xref: /freebsd/crypto/openssl/doc/man3/X509_VERIFY_PARAM_set_flags.pod (revision 52c2bb75163559a6e2866ad374a7de67a4ea1273) 
1=pod
2
3=head1 NAME
4
5X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags,
6X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose,
7X509_VERIFY_PARAM_get_inh_flags, X509_VERIFY_PARAM_set_inh_flags,
8X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth,
9X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_auth_level,
10X509_VERIFY_PARAM_get_auth_level, X509_VERIFY_PARAM_set_time,
11X509_VERIFY_PARAM_get_time,
12X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies,
13X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host,
14X509_VERIFY_PARAM_set_hostflags,
15X509_VERIFY_PARAM_get_hostflags,
16X509_VERIFY_PARAM_get0_peername,
17X509_VERIFY_PARAM_set1_email, X509_VERIFY_PARAM_set1_ip,
18X509_VERIFY_PARAM_set1_ip_asc
19- X509 verification parameters
20
21=head1 SYNOPSIS
22
23 #include <openssl/x509_vfy.h>
24
25 int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
26                                 unsigned long flags);
27 int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
28                                   unsigned long flags);
29 unsigned long X509_VERIFY_PARAM_get_flags(X509_VERIFY_PARAM *param);
30
31 int X509_VERIFY_PARAM_set_inh_flags(X509_VERIFY_PARAM *param,
32                                     uint32_t flags);
33 uint32_t X509_VERIFY_PARAM_get_inh_flags(const X509_VERIFY_PARAM *param);
34
35 int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
36 int X509_VERIFY_PARAM_set_trust(X509_VERIFY_PARAM *param, int trust);
37
38 void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
39 time_t X509_VERIFY_PARAM_get_time(const X509_VERIFY_PARAM *param);
40
41 int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
42                                   ASN1_OBJECT *policy);
43 int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param,
44                                     STACK_OF(ASN1_OBJECT) *policies);
45
46 void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
47 int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);
48
49 void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
50                                       int auth_level);
51 int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);
52
53 int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
54                                 const char *name, size_t namelen);
55 int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
56                                 const char *name, size_t namelen);
57 void X509_VERIFY_PARAM_set_hostflags(X509_VERIFY_PARAM *param,
58                                      unsigned int flags);
59 unsigned int X509_VERIFY_PARAM_get_hostflags(const X509_VERIFY_PARAM *param);
60 char *X509_VERIFY_PARAM_get0_peername(X509_VERIFY_PARAM *param);
61 int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
62                                  const char *email, size_t emaillen);
63 int X509_VERIFY_PARAM_set1_ip(X509_VERIFY_PARAM *param,
64                               const unsigned char *ip, size_t iplen);
65 int X509_VERIFY_PARAM_set1_ip_asc(X509_VERIFY_PARAM *param, const char *ipasc);
66
67=head1 DESCRIPTION
68
69These functions manipulate the B<X509_VERIFY_PARAM> structure associated with
70a certificate verification operation.
71
72The X509_VERIFY_PARAM_set_flags() function sets the flags in B<param> by oring
73it with B<flags>. See the B<VERIFICATION FLAGS> section for a complete
74description of values the B<flags> parameter can take.
75
76X509_VERIFY_PARAM_get_flags() returns the flags in B<param>.
77
78X509_VERIFY_PARAM_get_inh_flags() returns the inheritance flags in B<param>
79which specifies how verification flags are copied from one structure to
80another. X509_VERIFY_PARAM_set_inh_flags() sets the inheritance flags.
81See the B<INHERITANCE FLAGS> section for a description of these bits.
82
83X509_VERIFY_PARAM_clear_flags() clears the flags B<flags> in B<param>.
84
85X509_VERIFY_PARAM_set_purpose() sets the verification purpose in B<param>
86to B<purpose>. This determines the acceptable purpose of the certificate
87chain, for example SSL client or SSL server.
