1SSL_CONF_cmd(3) OpenSSL SSL_CONF_cmd(3)
2
6 SSL_CONF_cmd - send configuration command
7
9 #include <openssl/ssl.h>
10 int SSL_CONF_cmd(SSL_CONF_CTX *cctx, const char *cmd, const char *value);
12 int SSL_CONF_cmd_value_type(SSL_CONF_CTX *cctx, const char *cmd);
13 int SSL_CONF_finish(SSL_CONF_CTX *cctx);
14
16 The function SSL_CONF_cmd() performs configuration operation cmd with
17 optional parameter value on ctx. Its purpose is to simplify application
18 configuration of SSL_CTX or SSL structures by providing a common
19 framework for command line options or configuration files.
20 SSL_CONF_cmd_value_type() returns the type of value that cmd refers to.
22 The function SSL_CONF_finish() must be called after all configuration
24 operations have been completed. It is used to finalise any operations
25 or to process defaults.
26
28 Currently supported cmd names for command lines (i.e. when the flag
29 SSL_CONF_CMDLINE is set) are listed below. Note: all cmd names are case
30 sensitive. Unless otherwise stated commands can be used by both clients
31 and servers and the value parameter is not used. The default prefix for
32 command line commands is - and that is reflected below.
33 -sigalgs
35 This sets the supported signature algorithms for TLS v1.2. For
36 clients this value is used directly for the supported signature
37 algorithms extension. For servers it is used to determine which
38 signature algorithms to support.
39 The value argument should be a colon separated list of signature
41 algorithms in order of decreasing preference of the form
42 algorithm+hash. algorithm is one of RSA, DSA or ECDSA and hash is a
43 supported algorithm OID short name such as SHA1, SHA224, SHA256,
44 SHA384 of SHA512. Note: algorithm and hash names are case
45 sensitive.
46 If this option is not set then all signature algorithms supported
48 by the OpenSSL library are permissible.
49 -client_sigalgs
51 This sets the supported signature algorithms associated with client
52 authentication for TLS v1.2. For servers the value is used in the
53 supported signature algorithms field of a certificate request. For
54 clients it is used to determine which signature algorithm to with
55 the client certificate. If a server does not request a certificate
56 this option has no effect.
57 The syntax of value is identical to -sigalgs. If not set then the
59 value set for -sigalgs will be used instead.
60 -curves
62 This sets the supported elliptic curves. For clients the curves are
63 sent using the supported curves extension. For servers it is used
64 to determine which curve to use. This setting affects curves used
65 for both signatures and key exchange, if applicable.
66 The value argument is a colon separated list of curves. The curve
68 can be either the NIST name (e.g. P-256) or an OpenSSL OID name
69 (e.g prime256v1). Curve names are case sensitive.
70 -named_curve
72 This sets the temporary curve used for ephemeral ECDH modes. Only
73 used by servers
74 The value argument is a curve name or the special value auto which
76 picks an appropriate curve based on client and server preferences.
77 The curve can be either the NIST name (e.g. P-256) or an OpenSSL
78 OID name (e.g prime256v1). Curve names are case sensitive.
79 -cipher
81 Sets the cipher suite list to value. Note: syntax checking of value
82 is currently not performed unless a SSL or SSL_CTX structure is
83 associated with cctx.
84 -cert
86 Attempts to use the file value as the certificate for the
87 appropriate context. It currently uses
88 SSL_CTX_use_certificate_chain_file() if an SSL_CTX structure is set
89 or SSL_use_certificate_file() with filetype PEM if an SSL structure
90 is set. This option is only supported if certificate operations are
91 permitted.
92 -key
94 Attempts to use the file value as the private key for the
95 appropriate context. This option is only supported if certificate
96 operations are permitted. Note: if no -key option is set then a
97 private key is not loaded: it does not currently use the -cert
98 file.
