
482 In this case if the return value is positive then it is used to skip that
483 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
484 returned then B<cmd> is not recognised and application specific arguments
485 can be checked instead. If -3 is returned a required argument is missing
486 and an error is indicated. If 0 is returned some other error occurred and
487 this can be reported back to the user.
489 The function SSL_CONF_cmd_value_type() can be used by applications to
490 check for the existence of a command or to perform additional syntax
491 checking or translation of the command value. For example if the return
492 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
493 pathname to an absolute pathname.
497 Set supported signature algorithms:
499 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
501 There are various ways to select the supported protocols.
503 This set the minimum protocol version to TLSv1, and so disables SSLv3.
504 This is the recommended way to disable protocols.
506 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
508 The following also disables SSLv3:
510 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
512 The following will first enable all protocols, and then disable
514 If no protocol versions were disabled before this has the same effect as
515 "-SSLv3", but if some versions were disables this will re-enable them before
518 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
522 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
523 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
525 This also only enables TLSv1.2:
527 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
529 Disable TLS session tickets:
531 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
535 SSL_CONF_cmd(ctx, "Options", "Compression");
537 Set supported curves to P-256, P-384:
539 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
541 Set automatic support for any elliptic curve for key exchange:
543 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
547 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
548 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
549 returns the number of arguments processed. This is useful when processing
552 A return value of -2 means B<cmd> is not recognised.
554 A return value of -3 means B<cmd> is recognised and the command requires a
555 value but B<value> is NULL.
557 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
558 error occurred attempting to perform the operation: for example due to an
559 error in the syntax of B<value> in this case the error queue may provide
560 additional information.
562 SSL_CONF_finish() returns 1 for success and 0 for failure.
566 L<SSL_CONF_CTX_new(3)>,
567 L<SSL_CONF_CTX_set_flags(3)>,
568 L<SSL_CONF_CTX_set1_prefix(3)>,
569 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
570 L<SSL_CONF_cmd_argv(3)>,
571 L<SSL_CTX_set_options(3)>
575 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
577 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
578 for backwards compatibility.
580 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
581 OpenSSL passing a command which didn't take an argument would return
582 B<SSL_CONF_TYPE_UNKNOWN>.
584 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
588 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
590 Licensed under the OpenSSL license (the "License"). You may not use
591 this file except in compliance with the License. You can obtain a copy
592 in the file LICENSE in the source distribution or at
593 L<https://www.openssl.org/source/license.html>.