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3db935a9 DSH |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
5 | SSL_CONF_cmd - send configuration command | |
6 | ||
7 | =head1 SYNOPSIS | |
8 | ||
9 | #include <openssl/ssl.h> | |
10 | ||
11 | int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value); | |
ec2f7e56 DSH |
12 | int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd); |
13 | int SSL_CONF_finish(SSL_CONF_CTX *cctx); | |
3db935a9 DSH |
14 | |
15 | =head1 DESCRIPTION | |
16 | ||
17 | The function SSL_CONF_cmd() performs configuration operation B<cmd> 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 | |
13cfb043 DSH |
20 | framework for command line options or configuration files. |
21 | ||
ec2f7e56 DSH |
22 | SSL_CONF_cmd_value_type() returns the type of value that B<cmd> refers to. |
23 | ||
24 | The function SSL_CONF_finish() must be called after all configuration | |
25 | operations have been completed. It is used to finalise any operations | |
26 | or to process defaults. | |
27 | ||
13cfb043 DSH |
28 | =head1 SUPPORTED COMMAND LINE COMMANDS |
29 | ||
30 | Currently supported B<cmd> names for command lines (i.e. when the | |
31 | flag B<SSL_CONF_CMDLINE> is set) are listed below. Note: all B<cmd> names | |
32 | and are case sensitive. Unless otherwise stated commands can be used by | |
33 | both clients and servers and the B<value> parameter is not used. The default | |
34 | prefix for command line commands is B<-> and that is reflected below. | |
35 | ||
36 | =over 4 | |
37 | ||
38 | =item B<-sigalgs> | |
39 | ||
40 | This sets the supported signature algorithms for TLS v1.2. For clients this | |
41 | value is used directly for the supported signature algorithms extension. For | |
42 | servers it is used to determine which signature algorithms to support. | |
43 | ||
44 | The B<value> argument should be a colon separated list of signature algorithms | |
45 | in order of decreasing preference of the form B<algorithm+hash>. B<algorithm> | |
46 | is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm | |
47 | OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>. | |
48 | Note: algorithm and hash names are case sensitive. | |
49 | ||
50 | If this option is not set then all signature algorithms supported by the | |
51 | OpenSSL library are permissible. | |
52 | ||
53 | =item B<-client_sigalgs> | |
54 | ||
55 | This sets the supported signature algorithms associated with client | |
56 | authentication for TLS v1.2. For servers the value is used in the supported | |
57 | signature algorithms field of a certificate request. For clients it is | |
58 | used to determine which signature algorithm to with the client certificate. | |
59 | If a server does not request a certificate this option has no effect. | |
60 | ||
61 | The syntax of B<value> is identical to B<-sigalgs>. If not set then | |
62 | the value set for B<-sigalgs> will be used instead. | |
63 | ||
64 | =item B<-curves> | |
65 | ||
65f2a565 DSH |
66 | This sets the supported elliptic curves. For clients the curves are |
67 | sent using the supported curves extension. For servers it is used | |
13cfb043 DSH |
68 | to determine which curve to use. This setting affects curves used for both |
69 | signatures and key exchange, if applicable. | |
70 | ||
71 | The B<value> argument is a colon separated list of curves. The curve can be | |
72 | either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g | |
73 | B<prime256v1>). Curve names are case sensitive. | |
74 | ||
75 | =item B<-named_curve> | |
76 | ||
77 | This sets the temporary curve used for ephemeral ECDH modes. Only used by | |
78 | servers | |
79 | ||
80 | The B<value> argument is a curve name or the special value B<auto> which | |
81 | picks an appropriate curve based on client and server preferences. The curve | |
82 | can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name | |
83 | (e.g B<prime256v1>). Curve names are case sensitive. | |
84 | ||
85 | =item B<-cipher> | |
