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 elliptic curves. For clients the curves are
68 sent using the supported curves extension. For servers it is used
69 to determine which curve to use. This setting affects curves used for both
70 signatures and key exchange, if applicable.
72 The B<value> argument is a colon separated list of curves. The curve can be
73 either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
74 B<prime256v1>). Curve names are case sensitive.
78 This sets the temporary curve used for ephemeral ECDH modes. Only used by
81 The B<value> argument is a curve name or the special value B<auto> which
82 picks an appropriate curve based on client and server preferences. The curve
83 can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
84 (e.g B<prime256v1>). Curve names are case sensitive.
88 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
89 currently not performed unless a B<SSL> or B<SSL_CTX> structure is
90 associated with B<cctx>.
94 Attempts to use the file B<value> as the certificate for the appropriate
95 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
96 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
97 structure is set. This option is only supported if certificate operations
102 Attempts to use the file B<value> as the private key for the appropriate
103 context. This option is only supported if certificate operations
104 are permitted. Note: if no B<-key> option is set then a private key is
105 not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
109 Attempts to use the file B<value> as the set of temporary DH parameters for
110 the appropriate context. This option is only supported if certificate
111 operations are permitted.
113 =item B<-record_padding>
115 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
116 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
117 B<value> must be >1 or <=16384.
119 =item B<-min_protocol>, B<-max_protocol>
121 Sets the minimum and maximum supported protocol.
122 Currently supported protocol values are B<SSLv3>, B<TLSv1>,
123 B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
124 and B<None> for no limit.
125 If the either bound is not specified then only the other bound applies,
127 To restrict the supported protocol versions use these commands rather
128 than the deprecated alternative commands below.
130 =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
132 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by
133 setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
134 B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
135 respectively. These options are deprecated, instead use B<-min_protocol> and
140 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
144 Enables support for SSL/TLS compression, same as clearing
145 B<SSL_OP_NO_COMPRESSION>.
146 This command was introduced in OpenSSL 1.1.0.
147 As of OpenSSL 1.1.0, compression is off by default.
151 Disables support for SSL/TLS compression, same as setting
152 B<SSL_OP_NO_COMPRESSION>.
153 As of OpenSSL 1.1.0, compression is off by default.
157 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
161 Use server and not client preference order when determining which cipher suite,
162 signature algorithm or elliptic curve to use for an incoming connection.
163 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
165 =item B<-no_resumption_on_reneg>
167 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
169 =item B<-legacyrenegotiation>
171 permits the use of unsafe legacy renegotiation. Equivalent to setting
172 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
174 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
176 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
177 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
182 enables strict mode protocol handling. Equivalent to setting
183 B<SSL_CERT_FLAG_TLS_STRICT>.
187 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
189 Currently supported B<cmd> names for configuration files (i.e. when the
190 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
191 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
192 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
193 are also case insensitive.
195 Note: the command prefix (if set) alters the recognised B<cmd> values.
199 =item B<CipherString>
201 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
202 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
203 associated with B<cctx>.
207 Attempts to use the file B<value> as the certificate for the appropriate
208 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
209 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
210 structure is set. This option is only supported if certificate operations
215 Attempts to use the file B<value> as the private key for the appropriate
216 context. This option is only supported if certificate operations
217 are permitted. Note: if no B<PrivateKey> option is set then a private key is
218 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
220 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
222 These options indicate a file or directory used for building certificate
223 chains or verifying certificate chains. These options are only supported
224 if certificate operations are permitted.
226 =item B<RequestCAFile>
228 This option indicates a file containing a set of certificates in PEM form.
229 The subject names of the certificates are sent to the peer in the
230 B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
231 CertificateRequest) or in a certificate request for previous versions or
234 =item B<ServerInfoFile>
236 Attempts to use the file B<value> in the "serverinfo" extension using the
237 function SSL_CTX_use_serverinfo_file.
239 =item B<DHParameters>
241 Attempts to use the file B<value> as the set of temporary DH parameters for
242 the appropriate context. This option is only supported if certificate
243 operations are permitted.
