Adding upstream version 1:7.9p1.upstream/1%7.9p1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1875 insertions, 0 deletions

diff --git a/monitor.c b/monitor.c
new file mode 100644
index 0000000..531b299
--- /dev/null
+++ b/monitor.c
@@ -0,0 +1,1875 @@
+/* $OpenBSD: monitor.c,v 1.186 2018/07/20 03:46:34 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 "includes.h"
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#ifdef HAVE_PATHS_H
+#include <paths.h>
+#endif
+#include <pwd.h>
+#include <signal.h>
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <unistd.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#else
+# ifdef HAVE_SYS_POLL_H
+#  include <sys/poll.h>
+# endif
+#endif
+
+#ifdef WITH_OPENSSL
+#include <openssl/dh.h>
+#endif
+
+#include "openbsd-compat/sys-tree.h"
+#include "openbsd-compat/sys-queue.h"
+#include "openbsd-compat/openssl-compat.h"
+
+#include "atomicio.h"
+#include "xmalloc.h"
+#include "ssh.h"
+#include "sshkey.h"
+#include "sshbuf.h"
+#include "hostfile.h"
+#include "auth.h"
+#include "cipher.h"
+#include "kex.h"
+#include "dh.h"
+#include "auth-pam.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 "misc.h"
+#include "servconf.h"
+#include "monitor.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "monitor_wrap.h"
+#include "monitor_fdpass.h"
+#include "compat.h"
+#include "ssh2.h"
+#include "authfd.h"
+#include "match.h"
+#include "ssherr.h"
+
+#ifdef GSSAPI
+static Gssctxt *gsscontext = NULL;
+#endif
+
+/* Imports */
+extern ServerOptions options;
+extern u_int utmp_len;
+extern u_char session_id[];
+extern struct sshbuf *loginmsg;
+extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */
+
+/* State exported from the child */
+static struct sshbuf *child_state;
+
+/* Functions on the monitor that answer unprivileged requests */
+
+int mm_answer_moduli(int, struct sshbuf *);
+int mm_answer_sign(int, struct sshbuf *);
+int mm_answer_pwnamallow(int, struct sshbuf *);
+int mm_answer_auth2_read_banner(int, struct sshbuf *);
+int mm_answer_authserv(int, struct sshbuf *);
+int mm_answer_authpassword(int, struct sshbuf *);
+int mm_answer_bsdauthquery(int, struct sshbuf *);
+int mm_answer_bsdauthrespond(int, struct sshbuf *);
+int mm_answer_keyallowed(int, struct sshbuf *);
+int mm_answer_keyverify(int, struct sshbuf *);
+int mm_answer_pty(int, struct sshbuf *);
+int mm_answer_pty_cleanup(int, struct sshbuf *);
+int mm_answer_term(int, struct sshbuf *);
+int mm_answer_rsa_keyallowed(int, struct sshbuf *);
+int mm_answer_rsa_challenge(int, struct sshbuf *);
+int mm_answer_rsa_response(int, struct sshbuf *);
+int mm_answer_sesskey(int, struct sshbuf *);
+int mm_answer_sessid(int, struct sshbuf *);
+
+#ifdef USE_PAM
+int mm_answer_pam_start(int, struct sshbuf *);
+int mm_answer_pam_account(int, struct sshbuf *);
+int mm_answer_pam_init_ctx(int, struct sshbuf *);
+int mm_answer_pam_query(int, struct sshbuf *);
+int mm_answer_pam_respond(int, struct sshbuf *);
+int mm_answer_pam_free_ctx(int, struct sshbuf *);
+#endif
+
+#ifdef GSSAPI
+int mm_answer_gss_setup_ctx(int, struct sshbuf *);
+int mm_answer_gss_accept_ctx(int, struct sshbuf *);
+int mm_answer_gss_userok(int, struct sshbuf *);
+int mm_answer_gss_checkmic(int, struct sshbuf *);
+#endif
+
+#ifdef SSH_AUDIT_EVENTS
+int mm_answer_audit_event(int, struct sshbuf *);
+int mm_answer_audit_command(int, struct sshbuf *);
+#endif
+
+static int monitor_read_log(struct monitor *);
+
+static Authctxt *authctxt;
+
+/* local state for key verify */
+static u_char *key_blob = NULL;
+static size_t key_bloblen = 0;
+static int key_blobtype = MM_NOKEY;
+static struct sshauthopt *key_opts = NULL;
+static char *hostbased_cuser = NULL;
+static char *hostbased_chost = NULL;
+static char *auth_method = "unknown";
+static char *auth_submethod = NULL;
+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, struct sshbuf *);
+};
+
+#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[] = {
+#ifdef WITH_OPENSSL
+    {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
+#endif
+    {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 USE_PAM
+    {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start},
+    {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account},
+    {MONITOR_REQ_PAM_INIT_CTX, MON_ONCE, mm_answer_pam_init_ctx},
+    {MONITOR_REQ_PAM_QUERY, 0, mm_answer_pam_query},
+    {MONITOR_REQ_PAM_RESPOND, MON_ONCE, mm_answer_pam_respond},
+    {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx},
+#endif
+#ifdef SSH_AUDIT_EVENTS
+    {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
+#endif
+#ifdef BSD_AUTH
+    {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
+    {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond},
+#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, 0, mm_answer_gss_accept_ctx},
+    {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok},
+    {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic},
+#endif
+    {0, 0, NULL}
+};
+
+struct mon_table mon_dispatch_postauth20[] = {
+#ifdef WITH_OPENSSL
+    {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
+#endif
+    {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},
+#ifdef SSH_AUDIT_EVENTS
+    {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
+    {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command},