86 | ||
87 | Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is | |
88 | currently not performed unless a B<SSL> or B<SSL_CTX> structure is | |
89 | associated with B<cctx>. | |
90 | ||
ec2f7e56 DSH |
91 | =item B<-cert> |
92 | ||
93 | Attempts to use the file B<value> as the certificate for the appropriate | |
94 | context. It currently uses SSL_CTX_use_cerificate_chain_file if an B<SSL_CTX> | |
95 | structure is set or SSL_use_certifcate_file with filetype PEM if an B<SSL> | |
96 | structure is set. This option is only supported if certificate operations | |
97 | are permitted. | |
98 | ||
99 | =item B<-key> | |
100 | ||
101 | Attempts to use the file B<value> as the private key for the appropriate | |
102 | context. This option is only supported if certificate operations | |
103 | are permitted. Note: if no B<-key> option is set then a private key is | |
104 | not loaded: it does not currently use the B<-cert> file. | |
105 | ||
c557f921 DSH |
106 | =item B<-dhparam> |
107 | ||
108 | Attempts to use the file B<value> as the set of temporary DH parameters for | |
109 | the appropriate context. This option is only supported if certificate | |
110 | operations are permitted. | |
111 | ||
13cfb043 DSH |
112 | =item B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2> |
113 | ||
114 | Disables protocol support for SSLv2, SSLv3, TLS 1.0, TLS 1.1 or TLS 1.2 | |
115 | by setting the corresponding options B<SSL_OP_NO_SSL2>, B<SSL_OP_NO_SSL3>, | |
116 | B<SSL_OP_NO_TLS1>, B<SSL_OP_NO_TLS1_1> and B<SSL_OP_NO_TLS1_2> respectively. | |
117 | ||
118 | =item B<-bugs> | |
119 | ||
120 | Various bug workarounds are set, same as setting B<SSL_OP_ALL>. | |
121 | ||
122 | =item B<-no_comp> | |
123 | ||
124 | Disables support for SSL/TLS compression, same as setting B<SSL_OP_NO_COMPRESS>. | |
125 | ||
126 | =item B<-no_ticket> | |
127 | ||
128 | Disables support for session tickets, same as setting B<SSL_OP_NO_TICKET>. | |
129 | ||
130 | =item B<-serverpref> | |
131 | ||
132 | Use server and not client preference order when determining which cipher suite, | |
133 | signature algorithm or elliptic curve to use for an incoming connection. | |
134 | Equivalent to B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers. | |
135 | ||
136 | =item B<-legacyrenegotiation> | |
137 | ||
138 | permits the use of unsafe legacy renegotiation. Equivalent to setting | |
139 | B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>. | |
140 | ||
141 | =item B<-legacy_server_connect>, B<-no_legacy_server_connect> | |
142 | ||
143 | permits or prohibits the use of unsafe legacy renegotiation for OpenSSL | |
144 | clients only. Equivalent to setting or clearing B<SSL_OP_LEGACY_SERVER_CONNECT>. | |
145 | Set by default. | |
146 | ||
147 | =item B<-strict> | |
148 | ||
149 | enables strict mode protocol handling. Equivalent to setting | |
150 | B<SSL_CERT_FLAG_TLS_STRICT>. | |
151 | ||
152 | =item B<-debug_broken_protocol> | |
153 | ||
154 | disables various checks and permits several kinds of broken protocol behaviour | |
155 | for testing purposes: it should B<NEVER> be used in anything other than a test | |
156 | environment. Only supported if OpenSSL is configured with | |
157 | B<-DOPENSSL_SSL_DEBUG_BROKEN_PROTOCOL>. | |
158 | ||
159 | =back | |
3db935a9 DSH |
160 | |
161 | =head1 SUPPORTED CONFIGURATION FILE COMMANDS | |
162 | ||
163 | Currently supported B<cmd> names for configuration files (i.e. when the | |
164 | flag B<SSL_CONF_FLAG_FILE> is set) are listed below. All configuration file | |
165 | B<cmd> names and are case insensitive so B<signaturealgorithms> is recognised | |
c7b7984a | 166 | as well as B<SignatureAlgorithms>. Unless otherwise stated the B<value> names |
3db935a9 DSH |
167 | are also case insensitive. |
168 | ||
169 | Note: the command prefix (if set) alters the recognised B<cmd> values. | |
170 | ||
171 | =over 4 | |
172 | ||
65f2a565 | 173 | =item B<CipherString> |
3db935a9 DSH |
174 | |
