- provos@cvs.openbsd.org 2002/03/18 17:50:31

     [auth-bsdauth.c auth-options.c auth-rh-rsa.c auth-rsa.c auth-skey.c auth.h
      auth1.c auth2-chall.c auth2.c kex.c kex.h kexdh.c kexgex.c servconf.c
      session.h servconf.h serverloop.c session.c sshd.c]
     integrate privilege separated openssh; its turned off by default for now.
     work done by me and markus@

applied, but outside of ensure that smaller code bits migrated with
their owners.. no work was tried to 'fix' it to work. =)  Later project!

29 files changed, 3549 insertions, 138 deletions

diff --git a/ChangeLog b/ChangeLog
index 8ee5bb9a..9c8ddecc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -59,6 +59,12 @@
    - provos@cvs.openbsd.org 2002/03/18 17:31:54
      [compress.c]
      export compression streams for ssh-privsep
+   - provos@cvs.openbsd.org 2002/03/18 17:50:31
+     [auth-bsdauth.c auth-options.c auth-rh-rsa.c auth-rsa.c auth-skey.c auth.h
+      auth1.c auth2-chall.c auth2.c kex.c kex.h kexdh.c kexgex.c servconf.c
+      session.h servconf.h serverloop.c session.c sshd.c]
+     integrate privilege separated openssh; its turned off by default for now.
+     work done by me and markus@
 
 20020317
  - (tim) [configure.ac] Assume path given with --with-pid-dir=PATH is wanted,
@@ -7905,4 +7911,4 @@
  - Wrote replacements for strlcpy and mkdtemp
  - Released 1.0pre1
 
-$Id: ChangeLog,v 1.1942 2002/03/22 01:51:24 mouring Exp $
+$Id: ChangeLog,v 1.1943 2002/03/22 02:30:41 mouring Exp $
diff --git a/Makefile.in b/Makefile.in
index 31aa8e58..cae801ef 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1,4 +1,4 @@
-# $Id: Makefile.in,v 1.199 2002/03/13 02:19:42 djm Exp $
+# $Id: Makefile.in,v 1.200 2002/03/22 02:30:43 mouring Exp $
 
 prefix=@prefix@
 exec_prefix=@exec_prefix@
@@ -50,11 +50,11 @@ INSTALL_SSH_RAND_HELPER=@INSTALL_SSH_RAND_HELPER@
 
 TARGETS=ssh$(EXEEXT) sshd$(EXEEXT) ssh-add$(EXEEXT) ssh-keygen$(EXEEXT) ssh-keyscan${EXEEXT} ssh-agent$(EXEEXT) scp$(EXEEXT) ssh-rand-helper${EXEEXT} $(SFTP_PROGS)
 
-LIBSSH_OBJS=atomicio.o authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o cipher.o compat.o compress.o crc32.o deattack.o dh.o dispatch.o fatal.o mac.o hostfile.o key.o kex.o kexdh.o kexgex.o log.o match.o misc.o mpaux.o nchan.o packet.o radix.o rijndael.o entropy.o readpass.o rsa.o scard.o ssh-dss.o ssh-rsa.o tildexpand.o ttymodes.o uidswap.o uuencode.o xmalloc.o 
+LIBSSH_OBJS=atomicio.o authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o cipher.o compat.o compress.o crc32.o deattack.o dh.o dispatch.o fatal.o mac.o hostfile.o key.o kex.o kexdh.o kexgex.o log.o match.o misc.o mpaux.o nchan.o packet.o radix.o rijndael.o entropy.o readpass.o rsa.o scard.o ssh-dss.o ssh-rsa.o tildexpand.o ttymodes.o uidswap.o uuencode.o xmalloc.o monitor_wrap.o monitor_fdpass.o
 
 SSHOBJS= ssh.o sshconnect.o sshconnect1.o sshconnect2.o sshtty.o readconf.o clientloop.o
 
-SSHDOBJS= sshd.o auth.o auth1.o auth2.o auth-chall.o auth2-chall.o auth-rhosts.o auth-options.o auth-krb4.o auth-pam.o auth2-pam.o auth-passwd.o auth-rsa.o auth-rh-rsa.o auth-sia.o sshpty.o sshlogin.o loginrec.o servconf.o serverloop.o md5crypt.o session.o groupaccess.o auth-skey.o auth-bsdauth.o
+SSHDOBJS= sshd.o auth.o auth1.o auth2.o auth-chall.o auth2-chall.o auth-rhosts.o auth-options.o auth-krb4.o auth-pam.o auth2-pam.o auth-passwd.o auth-rsa.o auth-rh-rsa.o auth-sia.o sshpty.o sshlogin.o loginrec.o servconf.o serverloop.o md5crypt.o session.o groupaccess.o auth-skey.o auth-bsdauth.o monitor_mm.o monitor.o
 
 MANPAGES	= scp.1.out ssh-add.1.out ssh-agent.1.out ssh-keygen.1.out ssh-keyscan.1.out ssh.1.out sshd.8.out sftp-server.8.out sftp.1.out
 MANPAGES_IN	= scp.1 ssh-add.1 ssh-agent.1 ssh-keygen.1 ssh-keyscan.1 ssh.1 sshd.8 sftp-server.8 sftp.1
diff --git a/auth-bsdauth.c b/auth-bsdauth.c
index b70d48f2..fa06732c 100644
--- a/auth-bsdauth.c
+++ b/auth-bsdauth.c
@@ -22,12 +22,13 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include "includes.h"
-RCSID("$OpenBSD: auth-bsdauth.c,v 1.2 2001/12/19 07:18:56 deraadt Exp $");
+RCSID("$OpenBSD: auth-bsdauth.c,v 1.3 2002/03/18 17:50:31 provos Exp $");
 
 #ifdef BSD_AUTH
 #include "xmalloc.h"
 #include "auth.h"
 #include "log.h"
+#include "monitor_wrap.h"
 
 static void *
 bsdauth_init_ctx(Authctxt *authctxt)
@@ -35,7 +36,7 @@ bsdauth_init_ctx(Authctxt *authctxt)
 	return authctxt;
 }
 
-static int
+int
 bsdauth_query(void *ctx, char **name, char **infotxt,
    u_int *numprompts, char ***prompts, u_int **echo_on)
 {
@@ -76,7 +77,7 @@ bsdauth_query(void *ctx, char **name, char **infotxt,
 	return 0;
 }
 
-static int
+int
 bsdauth_respond(void *ctx, u_int numresponses, char **responses)
 {
 	Authctxt *authctxt = ctx;
@@ -113,4 +114,12 @@ KbdintDevice bsdauth_device = {
 	bsdauth_respond,
 	bsdauth_free_ctx
 };
+
+KbdintDevice mm_bsdauth_device = {
+	"bsdauth",
+	bsdauth_init_ctx,
+	mm_bsdauth_query,
+	mm_bsdauth_respond,
+	bsdauth_free_ctx
+};
 #endif
diff --git a/auth-options.c b/auth-options.c
index 8df6a6df..48be6d8e 100644
--- a/auth-options.c
+++ b/auth-options.c
@@ -10,7 +10,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth-options.c,v 1.21 2002/01/29 14:32:03 markus Exp $");
+RCSID("$OpenBSD: auth-options.c,v 1.22 2002/03/18 17:50:31 provos Exp $");
 
 #include "packet.h"
 #include "xmalloc.h"
@@ -20,7 +20,13 @@ RCSID("$OpenBSD: auth-options.c,v 1.21 2002/01/29 14:32:03 markus Exp $");
 #include "channels.h"
 #include "auth-options.h"
 #include "servconf.h"
+#include "bufaux.h"
 #include "misc.h"
+#include "monitor_wrap.h"
+
+/* Debugging messages */
+Buffer auth_debug;
+int auth_debug_init;
 
 /* Flags set authorized_keys flags */
 int no_port_forwarding_flag = 0;
@@ -37,8 +43,27 @@ struct envstring *custom_environment = NULL;
 extern ServerOptions options;
 
 void
+auth_send_debug(Buffer *m)
+{
+	char *msg;
+
+	while (buffer_len(m)) {
+		msg = buffer_get_string(m, NULL);
+		packet_send_debug("%s", msg);
+		xfree(msg);
+	}
+}
+
+void
 auth_clear_options(void)
 {
+	if (auth_debug_init)
+		buffer_clear(&auth_debug);
+	else {
+		buffer_init(&auth_debug);
+		auth_debug_init = 1;
+	}
+
 	no_agent_forwarding_flag = 0;
 	no_port_forwarding_flag = 0;
 	no_pty_flag = 0;
@@ -63,6 +88,7 @@ auth_clear_options(void)
 int
 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 {
+	char tmp[1024];
 	const char *cp;
 	int i;
 
@@ -75,28 +101,32 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 	while (*opts && *opts != ' ' && *opts != '\t') {
 		cp = "no-port-forwarding";
 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
-			packet_send_debug("Port forwarding disabled.");
+			snprintf(tmp, sizeof(tmp), "Port forwarding disabled.");
+			buffer_put_cstring(&auth_debug, tmp);
 			no_port_forwarding_flag = 1;
 			opts += strlen(cp);
 			goto next_option;
 		}
 		cp = "no-agent-forwarding";
 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
-			packet_send_debug("Agent forwarding disabled.");
+			snprintf(tmp, sizeof(tmp), "Agent forwarding disabled.");
+			buffer_put_cstring(&auth_debug, tmp);
 			no_agent_forwarding_flag = 1;
 			opts += strlen(cp);
 			goto next_option;
 		}
 		cp = "no-X11-forwarding";
 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
-			packet_send_debug("X11 forwarding disabled.");
+			snprintf(tmp, sizeof(tmp), "X11 forwarding disabled.");
+			buffer_put_cstring(&auth_debug, tmp);
 			no_x11_forwarding_flag = 1;
 			opts += strlen(cp);
 			goto next_option;
 		}
 		cp = "no-pty";
 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
-			packet_send_debug("Pty allocation disabled.");
+			snprintf(tmp, sizeof(tmp), "Pty allocation disabled.");
+			buffer_put_cstring(&auth_debug, tmp);
 			no_pty_flag = 1;
 			opts += strlen(cp);
 			goto next_option;
@@ -119,14 +149,16 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 			if (!*opts) {
 				debug("%.100s, line %lu: missing end quote",
 				    file, linenum);
-				packet_send_debug("%.100s, line %lu: missing end quote",
+				snprintf(tmp, sizeof(tmp), "%.100s, line %lu: missing end quote",
 				    file, linenum);
+				buffer_put_cstring(&auth_debug, tmp);
 				xfree(forced_command);
 				forced_command = NULL;
 				goto bad_option;
 			}
 			forced_command[i] = 0;
-			packet_send_debug("Forced command: %.900s", forced_command);
+			snprintf(tmp, sizeof(tmp), "Forced command: %.900s", forced_command);
+			buffer_put_cstring(&auth_debug, tmp);
 			opts++;
 			goto next_option;
 		}
@@ -151,13 +183,15 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 			if (!*opts) {
 				debug("%.100s, line %lu: missing end quote",
 				    file, linenum);
-				packet_send_debug("%.100s, line %lu: missing end quote",
+				snprintf(tmp, sizeof(tmp), "%.100s, line %lu: missing end quote",
 				    file, linenum);
+				buffer_put_cstring(&auth_debug, tmp);
 				xfree(s);
 				goto bad_option;
 			}
 			s[i] = 0;
-			packet_send_debug("Adding to environment: %.900s", s);
+			snprintf(tmp, sizeof(tmp), "Adding to environment: %.900s", s);
+			buffer_put_cstring(&auth_debug, tmp);
 			debug("Adding to environment: %.900s", s);
 			opts++;
 			new_envstring = xmalloc(sizeof(struct envstring));
@@ -188,8 +222,9 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 			if (!*opts) {
 				debug("%.100s, line %lu: missing end quote",
 				    file, linenum);
-				packet_send_debug("%.100s, line %lu: missing end quote",
+				snprintf(tmp, sizeof(tmp), "%.100s, line %lu: missing end quote",
 				    file, linenum);
+				buffer_put_cstring(&auth_debug, tmp);
 				xfree(patterns);
 				goto bad_option;
 			}
@@ -202,9 +237,11 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 				    "correct key but not from a permitted "
 				    "host (host=%.200s, ip=%.200s).",
 				    pw->pw_name, remote_host, remote_ip);
-				packet_send_debug("Your host '%.200s' is not "
+				snprintf(tmp, sizeof(tmp),
+				    "Your host '%.200s' is not "
 				    "permitted to use this key for login.",
 				    remote_host);
+				buffer_put_cstring(&auth_debug, tmp);
 				/* deny access */
 				return 0;
 			}
@@ -233,8 +270,9 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 			if (!*opts) {
 				debug("%.100s, line %lu: missing end quote",
 				    file, linenum);
-				packet_send_debug("%.100s, line %lu: missing end quote",
+				snprintf(tmp, sizeof(tmp), "%.100s, line %lu: missing end quote",
 				    file, linenum);
+				buffer_put_cstring(&auth_debug, tmp);
 				xfree(patterns);
 				goto bad_option;
 			}
@@ -244,16 +282,18 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 			    sscanf(patterns, "%255[^/]/%5[0-9]", host, sport) != 2) {
 				debug("%.100s, line %lu: Bad permitopen specification "
 				    "<%.100s>", file, linenum, patterns);
-				packet_send_debug("%.100s, line %lu: "
+				snprintf(tmp, sizeof(tmp), "%.100s, line %lu: "
 				    "Bad permitopen specification", file, linenum);
+				buffer_put_cstring(&auth_debug, tmp);
 				xfree(patterns);
 				goto bad_option;
 			}
 			if ((port = a2port(sport)) == 0) {
 				debug("%.100s, line %lu: Bad permitopen port <%.100s>",
 				    file, linenum, sport);
-				packet_send_debug("%.100s, line %lu: "
+				snprintf(tmp, sizeof(tmp), "%.100s, line %lu: "
 				    "Bad permitopen port", file, linenum);
+				buffer_put_cstring(&auth_debug, tmp);
 				xfree(patterns);
 				goto bad_option;
 			}
@@ -276,14 +316,24 @@ next_option:
 		opts++;
 		/* Process the next option. */
 	}
+
+	if (!use_privsep)
+		auth_send_debug(&auth_debug);
+
 	/* grant access */
 	return 1;
 
 bad_option:
 	log("Bad options in %.100s file, line %lu: %.50s",
 	    file, linenum, opts);
-	packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
+	snprintf(tmp, sizeof(tmp),
+	    "Bad options in %.100s file, line %lu: %.50s",
 	    file, linenum, opts);
+	buffer_put_cstring(&auth_debug, tmp);
+
+	if (!use_privsep)
+		auth_send_debug(&auth_debug);
+
 	/* deny access */
 	return 0;
 }
diff --git a/auth-rh-rsa.c b/auth-rh-rsa.c
index 2a88e18b..c940ec58 100644
--- a/auth-rh-rsa.c
+++ b/auth-rh-rsa.c
@@ -13,7 +13,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth-rh-rsa.c,v 1.31 2002/03/16 17:22:09 markus Exp $");
+RCSID("$OpenBSD: auth-rh-rsa.c,v 1.32 2002/03/18 17:50:31 provos Exp $");
 
 #include "packet.h"
 #include "uidswap.h"
@@ -25,6 +25,8 @@ RCSID("$OpenBSD: auth-rh-rsa.c,v 1.31 2002/03/16 17:22:09 markus Exp $");
 #include "auth.h"
 #include "canohost.h"
 
+#include "monitor_wrap.h"
+
 /* import */
 extern ServerOptions options;
 
@@ -69,7 +71,7 @@ auth_rhosts_rsa(struct passwd *pw, char *cuser, Key *client_host_key)
 	chost = (char *)get_canonical_hostname(options.verify_reverse_mapping);
 	debug("Rhosts RSA authentication: canonical host %.900s", chost);
 
-	if (!auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key)) {
+	if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
 		debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
 		packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
 		return 0;
diff --git a/auth-rsa.c b/auth-rsa.c
index ff9bf3b6..9c5d484b 100644
--- a/auth-rsa.c
+++ b/auth-rsa.c
@@ -14,7 +14,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth-rsa.c,v 1.51 2002/03/14 16:56:33 markus Exp $");
+RCSID("$OpenBSD: auth-rsa.c,v 1.52 2002/03/18 17:50:31 provos Exp $");
 
 #include <openssl/rsa.h>
 #include <openssl/md5.h>
@@ -32,6 +32,7 @@ RCSID("$OpenBSD: auth-rsa.c,v 1.51 2002/03/14 16:56:33 markus Exp $");
 #include "servconf.h"
 #include "auth.h"
 #include "hostfile.h"
+#include "monitor_wrap.h"
 
 /* import */
 extern ServerOptions options;
@@ -52,7 +53,7 @@ extern u_char session_id[16];
  * description of the options.
  */
 
-static BIGNUM *
+BIGNUM *
 auth_rsa_generate_challenge(Key *key)
 {
 	BIGNUM *challenge;
@@ -70,7 +71,7 @@ auth_rsa_generate_challenge(Key *key)
 	return challenge;
 }
 
-static int
+int
 auth_rsa_verify_response(Key *key, BIGNUM *challenge, u_char response[16])
 {
 	u_char buf[32], mdbuf[16];
@@ -113,7 +114,7 @@ auth_rsa_challenge_dialog(Key *key)
 	if ((encrypted_challenge = BN_new()) == NULL)
 		fatal("auth_rsa_challenge_dialog: BN_new() failed");
 
-	challenge = auth_rsa_generate_challenge(key);
+	challenge = PRIVSEP(auth_rsa_generate_challenge(key));
 
 	/* Encrypt the challenge with the public key. */
 	rsa_public_encrypt(encrypted_challenge, challenge, key->rsa);
@@ -131,7 +132,7 @@ auth_rsa_challenge_dialog(Key *key)
 		response[i] = packet_get_char();
 	packet_check_eom();
 
-	success = auth_rsa_verify_response(key, challenge, response);
+	success = PRIVSEP(auth_rsa_verify_response(key, challenge, response));
 	BN_clear_free(challenge);
 	return (success);
 }
@@ -141,11 +142,11 @@ auth_rsa_challenge_dialog(Key *key)
  * return key if login is allowed, NULL otherwise
  */
 
-static int
+int
 auth_rsa_key_allowed(struct passwd *pw, BIGNUM *client_n, Key **rkey)
 {
 	char line[8192], *file;
-	int allowed;
+	int allowed = 0;
 	u_int bits;
 	FILE *f;
 	u_long linenum = 0;
@@ -284,7 +285,7 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n)
 	if (pw == NULL)
 		return 0;
 
