cert auth: filter out unsupported cert types from TLS 1.2 CR

When the server is advertising signature algorithms in TLS 1.2
CertificateRequest, it shouldn't send certificate_types not backed by
any of those algorithms.

Signed-off-by: Daiki Ueno <ueno@gnu.org>

2 files changed, 89 insertions, 6 deletions

diff --git a/lib/auth/cert.c b/lib/auth/cert.c
index 3073a33d34..0b0f04b2b1 100644
--- a/lib/auth/cert.c
+++ b/lib/auth/cert.c
@@ -64,6 +64,16 @@ typedef enum CertificateSigType { RSA_SIGN = 1, DSA_SIGN = 2, ECDSA_SIGN = 64,
 #endif
 } CertificateSigType;
 
+enum CertificateSigTypeFlags {
+	RSA_SIGN_FLAG = 1,
+	DSA_SIGN_FLAG = 1 << 1,
+	ECDSA_SIGN_FLAG = 1 << 2,
+#ifdef ENABLE_GOST
+	GOSTR34102012_256_SIGN_FLAG = 1 << 3,
+	GOSTR34102012_512_SIGN_FLAG = 1 << 4
+#endif
+};
+
 /* Moves data from an internal certificate struct (gnutls_pcert_st) to
  * another internal certificate struct (cert_auth_info_t), and deinitializes
  * the former.
@@ -1281,6 +1291,7 @@ _gnutls_gen_cert_server_cert_req(gnutls_session_t session,
 	uint8_t tmp_data[CERTTYPE_SIZE];
 	const version_entry_st *ver = get_version(session);
 	unsigned init_pos = data->length;
+	enum CertificateSigTypeFlags flags;
 
 	if (unlikely(ver == NULL))
 		return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
@@ -1297,18 +1308,71 @@ _gnutls_gen_cert_server_cert_req(gnutls_session_t session,
 		return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
 	}
 
-	i = 1;
+	if (_gnutls_version_has_selectable_sighash(ver)) {
+		size_t j;
+
+		flags = 0;
+		for (j = 0; j < session->internals.priorities->sigalg.size; j++) {
+			const gnutls_sign_entry_st *se =
+				session->internals.priorities->sigalg.entry[j];
+			switch (se->pk) {
+			case GNUTLS_PK_RSA:
+			case GNUTLS_PK_RSA_PSS:
+				flags |= RSA_SIGN_FLAG;
+				break;
+			case GNUTLS_PK_DSA:
+				flags |= DSA_SIGN_FLAG;
+				break;
+			case GNUTLS_PK_ECDSA:
+				flags |= ECDSA_SIGN_FLAG;
+				break;
 #ifdef ENABLE_GOST
-	if (_gnutls_kx_is_vko_gost(session->security_parameters.cs->kx_algorithm)) {
-		tmp_data[i++] = GOSTR34102012_256_SIGN;
-		tmp_data[i++] = GOSTR34102012_512_SIGN;
-	} else
+			case GNUTLS_PK_GOST_12_256:
+				flags |= GOSTR34102012_256_SIGN_FLAG;
+				break;
+			case GNUTLS_PK_GOST_12_512:
+				flags |= GOSTR34102012_512_SIGN_FLAG;
+				break;
+#endif
+			default:
+				gnutls_assert();
+				_gnutls_debug_log(
+					"%s is unsupported for cert request\n",
+					gnutls_pk_get_name(se->pk));
+			}
+		}
+
+	} else {
+#ifdef ENABLE_GOST
+		if (_gnutls_kx_is_vko_gost(session->security_parameters.
+					   cs->kx_algorithm)) {
+			flags = GOSTR34102012_256_SIGN_FLAG |
+				GOSTR34102012_512_SIGN_FLAG;
+		} else
 #endif
-	{
+		{
+			flags = RSA_SIGN_FLAG | DSA_SIGN_FLAG | ECDSA_SIGN_FLAG;
+		}
+	}
+
+	i = 1;
+	if (flags & RSA_SIGN_FLAG) {
 		tmp_data[i++] = RSA_SIGN;
+	}
+	if (flags & DSA_SIGN_FLAG) {
 		tmp_data[i++] = DSA_SIGN;
+	}
+	if (flags & ECDSA_SIGN_FLAG) {
 		tmp_data[i++] = ECDSA_SIGN;
 	}
+#ifdef ENABLE_GOST
+	if (flags & GOSTR34102012_256_SIGN_FLAG) {
+		tmp_data[i++] = GOSTR34102012_256_SIGN;
+	}
+	if (flags & GOSTR34102012_512_SIGN_FLAG) {
+		tmp_data[i++] = GOSTR34102012_512_SIGN;
+	}
+#endif
 	tmp_data[0] = i - 1;
 
 	ret = _gnutls_buffer_append_data(data, tmp_data, i);
diff --git a/tests/suite/tls-fuzzer/gnutls-cert.json b/tests/suite/tls-fuzzer/gnutls-cert.json
index 6f5874c095..e49cb432ff 100644
--- a/tests/suite/tls-fuzzer/gnutls-cert.json
+++ b/tests/suite/tls-fuzzer/gnutls-cert.json
@@ -96,5 +96,24 @@
                          "-p", "@PORT@"]
 	 }
      ]
+    },
+    {"server_command": ["@SERVER@", "--http",
+                 "--x509keyfile", "tests/serverX509Key.pem",
+                 "--x509certfile", "tests/serverX509Cert.pem",
+                 "--debug=6",
+                 "--priority=NORMAL:+VERS-TLS1.2",
+                 "--port=@PORT@"],
+     "environment": {"PYTHONPATH" : "."},
+     "server_hostname": "localhost",
+     "server_port": @PORT@,
+     "tests" : [
+         {"name" : "test-certificate-request.py",
+          "arguments" : ["-k", "tests/clientX509Key.pem",
+                         "-c", "tests/clientX509Cert.pem",
+                         "-p", "@PORT@",
+                         "-s", "sha256+rsa rsa_pss_pss_sha256 rsa_pss_rsae_sha256 sha256+ecdsa rsa_pss_rsae_sha256 sha384+rsa rsa_pss_pss_sha384 rsa_pss_rsae_sha384 sha384+ecdsa ed448 sha512+rsa rsa_pss_pss_sha512 rsa_pss_rsae_sha512 sha512+ecdsa sha1+rsa sha1+ecdsa",
+                         "check cert types in cert request"]
+         }
+     ]
     }
 ]