175 | Sets the cipher suite list to B<value>. Note: syntax checking of B<value> is | |
c7b7984a | 176 | currently not performed unless an B<SSL> or B<SSL_CTX> structure is |
3db935a9 DSH |
177 | associated with B<cctx>. |
178 | ||
ec2f7e56 DSH |
179 | =item B<Certificate> |
180 | ||
181 | Attempts to use the file B<value> as the certificate for the appropriate | |
182 | context. It currently uses SSL_CTX_use_cerificate_chain_file if an B<SSL_CTX> | |
183 | structure is set or SSL_use_certifcate_file with filetype PEM if an B<SSL> | |
184 | structure is set. This option is only supported if certificate operations | |
185 | are permitted. | |
186 | ||
187 | =item B<PrivateKey> | |
188 | ||
189 | Attempts to use the file B<value> as the private key for the appropriate | |
190 | context. This option is only supported if certificate operations | |
191 | are permitted. Note: if no B<-key> option is set then a private key is | |
192 | not loaded: it does not currently use the B<Certificate> file. | |
193 | ||
c557f921 DSH |
194 | =item B<DHParameters> |
195 | ||
196 | Attempts to use the file B<value> as the set of temporary DH parameters for | |
197 | the appropriate context. This option is only supported if certificate | |
198 | operations are permitted. | |
199 | ||
3db935a9 DSH |
200 | =item B<SignatureAlgorithms> |
201 | ||
202 | This sets the supported signature algorithms for TLS v1.2. For clients this | |
203 | value is used directly for the supported signature algorithms extension. For | |
204 | servers it is used to determine which signature algorithms to support. | |
205 | ||
206 | The B<value> argument should be a colon separated list of signature algorithms | |
207 | in order of decreasing preference of the form B<algorithm+hash>. B<algorithm> | |
208 | is one of B<RSA>, B<DSA> or B<ECDSA> and B<hash> is a supported algorithm | |
209 | OID short name such as B<SHA1>, B<SHA224>, B<SHA256>, B<SHA384> of B<SHA512>. | |
210 | Note: algorithm and hash names are case sensitive. | |
211 | ||
212 | If this option is not set then all signature algorithms supported by the | |
213 | OpenSSL library are permissible. | |
214 | ||
215 | =item B<ClientSignatureAlgorithms> | |
216 | ||
217 | This sets the supported signature algorithms associated with client | |
218 | authentication for TLS v1.2. For servers the value is used in the supported | |
219 | signature algorithms field of a certificate request. For clients it is | |
c7b7984a | 220 | used to determine which signature algorithm to with the client certificate. |
3db935a9 DSH |
221 | |
222 | The syntax of B<value> is identical to B<SignatureAlgorithms>. If not set then | |
223 | the value set for B<SignatureAlgorithms> will be used instead. | |
224 | ||
225 | =item B<Curves> | |
226 | ||
65f2a565 DSH |
227 | This sets the supported elliptic curves. For clients the curves are |
228 | sent using the supported curves extension. For servers it is used | |
c7b7984a DSH |
229 | to determine which curve to use. This setting affects curves used for both |
230 | signatures and key exchange, if applicable. | |
3db935a9 DSH |
231 | |
232 | The B<value> argument is a colon separated list of curves. The curve can be | |
233 | either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name (e.g | |
234 | B<prime256v1>). Curve names are case sensitive. | |
235 | ||
236 | =item B<ECDHParameters> | |
237 | ||
13cfb043 DSH |
238 | This sets the temporary curve used for ephemeral ECDH modes. Only used by |
239 | servers | |
3db935a9 DSH |
240 | |
241 | The B<value> argument is a curve name or the special value B<Automatic> which | |
c7b7984a DSH |
242 | picks an appropriate curve based on client and server preferences. The curve |
243 | can be either the B<NIST> name (e.g. B<P-256>) or an OpenSSL OID name | |
244 | (e.g B<prime256v1>). Curve names are case sensitive. | |
3db935a9 DSH |
245 | |
246 | =item B<Protocol> | |
247 | ||
248 | The supported versions of the SSL or TLS protocol. | |
249 | ||
