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_SSL3>, B<SSL_OP_NO_TLS1>, B<SSL_OP_NO_TLS1_1>
128 and B<SSL_OP_NO_TLS1_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.
266 =item B<ECDHParameters>
268 This sets the temporary curve used for ephemeral ECDH modes. Only used by
271 The B<value> argument is a curve name or the special value B<Automatic> which
272 picks an appropriate curve based on client and server preferences. The curve
273 can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
274 (e.g B<prime256v1>). Curve names are case sensitive.
278 This sets the minimum supported SSL, TLS or DTLS version.
280 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
281 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
282 The value B<None> will disable the limit.
286 This sets the maximum supported SSL, TLS or DTLS version.
288 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
289 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
290 The value B<None> will disable the limit.
294 This can be used to enable or disable certain versions of the SSL,
295 TLS or DTLS protocol.
297 The B<value> argument is a comma separated list of supported protocols
298 to enable or disable.
299 If a protocol is preceded by B<-> that version is disabled.
301 All protocol versions are enabled by default.
302 You need to disable at least one protocol version for this setting have any
304 Only enabling some protocol versions does not disable the other protocol
307 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
308 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
309 The special value B<ALL> refers to all supported versions.
311 This can't enable protocols that are disabled using B<MinProtocol>
312 or B<MaxProtocol>, but can disable protocols that are still allowed
315 The B<Protocol> command is fragile and deprecated; do not use it.
316 Use B<MinProtocol> and B<MaxProtocol> instead.
317 If you do use B<Protocol>, make sure that the resulting range of enabled
318 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
319 sure to also leave TLS 1.1 enabled.
323 The B<value> argument is a comma separated list of various flags to set.
324 If a flag string is preceded B<-> it is disabled.
325 See the L<SSL_CTX_set_options(3)> function for more details of
328 Each option is listed below. Where an operation is enabled by default
329 the B<-flag> syntax is needed to disable it.
331 B<SessionTicket>: session ticket support, enabled by default. Inverse of
332 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
335 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
336 of B<SSL_OP_NO_COMPRESSION>.
338 B<EmptyFragments>: use empty fragments as a countermeasure against a
339 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
340 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
342 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
344 B<DHSingle>: enable single use DH keys, set by default. Inverse of
345 B<SSL_OP_DH_SINGLE>. Only used by servers.
347 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
348 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
350 B<ServerPreference> use server and not client preference order when
351 determining which cipher suite, signature algorithm or elliptic curve
352 to use for an incoming connection. Equivalent to
353 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
355 B<NoResumptionOnRenegotiation> set
356 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
358 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
359 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
361 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
362 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
367 The B<value> argument is a comma separated list of flags to set.
369 B<Peer> enables peer verification: for clients only.
371 B<Request> requests but does not require a certificate from the client.
374 B<Require> requests and requires a certificate from the client: an error
375 occurs if the client does not present a certificate. Servers only.
377 B<Once> requests a certificate from a client only on the initial connection:
378 not when renegotiating. Servers only.
380 =item B<ClientCAFile>, B<ClientCAPath>
382 A file or directory of certificates in PEM format whose names are used as the
383 set of acceptable names for client CAs. Servers only. This option is only
384 supported if certificate operations are permitted.
388 =head1 SUPPORTED COMMAND TYPES
390 The function SSL_CONF_cmd_value_type() currently returns one of the following
395 =item B<SSL_CONF_TYPE_UNKNOWN>
397 The B<cmd> string is unrecognised, this return value can be use to flag
400 =item B<SSL_CONF_TYPE_STRING>
402 The value is a string without any specific structure.
404 =item B<SSL_CONF_TYPE_FILE>
406 The value is a file name.
408 =item B<SSL_CONF_TYPE_DIR>
410 The value is a directory name.
412 =item B<SSL_CONF_TYPE_NONE>
414 The value string is not used e.g. a command line option which doesn't take an
421 The order of operations is significant. This can be used to set either defaults
422 or values which cannot be overridden. For example if an application calls:
424 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
425 SSL_CONF_cmd(ctx, userparam, uservalue);
427 it will disable SSLv3 support by default but the user can override it. If
428 however the call sequence is:
430 SSL_CONF_cmd(ctx, userparam, uservalue);
431 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
433 SSLv3 is B<always> disabled and attempt to override this by the user are
436 By checking the return code of SSL_CTX_cmd() it is possible to query if a
437 given B<cmd> is recognised, this is useful is SSL_CTX_cmd() values are
438 mixed with additional application specific operations.
440 For example an application might call SSL_CTX_cmd() and if it returns
441 -2 (unrecognised command) continue with processing of application specific
444 Applications can also use SSL_CTX_cmd() to process command lines though the
445 utility function SSL_CTX_cmd_argv() is normally used instead. One way
446 to do this is to set the prefix to an appropriate value using
447 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
448 following argument to B<value> (which may be NULL).
450 In this case if the return value is positive then it is used to skip that
451 number of arguments as they have been processed by SSL_CTX_cmd(). If -2 is
452 returned then B<cmd> is not recognised and application specific arguments
453 can be checked instead. If -3 is returned a required argument is missing
454 and an error is indicated. If 0 is returned some other error occurred and
455 this can be reported back to the user.
457 The function SSL_CONF_cmd_value_type() can be used by applications to
458 check for the existence of a command or to perform additional syntax
459 checking or translation of the command value. For example if the return
460 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
461 pathname to an absolute pathname.
465 Set supported signature algorithms:
467 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
469 There are various ways to select the supported protocols.
471 This set the minimum protocol version to TLSv1, and so disables SSLv3.
472 This is the recommended way to disable protocols.
474 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
476 The following also disables SSLv3:
478 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
480 The following will first enable all protocols, and then disable
482 If no protocol versions were disabled before this has the same effect as
483 "-SSLv3", but if some versions were disables this will re-enable them before
486 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
490 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
491 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
493 This also only enables TLSv1.2:
495 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
497 Disable TLS session tickets:
499 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
503 SSL_CONF_cmd(ctx, "Options", "Compression");
505 Set supported curves to P-256, P-384:
507 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
509 Set automatic support for any elliptic curve for key exchange:
511 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
515 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
516 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
517 returns the number of arguments processed. This is useful when processing
520 A return value of -2 means B<cmd> is not recognised.
522 A return value of -3 means B<cmd> is recognised and the command requires a
523 value but B<value> is NULL.
525 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
526 error occurred attempting to perform the operation: for example due to an
527 error in the syntax of B<value> in this case the error queue may provide
528 additional information.
530 SSL_CONF_finish() returns 1 for success and 0 for failure.
534 L<SSL_CONF_CTX_new(3)>,
535 L<SSL_CONF_CTX_set_flags(3)>,
536 L<SSL_CONF_CTX_set1_prefix(3)>,
537 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
538 L<SSL_CONF_cmd_argv(3)>,
539 L<SSL_CTX_set_options(3)>
543 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
545 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
546 for backwards compatibility.
548 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
549 OpenSSL passing a command which didn't take an argument would return
550 B<SSL_CONF_TYPE_UNKNOWN>.
552 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
556 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
558 Licensed under the OpenSSL license (the "License"). You may not use
559 this file except in compliance with the License. You can obtain a copy
560 in the file LICENSE in the source distribution or at
561 L<https://www.openssl.org/source/license.html>.