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 supported groups. For clients, the groups are
79 sent using the supported groups extension. For servers, it is used
80 to determine which group to use. This setting affects groups used for both
81 signatures and key exchange, if applicable. It also affects the preferred
82 key_share sent by a client in a TLSv1.3 compatible connection.
84 The B<value> argument is a colon separated list of groups. The group can be
85 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
86 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
87 names are case sensitive. The list should be in order of preference with the
88 most preferred group first. The first listed group will be the one used for a
89 key_share by a TLSv1.3 client.
93 This is a synonym for the "-groups" command.
98 This sets the temporary curve used for ephemeral ECDH modes. Only used by
101 The B<value> argument is a curve name or the special value B<auto> which
102 picks an appropriate curve based on client and server preferences. The curve
103 can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name
104 (e.g B<prime256v1>). Curve names are case sensitive.
108 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
109 currently not performed unless a B<SSL> or B<SSL_CTX> structure is
110 associated with B<cctx>.
114 Attempts to use the file B<value> as the certificate for the appropriate
115 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
116 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
117 structure is set. This option is only supported if certificate operations
122 Attempts to use the file B<value> as the private key for the appropriate
123 context. This option is only supported if certificate operations
124 are permitted. Note: if no B<-key> option is set then a private key is
125 not loaded unless the flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
129 Attempts to use the file B<value> as the set of temporary DH parameters for
130 the appropriate context. This option is only supported if certificate
131 operations are permitted.
133 =item B<-record_padding>
135 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
136 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
137 B<value> must be >1 or <=16384.
139 =item B<-min_protocol>, B<-max_protocol>
141 Sets the minimum and maximum supported protocol.
142 Currently supported protocol values are B<SSLv3>, B<TLSv1>,
143 B<TLSv1.1>, B<TLSv1.2> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
144 and B<None> for no limit.
145 If the either bound is not specified then only the other bound applies,
147 To restrict the supported protocol versions use these commands rather
148 than the deprecated alternative commands below.
150 =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
152 Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by
153 setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
154 B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
155 respectively. These options are deprecated, instead use B<-min_protocol> and
160 Various bug workarounds are set, same as setting B<SSL_OP_ALL>.
164 Enables support for SSL/TLS compression, same as clearing
165 B<SSL_OP_NO_COMPRESSION>.
166 This command was introduced in OpenSSL 1.1.0.
167 As of OpenSSL 1.1.0, compression is off by default.
171 Disables support for SSL/TLS compression, same as setting
172 B<SSL_OP_NO_COMPRESSION>.
173 As of OpenSSL 1.1.0, compression is off by default.
177 Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>.
181 Use server and not client preference order when determining which cipher suite,
182 signature algorithm or elliptic curve to use for an incoming connection.
183 Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
185 =item B<-no_resumption_on_reneg>
187 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers.
189 =item B<-legacyrenegotiation>
191 permits the use of unsafe legacy renegotiation. Equivalent to setting
192 B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
194 =item B<-legacy_server_connect>, B<-no_legacy_server_connect>
196 permits or prohibits the use of unsafe legacy renegotiation for OpenSSL
197 clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>.
202 enables strict mode protocol handling. Equivalent to setting
203 B<SSL_CERT_FLAG_TLS_STRICT>.
207 =head1 SUPPORTED CONFIGURATION FILE COMMANDS
209 Currently supported B<cmd> names for configuration files (i.e. when the
210 flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file
211 B<cmd> names are case insensitive so B<signaturealgorithms> is recognised
212 as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names
213 are also case insensitive.
215 Note: the command prefix (if set) alters the recognised B<cmd> values.
219 =item B<CipherString>
221 Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is
222 currently not performed unless an B<SSL> or B<SSL_CTX> structure is
223 associated with B<cctx>.
227 Attempts to use the file B<value> as the certificate for the appropriate
228 context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX>
229 structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL>
230 structure is set. This option is only supported if certificate operations
235 Attempts to use the file B<value> as the private key for the appropriate
236 context. This option is only supported if certificate operations
237 are permitted. Note: if no B<PrivateKey> option is set then a private key is
238 not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set.
240 =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath>
242 These options indicate a file or directory used for building certificate
243 chains or verifying certificate chains. These options are only supported
244 if certificate operations are permitted.
246 =item B<RequestCAFile>
248 This option indicates a file containing a set of certificates in PEM form.
249 The subject names of the certificates are sent to the peer in the
250 B<certificate_authorities> extension for TLS 1.3 (in ClientHello or
251 CertificateRequest) or in a certificate request for previous versions or
254 =item B<ServerInfoFile>
256 Attempts to use the file B<value> in the "serverinfo" extension using the
257 function SSL_CTX_use_serverinfo_file.
