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add "ext-info-in-auth@openssh.com" extension

This adds another transport protocol extension to allow a sshd to send
SSH2_MSG_EXT_INFO during user authentication, after the server has
learned the username that is being logged in to.

This lets sshd to update the acceptable signature algoritms for public
key authentication, and allows these to be varied via sshd_config(5)
"Match" directives, which are evaluated after the server learns the
username being authenticated.

Full details in the PROTOCOL file

/* $OpenBSD: monitor_wrap.c,v 1.129 2023/12/18 14:45:49 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/uio.h>
#include <sys/queue.h>

#include <errno.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>

#ifdef WITH_OPENSSL
#include <openssl/bn.h>
#include <openssl/dh.h>
#endif

#include "xmalloc.h"
#include "ssh.h"
#ifdef WITH_OPENSSL
#include "dh.h"
#endif
#include "sshbuf.h"
#include "sshkey.h"
#include "cipher.h"
#include "kex.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "packet.h"
#include "mac.h"
#include "log.h"
#include "monitor.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "atomicio.h"
#include "monitor_fdpass.h"
#include "misc.h"

#include "channels.h"
#include "session.h"
#include "servconf.h"

#include "ssherr.h"

/* Imports */
extern struct monitor *pmonitor;
extern struct sshbuf *loginmsg;
extern ServerOptions options;

void
mm_log_handler(LogLevel level, int forced, const char *msg, void *ctx)
{
	struct sshbuf *log_msg;
	struct monitor *mon = (struct monitor *)ctx;
	int r;
	size_t len;

	if (mon->m_log_sendfd == -1)
		fatal_f("no log channel");

	if ((log_msg = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");

	if ((r = sshbuf_put_u32(log_msg, 0)) != 0 || /* length; filled below */
	    (r = sshbuf_put_u32(log_msg, level)) != 0 ||
	    (r = sshbuf_put_u32(log_msg, forced)) != 0 ||
	    (r = sshbuf_put_cstring(log_msg, msg)) != 0)
		fatal_fr(r, "assemble");
	if ((len = sshbuf_len(log_msg)) < 4 || len > 0xffffffff)
		fatal_f("bad length %zu", len);
	POKE_U32(sshbuf_mutable_ptr(log_msg), len - 4);
	if (atomicio(vwrite, mon->m_log_sendfd,
	    sshbuf_mutable_ptr(log_msg), len) != len)
		fatal_f("write: %s", strerror(errno));
	sshbuf_free(log_msg);
}

int
mm_is_monitor(void)
{
	/*
	 * m_pid is only set in the privileged part, and
	 * points to the unprivileged child.
	 */
	return (pmonitor && pmonitor->m_pid > 0);
}

void
mm_request_send(int sock, enum monitor_reqtype type, struct sshbuf *m)
{
	size_t mlen = sshbuf_len(m);
	u_char buf[5];

	debug3_f("entering, type %d", type);

	if (mlen >= 0xffffffff)
		fatal_f("bad length %zu", mlen);
	POKE_U32(buf, mlen + 1);
	buf[4] = (u_char) type;		/* 1st byte of payload is mesg-type */
	if (atomicio(vwrite, sock, buf, sizeof(buf)) != sizeof(buf))
		fatal_f("write: %s", strerror(errno));
	if (atomicio(vwrite, sock, sshbuf_mutable_ptr(m), mlen) != mlen)
		fatal_f("write: %s", strerror(errno));
}

void
mm_request_receive(int sock, struct sshbuf *m)
{
	u_char buf[4], *p = NULL;
	u_int msg_len;
	int r;

	debug3_f("entering");

	if (atomicio(read, sock, buf, sizeof(buf)) != sizeof(buf)) {
		if (errno == EPIPE)
			cleanup_exit(255);
		fatal_f("read: %s", strerror(errno));
	}
	msg_len = PEEK_U32(buf);
	if (msg_len > 256 * 1024)
		fatal_f("read: bad msg_len %d", msg_len);
	sshbuf_reset(m);
	if ((r = sshbuf_reserve(m, msg_len, &p)) != 0)
		fatal_fr(r, "reserve");
	if (atomicio(read, sock, p, msg_len) != msg_len)
		fatal_f("read: %s", strerror(errno));
}

void
mm_request_receive_expect(int sock, enum monitor_reqtype type, struct sshbuf *m)
{
	u_char rtype;
	int r;

	debug3_f("entering, type %d", type);

	mm_request_receive(sock, m);
	if ((r = sshbuf_get_u8(m, &rtype)) != 0)
		fatal_fr(r, "parse");
	if (rtype != type)
		fatal_f("read: rtype %d != type %d", rtype, type);
}