245 =item B<RecordPadding>
247 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
248 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
249 B<value> must be >1 or <=16384.
251 =item B<SignatureAlgorithms>
253 This sets the supported signature algorithms for TLS v1.2. For clients this
254 value is used directly for the supported signature algorithms extension. For
255 servers it is used to determine which signature algorithms to support.
257 The B<value> argument should be a colon separated list of signature algorithms
258 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
259 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
260 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
261 Note: algorithm and hash names are case sensitive.
263 If this option is not set then all signature algorithms supported by the
264 OpenSSL library are permissible.
266 =item B<ClientSignatureAlgorithms>
268 This sets the supported signature algorithms associated with client
269 authentication for TLS v1.2. For servers the value is used in the supported
270 signature algorithms field of a certificate request. For clients it is
271 used to determine which signature algorithm to with the client certificate.
273 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
274 the value set for B<SignatureAlgorithms> will be used instead.
278 This sets the supported elliptic curves. For clients the curves are
279 sent using the supported curves extension. For servers it is used
280 to determine which curve to use. This setting affects curves used for both
281 signatures and key exchange, if applicable.
283 The B<value> argument is a colon separated list of curves. The curve can be
284 either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
285 B<prime256v1>). Curve names are case sensitive.
289 This sets the minimum supported SSL, TLS or DTLS version.
291 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
292 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
293 The value B<None> will disable the limit.
297 This sets the maximum supported SSL, TLS or DTLS version.
299 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
300 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
301 The value B<None> will disable the limit.
305 This can be used to enable or disable certain versions of the SSL,
306 TLS or DTLS protocol.
308 The B<value> argument is a comma separated list of supported protocols
309 to enable or disable.
310 If a protocol is preceded by B<-> that version is disabled.
312 All protocol versions are enabled by default.
313 You need to disable at least one protocol version for this setting have any
315 Only enabling some protocol versions does not disable the other protocol
318 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
319 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
320 The special value B<ALL> refers to all supported versions.
322 This can't enable protocols that are disabled using B<MinProtocol>
323 or B<MaxProtocol>, but can disable protocols that are still allowed
326 The B<Protocol> command is fragile and deprecated; do not use it.
327 Use B<MinProtocol> and B<MaxProtocol> instead.
328 If you do use B<Protocol>, make sure that the resulting range of enabled
329 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
330 sure to also leave TLS 1.1 enabled.
334 The B<value> argument is a comma separated list of various flags to set.
335 If a flag string is preceded B<-> it is disabled.
336 See the L<SSL_CTX_set_options(3)> function for more details of
339 Each option is listed below. Where an operation is enabled by default
340 the B<-flag> syntax is needed to disable it.
342 B<SessionTicket>: session ticket support, enabled by default. Inverse of
343 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
346 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
347 of B<SSL_OP_NO_COMPRESSION>.
349 B<EmptyFragments>: use empty fragments as a countermeasure against a
350 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
351 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
353 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
355 B<DHSingle>: enable single use DH keys, set by default. Inverse of
356 B<SSL_OP_DH_SINGLE>. Only used by servers.
358 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
359 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
361 B<ServerPreference> use server and not client preference order when
362 determining which cipher suite, signature algorithm or elliptic curve
363 to use for an incoming connection. Equivalent to
364 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
366 B<NoResumptionOnRenegotiation> set
367 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
369 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
370 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
372 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
373 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
376 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
377 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
378 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
382 The B<value> argument is a comma separated list of flags to set.
384 B<Peer> enables peer verification: for clients only.
386 B<Request> requests but does not require a certificate from the client.
389 B<Require> requests and requires a certificate from the client: an error
390 occurs if the client does not present a certificate. Servers only.
392 B<Once> requests a certificate from a client only on the initial connection:
393 not when renegotiating. Servers only.
395 =item B<ClientCAFile>, B<ClientCAPath>
397 A file or directory of certificates in PEM format whose names are used as the
398 set of acceptable names for client CAs. Servers only. This option is only
399 supported if certificate operations are permitted.
