- (djm) Merge FreeBSD PAM code: replaces PAM password auth kludge withAFTER_FREEBSD_PAM_MERGE

   proper challenge-response module

17 files changed, 819 insertions, 554 deletions

diff --git a/ChangeLog b/ChangeLog
index 5b4ff341..4acedd1a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,8 @@
    "make install".  Patch by roth@feep.net.
  - (dtucker) Bug #536: Test for and work around openpty/controlling tty
    problem on Linux (fixes "could not set controlling tty" errors).
+ - (djm) Merge FreeBSD PAM code: replaces PAM password auth kludge with 
+   proper challenge-response module
 
 20030504
  - (dtucker) Bug #497: Move #include of bsd-cygwin_util.h to openbsd-compat.h.
@@ -1376,4 +1378,4 @@
      save auth method before monitor_reset_key_state(); bugzilla bug #284;
      ok provos@
 
-$Id: ChangeLog,v 1.2672 2003/05/10 07:05:46 dtucker Exp $
+$Id: ChangeLog,v 1.2673 2003/05/10 09:28:02 djm Exp $
diff --git a/Makefile.in b/Makefile.in
index 23a9d413..670d9b50 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1,4 +1,4 @@
-# $Id: Makefile.in,v 1.230 2003/05/10 06:48:23 dtucker Exp $
+# $Id: Makefile.in,v 1.231 2003/05/10 09:28:02 djm Exp $
 
 # uncomment if you run a non bourne compatable shell. Ie. csh
 #SHELL = @SH@
@@ -81,7 +81,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o \
 	monitor_mm.o monitor.o monitor_wrap.o monitor_fdpass.o \
 	kexdhs.o kexgexs.o \
 	auth-krb5.o auth-krb4.o \
-	loginrec.o auth-pam.o auth2-pam.o auth-sia.o md5crypt.o
+	loginrec.o auth-pam.o auth-sia.o md5crypt.o
 
 MANPAGES	= scp.1.out ssh-add.1.out ssh-agent.1.out ssh-keygen.1.out ssh-keyscan.1.out ssh.1.out sshd.8.out sftp-server.8.out sftp.1.out ssh-rand-helper.8.out ssh-keysign.8.out sshd_config.5.out ssh_config.5.out
 MANPAGES_IN	= scp.1 ssh-add.1 ssh-agent.1 ssh-keygen.1 ssh-keyscan.1 ssh.1 sshd.8 sftp-server.8 sftp.1 ssh-rand-helper.8 ssh-keysign.8 sshd_config.5 ssh_config.5
diff --git a/auth-chall.c b/auth-chall.c
index 45e0c345..6b7c8bd1 100644
--- a/auth-chall.c
+++ b/auth-chall.c
@@ -76,7 +76,33 @@ verify_response(Authctxt *authctxt, const char *response)
 		return 0;
 	resp[0] = (char *)response;
 	res = device->respond(authctxt->kbdintctxt, 1, resp);
+	if (res == 1) {
+		/* postponed - send a null query just in case */
+		char *name, *info, **prompts;
+		u_int i, numprompts, *echo_on;
+
+		res = device->query(authctxt->kbdintctxt, &name, &info,
+		    &numprompts, &prompts, &echo_on);
+		if (res == 0) {
+			for (i = 0; i < numprompts; i++)
+				xfree(prompts[i]);
+			xfree(prompts);
+			xfree(name);
+			xfree(echo_on);
+			xfree(info);
+		}
+		/* if we received more prompts, we're screwed */
+		res = (numprompts != 0);
+	}
 	device->free_ctx(authctxt->kbdintctxt);
 	authctxt->kbdintctxt = NULL;
 	return res ? 0 : 1;
 }
+void
+abandon_challenge_response(Authctxt *authctxt)
+{
+	if (authctxt->kbdintctxt != NULL) {
+		device->free_ctx(authctxt->kbdintctxt);
+		authctxt->kbdintctxt = NULL;
+	}
+}
diff --git a/auth-pam.c b/auth-pam.c
index f3d1956e..f4718035 100644
--- a/auth-pam.c
+++ b/auth-pam.c
@@ -1,5 +1,11 @@
-/*
- * Copyright (c) 2000 Damien Miller.  All rights reserved.
+/*-
+ * Copyright (c) 2002 Networks Associates Technology, Inc.
+ * All rights reserved.
+ *
+ * This software was developed for the FreeBSD Project by ThinkSec AS and
+ * NAI Labs, the Security Research Division of Network Associates, Inc.
+ * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
+ * DARPA CHATS research program.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,446 +16,633 @@
  *    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.
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
  */
 