#ifdef WITH_OPENSSL
DH *
mm_choose_dh(int min, int nbits, int max)
{
	BIGNUM *p, *g;
	int r;
	u_char success = 0;
	struct sshbuf *m;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_u32(m, min)) != 0 ||
	    (r = sshbuf_put_u32(m, nbits)) != 0 ||
	    (r = sshbuf_put_u32(m, max)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_MODULI, m);

	debug3_f("waiting for MONITOR_ANS_MODULI");
	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_MODULI, m);

	if ((r = sshbuf_get_u8(m, &success)) != 0)
		fatal_fr(r, "parse success");
	if (success == 0)
		fatal_f("MONITOR_ANS_MODULI failed");

	if ((r = sshbuf_get_bignum2(m, &p)) != 0 ||
	    (r = sshbuf_get_bignum2(m, &g)) != 0)
		fatal_fr(r, "parse group");

	debug3_f("remaining %zu", sshbuf_len(m));
	sshbuf_free(m);

	return (dh_new_group(g, p));
}
#endif

int
mm_sshkey_sign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
    const u_char *data, size_t datalen, const char *hostkey_alg,
    const char *sk_provider, const char *sk_pin, u_int compat)
{
	struct kex *kex = *pmonitor->m_pkex;
	struct sshbuf *m;
	u_int ndx = kex->host_key_index(key, 0, ssh);
	int r;

	debug3_f("entering");
	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_u32(m, ndx)) != 0 ||
	    (r = sshbuf_put_string(m, data, datalen)) != 0 ||
	    (r = sshbuf_put_cstring(m, hostkey_alg)) != 0 ||
	    (r = sshbuf_put_u32(m, compat)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_SIGN, m);

	debug3_f("waiting for MONITOR_ANS_SIGN");
	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_SIGN, m);
	if ((r = sshbuf_get_string(m, sigp, lenp)) != 0)
		fatal_fr(r, "parse");
	sshbuf_free(m);

	return (0);
}

#define GETPW(b, id) \
	do { \
		if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) \
			fatal_fr(r, "parse pw %s", #id); \
		if (len != sizeof(pw->id)) \
			fatal_fr(r, "bad length for %s", #id); \
		memcpy(&pw->id, p, len); \
	} while (0)

struct passwd *
mm_getpwnamallow(struct ssh *ssh, const char *username)
{
	struct sshbuf *m;
	struct passwd *pw;
	size_t len;
	u_int i;
	ServerOptions *newopts;
	int r;
	u_char ok;
	const u_char *p;

	debug3_f("entering");

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_cstring(m, username)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PWNAM, m);

	debug3_f("waiting for MONITOR_ANS_PWNAM");
	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PWNAM, m);

	if ((r = sshbuf_get_u8(m, &ok)) != 0)
		fatal_fr(r, "parse success");
	if (ok == 0) {
		pw = NULL;
		goto out;
	}

	pw = xcalloc(sizeof(*pw), 1);
	GETPW(m, pw_uid);
	GETPW(m, pw_gid);
	GETPW(m, pw_change);
	GETPW(m, pw_expire);
	if ((r = sshbuf_get_cstring(m, &pw->pw_name, NULL)) != 0 ||
	    (r = sshbuf_get_cstring(m, &pw->pw_passwd, NULL)) != 0 ||
	    (r = sshbuf_get_cstring(m, &pw->pw_gecos, NULL)) != 0 ||
	    (r = sshbuf_get_cstring(m, &pw->pw_class, NULL)) != 0 ||
	    (r = sshbuf_get_cstring(m, &pw->pw_dir, NULL)) != 0 ||
	    (r = sshbuf_get_cstring(m, &pw->pw_shell, NULL)) != 0)
		fatal_fr(r, "parse pw");

out:
	/* copy options block as a Match directive may have changed some */
	if ((r = sshbuf_get_string_direct(m, &p, &len)) != 0)
		fatal_fr(r, "parse opts");
	if (len != sizeof(*newopts))
		fatal_f("option block size mismatch");
	newopts = xcalloc(sizeof(*newopts), 1);
	memcpy(newopts, p, sizeof(*newopts));

