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src/usr.sbin/rpki-client/x509.c

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/* $OpenBSD: x509.c,v 1.87 2024/04/21 09:03:22 job Exp $ */
/*
* Copyright (c) 2022 Theo Buehler <tb@openbsd.org>
* Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
* Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <err.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <openssl/evp.h>
#include <openssl/x509v3.h>
#include "extern.h"
ASN1_OBJECT *certpol_oid; /* id-cp-ipAddr-asNumber cert policy */
ASN1_OBJECT *carepo_oid; /* 1.3.6.1.5.5.7.48.5 (caRepository) */
ASN1_OBJECT *manifest_oid; /* 1.3.6.1.5.5.7.48.10 (rpkiManifest) */
ASN1_OBJECT *signedobj_oid; /* 1.3.6.1.5.5.7.48.11 (signedObject) */
ASN1_OBJECT *notify_oid; /* 1.3.6.1.5.5.7.48.13 (rpkiNotify) */
ASN1_OBJECT *roa_oid; /* id-ct-routeOriginAuthz CMS content type */
ASN1_OBJECT *mft_oid; /* id-ct-rpkiManifest CMS content type */
ASN1_OBJECT *gbr_oid; /* id-ct-rpkiGhostbusters CMS content type */
ASN1_OBJECT *bgpsec_oid; /* id-kp-bgpsec-router Key Purpose */
ASN1_OBJECT *cnt_type_oid; /* pkcs-9 id-contentType */
ASN1_OBJECT *msg_dgst_oid; /* pkcs-9 id-messageDigest */
ASN1_OBJECT *sign_time_oid; /* pkcs-9 id-signingTime */
ASN1_OBJECT *rsc_oid; /* id-ct-signedChecklist */
ASN1_OBJECT *aspa_oid; /* id-ct-ASPA */
ASN1_OBJECT *tak_oid; /* id-ct-SignedTAL */
ASN1_OBJECT *geofeed_oid; /* id-ct-geofeedCSVwithCRLF */
ASN1_OBJECT *spl_oid; /* id-ct-signedPrefixList */
static const struct {
const char *oid;
ASN1_OBJECT **ptr;
} oid_table[] = {
{
.oid = "1.3.6.1.5.5.7.14.2",
.ptr = &certpol_oid,
},
{
.oid = "1.3.6.1.5.5.7.48.5",
.ptr = &carepo_oid,
},
{
.oid = "1.3.6.1.5.5.7.48.10",
.ptr = &manifest_oid,
},
{
.oid = "1.3.6.1.5.5.7.48.11",
.ptr = &signedobj_oid,
},
{
.oid = "1.3.6.1.5.5.7.48.13",
.ptr = &notify_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.24",
.ptr = &roa_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.26",
.ptr = &mft_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.35",
.ptr = &gbr_oid,
},
{
.oid = "1.3.6.1.5.5.7.3.30",
.ptr = &bgpsec_oid,
},
{
.oid = "1.2.840.113549.1.9.3",
.ptr = &cnt_type_oid,
},
{
.oid = "1.2.840.113549.1.9.4",
.ptr = &msg_dgst_oid,
},
{
.oid = "1.2.840.113549.1.9.5",
.ptr = &sign_time_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.47",
.ptr = &geofeed_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.48",
.ptr = &rsc_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.49",
.ptr = &aspa_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.50",
.ptr = &tak_oid,
},
{
.oid = "1.2.840.113549.1.9.16.1.51",
.ptr = &spl_oid,
},
};
void
x509_init_oid(void)
{
size_t i;
for (i = 0; i < sizeof(oid_table) / sizeof(oid_table[0]); i++) {
*oid_table[i].ptr = OBJ_txt2obj(oid_table[i].oid, 1);
if (*oid_table[i].ptr == NULL)
errx(1, "OBJ_txt2obj for %s failed", oid_table[i].oid);
}
}
/*
* Parse X509v3 authority key identifier (AKI), RFC 6487 sec. 4.8.3.
