Join the x509 and x509v3 directories

This has been long overdue.

Note that this does not join the X509 and X509V3 error modules, that
will be too many macro changes at this stage.

Fixes #8919

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8925)

1 files changed, 909 insertions, 0 deletions

diff --git a/crypto/x509/v3_purp.c b/crypto/x509/v3_purp.c
new file mode 100644
index 0000000000..d0ac7e6ed9
--- /dev/null
+++ b/crypto/x509/v3_purp.c
@@ -0,0 +1,909 @@
+/*
+ * Copyright 1999-2018 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
+ */
+
+#include <stdio.h>
+#include "internal/cryptlib.h"
+#include "internal/numbers.h"
+#include <openssl/x509v3.h>
+#include <openssl/x509_vfy.h>
+#include "internal/x509_int.h"
+#include "internal/tsan_assist.h"
+
+static void x509v3_cache_extensions(X509 *x);
+
+static int check_ssl_ca(const X509 *x);
+static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
+                                    int ca);
+static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
+                                    int ca);
+static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
+                                       int ca);
+static int purpose_smime(const X509 *x, int ca);
+static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
+                                    int ca);
+static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
+                                       int ca);
+static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
+                                  int ca);
+static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
+                                        int ca);
+static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
+static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
+
+static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b);
+static void xptable_free(X509_PURPOSE *p);
+
+static X509_PURPOSE xstandard[] = {
+    {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0,
+     check_purpose_ssl_client, "SSL client", "sslclient", NULL},
+    {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
+     check_purpose_ssl_server, "SSL server", "sslserver", NULL},
+    {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0,
+     check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
+    {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign,
+     "S/MIME signing", "smimesign", NULL},
+    {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0,
+     check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
+    {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign,
+     "CRL signing", "crlsign", NULL},
+    {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any",
+     NULL},
+    {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper,
+     "OCSP helper", "ocsphelper", NULL},
+    {X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
+     check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign",
+     NULL},
+};
+
+#define X509_PURPOSE_COUNT OSSL_NELEM(xstandard)
+
+static STACK_OF(X509_PURPOSE) *xptable = NULL;
+
+static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b)
+{
+    return (*a)->purpose - (*b)->purpose;
+}
+
+/*
+ * As much as I'd like to make X509_check_purpose use a "const" X509* I
+ * really can't because it does recalculate hashes and do other non-const
+ * things.
+ */
+int X509_check_purpose(X509 *x, int id, int ca)
+{
+    int idx;
+    const X509_PURPOSE *pt;
+
+    x509v3_cache_extensions(x);
+
+    /* Return if side-effect only call */
+    if (id == -1)
+        return 1;
+    idx = X509_PURPOSE_get_by_id(id);
+    if (idx == -1)
+        return -1;
+    pt = X509_PURPOSE_get0(idx);
+    return pt->check_purpose(pt, x, ca);
+}
+
+int X509_PURPOSE_set(int *p, int purpose)
+{
+    if (X509_PURPOSE_get_by_id(purpose) == -1) {
+        X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
+        return 0;
+    }
+    *p = purpose;
+    return 1;
+}
+
+int X509_PURPOSE_get_count(void)
+{
+    if (!xptable)
+        return X509_PURPOSE_COUNT;
+    return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
+}
+
+X509_PURPOSE *X509_PURPOSE_get0(int idx)
+{
+    if (idx < 0)
+        return NULL;
+    if (idx < (int)X509_PURPOSE_COUNT)
+        return xstandard + idx;