+#endif
+    {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 ssh *ssh = active_state;	/* XXX */
+	struct mon_table *ent;
+	int authenticated = 0, partial = 0;
+
+	debug3("preauth child monitor started");
+
+	if (pmonitor->m_recvfd >= 0)
+		close(pmonitor->m_recvfd);
+	if (pmonitor->m_log_sendfd >= 0)
+		close(pmonitor->m_log_sendfd);
+	pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
+
+	authctxt = _authctxt;
+	memset(authctxt, 0, sizeof(*authctxt));
+	ssh->authctxt = authctxt;
+
+	authctxt->loginmsg = loginmsg;
+
+	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);
+
+	/* The first few requests do not require asynchronous access */
+	while (!authenticated) {
+		partial = 0;
+		auth_method = "unknown";
+		auth_submethod = NULL;
+		auth2_authctxt_reset_info(authctxt);
+
+		authenticated = (monitor_read(pmonitor, mon_dispatch, &ent) == 1);
+
+		/* Special handling for multiple required authentications */
+		if (options.num_auth_methods != 0) {
+			if (authenticated &&
+			    !auth2_update_methods_lists(authctxt,
+			    auth_method, auth_submethod)) {
+				debug3("%s: method %s: partial", __func__,
+				    auth_method);
+				authenticated = 0;
+				partial = 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(ssh, auth_method))
+				authenticated = 0;
+#ifdef USE_PAM
+			/* PAM needs to perform account checks after auth */
+			if (options.use_pam && authenticated) {
+				struct sshbuf *m;
+
+				if ((m = sshbuf_new()) == NULL)
+					fatal("%s: sshbuf_new failed",
+					    __func__);
+				mm_request_receive_expect(pmonitor->m_sendfd,
+				    MONITOR_REQ_PAM_ACCOUNT, m);
+				authenticated = mm_answer_pam_account(
+				    pmonitor->m_sendfd, m);
+				sshbuf_free(m);
+			}
+#endif
+		}
+		if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
+			auth_log(authctxt, authenticated, partial,
+			    auth_method, auth_submethod);
+			if (!partial && !authenticated)
+				authctxt->failures++;
+			if (authenticated || partial) {
+				auth2_update_session_info(authctxt,
+				    auth_method, auth_submethod);
+			}
+		}
+	}
+
+	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);
+	ssh->authctxt = NULL;
+	ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
+
+	mm_get_keystate(pmonitor);
+
+	/* Drain any buffered messages from the child */
+	while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
+		;
+
+	if (pmonitor->m_recvfd >= 0)
+		close(pmonitor->m_recvfd);
+	if (pmonitor->m_log_sendfd >= 0)
+		close(pmonitor->m_log_sendfd);
+	pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
+}
+
+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)
+{
+	close(pmonitor->m_recvfd);
+	pmonitor->m_recvfd = -1;
+
+	monitor_set_child_handler(pmonitor->m_pid);
+	signal(SIGHUP, &monitor_child_handler);
+	signal(SIGTERM, &monitor_child_handler);
+	signal(SIGINT, &monitor_child_handler);
+#ifdef SIGXFSZ
+	signal(SIGXFSZ, SIG_IGN);
+#endif
+
+	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);
+
+	if (auth_opts->permit_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);
+}
+
+static int
+monitor_read_log(struct monitor *pmonitor)
+{
+	struct sshbuf *logmsg;
+	u_int len, level;
+	char *msg;
+	u_char *p;
+	int r;
+
+	if ((logmsg = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new", __func__);
+
+	/* Read length */
+	if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0)
+		fatal("%s: reserve: %s", __func__, ssh_err(r));
+	if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) {
+		if (errno == EPIPE) {
+			sshbuf_free(logmsg);
+			debug("%s: child log fd closed", __func__);
+			close(pmonitor->m_log_recvfd);
+			pmonitor->m_log_recvfd = -1;
+			return -1;
+		}
+		fatal("%s: log fd read: %s", __func__, strerror(errno));
+	}
+	if ((r = sshbuf_get_u32(logmsg, &len)) != 0)
+		fatal("%s: get len: %s", __func__, ssh_err(r));
+	if (len <= 4 || len > 8192)
+		fatal("%s: invalid log message length %u", __func__, len);
+
+	/* Read severity, message */
+	sshbuf_reset(logmsg);
+	if ((r = sshbuf_reserve(logmsg, len, &p)) != 0)
+		fatal("%s: reserve: %s", __func__, ssh_err(r));
+	if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len)
+		fatal("%s: log fd read: %s", __func__, strerror(errno));
+	if ((r = sshbuf_get_u32(logmsg, &level)) != 0 ||
+	    (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0)
+		fatal("%s: decode: %s", __func__, ssh_err(r));
+
+	/* Log it */
+	if (log_level_name(level) == NULL)
+		fatal("%s: invalid log level %u (corrupted message?)",
+		    __func__, level);
+	do_log2(level, "%s [preauth]", msg);
+
+	sshbuf_free(logmsg);
+	free(msg);
+
+	return 0;
+}
+
+int
+monitor_read(struct monitor *pmonitor, struct mon_table *ent,
+    struct mon_table **pent)
+{
+	struct sshbuf *m;
+	int r, ret;
+	u_char type;
+	struct pollfd pfd[2];
+
+	for (;;) {
+		memset(&pfd, 0, sizeof(pfd));
+		pfd[0].fd = pmonitor->m_sendfd;
+		pfd[0].events = POLLIN;
+		pfd[1].fd = pmonitor->m_log_recvfd;
+		pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN;
+		if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) {
+			if (errno == EINTR || errno == EAGAIN)
+				continue;
+			fatal("%s: poll: %s", __func__, strerror(errno));
+		}
+		if (pfd[1].revents) {
+			/*
+			 * Drain all log messages before processing next
+			 * monitor request.
