/src/openssl41/crypto/x509/v3_purp.c

Source
/*
 * Copyright 1999-2026 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 "crypto/x509.h"
#include "internal/tsan_assist.h"
#include "x509_local.h"
#include "crypto/objects/obj_dat.h"
#include "crypto/siphash.h"
#include <openssl/rand.h>

static int check_ssl_ca(const X509 *x);
static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int purpose_smime(const X509 *x, int non_leaf);
static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_purpose_code_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int no_check_purpose(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_purpose_ocsp_helper(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf);
static int check_name_constraints(const NAME_CONSTRAINTS *nc);

static int xp_cmp(const X509_PURPOSE *const *a, const X509_PURPOSE *const *b);
static void xptable_free(X509_PURPOSE *p);

/* note that the id must be unique and for the standard entries == idx + 1 */
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_purpose,
        "Any Purpose", "any",
        NULL },
    { X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, check_purpose_ocsp_helper,
        "OCSP helper", "ocsphelper", NULL },
    { X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0,
        check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign",
        NULL },
    { X509_PURPOSE_CODE_SIGN, X509_TRUST_OBJECT_SIGN, 0,
        check_purpose_code_sign, "Code signing", "codesign",
        NULL },
};

#define X509_PURPOSE_COUNT OSSL_NELEM(xstandard)

/* the id must be unique, but there may be gaps and maybe table is not sorted */
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;
}

int X509_check_purpose(const X509 *x, int id, int non_leaf)
{
    int idx;
    const X509_PURPOSE *pt;

    /*
     * TODO: This cast can be dropped when https://github.com/openssl/openssl/pull/30067
     * gets merged
     */
    if (!ossl_x509v3_cache_extensions((X509 *)x))
        return -1;
    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, non_leaf);
}

/* resets to default (any) purpose if purpose == X509_PURPOSE_DEFAULT_ANY (0) */
int X509_PURPOSE_set(int *p, int purpose)
{
    if (purpose != X509_PURPOSE_DEFAULT_ANY && X509_PURPOSE_get_by_id(purpose) == -1) {
        ERR_raise(ERR_LIB_X509V3, 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;
}

/* find smallest identifier not yet taken - note there might be gaps */
int X509_PURPOSE_get_unused_id(ossl_unused OSSL_LIB_CTX *libctx)
{
    int id = X509_PURPOSE_MAX + 1;

    while (X509_PURPOSE_get_by_id(id) != -1)
        id++;
    return id; /* is guaranteed to be unique and > X509_PURPOSE_MAX and != 0 */
}

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;
}

/* Returns -1 on error, else an index => 0 in standard/extended purpose table */
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;
}

/*
 * Add purpose entry identified by |sname|. |id| must be >= X509_PURPOSE_MIN.
 * May also be used to modify existing entry, including changing its id.
 */
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 old_id = 0;
    int idx;
    X509_PURPOSE *ptmp;

    if (id < X509_PURPOSE_MIN) {
        ERR_raise(ERR_LIB_X509V3, X509V3_R_INVALID_PURPOSE);
        return 0;
    }
    if (trust < X509_TRUST_DEFAULT || name == NULL || sname == NULL || ck == NULL) {
        ERR_raise(ERR_LIB_X509V3, ERR_R_PASSED_INVALID_ARGUMENT);
        return 0;
    }

    /* 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_sname(sname);
    if (idx == -1) { /* Need a new entry */
        if (X509_PURPOSE_get_by_id(id) != -1) {
            ERR_raise(ERR_LIB_X509V3, X509V3_R_PURPOSE_NOT_UNIQUE);
            return 0;
        }
        if ((ptmp = OPENSSL_malloc(sizeof(*ptmp))) == NULL)
            return 0;
        ptmp->flags = X509_PURPOSE_DYNAMIC;
    } else {
        ptmp = X509_PURPOSE_get0(idx);
        old_id = ptmp->purpose;
        if (id != old_id && X509_PURPOSE_get_by_id(id) != -1) {
            ERR_raise(ERR_LIB_X509V3, X509V3_R_PURPOSE_NOT_UNIQUE);
            return 0;
        }
    }

    /* OPENSSL_free existing name if dynamic */
    if ((ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) != 0) {
        OPENSSL_free(ptmp->name);
        OPENSSL_free(ptmp->sname);
    }
    /* Dup supplied name */
    ptmp->name = OPENSSL_strdup(name);
    ptmp->sname = OPENSSL_strdup(sname);
    if (ptmp->name == NULL || ptmp->sname == NULL)
        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) {
            ERR_raise(ERR_LIB_X509V3, ERR_R_CRYPTO_LIB);
            goto err;
        }
        if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
            ERR_raise(ERR_LIB_X509V3, ERR_R_CRYPTO_LIB);
            goto err;
        }
    } else if (id != old_id) {
        /* on changing existing entry id, make sure to reset 'sorted' */
        (void)sk_X509_PURPOSE_set(xptable, idx, ptmp);
    }
    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 == NULL)
        return;
    if ((p->flags & X509_PURPOSE_DYNAMIC) != 0) {
        if ((p->flags & X509_PURPOSE_DYNAMIC_NAME) != 0) {
            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(const 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_id_pkix_OCSP_noCheck, /* 369 */
        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;
}

