mirror of
https://github.com/openssl/openssl.git
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418 lines
19 KiB
Plaintext
418 lines
19 KiB
Plaintext
=pod
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=head1 NAME
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X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags,
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X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose,
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X509_VERIFY_PARAM_get_inh_flags, X509_VERIFY_PARAM_set_inh_flags,
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X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth,
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X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_auth_level,
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X509_VERIFY_PARAM_get_auth_level, X509_VERIFY_PARAM_set_time,
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X509_VERIFY_PARAM_get_time,
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X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies,
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X509_VERIFY_PARAM_get0_host,
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X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host,
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X509_VERIFY_PARAM_set_hostflags,
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X509_VERIFY_PARAM_get_hostflags,
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X509_VERIFY_PARAM_get0_peername,
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X509_VERIFY_PARAM_get0_email, X509_VERIFY_PARAM_set1_email,
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X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_get1_ip_asc,
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X509_VERIFY_PARAM_set1_ip_asc
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- X509 verification parameters
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=head1 SYNOPSIS
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#include <openssl/x509_vfy.h>
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int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
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unsigned long flags);
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int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
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unsigned long flags);
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unsigned long X509_VERIFY_PARAM_get_flags(const X509_VERIFY_PARAM *param);
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int X509_VERIFY_PARAM_set_inh_flags(X509_VERIFY_PARAM *param,
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uint32_t flags);
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uint32_t X509_VERIFY_PARAM_get_inh_flags(const X509_VERIFY_PARAM *param);
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int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
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int X509_VERIFY_PARAM_set_trust(X509_VERIFY_PARAM *param, int trust);
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void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
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time_t X509_VERIFY_PARAM_get_time(const X509_VERIFY_PARAM *param);
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int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
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ASN1_OBJECT *policy);
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int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param,
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STACK_OF(ASN1_OBJECT) *policies);
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void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
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int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);
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void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
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int auth_level);
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int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);
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char *X509_VERIFY_PARAM_get0_host(X509_VERIFY_PARAM *param, int n);
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int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
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const char *name, size_t namelen);
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int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
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const char *name, size_t namelen);
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void X509_VERIFY_PARAM_set_hostflags(X509_VERIFY_PARAM *param,
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unsigned int flags);
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unsigned int X509_VERIFY_PARAM_get_hostflags(const X509_VERIFY_PARAM *param);
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char *X509_VERIFY_PARAM_get0_peername(const X509_VERIFY_PARAM *param);
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char *X509_VERIFY_PARAM_get0_email(X509_VERIFY_PARAM *param);
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int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
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const char *email, size_t emaillen);
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char *X509_VERIFY_PARAM_get1_ip_asc(X509_VERIFY_PARAM *param);
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int X509_VERIFY_PARAM_set1_ip(X509_VERIFY_PARAM *param,
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const unsigned char *ip, size_t iplen);
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int X509_VERIFY_PARAM_set1_ip_asc(X509_VERIFY_PARAM *param, const char *ipasc);
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=head1 DESCRIPTION
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These functions manipulate the B<X509_VERIFY_PARAM> structure associated with
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a certificate verification operation.
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The X509_VERIFY_PARAM_set_flags() function sets the flags in B<param> by oring
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it with B<flags>. See L</VERIFICATION FLAGS> for a complete
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description of values the B<flags> parameter can take.
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X509_VERIFY_PARAM_get_flags() returns the flags in B<param>.
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X509_VERIFY_PARAM_get_inh_flags() returns the inheritance flags in B<param>
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which specifies how verification flags are copied from one structure to
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another. X509_VERIFY_PARAM_set_inh_flags() sets the inheritance flags.
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See the B<INHERITANCE FLAGS> section for a description of these bits.
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X509_VERIFY_PARAM_clear_flags() clears the flags B<flags> in B<param>.
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X509_VERIFY_PARAM_set_purpose() sets the verification purpose in B<param>
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to B<purpose>. This determines the acceptable purpose of the certificate
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chain, for example B<X509_PURPOSE_SSL_CLIENT>.
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The purpose requirement is cleared if B<purpose> is 0.
