xref: /freebsd/crypto/openssl/doc/man3/X509_STORE_CTX_new.pod (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf) 
1=pod
2
3=head1 NAME
4
5X509_STORE_CTX_new_ex, X509_STORE_CTX_new, X509_STORE_CTX_cleanup,
6X509_STORE_CTX_free, X509_STORE_CTX_init, X509_STORE_CTX_set0_trusted_stack,
7X509_STORE_CTX_set_cert, X509_STORE_CTX_set0_crls,
8X509_STORE_CTX_get0_param, X509_STORE_CTX_set0_param,
9X509_STORE_CTX_get0_untrusted, X509_STORE_CTX_set0_untrusted,
10X509_STORE_CTX_get_num_untrusted,
11X509_STORE_CTX_get0_chain, X509_STORE_CTX_set0_verified_chain,
12X509_STORE_CTX_set_default,
13X509_STORE_CTX_set_verify,
14X509_STORE_CTX_verify_fn,
15X509_STORE_CTX_set_purpose,
16X509_STORE_CTX_set_trust,
17X509_STORE_CTX_purpose_inherit
18- X509_STORE_CTX initialisation
19
20=head1 SYNOPSIS
21
22 #include <openssl/x509_vfy.h>
23
24 X509_STORE_CTX *X509_STORE_CTX_new_ex(OSSL_LIB_CTX *libctx, const char *propq);
25 X509_STORE_CTX *X509_STORE_CTX_new(void);
26 void X509_STORE_CTX_cleanup(X509_STORE_CTX *ctx);
27 void X509_STORE_CTX_free(X509_STORE_CTX *ctx);
28
29 int X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *trust_store,
30                         X509 *target, STACK_OF(X509) *untrusted);
31
32 void X509_STORE_CTX_set0_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
33
34 void X509_STORE_CTX_set_cert(X509_STORE_CTX *ctx, X509 *target);
35 void X509_STORE_CTX_set0_crls(X509_STORE_CTX *ctx, STACK_OF(X509_CRL) *sk);
36
37 X509_VERIFY_PARAM *X509_STORE_CTX_get0_param(const X509_STORE_CTX *ctx);
38 void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param);
39
40 STACK_OF(X509)* X509_STORE_CTX_get0_untrusted(const X509_STORE_CTX *ctx);
41 void X509_STORE_CTX_set0_untrusted(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
42
43 int X509_STORE_CTX_get_num_untrusted(const X509_STORE_CTX *ctx);
44 STACK_OF(X509) *X509_STORE_CTX_get0_chain(const X509_STORE_CTX *ctx);
45 void X509_STORE_CTX_set0_verified_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *chain);
46
47 int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name);
48 typedef int (*X509_STORE_CTX_verify_fn)(X509_STORE_CTX *);
49 void X509_STORE_CTX_set_verify(X509_STORE_CTX *ctx, X509_STORE_CTX_verify_fn verify);
50
51 int X509_STORE_CTX_set_purpose(X509_STORE_CTX *ctx, int purpose);
52 int X509_STORE_CTX_set_trust(X509_STORE_CTX *ctx, int trust);
53 int X509_STORE_CTX_purpose_inherit(X509_STORE_CTX *ctx, int def_purpose,
54                                    int purpose, int trust);
55
56=head1 DESCRIPTION
57
58These functions initialise an B<X509_STORE_CTX> structure for subsequent use
59by L<X509_verify_cert(3)> or L<X509_STORE_CTX_verify(3)>.
60
61X509_STORE_CTX_new_ex() returns a newly initialised B<X509_STORE_CTX>
62structure associated with the specified library context I<libctx> and property
63query string I<propq>. Any cryptographic algorithms fetched while performing
64processing with the X509_STORE_CTX will use that library context and property
65query string.
66
67X509_STORE_CTX_new() is the same as X509_STORE_CTX_new_ex() except that
68the default library context and a NULL property query string are used.
69
70X509_STORE_CTX_cleanup() internally cleans up an B<X509_STORE_CTX> structure.
71It is used by X509_STORE_CTX_init() and X509_STORE_CTX_free().
72
73X509_STORE_CTX_free() completely frees up I<ctx>. After this call I<ctx>
74is no longer valid.
75If I<ctx> is NULL nothing is done.
76
77It must be called before each call to L<X509_verify_cert(3)> or
78L<X509_STORE_CTX_verify(3)>, i.e., a context is only good for one verification.
79If you want to verify a further certificate or chain with the same I<ctx>
80then you must call X509_STORE_CTX_init() again.
81The trusted certificate store is set to I<trust_store> of type B<X509_STORE>.
82This may be NULL because there are no trusted certificates or because
83they are provided simply as a list using X509_STORE_CTX_set0_trusted_stack().
84The certificate to be verified is set to I<target>,
85and a list of additional certificates may be provided in I<untrusted>,
86which will be untrusted but may be used to build the chain.
87Each of the I<trust_store>, I<target> and I<untrusted> parameters can be NULL.
