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() adds B<policy> to the acceptable policy set. 96Contrary to preexisting documentation of this function it does not enable 97policy checking. 98 99X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled 100by default) and sets the acceptable policy set to B<policies>. Any existing 101policy set is cleared. The B<policies> parameter can be B<NULL> to clear 102an existing policy set. 103 104X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>. 105That is the maximum number of intermediate CA certificates that can appear in a 106chain. 107A maximal depth chain contains 2 more certificates than the limit, since 108neither the end-entity certificate nor the trust-anchor count against this 109limit. 110Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed 111directly by the trust-anchor, while with a B<depth> limit of 1 there can be one 112intermediate CA certificate between the trust-anchor and the end-entity 113certificate. 114 115X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to 116B<auth_level>. 117The authentication security level determines the acceptable signature and public 118key strength when verifying certificate chains. 119For a certificate chain to validate, the public keys of all the certificates 120must meet the specified security level. 121The signature algorithm security level is not enforced for the chain's I<trust 122anchor> certificate, which is either directly trusted or validated by means other 123than its signature. 124See L<SSL_CTX_set_security_level(3)> for the definitions of the available 125levels. 126The default security level is -1, or "not set". 127At security level 0 or lower all algorithms are acceptable. 128Security level 1 requires at least 80-bit-equivalent security and is broadly 129interoperable, though it will, for example, reject MD5 signatures or RSA keys 130shorter than 1024 bits. 131 132X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to 133B<name> clearing any previously specified hostname or names. If 134B<name> is NULL, or empty the list of hostnames is cleared, and 135name checks are not performed on the peer certificate. If B<name> 136is NUL-terminated, B<namelen> may be zero, otherwise B<namelen> 137must be set to the length of B<name>. 138 139When a hostname is specified, 140certificate verification automatically invokes L<X509_check_host(3)> 141with flags equal to the B<flags> argument given to 142X509_VERIFY_PARAM_set_hostflags() (default zero). Applications 143are strongly advised to use this interface in preference to explicitly 144calling L<X509_check_host(3)>, hostname checks may be out of scope 145with the DANE-EE(3) certificate usage, and the internal check will 146be suppressed as appropriate when DANE verification is enabled. 147 148When the subject CommonName will not be ignored, whether as a result of the 149B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> host flag, or because no DNS subject 150alternative names are present in the certificate, any DNS name constraints in 151issuer certificates apply to the subject CommonName as well as the subject 152alternative name extension. 153 154When the subject CommonName will be ignored, whether as a result of the 155B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> host flag, or because some DNS subject 156alternative names are present in the certificate, DNS name constraints in 157issuer certificates will not be applied to the subject DN. 158As described in X509_check_host(3) the B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> 159flag takes precedence over the B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag. 160 161X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a 162call to X509_VERIFY_PARAM_set_hostflags(). 163 164X509_VERIFY_PARAM_add1_host() adds B<name> as an additional reference 165identifier that can match the peer's certificate. Any previous names 166set via X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host() 167are retained, no change is made if B<name> is NULL or empty. When 168multiple names are configured, the peer is considered verified when 169any name matches. 170 171X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject 172CommonName from the peer certificate that matched one of the reference 173identifiers. When wildcard matching is not disabled, or when a 174reference identifier specifies a parent domain (starts with ".") 175rather than a hostname, the peer name may be a wildcard name or a 176sub-domain of the reference identifier respectively. The return 177string is allocated by the library and is no longer valid once the 178associated B<param> argument is freed. Applications must not free 179the return value. 