#define M_CP_STROPT(x) do { \
		if (newopts->x != NULL && \
		    (r = sshbuf_get_cstring(m, &newopts->x, NULL)) != 0) \
			fatal_fr(r, "parse %s", #x); \
	} while (0)
#define M_CP_STRARRAYOPT(x, nx) do { \
		newopts->x = newopts->nx == 0 ? \
		    NULL : xcalloc(newopts->nx, sizeof(*newopts->x)); \
		for (i = 0; i < newopts->nx; i++) { \
			if ((r = sshbuf_get_cstring(m, \
			    &newopts->x[i], NULL)) != 0) \
				fatal_fr(r, "parse %s", #x); \
		} \
	} while (0)
	/* See comment in servconf.h */
	COPY_MATCH_STRING_OPTS();
#undef M_CP_STROPT
#undef M_CP_STRARRAYOPT

	copy_set_server_options(&options, newopts, 1);
	log_change_level(options.log_level);
	log_verbose_reset();
	for (i = 0; i < options.num_log_verbose; i++)
		log_verbose_add(options.log_verbose[i]);
	process_permitopen(ssh, &options);
	process_channel_timeouts(ssh, &options);
	kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos);
	free(newopts);
	sshbuf_free(m);

	return (pw);
}

char *
mm_auth2_read_banner(void)
{
	struct sshbuf *m;
	char *banner;
	int r;

	debug3_f("entering");

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTH2_READ_BANNER, m);
	sshbuf_reset(m);

	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_AUTH2_READ_BANNER, m);
	if ((r = sshbuf_get_cstring(m, &banner, NULL)) != 0)
		fatal_fr(r, "parse");
	sshbuf_free(m);

	/* treat empty banner as missing banner */
	if (strlen(banner) == 0) {
		free(banner);
		banner = NULL;
	}
	return (banner);
}

/* Inform the privileged process about service and style */

void
mm_inform_authserv(char *service, char *style)
{
	struct sshbuf *m;
	int r;

	debug3_f("entering");

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_cstring(m, service)) != 0 ||
	    (r = sshbuf_put_cstring(m, style ? style : "")) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHSERV, m);

	sshbuf_free(m);
}

/* Do the password authentication */
int
mm_auth_password(struct ssh *ssh, char *password)
{
	struct sshbuf *m;
	int r, authenticated = 0;

	debug3_f("entering");

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_cstring(m, password)) != 0)
		fatal_fr(r, "assemble");
	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHPASSWORD, m);

	debug3_f("waiting for MONITOR_ANS_AUTHPASSWORD");
	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_AUTHPASSWORD, m);

	if ((r = sshbuf_get_u32(m, &authenticated)) != 0)
		fatal_fr(r, "parse");

	sshbuf_free(m);

	debug3_f("user %sauthenticated", authenticated ? "" : "not ");
	return (authenticated);
}

int
mm_user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
    int pubkey_auth_attempt, struct sshauthopt **authoptp)
{
	return (mm_key_allowed(MM_USERKEY, NULL, NULL, key,
	    pubkey_auth_attempt, authoptp));
}

int
mm_hostbased_key_allowed(struct ssh *ssh, struct passwd *pw,
    const char *user, const char *host, struct sshkey *key)
{
	return (mm_key_allowed(MM_HOSTKEY, user, host, key, 0, NULL));
}

int
mm_key_allowed(enum mm_keytype type, const char *user, const char *host,
    struct sshkey *key, int pubkey_auth_attempt, struct sshauthopt **authoptp)
{
	struct sshbuf *m;
	int r, allowed = 0;
	struct sshauthopt *opts = NULL;

	debug3_f("entering");

	if (authoptp != NULL)
		*authoptp = NULL;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_u32(m, type)) != 0 ||
	    (r = sshbuf_put_cstring(m, user ? user : "")) != 0 ||
	    (r = sshbuf_put_cstring(m, host ? host : "")) != 0 ||
	    (r = sshkey_puts(key, m)) != 0 ||
	    (r = sshbuf_put_u32(m, pubkey_auth_attempt)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYALLOWED, m);

	debug3_f("waiting for MONITOR_ANS_KEYALLOWED");
	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_KEYALLOWED, m);

	if ((r = sshbuf_get_u32(m, &allowed)) != 0)
		fatal_fr(r, "parse");
	if (allowed && type == MM_USERKEY &&
	    (r = sshauthopt_deserialise(m, &opts)) != 0)
		fatal_fr(r, "sshauthopt_deserialise");
	sshbuf_free(m);

	if (authoptp != NULL) {
		*authoptp = opts;
		opts = NULL;
	}
	sshauthopt_free(opts);

