- dtucker@cvs.openbsd.org 2013/05/16 04:09:14

[sshd_config.5 servconf.c servconf.h packet.c serverloop.c monitor.c sshd_config
     sshd.c] Add RekeyLimit to sshd with the same syntax as the client allowing
     rekeying based on traffic volume or time.  ok djm@, help & ok jmc@ for the man
     page.

ChangeLog

@@ -28,6 +28,11 @@
      Add an optional second argument to RekeyLimit in the client to allow
      rekeying based on elapsed time in addition to amount of traffic.
      with djm@ jmc@, ok djm
+   - dtucker@cvs.openbsd.org 2013/05/16 04:09:14
+     [sshd_config.5 servconf.c servconf.h packet.c serverloop.c monitor.c sshd_config
+     sshd.c] Add RekeyLimit to sshd with the same syntax as the client allowing
+     rekeying based on traffic volume or time.  ok djm@, help & ok jmc@ for the man
+     page.
 
 20130510
  - (dtucker) [configure.ac] Enable -Wsizeof-pointer-memaccess if the compiler

monitor.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.122 2013/03/07 19:27:25 markus Exp $ */
+/* $OpenBSD: monitor.c,v 1.123 2013/05/16 04:09:13 dtucker Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -1810,6 +1810,10 @@ monitor_apply_keystate(struct monitor *pmonitor)
 	if (options.compression)
 		mm_init_compression(pmonitor->m_zlib);
 
+	if (options.rekey_limit || options.rekey_interval)
+		packet_set_rekey_limits((u_int32_t)options.rekey_limit,
+		    (time_t)options.rekey_interval);
+
 	/* Network I/O buffers */
 	/* XXX inefficient for large buffers, need: buffer_init_from_string */
 	buffer_clear(packet_get_input());

packet.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.184 2013/05/16 02:00:34 dtucker Exp $ */
+/* $OpenBSD: packet.c,v 1.185 2013/05/16 04:09:13 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1966,7 +1966,7 @@ packet_get_rekey_timeout(void)
 
 	seconds = active_state->rekey_time + active_state->rekey_interval -
 	    time(NULL);
-	return (seconds < 0 ? 0 : seconds);
+	return (seconds <= 0 ? 1 : seconds);
 }
 
 void

servconf.c

@@ -1,5 +1,5 @@
 
-/* $OpenBSD: servconf.c,v 1.234 2013/02/06 00:20:42 dtucker Exp $ */
+/* $OpenBSD: servconf.c,v 1.235 2013/05/16 04:09:14 dtucker Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -20,6 +20,7 @@
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
 
+#include <ctype.h>
 #include <netdb.h>
 #include <pwd.h>
 #include <stdio.h>
@@ -110,6 +111,8 @@ initialize_server_options(ServerOptions *options)
 	options->permit_user_env = -1;
 	options->use_login = -1;
 	options->compression = -1;
+	options->rekey_limit = -1;
+	options->rekey_interval = -1;
 	options->allow_tcp_forwarding = -1;
 	options->allow_agent_forwarding = -1;
 	options->num_allow_users = 0;
@@ -249,6 +252,10 @@ fill_default_server_options(ServerOptions *options)
 		options->use_login = 0;
 	if (options->compression == -1)
 		options->compression = COMP_DELAYED;
+	if (options->rekey_limit == -1)
+		options->rekey_limit = 0;
+	if (options->rekey_interval == -1)
+		options->rekey_interval = 0;
 	if (options->allow_tcp_forwarding == -1)
 		options->allow_tcp_forwarding = FORWARD_ALLOW;
 	if (options->allow_agent_forwarding == -1)
@@ -320,7 +327,7 @@ typedef enum {
 	sX11Forwarding, sX11DisplayOffset, sX11UseLocalhost,
 	sStrictModes, sEmptyPasswd, sTCPKeepAlive,
 	sPermitUserEnvironment, sUseLogin, sAllowTcpForwarding, sCompression,
-	sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups,
+	sRekeyLimit, sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups,
 	sIgnoreUserKnownHosts, sCiphers, sMacs, sProtocol, sPidFile,
 	sGatewayPorts, sPubkeyAuthentication, sXAuthLocation, sSubsystem,
 	sMaxStartups, sMaxAuthTries, sMaxSessions,
@@ -422,6 +429,7 @@ static struct {
 	{ "permituserenvironment", sPermitUserEnvironment, SSHCFG_GLOBAL },
 	{ "uselogin", sUseLogin, SSHCFG_GLOBAL },
 	{ "compression", sCompression, SSHCFG_GLOBAL },
+	{ "rekeylimit", sRekeyLimit, SSHCFG_ALL },
 	{ "tcpkeepalive", sTCPKeepAlive, SSHCFG_GLOBAL },
 	{ "keepalive", sTCPKeepAlive, SSHCFG_GLOBAL },	/* obsolete alias */
 	{ "allowtcpforwarding", sAllowTcpForwarding, SSHCFG_ALL },
@@ -800,14 +808,14 @@ process_server_config_line(ServerOptions *options, char *line,
     const char *filename, int linenum, int *activep,
     struct connection_info *connectinfo)
 {
-	char *cp, **charptr, *arg, *p;
+	char *cp, **charptr, *arg, *p, *endofnumber;
-	int cmdline = 0, *intptr, value, value2, n;
+	int cmdline = 0, *intptr, value, value2, n, port, scale;
 	SyslogFacility *log_facility_ptr;
 	LogLevel *log_level_ptr;
 	ServerOpCodes opcode;
-	int port;
 	u_int i, flags = 0;
 	size_t len;
+	long long orig, val64;
 	const struct multistate *multistate_ptr;
 
