Commit message: Fix alternate chains certificate forgery issue

During certificate verfification, OpenSSL will attempt to find an
alternative certificate chain if the first attempt to build such a chain
fails. An error in the implementation of this logic can mean that an
attacker could cause certain checks on untrusted certificates to be
bypassed, such as the CA flag, enabling them to use a valid leaf
certificate to act as a CA and "issue" an invalid certificate.

This occurs where at least one cert is added to the first chain from the
trust store, but that chain still ends up being untrusted. In that case
ctx->last_untrusted is decremented in error.

Patch provided by the BoringSSL project.

CVE-2015-1793

Reviewed-by: Stephen Henson <steve@openssl.org>
CVE: CVE-2015-1793
CWE: CWE-254
Vulnerability description: The X509_verify_cert function in crypto/x509/x509_vfy.c in OpenSSL 1.0.1n, 1.0.1o, 1.0.2b, and 1.0.2c does not properly process X.509 Basic Constraints cA values during identification of alternative certificate chains, which allows remote attackers to spoof a Certification Authority role and trigger unintended certificate verifications via a valid leaf certificate.

Project: openssl

void X509_STORE_CTX_cleanup(X509_STORE_CTX *ctx)
{
    if (ctx->cleanup)
        ctx->cleanup(ctx);
    if (ctx->param != NULL) {
        if (ctx->parent == NULL)
            X509_VERIFY_PARAM_free(ctx->param);
        ctx->param = NULL;
    }
    if (ctx->tree != NULL) {
        X509_policy_tree_free(ctx->tree);
        ctx->tree = NULL;
    }
    if (ctx->chain != NULL) {
        sk_X509_pop_free(ctx->chain, X509_free);
        ctx->chain = NULL;
    }
    CRYPTO_free_ex_data(CRYPTO_EX_INDEX_X509_STORE_CTX, ctx, &(ctx->ex_data));
    memset(&ctx->ex_data, 0, sizeof(CRYPTO_EX_DATA));
}

Project: openssl

void X509_STORE_CTX_free(X509_STORE_CTX *ctx)
{
    if (!ctx)
        return;
    X509_STORE_CTX_cleanup(ctx);
    OPENSSL_free(ctx);
}

Project: openssl

X509_CRL *X509_STORE_CTX_get0_current_crl(X509_STORE_CTX *ctx)
{
    return ctx->current_crl;
}

Project: openssl

X509 *X509_STORE_CTX_get0_current_issuer(X509_STORE_CTX *ctx)
{
    return ctx->current_issuer;
}

Project: openssl

X509_VERIFY_PARAM *X509_STORE_CTX_get0_param(X509_STORE_CTX *ctx)
{
    return ctx->param;
}

Project: openssl

X509_STORE_CTX *X509_STORE_CTX_get0_parent_ctx(X509_STORE_CTX *ctx)
{
    return ctx->parent;
}

Project: openssl

STACK_OF(X509) *X509_STORE_CTX_get1_chain(X509_STORE_CTX *ctx)
{
    int i;
    X509 *x;
    STACK_OF(X509) *chain;
    if (!ctx->chain || !(chain = sk_X509_dup(ctx->chain)))
        return NULL;
    for (i = 0; i < sk_X509_num(chain); i++) {
        x = sk_X509_value(chain, i);
        CRYPTO_add(&x->references, 1, CRYPTO_LOCK_X509);
    }
    return chain;
}

Project: openssl

STACK_OF(X509) *X509_STORE_CTX_get_chain(X509_STORE_CTX *ctx)
{
    return ctx->chain;
}

Project: openssl

X509 *X509_STORE_CTX_get_current_cert(X509_STORE_CTX *ctx)
{
    return ctx->current_cert;
}

Project: openssl

int X509_STORE_CTX_get_error(X509_STORE_CTX *ctx)
{
    return ctx->error;
}

Project: openssl

int X509_STORE_CTX_get_error_depth(X509_STORE_CTX *ctx)
{
    return ctx->error_depth;
}

Project: openssl

void *X509_STORE_CTX_get_ex_data(X509_STORE_CTX *ctx, int idx)
{
    return CRYPTO_get_ex_data(&ctx->ex_data, idx);
}

Project: openssl

int X509_STORE_CTX_get_ex_new_index(long argl, void *argp,
                                    CRYPTO_EX_new *new_func,
                                    CRYPTO_EX_dup *dup_func,
                                    CRYPTO_EX_free *free_func)
{
    /*
     * This function is (usually) called only once, by
     * SSL_get_ex_data_X509_STORE_CTX_idx (ssl/ssl_cert.c).
     */
    return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_X509_STORE_CTX, argl, argp,
                                   new_func, dup_func, free_func);
}

Project: openssl

int X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *store, X509 *x509,
                        STACK_OF(X509) *chain)
{
    int ret = 1;
    ctx->ctx = store;
    ctx->current_method = 0;
    ctx->cert = x509;
    ctx->untrusted = chain;
    ctx->crls = NULL;
    ctx->last_untrusted = 0;
    ctx->other_ctx = NULL;
    ctx->valid = 0;
    ctx->chain = NULL;
    ctx->error = 0;
    ctx->explicit_policy = 0;
    ctx->error_depth = 0;
    ctx->current_cert = NULL;
    ctx->current_issuer = NULL;
    ctx->current_crl = NULL;
    ctx->current_crl_score = 0;
    ctx->current_reasons = 0;
    ctx->tree = NULL;
    ctx->parent = NULL;

    ctx->param = X509_VERIFY_PARAM_new();

    if (!ctx->param) {
        X509err(X509_F_X509_STORE_CTX_INIT, ERR_R_MALLOC_FAILURE);
        return 0;
    }

