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1 | =pod | |
2 | ||
3 | =head1 NAME | |
4 | ||
5 | SSL_CONF_cmd_value_type, | |
6 | SSL_CONF_cmd - send configuration command | |
7 | ||
8 | =head1 SYNOPSIS | |
9 | ||
10 | #include <openssl/ssl.h> | |
11 | ||
12 | int SSL_CONF_cmd(SSL_CONF_CTX *ctx, const char *option, const char *value); | |
13 | int SSL_CONF_cmd_value_type(SSL_CONF_CTX *ctx, const char *option); | |
14 | ||
15 | =head1 DESCRIPTION | |
16 | ||
17 | The function SSL_CONF_cmd() performs configuration operation B<option> with | |
18 | optional parameter B<value> on B<ctx>. Its purpose is to simplify application | |
19 | configuration of B<SSL_CTX> or B<SSL> structures by providing a common | |
20 | framework for command line options or configuration files. | |
21 | ||
22 | SSL_CONF_cmd_value_type() returns the type of value that B<option> refers to. | |
23 | ||
24 | =head1 SUPPORTED COMMAND LINE COMMANDS | |
25 | ||
26 | Currently supported B<option> names for command lines (i.e. when the | |
27 | flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<option> names | |
28 | are case sensitive. Unless otherwise stated commands can be used by | |
29 | both clients and servers and the B<value> parameter is not used. The default | |
30 | prefix for command line commands is B<-> and that is reflected below. | |
31 | ||
32 | =over 4 | |
33 | ||
34 | =item B<-bugs> | |
35 | ||
36 | Various bug workarounds are set, same as setting B<SSL_OP_ALL>. | |
37 | ||
38 | =item B<-no_comp> | |
39 | ||
40 | Disables support for SSL/TLS compression, same as setting | |
41 | B<SSL_OP_NO_COMPRESSION>. | |
42 | As of OpenSSL 1.1.0, compression is off by default. | |
43 | ||
44 | =item B<-comp> | |
45 | ||
46 | Enables support for SSL/TLS compression, same as clearing | |
47 | B<SSL_OP_NO_COMPRESSION>. | |
48 | This command was introduced in OpenSSL 1.1.0. | |
49 | As of OpenSSL 1.1.0, compression is off by default. | |
50 | ||
51 | =item B<-no_ticket> | |
52 | ||
53 | Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>. | |
54 | ||
55 | =item B<-serverpref> | |
56 | ||
57 | Use server and not client preference order when determining which cipher suite, | |
58 | signature algorithm or elliptic curve to use for an incoming connection. | |
59 | Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers. | |
60 | ||
61 | =item B<-legacyrenegotiation> | |
62 | ||
63 | permits the use of unsafe legacy renegotiation. Equivalent to setting | |
64 | B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>. | |
65 | ||
66 | =item B<-no_renegotiation> | |
67 | ||
68 | Disables all attempts at renegotiation in TLSv1.2 and earlier, same as setting | |
69 | B<SSL_OP_NO_RENEGOTIATION>. | |
70 | ||
71 | =item B<-no_resumption_on_reneg> | |
72 | ||
73 | set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by servers. | |
74 | ||
75 | =item B<-legacy_server_connect>, B<-no_legacy_server_connect> | |
76 | ||
77 | permits or prohibits the use of unsafe legacy renegotiation for OpenSSL | |
78 | clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>. | |
79 | Set by default. | |
80 | ||
81 | =item B<-prioritize_chacha> | |
82 | ||
83 | Prioritize ChaCha ciphers when the client has a ChaCha20 cipher at the top of | |
84 | its preference list. This usually indicates a client without AES hardware | |
85 | acceleration (e.g. mobile) is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>. | |
86 | Only used by servers. Requires B<-serverpref>. | |
87 | ||
88 | =item B<-allow_no_dhe_kex> | |
89 | ||
90 | In TLSv1.3 allow a non-(ec)dhe based key exchange mode on resumption. This means | |
91 | that there will be no forward secrecy for the resumed session. | |
92 | ||
93 | =item B<-strict> | |
94 | ||
95 | enables strict mode protocol handling. Equivalent to setting | |
96 | B<SSL_CERT_FLAG_TLS_STRICT>. | |
97 | ||
98 | =item B<-sigalgs> I<algs> | |
99 | ||
100 | This sets the supported signature algorithms for TLSv1.2 and TLSv1.3. | |
101 | For clients this value is used directly for the supported signature | |
102 | algorithms extension. For servers it is used to determine which signature | |
103 | algorithms to support. | |
104 | ||
105 | The B<algs> argument should be a colon separated list of signature | |
106 | algorithms in order of decreasing preference of the form B<algorithm+hash> | |