* Returns the AKI or NULL if it could not be parsed.
* The AKI is formatted as a hex string.
*/
int
x509_get_aki(X509 *x, const char *fn, char **aki)
{
const unsigned char *d;
AUTHORITY_KEYID *akid;
ASN1_OCTET_STRING *os;
int dsz, crit, rc = 0;
*aki = NULL;
akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &crit, NULL);
if (akid == NULL) {
if (crit != -1) {
warnx("%s: RFC 6487 section 4.8.3: error parsing AKI",
fn);
return 0;
}
return 1;
}
if (crit != 0) {
warnx("%s: RFC 6487 section 4.8.3: "
"AKI: extension not non-critical", fn);
goto out;
}
if (akid->issuer != NULL || akid->serial != NULL) {
warnx("%s: RFC 6487 section 4.8.3: AKI: "
"authorityCertIssuer or authorityCertSerialNumber present",
fn);
goto out;
}
os = akid->keyid;
if (os == NULL) {
warnx("%s: RFC 6487 section 4.8.3: AKI: "
"Key Identifier missing", fn);
goto out;
}
d = os->data;
dsz = os->length;
if (dsz != SHA_DIGEST_LENGTH) {
warnx("%s: RFC 6487 section 4.8.2: AKI: "
"want %d bytes SHA1 hash, have %d bytes",
fn, SHA_DIGEST_LENGTH, dsz);
goto out;
}
*aki = hex_encode(d, dsz);
rc = 1;
out:
AUTHORITY_KEYID_free(akid);
return rc;
}
/*
* Validate the X509v3 subject key identifier (SKI), RFC 6487 section 4.8.2:
* "The SKI is a SHA-1 hash of the value of the DER-encoded ASN.1 BIT STRING of
* the Subject Public Key, as described in Section 4.2.1.2 of RFC 5280."
* Returns the SKI formatted as hex string, or NULL if it couldn't be parsed.
*/
int
x509_get_ski(X509 *x, const char *fn, char **ski)
{
ASN1_OCTET_STRING *os;
unsigned char md[EVP_MAX_MD_SIZE];
unsigned int md_len = EVP_MAX_MD_SIZE;
int crit, rc = 0;
*ski = NULL;
os = X509_get_ext_d2i(x, NID_subject_key_identifier, &crit, NULL);
if (os == NULL) {
if (crit != -1) {
warnx("%s: RFC 6487 section 4.8.2: error parsing SKI",
fn);
return 0;
}
return 1;
}
if (crit != 0) {
warnx("%s: RFC 6487 section 4.8.2: "
"SKI: extension not non-critical", fn);
goto out;
}
if (!X509_pubkey_digest(x, EVP_sha1(), md, &md_len)) {
warnx("%s: X509_pubkey_digest", fn);
goto out;
}
if (os->length < 0 || md_len != (size_t)os->length) {
warnx("%s: RFC 6487 section 4.8.2: SKI: "
"want %u bytes SHA1 hash, have %d bytes",
fn, md_len, os->length);
goto out;
}
if (memcmp(os->data, md, md_len) != 0) {
warnx("%s: SKI does not match SHA1 hash of SPK", fn);
goto out;
}
*ski = hex_encode(md, md_len);
rc = 1;
out:
ASN1_OCTET_STRING_free(os);
return rc;
}
/*
* Check the certificate's purpose: CA or BGPsec Router.
* Return a member of enum cert_purpose.