/*
 * Returns 1 on success, 0 if x is invalid.
 *
 * The full name of a nameRelativeToCRLIssuer distribution point is not
 * computed here.  Doing so for every parsed certificate cost an
 * X509_NAME_dup() of the issuer name per relative distribution point,
 * which a certificate with many such entries could turn into hundreds of
 * megabytes of heap on a plain TLS handshake, while the result is only
 * needed when a CRL is actually being matched against the certificate.
 * That name is now built on demand in the CRL checking code instead.
 */
static int setup_dp(DIST_POINT *dp)
{
    if (dp->distpoint == NULL && sk_GENERAL_NAME_num(dp->CRLissuer) <= 0) {
        ERR_raise(ERR_LIB_X509, X509_R_INVALID_DISTPOINT);
        return 0;
    }
    if (dp->reasons != NULL) {
        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;
    }
    return 1;
}

/* Return 1 on success, 0 if x is invalid. */
static int setup_crldp(const X509 *x, STACK_OF(DIST_POINT) **tmp_crldp)
{
    int i;

    *tmp_crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL);
    if (*tmp_crldp == NULL && i != -1)
        return 0;

    for (i = 0; i < sk_DIST_POINT_num(*tmp_crldp); i++) {
        if (!setup_dp(sk_DIST_POINT_value(*tmp_crldp, i)))
            return 0;
    }
    return 1;
}

/* Check that issuer public key algorithm matches subject signature algorithm */
static int check_sig_alg_match(const EVP_PKEY *issuer_key, const X509 *subject)
{
    int subj_sig_nid;

    if (issuer_key == NULL)
        return X509_V_ERR_NO_ISSUER_PUBLIC_KEY;
    if (OBJ_find_sigid_algs(OBJ_obj2nid(subject->cert_info.signature.algorithm),
            NULL, &subj_sig_nid)
        == 0)
        return X509_V_ERR_UNSUPPORTED_SIGNATURE_ALGORITHM;
    if (EVP_PKEY_is_a(issuer_key, OBJ_nid2sn(subj_sig_nid))
        || (EVP_PKEY_is_a(issuer_key, "RSA") && subj_sig_nid == NID_rsassaPss))
        return X509_V_OK;
    return X509_V_ERR_SIGNATURE_ALGORITHM_MISMATCH;
}

/*
 * Per-scan SipHash keying for the duplicate-extension fall-back table.
 *
 * Standard extensions have an assigned NID and are deduplicated with the O(1)
 * bitset in scan_ext_flags(). Only unknown or dynamically registered OIDs,
 * whose bytes are fully attacker-controlled on an untrusted certificate, reach
 * the hash table. An unkeyed hash would let an attacker precompute colliding
 * OIDs and drive the table into O(n^2) chain walks (hash flooding). Hash the
 * OID with SipHash under a random key drawn once per scan, mirroring the
 * defense in ssl/quic/quic_lcidm.c.
 */
typedef struct {
    const ASN1_OBJECT *obj;
    const uint64_t *key; /* 128-bit SipHash key owned by scan_ext_flags */
} oid_hte;

static unsigned long oid_hash(const void *p)
{
    const oid_hte *e = (const oid_hte *)p;
    SIPHASH sip = { 0 };
    unsigned char digest[SIPHASH_MIN_DIGEST_SIZE];
    unsigned long v = 0;

    if (!SipHash_set_hash_size(&sip, SIPHASH_MIN_DIGEST_SIZE))
        return 0;
    if (!SipHash_Init(&sip, (const unsigned char *)e->key, 0, 0))
        return 0;
    SipHash_Update(&sip, (const unsigned char *)e->obj->data, e->obj->length);

    if (!SipHash_Final(&sip, digest, sizeof(digest)))
        return 0;
    memcpy(&v, digest, sizeof(v) < sizeof(digest) ? sizeof(v) : sizeof(digest));
    return v;
}

static int oid_cmp(const void *a, const void *b)
{
    return OBJ_cmp(((const oid_hte *)a)->obj, ((const oid_hte *)b)->obj);
}

/*
 * Scan all extensions of a certificate to collect extension-related flags.
 * Detects duplicate extensions (RFC 5280 section 4.2), the presence of a
 * freshest CRL extension and unsupported critical extensions.
 *
 * In the future, if needed, this scanning function could return the index
 * of the offending extension on error, allowing the caller to identify which
 * extension caused the problem and report it via ERR_raise_data().
 */
static void scan_ext_flags(const X509 *x509, uint32_t *flags)
{
    OPENSSL_LHASH *h = NULL;
    oid_hte *arr = NULL;
    size_t num_entries = 0;
    uint64_t k[2]; /* random SipHash key for the fall-back table */
    uint8_t ex_bitset[(NUM_NID + 7) / 8];
    int count = X509_get_ext_count(x509);

    memset(ex_bitset, 0, sizeof(ex_bitset));
    /* A certificate MUST NOT include more than one instance of an extension. */
    for (int i = 0; i < count; i++) {
        const X509_EXTENSION *ex = X509_get_ext(x509, i);
        const ASN1_OBJECT *a = X509_EXTENSION_get_object(ex);
        int nid = OBJ_obj2nid(a);

