Return to monitor.c CVS log

Up to [local] / src / usr.bin / ssh

make file descriptor passing code return an error rather than call fatal()
when it encounters problems, and use this to make session multiplexing
masters survive slaves failing to pass all stdio FDs; ok markus@

/* $OpenBSD: monitor.c,v 1.92 2007/09/04 03:21:03 djm Exp $ */
/*
 * 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 <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/tree.h>
#include <sys/param.h>

#include <openssl/dh.h>

#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>

#ifdef SKEY
#include <skey.h>
#endif

#include "xmalloc.h"
#include "ssh.h"
#include "key.h"
#include "buffer.h"
#include "hostfile.h"
#include "auth.h"
#include "cipher.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"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "monitor_fdpass.h"
#include "misc.h"
#include "compat.h"
#include "ssh2.h"

#ifdef GSSAPI
static Gssctxt *gsscontext = NULL;
#endif

/* 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;
extern Buffer loginmsg;

/* 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;
	u_char *ssh1key;
	u_int ssh1keylen;
	int ssh1cipher;
	int ssh1protoflags;
	u_char *input;
	u_int ilen;
	u_char *output;
	u_int olen;
} child_state;

/* Functions on the monitor 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_auth2_read_banner(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 *);

#ifdef GSSAPI
int mm_answer_gss_setup_ctx(int, Buffer *);
int mm_answer_gss_accept_ctx(int, Buffer *);
int mm_answer_gss_userok(int, Buffer *);
int mm_answer_gss_checkmic(int, Buffer *);
#endif

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 char *hostbased_cuser = NULL;
static char *hostbased_chost = NULL;
static char *auth_method = "unknown";
static u_int session_id2_len = 0;
static u_char *session_id2 = NULL;
static pid_t monitor_child_pid;

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_ALOG	0x0020	/* Log auth attempt without authenticating */

#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_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner},
    {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},
#ifdef GSSAPI
    {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
    {MONITOR_REQ_GSSSTEP, MON_ISAUTH, mm_answer_gss_accept_ctx},
    {MONITOR_REQ_GSSUSEROK, MON_AUTH, mm_answer_gss_userok},
    {MONITOR_REQ_GSSCHECKMIC, MON_ISAUTH, mm_answer_gss_checkmic},
#endif
    {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|MON_ALOG, mm_answer_rsa_keyallowed},
    {MONITOR_REQ_KEYALLOWED, MON_ISAUTH|MON_ALOG, 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++;
	}
}

void
monitor_child_preauth(Authctxt *_authctxt, struct monitor *pmonitor)
{
	struct mon_table *ent;
	int authenticated = 0;

	debug3("preauth child monitor started");

	authctxt = _authctxt;
	memset(authctxt, 0, sizeof(*authctxt));

	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);
	}

	/* The first few requests do not require asynchronous access */
	while (!authenticated) {
		auth_method = "unknown";
		authenticated = (monitor_read(pmonitor, mon_dispatch, &ent) == 1);
		if (authenticated) {
			if (!(ent->flags & MON_AUTHDECIDE))
				fatal("%s: unexpected authentication from %d",
				    __func__, ent->type);
			if (authctxt->pw->pw_uid == 0 &&
			    !auth_root_allowed(auth_method))
				authenticated = 0;
		}

		if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
			auth_log(authctxt, authenticated, auth_method,
			    compat20 ? " ssh2" : "");
			if (!authenticated)
				authctxt->failures++;
		}
	}

	if (!authctxt->valid)
		fatal("%s: authenticated invalid user", __func__);
	if (strcmp(auth_method, "unknown") == 0)
		fatal("%s: authentication method name unknown", __func__);

	debug("%s: %s has been authenticated by privileged process",
	    __func__, authctxt->user);

	mm_get_keystate(pmonitor);
}

static void
monitor_set_child_handler(pid_t pid)
{
	monitor_child_pid = pid;
}

static void
monitor_child_handler(int sig)
{
	kill(monitor_child_pid, sig);
}

void
monitor_child_postauth(struct monitor *pmonitor)
{
	monitor_set_child_handler(pmonitor->m_pid);
	signal(SIGHUP, &monitor_child_handler);
	signal(SIGTERM, &monitor_child_handler);
	signal(SIGINT, &monitor_child_handler);

