Provided by: libssl-doc_3.0.8-1ubuntu1_all 
NAME
X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags, X509_VERIFY_PARAM_get_flags,
X509_VERIFY_PARAM_set_purpose, X509_VERIFY_PARAM_get_inh_flags,
X509_VERIFY_PARAM_set_inh_flags, X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth,
X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_auth_level,
X509_VERIFY_PARAM_get_auth_level, X509_VERIFY_PARAM_set_time, X509_VERIFY_PARAM_get_time,
X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies,
X509_VERIFY_PARAM_get0_host, X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host,
X509_VERIFY_PARAM_set_hostflags, X509_VERIFY_PARAM_get_hostflags,
X509_VERIFY_PARAM_get0_peername, X509_VERIFY_PARAM_get0_email,
X509_VERIFY_PARAM_set1_email, X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_get1_ip_asc,
X509_VERIFY_PARAM_set1_ip_asc - X509 verification parameters
SYNOPSIS
#include <openssl/x509_vfy.h>
int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
unsigned long flags);
int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
unsigned long flags);
unsigned long X509_VERIFY_PARAM_get_flags(const X509_VERIFY_PARAM *param);
int X509_VERIFY_PARAM_set_inh_flags(X509_VERIFY_PARAM *param,
uint32_t flags);
uint32_t X509_VERIFY_PARAM_get_inh_flags(const X509_VERIFY_PARAM *param);
int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
int X509_VERIFY_PARAM_set_trust(X509_VERIFY_PARAM *param, int trust);
void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
time_t X509_VERIFY_PARAM_get_time(const X509_VERIFY_PARAM *param);
int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
ASN1_OBJECT *policy);
int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param,
STACK_OF(ASN1_OBJECT) *policies);
void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);
void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
int auth_level);
int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);
char *X509_VERIFY_PARAM_get0_host(X509_VERIFY_PARAM *param, int n);
int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
const char *name, size_t namelen);
int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
const char *name, size_t namelen);
void X509_VERIFY_PARAM_set_hostflags(X509_VERIFY_PARAM *param,
unsigned int flags);
unsigned int X509_VERIFY_PARAM_get_hostflags(const X509_VERIFY_PARAM *param);
char *X509_VERIFY_PARAM_get0_peername(const X509_VERIFY_PARAM *param);
char *X509_VERIFY_PARAM_get0_email(X509_VERIFY_PARAM *param);
int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
const char *email, size_t emaillen);
char *X509_VERIFY_PARAM_get1_ip_asc(X509_VERIFY_PARAM *param);
int X509_VERIFY_PARAM_set1_ip(X509_VERIFY_PARAM *param,
const unsigned char *ip, size_t iplen);
int X509_VERIFY_PARAM_set1_ip_asc(X509_VERIFY_PARAM *param, const char *ipasc);
DESCRIPTION
These functions manipulate the X509_VERIFY_PARAM structure associated with a certificate
verification operation.
The X509_VERIFY_PARAM_set_flags() function sets the flags in param by oring it with flags.
See "VERIFICATION FLAGS" for a complete description of values the flags parameter can
take.
X509_VERIFY_PARAM_get_flags() returns the flags in param.
X509_VERIFY_PARAM_get_inh_flags() returns the inheritance flags in param which specifies
how verification flags are copied from one structure to another.
X509_VERIFY_PARAM_set_inh_flags() sets the inheritance flags. See the INHERITANCE FLAGS
section for a description of these bits.
X509_VERIFY_PARAM_clear_flags() clears the flags flags in param.
X509_VERIFY_PARAM_set_purpose() sets the verification purpose in param to purpose. This
determines the acceptable purpose of the certificate chain, for example
X509_PURPOSE_SSL_CLIENT. The purpose requirement is cleared if purpose is 0.
X509_VERIFY_PARAM_set_trust() sets the trust setting in param to trust.
X509_VERIFY_PARAM_set_time() sets the verification time in param to t. Normally the
current time is used.