 #include "includes.h"
+RCSID("$FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $");
 
 #ifdef USE_PAM
-#include "xmalloc.h"
-#include "log.h"
+#include <security/pam_appl.h>
+
 #include "auth.h"
-#include "auth-options.h"
 #include "auth-pam.h"
-#include "servconf.h"
+#include "buffer.h"
+#include "bufaux.h"
 #include "canohost.h"
+#include "log.h"
+#include "monitor_wrap.h"
+#include "msg.h"
+#include "packet.h"
 #include "readpass.h"
+#include "servconf.h"
+#include "ssh2.h"
+#include "xmalloc.h"
 
-extern char *__progname;
-
-extern int use_privsep;
+#define __unused
 
-RCSID("$Id: auth-pam.c,v 1.57 2003/04/29 13:22:40 djm Exp $");
+#ifdef USE_POSIX_THREADS
+#include <pthread.h>
+/*
+ * Avoid namespace clash when *not* using pthreads for systems *with* 
+ * pthreads, which unconditionally define pthread_t via sys/types.h 
+ * (e.g. Linux)
+ */
+typedef pthread_t sp_pthread_t; 
+#else
+/*
+ * Simulate threads with processes.
+ */
+typedef pid_t sp_pthread_t;
 
-#define NEW_AUTHTOK_MSG \
-	"Warning: Your password has expired, please change it now."
-#define NEW_AUTHTOK_MSG_PRIVSEP \
-	"Your password has expired, the session cannot proceed."
+static void
+pthread_exit(void *value __unused)
+{
+	_exit(0);
+}
 
-static int do_pam_conversation(int num_msg, const struct pam_message **msg,
-	struct pam_response **resp, void *appdata_ptr);
+static int
+pthread_create(sp_pthread_t *thread, const void *attr __unused,
+    void *(*thread_start)(void *), void *arg)
+{
+	pid_t pid;
+
+	switch ((pid = fork())) {
+	case -1:
+		error("fork(): %s", strerror(errno));
+		return (-1);
+	case 0:
+		thread_start(arg);
+		_exit(1);
+	default:
+		*thread = pid;
+		return (0);
+	}
+}
 
-/* module-local variables */
-static struct pam_conv conv = {
-	(int (*)())do_pam_conversation,
-	NULL
-};
-static char *__pam_msg = NULL;
-static pam_handle_t *__pamh = NULL;
-static const char *__pampasswd = NULL;
-
-/* states for do_pam_conversation() */
-enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN;
-/* remember whether pam_acct_mgmt() returned PAM_NEW_AUTHTOK_REQD */
-static int password_change_required = 0;
-/* remember whether the last pam_authenticate() succeeded or not */
-static int was_authenticated = 0;
-
-/* Remember what has been initialised */
-static int session_opened = 0;
-static int creds_set = 0;
-
-/* accessor which allows us to switch conversation structs according to
- * the authentication method being used */
-void do_pam_set_conv(struct pam_conv *conv)
+static int
+pthread_cancel(sp_pthread_t thread)
 {
-	pam_set_item(__pamh, PAM_CONV, conv);
+	return (kill(thread, SIGTERM));
 }
 
-/* start an authentication run */
-int do_pam_authenticate(int flags)
+static int
+pthread_join(sp_pthread_t thread, void **value __unused)
 {
-	int retval = pam_authenticate(__pamh, flags);
-	was_authenticated = (retval == PAM_SUCCESS);
-	return retval;
+	int status;
+
+	waitpid(thread, &status, 0);
+	return (status);
 }
+#endif
+
+
+static pam_handle_t *sshpam_handle;
+static int sshpam_err;
+static int sshpam_authenticated;
+static int sshpam_new_authtok_reqd;
+static int sshpam_session_open;
+static int sshpam_cred_established;
+
+struct pam_ctxt {
+	sp_pthread_t	 pam_thread;
+	int		 pam_psock;
+	int		 pam_csock;
+	int		 pam_done;
+};
+
+static void sshpam_free_ctx(void *);
 