        /*
         * Known NIDs within the build-time bitset limit are checked for
         * duplicates in constant time. Unknown OIDs and dynamically registered
         * NIDs that exceed the limit fall back to duplicate detection via a
         * hash table.
         */
        if (nid > NID_undef && nid < NUM_NID) {
            unsigned int ex_bit = nid;

            if ((ex_bitset[ex_bit >> 3] & (1u << (ex_bit & 7))) != 0) {
                *flags |= EXFLAG_DUPLICATE;
                break;
            }
            ex_bitset[ex_bit >> 3] |= (1u << (ex_bit & 7));
        } else {
            /*
             * Extensions with unknown NID (NID_undef) and dynamically
             * registered NIDs are handled here by hashing the OID (data/length).
             * A zero-length OID should not reach this point, but we check for
             * it anyway and assign the EXFLAG_INVALID flag if it does.
             */
            if (a->length < 1) {
                *flags |= EXFLAG_INVALID;
                break;
            }
            /*
             * Create the table and draw a fresh random SipHash key the first
             * time an attacker-controlled OID is seen, so unkeyed hashing
             * cannot be used to force O(n^2) collisions (hash flooding).
             *
             * The key and the entry wrappers remain valid for the duration of
             * the scan; the table never outlives this function.
             *
             * If the table cannot be set up or an insert fails, fail closed
             * with EXFLAG_INVALID, as ossl_x509v3_cache_extensions() does for
             * any other extension it cannot process. Leaving the loop
             * silently would skip not only the duplicate check but also the
             * unsupported-critical check for this and every later extension.
             */
            if (h == NULL) {
                if (RAND_bytes_ex(x509->libctx, (unsigned char *)k, sizeof(k), 0) <= 0
                    || (arr = OPENSSL_malloc_array(count, sizeof(*arr))) == NULL
                    || (h = OPENSSL_LH_new(oid_hash, oid_cmp)) == NULL) {
                    *flags |= EXFLAG_INVALID;
                    break;
                }
            }
            arr[num_entries].obj = a;
            arr[num_entries].key = k;
            if (OPENSSL_LH_insert(h, &arr[num_entries]) != NULL) {
                *flags |= EXFLAG_DUPLICATE;
                break;
            }
            if (OPENSSL_LH_error(h) != 0) {
                *flags |= EXFLAG_INVALID;
                break;
            }
            num_entries++;
        }
        if (nid == NID_freshest_crl)
            *flags |= EXFLAG_FRESHEST;
        if (!X509_EXTENSION_get_critical(ex))
            continue;
        if (!X509_supported_extension(ex)) {
            *flags |= EXFLAG_CRITICAL;
            break;
        }
    }
    OPENSSL_LH_free(h);
    OPENSSL_free(arr);
}

#define V1_ROOT (EXFLAG_V1 | EXFLAG_SS)
#define ku_reject(x, usage) \
    (((x)->ex_flags & EXFLAG_KUSAGE) != 0 && ((x)->ex_kusage & (usage)) == 0)
#define xku_reject(x, usage) \
    (((x)->ex_flags & EXFLAG_XKUSAGE) != 0 && ((x)->ex_xkusage & (usage)) == 0)
#define ns_reject(x, usage) \
    (((x)->ex_flags & EXFLAG_NSCERT) != 0 && ((x)->ex_nscert & (usage)) == 0)

/*
 * Cache info on various X.509v3 extensions and further derived information,
 * e.g., if cert 'x' is self-issued, in x->ex_flags and other internal fields.
 * x->sha1_hash is filled in, or else EXFLAG_NO_FINGERPRINT is set in x->flags.
 * X509_SIG_INFO_VALID is set in x->flags if x->siginf was filled successfully.
 * Set EXFLAG_INVALID and return 0 in case the certificate is invalid.
 *
 * This is usually called by side-effect on objects, and forces us to keep
 * mutable X509 objects around. We should really make this go away.
 * In the interest of being able to do so, this function explicitly takes
 * a const argument and casts away const.
 */
int ossl_x509v3_cache_extensions(const X509 *const_x)
{
    BASIC_CONSTRAINTS *bs;
    PROXY_CERT_INFO_EXTENSION *pci;
    ASN1_BIT_STRING *usage;
    ASN1_BIT_STRING *ns;
    EXTENDED_KEY_USAGE *extusage;
    int i;
    int res;
    uint32_t tmp_ex_flags;
    unsigned char tmp_sha1_hash[SHA_DIGEST_LENGTH];
    long tmp_ex_pathlen;
    long tmp_ex_pcpathlen;
    uint32_t tmp_ex_kusage;
    uint32_t tmp_ex_xkusage;
    uint32_t tmp_ex_nscert;
    ASN1_OCTET_STRING *tmp_skid = NULL;
    AUTHORITY_KEYID *tmp_akid = NULL;
    STACK_OF(GENERAL_NAME) *tmp_altname = NULL;
    NAME_CONSTRAINTS *tmp_nc = NULL;
    STACK_OF(DIST_POINT) *tmp_crldp = NULL;
    X509_SIG_INFO tmp_siginf;
#ifndef OPENSSL_NO_RFC3779
    STACK_OF(IPAddressFamily) *tmp_rfc3779_addr = NULL;
    struct ASIdentifiers_st *tmp_rfc3779_asid = NULL;
#endif
    int ret = 0;

#ifdef tsan_ld_acq
    /* Fast lock-free check, see end of the function for details. */
    if (tsan_ld_acq((TSAN_QUALIFIER int *)&const_x->ex_cached)) {
        ret = (const_x->ex_flags & EXFLAG_INVALID) == 0;
        goto done;
    }
#endif

    if (!CRYPTO_THREAD_read_lock(const_x->lock))
        goto done;
    tmp_ex_flags = const_x->ex_flags;
    tmp_ex_pcpathlen = const_x->ex_pcpathlen;
    tmp_ex_kusage = const_x->ex_kusage;
    tmp_ex_nscert = const_x->ex_nscert;

    if ((tmp_ex_flags & EXFLAG_SET) != 0) { /* Cert has already been processed */
        CRYPTO_THREAD_unlock(const_x->lock);
        ret = (tmp_ex_flags & EXFLAG_INVALID) == 0;
        goto done;
    }