	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_sshkey_verify(const struct sshkey *key, const u_char *sig, size_t siglen,
    const u_char *data, size_t datalen, const char *sigalg, u_int compat,
    struct sshkey_sig_details **sig_detailsp)
{
	struct sshbuf *m;
	u_int encoded_ret = 0;
	int r;
	u_char sig_details_present, flags;
	u_int counter;

	debug3_f("entering");

	if (sig_detailsp != NULL)
		*sig_detailsp = NULL;
	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshkey_puts(key, m)) != 0 ||
	    (r = sshbuf_put_string(m, sig, siglen)) != 0 ||
	    (r = sshbuf_put_string(m, data, datalen)) != 0 ||
	    (r = sshbuf_put_cstring(m, sigalg == NULL ? "" : sigalg)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYVERIFY, m);

	debug3_f("waiting for MONITOR_ANS_KEYVERIFY");
	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_KEYVERIFY, m);

	if ((r = sshbuf_get_u32(m, &encoded_ret)) != 0 ||
	    (r = sshbuf_get_u8(m, &sig_details_present)) != 0)
		fatal_fr(r, "parse");
	if (sig_details_present && encoded_ret == 0) {
		if ((r = sshbuf_get_u32(m, &counter)) != 0 ||
		    (r = sshbuf_get_u8(m, &flags)) != 0)
			fatal_fr(r, "parse sig_details");
		if (sig_detailsp != NULL) {
			*sig_detailsp = xcalloc(1, sizeof(**sig_detailsp));
			(*sig_detailsp)->sk_counter = counter;
			(*sig_detailsp)->sk_flags = flags;
		}
	}

	sshbuf_free(m);

	if (encoded_ret != 0)
		return SSH_ERR_SIGNATURE_INVALID;
	return 0;
}

void
mm_send_keystate(struct ssh *ssh, struct monitor *monitor)
{
	struct sshbuf *m;
	int r;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = ssh_packet_get_state(ssh, m)) != 0)
		fatal_fr(r, "ssh_packet_get_state");
	mm_request_send(monitor->m_recvfd, MONITOR_REQ_KEYEXPORT, m);
	debug3_f("Finished sending state");
	sshbuf_free(m);
}

int
mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
{
	struct sshbuf *m;
	char *p, *msg;
	int success = 0, tmp1 = -1, tmp2 = -1, r;

	/* Kludge: ensure there are fds free to receive the pty/tty */
	if ((tmp1 = dup(pmonitor->m_recvfd)) == -1 ||
	    (tmp2 = dup(pmonitor->m_recvfd)) == -1) {
		error_f("cannot allocate fds for pty");
		if (tmp1 >= 0)
			close(tmp1);
		return 0;
	}
	close(tmp1);
	close(tmp2);

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTY, m);

	debug3_f("waiting for MONITOR_ANS_PTY");
	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PTY, m);

	if ((r = sshbuf_get_u32(m, &success)) != 0)
		fatal_fr(r, "parse success");
	if (success == 0) {
		debug3_f("pty alloc failed");
		sshbuf_free(m);
		return (0);
	}
	if ((r = sshbuf_get_cstring(m, &p, NULL)) != 0 ||
	    (r = sshbuf_get_cstring(m, &msg, NULL)) != 0)
		fatal_fr(r, "parse");
	sshbuf_free(m);

	strlcpy(namebuf, p, namebuflen); /* Possible truncation */
	free(p);

	if ((r = sshbuf_put(loginmsg, msg, strlen(msg))) != 0)
		fatal_fr(r, "put loginmsg");
	free(msg);

	if ((*ptyfd = mm_receive_fd(pmonitor->m_recvfd)) == -1 ||
	    (*ttyfd = mm_receive_fd(pmonitor->m_recvfd)) == -1)
		fatal_f("receive fds failed");

	/* Success */
	return (1);
}

void
mm_session_pty_cleanup2(Session *s)
{
	struct sshbuf *m;
	int r;

	if (s->ttyfd == -1)
		return;
	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_cstring(m, s->tty)) != 0)
		fatal_fr(r, "assmble");
	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTYCLEANUP, m);
	sshbuf_free(m);