-	if (auth_rsa_key_allowed(pw, client_n, &key) == 0) {
+	if (!PRIVSEP(auth_rsa_key_allowed(pw, client_n, &key))) {
 		auth_clear_options();
 		return (0);
 	}
diff --git a/auth-skey.c b/auth-skey.c
index df19f750..e897d187 100644
--- a/auth-skey.c
+++ b/auth-skey.c
@@ -22,7 +22,7 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include "includes.h"
-RCSID("$OpenBSD: auth-skey.c,v 1.16 2002/01/12 13:10:29 markus Exp $");
+RCSID("$OpenBSD: auth-skey.c,v 1.17 2002/03/18 17:50:31 provos Exp $");
 
 #ifdef SKEY
 
@@ -30,6 +30,7 @@ RCSID("$OpenBSD: auth-skey.c,v 1.16 2002/01/12 13:10:29 markus Exp $");
 
 #include "xmalloc.h"
 #include "auth.h"
+#include "monitor_wrap.h"
 
 static void *
 skey_init_ctx(Authctxt *authctxt)
@@ -37,8 +38,6 @@ skey_init_ctx(Authctxt *authctxt)
 	return authctxt;
 }
 
-#define PROMPT "\nS/Key Password: "
-
 static int
 skey_query(void *ctx, char **name, char **infotxt,
     u_int* numprompts, char ***prompts, u_int **echo_on)
@@ -58,10 +57,10 @@ skey_query(void *ctx, char **name, char **infotxt,
 	*echo_on = xmalloc(*numprompts * sizeof(u_int));
 	(*echo_on)[0] = 0;
 
-	len = strlen(challenge) + strlen(PROMPT) + 1;
+	len = strlen(challenge) + strlen(SKEY_PROMPT) + 1;
 	p = xmalloc(len);
 	strlcpy(p, challenge, len);
-	strlcat(p, PROMPT, len);
+	strlcat(p, SKEY_PROMPT, len);
 	(*prompts)[0] = p;
 
 	return 0;
@@ -93,4 +92,12 @@ KbdintDevice skey_device = {
 	skey_respond,
 	skey_free_ctx
 };
+
+KbdintDevice mm_skey_device = {
+	"skey",
+	skey_init_ctx,
+	mm_skey_query,
+	mm_skey_respond,
+	skey_free_ctx
+};
 #endif /* SKEY */
diff --git a/auth.h b/auth.h
index bdfdf1c5..3e4a5501 100644
--- a/auth.h
+++ b/auth.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: auth.h,v 1.33 2002/03/18 01:12:14 provos Exp $	*/
+/*	$OpenBSD: auth.h,v 1.34 2002/03/18 17:50:31 provos Exp $	*/
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -129,6 +129,8 @@ void	auth_log(Authctxt *, int, char *, char *);
 void	userauth_finish(Authctxt *, int, char *);
 int	auth_root_allowed(char *);
 
+void	privsep_challenge_enable(void);
+
 int	auth2_challenge(Authctxt *, char *);
 void	auth2_challenge_stop(Authctxt *);
 
@@ -155,4 +157,5 @@ check_key_in_hostfiles(struct passwd *, Key *, const char *,
 #define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2)
 #define AUTH_FAIL_MSG "Too many authentication failures for %.100s"
 
+#define SKEY_PROMPT "\nS/Key Password: "
 #endif
diff --git a/auth1.c b/auth1.c
index 4c295215..ca288958 100644
--- a/auth1.c
+++ b/auth1.c
@@ -10,7 +10,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth1.c,v 1.37 2002/03/18 01:12:14 provos Exp $");
+RCSID("$OpenBSD: auth1.c,v 1.38 2002/03/18 17:50:31 provos Exp $");
 
 #include "xmalloc.h"
 #include "rsa.h"
@@ -26,6 +26,7 @@ RCSID("$OpenBSD: auth1.c,v 1.37 2002/03/18 01:12:14 provos Exp $");
 #include "session.h"
 #include "misc.h"
 #include "uidswap.h"
+#include "monitor_wrap.h"
 
 /* import */
 extern ServerOptions options;
@@ -89,7 +90,7 @@ do_authloop(Authctxt *authctxt)
 #elif defined(HAVE_OSF_SIA)
 	    0) {
 #else
-	    auth_password(authctxt, "")) {
+	    PRIVSEP(auth_password(authctxt, ""))) {
 #endif
 		auth_log(authctxt, 1, "without authentication", "");
 		return;
@@ -253,9 +254,8 @@ do_authloop(Authctxt *authctxt)
 			/* Do SIA auth with password */
 			authenticated = auth_sia_password(authctxt->user, 
 			    password);
-#else /* !USE_PAM && !HAVE_OSF_SIA */
 			/* Try authentication with the password. */
-			authenticated = auth_password(authctxt, password);
+			authenticated = PRIVSEP(auth_password(authctxt, password));
 #endif /* USE_PAM */
 
 			memset(password, 0, strlen(password));
@@ -359,7 +359,7 @@ Authctxt *
 do_authentication(void)
 {
 	Authctxt *authctxt;
-	struct passwd *pw;
+	struct passwd *pw = NULL, *pwent;
 	u_int ulen;
 	char *p, *user, *style = NULL;
 
@@ -382,17 +382,22 @@ do_authentication(void)
 	authctxt->style = style;
 
 	/* Verify that the user is a valid user. */
-	pw = getpwnamallow(user);
-	if (pw) {
+	pwent = PRIVSEP(getpwnamallow(user));
+	if (pwent) {
 		authctxt->valid = 1;
-		pw = pwcopy(pw);
+		pw = pwcopy(pwent);
 	} else {
 		debug("do_authentication: illegal user %s", user);
 		pw = NULL;
 	}
+	/* Free memory */
+	if (use_privsep && pwent != NULL)
+		pwfree(pwent);
+
 	authctxt->pw = pw;
 
-	setproctitle("%s", pw ? user : "unknown");
+	setproctitle("%s%s", pw ? user : "unknown",
+	    use_privsep ? " [net]" : "");
 
 #ifdef USE_PAM
 	start_pam(pw == NULL ? "NOUSER" : user);
@@ -403,7 +408,7 @@ do_authentication(void)
 	 * the server. (Unless you are running Windows)
 	 */
 #ifndef HAVE_CYGWIN
-	if (getuid() != 0 && pw && pw->pw_uid != getuid())
+	if (!use_privsep && getuid() != 0 && pw && pw->pw_uid != getuid())
 		packet_disconnect("Cannot change user when server not running as root.");
 #endif
 
diff --git a/auth2-chall.c b/auth2-chall.c
index 9f1d9327..38f955a0 100644
--- a/auth2-chall.c
+++ b/auth2-chall.c
@@ -23,7 +23,7 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include "includes.h"
-RCSID("$OpenBSD: auth2-chall.c,v 1.16 2002/01/13 17:57:37 markus Exp $");
+RCSID("$OpenBSD: auth2-chall.c,v 1.17 2002/03/18 17:50:31 provos Exp $");
 
 #include "ssh2.h"
 #include "auth.h"
@@ -310,3 +310,22 @@ input_userauth_info_response(int type, u_int32_t seq, void *ctxt)
 	userauth_finish(authctxt, authenticated, method);
 	xfree(method);
 }
+
+void
+privsep_challenge_enable(void)
+{
+#ifdef BSD_AUTH
+	extern KbdintDevice mm_bsdauth_device;
+#endif
+#ifdef SKEY
+	extern KbdintDevice mm_skey_device;
+#endif
+	/* As long as SSHv1 has devices[0] hard coded this is fine */
+#ifdef BSD_AUTH
+	devices[0] = &mm_bsdauth_device;
+#else
+#ifdef SKEY
+	devices[0] = &mm_skey_device;
+#endif
+#endif
+}
diff --git a/auth2.c b/auth2.c
index b57fda21..9bfcde5c 100644
--- a/auth2.c
+++ b/auth2.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth2.c,v 1.87 2002/03/18 01:12:14 provos Exp $");
+RCSID("$OpenBSD: auth2.c,v 1.88 2002/03/18 17:50:31 provos Exp $");
 
 #include <openssl/evp.h>
 
@@ -51,13 +51,14 @@ RCSID("$OpenBSD: auth2.c,v 1.87 2002/03/18 01:12:14 provos Exp $");
 #include "hostfile.h"
 #include "canohost.h"
 #include "match.h"
+#include "monitor_wrap.h"
 
 /* import */
 extern ServerOptions options;
 extern u_char *session_id2;
 extern int session_id2_len;
 
-static Authctxt	*x_authctxt = NULL;
+Authctxt *x_authctxt = NULL;
 static int one = 1;
 
 typedef struct Authmethod Authmethod;
@@ -75,8 +76,8 @@ static void input_userauth_request(int, u_int32_t, void *);
 /* helper */
 static Authmethod *authmethod_lookup(const char *);
 static char *authmethods_get(void);
-static int user_key_allowed(struct passwd *, Key *);
-static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
+int user_key_allowed(struct passwd *, Key *);
+int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
 
 /* auth */
 static void userauth_banner(void);
@@ -185,7 +186,7 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
 	if (authctxt->attempt++ == 0) {
 		/* setup auth context */
 		struct passwd *pw = NULL;
-		pw = getpwnamallow(user);
+		pw = PRIVSEP(getpwnamallow(user));
 		if (pw && strcmp(service, "ssh-connection")==0) {
 			authctxt->pw = pwcopy(pw);
 			authctxt->valid = 1;
@@ -199,10 +200,18 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
 			start_pam("NOUSER");
 #endif
 		}
-		setproctitle("%s", pw ? user : "unknown");
+		/* Free memory */
+		if (use_privsep && pw != NULL)
+			pwfree(pw);
+
+		setproctitle("%s%s", pw ? user : "unknown",
+		    use_privsep ? " [net]" : "");
 		authctxt->user = xstrdup(user);
 		authctxt->service = xstrdup(service);
 		authctxt->style = style ? xstrdup(style) : NULL;
+
+		if (use_privsep)
+			mm_inform_authserv(service, style);
 	} else if (strcmp(user, authctxt->user) != 0 ||
 	    strcmp(service, authctxt->service) != 0) {
 		packet_disconnect("Change of username or service not allowed: "
@@ -333,7 +342,7 @@ userauth_none(Authctxt *authctxt)
 #elif defined(HAVE_OSF_SIA)
 	return 0;
 #else /* !HAVE_OSF_SIA && !USE_PAM */
-	return auth_password(authctxt, "");
+	return PRIVSEP(auth_password(authctxt, ""));
 #endif /* USE_PAM */
 }
 
@@ -358,7 +367,7 @@ userauth_passwd(Authctxt *authctxt)
 #elif defined(HAVE_OSF_SIA)
 	    auth_sia_password(authctxt->user, password) == 1)
 #else /* !USE_PAM && !HAVE_OSF_SIA */
-	    auth_password(authctxt, password) == 1)
+	    PRIVSEP(auth_password(authctxt, password)) == 1)
 #endif /* USE_PAM */
 		authenticated = 1;
 	memset(password, 0, len);
@@ -468,8 +477,10 @@ userauth_pubkey(Authctxt *authctxt)
 		buffer_dump(&b);
 #endif
 		/* test for correct signature */
-		if (user_key_allowed(authctxt->pw, key) &&
-		    key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
+		authenticated = 0;
+		if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
+		    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
+				buffer_len(&b))) == 1)
 			authenticated = 1;
 		buffer_clear(&b);
 		xfree(sig);
@@ -485,7 +496,7 @@ userauth_pubkey(Authctxt *authctxt)
 		 * if a user is not allowed to login. is this an
 		 * issue? -markus
 		 */
-		if (user_key_allowed(authctxt->pw, key)) {
+		if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
 			packet_start(SSH2_MSG_USERAUTH_PK_OK);
 			packet_put_string(pkalg, alen);
 			packet_put_string(pkblob, blen);
@@ -573,8 +584,10 @@ userauth_hostbased(Authctxt *authctxt)
 	buffer_dump(&b);
 #endif
 	/* test for allowed key and correct signature */
-	if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) &&
-	    key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
+	authenticated = 0;
+	if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
+	    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
+			buffer_len(&b))) == 1)
 		authenticated = 1;
 
 	buffer_clear(&b);
@@ -731,7 +744,7 @@ user_key_allowed2(struct passwd *pw, Key *key, char *file)
 }
 
 /* check whether given key is in .ssh/authorized_keys* */
-static int
+int
 user_key_allowed(struct passwd *pw, Key *key)
 {
 	int success;
@@ -751,7 +764,7 @@ user_key_allowed(struct passwd *pw, Key *key)
 }
 
 /* return 1 if given hostkey is allowed */
-static int
+int
 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
     Key *key)
 {
diff --git a/kex.c b/kex.c
index bf8fd95b..8097ab0f 100644
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.47 2002/02/28 15:46:33 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.48 2002/03/18 17:50:31 provos Exp $");
 
 #include <openssl/crypto.h>
 
@@ -40,9 +40,15 @@ RCSID("$OpenBSD: kex.c,v 1.47 2002/02/28 15:46:33 markus Exp $");
 #include "mac.h"
 #include "match.h"
 #include "dispatch.h"
+#include "monitor.h"
 
 #define KEX_COOKIE_LEN	16
 
+/* Use privilege separation for sshd */
+int use_privsep;
+struct monitor *monitor;
+
+
 /* prototype */
 static void kex_kexinit_finish(Kex *);
 static void kex_choose_conf(Kex *);
diff --git a/kex.h b/kex.h
index 755bf332..2d3523a3 100644
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kex.h,v 1.29 2002/02/14 23:41:01 markus Exp $	*/
+/*	$OpenBSD: kex.h,v 1.30 2002/03/18 17:50:31 provos Exp $	*/
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -111,6 +111,7 @@ struct Kex {
 	char	*server_version_string;
 	int	(*verify_host_key)(Key *);
 	Key	*(*load_host_key)(int);
+	int	(*host_key_index)(Key *);
 };
 
 Kex	*kex_setup(char *[PROPOSAL_MAX]);
diff --git a/kexdh.c b/kexdh.c
index eaf497ca..1e91e255 100644
--- a/kexdh.c
+++ b/kexdh.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kexdh.c,v 1.17 2002/02/28 15:46:33 markus Exp $");
+RCSID("$OpenBSD: kexdh.c,v 1.18 2002/03/18 17:50:31 provos Exp $");
 
 #include <openssl/crypto.h>
 #include <openssl/bn.h>
@@ -37,6 +37,7 @@ RCSID("$OpenBSD: kexdh.c,v 1.17 2002/02/28 15:46:33 markus Exp $");
 #include "packet.h"
 #include "dh.h"
 #include "ssh2.h"
+#include "monitor_wrap.h"
 
 static u_char *
 kex_dh_hash(
@@ -275,7 +276,7 @@ kexdh_server(Kex *kex)
 
 	/* sign H */
 	/* XXX hashlen depends on KEX */
-	key_sign(server_host_key, &signature, &slen, hash, 20);
+	PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, 20));
 
 	/* destroy_sensitive_data(); */
 
diff --git a/kexgex.c b/kexgex.c
index 61896e6e..7379e8d1 100644
--- a/kexgex.c
+++ b/kexgex.c
@@ -24,7 +24,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kexgex.c,v 1.20 2002/02/28 15:46:33 markus Exp $");
+RCSID("$OpenBSD: kexgex.c,v 1.21 2002/03/18 17:50:31 provos Exp $");
 
 #include <openssl/bn.h>
 
@@ -38,6 +38,7 @@ RCSID("$OpenBSD: kexgex.c,v 1.20 2002/02/28 15:46:33 markus Exp $");
 #include "dh.h"
 #include "ssh2.h"
 #include "compat.h"
+#include "monitor_wrap.h"
 
 static u_char *
 kexgex_hash(
@@ -296,7 +297,8 @@ kexgex_server(Kex *kex)
 		fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
 		    min, nbits, max);
 
-	dh = choose_dh(min, nbits, max);
+	/* Contact privileged parent */
+	dh = PRIVSEP(choose_dh(min, nbits, max));
 	if (dh == NULL)
 		packet_disconnect("Protocol error: no matching DH grp found");
 
@@ -379,7 +381,7 @@ kexgex_server(Kex *kex)
 
 	/* sign H */
 	/* XXX hashlen depends on KEX */
-	key_sign(server_host_key, &signature, &slen, hash, 20);
+	PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, 20));
 