    ERR_set_mark();

    /* Cache the SHA1 digest of the cert */
    if (!X509_digest(const_x, EVP_sha1(), tmp_sha1_hash, NULL))
        tmp_ex_flags |= EXFLAG_NO_FINGERPRINT;

    /* V1 should mean no extensions ... */
    if (X509_get_version(const_x) == X509_VERSION_1)
        tmp_ex_flags |= EXFLAG_V1;

    /* Handle basic constraints */
    tmp_ex_pathlen = -1;
    if ((bs = X509_get_ext_d2i(const_x, NID_basic_constraints, &i, NULL)) != NULL) {
        if (bs->ca)
            tmp_ex_flags |= EXFLAG_CA;
        if (bs->pathlen != NULL) {
            /*
             * The error case !bs->ca is checked by check_chain()
             * in case ctx->param->flags & X509_V_FLAG_X509_STRICT
             */
            if (bs->pathlen->type == V_ASN1_NEG_INTEGER) {
                ERR_raise(ERR_LIB_X509V3, X509V3_R_NEGATIVE_PATHLEN);
                tmp_ex_flags |= EXFLAG_INVALID;
            } else {
                tmp_ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
            }
        }
        BASIC_CONSTRAINTS_free(bs);
        tmp_ex_flags |= EXFLAG_BCONS;
    } else if (i != -1) {
        tmp_ex_flags |= EXFLAG_INVALID;
    }

    /* Handle proxy certificates */
    if ((pci = X509_get_ext_d2i(const_x, NID_proxyCertInfo, &i, NULL)) != NULL) {
        if ((tmp_ex_flags & EXFLAG_CA) != 0
            || X509_get_ext_by_NID(const_x, NID_subject_alt_name, -1) >= 0
            || X509_get_ext_by_NID(const_x, NID_issuer_alt_name, -1) >= 0) {
            tmp_ex_flags |= EXFLAG_INVALID;
        }
        if (pci->pcPathLengthConstraint != NULL)
            tmp_ex_pcpathlen = ASN1_INTEGER_get(pci->pcPathLengthConstraint);
        else
            tmp_ex_pcpathlen = -1;
        PROXY_CERT_INFO_EXTENSION_free(pci);
        tmp_ex_flags |= EXFLAG_PROXY;
    } else if (i != -1) {
        tmp_ex_flags |= EXFLAG_INVALID;
    }

    /* Handle (basic) key usage */
    if ((usage = X509_get_ext_d2i(const_x, NID_key_usage, &i, NULL)) != NULL) {
        tmp_ex_kusage = 0;
        if (usage->length > 0) {
            tmp_ex_kusage = usage->data[0];
            if (usage->length > 1)
                tmp_ex_kusage |= usage->data[1] << 8;
        }
        tmp_ex_flags |= EXFLAG_KUSAGE;
        ASN1_BIT_STRING_free(usage);
        /* Check for empty key usage according to RFC 5280 section 4.2.1.3 */
        if (tmp_ex_kusage == 0) {
            ERR_raise(ERR_LIB_X509V3, X509V3_R_EMPTY_KEY_USAGE);
            tmp_ex_flags |= EXFLAG_INVALID;
        }
    } else if (i != -1) {
        tmp_ex_flags |= EXFLAG_INVALID;
    }

    /* Handle extended key usage */
    tmp_ex_xkusage = 0;
    if ((extusage = X509_get_ext_d2i(const_x, NID_ext_key_usage, &i, NULL)) != NULL) {
        tmp_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:
                tmp_ex_xkusage |= XKU_SSL_SERVER;
                break;
            case NID_client_auth:
                tmp_ex_xkusage |= XKU_SSL_CLIENT;
                break;
            case NID_email_protect:
                tmp_ex_xkusage |= XKU_SMIME;
                break;
            case NID_code_sign:
                tmp_ex_xkusage |= XKU_CODE_SIGN;
                break;
            case NID_ms_sgc:
            case NID_ns_sgc:
                tmp_ex_xkusage |= XKU_SGC;
                break;
            case NID_OCSP_sign:
                tmp_ex_xkusage |= XKU_OCSP_SIGN;
                break;
            case NID_time_stamp:
                tmp_ex_xkusage |= XKU_TIMESTAMP;
                break;
            case NID_dvcs:
                tmp_ex_xkusage |= XKU_DVCS;
                break;
            case NID_anyExtendedKeyUsage:
                tmp_ex_xkusage |= XKU_ANYEKU;
                break;
            default:
                /* Ignore unknown extended key usage */
                break;
            }
        }
        sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
    } else if (i != -1) {
        tmp_ex_flags |= EXFLAG_INVALID;
    }

    /* Handle legacy Netscape extension */
    if ((ns = X509_get_ext_d2i(const_x, NID_netscape_cert_type, &i, NULL)) != NULL) {
        if (ns->length > 0)
            tmp_ex_nscert = ns->data[0];
        else
            tmp_ex_nscert = 0;
        tmp_ex_flags |= EXFLAG_NSCERT;
        ASN1_BIT_STRING_free(ns);
    } else if (i != -1) {
        tmp_ex_flags |= EXFLAG_INVALID;
    }

