5 SSL_CONF_cmd - send configuration command
9 #include <openssl/ssl.h>
11 int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value);
12 int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd);
13 int SSL_CONF_finish(SSL_CONF_CTX *cctx);
17 The function SSL_CONF_cmd() performs configuration operation B<cmd> with
18 optional parameter B<value> on B<ctx>. Its purpose is to simplify application
19 configuration of B<SSL_CTX> or B<SSL> structures by providing a common
20 framework for command line options or configuration files.
22 SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to.
24 The function SSL_CONF_finish() must be called after all configuration
25 operations have been completed. It is used to finalise any operations
26 or to process defaults.
28 =head1 SUPPORTED COMMAND LINE COMMANDS
30 Currently supported B<cmd> names for command lines (i.e. when the
31 flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names
32 are case sensitive. Unless otherwise stated commands can be used by
33 both clients and servers and the B<value> parameter is not used. The default
34 prefix for command line commands is B<-> and that is reflected below.
40 This sets the supported signature algorithms for TLS v1.2. For clients this
41 value is used directly for the supported signature algorithms extension. For
42 servers it is used to determine which signature algorithms to support.
44 The B<value> argument should be a colon separated list of signature algorithms
45 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
46 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
47 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
48 Note: algorithm and hash names are case sensitive.
50 If this option is not set then all signature algorithms supported by the
51 OpenSSL library are permissible.
53 =item B<-client_sigalgs>
55 This sets the supported signature algorithms associated with client
56 authentication for TLS v1.2. For servers the value is used in the supported
57 signature algorithms field of a certificate request. For clients it is
58 used to determine which signature algorithm to with the client certificate.
59 If a server does not request a certificate this option has no effect.
61 The syntax of B<value> is identical to B<-sigalgs>. If not set then
62 the value set for B<-sigalgs> will be used instead.
66 This sets the supported elliptic curves. For clients the curves are
67 sent using the supported curves extension. For servers it is used
68 to determine which curve to use. This setting affects curves used for both
69 signatures and key exchange, if applicable.
71 The B<value> argument is a colon separated list of curves. The curve can be
72 either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
73 B<prime256v1>). Curve names are case sensitive.
77 This sets the temporary curve used for ephemeral ECDH modes. Only used by
80 The B<value> argument is a curve name or the special value B<auto> which
81 picks an appropriate curve based on client and server preferences. The curve
82 can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
83 (e.g B<prime256v1>). Curve names are case sensitive.
87 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
88 currently not performed unless a B<SSL> or B<SSL_CTX> structure is
89 associated with B<cctx>.
93 Attempts to use the file B<value> as the certificate for the appropriate
94 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
95 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
96 structure is set. This option is only supported if certificate operations
101 Attempts to use the file B<value> as the private key for the appropriate
102 context. This option is only supported if certificate operations
103 are permitted. Note: if no B<-key> option is set then a private key is
104 not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
108 Attempts to use the file B<value> as the set of temporary DH parameters for
109 the appropriate context. This option is only supported if certificate
110 operations are permitted.
112 =item B<-min_protocol>, B<-max_protocol>
114 Sets the minimum and maximum supported protocol.
115 Currently supported protocol values are B<SSLv3>, B<TLSv1>,
116 B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
117 and B<None> for no limit.
118 If the either bound is not specified then only the other bound applies,
120 To restrict the supported protocol versions use these commands rather
121 than the deprecated alternative commands below.
123 =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>
125 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1 or TLSv1.2 by setting the
126 corresponding options B<SSL_OP_NO_SSL3>, B<SSL_OP_NO_TLS1>, B<SSL_OP_NO_TLS1_1>
127 and B<SSL_OP_NO_TLS1_2> respectively.
128 These options are deprecated, instead use B<-min_protocol> and B<-max_protocol>.
132 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
136 Enables support for SSL/TLS compression, same as clearing
137 B<SSL_OP_NO_COMPRESSION>.
138 This command was introduced in OpenSSL 1.1.0.
139 As of OpenSSL 1.1.0, compression is off by default.
143 Disables support for SSL/TLS compression, same as setting
144 B<SSL_OP_NO_COMPRESSION>.
145 As of OpenSSL 1.1.0, compression is off by default.
149 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
153 Use server and not client preference order when determining which cipher suite,
154 signature algorithm or elliptic curve to use for an incoming connection.
155 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
157 =item B<-no_resumption_on_reneg>
159 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
161 =item B<-legacyrenegotiation>
163 permits the use of unsafe legacy renegotiation. Equivalent to setting
164 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
166 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
168 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
169 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
174 enables strict mode protocol handling. Equivalent to setting
175 B<SSL_CERT_FLAG_TLS_STRICT>.
179 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
181 Currently supported B<cmd> names for configuration files (i.e. when the
182 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
183 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
184 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
185 are also case insensitive.