+    return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
+}
+
+int X509_PURPOSE_get_by_sname(const char *sname)
+{
+    int i;
+    X509_PURPOSE *xptmp;
+    for (i = 0; i < X509_PURPOSE_get_count(); i++) {
+        xptmp = X509_PURPOSE_get0(i);
+        if (strcmp(xptmp->sname, sname) == 0)
+            return i;
+    }
+    return -1;
+}
+
+int X509_PURPOSE_get_by_id(int purpose)
+{
+    X509_PURPOSE tmp;
+    int idx;
+
+    if ((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
+        return purpose - X509_PURPOSE_MIN;
+    if (xptable == NULL)
+        return -1;
+    tmp.purpose = purpose;
+    idx = sk_X509_PURPOSE_find(xptable, &tmp);
+    if (idx < 0)
+        return -1;
+    return idx + X509_PURPOSE_COUNT;
+}
+
+int X509_PURPOSE_add(int id, int trust, int flags,
+                     int (*ck) (const X509_PURPOSE *, const X509 *, int),
+                     const char *name, const char *sname, void *arg)
+{
+    int idx;
+    X509_PURPOSE *ptmp;
+    /*
+     * This is set according to what we change: application can't set it
+     */
+    flags &= ~X509_PURPOSE_DYNAMIC;
+    /* This will always be set for application modified trust entries */
+    flags |= X509_PURPOSE_DYNAMIC_NAME;
+    /* Get existing entry if any */
+    idx = X509_PURPOSE_get_by_id(id);
+    /* Need a new entry */
+    if (idx == -1) {
+        if ((ptmp = OPENSSL_malloc(sizeof(*ptmp))) == NULL) {
+            X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
+            return 0;
+        }
+        ptmp->flags = X509_PURPOSE_DYNAMIC;
+    } else
+        ptmp = X509_PURPOSE_get0(idx);
+
+    /* OPENSSL_free existing name if dynamic */
+    if (ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
+        OPENSSL_free(ptmp->name);
+        OPENSSL_free(ptmp->sname);
+    }
+    /* dup supplied name */
+    ptmp->name = OPENSSL_strdup(name);
+    ptmp->sname = OPENSSL_strdup(sname);
+    if (!ptmp->name || !ptmp->sname) {
+        X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+    /* Keep the dynamic flag of existing entry */
+    ptmp->flags &= X509_PURPOSE_DYNAMIC;
+    /* Set all other flags */
+    ptmp->flags |= flags;
+
+    ptmp->purpose = id;
+    ptmp->trust = trust;
+    ptmp->check_purpose = ck;
+    ptmp->usr_data = arg;
+
+    /* If its a new entry manage the dynamic table */
+    if (idx == -1) {
+        if (xptable == NULL
+            && (xptable = sk_X509_PURPOSE_new(xp_cmp)) == NULL) {
+            X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
+            goto err;
+        }
+        if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
+            X509V3err(X509V3_F_X509_PURPOSE_ADD, ERR_R_MALLOC_FAILURE);
+            goto err;
+        }
+    }
+    return 1;
+ err:
+    if (idx == -1) {
+        OPENSSL_free(ptmp->name);
+        OPENSSL_free(ptmp->sname);
+        OPENSSL_free(ptmp);
+    }
+    return 0;
+}
+
+static void xptable_free(X509_PURPOSE *p)
+{
+    if (!p)
+        return;
+    if (p->flags & X509_PURPOSE_DYNAMIC) {
+        if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
+            OPENSSL_free(p->name);
+            OPENSSL_free(p->sname);
+        }
+        OPENSSL_free(p);
+    }
+}
+
+void X509_PURPOSE_cleanup(void)
+{
+    sk_X509_PURPOSE_pop_free(xptable, xptable_free);
+    xptable = NULL;
+}
+
+int X509_PURPOSE_get_id(const X509_PURPOSE *xp)
+{
+    return xp->purpose;
+}
+
+char *X509_PURPOSE_get0_name(const X509_PURPOSE *xp)
+{
+    return xp->name;
+}
+
+char *X509_PURPOSE_get0_sname(const X509_PURPOSE *xp)
+{
+    return xp->sname;
+}
+
+int X509_PURPOSE_get_trust(const X509_PURPOSE *xp)
+{
+    return xp->trust;
+}
+
+static int nid_cmp(const int *a, const int *b)
+{
+    return *a - *b;
+}
+
+DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
+IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
+
+int X509_supported_extension(X509_EXTENSION *ex)
+{
+    /*
+     * This table is a list of the NIDs of supported extensions: that is
+     * those which are used by the verify process. If an extension is
+     * critical and doesn't appear in this list then the verify process will
+     * normally reject the certificate. The list must be kept in numerical
+     * order because it will be searched using bsearch.