    /* Handle subject key identifier and issuer/authority key identifier */
    tmp_skid = X509_get_ext_d2i(const_x, NID_subject_key_identifier, &i, NULL);
    if (tmp_skid == NULL && i != -1)
        tmp_ex_flags |= EXFLAG_INVALID;

    tmp_akid = X509_get_ext_d2i(const_x, NID_authority_key_identifier, &i, NULL);
    if (tmp_akid == NULL && i != -1)
        tmp_ex_flags |= EXFLAG_INVALID;

    /* Setting EXFLAG_SS is equivalent to ossl_x509_likely_issued(const_x, const_x) == X509_V_OK */
    if (X509_NAME_cmp(X509_get_subject_name(const_x), X509_get_issuer_name(const_x)) == 0) {
        tmp_ex_flags |= EXFLAG_SI; /* Certificate is self-issued: subject == issuer */
        /*
         * When the SKID is missing, which is rare for self-issued certs,
         * we could afford doing the (accurate) actual self-signature check, but
         * decided against it for efficiency reasons and according to RFC 5280,
         * CA certs MUST have an SKID and non-root certs MUST have an AKID.
         *
         * The cached const_x->skid is not populated until the write-lock
         * publication below, so the keyid comparison is done directly
         * against tmp_skid.  X509_check_akid() is retained for its serial
         * number and issuer name checks.
         */
        if ((tmp_akid == NULL || tmp_akid->keyid == NULL || tmp_skid == NULL
                || ASN1_OCTET_STRING_cmp(tmp_akid->keyid, tmp_skid) == 0)
            && X509_check_akid(const_x, tmp_akid) == X509_V_OK
            && check_sig_alg_match(X509_get0_pubkey(const_x), const_x) == X509_V_OK) {
            /*
             * Assume self-signed if the signature alg matches the pkey alg and
             * AKID is missing or matches respective fields in the same cert
             * Not checking if any given key usage extension allows signing.
             */
            tmp_ex_flags |= EXFLAG_SS;
        }
    }

    /* Handle subject alternative names and various other extensions */
    tmp_altname = X509_get_ext_d2i(const_x, NID_subject_alt_name, &i, NULL);
    if (tmp_altname == NULL && i != -1)
        tmp_ex_flags |= EXFLAG_INVALID;
    tmp_nc = X509_get_ext_d2i(const_x, NID_name_constraints, &i, NULL);
    if (tmp_nc == NULL && i != -1)
        tmp_ex_flags |= EXFLAG_INVALID;
    if (!check_name_constraints(tmp_nc))
        tmp_ex_flags |= EXFLAG_INVALID;

    /* Handle CRL distribution point entries */
    res = setup_crldp(const_x, &tmp_crldp);
    if (res == 0)
        tmp_ex_flags |= EXFLAG_INVALID;

#ifndef OPENSSL_NO_RFC3779
    tmp_rfc3779_addr = X509_get_ext_d2i(const_x, NID_sbgp_ipAddrBlock, &i, NULL);
    if (tmp_rfc3779_addr == NULL && i != -1)
        tmp_ex_flags |= EXFLAG_INVALID;

    tmp_rfc3779_asid = X509_get_ext_d2i(const_x, NID_sbgp_autonomousSysNum, &i, NULL);
    if (tmp_rfc3779_asid == NULL && i != -1)
        tmp_ex_flags |= EXFLAG_INVALID;
#endif

    scan_ext_flags(const_x, &tmp_ex_flags);

    /* Set x->siginf, ignoring errors due to unsupported algos */
    (void)ossl_x509_init_sig_info(const_x, &tmp_siginf);

    tmp_ex_flags |= EXFLAG_SET; /* Indicate that cert has been processed */
    ERR_pop_to_mark();

    CRYPTO_THREAD_unlock(const_x->lock);
    /*
     * Now that we've done all the compute intensive work under read lock
     * do all the updating under a write lock
     */
    if (!CRYPTO_THREAD_write_lock(const_x->lock))
        goto done;

    /* See if another thread updated this certificate before we got the write lock. */
    if ((const_x->ex_flags & EXFLAG_SET) != 0) { /* Cert has already been processed */
        CRYPTO_THREAD_unlock(const_x->lock);
        ret = (const_x->ex_flags & EXFLAG_INVALID) == 0;
        goto done;
    }