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X509_VERIFY_PARAM_set_trust() sets the trust setting in B<param> to
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B<trust>.
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X509_VERIFY_PARAM_set_time() sets the verification time in B<param> to
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B<t>. Normally the current time is used.
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X509_VERIFY_PARAM_add0_policy() adds B<policy> to the acceptable policy set.
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Contrary to preexisting documentation of this function it does not enable
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policy checking.
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X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled
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by default) and sets the acceptable policy set to B<policies>. Any existing
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policy set is cleared. The B<policies> parameter can be B<NULL> to clear
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an existing policy set.
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X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>.
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That is the maximum number of intermediate CA certificates that can appear in a
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chain.
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A maximal depth chain contains 2 more certificates than the limit, since
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neither the end-entity certificate nor the trust-anchor count against this
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limit.
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Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed
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directly by the trust anchor, while with a B<depth> limit of 1 there can be one
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intermediate CA certificate between the trust anchor and the end-entity
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certificate.
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X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to
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B<auth_level>.
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The authentication security level determines the acceptable signature and public
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key strength when verifying certificate chains.
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For a certificate chain to validate, the public keys of all the certificates
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must meet the specified security level.
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The signature algorithm security level is not enforced for the chain's I<trust
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anchor> certificate, which is either directly trusted or validated by means other
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than its signature.
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See L<SSL_CTX_set_security_level(3)> for the definitions of the available
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levels.
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The default security level is -1, or "not set".
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At security level 0 or lower all algorithms are acceptable.
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Security level 1 requires at least 80-bit-equivalent security and is broadly
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interoperable, though it will, for example, reject MD5 signatures or RSA keys
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shorter than 1024 bits.
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X509_VERIFY_PARAM_get0_host() returns the B<n>th expected DNS hostname that has
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been set using X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host().
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To obtain all names start with B<n> = 0 and increment B<n> as long as no NULL
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pointer is returned.
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X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to
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B<name> clearing any previously specified hostname. If
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B<name> is NULL, or empty the list of hostnames is cleared, and
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name checks are not performed on the peer certificate. If B<name>
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is NUL-terminated, B<namelen> may be zero, otherwise B<namelen>
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must be set to the length of B<name>.
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When a hostname is specified,
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certificate verification automatically invokes L<X509_check_host(3)>
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with flags equal to the B<flags> argument given to
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X509_VERIFY_PARAM_set_hostflags() (default zero). Applications
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are strongly advised to use this interface in preference to explicitly
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calling L<X509_check_host(3)>, hostname checks may be out of scope
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with the DANE-EE(3) certificate usage, and the internal check will
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be suppressed as appropriate when DANE verification is enabled.
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When the subject CommonName will not be ignored, whether as a result of the
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B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> host flag, or because no DNS subject
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alternative names are present in the certificate, any DNS name constraints in
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issuer certificates apply to the subject CommonName as well as the subject
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alternative name extension.
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When the subject CommonName will be ignored, whether as a result of the
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B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> host flag, or because some DNS subject
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alternative names are present in the certificate, DNS name constraints in
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issuer certificates will not be applied to the subject DN.
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As described in X509_check_host(3) the B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT>
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flag takes precedence over the B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag.
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X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a
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call to X509_VERIFY_PARAM_set_hostflags().
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X509_VERIFY_PARAM_add1_host() adds B<name> as an additional reference
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identifier that can match the peer's certificate. Any previous names
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set via X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host()
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are retained, no change is made if B<name> is NULL or empty. When
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multiple names are configured, the peer is considered verified when
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any name matches.
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X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject
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CommonName from the peer certificate that matched one of the reference
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identifiers. When wildcard matching is not disabled, or when a
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reference identifier specifies a parent domain (starts with ".")
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rather than a hostname, the peer name may be a wildcard name or a
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sub-domain of the reference identifier respectively. The return
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string is allocated by the library and is no longer valid once the
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associated B<param> argument is freed. Applications must not free
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the return value.
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X509_VERIFY_PARAM_get0_email() returns the expected RFC822 email address.
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X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to
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B<email>. If B<email> is NUL-terminated, B<emaillen> may be zero, otherwise
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B<emaillen> must be set to the length of B<email>. When an email address
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is specified, certificate verification automatically invokes
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L<X509_check_email(3)>.