+     */
+
+    static const int supported_nids[] = {
+        NID_netscape_cert_type, /* 71 */
+        NID_key_usage,          /* 83 */
+        NID_subject_alt_name,   /* 85 */
+        NID_basic_constraints,  /* 87 */
+        NID_certificate_policies, /* 89 */
+        NID_crl_distribution_points, /* 103 */
+        NID_ext_key_usage,      /* 126 */
+#ifndef OPENSSL_NO_RFC3779
+        NID_sbgp_ipAddrBlock,   /* 290 */
+        NID_sbgp_autonomousSysNum, /* 291 */
+#endif
+        NID_policy_constraints, /* 401 */
+        NID_proxyCertInfo,      /* 663 */
+        NID_name_constraints,   /* 666 */
+        NID_policy_mappings,    /* 747 */
+        NID_inhibit_any_policy  /* 748 */
+    };
+
+    int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
+
+    if (ex_nid == NID_undef)
+        return 0;
+
+    if (OBJ_bsearch_nid(&ex_nid, supported_nids, OSSL_NELEM(supported_nids)))
+        return 1;
+    return 0;
+}
+
+static void setup_dp(X509 *x, DIST_POINT *dp)
+{
+    X509_NAME *iname = NULL;
+    int i;
+    if (dp->reasons) {
+        if (dp->reasons->length > 0)
+            dp->dp_reasons = dp->reasons->data[0];
+        if (dp->reasons->length > 1)
+            dp->dp_reasons |= (dp->reasons->data[1] << 8);
+        dp->dp_reasons &= CRLDP_ALL_REASONS;
+    } else
+        dp->dp_reasons = CRLDP_ALL_REASONS;
+    if (!dp->distpoint || (dp->distpoint->type != 1))
+        return;
+    for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++) {
+        GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
+        if (gen->type == GEN_DIRNAME) {
+            iname = gen->d.directoryName;
+            break;
+        }
+    }
+    if (!iname)
+        iname = X509_get_issuer_name(x);
+
+    DIST_POINT_set_dpname(dp->distpoint, iname);
+
+}
+
+static void setup_crldp(X509 *x)
+{
+    int i;
+    x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
+    for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
+        setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
+}
+
+#define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
+#define ku_reject(x, usage) \
+        (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
+#define xku_reject(x, usage) \
+        (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
+#define ns_reject(x, usage) \
+        (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
+
+static void x509v3_cache_extensions(X509 *x)
+{
+    BASIC_CONSTRAINTS *bs;
+    PROXY_CERT_INFO_EXTENSION *pci;
+    ASN1_BIT_STRING *usage;
+    ASN1_BIT_STRING *ns;
+    EXTENDED_KEY_USAGE *extusage;
+    X509_EXTENSION *ex;
+    int i;
+
+#ifdef tsan_ld_acq
+    /* fast lock-free check, see end of the function for details. */
+    if (tsan_ld_acq((TSAN_QUALIFIER int *)&x->ex_cached))
+        return;
+#endif
+
+    CRYPTO_THREAD_write_lock(x->lock);
+    if (x->ex_flags & EXFLAG_SET) {
+        CRYPTO_THREAD_unlock(x->lock);
+        return;
+    }
+
+    X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
+    /* V1 should mean no extensions ... */
+    if (!X509_get_version(x))
+        x->ex_flags |= EXFLAG_V1;
+    /* Handle basic constraints */
+    if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
+        if (bs->ca)
+            x->ex_flags |= EXFLAG_CA;
+        if (bs->pathlen) {
+            if ((bs->pathlen->type == V_ASN1_NEG_INTEGER)
+                || !bs->ca) {
+                x->ex_flags |= EXFLAG_INVALID;
+                x->ex_pathlen = 0;
+            } else
+                x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
+        } else
+            x->ex_pathlen = -1;
+        BASIC_CONSTRAINTS_free(bs);
+        x->ex_flags |= EXFLAG_BCONS;
+    }
+    /* Handle proxy certificates */
+    if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
+        if (x->ex_flags & EXFLAG_CA
+            || X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0
+            || X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) {
