tls: add an option to dump tls secrets for wireshark decoding (#8120)

This new option /tls-secret-file:<file> allows to dump TLS secrets in a file with
the SSLKEYLOGFILE format. So this way you can setup the TLS dissector of wireshark
(Pre-Master-Secret log filename) and see the traffic in clear in wireshark.
It also add some more PFS ciphers to remove for netmon captures.

client/common/cmdline.c

@@ -2867,7 +2867,7 @@ int freerdp_client_settings_parse_command_line_arguments(rdpSettings* settings,
 
 			if (strcmp(arg->Value, "netmon") == 0)
 			{
-				ciphers = "ALL:!ECDH";
+				ciphers = "ALL:!ECDH:!ADH:!DHE";
 			}
 			else if (strcmp(arg->Value, "ma") == 0)
 			{
@@ -2890,6 +2890,14 @@ int freerdp_client_settings_parse_command_line_arguments(rdpSettings* settings,
 
 			settings->TlsSecLevel = (UINT32)val;
 		}
+		CommandLineSwitchCase(arg, "tls-secrets-file")
+		{
+			if (!arg->Value)
+				return COMMAND_LINE_ERROR_UNEXPECTED_VALUE;
+
+			if (!freerdp_settings_set_string(settings, FreeRDP_TlsSecretsFile, arg->Value))
+				return COMMAND_LINE_ERROR_MEMORY;
+		}
 		CommandLineSwitchCase(arg, "enforce-tlsv1_2")
 		{
 			if (!(freerdp_settings_set_uint16(settings, FreeRDP_TLSMinVersion, TLS1_2_VERSION) &&

client/common/cmdline.h

@@ -369,6 +369,8 @@ static const COMMAND_LINE_ARGUMENT_A global_cmd_args[] = {
 	  "Allowed TLS ciphers" },
 	{ "tls-seclevel", COMMAND_LINE_VALUE_REQUIRED, "<level>", "1", NULL, -1, NULL,
 	  "TLS security level - defaults to 1" },
+	{ "tls-secrets-file", COMMAND_LINE_VALUE_REQUIRED, "<filename>", NULL, NULL, -1, NULL,
+	  "File were TLS secrets will be stored in the SSLKEYLOGFILE format" },
 	{ "enforce-tlsv1_2", COMMAND_LINE_VALUE_BOOL, NULL, BoolValueFalse, NULL, -1, NULL,
 	  "Force use of TLS1.2 for connection. Some servers have a buggy TLS version negotiation and "
 	  "might fail without this" },

include/freerdp/settings.h

@@ -639,6 +639,7 @@ typedef struct
 #define FreeRDP_SspiModule (1106)
 #define FreeRDP_TLSMinVersion (1107)
 #define FreeRDP_TLSMaxVersion (1108)
+#define FreeRDP_TlsSecretsFile (1109)
 #define FreeRDP_MstscCookieMode (1152)
 #define FreeRDP_CookieMaxLength (1153)
 #define FreeRDP_PreconnectionId (1154)
@@ -1126,7 +1127,8 @@ struct rdp_settings
 	ALIGN64 char* SspiModule;                  /* 1106 */
 	ALIGN64 UINT16 TLSMinVersion;              /* 1107 */
 	ALIGN64 UINT16 TLSMaxVersion;              /* 1108 */
-	UINT64 padding1152[1152 - 1109];           /* 1109 */
+	ALIGN64 char* TlsSecretsFile;              /* 1109 */
+	UINT64 padding1152[1152 - 1110];           /* 1110 */
 
 	/* Connection Cookie */
 	ALIGN64 BOOL MstscCookieMode;      /* 1152 */

libfreerdp/common/settings_getters.c

@@ -2594,6 +2594,9 @@ const char* freerdp_settings_get_string(const rdpSettings* settings, size_t id)
 		case FreeRDP_TargetNetAddress:
 			return settings->TargetNetAddress;
 
+		case FreeRDP_TlsSecretsFile:
+			return settings->TlsSecretsFile;
+
 		case FreeRDP_TransportDumpFile:
 			return settings->TransportDumpFile;
 
@@ -2855,6 +2858,9 @@ char* freerdp_settings_get_string_writable(rdpSettings* settings, size_t id)
 		case FreeRDP_TargetNetAddress:
 			return settings->TargetNetAddress;
 