    /*
     * Inherit callbacks and flags from X509_STORE if not set use defaults.
     */

    if (store)
        ret = X509_VERIFY_PARAM_inherit(ctx->param, store->param);
    else
        ctx->param->inh_flags |= X509_VP_FLAG_DEFAULT | X509_VP_FLAG_ONCE;

    if (store) {
        ctx->verify_cb = store->verify_cb;
        ctx->cleanup = store->cleanup;
    } else
        ctx->cleanup = 0;

    if (ret)
        ret = X509_VERIFY_PARAM_inherit(ctx->param,
                                        X509_VERIFY_PARAM_lookup("default"));

    if (ret == 0) {
        X509err(X509_F_X509_STORE_CTX_INIT, ERR_R_MALLOC_FAILURE);
        return 0;
    }

    if (store && store->check_issued)
        ctx->check_issued = store->check_issued;
    else
        ctx->check_issued = check_issued;

    if (store && store->get_issuer)
        ctx->get_issuer = store->get_issuer;
    else
        ctx->get_issuer = X509_STORE_CTX_get1_issuer;

    if (store && store->verify_cb)
        ctx->verify_cb = store->verify_cb;
    else
        ctx->verify_cb = null_callback;

    if (store && store->verify)
        ctx->verify = store->verify;
    else
        ctx->verify = internal_verify;

    if (store && store->check_revocation)
        ctx->check_revocation = store->check_revocation;
    else
        ctx->check_revocation = check_revocation;

    if (store && store->get_crl)
        ctx->get_crl = store->get_crl;
    else
        ctx->get_crl = NULL;

    if (store && store->check_crl)
        ctx->check_crl = store->check_crl;
    else
        ctx->check_crl = check_crl;

    if (store && store->cert_crl)
        ctx->cert_crl = store->cert_crl;
    else
        ctx->cert_crl = cert_crl;

    if (store && store->lookup_certs)
        ctx->lookup_certs = store->lookup_certs;
    else
        ctx->lookup_certs = X509_STORE_get1_certs;

    if (store && store->lookup_crls)
        ctx->lookup_crls = store->lookup_crls;
    else
        ctx->lookup_crls = X509_STORE_get1_crls;

    ctx->check_policy = check_policy;

    /*
     * This memset() can't make any sense anyway, so it's removed. As
     * X509_STORE_CTX_cleanup does a proper "free" on the ex_data, we put a
     * corresponding "new" here and remove this bogus initialisation.
     */
    /* memset(&(ctx->ex_data),0,sizeof(CRYPTO_EX_DATA)); */
    if (!CRYPTO_new_ex_data(CRYPTO_EX_INDEX_X509_STORE_CTX, ctx,
                            &(ctx->ex_data))) {
        OPENSSL_free(ctx);
        X509err(X509_F_X509_STORE_CTX_INIT, ERR_R_MALLOC_FAILURE);
        return 0;
    }
    return 1;
}

Project: openssl

X509_STORE_CTX *X509_STORE_CTX_new(void)
{
    X509_STORE_CTX *ctx;
    ctx = (X509_STORE_CTX *)OPENSSL_malloc(sizeof(X509_STORE_CTX));
    if (!ctx) {
        X509err(X509_F_X509_STORE_CTX_NEW, ERR_R_MALLOC_FAILURE);
        return NULL;
    }
    memset(ctx, 0, sizeof(X509_STORE_CTX));
    return ctx;
}

Project: openssl

int X509_STORE_CTX_purpose_inherit(X509_STORE_CTX *ctx, int def_purpose,
                                   int purpose, int trust)
{
    int idx;
    /* If purpose not set use default */
    if (!purpose)
        purpose = def_purpose;
    /* If we have a purpose then check it is valid */
    if (purpose) {
        X509_PURPOSE *ptmp;
        idx = X509_PURPOSE_get_by_id(purpose);
        if (idx == -1) {
            X509err(X509_F_X509_STORE_CTX_PURPOSE_INHERIT,
                    X509_R_UNKNOWN_PURPOSE_ID);
            return 0;
        }
        ptmp = X509_PURPOSE_get0(idx);
        if (ptmp->trust == X509_TRUST_DEFAULT) {
            idx = X509_PURPOSE_get_by_id(def_purpose);
            if (idx == -1) {
                X509err(X509_F_X509_STORE_CTX_PURPOSE_INHERIT,
                        X509_R_UNKNOWN_PURPOSE_ID);
                return 0;
            }
            ptmp = X509_PURPOSE_get0(idx);
        }
        /* If trust not set then get from purpose default */
        if (!trust)
            trust = ptmp->trust;
    }
    if (trust) {
        idx = X509_TRUST_get_by_id(trust);
        if (idx == -1) {
            X509err(X509_F_X509_STORE_CTX_PURPOSE_INHERIT,
                    X509_R_UNKNOWN_TRUST_ID);
            return 0;
        }
    }

    if (purpose && !ctx->param->purpose)
        ctx->param->purpose = purpose;
    if (trust && !ctx->param->trust)
        ctx->param->trust = trust;
    return 1;
}

Project: openssl

void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param)
{
    if (ctx->param)
        X509_VERIFY_PARAM_free(ctx->param);
    ctx->param = param;
}

Project: openssl

void X509_STORE_CTX_set_cert(X509_STORE_CTX *ctx, X509 *x)
{
    ctx->cert = x;
}

Project: openssl

void X509_STORE_CTX_set_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
    ctx->untrusted = sk;
}

Project: openssl

int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name)
{
    const X509_VERIFY_PARAM *param;
    param = X509_VERIFY_PARAM_lookup(name);
    if (!param)
        return 0;
    return X509_VERIFY_PARAM_inherit(ctx->param, param);
}

Project: openssl

void X509_STORE_CTX_set_error(X509_STORE_CTX *ctx, int err)
{
    ctx->error = err;
}

Project: openssl

int X509_STORE_CTX_set_ex_data(X509_STORE_CTX *ctx, int idx, void *data)
{
    return CRYPTO_set_ex_data(&ctx->ex_data, idx, data);
}

Project: openssl

void X509_STORE_CTX_set_flags(X509_STORE_CTX *ctx, unsigned long flags)
{
    X509_VERIFY_PARAM_set_flags(ctx->param, flags);
}

Project: openssl

int X509_STORE_CTX_set_purpose(X509_STORE_CTX *ctx, int purpose)
{
    return X509_STORE_CTX_purpose_inherit(ctx, 0, purpose, 0);
}

Project: openssl

void X509_STORE_CTX_set_time(X509_STORE_CTX *ctx, unsigned long flags,
                             time_t t)
{
    X509_VERIFY_PARAM_set_time(ctx->param, t);
}

Project: openssl

int X509_STORE_CTX_set_trust(X509_STORE_CTX *ctx, int trust)
{
    return X509_STORE_CTX_purpose_inherit(ctx, 0, 0, trust);
}