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X509_VERIFY_PARAM_get1_ip_asc() returns the expected IP address as a string.
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The caller is responsible for freeing it.
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X509_VERIFY_PARAM_set1_ip() sets the expected IP address to B<ip>.
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The B<ip> argument is in binary format, in network byte-order and
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B<iplen> must be set to 4 for IPv4 and 16 for IPv6. When an IP
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address is specified, certificate verification automatically invokes
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L<X509_check_ip(3)>.
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X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to
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B<ipasc>. The B<ipasc> argument is a NUL-terminal ASCII string:
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dotted decimal quad for IPv4 and colon-separated hexadecimal for
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IPv6. The condensed "::" notation is supported for IPv6 addresses.
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=head1 RETURN VALUES
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X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(),
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X509_VERIFY_PARAM_set_inh_flags(),
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X509_VERIFY_PARAM_set_purpose(), X509_VERIFY_PARAM_set_trust(),
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X509_VERIFY_PARAM_add0_policy() X509_VERIFY_PARAM_set1_policies(),
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X509_VERIFY_PARAM_set1_host(), X509_VERIFY_PARAM_add1_host(),
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X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip() and
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X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for
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failure.
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X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(), and
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X509_VERIFY_PARAM_get1_ip_asc(), return the string pointers specified above
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or NULL if the respective value has not been set or on error.
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X509_VERIFY_PARAM_get_flags() returns the current verification flags.
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X509_VERIFY_PARAM_get_hostflags() returns any current host flags.
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X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags.
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X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return
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values.
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X509_VERIFY_PARAM_get_depth() returns the current verification depth.
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X509_VERIFY_PARAM_get_auth_level() returns the current authentication security
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level.
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=head1 VERIFICATION FLAGS
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The verification flags consists of zero or more of the following flags
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ored together.
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B<X509_V_FLAG_CRL_CHECK> enables CRL checking for the certificate chain leaf
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certificate. An error occurs if a suitable CRL cannot be found.
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B<X509_V_FLAG_CRL_CHECK_ALL> enables CRL checking for the entire certificate
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chain.
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B<X509_V_FLAG_IGNORE_CRITICAL> disables critical extension checking. By default
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any unhandled critical extensions in certificates or (if checked) CRLs result
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in a fatal error. If this flag is set unhandled critical extensions are
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ignored. B<WARNING> setting this option for anything other than debugging
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purposes can be a security risk. Finer control over which extensions are
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supported can be performed in the verification callback.
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The B<X509_V_FLAG_X509_STRICT> flag disables workarounds for some broken
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certificates and makes the verification strictly apply B<X509> rules.
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B<X509_V_FLAG_ALLOW_PROXY_CERTS> enables proxy certificate verification.
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B<X509_V_FLAG_POLICY_CHECK> enables certificate policy checking, by default
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no policy checking is performed. Additional information is sent to the
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verification callback relating to policy checking.
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B<X509_V_FLAG_EXPLICIT_POLICY>, B<X509_V_FLAG_INHIBIT_ANY> and
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B<X509_V_FLAG_INHIBIT_MAP> set the B<require explicit policy>, B<inhibit any
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policy> and B<inhibit policy mapping> flags respectively as defined in
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B<RFC3280>. Policy checking is automatically enabled if any of these flags
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are set.
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If B<X509_V_FLAG_NOTIFY_POLICY> is set and the policy checking is successful
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a special status code is set to the verification callback. This permits it
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to examine the valid policy tree and perform additional checks or simply
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log it for debugging purposes.
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By default some additional features such as indirect CRLs and CRLs signed by
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different keys are disabled. If B<X509_V_FLAG_EXTENDED_CRL_SUPPORT> is set
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they are enabled.
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If B<X509_V_FLAG_USE_DELTAS> is set delta CRLs (if present) are used to
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determine certificate status. If not set deltas are ignored.
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B<X509_V_FLAG_CHECK_SS_SIGNATURE> requests checking the signature of
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the last certificate in a chain if the certificate is supposedly self-signed.