 	cp = line;
@@ -1118,6 +1126,59 @@ process_server_config_line(ServerOptions *options, char *line,
 		multistate_ptr = multistate_compression;
 		goto parse_multistate;
 
+	case sRekeyLimit:
+		arg = strdelim(&cp);
+		if (!arg || *arg == '\0')
+			fatal("%.200s line %d: Missing argument.", filename,
+			    linenum);
+		if (strcmp(arg, "default") == 0) {
+			val64 = 0;
+		} else {
+			if (arg[0] < '0' || arg[0] > '9')
+				fatal("%.200s line %d: Bad number.", filename,
+				    linenum);
+			orig = val64 = strtoll(arg, &endofnumber, 10);
+			if (arg == endofnumber)
+				fatal("%.200s line %d: Bad number.", filename,
+			 linenum);
+	 		switch (toupper(*endofnumber)) {
+			case '\0':
+				scale = 1;
+				break;
+			case 'K':
+				scale = 1<<10;
+				break;
+			case 'M':
+				scale = 1<<20;
+				break;
+			case 'G':
+				scale = 1<<30;
+				break;
+			default:
+				fatal("%.200s line %d: Invalid RekeyLimit "
+				    "suffix", filename, linenum);
+			}
+			val64 *= scale;
+			/* detect integer wrap and too-large limits */
+			if ((val64 / scale) != orig || val64 > UINT_MAX)
+				fatal("%.200s line %d: RekeyLimit too large",
+				    filename, linenum);
+			if (val64 != 0 && val64 < 16)
+				fatal("%.200s line %d: RekeyLimit too small",
+				    filename, linenum);
+		}
+		if (*activep && options->rekey_limit == -1)
+			options->rekey_limit = (u_int32_t)val64;
+		if (cp != NULL) { /* optional rekey interval present */
+			if (strcmp(cp, "none") == 0) {
+				(void)strdelim(&cp);	/* discard */
+				break;
+			}
+			intptr = &options->rekey_interval;
+			goto parse_time;
+		}
+		break;
+
 	case sGatewayPorts:
 		intptr = &options->gateway_ports;
 		multistate_ptr = multistate_gatewayports;
@@ -1718,6 +1779,8 @@ copy_set_server_options(ServerOptions *dst, ServerOptions *src, int preauth)
 	M_CP_INTOPT(max_authtries);
 	M_CP_INTOPT(ip_qos_interactive);
 	M_CP_INTOPT(ip_qos_bulk);
+	M_CP_INTOPT(rekey_limit);
+	M_CP_INTOPT(rekey_interval);
 
 	/* See comment in servconf.h */
 	COPY_MATCH_STRING_OPTS();
@@ -2006,5 +2069,7 @@ dump_config(ServerOptions *o)
 	printf("ipqos %s ", iptos2str(o->ip_qos_interactive));
 	printf("%s\n", iptos2str(o->ip_qos_bulk));
 
+	printf("rekeylimit %lld %d\n", o->rekey_limit, o->rekey_interval);
+
 	channel_print_adm_permitted_opens();
 }

servconf.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.h,v 1.107 2013/01/03 05:49:36 djm Exp $ */
+/* $OpenBSD: servconf.h,v 1.108 2013/05/16 04:09:14 dtucker Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -176,6 +176,9 @@ typedef struct {
 	char   *authorized_keys_command;
 	char   *authorized_keys_command_user;
 