259 =item B<DHParameters>
261 Attempts to use the file B<value> as the set of temporary DH parameters for
262 the appropriate context. This option is only supported if certificate
263 operations are permitted.
265 =item B<RecordPadding>
267 Attempts to pad TLS 1.3 records so that they are a multiple of B<value> in
268 length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the
269 B<value> must be >1 or <=16384.
271 =item B<SignatureAlgorithms>
273 This sets the supported signature algorithms for TLS v1.2. For clients this
274 value is used directly for the supported signature algorithms extension. For
275 servers it is used to determine which signature algorithms to support.
277 The B<value> argument should be a colon separated list of signature algorithms
278 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
279 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
280 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
281 Note: algorithm and hash names are case sensitive.
283 If this option is not set then all signature algorithms supported by the
284 OpenSSL library are permissible.
286 =item B<ClientSignatureAlgorithms>
288 This sets the supported signature algorithms associated with client
289 authentication for TLS v1.2. For servers the value is used in the supported
290 signature algorithms field of a certificate request. For clients it is
291 used to determine which signature algorithm to with the client certificate.
293 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
294 the value set for B<SignatureAlgorithms> will be used instead.
298 This sets the supported groups. For clients, the groups are
299 sent using the supported groups extension. For servers, it is used
300 to determine which group to use. This setting affects groups used for both
301 signatures and key exchange, if applicable. It also affects the preferred
302 key_share sent by a client in a TLSv1.3 compatible connection.
304 The B<value> argument is a colon separated list of groups. The group can be
305 either the B<NIST> name (e.g. B<P-256>), some other commonly used name where
306 applicable (e.g. B<X25519>) or an OpenSSL OID name (e.g B<prime256v1>). Group
307 names are case sensitive. The list should be in order of preference with the
308 most preferred group first. The first listed group will be the one used for a
309 key_share by a TLSv1.3 client.
313 This is a synonym for the "Groups" command.
317 This sets the minimum supported SSL, TLS or DTLS version.
319 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
320 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
321 The value B<None> will disable the limit.
325 This sets the maximum supported SSL, TLS or DTLS version.
327 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
328 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
329 The value B<None> will disable the limit.
333 This can be used to enable or disable certain versions of the SSL,
334 TLS or DTLS protocol.
336 The B<value> argument is a comma separated list of supported protocols
337 to enable or disable.
338 If a protocol is preceded by B<-> that version is disabled.
340 All protocol versions are enabled by default.
341 You need to disable at least one protocol version for this setting have any
343 Only enabling some protocol versions does not disable the other protocol
346 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
347 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
348 The special value B<ALL> refers to all supported versions.
350 This can't enable protocols that are disabled using B<MinProtocol>
351 or B<MaxProtocol>, but can disable protocols that are still allowed
354 The B<Protocol> command is fragile and deprecated; do not use it.
355 Use B<MinProtocol> and B<MaxProtocol> instead.
356 If you do use B<Protocol>, make sure that the resulting range of enabled
357 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
358 sure to also leave TLS 1.1 enabled.
362 The B<value> argument is a comma separated list of various flags to set.
363 If a flag string is preceded B<-> it is disabled.
364 See the L<SSL_CTX_set_options(3)> function for more details of
367 Each option is listed below. Where an operation is enabled by default
368 the B<-flag> syntax is needed to disable it.
370 B<SessionTicket>: session ticket support, enabled by default. Inverse of
371 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
374 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
375 of B<SSL_OP_NO_COMPRESSION>.
377 B<EmptyFragments>: use empty fragments as a countermeasure against a
378 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
379 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
381 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
383 B<DHSingle>: enable single use DH keys, set by default. Inverse of
384 B<SSL_OP_DH_SINGLE>. Only used by servers.
386 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
387 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
389 B<ServerPreference> use server and not client preference order when
390 determining which cipher suite, signature algorithm or elliptic curve
391 to use for an incoming connection. Equivalent to
392 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
394 B<NoResumptionOnRenegotiation> set
395 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
397 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
398 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
400 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
401 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
404 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
405 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
406 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
410 The B<value> argument is a comma separated list of flags to set.
412 B<Peer> enables peer verification: for clients only.
414 B<Request> requests but does not require a certificate from the client.
417 B<Require> requests and requires a certificate from the client: an error
418 occurs if the client does not present a certificate. Servers only.