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This is prohibited and will result in an error if it is a non-conforming CA
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certificate with key usage restrictions not including the I<keyCertSign> bit.
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By default this check is disabled because it doesn't
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add any additional security but in some cases applications might want to
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check the signature anyway. A side effect of not checking the self-signature
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of such a certificate is that disabled or unsupported message digests used for
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the signature are not treated as fatal errors.
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When B<X509_V_FLAG_TRUSTED_FIRST> is set, which is always the case since
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OpenSSL 1.1.0, construction of the certificate chain
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in L<X509_verify_cert(3)> searches the trust store for issuer certificates
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before searching the provided untrusted certificates.
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Local issuer certificates are often more likely to satisfy local security
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requirements and lead to a locally trusted root.
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This is especially important when some certificates in the trust store have
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explicit trust settings (see "TRUST SETTINGS" in L<openssl-x509(1)>).
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The B<X509_V_FLAG_NO_ALT_CHAINS> flag could have been used before OpenSSL 1.1.0
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to suppress checking for alternative chains.
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By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a
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certificate chain, if the first certificate chain found is not trusted, then
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OpenSSL will attempt to replace untrusted certificates supplied by the peer
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with certificates from the trust store to see if an alternative chain can be
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found that is trusted.
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As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option
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has no effect.
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The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes non-self-signed certificates in the
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trust store to be treated as trust anchors, in the same way as self-signed
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root CA certificates.
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This makes it possible to trust self-issued certificates as well as certificates
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issued by an intermediate CA without having to trust their ancestor root CA.
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With OpenSSL 1.1.0 and later and B<X509_V_FLAG_PARTIAL_CHAIN> set, chain
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construction stops as soon as the first certificate contained in the trust store
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is added to the chain, whether that certificate is a self-signed "root"
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certificate or a not self-signed "intermediate" or self-issued certificate.
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Thus, when an intermediate certificate is found in the trust store, the
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verified chain passed to callbacks may be shorter than it otherwise would
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be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag.
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The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period
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of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time()
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is used to specify a verification time, the check is not suppressed.
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=head1 INHERITANCE FLAGS
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These flags specify how parameters are "inherited" from one structure to
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another.
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If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed
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after the next call.
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If B<X509_VP_FLAG_LOCKED> is set then no values are copied. This overrides
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all of the following flags.
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If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied
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to the destination. Effectively the values in "to" become default values
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which will be used only if nothing new is set in "from". This is the
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default.
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If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether
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they are set or not. Flags is still Ored though.
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If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead
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of ORed.
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=head1 NOTES
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The above functions should be used to manipulate verification parameters
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instead of functions which work in specific structures such as
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X509_STORE_CTX_set_flags() which are likely to be deprecated in a future
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release.
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=head1 BUGS
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Delta CRL checking is currently primitive. Only a single delta can be used and
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(partly due to limitations of B<X509_STORE>) constructed CRLs are not
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maintained.
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If CRLs checking is enable CRLs are expected to be available in the
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corresponding B<X509_STORE> structure. No attempt is made to download
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CRLs from the CRL distribution points extension.
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=head1 EXAMPLES
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Enable CRL checking when performing certificate verification during SSL
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connections associated with an B<SSL_CTX> structure B<ctx>:
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X509_VERIFY_PARAM *param;
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param = X509_VERIFY_PARAM_new();
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X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
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SSL_CTX_set1_param(ctx, param);
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X509_VERIFY_PARAM_free(param);
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=head1 SEE ALSO
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L<X509_verify_cert(3)>,
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L<X509_check_host(3)>,
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L<X509_check_email(3)>,
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L<X509_check_ip(3)>,
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L<openssl-x509(1)>
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=head1 HISTORY
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The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0.
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The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0
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and has no effect.
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The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i.
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The X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(),
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and X509_VERIFY_PARAM_get1_ip_asc() functions were added in OpenSSL 3.0.
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The function X509_VERIFY_PARAM_add0_policy() was historically documented as
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enabling policy checking however the implementation has never done this.
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The documentation was changed to align with the implementation.
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=head1 COPYRIGHT
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Copyright 2009-2023 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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