[syslog] Add basic support for encrypted syslog via TLS

Encrypted syslog seems not yet to be standardised, but is supported by
some existing syslog servers.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/config.c

@@ -77,6 +77,9 @@ REQUIRE_OBJECT ( pc_kbd );
 #ifdef CONSOLE_SYSLOG
 REQUIRE_OBJECT ( syslog );
 #endif
+#ifdef CONSOLE_SYSLOGS
+REQUIRE_OBJECT ( syslogs );
+#endif
 #ifdef CONSOLE_EFI
 REQUIRE_OBJECT ( efi_console );
 #endif

src/config/console.h

@@ -19,6 +19,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 //#define	CONSOLE_DIRECT_VGA	/* Direct access to VGA card */
 //#define	CONSOLE_PC_KBD		/* Direct access to PC keyboard */
 //#define	CONSOLE_SYSLOG		/* Syslog console */
+//#define	CONSOLE_SYSLOGS		/* Encrypted syslog console */
 //#define	CONSOLE_VMWARE		/* VMware logfile console */
 
 #define	KEYBOARD_MAP	us

src/include/ipxe/dhcp.h

@@ -352,6 +352,9 @@ struct dhcp_client_uuid {
  */
 #define DHCP_EB_SCRIPTLET DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x51 )
 
+/** Encrypted syslog server */
+#define DHCP_EB_SYSLOGS_SERVER DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x55 )
+
 /** Skip PXE DHCP protocol extensions such as ProxyDHCP
  *
  * If set to a non-zero value, iPXE will not wait for ProxyDHCP offers

