doc/man3/X509_STORE_CTX_new.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 X509_STORE_CTX_new_ex, X509_STORE_CTX_new, X509_STORE_CTX_cleanup,
   6 X509_STORE_CTX_free, X509_STORE_CTX_init,
   7 X509_STORE_CTX_init_rpk,
   8 X509_STORE_CTX_set0_trusted_stack,
   9 X509_STORE_CTX_set_cert, X509_STORE_CTX_set0_crls,
  10 X509_STORE_CTX_set0_rpk,
  11 X509_STORE_CTX_get0_param, X509_STORE_CTX_set0_param,
  12 X509_STORE_CTX_get0_untrusted, X509_STORE_CTX_set0_untrusted,
  13 X509_STORE_CTX_get_num_untrusted,
  14 X509_STORE_CTX_get0_chain, X509_STORE_CTX_set0_verified_chain,
  15 X509_STORE_CTX_get0_rpk,
  16 X509_STORE_CTX_set_default,
  17 X509_STORE_CTX_set_verify,
  18 X509_STORE_CTX_verify_fn,
  19 X509_STORE_CTX_set_purpose,
  20 X509_STORE_CTX_set_trust,
  21 X509_STORE_CTX_purpose_inherit
  22 - X509_STORE_CTX initialisation
  23
  24 =head1 SYNOPSIS
  25
  26  #include <openssl/x509_vfy.h>
  27
  28  X509_STORE_CTX *X509_STORE_CTX_new_ex(OSSL_LIB_CTX *libctx, const char *propq);
  29  X509_STORE_CTX *X509_STORE_CTX_new(void);
  30  void X509_STORE_CTX_cleanup(X509_STORE_CTX *ctx);
  31  void X509_STORE_CTX_free(X509_STORE_CTX *ctx);
  32
  33  int X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *trust_store,
  34                          X509 *target, STACK_OF(X509) *untrusted);
  35  int X509_STORE_CTX_init_rpk(X509_STORE_CTX *ctx, X509_STORE *trust_store,
  36                              EVP_PKEY *rpk);
  37
  38  void X509_STORE_CTX_set0_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
  39
  40  void X509_STORE_CTX_set_cert(X509_STORE_CTX *ctx, X509 *target);
  41  void X509_STORE_CTX_set0_crls(X509_STORE_CTX *ctx, STACK_OF(X509_CRL) *sk);
  42  void X509_STORE_CTX_set0_rpk(X509_STORE_CTX *ctx, EVP_PKEY *target);
  43
  44  X509_VERIFY_PARAM *X509_STORE_CTX_get0_param(const X509_STORE_CTX *ctx);
  45  void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param);
  46
  47  STACK_OF(X509)* X509_STORE_CTX_get0_untrusted(const X509_STORE_CTX *ctx);
  48  void X509_STORE_CTX_set0_untrusted(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
  49
  50  int X509_STORE_CTX_get_num_untrusted(const X509_STORE_CTX *ctx);
  51  STACK_OF(X509) *X509_STORE_CTX_get0_chain(const X509_STORE_CTX *ctx);
  52  void X509_STORE_CTX_set0_verified_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *chain);
  53  EVP_PKEY *X509_STORE_CTX_get0_rpk(const X509_STORE_CTX *ctx);
  54
  55  int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name);
  56  typedef int (*X509_STORE_CTX_verify_fn)(X509_STORE_CTX *);
  57  void X509_STORE_CTX_set_verify(X509_STORE_CTX *ctx, X509_STORE_CTX_verify_fn verify);
  58
  59  int X509_STORE_CTX_set_purpose(X509_STORE_CTX *ctx, int purpose);
  60  int X509_STORE_CTX_set_trust(X509_STORE_CTX *ctx, int trust);
  61  int X509_STORE_CTX_purpose_inherit(X509_STORE_CTX *ctx, int def_purpose,
  62                                     int purpose, int trust);
  63
  64 =head1 DESCRIPTION
  65
  66 These functions initialise an B<X509_STORE_CTX> structure for subsequent use
  67 by L<X509_verify_cert(3)> or L<X509_STORE_CTX_verify(3)>.
  68
  69 X509_STORE_CTX_new_ex() returns a newly initialised B<X509_STORE_CTX>
  70 structure associated with the specified library context I<libctx> and property
  71 query string I<propq>. Any cryptographic algorithms fetched while performing
  72 processing with the X509_STORE_CTX will use that library context and property
  73 query string.
  74
  75 X509_STORE_CTX_new() is the same as X509_STORE_CTX_new_ex() except that
  76 the default library context and a NULL property query string are used.