+			 */
+			monitor_read_log(pmonitor);
+			continue;
+		}
+		if (pfd[0].revents)
+			break;  /* Continues below */
+	}
+
+	if ((m = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new", __func__);
+
+	mm_request_receive(pmonitor->m_sendfd, m);
+	if ((r = sshbuf_get_u8(m, &type)) != 0)
+		fatal("%s: decode: %s", __func__, ssh_err(r));
+
+	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);
+		sshbuf_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 ||
+	    timingsafe_bcmp(key_blob, blob, key_bloblen))
+		return (0);
+	return (1);
+}
+
+static void
+monitor_reset_key_state(void)
+{
+	/* reset state */
+	free(key_blob);
+	free(hostbased_cuser);
+	free(hostbased_chost);
+	sshauthopt_free(key_opts);
+	key_blob = NULL;
+	key_bloblen = 0;
+	key_blobtype = MM_NOKEY;
+	key_opts = NULL;
+	hostbased_cuser = NULL;
+	hostbased_chost = NULL;
+}
+
+#ifdef WITH_OPENSSL
+int
+mm_answer_moduli(int sock, struct sshbuf *m)
+{
+	DH *dh;
+	const BIGNUM *dh_p, *dh_g;
+	int r;
+	u_int min, want, max;
+
+	if ((r = sshbuf_get_u32(m, &min)) != 0 ||
+	    (r = sshbuf_get_u32(m, &want)) != 0 ||
+	    (r = sshbuf_get_u32(m, &max)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	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);
+
+	sshbuf_reset(m);
+
+	dh = choose_dh(min, want, max);
+	if (dh == NULL) {
+		if ((r = sshbuf_put_u8(m, 0)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+		return (0);
+	} else {
+		/* Send first bignum */
+		DH_get0_pqg(dh, &dh_p, NULL, &dh_g);
+		if ((r = sshbuf_put_u8(m, 1)) != 0 ||
+		    (r = sshbuf_put_bignum2(m, dh_p)) != 0 ||
+		    (r = sshbuf_put_bignum2(m, dh_g)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+		DH_free(dh);
+	}
+	mm_request_send(sock, MONITOR_ANS_MODULI, m);
+	return (0);
+}
+#endif
+
+int
+mm_answer_sign(int sock, struct sshbuf *m)
+{
+	struct ssh *ssh = active_state; 	/* XXX */
+	extern int auth_sock;			/* XXX move to state struct? */
+	struct sshkey *key;
+	struct sshbuf *sigbuf = NULL;
+	u_char *p = NULL, *signature = NULL;
+	char *alg = NULL;
+	size_t datlen, siglen, alglen;
+	int r, is_proof = 0;
+	u_int keyid, compat;
+	const char proof_req[] = "hostkeys-prove-00@openssh.com";
+
+	debug3("%s", __func__);
+
+	if ((r = sshbuf_get_u32(m, &keyid)) != 0 ||
+	    (r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
+	    (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 ||
+	    (r = sshbuf_get_u32(m, &compat)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (keyid > INT_MAX)
+		fatal("%s: invalid key ID", __func__);
+
+	/*
+	 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),
+	 * SHA384 (48 bytes) and SHA512 (64 bytes).
+	 *
+	 * Otherwise, verify the signature request is for a hostkey
+	 * proof.
+	 *
+	 * XXX perform similar check for KEX signature requests too?
+	 * it's not trivial, since what is signed is the hash, rather
+	 * than the full kex structure...
+	 */
+	if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) {
+		/*
+		 * Construct expected hostkey proof and compare it to what
+		 * the client sent us.
+		 */
+		if (session_id2_len == 0) /* hostkeys is never first */
+			fatal("%s: bad data length: %zu", __func__, datlen);
+		if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL)
+			fatal("%s: no hostkey for index %d", __func__, keyid);
+		if ((sigbuf = sshbuf_new()) == NULL)
+			fatal("%s: sshbuf_new", __func__);
+		if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 ||
+		    (r = sshbuf_put_string(sigbuf, session_id2,
+		    session_id2_len)) != 0 ||
+		    (r = sshkey_puts(key, sigbuf)) != 0)
+			fatal("%s: couldn't prepare private key "
+			    "proof buffer: %s", __func__, ssh_err(r));
+		if (datlen != sshbuf_len(sigbuf) ||
+		    memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0)
+			fatal("%s: bad data length: %zu, hostkey proof len %zu",
+			    __func__, datlen, sshbuf_len(sigbuf));
+		sshbuf_free(sigbuf);
+		is_proof = 1;
+	}
+
+	/* 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) {
+		if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
+		    compat)) != 0)
+			fatal("%s: sshkey_sign failed: %s",
+			    __func__, ssh_err(r));
+	} else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
+	    auth_sock > 0) {
+		if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen,
+		    p, datlen, alg, compat)) != 0) {
+			fatal("%s: ssh_agent_sign failed: %s",
+			    __func__, ssh_err(r));
+		}
+	} else
+		fatal("%s: no hostkey from index %d", __func__, keyid);
+
+	debug3("%s: %s signature %p(%zu)", __func__,
+	    is_proof ? "KEX" : "hostkey proof", signature, siglen);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	free(alg);
+	free(p);
+	free(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, struct sshbuf *m)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+	char *username;
+	struct passwd *pwent;
+	int r, allowed = 0;
+	u_int i;
+
+	debug3("%s", __func__);
+
+	if (authctxt->attempt++ != 0)
+		fatal("%s: multiple attempts for getpwnam", __func__);
+
+	if ((r = sshbuf_get_cstring(m, &username, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	pwent = getpwnamallow(username);
+
+	authctxt->user = xstrdup(username);
+	setproctitle("%s [priv]", pwent ? username : "unknown");
+	free(username);
+
+	sshbuf_reset(m);
+
+	if (pwent == NULL) {