+		case FreeRDP_TlsSecretsFile:
+			return settings->TlsSecretsFile;
+
 		case FreeRDP_TransportDumpFile:
 			return settings->TransportDumpFile;
 
@@ -3126,6 +3132,9 @@ BOOL freerdp_settings_set_string_(rdpSettings* settings, size_t id, const char*
 		case FreeRDP_TargetNetAddress:
 			return update_string(&settings->TargetNetAddress, cnv.cc, len, cleanup);
 
+		case FreeRDP_TlsSecretsFile:
+			return update_string(&settings->TlsSecretsFile, cnv.cc, len, cleanup);
+
 		case FreeRDP_TransportDumpFile:
 			return update_string(&settings->TransportDumpFile, cnv.cc, len, cleanup);
 

libfreerdp/common/settings_str.c

@@ -391,6 +391,7 @@ static const struct settings_str_entry settings_map[] = {
 	{ FreeRDP_SmartcardPrivateKey, 7, "FreeRDP_SmartcardPrivateKey" },
 	{ FreeRDP_SspiModule, 7, "FreeRDP_SspiModule" },
 	{ FreeRDP_TargetNetAddress, 7, "FreeRDP_TargetNetAddress" },
+	{ FreeRDP_TlsSecretsFile, 7, "FreeRDP_TlsSecretsFile" },
 	{ FreeRDP_TransportDumpFile, 7, "FreeRDP_TransportDumpFile" },
 	{ FreeRDP_Username, 7, "FreeRDP_Username" },
 	{ FreeRDP_WindowTitle, 7, "FreeRDP_WindowTitle" },

libfreerdp/core/test/settings_property_lists.h

@@ -400,6 +400,7 @@ static const size_t string_list_indices[] = {
 	FreeRDP_SmartcardPrivateKey,
 	FreeRDP_SspiModule,
 	FreeRDP_TargetNetAddress,
+	FreeRDP_TlsSecretsFile,
 	FreeRDP_TransportDumpFile,
 	FreeRDP_Username,
 	FreeRDP_WindowTitle,

libfreerdp/crypto/tls.c

@@ -646,6 +646,33 @@ out_free:
 	return NULL;
 }
 
+static INIT_ONCE secrets_file_idx_once = INIT_ONCE_STATIC_INIT;
+static int secrets_file_idx = -1;
+
+static BOOL CALLBACK secrets_file_init_cb(PINIT_ONCE once, PVOID param, PVOID* context)
+{
+	secrets_file_idx = SSL_get_ex_new_index(0, NULL, NULL, NULL, NULL);
+
+	return (secrets_file_idx != -1);
+}
+
+static void SSLCTX_keylog_cb(const SSL* ssl, const char* line)
+{
+	char* dfile;
+
+	if (secrets_file_idx == -1)
+		return;
+
+	dfile = SSL_get_ex_data(ssl, secrets_file_idx);
+	if (dfile)
+	{
+		FILE* f = fopen(dfile, "a+");
+		fwrite(line, strlen(line), 1, f);
+		fwrite("\n", 1, 1, f);
+		fclose(f);
+	}
+}
+
 #if OPENSSL_VERSION_NUMBER >= 0x010000000L
 static BOOL tls_prepare(rdpTls* tls, BIO* underlying, const SSL_METHOD* method, int options,
                         BOOL clientMode)
@@ -656,6 +683,7 @@ static BOOL tls_prepare(rdpTls* tls, BIO* underlying, SSL_METHOD* method, int op
 {
 	rdpSettings* settings = tls->settings;
 	tls->ctx = SSL_CTX_new(method);
+
 	tls->underlying = underlying;
 
 	if (!tls->ctx)
@@ -702,6 +730,17 @@ static BOOL tls_prepare(rdpTls* tls, BIO* underlying, SSL_METHOD* method, int op
 		return FALSE;
 	}
 
+	if (settings->TlsSecretsFile)
+	{
+		InitOnceExecuteOnce(&secrets_file_idx_once, secrets_file_init_cb, NULL, NULL);
+
+		if (secrets_file_idx != -1)
+		{
+			SSL_set_ex_data(tls->ssl, secrets_file_idx, settings->TlsSecretsFile);
+			SSL_CTX_set_keylog_callback(tls->ctx, SSLCTX_keylog_cb);
+		}
+	}
+
 	BIO_push(tls->bio, underlying);
 	return TRUE;
 }