180 181X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to 182B<email>. If B<email> is NUL-terminated, B<emaillen> may be zero, otherwise 183B<emaillen> must be set to the length of B<email>. When an email address 184is specified, certificate verification automatically invokes 185L<X509_check_email(3)>. 186 187X509_VERIFY_PARAM_set1_ip() sets the expected IP address to B<ip>. 188The B<ip> argument is in binary format, in network byte-order and 189B<iplen> must be set to 4 for IPv4 and 16 for IPv6. When an IP 190address is specified, certificate verification automatically invokes 191L<X509_check_ip(3)>. 192 193X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to 194B<ipasc>. The B<ipasc> argument is a NUL-terminal ASCII string: 195dotted decimal quad for IPv4 and colon-separated hexadecimal for 196IPv6. The condensed "::" notation is supported for IPv6 addresses. 197 198=head1 RETURN VALUES 199 200X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(), 201X509_VERIFY_PARAM_set_inh_flags(), 202X509_VERIFY_PARAM_set_purpose(), X509_VERIFY_PARAM_set_trust(), 203X509_VERIFY_PARAM_add0_policy() X509_VERIFY_PARAM_set1_policies(), 204X509_VERIFY_PARAM_set1_host(), X509_VERIFY_PARAM_add1_host(), 205X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip() and 206X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for 207failure. 208 209X509_VERIFY_PARAM_get_flags() returns the current verification flags. 210 211X509_VERIFY_PARAM_get_hostflags() returns any current host flags. 212 213X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags. 214 215X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return 216values. 217 218X509_VERIFY_PARAM_get_depth() returns the current verification depth. 219 220X509_VERIFY_PARAM_get_auth_level() returns the current authentication security 221level. 222 223=head1 VERIFICATION FLAGS 224 225The verification flags consists of zero or more of the following flags 226ored together. 227 228B<X509_V_FLAG_CRL_CHECK> enables CRL checking for the certificate chain leaf 229certificate. An error occurs if a suitable CRL cannot be found. 230 231B<X509_V_FLAG_CRL_CHECK_ALL> enables CRL checking for the entire certificate 232chain. 233 234B<X509_V_FLAG_IGNORE_CRITICAL> disabled critical extension checking. By default 235any unhandled critical extensions in certificates or (if checked) CRLs results 236in a fatal error. If this flag is set unhandled critical extensions are 237ignored. B<WARNING> setting this option for anything other than debugging 238purposes can be a security risk. Finer control over which extensions are 239supported can be performed in the verification callback. 240 241The B<X509_V_FLAG_X509_STRICT> flag disables workarounds for some broken 242certificates and makes the verification strictly apply B<X509> rules. 243 244B<X509_V_FLAG_ALLOW_PROXY_CERTS> enables proxy certificate verification. 245 246B<X509_V_FLAG_POLICY_CHECK> enables certificate policy checking, by default 247no policy checking is performed. Additional information is sent to the 248verification callback relating to policy checking. 249 250B<X509_V_FLAG_EXPLICIT_POLICY>, B<X509_V_FLAG_INHIBIT_ANY> and 251B<X509_V_FLAG_INHIBIT_MAP> set the B<require explicit policy>, B<inhibit any 252policy> and B<inhibit policy mapping> flags respectively as defined in 253B<RFC3280>. Policy checking is automatically enabled if any of these flags 254are set. 255 256If B<X509_V_FLAG_NOTIFY_POLICY> is set and the policy checking is successful 257a special status code is set to the verification callback. This permits it 258to examine the valid policy tree and perform additional checks or simply 259log it for debugging purposes. 260 261By default some additional features such as indirect CRLs and CRLs signed by 262different keys are disabled. If B<X509_V_FLAG_EXTENDED_CRL_SUPPORT> is set 263they are enabled. 264 265If B<X509_V_FLAG_USE_DELTAS> is set delta CRLs (if present) are used to 266determine certificate status. If not set deltas are ignored. 267 268B<X509_V_FLAG_CHECK_SS_SIGNATURE> requests checking the signature of 269the last certificate in a chain if the certificate is supposedly self-signed. 270This is prohibited and will result in an error if it is a non-conforming CA 271certificate with key usage restrictions not including the keyCertSign bit. 272By default this check is disabled because it doesn't 273add any additional security but in some cases applications might want to 274check the signature anyway. A side effect of not checking the self-signature 275of such a certificate is that disabled or unsupported message digests used for 276the signature are not treated as fatal errors. 