Project: openssl

void X509_STORE_CTX_set_verify_cb(X509_STORE_CTX *ctx,
                                  int (*verify_cb) (int, X509_STORE_CTX *))
{
    ctx->verify_cb = verify_cb;
}

Project: openssl

void X509_STORE_CTX_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *sk)
{
    ctx->other_ctx = sk;
    ctx->get_issuer = get_issuer_sk;
}

Project: openssl

int X509_cmp_current_time(const ASN1_TIME *ctm)
{
    return X509_cmp_time(ctm, NULL);
}

Project: openssl

int X509_cmp_time(const ASN1_TIME *ctm, time_t *cmp_time)
{
    char *str;
    ASN1_TIME atm;
    long offset;
    char buff1[24], buff2[24], *p;
    int i, j, remaining;

    p = buff1;
    remaining = ctm->length;
    str = (char *)ctm->data;
    /*
     * Note that the following (historical) code allows much more slack in the
     * time format than RFC5280. In RFC5280, the representation is fixed:
     * UTCTime: YYMMDDHHMMSSZ
     * GeneralizedTime: YYYYMMDDHHMMSSZ
     */
    if (ctm->type == V_ASN1_UTCTIME) {
        /* YYMMDDHHMM[SS]Z or YYMMDDHHMM[SS](+-)hhmm */
        int min_length = sizeof("YYMMDDHHMMZ") - 1;
        int max_length = sizeof("YYMMDDHHMMSS+hhmm") - 1;
        if (remaining < min_length || remaining > max_length)
            return 0;
        memcpy(p, str, 10);
        p += 10;
        str += 10;
        remaining -= 10;
    } else {
        /* YYYYMMDDHHMM[SS[.fff]]Z or YYYYMMDDHHMM[SS[.f[f[f]]]](+-)hhmm */
        int min_length = sizeof("YYYYMMDDHHMMZ") - 1;
        int max_length = sizeof("YYYYMMDDHHMMSS.fff+hhmm") - 1;
        if (remaining < min_length || remaining > max_length)
            return 0;
        memcpy(p, str, 12);
        p += 12;
        str += 12;
        remaining -= 12;
    }

    if ((*str == 'Z') || (*str == '-') || (*str == '+')) {
        *(p++) = '0';
        *(p++) = '0';
    } else {
        /* SS (seconds) */
        if (remaining < 2)
            return 0;
        *(p++) = *(str++);
        *(p++) = *(str++);
        remaining -= 2;
        /*
         * Skip any (up to three) fractional seconds...
         * TODO(emilia): in RFC5280, fractional seconds are forbidden.
         * Can we just kill them altogether?
         */
        if (remaining && *str == '.') {
            str++;
            remaining--;
            for (i = 0; i < 3 && remaining; i++, str++, remaining--) {
                if (*str < '0' || *str > '9')
                    break;
            }
        }

    }
    *(p++) = 'Z';
    *(p++) = '\0';

    /* We now need either a terminating 'Z' or an offset. */
    if (!remaining)
        return 0;
    if (*str == 'Z') {
        if (remaining != 1)
            return 0;
        offset = 0;
    } else {
        /* (+-)HHMM */
        if ((*str != '+') && (*str != '-'))
            return 0;
        /* Historical behaviour: the (+-)hhmm offset is forbidden in RFC5280. */
        if (remaining != 5)
            return 0;
        if (str[1] < '0' || str[1] > '9' || str[2] < '0' || str[2] > '9' ||
            str[3] < '0' || str[3] > '9' || str[4] < '0' || str[4] > '9')
            return 0;
        offset = ((str[1] - '0') * 10 + (str[2] - '0')) * 60;
        offset += (str[3] - '0') * 10 + (str[4] - '0');
        if (*str == '-')
            offset = -offset;
    }
    atm.type = ctm->type;
    atm.flags = 0;
    atm.length = sizeof(buff2);
    atm.data = (unsigned char *)buff2;

    if (X509_time_adj(&atm, offset * 60, cmp_time) == NULL)
        return 0;

    if (ctm->type == V_ASN1_UTCTIME) {
        i = (buff1[0] - '0') * 10 + (buff1[1] - '0');
        if (i < 50)
            i += 100;           /* cf. RFC 2459 */
        j = (buff2[0] - '0') * 10 + (buff2[1] - '0');
        if (j < 50)
            j += 100;

        if (i < j)
            return -1;
        if (i > j)
            return 1;
    }
    i = strcmp(buff1, buff2);
    if (i == 0)                 /* wait a second then return younger :-) */
        return -1;
    else
        return i;
}

Project: openssl

int X509_get_pubkey_parameters(EVP_PKEY *pkey, STACK_OF(X509) *chain)
{
    EVP_PKEY *ktmp = NULL, *ktmp2;
    int i, j;

    if ((pkey != NULL) && !EVP_PKEY_missing_parameters(pkey))
        return 1;

    for (i = 0; i < sk_X509_num(chain); i++) {
        ktmp = X509_get_pubkey(sk_X509_value(chain, i));
        if (ktmp == NULL) {
            X509err(X509_F_X509_GET_PUBKEY_PARAMETERS,
                    X509_R_UNABLE_TO_GET_CERTS_PUBLIC_KEY);
            return 0;
        }
        if (!EVP_PKEY_missing_parameters(ktmp))
            break;
        else {
            EVP_PKEY_free(ktmp);
            ktmp = NULL;
        }
    }
    if (ktmp == NULL) {
        X509err(X509_F_X509_GET_PUBKEY_PARAMETERS,
                X509_R_UNABLE_TO_FIND_PARAMETERS_IN_CHAIN);
        return 0;
    }

    /* first, populate the other certs */
    for (j = i - 1; j >= 0; j--) {
        ktmp2 = X509_get_pubkey(sk_X509_value(chain, j));
        EVP_PKEY_copy_parameters(ktmp2, ktmp);
        EVP_PKEY_free(ktmp2);
    }

    if (pkey != NULL)
        EVP_PKEY_copy_parameters(pkey, ktmp);
    EVP_PKEY_free(ktmp);
    return 1;
}

Project: openssl

ASN1_TIME *X509_gmtime_adj(ASN1_TIME *s, long adj)
{
    return X509_time_adj(s, adj, NULL);
}