 	/* destroy_sensitive_data(); */
 
@@ -390,6 +392,7 @@ kexgex_server(Kex *kex)
 	packet_put_bignum2(dh->pub_key);	/* f */
 	packet_put_string(signature, slen);
 	packet_send();
+
 	xfree(signature);
 	xfree(server_host_key_blob);
 	/* have keys, free DH */
diff --git a/monitor.c b/monitor.c
new file mode 100644
index 00000000..921ad985
--- /dev/null
+++ b/monitor.c
@@ -0,0 +1,1440 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * Copyright 2002 Markus Friedl <markus@openbsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD: monitor.c,v 1.6 2002/03/21 18:38:33 stevesk Exp $");
+
+#include <openssl/dh.h>
+
+#ifdef SKEY
+#include <skey.h>
+#endif
+
+#include "ssh.h"
+#include "auth.h"
+#include "kex.h"
+#include "dh.h"
+#include "zlib.h"
+#include "packet.h"
+#include "auth-options.h"
+#include "sshpty.h"
+#include "channels.h"
+#include "session.h"
+#include "sshlogin.h"
+#include "canohost.h"
+#include "log.h"
+#include "servconf.h"
+#include "monitor.h"
+#include "monitor_mm.h"
+#include "monitor_wrap.h"
+#include "monitor_fdpass.h"
+#include "xmalloc.h"
+#include "misc.h"
+#include "buffer.h"
+#include "bufaux.h"
+#include "compat.h"
+#include "ssh2.h"
+#include "mpaux.h"
+
+/* Imports */
+extern ServerOptions options;
+extern u_int utmp_len;
+extern Newkeys *current_keys[];
+extern z_stream incoming_stream;
+extern z_stream outgoing_stream;
+extern u_char session_id[];
+extern Buffer input, output;
+extern Buffer auth_debug;
+extern int auth_debug_init;
+
+/* State exported from the child */
+
+struct {
+	z_stream incoming;
+	z_stream outgoing;
+	u_char *keyin;
+	u_int keyinlen;
+	u_char *keyout;
+	u_int keyoutlen;
+	u_char *ivin;
+	u_int ivinlen;
+	u_char *ivout;
+	u_int ivoutlen;
+	int ssh1cipher;
+	int ssh1protoflags;
+	u_char *input;
+	u_int ilen;
+	u_char *output;
+	u_int olen;
+} child_state;
+
+/* Functions on the montior that answer unprivileged requests */
+
+int mm_answer_moduli(int, Buffer *);
+int mm_answer_sign(int, Buffer *);
+int mm_answer_pwnamallow(int, Buffer *);
+int mm_answer_authserv(int, Buffer *);
+int mm_answer_authpassword(int, Buffer *);
+int mm_answer_bsdauthquery(int, Buffer *);
+int mm_answer_bsdauthrespond(int, Buffer *);
+int mm_answer_skeyquery(int, Buffer *);
+int mm_answer_skeyrespond(int, Buffer *);
+int mm_answer_keyallowed(int, Buffer *);
+int mm_answer_keyverify(int, Buffer *);
+int mm_answer_pty(int, Buffer *);
+int mm_answer_pty_cleanup(int, Buffer *);
+int mm_answer_term(int, Buffer *);
+int mm_answer_rsa_keyallowed(int, Buffer *);
+int mm_answer_rsa_challenge(int, Buffer *);
+int mm_answer_rsa_response(int, Buffer *);
+int mm_answer_sesskey(int, Buffer *);
+int mm_answer_sessid(int, Buffer *);
+
+static Authctxt *authctxt;
+static BIGNUM *ssh1_challenge = NULL;	/* used for ssh1 rsa auth */
+
+/* local state for key verify */
+static u_char *key_blob = NULL;
+static u_int key_bloblen = 0;
+static int key_blobtype = MM_NOKEY;
+static u_char *hostbased_cuser = NULL;
+static u_char *hostbased_chost = NULL;
+static char *auth_method = "unknown";
+
+struct mon_table {
+	enum monitor_reqtype type;
+	int flags;
+	int (*f)(int, Buffer *);
+};
+
+#define MON_ISAUTH	0x0004	/* Required for Authentication */
+#define MON_AUTHDECIDE	0x0008	/* Decides Authentication */
+#define MON_ONCE	0x0010	/* Disable after calling */
+
+#define MON_AUTH	(MON_ISAUTH|MON_AUTHDECIDE)
+
+#define MON_PERMIT	0x1000	/* Request is permitted */
+
+struct mon_table mon_dispatch_proto20[] = {
+    {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
+    {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign},
+    {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
+    {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv},
+    {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
+#ifdef BSD_AUTH
+    {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
+    {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH,mm_answer_bsdauthrespond},
+#endif
+#ifdef SKEY
+    {MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery},
+    {MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond},
+#endif
+    {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
+    {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify},
+    {0, 0, NULL}
+};
+
+struct mon_table mon_dispatch_postauth20[] = {
+    {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
+    {MONITOR_REQ_SIGN, 0, mm_answer_sign},
+    {MONITOR_REQ_PTY, 0, mm_answer_pty},
+    {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup},
+    {MONITOR_REQ_TERM, 0, mm_answer_term},
+    {0, 0, NULL}
+};
+
+struct mon_table mon_dispatch_proto15[] = {
+    {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
+    {MONITOR_REQ_SESSKEY, MON_ONCE, mm_answer_sesskey},
+    {MONITOR_REQ_SESSID, MON_ONCE, mm_answer_sessid},
+    {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
+    {MONITOR_REQ_RSAKEYALLOWED, MON_ISAUTH, mm_answer_rsa_keyallowed},
+    {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
+    {MONITOR_REQ_RSACHALLENGE, MON_ONCE, mm_answer_rsa_challenge},
+    {MONITOR_REQ_RSARESPONSE, MON_ONCE|MON_AUTHDECIDE, mm_answer_rsa_response},
+#ifdef BSD_AUTH
+    {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
+    {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH,mm_answer_bsdauthrespond},
+#endif
+#ifdef SKEY
+    {MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery},
+    {MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond},
+#endif
+    {0, 0, NULL}
+};
+
+struct mon_table mon_dispatch_postauth15[] = {
+    {MONITOR_REQ_PTY, MON_ONCE, mm_answer_pty},
+    {MONITOR_REQ_PTYCLEANUP, MON_ONCE, mm_answer_pty_cleanup},
+    {MONITOR_REQ_TERM, 0, mm_answer_term},
+    {0, 0, NULL}
+};
+
+struct mon_table *mon_dispatch;
+
+/* Specifies if a certain message is allowed at the moment */
+
+static void
+monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
+{
+	while (ent->f != NULL) {
+		if (ent->type == type) {
+			ent->flags &= ~MON_PERMIT;
+			ent->flags |= permit ? MON_PERMIT : 0;
+			return;
+		}
+		ent++;
+	}
+}
+
+static void
+monitor_permit_authentications(int permit)
+{
+	struct mon_table *ent = mon_dispatch;
+
+	while (ent->f != NULL) {
+		if (ent->flags & MON_AUTH) {
+			ent->flags &= ~MON_PERMIT;
+			ent->flags |= permit ? MON_PERMIT : 0;
+		}
+		ent++;
+	}
+}
+
+Authctxt *
+monitor_child_preauth(struct monitor *monitor)
+{
+	struct mon_table *ent;
+	int authenticated = 0;
+
+	debug3("preauth child monitor started");
+
+	if (compat20) {
+		mon_dispatch = mon_dispatch_proto20;
+
+		/* Permit requests for moduli and signatures */
+		monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
+		monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
+	} else {
+		mon_dispatch = mon_dispatch_proto15;
+
+		monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 1);
+	}
+
+	authctxt = authctxt_new();
+
+	/* The first few requests do not require asynchronous access */
+	while (!authenticated) {
+		authenticated = monitor_read(monitor, mon_dispatch, &ent);
+		if (authenticated) {
+			if (!(ent->flags & MON_AUTHDECIDE))
+				fatal("%s: unexpected authentication from %d",
+				    __FUNCTION__, ent->type);
+			if (authctxt->pw->pw_uid == 0 &&
+			    !auth_root_allowed(auth_method))
+				authenticated = 0;
+		}
+
+		if (ent->flags & MON_AUTHDECIDE) {
+			auth_log(authctxt, authenticated, auth_method,
+			    compat20 ? " ssh2" : "");
+			if (!authenticated)
+				authctxt->failures++;
+		}
+	}
+
+	if (!authctxt->valid)
+		fatal("%s: authenticated invalid user", __FUNCTION__);
+
+	debug("%s: %s has been authenticated by privileged process",
+	    __FUNCTION__, authctxt->user);
+
+	mm_get_keystate(monitor);
+
+	return (authctxt);
+}
+
+void
+monitor_child_postauth(struct monitor *monitor)
+{
+	if (compat20) {
+		mon_dispatch = mon_dispatch_postauth20;
+
+		/* Permit requests for moduli and signatures */
+		monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
+		monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
+		monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
+
+	} else {
+		mon_dispatch = mon_dispatch_postauth15;
+		monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
+	}
+	if (!no_pty_flag) {
+		monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
+		monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
+	}
+
+	for (;;)
+		monitor_read(monitor, mon_dispatch, NULL);
+}
+
+void
+monitor_sync(struct monitor *monitor)
+{
+	/* The member allocation is not visible, so sync it */
+	mm_share_sync(&monitor->m_zlib, &monitor->m_zback);
+}
+
+int
+monitor_read(struct monitor *monitor, struct mon_table *ent,
+    struct mon_table **pent)
+{
+	Buffer m;
+	int ret;
+	u_char type;
+
+	buffer_init(&m);
+
+	mm_request_receive(monitor->m_sendfd, &m);
+	type = buffer_get_char(&m);
+
+	debug3("%s: checking request %d", __FUNCTION__, type);
+
+	while (ent->f != NULL) {
+		if (ent->type == type)
+			break;
+		ent++;
+	}
+
+	if (ent->f != NULL) {
+		if (!(ent->flags & MON_PERMIT))
+			fatal("%s: unpermitted request %d", __FUNCTION__,
+			    type);
+		ret = (*ent->f)(monitor->m_sendfd, &m);
+		buffer_free(&m);
+
+		/* The child may use this request only once, disable it */
+		if (ent->flags & MON_ONCE) {
+			debug2("%s: %d used once, disabling now", __FUNCTION__,
+			    type);
+			ent->flags &= ~MON_PERMIT;
+		}
+
+		if (pent != NULL)
+			*pent = ent;
+
+		return ret;
+	}
+
+	fatal("%s: unsupported request: %d\n", __FUNCTION__, type);
+
+	/* NOTREACHED */
+	return (-1);
+}
+
+/* allowed key state */
+static int
+monitor_allowed_key(u_char *blob, u_int bloblen)
+{
+	/* make sure key is allowed */
+	if (key_blob == NULL || key_bloblen != bloblen ||
+	    memcmp(key_blob, blob, key_bloblen))
+		return (0);
+	return (1);
+}
+
+static void
+monitor_reset_key_state(void)
+{
+	/* reset state */
+	if (key_blob != NULL)
+		xfree(key_blob);
+	if (hostbased_cuser != NULL)
+		xfree(hostbased_cuser);
+	if (hostbased_chost != NULL)
+		xfree(hostbased_chost);
+	key_blob = NULL;
+	key_bloblen = 0;
+	key_blobtype = MM_NOKEY;
+	hostbased_cuser = NULL;
+	hostbased_chost = NULL;
+}
+
+int
+mm_answer_moduli(int socket, Buffer *m)
+{
+	DH *dh;
+	int min, want, max;
+
+	min = buffer_get_int(m);
+	want = buffer_get_int(m);
+	max = buffer_get_int(m);
+
+	debug3("%s: got parameters: %d %d %d",
+	    __FUNCTION__, min, want, max);
+	/* We need to check here, too, in case the child got corrupted */
+	if (max < min || want < min || max < want)
+		fatal("%s: bad parameters: %d %d %d",
+		    __FUNCTION__, min, want, max);
+
+	buffer_clear(m);
+
+	dh = choose_dh(min, want, max);
+	if (dh == NULL) {
+		buffer_put_char(m, 0);
+		return (0);
+	} else {
+		/* Send first bignum */
+		buffer_put_char(m, 1);
+		buffer_put_bignum2(m, dh->p);
+		buffer_put_bignum2(m, dh->g);
+
+		DH_free(dh);
+	}
+	mm_request_send(socket, MONITOR_ANS_MODULI, m);
+	return (0);
+}
+
+int
+mm_answer_sign(int socket, Buffer *m)
+{
+	Key *key;
+	u_char *p;
+	u_char *signature;
+	u_int siglen, datlen;
+	int keyid;
+
+	debug3("%s", __FUNCTION__);
+
+	keyid = buffer_get_int(m);
+	p = buffer_get_string(m, &datlen);
+
+	if (datlen != 20)
+		fatal("%s: data length incorrect: %d", __FUNCTION__, datlen);
+
+	if ((key = get_hostkey_by_index(keyid)) == NULL)
+		fatal("%s: no hostkey from index %d", __FUNCTION__, keyid);
+	if (key_sign(key, &signature, &siglen, p, datlen) < 0)
+		fatal("%s: key_sign failed", __FUNCTION__);
+
+	debug3("%s: signature %p(%d)", __FUNCTION__, signature, siglen);
+
+	buffer_clear(m);
+	buffer_put_string(m, signature, siglen);
+
+	xfree(p);
+	xfree(signature);
+
+	mm_request_send(socket, MONITOR_ANS_SIGN, m);
+
+	/* Turn on permissions for getpwnam */
+	monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
+
+	return (0);
+}
+
+/* Retrieves the password entry and also checks if the user is permitted */
+
+int
+mm_answer_pwnamallow(int socket, Buffer *m)
+{
+	char *login;
+	struct passwd *pwent;
+	int allowed = 0;
+
+	debug3("%s", __FUNCTION__);
+
+	if (authctxt->attempt++ != 0)
+		fatal("%s: multiple attempts for getpwnam", __FUNCTION__);
+
+	login = buffer_get_string(m, NULL);
+
+	pwent = getpwnamallow(login);
+
+	authctxt->user = xstrdup(login);
+	setproctitle("%s [priv]", pwent ? login : "unknown");
+	xfree(login);
+
+	buffer_clear(m);
+
+	if (pwent == NULL) {
+		buffer_put_char(m, 0);
+		goto out;
+	}
+
+	allowed = 1;
+	authctxt->pw = pwent;
+	authctxt->valid = 1;
+
+	buffer_put_char(m, 1);
+	buffer_put_string(m, pwent, sizeof(struct passwd));
+	buffer_put_cstring(m, pwent->pw_name);
+	buffer_put_cstring(m, "*");
+	buffer_put_cstring(m, pwent->pw_gecos);
+	buffer_put_cstring(m, pwent->pw_class);
+	buffer_put_cstring(m, pwent->pw_dir);
+	buffer_put_cstring(m, pwent->pw_shell);
+
+ out:
+	debug3("%s: sending MONITOR_ANS_PWNAM: %d", __FUNCTION__, allowed);
+	mm_request_send(socket, MONITOR_ANS_PWNAM, m);
+
+	/* For SSHv1 allow authentication now */
+	if (!compat20)
+		monitor_permit_authentications(1);
+	else
+		/* Allow service/style information on the auth context */
+		monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
+
+
+	return (0);
+}
+
+int
+mm_answer_authserv(int socket, Buffer *m)
+{
+	monitor_permit_authentications(1);
+
+	authctxt->service = buffer_get_string(m, NULL);
+	authctxt->style = buffer_get_string(m, NULL);
+	debug3("%s: service=%s, style=%s",
+	    __FUNCTION__, authctxt->service, authctxt->style);
+
+	if (strlen(authctxt->style) == 0) {
+		xfree(authctxt->style);
+		authctxt->style = NULL;
+	}
+
+	return (0);
+}
+
+int
+mm_answer_authpassword(int socket, Buffer *m)
+{
+	static int call_count;
+	char *passwd;
+	int authenticated, plen;
+
+	passwd = buffer_get_string(m, &plen);
+	/* Only authenticate if the context is valid */
+	authenticated = authctxt->valid && auth_password(authctxt, passwd);
+	memset(passwd, 0, strlen(passwd));
+	xfree(passwd);
+
+	buffer_clear(m);
+	buffer_put_int(m, authenticated);
+
+	debug3("%s: sending result %d", __FUNCTION__, authenticated);
+	mm_request_send(socket, MONITOR_ANS_AUTHPASSWORD, m);
+
+	call_count++;
+	if (plen == 0 && call_count == 1)
+		auth_method = "none";
+	else
+		auth_method = "password";
+
+	/* Causes monitor loop to terminate if authenticated */
+	return (authenticated);
+}
+
+#ifdef BSD_AUTH
+int
+mm_answer_bsdauthquery(int socket, Buffer *m)
+{
+	char *name, *infotxt;
+	u_int numprompts;
+	u_int *echo_on;
+	char **prompts;
+	int res;
+
+	res = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
+	    &prompts, &echo_on);
+
+	buffer_clear(m);
+	buffer_put_int(m, res);
+	if (res != -1)
+		buffer_put_cstring(m, prompts[0]);
+
+	debug3("%s: sending challenge res: %d", __FUNCTION__, res);
+	mm_request_send(socket, MONITOR_ANS_BSDAUTHQUERY, m);
+
+	if (res != -1) {
+		xfree(name);
+		xfree(infotxt);
+		xfree(prompts);
+		xfree(echo_on);
+	}
+
+	return (0);
+}
+
+int
+mm_answer_bsdauthrespond(int socket, Buffer *m)
+{
+	char *response;
+	int authok;
+
+	if (authctxt->as == 0)
+		fatal("%s: no bsd auth session", __FUNCTION__);
+
+	response = buffer_get_string(m, NULL);
+	authok = auth_userresponse(authctxt->as, response, 0);
+	authctxt->as = NULL;
+	debug3("%s: <%s> = <%d>", __FUNCTION__, response, authok);
+	xfree(response);
+
+	buffer_clear(m);
+	buffer_put_int(m, authok);
+
+	debug3("%s: sending authenticated: %d", __FUNCTION__, authok);
+	mm_request_send(socket, MONITOR_ANS_BSDAUTHRESPOND, m);
+
+	auth_method = "bsdauth";
+
+	return (authok != 0);
+}
+#endif
+
+#ifdef SKEY
+int
+mm_answer_skeyquery(int socket, Buffer *m)
+{
+	struct skey skey;
+	char challenge[1024];
+	int res;
+
+	res = skeychallenge(&skey, authctxt->user, challenge);
+
+	buffer_clear(m);
+	buffer_put_int(m, res);
+	if (res != -1)
+		buffer_put_cstring(m, challenge);
+
+	debug3("%s: sending challenge res: %d", __FUNCTION__, res);
+	mm_request_send(socket, MONITOR_ANS_SKEYQUERY, m);
+
+	return (0);
+}
+
+int
+mm_answer_skeyrespond(int socket, Buffer *m)
+{
+	char *response;
+	int authok;
+
+	response = buffer_get_string(m, NULL);
+
+	authok = (authctxt->valid &&
+	    skey_haskey(authctxt->pw->pw_name) == 0 &&
+	    skey_passcheck(authctxt->pw->pw_name, response) != -1);
+
+	xfree(response);
+
+	buffer_clear(m);
+	buffer_put_int(m, authok);
+
+	debug3("%s: sending authenticated: %d", __FUNCTION__, authok);
+	mm_request_send(socket, MONITOR_ANS_SKEYRESPOND, m);
+
+	auth_method = "skey";
+
+	return (authok != 0);
+}
+#endif
+
+static void
+mm_append_debug(Buffer *m)
+{
+	if (auth_debug_init && buffer_len(&auth_debug)) {
+		debug3("%s: Appending debug messages for child", __FUNCTION__);
+		buffer_append(m, buffer_ptr(&auth_debug),
+		    buffer_len(&auth_debug));
+		buffer_clear(&auth_debug);
+	}
+}
+
+int
+mm_answer_keyallowed(int socket, Buffer *m)
+{
+	Key *key;
+	u_char *cuser, *chost, *blob;
+	u_int bloblen;
+	enum mm_keytype type = 0;
+	int allowed = 0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	type = buffer_get_int(m);
+	cuser = buffer_get_string(m, NULL);
+	chost = buffer_get_string(m, NULL);
+	blob = buffer_get_string(m, &bloblen);
+
+	key = key_from_blob(blob, bloblen);
+
+	if ((compat20 && type == MM_RSAHOSTKEY) ||
+	    (!compat20 && type != MM_RSAHOSTKEY))
+		fatal("%s: key type and protocol mismatch", __FUNCTION__);
+
+	debug3("%s: key_from_blob: %p", __FUNCTION__, key);
+
+	if (key != NULL && authctxt->pw != NULL) {
+		switch(type) {
+		case MM_USERKEY:
+			allowed = user_key_allowed(authctxt->pw, key);
+			break;
+		case MM_HOSTKEY:
+			allowed = hostbased_key_allowed(authctxt->pw,
+			    cuser, chost, key);
+			break;
+		case MM_RSAHOSTKEY:
+			key->type = KEY_RSA1; /* XXX */
+			allowed = auth_rhosts_rsa_key_allowed(authctxt->pw,
+			    cuser, chost, key);
+			break;
+		default:
+			fatal("%s: unknown key type %d", __FUNCTION__, type);
+			break;
+		}
+		key_free(key);
+	}
+
+	/* clear temporarily storage (used by verify) */
+	monitor_reset_key_state();
+
+	if (allowed) {