250 | The B<value> argument is a comma separated list of supported protocols to | |
251 | enable or disable. If an protocol is preceded by B<-> that version is disabled. | |
252 | All versions are enabled by default, though applications may choose to | |
c7b7984a DSH |
253 | explicitly disable some. Currently supported protocol values are B<SSLv2>, |
254 | B<SSLv3>, B<TLSv1>, B<TLSv1.1> and B<TLSv1.2>. The special value B<ALL> refers | |
255 | to all supported versions. | |
3db935a9 DSH |
256 | |
257 | =item B<Options> | |
258 | ||
259 | The B<value> argument is a comma separated list of various flags to set. | |
260 | If a flag string is preceded B<-> it is disabled. See the | |
261 | B<SSL_CTX_set_options> function for more details of individual options. | |
262 | ||
263 | Each option is listed below. Where an operation is enabled by default | |
264 | the B<-flag> syntax is needed to disable it. | |
265 | ||
266 | B<SessionTicket>: session ticket support, enabled by default. Inverse of | |
267 | B<SSL_OP_NO_TICKET>: that is B<-SessionTicket> is the same as setting | |
268 | B<SSL_OP_NO_TICKET>. | |
269 | ||
270 | B<Compression>: SSL/TLS compression support, enabled by default. Inverse | |
271 | of B<SSL_OP_NO_COMPRESSION>. | |
272 | ||
273 | B<EmptyFragments>: use empty fragments as a countermeasure against a | |
274 | SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It | |
275 | is set by default. Inverse of B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS>. | |
276 | ||
c7b7984a | 277 | B<Bugs>: enable various bug workarounds. Same as B<SSL_OP_ALL>. |
3db935a9 | 278 | |
c7b7984a | 279 | B<DHSingle>: enable single use DH keys, set by default. Inverse of |
3db935a9 DSH |
280 | B<SSL_OP_DH_SINGLE>. Only used by servers. |
281 | ||
282 | B<ECDHSingle> enable single use ECDH keys, set by default. Inverse of | |
283 | B<SSL_OP_ECDH_SINGLE>. Only used by servers. | |
284 | ||
285 | B<ServerPreference> use server and not client preference order when | |
286 | determining which cipher suite, signature algorithm or elliptic curve | |
287 | to use for an incoming connection. Equivalent to | |
288 | B<SSL_OP_CIPHER_SERVER_PREFERENCE>. Only used by servers. | |
289 | ||
290 | B<UnsafeLegacyRenegotiation> permits the use of unsafe legacy renegotiation. | |
291 | Equivalent to B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION>. | |
292 | ||
293 | B<UnsafeLegacyServerConnect> permits the use of unsafe legacy renegotiation | |
294 | for OpenSSL clients only. Equivalent to B<SSL_OP_LEGACY_SERVER_CONNECT>. | |
295 | Set by default. | |
296 | ||
297 | =back | |
298 | ||
ec2f7e56 DSH |
299 | =head1 SUPPORTED COMMAND TYPES |
300 | ||
301 | The function SSL_CONF_cmd_value_type() currently returns one of the following | |
302 | types: | |
303 | ||
304 | =over 4 | |
305 | ||
306 | =item B<SSL_CONF_TYPE_UNKNOWN> | |
307 | ||
308 | The B<cmd> string is unrecognised, this return value can be use to flag | |
309 | syntax errors. | |
310 | ||
311 | =item B<SSL_CONF_TYPE_STRING> | |
312 | ||
313 | The value is a string without any specific structure. | |
314 | ||
315 | =item B<SSL_CONF_TYPE_FILE> | |
316 | ||
317 | The value is a file name. | |
318 | ||
319 | =item B<SSL_CONF_TYPE_DIR> | |
320 | ||
321 | The value is a directory name. | |
322 | ||
3db935a9 DSH |
323 | =head1 NOTES |
324 | ||
325 | The order of operations is significant. This can be used to set either defaults | |
326 | or values which cannot be overridden. For example if an application calls: | |
327 | ||
328 | SSL_CONF_cmd(ctx, "Protocol", "-SSLv2"); | |
329 | SSL_CONF_cmd(ctx, userparam, uservalue); | |
330 | ||
331 | it will disable SSLv2 support by default but the user can override it. If | |
332 | however the call sequence is: | |
333 | ||
334 | SSL_CONF_cmd(ctx, userparam, uservalue); | |
335 | SSL_CONF_cmd(ctx, "Protocol", "-SSLv2"); | |
336 | ||
337 | SSLv2 is B<always> disabled and attempt to override this by the user are | |
338 | ignored. | |
339 | ||