+            x->ex_flags |= EXFLAG_INVALID;
+        }
+        if (pci->pcPathLengthConstraint) {
+            x->ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
+        } else
+            x->ex_pcpathlen = -1;
+        PROXY_CERT_INFO_EXTENSION_free(pci);
+        x->ex_flags |= EXFLAG_PROXY;
+    }
+    /* Handle key usage */
+    if ((usage = X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
+        if (usage->length > 0) {
+            x->ex_kusage = usage->data[0];
+            if (usage->length > 1)
+                x->ex_kusage |= usage->data[1] << 8;
+        } else
+            x->ex_kusage = 0;
+        x->ex_flags |= EXFLAG_KUSAGE;
+        ASN1_BIT_STRING_free(usage);
+    }
+    x->ex_xkusage = 0;
+    if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
+        x->ex_flags |= EXFLAG_XKUSAGE;
+        for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
+            switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) {
+            case NID_server_auth:
+                x->ex_xkusage |= XKU_SSL_SERVER;
+                break;
+
+            case NID_client_auth:
+                x->ex_xkusage |= XKU_SSL_CLIENT;
+                break;
+
+            case NID_email_protect:
+                x->ex_xkusage |= XKU_SMIME;
+                break;
+
+            case NID_code_sign:
+                x->ex_xkusage |= XKU_CODE_SIGN;
+                break;
+
+            case NID_ms_sgc:
+            case NID_ns_sgc:
+                x->ex_xkusage |= XKU_SGC;
+                break;
+
+            case NID_OCSP_sign:
+                x->ex_xkusage |= XKU_OCSP_SIGN;
+                break;
+
+            case NID_time_stamp:
+                x->ex_xkusage |= XKU_TIMESTAMP;
+                break;
+
+            case NID_dvcs:
+                x->ex_xkusage |= XKU_DVCS;
+                break;
+
+            case NID_anyExtendedKeyUsage:
+                x->ex_xkusage |= XKU_ANYEKU;
+                break;
+            }
+        }
+        sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
+    }
+
+    if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
+        if (ns->length > 0)
+            x->ex_nscert = ns->data[0];
+        else
+            x->ex_nscert = 0;
+        x->ex_flags |= EXFLAG_NSCERT;
+        ASN1_BIT_STRING_free(ns);
+    }
+    x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
+    x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
+    /* Does subject name match issuer ? */
+    if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) {
+        x->ex_flags |= EXFLAG_SI;
+        /* If SKID matches AKID also indicate self signed */
+        if (X509_check_akid(x, x->akid) == X509_V_OK &&
+            !ku_reject(x, KU_KEY_CERT_SIGN))
+            x->ex_flags |= EXFLAG_SS;
+    }
+    x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
+    x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
+    if (!x->nc && (i != -1))
+        x->ex_flags |= EXFLAG_INVALID;
+    setup_crldp(x);
+
+#ifndef OPENSSL_NO_RFC3779
+    x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
+    x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
+                                       NULL, NULL);
+#endif
+    for (i = 0; i < X509_get_ext_count(x); i++) {
+        ex = X509_get_ext(x, i);
+        if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
+            == NID_freshest_crl)
+            x->ex_flags |= EXFLAG_FRESHEST;
+        if (!X509_EXTENSION_get_critical(ex))
+            continue;
+        if (!X509_supported_extension(ex)) {
+            x->ex_flags |= EXFLAG_CRITICAL;
+            break;
+        }
+    }
+    x509_init_sig_info(x);
+    x->ex_flags |= EXFLAG_SET;
+#ifdef tsan_st_rel
+    tsan_st_rel((TSAN_QUALIFIER int *)&x->ex_cached, 1);
+    /*
+     * Above store triggers fast lock-free check in the beginning of the
+     * function. But one has to ensure that the structure is "stable", i.e.
