/* Given the certificate CERT locate the issuer for this certificate
and return it at R_CERT. Returns 0 on success or
GPG_ERR_NOT_FOUND. */
gpg_error_t
find_issuing_cert (ctrl_t ctrl, ksba_cert_t cert, ksba_cert_t *r_cert)
{
gpg_error_t err;
char *issuer_dn;
ksba_cert_t issuer_cert = NULL;
ksba_name_t authid;
ksba_sexp_t authidno;
ksba_sexp_t keyid;
*r_cert = NULL;
issuer_dn = ksba_cert_get_issuer (cert, 0);
if (!issuer_dn)
{
log_error (_("no issuer found in certificate\n"));
err = gpg_error (GPG_ERR_BAD_CERT);
goto leave;
}
/* First we need to check whether we can return that certificate
using the authorithyKeyIdentifier. */
err = ksba_cert_get_auth_key_id (cert, &keyid, &authid, &authidno);
if (err)
{
log_info (_("error getting authorityKeyIdentifier: %s\n"),
gpg_strerror (err));
}
else
{
const char *s = ksba_name_enum (authid, 0);
if (s && *authidno)
{
issuer_cert = find_cert_bysn (ctrl, s, authidno);
}
if (!issuer_cert && keyid)
{
/* Not found by issuer+s/n. Now that we have an AKI
keyIdentifier look for a certificate with a matching
SKI. */
issuer_cert = find_cert_bysubject (ctrl, issuer_dn, keyid);
}
/* Print a note so that the user does not feel too helpless when
an issuer certificate was found and gpgsm prints BAD
signature because it is not the correct one. */
if (!issuer_cert)
{
log_info ("issuer certificate ");
if (keyid)
{
log_printf ("{");
dump_serial (keyid);
log_printf ("} ");
}
if (authidno)
{
log_printf ("(#");
dump_serial (authidno);
log_printf ("/");
dump_string (s);
log_printf (") ");
}
log_printf ("not found using authorityKeyIdentifier\n");
}
ksba_name_release (authid);
xfree (authidno);
xfree (keyid);
}
/* If this did not work, try just with the issuer's name and assume
that there is only one such certificate. We only look into our
cache then. */
if (err || !issuer_cert)
{
issuer_cert = get_cert_bysubject (issuer_dn, 0);
if (issuer_cert)
err = 0;
}
leave:
if (!err && !issuer_cert)
err = gpg_error (GPG_ERR_NOT_FOUND);
xfree (issuer_dn);
if (err)
ksba_cert_release (issuer_cert);
else
*r_cert = issuer_cert;
return err;
}
/* Check whether CERT is a root certificate. ISSUERDN and SUBJECTDN
are the DNs already extracted by the caller from CERT. Returns
True if this is the case. */
static int
is_root_cert (ksba_cert_t cert, const char *issuerdn, const char *subjectdn)
{
gpg_error_t err;
int result = 0;
ksba_sexp_t serialno;
ksba_sexp_t ak_keyid;
ksba_name_t ak_name;
ksba_sexp_t ak_sn;
const char *ak_name_str;
ksba_sexp_t subj_keyid = NULL;
if (!issuerdn || !subjectdn)
return 0; /* No. */
if (strcmp (issuerdn, subjectdn))
return 0; /* No. */
err = ksba_cert_get_auth_key_id (cert, &ak_keyid, &ak_name, &ak_sn);
if (err)
{
if (gpg_err_code (err) == GPG_ERR_NO_DATA)
return 1; /* Yes. Without a authorityKeyIdentifier this needs
to be the Root certifcate (our trust anchor). */
log_error ("error getting authorityKeyIdentifier: %s\n",
gpg_strerror (err));
return 0; /* Well, it is broken anyway. Return No. */
}
serialno = ksba_cert_get_serial (cert);
if (!serialno)
{
log_error ("error getting serialno: %s\n", gpg_strerror (err));
goto leave;
}
/* Check whether the auth name's matches the issuer name+sn. If
that is the case this is a root certificate. */
ak_name_str = ksba_name_enum (ak_name, 0);
if (ak_name_str
&& !strcmp (ak_name_str, issuerdn)
&& !cmp_simple_canon_sexp (ak_sn, serialno))
{
result = 1; /* Right, CERT is self-signed. */
goto leave;
}
/* Similar for the ak_keyid. */
if (ak_keyid && !ksba_cert_get_subj_key_id (cert, NULL, &subj_keyid)
&& !cmp_simple_canon_sexp (ak_keyid, subj_keyid))
{
result = 1; /* Right, CERT is self-signed. */