+		if ((r = sshbuf_put_u8(m, 0)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+		authctxt->pw = fakepw();
+		goto out;
+	}
+
+	allowed = 1;
+	authctxt->pw = pwent;
+	authctxt->valid = 1;
+
+	/* XXX don't sent pwent to unpriv; send fake class/dir/shell too */
+	if ((r = sshbuf_put_u8(m, 1)) != 0 ||
+	    (r = sshbuf_put_string(m, pwent, sizeof(*pwent))) != 0 ||
+	    (r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
+	    (r = sshbuf_put_cstring(m, "*")) != 0 ||
+#ifdef HAVE_STRUCT_PASSWD_PW_GECOS
+	    (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 ||
+#endif
+#ifdef HAVE_STRUCT_PASSWD_PW_CLASS
+	    (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 ||
+#endif
+	    (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 ||
+	    (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+ out:
+	ssh_packet_set_log_preamble(ssh, "%suser %s",
+	    authctxt->valid ? "authenticating" : "invalid ", authctxt->user);
+	if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+#define M_CP_STROPT(x) do { \
+		if (options.x != NULL) { \
+			if ((r = sshbuf_put_cstring(m, options.x)) != 0) \
+				fatal("%s: buffer error: %s", \
+				    __func__, ssh_err(r)); \
+		} \
+	} while (0)
+#define M_CP_STRARRAYOPT(x, nx) do { \
+		for (i = 0; i < options.nx; i++) { \
+			if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \
+				fatal("%s: buffer error: %s", \
+				    __func__, ssh_err(r)); \
+		} \
+	} while (0)
+	/* See comment in servconf.h */
+	COPY_MATCH_STRING_OPTS();
+#undef M_CP_STROPT
+#undef M_CP_STRARRAYOPT
+
+	/* Create valid auth method lists */
+	if (auth2_setup_methods_lists(authctxt) != 0) {
+		/*
+		 * The monitor will continue long enough to let the child
+		 * run to it's packet_disconnect(), but it must not allow any
+		 * authentication to succeed.
+		 */
+		debug("%s: no valid authentication method lists", __func__);
+	}
+
+	debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed);
+	mm_request_send(sock, MONITOR_ANS_PWNAM, m);
+
+	/* 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);
+
+#ifdef USE_PAM
+	if (options.use_pam)
+		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
+#endif
+
+	return (0);
+}
+
+int mm_answer_auth2_read_banner(int sock, struct sshbuf *m)
+{
+	char *banner;
+	int r;
+
+	sshbuf_reset(m);
+	banner = auth2_read_banner();
+	if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
+	free(banner);
+
+	return (0);
+}
+
+int
+mm_answer_authserv(int sock, struct sshbuf *m)
+{
+	int r;
+
+	monitor_permit_authentications(1);
+
+	if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 ||
+	    (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	debug3("%s: service=%s, style=%s",
+	    __func__, authctxt->service, authctxt->style);
+
+	if (strlen(authctxt->style) == 0) {
+		free(authctxt->style);
+		authctxt->style = NULL;
+	}
+
+	return (0);
+}
+
+int
+mm_answer_authpassword(int sock, struct sshbuf *m)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+	static int call_count;
+	char *passwd;
+	int r, authenticated;
+	size_t plen;
+
+	if (!options.password_authentication)
+		fatal("%s: password authentication not enabled", __func__);
+	if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	/* Only authenticate if the context is valid */
+	authenticated = options.password_authentication &&
+	    auth_password(ssh, passwd);
+	explicit_bzero(passwd, plen);
+	free(passwd);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, authenticated)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+#ifdef USE_PAM
+	if ((r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+#endif
+
+	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, struct sshbuf *m)
+{
+	char *name, *infotxt;
+	u_int numprompts, *echo_on, success;
+	char **prompts;
+	int r;
+
+	if (!options.kbd_interactive_authentication)
+		fatal("%s: kbd-int authentication not enabled", __func__);
+	success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
+	    &prompts, &echo_on) < 0 ? 0 : 1;
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, success)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (success) {
+		if ((r = sshbuf_put_cstring(m, prompts[0])) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	}
+
+	debug3("%s: sending challenge success: %u", __func__, success);
+	mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);
+
+	if (success) {
+		free(name);
+		free(infotxt);
+		free(prompts);
+		free(echo_on);
+	}
+
+	return (0);
+}
+
+int
+mm_answer_bsdauthrespond(int sock, struct sshbuf *m)
+{
+	char *response;
+	int r, authok;
+
+	if (!options.kbd_interactive_authentication)
+		fatal("%s: kbd-int authentication not enabled", __func__);
+	if (authctxt->as == NULL)
+		fatal("%s: no bsd auth session", __func__);
+
+	if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	authok = options.challenge_response_authentication &&
+	    auth_userresponse(authctxt->as, response, 0);
+	authctxt->as = NULL;
+	debug3("%s: <%s> = <%d>", __func__, response, authok);
+	free(response);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, authok)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	debug3("%s: sending authenticated: %d", __func__, authok);
+	mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
+
+	auth_method = "keyboard-interactive";
+	auth_submethod = "bsdauth";
+
+	return (authok != 0);
+}
+#endif
+
+#ifdef USE_PAM