107 | or B<signature_scheme>. B<algorithm> is one of B<RSA>, B<DSA> or B<ECDSA> and | |
108 | B<hash> is a supported algorithm OID short name such as B<SHA1>, B<SHA224>, | |
109 | B<SHA256>, B<SHA384> of B<SHA512>. Note: algorithm and hash names are case | |
110 | sensitive. B<signature_scheme> is one of the signature schemes defined in | |
111 | TLSv1.3, specified using the IETF name, e.g., B<ecdsa_secp256r1_sha256>, | |
112 | B<ed25519>, or B<rsa_pss_pss_sha256>. | |
113 | ||
114 | If this option is not set then all signature algorithms supported by the | |
115 | OpenSSL library are permissible. | |
116 | ||
117 | Note: algorithms which specify a PKCS#1 v1.5 signature scheme (either by | |
118 | using B<RSA> as the B<algorithm> or by using one of the B<rsa_pkcs1_*> | |
119 | identifiers) are ignored in TLSv1.3 and will not be negotiated. | |
120 | ||
121 | =item B<-client_sigalgs> I<algs> | |
122 | ||
123 | This sets the supported signature algorithms associated with client | |
124 | authentication for TLSv1.2 and TLSv1.3. For servers the B<algs> is used | |
125 | in the B<signature_algorithms> field of a B<CertificateRequest> message. | |
126 | For clients it is used to determine which signature algorithm to use with | |
127 | the client certificate. If a server does not request a certificate this | |
128 | option has no effect. | |
129 | ||
130 | The syntax of B<algs> is identical to B<-sigalgs>. If not set, then the | |
131 | value set for B<-sigalgs> will be used instead. | |
132 | ||
133 | =item B<-groups> I<groups> | |
134 | ||
135 | This sets the supported groups. For clients, the groups are sent using | |
136 | the supported groups extension. For servers, it is used to determine which | |
137 | group to use. This setting affects groups used for signatures (in TLSv1.2 | |
138 | and earlier) and key exchange. The first group listed will also be used | |
139 | for the B<key_share> sent by a client in a TLSv1.3 B<ClientHello>. | |
140 | ||
141 | The B<groups> argument is a colon separated list of groups. The group can | |
142 | be either the B<NIST> name (e.g. B<P-256>), some other commonly used name | |
143 | where applicable (e.g. B<X25519>, B<ffdhe2048>) or an OpenSSL OID name | |
144 | (e.g. B<prime256v1>). Group names are case sensitive. The list should be | |
145 | in order of preference with the most preferred group first. | |
146 | ||
147 | Currently supported groups for B<TLSv1.3> are B<P-256>, B<P-384>, B<P-521>, | |
148 | B<X25519>, B<X448>, B<ffdhe2048>, B<ffdhe3072>, B<ffdhe4096>, B<ffdhe6144>, | |
149 | B<ffdhe8192>. | |
150 | ||
151 | =item B<-curves> I<groups> | |
152 | ||
153 | This is a synonym for the B<-groups> command. | |
154 | ||
155 | =item B<-named_curve> I<curve> | |
156 | ||
157 | This sets the temporary curve used for ephemeral ECDH modes. Only used | |
158 | by servers. | |
159 | ||
160 | The B<groups> argument is a curve name or the special value B<auto> which | |
161 | picks an appropriate curve based on client and server preferences. The | |
162 | curve can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name | |
163 | (e.g. B<prime256v1>). Curve names are case sensitive. | |
164 | ||
165 | =item B<-cipher> I<ciphers> | |
166 | ||
167 | Sets the TLSv1.2 and below ciphersuite list to B<ciphers>. This list will be | |
168 | combined with any configured TLSv1.3 ciphersuites. Note: syntax checking | |
169 | of B<ciphers> is currently not performed unless a B<SSL> or B<SSL_CTX> | |
170 | structure is associated with B<ctx>. | |
171 | ||
172 | =item B<-ciphersuites> I<1.3ciphers> | |
173 | ||
174 | Sets the available ciphersuites for TLSv1.3 to value. This is a | |
175 | colon-separated list of TLSv1.3 ciphersuite names in order of preference. This | |
176 | list will be combined any configured TLSv1.2 and below ciphersuites. | |
177 | See L<openssl-ciphers(1)> for more information. | |
178 | ||
179 | =item B<-min_protocol> I<minprot>, B<-max_protocol> I<maxprot> | |
180 | ||
181 | Sets the minimum and maximum supported protocol. | |
182 | Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>, | |
183 | B<TLSv1.2>, B<TLSv1.3> for TLS; B<DTLSv1>, B<DTLSv1.2> for DTLS, and B<None> | |
184 | for no limit. | |
185 | If either the lower or upper bound is not specified then only the other bound | |
186 | applies, if specified. | |
187 | If your application supports both TLS and DTLS you can specify any of these | |
