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<-min_protocol>, B<-max_protocol>
115 Sets the minimum and maximum supported protocol.
116 Currently supported protocol values are B<SSLv3>, B<TLSv1>,
117 B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
118 and B<None> for no limit.
119 If the either bound is not specified then only the other bound applies,
121 To restrict the supported protocol versions use these commands rather
122 than the deprecated alternative commands below.
124 =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>
126 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1 or TLSv1.2 by setting the
127 corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>, B<SSL_OP_NO_TLSv1_1>
128 and B<SSL_OP_NO_TLSv1_2> respectively.
129 These options are deprecated, instead use B<-min_protocol> and B<-max_protocol>.
133 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
137 Enables support for SSL/TLS compression, same as clearing
138 B<SSL_OP_NO_COMPRESSION>.
139 This command was introduced in OpenSSL 1.1.0.
140 As of OpenSSL 1.1.0, compression is off by default.
144 Disables support for SSL/TLS compression, same as setting
145 B<SSL_OP_NO_COMPRESSION>.
146 As of OpenSSL 1.1.0, compression is off by default.
150 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
154 Use server and not client preference order when determining which cipher suite,
155 signature algorithm or elliptic curve to use for an incoming connection.
156 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
158 =item B<-no_resumption_on_reneg>
160 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
162 =item B<-legacyrenegotiation>
164 permits the use of unsafe legacy renegotiation. Equivalent to setting
165 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
167 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
169 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
170 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
175 enables strict mode protocol handling. Equivalent to setting
176 B<SSL_CERT_FLAG_TLS_STRICT>.
180 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
182 Currently supported B<cmd> names for configuration files (i.e. when the
183 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
184 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
185 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
186 are also case insensitive.
188 Note: the command prefix (if set) alters the recognised B<cmd> values.
192 =item B<CipherString>
194 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
195 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
196 associated with B<cctx>.
200 Attempts to use the file B<value> as the certificate for the appropriate
201 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
202 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
203 structure is set. This option is only supported if certificate operations
208 Attempts to use the file B<value> as the private key for the appropriate
209 context. This option is only supported if certificate operations
210 are permitted. Note: if no B<PrivateKey> option is set then a private key is
211 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
213 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
215 These options indicate a file or directory used for building certificate
216 chains or verifying certificate chains. These options are only supported
217 if certificate operations are permitted.
219 =item B<ServerInfoFile>
221 Attempts to use the file B<value> in the "serverinfo" extension using the
222 function SSL_CTX_use_serverinfo_file.
224 =item B<DHParameters>
226 Attempts to use the file B<value> as the set of temporary DH parameters for
227 the appropriate context. This option is only supported if certificate
228 operations are permitted.
230 =item B<SignatureAlgorithms>
232 This sets the supported signature algorithms for TLS v1.2. For clients this
233 value is used directly for the supported signature algorithms extension. For
234 servers it is used to determine which signature algorithms to support.
236 The B<value> argument should be a colon separated list of signature algorithms
237 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
238 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
239 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
240 Note: algorithm and hash names are case sensitive.
242 If this option is not set then all signature algorithms supported by the
243 OpenSSL library are permissible.
245 =item B<ClientSignatureAlgorithms>
247 This sets the supported signature algorithms associated with client
248 authentication for TLS v1.2. For servers the value is used in the supported
249 signature algorithms field of a certificate request. For clients it is
250 used to determine which signature algorithm to with the client certificate.
252 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
253 the value set for B<SignatureAlgorithms> will be used instead.
257 This sets the supported elliptic curves. For clients the curves are
258 sent using the supported curves extension. For servers it is used
259 to determine which curve to use. This setting affects curves used for both
260 signatures and key exchange, if applicable.
262 The B<value> argument is a colon separated list of curves. The curve can be
263 either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
264 B<prime256v1>). Curve names are case sensitive.
268 This sets the minimum supported SSL, TLS or DTLS version.
270 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
271 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
272 The value B<None> will disable the limit.
276 This sets the maximum supported SSL, TLS or DTLS version.
278 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
279 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
280 The value B<None> will disable the limit.
284 This can be used to enable or disable certain versions of the SSL,
285 TLS or DTLS protocol.
287 The B<value> argument is a comma separated list of supported protocols
288 to enable or disable.
289 If a protocol is preceded by B<-> that version is disabled.
291 All protocol versions are enabled by default.
292 You need to disable at least one protocol version for this setting have any
294 Only enabling some protocol versions does not disable the other protocol
297 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
298 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
299 The special value B<ALL> refers to all supported versions.
301 This can't enable protocols that are disabled using B<MinProtocol>
302 or B<MaxProtocol>, but can disable protocols that are still allowed
305 The B<Protocol> command is fragile and deprecated; do not use it.
306 Use B<MinProtocol> and B<MaxProtocol> instead.
307 If you do use B<Protocol>, make sure that the resulting range of enabled
308 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
309 sure to also leave TLS 1.1 enabled.
313 The B<value> argument is a comma separated list of various flags to set.
314 If a flag string is preceded B<-> it is disabled.
315 See the L<SSL_CTX_set_options(3)> function for more details of
318 Each option is listed below. Where an operation is enabled by default
319 the B<-flag> syntax is needed to disable it.
321 B<SessionTicket>: session ticket support, enabled by default. Inverse of
322 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
325 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
326 of B<SSL_OP_NO_COMPRESSION>.
