Security framework.

Security callback: selects which parameters are permitted including
sensible defaults based on bits of security.

The "parameters" which can be selected include: ciphersuites,
curves, key sizes, certificate signature algorithms, supported
signature algorithms, DH parameters, SSL/TLS version, session tickets
and compression.

In some cases prohibiting the use of a parameters will mean they are
not advertised to the peer: for example cipher suites and ECC curves.
In other cases it will abort the handshake: e.g DH parameters or the
peer key size.

Documentation to follow...

ssl/s23_clnt.c

@@ -259,10 +259,13 @@ static int ssl23_no_ssl2_ciphers(SSL *s)
 	SSL_CIPHER *cipher;
 	STACK_OF(SSL_CIPHER) *ciphers;
 	int i;
+	ssl_set_client_disabled(s);
 	ciphers = SSL_get_ciphers(s);
 	for (i = 0; i < sk_SSL_CIPHER_num(ciphers); i++)
 		{
 		cipher = sk_SSL_CIPHER_value(ciphers, i);
+		if (ssl_cipher_disabled(s, cipher, SSL_SECOP_CIPHER_SUPPORTED))
+			continue;
 		if (cipher->algorithm_ssl == SSL_SSLV2)
 			return 0;
 		}
@@ -309,6 +312,8 @@ static int ssl23_client_hello(SSL *s)
 
 	ssl2_compat = (options & SSL_OP_NO_SSLv2) ? 0 : 1;
 
+	if (ssl2_compat && !ssl_security(s, SSL_SECOP_SSL2_COMPAT, 0, 0, NULL))
+		ssl2_compat = 0;
 	if (ssl2_compat && ssl23_no_ssl2_ciphers(s))
 		ssl2_compat = 0;
 
@@ -533,8 +538,7 @@ static int ssl23_client_hello(SSL *s)
 #ifdef OPENSSL_NO_COMP
 			*(p++)=1;
 #else
-			if ((s->options & SSL_OP_NO_COMPRESSION)
-						|| !s->ctx->comp_methods)
+			if (!ssl_allow_compression(s) || !s->ctx->comp_methods)
 				j=0;
 			else
 				j=sk_SSL_COMP_num(s->ctx->comp_methods);
@@ -750,6 +754,12 @@ static int ssl23_get_server_hello(SSL *s)
 			goto err;
 			}
 
+		if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL))
+			{
+			SSLerr(SSL_F_SSL23_GET_SERVER_HELLO,SSL_R_VERSION_TOO_LOW);
+			goto err;
+			}
+
 		if (p[0] == SSL3_RT_ALERT && p[5] != SSL3_AL_WARNING)
 			{
 			/* fatal alert */

ssl/s23_srvr.c

@@ -441,6 +441,12 @@ int ssl23_get_client_hello(SSL *s)
 		}
 #endif
 
+	if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL))
+		{
+		SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,SSL_R_VERSION_TOO_LOW);
+		goto err;
+		}
+
 	if (s->state == SSL23_ST_SR_CLNT_HELLO_B)
 		{
 		/* we have SSLv3/TLSv1 in an SSLv2 header

ssl/s2_clnt.c

@@ -1056,6 +1056,12 @@ int ssl2_set_certificate(SSL *s, int type, int len, const unsigned char *data)
 	ERR_clear_error(); /* but we keep s->verify_result */
 	s->session->verify_result = s->verify_result;
 
+	if (i > 1)
+		{
+		SSLerr(SSL_F_SSL2_SET_CERTIFICATE, i);
+		goto err;
+		}
+
 	/* server's cert for this session */
 	sc=ssl_sess_cert_new();
 	if (sc == NULL)

ssl/s2_srvr.c

@@ -1053,6 +1053,12 @@ static int request_certificate(SSL *s)
 
 	i=ssl_verify_cert_chain(s,sk);
 
+	if (i > 1)
+		{
+		SSLerr(SSL_F_REQUEST_CERTIFICATE, i);
+		goto msg_end;
+		}
+
 	if (i > 0)	/* we like the packet, now check the chksum */
 		{
 		EVP_MD_CTX ctx;

ssl/s3_both.c

@@ -695,7 +695,7 @@ int ssl3_setup_read_buffer(SSL *s)
 			len += SSL3_RT_MAX_EXTRA;
 			}
 #ifndef OPENSSL_NO_COMP
-		if (!(s->options & SSL_OP_NO_COMPRESSION))
+		if (ssl_allow_compression(s))
 			len += SSL3_RT_MAX_COMPRESSED_OVERHEAD;
 #endif
 		if ((p=freelist_extract(s->ctx, 1, len)) == NULL)
@@ -732,7 +732,7 @@ int ssl3_setup_write_buffer(SSL *s)
 			+ SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD
 			+ headerlen + align;
 #ifndef OPENSSL_NO_COMP
-		if (!(s->options & SSL_OP_NO_COMPRESSION))
+		if (ssl_allow_compression(s))
 			len += SSL3_RT_MAX_COMPRESSED_OVERHEAD;
 #endif
 		if (!(s->options & SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS))
@@ -782,3 +782,10 @@ int ssl3_release_read_buffer(SSL *s)
 	return 1;
 	}
 