+int
+mm_answer_pam_start(int sock, struct sshbuf *m)
+{
+	if (!options.use_pam)
+		fatal("UsePAM not set, but ended up in %s anyway", __func__);
+
+	start_pam(authctxt);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
+	if (options.kbd_interactive_authentication)
+		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
+
+	return (0);
+}
+
+int
+mm_answer_pam_account(int sock, struct sshbuf *m)
+{
+	u_int ret;
+	int r;
+
+	if (!options.use_pam)
+		fatal("%s: PAM not enabled", __func__);
+
+	ret = do_pam_account();
+
+	if ((r = sshbuf_put_u32(m, ret)) != 0 ||
+	    (r = sshbuf_put_stringb(m, loginmsg)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m);
+
+	return (ret);
+}
+
+static void *sshpam_ctxt, *sshpam_authok;
+extern KbdintDevice sshpam_device;
+
+int
+mm_answer_pam_init_ctx(int sock, struct sshbuf *m)
+{
+	u_int ok = 0;
+	int r;
+
+	debug3("%s", __func__);
+	if (!options.kbd_interactive_authentication)
+		fatal("%s: kbd-int authentication not enabled", __func__);
+	if (sshpam_ctxt != NULL)
+		fatal("%s: already called", __func__);
+	sshpam_ctxt = (sshpam_device.init_ctx)(authctxt);
+	sshpam_authok = NULL;
+	sshbuf_reset(m);
+	if (sshpam_ctxt != NULL) {
+		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1);
+		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1);
+		ok = 1;
+	}
+	if ((r = sshbuf_put_u32(m, ok)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m);
+	return (0);
+}
+
+int
+mm_answer_pam_query(int sock, struct sshbuf *m)
+{
+	char *name = NULL, *info = NULL, **prompts = NULL;
+	u_int i, num = 0, *echo_on = 0;
+	int r, ret;
+
+	debug3("%s", __func__);
+	sshpam_authok = NULL;
+	if (sshpam_ctxt == NULL)
+		fatal("%s: no context", __func__);
+	ret = (sshpam_device.query)(sshpam_ctxt, &name, &info,
+	    &num, &prompts, &echo_on);
+	if (ret == 0 && num == 0)
+		sshpam_authok = sshpam_ctxt;
+	if (num > 1 || name == NULL || info == NULL)
+		fatal("sshpam_device.query failed");
+	monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1);
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, ret)) != 0 ||
+	    (r = sshbuf_put_cstring(m, name)) != 0 ||
+	    (r = sshbuf_put_cstring(m, info)) != 0 ||
+	    (r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0 ||
+	    (r = sshbuf_put_u32(m, num)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	free(name);
+	free(info);
+	for (i = 0; i < num; ++i) {
+		if ((r = sshbuf_put_cstring(m, prompts[i])) != 0 ||
+		    (r = sshbuf_put_u32(m, echo_on[i])) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+		free(prompts[i]);
+	}
+	free(prompts);
+	free(echo_on);
+	auth_method = "keyboard-interactive";
+	auth_submethod = "pam";
+	mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m);
+	return (0);
+}
+
+int
+mm_answer_pam_respond(int sock, struct sshbuf *m)
+{
+	char **resp;
+	u_int i, num;
+	int r, ret;
+
+	debug3("%s", __func__);
+	if (sshpam_ctxt == NULL)
+		fatal("%s: no context", __func__);
+	sshpam_authok = NULL;
+	if ((r = sshbuf_get_u32(m, &num)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (num > 0) {
+		resp = xcalloc(num, sizeof(char *));
+		for (i = 0; i < num; ++i) {
+			if ((r = sshbuf_get_cstring(m, &(resp[i]), NULL)) != 0)
+				fatal("%s: buffer error: %s",
+				    __func__, ssh_err(r));
+		}
+		ret = (sshpam_device.respond)(sshpam_ctxt, num, resp);
+		for (i = 0; i < num; ++i)
+			free(resp[i]);
+		free(resp);
+	} else {
+		ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL);
+	}
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, ret)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m);
+	auth_method = "keyboard-interactive";
+	auth_submethod = "pam";
+	if (ret == 0)
+		sshpam_authok = sshpam_ctxt;
+	return (0);
+}
+
+int
+mm_answer_pam_free_ctx(int sock, struct sshbuf *m)
+{
+	int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt;
+
+	debug3("%s", __func__);
+	if (sshpam_ctxt == NULL)
+		fatal("%s: no context", __func__);
+	(sshpam_device.free_ctx)(sshpam_ctxt);
+	sshpam_ctxt = sshpam_authok = NULL;
+	sshbuf_reset(m);
+	mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m);
+	/* Allow another attempt */
+	monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
+	auth_method = "keyboard-interactive";
+	auth_submethod = "pam";
+	return r;
+}
+#endif
+
+int
+mm_answer_keyallowed(int sock, struct sshbuf *m)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+	struct sshkey *key = NULL;
+	char *cuser, *chost;
+	u_int pubkey_auth_attempt;
+	enum mm_keytype type = 0;
+	int r, allowed = 0;
+	struct sshauthopt *opts = NULL;
+
+	debug3("%s entering", __func__);
+	if ((r = sshbuf_get_u32(m, &type)) != 0 ||
+	    (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 ||
+	    (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
+	    (r = sshkey_froms(m, &key)) != 0 ||
+	    (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	debug3("%s: key_from_blob: %p", __func__, key);
+
+	if (key != NULL && authctxt->valid) {
+		/* These should not make it past the privsep child */
+		if (sshkey_type_plain(key->type) == KEY_RSA &&
+		    (datafellows & SSH_BUG_RSASIGMD5) != 0)
+			fatal("%s: passed a SSH_BUG_RSASIGMD5 key", __func__);
+
+		switch (type) {
+		case MM_USERKEY:
+			auth_method = "publickey";
+			if (!options.pubkey_authentication)
+				break;
+			if (auth2_key_already_used(authctxt, key))