Project: openssl

ASN1_TIME *X509_time_adj(ASN1_TIME *s, long offset_sec, time_t *in_tm)
{
    return X509_time_adj_ex(s, 0, offset_sec, in_tm);
}

Project: openssl

ASN1_TIME *X509_time_adj_ex(ASN1_TIME *s,
                            int offset_day, long offset_sec, time_t *in_tm)
{
    time_t t;

    if (in_tm)
        t = *in_tm;
    else
        time(&t);

    if (s && !(s->flags & ASN1_STRING_FLAG_MSTRING)) {
        if (s->type == V_ASN1_UTCTIME)
            return ASN1_UTCTIME_adj(s, t, offset_day, offset_sec);
        if (s->type == V_ASN1_GENERALIZEDTIME)
            return ASN1_GENERALIZEDTIME_adj(s, t, offset_day, offset_sec);
    }
    return ASN1_TIME_adj(s, t, offset_day, offset_sec);
}

Project: openssl

static int cert_crl(X509_STORE_CTX *ctx, X509_CRL *crl, X509 *x)
{
    int ok;
    X509_REVOKED *rev;
    /*
     * The rules changed for this... previously if a CRL contained unhandled
     * critical extensions it could still be used to indicate a certificate
     * was revoked. This has since been changed since critical extension can
     * change the meaning of CRL entries.
     */
    if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL)
        && (crl->flags & EXFLAG_CRITICAL)) {
        ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION;
        ok = ctx->verify_cb(0, ctx);
        if (!ok)
            return 0;
    }
    /*
     * Look for serial number of certificate in CRL If found make sure reason
     * is not removeFromCRL.
     */
    if (X509_CRL_get0_by_cert(crl, &rev, x)) {
        if (rev->reason == CRL_REASON_REMOVE_FROM_CRL)
            return 2;
        ctx->error = X509_V_ERR_CERT_REVOKED;
        ok = ctx->verify_cb(0, ctx);
        if (!ok)
            return 0;
    }

    return 1;
}

Project: openssl

static int check_cert(X509_STORE_CTX *ctx)
{
    X509_CRL *crl = NULL, *dcrl = NULL;
    X509 *x;
    int ok, cnum;
    unsigned int last_reasons;
    cnum = ctx->error_depth;
    x = sk_X509_value(ctx->chain, cnum);
    ctx->current_cert = x;
    ctx->current_issuer = NULL;
    ctx->current_crl_score = 0;
    ctx->current_reasons = 0;
    while (ctx->current_reasons != CRLDP_ALL_REASONS) {
        last_reasons = ctx->current_reasons;
        /* Try to retrieve relevant CRL */
        if (ctx->get_crl)
            ok = ctx->get_crl(ctx, &crl, x);
        else
            ok = get_crl_delta(ctx, &crl, &dcrl, x);
        /*
         * If error looking up CRL, nothing we can do except notify callback
         */
        if (!ok) {
            ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
            ok = ctx->verify_cb(0, ctx);
            goto err;
        }
        ctx->current_crl = crl;
        ok = ctx->check_crl(ctx, crl);
        if (!ok)
            goto err;

        if (dcrl) {
            ok = ctx->check_crl(ctx, dcrl);
            if (!ok)
                goto err;
            ok = ctx->cert_crl(ctx, dcrl, x);
            if (!ok)
                goto err;
        } else
            ok = 1;

        /* Don't look in full CRL if delta reason is removefromCRL */
        if (ok != 2) {
            ok = ctx->cert_crl(ctx, crl, x);
            if (!ok)
                goto err;
        }

        X509_CRL_free(crl);
        X509_CRL_free(dcrl);
        crl = NULL;
        dcrl = NULL;
        /*
         * If reasons not updated we wont get anywhere by another iteration,
         * so exit loop.
         */
        if (last_reasons == ctx->current_reasons) {
            ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL;
            ok = ctx->verify_cb(0, ctx);
            goto err;
        }
    }
 err:
    X509_CRL_free(crl);
    X509_CRL_free(dcrl);

    ctx->current_crl = NULL;
    return ok;

}

Project: openssl

static int check_cert_time(X509_STORE_CTX *ctx, X509 *x)
{
    time_t *ptime;
    int i;

    if (ctx->param->flags & X509_V_FLAG_USE_CHECK_TIME)
        ptime = &ctx->param->check_time;
    else
        ptime = NULL;

    i = X509_cmp_time(X509_get_notBefore(x), ptime);
    if (i == 0) {
        ctx->error = X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD;
        ctx->current_cert = x;
        if (!ctx->verify_cb(0, ctx))
            return 0;
    }

    if (i > 0) {
        ctx->error = X509_V_ERR_CERT_NOT_YET_VALID;
        ctx->current_cert = x;
        if (!ctx->verify_cb(0, ctx))
            return 0;
    }

    i = X509_cmp_time(X509_get_notAfter(x), ptime);
    if (i == 0) {
        ctx->error = X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD;
        ctx->current_cert = x;
        if (!ctx->verify_cb(0, ctx))
            return 0;
    }

    if (i < 0) {
        ctx->error = X509_V_ERR_CERT_HAS_EXPIRED;
        ctx->current_cert = x;
        if (!ctx->verify_cb(0, ctx))
            return 0;
    }

    return 1;
}

Project: openssl

static int check_chain_extensions(X509_STORE_CTX *ctx)
{
#ifdef OPENSSL_NO_CHAIN_VERIFY
    return 1;
#else
    int i, ok = 0, must_be_ca, plen = 0;
    X509 *x;
    int (*cb) (int xok, X509_STORE_CTX *xctx);
    int proxy_path_length = 0;
    int purpose;
    int allow_proxy_certs;
    cb = ctx->verify_cb;

    /*-
     *  must_be_ca can have 1 of 3 values:
     * -1: we accept both CA and non-CA certificates, to allow direct
     *     use of self-signed certificates (which are marked as CA).
     * 0:  we only accept non-CA certificates.  This is currently not
     *     used, but the possibility is present for future extensions.
     * 1:  we only accept CA certificates.  This is currently used for
     *     all certificates in the chain except the leaf certificate.
     */
    must_be_ca = -1;