 /*
- * PAM conversation function.
- * There are two states this can run in.
- *
- * INITIAL_LOGIN mode simply feeds the password from the client into
- * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output
- * messages with into __pam_msg.  This is used during initial
- * authentication to bypass the normal PAM password prompt.
- *
- * OTHER mode handles PAM_PROMPT_ECHO_OFF with read_passphrase()
- * and outputs messages to stderr. This mode is used if pam_chauthtok()
- * is called to update expired passwords.
+ * Conversation function for authentication thread.
  */
-static int do_pam_conversation(int num_msg, const struct pam_message **msg,
-	struct pam_response **resp, void *appdata_ptr)
+static int
+sshpam_thread_conv(int n,
+	 const struct pam_message **msg,
+	 struct pam_response **resp,
+	 void *data)
 {
-	struct pam_response *reply;
-	int count;
-	char buf[1024];
-
-	/* PAM will free this later */
-	reply = xmalloc(num_msg * sizeof(*reply));
-
-	for (count = 0; count < num_msg; count++) {
-		if (pamstate == INITIAL_LOGIN) {
-			/*
-			 * We can't use stdio yet, queue messages for 
-			 * printing later
-			 */
-			switch(PAM_MSG_MEMBER(msg, count, msg_style)) {
-			case PAM_PROMPT_ECHO_ON:
-				xfree(reply);
-				return PAM_CONV_ERR;
-			case PAM_PROMPT_ECHO_OFF:
-				if (__pampasswd == NULL) {
-					xfree(reply);
-					return PAM_CONV_ERR;
-				}
-				reply[count].resp = xstrdup(__pampasswd);
-				reply[count].resp_retcode = PAM_SUCCESS;
-				break;
-			case PAM_ERROR_MSG:
-			case PAM_TEXT_INFO:
-				if (PAM_MSG_MEMBER(msg, count, msg) != NULL) {
-					message_cat(&__pam_msg, 
-					    PAM_MSG_MEMBER(msg, count, msg));
-				}
-				reply[count].resp = xstrdup("");
-				reply[count].resp_retcode = PAM_SUCCESS;
-				break;
-			default:
-				xfree(reply);
-				return PAM_CONV_ERR;
-			}
-		} else {
-			/*
-			 * stdio is connected, so interact directly
-			 */
-			switch(PAM_MSG_MEMBER(msg, count, msg_style)) {
-			case PAM_PROMPT_ECHO_ON:
-				fputs(PAM_MSG_MEMBER(msg, count, msg), stderr);
-				fgets(buf, sizeof(buf), stdin);
-				reply[count].resp = xstrdup(buf);
-				reply[count].resp_retcode = PAM_SUCCESS;
-				break;
-			case PAM_PROMPT_ECHO_OFF:
-				reply[count].resp = 
-				    read_passphrase(PAM_MSG_MEMBER(msg, count,
-					msg), RP_ALLOW_STDIN);
-				reply[count].resp_retcode = PAM_SUCCESS;
-				break;
-			case PAM_ERROR_MSG:
-			case PAM_TEXT_INFO:
-				if (PAM_MSG_MEMBER(msg, count, msg) != NULL)
-					fprintf(stderr, "%s\n", 
-					    PAM_MSG_MEMBER(msg, count, msg));
-				reply[count].resp = xstrdup("");
-				reply[count].resp_retcode = PAM_SUCCESS;
-				break;
-			default:
-				xfree(reply);
-				return PAM_CONV_ERR;
-			}
+	Buffer buffer;
+	struct pam_ctxt *ctxt;
+	int i;
+
+	ctxt = data;
+	if (n <= 0 || n > PAM_MAX_NUM_MSG)
+		return (PAM_CONV_ERR);
+	*resp = xmalloc(n * sizeof **resp);
+	buffer_init(&buffer);
+	for (i = 0; i < n; ++i) {
+		resp[i]->resp_retcode = 0;
+		resp[i]->resp = NULL;
+		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
+		case PAM_PROMPT_ECHO_OFF:
+			buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
+			ssh_msg_send(ctxt->pam_csock, 
+			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
+			ssh_msg_recv(ctxt->pam_csock, &buffer);
+			if (buffer_get_char(&buffer) != PAM_AUTHTOK)
+				goto fail;
+			resp[i]->resp = buffer_get_string(&buffer, NULL);
+			break;
+		case PAM_PROMPT_ECHO_ON:
+			buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
+			ssh_msg_send(ctxt->pam_csock, 
+			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
+			ssh_msg_recv(ctxt->pam_csock, &buffer);
+			if (buffer_get_char(&buffer) != PAM_AUTHTOK)
+				goto fail;
+			resp[i]->resp = buffer_get_string(&buffer, NULL);
+			break;
+		case PAM_ERROR_MSG:
+			buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
+			ssh_msg_send(ctxt->pam_csock, 
+			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
+			break;
+		case PAM_TEXT_INFO:
+			buffer_put_cstring(&buffer, PAM_MSG_MEMBER(msg, i, msg));
+			ssh_msg_send(ctxt->pam_csock, 
+			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer);
+			break;
+		default:
+			goto fail;
 		}
+		buffer_clear(&buffer);
 	}
+	buffer_free(&buffer);
+	return (PAM_SUCCESS);
+ fail:
+	while (i)
+		xfree(resp[--i]);
+	xfree(*resp);
+	*resp = NULL;
+	buffer_free(&buffer);
+	return (PAM_CONV_ERR);
+}
 