420 B<Once> requests a certificate from a client only on the initial connection:
421 not when renegotiating. Servers only.
423 =item B<ClientCAFile>, B<ClientCAPath>
425 A file or directory of certificates in PEM format whose names are used as the
426 set of acceptable names for client CAs. Servers only. This option is only
427 supported if certificate operations are permitted.
431 =head1 SUPPORTED COMMAND TYPES
433 The function SSL_CONF_cmd_value_type() currently returns one of the following
438 =item B<SSL_CONF_TYPE_UNKNOWN>
440 The B<cmd> string is unrecognised, this return value can be use to flag
443 =item B<SSL_CONF_TYPE_STRING>
445 The value is a string without any specific structure.
447 =item B<SSL_CONF_TYPE_FILE>
449 The value is a file name.
451 =item B<SSL_CONF_TYPE_DIR>
453 The value is a directory name.
455 =item B<SSL_CONF_TYPE_NONE>
457 The value string is not used e.g. a command line option which doesn't take an
464 The order of operations is significant. This can be used to set either defaults
465 or values which cannot be overridden. For example if an application calls:
467 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
468 SSL_CONF_cmd(ctx, userparam, uservalue);
470 it will disable SSLv3 support by default but the user can override it. If
471 however the call sequence is:
473 SSL_CONF_cmd(ctx, userparam, uservalue);
474 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
476 SSLv3 is B<always> disabled and attempt to override this by the user are
479 By checking the return code of SSL_CONF_cmd() it is possible to query if a
480 given B<cmd> is recognised, this is useful is SSL_CONF_cmd() values are
481 mixed with additional application specific operations.
483 For example an application might call SSL_CONF_cmd() and if it returns
484 -2 (unrecognised command) continue with processing of application specific
487 Applications can also use SSL_CONF_cmd() to process command lines though the
488 utility function SSL_CONF_cmd_argv() is normally used instead. One way
489 to do this is to set the prefix to an appropriate value using
490 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
491 following argument to B<value> (which may be NULL).
493 In this case if the return value is positive then it is used to skip that
494 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
495 returned then B<cmd> is not recognised and application specific arguments
496 can be checked instead. If -3 is returned a required argument is missing
497 and an error is indicated. If 0 is returned some other error occurred and
498 this can be reported back to the user.
500 The function SSL_CONF_cmd_value_type() can be used by applications to
501 check for the existence of a command or to perform additional syntax
502 checking or translation of the command value. For example if the return
503 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
504 pathname to an absolute pathname.
508 Set supported signature algorithms:
510 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
512 There are various ways to select the supported protocols.
514 This set the minimum protocol version to TLSv1, and so disables SSLv3.
515 This is the recommended way to disable protocols.
517 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
519 The following also disables SSLv3:
521 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
523 The following will first enable all protocols, and then disable
525 If no protocol versions were disabled before this has the same effect as
526 "-SSLv3", but if some versions were disables this will re-enable them before
529 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
533 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
534 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
536 This also only enables TLSv1.2:
538 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
540 Disable TLS session tickets:
542 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
546 SSL_CONF_cmd(ctx, "Options", "Compression");
548 Set supported curves to P-256, P-384:
550 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
552 Set automatic support for any elliptic curve for key exchange:
554 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
558 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
559 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
560 returns the number of arguments processed. This is useful when processing
563 A return value of -2 means B<cmd> is not recognised.
565 A return value of -3 means B<cmd> is recognised and the command requires a
566 value but B<value> is NULL.
568 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
569 error occurred attempting to perform the operation: for example due to an
570 error in the syntax of B<value> in this case the error queue may provide
571 additional information.
573 SSL_CONF_finish() returns 1 for success and 0 for failure.
577 L<SSL_CONF_CTX_new(3)>,
578 L<SSL_CONF_CTX_set_flags(3)>,
579 L<SSL_CONF_CTX_set1_prefix(3)>,
580 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
581 L<SSL_CONF_cmd_argv(3)>,
582 L<SSL_CTX_set_options(3)>
586 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
588 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
589 for backwards compatibility.
591 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
592 OpenSSL passing a command which didn't take an argument would return
593 B<SSL_CONF_TYPE_UNKNOWN>.
595 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
599 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
601 Licensed under the OpenSSL license (the "License"). You may not use
602 this file except in compliance with the License. You can obtain a copy
603 in the file LICENSE in the source distribution or at
604 L<https://www.openssl.org/source/license.html>.