403 =head1 SUPPORTED COMMAND TYPES
405 The function SSL_CONF_cmd_value_type() currently returns one of the following
410 =item B<SSL_CONF_TYPE_UNKNOWN>
412 The B<cmd> string is unrecognised, this return value can be use to flag
415 =item B<SSL_CONF_TYPE_STRING>
417 The value is a string without any specific structure.
419 =item B<SSL_CONF_TYPE_FILE>
421 The value is a file name.
423 =item B<SSL_CONF_TYPE_DIR>
425 The value is a directory name.
427 =item B<SSL_CONF_TYPE_NONE>
429 The value string is not used e.g. a command line option which doesn't take an
436 The order of operations is significant. This can be used to set either defaults
437 or values which cannot be overridden. For example if an application calls:
439 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
440 SSL_CONF_cmd(ctx, userparam, uservalue);
442 it will disable SSLv3 support by default but the user can override it. If
443 however the call sequence is:
445 SSL_CONF_cmd(ctx, userparam, uservalue);
446 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
448 SSLv3 is B<always> disabled and attempt to override this by the user are
451 By checking the return code of SSL_CONF_cmd() it is possible to query if a
452 given B<cmd> is recognised, this is useful is SSL_CONF_cmd() values are
453 mixed with additional application specific operations.
455 For example an application might call SSL_CONF_cmd() and if it returns
456 -2 (unrecognised command) continue with processing of application specific
459 Applications can also use SSL_CONF_cmd() to process command lines though the
460 utility function SSL_CONF_cmd_argv() is normally used instead. One way
461 to do this is to set the prefix to an appropriate value using
462 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
463 following argument to B<value> (which may be NULL).
465 In this case if the return value is positive then it is used to skip that
466 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
467 returned then B<cmd> is not recognised and application specific arguments
468 can be checked instead. If -3 is returned a required argument is missing
469 and an error is indicated. If 0 is returned some other error occurred and
470 this can be reported back to the user.
472 The function SSL_CONF_cmd_value_type() can be used by applications to
473 check for the existence of a command or to perform additional syntax
474 checking or translation of the command value. For example if the return
475 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
476 pathname to an absolute pathname.
480 Set supported signature algorithms:
482 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
484 There are various ways to select the supported protocols.
486 This set the minimum protocol version to TLSv1, and so disables SSLv3.
487 This is the recommended way to disable protocols.
489 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
491 The following also disables SSLv3:
493 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
495 The following will first enable all protocols, and then disable
497 If no protocol versions were disabled before this has the same effect as
498 "-SSLv3", but if some versions were disables this will re-enable them before
501 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
505 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
506 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
508 This also only enables TLSv1.2:
510 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
512 Disable TLS session tickets:
514 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
518 SSL_CONF_cmd(ctx, "Options", "Compression");
520 Set supported curves to P-256, P-384:
522 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
524 Set automatic support for any elliptic curve for key exchange:
526 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
530 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
531 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
532 returns the number of arguments processed. This is useful when processing
535 A return value of -2 means B<cmd> is not recognised.
537 A return value of -3 means B<cmd> is recognised and the command requires a
538 value but B<value> is NULL.
540 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
541 error occurred attempting to perform the operation: for example due to an
542 error in the syntax of B<value> in this case the error queue may provide
543 additional information.
545 SSL_CONF_finish() returns 1 for success and 0 for failure.
549 L<SSL_CONF_CTX_new(3)>,
550 L<SSL_CONF_CTX_set_flags(3)>,
551 L<SSL_CONF_CTX_set1_prefix(3)>,
552 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
553 L<SSL_CONF_cmd_argv(3)>,
554 L<SSL_CTX_set_options(3)>
558 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
560 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
561 for backwards compatibility.
563 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
564 OpenSSL passing a command which didn't take an argument would return
565 B<SSL_CONF_TYPE_UNKNOWN>.
567 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
571 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
573 Licensed under the OpenSSL license (the "License"). You may not use
574 this file except in compliance with the License. You can obtain a copy
575 in the file LICENSE in the source distribution or at
576 L<https://www.openssl.org/source/license.html>.