*/
enum cert_purpose
x509_get_purpose(X509 *x, const char *fn)
{
BASIC_CONSTRAINTS *bc = NULL;
EXTENDED_KEY_USAGE *eku = NULL;
int crit;
enum cert_purpose purpose = CERT_PURPOSE_INVALID;
if (X509_check_ca(x) == 1) {
bc = X509_get_ext_d2i(x, NID_basic_constraints, &crit, NULL);
if (bc == NULL) {
if (crit != -1)
warnx("%s: RFC 6487 section 4.8.1: "
"error parsing basic constraints", fn);
else
warnx("%s: RFC 6487 section 4.8.1: "
"missing basic constraints", fn);
goto out;
}
if (crit != 1) {
warnx("%s: RFC 6487 section 4.8.1: Basic Constraints "
"must be marked critical", fn);
goto out;
}
if (bc->pathlen != NULL) {
warnx("%s: RFC 6487 section 4.8.1: Path Length "
"Constraint must be absent", fn);
goto out;
}
purpose = CERT_PURPOSE_CA;
goto out;
}
if (X509_get_extension_flags(x) & EXFLAG_BCONS) {
warnx("%s: Basic Constraints ext in non-CA cert", fn);
goto out;
}
eku = X509_get_ext_d2i(x, NID_ext_key_usage, &crit, NULL);
if (eku == NULL) {
if (crit != -1)
warnx("%s: error parsing EKU", fn);
else
warnx("%s: EKU: extension missing", fn);
goto out;
}
if (crit != 0) {
warnx("%s: EKU: extension must not be marked critical", fn);
goto out;
}
if (sk_ASN1_OBJECT_num(eku) != 1) {
warnx("%s: EKU: expected 1 purpose, have %d", fn,
sk_ASN1_OBJECT_num(eku));
goto out;
}
if (OBJ_cmp(bgpsec_oid, sk_ASN1_OBJECT_value(eku, 0)) == 0) {
purpose = CERT_PURPOSE_BGPSEC_ROUTER;
goto out;
}
out:
BASIC_CONSTRAINTS_free(bc);
EXTENDED_KEY_USAGE_free(eku);
return purpose;
}
/*
* Extract Subject Public Key Info (SPKI) from BGPsec X.509 Certificate.
* Returns NULL on failure, on success return the SPKI as base64 encoded pubkey
*/
char *
x509_get_pubkey(X509 *x, const char *fn)
{
EVP_PKEY *pkey;
EC_KEY *eckey;
int nid;
const char *cname;
uint8_t *pubkey = NULL;
char *res = NULL;
int len;
pkey = X509_get0_pubkey(x);
if (pkey == NULL) {
warnx("%s: X509_get0_pubkey failed in %s", fn, __func__);
goto out;
}
if (EVP_PKEY_base_id(pkey) != EVP_PKEY_EC) {
warnx("%s: Expected EVP_PKEY_EC, got %d", fn,
EVP_PKEY_base_id(pkey));
goto out;
}
eckey = EVP_PKEY_get0_EC_KEY(pkey);
if (eckey == NULL) {
warnx("%s: Incorrect key type", fn);
goto out;
}
nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(eckey));
if (nid != NID_X9_62_prime256v1) {
if ((cname = EC_curve_nid2nist(nid)) == NULL)
cname = nid2str(nid);
warnx("%s: Expected P-256, got %s", fn, cname);
goto out;
}
if (!EC_KEY_check_key(eckey)) {
warnx("%s: EC_KEY_check_key failed in %s", fn, __func__);
goto out;
}
len = i2d_PUBKEY(pkey, &pubkey);
if (len <= 0) {
warnx("%s: i2d_PUBKEY failed in %s", fn, __func__);
goto out;
}
if (base64_encode(pubkey, len, &res) == -1)
errx(1, "base64_encode failed in %s", __func__);
out:
free(pubkey);
return res;
}
/*
* Compute the SKI of an RSA public key in an X509_PUBKEY using SHA-1.
* Returns allocated hex-encoded SKI on success, NULL on failure.