goto leave;
}
leave:
ksba_free (subj_keyid);
ksba_free (ak_keyid);
ksba_name_release (ak_name);
ksba_free (ak_sn);
ksba_free (serialno);
return result;
}
/* Check whether the certificate either given by fingerprint CERT_FPR
or directly through the CERT object is valid by running an OCSP
transaction. With FORCE_DEFAULT_RESPONDER set only the configured
default responder is used. */
gpg_error_t
ocsp_isvalid (ctrl_t ctrl, ksba_cert_t cert, const char *cert_fpr,
int force_default_responder)
{
gpg_error_t err;
ksba_ocsp_t ocsp = NULL;
ksba_cert_t issuer_cert = NULL;
ksba_sexp_t sigval = NULL;
gcry_sexp_t s_sig = NULL;
ksba_isotime_t current_time;
ksba_isotime_t this_update, next_update, revocation_time, produced_at;
ksba_isotime_t tmp_time;
ksba_status_t status;
ksba_crl_reason_t reason;
char *url_buffer = NULL;
const char *url;
gcry_md_hd_t md = NULL;
int i, idx;
char *oid;
ksba_name_t name;
fingerprint_list_t default_signer = NULL;
/* Get the certificate. */
if (cert)
{
ksba_cert_ref (cert);
err = find_issuing_cert (ctrl, cert, &issuer_cert);
if (err)
{
log_error (_("issuer certificate not found: %s\n"),
gpg_strerror (err));
goto leave;
}
}
else
{
cert = get_cert_local (ctrl, cert_fpr);
if (!cert)
{
log_error (_("caller did not return the target certificate\n"));
err = gpg_error (GPG_ERR_GENERAL);
goto leave;
}
issuer_cert = get_issuing_cert_local (ctrl, NULL);
if (!issuer_cert)
{
log_error (_("caller did not return the issuing certificate\n"));
err = gpg_error (GPG_ERR_GENERAL);
goto leave;
}
}
/* Create an OCSP instance. */
err = ksba_ocsp_new (&ocsp);
if (err)
{
log_error (_("failed to allocate OCSP context: %s\n"),
gpg_strerror (err));
goto leave;
}
/* Figure out the OCSP responder to use.
1. Try to get the reponder from the certificate.
We do only take http and https style URIs into account.
2. If this fails use the default responder, if any.
*/
url = NULL;
for (idx=0; !url && !opt.ignore_ocsp_service_url && !force_default_responder
&& !(err=ksba_cert_get_authority_info_access (cert, idx,
&oid, &name)); idx++)
{
if ( !strcmp (oid, oidstr_ocsp) )
{
for (i=0; !url && ksba_name_enum (name, i); i++)
{
char *p = ksba_name_get_uri (name, i);
if (p && (!ascii_strncasecmp (p, "http:", 5)
|| !ascii_strncasecmp (p, "https:", 6)))
url = url_buffer = p;
else
xfree (p);
}
}
ksba_name_release (name);
ksba_free (oid);
}
if (err && gpg_err_code (err) != GPG_ERR_EOF)
{
log_error (_("can't get authorityInfoAccess: %s\n"), gpg_strerror (err));
goto leave;
}
if (!url)
{
if (!opt.ocsp_responder || !*opt.ocsp_responder)
{
log_info (_("no default OCSP responder defined\n"));
err = gpg_error (GPG_ERR_CONFIGURATION);
goto leave;
}
if (!opt.ocsp_signer)
{
log_info (_("no default OCSP signer defined\n"));
err = gpg_error (GPG_ERR_CONFIGURATION);
goto leave;
}
url = opt.ocsp_responder;
default_signer = opt.ocsp_signer;
if (opt.verbose)
log_info (_("using default OCSP responder '%s'\n"), url);
}
else
{
if (opt.verbose)
log_info (_("using OCSP responder '%s'\n"), url);
}
/* Ask the OCSP responder. */
err = gcry_md_open (&md, GCRY_MD_SHA1, 0);
if (err)
{
log_error (_("failed to establish a hashing context for OCSP: %s\n"),
gpg_strerror (err));
goto leave;
}
err = do_ocsp_request (ctrl, ocsp, md, url, cert, issuer_cert);
if (err)
goto leave;
/* We got a useful answer, check that the answer has a valid signature. */
sigval = ksba_ocsp_get_sig_val (ocsp, produced_at);
if (!sigval || !*produced_at)
{
err = gpg_error (GPG_ERR_INV_OBJ);
goto leave;
}
if ( (err = canon_sexp_to_gcry (sigval, &s_sig)) )
goto leave;
xfree (sigval);
sigval = NULL;
err = check_signature (ctrl, ocsp, s_sig, md, default_signer);