	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(pmonitor, mon_dispatch, NULL);
}

void
monitor_sync(struct monitor *pmonitor)
{
	if (options.compression) {
		/* The member allocation is not visible, so sync it */
		mm_share_sync(&pmonitor->m_zlib, &pmonitor->m_zback);
	}
}

int
monitor_read(struct monitor *pmonitor, struct mon_table *ent,
    struct mon_table **pent)
{
	Buffer m;
	int ret;
	u_char type;

	buffer_init(&m);

	mm_request_receive(pmonitor->m_sendfd, &m);
	type = buffer_get_char(&m);

	debug3("%s: checking request %d", __func__, 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", __func__,
			    type);
		ret = (*ent->f)(pmonitor->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", __func__,
			    type);
			ent->flags &= ~MON_PERMIT;
		}

		if (pent != NULL)
			*pent = ent;

		return ret;
	}

	fatal("%s: unsupported request: %d", __func__, 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 sock, 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",
	    __func__, 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",
		    __func__, 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(sock, MONITOR_ANS_MODULI, m);
	return (0);
}

int
mm_answer_sign(int sock, Buffer *m)
{
	Key *key;
	u_char *p;
	u_char *signature;
	u_int siglen, datlen;
	int keyid;

	debug3("%s", __func__);

	keyid = buffer_get_int(m);
	p = buffer_get_string(m, &datlen);

	/*
	 * Supported KEX types will only return SHA1 (20 byte) or
	 * SHA256 (32 byte) hashes
	 */
	if (datlen != 20 && datlen != 32)
		fatal("%s: data length incorrect: %u", __func__, datlen);

	/* save session id, it will be passed on the first call */
	if (session_id2_len == 0) {
		session_id2_len = datlen;
		session_id2 = xmalloc(session_id2_len);
		memcpy(session_id2, p, session_id2_len);
	}

	if ((key = get_hostkey_by_index(keyid)) == NULL)
		fatal("%s: no hostkey from index %d", __func__, keyid);
	if (key_sign(key, &signature, &siglen, p, datlen) < 0)
		fatal("%s: key_sign failed", __func__);

	debug3("%s: signature %p(%u)", __func__, signature, siglen);

	buffer_clear(m);
	buffer_put_string(m, signature, siglen);

	xfree(p);
	xfree(signature);

	mm_request_send(sock, 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 sock, Buffer *m)
{
	char *username;
	struct passwd *pwent;
	int allowed = 0;

	debug3("%s", __func__);

	if (authctxt->attempt++ != 0)
		fatal("%s: multiple attempts for getpwnam", __func__);

	username = buffer_get_string(m, NULL);

	pwent = getpwnamallow(username);

	authctxt->user = xstrdup(username);
	setproctitle("%s [priv]", pwent ? username : "unknown");
	xfree(username);

	buffer_clear(m);

	if (pwent == NULL) {
		buffer_put_char(m, 0);
		authctxt->pw = fakepw();
		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);
	buffer_put_string(m, &options, sizeof(options));
	if (options.banner != NULL)
		buffer_put_cstring(m, options.banner);

 out:
	debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed);
	mm_request_send(sock, 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);
		monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1);
	}


	return (0);
}

int mm_answer_auth2_read_banner(int sock, Buffer *m)
{
	char *banner;

	buffer_clear(m);
	banner = auth2_read_banner();
	buffer_put_cstring(m, banner != NULL ? banner : "");
	mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);

	if (banner != NULL)
		xfree(banner);

	return (0);
}

int
mm_answer_authserv(int sock, 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",
	    __func__, authctxt->service, authctxt->style);

	if (strlen(authctxt->style) == 0) {
		xfree(authctxt->style);
		authctxt->style = NULL;
	}

	return (0);
}

int
mm_answer_authpassword(int sock, Buffer *m)
{
	static int call_count;
	char *passwd;
	int authenticated;
	u_int plen;

	passwd = buffer_get_string(m, &plen);
	/* Only authenticate if the context is valid */
	authenticated = options.password_authentication &&
	    auth_password(authctxt, passwd);
	memset(passwd, 0, strlen(passwd));
	xfree(passwd);

	buffer_clear(m);
	buffer_put_int(m, authenticated);

	debug3("%s: sending result %d", __func__, authenticated);
	mm_request_send(sock, 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 sock, Buffer *m)
{
	char *name, *infotxt;
	u_int numprompts;
	u_int *echo_on;
	char **prompts;
	u_int success;