-	*resp = reply;
+/*
+ * Authentication thread.
+ */
+static void *
+sshpam_thread(void *ctxtp)
+{
+	struct pam_ctxt *ctxt = ctxtp;
+	Buffer buffer;
+	struct pam_conv sshpam_conv = { sshpam_thread_conv, ctxt };
+#ifndef USE_POSIX_THREADS
+	const char *pam_user;
+
+	pam_get_item(sshpam_handle, PAM_USER, (const void **)&pam_user);
+	setproctitle("%s [pam]", pam_user);
+#endif
 
-	return PAM_SUCCESS;
+	buffer_init(&buffer);
+	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+	    (const void *)&sshpam_conv);
+	if (sshpam_err != PAM_SUCCESS)
+		goto auth_fail;
+	sshpam_err = pam_authenticate(sshpam_handle, 0);
+	if (sshpam_err != PAM_SUCCESS)
+		goto auth_fail;
+	sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
+	if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD)
+		goto auth_fail;
+	buffer_put_cstring(&buffer, "OK");
+	ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
+	buffer_free(&buffer);
+	pthread_exit(NULL);
+
+ auth_fail:
+	buffer_put_cstring(&buffer,
+	    pam_strerror(sshpam_handle, sshpam_err));
+	ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
+	buffer_free(&buffer);
+	pthread_exit(NULL);
+	
+	return (NULL); /* Avoid warning for non-pthread case */
 }
 
-/* Called at exit to cleanly shutdown PAM */
-void do_pam_cleanup_proc(void *context)
+static void
+sshpam_thread_cleanup(void *ctxtp)
 {
-	int pam_retval = PAM_SUCCESS;
+	struct pam_ctxt *ctxt = ctxtp;
 
-	if (__pamh && session_opened) {
-		pam_retval = pam_close_session(__pamh, 0);
-		if (pam_retval != PAM_SUCCESS)
-			logit("Cannot close PAM session[%d]: %.200s",
-			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-	}
+	pthread_cancel(ctxt->pam_thread);
+	pthread_join(ctxt->pam_thread, NULL);
+	close(ctxt->pam_psock);
+	close(ctxt->pam_csock);
+}
 
-	if (__pamh && creds_set) {
-		pam_retval = pam_setcred(__pamh, PAM_DELETE_CRED);
-		if (pam_retval != PAM_SUCCESS)
-			debug("Cannot delete credentials[%d]: %.200s", 
-			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-	}
+static int
+sshpam_null_conv(int n,
+	 const struct pam_message **msg,
+	 struct pam_response **resp,
+	 void *data)
+{
+
+	return (PAM_CONV_ERR);
+}
 
-	if (__pamh) {
-		pam_retval = pam_end(__pamh, pam_retval);
-		if (pam_retval != PAM_SUCCESS)
-			logit("Cannot release PAM authentication[%d]: %.200s",
-			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+static struct pam_conv null_conv = { sshpam_null_conv, NULL };
+
+static void
+sshpam_cleanup(void *arg)
+{
+	(void)arg;
+	debug("PAM: cleanup");
+	pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
+	if (sshpam_cred_established) {
+		pam_setcred(sshpam_handle, PAM_DELETE_CRED);
+		sshpam_cred_established = 0;
+	}
+	if (sshpam_session_open) {
+		pam_close_session(sshpam_handle, PAM_SILENT);
+		sshpam_session_open = 0;
 	}
+	sshpam_authenticated = sshpam_new_authtok_reqd = 0;
+	pam_end(sshpam_handle, sshpam_err);
+	sshpam_handle = NULL;
 }
 