    /* CRL path validation */
    if (ctx->parent) {
        allow_proxy_certs = 0;
        purpose = X509_PURPOSE_CRL_SIGN;
    } else {
        allow_proxy_certs =
            ! !(ctx->param->flags & X509_V_FLAG_ALLOW_PROXY_CERTS);
        /*
         * A hack to keep people who don't want to modify their software
         * happy
         */
        if (getenv("OPENSSL_ALLOW_PROXY_CERTS"))
            allow_proxy_certs = 1;
        purpose = ctx->param->purpose;
    }

    /* Check all untrusted certificates */
    for (i = 0; i < ctx->last_untrusted; i++) {
        int ret;
        x = sk_X509_value(ctx->chain, i);
        if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL)
            && (x->ex_flags & EXFLAG_CRITICAL)) {
            ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION;
            ctx->error_depth = i;
            ctx->current_cert = x;
            ok = cb(0, ctx);
            if (!ok)
                goto end;
        }
        if (!allow_proxy_certs && (x->ex_flags & EXFLAG_PROXY)) {
            ctx->error = X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED;
            ctx->error_depth = i;
            ctx->current_cert = x;
            ok = cb(0, ctx);
            if (!ok)
                goto end;
        }
        ret = X509_check_ca(x);
        switch (must_be_ca) {
        case -1:
            if ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
                && (ret != 1) && (ret != 0)) {
                ret = 0;
                ctx->error = X509_V_ERR_INVALID_CA;
            } else
                ret = 1;
            break;
        case 0:
            if (ret != 0) {
                ret = 0;
                ctx->error = X509_V_ERR_INVALID_NON_CA;
            } else
                ret = 1;
            break;
        default:
            if ((ret == 0)
                || ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
                    && (ret != 1))) {
                ret = 0;
                ctx->error = X509_V_ERR_INVALID_CA;
            } else
                ret = 1;
            break;
        }
        if (ret == 0) {
            ctx->error_depth = i;
            ctx->current_cert = x;
            ok = cb(0, ctx);
            if (!ok)
                goto end;
        }
        if (ctx->param->purpose > 0) {
            ret = X509_check_purpose(x, purpose, must_be_ca > 0);
            if ((ret == 0)
                || ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
                    && (ret != 1))) {
                ctx->error = X509_V_ERR_INVALID_PURPOSE;
                ctx->error_depth = i;
                ctx->current_cert = x;
                ok = cb(0, ctx);
                if (!ok)
                    goto end;
            }
        }
        /* Check pathlen if not self issued */
        if ((i > 1) && !(x->ex_flags & EXFLAG_SI)
            && (x->ex_pathlen != -1)
            && (plen > (x->ex_pathlen + proxy_path_length + 1))) {
            ctx->error = X509_V_ERR_PATH_LENGTH_EXCEEDED;
            ctx->error_depth = i;
            ctx->current_cert = x;
            ok = cb(0, ctx);
            if (!ok)
                goto end;
        }
        /* Increment path length if not self issued */
        if (!(x->ex_flags & EXFLAG_SI))
            plen++;
        /*
         * If this certificate is a proxy certificate, the next certificate
         * must be another proxy certificate or a EE certificate.  If not,
         * the next certificate must be a CA certificate.
         */
        if (x->ex_flags & EXFLAG_PROXY) {
            if (x->ex_pcpathlen != -1 && i > x->ex_pcpathlen) {
                ctx->error = X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED;
                ctx->error_depth = i;
                ctx->current_cert = x;
                ok = cb(0, ctx);
                if (!ok)
                    goto end;
            }
            proxy_path_length++;
            must_be_ca = 0;
        } else
            must_be_ca = 1;
    }
    ok = 1;
 end:
    return ok;
#endif
}

Project: openssl

static int check_crl(X509_STORE_CTX *ctx, X509_CRL *crl)
{
    X509 *issuer = NULL;
    EVP_PKEY *ikey = NULL;
    int ok = 0, chnum, cnum;
    cnum = ctx->error_depth;
    chnum = sk_X509_num(ctx->chain) - 1;
    /* if we have an alternative CRL issuer cert use that */
    if (ctx->current_issuer)
        issuer = ctx->current_issuer;

    /*
     * Else find CRL issuer: if not last certificate then issuer is next
     * certificate in chain.
     */
    else if (cnum < chnum)
        issuer = sk_X509_value(ctx->chain, cnum + 1);
    else {
        issuer = sk_X509_value(ctx->chain, chnum);
        /* If not self signed, can't check signature */
        if (!ctx->check_issued(ctx, issuer, issuer)) {
            ctx->error = X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER;
            ok = ctx->verify_cb(0, ctx);
            if (!ok)
                goto err;
        }
    }

    if (issuer) {
        /*
         * Skip most tests for deltas because they have already been done
         */
        if (!crl->base_crl_number) {
            /* Check for cRLSign bit if keyUsage present */
            if ((issuer->ex_flags & EXFLAG_KUSAGE) &&
                !(issuer->ex_kusage & KU_CRL_SIGN)) {
                ctx->error = X509_V_ERR_KEYUSAGE_NO_CRL_SIGN;
                ok = ctx->verify_cb(0, ctx);
                if (!ok)
                    goto err;
            }

            if (!(ctx->current_crl_score & CRL_SCORE_SCOPE)) {
                ctx->error = X509_V_ERR_DIFFERENT_CRL_SCOPE;
                ok = ctx->verify_cb(0, ctx);
                if (!ok)
                    goto err;
            }

            if (!(ctx->current_crl_score & CRL_SCORE_SAME_PATH)) {
                if (check_crl_path(ctx, ctx->current_issuer) <= 0) {
                    ctx->error = X509_V_ERR_CRL_PATH_VALIDATION_ERROR;
                    ok = ctx->verify_cb(0, ctx);
                    if (!ok)
                        goto err;
                }
            }

            if (crl->idp_flags & IDP_INVALID) {
                ctx->error = X509_V_ERR_INVALID_EXTENSION;
                ok = ctx->verify_cb(0, ctx);
                if (!ok)
                    goto err;
            }

        }

        if (!(ctx->current_crl_score & CRL_SCORE_TIME)) {
            ok = check_crl_time(ctx, crl, 1);
            if (!ok)
                goto err;
        }

