/*

 * Copyright 1999-2020 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (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 "crypto/x509.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);

    if (x->ex_flags & EXFLAG_INVALID)

        return -1;

    /* 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 int 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 1;

    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);

    return DIST_POINT_set_dpname(dp->distpoint, iname);

}

static int setup_crldp(X509 *x)

{

    int i;

    x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL);

    if (x->crldp == NULL && i != -1)

        return 0;

    for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {

        if (!setup_dp(x, sk_DIST_POINT_value(x->crldp, i)))

            return 0;

    }

    return 1;

}

#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;

    }

    if (!X509_digest(x, EVP_sha1(), x->sha1_hash, NULL))

        x->ex_flags |= EXFLAG_INVALID;

    /* 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, &i, NULL))) {

        if (bs->ca)

            x->ex_flags |= EXFLAG_CA;

        if (bs->pathlen) {

            if (bs->pathlen->type == V_ASN1_NEG_INTEGER) {

                x->ex_flags |= EXFLAG_INVALID;

                x->ex_pathlen = 0;

            } else {

                x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);

                if (!bs->ca && x->ex_pathlen != 0) {

                    x->ex_flags |= EXFLAG_INVALID;

                    x->ex_pathlen = 0;

                }

            }

        } else

            x->ex_pathlen = -1;

        BASIC_CONSTRAINTS_free(bs);

        x->ex_flags |= EXFLAG_BCONS;

    } else if (i != -1) {

        x->ex_flags |= EXFLAG_INVALID;

    }

    /* Handle proxy certificates */

    if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &i, 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;

    } else if (i != -1) {

        x->ex_flags |= EXFLAG_INVALID;

    }

    /* Handle key usage */

    if ((usage = X509_get_ext_d2i(x, NID_key_usage, &i, 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);

    } else if (i != -1) {

        x->ex_flags |= EXFLAG_INVALID;

    }

    x->ex_xkusage = 0;

    if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &i, 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);

    } else if (i != -1) {

        x->ex_flags |= EXFLAG_INVALID;

    }

    if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &i, 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);

    } else if (i != -1) {

        x->ex_flags |= EXFLAG_INVALID;

    }

    x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &i, NULL);

    if (x->skid == NULL && i != -1)

        x->ex_flags |= EXFLAG_INVALID;

    x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &i, NULL);

    if (x->akid == NULL && i != -1)

        x->ex_flags |= EXFLAG_INVALID;

    /* 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, &i, NULL);

    if (x->altname == NULL && i != -1)

        x->ex_flags |= EXFLAG_INVALID;

    x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);

    if (x->nc == NULL && i != -1)

        x->ex_flags |= EXFLAG_INVALID;

    if (!setup_crldp(x))

        x->ex_flags |= EXFLAG_INVALID;

#ifndef OPENSSL_NO_RFC3779

    x->rfc3779_addr = X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, &i, NULL);

    if (x->rfc3779_addr == NULL && i != -1)

        x->ex_flags |= EXFLAG_INVALID;

    x->rfc3779_asid = X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum, &i, NULL);

    if (x->rfc3779_asid == NULL && i != -1)

        x->ex_flags |= EXFLAG_INVALID;

#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 Only possible in older versions of openSSL when basicConstraints are absent

 *   new versions will not return this value. May be a CA

 * 3 basicConstraints absent but self signed V1.

 * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.

 * 5 Netscape specific CA Flags present

 */

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 it matches issuer

 * 3. If key_usage(issuer) exists check 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);

    if (issuer->ex_flags & EXFLAG_INVALID)

        return X509_V_ERR_UNSPECIFIED;

    x509v3_cache_extensions(subject);

    if (subject->ex_flags & EXFLAG_INVALID)

        return X509_V_ERR_UNSPECIFIED;

    if (subject->akid) {

        int ret = X509_check_akid(issuer, subject->akid);

        if (ret != X509_V_OK)

            return ret;

    }

    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;

}