188 | options twice, once with a bound for TLS and again with an appropriate bound | |
189 | for DTLS. | |
190 | To restrict the supported protocol versions use these commands rather than the | |
191 | deprecated alternative commands below. | |
192 | ||
193 | =item B<-record_padding> I<padding> | |
194 | ||
195 | Attempts to pad TLSv1.3 records so that they are a multiple of B<padding> | |
196 | in length on send. A B<padding> of 0 or 1 turns off padding. Otherwise, | |
197 | the B<padding> must be >1 or <=16384. | |
198 | ||
199 | =item B<-debug_broken_protocol> | |
200 | ||
201 | Ignored. | |
202 | ||
203 | =item B<-no_middlebox> | |
204 | ||
205 | Turn off "middlebox compatibility", as described below. | |
206 | ||
207 | =back | |
208 | ||
209 | =head2 Additional Options | |
210 | ||
211 | The following options are accepted by SSL_CONF_cmd(), but are not | |
212 | processed by the OpenSSL commands. | |
213 | ||
214 | =over 4 | |
215 | ||
216 | =item B<-cert> I<file> | |
217 | ||
218 | Attempts to use B<file> as the certificate for the appropriate context. It | |
219 | currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX> | |
220 | structure is set or SSL_use_certificate_file() with filetype PEM if an | |
221 | B<SSL> structure is set. This option is only supported if certificate | |
222 | operations are permitted. | |
223 | ||
224 | =item B<-key> I<file> | |
225 | ||
226 | Attempts to use B<file> as the private key for the appropriate context. This | |
227 | option is only supported if certificate operations are permitted. Note: | |
228 | if no B<-key> option is set then a private key is not loaded unless the | |
229 | flag B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set. | |
230 | ||
231 | =item B<-dhparam> I<file> | |
232 | ||
233 | Attempts to use B<file> as the set of temporary DH parameters for | |
234 | the appropriate context. This option is only supported if certificate | |
235 | operations are permitted. | |
236 | ||
237 | =item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3> | |
238 | ||
239 | Disables protocol support for SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3 by | |
240 | setting the corresponding options B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>, | |
241 | B<SSL_OP_NO_TLSv1_1>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3> | |
242 | respectively. These options are deprecated, use B<-min_protocol> and | |
243 | B<-max_protocol> instead. | |
244 | ||
245 | =item B<-anti_replay>, B<-no_anti_replay> | |
246 | ||
247 | Switches replay protection, on or off respectively. With replay protection on, | |
248 | OpenSSL will automatically detect if a session ticket has been used more than | |
249 | once, TLSv1.3 has been negotiated, and early data is enabled on the server. A | |
250 | full handshake is forced if a session ticket is used a second or subsequent | |
251 | time. Anti-Replay is on by default unless overridden by a configuration file and | |
252 | is only used by servers. Anti-replay measures are required for compliance with | |
253 | the TLSv1.3 specification. Some applications may be able to mitigate the replay | |
254 | risks in other ways and in such cases the built-in OpenSSL functionality is not | |
255 | required. Switching off anti-replay is equivalent to B<SSL_OP_NO_ANTI_REPLAY>. | |
256 | ||
257 | =back | |
258 | ||
259 | =head1 SUPPORTED CONFIGURATION FILE COMMANDS | |
260 | ||
261 | Currently supported B<option> names for configuration files (i.e., when the | |
262 | flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file | |
263 | B<option> names are case insensitive so B<signaturealgorithms> is recognised | |
264 | as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names | |
265 | are also case insensitive. | |
266 | ||
267 | Note: the command prefix (if set) alters the recognised B<option> values. | |
268 | ||
269 | =over 4 | |
270 | ||
271 | =item B<CipherString> | |
272 | ||
273 | Sets the ciphersuite list for TLSv1.2 and below to B<value>. This list will be | |
274 | combined with any configured TLSv1.3 ciphersuites. Note: syntax | |
275 | checking of B<value> is currently not performed unless an B<SSL> or B<SSL_CTX> | |
276 | structure is associated with B<ctx>. | |
277 | ||
278 | =item B<Ciphersuites> | |
279 | ||
280 | Sets the available ciphersuites for TLSv1.3 to B<value>. This is a | |