328 B<EmptyFragments>: use empty fragments as a countermeasure against a
329 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
330 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
332 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
334 B<DHSingle>: enable single use DH keys, set by default. Inverse of
335 B<SSL_OP_DH_SINGLE>. Only used by servers.
337 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
338 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
340 B<ServerPreference> use server and not client preference order when
341 determining which cipher suite, signature algorithm or elliptic curve
342 to use for an incoming connection. Equivalent to
343 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
345 B<NoResumptionOnRenegotiation> set
346 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
348 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
349 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
351 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
352 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
357 The B<value> argument is a comma separated list of flags to set.
359 B<Peer> enables peer verification: for clients only.
361 B<Request> requests but does not require a certificate from the client.
364 B<Require> requests and requires a certificate from the client: an error
365 occurs if the client does not present a certificate. Servers only.
367 B<Once> requests a certificate from a client only on the initial connection:
368 not when renegotiating. Servers only.
370 =item B<ClientCAFile>, B<ClientCAPath>
372 A file or directory of certificates in PEM format whose names are used as the
373 set of acceptable names for client CAs. Servers only. This option is only
374 supported if certificate operations are permitted.
378 =head1 SUPPORTED COMMAND TYPES
380 The function SSL_CONF_cmd_value_type() currently returns one of the following
385 =item B<SSL_CONF_TYPE_UNKNOWN>
387 The B<cmd> string is unrecognised, this return value can be use to flag
390 =item B<SSL_CONF_TYPE_STRING>
392 The value is a string without any specific structure.
394 =item B<SSL_CONF_TYPE_FILE>
396 The value is a file name.
398 =item B<SSL_CONF_TYPE_DIR>
400 The value is a directory name.
402 =item B<SSL_CONF_TYPE_NONE>
404 The value string is not used e.g. a command line option which doesn't take an
411 The order of operations is significant. This can be used to set either defaults
412 or values which cannot be overridden. For example if an application calls:
414 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
415 SSL_CONF_cmd(ctx, userparam, uservalue);
417 it will disable SSLv3 support by default but the user can override it. If
418 however the call sequence is:
420 SSL_CONF_cmd(ctx, userparam, uservalue);
421 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
423 SSLv3 is B<always> disabled and attempt to override this by the user are
426 By checking the return code of SSL_CTX_cmd() it is possible to query if a
427 given B<cmd> is recognised, this is useful is SSL_CTX_cmd() values are
428 mixed with additional application specific operations.
430 For example an application might call SSL_CTX_cmd() and if it returns
431 -2 (unrecognised command) continue with processing of application specific
434 Applications can also use SSL_CTX_cmd() to process command lines though the
435 utility function SSL_CTX_cmd_argv() is normally used instead. One way
436 to do this is to set the prefix to an appropriate value using
437 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
438 following argument to B<value> (which may be NULL).
440 In this case if the return value is positive then it is used to skip that
441 number of arguments as they have been processed by SSL_CTX_cmd(). If -2 is
442 returned then B<cmd> is not recognised and application specific arguments
443 can be checked instead. If -3 is returned a required argument is missing
444 and an error is indicated. If 0 is returned some other error occurred and
445 this can be reported back to the user.
447 The function SSL_CONF_cmd_value_type() can be used by applications to
448 check for the existence of a command or to perform additional syntax
449 checking or translation of the command value. For example if the return
450 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
451 pathname to an absolute pathname.
455 Set supported signature algorithms:
457 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
459 There are various ways to select the supported protocols.
461 This set the minimum protocol version to TLSv1, and so disables SSLv3.
462 This is the recommended way to disable protocols.
464 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
466 The following also disables SSLv3:
468 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
470 The following will first enable all protocols, and then disable
472 If no protocol versions were disabled before this has the same effect as
473 "-SSLv3", but if some versions were disables this will re-enable them before
476 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
480 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
481 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
483 This also only enables TLSv1.2:
485 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
487 Disable TLS session tickets:
489 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
493 SSL_CONF_cmd(ctx, "Options", "Compression");
495 Set supported curves to P-256, P-384:
497 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
499 Set automatic support for any elliptic curve for key exchange:
501 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
505 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
506 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
507 returns the number of arguments processed. This is useful when processing
510 A return value of -2 means B<cmd> is not recognised.
512 A return value of -3 means B<cmd> is recognised and the command requires a
513 value but B<value> is NULL.
515 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
516 error occurred attempting to perform the operation: for example due to an
517 error in the syntax of B<value> in this case the error queue may provide
518 additional information.
520 SSL_CONF_finish() returns 1 for success and 0 for failure.
524 L<SSL_CONF_CTX_new(3)>,
525 L<SSL_CONF_CTX_set_flags(3)>,
526 L<SSL_CONF_CTX_set1_prefix(3)>,
527 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
528 L<SSL_CONF_cmd_argv(3)>,
529 L<SSL_CTX_set_options(3)>
533 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
535 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
536 for backwards compatibility.
538 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
539 OpenSSL passing a command which didn't take an argument would return
540 B<SSL_CONF_TYPE_UNKNOWN>.
542 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
546 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
548 Licensed under the OpenSSL license (the "License"). You may not use
549 this file except in compliance with the License. You can obtain a copy
550 in the file LICENSE in the source distribution or at
551 L<https://www.openssl.org/source/license.html>.