  77
  78 X509_STORE_CTX_cleanup() internally cleans up an B<X509_STORE_CTX> structure.
  79 It is used by X509_STORE_CTX_init() and X509_STORE_CTX_free().
  80
  81 X509_STORE_CTX_free() completely frees up I<ctx>. After this call I<ctx>
  82 is no longer valid.
  83 If I<ctx> is NULL nothing is done.
  84
  85 X509_STORE_CTX_init() sets up I<ctx> for a subsequent verification operation.
  86 It must be called before each call to L<X509_verify_cert(3)> or
  87 L<X509_STORE_CTX_verify(3)>, i.e., a context is only good for one verification.
  88 If you want to verify a further certificate or chain with the same I<ctx>
  89 then you must call X509_STORE_CTX_init() again.
  90 The trusted certificate store is set to I<trust_store> of type B<X509_STORE>.
  91 This may be NULL because there are no trusted certificates or because
  92 they are provided simply as a list using X509_STORE_CTX_set0_trusted_stack().
  93 The certificate to be verified is set to I<target>,
  94 and a list of additional certificates may be provided in I<untrusted>,
  95 which will be untrusted but may be used to build the chain.
  96 The I<target> certificate is not copied (its reference count is not updated),
  97 and the caller must not free it before verification is complete.
  98 Each of the I<trust_store>, I<target> and I<untrusted> parameters can be NULL.
  99 Yet note that L<X509_verify_cert(3)> and L<X509_STORE_CTX_verify(3)>
 100 will need a verification target.
 101 This can also be set using X509_STORE_CTX_set_cert().
 102 For L<X509_STORE_CTX_verify(3)>, which takes by default the first element of the
 103 list of untrusted certificates as its verification target,
 104 this can be also set indirectly using X509_STORE_CTX_set0_untrusted().
 105
 106 X509_STORE_CTX_init_rpk() sets up I<ctx> for a subsequent verification
 107 operation for the I<target> raw public key.
 108 It behaves similarly to X509_STORE_CTX_init().
 109 The I<target> raw public key can aslo be supplied separately, via
 110 X509_STORE_CTX_set0_rpk().
 111 The I<target> public key is not copied (its reference count is not updated),
 112 and the caller must not free it before verification is complete.
 113
 114 X509_STORE_CTX_set0_trusted_stack() sets the set of trusted certificates of
 115 I<ctx> to I<sk>. This is an alternative way of specifying trusted certificates
 116 instead of using an B<X509_STORE> where its complexity is not needed
 117 or to make sure that only the given set I<sk> of certificates are trusted.
 118
 119 X509_STORE_CTX_set_cert() sets the target certificate to be verified in I<ctx>
 120 to I<target>.
 121 The target certificate is not copied (its reference count is not updated),
 122 and the caller must not free it before verification is complete.
 123
 124 X509_STORE_CTX_set0_rpk() sets the target raw public key to be verified in I<ctx>
 125 to I<target>, a non-NULL raw public key preempts any target certificate, which
 126 is then ignored.
 127 The I<target> public key is not copied (its reference count is not updated),
 128 and the caller must not free it before verification is complete.
 129
 130 X509_STORE_CTX_set0_verified_chain() sets the validated chain to I<chain>.
 131 Ownership of the chain is transferred to I<ctx>,
 132 and so it should not be free'd by the caller.
 133
 134 X509_STORE_CTX_get0_chain() returns the internal pointer used by the
 135 I<ctx> that contains the constructed (output) chain.
 136
 137 X509_STORE_CTX_get0_rpk() returns the internal pointer used by the
 138 I<ctx> that contains the raw public key.
 139
 140 X509_STORE_CTX_set0_crls() sets a set of CRLs to use to aid certificate
 141 verification to I<sk>. These CRLs will only be used if CRL verification is
 142 enabled in the associated B<X509_VERIFY_PARAM> structure. This might be
 143 used where additional "useful" CRLs are supplied as part of a protocol,
 144 for example in a PKCS#7 structure.
 145
 146 X509_STORE_CTX_get0_param() retrieves an internal pointer
 147 to the verification parameters associated with I<ctx>.
 148
 149 X509_STORE_CTX_set0_param() sets the internal verification parameter pointer
 150 to I<param>. After this call B<param> should not be used.
 151
 152 X509_STORE_CTX_get0_untrusted() retrieves an internal pointer to the
 153 stack of untrusted certificates associated with I<ctx>.
 154
 155 X509_STORE_CTX_set0_untrusted() sets the internal pointer to the stack
 156 of untrusted certificates associated with I<ctx> to I<sk>.
 157 X509_STORE_CTX_verify() will take the first element, if any,
 158 as its default target if the target certificate is not set explicitly.
