sslutils.c

业界著名的tomcat服务器的最新6.0的源代码。

RSA *SSL_callback_tmp_RSA(SSL *ssl, int export, int keylen)
{
    int idx;

    /* doesn't matter if export flag is on,
     * we won't be asked for keylen > 512 in that case.
     * if we are asked for a keylen > 1024, it is too expensive
     * to generate on the fly.
     */

    switch (keylen) {
        case 512:
            idx = SSL_TMP_KEY_RSA_512;
        break;
        case 2048:
            idx = SSL_TMP_KEY_RSA_2048;
            if (SSL_temp_keys[idx] == NULL)
                idx = SSL_TMP_KEY_RSA_1024;
        break;
        case 4096:
            idx = SSL_TMP_KEY_RSA_4096;
            if (SSL_temp_keys[idx] == NULL)
                idx = SSL_TMP_KEY_RSA_2048;
        break;
        case 1024:
        default:
            idx = SSL_TMP_KEY_RSA_1024;
        break;
    }
    return (RSA *)SSL_temp_keys[idx];
}

/*
 * Hand out the already generated DH parameters...
 */
DH *SSL_callback_tmp_DH(SSL *ssl, int export, int keylen)
{
    int idx;
    switch (keylen) {
        case 512:
            idx = SSL_TMP_KEY_DH_512;
        break;
        case 2048:
            idx = SSL_TMP_KEY_DH_2048;
        break;
        case 4096:
            idx = SSL_TMP_KEY_DH_4096;
        break;
        case 1024:
        default:
            idx = SSL_TMP_KEY_DH_1024;
        break;
    }
    return (DH *)SSL_temp_keys[idx];
}

void SSL_vhost_algo_id(const unsigned char *vhost_id, unsigned char *md, int algo)
{
    MD5_CTX c;
    MD5_Init(&c);
    MD5_Update(&c, vhost_id, MD5_DIGEST_LENGTH);
    switch (algo) {
        case SSL_ALGO_UNKNOWN:
            MD5_Update(&c, "UNKNOWN", 7);
        break;
        case SSL_ALGO_RSA:
            MD5_Update(&c, "RSA", 3);
        break;
        case SSL_ALGO_DSA:
            MD5_Update(&c, "DSA", 3);
        break;
    }
    MD5_Final(md, &c);
}

/*
 * Read a file that optionally contains the server certificate in PEM
 * format, possibly followed by a sequence of CA certificates that
 * should be sent to the peer in the SSL Certificate message.
 */
int SSL_CTX_use_certificate_chain(SSL_CTX *ctx, const char *file,
                                  int skipfirst)
{
    BIO *bio;
    X509 *x509;
    unsigned long err;
    int n;
    STACK *extra_certs;

    if ((bio = BIO_new(BIO_s_file_internal())) == NULL)
        return -1;
    if (BIO_read_filename(bio, file) <= 0) {
        BIO_free(bio);
        return -1;
    }
    /* optionally skip a leading server certificate */
    if (skipfirst) {
        if ((x509 = PEM_read_bio_X509(bio, NULL, NULL, NULL)) == NULL) {
            BIO_free(bio);
            return -1;
        }
        X509_free(x509);
    }
    /* free a perhaps already configured extra chain */
    extra_certs = SSL_CTX_get_extra_certs(ctx);
    if (extra_certs != NULL) {
        sk_X509_pop_free((STACK_OF(X509) *)extra_certs, X509_free);
        SSL_CTX_set_extra_certs(ctx,NULL);
    }
    /* create new extra chain by loading the certs */
    n = 0;
    while ((x509 = PEM_read_bio_X509(bio, NULL, NULL, NULL)) != NULL) {
        if (!SSL_CTX_add_extra_chain_cert(ctx, x509)) {
            X509_free(x509);
            BIO_free(bio);
            return -1;
        }
        n++;
    }
    /* Make sure that only the error is just an EOF */
    if ((err = ERR_peek_error()) > 0) {
        if (!(   ERR_GET_LIB(err) == ERR_LIB_PEM
              && ERR_GET_REASON(err) == PEM_R_NO_START_LINE)) {
            BIO_free(bio);
            return -1;
        }
        while (ERR_get_error() > 0) ;
    }
    BIO_free(bio);
    return n;
}

static int ssl_X509_STORE_lookup(X509_STORE *store, int yype,
                                 X509_NAME *name, X509_OBJECT *obj)
{
    X509_STORE_CTX ctx;
    int rc;

    X509_STORE_CTX_init(&ctx, store, NULL, NULL);
    rc = X509_STORE_get_by_subject(&ctx, yype, name, obj);
    X509_STORE_CTX_cleanup(&ctx);
    return rc;
}

static int ssl_verify_CRL(int ok, X509_STORE_CTX *ctx, tcn_ssl_conn_t *con)
{
    X509_OBJECT obj;
    X509_NAME *subject, *issuer;
    X509 *cert;
    X509_CRL *crl;
    EVP_PKEY *pubkey;
    int i, n, rc;

    /*
     * Determine certificate ingredients in advance
     */
    cert    = X509_STORE_CTX_get_current_cert(ctx);
    subject = X509_get_subject_name(cert);
    issuer  = X509_get_issuer_name(cert);