+				break;
+			if (match_pattern_list(sshkey_ssh_name(key),
+			    options.pubkey_key_types, 0) != 1)
+				break;
+			allowed = user_key_allowed(ssh, authctxt->pw, key,
+			    pubkey_auth_attempt, &opts);
+			break;
+		case MM_HOSTKEY:
+			auth_method = "hostbased";
+			if (!options.hostbased_authentication)
+				break;
+			if (auth2_key_already_used(authctxt, key))
+				break;
+			if (match_pattern_list(sshkey_ssh_name(key),
+			    options.hostbased_key_types, 0) != 1)
+				break;
+			allowed = hostbased_key_allowed(authctxt->pw,
+			    cuser, chost, key);
+			auth2_record_info(authctxt,
+			    "client user \"%.100s\", client host \"%.100s\"",
+			    cuser, chost);
+			break;
+		default:
+			fatal("%s: unknown key type %d", __func__, type);
+			break;
+		}
+	}
+
+	debug3("%s: %s authentication%s: %s key is %s", __func__,
+	    auth_method, pubkey_auth_attempt ? "" : " test",
+	    (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key),
+	    allowed ? "allowed" : "not allowed");
+
+	auth2_record_key(authctxt, 0, key);
+
+	/* clear temporarily storage (used by verify) */
+	monitor_reset_key_state();
+
+	if (allowed) {
+		/* Save temporarily for comparison in verify */
+		if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+		key_blobtype = type;
+		key_opts = opts;
+		hostbased_cuser = cuser;
+		hostbased_chost = chost;
+	} else {
+		/* Log failed attempt */
+		auth_log(authctxt, 0, 0, auth_method, NULL);
+		free(cuser);
+		free(chost);
+	}
+	sshkey_free(key);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, allowed)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0)
+		fatal("%s: sshauthopt_serialise: %s", __func__, ssh_err(r));
+	mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);
+
+	if (!allowed)
+		sshauthopt_free(opts);
+
+	return (0);
+}
+
+static int
+monitor_valid_userblob(u_char *data, u_int datalen)
+{
+	struct sshbuf *b;
+	const u_char *p;
+	char *userstyle, *cp;
+	size_t len;
+	u_char type;
+	int r, fail = 0;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new", __func__);
+	if ((r = sshbuf_put(b, data, datalen)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	if (datafellows & SSH_OLD_SESSIONID) {
+		p = sshbuf_ptr(b);
+		len = sshbuf_len(b);
+		if ((session_id2 == NULL) ||
+		    (len < session_id2_len) ||
+		    (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
+			fail++;
+		if ((r = sshbuf_consume(b, session_id2_len)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	} else {
+		if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
+			fatal("%s: buffer error: %s", __func__, ssh_err(r));
+		if ((session_id2 == NULL) ||
+		    (len != session_id2_len) ||
+		    (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
+			fail++;
+	}
+	if ((r = sshbuf_get_u8(b, &type)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (type != SSH2_MSG_USERAUTH_REQUEST)
+		fail++;
+	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	xasprintf(&userstyle, "%s%s%s", authctxt->user,
+	    authctxt->style ? ":" : "",
+	    authctxt->style ? authctxt->style : "");
+	if (strcmp(userstyle, cp) != 0) {
+		logit("wrong user name passed to monitor: "
+		    "expected %s != %.100s", userstyle, cp);
+		fail++;
+	}
+	free(userstyle);
+	free(cp);
+	if ((r = sshbuf_skip_string(b)) != 0 ||	/* service */
+	    (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (strcmp("publickey", cp) != 0)
+		fail++;
+	free(cp);
+	if ((r = sshbuf_get_u8(b, &type)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (type == 0)
+		fail++;
+	if ((r = sshbuf_skip_string(b)) != 0 ||	/* pkalg */
+	    (r = sshbuf_skip_string(b)) != 0)	/* pkblob */
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (sshbuf_len(b) != 0)
+		fail++;
+	sshbuf_free(b);
+	return (fail == 0);
+}
+
+static int
+monitor_valid_hostbasedblob(u_char *data, u_int datalen, char *cuser,
+    char *chost)
+{
+	struct sshbuf *b;
+	const u_char *p;
+	char *cp, *userstyle;
+	size_t len;
+	int r, fail = 0;
+	u_char type;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new", __func__);
+	if ((r = sshbuf_put(b, data, datalen)) != 0 ||
+	    (r = sshbuf_get_string_direct(b, &p, &len)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	if ((session_id2 == NULL) ||
+	    (len != session_id2_len) ||
+	    (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
+		fail++;
+
+	if ((r = sshbuf_get_u8(b, &type)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (type != SSH2_MSG_USERAUTH_REQUEST)
+		fail++;
+	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	xasprintf(&userstyle, "%s%s%s", authctxt->user,
+	    authctxt->style ? ":" : "",
+	    authctxt->style ? authctxt->style : "");
+	if (strcmp(userstyle, cp) != 0) {
+		logit("wrong user name passed to monitor: "
+		    "expected %s != %.100s", userstyle, cp);
+		fail++;
+	}
+	free(userstyle);
+	free(cp);
+	if ((r = sshbuf_skip_string(b)) != 0 ||	/* service */
+	    (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (strcmp(cp, "hostbased") != 0)
+		fail++;
+	free(cp);
+	if ((r = sshbuf_skip_string(b)) != 0 ||	/* pkalg */
+	    (r = sshbuf_skip_string(b)) != 0)	/* pkblob */
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	/* verify client host, strip trailing dot if necessary */
+	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (((len = strlen(cp)) > 0) && cp[len - 1] == '.')