src/net/tcp/syslogs.c

@@ -0,0 +1,275 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * Encrypted syslog protocol
+ *
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <byteswap.h>
+#include <ipxe/xfer.h>
+#include <ipxe/open.h>
+#include <ipxe/tcpip.h>
+#include <ipxe/dhcp.h>
+#include <ipxe/settings.h>
+#include <ipxe/console.h>
+#include <ipxe/lineconsole.h>
+#include <ipxe/tls.h>
+#include <ipxe/syslog.h>
+#include <config/console.h>
+
+/* Set default console usage if applicable */
+#if ! ( defined ( CONSOLE_SYSLOGS ) && CONSOLE_EXPLICIT ( CONSOLE_SYSLOGS ) )
+#undef CONSOLE_SYSLOGS
+#define CONSOLE_SYSLOGS ( CONSOLE_USAGE_ALL & ~CONSOLE_USAGE_TUI )
+#endif
+
+struct console_driver syslogs_console __console_driver;
+
+/** The encrypted syslog server */
+static struct sockaddr_tcpip logserver = {
+	.st_family = AF_INET,
+	.st_port = htons ( SYSLOG_PORT ),
+};
+
+/**
+ * Handle encrypted syslog TLS interface close
+ *
+ * @v intf		Interface
+ * @v rc		Reason for close
+ */
+static void syslogs_close ( struct interface *intf __unused, int rc ) {
+
+	DBG ( "SYSLOGS console disconnected: %s\n", strerror ( rc ) );
+}
+
+/**
+ * Handle encrypted syslog TLS interface window change
+ *
+ * @v intf		Interface
+ */
+static void syslogs_window_changed ( struct interface *intf ) {
+
+	/* Mark console as enabled when window first opens, indicating
+	 * that TLS negotiation is complete.  (Do not disable console
+	 * when window closes again, since TCP will close the window
+	 * whenever there is unACKed data.)
+	 */
+	if ( xfer_window ( intf ) ) {
+		if ( syslogs_console.disabled )
+			DBG ( "SYSLOGS console connected\n" );
+		syslogs_console.disabled = 0;
+	}
+}
+
+/** Encrypted syslog TLS interface operations */
+static struct interface_operation syslogs_operations[] = {
+	INTF_OP ( xfer_window_changed, struct interface *,
+		  syslogs_window_changed ),
+	INTF_OP ( intf_close, struct interface *, syslogs_close ),
+};
+
+/** Encrypted syslog TLS interface descriptor */
+static struct interface_descriptor syslogs_desc =
+	INTF_DESC_PURE ( syslogs_operations );
+
+/** The encrypted syslog TLS interface */
+static struct interface syslogs = INTF_INIT ( syslogs_desc );
+
+/******************************************************************************
+ *
+ * Console driver
+ *
+ ******************************************************************************
+ */
+
+/** Encrypted syslog line buffer */
+static char syslogs_buffer[SYSLOG_BUFSIZE];
+
+/** Encrypted syslog severity */
+static unsigned int syslogs_severity = SYSLOG_DEFAULT_SEVERITY;
+
+/**
+ * Handle ANSI set encrypted syslog priority (private sequence)
+ *
+ * @v count		Parameter count
+ * @v params		List of graphic rendition aspects
+ */
+static void syslogs_handle_priority ( unsigned int count __unused,
+				      int params[] ) {
+	if ( params[0] >= 0 ) {
+		syslogs_severity = params[0];
+	} else {
+		syslogs_severity = SYSLOG_DEFAULT_SEVERITY;
+	}
+}
+
+/** Encrypted syslog ANSI escape sequence handlers */
+static struct ansiesc_handler syslogs_handlers[] = {
+	{ ANSIESC_LOG_PRIORITY, syslogs_handle_priority },
+	{ 0, NULL }
+};
+
+/** Encrypted syslog line console */
+static struct line_console syslogs_line = {
+	.buffer = syslogs_buffer,
+	.len = sizeof ( syslogs_buffer ),
+	.ctx = {
+		.handlers = syslogs_handlers,
+	},
+};
+
+/** Encrypted syslog recursion marker */
+static int syslogs_entered;
+
+/**
+ * Print a character to encrypted syslog console
+ *
+ * @v character		Character to be printed
+ */
+static void syslogs_putchar ( int character ) {
+	int rc;
+
+	/* Ignore if we are already mid-logging */
+	if ( syslogs_entered )
+		return;
+
+	/* Fill line buffer */
+	if ( line_putchar ( &syslogs_line, character ) == 0 )
+		return;
+
+	/* Guard against re-entry */
+	syslogs_entered = 1;
+
+	/* Send log message */
+	if ( ( rc = xfer_printf ( &syslogs, "<%d>ipxe: %s\n",
+				  SYSLOG_PRIORITY ( SYSLOG_DEFAULT_FACILITY,
+						    syslogs_severity ),
+				  syslogs_buffer ) ) != 0 ) {
+		DBG ( "SYSLOGS could not send log message: %s\n",
+		      strerror ( rc ) );
+	}
+
+	/* Clear re-entry flag */
+	syslogs_entered = 0;
+}
+
+/** Encrypted syslog console driver */
+struct console_driver syslogs_console __console_driver = {
+	.putchar = syslogs_putchar,
+	.disabled = 1,
+	.usage = CONSOLE_SYSLOGS,
+};
+
+/******************************************************************************
+ *
+ * Settings
+ *
+ ******************************************************************************
+ */
+
+/** Encrypted syslog server setting */
+struct setting syslogs_setting __setting ( SETTING_MISC ) = {
+	.name = "syslogs",
+	.description = "Encrypted syslog server",
+	.tag = DHCP_EB_SYSLOGS_SERVER,
+	.type = &setting_type_string,
+};
+
+/**
+ * Apply encrypted syslog settings
+ *
+ * @ret rc		Return status code
+ */
+static int apply_syslogs_settings ( void ) {
+	static char *old_server;
+	char *server;
+	struct interface *socket;
+	int len;
+	int rc;
+
+	/* Fetch log server */
+	len = fetch_string_setting_copy ( NULL, &syslogs_setting, &server );
+	if ( len < 0 ) {
+		rc = len;
+		goto err_fetch_server;
+	}
+
+	/* Do nothing unless log server has changed */
+	if ( ( ( server == NULL ) && ( old_server == NULL ) ) ||
+	     ( ( server != NULL ) && ( old_server != NULL ) &&
+	       ( strcmp ( server, old_server ) == 0 ) ) ) {
+		rc = 0;
+		goto out_no_change;
+	}
+	free ( old_server );
+	old_server = NULL;
+
+	/* Reset encrypted syslog connection */
+	syslogs_console.disabled = 1;
+	intf_restart ( &syslogs, 0 );
+
+	/* Do nothing unless we have a log server */
+	if ( ! server ) {
+		DBG ( "SYSLOGS has no log server\n" );
+		rc = 0;
+		goto out_no_server;
+	}
+
+	/* Add TLS filter */
+	if ( ( rc = add_tls ( &syslogs, server, &socket ) ) != 0 ) {
+		DBG ( "SYSLOGS cannot create TLS filter: %s\n",
+		      strerror ( rc ) );
+		goto err_add_tls;
+	}
+
+	/* Connect to log server */
+	if ( ( rc = xfer_open_named_socket ( socket, SOCK_STREAM,
+					     (( struct sockaddr *) &logserver ),
+					     server, NULL ) ) != 0 ) {
+		DBG ( "SYSLOGS cannot connect to log server: %s\n",
+		      strerror ( rc ) );
+		goto err_open_named_socket;
+	}
+	DBG ( "SYSLOGS using log server %s\n", server );
+
+	/* Record log server */
+	old_server = server;
+	server = NULL;
+
+	/* Success */
+	rc = 0;
+
+ err_open_named_socket:
+ err_add_tls:
+ out_no_server:
+ out_no_change:
+	free ( server );
+ err_fetch_server:
+	return rc;
+}
+
+/** Encrypted syslog settings applicator */
+struct settings_applicator syslogs_applicator __settings_applicator = {
+	.apply = apply_syslogs_settings,
+};