+		/* Save temporarily for comparison in verify */
+		key_blob = blob;
+		key_bloblen = bloblen;
+		key_blobtype = type;
+		hostbased_cuser = cuser;
+		hostbased_chost = chost;
+	}
+
+	debug3("%s: key %p is %s",
+	    __FUNCTION__, key, allowed ? "allowed" : "disallowed");
+
+	buffer_clear(m);
+	buffer_put_int(m, allowed);
+
+	mm_append_debug(m);
+
+	mm_request_send(socket, MONITOR_ANS_KEYALLOWED, m);
+
+	if (type == MM_RSAHOSTKEY)
+		monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed);
+
+	return (0);
+}
+
+static int
+monitor_valid_userblob(u_char *data, u_int datalen)
+{
+	Buffer b;
+	u_char *p;
+	u_int len;
+	int fail = 0;
+	int session_id2_len = 20 /*XXX should get from [net] */;
+
+	buffer_init(&b);
+	buffer_append(&b, data, datalen);
+
+	if (datafellows & SSH_OLD_SESSIONID) {
+		buffer_consume(&b, session_id2_len);
+	} else {
+		xfree(buffer_get_string(&b, &len));
+		if (len != session_id2_len)
+			fail++;
+	}
+	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
+		fail++;
+	p = buffer_get_string(&b, NULL);
+	if (strcmp(authctxt->user, p) != 0) {
+		log("wrong user name passed to monitor: expected %s != %.100s",
+		    authctxt->user, p);
+		fail++;
+	}
+	xfree(p);
+	buffer_skip_string(&b);
+	if (datafellows & SSH_BUG_PKAUTH) {
+		if (!buffer_get_char(&b))
+			fail++;
+	} else {
+		p = buffer_get_string(&b, NULL);
+		if (strcmp("publickey", p) != 0)
+			fail++;
+		xfree(p);
+		if (!buffer_get_char(&b))
+			fail++;
+		buffer_skip_string(&b);
+	}
+	buffer_skip_string(&b);
+	if (buffer_len(&b) != 0)
+		fail++;
+	buffer_free(&b);
+	return (fail == 0);
+}
+
+static int
+monitor_valid_hostbasedblob(u_char *data, u_int datalen, u_char *cuser,
+    u_char *chost)
+{
+	Buffer b;
+	u_char *p;
+	u_int len;
+	int fail = 0;
+	int session_id2_len = 20 /*XXX should get from [net] */;
+
+	buffer_init(&b);
+	buffer_append(&b, data, datalen);
+
+	xfree(buffer_get_string(&b, &len));
+	if (len != session_id2_len)
+		fail++;
+	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
+		fail++;
+	p = buffer_get_string(&b, NULL);
+	if (strcmp(authctxt->user, p) != 0) {
+		log("wrong user name passed to monitor: expected %s != %.100s",
+		    authctxt->user, p);
+		fail++;
+	}
+	xfree(p);
+	buffer_skip_string(&b);	/* service */
+	p = buffer_get_string(&b, NULL);
+	if (strcmp(p, "hostbased") != 0)
+		fail++;
+	xfree(p);
+	buffer_skip_string(&b);	/* pkalg */
+	buffer_skip_string(&b);	/* pkblob */
+
+	/* verify client host, strip trailing dot if necessary */
+	p = buffer_get_string(&b, NULL);
+	if (((len = strlen(p)) > 0) && p[len - 1] == '.')
+		p[len - 1] = '\0';
+	if (strcmp(p, chost) != 0)
+		fail++;
+	xfree(p);
+
+	/* verify client user */
+	p = buffer_get_string(&b, NULL);
+	if (strcmp(p, cuser) != 0)
+		fail++;
+	xfree(p);
+
+	if (buffer_len(&b) != 0)
+		fail++;
+	buffer_free(&b);
+	return (fail == 0);
+}
+
+int
+mm_answer_keyverify(int socket, Buffer *m)
+{
+	Key *key;
+	u_char *signature, *data, *blob;
+	u_int signaturelen, datalen, bloblen;
+	int verified = 0;
+	int valid_data = 0;
+
+	blob = buffer_get_string(m, &bloblen);
+	signature = buffer_get_string(m, &signaturelen);
+	data = buffer_get_string(m, &datalen);
+
+	if (hostbased_cuser == NULL || hostbased_chost == NULL ||
+	   monitor_allowed_key(blob, bloblen) == NULL)
+		fatal("%s: bad key, not previously allowed", __FUNCTION__);
+
+	key = key_from_blob(blob, bloblen);
+	if (key == NULL)
+		fatal("%s: bad public key blob", __FUNCTION__);
+
+	switch (key_blobtype) {
+	case MM_USERKEY:
+		valid_data = monitor_valid_userblob(data, datalen);
+		break;
+	case MM_HOSTKEY:
+		valid_data = monitor_valid_hostbasedblob(data, datalen,
+		    hostbased_cuser, hostbased_chost);
+		break;
+	default:
+		valid_data = 0;
+		break;
+	}
+	if (!valid_data)
+		fatal("%s: bad signature data blob", __FUNCTION__);
+
+	verified = key_verify(key, signature, signaturelen, data, datalen);
+	debug3("%s: key %p signature %s",
+	    __FUNCTION__, key, verified ? "verified" : "unverified");
+
+	key_free(key);
+	xfree(blob);
+	xfree(signature);
+	xfree(data);
+
+	monitor_reset_key_state();
+
+	buffer_clear(m);
+	buffer_put_int(m, verified);
+	mm_request_send(socket, MONITOR_ANS_KEYVERIFY, m);
+
+	auth_method = "publickey";
+
+	return (verified);
+}
+
+static void
+mm_record_login(Session *s, struct passwd *pw)
+{
+	socklen_t fromlen;
+	struct sockaddr_storage from;
+
+	/*
+	 * Get IP address of client. If the connection is not a socket, let
+	 * the address be 0.0.0.0.
+	 */
+	memset(&from, 0, sizeof(from));
+	if (packet_connection_is_on_socket()) {
+		fromlen = sizeof(from);
+		if (getpeername(packet_get_connection_in(),
+			(struct sockaddr *) & from, &fromlen) < 0) {
+			debug("getpeername: %.100s", strerror(errno));
+			fatal_cleanup();
+		}
+	}
+	/* Record that there was a login on that tty from the remote host. */
+	record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid,
+	    get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping),
+	    (struct sockaddr *)&from);
+}
+
+static void
+mm_session_close(Session *s)
+{
+	debug3("%s: session %d pid %d", __FUNCTION__, s->self, s->pid);
+	if (s->ttyfd != -1) {
+		debug3("%s: tty %s ptyfd %d",  __FUNCTION__, s->tty, s->ptyfd);
+		fatal_remove_cleanup(session_pty_cleanup2, (void *)s);
+		session_pty_cleanup2(s);
+	}
+	s->used = 0;
+}
+
+int
+mm_answer_pty(int socket, Buffer *m)
+{
+	extern struct monitor *monitor;
+	Session *s;
+	int res, fd0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	buffer_clear(m);
+	s = session_new();
+	if (s == NULL)
+		goto error;
+	s->authctxt = authctxt;
+	s->pw = authctxt->pw;
+	s->pid = monitor->m_pid;
+	res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
+	if (res == 0)
+		goto error;
+	fatal_add_cleanup(session_pty_cleanup2, (void *)s);
+	pty_setowner(authctxt->pw, s->tty);
+
+	buffer_put_int(m, 1);
+	buffer_put_cstring(m, s->tty);
+	mm_request_send(socket, MONITOR_ANS_PTY, m);
+
+	mm_send_fd(socket, s->ptyfd);
+	mm_send_fd(socket, s->ttyfd);
+
+	/* We need to trick ttyslot */
+	if (dup2(s->ttyfd, 0) == -1)
+		fatal("%s: dup2", __FUNCTION__);
+
+	mm_record_login(s, authctxt->pw);
+
+	/* Now we can close the file descriptor again */
+	close(0);
+
+	/* make sure nothing uses fd 0 */
+	if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0)
+		fatal("%s: open(/dev/null): %s", __FUNCTION__, strerror(errno));
+	if (fd0 != 0)
+		error("%s: fd0 %d != 0", __FUNCTION__, fd0);
+
+	/* slave is not needed */
+	close(s->ttyfd);
+	s->ttyfd = s->ptyfd;
+	/* no need to dup() because nobody closes ptyfd */
+	s->ptymaster = s->ptyfd;
+
+	debug3("%s: tty %s ptyfd %d",  __FUNCTION__, s->tty, s->ttyfd);
+
+	return (0);
+
+ error:
+	if (s != NULL)
+		mm_session_close(s);
+	buffer_put_int(m, 0);
+	mm_request_send(socket, MONITOR_ANS_PTY, m);
+	return (0);
+}
+
+int
+mm_answer_pty_cleanup(int socket, Buffer *m)
+{
+	Session *s;
+	char *tty;
+
+	debug3("%s entering", __FUNCTION__);
+
+	tty = buffer_get_string(m, NULL);
+	if ((s = session_by_tty(tty)) != NULL)
+		mm_session_close(s);
+	buffer_clear(m);
+	xfree(tty);
+	return (0);
+}
+
+int
+mm_answer_sesskey(int socket, Buffer *m)
+{
+	BIGNUM *p;
+	int rsafail;
+
+	/* Turn off permissions */
+	monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 1);
+
+	if ((p = BN_new()) == NULL)
+		fatal("%s: BN_new", __FUNCTION__);
+
+	buffer_get_bignum2(m, p);
+
+	rsafail = ssh1_session_key(p);
+
+	buffer_clear(m);
+	buffer_put_int(m, rsafail);
+	buffer_put_bignum2(m, p);
+
+	BN_clear_free(p);
+
+	mm_request_send(socket, MONITOR_ANS_SESSKEY, m);
+
+	/* Turn on permissions for sessid passing */
+	monitor_permit(mon_dispatch, MONITOR_REQ_SESSID, 1);
+
+	return (0);
+}
+
+int
+mm_answer_sessid(int socket, Buffer *m)
+{
+	int i;
+
+	debug3("%s entering", __FUNCTION__);
+
+	if (buffer_len(m) != 16)
+		fatal("%s: bad ssh1 session id", __FUNCTION__);
+	for (i = 0; i < 16; i++)
+		session_id[i] = buffer_get_char(m);
+
+	/* Turn on permissions for getpwnam */
+	monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
+
+	return (0);
+}
+
+int
+mm_answer_rsa_keyallowed(int socket, Buffer *m)
+{
+	BIGNUM *client_n;
+	Key *key = NULL;
+	u_char *blob = NULL;
+	u_int blen = 0;
+	int allowed = 0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	if (authctxt->valid) {
+		if ((client_n = BN_new()) == NULL)
+			fatal("%s: BN_new", __FUNCTION__);
+		buffer_get_bignum2(m, client_n);
+		allowed = auth_rsa_key_allowed(authctxt->pw, client_n, &key);
+		BN_clear_free(client_n);
+	}
+	buffer_clear(m);
+	buffer_put_int(m, allowed);
+
+	/* clear temporarily storage (used by generate challenge) */
+	monitor_reset_key_state();
+
+	if (allowed && key != NULL) {
+		key->type = KEY_RSA;	/* cheat for key_to_blob */
+		if (key_to_blob(key, &blob, &blen) == 0)
+			fatal("%s: key_to_blob failed", __FUNCTION__);
+		buffer_put_string(m, blob, blen);
+
+		/* Save temporarily for comparison in verify */
+		key_blob = blob;
+		key_bloblen = blen;
+		key_blobtype = MM_RSAUSERKEY;
+		key_free(key);
+	}
+
+	mm_append_debug(m);
+
+	mm_request_send(socket, MONITOR_ANS_RSAKEYALLOWED, m);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed);
+	monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 0);
+	return (0);
+}
+
+int
+mm_answer_rsa_challenge(int socket, Buffer *m)
+{
+	Key *key = NULL;
+	u_char *blob;
+	u_int blen;
+
+	debug3("%s entering", __FUNCTION__);
+
+	if (!authctxt->valid)
+		fatal("%s: authctxt not valid", __FUNCTION__);
+	blob = buffer_get_string(m, &blen);
+	if (!monitor_allowed_key(blob, blen))
+		fatal("%s: bad key, not previously allowed", __FUNCTION__);
+	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
+		fatal("%s: key type mismatch", __FUNCTION__);
+	if ((key = key_from_blob(blob, blen)) == NULL)
+		fatal("%s: received bad key", __FUNCTION__);
+
+	if (ssh1_challenge)
+		BN_clear_free(ssh1_challenge);
+	ssh1_challenge = auth_rsa_generate_challenge(key);
+
+	buffer_clear(m);
+	buffer_put_bignum2(m, ssh1_challenge);
+
+	debug3("%s sending reply", __FUNCTION__);
+	mm_request_send(socket, MONITOR_ANS_RSACHALLENGE, m);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 1);
+	return (0);
+}
+
+int
+mm_answer_rsa_response(int socket, Buffer *m)
+{
+	Key *key = NULL;
+	u_char *blob, *response;
+	u_int blen, len;
+	int success;
+
+	debug3("%s entering", __FUNCTION__);
+
+	if (!authctxt->valid)
+		fatal("%s: authctxt not valid", __FUNCTION__);
+	if (ssh1_challenge == NULL)
+		fatal("%s: no ssh1_challenge", __FUNCTION__);
+
+	blob = buffer_get_string(m, &blen);
+	if (!monitor_allowed_key(blob, blen))
+		fatal("%s: bad key, not previously allowed", __FUNCTION__);
+	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
+		fatal("%s: key type mismatch: %d", __FUNCTION__, key_blobtype);
+	if ((key = key_from_blob(blob, blen)) == NULL)
+		fatal("%s: received bad key", __FUNCTION__);
+	response = buffer_get_string(m, &len);
+	if (len != 16)
+		fatal("%s: received bad response to challenge", __FUNCTION__);
+	success = auth_rsa_verify_response(key, ssh1_challenge, response);
+
+	key_free(key);
+	xfree(response);
+
+	auth_method = key_blobtype == MM_RSAUSERKEY ? "rsa" : "rhosts-rsa";
+
+	/* reset state */
+	BN_clear_free(ssh1_challenge);
+	ssh1_challenge = NULL;
+	monitor_reset_key_state();
+
+	buffer_clear(m);
+	buffer_put_int(m, success);
+	mm_request_send(socket, MONITOR_ANS_RSARESPONSE, m);
+
+	return (success);
+}
+
+int
+mm_answer_term(int socket, Buffer *req)
+{
+	extern struct monitor *monitor;
+	int res, status;
+
+	debug3("%s: tearing down sessions", __FUNCTION__);
+
+	/* The child is terminating */
+	session_destroy_all(&mm_session_close);
+
+	if (waitpid(monitor->m_pid, &status, 0) == -1)
+		exit(1);
+
+	res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
+
+	/* Terminate process */
+	exit (res);
+}
+
+void
+monitor_apply_keystate(struct monitor *monitor)
+{
+	if (compat20) {
+		set_newkeys(MODE_IN);
+		set_newkeys(MODE_OUT);
+	} else {
+		u_char key[SSH_SESSION_KEY_LENGTH];
+
+		memset(key, 'a', sizeof(key));
+		packet_set_protocol_flags(child_state.ssh1protoflags);
+		packet_set_encryption_key(key, SSH_SESSION_KEY_LENGTH,
+		    child_state.ssh1cipher);
+	}
+
+	packet_set_keycontext(MODE_OUT, child_state.keyout);
+	xfree(child_state.keyout);
+	packet_set_keycontext(MODE_IN, child_state.keyin);
+	xfree(child_state.keyin);
+
+	if (!compat20) {
+		packet_set_iv(MODE_OUT, child_state.ivout);
+		xfree(child_state.ivout);
+		packet_set_iv(MODE_IN, child_state.ivin);
+		xfree(child_state.ivin);
+	}
+
+	memcpy(&incoming_stream, &child_state.incoming,
+	    sizeof(incoming_stream));
+	memcpy(&outgoing_stream, &child_state.outgoing,
+	    sizeof(outgoing_stream));
+
+	/* Update with new address */
+	mm_init_compression(monitor->m_zlib);
+
+	/* Network I/O buffers */
+	/* XXX inefficient for large buffers, need: buffer_init_from_string */
+	buffer_clear(&input);
+	buffer_append(&input, child_state.input, child_state.ilen);
+	memset(child_state.input, 0, child_state.ilen);
+	xfree(child_state.input);
+
+	buffer_clear(&output);
+	buffer_append(&output, child_state.output, child_state.olen);
+	memset(child_state.output, 0, child_state.olen);
+	xfree(child_state.output);
+}
+
+static Kex *
+mm_get_kex(Buffer *m)
+{
+	Kex *kex;
+	void *blob;
+	u_int bloblen;
+
+	kex = xmalloc(sizeof(*kex));
+	memset(kex, 0, sizeof(*kex));
+	kex->session_id = buffer_get_string(m, &kex->session_id_len);
+	kex->we_need = buffer_get_int(m);
+	kex->server = 1;
+	kex->hostkey_type = buffer_get_int(m);
+	kex->kex_type = buffer_get_int(m);
+	blob = buffer_get_string(m, &bloblen);
+	buffer_init(&kex->my);
+	buffer_append(&kex->my, blob, bloblen);
+	xfree(blob);
+	blob = buffer_get_string(m, &bloblen);
+	buffer_init(&kex->peer);
+	buffer_append(&kex->peer, blob, bloblen);
+	xfree(blob);
+	kex->done = 1;
+	kex->flags = buffer_get_int(m);
+	kex->client_version_string = buffer_get_string(m, NULL);
+	kex->server_version_string = buffer_get_string(m, NULL);
+	kex->load_host_key=&get_hostkey_by_type;
+	kex->host_key_index=&get_hostkey_index;
+
+	return (kex);
+}
+
+/* This function requries careful sanity checking */
+
+void
+mm_get_keystate(struct monitor *monitor)
+{
+	Buffer m;
+	u_char *blob, *p;
+	u_int bloblen, plen;
+
+	debug3("%s: Waiting for new keys", __FUNCTION__);
+
+	buffer_init(&m);
+	mm_request_receive_expect(monitor->m_sendfd, MONITOR_REQ_KEYEXPORT, &m);
+	if (!compat20) {
+		child_state.ssh1protoflags = buffer_get_int(&m);
+		child_state.ssh1cipher = buffer_get_int(&m);
+		child_state.ivout = buffer_get_string(&m,
+		    &child_state.ivoutlen);
+		child_state.ivin = buffer_get_string(&m, &child_state.ivinlen);
+		goto skip;
+	} else {
+		/* Get the Kex for rekeying */
+		*monitor->m_pkex = mm_get_kex(&m);
+	}
+
+	blob = buffer_get_string(&m, &bloblen);
+	current_keys[MODE_OUT] = mm_newkeys_from_blob(blob, bloblen);
+	xfree(blob);
+
+	debug3("%s: Waiting for second key", __FUNCTION__);
+	blob = buffer_get_string(&m, &bloblen);
+	current_keys[MODE_IN] = mm_newkeys_from_blob(blob, bloblen);
+	xfree(blob);
+
+	/* Now get sequence numbers for the packets */
+	packet_set_seqnr(MODE_OUT, buffer_get_int(&m));
+	packet_set_seqnr(MODE_IN, buffer_get_int(&m));
+
+ skip:
+	/* Get the key context */
+	child_state.keyout = buffer_get_string(&m, &child_state.keyoutlen);
+	child_state.keyin  = buffer_get_string(&m, &child_state.keyinlen);
+
+	debug3("%s: Getting compression state", __FUNCTION__);
+	/* Get compression state */
+	p = buffer_get_string(&m, &plen);
+	if (plen != sizeof(child_state.outgoing))
+		fatal("%s: bad request size", __FUNCTION__);
+	memcpy(&child_state.outgoing, p, sizeof(child_state.outgoing));
+	xfree(p);
+
+	p = buffer_get_string(&m, &plen);
+	if (plen != sizeof(child_state.incoming))
+		fatal("%s: bad request size", __FUNCTION__);
+	memcpy(&child_state.incoming, p, sizeof(child_state.incoming));
+	xfree(p);
+
+	/* Network I/O buffers */
+	debug3("%s: Getting Network I/O buffers", __FUNCTION__);
+	child_state.input = buffer_get_string(&m, &child_state.ilen);
+	child_state.output = buffer_get_string(&m, &child_state.olen);
+
+	buffer_free(&m);
+}
+
+
+/* Allocation functions for zlib */
+void *
+mm_zalloc(struct mm_master *mm, u_int ncount, u_int size)
+{
+	void *address;
+
+	address = mm_malloc(mm, size * ncount);
+
+	return (address);
+}
+
+void
+mm_zfree(struct mm_master *mm, void *address)
+{
+	mm_free(mm, address);
+}
+
+void
+mm_init_compression(struct mm_master *mm)
+{
+	outgoing_stream.zalloc = (alloc_func)mm_zalloc;
+	outgoing_stream.zfree = (free_func)mm_zfree;
+	outgoing_stream.opaque = mm;
+
+	incoming_stream.zalloc = (alloc_func)mm_zalloc;
+	incoming_stream.zfree = (free_func)mm_zfree;
+	incoming_stream.opaque = mm;
+}
+
+/* XXX */
+
+#define FD_CLOSEONEXEC(x) do { \
+	if (fcntl(x, F_SETFD, 1) == -1) \
+		fatal("fcntl(%d, F_SETFD)", x); \
+} while (0)
+
+static void
+monitor_socketpair(int *pair)
+{
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
+		fatal("%s: socketpair", __FUNCTION__);
+	FD_CLOSEONEXEC(pair[0]);
+	FD_CLOSEONEXEC(pair[1]);
+}
+
+#define MM_MEMSIZE	65536
+
+struct monitor *
+monitor_init(void)
+{
+	struct monitor *mon;
+	int pair[2];
+
+	mon = xmalloc(sizeof(*mon));
+
+	monitor_socketpair(pair);
+
+	mon->m_recvfd = pair[0];
+	mon->m_sendfd = pair[1];
+
+	/* Used to share zlib space across processes */
+	mon->m_zback = mm_create(NULL, MM_MEMSIZE);
+	mon->m_zlib = mm_create(mon->m_zback, 20 * MM_MEMSIZE);
+
+	/* Compression needs to share state across borders */
+	mm_init_compression(mon->m_zlib);
+
+	return mon;
+}
+
+void
+monitor_reinit(struct monitor *mon)
+{
+	int pair[2];
+
+	monitor_socketpair(pair);
+
+	mon->m_recvfd = pair[0];
+	mon->m_sendfd = pair[1];
+}
diff --git a/monitor.h b/monitor.h
new file mode 100644
index 00000000..da7f780b
--- /dev/null
+++ b/monitor.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MONITOR_H_
+#define _MONITOR_H_
+
+enum monitor_reqtype {
+	MONITOR_REQ_MODULI, MONITOR_ANS_MODULI,