+		cp[len - 1] = '\0';
+	if (strcmp(cp, chost) != 0)
+		fail++;
+	free(cp);
+
+	/* verify client user */
+	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (strcmp(cp, cuser) != 0)
+		fail++;
+	free(cp);
+
+	if (sshbuf_len(b) != 0)
+		fail++;
+	sshbuf_free(b);
+	return (fail == 0);
+}
+
+int
+mm_answer_keyverify(int sock, struct sshbuf *m)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+	struct sshkey *key;
+	u_char *signature, *data, *blob;
+	char *sigalg;
+	size_t signaturelen, datalen, bloblen;
+	int r, ret, valid_data = 0, encoded_ret;
+
+	if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 ||
+	    (r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 ||
+	    (r = sshbuf_get_string(m, &data, &datalen)) != 0 ||
+	    (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	if (hostbased_cuser == NULL || hostbased_chost == NULL ||
+	  !monitor_allowed_key(blob, bloblen))
+		fatal("%s: bad key, not previously allowed", __func__);
+
+	/* Empty signature algorithm means NULL. */
+	if (*sigalg == '\0') {
+		free(sigalg);
+		sigalg = NULL;
+	}
+
+	/* XXX use sshkey_froms here; need to change key_blob, etc. */
+	if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
+		fatal("%s: bad public key blob: %s", __func__, ssh_err(r));
+
+	switch (key_blobtype) {
+	case MM_USERKEY:
+		valid_data = monitor_valid_userblob(data, datalen);
+		auth_method = "publickey";
+		break;
+	case MM_HOSTKEY:
+		valid_data = monitor_valid_hostbasedblob(data, datalen,
+		    hostbased_cuser, hostbased_chost);
+		auth_method = "hostbased";
+		break;
+	default:
+		valid_data = 0;
+		break;
+	}
+	if (!valid_data)
+		fatal("%s: bad signature data blob", __func__);
+
+	ret = sshkey_verify(key, signature, signaturelen, data, datalen,
+	    sigalg, active_state->compat);
+	debug3("%s: %s %p signature %s", __func__, auth_method, key,
+	    (ret == 0) ? "verified" : "unverified");
+	auth2_record_key(authctxt, ret == 0, key);
+
+	free(blob);
+	free(signature);
+	free(data);
+	free(sigalg);
+
+	if (key_blobtype == MM_USERKEY)
+		auth_activate_options(ssh, key_opts);
+	monitor_reset_key_state();
+
+	sshkey_free(key);
+	sshbuf_reset(m);
+
+	/* encode ret != 0 as positive integer, since we're sending u32 */
+	encoded_ret = (ret != 0);
+	if ((r = sshbuf_put_u32(m, encoded_ret)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
+
+	return ret == 0;
+}
+
+static void
+mm_record_login(Session *s, struct passwd *pw)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+	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,
+	    session_get_remote_name_or_ip(ssh, 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);
+	}
+	session_unused(s->self);
+}
+
+int
+mm_answer_pty(int sock, struct sshbuf *m)
+{
+	extern struct monitor *pmonitor;
+	Session *s;
+	int r, res, fd0;
+
+	debug3("%s entering", __func__);
+
+	sshbuf_reset(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);
+
+	if ((r = sshbuf_put_u32(m, 1)) != 0 ||
+	    (r = sshbuf_put_cstring(m, s->tty)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	/* 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 */
+	if ((r = sshbuf_put_stringb(m, loginmsg)) != 0)
+		fatal("%s: put login message: %s", __func__, ssh_err(r));
+	sshbuf_reset(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);
+	if ((r = sshbuf_put_u32(m, 0)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	mm_request_send(sock, MONITOR_ANS_PTY, m);
+	return (0);
+}
+
+int
+mm_answer_pty_cleanup(int sock, struct sshbuf *m)
+{
+	Session *s;
+	char *tty;
+	int r;
+
+	debug3("%s entering", __func__);
+
+	if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if ((s = session_by_tty(tty)) != NULL)
+		mm_session_close(s);
+	sshbuf_reset(m);
+	free(tty);
+	return (0);
+}
+
+int
+mm_answer_term(int sock, struct sshbuf *req)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+	extern struct monitor *pmonitor;
+	int res, status;
+
+	debug3("%s: tearing down sessions", __func__);
+
+	/* The child is terminating */
+	session_destroy_all(ssh, &mm_session_close);
+
+#ifdef USE_PAM
+	if (options.use_pam)
+		sshpam_cleanup();
+#endif
+
+	while (waitpid(pmonitor->m_pid, &status, 0) == -1)
+		if (errno != EINTR)
+			exit(1);
+
+	res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
+
+	/* Terminate process */
+	exit(res);
+}
+
+#ifdef SSH_AUDIT_EVENTS
+/* Report that an audit event occurred */
+int
+mm_answer_audit_event(int socket, struct sshbuf *m)
+{
+	u_int n;
+	ssh_audit_event_t event;
+	int r;
+
+	debug3("%s entering", __func__);
+
+	if ((r = sshbuf_get_u32(m, &n)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	event = (ssh_audit_event_t)n;
+	switch (event) {
+	case SSH_AUTH_FAIL_PUBKEY:
+	case SSH_AUTH_FAIL_HOSTBASED:
+	case SSH_AUTH_FAIL_GSSAPI:
+	case SSH_LOGIN_EXCEED_MAXTRIES:
+	case SSH_LOGIN_ROOT_DENIED:
+	case SSH_CONNECTION_CLOSE:
+	case SSH_INVALID_USER:
+		audit_event(event);
+		break;
+	default:
+		fatal("Audit event type %d not permitted", event);
+	}
+
+	return (0);
+}
+
+int
+mm_answer_audit_command(int socket, struct sshbuf *m)
+{
+	char *cmd;
+	int r;
+
+	debug3("%s entering", __func__);
+	if ((r = sshbuf_get_cstring(m, &cmd, NULL)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	/* sanity check command, if so how? */
+	audit_run_command(cmd);
+	free(cmd);
+	return (0);
+}
+#endif /* SSH_AUDIT_EVENTS */
+
+void
+monitor_clear_keystate(struct monitor *pmonitor)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+
+	ssh_clear_newkeys(ssh, MODE_IN);