	success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
	    &prompts, &echo_on) < 0 ? 0 : 1;

	buffer_clear(m);
	buffer_put_int(m, success);
	if (success)
		buffer_put_cstring(m, prompts[0]);

	debug3("%s: sending challenge success: %u", __func__, success);
	mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);

	if (success) {
		xfree(name);
		xfree(infotxt);
		xfree(prompts);
		xfree(echo_on);
	}

	return (0);
}

int
mm_answer_bsdauthrespond(int sock, Buffer *m)
{
	char *response;
	int authok;

	if (authctxt->as == 0)
		fatal("%s: no bsd auth session", __func__);

	response = buffer_get_string(m, NULL);
	authok = options.challenge_response_authentication &&
	    auth_userresponse(authctxt->as, response, 0);
	authctxt->as = NULL;
	debug3("%s: <%s> = <%d>", __func__, response, authok);
	xfree(response);

	buffer_clear(m);
	buffer_put_int(m, authok);

	debug3("%s: sending authenticated: %d", __func__, authok);
	mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);

	auth_method = "bsdauth";

	return (authok != 0);
}
#endif

#ifdef SKEY
int
mm_answer_skeyquery(int sock, Buffer *m)
{
	struct skey skey;
	char challenge[1024];
	u_int success;

	success = skeychallenge(&skey, authctxt->user, challenge) < 0 ? 0 : 1;

	buffer_clear(m);
	buffer_put_int(m, success);
	if (success)
		buffer_put_cstring(m, challenge);

	debug3("%s: sending challenge success: %u", __func__, success);
	mm_request_send(sock, MONITOR_ANS_SKEYQUERY, m);

	return (0);
}

int
mm_answer_skeyrespond(int sock, Buffer *m)
{
	char *response;
	int authok;

	response = buffer_get_string(m, NULL);

	authok = (options.challenge_response_authentication &&
	    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", __func__, authok);
	mm_request_send(sock, 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", __func__);
		buffer_append(m, buffer_ptr(&auth_debug),
		    buffer_len(&auth_debug));
		buffer_clear(&auth_debug);
	}
}

int
mm_answer_keyallowed(int sock, Buffer *m)
{
	Key *key;
	char *cuser, *chost;
	u_char *blob;
	u_int bloblen;
	enum mm_keytype type = 0;
	int allowed = 0;

	debug3("%s entering", __func__);

	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", __func__);

	debug3("%s: key_from_blob: %p", __func__, key);

	if (key != NULL && authctxt->valid) {
		switch (type) {
		case MM_USERKEY:
			allowed = options.pubkey_authentication &&
			    user_key_allowed(authctxt->pw, key);
			auth_method = "publickey";
			break;
		case MM_HOSTKEY:
			allowed = options.hostbased_authentication &&
			    hostbased_key_allowed(authctxt->pw,
			    cuser, chost, key);
			auth_method = "hostbased";
			break;
		case MM_RSAHOSTKEY:
			key->type = KEY_RSA1; /* XXX */
			allowed = options.rhosts_rsa_authentication &&
			    auth_rhosts_rsa_key_allowed(authctxt->pw,
			    cuser, chost, key);
			auth_method = "rsa";
			break;
		default:
			fatal("%s: unknown key type %d", __func__, type);
			break;
		}
	}
	if (key != NULL)
		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;
	} else {
		/* Log failed attempt */
		auth_log(authctxt, 0, auth_method, compat20 ? " ssh2" : "");
		xfree(blob);
		xfree(cuser);
		xfree(chost);
	}

	debug3("%s: key %p is %s",
	    __func__, key, allowed ? "allowed" : "disallowed");

	buffer_clear(m);
	buffer_put_int(m, allowed);
	buffer_put_int(m, forced_command != NULL);

	mm_append_debug(m);

	mm_request_send(sock, 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;
	char *p;
	u_int len;
	int fail = 0;

	buffer_init(&b);
	buffer_append(&b, data, datalen);

