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 hostname 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> requests checking the signature of 268the last certificate in a chain if the certificate is supposedly self-signed. 269This is prohibited and will result in an error if it is a non-conforming CA 270certificate with key usage restrictions not including the keyCertSign bit. 271By default this check is disabled because it doesn't 272add any additional security but in some cases applications might want to 273check the signature anyway. A side effect of not checking the self-signature 274of such a certificate is that disabled or unsupported message digests used for 275the signature are not treated as fatal errors. 276 277When B<X509_V_FLAG_TRUSTED_FIRST> is set, construction of the certificate chain 278in L<X509_verify_cert(3)> will search the trust store for issuer certificates 279before searching the provided untrusted certificates. 280Local issuer certificates are often more likely to satisfy local security 281requirements and lead to a locally trusted root. 282This is especially important when some certificates in the trust store have 283explicit trust settings (see "TRUST SETTINGS" in L<x509(1)>). 284As of OpenSSL 1.1.0 this option is on by default. 285 286The B<X509_V_FLAG_NO_ALT_CHAINS> flag suppresses checking for alternative 287chains. 288By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a 289certificate chain, if the first certificate chain found is not trusted, then 290OpenSSL will attempt to replace untrusted certificates supplied by the peer 291with certificates from the trust store to see if an alternative chain can be 292found that is trusted. 293As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option 294has no effect. 295 296The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes intermediate certificates in the 297trust store to be treated as trust-anchors, in the same way as the self-signed 298root CA certificates. 299This makes it possible to trust certificates issued by an intermediate CA 300without having to trust its ancestor root CA. 301With OpenSSL 1.1.0 and later and <X509_V_FLAG_PARTIAL_CHAIN> set, chain 302construction stops as soon as the first certificate from the trust store is 303added to the chain, whether that certificate is a self-signed "root" 304certificate or a not self-signed intermediate certificate. 305Thus, when an intermediate certificate is found in the trust store, the 306verified chain passed to callbacks may be shorter than it otherwise would 307be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag. 308 309The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period 310of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time() 311is used to specify a verification time, the check is not suppressed. 312 313=head1 INHERITANCE FLAGS 314 315These flags specify how parameters are "inherited" from one structure to 316another. 317 318If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed 319after the next call. 320 321If B<X509_VP_FLAG_LOCKED> is set then no values are copied. This overrides 322all of the following flags. 323 324If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied 325to the destination. Effectively the values in "to" become default values 326which will be used only if nothing new is set in "from". This is the 327default. 328 329If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether 330they are set or not. Flags is still Ored though. 331 332If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead 333of ORed. 334 335=head1 NOTES 336 337The above functions should be used to manipulate verification parameters 338instead of functions which work in specific structures such as 339X509_STORE_CTX_set_flags() which are likely to be deprecated in a future 340release. 341 342=head1 BUGS 343 344Delta CRL checking is currently primitive. Only a single delta can be used and 345(partly due to limitations of B<X509_STORE>) constructed CRLs are not 346maintained. 347 348If CRLs checking is enable CRLs are expected to be available in the 349corresponding B<X509_STORE> structure. No attempt is made to download 350CRLs from the CRL distribution points extension. 351 352=head1 EXAMPLES 353 354Enable CRL checking when performing certificate verification during SSL 355connections associated with an B<SSL_CTX> structure B<ctx>: 356 357 X509_VERIFY_PARAM *param; 358 359 param = X509_VERIFY_PARAM_new(); 360 X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK); 361 SSL_CTX_set1_param(ctx, param); 362 X509_VERIFY_PARAM_free(param); 363 364=head1 SEE ALSO 365 366L<X509_verify_cert(3)>, 367L<X509_check_host(3)>, 368L<X509_check_email(3)>, 369L<X509_check_ip(3)>, 370L<x509(1)> 371 372=head1 HISTORY 373 374The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0. 375The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0 376and has no effect. 377 378The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i. 379 380=head1 COPYRIGHT 381 382Copyright 2009-2020 The OpenSSL Project Authors. All Rights Reserved. 383 384Licensed under the OpenSSL license (the "License"). You may not use 385this file except in compliance with the License. You can obtain a copy 386in the file LICENSE in the source distribution or at 387L<https://www.openssl.org/source/license.html>. 388 389=cut 390