+	MONITOR_REQ_FREE, MONITOR_REQ_AUTHSERV,
+	MONITOR_REQ_SIGN, MONITOR_ANS_SIGN,
+	MONITOR_REQ_PWNAM, MONITOR_ANS_PWNAM,
+	MONITOR_REQ_AUTHPASSWORD, MONITOR_ANS_AUTHPASSWORD,
+	MONITOR_REQ_BSDAUTHQUERY, MONITOR_ANS_BSDAUTHQUERY,
+	MONITOR_REQ_BSDAUTHRESPOND, MONITOR_ANS_BSDAUTHRESPOND,
+	MONITOR_REQ_SKEYQUERY, MONITOR_ANS_SKEYQUERY,
+	MONITOR_REQ_SKEYRESPOND, MONITOR_ANS_SKEYRESPOND,
+	MONITOR_REQ_KEYALLOWED, MONITOR_ANS_KEYALLOWED,
+	MONITOR_REQ_KEYVERIFY, MONITOR_ANS_KEYVERIFY,
+	MONITOR_REQ_KEYEXPORT,
+	MONITOR_REQ_PTY, MONITOR_ANS_PTY,
+	MONITOR_REQ_PTYCLEANUP,
+	MONITOR_REQ_SESSKEY, MONITOR_ANS_SESSKEY,
+	MONITOR_REQ_SESSID,
+	MONITOR_REQ_RSAKEYALLOWED, MONITOR_ANS_RSAKEYALLOWED,
+	MONITOR_REQ_RSACHALLENGE, MONITOR_ANS_RSACHALLENGE,
+	MONITOR_REQ_RSARESPONSE, MONITOR_ANS_RSARESPONSE,
+	MONITOR_REQ_TERM,
+};
+
+struct mm_master;
+struct monitor {
+	int			 m_recvfd;
+	int			 m_sendfd;
+	struct mm_master	*m_zback;
+	struct mm_master	*m_zlib;
+	struct Kex		**m_pkex;
+	int			 m_pid;
+};
+
+struct monitor *monitor_init(void);
+void monitor_reinit(struct monitor *);
+void monitor_sync(struct monitor *);
+
+struct Authctxt;
+struct Authctxt *monitor_child_preauth(struct monitor *);
+void monitor_child_postauth(struct monitor *);
+
+struct mon_table;
+int monitor_read(struct monitor*, struct mon_table *, struct mon_table **);
+
+/* Prototypes for request sending and receiving */
+void mm_request_send(int, enum monitor_reqtype, Buffer *);
+void mm_request_receive(int, Buffer *);
+void mm_request_receive_expect(int, enum monitor_reqtype, Buffer *);
+
+#endif /* _MONITOR_H_ */
diff --git a/monitor_fdpass.c b/monitor_fdpass.c
new file mode 100644
index 00000000..7785535b
--- /dev/null
+++ b/monitor_fdpass.c
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2001 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD: monitor_fdpass.c,v 1.1 2002/03/18 17:27:22 provos Exp $");
+
+#include <sys/uio.h>
+
+#include "log.h"
+#include "monitor_fdpass.h"
+
+void
+mm_send_fd(int socket, int fd)
+{
+	struct msghdr msg;
+	char tmp[CMSG_SPACE(sizeof(int))];
+	struct cmsghdr *cmsg;
+	struct iovec vec;
+	char ch;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_control = (caddr_t)tmp;
+	msg.msg_controllen = CMSG_LEN(sizeof(int));
+	cmsg = CMSG_FIRSTHDR(&msg);
+	cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+	cmsg->cmsg_level = SOL_SOCKET;
+	cmsg->cmsg_type = SCM_RIGHTS;
+	*(int *)CMSG_DATA(cmsg) = fd;
+
+	vec.iov_base = &ch;
+	vec.iov_len = 1;
+	msg.msg_iov = &vec;
+	msg.msg_iovlen = 1;
+
+	if (sendmsg(socket, &msg, 0) == -1)
+		fatal("%s: sendmsg(%d)", __FUNCTION__, fd);
+}
+
+int
+mm_receive_fd(int socket)
+{
+	struct msghdr msg;
+	char tmp[CMSG_SPACE(sizeof(int))];
+	struct cmsghdr *cmsg;
+	struct iovec vec;
+	char ch;
+
+	memset(&msg, 0, sizeof(msg));
+	vec.iov_base = &ch;
+	vec.iov_len = 1;
+	msg.msg_iov = &vec;
+	msg.msg_iovlen = 1;
+	msg.msg_control = tmp;
+	msg.msg_controllen = sizeof(tmp);
+
+	if (recvmsg(socket, &msg, 0) == -1)
+		fatal("%s: recvmsg", __FUNCTION__);
+
+	cmsg = CMSG_FIRSTHDR(&msg);
+	if (cmsg->cmsg_type != SCM_RIGHTS)
+		fatal("%s: expected type %d got %d", __FUNCTION__,
+		    SCM_RIGHTS, cmsg->cmsg_type);
+	return (*(int *)CMSG_DATA(cmsg));
+}
diff --git a/monitor_fdpass.h b/monitor_fdpass.h
new file mode 100644
index 00000000..cb6b71c9
--- /dev/null
+++ b/monitor_fdpass.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MM_FDPASS_H_
+#define _MM_FDPASS_H_
+
+void mm_send_fd(int, int);
+int mm_receive_fd(int);
+
+#endif /* _MM_FDPASS_H_ */
diff --git a/monitor_mm.c b/monitor_mm.c
new file mode 100644
index 00000000..bce98c93
--- /dev/null
+++ b/monitor_mm.c
@@ -0,0 +1,329 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD: monitor_mm.c,v 1.3 2002/03/19 10:41:32 markus Exp $");
+
+#include <sys/mman.h>
+
+#include "ssh.h"
+#include "xmalloc.h"
+#include "log.h"
+#include "monitor_mm.h"
+
+static int
+mm_compare(struct mm_share *a, struct mm_share *b)
+{
+	return ((char *)a->address - (char *)b->address);
+}
+
+RB_GENERATE(mmtree, mm_share, next, mm_compare)
+
+static struct mm_share *
+mm_make_entry(struct mm_master *mm, struct mmtree *head,
+    void *address, size_t size)
+{
+	struct mm_share *tmp, *tmp2;
+
+	if (mm->mmalloc == NULL)
+		tmp = xmalloc(sizeof(struct mm_share));
+	else
+		tmp = mm_xmalloc(mm->mmalloc, sizeof(struct mm_share));
+	tmp->address = address;
+	tmp->size = size;
+
+	tmp2 = RB_INSERT(mmtree, head, tmp);
+	if (tmp2 != NULL)
+		fatal("mm_make_entry(%p): double address %p->%p(%d)",
+		    mm, tmp2, address, size);
+
+	return (tmp);
+}
+
+/* Creates a shared memory area of a certain size */
+
+struct mm_master *
+mm_create(struct mm_master *mmalloc, size_t size)
+{
+	void *address;
+	struct mm_master *mm;
+
+	if (mmalloc == NULL)
+		mm = xmalloc(sizeof(struct mm_master));
+	else
+		mm = mm_xmalloc(mmalloc, sizeof(struct mm_master));
+
+	/*
+	 * If the memory map has a mm_master it can be completely
+	 * shared including authentication between the child
+	 * and the client.
+	 */
+	mm->mmalloc = mmalloc;
+
+	address = mmap(NULL, size, PROT_WRITE|PROT_READ, MAP_ANON|MAP_SHARED,
+	    -1, 0);
+	if (address == MAP_FAILED)
+		fatal("mmap(%d)", size);
+
+	mm->address = address;
+	mm->size = size;
+
+	RB_INIT(&mm->rb_free);
+	RB_INIT(&mm->rb_allocated);
+
+	mm_make_entry(mm, &mm->rb_free, address, size);
+
+	return (mm);
+}
+
+/* Frees either the allocated or the free list */
+
+static void
+mm_freelist(struct mm_master *mmalloc, struct mmtree *head)
+{
+	struct mm_share *mms, *next;
+
+	for (mms = RB_ROOT(head); mms; mms = next) {
+		next = RB_NEXT(mmtree, head, mms);
+		RB_REMOVE(mmtree, head, mms);
+		if (mmalloc == NULL)
+			xfree(mms);
+		else
+			mm_free(mmalloc, mms);
+	}
+}
+
+/* Destroys a memory mapped area */
+
+void
+mm_destroy(struct mm_master *mm)
+{
+	mm_freelist(mm->mmalloc, &mm->rb_free);
+	mm_freelist(mm->mmalloc, &mm->rb_allocated);
+
+	if (munmap(mm->address, mm->size) == -1)
+		fatal("munmap(%p, %d)", mm->address, mm->size);
+	if (mm->mmalloc == NULL)
+		xfree(mm);
+	else
+		mm_free(mm->mmalloc, mm);
+}
+
+void *
+mm_xmalloc(struct mm_master *mm, size_t size)
+{
+	void *address;
+
+	address = mm_malloc(mm, size);
+	if (address == NULL)
+		fatal("%s: mm_malloc(%d)", __FUNCTION__, size);
+	return (address);
+}
+
+
+/* Allocates data from a memory mapped area */
+
+void *
+mm_malloc(struct mm_master *mm, size_t size)
+{
+	struct mm_share *mms, *tmp;
+
+	if (size == 0)
+		fatal("mm_malloc: try to allocate 0 space");
+
+	size = ((size + MM_MINSIZE - 1) / MM_MINSIZE) * MM_MINSIZE;
+
+	RB_FOREACH(mms, mmtree, &mm->rb_free) {
+		if (mms->size >= size)
+			break;
+	}
+
+	if (mms == NULL)
+		return (NULL);
+
+	/* Debug */
+	memset(mms->address, 0xd0, size);
+
+	tmp = mm_make_entry(mm, &mm->rb_allocated, mms->address, size);
+
+	/* Does not change order in RB tree */
+	mms->size -= size;
+	mms->address = (u_char *)mms->address + size;
+
+	if (mms->size == 0) {
+		RB_REMOVE(mmtree, &mm->rb_free, mms);
+		if (mm->mmalloc == NULL)
+			xfree(mms);
+		else
+			mm_free(mm->mmalloc, mms);
+	}
+
+	return (tmp->address);
+}
+
+/* Frees memory in a memory mapped area */
+
+void
+mm_free(struct mm_master *mm, void *address)
+{
+	struct mm_share *mms, *prev, tmp;
+
+	tmp.address = address;
+	mms = RB_FIND(mmtree, &mm->rb_allocated, &tmp);
+	if (mms == NULL)
+		fatal("mm_free(%p): can not find %p", mm, address);
+
+	/* Debug */
+	memset(mms->address, 0xd0, mms->size);
+
+	/* Remove from allocated list and insert in free list */
+	RB_REMOVE(mmtree, &mm->rb_allocated, mms);
+	if (RB_INSERT(mmtree, &mm->rb_free, mms) != NULL)
+		fatal("mm_free(%p): double address %p", mm, address);
+
+	/* Find previous entry */
+	prev = mms;
+	if (RB_LEFT(prev, next)) {
+		prev = RB_LEFT(prev, next);
+		while (RB_RIGHT(prev, next))
+			prev = RB_RIGHT(prev, next);
+	} else {
+		if (RB_PARENT(prev, next) &&
+		    (prev == RB_RIGHT(RB_PARENT(prev, next), next)))
+			prev = RB_PARENT(prev, next);
+		else {
+			while (RB_PARENT(prev, next) &&
+			    (prev == RB_LEFT(RB_PARENT(prev, next), next)))
+				prev = RB_PARENT(prev, next);
+			prev = RB_PARENT(prev, next);
+		}
+	}
+
+	/* Check if range does not overlap */
+	if (prev != NULL && MM_ADDRESS_END(prev) > address)
+		fatal("mm_free: memory corruption: %p(%d) > %p",
+		    prev->address, prev->size, address);
+
+	/* See if we can merge backwards */
+	if (prev != NULL && MM_ADDRESS_END(prev) == address) {
+		prev->size += mms->size;
+		RB_REMOVE(mmtree, &mm->rb_free, mms);
+		if (mm->mmalloc == NULL)
+			xfree(mms);
+		else
+			mm_free(mm->mmalloc, mms);
+	} else
+		prev = mms;
+
+	if (prev == NULL)
+		return;
+
+	/* Check if we can merge forwards */
+	mms = RB_NEXT(mmtree, &mm->rb_free, prev);
+	if (mms == NULL)
+		return;
+
+	if (MM_ADDRESS_END(prev) > mms->address)
+		fatal("mm_free: memory corruption: %p < %p(%d)",
+		    mms->address, prev->address, prev->size);
+	if (MM_ADDRESS_END(prev) != mms->address)
+		return;
+
+	prev->size += mms->size;
+	RB_REMOVE(mmtree, &mm->rb_free, mms);
+
+	if (mm->mmalloc == NULL)
+		xfree(mms);
+	else
+		mm_free(mm->mmalloc, mms);
+}
+
+static void
+mm_sync_list(struct mmtree *oldtree, struct mmtree *newtree,
+    struct mm_master *mm, struct mm_master *mmold)
+{
+	struct mm_master *mmalloc = mm->mmalloc;
+	struct mm_share *mms, *new;
+
+	/* Sync free list */
+	RB_FOREACH(mms, mmtree, oldtree) {
+		/* Check the values */
+		mm_memvalid(mmold, mms, sizeof(struct mm_share));
+		mm_memvalid(mm, mms->address, mms->size);
+
+		new = mm_xmalloc(mmalloc, sizeof(struct mm_share));
+		memcpy(new, mms, sizeof(struct mm_share));
+		RB_INSERT(mmtree, newtree, new);
+	}
+}
+
+void
+mm_share_sync(struct mm_master **pmm, struct mm_master **pmmalloc)
+{
+	struct mm_master *mm;
+	struct mm_master *mmalloc;
+	struct mm_master *mmold;
+	struct mmtree rb_free, rb_allocated;
+
+	debug3("%s: Share sync", __FUNCTION__);
+
+	mm = *pmm;
+	mmold = mm->mmalloc;
+	mm_memvalid(mmold, mm, sizeof(*mm));
+
+	mmalloc = mm_create(NULL, mm->size);
+	mm = mm_xmalloc(mmalloc, sizeof(struct mm_master));
+	memcpy(mm, *pmm, sizeof(struct mm_master));
+	mm->mmalloc = mmalloc;
+
+	rb_free = mm->rb_free;
+	rb_allocated = mm->rb_allocated;
+
+	RB_INIT(&mm->rb_free);
+	RB_INIT(&mm->rb_allocated);
+
+	mm_sync_list(&rb_free, &mm->rb_free, mm, mmold);
+	mm_sync_list(&rb_allocated, &mm->rb_allocated, mm, mmold);
+
+	mm_destroy(mmold);
+
+	*pmm = mm;
+	*pmmalloc = mmalloc;
+
+	debug3("%s: Share sync end", __FUNCTION__);
+}
+
+void
+mm_memvalid(struct mm_master *mm, void *address, size_t size)
+{
+	void *end = (u_char *)address + size;
+
+	if (address < mm->address)
+		fatal("mm_memvalid: address too small: %p", address);
+	if (end < address)
+		fatal("mm_memvalid: end < address: %p < %p", end, address);
+	if (end > (void *)((u_char *)mm->address + mm->size))
+		fatal("mm_memvalid: address too large: %p", address);
+}
diff --git a/monitor_mm.h b/monitor_mm.h
new file mode 100644
index 00000000..43442609
--- /dev/null
+++ b/monitor_mm.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MM_H_
+#define _MM_H_
+#include <sys/tree.h>
+
+struct mm_share {
+	RB_ENTRY(mm_share) next;
+	void *address;
+	size_t size;
+};
+
+struct mm_master {
+	RB_HEAD(mmtree, mm_share) rb_free;
+	struct mmtree rb_allocated;
+	void *address;
+	size_t size;
+
+	struct mm_master *mmalloc;	/* Used to completely share */
+
+	int write;		/* used to writing to other party */
+	int read;		/* used for reading from other party */
+};
+
+RB_PROTOTYPE(mmtree, mm_share, next, mm_compare)
+
+#define MM_MINSIZE		128
+
+#define MM_ADDRESS_END(x)	(void *)((u_char *)(x)->address + (x)->size)
+
+struct mm_master *mm_create(struct mm_master *, size_t);
+void mm_destroy(struct mm_master *);
+
+void mm_share_sync(struct mm_master **, struct mm_master **);
+
+void *mm_malloc(struct mm_master *, size_t);
+void *mm_xmalloc(struct mm_master *, size_t);
+void mm_free(struct mm_master *, void *);
+
+void mm_memvalid(struct mm_master *, void *, size_t);
+#endif /* _MM_H_ */
diff --git a/monitor_wrap.c b/monitor_wrap.c
new file mode 100644
index 00000000..e477cff2
--- /dev/null
+++ b/monitor_wrap.c
@@ -0,0 +1,894 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * Copyright 2002 Markus Friedl <markus@openbsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD: monitor_wrap.c,v 1.4 2002/03/19 14:27:39 markus Exp $");
+
+#include <openssl/bn.h>
+#include <openssl/dh.h>
+
+#include "ssh.h"
+#include "dh.h"
+#include "kex.h"
+#include "auth.h"
+#include "buffer.h"
+#include "bufaux.h"
+#include "packet.h"
+#include "mac.h"
+#include "log.h"
+#include "zlib.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
+#include "xmalloc.h"
+#include "atomicio.h"
+#include "monitor_fdpass.h"
+#include "getput.h"
+
+#include "auth.h"
+#include "channels.h"
+#include "session.h"
+
+/* Imports */
+extern int compat20;
+extern Newkeys *newkeys[];
+extern z_stream incoming_stream;
+extern z_stream outgoing_stream;
+extern struct monitor *monitor;
+extern Buffer input, output;
+
+void
+mm_request_send(int socket, enum monitor_reqtype type, Buffer *m)
+{
+	u_char buf[5];
+	u_int mlen = buffer_len(m);
+
+	debug3("%s entering: type %d", __FUNCTION__, type);
+
+	PUT_32BIT(buf, mlen + 1);
+	buf[4] = (u_char) type;         /* 1st byte of payload is mesg-type */
+	if (atomicio(write, socket, buf, sizeof(buf)) != sizeof(buf))
+		fatal("%s: write", __FUNCTION__);
+	if (atomicio(write, socket, buffer_ptr(m), mlen) != mlen)
+		fatal("%s: write", __FUNCTION__);
+}
+
+void
+mm_request_receive(int socket, Buffer *m)
+{
+	u_char buf[4];
+	ssize_t res;
+	u_int msg_len;
+
+	debug3("%s entering", __FUNCTION__);
+
+	res = atomicio(read, socket, buf, sizeof(buf));
+	if (res != sizeof(buf)) {
+		if (res == 0)
+			fatal_cleanup();
+		fatal("%s: read: %d", __FUNCTION__, res);
+	}
+	msg_len = GET_32BIT(buf);
+	if (msg_len > 256 * 1024)
+		fatal("%s: read: bad msg_len %d", __FUNCTION__, msg_len);
+	buffer_clear(m);
+	buffer_append_space(m, msg_len);
+	res = atomicio(read, socket, buffer_ptr(m), msg_len);
+	if (res != msg_len)
+		fatal("%s: read: %d != msg_len", __FUNCTION__, res);
+}
+
+void
+mm_request_receive_expect(int socket, enum monitor_reqtype type, Buffer *m)
+{
+	u_char rtype;
+
+	debug3("%s entering: type %d", __FUNCTION__, type);
+
+	mm_request_receive(socket, m);
+	rtype = buffer_get_char(m);
+	if (rtype != type)
+		fatal("%s: read: rtype %d != type %d", __FUNCTION__,
+		    rtype, type);
+}
+
+DH *
+mm_choose_dh(int min, int nbits, int max)
+{
+	BIGNUM *p, *g;
+	int success = 0;
+	Buffer m;
+
+	buffer_init(&m);
+	buffer_put_int(&m, min);
+	buffer_put_int(&m, nbits);
+	buffer_put_int(&m, max);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_MODULI, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_MODULI", __FUNCTION__);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_MODULI, &m);
+
+	success = buffer_get_char(&m);
+	if (success == 0)
+		fatal("%s: MONITOR_ANS_MODULI failed", __FUNCTION__);
+
+	if ((p = BN_new()) == NULL)
+		fatal("%s: BN_new failed", __FUNCTION__);
+	if ((g = BN_new()) == NULL)
+		fatal("%s: BN_new failed", __FUNCTION__);
+	buffer_get_bignum2(&m, p);
+	buffer_get_bignum2(&m, g);
+
+	debug3("%s: remaining %d", __FUNCTION__, buffer_len(&m));
+	buffer_free(&m);
+
+	return (dh_new_group(g, p));
+}
+
+int
+mm_key_sign(Key *key, u_char **sigp, u_int *lenp, u_char *data, u_int datalen)
+{
+	Kex *kex = *monitor->m_pkex;
+	Buffer m;
+
+	debug3("%s entering", __FUNCTION__);
+
+	buffer_init(&m);
+	buffer_put_int(&m, kex->host_key_index(key));
+	buffer_put_string(&m, data, datalen);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_SIGN, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_SIGN", __FUNCTION__);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_SIGN, &m);
+	*sigp  = buffer_get_string(&m, lenp);
+	buffer_free(&m);
+
+	return (0);
+}
+
+struct passwd *
+mm_getpwnamallow(const char *login)
+{
+	Buffer m;
+	struct passwd *pw;
+	u_int pwlen;
+
+	debug3("%s entering", __FUNCTION__);
+
+	buffer_init(&m);
+	buffer_put_cstring(&m, login);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_PWNAM, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_PWNAM", __FUNCTION__);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_PWNAM, &m);
+
+	if (buffer_get_char(&m) == 0) {
+		buffer_free(&m);
+		return (NULL);
+	}
+	pw = buffer_get_string(&m, &pwlen);
+	if (pwlen != sizeof(struct passwd))
+		fatal("%s: struct passwd size mismatch", __FUNCTION__);
+	pw->pw_name = buffer_get_string(&m, NULL);
+	pw->pw_passwd = buffer_get_string(&m, NULL);
+	pw->pw_gecos = buffer_get_string(&m, NULL);
+	pw->pw_class = buffer_get_string(&m, NULL);
+	pw->pw_dir = buffer_get_string(&m, NULL);
+	pw->pw_shell = buffer_get_string(&m, NULL);
+	buffer_free(&m);
+
+	return (pw);
+}
+
+/* Inform the privileged process about service and style */
+
+void
+mm_inform_authserv(char *service, char *style)
+{
+	Buffer m;
+
+	debug3("%s entering", __FUNCTION__);
+
+	buffer_init(&m);
+	buffer_put_cstring(&m, service);
+	buffer_put_cstring(&m, style ? style : "");
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_AUTHSERV, &m);
+
+	buffer_free(&m);
+}
+
+/* Do the password authentication */
+int
+mm_auth_password(Authctxt *authctxt, char *password)
+{
+	Buffer m;
+	int authenticated = 0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	buffer_init(&m);
+	buffer_put_cstring(&m, password);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_AUTHPASSWORD, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_AUTHPASSWORD", __FUNCTION__);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_AUTHPASSWORD, &m);
+
+	authenticated = buffer_get_int(&m);
+
+	buffer_free(&m);
+
+	debug3("%s: user %sauthenticated",
+	    __FUNCTION__, authenticated ? "" : "not ");
+	return (authenticated);
+}
+
+int
+mm_user_key_allowed(struct passwd *pw, Key *key)
+{
+	return (mm_key_allowed(MM_USERKEY, NULL, NULL, key));