281 | colon-separated list of TLSv1.3 ciphersuite names in order of preference. This | |
282 | list will be combined any configured TLSv1.2 and below ciphersuites. | |
283 | See L<openssl-ciphers(1)> for more information. | |
284 | ||
285 | =item B<Certificate> | |
286 | ||
287 | Attempts to use the file B<value> as the certificate for the appropriate | |
288 | context. It currently uses SSL_CTX_use_certificate_chain_file() if an B<SSL_CTX> | |
289 | structure is set or SSL_use_certificate_file() with filetype PEM if an B<SSL> | |
290 | structure is set. This option is only supported if certificate operations | |
291 | are permitted. | |
292 | ||
293 | =item B<PrivateKey> | |
294 | ||
295 | Attempts to use the file B<value> as the private key for the appropriate | |
296 | context. This option is only supported if certificate operations | |
297 | are permitted. Note: if no B<PrivateKey> option is set then a private key is | |
298 | not loaded unless the B<SSL_CONF_FLAG_REQUIRE_PRIVATE> is set. | |
299 | ||
300 | =item B<ChainCAFile>, B<ChainCAPath>, B<VerifyCAFile>, B<VerifyCAPath> | |
301 | ||
302 | These options indicate a file or directory used for building certificate | |
303 | chains or verifying certificate chains. These options are only supported | |
304 | if certificate operations are permitted. | |
305 | ||
306 | =item B<RequestCAFile> | |
307 | ||
308 | This option indicates a file containing a set of certificates in PEM form. | |
309 | The subject names of the certificates are sent to the peer in the | |
310 | B<certificate_authorities> extension for TLS 1.3 (in ClientHello or | |
311 | CertificateRequest) or in a certificate request for previous versions or | |
312 | TLS. | |
313 | ||
314 | =item B<ServerInfoFile> | |
315 | ||
316 | Attempts to use the file B<value> in the "serverinfo" extension using the | |
317 | function SSL_CTX_use_serverinfo_file. | |
318 | ||
319 | =item B<DHParameters> | |
320 | ||
321 | Attempts to use the file B<value> as the set of temporary DH parameters for | |
322 | the appropriate context. This option is only supported if certificate | |
323 | operations are permitted. | |
324 | ||
325 | =item B<RecordPadding> | |
326 | ||
327 | Attempts to pad TLSv1.3 records so that they are a multiple of B<value> in | |
328 | length on send. A B<value> of 0 or 1 turns off padding. Otherwise, the | |
329 | B<value> must be >1 or <=16384. | |
330 | ||
331 | =item B<SignatureAlgorithms> | |
332 | ||
333 | This sets the supported signature algorithms for TLSv1.2 and TLSv1.3. | |
334 | For clients this | |
335 | value is used directly for the supported signature algorithms extension. For | |
336 | servers it is used to determine which signature algorithms to support. | |
337 | ||
338 | The B<value> argument should be a colon separated list of signature algorithms | |
339 | in order of decreasing preference of the form B<algorithm+hash> or | |
340 | B<signature_scheme>. B<algorithm> | |
341 | is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm | |
342 | OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>. | |
343 | Note: algorithm and hash names are case sensitive. | |
344 | B<signature_scheme> is one of the signature schemes defined in TLSv1.3, | |
345 | specified using the IETF name, e.g., B<ecdsa_secp256r1_sha256>, B<ed25519>, | |
346 | or B<rsa_pss_pss_sha256>. | |
347 | ||
348 | If this option is not set then all signature algorithms supported by the | |
349 | OpenSSL library are permissible. | |
350 | ||
351 | Note: algorithms which specify a PKCS#1 v1.5 signature scheme (either by | |
352 | using B<RSA> as the B<algorithm> or by using one of the B<rsa_pkcs1_*> | |
353 | identifiers) are ignored in TLSv1.3 and will not be negotiated. | |
354 | ||
355 | =item B<ClientSignatureAlgorithms> | |
356 | ||
357 | This sets the supported signature algorithms associated with client | |
358 | authentication for TLSv1.2 and TLSv1.3. | |
359 | For servers the value is used in the | |
360 | B<signature_algorithms> field of a B<CertificateRequest> message. | |
361 | For clients it is | |
362 | used to determine which signature algorithm to use with the client certificate. | |
363 | If a server does not request a certificate this option has no effect. | |
364 | ||
365 | The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then | |
