.\"	$OpenBSD: X509_VERIFY_PARAM_set_flags.3,v 1.5 2017/01/06 21:30:27 schwarze Exp $
.\"	OpenSSL 2b4ffc65 Dec 23 19:28:30 2013 +0100
.\"
.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
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.Dd $Mdocdate: January 6 2017 $
.Dt X509_VERIFY_PARAM_SET_FLAGS 3
.Os
.Sh NAME
.Nm X509_VERIFY_PARAM_set_flags ,
.Nm X509_VERIFY_PARAM_clear_flags ,
.Nm X509_VERIFY_PARAM_get_flags ,
.Nm X509_VERIFY_PARAM_set_purpose ,
.Nm X509_VERIFY_PARAM_set_trust ,
.Nm X509_VERIFY_PARAM_set_time ,
.Nm X509_VERIFY_PARAM_add0_policy ,
.Nm X509_VERIFY_PARAM_set1_policies ,
.Nm X509_VERIFY_PARAM_set_depth ,
.Nm X509_VERIFY_PARAM_get_depth
.Nd X509 verification parameters
.Sh SYNOPSIS
.In openssl/x509_vfy.h
.Ft int
.Fo X509_VERIFY_PARAM_set_flags
.Fa "X509_VERIFY_PARAM *param"
.Fa "unsigned long flags"
.Fc
.Ft int
.Fo X509_VERIFY_PARAM_clear_flags
.Fa "X509_VERIFY_PARAM *param"
.Fa "unsigned long flags"
.Fc
.Ft unsigned long
.Fo X509_VERIFY_PARAM_get_flags
.Fa "X509_VERIFY_PARAM *param"
.Fc
.Ft int
.Fo X509_VERIFY_PARAM_set_purpose
.Fa "X509_VERIFY_PARAM *param"
.Fa "int purpose"
.Fc
.Ft int
.Fo X509_VERIFY_PARAM_set_trust
.Fa "X509_VERIFY_PARAM *param"
.Fa "int trust"
.Fc
.Ft void
.Fo X509_VERIFY_PARAM_set_time
.Fa "X509_VERIFY_PARAM *param"
.Fa "time_t t"
.Fc
.Ft int
.Fo X509_VERIFY_PARAM_add0_policy
.Fa "X509_VERIFY_PARAM *param"
.Fa "ASN1_OBJECT *policy"
.Fc
.Ft int
.Fo X509_VERIFY_PARAM_set1_policies
.Fa "X509_VERIFY_PARAM *param"
.Fa "STACK_OF(ASN1_OBJECT) *policies"
.Fc
.Ft void
.Fo X509_VERIFY_PARAM_set_depth
.Fa "X509_VERIFY_PARAM *param"
.Fa "int depth"
.Fc
.Ft int
.Fo X509_VERIFY_PARAM_get_depth
.Fa "const X509_VERIFY_PARAM *param"
.Fc
.Sh DESCRIPTION
These functions manipulate the
.Vt X509_VERIFY_PARAM
structure associated with a certificate verification operation.
.Pp
The
.Fn X509_VERIFY_PARAM_set_flags
function sets the flags in
.Fa param
by OR'ing it with
.Fa flags .
See the
.Sx VERIFICATION FLAGS
section for a complete description of values the
.Fa flags
parameter can take.
.Pp
.Fn X509_VERIFY_PARAM_get_flags
returns the flags in
.Fa param .
.Pp
.Fn X509_VERIFY_PARAM_clear_flags
clears the flags
.Fa flags
in
.Fa param .
.Pp
.Fn X509_VERIFY_PARAM_set_purpose
sets the verification purpose in
.Fa param
to
.Fa purpose .
This determines the acceptable purpose of the certificate chain, for
example SSL client or SSL server.
.Pp
.Fn X509_VERIFY_PARAM_set_trust
sets the trust setting in
.Fa param
to
.Fa trust .
.Pp
.Fn X509_VERIFY_PARAM_set_time
sets the verification time in
.Fa param
to
.Fa t .
Normally the current time is used.
.Pp
.Fn X509_VERIFY_PARAM_add0_policy
enables policy checking (it is disabled by default) and adds
.Fa policy
to the acceptable policy set.