 159
 160 X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
 161 that were used in building the chain.
 162 This is can be used after calling L<X509_verify_cert(3)> and similar functions.
 163 With L<X509_STORE_CTX_verify(3)>, this does not count the first chain element.
 164
 165 X509_STORE_CTX_get0_chain() returns the internal pointer used by the
 166 I<ctx> that contains the validated chain.
 167
 168 Details of the chain building and checking process are described in
 169 L<openssl-verification-options(1)/Certification Path Building> and
 170 L<openssl-verification-options(1)/Certification Path Validation>.
 171
 172 X509_STORE_CTX_set0_verified_chain() sets the validated chain used
 173 by I<ctx> to be I<chain>.
 174 Ownership of the chain is transferred to I<ctx>,
 175 and so it should not be free'd by the caller.
 176
 177 X509_STORE_CTX_set_default() looks up and sets the default verification
 178 method to I<name>. This uses the function X509_VERIFY_PARAM_lookup() to
 179 find an appropriate set of parameters from the purpose identifier I<name>.
 180 Currently defined purposes are C<sslclient>, C<sslserver>, C<nssslserver>,
 181 C<smimesign>, C<smimeencrypt>, C<crlsign>, C<ocsphelper>, C<timestampsign>,
 182 and C<any>.
 183
 184 X509_STORE_CTX_set_verify() provides the capability for overriding the default
 185 verify function. This function is responsible for verifying chain signatures and
 186 expiration times.
 187
 188 A verify function is defined as an X509_STORE_CTX_verify type which has the
 189 following signature:
 190
 191  int (*verify)(X509_STORE_CTX *);
 192
 193 This function should receive the current X509_STORE_CTX as a parameter and
 194 return 1 on success or 0 on failure.
 195
 196 X509 certificates may contain information about what purposes keys contained
 197 within them can be used for. For example "TLS WWW Server Authentication" or
 198 "Email Protection". This "key usage" information is held internally to the
 199 certificate itself. In addition the trust store containing trusted certificates
 200 can declare what purposes we trust different certificates for. This "trust"
 201 information is not held within the certificate itself but is "meta" information
 202 held alongside it. This "meta" information is associated with the certificate
 203 after it is issued and could be determined by a system administrator. For
 204 example a certificate might declare that it is suitable for use for both
 205 "TLS WWW Server Authentication" and "TLS Client Authentication", but a system
 206 administrator might only trust it for the former. An X.509 certificate extension
 207 exists that can record extended key usage information to supplement the purpose
 208 information described above. This extended mechanism is arbitrarily extensible
 209 and not well suited for a generic library API; applications that need to
 210 validate extended key usage information in certificates will need to define a
 211 custom "purpose" (see below) or supply a nondefault verification callback
 212 (L<X509_STORE_set_verify_cb_func(3)>).
 213
 214 X509_STORE_CTX_set_purpose() sets the purpose for the target certificate being
 215 verified in the I<ctx>. Built-in available values for the I<purpose> argument
 216 are B<X509_PURPOSE_SSL_CLIENT>, B<X509_PURPOSE_SSL_SERVER>,
 217 B<X509_PURPOSE_NS_SSL_SERVER>, B<X509_PURPOSE_SMIME_SIGN>,
 218 B<X509_PURPOSE_SMIME_ENCRYPT>, B<X509_PURPOSE_CRL_SIGN>, B<X509_PURPOSE_ANY>,
 219 B<X509_PURPOSE_OCSP_HELPER>, B<X509_PURPOSE_TIMESTAMP_SIGN> and
 220 B<X509_PURPOSE_CODE_SIGN>.  It is also
 221 possible to create a custom purpose value. Setting a purpose requests that
 222 the key usage and extended key usage (EKU) extensions optionally declared within
 223 the certificate and its chain are verified to be consistent with that purpose.
 224 For SSL client, SSL server, and S/MIME purposes, the EKU is checked also for the
 225 CA certificates along the chain, including any given trust anchor certificate.
 226 Potentially also further checks are done (depending on the purpose given).
 227 Every purpose also has an associated default trust value, which will also be set
 228 at the same time. During verification, this trust setting will be verified
 229 to check whether it is consistent with the trust set by the system administrator
 230 for certificates in the chain.
 231
 232 X509_STORE_CTX_set_trust() sets the trust value for the target certificate
 233 being verified in the I<ctx>. Built-in available values for the I<trust>
 234 argument are B<X509_TRUST_COMPAT>, B<X509_TRUST_SSL_CLIENT>,
 235 B<X509_TRUST_SSL_SERVER>, B<X509_TRUST_EMAIL>, B<X509_TRUST_OBJECT_SIGN>,
 236 B<X509_TRUST_OCSP_SIGN>, B<X509_TRUST_OCSP_REQUEST> and B<X509_TRUST_TSA>. It is
 237 also possible to create a custom trust value. Since X509_STORE_CTX_set_purpose()
 238 also sets the trust value it is normally sufficient to only call that function.