277 278When B<X509_V_FLAG_TRUSTED_FIRST> is set, construction of the certificate chain 279in L<X509_verify_cert(3)> will search the trust store for issuer certificates 280before searching the provided untrusted certificates. 281Local issuer certificates are often more likely to satisfy local security 282requirements and lead to a locally trusted root. 283This is especially important when some certificates in the trust store have 284explicit trust settings (see "TRUST SETTINGS" in L<x509(1)>). 285As of OpenSSL 1.1.0 this option is on by default. 286 287The B<X509_V_FLAG_NO_ALT_CHAINS> flag suppresses checking for alternative 288chains. 289By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a 290certificate chain, if the first certificate chain found is not trusted, then 291OpenSSL will attempt to replace untrusted certificates supplied by the peer 292with certificates from the trust store to see if an alternative chain can be 293found that is trusted. 294As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option 295has no effect. 296 297The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes intermediate certificates in the 298trust store to be treated as trust-anchors, in the same way as the self-signed 299root CA certificates. 300This makes it possible to trust certificates issued by an intermediate CA 301without having to trust its ancestor root CA. 302With OpenSSL 1.1.0 and later and <X509_V_FLAG_PARTIAL_CHAIN> set, chain 303construction stops as soon as the first certificate from the trust store is 304added to the chain, whether that certificate is a self-signed "root" 305certificate or a not self-signed intermediate certificate. 306Thus, when an intermediate certificate is found in the trust store, the 307verified chain passed to callbacks may be shorter than it otherwise would 308be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag. 309 310The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period 311of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time() 312is used to specify a verification time, the check is not suppressed. 313 314=head1 INHERITANCE FLAGS 315 316These flags specify how parameters are "inherited" from one structure to 317another. 318 319If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed 320after the next call. 321 322If B<X509_VP_FLAG_LOCKED> is set then no values are copied. This overrides 323all of the following flags. 324 325If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied 326to the destination. Effectively the values in "to" become default values 327which will be used only if nothing new is set in "from". This is the 328default. 329 330If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether 331they are set or not. Flags is still Ored though. 332 333If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead 334of ORed. 335 336=head1 NOTES 337 338The above functions should be used to manipulate verification parameters 339instead of functions which work in specific structures such as 340X509_STORE_CTX_set_flags() which are likely to be deprecated in a future 341release. 342 343=head1 BUGS 344 345Delta CRL checking is currently primitive. Only a single delta can be used and 346(partly due to limitations of B<X509_STORE>) constructed CRLs are not 347maintained. 348 349If CRLs checking is enable CRLs are expected to be available in the 350corresponding B<X509_STORE> structure. No attempt is made to download 351CRLs from the CRL distribution points extension. 352 353=head1 EXAMPLES 354 355Enable CRL checking when performing certificate verification during SSL 356connections associated with an B<SSL_CTX> structure B<ctx>: 357 358 X509_VERIFY_PARAM *param; 359 360 param = X509_VERIFY_PARAM_new(); 361 X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK); 362 SSL_CTX_set1_param(ctx, param); 363 X509_VERIFY_PARAM_free(param); 364 365=head1 SEE ALSO 366 367L<X509_verify_cert(3)>, 368L<X509_check_host(3)>, 369L<X509_check_email(3)>, 370L<X509_check_ip(3)>, 371L<x509(1)> 372 373=head1 HISTORY 374 375The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0. 376The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0 377and has no effect. 378 379The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i. 380 381The function X509_VERIFY_PARAM_add0_policy() was historically documented as 382enabling policy checking however the implementation has never done this. 383The documentation was changed to align with the implementation. 384 385=head1 COPYRIGHT 386 387Copyright 2009-2020 The OpenSSL Project Authors. All Rights Reserved. 388 389Licensed under the OpenSSL license (the "License"). You may not use 390this file except in compliance with the License. You can obtain a copy 391in the file LICENSE in the source distribution or at 392L<https://www.openssl.org/source/license.html>. 393 394=cut 395