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<ServerInfoFile>
222 Attempts to use the file B<value> in the "serverinfo" extension using the
223 function SSL_CTX_use_serverinfo_file.
225 =item B<DHParameters>
227 Attempts to use the file B<value> as the set of temporary DH parameters for
228 the appropriate context. This option is only supported if certificate
229 operations are permitted.
231 =item B<SignatureAlgorithms>
233 This sets the supported signature algorithms for TLS v1.2. For clients this
234 value is used directly for the supported signature algorithms extension. For
235 servers it is used to determine which signature algorithms to support.
237 The B<value> argument should be a colon separated list of signature algorithms
238 in order of decreasing preference of the form B<algorithm+hash>. B<algorithm>
239 is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm
240 OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>.
241 Note: algorithm and hash names are case sensitive.
243 If this option is not set then all signature algorithms supported by the
244 OpenSSL library are permissible.
246 =item B<ClientSignatureAlgorithms>
248 This sets the supported signature algorithms associated with client
249 authentication for TLS v1.2. For servers the value is used in the supported
250 signature algorithms field of a certificate request. For clients it is
251 used to determine which signature algorithm to with the client certificate.
253 The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then
254 the value set for B<SignatureAlgorithms> will be used instead.
258 This sets the supported elliptic curves. For clients the curves are
259 sent using the supported curves extension. For servers it is used
260 to determine which curve to use. This setting affects curves used for both
261 signatures and key exchange, if applicable.
263 The B<value> argument is a colon separated list of curves. The curve can be
264 either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g
265 B<prime256v1>). Curve names are case sensitive.
269 This sets the minimum supported SSL, TLS or DTLS version.
271 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
272 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
273 The value B<None> will disable the limit.
277 This sets the maximum 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 can be used to enable or disable certain versions of the SSL,
286 TLS or DTLS protocol.
288 The B<value> argument is a comma separated list of supported protocols
289 to enable or disable.
290 If a protocol is preceded by B<-> that version is disabled.
292 All protocol versions are enabled by default.
293 You need to disable at least one protocol version for this setting have any
295 Only enabling some protocol versions does not disable the other protocol
298 Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
299 B<TLSv1.2>, B<DTLSv1> and B<DTLSv1.2>.
300 The special value B<ALL> refers to all supported versions.
302 This can't enable protocols that are disabled using B<MinProtocol>
303 or B<MaxProtocol>, but can disable protocols that are still allowed
306 The B<Protocol> command is fragile and deprecated; do not use it.
307 Use B<MinProtocol> and B<MaxProtocol> instead.
308 If you do use B<Protocol>, make sure that the resulting range of enabled
309 protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make
310 sure to also leave TLS 1.1 enabled.
314 The B<value> argument is a comma separated list of various flags to set.
315 If a flag string is preceded B<-> it is disabled.
316 See the L<SSL_CTX_set_options(3)> function for more details of
319 Each option is listed below. Where an operation is enabled by default
320 the B<-flag> syntax is needed to disable it.
322 B<SessionTicket>: session ticket support, enabled by default. Inverse of
323 B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting
326 B<Compression>: SSL/TLS compression support, enabled by default. Inverse
327 of B<SSL_OP_NO_COMPRESSION>.
329 B<EmptyFragments>: use empty fragments as a countermeasure against a
330 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It
331 is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>.
333 B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>.
335 B<DHSingle>: enable single use DH keys, set by default. Inverse of
336 B<SSL_OP_DH_SINGLE>. Only used by servers.
338 B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of
339 B<SSL_OP_ECDH_SINGLE>. Only used by servers.
341 B<ServerPreference> use server and not client preference order when
342 determining which cipher suite, signature algorithm or elliptic curve
343 to use for an incoming connection. Equivalent to
344 B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers.
346 B<NoResumptionOnRenegotiation> set
347 B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers.
349 B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation.
350 Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>.
352 B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation
353 for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>.
356 B<EncryptThenMac>: use encrypt-then-mac extension, enabled by
357 default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is,
358 B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>.
362 The B<value> argument is a comma separated list of flags to set.
364 B<Peer> enables peer verification: for clients only.
366 B<Request> requests but does not require a certificate from the client.
369 B<Require> requests and requires a certificate from the client: an error
370 occurs if the client does not present a certificate. Servers only.
372 B<Once> requests a certificate from a client only on the initial connection:
373 not when renegotiating. Servers only.
375 =item B<ClientCAFile>, B<ClientCAPath>
377 A file or directory of certificates in PEM format whose names are used as the
378 set of acceptable names for client CAs. Servers only. This option is only
379 supported if certificate operations are permitted.