        /* Attempt to get issuer certificate public key */
        ikey = X509_get_pubkey(issuer);

        if (!ikey) {
            ctx->error = X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY;
            ok = ctx->verify_cb(0, ctx);
            if (!ok)
                goto err;
        } else {
            /* Verify CRL signature */
            if (X509_CRL_verify(crl, ikey) <= 0) {
                ctx->error = X509_V_ERR_CRL_SIGNATURE_FAILURE;
                ok = ctx->verify_cb(0, ctx);
                if (!ok)
                    goto err;
            }
        }
    }

    ok = 1;

 err:
    EVP_PKEY_free(ikey);
    return ok;
}

Project: openssl

static int check_crl_chain(X509_STORE_CTX *ctx,
                           STACK_OF(X509) *cert_path,
                           STACK_OF(X509) *crl_path)
{
    X509 *cert_ta, *crl_ta;
    cert_ta = sk_X509_value(cert_path, sk_X509_num(cert_path) - 1);
    crl_ta = sk_X509_value(crl_path, sk_X509_num(crl_path) - 1);
    if (!X509_cmp(cert_ta, crl_ta))
        return 1;
    return 0;
}

Project: openssl

static int check_delta_base(X509_CRL *delta, X509_CRL *base)
{
    /* Delta CRL must be a delta */
    if (!delta->base_crl_number)
        return 0;
    /* Base must have a CRL number */
    if (!base->crl_number)
        return 0;
    /* Issuer names must match */
    if (X509_NAME_cmp(X509_CRL_get_issuer(base), X509_CRL_get_issuer(delta)))
        return 0;
    /* AKID and IDP must match */
    if (!crl_extension_match(delta, base, NID_authority_key_identifier))
        return 0;
    if (!crl_extension_match(delta, base, NID_issuing_distribution_point))
        return 0;
    /* Delta CRL base number must not exceed Full CRL number. */
    if (ASN1_INTEGER_cmp(delta->base_crl_number, base->crl_number) > 0)
        return 0;
    /* Delta CRL number must exceed full CRL number */
    if (ASN1_INTEGER_cmp(delta->crl_number, base->crl_number) > 0)
        return 1;
    return 0;
}

Project: openssl

static int check_issued(X509_STORE_CTX *ctx, X509 *x, X509 *issuer)
{
    int ret;
    ret = X509_check_issued(issuer, x);
    if (ret == X509_V_OK)
        return 1;
    /* If we haven't asked for issuer errors don't set ctx */
    if (!(ctx->param->flags & X509_V_FLAG_CB_ISSUER_CHECK))
        return 0;

    ctx->error = ret;
    ctx->current_cert = x;
    ctx->current_issuer = issuer;
    return ctx->verify_cb(0, ctx);
    return 0;
}

Project: openssl

static int check_name_constraints(X509_STORE_CTX *ctx)
{
    X509 *x;
    int i, j, rv;
    /* Check name constraints for all certificates */
    for (i = sk_X509_num(ctx->chain) - 1; i >= 0; i--) {
        x = sk_X509_value(ctx->chain, i);
        /* Ignore self issued certs unless last in chain */
        if (i && (x->ex_flags & EXFLAG_SI))
            continue;
        /*
         * Check against constraints for all certificates higher in chain
         * including trust anchor. Trust anchor not strictly speaking needed
         * but if it includes constraints it is to be assumed it expects them
         * to be obeyed.
         */
        for (j = sk_X509_num(ctx->chain) - 1; j > i; j--) {
            NAME_CONSTRAINTS *nc = sk_X509_value(ctx->chain, j)->nc;
            if (nc) {
                rv = NAME_CONSTRAINTS_check(x, nc);
                if (rv != X509_V_OK) {
                    ctx->error = rv;
                    ctx->error_depth = i;
                    ctx->current_cert = x;
                    if (!ctx->verify_cb(0, ctx))
                        return 0;
                }
            }
        }
    }
    return 1;
}

Project: openssl

static int check_policy(X509_STORE_CTX *ctx)
{
    int ret;
    if (ctx->parent)
        return 1;
    ret = X509_policy_check(&ctx->tree, &ctx->explicit_policy, ctx->chain,
                            ctx->param->policies, ctx->param->flags);
    if (ret == 0) {
        X509err(X509_F_CHECK_POLICY, ERR_R_MALLOC_FAILURE);
        return 0;
    }
    /* Invalid or inconsistent extensions */
    if (ret == -1) {
        /*
         * Locate certificates with bad extensions and notify callback.
         */
        X509 *x;
        int i;
        for (i = 1; i < sk_X509_num(ctx->chain); i++) {
            x = sk_X509_value(ctx->chain, i);
            if (!(x->ex_flags & EXFLAG_INVALID_POLICY))
                continue;
            ctx->current_cert = x;
            ctx->error = X509_V_ERR_INVALID_POLICY_EXTENSION;
            if (!ctx->verify_cb(0, ctx))
                return 0;
        }
        return 1;
    }
    if (ret == -2) {
        ctx->current_cert = NULL;
        ctx->error = X509_V_ERR_NO_EXPLICIT_POLICY;
        return ctx->verify_cb(0, ctx);
    }

    if (ctx->param->flags & X509_V_FLAG_NOTIFY_POLICY) {
        ctx->current_cert = NULL;
        ctx->error = X509_V_OK;
        if (!ctx->verify_cb(2, ctx))
            return 0;
    }

    return 1;
}

Project: openssl

static int check_revocation(X509_STORE_CTX *ctx)
{
    int i, last, ok;
    if (!(ctx->param->flags & X509_V_FLAG_CRL_CHECK))
        return 1;
    if (ctx->param->flags & X509_V_FLAG_CRL_CHECK_ALL)
        last = sk_X509_num(ctx->chain) - 1;
    else {
        /* If checking CRL paths this isn't the EE certificate */
        if (ctx->parent)
            return 1;
        last = 0;
    }
    for (i = 0; i <= last; i++) {
        ctx->error_depth = i;
        ok = check_cert(ctx);
        if (!ok)
            return ok;
    }
    return 1;
}