366 | the value set for B<SignatureAlgorithms> will be used instead. | |
367 | ||
368 | =item B<Groups> | |
369 | ||
370 | This sets the supported groups. For clients, the groups are | |
371 | sent using the supported groups extension. For servers, it is used | |
372 | to determine which group to use. This setting affects groups used for | |
373 | signatures (in TLSv1.2 and earlier) and key exchange. The first group listed | |
374 | will also be used for the B<key_share> sent by a client in a TLSv1.3 | |
375 | B<ClientHello>. | |
376 | ||
377 | The B<value> argument is a colon separated list of groups. The group can be | |
378 | either the B<NIST> name (e.g. B<P-256>), some other commonly used name where | |
379 | applicable (e.g. B<X25519>, B<ffdhe2048>) or an OpenSSL OID name | |
380 | (e.g. B<prime256v1>). Group names are case sensitive. The list should be in | |
381 | order of preference with the most preferred group first. | |
382 | ||
383 | Currently supported groups for B<TLSv1.3> are B<P-256>, B<P-384>, B<P-521>, | |
384 | B<X25519>, B<X448>, B<ffdhe2048>, B<ffdhe3072>, B<ffdhe4096>, B<ffdhe6144>, | |
385 | B<ffdhe8192>. | |
386 | ||
387 | =item B<Curves> | |
388 | ||
389 | This is a synonym for the "Groups" command. | |
390 | ||
391 | =item B<MinProtocol> | |
392 | ||
393 | This sets the minimum supported SSL, TLS or DTLS version. | |
394 | ||
395 | Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>, | |
396 | B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>. | |
397 | The SSL and TLS bounds apply only to TLS-based contexts, while the DTLS bounds | |
398 | apply only to DTLS-based contexts. | |
399 | The command can be repeated with one instance setting a TLS bound, and the | |
400 | other setting a DTLS bound. | |
401 | The value B<None> applies to both types of contexts and disables the limits. | |
402 | ||
403 | =item B<MaxProtocol> | |
404 | ||
405 | This sets the maximum supported SSL, TLS or DTLS version. | |
406 | ||
407 | Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>, | |
408 | B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>. | |
409 | The SSL and TLS bounds apply only to TLS-based contexts, while the DTLS bounds | |
410 | apply only to DTLS-based contexts. | |
411 | The command can be repeated with one instance setting a TLS bound, and the | |
412 | other setting a DTLS bound. | |
413 | The value B<None> applies to both types of contexts and disables the limits. | |
414 | ||
415 | =item B<Protocol> | |
416 | ||
417 | This can be used to enable or disable certain versions of the SSL, | |
418 | TLS or DTLS protocol. | |
419 | ||
420 | The B<value> argument is a comma separated list of supported protocols | |
421 | to enable or disable. | |
422 | If a protocol is preceded by B<-> that version is disabled. | |
423 | ||
424 | All protocol versions are enabled by default. | |
425 | You need to disable at least one protocol version for this setting have any | |
426 | effect. | |
427 | Only enabling some protocol versions does not disable the other protocol | |
428 | versions. | |
429 | ||
430 | Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>, | |
431 | B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>. | |
432 | The special value B<ALL> refers to all supported versions. | |
433 | ||
434 | This can't enable protocols that are disabled using B<MinProtocol> | |
435 | or B<MaxProtocol>, but can disable protocols that are still allowed | |
436 | by them. | |
437 | ||
438 | The B<Protocol> command is fragile and deprecated; do not use it. | |
439 | Use B<MinProtocol> and B<MaxProtocol> instead. | |
440 | If you do use B<Protocol>, make sure that the resulting range of enabled | |
441 | protocols has no "holes", e.g. if TLS 1.0 and TLS 1.2 are both enabled, make | |
442 | sure to also leave TLS 1.1 enabled. | |
443 | ||
444 | =item B<Options> | |
445 | ||
446 | The B<value> argument is a comma separated list of various flags to set. | |
447 | If a flag string is preceded B<-> it is disabled. | |
448 | See the L<SSL_CTX_set_options(3)> function for more details of | |
449 | individual options. | |
450 | ||
451 | Each option is listed below. Where an operation is enabled by default | |
452 | the B<-flag> syntax is needed to disable it. | |
453 | ||
454 | B<SessionTicket>: session ticket support, enabled by default. Inverse of | |
