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>, B<-no_tls1_3>
126 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by
127 setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
128 B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
129 respectively. These options are deprecated, instead use B<-min_protocol> and
134 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
138 Enables support for SSL/TLS compression, same as clearing
139 B<SSL_OP_NO_COMPRESSION>.
140 This command was introduced in OpenSSL 1.1.0.
141 As of OpenSSL 1.1.0, compression is off by default.
145 Disables support for SSL/TLS compression, same as setting
146 B<SSL_OP_NO_COMPRESSION>.
147 As of OpenSSL 1.1.0, compression is off by default.
151 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
155 Use server and not client preference order when determining which cipher suite,
156 signature algorithm or elliptic curve to use for an incoming connection.
157 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
159 =item B<-no_resumption_on_reneg>
161 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
163 =item B<-legacyrenegotiation>
165 permits the use of unsafe legacy renegotiation. Equivalent to setting
166 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
168 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
170 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
171 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
176 enables strict mode protocol handling. Equivalent to setting
177 B<SSL_CERT_FLAG_TLS_STRICT>.
181 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
183 Currently supported B<cmd> names for configuration files (i.e. when the
184 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
185 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
186 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
187 are also case insensitive.
189 Note: the command prefix (if set) alters the recognised B<cmd> values.
193 =item B<CipherString>
195 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
196 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
197 associated with B<cctx>.
201 Attempts to use the file B<value> as the certificate for the appropriate
202 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
203 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
204 structure is set. This option is only supported if certificate operations
209 Attempts to use the file B<value> as the private key for the appropriate
210 context. This option is only supported if certificate operations
211 are permitted. Note: if no B<PrivateKey> option is set then a private key is
212 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
214 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
216 These options indicate a file or directory used for building certificate
217 chains or verifying certificate chains. These options are only supported
218 if certificate operations are permitted.
220 =item B<RequestCAFile>
222 This option indicates a file containing a set of certificates in PEM form.
223 The subject names of the certificates are sent to the peer in the
224 B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
225 CertificateRequest) or in a certificate request for previous versions or
228 =item B<ServerInfoFile>
230 Attempts to use the file B<value> in the "serverinfo" extension using the
231 function SSL_CTX_use_serverinfo_file.
233 =item B<DHParameters>
235 Attempts to use the file B<value> as the set of temporary DH parameters for
236 the appropriate context. This option is only supported if certificate
237 operations are permitted.
239 =item B<SignatureAlgorithms>
241 This sets the supported signature algorithms for TLS v1.2. For clients this
242 value is used directly for the supported signature algorithms extension. For
243 servers it is used to determine which signature algorithms to support.
245 The B<value> argument should be a colon separated list of signature algorithms
246 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
247 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
248 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
249 Note: algorithm and hash names are case sensitive.
251 If this option is not set then all signature algorithms supported by the
252 OpenSSL library are permissible.
254 =item B<ClientSignatureAlgorithms>
256 This sets the supported signature algorithms associated with client
257 authentication for TLS v1.2. For servers the value is used in the supported
258 signature algorithms field of a certificate request. For clients it is
259 used to determine which signature algorithm to with the client certificate.
261 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
262 the value set for B<SignatureAlgorithms> will be used instead.
266 This sets the supported elliptic curves. For clients the curves are
267 sent using the supported curves extension. For servers it is used
268 to determine which curve to use. This setting affects curves used for both
269 signatures and key exchange, if applicable.
271 The B<value> argument is a colon separated list of curves. The curve can be
272 either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
273 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>.
364 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
365 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
366 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
370 The B<value> argument is a comma separated list of flags to set.
372 B<Peer> enables peer verification: for clients only.
374 B<Request> requests but does not require a certificate from the client.
377 B<Require> requests and requires a certificate from the client: an error
378 occurs if the client does not present a certificate. Servers only.
380 B<Once> requests a certificate from a client only on the initial connection:
381 not when renegotiating. Servers only.
383 =item B<ClientCAFile>, B<ClientCAPath>
385 A file or directory of certificates in PEM format whose names are used as the
386 set of acceptable names for client CAs. Servers only. This option is only
387 supported if certificate operations are permitted.