    /* Otherwise, we have the lock, set the cached fields in the cert. */
    ((X509 *)const_x)->ex_flags = tmp_ex_flags;
    ((X509 *)const_x)->ex_pathlen = tmp_ex_pathlen;
    ((X509 *)const_x)->ex_pcpathlen = tmp_ex_pcpathlen;
    if (!(tmp_ex_flags & EXFLAG_NO_FINGERPRINT))
        memcpy(((X509 *)const_x)->sha1_hash, tmp_sha1_hash, SHA_DIGEST_LENGTH);
    if (tmp_ex_flags & EXFLAG_KUSAGE)
        ((X509 *)const_x)->ex_kusage = tmp_ex_kusage;
    ((X509 *)const_x)->ex_xkusage = tmp_ex_xkusage;
    if (tmp_ex_flags & EXFLAG_NSCERT)
        ((X509 *)const_x)->ex_nscert = tmp_ex_nscert;
    ASN1_OCTET_STRING_free(((X509 *)const_x)->skid);
    ((X509 *)const_x)->skid = tmp_skid;
    tmp_skid = NULL;
    AUTHORITY_KEYID_free(((X509 *)const_x)->akid);
    ((X509 *)const_x)->akid = tmp_akid;
    tmp_akid = NULL;
    sk_GENERAL_NAME_pop_free(((X509 *)const_x)->altname, GENERAL_NAME_free);
    ((X509 *)const_x)->altname = tmp_altname;
    tmp_altname = NULL;
    NAME_CONSTRAINTS_free(((X509 *)const_x)->nc);
    ((X509 *)const_x)->nc = tmp_nc;
    tmp_nc = NULL;
    sk_DIST_POINT_pop_free(((X509 *)const_x)->crldp, DIST_POINT_free);
    ((X509 *)const_x)->crldp = tmp_crldp;
    tmp_crldp = NULL;
#ifndef OPENSSL_NO_RFC3779
    sk_IPAddressFamily_pop_free(((X509 *)const_x)->rfc3779_addr, IPAddressFamily_free);
    ((X509 *)const_x)->rfc3779_addr = tmp_rfc3779_addr;
    tmp_rfc3779_addr = NULL;
    ASIdentifiers_free(((X509 *)const_x)->rfc3779_asid);
    ((X509 *)const_x)->rfc3779_asid = tmp_rfc3779_asid;
    tmp_rfc3779_asid = NULL;
#endif
    ((X509 *)const_x)->siginf = tmp_siginf;

#ifdef tsan_st_rel
    tsan_st_rel((TSAN_QUALIFIER int *)&const_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(const_x->lock);
    if (tmp_ex_flags & EXFLAG_INVALID) {
        ERR_raise(ERR_LIB_X509V3, X509V3_R_INVALID_CERTIFICATE);
        goto done;
    }

    ret = 1;

done:
    ASN1_OCTET_STRING_free(tmp_skid);
    AUTHORITY_KEYID_free(tmp_akid);
    sk_GENERAL_NAME_pop_free(tmp_altname, GENERAL_NAME_free);
    NAME_CONSTRAINTS_free(tmp_nc);
    sk_DIST_POINT_pop_free(tmp_crldp, DIST_POINT_free);
#ifndef OPENSSL_NO_RFC3779
    sk_IPAddressFamily_pop_free(tmp_rfc3779_addr, IPAddressFamily_free);
    ASIdentifiers_free(tmp_rfc3779_asid);
#endif
    return ret;
}

/*-
 * 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) != 0) {
        /* If basicConstraints says not a CA then say so */
        return (x->ex_flags & EXFLAG_CA) != 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) != 0)
            return 4;
        /* Older certificates could have Netscape-specific CA types */
        else if ((x->ex_flags & EXFLAG_NSCERT) != 0
            && (x->ex_nscert & NS_ANY_CA) != 0)
            return 5;
        /* Can this still be regarded a CA certificate?  I doubt it. */
        return 0;
    }
}

void X509_set_proxy_flag(X509 *x)
{
    if (CRYPTO_THREAD_write_lock(x->lock)) {
        x->ex_flags |= EXFLAG_PROXY;
        CRYPTO_THREAD_unlock(x->lock);
    }
}

void X509_set_proxy_pathlen(X509 *x, long l)
{
    x->ex_pcpathlen = l;
}

int X509_check_ca(const X509 *x)
{
    /* Note 0 normally means "not a CA" - but in this case means error. */
    if (!ossl_x509v3_cache_extensions(x))
        return 0;

    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 = check_ca(x);

    if (ca_ret == 0)
        return 0;
    /* Check nsCertType if present */
    return ca_ret != 5 || (x->ex_nscert & NS_SSL_CA) != 0;
}

static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    if (xku_reject(x, XKU_SSL_CLIENT))
        return 0;
    if (non_leaf)
        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 non_leaf)
{
    if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
        return 0;
    if (non_leaf)
        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 non_leaf)
{
    int ret = check_purpose_ssl_server(xp, x, non_leaf);

    if (!ret || non_leaf)
        return ret;
    /* We need to encipher or Netscape complains */
    return ku_reject(x, KU_KEY_ENCIPHERMENT) ? 0 : ret;
}

/* common S/MIME client checks */
static int purpose_smime(const X509 *x, int non_leaf)
{
    if (xku_reject(x, XKU_SMIME))
        return 0;
    if (non_leaf) {
        int ca_ret = check_ca(x);

        if (ca_ret == 0)
            return 0;
        /* Check nsCertType if present */
        if (ca_ret != 5 || (x->ex_nscert & NS_SMIME_CA) != 0)
            return ca_ret;
        else
            return 0;
    }
    if ((x->ex_flags & EXFLAG_NSCERT) != 0) {
        if ((x->ex_nscert & NS_SMIME) != 0)
            return 1;
        /* Workaround for some buggy certificates */
        return (x->ex_nscert & NS_SSL_CLIENT) != 0 ? 2 : 0;
    }
    return 1;
}

static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    int ret = purpose_smime(x, non_leaf);

    if (!ret || non_leaf)
        return ret;
    return ku_reject(x, KU_DIGITAL_SIGNATURE | KU_NON_REPUDIATION) ? 0 : ret;
}

static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    int ret = purpose_smime(x, non_leaf);

    if (!ret || non_leaf)
        return ret;
    return ku_reject(x, KU_KEY_ENCIPHERMENT) ? 0 : ret;
}

static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    if (non_leaf) {
        int ca_ret = check_ca(x);

        return ca_ret == 2 ? 0 : ca_ret;
    }
    return !ku_reject(x, KU_CRL_SIGN);
}

/*
 * 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 check_purpose_ocsp_helper(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    /*
     * Must be a valid CA.  Should we really support the "I don't know" value
     * (2)?
     */
    if (non_leaf)
        return check_ca(x);
    /* Leaf certificate is checked in OCSP_basic_verify() */
    return 1;
}

static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    int i_ext;