88
89X509_VERIFY_PARAM_set_trust() sets the trust setting in B<param> to
90B<trust>.
91
92X509_VERIFY_PARAM_set_time() sets the verification time in B<param> to
93B<t>. Normally the current time is used.
94
95X509_VERIFY_PARAM_add0_policy() enables policy checking (it is disabled
96by default) and adds B<policy> to the acceptable policy set.
97
98X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled
99by default) and sets the acceptable policy set to B<policies>. Any existing
100policy set is cleared. The B<policies> parameter can be B<NULL> to clear
101an existing policy set.
102
103X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>.
104That is the maximum number of intermediate CA certificates that can appear in a
105chain.
106A maximal depth chain contains 2 more certificates than the limit, since
107neither the end-entity certificate nor the trust-anchor count against this
108limit.
109Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed
110directly by the trust-anchor, while with a B<depth> limit of 1 there can be one
111intermediate CA certificate between the trust-anchor and the end-entity
112certificate.
113
114X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to
115B<auth_level>.
116The authentication security level determines the acceptable signature and public
117key strength when verifying certificate chains.
118For a certificate chain to validate, the public keys of all the certificates
119must meet the specified security level.
120The signature algorithm security level is not enforced for the chain's I<trust
121anchor> certificate, which is either directly trusted or validated by means other
122than its signature.
123See L<SSL_CTX_set_security_level(3)> for the definitions of the available
124levels.
125The default security level is -1, or "not set".
126At security level 0 or lower all algorithms are acceptable.
127Security level 1 requires at least 80-bit-equivalent security and is broadly
128interoperable, though it will, for example, reject MD5 signatures or RSA keys
129shorter than 1024 bits.
130
131X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to
132B<name> clearing any previously specified host name or names.  If
133B<name> is NULL, or empty the list of hostnames is cleared, and
134name checks are not performed on the peer certificate.  If B<name>
135is NUL-terminated, B<namelen> may be zero, otherwise B<namelen>
136must be set to the length of B<name>.
137
138When a hostname is specified,
139certificate verification automatically invokes L<X509_check_host(3)>
140with flags equal to the B<flags> argument given to
141X509_VERIFY_PARAM_set_hostflags() (default zero).  Applications
142are strongly advised to use this interface in preference to explicitly
143calling L<X509_check_host(3)>, hostname checks may be out of scope
144with the DANE-EE(3) certificate usage, and the internal check will
145be suppressed as appropriate when DANE verification is enabled.
146
147When the subject CommonName will not be ignored, whether as a result of the
148B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> host flag, or because no DNS subject
149alternative names are present in the certificate, any DNS name constraints in
150issuer certificates apply to the subject CommonName as well as the subject
151alternative name extension.
152
153When the subject CommonName will be ignored, whether as a result of the
154B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> host flag, or because some DNS subject
155alternative names are present in the certificate, DNS name constraints in
156issuer certificates will not be applied to the subject DN.
157As described in X509_check_host(3) the B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT>
158flag takes precedence over the B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag.
159
160X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a
161call to X509_VERIFY_PARAM_set_hostflags().
162
163X509_VERIFY_PARAM_add1_host() adds B<name> as an additional reference
164identifier that can match the peer's certificate.  Any previous names
165set via X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host()
166are retained, no change is made if B<name> is NULL or empty.  When
167multiple names are configured, the peer is considered verified when
168any name matches.
169
170X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject
171CommonName from the peer certificate that matched one of the reference
172identifiers.  When wildcard matching is not disabled, or when a
173reference identifier specifies a parent domain (starts with ".")
174rather than a hostname, the peer name may be a wildcard name or a
175sub-domain of the reference identifier respectively.  The return
176string is allocated by the library and is no longer valid once the
177associated B<param> argument is freed.  Applications must not free
178the return value.
179
180X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to
181B<email>.  If B<email> is NUL-terminated, B<emaillen> may be zero, otherwise
182B<emaillen> must be set to the length of B<email>.  When an email address
183is specified, certificate verification automatically invokes
184L<X509_check_email(3)>.