*/
char *
x509_pubkey_get_ski(X509_PUBKEY *pubkey, const char *fn)
{
ASN1_OBJECT *obj;
const unsigned char *der;
int der_len, nid;
unsigned char md[EVP_MAX_MD_SIZE];
unsigned int md_len = EVP_MAX_MD_SIZE;
if (!X509_PUBKEY_get0_param(&obj, &der, &der_len, NULL, pubkey)) {
warnx("%s: X509_PUBKEY_get0_param failed", fn);
return NULL;
}
if ((nid = OBJ_obj2nid(obj)) != NID_rsaEncryption) {
warnx("%s: RFC 7935: wrong signature algorithm %s, want %s",
fn, nid2str(nid), LN_rsaEncryption);
return NULL;
}
if (!EVP_Digest(der, der_len, md, &md_len, EVP_sha1(), NULL)) {
warnx("%s: EVP_Digest failed", fn);
return NULL;
}
return hex_encode(md, md_len);
}
/*
* Parse the Authority Information Access (AIA) extension
* See RFC 6487, section 4.8.7 for details.
* Returns NULL on failure, on success returns the AIA URI
* (which has to be freed after use).
*/
int
x509_get_aia(X509 *x, const char *fn, char **aia)
{
ACCESS_DESCRIPTION *ad;
AUTHORITY_INFO_ACCESS *info;
int crit, rc = 0;
*aia = NULL;
info = X509_get_ext_d2i(x, NID_info_access, &crit, NULL);
if (info == NULL) {
if (crit != -1) {
warnx("%s: RFC 6487 section 4.8.7: error parsing AIA",
fn);
return 0;
}
return 1;
}
if (crit != 0) {
warnx("%s: RFC 6487 section 4.8.7: "
"AIA: extension not non-critical", fn);
goto out;
}
if ((X509_get_extension_flags(x) & EXFLAG_SS) != 0) {
warnx("%s: RFC 6487 section 4.8.7: AIA must be absent from "
"a self-signed certificate", fn);
goto out;
}
if (sk_ACCESS_DESCRIPTION_num(info) != 1) {
warnx("%s: RFC 6487 section 4.8.7: AIA: "
"want 1 element, have %d", fn,
sk_ACCESS_DESCRIPTION_num(info));
goto out;
}
ad = sk_ACCESS_DESCRIPTION_value(info, 0);
if (OBJ_obj2nid(ad->method) != NID_ad_ca_issuers) {
warnx("%s: RFC 6487 section 4.8.7: AIA: "
"expected caIssuers, have %d", fn, OBJ_obj2nid(ad->method));
goto out;
}
if (!x509_location(fn, "AIA: caIssuers", NULL, ad->location, aia))
goto out;
rc = 1;
out:
AUTHORITY_INFO_ACCESS_free(info);
return rc;
}
/*
* Parse the Subject Information Access (SIA) extension
* See RFC 6487, section 4.8.8 for details.
* Returns NULL on failure, on success returns the SIA signedObject URI
* (which has to be freed after use).
*/
int
x509_get_sia(X509 *x, const char *fn, char **sia)
{
ACCESS_DESCRIPTION *ad;
AUTHORITY_INFO_ACCESS *info;
ASN1_OBJECT *oid;
int i, crit, rsync_found = 0;
*sia = NULL;
info = X509_get_ext_d2i(x, NID_sinfo_access, &crit, NULL);
if (info == NULL) {
if (crit != -1) {
warnx("%s: error parsing SIA", fn);
return 0;
}
return 1;
}
if (crit != 0) {
warnx("%s: RFC 6487 section 4.8.8: "
"SIA: extension not non-critical", fn);
goto out;
}
for (i = 0; i < sk_ACCESS_DESCRIPTION_num(info); i++) {
ad = sk_ACCESS_DESCRIPTION_value(info, i);
oid = ad->method;
/*
* XXX: RFC 6487 4.8.8.2 states that the accessMethod MUST be
* signedObject. However, rpkiNotify accessMethods currently
* exist in the wild. Consider removing this special case.
* See also https://www.rfc-editor.org/errata/eid7239.