    /*
     * If non_leaf is true we must check if this is a valid CA certificate.
     * The extra requirements by the CA/Browser Forum are not checked.
     */
    if (non_leaf)
        return check_ca(x);

    /*
     * Key Usage is checked according to RFC 5280 and
     * Extended Key Usage attributes is checked according to RFC 3161.
     * The extra (and somewhat conflicting) CA/Browser Forum
     * Baseline Requirements for the Issuance and Management of
     * Publicly‐Trusted Code Signing Certificates, Version 3.0.0,
     * Section 7.1.2.3: Code signing and Timestamp Certificate are not checked.
     */
    /*
     * 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) != 0
        && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) || !(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
        return 0;

    /* Only timestamp key usage is permitted and it's required. */
    if ((x->ex_flags & EXFLAG_XKUSAGE) == 0 || 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_get_critical(X509_get_ext((X509 *)x, i_ext)))
        return 0;
    return 1;
}

static int check_purpose_code_sign(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    int i_ext;

    /*
     * If non_leaf is true we must check if this is a valid CA certificate.
     * The extra requirements by the CA/Browser Forum are not checked.
     */
    if (non_leaf)
        return check_ca(x);

    /*
     * Check the key usage and extended key usage fields:
     *
     * Reference: CA/Browser Forum,
     * Baseline Requirements for the Issuance and Management of
     * Publicly‐Trusted Code Signing Certificates, Version 3.0.0,
     * Section 7.1.2.3: Code signing and Timestamp Certificate
     *
     * Checking covers Key Usage and Extended Key Usage attributes.
     * The certificatePolicies, cRLDistributionPoints (CDP), and
     * authorityInformationAccess (AIA) extensions are so far not checked.
     */
    /* Key Usage */
    if ((x->ex_flags & EXFLAG_KUSAGE) == 0)
        return 0;
    if ((x->ex_kusage & KU_DIGITAL_SIGNATURE) == 0)
        return 0;
    if ((x->ex_kusage & (KU_KEY_CERT_SIGN | KU_CRL_SIGN)) != 0)
        return 0;

    /* Key Usage MUST be critical */
    i_ext = X509_get_ext_by_NID(x, NID_key_usage, -1);
    if (i_ext < 0)
        return 0;
    if (i_ext >= 0) {
        const X509_EXTENSION *ext = X509_get_ext((X509 *)x, i_ext);
        if (!X509_EXTENSION_get_critical(ext))
            return 0;
    }

    /* Extended Key Usage */
    if ((x->ex_flags & EXFLAG_XKUSAGE) == 0)
        return 0;
    if ((x->ex_xkusage & XKU_CODE_SIGN) == 0)
        return 0;
    if ((x->ex_xkusage & (XKU_ANYEKU | XKU_SSL_SERVER)) != 0)
        return 0;

    return 1;
}

static int no_check_purpose(const X509_PURPOSE *xp, const X509 *x,
    int non_leaf)
{
    return 1;
}

static int check_name_constraints(const NAME_CONSTRAINTS *nc)
{
    GENERAL_SUBTREE *sub;
    int ret = 1;

    if (nc == NULL)
        goto done;

    for (int i = 0; nc->permittedSubtrees != NULL
        && i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees);
        i++) {
        sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);
        if (sub->base->type == GEN_OTHERNAME
            && OBJ_obj2nid(sub->base->d.otherName->type_id)
                == NID_id_on_SmtpUTF8Mailbox) {
            /* RFC 9598 prohibits GEN_OTHERNAME email constraints */
            ERR_raise(ERR_LIB_X509V3, X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE);
            ret = 0;
            goto done;
        }
    }
    for (int i = 0; nc->excludedSubtrees != NULL
        && i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees);
        i++) {
        sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);
        if (sub->base->type == GEN_OTHERNAME
            && OBJ_obj2nid(sub->base->d.otherName->type_id)
                == NID_id_on_SmtpUTF8Mailbox) {
            /* RFC 9598 prohibits GEN_OTHERNAME email constraints */
            ERR_raise(ERR_LIB_X509V3, X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE);
            ret = 0;
            goto done;
        }
    }

done:
    return ret;
}

/*-
 * Various checks to see if one certificate potentially 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. issuer_name(subject) == subject_name(issuer)
 * 2. If akid(subject) exists, it matches the respective issuer fields.
 * 3. subject signature algorithm == issuer public key algorithm
 * 4. If key_usage(issuer) exists, it allows for signing subject.
 * Note that this does not include actually checking the signature.
 * Returns 0 for OK, or positive for reason for mismatch
 * where reason codes match those for X509_verify_cert().
 */
int X509_check_issued(const X509 *issuer, const X509 *subject)
{
    int ret;

    if ((ret = ossl_x509_likely_issued(issuer, subject)) != X509_V_OK)
        return ret;
    return ossl_x509_signing_allowed(issuer, subject);
}