+     * all stores are visible on all processors. Hence the release fence.
+     */
+#endif
+    CRYPTO_THREAD_unlock(x->lock);
+}
+
+/*-
+ * CA checks common to all purposes
+ * return codes:
+ * 0 not a CA
+ * 1 is a CA
+ * 2 basicConstraints absent so "maybe" a CA
+ * 3 basicConstraints absent but self signed V1.
+ * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
+ */
+
+static int check_ca(const X509 *x)
+{
+    /* keyUsage if present should allow cert signing */
+    if (ku_reject(x, KU_KEY_CERT_SIGN))
+        return 0;
+    if (x->ex_flags & EXFLAG_BCONS) {
+        if (x->ex_flags & EXFLAG_CA)
+            return 1;
+        /* If basicConstraints says not a CA then say so */
+        else
+            return 0;
+    } else {
+        /* we support V1 roots for...  uh, I don't really know why. */
+        if ((x->ex_flags & V1_ROOT) == V1_ROOT)
+            return 3;
+        /*
+         * If key usage present it must have certSign so tolerate it
+         */
+        else if (x->ex_flags & EXFLAG_KUSAGE)
+            return 4;
+        /* Older certificates could have Netscape-specific CA types */
+        else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
+            return 5;
+        /* can this still be regarded a CA certificate?  I doubt it */
+        return 0;
+    }
+}
+
+void X509_set_proxy_flag(X509 *x)
+{
+    x->ex_flags |= EXFLAG_PROXY;
+}
+
+void X509_set_proxy_pathlen(X509 *x, long l)
+{
+    x->ex_pcpathlen = l;
+}
+
+int X509_check_ca(X509 *x)
+{
+    x509v3_cache_extensions(x);
+
+    return check_ca(x);
+}
+
+/* Check SSL CA: common checks for SSL client and server */
+static int check_ssl_ca(const X509 *x)
+{
+    int ca_ret;
+    ca_ret = check_ca(x);
+    if (!ca_ret)
+        return 0;
+    /* check nsCertType if present */
+    if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
+        return ca_ret;
+    else
+        return 0;
+}
+
+static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
+                                    int ca)
+{
+    if (xku_reject(x, XKU_SSL_CLIENT))
+        return 0;
+    if (ca)
+        return check_ssl_ca(x);
+    /* We need to do digital signatures or key agreement */
+    if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
+        return 0;
+    /* nsCertType if present should allow SSL client use */
+    if (ns_reject(x, NS_SSL_CLIENT))
+        return 0;
+    return 1;
+}
+
+/*
+ * Key usage needed for TLS/SSL server: digital signature, encipherment or
+ * key agreement. The ssl code can check this more thoroughly for individual
+ * key types.