+int ssl_allow_compression(SSL *s)
+	{
+	if (s->options & SSL_OP_NO_COMPRESSION)
+		return 0;
+	return ssl_security(s, SSL_SECOP_COMPRESSION, 0, 0, NULL);
+	}
+

ssl/s3_clnt.c

@@ -240,6 +240,13 @@ int ssl3_connect(SSL *s)
 				ret = -1;
 				goto end;
 				}
+
+			if (!ssl_security(s, SSL_SECOP_VERSION, 0,
+							s->version, NULL))
+				{
+				SSLerr(SSL_F_SSL3_CONNECT, SSL_R_VERSION_TOO_LOW);
+				return -1;
+				}
 
 			/* s->version=SSL3_VERSION; */
 			s->type=SSL_ST_CONNECT;
@@ -871,8 +878,7 @@ int ssl3_client_hello(SSL *s)
 		*(p++)=1;
 #else
 
-		if ((s->options & SSL_OP_NO_COMPRESSION)
-					|| !s->ctx->comp_methods)
+		if (!ssl_allow_compression(s) || !s->ctx->comp_methods)
 			j=0;
 		else
 			j=sk_SSL_COMP_num(s->ctx->comp_methods);
@@ -1079,7 +1085,7 @@ int ssl3_get_server_hello(SSL *s)
 	/* If it is a disabled cipher we didn't send it in client hello,
 	 * so return an error.
 	 */
-	if (ssl_cipher_disabled(s, c))
+	if (ssl_cipher_disabled(s, c, SSL_SECOP_CIPHER_CHECK))
 		{
 		al=SSL_AD_ILLEGAL_PARAMETER;
 		SSLerr(SSL_F_SSL3_GET_SERVER_HELLO,SSL_R_WRONG_CIPHER_RETURNED);
@@ -1148,7 +1154,7 @@ int ssl3_get_server_hello(SSL *s)
 		}
 	if (j == 0)
 		comp=NULL;
-	else if (s->options & SSL_OP_NO_COMPRESSION)
+	else if (!ssl_allow_compression(s))
 		{
 		al=SSL_AD_ILLEGAL_PARAMETER;
 		SSLerr(SSL_F_SSL3_GET_SERVER_HELLO,SSL_R_COMPRESSION_DISABLED);
@@ -1290,6 +1296,12 @@ int ssl3_get_server_certificate(SSL *s)
 		goto f_err; 
 		}
 	ERR_clear_error(); /* but we keep s->verify_result */
+	if (i > 1)
+		{
+		SSLerr(SSL_F_SSL3_GET_SERVER_CERTIFICATE, i);
+		al = SSL_AD_HANDSHAKE_FAILURE;
+		goto f_err;
+		}
 
 	sc=ssl_sess_cert_new();
 	if (sc == NULL) goto err;
@@ -1709,6 +1721,14 @@ int ssl3_get_key_exchange(SSL *s)
 		p+=i;
 		n-=param_len;
 
+		if (!ssl_security(s, SSL_SECOP_TMP_DH,
+						DH_security_bits(dh), 0, dh))
+			{
+			al=SSL_AD_HANDSHAKE_FAILURE;
+			SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE,SSL_R_DH_KEY_TOO_SMALL);
+			goto f_err;
+			}
+
 #ifndef OPENSSL_NO_RSA
 		if (alg_a & SSL_aRSA)
 			pkey=X509_get_pubkey(s->session->sess_cert->peer_pkeys[SSL_PKEY_RSA_ENC].x509);

ssl/s3_lib.c

@@ -3228,6 +3228,12 @@ long ssl3_ctrl(SSL *s, int cmd, long larg, void *parg)
 				SSLerr(SSL_F_SSL3_CTRL, ERR_R_PASSED_NULL_PARAMETER);
 				return(ret);
 				}
+			if (!ssl_security(s, SSL_SECOP_TMP_DH,
+						DH_security_bits(dh), 0, dh))
+				{
+				SSLerr(SSL_F_SSL3_CTRL, SSL_R_DH_KEY_TOO_SMALL);
+				return(ret);
+				}
 			if ((dh = DHparams_dup(dh)) == NULL)
 				{
 				SSLerr(SSL_F_SSL3_CTRL, ERR_R_DH_LIB);
@@ -3415,17 +3421,17 @@ long ssl3_ctrl(SSL *s, int cmd, long larg, void *parg)
 