/*
 * Do the checks 1., 2., and 3. as described above for X509_check_issued().
 * These are very similar to a section of ossl_x509v3_cache_extensions().
 * If |issuer| equals |subject| (such that self-signature should be checked),
 * use the EXFLAG_SS result of ossl_x509v3_cache_extensions().
 */
int ossl_x509_likely_issued(const X509 *issuer, const X509 *subject)
{
    int ret;

    if (X509_NAME_cmp(X509_get_subject_name(issuer),
            X509_get_issuer_name(subject))
        != 0)
        return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;

    /* set issuer->skid, subject->akid, and subject->ex_flags */
    if (!ossl_x509v3_cache_extensions(issuer)
        || !ossl_x509v3_cache_extensions(subject))
        return X509_V_ERR_UNSPECIFIED;

    if (issuer == subject
        || (X509_NAME_cmp(X509_get_issuer_name(issuer), X509_get_issuer_name(subject)) == 0
            && ASN1_INTEGER_cmp(X509_get0_serialNumber(issuer), X509_get0_serialNumber(subject)) == 0))
        /*
         * At this point, we can assume that issuer and subject
         * are semantically the same cert because they are identical
         * or at least have the same issuer and serial number,
         * which (for any sane cert issuer) implies equality of the two certs.
         * In this case, for consistency with chain building and validation,
         * we make our issuance judgment depend on the presence of EXFLAG_SS.
         * This is used for corrected chain building in the corner case of
         * a self-issued but not actually self-signed trust anchor cert
         * without subject and issuer key identifiers (i.e., no SKID and AKID).
         */
        return (issuer->ex_flags & EXFLAG_SS) != 0
            ? X509_V_OK
            : X509_V_ERR_CERT_SIGNATURE_FAILURE;

    ret = X509_check_akid(issuer, subject->akid);
    if (ret != X509_V_OK)
        return ret;

    /* Check if the subject signature alg matches the issuer's PUBKEY alg */
    return check_sig_alg_match(X509_get0_pubkey(issuer), subject);
}

/*-
 * Check if certificate I<issuer> is allowed to issue certificate I<subject>
 * according to the B<keyUsage> field of I<issuer> if present
 * depending on any proxyCertInfo extension of I<subject>.
 * Returns 0 for OK, or positive for reason for rejection
 * where reason codes match those for X509_verify_cert().
 */
int ossl_x509_signing_allowed(const X509 *issuer, const X509 *subject)
{
    if ((subject->ex_flags & EXFLAG_PROXY) != 0) {
        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;
}

/*
 * check if all sub-fields of the authority key identifier information akid,
 * as far as present, match the respective subjectKeyIdentifier extension (if
 * present in issuer), serialNumber field, and issuer fields of issuer.
 * returns X509_V_OK also if akid is NULL because this means no restriction.
 */
int X509_check_akid(const X509 *issuer, const AUTHORITY_KEYID *akid)
{
    if (akid == NULL)
        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_get0_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 = akid->issuer;
        GENERAL_NAME *gen;
        X509_NAME *nm = NULL;
        int i;

        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 != NULL && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)) != 0)
            return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
    }
    return X509_V_OK;
}

uint32_t X509_get_extension_flags(const X509 *x)
{
    /* Call for side-effect of computing hash and caching extensions */
    X509_check_purpose(x, -1, 0);
    return x->ex_flags;
}

uint32_t X509_get_key_usage(const X509 *x)
{
    /* Call for side-effect of computing hash and caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1)
        return 0;
    return (x->ex_flags & EXFLAG_KUSAGE) != 0 ? x->ex_kusage : UINT32_MAX;
}

uint32_t X509_get_extended_key_usage(const X509 *x)
{
    /* Call for side-effect of computing hash and caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1)
        return 0;
    return (x->ex_flags & EXFLAG_XKUSAGE) != 0 ? x->ex_xkusage : UINT32_MAX;
}

const ASN1_OCTET_STRING *X509_get0_subject_key_id(const X509 *x)
{
    /* Call for side-effect of computing hash and caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1)
        return NULL;
    return x->skid;
}

const ASN1_OCTET_STRING *X509_get0_authority_key_id(const X509 *x)
{
    /* Call for side-effect of computing hash and caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1)
        return NULL;
    return (x->akid != NULL ? x->akid->keyid : NULL);
}

const GENERAL_NAMES *X509_get0_authority_issuer(const X509 *x)
{
    /* Call for side-effect of computing hash and caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1)
        return NULL;
    return (x->akid != NULL ? x->akid->issuer : NULL);
}

const ASN1_INTEGER *X509_get0_authority_serial(const X509 *x)
{
    /* Call for side-effect of computing hash and caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1)
        return NULL;
    return (x->akid != NULL ? x->akid->serial : NULL);
}

long X509_get_pathlen(const X509 *x)
{
    /* Called for side effect of caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1
        || (x->ex_flags & EXFLAG_BCONS) == 0)
        return -1;
    return x->ex_pathlen;
}

long X509_get_proxy_pathlen(const X509 *x)
{
    /* Called for side effect of caching extensions */
    if (X509_check_purpose(x, -1, 0) != 1
        || (x->ex_flags & EXFLAG_PROXY) == 0)
        return -1;
    return x->ex_pcpathlen;
}

Coverage Report

Created: 2026-10-28 06:28