99 -dhparam
101 Attempts to use the file value as the set of temporary DH
102 parameters for the appropriate context. This option is only
103 supported if certificate operations are permitted.
104 -no_ssl2, -no_ssl3, -no_tls1, -no_tls1_1, -no_tls1_2
106 Disables protocol support for SSLv2, SSLv3, TLSv1.0, TLSv1.1 or
107 TLSv1.2 by setting the corresponding options SSL_OP_NO_SSLv2,
108 SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1 and
109 SSL_OP_NO_TLSv1_2 respectively.
110 -bugs
112 Various bug workarounds are set, same as setting SSL_OP_ALL.
113 -no_comp
115 Disables support for SSL/TLS compression, same as setting
116 SSL_OP_NO_COMPRESS.
117 -no_ticket
119 Disables support for session tickets, same as setting
120 SSL_OP_NO_TICKET.
121 -serverpref
123 Use server and not client preference order when determining which
124 cipher suite, signature algorithm or elliptic curve to use for an
125 incoming connection. Equivalent to
126 SSL_OP_CIPHER_SERVER_PREFERENCE. Only used by servers.
127 -no_resumption_on_reneg
129 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used
130 by servers.
131 -legacyrenegotiation
133 permits the use of unsafe legacy renegotiation. Equivalent to
134 setting SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION.
135 -legacy_server_connect, -no_legacy_server_connect
137 permits or prohibits the use of unsafe legacy renegotiation for
138 OpenSSL clients only. Equivalent to setting or clearing
139 SSL_OP_LEGACY_SERVER_CONNECT. Set by default.
140 -strict
142 enables strict mode protocol handling. Equivalent to setting
143 SSL_CERT_FLAG_TLS_STRICT.
144 -debug_broken_protocol
146 disables various checks and permits several kinds of broken
147 protocol behaviour for testing purposes: it should NEVER be used in
148 anything other than a test environment. Only supported if OpenSSL
149 is configured with -DOPENSSL_SSL_DEBUG_BROKEN_PROTOCOL.
150
152 Currently supported cmd names for configuration files (i.e. when the
153 flag SSL_CONF_FLAG_FILE is set) are listed below. All configuration
154 file cmd names and are case insensitive so signaturealgorithms is
155 recognised as well as SignatureAlgorithms. Unless otherwise stated the
156 value names are also case insensitive.
157 Note: the command prefix (if set) alters the recognised cmd values.
159 CipherString
161 Sets the cipher suite list to value. Note: syntax checking of value
162 is currently not performed unless an SSL or SSL_CTX structure is
163 associated with cctx.
164 Certificate
166 Attempts to use the file value as the certificate for the
167 appropriate context. It currently uses
168 SSL_CTX_use_certificate_chain_file() if an SSL_CTX structure is set
169 or SSL_use_certificate_file() with filetype PEM if an SSL structure
170 is set. This option is only supported if certificate operations are
171 permitted.
172 PrivateKey
174 Attempts to use the file value as the private key for the
175 appropriate context. This option is only supported if certificate
176 operations are permitted. Note: if no -key option is set then a
177 private key is not loaded: it does not currently use the
178 Certificate file.
179 ServerInfoFile
181 Attempts to use the file value in the "serverinfo" extension using
182 the function SSL_CTX_use_serverinfo_file.
183 DHParameters
185 Attempts to use the file value as the set of temporary DH
186 parameters for the appropriate context. This option is only
187 supported if certificate operations are permitted.
188 SignatureAlgorithms
190 This sets the supported signature algorithms for TLS v1.2. For
191 clients this value is used directly for the supported signature
192 algorithms extension. For servers it is used to determine which
193 signature algorithms to support.
194 The value argument should be a colon separated list of signature
196 algorithms in order of decreasing preference of the form
197 algorithm+hash. algorithm is one of RSA, DSA or ECDSA and hash is a
198 supported algorithm OID short name such as SHA1, SHA224, SHA256,
199 SHA384 of SHA512. Note: algorithm and hash names are case
200 sensitive.