    /*
     * OpenSSL provides the general mechanism to deal with CRLs but does not
     * use them automatically when verifying certificates, so we do it
     * explicitly here. We will check the CRL for the currently checked
     * certificate, if there is such a CRL in the store.
     *
     * We come through this procedure for each certificate in the certificate
     * chain, starting with the root-CA's certificate. At each step we've to
     * both verify the signature on the CRL (to make sure it's a valid CRL)
     * and it's revocation list (to make sure the current certificate isn't
     * revoked).  But because to check the signature on the CRL we need the
     * public key of the issuing CA certificate (which was already processed
     * one round before), we've a little problem. But we can both solve it and
     * at the same time optimize the processing by using the following
     * verification scheme (idea and code snippets borrowed from the GLOBUS
     * project):
     *
     * 1. We'll check the signature of a CRL in each step when we find a CRL
     *    through the _subject_ name of the current certificate. This CRL
     *    itself will be needed the first time in the next round, of course.
     *    But we do the signature processing one round before this where the
     *    public key of the CA is available.
     *
     * 2. We'll check the revocation list of a CRL in each step when
     *    we find a CRL through the _issuer_ name of the current certificate.
     *    This CRLs signature was then already verified one round before.
     *
     * This verification scheme allows a CA to revoke its own certificate as
     * well, of course.
     */

    /*
     * Try to retrieve a CRL corresponding to the _subject_ of
     * the current certificate in order to verify it's integrity.
     */
    memset((char *)&obj, 0, sizeof(obj));
    rc = ssl_X509_STORE_lookup(con->ctx->crl,
                               X509_LU_CRL, subject, &obj);
    crl = obj.data.crl;

    if ((rc > 0) && crl) {
        /*
         * Log information about CRL
         * (A little bit complicated because of ASN.1 and BIOs...)
         */
        /*
         * Verify the signature on this CRL
         */
        pubkey = X509_get_pubkey(cert);
        rc = X509_CRL_verify(crl, pubkey);
        /* Only refcounted in OpenSSL */
        if (pubkey)
            EVP_PKEY_free(pubkey);
        if (rc <= 0) {
            /* TODO: Log Invalid signature on CRL */
            X509_STORE_CTX_set_error(ctx, X509_V_ERR_CRL_SIGNATURE_FAILURE);
            X509_OBJECT_free_contents(&obj);
            return 0;
        }

        /*
         * Check date of CRL to make sure it's not expired
         */
        i = X509_cmp_current_time(X509_CRL_get_nextUpdate(crl));

        if (i == 0) {
            /* TODO: Log Found CRL has invalid nextUpdate field */

            X509_STORE_CTX_set_error(ctx,
                                     X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD);
            X509_OBJECT_free_contents(&obj);
            return 0;
        }

        if (i < 0) {
            /* TODO: Log Found CRL is expired */
            X509_STORE_CTX_set_error(ctx, X509_V_ERR_CRL_HAS_EXPIRED);
            X509_OBJECT_free_contents(&obj);

            return 0;
        }

        X509_OBJECT_free_contents(&obj);
    }

    /*
     * Try to retrieve a CRL corresponding to the _issuer_ of
     * the current certificate in order to check for revocation.
     */
    memset((char *)&obj, 0, sizeof(obj));
    rc = ssl_X509_STORE_lookup(con->ctx->crl,
                               X509_LU_CRL, issuer, &obj);

    crl = obj.data.crl;
    if ((rc > 0) && crl) {
        /*
         * Check if the current certificate is revoked by this CRL
         */
        n = sk_X509_REVOKED_num(X509_CRL_get_REVOKED(crl));

        for (i = 0; i < n; i++) {
            X509_REVOKED *revoked =
                sk_X509_REVOKED_value(X509_CRL_get_REVOKED(crl), i);

            ASN1_INTEGER *sn = revoked->serialNumber;

            if (!ASN1_INTEGER_cmp(sn, X509_get_serialNumber(cert))) {
                X509_STORE_CTX_set_error(ctx, X509_V_ERR_CERT_REVOKED);
                X509_OBJECT_free_contents(&obj);

                return 0;
            }
        }

        X509_OBJECT_free_contents(&obj);
    }

    return ok;
}

/*
 * This OpenSSL callback function is called when OpenSSL
 * does client authentication and verifies the certificate chain.
 */
int SSL_callback_SSL_verify(int ok, X509_STORE_CTX *ctx)
{
   /* Get Apache context back through OpenSSL context */
    SSL *ssl = X509_STORE_CTX_get_ex_data(ctx,
                                          SSL_get_ex_data_X509_STORE_CTX_idx());
    tcn_ssl_conn_t *con = (tcn_ssl_conn_t *)SSL_get_app_data(ssl);
    /* Get verify ingredients */
    int errnum   = X509_STORE_CTX_get_error(ctx);
    int errdepth = X509_STORE_CTX_get_error_depth(ctx);
    int verify   = con->ctx->verify_mode;
    int depth    = con->ctx->verify_depth;

    if (verify == SSL_CVERIFY_UNSET ||
        verify == SSL_CVERIFY_NONE)
        return 1;

    if (SSL_VERIFY_ERROR_IS_OPTIONAL(errnum) &&
        (verify == SSL_CVERIFY_OPTIONAL_NO_CA)) {
        ok = 1;
        SSL_set_verify_result(ssl, X509_V_OK);
    }
    /*
     * Additionally perform CRL-based revocation checks
     */
    if (ok && con->ctx->crl) {
        if (!(ok = ssl_verify_CRL(ok, ctx, con))) {
            errnum = X509_STORE_CTX_get_error(ctx);
            /* TODO: Log something */
        }
    }
    /*
     * If we already know it's not ok, log the real reason
     */
    if (!ok) {
        /* TODO: Some logging
         * Certificate Verification: Error
         */
        if (con->peer) {
            X509_free(con->peer);
            con->peer = NULL;
        }
    }
    if (errdepth > depth) {
        /* TODO: Some logging
         * Certificate Verification: Certificate Chain too long
         */
        ok = 0;
    }
    return ok;
}

#endif