	if (datafellows & SSH_OLD_SESSIONID) {
		p = buffer_ptr(&b);
		len = buffer_len(&b);
		if ((session_id2 == NULL) ||
		    (len < session_id2_len) ||
		    (memcmp(p, session_id2, session_id2_len) != 0))
			fail++;
		buffer_consume(&b, session_id2_len);
	} else {
		p = buffer_get_string(&b, &len);
		if ((session_id2 == NULL) ||
		    (len != session_id2_len) ||
		    (memcmp(p, session_id2, session_id2_len) != 0))
			fail++;
		xfree(p);
	}
	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
		fail++;
	p = buffer_get_string(&b, NULL);
	if (strcmp(authctxt->user, p) != 0) {
		logit("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, char *cuser,
    char *chost)
{
	Buffer b;
	char *p;
	u_int len;
	int fail = 0;

	buffer_init(&b);
	buffer_append(&b, data, datalen);

	p = buffer_get_string(&b, &len);
	if ((session_id2 == NULL) ||
	    (len != session_id2_len) ||
	    (memcmp(p, session_id2, session_id2_len) != 0))
		fail++;
	xfree(p);

	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
		fail++;
	p = buffer_get_string(&b, NULL);
	if (strcmp(authctxt->user, p) != 0) {
		logit("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 sock, 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))
		fatal("%s: bad key, not previously allowed", __func__);

	key = key_from_blob(blob, bloblen);
	if (key == NULL)
		fatal("%s: bad public key blob", __func__);

	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", __func__);

	verified = key_verify(key, signature, signaturelen, data, datalen);
	debug3("%s: key %p signature %s",
	    __func__, key, (verified == 1) ? "verified" : "unverified");

	key_free(key);
	xfree(blob);
	xfree(signature);
	xfree(data);

	auth_method = key_blobtype == MM_USERKEY ? "publickey" : "hostbased";

	monitor_reset_key_state();

	buffer_clear(m);
	buffer_put_int(m, verified);
	mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);

	return (verified == 1);
}

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));
	fromlen = sizeof(from);
	if (packet_connection_is_on_socket()) {
		if (getpeername(packet_get_connection_in(),
		    (struct sockaddr *)&from, &fromlen) < 0) {
			debug("getpeername: %.100s", strerror(errno));
			cleanup_exit(255);
		}
	}
	/* 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.use_dns),
	    (struct sockaddr *)&from, fromlen);
}

static void
mm_session_close(Session *s)
{
	debug3("%s: session %d pid %ld", __func__, s->self, (long)s->pid);
	if (s->ttyfd != -1) {
		debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd);
		session_pty_cleanup2(s);
	}
	s->used = 0;
}

int
mm_answer_pty(int sock, Buffer *m)
{
	extern struct monitor *pmonitor;
	Session *s;
	int res, fd0;

	debug3("%s entering", __func__);

	buffer_clear(m);
	s = session_new();
	if (s == NULL)
		goto error;
	s->authctxt = authctxt;
	s->pw = authctxt->pw;
	s->pid = pmonitor->m_pid;
	res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
	if (res == 0)
		goto error;
	pty_setowner(authctxt->pw, s->tty);

	buffer_put_int(m, 1);
	buffer_put_cstring(m, s->tty);

	/* We need to trick ttyslot */
	if (dup2(s->ttyfd, 0) == -1)
		fatal("%s: dup2", __func__);

	mm_record_login(s, authctxt->pw);

	/* Now we can close the file descriptor again */
	close(0);

	/* send messages generated by record_login */
	buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg));
	buffer_clear(&loginmsg);

	mm_request_send(sock, MONITOR_ANS_PTY, m);

	if (mm_send_fd(sock, s->ptyfd) == -1 ||
	    mm_send_fd(sock, s->ttyfd) == -1)
		fatal("%s: send fds failed", __func__);

	/* make sure nothing uses fd 0 */
	if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0)
		fatal("%s: open(/dev/null): %s", __func__, strerror(errno));
	if (fd0 != 0)
		error("%s: fd0 %d != 0", __func__, 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", __func__, s->tty, s->ttyfd);

	return (0);

 error:
	if (s != NULL)
		mm_session_close(s);
	buffer_put_int(m, 0);
	mm_request_send(sock, MONITOR_ANS_PTY, m);
	return (0);
}

int
mm_answer_pty_cleanup(int sock, Buffer *m)
{
	Session *s;
	char *tty;

	debug3("%s entering", __func__);

	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 sock, Buffer *m)
{
	BIGNUM *p;
	int rsafail;

	/* Turn off permissions */
	monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 0);

	if ((p = BN_new()) == NULL)
		fatal("%s: BN_new", __func__);