-/* Attempt password authentication using PAM */
-int auth_pam_password(Authctxt *authctxt, const char *password)
+static int
+sshpam_init(const char *user)
 {
 	extern ServerOptions options;
-	int pam_retval;
-	struct passwd *pw = authctxt->pw;
-
-	do_pam_set_conv(&conv);
-
-	__pampasswd = password;
-
-	pamstate = INITIAL_LOGIN;
-	pam_retval = do_pam_authenticate(
-	    options.permit_empty_passwd == 0 ? PAM_DISALLOW_NULL_AUTHTOK : 0);
-	if (pam_retval == PAM_SUCCESS && pw) {
-		debug("PAM password authentication accepted for "
-		    "%.100s", pw->pw_name);
-		return 1;
-	} else {
-		debug("PAM password authentication failed for "
-		    "%.100s: %s", pw ? pw->pw_name : "an illegal user",
-		    PAM_STRERROR(__pamh, pam_retval));
-		return 0;
+	extern u_int utmp_len;
+	const char *pam_rhost, *pam_user;
+
+	if (sshpam_handle != NULL) {
+		/* We already have a PAM context; check if the user matches */
+		sshpam_err = pam_get_item(sshpam_handle,
+		    PAM_USER, (const void **)&pam_user);
+		if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
+			return (0);
+		fatal_remove_cleanup(sshpam_cleanup, NULL);
+		pam_end(sshpam_handle, sshpam_err);
+		sshpam_handle = NULL;
+	}
+	debug("PAM: initializing for \"%s\"", user);
+	sshpam_err = pam_start("sshd", user, &null_conv, &sshpam_handle);
+	if (sshpam_err != PAM_SUCCESS)
+		return (-1);
+	pam_rhost = get_remote_name_or_ip(utmp_len,
+	    options.verify_reverse_mapping);
+	debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
+	sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
+	if (sshpam_err != PAM_SUCCESS) {
+		pam_end(sshpam_handle, sshpam_err);
+		sshpam_handle = NULL;
+		return (-1);
 	}
+	fatal_add_cleanup(sshpam_cleanup, NULL);
+	return (0);
 }
 
-/* Do account management using PAM */
-int do_pam_account(char *username, char *remote_user)
+static void *
+sshpam_init_ctx(Authctxt *authctxt)
 {
-	int pam_retval;
+	struct pam_ctxt *ctxt;
+	int socks[2];
 
-	do_pam_set_conv(&conv);
+	/* Initialize PAM */
+	if (sshpam_init(authctxt->user) == -1) {
+		error("PAM: initialization failed");
+		return (NULL);
+	}
 
-	if (remote_user) {
-		debug("PAM setting ruser to \"%.200s\"", remote_user);
-		pam_retval = pam_set_item(__pamh, PAM_RUSER, remote_user);
-		if (pam_retval != PAM_SUCCESS)
-			fatal("PAM set ruser failed[%d]: %.200s", pam_retval, 
-			    PAM_STRERROR(__pamh, pam_retval));
+	ctxt = xmalloc(sizeof *ctxt);
+	ctxt->pam_done = 0;
+
+	/* Start the authentication thread */
+	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
+		error("PAM: failed create sockets: %s", strerror(errno));
+		xfree(ctxt);
+		return (NULL);
+	}
+	ctxt->pam_psock = socks[0];
+	ctxt->pam_csock = socks[1];
+	if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
+		error("PAM: failed to start authentication thread: %s",
+		    strerror(errno));
+		close(socks[0]);
+		close(socks[1]);
+		xfree(ctxt);
+		return (NULL);
 	}
+	fatal_add_cleanup(sshpam_thread_cleanup, ctxt);
+	return (ctxt);
+}
 