201 If this option is not set then all signature algorithms supported
203 by the OpenSSL library are permissible.
204 ClientSignatureAlgorithms
206 This sets the supported signature algorithms associated with client
207 authentication for TLS v1.2. For servers the value is used in the
208 supported signature algorithms field of a certificate request. For
209 clients it is used to determine which signature algorithm to with
210 the client certificate.
211 The syntax of value is identical to SignatureAlgorithms. If not set
213 then the value set for SignatureAlgorithms will be used instead.
214 Curves
216 This sets the supported elliptic curves. For clients the curves are
217 sent using the supported curves extension. For servers it is used
218 to determine which curve to use. This setting affects curves used
219 for both signatures and key exchange, if applicable.
220 The value argument is a colon separated list of curves. The curve
222 can be either the NIST name (e.g. P-256) or an OpenSSL OID name
223 (e.g prime256v1). Curve names are case sensitive.
224 ECDHParameters
226 This sets the temporary curve used for ephemeral ECDH modes. Only
227 used by servers
228 The value argument is a curve name or the special value Automatic
230 which picks an appropriate curve based on client and server
231 preferences. The curve can be either the NIST name (e.g. P-256) or
232 an OpenSSL OID name (e.g prime256v1). Curve names are case
233 sensitive.
234 Protocol
236 The supported versions of the SSL or TLS protocol.
237 The value argument is a comma separated list of supported protocols
239 to enable or disable. If an protocol is preceded by - that version
240 is disabled. Currently supported protocol values are SSLv2, SSLv3,
241 TLSv1, TLSv1.1 and TLSv1.2. All protocol versions other than SSLv2
242 are enabled by default. To avoid inadvertent enabling of SSLv2,
243 when SSLv2 is disabled, it is not possible to enable it via the
244 Protocol command.
245 Options
247 The value argument is a comma separated list of various flags to
248 set. If a flag string is preceded - it is disabled. See the
249 SSL_CTX_set_options function for more details of individual
250 options.
251 Each option is listed below. Where an operation is enabled by
253 default the -flag syntax is needed to disable it.
254 SessionTicket: session ticket support, enabled by default. Inverse
256 of SSL_OP_NO_TICKET: that is -SessionTicket is the same as setting
257 SSL_OP_NO_TICKET.
258 Compression: SSL/TLS compression support, enabled by default.
260 Inverse of SSL_OP_NO_COMPRESSION.
261 EmptyFragments: use empty fragments as a countermeasure against a
263 SSL 3.0/TLS 1.0 protocol vulnerability affecting CBC ciphers. It is
264 set by default. Inverse of SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS.
265 Bugs: enable various bug workarounds. Same as SSL_OP_ALL.
267 DHSingle: enable single use DH keys, set by default. Inverse of
269 SSL_OP_DH_SINGLE. Only used by servers.
270 ECDHSingle enable single use ECDH keys, set by default. Inverse of
272 SSL_OP_ECDH_SINGLE. Only used by servers.
273 ServerPreference use server and not client preference order when
275 determining which cipher suite, signature algorithm or elliptic
276 curve to use for an incoming connection. Equivalent to
277 SSL_OP_CIPHER_SERVER_PREFERENCE. Only used by servers.
278 NoResumptionOnRenegotiation set
280 SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Only used by
281 servers.
282 UnsafeLegacyRenegotiation permits the use of unsafe legacy
284 renegotiation. Equivalent to
285 SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION.
286 UnsafeLegacyServerConnect permits the use of unsafe legacy
288 renegotiation for OpenSSL clients only. Equivalent to
289 SSL_OP_LEGACY_SERVER_CONNECT. Set by default.
290
292 The function SSL_CONF_cmd_value_type() currently returns one of the
293 following types:
294 SSL_CONF_TYPE_UNKNOWN
296 The cmd string is unrecognised, this return value can be use to
297 flag syntax errors.