185
186X509_VERIFY_PARAM_set1_ip() sets the expected IP address to B<ip>.
187The B<ip> argument is in binary format, in network byte-order and
188B<iplen> must be set to 4 for IPv4 and 16 for IPv6.  When an IP
189address is specified, certificate verification automatically invokes
190L<X509_check_ip(3)>.
191
192X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to
193B<ipasc>.  The B<ipasc> argument is a NUL-terminal ASCII string:
194dotted decimal quad for IPv4 and colon-separated hexadecimal for
195IPv6.  The condensed "::" notation is supported for IPv6 addresses.
196
197=head1 RETURN VALUES
198
199X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(),
200X509_VERIFY_PARAM_set_inh_flags(),
201X509_VERIFY_PARAM_set_purpose(), X509_VERIFY_PARAM_set_trust(),
202X509_VERIFY_PARAM_add0_policy() X509_VERIFY_PARAM_set1_policies(),
203X509_VERIFY_PARAM_set1_host(), X509_VERIFY_PARAM_add1_host(),
204X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip() and
205X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for
206failure.
207
208X509_VERIFY_PARAM_get_flags() returns the current verification flags.
209
210X509_VERIFY_PARAM_get_hostflags() returns any current host flags.
211
212X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags.
213
214X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return
215values.
216
217X509_VERIFY_PARAM_get_depth() returns the current verification depth.
218
219X509_VERIFY_PARAM_get_auth_level() returns the current authentication security
220level.
221
222=head1 VERIFICATION FLAGS
223
224The verification flags consists of zero or more of the following flags
225ored together.
226
227B<X509_V_FLAG_CRL_CHECK> enables CRL checking for the certificate chain leaf
228certificate. An error occurs if a suitable CRL cannot be found.
229
230B<X509_V_FLAG_CRL_CHECK_ALL> enables CRL checking for the entire certificate
231chain.
232
233B<X509_V_FLAG_IGNORE_CRITICAL> disabled critical extension checking. By default
234any unhandled critical extensions in certificates or (if checked) CRLs results
235in a fatal error. If this flag is set unhandled critical extensions are
236ignored. B<WARNING> setting this option for anything other than debugging
237purposes can be a security risk. Finer control over which extensions are
238supported can be performed in the verification callback.
239
240The B<X509_V_FLAG_X509_STRICT> flag disables workarounds for some broken
241certificates and makes the verification strictly apply B<X509> rules.
242
243B<X509_V_FLAG_ALLOW_PROXY_CERTS> enables proxy certificate verification.
244
245B<X509_V_FLAG_POLICY_CHECK> enables certificate policy checking, by default
246no policy checking is performed. Additional information is sent to the
247verification callback relating to policy checking.
248
249B<X509_V_FLAG_EXPLICIT_POLICY>, B<X509_V_FLAG_INHIBIT_ANY> and
250B<X509_V_FLAG_INHIBIT_MAP> set the B<require explicit policy>, B<inhibit any
251policy> and B<inhibit policy mapping> flags respectively as defined in
252B<RFC3280>. Policy checking is automatically enabled if any of these flags
253are set.
254
255If B<X509_V_FLAG_NOTIFY_POLICY> is set and the policy checking is successful
256a special status code is set to the verification callback. This permits it
257to examine the valid policy tree and perform additional checks or simply
258log it for debugging purposes.
259
260By default some additional features such as indirect CRLs and CRLs signed by
261different keys are disabled. If B<X509_V_FLAG_EXTENDED_CRL_SUPPORT> is set
262they are enabled.
263
264If B<X509_V_FLAG_USE_DELTAS> is set delta CRLs (if present) are used to
265determine certificate status. If not set deltas are ignored.
266
267B<X509_V_FLAG_CHECK_SS_SIGNATURE> enables checking of the root CA self signed
268certificate signature. By default this check is disabled because it doesn't
269add any additional security but in some cases applications might want to
270check the signature anyway. A side effect of not checking the root CA
271signature is that disabled or unsupported message digests on the root CA
272are not treated as fatal errors.