 	case SSL_CTRL_CHAIN:
 		if (larg)
-			return ssl_cert_set1_chain(s->cert,
+			return ssl_cert_set1_chain(s, NULL,
 						(STACK_OF (X509) *)parg);
 		else
-			return ssl_cert_set0_chain(s->cert,
+			return ssl_cert_set0_chain(s, NULL,
 						(STACK_OF (X509) *)parg);
 
 	case SSL_CTRL_CHAIN_CERT:
 		if (larg)
-			return ssl_cert_add1_chain_cert(s->cert, (X509 *)parg);
+			return ssl_cert_add1_chain_cert(s, NULL, (X509 *)parg);
 		else
-			return ssl_cert_add0_chain_cert(s->cert, (X509 *)parg);
+			return ssl_cert_add0_chain_cert(s, NULL, (X509 *)parg);
 
 	case SSL_CTRL_GET_CHAIN_CERTS:
 		*(STACK_OF(X509) **)parg = s->cert->key->chain;
@@ -3533,7 +3539,7 @@ long ssl3_ctrl(SSL *s, int cmd, long larg, void *parg)
 		return ssl3_set_req_cert_type(s->cert, parg, larg);
 
 	case SSL_CTRL_BUILD_CERT_CHAIN:
-		return ssl_build_cert_chain(s->cert, s->ctx->cert_store, larg);
+		return ssl_build_cert_chain(s, NULL, larg);
 
 	case SSL_CTRL_SET_VERIFY_CERT_STORE:
 		return ssl_cert_set_cert_store(s->cert, parg, 0, larg);
@@ -3736,6 +3742,12 @@ long ssl3_ctx_ctrl(SSL_CTX *ctx, int cmd, long larg, void *parg)
 		DH *new=NULL,*dh;
 
 		dh=(DH *)parg;
+		if (!ssl_ctx_security(ctx, SSL_SECOP_TMP_DH,
+						DH_security_bits(dh), 0, dh))
+			{
+			SSLerr(SSL_F_SSL3_CTX_CTRL, SSL_R_DH_KEY_TOO_SMALL);
+			return 0;
+			}
 		if ((new=DHparams_dup(dh)) == NULL)
 			{
 			SSLerr(SSL_F_SSL3_CTX_CTRL,ERR_R_DH_LIB);
@@ -3911,7 +3923,7 @@ long ssl3_ctx_ctrl(SSL_CTX *ctx, int cmd, long larg, void *parg)
 		return ssl3_set_req_cert_type(ctx->cert, parg, larg);
 
 	case SSL_CTRL_BUILD_CERT_CHAIN:
-		return ssl_build_cert_chain(ctx->cert, ctx->cert_store, larg);
+		return ssl_build_cert_chain(NULL, ctx, larg);
 
 	case SSL_CTRL_SET_VERIFY_CERT_STORE:
 		return ssl_cert_set_cert_store(ctx->cert, parg, 0, larg);
@@ -3948,17 +3960,17 @@ long ssl3_ctx_ctrl(SSL_CTX *ctx, int cmd, long larg, void *parg)
 
 	case SSL_CTRL_CHAIN:
 		if (larg)
-			return ssl_cert_set1_chain(ctx->cert,
+			return ssl_cert_set1_chain(NULL, ctx,
 						(STACK_OF (X509) *)parg);
 		else
-			return ssl_cert_set0_chain(ctx->cert,
+			return ssl_cert_set0_chain(NULL, ctx,
 						(STACK_OF (X509) *)parg);
 
 	case SSL_CTRL_CHAIN_CERT:
 		if (larg)
-			return ssl_cert_add1_chain_cert(ctx->cert, (X509 *)parg);
+			return ssl_cert_add1_chain_cert(NULL, ctx, (X509 *)parg);
 		else
-			return ssl_cert_add0_chain_cert(ctx->cert, (X509 *)parg);
+			return ssl_cert_add0_chain_cert(NULL, ctx, (X509 *)parg);
 