if (err)
goto leave;
/* We only support one certificate per request. Check that the
answer matches the right certificate. */
err = ksba_ocsp_get_status (ocsp, cert,
&status, this_update, next_update,
revocation_time, &reason);
if (err)
{
log_error (_("error getting OCSP status for target certificate: %s\n"),
gpg_strerror (err));
goto leave;
}
/* In case the certificate has been revoked, we better invalidate
our cached validation status. */
if (status == KSBA_STATUS_REVOKED)
{
time_t validated_at = 0; /* That is: No cached validation available. */
err = ksba_cert_set_user_data (cert, "validated_at",
&validated_at, sizeof (validated_at));
if (err)
{
log_error ("set_user_data(validated_at) failed: %s\n",
gpg_strerror (err));
err = 0; /* The certificate is anyway revoked, and that is a
more important message than the failure of our
cache. */
}
}
if (opt.verbose)
{
log_info (_("certificate status is: %s (this=%s next=%s)\n"),
status == KSBA_STATUS_GOOD? _("good"):
status == KSBA_STATUS_REVOKED? _("revoked"):
status == KSBA_STATUS_UNKNOWN? _("unknown"):
status == KSBA_STATUS_NONE? _("none"): "?",
this_update, next_update);
if (status == KSBA_STATUS_REVOKED)
log_info (_("certificate has been revoked at: %s due to: %s\n"),
revocation_time,
reason == KSBA_CRLREASON_UNSPECIFIED? "unspecified":
reason == KSBA_CRLREASON_KEY_COMPROMISE? "key compromise":
reason == KSBA_CRLREASON_CA_COMPROMISE? "CA compromise":
reason == KSBA_CRLREASON_AFFILIATION_CHANGED?
"affiliation changed":
reason == KSBA_CRLREASON_SUPERSEDED? "superseeded":
reason == KSBA_CRLREASON_CESSATION_OF_OPERATION?
"cessation of operation":
reason == KSBA_CRLREASON_CERTIFICATE_HOLD?
"certificate on hold":
reason == KSBA_CRLREASON_REMOVE_FROM_CRL?
"removed from CRL":
reason == KSBA_CRLREASON_PRIVILEGE_WITHDRAWN?
"privilege withdrawn":
reason == KSBA_CRLREASON_AA_COMPROMISE? "AA compromise":
reason == KSBA_CRLREASON_OTHER? "other":"?");
}
if (status == KSBA_STATUS_REVOKED)
err = gpg_error (GPG_ERR_CERT_REVOKED);
else if (status == KSBA_STATUS_UNKNOWN)
err = gpg_error (GPG_ERR_NO_DATA);
else if (status != KSBA_STATUS_GOOD)
err = gpg_error (GPG_ERR_GENERAL);
/* Allow for some clock skew. */
gnupg_get_isotime (current_time);
add_seconds_to_isotime (current_time, opt.ocsp_max_clock_skew);
if (strcmp (this_update, current_time) > 0 )
{
log_error (_("OCSP responder returned a status in the future\n"));
log_info ("used now: %s this_update: %s\n", current_time, this_update);
if (!err)
err = gpg_error (GPG_ERR_TIME_CONFLICT);
}
/* Check that THIS_UPDATE is not too far back in the past. */
gnupg_copy_time (tmp_time, this_update);
add_seconds_to_isotime (tmp_time,
opt.ocsp_max_period+opt.ocsp_max_clock_skew);
if (!*tmp_time || strcmp (tmp_time, current_time) < 0 )
{
log_error (_("OCSP responder returned a non-current status\n"));
log_info ("used now: %s this_update: %s\n",
current_time, this_update);
if (!err)
err = gpg_error (GPG_ERR_TIME_CONFLICT);
}
/* Check that we are not beyound NEXT_UPDATE (plus some extra time). */
if (*next_update)
{
gnupg_copy_time (tmp_time, next_update);
add_seconds_to_isotime (tmp_time,
opt.ocsp_current_period+opt.ocsp_max_clock_skew);
if (!*tmp_time && strcmp (tmp_time, current_time) < 0 )
{
log_error (_("OCSP responder returned an too old status\n"));
log_info ("used now: %s next_update: %s\n",
current_time, next_update);
if (!err)
err = gpg_error (GPG_ERR_TIME_CONFLICT);
}
}
leave:
gcry_md_close (md);
gcry_sexp_release (s_sig);
xfree (sigval);
ksba_cert_release (issuer_cert);
ksba_cert_release (cert);
ksba_ocsp_release (ocsp);
xfree (url_buffer);
return err;
}