273
274When B<X509_V_FLAG_TRUSTED_FIRST> is set, construction of the certificate chain
275in L<X509_verify_cert(3)> will search the trust store for issuer certificates
276before searching the provided untrusted certificates.
277Local issuer certificates are often more likely to satisfy local security
278requirements and lead to a locally trusted root.
279This is especially important when some certificates in the trust store have
280explicit trust settings (see "TRUST SETTINGS" in L<x509(1)>).
281As of OpenSSL 1.1.0 this option is on by default.
282
283The B<X509_V_FLAG_NO_ALT_CHAINS> flag suppresses checking for alternative
284chains.
285By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a
286certificate chain, if the first certificate chain found is not trusted, then
287OpenSSL will attempt to replace untrusted certificates supplied by the peer
288with certificates from the trust store to see if an alternative chain can be
289found that is trusted.
290As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option
291has no effect.
292
293The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes intermediate certificates in the
294trust store to be treated as trust-anchors, in the same way as the self-signed
295root CA certificates.
296This makes it possible to trust certificates issued by an intermediate CA
297without having to trust its ancestor root CA.
298With OpenSSL 1.1.0 and later and <X509_V_FLAG_PARTIAL_CHAIN> set, chain
299construction stops as soon as the first certificate from the trust store is
300added to the chain, whether that certificate is a self-signed "root"
301certificate or a not self-signed intermediate certificate.
302Thus, when an intermediate certificate is found in the trust store, the
303verified chain passed to callbacks may be shorter than it otherwise would
304be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag.
305
306The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period
307of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time()
308is used to specify a verification time, the check is not suppressed.
309
310=head1 INHERITANCE FLAGS
311
312These flags specify how parameters are "inherited" from one structure to
313another.
314
315If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed
316after the next call.
317
318If B<X509_VP_FLAG_LOCKED> is set then no values are copied.  This overrides
319all of the following flags.
320
321If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied
322to the destination. Effectively the values in "to" become default values
323which will be used only if nothing new is set in "from".  This is the
324default.
325
326If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether
327they are set or not. Flags is still Ored though.
328
329If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead
330of ORed.
331
332=head1 NOTES
333
334The above functions should be used to manipulate verification parameters
335instead of functions which work in specific structures such as
336X509_STORE_CTX_set_flags() which are likely to be deprecated in a future
337release.
338
339=head1 BUGS
340
341Delta CRL checking is currently primitive. Only a single delta can be used and
342(partly due to limitations of B<X509_STORE>) constructed CRLs are not
343maintained.
344
345If CRLs checking is enable CRLs are expected to be available in the
346corresponding B<X509_STORE> structure. No attempt is made to download
347CRLs from the CRL distribution points extension.
348
349=head1 EXAMPLE
350
351Enable CRL checking when performing certificate verification during SSL
352connections associated with an B<SSL_CTX> structure B<ctx>:
353
354 X509_VERIFY_PARAM *param;
355
356 param = X509_VERIFY_PARAM_new();
357 X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
358 SSL_CTX_set1_param(ctx, param);
359 X509_VERIFY_PARAM_free(param);
360
361=head1 SEE ALSO
362
363L<X509_verify_cert(3)>,
364L<X509_check_host(3)>,
365L<X509_check_email(3)>,
366L<X509_check_ip(3)>,
367L<x509(1)>
368
369=head1 HISTORY
370
371The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0.
372The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0
373and has no effect.
374
375The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i.
376
377=head1 COPYRIGHT
378
379Copyright 2009-2018 The OpenSSL Project Authors. All Rights Reserved.
380
381Licensed under the OpenSSL license (the "License").  You may not use
382this file except in compliance with the License.  You can obtain a copy
383in the file LICENSE in the source distribution or at
384L<https://www.openssl.org/source/license.html>.
385
386=cut
387