*/
if (OBJ_cmp(oid, notify_oid) == 0) {
if (verbose > 1)
warnx("%s: RFC 6487 section 4.8.8.2: SIA should"
" not contain rpkiNotify accessMethod", fn);
continue;
}
if (OBJ_cmp(oid, signedobj_oid) != 0) {
char buf[128];
OBJ_obj2txt(buf, sizeof(buf), oid, 0);
warnx("%s: RFC 6487 section 4.8.8.2: unexpected"
" accessMethod: %s", fn, buf);
goto out;
}
/* Don't fail on non-rsync URI, so check this afterward. */
if (!x509_location(fn, "SIA: signedObject", NULL, ad->location,
sia))
goto out;
if (rsync_found)
continue;
if (strncasecmp(*sia, RSYNC_PROTO, RSYNC_PROTO_LEN) == 0) {
const char *p = *sia + RSYNC_PROTO_LEN;
size_t fnlen, plen;
rsync_found = 1;
if (filemode)
continue;
fnlen = strlen(fn);
plen = strlen(p);
if (fnlen < plen || strcmp(p, fn + fnlen - plen) != 0) {
warnx("%s: mismatch between pathname and SIA "
"(%s)", fn, *sia);
goto out;
}
continue;
}
free(*sia);
*sia = NULL;
}
if (!rsync_found) {
warnx("%s: RFC 6487 section 4.8.8.2: "
"SIA without rsync accessLocation", fn);
goto out;
}
AUTHORITY_INFO_ACCESS_free(info);
return 1;
out:
free(*sia);
*sia = NULL;
AUTHORITY_INFO_ACCESS_free(info);
return 0;
}
/*
* Extract the notBefore of a certificate.
*/
int
x509_get_notbefore(X509 *x, const char *fn, time_t *tt)
{
const ASN1_TIME *at;
at = X509_get0_notBefore(x);
if (at == NULL) {
warnx("%s: X509_get0_notBefore failed", fn);
return 0;
}
if (!x509_get_time(at, tt)) {
warnx("%s: ASN1_TIME_to_tm failed", fn);
return 0;
}
return 1;
}
/*
* Extract the notAfter from a certificate.
*/
int
x509_get_notafter(X509 *x, const char *fn, time_t *tt)
{
const ASN1_TIME *at;
at = X509_get0_notAfter(x);
if (at == NULL) {
warnx("%s: X509_get0_notafter failed", fn);
return 0;
}
if (!x509_get_time(at, tt)) {
warnx("%s: ASN1_TIME_to_tm failed", fn);
return 0;
}
return 1;
}
/*
* Check whether all RFC 3779 extensions are set to inherit.
* Return 1 if both AS & IP are set to inherit.
* Return 0 on failure (such as missing extensions or no inheritance).
*/
int
x509_inherits(X509 *x)
{
STACK_OF(IPAddressFamily) *addrblk = NULL;
ASIdentifiers *asidentifiers = NULL;
const IPAddressFamily *af;
int crit, i, rc = 0;
addrblk = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &crit, NULL);
if (addrblk == NULL) {
if (crit != -1)
warnx("error parsing ipAddrBlock");
goto out;
}
/*
* Check by hand, since X509v3_addr_inherits() success only means that
* at least one address family inherits, not all of them.
*/
for (i = 0; i < sk_IPAddressFamily_num(addrblk); i++) {
af = sk_IPAddressFamily_value(addrblk, i);
if (af->ipAddressChoice->type != IPAddressChoice_inherit)
goto out;
}
asidentifiers = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, NULL,
NULL);
if (asidentifiers == NULL) {
if (crit != -1)
warnx("error parsing asIdentifiers");
goto out;
}
/* We need to have AS numbers and don't want RDIs. */
if (asidentifiers->asnum == NULL || asidentifiers->rdi != NULL)
goto out;
if (!X509v3_asid_inherits(asidentifiers))
goto out;
rc = 1;
out:
ASIdentifiers_free(asidentifiers);
sk_IPAddressFamily_pop_free(addrblk, IPAddressFamily_free);
return rc;
}
/*
* Check whether at least one RFC 3779 extension is set to inherit.