+}
+
+int
+mm_hostbased_key_allowed(struct passwd *pw, char *user, char *host,
+    Key *key)
+{
+	return (mm_key_allowed(MM_HOSTKEY, user, host, key));
+}
+
+int
+mm_auth_rhosts_rsa_key_allowed(struct passwd *pw, char *user,
+    char *host, Key *key)
+{
+	int ret;
+
+	key->type = KEY_RSA; /* XXX hack for key_to_blob */
+	ret = mm_key_allowed(MM_RSAHOSTKEY, user, host, key);
+	key->type = KEY_RSA1;
+	return (ret);
+}
+
+static void
+mm_send_debug(Buffer *m)
+{
+	char *msg;
+
+	while (buffer_len(m)) {
+		msg = buffer_get_string(m, NULL);
+		debug3("%s: Sending debug: %s", __FUNCTION__, msg);
+		packet_send_debug("%s", msg);
+		xfree(msg);
+	}
+}
+
+int
+mm_key_allowed(enum mm_keytype type, char *user, char *host, Key *key)
+{
+	Buffer m;
+	u_char *blob;
+	u_int len;
+	int allowed = 0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	/* Convert the key to a blob and the pass it over */
+	if (!key_to_blob(key, &blob, &len))
+		return (0);
+
+	buffer_init(&m);
+	buffer_put_int(&m, type);
+	buffer_put_cstring(&m, user ? user : "");
+	buffer_put_cstring(&m, host ? host : "");
+	buffer_put_string(&m, blob, len);
+	xfree(blob);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_KEYALLOWED, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_KEYALLOWED", __FUNCTION__);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_KEYALLOWED, &m);
+
+	allowed = buffer_get_int(&m);
+
+	/* Send potential debug messages */
+	mm_send_debug(&m);
+
+	buffer_free(&m);
+
+	return (allowed);
+}
+
+/*
+ * This key verify needs to send the key type along, because the
+ * privileged parent makes the decision if the key is allowed
+ * for authentication.
+ */
+
+int
+mm_key_verify(Key *key, u_char *sig, u_int siglen, u_char *data, u_int datalen)
+{
+	Buffer m;
+	u_char *blob;
+	u_int len;
+	int verified = 0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	/* Convert the key to a blob and the pass it over */
+	if (!key_to_blob(key, &blob, &len))
+		return (0);
+
+	buffer_init(&m);
+	buffer_put_string(&m, blob, len);
+	buffer_put_string(&m, sig, siglen);
+	buffer_put_string(&m, data, datalen);
+	xfree(blob);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_KEYVERIFY, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_KEYVERIFY", __FUNCTION__);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_KEYVERIFY, &m);
+
+	verified = buffer_get_int(&m);
+
+	buffer_free(&m);
+
+	return (verified);
+}
+
+/* Export key state after authentication */
+Newkeys *
+mm_newkeys_from_blob(u_char *blob, int blen)
+{
+	Buffer b;
+	u_int len;
+	Newkeys *newkey = NULL;
+	Enc *enc;
+	Mac *mac;
+	Comp *comp;
+
+	debug3("%s: %p(%d)", __FUNCTION__, blob, blen);
+#ifdef DEBUG_PK
+	dump_base64(stderr, blob, blen);
+#endif
+	buffer_init(&b);
+	buffer_append(&b, blob, blen);
+
+	newkey = xmalloc(sizeof(*newkey));
+	enc = &newkey->enc;
+	mac = &newkey->mac;
+	comp = &newkey->comp;
+
+	/* Enc structure */
+	enc->name = buffer_get_string(&b, NULL);
+	buffer_get(&b, &enc->cipher, sizeof(enc->cipher));
+	enc->enabled = buffer_get_int(&b);
+	enc->block_size = buffer_get_int(&b);
+	enc->key = buffer_get_string(&b, &enc->key_len);
+	enc->iv = buffer_get_string(&b, &len);
+	if (len != enc->block_size)
+		fatal("%s: bad ivlen: expected %d != %d", __FUNCTION__,
+		    enc->block_size, len);
+
+	if (enc->name == NULL || cipher_by_name(enc->name) != enc->cipher)
+		fatal("%s: bad cipher name %s or pointer %p", __FUNCTION__,
+		    enc->name, enc->cipher);
+
+	/* Mac structure */
+	mac->name = buffer_get_string(&b, NULL);
+	if (mac->name == NULL || mac_init(mac, mac->name) == -1)
+		fatal("%s: can not init mac %s", __FUNCTION__, mac->name);
+	mac->enabled = buffer_get_int(&b);
+	mac->key = buffer_get_string(&b, &len);
+	if (len > mac->key_len)
+		fatal("%s: bad mac key lenght: %d > %d", __FUNCTION__, len,
+		    mac->key_len);
+	mac->key_len = len;
+
+	/* Comp structure */
+	comp->type = buffer_get_int(&b);
+	comp->enabled = buffer_get_int(&b);
+	comp->name = buffer_get_string(&b, NULL);
+
+	len = buffer_len(&b);
+	if (len != 0)
+		error("newkeys_from_blob: remaining bytes in blob %d", len);
+	buffer_free(&b);
+	return (newkey);
+}
+
+int
+mm_newkeys_to_blob(int mode, u_char **blobp, u_int *lenp)
+{
+	Buffer b;
+	int len;
+	u_char *buf;
+	Enc *enc;
+	Mac *mac;
+	Comp *comp;
+	Newkeys *newkey = newkeys[mode];
+
+	debug3("%s: converting %p", __FUNCTION__, newkey);
+
+	if (newkey == NULL) {
+		error("%s: newkey == NULL", __FUNCTION__);
+		return 0;
+	}
+	enc = &newkey->enc;
+	mac = &newkey->mac;
+	comp = &newkey->comp;
+
+	buffer_init(&b);
+	/* Enc structure */
+	buffer_put_cstring(&b, enc->name);
+	/* The cipher struct is constant and shared, you export pointer */
+	buffer_append(&b, &enc->cipher, sizeof(enc->cipher));
+	buffer_put_int(&b, enc->enabled);
+	buffer_put_int(&b, enc->block_size);
+	buffer_put_string(&b, enc->key, enc->key_len);
+	packet_get_keyiv(mode, enc->iv, enc->block_size);
+	buffer_put_string(&b, enc->iv, enc->block_size);
+
+	/* Mac structure */
+	buffer_put_cstring(&b, mac->name);
+	buffer_put_int(&b, mac->enabled);
+	buffer_put_string(&b, mac->key, mac->key_len);
+
+	/* Comp structure */
+	buffer_put_int(&b, comp->type);
+	buffer_put_int(&b, comp->enabled);
+	buffer_put_cstring(&b, comp->name);
+
+	len = buffer_len(&b);
+	buf = xmalloc(len);
+	memcpy(buf, buffer_ptr(&b), len);
+	memset(buffer_ptr(&b), 0, len);
+	buffer_free(&b);
+	if (lenp != NULL)
+		*lenp = len;
+	if (blobp != NULL)
+		*blobp = buf;
+	return len;
+}
+
+static void
+mm_send_kex(Buffer *m, Kex *kex)
+{
+	buffer_put_string(m, kex->session_id, kex->session_id_len);
+	buffer_put_int(m, kex->we_need);
+	buffer_put_int(m, kex->hostkey_type);
+	buffer_put_int(m, kex->kex_type);
+	buffer_put_string(m, buffer_ptr(&kex->my), buffer_len(&kex->my));
+	buffer_put_string(m, buffer_ptr(&kex->peer), buffer_len(&kex->peer));
+	buffer_put_int(m, kex->flags);
+	buffer_put_cstring(m, kex->client_version_string);
+	buffer_put_cstring(m, kex->server_version_string);
+}
+
+void
+mm_send_keystate(struct monitor *monitor)
+{
+	Buffer m;
+	u_char *blob, *p;
+	u_int bloblen, plen;
+
+	buffer_init(&m);
+
+	if (!compat20) {
+		u_char iv[24];
+		int ivlen;
+
+		buffer_put_int(&m, packet_get_protocol_flags());
+
+		buffer_put_int(&m, packet_get_ssh1_cipher());
+
+		debug3("%s: Sending ssh1 IV", __FUNCTION__);
+		ivlen = packet_get_keyiv_len(MODE_OUT);
+		packet_get_keyiv(MODE_OUT, iv, ivlen);
+		buffer_put_string(&m, iv, ivlen);
+		ivlen = packet_get_keyiv_len(MODE_OUT);
+		packet_get_keyiv(MODE_IN, iv, ivlen);
+		buffer_put_string(&m, iv, ivlen);
+		goto skip;
+	} else {
+		/* Kex for rekeying */
+		mm_send_kex(&m, *monitor->m_pkex);
+	}
+
+	debug3("%s: Sending new keys: %p %p",
+	    __FUNCTION__, newkeys[MODE_OUT], newkeys[MODE_IN]);
+
+	/* Keys from Kex */
+	if (!mm_newkeys_to_blob(MODE_OUT, &blob, &bloblen))
+		fatal("%s: conversion of newkeys failed", __FUNCTION__);
+
+	buffer_put_string(&m, blob, bloblen);
+	xfree(blob);
+
+	if (!mm_newkeys_to_blob(MODE_IN, &blob, &bloblen))
+		fatal("%s: conversion of newkeys failed", __FUNCTION__);
+
+	buffer_put_string(&m, blob, bloblen);
+	xfree(blob);
+
+	buffer_put_int(&m, packet_get_seqnr(MODE_OUT));
+	buffer_put_int(&m, packet_get_seqnr(MODE_IN));
+
+	debug3("%s: New keys have been sent", __FUNCTION__);
+ skip:
+	/* More key context */
+	plen = packet_get_keycontext(MODE_OUT, NULL);
+	p = xmalloc(plen+1);
+	packet_get_keycontext(MODE_OUT, p);
+	buffer_put_string(&m, p, plen);
+	xfree(p);
+
+	plen = packet_get_keycontext(MODE_IN, NULL);
+	p = xmalloc(plen+1);
+	packet_get_keycontext(MODE_IN, p);
+	buffer_put_string(&m, p, plen);
+	xfree(p);
+
+	/* Compression state */
+	debug3("%s: Sending compression state", __FUNCTION__);
+	buffer_put_string(&m, &outgoing_stream, sizeof(outgoing_stream));
+	buffer_put_string(&m, &incoming_stream, sizeof(incoming_stream));
+
+	/* Network I/O buffers */
+	buffer_put_string(&m, buffer_ptr(&input), buffer_len(&input));
+	buffer_put_string(&m, buffer_ptr(&output), buffer_len(&output));
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_KEYEXPORT, &m);
+	debug3("%s: Finished sending state", __FUNCTION__);
+
+	buffer_free(&m);
+}
+
+int
+mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
+{
+	Buffer m;
+	u_char *p;
+	int success = 0;
+
+	buffer_init(&m);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_PTY, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_PTY", __FUNCTION__);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_PTY, &m);
+
+	success = buffer_get_int(&m);
+	if (success == 0) {
+		debug3("%s: pty alloc failed", __FUNCTION__);
+		buffer_free(&m);
+		return (0);
+	}
+	p = buffer_get_string(&m, NULL);
+	buffer_free(&m);
+
+	strlcpy(namebuf, p, namebuflen); /* Possible truncation */
+	xfree(p);
+
+	*ptyfd = mm_receive_fd(monitor->m_recvfd);
+	*ttyfd = mm_receive_fd(monitor->m_recvfd);
+
+	/* Success */
+	return (1);
+}
+
+void
+mm_session_pty_cleanup2(void *session)
+{
+	Session *s = session;
+	Buffer m;
+
+	if (s->ttyfd == -1)
+		return;
+	buffer_init(&m);
+	buffer_put_cstring(&m, s->tty);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_PTYCLEANUP, &m);
+	buffer_free(&m);
+
+	/* closed dup'ed master */
+	if (close(s->ptymaster) < 0)
+		error("close(s->ptymaster): %s", strerror(errno));
+
+	/* unlink pty from session */
+	s->ttyfd = -1;
+}
+
+/* Request process termination */
+
+void
+mm_terminate(void)
+{
+	Buffer m;
+
+	buffer_init(&m);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_TERM, &m);
+	buffer_free(&m);
+}
+
+int
+mm_ssh1_session_key(BIGNUM *num)
+{
+	int rsafail;
+	Buffer m;
+
+	buffer_init(&m);
+	buffer_put_bignum2(&m, num);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_SESSKEY, &m);
+
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_SESSKEY, &m);
+
+	rsafail = buffer_get_int(&m);
+	buffer_get_bignum2(&m, num);
+
+	buffer_free(&m);
+
+	return (rsafail);
+}
+
+static void
+mm_chall_setup(char **name, char **infotxt, u_int *numprompts,
+    char ***prompts, u_int **echo_on)
+{
+	*name       = xstrdup("");
+	*infotxt    = xstrdup("");
+	*numprompts = 1;
+	*prompts = xmalloc(*numprompts * sizeof(char*));
+	*echo_on = xmalloc(*numprompts * sizeof(u_int));
+	(*echo_on)[0] = 0;
+}
+
+int
+mm_bsdauth_query(void *ctx, char **name, char **infotxt,
+   u_int *numprompts, char ***prompts, u_int **echo_on)
+{
+	Buffer m;
+	int res;
+	char *challenge;
+
+	debug3("%s: entering", __FUNCTION__);
+
+	buffer_init(&m);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_BSDAUTHQUERY, &m);
+
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_BSDAUTHQUERY,
+	    &m);
+	res = buffer_get_int(&m);
+	if (res == -1) {
+		debug3("%s: no challenge", __FUNCTION__);
+		buffer_free(&m);
+		return (-1);
+	}
+
+	/* Get the challenge, and format the response */
+	challenge  = buffer_get_string(&m, NULL);
+	buffer_free(&m);
+
+	mm_chall_setup(name, infotxt, numprompts, prompts, echo_on);
+	(*prompts)[0] = challenge;
+
+	debug3("%s: received challenge: %s", __FUNCTION__, challenge);
+
+	return (0);
+}
+
+int
+mm_bsdauth_respond(void *ctx, u_int numresponses, char **responses)
+{
+	Buffer m;
+	int authok;
+
+	debug3("%s: entering", __FUNCTION__);
+	if (numresponses != 1)
+		return (-1);
+
+	buffer_init(&m);
+	buffer_put_cstring(&m, responses[0]);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_BSDAUTHRESPOND, &m);
+
+	mm_request_receive_expect(monitor->m_recvfd,
+	    MONITOR_ANS_BSDAUTHRESPOND, &m);
+
+	authok = buffer_get_int(&m);
+	buffer_free(&m);
+
+	return ((authok == 0) ? -1 : 0);
+}
+
+int
+mm_skey_query(void *ctx, char **name, char **infotxt,
+   u_int *numprompts, char ***prompts, u_int **echo_on)
+{
+	Buffer m;
+	int len, res;
+	char *p, *challenge;
+
+	debug3("%s: entering", __FUNCTION__);
+
+	buffer_init(&m);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_SKEYQUERY, &m);
+
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_SKEYQUERY,
+	    &m);
+	res = buffer_get_int(&m);
+	if (res == -1) {
+		debug3("%s: no challenge", __FUNCTION__);
+		buffer_free(&m);
+		return (-1);
+	}
+
+	/* Get the challenge, and format the response */
+	challenge  = buffer_get_string(&m, NULL);
+	buffer_free(&m);
+
+	debug3("%s: received challenge: %s", __FUNCTION__, challenge);
+
+	mm_chall_setup(name, infotxt, numprompts, prompts, echo_on);
+
+	len = strlen(challenge) + strlen(SKEY_PROMPT) + 1;
+	p = xmalloc(len);
+	strlcpy(p, challenge, len);
+	strlcat(p, SKEY_PROMPT, len);
+	(*prompts)[0] = p;
+	xfree(challenge);
+
+	return (0);
+}
+
+int
+mm_skey_respond(void *ctx, u_int numresponses, char **responses)
+{
+	Buffer m;
+	int authok;
+
+	debug3("%s: entering", __FUNCTION__);
+	if (numresponses != 1)
+		return (-1);
+
+	buffer_init(&m);
+	buffer_put_cstring(&m, responses[0]);
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_SKEYRESPOND, &m);
+
+	mm_request_receive_expect(monitor->m_recvfd,
+	    MONITOR_ANS_SKEYRESPOND, &m);
+
+	authok = buffer_get_int(&m);
+	buffer_free(&m);
+
+	return ((authok == 0) ? -1 : 0);
+}
+
+void
+mm_ssh1_session_id(u_char session_id[16])
+{
+	Buffer m;
+	int i;
+
+	debug3("%s entering", __FUNCTION__);
+
+	buffer_init(&m);
+	for (i = 0; i < 16; i++)
+		buffer_put_char(&m, session_id[i]);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_SESSID, &m);
+	buffer_free(&m);
+}
+
+int
+mm_auth_rsa_key_allowed(struct passwd *pw, BIGNUM *client_n, Key **rkey)
+{
+	Buffer m;
+	Key *key;
+	u_char *blob;
+	u_int blen;
+	int allowed = 0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	buffer_init(&m);
+	buffer_put_bignum2(&m, client_n);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_RSAKEYALLOWED, &m);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_RSAKEYALLOWED, &m);
+
+	allowed = buffer_get_int(&m);
+
+	if (allowed && rkey != NULL) {
+		blob = buffer_get_string(&m, &blen);
+		if ((key = key_from_blob(blob, blen)) == NULL)
+			fatal("%s: key_from_blob failed", __FUNCTION__);
+		*rkey = key;
+		xfree(blob);
+	}
+	mm_send_debug(&m);
+	buffer_free(&m);
+
+	return (allowed);
+}
+
+BIGNUM *
+mm_auth_rsa_generate_challenge(Key *key)
+{
+	Buffer m;
+	BIGNUM *challenge;
+	u_char *blob;
+	u_int blen;
+
+	debug3("%s entering", __FUNCTION__);
+
+	if ((challenge = BN_new()) == NULL)
+		fatal("%s: BN_new failed", __FUNCTION__);
+
+	key->type = KEY_RSA;    /* XXX cheat for key_to_blob */
+	if (key_to_blob(key, &blob, &blen) == 0)
+		fatal("%s: key_to_blob failed", __FUNCTION__);
+	key->type = KEY_RSA1;
+
+	buffer_init(&m);
+	buffer_put_string(&m, blob, blen);
+	xfree(blob);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_RSACHALLENGE, &m);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_RSACHALLENGE, &m);
+
+	buffer_get_bignum2(&m, challenge);
+	buffer_free(&m);
+
+	return (challenge);
+}
+
+int
+mm_auth_rsa_verify_response(Key *key, BIGNUM *p, u_char response[16])
+{
+	Buffer m;
+	u_char *blob;
+	u_int blen;
+	int success = 0;
+
+	debug3("%s entering", __FUNCTION__);
+
+	key->type = KEY_RSA;    /* XXX cheat for key_to_blob */
+	if (key_to_blob(key, &blob, &blen) == 0)
+		fatal("%s: key_to_blob failed", __FUNCTION__);
+	key->type = KEY_RSA1;
+
+	buffer_init(&m);
+	buffer_put_string(&m, blob, blen);
+	buffer_put_string(&m, response, 16);
+	xfree(blob);
+
+	mm_request_send(monitor->m_recvfd, MONITOR_REQ_RSARESPONSE, &m);
+	mm_request_receive_expect(monitor->m_recvfd, MONITOR_ANS_RSARESPONSE, &m);
+
+	success = buffer_get_int(&m);
+	buffer_free(&m);
+
+	return (success);
+}
diff --git a/monitor_wrap.h b/monitor_wrap.h
new file mode 100644
index 00000000..a75b9050
--- /dev/null
+++ b/monitor_wrap.h
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MM_WRAP_H_
+#define _MM_WRAP_H_
+#include "key.h"
+#include "buffer.h"
+
+extern int use_privsep;
+#define PRIVSEP(x)	(use_privsep ? mm_##x : x)
+
+enum mm_keytype {MM_NOKEY, MM_HOSTKEY, MM_USERKEY, MM_RSAHOSTKEY, MM_RSAUSERKEY};
+
+struct monitor;
+struct mm_master;
+struct passwd;
+struct Authctxt;
+
+DH *mm_choose_dh(int, int, int);
+int mm_key_sign(Key *, u_char **, u_int *, u_char *, u_int);
+void mm_inform_authserv(char *, char *);
+struct passwd *mm_getpwnamallow(const char *);
+int mm_auth_password(struct Authctxt *, char *);
+int mm_key_allowed(enum mm_keytype, char *, char *, Key *);
+int mm_user_key_allowed(struct passwd *, Key *);
+int mm_hostbased_key_allowed(struct passwd *, char *, char *, Key *);
+int mm_auth_rhosts_rsa_key_allowed(struct passwd *, char *, char *, Key *);
+int mm_key_verify(Key *, u_char *, u_int, u_char *, u_int);
+int mm_auth_rsa_key_allowed(struct passwd *, BIGNUM *, Key **);
+int mm_auth_rsa_verify_response(Key *, BIGNUM *, u_char *);
+BIGNUM *mm_auth_rsa_generate_challenge(Key *);
+
+void mm_terminate(void);
+int mm_pty_allocate(int *, int *, char *, int);
+void mm_session_pty_cleanup2(void *);
+
+/* SSHv1 interfaces */
+void mm_ssh1_session_id(u_char *);
+int mm_ssh1_session_key(BIGNUM *);
+
+/* Key export functions */
+struct Newkeys *mm_newkeys_from_blob(u_char *, int);
+int mm_newkeys_to_blob(int, u_char **, u_int *);
+
+void monitor_apply_keystate(struct monitor *);
+void mm_get_keystate(struct monitor *);
+void mm_send_keystate(struct monitor*);
+
+/* bsdauth */
+int mm_bsdauth_query(void *, char **, char **, u_int *, char ***, u_int **);
+int mm_bsdauth_respond(void *, u_int, char **);
+
+/* skey */
+int mm_skey_query(void *, char **, char **, u_int *, char ***, u_int **);
+int mm_skey_respond(void *, u_int, char **);
+
+/* zlib allocation hooks */
+
+void *mm_zalloc(struct mm_master *, u_int, u_int);
+void mm_zfree(struct mm_master *, void *);
+void mm_init_compression(struct mm_master *);
+
+#endif /* _MM_H_ */
diff --git a/servconf.c b/servconf.c
index 9bbd994c..3b6b55e9 100644
--- a/servconf.c
+++ b/servconf.c
@@ -10,7 +10,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: servconf.c,v 1.101 2002/02/04 12:15:25 markus Exp $");
+RCSID("$OpenBSD: servconf.c,v 1.102 2002/03/18 17:50:31 provos Exp $");
 