455 | B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting | |
456 | B<SSL_OP_NO_TICKET>. | |
457 | ||
458 | B<Compression>: SSL/TLS compression support, enabled by default. Inverse | |
459 | of B<SSL_OP_NO_COMPRESSION>. | |
460 | ||
461 | B<EmptyFragments>: use empty fragments as a countermeasure against a | |
462 | SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It | |
463 | is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>. | |
464 | ||
465 | B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>. | |
466 | ||
467 | B<DHSingle>: enable single use DH keys, set by default. Inverse of | |
468 | B<SSL_OP_DH_SINGLE>. Only used by servers. | |
469 | ||
470 | B<ECDHSingle>: enable single use ECDH keys, set by default. Inverse of | |
471 | B<SSL_OP_ECDH_SINGLE>. Only used by servers. | |
472 | ||
473 | B<ServerPreference>: use server and not client preference order when | |
474 | determining which cipher suite, signature algorithm or elliptic curve | |
475 | to use for an incoming connection. Equivalent to | |
476 | B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers. | |
477 | ||
478 | B<PrioritizeChaCha>: prioritizes ChaCha ciphers when the client has a | |
479 | ChaCha20 cipher at the top of its preference list. This usually indicates | |
480 | a mobile client is in use. Equivalent to B<SSL_OP_PRIORITIZE_CHACHA>. | |
481 | Only used by servers. | |
482 | ||
483 | B<NoResumptionOnRenegotiation>: set | |
484 | B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> flag. Only used by servers. | |
485 | ||
486 | B<NoRenegotiation>: disables all attempts at renegotiation in TLSv1.2 and | |
487 | earlier, same as setting B<SSL_OP_NO_RENEGOTIATION>. | |
488 | ||
489 | B<UnsafeLegacyRenegotiation>: permits the use of unsafe legacy renegotiation. | |
490 | Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>. | |
491 | ||
492 | B<UnsafeLegacyServerConnect>: permits the use of unsafe legacy renegotiation | |
493 | for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>. | |
494 | Set by default. | |
495 | ||
496 | B<EncryptThenMac>: use encrypt-then-mac extension, enabled by | |
497 | default. Inverse of B<SSL_OP_NO_ENCRYPT_THEN_MAC>: that is, | |
498 | B<-EncryptThenMac> is the same as setting B<SSL_OP_NO_ENCRYPT_THEN_MAC>. | |
499 | ||
500 | B<AllowNoDHEKEX>: In TLSv1.3 allow a non-(ec)dhe based key exchange mode on | |
501 | resumption. This means that there will be no forward secrecy for the resumed | |
502 | session. Equivalent to B<SSL_OP_ALLOW_NO_DHE_KEX>. | |
503 | ||
504 | B<MiddleboxCompat>: If set then dummy Change Cipher Spec (CCS) messages are sent | |
505 | in TLSv1.3. This has the effect of making TLSv1.3 look more like TLSv1.2 so that | |
506 | middleboxes that do not understand TLSv1.3 will not drop the connection. This | |
507 | option is set by default. A future version of OpenSSL may not set this by | |
508 | default. Equivalent to B<SSL_OP_ENABLE_MIDDLEBOX_COMPAT>. | |
509 | ||
510 | B<AntiReplay>: If set then OpenSSL will automatically detect if a session ticket | |
511 | has been used more than once, TLSv1.3 has been negotiated, and early data is | |
512 | enabled on the server. A full handshake is forced if a session ticket is used a | |
513 | second or subsequent time. This option is set by default and is only used by | |
514 | servers. Anti-replay measures are required to comply with the TLSv1.3 | |
515 | specification. Some applications may be able to mitigate the replay risks in | |
516 | other ways and in such cases the built-in OpenSSL functionality is not required. | |
517 | Disabling anti-replay is equivalent to setting B<SSL_OP_NO_ANTI_REPLAY>. | |
518 | ||
519 | B<ExtendedMasterSecret>: use extended master secret extension, enabled by | |
520 | default. Inverse of B<SSL_OP_NO_EXTENDED_MASTER_SECRET>: that is, | |
521 | B<-ExtendedMasterSecret> is the same as setting B<SSL_OP_NO_EXTENDED_MASTER_SECRET>. | |
522 | ||
523 | B<CANames>: use CA names extension, enabled by | |
524 | default. Inverse of B<SSL_OP_DISABLE_TLSEXT_CA_NAMES>: that is, | |
525 | B<-CANames> is the same as setting B<SSL_OP_DISABLE_TLSEXT_CA_NAMES>. | |
526 | ||
527 | B<KTLS>: Enables kernel TLS if support has been compiled in, and it is supported | |
528 | by the negotiated ciphersuites and extensions. Equivalent to | |
529 | B<SSL_OP_ENABLE_KTLS>. | |
530 | ||
531 | =item B<VerifyMode> | |
532 | ||