Project: openssl

static int check_trust(X509_STORE_CTX *ctx)
{
#ifdef OPENSSL_NO_CHAIN_VERIFY
    return 1;
#else
    int i, ok;
    X509 *x;
    int (*cb) (int xok, X509_STORE_CTX *xctx);
    cb = ctx->verify_cb;
/* For now just check the last certificate in the chain */
    i = sk_X509_num(ctx->chain) - 1;
    x = sk_X509_value(ctx->chain, i);
    ok = X509_check_trust(x, ctx->param->trust, 0);
    if (ok == X509_TRUST_TRUSTED)
        return 1;
    ctx->error_depth = i;
    ctx->current_cert = x;
    if (ok == X509_TRUST_REJECTED)
        ctx->error = X509_V_ERR_CERT_REJECTED;
    else
        ctx->error = X509_V_ERR_CERT_UNTRUSTED;
    ok = cb(0, ctx);
    return ok;
#endif
}

Project: openssl

static int crl_crldp_check(X509 *x, X509_CRL *crl, int crl_score,
                           unsigned int *preasons)
{
    int i;
    if (crl->idp_flags & IDP_ONLYATTR)
        return 0;
    if (x->ex_flags & EXFLAG_CA) {
        if (crl->idp_flags & IDP_ONLYUSER)
            return 0;
    } else {
        if (crl->idp_flags & IDP_ONLYCA)
            return 0;
    }
    *preasons = crl->idp_reasons;
    for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) {
        DIST_POINT *dp = sk_DIST_POINT_value(x->crldp, i);
        if (crldp_check_crlissuer(dp, crl, crl_score)) {
            if (!crl->idp || idp_check_dp(dp->distpoint, crl->idp->distpoint)) {
                *preasons &= dp->dp_reasons;
                return 1;
            }
        }
    }
    if ((!crl->idp || !crl->idp->distpoint)
        && (crl_score & CRL_SCORE_ISSUER_NAME))
        return 1;
    return 0;
}

Project: openssl

static int crl_extension_match(X509_CRL *a, X509_CRL *b, int nid)
{
    ASN1_OCTET_STRING *exta, *extb;
    int i;
    i = X509_CRL_get_ext_by_NID(a, nid, -1);
    if (i >= 0) {
        /* Can't have multiple occurrences */
        if (X509_CRL_get_ext_by_NID(a, nid, i) != -1)
            return 0;
        exta = X509_EXTENSION_get_data(X509_CRL_get_ext(a, i));
    } else
        exta = NULL;

    i = X509_CRL_get_ext_by_NID(b, nid, -1);

    if (i >= 0) {

        if (X509_CRL_get_ext_by_NID(b, nid, i) != -1)
            return 0;
        extb = X509_EXTENSION_get_data(X509_CRL_get_ext(b, i));
    } else
        extb = NULL;

    if (!exta && !extb)
        return 1;

    if (!exta || !extb)
        return 0;

    if (ASN1_OCTET_STRING_cmp(exta, extb))
        return 0;

    return 1;
}

Project: openssl

static int crldp_check_crlissuer(DIST_POINT *dp, X509_CRL *crl, int crl_score)
{
    int i;
    X509_NAME *nm = X509_CRL_get_issuer(crl);
    /* If no CRLissuer return is successful iff don't need a match */
    if (!dp->CRLissuer)
        return ! !(crl_score & CRL_SCORE_ISSUER_NAME);
    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)
            continue;
        if (!X509_NAME_cmp(gen->d.directoryName, nm))
            return 1;
    }
    return 0;
}

Project: openssl

static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x)
{
    int i;
    X509 *issuer;
    for (i = 0; i < sk_X509_num(sk); i++) {
        issuer = sk_X509_value(sk, i);
        if (ctx->check_issued(ctx, x, issuer))
            return issuer;
    }
    return NULL;
}

Project: openssl

static int get_crl_delta(X509_STORE_CTX *ctx,
                         X509_CRL **pcrl, X509_CRL **pdcrl, X509 *x)
{
    int ok;
    X509 *issuer = NULL;
    int crl_score = 0;
    unsigned int reasons;
    X509_CRL *crl = NULL, *dcrl = NULL;
    STACK_OF(X509_CRL) *skcrl;
    X509_NAME *nm = X509_get_issuer_name(x);
    reasons = ctx->current_reasons;
    ok = get_crl_sk(ctx, &crl, &dcrl,
                    &issuer, &crl_score, &reasons, ctx->crls);

    if (ok)
        goto done;

    /* Lookup CRLs from store */

    skcrl = ctx->lookup_crls(ctx, nm);

    /* If no CRLs found and a near match from get_crl_sk use that */
    if (!skcrl && crl)
        goto done;

    get_crl_sk(ctx, &crl, &dcrl, &issuer, &crl_score, &reasons, skcrl);

    sk_X509_CRL_pop_free(skcrl, X509_CRL_free);

 done:

    /* If we got any kind of CRL use it and return success */
    if (crl) {
        ctx->current_issuer = issuer;
        ctx->current_crl_score = crl_score;
        ctx->current_reasons = reasons;
        *pcrl = crl;
        *pdcrl = dcrl;
        return 1;
    }

    return 0;
}

Project: openssl

static int get_crl_score(X509_STORE_CTX *ctx, X509 **pissuer,
                         unsigned int *preasons, X509_CRL *crl, X509 *x)
{

    int crl_score = 0;
    unsigned int tmp_reasons = *preasons, crl_reasons;

    /* First see if we can reject CRL straight away */

    /* Invalid IDP cannot be processed */
    if (crl->idp_flags & IDP_INVALID)
        return 0;
    /* Reason codes or indirect CRLs need extended CRL support */
    if (!(ctx->param->flags & X509_V_FLAG_EXTENDED_CRL_SUPPORT)) {
        if (crl->idp_flags & (IDP_INDIRECT | IDP_REASONS))
            return 0;
    } else if (crl->idp_flags & IDP_REASONS) {
        /* If no new reasons reject */
        if (!(crl->idp_reasons & ~tmp_reasons))
            return 0;
    }
    /* Don't process deltas at this stage */
    else if (crl->base_crl_number)
        return 0;
    /* If issuer name doesn't match certificate need indirect CRL */
    if (X509_NAME_cmp(X509_get_issuer_name(x), X509_CRL_get_issuer(crl))) {
        if (!(crl->idp_flags & IDP_INDIRECT))
            return 0;
    } else
        crl_score |= CRL_SCORE_ISSUER_NAME;

    if (!(crl->flags & EXFLAG_CRITICAL))
        crl_score |= CRL_SCORE_NOCRITICAL;