	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(sock, 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 sock, Buffer *m)
{
	int i;

	debug3("%s entering", __func__);

	if (buffer_len(m) != 16)
		fatal("%s: bad ssh1 session id", __func__);
	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 sock, Buffer *m)
{
	BIGNUM *client_n;
	Key *key = NULL;
	u_char *blob = NULL;
	u_int blen = 0;
	int allowed = 0;

	debug3("%s entering", __func__);

	auth_method = "rsa";
	if (options.rsa_authentication && authctxt->valid) {
		if ((client_n = BN_new()) == NULL)
			fatal("%s: BN_new", __func__);
		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);
	buffer_put_int(m, forced_command != NULL);

	/* 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", __func__);
		buffer_put_string(m, blob, blen);

		/* Save temporarily for comparison in verify */
		key_blob = blob;
		key_bloblen = blen;
		key_blobtype = MM_RSAUSERKEY;
	}
	if (key != NULL)
		key_free(key);

	mm_append_debug(m);

	mm_request_send(sock, 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 sock, Buffer *m)
{
	Key *key = NULL;
	u_char *blob;
	u_int blen;

	debug3("%s entering", __func__);

	if (!authctxt->valid)
		fatal("%s: authctxt not valid", __func__);
	blob = buffer_get_string(m, &blen);
	if (!monitor_allowed_key(blob, blen))
		fatal("%s: bad key, not previously allowed", __func__);
	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
		fatal("%s: key type mismatch", __func__);
	if ((key = key_from_blob(blob, blen)) == NULL)
		fatal("%s: received bad key", __func__);

	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", __func__);
	mm_request_send(sock, MONITOR_ANS_RSACHALLENGE, m);

	monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 1);

	xfree(blob);
	key_free(key);
	return (0);
}

int
mm_answer_rsa_response(int sock, Buffer *m)
{
	Key *key = NULL;
	u_char *blob, *response;
	u_int blen, len;
	int success;

	debug3("%s entering", __func__);

	if (!authctxt->valid)
		fatal("%s: authctxt not valid", __func__);
	if (ssh1_challenge == NULL)
		fatal("%s: no ssh1_challenge", __func__);

	blob = buffer_get_string(m, &blen);
	if (!monitor_allowed_key(blob, blen))
		fatal("%s: bad key, not previously allowed", __func__);
	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
		fatal("%s: key type mismatch: %d", __func__, key_blobtype);
	if ((key = key_from_blob(blob, blen)) == NULL)
		fatal("%s: received bad key", __func__);
	response = buffer_get_string(m, &len);
	if (len != 16)
		fatal("%s: received bad response to challenge", __func__);
	success = auth_rsa_verify_response(key, ssh1_challenge, response);

	xfree(blob);
	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(sock, MONITOR_ANS_RSARESPONSE, m);

	return (success);
}

int
mm_answer_term(int sock, Buffer *req)
{
	extern struct monitor *pmonitor;
	int res, status;

	debug3("%s: tearing down sessions", __func__);

	/* The child is terminating */
	session_destroy_all(&mm_session_close);

	while (waitpid(pmonitor->m_pid, &status, 0) == -1)
		if (errno != EINTR)
			exit(1);

	res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;

	/* Terminate process */
	exit(res);
}

void
monitor_apply_keystate(struct monitor *pmonitor)
{
	if (compat20) {
		set_newkeys(MODE_IN);
		set_newkeys(MODE_OUT);
	} else {
		packet_set_protocol_flags(child_state.ssh1protoflags);
		packet_set_encryption_key(child_state.ssh1key,
		    child_state.ssh1keylen, child_state.ssh1cipher);
		xfree(child_state.ssh1key);
	}

	/* for rc4 and other stateful ciphers */
	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 */
	if (options.compression)
		mm_init_compression(pmonitor->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 = xcalloc(1, sizeof(*kex));
	kex->session_id = buffer_get_string(m, &kex->session_id_len);
	if ((session_id2 == NULL) ||
	    (kex->session_id_len != session_id2_len) ||
	    (memcmp(kex->session_id, session_id2, session_id2_len) != 0))
		fatal("mm_get_get: internal error: bad session id");
	kex->we_need = buffer_get_int(m);
	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
	kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
	kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
	kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
	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 *pmonitor)
{
	Buffer m;
	u_char *blob, *p;
	u_int bloblen, plen;
	u_int32_t seqnr, packets;
	u_int64_t blocks;