88Yet note that L<X509_verify_cert(3)> and L<X509_STORE_CTX_verify(3)>
89will need a verification target.
90This can also be set using X509_STORE_CTX_set_cert().
91For L<X509_STORE_CTX_verify(3)>, which takes by default the first element of the
92list of untrusted certificates as its verification target,
93this can be also set indirectly using X509_STORE_CTX_set0_untrusted().
94
95X509_STORE_CTX_set0_trusted_stack() sets the set of trusted certificates of
96I<ctx> to I<sk>. This is an alternative way of specifying trusted certificates
97instead of using an B<X509_STORE> where its complexity is not needed
98or to make sure that only the given set I<sk> of certificates are trusted.
99
100X509_STORE_CTX_set_cert() sets the target certificate to be verified in I<ctx>
101to I<target>.
102
103X509_STORE_CTX_set0_verified_chain() sets the validated chain to I<chain>.
104Ownership of the chain is transferred to I<ctx>,
105and so it should not be free'd by the caller.
106
107X509_STORE_CTX_get0_chain() returns the internal pointer used by the
108I<ctx> that contains the constructed (output) chain.
109
110X509_STORE_CTX_set0_crls() sets a set of CRLs to use to aid certificate
111verification to I<sk>. These CRLs will only be used if CRL verification is
112enabled in the associated B<X509_VERIFY_PARAM> structure. This might be
113used where additional "useful" CRLs are supplied as part of a protocol,
114for example in a PKCS#7 structure.
115
116X509_STORE_CTX_get0_param() retrieves an internal pointer
117to the verification parameters associated with I<ctx>.
118
119X509_STORE_CTX_set0_param() sets the internal verification parameter pointer
120to I<param>. After this call B<param> should not be used.
121
122X509_STORE_CTX_get0_untrusted() retrieves an internal pointer to the
123stack of untrusted certificates associated with I<ctx>.
124
125X509_STORE_CTX_set0_untrusted() sets the internal pointer to the stack
126of untrusted certificates associated with I<ctx> to I<sk>.
127X509_STORE_CTX_verify() will take the first element, if any,
128as its default target if the target certificate is not set explicitly.
129
130X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
131that were used in building the chain.
132This is can be used after calling L<X509_verify_cert(3)> and similar functions.
133With L<X509_STORE_CTX_verify(3)>, this does not count the first chain element.
134
135X509_STORE_CTX_get0_chain() returns the internal pointer used by the
136I<ctx> that contains the validated chain.
137
138Details of the chain building and checking process are described in
139L<openssl-verification-options(1)/Certification Path Building> and
140L<openssl-verification-options(1)/Certification Path Validation>.
141
142X509_STORE_CTX_set0_verified_chain() sets the validated chain used
143by I<ctx> to be I<chain>.
144Ownership of the chain is transferred to I<ctx>,
145and so it should not be free'd by the caller.
146
147X509_STORE_CTX_set_default() looks up and sets the default verification
148method to I<name>. This uses the function X509_VERIFY_PARAM_lookup() to
149find an appropriate set of parameters from the purpose identifier I<name>.
150Currently defined purposes are C<sslclient>, C<sslserver>, C<nssslserver>,
151C<smimesign>, C<smimeencrypt>, C<crlsign>, C<ocsphelper>, C<timestampsign>,
152and C<any>.
153
154X509_STORE_CTX_set_verify() provides the capability for overriding the default
155verify function. This function is responsible for verifying chain signatures and
156expiration times.
157
158A verify function is defined as an X509_STORE_CTX_verify type which has the
159following signature:
160
161 int (*verify)(X509_STORE_CTX *);
162
163This function should receive the current X509_STORE_CTX as a parameter and
164return 1 on success or 0 on failure.
165
166X509 certificates may contain information about what purposes keys contained
167within them can be used for. For example "TLS WWW Server Authentication" or
168"Email Protection". This "key usage" information is held internally to the
169certificate itself. In addition the trust store containing trusted certificates
170can declare what purposes we trust different certificates for. This "trust"
171information is not held within the certificate itself but is "meta" information
172held alongside it. This "meta" information is associated with the certificate
173after it is issued and could be determined by a system administrator. For
174example a certificate might declare that it is suitable for use for both
175"TLS WWW Server Authentication" and "TLS Client Authentication", but a system
176administrator might only trust it for the former. An X.509 certificate extension
177exists that can record extended key usage information to supplement the purpose
178information described above. This extended mechanism is arbitrarily extensible
179and not well suited for a generic library API; applications that need to
180validate extended key usage information in certificates will need to define a
181custom "purpose" (see below) or supply a nondefault verification callback
182(L<X509_STORE_set_verify_cb_func(3)>).