* Return 1 if an inherit element is encountered in AS or IP.
* Return 0 otherwise.
*/
int
x509_any_inherits(X509 *x)
{
STACK_OF(IPAddressFamily) *addrblk = NULL;
ASIdentifiers *asidentifiers = NULL;
int crit, rc = 0;
addrblk = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &crit, NULL);
if (addrblk == NULL && crit != -1)
warnx("error parsing ipAddrBlock");
if (X509v3_addr_inherits(addrblk))
rc = 1;
asidentifiers = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, &crit,
NULL);
if (asidentifiers == NULL && crit != -1)
warnx("error parsing asIdentifiers");
if (X509v3_asid_inherits(asidentifiers))
rc = 1;
ASIdentifiers_free(asidentifiers);
sk_IPAddressFamily_pop_free(addrblk, IPAddressFamily_free);
return rc;
}
/*
* Parse the very specific subset of information in the CRL distribution
* point extension.
* See RFC 6487, section 4.8.6 for details.
* Returns NULL on failure, the crl URI on success which has to be freed
* after use.
*/
int
x509_get_crl(X509 *x, const char *fn, char **crl)
{
CRL_DIST_POINTS *crldp;
DIST_POINT *dp;
GENERAL_NAMES *names;
GENERAL_NAME *name;
int i, crit, rsync_found = 0;
*crl = NULL;
crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &crit, NULL);
if (crldp == NULL) {
if (crit != -1) {
warnx("%s: RFC 6487 section 4.8.6: failed to parse "
"CRL distribution points", fn);
return 0;
}
return 1;
}
if (crit != 0) {
warnx("%s: RFC 6487 section 4.8.6: "
"CRL distribution point: extension not non-critical", fn);
goto out;
}
if (sk_DIST_POINT_num(crldp) != 1) {
warnx("%s: RFC 6487 section 4.8.6: CRL: "
"want 1 element, have %d", fn,
sk_DIST_POINT_num(crldp));
goto out;
}
dp = sk_DIST_POINT_value(crldp, 0);
if (dp->CRLissuer != NULL) {
warnx("%s: RFC 6487 section 4.8.6: CRL CRLIssuer field"
" disallowed", fn);
goto out;
}
if (dp->reasons != NULL) {
warnx("%s: RFC 6487 section 4.8.6: CRL Reasons field"
" disallowed", fn);
goto out;
}
if (dp->distpoint == NULL) {
warnx("%s: RFC 6487 section 4.8.6: CRL: "
"no distribution point name", fn);
goto out;
}
if (dp->distpoint->dpname != NULL) {
warnx("%s: RFC 6487 section 4.8.6: nameRelativeToCRLIssuer"
" disallowed", fn);
goto out;
}
/* Need to hardcode the alternative 0 due to missing macros or enum. */
if (dp->distpoint->type != 0) {
warnx("%s: RFC 6487 section 4.8.6: CRL DistributionPointName:"
" expected fullName, have %d", fn, dp->distpoint->type);
goto out;
}
names = dp->distpoint->name.fullname;
for (i = 0; i < sk_GENERAL_NAME_num(names); i++) {
name = sk_GENERAL_NAME_value(names, i);
/* Don't fail on non-rsync URI, so check this afterward. */
if (!x509_location(fn, "CRL distribution point", NULL, name,
crl))
goto out;
if (strncasecmp(*crl, RSYNC_PROTO, RSYNC_PROTO_LEN) == 0) {
rsync_found = 1;
goto out;
}
free(*crl);
*crl = NULL;
}
warnx("%s: RFC 6487 section 4.8.6: no rsync URI "
"in CRL distributionPoint", fn);
out:
CRL_DIST_POINTS_free(crldp);
return rsync_found;
}
/*
* Parse X509v3 authority key identifier (AKI) from the CRL.
