Commit message: Correctly compare EdiPartyName in GENERAL_NAME_cmp()

If a GENERAL_NAME field contained EdiPartyName data then it was
incorrectly being handled as type "other". This could lead to a
segmentation fault.

Many thanks to David Benjamin from Google for reporting this issue.

CVE-2020-1971

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
CVE: CVE-2020-1971
CWE: CWE-476
Vulnerability description: The X.509 GeneralName type is a generic type for representing different types of names. One of those name types is known as EDIPartyName. OpenSSL provides a function GENERAL_NAME_cmp which compares different instances of a GENERAL_NAME to see if they are equal or not. This function behaves incorrectly when both GENERAL_NAMEs contain an EDIPARTYNAME. A NULL pointer dereference and a crash may occur leading to a possible denial of service attack. OpenSSL itself uses the GENERAL_NAME_cmp function for two purposes: 1) Comparing CRL distribution point names between an available CRL and a CRL distribution point embedded in an X509 certificate 2) When verifying that a timestamp response token signer matches the timestamp authority name (exposed via the API functions TS_RESP_verify_response and TS_RESP_verify_token) If an attacker can control both items being compared then that attacker could trigger a crash. For example if the attacker can trick a client or server into checking a malicious certificate against a malicious CRL then this may occur. Note that some applications automatically download CRLs based on a URL embedded in a certificate. This checking happens prior to the signatures on the certificate and CRL being verified. OpenSSL's s_server, s_client and verify tools have support for the "-crl_download" option which implements automatic CRL downloading and this attack has been demonstrated to work against those tools. Note that an unrelated bug means that affected versions of OpenSSL cannot parse or construct correct encodings of EDIPARTYNAME. However it is possible to construct a malformed EDIPARTYNAME that OpenSSL's parser will accept and hence trigger this attack. All OpenSSL 1.1.1 and 1.0.2 versions are affected by this issue. Other OpenSSL releases are out of support and have not been checked. Fixed in OpenSSL 1.1.1i (Affected 1.1.1-1.1.1h). Fixed in OpenSSL 1.0.2x (Affected 1.0.2-1.0.2w).

Project: openssl

int GENERAL_NAME_cmp(GENERAL_NAME *a, GENERAL_NAME *b)
{
    int result = -1;

    if (!a || !b || a->type != b->type)
        return -1;
    switch (a->type) {
    case GEN_X400:
        result = ASN1_TYPE_cmp(a->d.x400Address, b->d.x400Address);
        break;

    case GEN_EDIPARTY:
        result = edipartyname_cmp(a->d.ediPartyName, b->d.ediPartyName);
        break;

    case GEN_OTHERNAME:
        result = OTHERNAME_cmp(a->d.otherName, b->d.otherName);
        break;

    case GEN_EMAIL:
    case GEN_DNS:
    case GEN_URI:
        result = ASN1_STRING_cmp(a->d.ia5, b->d.ia5);
        break;

    case GEN_DIRNAME:
        result = X509_NAME_cmp(a->d.dirn, b->d.dirn);
        break;

    case GEN_IPADD:
        result = ASN1_OCTET_STRING_cmp(a->d.ip, b->d.ip);
        break;

    case GEN_RID:
        result = OBJ_cmp(a->d.rid, b->d.rid);
        break;
    }
    return result;
}

Project: openssl

int GENERAL_NAME_get0_otherName(const GENERAL_NAME *gen,
                                ASN1_OBJECT **poid, ASN1_TYPE **pvalue)
{
    if (gen->type != GEN_OTHERNAME)
        return 0;
    if (poid)
        *poid = gen->d.otherName->type_id;
    if (pvalue)
        *pvalue = gen->d.otherName->value;
    return 1;
}

Project: openssl

void GENERAL_NAME_set0_value(GENERAL_NAME *a, int type, void *value)
{
    switch (type) {
    case GEN_X400:
        a->d.x400Address = value;
        break;

    case GEN_EDIPARTY:
        a->d.ediPartyName = value;
        break;

    case GEN_OTHERNAME:
        a->d.otherName = value;
        break;

    case GEN_EMAIL:
    case GEN_DNS:
    case GEN_URI:
        a->d.ia5 = value;
        break;

    case GEN_DIRNAME:
        a->d.dirn = value;
        break;

    case GEN_IPADD:
        a->d.ip = value;
        break;

    case GEN_RID:
        a->d.rid = value;
        break;
    }
    a->type = type;
}

Project: openssl

int OTHERNAME_cmp(OTHERNAME *a, OTHERNAME *b)
{
    int result = -1;

    if (!a || !b)
        return -1;
    /* Check their type first. */
    if ((result = OBJ_cmp(a->type_id, b->type_id)) != 0)
        return result;
    /* Check the value. */
    result = ASN1_TYPE_cmp(a->value, b->value);
    return result;
}

Project: openssl

int GENERAL_NAME_set0_othername(GENERAL_NAME *gen,
                                ASN1_OBJECT *oid, ASN1_TYPE *value)
{
    OTHERNAME *oth;
    oth = OTHERNAME_new();
    if (oth == NULL)
        return 0;
    ASN1_TYPE_free(oth->value);
    oth->type_id = oid;
    oth->value = value;
    GENERAL_NAME_set0_value(gen, GEN_OTHERNAME, oth);
    return 1;
}

Project: openssl

void *GENERAL_NAME_get0_value(const GENERAL_NAME *a, int *ptype)
{
    if (ptype)
        *ptype = a->type;
    switch (a->type) {
    case GEN_X400:
        return a->d.x400Address;

    case GEN_EDIPARTY:
        return a->d.ediPartyName;

    case GEN_OTHERNAME:
        return a->d.otherName;

    case GEN_EMAIL:
    case GEN_DNS:
    case GEN_URI:
        return a->d.ia5;

    case GEN_DIRNAME:
        return a->d.dirn;

    case GEN_IPADD:
        return a->d.ip;

    case GEN_RID:
        return a->d.rid;

    default:
        return NULL;
    }
}

Project: openssl

static int edipartyname_cmp(const EDIPARTYNAME *a, const EDIPARTYNAME *b)
{
    int res;

    if (a == NULL || b == NULL) {
        /*
         * Shouldn't be possible in a valid GENERAL_NAME, but we handle it
         * anyway. OTHERNAME_cmp treats NULL != NULL so we do the same here
         */
        return -1;
    }
    if (a->nameAssigner == NULL && b->nameAssigner != NULL)
        return -1;
    if (a->nameAssigner != NULL && b->nameAssigner == NULL)
        return 1;
    /* If we get here then both have nameAssigner set, or both unset */
    if (a->nameAssigner != NULL) {
        res = ASN1_STRING_cmp(a->nameAssigner, b->nameAssigner);
        if (res != 0)
            return res;
    }
    /*
     * partyName is required, so these should never be NULL. We treat it in
     * the same way as the a == NULL || b == NULL case above
     */
    if (a->partyName == NULL || b->partyName == NULL)
        return -1;

    return ASN1_STRING_cmp(a->partyName, b->partyName);
}

Project: openssl

GENERAL_NAME *GENERAL_NAME_dup(const GENERAL_NAME *a)
{
    return (GENERAL_NAME *)ASN1_dup((i2d_of_void *)i2d_GENERAL_NAME,
                                    (d2i_of_void *)d2i_GENERAL_NAME,
                                    (char *)a);
}