+ */
+#define KU_TLS \
+        KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT|KU_KEY_AGREEMENT
+
+static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
+                                    int ca)
+{
+    if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
+        return 0;
+    if (ca)
+        return check_ssl_ca(x);
+
+    if (ns_reject(x, NS_SSL_SERVER))
+        return 0;
+    if (ku_reject(x, KU_TLS))
+        return 0;
+
+    return 1;
+
+}
+
+static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
+                                       int ca)
+{
+    int ret;
+    ret = check_purpose_ssl_server(xp, x, ca);
+    if (!ret || ca)
+        return ret;
+    /* We need to encipher or Netscape complains */
+    if (ku_reject(x, KU_KEY_ENCIPHERMENT))
+        return 0;
+    return ret;
+}
+
+/* common S/MIME checks */
+static int purpose_smime(const X509 *x, int ca)
+{
+    if (xku_reject(x, XKU_SMIME))
+        return 0;
+    if (ca) {
+        int ca_ret;
+        ca_ret = check_ca(x);
+        if (!ca_ret)
+            return 0;
+        /* check nsCertType if present */
+        if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
+            return ca_ret;
+        else
+            return 0;
+    }
+    if (x->ex_flags & EXFLAG_NSCERT) {
+        if (x->ex_nscert & NS_SMIME)
+            return 1;
+        /* Workaround for some buggy certificates */
+        if (x->ex_nscert & NS_SSL_CLIENT)
+            return 2;
+        return 0;
+    }
+    return 1;
+}
+
+static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
+                                    int ca)
+{
+    int ret;
+    ret = purpose_smime(x, ca);
+    if (!ret || ca)
+        return ret;
+    if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION))
+        return 0;
+    return ret;
+}
+
+static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
+                                       int ca)
+{
+    int ret;
+    ret = purpose_smime(x, ca);
+    if (!ret || ca)
+        return ret;
+    if (ku_reject(x, KU_KEY_ENCIPHERMENT))
+        return 0;
+    return ret;
+}
+
+static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
+                                  int ca)
+{
+    if (ca) {
+        int ca_ret;
+        if ((ca_ret = check_ca(x)) != 2)
+            return ca_ret;
+        else
+            return 0;
+    }
+    if (ku_reject(x, KU_CRL_SIGN))
+        return 0;
+    return 1;
+}
+
+/*
+ * OCSP helper: this is *not* a full OCSP check. It just checks that each CA
+ * is valid. Additional checks must be made on the chain.
+ */
+
+static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
+{
+    /*
+     * Must be a valid CA.  Should we really support the "I don't know" value
+     * (2)?
+     */
+    if (ca)
+        return check_ca(x);
+    /* leaf certificate is checked in OCSP_verify() */
+    return 1;
+}
+
+static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
+                                        int ca)
+{
+    int i_ext;
+
+    /* If ca is true we must return if this is a valid CA certificate. */
+    if (ca)
+        return check_ca(x);
+
+    /*
+     * Check the optional key usage field:
+     * if Key Usage is present, it must be one of digitalSignature
+     * and/or nonRepudiation (other values are not consistent and shall
+     * be rejected).
+     */
+    if ((x->ex_flags & EXFLAG_KUSAGE)
+        && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
+            !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
+        return 0;
+
+    /* Only time stamp key usage is permitted and it's required. */
+    if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
+        return 0;
+
+    /* Extended Key Usage MUST be critical */
+    i_ext = X509_get_ext_by_NID(x, NID_ext_key_usage, -1);
+    if (i_ext >= 0) {
+        X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
+        if (!X509_EXTENSION_get_critical(ext))
+            return 0;
+    }
+
+    return 1;
+}
+
+static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
+{
+    return 1;
+}
+
+/*-
+ * Various checks to see if one certificate issued the second.
+ * This can be used to prune a set of possible issuer certificates
+ * which have been looked up using some simple method such as by
+ * subject name.