 #if defined(KRB4) || defined(KRB5)
 #include <krb.h>
@@ -36,6 +36,8 @@ static void add_one_listen_addr(ServerOptions *, char *, u_short);
 
 /* AF_UNSPEC or AF_INET or AF_INET6 */
 extern int IPv4or6;
+/* Use of privilege separation or not */
+extern int use_privsep;
 
 /* Initializes the server options to their default values. */
 
@@ -110,6 +112,13 @@ initialize_server_options(ServerOptions *options)
 	options->client_alive_count_max = -1;
 	options->authorized_keys_file = NULL;
 	options->authorized_keys_file2 = NULL;
+
+	options->unprivileged_user = -1;
+	options->unprivileged_group = -1;
+	options->unprivileged_dir = NULL;
+
+	/* Needs to be accessable in many places */
+	use_privsep = -1;
 }
 
 void
@@ -235,6 +244,16 @@ fill_default_server_options(ServerOptions *options)
 	}
 	if (options->authorized_keys_file == NULL)
 		options->authorized_keys_file = _PATH_SSH_USER_PERMITTED_KEYS;
+
+	/* Turn privilege separation _off_ by default */
+	if (use_privsep == -1)
+		use_privsep = 0;
+	if (options->unprivileged_user == -1)
+		options->unprivileged_user = 32767;
+	if (options->unprivileged_group == -1)
+		options->unprivileged_group = 32767;
+	if (options->unprivileged_dir == NULL)
+		options->unprivileged_dir = "/var/empty";
 }
 
 /* Keyword tokens. */
@@ -267,6 +286,7 @@ typedef enum {
 	sBanner, sVerifyReverseMapping, sHostbasedAuthentication,
 	sHostbasedUsesNameFromPacketOnly, sClientAliveInterval,
 	sClientAliveCountMax, sAuthorizedKeysFile, sAuthorizedKeysFile2,
+	sUsePrivilegeSeparation, sUnprivUser, sUnprivGroup, sUnprivDir,
 	sDeprecated
 } ServerOpCodes;
 
@@ -342,6 +362,10 @@ static struct {
 	{ "clientalivecountmax", sClientAliveCountMax },
 	{ "authorizedkeysfile", sAuthorizedKeysFile },
 	{ "authorizedkeysfile2", sAuthorizedKeysFile2 },
+	{ "useprivilegeseparation", sUsePrivilegeSeparation},
+	{ "unprivuser", sUnprivUser},
+	{ "unprivgroup", sUnprivGroup},
+	{ "unprivdir", sUnprivDir},
 	{ NULL, sBadOption }
 };
 
@@ -718,6 +742,22 @@ parse_flag:
 		intptr = &options->allow_tcp_forwarding;
 		goto parse_flag;
 
+	case sUsePrivilegeSeparation:
+		intptr = &use_privsep;
+		goto parse_flag;
+
+	case sUnprivUser:
+		intptr = &options->unprivileged_user;
+		goto parse_flag;
+
+	case sUnprivGroup:
+		intptr = &options->unprivileged_group;
+		goto parse_flag;
+
+	case sUnprivDir:
+		charptr = &options->unprivileged_dir;
+		goto parse_filename;
+
 	case sAllowUsers:
 		while ((arg = strdelim(&cp)) && *arg != '\0') {
 			if (options->num_allow_users >= MAX_ALLOW_USERS)
diff --git a/servconf.h b/servconf.h
index 3134b222..b5d110a5 100644
--- a/servconf.h
+++ b/servconf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: servconf.h,v 1.54 2002/03/04 17:27:39 stevesk Exp $	*/
+/*	$OpenBSD: servconf.h,v 1.55 2002/03/18 17:50:31 provos Exp $	*/
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -131,6 +131,9 @@ typedef struct {
 	char   *authorized_keys_file2;
 	int	pam_authentication_via_kbd_int;
 
+	int	unprivileged_user;	/* User unprivileged child uses */
+	int	unprivileged_group;	/* Group unprivileged child uses */
+	char   *unprivileged_dir;	/* Chroot dir for unprivileged user */
 }       ServerOptions;
 
 void	 initialize_server_options(ServerOptions *);
diff --git a/serverloop.c b/serverloop.c
index 46b12ee3..f3a65918 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -35,7 +35,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: serverloop.c,v 1.98 2002/02/06 14:55:16 markus Exp $");
+RCSID("$OpenBSD: serverloop.c,v 1.99 2002/03/18 17:50:31 provos Exp $");
 