* This is matched against the string from x509_get_ski() above.
* Returns the AKI or NULL if it could not be parsed.
* The AKI is formatted as a hex string.
*/
char *
x509_crl_get_aki(X509_CRL *crl, const char *fn)
{
const unsigned char *d;
AUTHORITY_KEYID *akid;
ASN1_OCTET_STRING *os;
int dsz, crit;
char *res = NULL;
akid = X509_CRL_get_ext_d2i(crl, NID_authority_key_identifier, &crit,
NULL);
if (akid == NULL) {
warnx("%s: RFC 6487 section 4.8.3: AKI: extension missing", fn);
return NULL;
}
if (crit != 0) {
warnx("%s: RFC 6487 section 4.8.3: "
"AKI: extension not non-critical", fn);
goto out;
}
if (akid->issuer != NULL || akid->serial != NULL) {
warnx("%s: RFC 6487 section 4.8.3: AKI: "
"authorityCertIssuer or authorityCertSerialNumber present",
fn);
goto out;
}
os = akid->keyid;
if (os == NULL) {
warnx("%s: RFC 6487 section 4.8.3: AKI: "
"Key Identifier missing", fn);
goto out;
}
d = os->data;
dsz = os->length;
if (dsz != SHA_DIGEST_LENGTH) {
warnx("%s: RFC 6487 section 4.8.2: AKI: "
"want %d bytes SHA1 hash, have %d bytes",
fn, SHA_DIGEST_LENGTH, dsz);
goto out;
}
res = hex_encode(d, dsz);
out:
AUTHORITY_KEYID_free(akid);
return res;
}
/*
* Retrieve CRL Number extension. Returns a printable hexadecimal representation
* of the number which has to be freed after use.
*/
char *
x509_crl_get_number(X509_CRL *crl, const char *fn)
{
ASN1_INTEGER *aint;
int crit;
char *res = NULL;
aint = X509_CRL_get_ext_d2i(crl, NID_crl_number, &crit, NULL);
if (aint == NULL) {
warnx("%s: RFC 6487 section 5: CRL Number missing", fn);
return NULL;
}
if (crit != 0) {
warnx("%s: RFC 5280, section 5.2.3: "
"CRL Number not non-critical", fn);
goto out;
}
/* This checks that the number is non-negative and <= 20 bytes. */
res = x509_convert_seqnum(fn, aint);
out:
ASN1_INTEGER_free(aint);
return res;
}
/*
* Convert passed ASN1_TIME to time_t *t.
* Returns 1 on success and 0 on failure.
*/
int
x509_get_time(const ASN1_TIME *at, time_t *t)
{
struct tm tm;
*t = 0;
memset(&tm, 0, sizeof(tm));
/* Fail instead of silently falling back to the current time. */
if (at == NULL)
return 0;
if (!ASN1_TIME_to_tm(at, &tm))
return 0;
if ((*t = timegm(&tm)) == -1)
errx(1, "timegm failed");
return 1;
}
/*
* Extract and validate an accessLocation, RFC 6487, 4.8 and RFC 8182, 3.2.
* Returns 0 on failure and 1 on success.
*/
int
x509_location(const char *fn, const char *descr, const char *proto,
GENERAL_NAME *location, char **out)
{
ASN1_IA5STRING *uri;
if (location->type != GEN_URI) {
warnx("%s: RFC 6487 section 4.8: %s not URI", fn, descr);
return 0;
}
uri = location->d.uniformResourceIdentifier;
if (!valid_uri(uri->data, uri->length, proto)) {
warnx("%s: RFC 6487 section 4.8: %s bad location", fn, descr);
return 0;
}
if (*out != NULL) {
warnx("%s: RFC 6487 section 4.8: multiple %s specified, "
"using the first one", fn, descr);
return 1;
}
if ((*out = strndup(uri->data, uri->length)) == NULL)
err(1, NULL);
return 1;
}
/*
* Check that the subject only contains commonName and serialNumber.