    /* Check expiry */
    if (check_crl_time(ctx, crl, 0))
        crl_score |= CRL_SCORE_TIME;

    /* Check authority key ID and locate certificate issuer */
    crl_akid_check(ctx, crl, pissuer, &crl_score);

    /* If we can't locate certificate issuer at this point forget it */

    if (!(crl_score & CRL_SCORE_AKID))
        return 0;

    /* Check cert for matching CRL distribution points */

    if (crl_crldp_check(x, crl, crl_score, &crl_reasons)) {
        /* If no new reasons reject */
        if (!(crl_reasons & ~tmp_reasons))
            return 0;
        tmp_reasons |= crl_reasons;
        crl_score |= CRL_SCORE_SCOPE;
    }

    *preasons = tmp_reasons;

    return crl_score;

}

Project: openssl

static void get_delta_sk(X509_STORE_CTX *ctx, X509_CRL **dcrl, int *pscore,
                         X509_CRL *base, STACK_OF(X509_CRL) *crls)
{
    X509_CRL *delta;
    int i;
    if (!(ctx->param->flags & X509_V_FLAG_USE_DELTAS))
        return;
    if (!((ctx->current_cert->ex_flags | base->flags) & EXFLAG_FRESHEST))
        return;
    for (i = 0; i < sk_X509_CRL_num(crls); i++) {
        delta = sk_X509_CRL_value(crls, i);
        if (check_delta_base(delta, base)) {
            if (check_crl_time(ctx, delta, 0))
                *pscore |= CRL_SCORE_TIME_DELTA;
            CRYPTO_add(&delta->references, 1, CRYPTO_LOCK_X509_CRL);
            *dcrl = delta;
            return;
        }
    }
    *dcrl = NULL;
}

Project: openssl

static int get_issuer_sk(X509 **issuer, X509_STORE_CTX *ctx, X509 *x)
{
    *issuer = find_issuer(ctx, ctx->other_ctx, x);
    if (*issuer) {
        CRYPTO_add(&(*issuer)->references, 1, CRYPTO_LOCK_X509);
        return 1;
    } else
        return 0;
}

Project: openssl

static int idp_check_dp(DIST_POINT_NAME *a, DIST_POINT_NAME *b)
{
    X509_NAME *nm = NULL;
    GENERAL_NAMES *gens = NULL;
    GENERAL_NAME *gena, *genb;
    int i, j;
    if (!a || !b)
        return 1;
    if (a->type == 1) {
        if (!a->dpname)
            return 0;
        /* Case 1: two X509_NAME */
        if (b->type == 1) {
            if (!b->dpname)
                return 0;
            if (!X509_NAME_cmp(a->dpname, b->dpname))
                return 1;
            else
                return 0;
        }
        /* Case 2: set name and GENERAL_NAMES appropriately */
        nm = a->dpname;
        gens = b->name.fullname;
    } else if (b->type == 1) {
        if (!b->dpname)
            return 0;
        /* Case 2: set name and GENERAL_NAMES appropriately */
        gens = a->name.fullname;
        nm = b->dpname;
    }

    /* Handle case 2 with one GENERAL_NAMES and one X509_NAME */
    if (nm) {
        for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
            gena = sk_GENERAL_NAME_value(gens, i);
            if (gena->type != GEN_DIRNAME)
                continue;
            if (!X509_NAME_cmp(nm, gena->d.directoryName))
                return 1;
        }
        return 0;
    }

    /* Else case 3: two GENERAL_NAMES */

    for (i = 0; i < sk_GENERAL_NAME_num(a->name.fullname); i++) {
        gena = sk_GENERAL_NAME_value(a->name.fullname, i);
        for (j = 0; j < sk_GENERAL_NAME_num(b->name.fullname); j++) {
            genb = sk_GENERAL_NAME_value(b->name.fullname, j);
            if (!GENERAL_NAME_cmp(gena, genb))
                return 1;
        }
    }

    return 0;

}

Project: openssl

static int internal_verify(X509_STORE_CTX *ctx)
{
    int ok = 0, n;
    X509 *xs, *xi;
    EVP_PKEY *pkey = NULL;
    int (*cb) (int xok, X509_STORE_CTX *xctx);

    cb = ctx->verify_cb;

    n = sk_X509_num(ctx->chain);
    ctx->error_depth = n - 1;
    n--;
    xi = sk_X509_value(ctx->chain, n);

    if (ctx->check_issued(ctx, xi, xi))
        xs = xi;
    else {
        if (n <= 0) {
            ctx->error = X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE;
            ctx->current_cert = xi;
            ok = cb(0, ctx);
            goto end;
        } else {
            n--;
            ctx->error_depth = n;
            xs = sk_X509_value(ctx->chain, n);
        }
    }

/*      ctx->error=0;  not needed */
    while (n >= 0) {
        ctx->error_depth = n;

        /*
         * Skip signature check for self signed certificates unless
         * explicitly asked for. It doesn't add any security and just wastes
         * time.
         */
        if (!xs->valid
            && (xs != xi
                || (ctx->param->flags & X509_V_FLAG_CHECK_SS_SIGNATURE))) {
            if ((pkey = X509_get_pubkey(xi)) == NULL) {
                ctx->error = X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY;
                ctx->current_cert = xi;
                ok = (*cb) (0, ctx);
                if (!ok)
                    goto end;
            } else if (X509_verify(xs, pkey) <= 0) {
                ctx->error = X509_V_ERR_CERT_SIGNATURE_FAILURE;
                ctx->current_cert = xs;
                ok = (*cb) (0, ctx);
                if (!ok) {
                    EVP_PKEY_free(pkey);
                    goto end;
                }
            }
            EVP_PKEY_free(pkey);
            pkey = NULL;
        }

        xs->valid = 1;

        ok = check_cert_time(ctx, xs);
        if (!ok)
            goto end;

        /* The last error (if any) is still in the error value */
        ctx->current_issuer = xi;
        ctx->current_cert = xs;
        ok = (*cb) (1, ctx);
        if (!ok)
            goto end;

        n--;
        if (n >= 0) {
            xi = xs;
            xs = sk_X509_value(ctx->chain, n);
        }
    }
    ok = 1;
 end:
    return ok;
}

Project: openssl

static int null_callback(int ok, X509_STORE_CTX *e)
{
    return ok;
}