340 | By checking the return code of SSL_CTX_cmd() it is possible to query if a | |
341 | given B<cmd> is recognised, this is useful is SSL_CTX_cmd() values are | |
342 | mixed with additional application specific operations. | |
343 | ||
344 | For example an application might call SSL_CTX_cmd() and if it returns | |
345 | -2 (unrecognised command) continue with processing of application specific | |
346 | commands. | |
347 | ||
348 | Applications can also use SSL_CTX_cmd() to process command lines though the | |
349 | utility function SSL_CTX_cmd_argv() is normally used instead. One way | |
821244cf DSH |
350 | to do this is to set the prefix to an appropriate value using |
351 | SSL_CONF_CTX_set1_prefix(), pass the current argument to B<cmd> and the | |
352 | following argument to B<value> (which may be NULL). | |
3db935a9 DSH |
353 | |
354 | In this case if the return value is positive then it is used to skip that | |
355 | number of arguments as they have been processed by SSL_CTX_cmd(). If -2 is | |
356 | returned then B<cmd> is not recognised and application specific arguments | |
357 | can be checked instead. If -3 is returned a required argument is missing | |
358 | and an error is indicated. If 0 is returned some other error occurred and | |
359 | this can be reported back to the user. | |
360 | ||
ec2f7e56 DSH |
361 | The function SSL_CONF_cmd_value_type() can be used by applications to |
362 | check for the existence of a command or to perform additional syntax | |
363 | checking or translation of the command value. For example if the return | |
364 | value is B<SSL_CONF_TYPE_FILE> an application could translate a relative | |
365 | pathname to an absolute pathname. | |
366 | ||
3db935a9 DSH |
367 | =head1 EXAMPLES |
368 | ||
369 | Set supported signature algorithms: | |
370 | ||
371 | SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256"); | |
372 | ||
373 | Enable all protocols except SSLv3 and SSLv2: | |
374 | ||
375 | SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3,-SSLv2"); | |
376 | ||
377 | Only enable TLSv1.2: | |
378 | ||
379 | SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2"); | |
380 | ||
381 | Disable TLS session tickets: | |
382 | ||
383 | SSL_CONF_cmd(ctx, "Options", "-SessionTicket"); | |
384 | ||
385 | Set supported curves to P-256, P-384: | |
386 | ||
387 | SSL_CONF_cmd(ctx, "Curves", "P-256:P-384"); | |
388 | ||
389 | Set automatic support for any elliptic curve for key exchange: | |
390 | ||
391 | SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic"); | |
392 | ||
393 | =head1 RETURN VALUES | |
394 | ||
4365e4aa | 395 | SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is |
3db935a9 DSH |
396 | B<NOT> used and 2 if both B<cmd> and B<value> are used. In other words it |
397 | returns the number of arguments processed. This is useful when processing | |
398 | command lines. | |
399 | ||
400 | A return value of -2 means B<cmd> is not recognised. | |
401 | ||
402 | A return value of -3 means B<cmd> is recognised and the command requires a | |
403 | value but B<value> is NULL. | |
404 | ||
405 | A return code of 0 indicates that both B<cmd> and B<value> are valid but an | |
406 | error occurred attempting to perform the operation: for example due to an | |
407 | error in the syntax of B<value> in this case the error queue may provide | |
408 | additional information. | |
409 | ||
ec2f7e56 DSH |
410 | SSL_CONF_finish() returns 1 for success and 0 for failure. |
411 | ||
3db935a9 DSH |
412 | =head1 SEE ALSO |
413 | ||
414 | L<SSL_CONF_CTX_new(3)|SSL_CONF_CTX_new(3)>, | |
415 | L<SSL_CONF_CTX_set_flags(3)|SSL_CONF_CTX_set_flags(3)>, | |
416 | L<SSL_CONF_CTX_set1_prefix(3)|SSL_CONF_CTX_set1_prefix(3)>, | |
417 | L<SSL_CONF_CTX_set_ssl_ctx(3)|SSL_CONF_CTX_set_ssl_ctx(3)>, | |
418 | L<SSL_CONF_cmd_argv(3)|SSL_CONF_cmd_argv(3)> | |
419 | ||
420 | =head1 HISTORY | |
421 | ||
4365e4aa | 422 | SSL_CONF_cmd() was first added to OpenSSL 1.0.2 |
3db935a9 DSH |
423 | |
424 | =cut |