187 Note: the command prefix (if set) alters the recognised B<cmd> values.
191 =item B<CipherString>
193 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
194 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
195 associated with B<cctx>.
199 Attempts to use the file B<value> as the certificate for the appropriate
200 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
201 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
202 structure is set. This option is only supported if certificate operations
207 Attempts to use the file B<value> as the private key for the appropriate
208 context. This option is only supported if certificate operations
209 are permitted. Note: if no B<PrivateKey> option is set then a private key is
210 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
212 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
214 These options indicate a file or directory used for building certificate
215 chains or verifying certificate chains. These options are only supported
216 if certificate operations are permitted.
218 =item B<ServerInfoFile>
220 Attempts to use the file B<value> in the "serverinfo" extension using the
221 function SSL_CTX_use_serverinfo_file.
223 =item B<DHParameters>
225 Attempts to use the file B<value> as the set of temporary DH parameters for
226 the appropriate context. This option is only supported if certificate
227 operations are permitted.
229 =item B<SignatureAlgorithms>
231 This sets the supported signature algorithms for TLS v1.2. For clients this
232 value is used directly for the supported signature algorithms extension. For
233 servers it is used to determine which signature algorithms to support.
235 The B<value> argument should be a colon separated list of signature algorithms
236 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
237 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
238 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
239 Note: algorithm and hash names are case sensitive.
241 If this option is not set then all signature algorithms supported by the
242 OpenSSL library are permissible.
244 =item B<ClientSignatureAlgorithms>
246 This sets the supported signature algorithms associated with client
247 authentication for TLS v1.2. For servers the value is used in the supported
248 signature algorithms field of a certificate request. For clients it is
249 used to determine which signature algorithm to with the client certificate.
251 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
252 the value set for B<SignatureAlgorithms> will be used instead.
256 This sets the supported elliptic curves. For clients the curves are
257 sent using the supported curves extension. For servers it is used
258 to determine which curve to use. This setting affects curves used for both
259 signatures and key exchange, if applicable.
261 The B<value> argument is a colon separated list of curves. The curve can be
262 either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
263 B<prime256v1>). Curve names are case sensitive.
265 =item B<ECDHParameters>
267 This sets the temporary curve used for ephemeral ECDH modes. Only used by
270 The B<value> argument is a curve name or the special value B<Automatic> which
271 picks an appropriate curve based on client and server preferences. The curve
272 can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
273 (e.g B<prime256v1>). Curve names are case sensitive.
277 This sets the minimum supported SSL, TLS or DTLS version.
279 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
280 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
281 The value B<None> will disable the limit.
285 This sets the maximum supported SSL, TLS or DTLS version.
287 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
288 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
289 The value B<None> will disable the limit.
293 This can be used to enable or disable certain versions of the SSL,
294 TLS or DTLS protocol.
296 The B<value> argument is a comma separated list of supported protocols
297 to enable or disable.
298 If a protocol is preceded by B<-> that version is disabled.
300 All protocol versions are enabled by default.
301 You need to disable at least one protocol version for this setting have any
303 Only enabling some protocol versions does not disable the other protocol
306 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
307 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
308 The special value B<ALL> refers to all supported versions.
310 This can't enable protocols that are disabled using B<MinProtocol>
311 or B<MaxProtocol>, but can disable protocols that are still allowed
314 The B<Protocol> command is fragile and deprecated; do not use it.
315 Use B<MinProtocol> and B<MaxProtocol> instead.
316 If you do use B<Protocol>, make sure that the resulting range of enabled
317 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
318 sure to also leave TLS 1.1 enabled.
322 The B<value> argument is a comma separated list of various flags to set.
323 If a flag string is preceded B<-> it is disabled.
324 See the L<SSL_CTX_set_options(3)> function for more details of
327 Each option is listed below. Where an operation is enabled by default
328 the B<-flag> syntax is needed to disable it.
330 B<SessionTicket>: session ticket support, enabled by default. Inverse of
331 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
334 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
335 of B<SSL_OP_NO_COMPRESSION>.
337 B<EmptyFragments>: use empty fragments as a countermeasure against a
338 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
339 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
341 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
343 B<DHSingle>: enable single use DH keys, set by default. Inverse of
344 B<SSL_OP_DH_SINGLE>. Only used by servers.
346 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
347 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
349 B<ServerPreference> use server and not client preference order when
350 determining which cipher suite, signature algorithm or elliptic curve
351 to use for an incoming connection. Equivalent to
352 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
354 B<NoResumptionOnRenegotiation> set
355 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
357 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
358 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
360 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
361 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
366 The B<value> argument is a comma separated list of flags to set.
368 B<Peer> enables peer verification: for clients only.
370 B<Request> requests but does not require a certificate from the client.
373 B<Require> requests and requires a certificate from the client: an error
374 occurs if the client does not present a certificate. Servers only.