X509_VERIFY_PARAM_add0_policy() enables policy checking (it is disabled by default) and
adds policy to the acceptable policy set.
X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled by default) and
sets the acceptable policy set to policies. Any existing policy set is cleared. The
policies parameter can be NULL to clear an existing policy set.
X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to depth. That is the
maximum number of intermediate CA certificates that can appear in a chain. A maximal
depth chain contains 2 more certificates than the limit, since neither the end-entity
certificate nor the trust-anchor count against this limit. Thus a depth limit of 0 only
allows the end-entity certificate to be signed directly by the trust anchor, while with a
depth limit of 1 there can be one intermediate CA certificate between the trust anchor and
the end-entity certificate.
X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to auth_level.
The authentication security level determines the acceptable signature and public key
strength when verifying certificate chains. For a certificate chain to validate, the
public keys of all the certificates must meet the specified security level. The signature
algorithm security level is not enforced for the chain's trust anchor certificate, which
is either directly trusted or validated by means other than its signature. See
SSL_CTX_set_security_level(3) for the definitions of the available levels. The default
security level is -1, or "not set". At security level 0 or lower all algorithms are
acceptable. Security level 1 requires at least 80-bit-equivalent security and is broadly
interoperable, though it will, for example, reject MD5 signatures or RSA keys shorter than
1024 bits.
X509_VERIFY_PARAM_get0_host() returns the nth expected DNS hostname that has been set
using X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host(). To obtain all names
start with n = 0 and increment n as long as no NULL pointer is returned.
X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to name clearing any
previously specified hostname. If name is NULL, or empty the list of hostnames is
cleared, and name checks are not performed on the peer certificate. If name is NUL-
terminated, namelen may be zero, otherwise namelen must be set to the length of name.
When a hostname is specified, certificate verification automatically invokes
X509_check_host(3) with flags equal to the flags argument given to
X509_VERIFY_PARAM_set_hostflags() (default zero). Applications are strongly advised to
use this interface in preference to explicitly calling X509_check_host(3), hostname checks
may be out of scope with the DANE-EE(3) certificate usage, and the internal check will be
suppressed as appropriate when DANE verification is enabled.
When the subject CommonName will not be ignored, whether as a result of the
X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT host flag, or because no DNS subject alternative
names are present in the certificate, any DNS name constraints in issuer certificates
apply to the subject CommonName as well as the subject alternative name extension.
When the subject CommonName will be ignored, whether as a result of the
X509_CHECK_FLAG_NEVER_CHECK_SUBJECT host flag, or because some DNS subject alternative
names are present in the certificate, DNS name constraints in issuer certificates will not
be applied to the subject DN. As described in X509_check_host(3) the
X509_CHECK_FLAG_NEVER_CHECK_SUBJECT flag takes precedence over the
X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT flag.
X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a call to
X509_VERIFY_PARAM_set_hostflags().
X509_VERIFY_PARAM_add1_host() adds name as an additional reference identifier that can
match the peer's certificate. Any previous names set via X509_VERIFY_PARAM_set1_host() or
X509_VERIFY_PARAM_add1_host() are retained, no change is made if name is NULL or empty.
When multiple names are configured, the peer is considered verified when any name matches.
X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject CommonName from the
peer certificate that matched one of the reference identifiers. When wildcard matching is
not disabled, or when a reference identifier specifies a parent domain (starts with ".")
rather than a hostname, the peer name may be a wildcard name or a sub-domain of the
reference identifier respectively. The return string is allocated by the library and is
no longer valid once the associated param argument is freed. Applications must not free
the return value.
X509_VERIFY_PARAM_get0_email() returns the expected RFC822 email address.
X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to email. If email
is NUL-terminated, emaillen may be zero, otherwise emaillen must be set to the length of
email. When an email address is specified, certificate verification automatically invokes
X509_check_email(3).
X509_VERIFY_PARAM_get1_ip_asc() returns the expected IP address as a string. The caller
is responsible for freeing it.