	debug3("%s: Waiting for new keys", __func__);

	buffer_init(&m);
	mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, &m);
	if (!compat20) {
		child_state.ssh1protoflags = buffer_get_int(&m);
		child_state.ssh1cipher = buffer_get_int(&m);
		child_state.ssh1key = buffer_get_string(&m,
		    &child_state.ssh1keylen);
		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 */
		*pmonitor->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", __func__);
	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 */
	seqnr = buffer_get_int(&m);
	blocks = buffer_get_int64(&m);
	packets = buffer_get_int(&m);
	packet_set_state(MODE_OUT, seqnr, blocks, packets);
	seqnr = buffer_get_int(&m);
	blocks = buffer_get_int64(&m);
	packets = buffer_get_int(&m);
	packet_set_state(MODE_IN, seqnr, blocks, packets);

 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", __func__);
	/* Get compression state */
	p = buffer_get_string(&m, &plen);
	if (plen != sizeof(child_state.outgoing))
		fatal("%s: bad request size", __func__);
	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", __func__);
	memcpy(&child_state.incoming, p, sizeof(child_state.incoming));
	xfree(p);

	/* Network I/O buffers */
	debug3("%s: Getting Network I/O buffers", __func__);
	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)
{
	size_t len = (size_t) size * ncount;
	void *address;

	if (len == 0 || ncount > SIZE_T_MAX / size)
		fatal("%s: mm_zalloc(%u, %u)", __func__, ncount, size);

	address = mm_malloc(mm, len);

	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", __func__);
	FD_CLOSEONEXEC(pair[0]);
	FD_CLOSEONEXEC(pair[1]);
}

#define MM_MEMSIZE	65536

struct monitor *
monitor_init(void)
{
	struct monitor *mon;
	int pair[2];

	mon = xcalloc(1, sizeof(*mon));

	monitor_socketpair(pair);

	mon->m_recvfd = pair[0];
	mon->m_sendfd = pair[1];

	/* Used to share zlib space across processes */
	if (options.compression) {
		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];
}

#ifdef GSSAPI
int
mm_answer_gss_setup_ctx(int sock, Buffer *m)
{
	gss_OID_desc goid;
	OM_uint32 major;
	u_int len;

	goid.elements = buffer_get_string(m, &len);
	goid.length = len;

	major = ssh_gssapi_server_ctx(&gsscontext, &goid);

	xfree(goid.elements);

	buffer_clear(m);
	buffer_put_int(m, major);

	mm_request_send(sock, MONITOR_ANS_GSSSETUP, m);

	/* Now we have a context, enable the step */
	monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1);

	return (0);
}

int
mm_answer_gss_accept_ctx(int sock, Buffer *m)
{
	gss_buffer_desc in;
	gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
	OM_uint32 major, minor;
	OM_uint32 flags = 0; /* GSI needs this */
	u_int len;

	in.value = buffer_get_string(m, &len);
	in.length = len;
	major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
	xfree(in.value);

	buffer_clear(m);
	buffer_put_int(m, major);
	buffer_put_string(m, out.value, out.length);
	buffer_put_int(m, flags);
	mm_request_send(sock, MONITOR_ANS_GSSSTEP, m);

	gss_release_buffer(&minor, &out);

	if (major == GSS_S_COMPLETE) {
		monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
		monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
		monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
	}
	return (0);
}

int
mm_answer_gss_checkmic(int sock, Buffer *m)
{
	gss_buffer_desc gssbuf, mic;
	OM_uint32 ret;
	u_int len;

	gssbuf.value = buffer_get_string(m, &len);
	gssbuf.length = len;
	mic.value = buffer_get_string(m, &len);
	mic.length = len;

	ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);

	xfree(gssbuf.value);
	xfree(mic.value);

	buffer_clear(m);
	buffer_put_int(m, ret);

	mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m);

	if (!GSS_ERROR(ret))
		monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);

	return (0);
}

int
mm_answer_gss_userok(int sock, Buffer *m)
{
	int authenticated;

	authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);

	buffer_clear(m);
	buffer_put_int(m, authenticated);

	debug3("%s: sending result %d", __func__, authenticated);
	mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);

	auth_method = "gssapi-with-mic";

	/* Monitor loop will terminate if authenticated */
	return (authenticated);
}
#endif /* GSSAPI */