* Return 0 on failure.
*/
int
x509_valid_subject(const char *fn, const X509 *x)
{
const X509_NAME *xn;
const X509_NAME_ENTRY *ne;
const ASN1_OBJECT *ao;
const ASN1_STRING *as;
int cn = 0, sn = 0;
int i, nid;
if ((xn = X509_get_subject_name(x)) == NULL) {
warnx("%s: X509_get_subject_name", fn);
return 0;
}
for (i = 0; i < X509_NAME_entry_count(xn); i++) {
if ((ne = X509_NAME_get_entry(xn, i)) == NULL) {
warnx("%s: X509_NAME_get_entry", fn);
return 0;
}
if ((ao = X509_NAME_ENTRY_get_object(ne)) == NULL) {
warnx("%s: X509_NAME_ENTRY_get_object", fn);
return 0;
}
nid = OBJ_obj2nid(ao);
switch (nid) {
case NID_commonName:
if (cn++ > 0) {
warnx("%s: duplicate commonName in subject",
fn);
return 0;
}
if ((as = X509_NAME_ENTRY_get_data(ne)) == NULL) {
warnx("%s: X509_NAME_ENTRY_get_data failed",
fn);
return 0;
}
/*
* The following check can be enabled after AFRINIC re-issues CA certs.
* https://lists.afrinic.net/pipermail/dbwg/2023-March/000436.html
*/
#if 0
if (ASN1_STRING_type(as) != V_ASN1_PRINTABLESTRING) {
warnx("%s: RFC 6487 section 4.5: commonName is"
" not PrintableString", fn);
return 0;
}
#endif
break;
case NID_serialNumber:
if (sn++ > 0) {
warnx("%s: duplicate serialNumber in subject",
fn);
return 0;
}
break;
case NID_undef:
warnx("%s: OBJ_obj2nid failed", fn);
return 0;
default:
warnx("%s: RFC 6487 section 4.5: unexpected attribute"
" %s", fn, nid2str(nid));
return 0;
}
}
if (cn == 0) {
warnx("%s: RFC 6487 section 4.5: subject missing commonName",
fn);
return 0;
}
return 1;
}
/*
* Convert an ASN1_INTEGER into a hexstring.
* Returned string needs to be freed by the caller.
*/
char *
x509_convert_seqnum(const char *fn, const ASN1_INTEGER *i)
{
BIGNUM *seqnum = NULL;
char *s = NULL;
if (i == NULL)
goto out;
if (ASN1_STRING_length(i) > 20) {
warnx("%s: %s: want 20 octets or fewer, have more.",
__func__, fn);
goto out;
}
seqnum = ASN1_INTEGER_to_BN(i, NULL);
if (seqnum == NULL) {
warnx("%s: ASN1_INTEGER_to_BN error", fn);
goto out;
}
if (BN_is_negative(seqnum)) {
warnx("%s: %s: want positive integer, have negative.",
__func__, fn);
goto out;
}
s = BN_bn2hex(seqnum);
if (s == NULL)
warnx("%s: BN_bn2hex error", fn);
out:
BN_free(seqnum);
return s;
}
/*
* Find the closest expiry moment by walking the chain of authorities.
*/
time_t
x509_find_expires(time_t notafter, struct auth *a, struct crl_tree *crlt)
{
struct crl *crl;
time_t expires;
expires = notafter;
for (; a != NULL; a = a->issuer) {
if (expires > a->cert->notafter)
expires = a->cert->notafter;
crl = crl_get(crlt, a);
if (crl != NULL && expires > crl->nextupdate)
expires = crl->nextupdate;
}
return expires;
}
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