183
184X509_STORE_CTX_set_purpose() sets the purpose for the target certificate being
185verified in the I<ctx>. Built-in available values for the I<purpose> argument
186are B<X509_PURPOSE_SSL_CLIENT>, B<X509_PURPOSE_SSL_SERVER>,
187B<X509_PURPOSE_NS_SSL_SERVER>, B<X509_PURPOSE_SMIME_SIGN>,
188B<X509_PURPOSE_SMIME_ENCRYPT>, B<X509_PURPOSE_CRL_SIGN>, B<X509_PURPOSE_ANY>,
189B<X509_PURPOSE_OCSP_HELPER> and B<X509_PURPOSE_TIMESTAMP_SIGN>. It is also
190possible to create a custom purpose value. Setting a purpose will ensure that
191the key usage declared within certificates in the chain being verified is
192consistent with that purpose as well as, potentially, other checks. Every
193purpose also has an associated default trust value which will also be set at the
194same time. During verification this trust setting will be verified to check it
195is consistent with the trust set by the system administrator for certificates in
196the chain.
197
198X509_STORE_CTX_set_trust() sets the trust value for the target certificate
199being verified in the I<ctx>. Built-in available values for the I<trust>
200argument are B<X509_TRUST_COMPAT>, B<X509_TRUST_SSL_CLIENT>,
201B<X509_TRUST_SSL_SERVER>, B<X509_TRUST_EMAIL>, B<X509_TRUST_OBJECT_SIGN>,
202B<X509_TRUST_OCSP_SIGN>, B<X509_TRUST_OCSP_REQUEST> and B<X509_TRUST_TSA>. It is
203also possible to create a custom trust value. Since X509_STORE_CTX_set_purpose()
204also sets the trust value it is normally sufficient to only call that function.
205If both are called then X509_STORE_CTX_set_trust() should be called after
206X509_STORE_CTX_set_purpose() since the trust setting of the last call will be
207used.
208
209It should not normally be necessary for end user applications to call
210X509_STORE_CTX_purpose_inherit() directly. Typically applications should call
211X509_STORE_CTX_set_purpose() or X509_STORE_CTX_set_trust() instead. Using this
212function it is possible to set the purpose and trust values for the I<ctx> at
213the same time.
214Both I<ctx> and its internal verification parameter pointer must not be NULL.
215The I<def_purpose> and I<purpose> arguments can have the same
216purpose values as described for X509_STORE_CTX_set_purpose() above. The I<trust>
217argument can have the same trust values as described in
218X509_STORE_CTX_set_trust() above. Any of the I<def_purpose>, I<purpose> or
219I<trust> values may also have the value 0 to indicate that the supplied
220parameter should be ignored. After calling this function the purpose to be used
221for verification is set from the I<purpose> argument unless the purpose was
222already set in I<ctx> before, and the trust is set from the I<trust> argument
223unless the trust was already set in I<ctx> before.
224If I<trust> is 0 then the trust value will be set from
225the default trust value for I<purpose>. If the default trust value for the
226purpose is I<X509_TRUST_DEFAULT> and I<trust> is 0 then the default trust value
227associated with the I<def_purpose> value is used for the trust setting instead.
228
229=head1 NOTES
230
231The certificates and CRLs in a store are used internally and should B<not>
232be freed up until after the associated B<X509_STORE_CTX> is freed.
233
234=head1 BUGS
235
236The certificates and CRLs in a context are used internally and should B<not>
237be freed up until after the associated B<X509_STORE_CTX> is freed. Copies
238should be made or reference counts increased instead.
239
240=head1 RETURN VALUES
241
242X509_STORE_CTX_new() returns a newly allocated context or NULL if an
243error occurred.
244
245X509_STORE_CTX_init() returns 1 for success or 0 if an error occurred.
246
247X509_STORE_CTX_get0_param() returns a pointer to an B<X509_VERIFY_PARAM>
248structure or NULL if an error occurred.
249
250X509_STORE_CTX_cleanup(), X509_STORE_CTX_free(),
251X509_STORE_CTX_set0_trusted_stack(),
252X509_STORE_CTX_set_cert(),
253X509_STORE_CTX_set0_crls() and X509_STORE_CTX_set0_param() do not return
254values.
255
256X509_STORE_CTX_set_default() returns 1 for success or 0 if an error occurred.
257
258X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
259used.
260
261=head1 SEE ALSO
262
263L<X509_verify_cert(3)>, L<X509_STORE_CTX_verify(3)>,
264L<X509_VERIFY_PARAM_set_flags(3)>
265
266=head1 HISTORY
267
268The X509_STORE_CTX_set0_crls() function was added in OpenSSL 1.0.0.
269The X509_STORE_CTX_get_num_untrusted() function was added in OpenSSL 1.1.0.
270The X509_STORE_CTX_new_ex() function was added in OpenSSL 3.0.
271
272There is no need to call X509_STORE_CTX_cleanup() explicitly since OpenSSL 3.0.
273
274=head1 COPYRIGHT
275
276Copyright 2009-2023 The OpenSSL Project Authors. All Rights Reserved.
277
278Licensed under the Apache License 2.0 (the "License").  You may not use
279this file except in compliance with the License.  You can obtain a copy
280in the file LICENSE in the source distribution or at
281L<https://www.openssl.org/source/license.html>.
282
283=cut
284