383 =head1 SUPPORTED COMMAND TYPES
385 The function SSL_CONF_cmd_value_type() currently returns one of the following
390 =item B<SSL_CONF_TYPE_UNKNOWN>
392 The B<cmd> string is unrecognised, this return value can be use to flag
395 =item B<SSL_CONF_TYPE_STRING>
397 The value is a string without any specific structure.
399 =item B<SSL_CONF_TYPE_FILE>
401 The value is a file name.
403 =item B<SSL_CONF_TYPE_DIR>
405 The value is a directory name.
407 =item B<SSL_CONF_TYPE_NONE>
409 The value string is not used e.g. a command line option which doesn't take an
416 The order of operations is significant. This can be used to set either defaults
417 or values which cannot be overridden. For example if an application calls:
419 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
420 SSL_CONF_cmd(ctx, userparam, uservalue);
422 it will disable SSLv3 support by default but the user can override it. If
423 however the call sequence is:
425 SSL_CONF_cmd(ctx, userparam, uservalue);
426 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
428 SSLv3 is B<always> disabled and attempt to override this by the user are
431 By checking the return code of SSL_CONF_cmd() it is possible to query if a
432 given B<cmd> is recognised, this is useful is SSL_CONF_cmd() values are
433 mixed with additional application specific operations.
435 For example an application might call SSL_CONF_cmd() and if it returns
436 -2 (unrecognised command) continue with processing of application specific
439 Applications can also use SSL_CONF_cmd() to process command lines though the
440 utility function SSL_CONF_cmd_argv() is normally used instead. One way
441 to do this is to set the prefix to an appropriate value using
442 SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the
443 following argument to B<value> (which may be NULL).
445 In this case if the return value is positive then it is used to skip that
446 number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is
447 returned then B<cmd> is not recognised and application specific arguments
448 can be checked instead. If -3 is returned a required argument is missing
449 and an error is indicated. If 0 is returned some other error occurred and
450 this can be reported back to the user.
452 The function SSL_CONF_cmd_value_type() can be used by applications to
453 check for the existence of a command or to perform additional syntax
454 checking or translation of the command value. For example if the return
455 value is B<SSL_CONF_TYPE_FILE> an application could translate a relative
456 pathname to an absolute pathname.
460 Set supported signature algorithms:
462 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
464 There are various ways to select the supported protocols.
466 This set the minimum protocol version to TLSv1, and so disables SSLv3.
467 This is the recommended way to disable protocols.
469 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1");
471 The following also disables SSLv3:
473 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
475 The following will first enable all protocols, and then disable
477 If no protocol versions were disabled before this has the same effect as
478 "-SSLv3", but if some versions were disables this will re-enable them before
481 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3");
485 SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2");
486 SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2");
488 This also only enables TLSv1.2:
490 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
492 Disable TLS session tickets:
494 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
498 SSL_CONF_cmd(ctx, "Options", "Compression");
500 Set supported curves to P-256, P-384:
502 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
504 Set automatic support for any elliptic curve for key exchange:
506 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
510 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is
511 B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it
512 returns the number of arguments processed. This is useful when processing
515 A return value of -2 means B<cmd> is not recognised.
517 A return value of -3 means B<cmd> is recognised and the command requires a
518 value but B<value> is NULL.
520 A return code of 0 indicates that both B<cmd> and B<value> are valid but an
521 error occurred attempting to perform the operation: for example due to an
522 error in the syntax of B<value> in this case the error queue may provide
523 additional information.
525 SSL_CONF_finish() returns 1 for success and 0 for failure.
529 L<SSL_CONF_CTX_new(3)>,
530 L<SSL_CONF_CTX_set_flags(3)>,
531 L<SSL_CONF_CTX_set1_prefix(3)>,
532 L<SSL_CONF_CTX_set_ssl_ctx(3)>,
533 L<SSL_CONF_cmd_argv(3)>,
534 L<SSL_CTX_set_options(3)>
538 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
540 B<SSL_OP_NO_SSL2> doesn't have effect since 1.1.0, but the macro is retained
541 for backwards compatibility.
543 B<SSL_CONF_TYPE_NONE> was first added to OpenSSL 1.1.0. In earlier versions of
544 OpenSSL passing a command which didn't take an argument would return
545 B<SSL_CONF_TYPE_UNKNOWN>.
547 B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0.
551 Copyright 2012-2016 The OpenSSL Project Authors. All Rights Reserved.
553 Licensed under the OpenSSL license (the "License"). You may not use
554 this file except in compliance with the License. You can obtain a copy
555 in the file LICENSE in the source distribution or at
556 L<https://www.openssl.org/source/license.html>.