	/* closed dup'ed master */
	if (s->ptymaster != -1 && close(s->ptymaster) == -1)
		error("close(s->ptymaster/%d): %s",
		    s->ptymaster, strerror(errno));

	/* unlink pty from session */
	s->ttyfd = -1;
}

/* Request process termination */

void
mm_terminate(void)
{
	struct sshbuf *m;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_TERM, m);
	sshbuf_free(m);
}

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 = xcalloc(*numprompts, sizeof(char *));
	*echo_on = xcalloc(*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)
{
	struct sshbuf *m;
	u_int success;
	char *challenge;
	int r;

	debug3_f("entering");

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHQUERY, m);

	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_BSDAUTHQUERY, m);
	if ((r = sshbuf_get_u32(m, &success)) != 0)
		fatal_fr(r, "parse success");
	if (success == 0) {
		debug3_f("no challenge");
		sshbuf_free(m);
		return (-1);
	}

	/* Get the challenge, and format the response */
	if ((r = sshbuf_get_cstring(m, &challenge, NULL)) != 0)
		fatal_fr(r, "parse challenge");
	sshbuf_free(m);

	mm_chall_setup(name, infotxt, numprompts, prompts, echo_on);
	(*prompts)[0] = challenge;

	debug3_f("received challenge: %s", challenge);

	return (0);
}

int
mm_bsdauth_respond(void *ctx, u_int numresponses, char **responses)
{
	struct sshbuf *m;
	int r, authok;

	debug3_f("entering");
	if (numresponses != 1)
		return (-1);

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_cstring(m, responses[0])) != 0)
		fatal_fr(r, "assemble");
	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHRESPOND, m);

	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_BSDAUTHRESPOND, m);

	if ((r = sshbuf_get_u32(m, &authok)) != 0)
		fatal_fr(r, "parse");
	sshbuf_free(m);

	return ((authok == 0) ? -1 : 0);
}

#ifdef GSSAPI
OM_uint32
mm_ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID goid)
{
	struct sshbuf *m;
	OM_uint32 major;
	int r;

	/* Client doesn't get to see the context */
	*ctx = NULL;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_string(m, goid->elements, goid->length)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSETUP, m);
	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSETUP, m);

	if ((r = sshbuf_get_u32(m, &major)) != 0)
		fatal_fr(r, "parse");

	sshbuf_free(m);
	return (major);
}

OM_uint32
mm_ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *in,
    gss_buffer_desc *out, OM_uint32 *flagsp)
{
	struct sshbuf *m;
	OM_uint32 major;
	u_int flags;
	int r;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_string(m, in->value, in->length)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSTEP, m);
	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSTEP, m);

	if ((r = sshbuf_get_u32(m, &major)) != 0 ||
	    (r = ssh_gssapi_get_buffer_desc(m, out)) != 0)
		fatal_fr(r, "parse");
	if (flagsp != NULL) {
		if ((r = sshbuf_get_u32(m, &flags)) != 0)
			fatal_fr(r, "parse flags");
		*flagsp = flags;
	}

	sshbuf_free(m);

	return (major);
}

OM_uint32
mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
{
	struct sshbuf *m;
	OM_uint32 major;
	int r;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");
	if ((r = sshbuf_put_string(m, gssbuf->value, gssbuf->length)) != 0 ||
	    (r = sshbuf_put_string(m, gssmic->value, gssmic->length)) != 0)
		fatal_fr(r, "assemble");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSCHECKMIC, m);
	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_GSSCHECKMIC, m);

	if ((r = sshbuf_get_u32(m, &major)) != 0)
		fatal_fr(r, "parse");
	sshbuf_free(m);
	return(major);
}

int
mm_ssh_gssapi_userok(char *user)
{
	struct sshbuf *m;
	int r, authenticated = 0;

	if ((m = sshbuf_new()) == NULL)
		fatal_f("sshbuf_new failed");

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, m);
	mm_request_receive_expect(pmonitor->m_recvfd,
	    MONITOR_ANS_GSSUSEROK, m);

	if ((r = sshbuf_get_u32(m, &authenticated)) != 0)
		fatal_fr(r, "parse");

	sshbuf_free(m);
	debug3_f("user %sauthenticated", authenticated ? "" : "not ");
	return (authenticated);
}
#endif /* GSSAPI */