+	ssh_clear_newkeys(ssh, MODE_OUT);
+	sshbuf_free(child_state);
+	child_state = NULL;
+}
+
+void
+monitor_apply_keystate(struct monitor *pmonitor)
+{
+	struct ssh *ssh = active_state;	/* XXX */
+	struct kex *kex;
+	int r;
+
+	debug3("%s: packet_set_state", __func__);
+	if ((r = ssh_packet_set_state(ssh, child_state)) != 0)
+                fatal("%s: packet_set_state: %s", __func__, ssh_err(r));
+	sshbuf_free(child_state);
+	child_state = NULL;
+
+	if ((kex = ssh->kex) != NULL) {
+		/* XXX set callbacks */
+#ifdef WITH_OPENSSL
+		kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
+		kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
+		kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
+		kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
+		kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
+		kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
+		kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
+# ifdef OPENSSL_HAS_ECC
+		kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
+# endif
+#endif /* WITH_OPENSSL */
+		kex->kex[KEX_C25519_SHA256] = kexc25519_server;
+		kex->load_host_public_key=&get_hostkey_public_by_type;
+		kex->load_host_private_key=&get_hostkey_private_by_type;
+		kex->host_key_index=&get_hostkey_index;
+		kex->sign = sshd_hostkey_sign;
+	}
+}
+
+/* This function requries careful sanity checking */
+
+void
+mm_get_keystate(struct monitor *pmonitor)
+{
+	debug3("%s: Waiting for new keys", __func__);
+
+	if ((child_state = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT,
+	    child_state);
+	debug3("%s: GOT new keys", __func__);
+}
+
+
+/* XXX */
+
+#define FD_CLOSEONEXEC(x) do { \
+	if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \
+		fatal("fcntl(%d, F_SETFD)", x); \
+} while (0)
+
+static void
+monitor_openfds(struct monitor *mon, int do_logfds)
+{
+	int pair[2];
+#ifdef SO_ZEROIZE
+	int on = 1;
+#endif
+
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
+		fatal("%s: socketpair: %s", __func__, strerror(errno));
+#ifdef SO_ZEROIZE
+	if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) < 0)
+		error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno));
+	if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) < 0)
+		error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno));
+#endif
+	FD_CLOSEONEXEC(pair[0]);
+	FD_CLOSEONEXEC(pair[1]);
+	mon->m_recvfd = pair[0];
+	mon->m_sendfd = pair[1];
+
+	if (do_logfds) {
+		if (pipe(pair) == -1)
+			fatal("%s: pipe: %s", __func__, strerror(errno));
+		FD_CLOSEONEXEC(pair[0]);
+		FD_CLOSEONEXEC(pair[1]);
+		mon->m_log_recvfd = pair[0];
+		mon->m_log_sendfd = pair[1];
+	} else
+		mon->m_log_recvfd = mon->m_log_sendfd = -1;
+}
+
+#define MM_MEMSIZE	65536
+
+struct monitor *
+monitor_init(void)
+{
+	struct monitor *mon;
+
+	mon = xcalloc(1, sizeof(*mon));
+	monitor_openfds(mon, 1);
+
+	return mon;
+}
+
+void
+monitor_reinit(struct monitor *mon)
+{
+	monitor_openfds(mon, 0);
+}
+
+#ifdef GSSAPI
+int
+mm_answer_gss_setup_ctx(int sock, struct sshbuf *m)
+{
+	gss_OID_desc goid;
+	OM_uint32 major;
+	size_t len;
+	u_char *p;
+	int r;
+
+	if (!options.gss_authentication)
+		fatal("%s: GSSAPI authentication not enabled", __func__);
+
+	if ((r = sshbuf_get_string(m, &p, &len)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	goid.elements = p;
+	goid.length = len;
+
+	major = ssh_gssapi_server_ctx(&gsscontext, &goid);
+
+	free(goid.elements);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, major)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	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, struct sshbuf *m)
+{
+	gss_buffer_desc in;
+	gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
+	OM_uint32 major, minor;
+	OM_uint32 flags = 0; /* GSI needs this */
+	int r;
+
+	if (!options.gss_authentication)
+		fatal("%s: GSSAPI authentication not enabled", __func__);
+
+	if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
+	free(in.value);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, major)) != 0 ||
+	    (r = sshbuf_put_string(m, out.value, out.length)) != 0 ||
+	    (r = sshbuf_put_u32(m, flags)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	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, struct sshbuf *m)
+{
+	gss_buffer_desc gssbuf, mic;
+	OM_uint32 ret;
+	int r;
+
+	if (!options.gss_authentication)
+		fatal("%s: GSSAPI authentication not enabled", __func__);
+
+	if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
+	    (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
+
+	free(gssbuf.value);
+	free(mic.value);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, ret)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	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, struct sshbuf *m)
+{
+	int r, authenticated;
+	const char *displayname;
+
+	if (!options.gss_authentication)
+		fatal("%s: GSSAPI authentication not enabled", __func__);
+
+	authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
+
+	sshbuf_reset(m);
+	if ((r = sshbuf_put_u32(m, authenticated)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+
+	debug3("%s: sending result %d", __func__, authenticated);
+	mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
+
+	auth_method = "gssapi-with-mic";
+
+	if ((displayname = ssh_gssapi_displayname()) != NULL)
+		auth2_record_info(authctxt, "%s", displayname);
+
+	/* Monitor loop will terminate if authenticated */
+	return (authenticated);
+}
+#endif /* GSSAPI */
+