298 SSL_CONF_TYPE_STRING
300 The value is a string without any specific structure.
301 SSL_CONF_TYPE_FILE
303 The value is a file name.
304 SSL_CONF_TYPE_DIR
306 The value is a directory name.
307
309 The order of operations is significant. This can be used to set either
310 defaults or values which cannot be overridden. For example if an
311 application calls:
312 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
314 SSL_CONF_cmd(ctx, userparam, uservalue);
315 it will disable SSLv3 support by default but the user can override it.
317 If however the call sequence is:
318 SSL_CONF_cmd(ctx, userparam, uservalue);
320 SSL_CONF_cmd(ctx, "Protocol", "-SSLv3");
321 then SSLv3 is always disabled and attempt to override this by the user
323 are ignored.
324 By checking the return code of SSL_CTX_cmd() it is possible to query if
326 a given cmd is recognised, this is useful is SSL_CTX_cmd() values are
327 mixed with additional application specific operations.
328 For example an application might call SSL_CTX_cmd() and if it returns
330 -2 (unrecognised command) continue with processing of application
331 specific commands.
332 Applications can also use SSL_CTX_cmd() to process command lines though
334 the utility function SSL_CTX_cmd_argv() is normally used instead. One
335 way to do this is to set the prefix to an appropriate value using
336 SSL_CONF_CTX_set1_prefix(), pass the current argument to cmd and the
337 following argument to value (which may be NULL).
338 In this case if the return value is positive then it is used to skip
340 that number of arguments as they have been processed by SSL_CTX_cmd().
341 If -2 is returned then cmd is not recognised and application specific
342 arguments can be checked instead. If -3 is returned a required argument
343 is missing and an error is indicated. If 0 is returned some other error
344 occurred and this can be reported back to the user.
345 The function SSL_CONF_cmd_value_type() can be used by applications to
347 check for the existence of a command or to perform additional syntax
348 checking or translation of the command value. For example if the return
349 value is SSL_CONF_TYPE_FILE an application could translate a relative
350 pathname to an absolute pathname.
351
353 Set supported signature algorithms:
354 SSL_CONF_cmd(ctx, "SignatureAlgorithms", "ECDSA+SHA256:RSA+SHA256:DSA+SHA256");
356 Enable all protocols except SSLv3 and SSLv2:
358 SSL_CONF_cmd(ctx, "Protocol", "ALL,-SSLv3,-SSLv2");
360 Only enable TLSv1.2:
362 SSL_CONF_cmd(ctx, "Protocol", "-ALL,TLSv1.2");
364 Disable TLS session tickets:
366 SSL_CONF_cmd(ctx, "Options", "-SessionTicket");
368 Set supported curves to P-256, P-384:
370 SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
372 Set automatic support for any elliptic curve for key exchange:
374 SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
376
378 SSL_CONF_cmd() returns 1 if the value of cmd is recognised and value is
379 NOT used and 2 if both cmd and value are used. In other words it
380 returns the number of arguments processed. This is useful when
381 processing command lines.
382 A return value of -2 means cmd is not recognised.
384 A return value of -3 means cmd is recognised and the command requires a
386 value but value is NULL.
387 A return code of 0 indicates that both cmd and value are valid but an
389 error occurred attempting to perform the operation: for example due to
390 an error in the syntax of value in this case the error queue may
391 provide additional information.
392 SSL_CONF_finish() returns 1 for success and 0 for failure.
394
396 SSL_CONF_CTX_new(3), SSL_CONF_CTX_set_flags(3),
397 SSL_CONF_CTX_set1_prefix(3), SSL_CONF_CTX_set_ssl_ctx(3),
398 SSL_CONF_cmd_argv(3)
399
401 SSL_CONF_cmd() was first added to OpenSSL 1.0.2
4021.0.2o 2020-08-01 SSL_CONF_cmd(3)