 	case SSL_CTRL_GET_CHAIN_CERTS:
 		*(STACK_OF(X509) **)parg = ctx->cert->key->chain;
@@ -4203,6 +4215,10 @@ SSL_CIPHER *ssl3_choose_cipher(SSL *s, STACK_OF(SSL_CIPHER) *clnt,
 		ii=sk_SSL_CIPHER_find(allow,c);
 		if (ii >= 0)
 			{
+			/* Check security callback permits this cipher */
+			if (!ssl_security(s, SSL_SECOP_CIPHER_SHARED,
+						c->strength_bits, 0, c))
+				continue;
 #if !defined(OPENSSL_NO_EC) && !defined(OPENSSL_NO_TLSEXT)
 			if ((alg_k & SSL_kECDHE) && (alg_a & SSL_aECDSA) && s->s3->is_probably_safari)
 				{
@@ -4220,43 +4236,19 @@ SSL_CIPHER *ssl3_choose_cipher(SSL *s, STACK_OF(SSL_CIPHER) *clnt,
 int ssl3_get_req_cert_type(SSL *s, unsigned char *p)
 	{
 	int ret=0;
-	const unsigned char *sig;
-	size_t i, siglen;
-	int have_rsa_sign = 0, have_dsa_sign = 0;
-#ifndef OPENSSL_NO_ECDSA
-	int have_ecdsa_sign = 0;
-#endif
 	int nostrict = 1;
-	unsigned long alg_k;
+	unsigned long alg_k, alg_a = 0;
 
 	/* If we have custom certificate types set, use them */
 	if (s->cert->ctypes)
 		{
 		memcpy(p, s->cert->ctypes, s->cert->ctype_num);
 		return (int)s->cert->ctype_num;
 		}
-	/* get configured sigalgs */
-	siglen = tls12_get_psigalgs(s, &sig);
+	/* Get mask of algorithms disabled by signature list */
+	ssl_set_sig_mask(&alg_a, s, SSL_SECOP_SIGALG_MASK);
 	if (s->cert->cert_flags & SSL_CERT_FLAGS_CHECK_TLS_STRICT)
 		nostrict = 0;
-	for (i = 0; i < siglen; i+=2, sig+=2)
-		{
-		switch(sig[1])
-			{
-		case TLSEXT_signature_rsa:
-			have_rsa_sign = 1;
-			break;
-
-		case TLSEXT_signature_dsa:
-			have_dsa_sign = 1;
-			break;
-#ifndef OPENSSL_NO_ECDSA
-		case TLSEXT_signature_ecdsa:
-			have_ecdsa_sign = 1;
-			break;
-#endif
-			}
-		}
 
 	alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
 
@@ -4279,11 +4271,11 @@ int ssl3_get_req_cert_type(SSL *s, unsigned char *p)
 		/* Since this refers to a certificate signed with an RSA
 		 * algorithm, only check for rsa signing in strict mode.
 		 */
-		if (nostrict || have_rsa_sign)
+		if (nostrict || !(alg_a & SSL_aRSA))
 			p[ret++]=SSL3_CT_RSA_FIXED_DH;
 #  endif
 #  ifndef OPENSSL_NO_DSA
-		if (nostrict || have_dsa_sign)
+		if (nostrict || !(alg_a & SSL_aDSS))
 			p[ret++]=SSL3_CT_DSS_FIXED_DH;
 #  endif
 		}
@@ -4299,19 +4291,19 @@ int ssl3_get_req_cert_type(SSL *s, unsigned char *p)
 		}
 #endif /* !OPENSSL_NO_DH */
 #ifndef OPENSSL_NO_RSA
-	if (have_rsa_sign)
+	if (!(alg_a & SSL_aRSA))
 		p[ret++]=SSL3_CT_RSA_SIGN;
 #endif
 #ifndef OPENSSL_NO_DSA
-	if (have_dsa_sign)
+	if (!(alg_a & SSL_aDSS))
 		p[ret++]=SSL3_CT_DSS_SIGN;
 #endif
 #ifndef OPENSSL_NO_ECDH
 	if ((alg_k & (SSL_kECDHr|SSL_kECDHe)) && (s->version >= TLS1_VERSION))
 		{
-		if (nostrict || have_rsa_sign)
+		if (nostrict || !(alg_a & SSL_aRSA))
 			p[ret++]=TLS_CT_RSA_FIXED_ECDH;
-		if (nostrict || have_ecdsa_sign)
+		if (nostrict || !(alg_a & SSL_aECDSA))
 			p[ret++]=TLS_CT_ECDSA_FIXED_ECDH;
 		}
 #endif
@@ -4322,7 +4314,7 @@ int ssl3_get_req_cert_type(SSL *s, unsigned char *p)
 	 */
 	if (s->version >= TLS1_VERSION)
 		{
-		if (have_ecdsa_sign)
+		if (!(alg_a & SSL_aECDSA))
 			p[ret++]=TLS_CT_ECDSA_SIGN;
 		}
 #endif