X509_VERIFY_PARAM_set1_ip() sets the expected IP address to ip. The ip argument is in
binary format, in network byte-order and iplen must be set to 4 for IPv4 and 16 for IPv6.
When an IP address is specified, certificate verification automatically invokes
X509_check_ip(3).
X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to ipasc. The ipasc argument
is a NUL-terminal ASCII string: dotted decimal quad for IPv4 and colon-separated
hexadecimal for IPv6. The condensed "::" notation is supported for IPv6 addresses.
RETURN VALUES
X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(),
X509_VERIFY_PARAM_set_inh_flags(), X509_VERIFY_PARAM_set_purpose(),
X509_VERIFY_PARAM_set_trust(), X509_VERIFY_PARAM_add0_policy()
X509_VERIFY_PARAM_set1_policies(), X509_VERIFY_PARAM_set1_host(),
X509_VERIFY_PARAM_add1_host(), X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip()
and X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for failure.
X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(), and
X509_VERIFY_PARAM_get1_ip_asc(), return the string pointers pecified above or NULL if the
respective value has not been set or on error.
X509_VERIFY_PARAM_get_flags() returns the current verification flags.
X509_VERIFY_PARAM_get_hostflags() returns any current host flags.
X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags.
X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return values.
X509_VERIFY_PARAM_get_depth() returns the current verification depth.
X509_VERIFY_PARAM_get_auth_level() returns the current authentication security level.
VERIFICATION FLAGS
The verification flags consists of zero or more of the following flags ored together.
X509_V_FLAG_CRL_CHECK enables CRL checking for the certificate chain leaf certificate. An
error occurs if a suitable CRL cannot be found.
X509_V_FLAG_CRL_CHECK_ALL enables CRL checking for the entire certificate chain.
X509_V_FLAG_IGNORE_CRITICAL disables critical extension checking. By default any unhandled
critical extensions in certificates or (if checked) CRLs result in a fatal error. If this
flag is set unhandled critical extensions are ignored. WARNING setting this option for
anything other than debugging purposes can be a security risk. Finer control over which
extensions are supported can be performed in the verification callback.
The X509_V_FLAG_X509_STRICT flag disables workarounds for some broken certificates and
makes the verification strictly apply X509 rules.
X509_V_FLAG_ALLOW_PROXY_CERTS enables proxy certificate verification.
X509_V_FLAG_POLICY_CHECK enables certificate policy checking, by default no policy
checking is performed. Additional information is sent to the verification callback
relating to policy checking.
X509_V_FLAG_EXPLICIT_POLICY, X509_V_FLAG_INHIBIT_ANY and X509_V_FLAG_INHIBIT_MAP set the
require explicit policy, inhibit any policy and inhibit policy mapping flags respectively
as defined in RFC3280. Policy checking is automatically enabled if any of these flags are
set.
If X509_V_FLAG_NOTIFY_POLICY is set and the policy checking is successful a special status
code is set to the verification callback. This permits it to examine the valid policy tree
and perform additional checks or simply log it for debugging purposes.
By default some additional features such as indirect CRLs and CRLs signed by different
keys are disabled. If X509_V_FLAG_EXTENDED_CRL_SUPPORT is set they are enabled.
If X509_V_FLAG_USE_DELTAS is set delta CRLs (if present) are used to determine certificate
status. If not set deltas are ignored.
X509_V_FLAG_CHECK_SS_SIGNATURE requests checking the signature of the last certificate in
a chain if the certificate is supposedly self-signed. This is prohibited and will result
in an error if it is a non-conforming CA certificate with key usage restrictions not
including the keyCertSign bit. By default this check is disabled because it doesn't add
any additional security but in some cases applications might want to check the signature
anyway. A side effect of not checking the self-signature of such a certificate is that
disabled or unsupported message digests used for the signature are not treated as fatal
errors.