+ * These are:
+ * 1. Check issuer_name(subject) == subject_name(issuer)
+ * 2. If akid(subject) exists, check that it matches issuer
+ * 3. Check that issuer public key algorithm matches subject signature algorithm
+ * 4. If key_usage(issuer) exists, check that it supports certificate signing
+ * returns 0 for OK, positive for reason for mismatch, reasons match
+ * codes for X509_verify_cert()
+ */
+
+int X509_check_issued(X509 *issuer, X509 *subject)
+{
+    if (X509_NAME_cmp(X509_get_subject_name(issuer),
+                      X509_get_issuer_name(subject)))
+        return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
+
+    x509v3_cache_extensions(issuer);
+    x509v3_cache_extensions(subject);
+
+    if (subject->akid) {
+        int ret = X509_check_akid(issuer, subject->akid);
+        if (ret != X509_V_OK)
+            return ret;
+    }
+
+    {
+        /*
+         * Check if the subject signature algorithm matches the issuer's PUBKEY
+         * algorithm
+         */
+        EVP_PKEY *i_pkey = X509_get0_pubkey(issuer);
+        X509_ALGOR *s_algor = &subject->cert_info.signature;
+        int s_pknid = NID_undef, s_mdnid = NID_undef;
+
+        if (i_pkey == NULL)
+            return X509_V_ERR_NO_ISSUER_PUBLIC_KEY;
+
+        if (!OBJ_find_sigid_algs(OBJ_obj2nid(s_algor->algorithm),
+                                 &s_mdnid, &s_pknid)
+            || EVP_PKEY_type(s_pknid) != EVP_PKEY_base_id(i_pkey))
+            return X509_V_ERR_SIGNATURE_ALGORITHM_MISMATCH;
+    }
+
+    if (subject->ex_flags & EXFLAG_PROXY) {
+        if (ku_reject(issuer, KU_DIGITAL_SIGNATURE))
+            return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
+    } else if (ku_reject(issuer, KU_KEY_CERT_SIGN))
+        return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
+    return X509_V_OK;
+}
+
+int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
+{
+
+    if (!akid)
+        return X509_V_OK;
+
+    /* Check key ids (if present) */
+    if (akid->keyid && issuer->skid &&
+        ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid))
+        return X509_V_ERR_AKID_SKID_MISMATCH;
+    /* Check serial number */
+    if (akid->serial &&
+        ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
+        return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
+    /* Check issuer name */
+    if (akid->issuer) {
+        /*
+         * Ugh, for some peculiar reason AKID includes SEQUENCE OF
+         * GeneralName. So look for a DirName. There may be more than one but
+         * we only take any notice of the first.
+         */
+        GENERAL_NAMES *gens;
+        GENERAL_NAME *gen;
+        X509_NAME *nm = NULL;
+        int i;
+        gens = akid->issuer;
+        for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
+            gen = sk_GENERAL_NAME_value(gens, i);
+            if (gen->type == GEN_DIRNAME) {
+                nm = gen->d.dirn;
+                break;
+            }
+        }
+        if (nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
+            return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
+    }
+    return X509_V_OK;
+}
+
+uint32_t X509_get_extension_flags(X509 *x)
+{
+    /* Call for side-effect of computing hash and caching extensions */
+    X509_check_purpose(x, -1, -1);
+    return x->ex_flags;
+}
+
+uint32_t X509_get_key_usage(X509 *x)
+{
+    /* Call for side-effect of computing hash and caching extensions */
+    X509_check_purpose(x, -1, -1);
+    if (x->ex_flags & EXFLAG_KUSAGE)
+        return x->ex_kusage;
+    return UINT32_MAX;
+}
+
+uint32_t X509_get_extended_key_usage(X509 *x)
+{
+    /* Call for side-effect of computing hash and caching extensions */
+    X509_check_purpose(x, -1, -1);
+    if (x->ex_flags & EXFLAG_XKUSAGE)
+        return x->ex_xkusage;
+    return UINT32_MAX;
+}
+
+const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x)
+{
+    /* Call for side-effect of computing hash and caching extensions */
+    X509_check_purpose(x, -1, -1);
+    return x->skid;
+}
+
+const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x)
+{
+    /* Call for side-effect of computing hash and caching extensions */
+    X509_check_purpose(x, -1, -1);
+    return (x->akid != NULL ? x->akid->keyid : NULL);
+}
+
+long X509_get_pathlen(X509 *x)
+{
+    /* Called for side effect of caching extensions */
+    if (X509_check_purpose(x, -1, -1) != 1
+            || (x->ex_flags & EXFLAG_BCONS) == 0)
+        return -1;
+    return x->ex_pathlen;
+}
+
+long X509_get_proxy_pathlen(X509 *x)
+{
+    /* Called for side effect of caching extensions */
+    if (X509_check_purpose(x, -1, -1) != 1
+            || (x->ex_flags & EXFLAG_PROXY) == 0)
+        return -1;
+    return x->ex_pcpathlen;
+}