533 | The B<value> argument is a comma separated list of flags to set. | |
534 | ||
535 | B<Peer> enables peer verification: for clients only. | |
536 | ||
537 | B<Request> requests but does not require a certificate from the client. | |
538 | Servers only. | |
539 | ||
540 | B<Require> requests and requires a certificate from the client: an error | |
541 | occurs if the client does not present a certificate. Servers only. | |
542 | ||
543 | B<Once> requests a certificate from a client only on the initial connection: | |
544 | not when renegotiating. Servers only. | |
545 | ||
546 | B<RequestPostHandshake> configures the connection to support requests but does | |
547 | not require a certificate from the client post-handshake. A certificate will | |
548 | not be requested during the initial handshake. The server application must | |
549 | provide a mechanism to request a certificate post-handshake. Servers only. | |
550 | TLSv1.3 only. | |
551 | ||
552 | B<RequiresPostHandshake> configures the connection to support requests and | |
553 | requires a certificate from the client post-handshake: an error occurs if the | |
554 | client does not present a certificate. A certificate will not be requested | |
555 | during the initial handshake. The server application must provide a mechanism | |
556 | to request a certificate post-handshake. Servers only. TLSv1.3 only. | |
557 | ||
558 | =item B<ClientCAFile>, B<ClientCAPath> | |
559 | ||
560 | A file or directory of certificates in PEM format whose names are used as the | |
561 | set of acceptable names for client CAs. Servers only. This option is only | |
562 | supported if certificate operations are permitted. | |
563 | ||
564 | =back | |
565 | ||
566 | =head1 SUPPORTED COMMAND TYPES | |
567 | ||
568 | The function SSL_CONF_cmd_value_type() currently returns one of the following | |
569 | types: | |
570 | ||
571 | =over 4 | |
572 | ||
573 | =item B<SSL_CONF_TYPE_UNKNOWN> | |
574 | ||
575 | The B<option> string is unrecognised, this return value can be use to flag | |
576 | syntax errors. | |
577 | ||
578 | =item B<SSL_CONF_TYPE_STRING> | |
579 | ||
580 | The value is a string without any specific structure. | |
581 | ||
582 | =item B<SSL_CONF_TYPE_FILE> | |
583 | ||
584 | The value is a filename. | |
585 | ||
586 | =item B<SSL_CONF_TYPE_DIR> | |
587 | ||
588 | The value is a directory name. | |
589 | ||
590 | =item B<SSL_CONF_TYPE_NONE> | |
591 | ||
592 | The value string is not used e.g. a command line option which doesn't take an | |
593 | argument. | |
594 | ||
595 | =back | |
596 | ||
597 | =head1 NOTES | |
598 | ||
599 | The order of operations is significant. This can be used to set either defaults | |
600 | or values which cannot be overridden. For example if an application calls: | |
601 | ||
602 | SSL_CONF_cmd(ctx, "Protocol", "-SSLv3"); | |
603 | SSL_CONF_cmd(ctx, userparam, uservalue); | |
604 | ||
605 | it will disable SSLv3 support by default but the user can override it. If | |
606 | however the call sequence is: | |
607 | ||
608 | SSL_CONF_cmd(ctx, userparam, uservalue); | |
609 | SSL_CONF_cmd(ctx, "Protocol", "-SSLv3"); | |
610 | ||
611 | SSLv3 is B<always> disabled and attempt to override this by the user are | |
612 | ignored. | |
613 | ||
614 | By checking the return code of SSL_CONF_cmd() it is possible to query if a | |
615 | given B<option> is recognised, this is useful if SSL_CONF_cmd() values are | |
616 | mixed with additional application specific operations. | |
617 | ||
618 | For example an application might call SSL_CONF_cmd() and if it returns | |
619 | -2 (unrecognised command) continue with processing of application specific | |
620 | commands. | |
621 | ||
622 | Applications can also use SSL_CONF_cmd() to process command lines though the | |
623 | utility function SSL_CONF_cmd_argv() is normally used instead. One way | |
624 | to do this is to set the prefix to an appropriate value using | |
625 | SSL_CONF_CTX_set1_prefix(), pass the current argument to B<option> and the | |
626 | following argument to B<value> (which may be NULL). | |
627 | ||
628 | In this case if the return value is positive then it is used to skip that | |
629 | number of arguments as they have been processed by SSL_CONF_cmd(). If -2 is | |
630 | returned then B<option> is not recognised and application specific arguments | |