 239 If both are called then X509_STORE_CTX_set_trust() should be called after
 240 X509_STORE_CTX_set_purpose() since the trust setting of the last call will be
 241 used.
 242
 243 It should not normally be necessary for end user applications to call
 244 X509_STORE_CTX_purpose_inherit() directly. Typically applications should call
 245 X509_STORE_CTX_set_purpose() or X509_STORE_CTX_set_trust() instead. Using this
 246 function it is possible to set the purpose and trust values for the I<ctx> at
 247 the same time.
 248 Both I<ctx> and its internal verification parameter pointer must not be NULL.
 249 The I<def_purpose> and I<purpose> arguments can have the same
 250 purpose values as described for X509_STORE_CTX_set_purpose() above. The I<trust>
 251 argument can have the same trust values as described in
 252 X509_STORE_CTX_set_trust() above. Any of the I<def_purpose>, I<purpose> or
 253 I<trust> values may also have the value 0 to indicate that the supplied
 254 parameter should be ignored. After calling this function the purpose to be used
 255 for verification is set from the I<purpose> argument unless the purpose was
 256 already set in I<ctx> before, and the trust is set from the I<trust> argument
 257 unless the trust was already set in I<ctx> before.
 258 If I<trust> is 0 then the trust value will be set from
 259 the default trust value for I<purpose>. If the default trust value for the
 260 purpose is I<X509_TRUST_DEFAULT> and I<trust> is 0 then the default trust value
 261 associated with the I<def_purpose> value is used for the trust setting instead.
 262
 263 =head1 NOTES
 264
 265 The certificates and CRLs in a store are used internally and should B<not>
 266 be freed up until after the associated B<X509_STORE_CTX> is freed.
 267
 268 =head1 BUGS
 269
 270 The certificates and CRLs in a context are used internally and should B<not>
 271 be freed up until after the associated B<X509_STORE_CTX> is freed. Copies
 272 should be made or reference counts increased instead.
 273
 274 =head1 RETURN VALUES
 275
 276 X509_STORE_CTX_new() returns a newly allocated context or NULL if an
 277 error occurred.
 278
 279 X509_STORE_CTX_init() and X509_STORE_CTX_init_rpk() return 1 for success
 280 or 0 if an error occurred.
 281
 282 X509_STORE_CTX_get0_param() returns a pointer to an B<X509_VERIFY_PARAM>
 283 structure or NULL if an error occurred.
 284
 285 X509_STORE_CTX_get0_rpk() returns a pointer to an B<EVP_PKEY> structure if
 286 present, or NULL if absent.
 287
 288 X509_STORE_CTX_cleanup(), X509_STORE_CTX_free(),
 289 X509_STORE_CTX_set0_trusted_stack(),
 290 X509_STORE_CTX_set_cert(),
 291 X509_STORE_CTX_set0_crls() and X509_STORE_CTX_set0_param() do not return
 292 values.
 293
 294 X509_STORE_CTX_set_default() returns 1 for success or 0 if an error occurred.
 295
 296 X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
 297 used.
 298
 299 =head1 SEE ALSO
 300
 301 L<X509_verify_cert(3)>, L<X509_STORE_CTX_verify(3)>,
 302 L<X509_VERIFY_PARAM_set_flags(3)>
 303
 304 =head1 HISTORY
 305
 306 The X509_STORE_CTX_set0_crls() function was added in OpenSSL 1.0.0.
 307 The X509_STORE_CTX_get_num_untrusted() function was added in OpenSSL 1.1.0.
 308 The X509_STORE_CTX_new_ex() function was added in OpenSSL 3.0.
 309 The X509_STORE_CTX_init_rpk(), X509_STORE_CTX_get0_rpk(), and
 310 X509_STORE_CTX_set0_rpk() functions were added in OpenSSL 3.2.
 311
 312 There is no need to call X509_STORE_CTX_cleanup() explicitly since OpenSSL 3.0.
 313
 314 =head1 COPYRIGHT
 315
 316 Copyright 2009-2023 The OpenSSL Project Authors. All Rights Reserved.
 317
 318 Licensed under the Apache License 2.0 (the "License").  You may not use
 319 this file except in compliance with the License.  You can obtain a copy
 320 in the file LICENSE in the source distribution or at
 321 L<https://www.openssl.org/source/license.html>.
 322
 323 =cut