391 =head1 SUPPORTED COMMAND TYPES
393 The function SSL_CONF_cmd_value_type() currently returns one of the following
398 =item B<SSL_CONF_TYPE_UNKNOWN>
400 The B<cmd> string is unrecognised, this return value can be use to flag
403 =item B<SSL_CONF_TYPE_STRING>
405 The value is a string without any specific structure.
407 =item B<SSL_CONF_TYPE_FILE>
409 The value is a file name.
411 =item B<SSL_CONF_TYPE_DIR>
413 The value is a directory name.
415 =item B<SSL_CONF_TYPE_NONE>
417 The value string is not used e.g. a command line option which doesn't take an
424 The order of operations is significant. This can be used to set either defaults
425 or values which cannot be overridden. For example if an application calls:
427 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
428 SSL_CONF_cmd(ctx, userparam, uservalue);
430 it will disable SSLv3 support by default but the user can override it. If
431 however the call sequence is:
433 SSL_CONF_cmd(ctx, userparam, uservalue);
434 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
436 SSLv3 is B<always> disabled and attempt to override this by the user are
439 By checking the return code of SSL_CONF_cmd() it is possible to query if a
440 given B<cmd> is recognised, this is useful is SSL_CONF_cmd() values are
441 mixed with additional application specific operations.
443 For example an application might call SSL_CONF_cmd() and if it returns
444 -2 (unrecognised command) continue with processing of application specific
447 Applications can also use SSL_CONF_cmd() to process command lines though the
448 utility function SSL_CONF_cmd_argv() is normally used instead. One way
449 to do this is to set the prefix to an appropriate value using
450 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
451 following argument to B<value> (which may be NULL).
453 In this case if the return value is positive then it is used to skip that
454 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
455 returned then B<cmd> is not recognised and application specific arguments
456 can be checked instead. If -3 is returned a required argument is missing
457 and an error is indicated. If 0 is returned some other error occurred and
458 this can be reported back to the user.
460 The function SSL_CONF_cmd_value_type() can be used by applications to
461 check for the existence of a command or to perform additional syntax
462 checking or translation of the command value. For example if the return
463 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
464 pathname to an absolute pathname.
468 Set supported signature algorithms:
470 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
472 There are various ways to select the supported protocols.
474 This set the minimum protocol version to TLSv1, and so disables SSLv3.
475 This is the recommended way to disable protocols.
477 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
479 The following also disables SSLv3:
481 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
483 The following will first enable all protocols, and then disable
485 If no protocol versions were disabled before this has the same effect as
486 "-SSLv3", but if some versions were disables this will re-enable them before
489 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
493 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
494 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
496 This also only enables TLSv1.2:
498 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
500 Disable TLS session tickets:
502 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
506 SSL_CONF_cmd(ctx, "Options", "Compression");
508 Set supported curves to P-256, P-384:
510 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
512 Set automatic support for any elliptic curve for key exchange:
514 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
518 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
519 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
520 returns the number of arguments processed. This is useful when processing
523 A return value of -2 means B<cmd> is not recognised.
525 A return value of -3 means B<cmd> is recognised and the command requires a
526 value but B<value> is NULL.
528 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
529 error occurred attempting to perform the operation: for example due to an
530 error in the syntax of B<value> in this case the error queue may provide
531 additional information.
533 SSL_CONF_finish() returns 1 for success and 0 for failure.
537 L<SSL_CONF_CTX_new(3)>,
538 L<SSL_CONF_CTX_set_flags(3)>,
539 L<SSL_CONF_CTX_set1_prefix(3)>,
540 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
541 L<SSL_CONF_cmd_argv(3)>,
542 L<SSL_CTX_set_options(3)>
546 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
548 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
549 for backwards compatibility.
551 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
552 OpenSSL passing a command which didn't take an argument would return
553 B<SSL_CONF_TYPE_UNKNOWN>.
555 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
559 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
561 Licensed under the OpenSSL license (the "License"). You may not use
562 this file except in compliance with the License. You can obtain a copy
563 in the file LICENSE in the source distribution or at
564 L<https://www.openssl.org/source/license.html>.