 #include "xmalloc.h"
 #include "packet.h"
@@ -784,7 +784,7 @@ server_loop2(Authctxt *authctxt)
 	channel_free_all();
 
 	/* free remaining sessions, e.g. remove wtmp entries */
-	session_destroy_all();
+	session_destroy_all(NULL);
 }
 
 static void
diff --git a/session.c b/session.c
index 29467029..e5ea637d 100644
--- a/session.c
+++ b/session.c
@@ -33,7 +33,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: session.c,v 1.129 2002/03/18 03:41:08 provos Exp $");
+RCSID("$OpenBSD: session.c,v 1.130 2002/03/18 17:50:31 provos Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -56,6 +56,7 @@ RCSID("$OpenBSD: session.c,v 1.129 2002/03/18 03:41:08 provos Exp $");
 #include "serverloop.h"
 #include "canohost.h"
 #include "session.h"
+#include "monitor_wrap.h"
 
 #ifdef HAVE_CYGWIN
 #include <windows.h>
@@ -63,39 +64,11 @@ RCSID("$OpenBSD: session.c,v 1.129 2002/03/18 03:41:08 provos Exp $");
 #define is_winnt       (GetVersion() < 0x80000000)
 #endif
 
-/* types */
-
-#define TTYSZ 64
-typedef struct Session Session;
-struct Session {
-	int	used;
-	int	self;
-	struct passwd *pw;
-	Authctxt *authctxt;
-	pid_t	pid;
-	/* tty */
-	char	*term;
-	int	ptyfd, ttyfd, ptymaster;
-	int	row, col, xpixel, ypixel;
-	char	tty[TTYSZ];
-	/* X11 */
-	int	display_number;
-	char	*display;
-	int	screen;
-	char	*auth_display;
-	char	*auth_proto;
-	char	*auth_data;
-	int	single_connection;
-	/* proto 2 */
-	int	chanid;
-	int	is_subsystem;
-};
-
 /* func */
 
 Session *session_new(void);
 void	session_set_fds(Session *, int, int, int);
-static void	session_pty_cleanup(void *);
+void	session_pty_cleanup(void *);
 void	session_proctitle(Session *);
 int	session_setup_x11fwd(Session *);
 void	do_exec_pty(Session *, const char *);
@@ -112,7 +85,6 @@ int	check_quietlogin(Session *, const char *);
 static void do_authenticated1(Authctxt *);
 static void do_authenticated2(Authctxt *);
 
-static void session_close(Session *);
 static int session_pty_req(Session *);
 
 /* import */
@@ -1087,7 +1059,7 @@ do_nologin(struct passwd *pw)
 }
 
 /* Set login name, uid, gid, and groups. */
-static void
+void
 do_setusercontext(struct passwd *pw)
 {
 #ifdef HAVE_CYGWIN
@@ -1142,6 +1114,23 @@ do_setusercontext(struct passwd *pw)
 		fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
 }
 
+void
+launch_login(struct passwd *pw, const char *hostname)
+{
+	/* Launch login(1). */
+
+	execl("/usr/bin/login", "login", "-h", hostname,
+#ifdef LOGIN_NEEDS_TERM
+                    (s->term ? s->term : "unknown"),
+#endif /* LOGIN_NEEDS_TERM */
+	    "-p", "-f", "--", pw->pw_name, (char *)NULL);
+
+	/* Login couldn't be executed, die. */
+
+	perror("login");
+	exit(1);
+}
+
 /*
  * Performs common processing for the child, such as setting up the
  * environment, closing extra file descriptors, setting the user and group
@@ -1267,18 +1256,8 @@ do_child(Session *s, const char *command)
 	signal(SIGPIPE,  SIG_DFL);
 
 	if (options.use_login) {
-		/* Launch login(1). */
-
-		execl(LOGIN_PROGRAM, "login", "-h", hostname,
-#ifdef LOGIN_NEEDS_TERM
-		    (s->term ? s->term : "unknown"),
-#endif /* LOGIN_NEEDS_TERM */
-		    "-p", "-f", "--", pw->pw_name, (char *)NULL);
-
-		/* Login couldn't be executed, die. */
-
-		perror("login");
-		exit(1);
+		launch_login(pw, hostname);
+		/* NEVERREACHED */
 	}
 
 	/* Get the last component of the shell name. */
@@ -1388,6 +1367,22 @@ session_open(Authctxt *authctxt, int chanid)
 	return 1;
 }
 
+Session *
+session_by_tty(char *tty)
+{
+	int i;
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
+			debug("session_by_tty: session %d tty %s", i, tty);
+			return s;
+		}
+	}
+	debug("session_by_tty: unknown tty %.100s", tty);
+	session_dump();
+	return NULL;
+}
+
 static Session *
 session_by_channel(int id)
 {
@@ -1436,7 +1431,7 @@ session_pty_req(Session *s)
 {
 	u_int len;
 	int n_bytes;
-
+	
 	if (no_pty_flag) {
 		debug("Allocating a pty not permitted for this authentication.");
 		return 0;
@@ -1465,7 +1460,7 @@ session_pty_req(Session *s)
 
 	/* Allocate a pty and open it. */
 	debug("Allocating pty.");
-	if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) {
+	if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) {
 		if (s->term)
 			xfree(s->term);
 		s->term = NULL;
@@ -1486,7 +1481,8 @@ session_pty_req(Session *s)
 	 * time in case we call fatal() (e.g., the connection gets closed).
 	 */
 	fatal_add_cleanup(session_pty_cleanup, (void *)s);
-	pty_setowner(s->pw, s->tty);
+	if (!use_privsep)
+		pty_setowner(s->pw, s->tty);
 
 	/* Set window size from the packet. */
 	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
@@ -1649,8 +1645,8 @@ session_set_fds(Session *s, int fdin, int fdout, int fderr)
  * Function to perform pty cleanup. Also called if we get aborted abnormally
  * (e.g., due to a dropped connection).
  */
-static void
-session_pty_cleanup(void *session)
+void
+session_pty_cleanup2(void *session)
 {
 	Session *s = session;
 
@@ -1668,7 +1664,8 @@ session_pty_cleanup(void *session)
 		record_logout(s->pid, s->tty, s->pw->pw_name);
 
 	/* Release the pseudo-tty. */
-	pty_release(s->tty);
+	if (getuid() == 0)
+		pty_release(s->tty);
 
 	/*
 	 * Close the server side of the socket pairs.  We must do this after
@@ -1676,12 +1673,18 @@ session_pty_cleanup(void *session)
 	 * while we're still cleaning up.
 	 */
 	if (close(s->ptymaster) < 0)
-		error("close(s->ptymaster): %s", strerror(errno));
+		error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno));
 
 	/* unlink pty from session */
 	s->ttyfd = -1;
 }
 
+void
+session_pty_cleanup(void *session)
+{
+	PRIVSEP(session_pty_cleanup2(session));
+}
+
 static void
 session_exit_message(Session *s, int status)
 {
@@ -1727,7 +1730,7 @@ session_exit_message(Session *s, int status)
 	s->chanid = -1;
 }
 
-static void
+void
 session_close(Session *s)
 {
 	debug("session_close: session %d pid %d", s->self, s->pid);
@@ -1794,13 +1797,17 @@ session_close_by_channel(int id, void *arg)
 }
 
 void
-session_destroy_all(void)
+session_destroy_all(void (*closefunc)(Session *))
 {
 	int i;
 	for (i = 0; i < MAX_SESSIONS; i++) {
 		Session *s = &sessions[i];
-		if (s->used)
-			session_close(s);
+		if (s->used) {
+			if (closefunc != NULL)
+				closefunc(s);
+			else
+				session_close(s);
+		}
 	}
 }
 
diff --git a/session.h b/session.h
index ec8284a5..81f024c9 100644
--- a/session.h
+++ b/session.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: session.h,v 1.14 2002/02/03 17:53:25 markus Exp $	*/
+/*	$OpenBSD: session.h,v 1.15 2002/03/18 17:50:31 provos Exp $	*/
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -26,12 +26,42 @@
 #ifndef SESSION_H
 #define SESSION_H
 
+#define TTYSZ 64
+typedef struct Session Session;
+struct Session {
+	int	used;
+	int	self;
+	struct passwd *pw;
+	Authctxt *authctxt;
+	pid_t	pid;
+	/* tty */
+	char	*term;
+	int	ptyfd, ttyfd, ptymaster;
+	int	row, col, xpixel, ypixel;
+	char	tty[TTYSZ];
+	/* X11 */
+	int	display_number;
+	char	*display;
+	int	screen;
+	char	*auth_display;
+	char	*auth_proto;
+	char	*auth_data;
+	int	single_connection;
+	/* proto 2 */
+	int	chanid;
+	int	is_subsystem;
+};
+
 void	 do_authenticated(Authctxt *);
 
 int	 session_open(Authctxt*, int);
 int	 session_input_channel_req(Channel *, const char *);
 void	 session_close_by_pid(pid_t, int);
 void	 session_close_by_channel(int, void *);
-void	 session_destroy_all(void);
+void	 session_destroy_all(void (*)(Session *));
 
+Session	*session_new(void);
+Session	*session_by_tty(char *);
+void	 session_close(Session *);
+void	 do_setusercontext(struct passwd *);
 #endif
diff --git a/sshd.c b/sshd.c
index 0764588f..c82603d5 100644
--- a/sshd.c
+++ b/sshd.c
@@ -15,8 +15,10 @@
  * called by a name other than "ssh" or "Secure Shell".
  *
  * SSH2 implementation:
+ * Privilege Separation:
  *
- * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2002 Niels Provos.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -40,11 +42,12 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshd.c,v 1.230 2002/03/18 01:12:14 provos Exp $");
+RCSID("$OpenBSD: sshd.c,v 1.231 2002/03/18 17:50:31 provos Exp $");
 
 #include <openssl/dh.h>
 #include <openssl/bn.h>
 #include <openssl/md5.h>
+#include <openssl/rand.h>
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -73,6 +76,10 @@ RCSID("$OpenBSD: sshd.c,v 1.230 2002/03/18 01:12:14 provos Exp $");
 #include "dispatch.h"
 #include "channels.h"
 #include "session.h"
+#include "monitor_mm.h"
+#include "monitor.h"
+#include "monitor_wrap.h"
+#include "monitor_fdpass.h"
 
 #ifdef LIBWRAP
 #include <tcpd.h>
@@ -190,8 +197,13 @@ u_int utmp_len = MAXHOSTNAMELEN;
 int *startup_pipes = NULL;
 int startup_pipe;		/* in child */
 
+/* variables used for privilege separation */
+extern struct monitor *monitor;
+extern int use_privsep;
+
 /* Prototypes for various functions defined later in this file. */
 void destroy_sensitive_data(void);
+void demote_sensitive_data(void);
 
 static void do_ssh1_kex(void);
 static void do_ssh2_kex(void);
@@ -478,6 +490,115 @@ destroy_sensitive_data(void)
 	memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
 }
 
+/* Demote private to public keys for network child */
+void
+demote_sensitive_data(void)
+{
+	Key *tmp;
+	int i;
+
+	if (sensitive_data.server_key) {
+		tmp = key_demote(sensitive_data.server_key);
+		key_free(sensitive_data.server_key);
+		sensitive_data.server_key = tmp;
+	}
+
+	for (i = 0; i < options.num_host_key_files; i++) {
+		if (sensitive_data.host_keys[i]) {
+			tmp = key_demote(sensitive_data.host_keys[i]);
+			key_free(sensitive_data.host_keys[i]);
+			sensitive_data.host_keys[i] = tmp;
+			if (tmp->type == KEY_RSA1)
+				sensitive_data.ssh1_host_key = tmp;
+		}
+	}
+
+	/* We do not clear ssh1_host key and cookie.  XXX - Okay Niels? */
+}
+
+void
+privsep_preauth_child(void)
+{
+	u_int32_t rand[256];
+	int i;
+
+	/* Enable challenge-response authentication for privilege separation */
+	privsep_challenge_enable();
+
+	for (i = 0; i < 256; i++)
+		rand[i] = arc4random();
+	RAND_seed(rand, sizeof(rand));
+
+	/* Demote the private keys to public keys. */
+	demote_sensitive_data();
+
+	/* Change our root directory*/
+	if (chroot(options.unprivileged_dir) == -1)
+		fatal("chroot(/var/empty)");
+	if (chdir("/") == -1)
+		fatal("chdir(/)");
+		
+	/* Drop our privileges */
+	setegid(options.unprivileged_group);
+	setgid(options.unprivileged_group);
+	seteuid(options.unprivileged_user);
+	setuid(options.unprivileged_user);
+}
+
+void
+privsep_postauth(Authctxt *authctxt, pid_t pid)
+{
+	extern Authctxt *x_authctxt;
+	int status;
+
+	/* Wait for the child's exit status */
+	waitpid(pid, &status, 0);
+
+	/* XXX - Remote port forwarding */
+	x_authctxt = authctxt;
+
+	if (authctxt->pw->pw_uid == 0 || options.use_login) {
+		/* File descriptor passing is broken or root login */
+		monitor_apply_keystate(monitor);
+		use_privsep = 0;
+		return;
+	}
+	
+	/* Authentication complete */
+	alarm(0);
+	if (startup_pipe != -1) {
+		close(startup_pipe);
+		startup_pipe = -1;
+	}
+
+	/* New socket pair */
+	monitor_reinit(monitor);
+
+	monitor->m_pid = fork();
+	if (monitor->m_pid == -1)
+		fatal("fork of unprivileged child failed");
+	else if (monitor->m_pid != 0) {
+		debug2("User child is on pid %d", pid);
+		close(monitor->m_recvfd);
+		monitor_child_postauth(monitor);
+
+		/* NEVERREACHED */
+		exit(0);
+	}
+
+	close(monitor->m_sendfd);
+
+	/* Demote the private keys to public keys. */
+	demote_sensitive_data();
+
+	/* Drop privileges */
+	do_setusercontext(authctxt->pw);
+
+	/* It is safe now to apply the key state */
+	monitor_apply_keystate(monitor);
+}
+
+
 static char *
 list_hostkey_types(void)
 {
@@ -507,7 +628,7 @@ list_hostkey_types(void)
 	return p;
 }
 
-static Key *
+Key *
 get_hostkey_by_type(int type)
 {
 	int i;
@@ -519,6 +640,25 @@ get_hostkey_by_type(int type)
 	return NULL;
 }
 
+Key *
+get_hostkey_by_index(int ind)
+{
+	if (ind < 0 || ind >= options.num_host_key_files)
+		return (NULL);
+	return (sensitive_data.host_keys[ind]);
+}
+
+int
+get_hostkey_index(Key *key)
+{
+	int i;
+	for (i = 0; i < options.num_host_key_files; i++) {
+		if (key == sensitive_data.host_keys[i])
+			return (i);
+	}
+	return (-1);
+}
+
 /*
  * returns 1 if connection should be dropped, 0 otherwise.
  * dropping starts at connection #max_startups_begin with a probability
@@ -1233,6 +1373,37 @@ main(int ac, char **av)
 
 	packet_set_nonblocking();
 
+	if (!use_privsep)
+		goto skip_privilegeseparation;
+		
+	/* Set up unprivileged child process to deal with network data */
+	monitor = monitor_init();
+	/* Store a pointer to the kex for later rekeying */
+	monitor->m_pkex = &xxx_kex;
+
+	pid = fork();
+	if (pid == -1)
+		fatal("fork of unprivileged child failed");
+	else if (pid != 0) {
+		debug2("Network child is on pid %d", pid);
+
+		close(monitor->m_recvfd);
+		authctxt = monitor_child_preauth(monitor);
+		close(monitor->m_sendfd);
+
+		/* Sync memory */
+		monitor_sync(monitor);
+		goto authenticated;
+	} else {
+		close(monitor->m_sendfd);
+
+		/* Demote the child */
+		if (getuid() == 0 || geteuid() == 0)
+			privsep_preauth_child();
+	}
+
+ skip_privilegeseparation:
+
 	/* perform the key exchange */
 	/* authenticate user and start session */
 	if (compat20) {
@@ -1242,6 +1413,23 @@ main(int ac, char **av)
 		do_ssh1_kex();
 		authctxt = do_authentication();
 	}
+	if (use_privsep)
+		mm_send_keystate(monitor);
+
+	/* If we use privilege separation, the unprivileged child exits */
+	if (use_privsep)
+		exit(0);
+
+ authenticated:
+	/* 
+	 * In privilege separation, we fork another child and prepare
+	 * file descriptor passing.
+	 */
+	if (use_privsep) {
+		privsep_postauth(authctxt, pid);
+		if (!compat20)
+			destroy_sensitive_data();
+	}
 
 	/* Perform session preparation. */
 	do_authenticated(authctxt);
@@ -1254,6 +1442,10 @@ main(int ac, char **av)
 #endif /* USE_PAM */
 
 	packet_close();
+
+	if (use_privsep)
+		mm_terminate();
+
 	exit(0);
 }
 
@@ -1261,7 +1453,7 @@ main(int ac, char **av)
  * Decrypt session_key_int using our private server key and private host key
  * (key with larger modulus first).
  */
-static int
+int
 ssh1_session_key(BIGNUM *session_key_int)
 {
 	int rsafail = 0;
@@ -1417,7 +1609,8 @@ do_ssh1_kex(void)
 	packet_check_eom();
 
 	/* Decrypt session_key_int using host/server keys */
-	rsafail = ssh1_session_key(session_key_int);
+	rsafail = PRIVSEP(ssh1_session_key(session_key_int));
+
 	/*
 	 * Extract session key from the decrypted integer.  The key is in the
 	 * least significant 256 bits of the integer; the first byte of the
@@ -1468,9 +1661,12 @@ do_ssh1_kex(void)
 		for (i = 0; i < 16; i++)
 			session_id[i] = session_key[i] ^ session_key[i + 16];
 	}
-	/* Destroy the private and public keys.  They will no longer be needed. */
+	/* Destroy the private and public keys. No longer. */
 	destroy_sensitive_data();
 
+	if (use_privsep)
+		mm_ssh1_session_id(session_id);
+
 	/* Destroy the decrypted integer.  It is no longer needed. */
 	BN_clear_free(session_key_int);
 
@@ -1517,6 +1713,7 @@ do_ssh2_kex(void)
 	kex->client_version_string=client_version_string;
 	kex->server_version_string=server_version_string;
 	kex->load_host_key=&get_hostkey_by_type;
+	kex->host_key_index=&get_hostkey_index;
 
 	xxx_kex = kex;