When X509_V_FLAG_TRUSTED_FIRST is set, which is always the case since OpenSSL 1.1.0,
construction of the certificate chain in X509_verify_cert(3) searches the trust store for
issuer certificates before searching the provided untrusted certificates. Local issuer
certificates are often more likely to satisfy local security requirements and lead to a
locally trusted root. This is especially important when some certificates in the trust
store have explicit trust settings (see "TRUST SETTINGS" in openssl-x509(1)).
The X509_V_FLAG_NO_ALT_CHAINS flag could have been used before OpenSSL 1.1.0 to suppress
checking for alternative chains. By default, unless X509_V_FLAG_TRUSTED_FIRST is set,
when building a certificate chain, if the first certificate chain found is not trusted,
then OpenSSL will attempt to replace untrusted certificates supplied by the peer with
certificates from the trust store to see if an alternative chain can be found that is
trusted. As of OpenSSL 1.1.0, with X509_V_FLAG_TRUSTED_FIRST always set, this option has
no effect.
The X509_V_FLAG_PARTIAL_CHAIN flag causes non-self-signed certificates in the trust store
to be treated as trust anchors, in the same way as self-signed root CA certificates. This
makes it possible to trust self-issued certificates as well as certificates issued by an
intermediate CA without having to trust their ancestor root CA. With OpenSSL 1.1.0 and
later and X509_V_FLAG_PARTIAL_CHAIN set, chain construction stops as soon as the first
certificate contained in the trust store is added to the chain, whether that certificate
is a self-signed "root" certificate or a not self-signed "intermediate" or self-issued
certificate. Thus, when an intermediate certificate is found in the trust store, the
verified chain passed to callbacks may be shorter than it otherwise would be without the
X509_V_FLAG_PARTIAL_CHAIN flag.
The X509_V_FLAG_NO_CHECK_TIME flag suppresses checking the validity period of certificates
and CRLs against the current time. If X509_VERIFY_PARAM_set_time() is used to specify a
verification time, the check is not suppressed.
INHERITANCE FLAGS
These flags specify how parameters are "inherited" from one structure to another.
If X509_VP_FLAG_ONCE is set then the current setting is zeroed after the next call.
If X509_VP_FLAG_LOCKED is set then no values are copied. This overrides all of the
following flags.
If X509_VP_FLAG_DEFAULT is set then anything set in the source is copied to the
destination. Effectively the values in "to" become default values which will be used only
if nothing new is set in "from". This is the default.
If X509_VP_FLAG_OVERWRITE is set then all value are copied across whether they are set or
not. Flags is still Ored though.
If X509_VP_FLAG_RESET_FLAGS is set then the flags value is copied instead of ORed.
NOTES
The above functions should be used to manipulate verification parameters instead of
functions which work in specific structures such as X509_STORE_CTX_set_flags() which are
likely to be deprecated in a future release.
BUGS
Delta CRL checking is currently primitive. Only a single delta can be used and (partly due
to limitations of X509_STORE) constructed CRLs are not maintained.
If CRLs checking is enable CRLs are expected to be available in the corresponding
X509_STORE structure. No attempt is made to download CRLs from the CRL distribution points
extension.
EXAMPLES
Enable CRL checking when performing certificate verification during SSL connections
associated with an SSL_CTX structure ctx:
X509_VERIFY_PARAM *param;
param = X509_VERIFY_PARAM_new();
X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
SSL_CTX_set1_param(ctx, param);
X509_VERIFY_PARAM_free(param);
SEE ALSO
X509_verify_cert(3), X509_check_host(3), X509_check_email(3), X509_check_ip(3),
openssl-x509(1)
HISTORY
The X509_V_FLAG_NO_ALT_CHAINS flag was added in OpenSSL 1.1.0. The flag
X509_V_FLAG_CB_ISSUER_CHECK was deprecated in OpenSSL 1.1.0 and has no effect.
The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i.
The X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(), and
X509_VERIFY_PARAM_get1_ip_asc() functions were added in OpenSSL 3.0.
COPYRIGHT
Copyright 2009-2023 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use this file except
in compliance with the License. You can obtain a copy in the file LICENSE in the source
distribution or at <https://www.openssl.org/source/license.html>.