.Pp
.Fn X509_VERIFY_PARAM_set1_policies
enables policy checking (it is disabled by default) and sets the
acceptable policy set to
.Fa policies .
Any existing policy set is cleared.
The
.Fa policies
parameter can be
.Dv NULL
to clear an existing policy set.
.Pp
.Fn X509_VERIFY_PARAM_set_depth
sets the maximum verification depth to
.Fa depth .
That is the maximum number of untrusted CA certificates that can appear
in a chain.
.Sh RETURN VALUES
.Fn X509_VERIFY_PARAM_set_flags ,
.Fn X509_VERIFY_PARAM_clear_flags ,
.Fn X509_VERIFY_PARAM_set_purpose ,
.Fn X509_VERIFY_PARAM_set_trust ,
.Fn X509_VERIFY_PARAM_add0_policy ,
and
.Fn X509_VERIFY_PARAM_set1_policies
return 1 for success or 0 for failure.
.Pp
.Fn X509_VERIFY_PARAM_get_flags
returns the current verification flags.
.Pp
.Fn X509_VERIFY_PARAM_set_time
and
.Fn X509_VERIFY_PARAM_set_depth
do not return values.
.Pp
.Fn X509_VERIFY_PARAM_get_depth
returns the current verification depth.
.Sh VERIFICATION FLAGS
The verification flags consists of zero or more of the following
flags OR'ed together.
.Pp
.Dv X509_V_FLAG_CRL_CHECK
enables CRL checking for the certificate chain leaf certificate.
An error occurs if a suitable CRL cannot be found.
.Pp
.Dv X509_V_FLAG_CRL_CHECK_ALL
enables CRL checking for the entire certificate chain.
.Pp
.Dv X509_V_FLAG_IGNORE_CRITICAL
disables critical extension checking.
By default any unhandled critical extensions in certificates or (if
checked) CRLs results in a fatal error.
If this flag is set unhandled critical extensions are ignored.
.Sy 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.
.Pp
The
.Dv X509_V_FLAG_X509_STRICT
flag disables workarounds for some broken certificates and makes the
verification strictly apply X509 rules.
.Pp
.Dv X509_V_FLAG_ALLOW_PROXY_CERTS
enables proxy certificate verification.
.Pp
.Dv 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.
.Pp
.Dv X509_V_FLAG_EXPLICIT_POLICY ,
.Dv X509_V_FLAG_INHIBIT_ANY ,
and
.Dv X509_V_FLAG_INHIBIT_MAP
set the
.Dq require explicit policy ,
.Dq inhibit any policy ,
and
.Dq inhibit policy mapping
flags, respectively, as defined in RFC 3280.
Policy checking is automatically enabled if any of these flags are set.
.Pp
If
.Dv 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.
.Pp
By default some additional features such as indirect CRLs and CRLs
signed by different keys are disabled.
If
.Dv X509_V_FLAG_EXTENDED_CRL_SUPPORT
is set they are enabled.
.Pp
If
.Dv X509_V_FLAG_USE_DELTAS
is set, delta CRLs (if present) are used to determine certificate
status.
If not set, deltas are ignored.
.Pp
.Dv X509_V_FLAG_CHECK_SS_SIGNATURE
enables checking of the root CA self signed certificate signature.
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 root CA signature is that disabled or
unsupported message digests on the root CA are not treated as fatal
errors.
.Pp
The
.Dv X509_V_FLAG_CB_ISSUER_CHECK
flag enables debugging of certificate issuer checks.
It is
.Sy not
needed unless you are logging certificate verification.
If this flag is set then additional status codes will be sent to the
verification callback and it
.Sy must
be prepared to handle such cases without assuming they are hard errors.
.Sh EXAMPLES
Enable CRL checking when performing certificate verification during
SSL connections associated with an
.Vt SSL_CTX
structure
.Fa ctx :
.Bd -literal -offset indent
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);
.Ed
.Sh SEE ALSO
.Xr X509_verify_cert 3
.Sh BUGS
Delta CRL checking is currently primitive.
Only a single delta can be used and (partly due to limitations of
.Vt X509_STORE )
constructed CRLs are not maintained.
.Pp
If CRLs checking is enabled, CRLs are expected to be available in
the corresponding
.Vt X509_STORE
structure.
No attempt is made to download CRLs from the CRL distribution points
extension.