376 B<Once> requests a certificate from a client only on the initial connection:
377 not when renegotiating. Servers only.
379 =item B<ClientCAFile>, B<ClientCAPath>
381 A file or directory of certificates in PEM format whose names are used as the
382 set of acceptable names for client CAs. Servers only. This option is only
383 supported if certificate operations are permitted.
387 =head1 SUPPORTED COMMAND TYPES
389 The function SSL_CONF_cmd_value_type() currently returns one of the following
394 =item B<SSL_CONF_TYPE_UNKNOWN>
396 The B<cmd> string is unrecognised, this return value can be use to flag
399 =item B<SSL_CONF_TYPE_STRING>
401 The value is a string without any specific structure.
403 =item B<SSL_CONF_TYPE_FILE>
405 The value is a file name.
407 =item B<SSL_CONF_TYPE_DIR>
409 The value is a directory name.
411 =item B<SSL_CONF_TYPE_NONE>
413 The value string is not used e.g. a command line option which doesn't take an
420 The order of operations is significant. This can be used to set either defaults
421 or values which cannot be overridden. For example if an application calls:
423 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
424 SSL_CONF_cmd(ctx, userparam, uservalue);
426 it will disable SSLv3 support by default but the user can override it. If
427 however the call sequence is:
429 SSL_CONF_cmd(ctx, userparam, uservalue);
430 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
432 SSLv3 is B<always> disabled and attempt to override this by the user are
435 By checking the return code of SSL_CTX_cmd() it is possible to query if a
436 given B<cmd> is recognised, this is useful is SSL_CTX_cmd() values are
437 mixed with additional application specific operations.
439 For example an application might call SSL_CTX_cmd() and if it returns
440 -2 (unrecognised command) continue with processing of application specific
443 Applications can also use SSL_CTX_cmd() to process command lines though the
444 utility function SSL_CTX_cmd_argv() is normally used instead. One way
445 to do this is to set the prefix to an appropriate value using
446 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
447 following argument to B<value> (which may be NULL).
449 In this case if the return value is positive then it is used to skip that
450 number of arguments as they have been processed by SSL_CTX_cmd(). If -2 is
451 returned then B<cmd> is not recognised and application specific arguments
452 can be checked instead. If -3 is returned a required argument is missing
453 and an error is indicated. If 0 is returned some other error occurred and
454 this can be reported back to the user.
456 The function SSL_CONF_cmd_value_type() can be used by applications to
457 check for the existence of a command or to perform additional syntax
458 checking or translation of the command value. For example if the return
459 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
460 pathname to an absolute pathname.
464 Set supported signature algorithms:
466 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
468 There are various ways to select the supported protocols.
470 This set the minimum protocol version to TLSv1, and so disables SSLv3.
471 This is the recommended way to disable protocols.
473 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
475 The following also disables SSLv3:
477 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
479 The following will first enable all protocols, and then disable
481 If no protocol versions were disabled before this has the same effect as
482 "-SSLv3", but if some versions were disables this will re-enable them before
485 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
489 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
490 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
492 This also only enables TLSv1.2:
494 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
496 Disable TLS session tickets:
498 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
502 SSL_CONF_cmd(ctx, "Options", "Compression");
504 Set supported curves to P-256, P-384:
506 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
508 Set automatic support for any elliptic curve for key exchange:
510 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
514 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
515 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
516 returns the number of arguments processed. This is useful when processing
519 A return value of -2 means B<cmd> is not recognised.
521 A return value of -3 means B<cmd> is recognised and the command requires a
522 value but B<value> is NULL.
524 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
525 error occurred attempting to perform the operation: for example due to an
526 error in the syntax of B<value> in this case the error queue may provide
527 additional information.
529 SSL_CONF_finish() returns 1 for success and 0 for failure.
533 L<SSL_CONF_CTX_new(3)>,
534 L<SSL_CONF_CTX_set_flags(3)>,
535 L<SSL_CONF_CTX_set1_prefix(3)>,
536 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
537 L<SSL_CONF_cmd_argv(3)>,
538 L<SSL_CTX_set_options(3)>
542 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
544 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
545 for backwards compatibility.
547 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
548 OpenSSL passing a command which didn't take an argument would return
549 B<SSL_CONF_TYPE_UNKNOWN>.
551 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
557 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
559 Licensed under the OpenSSL license (the "License"). You may not use
560 this file except in compliance with the License. You can obtain a copy
561 in the file LICENSE in the source distribution or at
562 L<https://www.openssl.org/source/license.html>.