631 | can be checked instead. If -3 is returned a required argument is missing | |
632 | and an error is indicated. If 0 is returned some other error occurred and | |
633 | this can be reported back to the user. | |
634 | ||
635 | The function SSL_CONF_cmd_value_type() can be used by applications to | |
636 | check for the existence of a command or to perform additional syntax | |
637 | checking or translation of the command value. For example if the return | |
638 | value is B<SSL_CONF_TYPE_FILE> an application could translate a relative | |
639 | pathname to an absolute pathname. | |
640 | ||
641 | =head1 RETURN VALUES | |
642 | ||
643 | SSL_CONF_cmd() returns 1 if the value of B<option> is recognised and B<value> is | |
644 | B<NOT> used and 2 if both B<option> and B<value> are used. In other words it | |
645 | returns the number of arguments processed. This is useful when processing | |
646 | command lines. | |
647 | ||
648 | A return value of -2 means B<option> is not recognised. | |
649 | ||
650 | A return value of -3 means B<option> is recognised and the command requires a | |
651 | value but B<value> is NULL. | |
652 | ||
653 | A return code of 0 indicates that both B<option> and B<value> are valid but an | |
654 | error occurred attempting to perform the operation: for example due to an | |
655 | error in the syntax of B<value> in this case the error queue may provide | |
656 | additional information. | |
657 | ||
658 | =head1 EXAMPLES | |
659 | ||
660 | Set supported signature algorithms: | |
661 | ||
662 | SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256"); | |
663 | ||
664 | There are various ways to select the supported protocols. | |
665 | ||
666 | This set the minimum protocol version to TLSv1, and so disables SSLv3. | |
667 | This is the recommended way to disable protocols. | |
668 | ||
669 | SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1"); | |
670 | ||
671 | The following also disables SSLv3: | |
672 | ||
673 | SSL_CONF_cmd(ctx, "Protocol", "-SSLv3"); | |
674 | ||
675 | The following will first enable all protocols, and then disable | |
676 | SSLv3. | |
677 | If no protocol versions were disabled before this has the same effect as | |
678 | "-SSLv3", but if some versions were disables this will re-enable them before | |
679 | disabling SSLv3. | |
680 | ||
681 | SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3"); | |
682 | ||
683 | Only enable TLSv1.2: | |
684 | ||
685 | SSL_CONF_cmd(ctx, "MinProtocol", "TLSv1.2"); | |
686 | SSL_CONF_cmd(ctx, "MaxProtocol", "TLSv1.2"); | |
687 | ||
688 | This also only enables TLSv1.2: | |
689 | ||
690 | SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2"); | |
691 | ||
692 | Disable TLS session tickets: | |
693 | ||
694 | SSL_CONF_cmd(ctx, "Options", "-SessionTicket"); | |
695 | ||
696 | Enable compression: | |
697 | ||
698 | SSL_CONF_cmd(ctx, "Options", "Compression"); | |
699 | ||
700 | Set supported curves to P-256, P-384: | |
701 | ||
702 | SSL_CONF_cmd(ctx, "Curves", "P-256:P-384"); | |
703 | ||
704 | =head1 SEE ALSO | |
705 | ||
706 | L<ssl(7)>, | |
707 | L<SSL_CONF_CTX_new(3)>, | |
708 | L<SSL_CONF_CTX_set_flags(3)>, | |
709 | L<SSL_CONF_CTX_set1_prefix(3)>, | |
710 | L<SSL_CONF_CTX_set_ssl_ctx(3)>, | |
711 | L<SSL_CONF_cmd_argv(3)>, | |
712 | L<SSL_CTX_set_options(3)> | |
713 | ||
714 | =head1 HISTORY | |
715 | ||
716 | The SSL_CONF_cmd() function was added in OpenSSL 1.0.2. | |
717 | ||
718 | The B<SSL_OP_NO_SSL2> option doesn't have effect since 1.1.0, but the macro | |
719 | is retained for backwards compatibility. | |
720 | ||
721 | The B<SSL_CONF_TYPE_NONE> was added in OpenSSL 1.1.0. In earlier versions of | |
722 | OpenSSL passing a command which didn't take an argument would return | |
723 | B<SSL_CONF_TYPE_UNKNOWN>. | |
724 | ||
725 | B<MinProtocol> and B<MaxProtocol> where added in OpenSSL 1.1.0. | |
726 | ||
727 | B<AllowNoDHEKEX> and B<PrioritizeChaCha> were added in OpenSSL 1.1.1. | |
728 | ||
729 | =head1 COPYRIGHT | |
730 | ||
731 | Copyright 2012-2020 The OpenSSL Project Authors. All Rights Reserved. | |
732 | ||
733 | Licensed under the Apache License 2.0 (the "License"). You may not use | |
734 | this file except in compliance with the License. You can obtain a copy | |
735 | in the file LICENSE in the source distribution or at | |
736 | L<https://www.openssl.org/source/license.html>. | |
737 | ||
738 | =cut |