+	int64_t rekey_limit;
+	int	rekey_interval;
+
 	char   *version_addendum;	/* Appended to SSH banner */
 
 	u_int	num_auth_methods;

serverloop.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.164 2012/12/07 01:51:35 dtucker Exp $ */
+/* $OpenBSD: serverloop.c,v 1.165 2013/05/16 04:09:14 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -277,7 +277,7 @@ client_alive_check(void)
  */
 static void
 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
-    u_int *nallocp, u_int max_time_milliseconds)
+    u_int *nallocp, u_int64_t max_time_milliseconds)
 {
 	struct timeval tv, *tvp;
 	int ret;
@@ -563,7 +563,7 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
 	int wait_status;	/* Status returned by wait(). */
 	pid_t wait_pid;		/* pid returned by wait(). */
 	int waiting_termination = 0;	/* Have displayed waiting close message. */
-	u_int max_time_milliseconds;
+	u_int64_t max_time_milliseconds;
 	u_int previous_stdout_buffer_bytes;
 	u_int stdout_buffer_bytes;
 	int type;
@@ -826,6 +826,7 @@ server_loop2(Authctxt *authctxt)
 {
 	fd_set *readset = NULL, *writeset = NULL;
 	int rekeying = 0, max_fd, nalloc = 0;
+	u_int64_t rekey_timeout_ms = 0;
 
 	debug("Entering interactive session for SSH2.");
 
@@ -854,8 +855,13 @@ server_loop2(Authctxt *authctxt)
 
 		if (!rekeying && packet_not_very_much_data_to_write())
 			channel_output_poll();
+		if (options.rekey_interval > 0 && compat20 && !rekeying)
+			rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
+		else
+			rekey_timeout_ms = 0;
+
 		wait_until_can_do_something(&readset, &writeset, &max_fd,
-		    &nalloc, 0);
+		    &nalloc, rekey_timeout_ms);
 
 		if (received_sigterm) {
 			logit("Exiting on signal %d", (int)received_sigterm);

sshd.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.399 2013/04/07 02:10:33 dtucker Exp $ */
+/* $OpenBSD: sshd.c,v 1.400 2013/05/16 04:09:14 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2364,6 +2364,10 @@ do_ssh2_kex(void)
 	if (options.kex_algorithms != NULL)
 		myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 
+	if (options.rekey_limit || options.rekey_interval)
+		packet_set_rekey_limits((u_int32_t)options.rekey_limit,
+		    (time_t)options.rekey_interval);
+
 	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
 
 	/* start key exchange */

sshd_config

@@ -1,4 +1,4 @@
-#	$OpenBSD: sshd_config,v 1.89 2013/02/06 00:20:42 dtucker Exp $
+#	$OpenBSD: sshd_config,v 1.90 2013/05/16 04:09:14 dtucker Exp $
 
 # This is the sshd server system-wide configuration file.  See
 # sshd_config(5) for more information.
@@ -29,6 +29,9 @@
 #KeyRegenerationInterval 1h
 #ServerKeyBits 1024
 
+# Ciphers and keying
+#RekeyLimit default none
+
 # Logging
 # obsoletes QuietMode and FascistLogging
 #SyslogFacility AUTH

sshd_config.5

@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd_config.5,v 1.158 2013/04/19 01:00:10 djm Exp $
+.\" $OpenBSD: sshd_config.5,v 1.159 2013/05/16 04:09:14 dtucker Exp $
-.Dd $Mdocdate: April 19 2013 $
+.Dd $Mdocdate: May 16 2013 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -814,6 +814,7 @@ Available keywords are
 .Cm PermitRootLogin ,
 .Cm PermitTunnel ,
 .Cm PubkeyAuthentication ,
+.Cm RekeyLimit ,
 .Cm RhostsRSAAuthentication ,
 .Cm RSAAuthentication ,
 .Cm X11DisplayOffset ,
@@ -1008,6 +1009,33 @@ Specifies whether public key authentication is allowed.
 The default is
 .Dq yes .
 Note that this option applies to protocol version 2 only.
+.It Cm RekeyLimit
+Specifies the maximum amount of data that may be transmitted before the
+session key is renegotiated, optionally followed a maximum amount of
+time that may pass before the session key is renegotiated.
+The first argument is specified in bytes and may have a suffix of
+.Sq K ,
+.Sq M ,
+or
+.Sq G
+to indicate Kilobytes, Megabytes, or Gigabytes, respectively.
+The default is between
+.Sq 1G
+and
+.Sq 4G ,
+depending on the cipher.
+The optional second value is specified in seconds and may use any of the
+units documented in the
+.Sx TIME FORMATS
+section of
+.Xr sshd_config 5 .
+The default value for
+.Cm RekeyLimit
+is
+.Dq default none ,
+which means that rekeying is performed after the cipher's default amount
+of data has been sent or received and no time based rekeying is done.
+This option applies to protocol version 2 only.
 .It Cm RevokedKeys
 Specifies revoked public keys.
 Keys listed in this file will be refused for public key authentication.