-	pam_retval = pam_acct_mgmt(__pamh, 0);
-	debug2("pam_acct_mgmt() = %d", pam_retval);
-	switch (pam_retval) {
-		case PAM_SUCCESS:
-			/* This is what we want */
+static int
+sshpam_query(void *ctx, char **name, char **info,
+    u_int *num, char ***prompts, u_int **echo_on)
+{
+	Buffer buffer;
+	struct pam_ctxt *ctxt = ctx;
+	size_t plen;
+	u_char type;
+	char *msg;
+
+	buffer_init(&buffer);
+	*name = xstrdup("");
+	*info = xstrdup("");
+	*prompts = xmalloc(sizeof(char *));
+	**prompts = NULL;
+	plen = 0;
+	*echo_on = xmalloc(sizeof(u_int));
+	while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
+		type = buffer_get_char(&buffer);
+		msg = buffer_get_string(&buffer, NULL);
+		switch (type) {
+		case PAM_PROMPT_ECHO_ON:
+		case PAM_PROMPT_ECHO_OFF:
+			*num = 1;
+			**prompts = xrealloc(**prompts, plen + strlen(msg) + 1);
+			plen += sprintf(**prompts + plen, "%s", msg);
+			**echo_on = (type == PAM_PROMPT_ECHO_ON);
+			xfree(msg);
+			return (0);
+		case PAM_ERROR_MSG:
+		case PAM_TEXT_INFO:
+			/* accumulate messages */
+			**prompts = xrealloc(**prompts, plen + strlen(msg) + 1);
+			plen += sprintf(**prompts + plen, "%s", msg);
+			xfree(msg);
 			break;
-#if 0
 		case PAM_NEW_AUTHTOK_REQD:
-			message_cat(&__pam_msg, use_privsep ?
-			    NEW_AUTHTOK_MSG_PRIVSEP : NEW_AUTHTOK_MSG);
-			/* flag that password change is necessary */
-			password_change_required = 1;
-			/* disallow other functionality for now */
-			no_port_forwarding_flag |= 2;
-			no_agent_forwarding_flag |= 2;
-			no_x11_forwarding_flag |= 2;
-			break;
+			sshpam_new_authtok_reqd = 1;
+			/* FALLTHROUGH */
+		case PAM_SUCCESS:
+		case PAM_AUTH_ERR:
+			if (**prompts != NULL) {
+				/* drain any accumulated messages */
+#if 0 /* XXX - not compatible with privsep */
+				packet_start(SSH2_MSG_USERAUTH_BANNER);
+				packet_put_cstring(**prompts);
+				packet_put_cstring("");
+				packet_send();
+				packet_write_wait();
 #endif
+				xfree(**prompts);
+				**prompts = NULL;
+			}
+			if (type == PAM_SUCCESS) {
+				*num = 0;
+				**echo_on = 0;
+				ctxt->pam_done = 1;
+				xfree(msg);
+				return (0);
+			}
+			error("PAM: %s", msg);
 		default:
-			logit("PAM rejected by account configuration[%d]: "
-			    "%.200s", pam_retval, PAM_STRERROR(__pamh, 
-			    pam_retval));
-			return(0);
+			*num = 0;
+			**echo_on = 0;
+			xfree(msg);
+			ctxt->pam_done = -1;
+			return (-1);
+		}
 	}
-
-	return(1);
+	return (-1);
 }
 
-/* Do PAM-specific session initialisation */
-void do_pam_session(char *username, const char *ttyname)
+/* XXX - see also comment in auth-chall.c:verify_response */
+static int
+sshpam_respond(void *ctx, u_int num, char **resp)
 {
-	int pam_retval;
-
-	do_pam_set_conv(&conv);
-
-	if (ttyname != NULL) {
-		debug("PAM setting tty to \"%.200s\"", ttyname);
-		pam_retval = pam_set_item(__pamh, PAM_TTY, ttyname);
-		if (pam_retval != PAM_SUCCESS)
-			fatal("PAM set tty failed[%d]: %.200s",
-			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+	Buffer buffer;
+	struct pam_ctxt *ctxt = ctx;
+
+	debug2("PAM: %s", __func__);
+	switch (ctxt->pam_done) {
+	case 1:
+		sshpam_authenticated = 1;
+		return (0);
+	case 0:
+		break;
+	default:
+		return (-1);
 	}
-
-	pam_retval = pam_open_session(__pamh, 0);
-	if (pam_retval != PAM_SUCCESS)
-		fatal("PAM session setup failed[%d]: %.200s",
-		    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-
-	session_opened = 1;
+	if (num != 1) {
+		error("PAM: expected one response, got %u", num);
+		return (-1);
+	}
+	buffer_init(&buffer);
+	buffer_put_cstring(&buffer, *resp);
+	ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer);
+	buffer_free(&buffer);
+	return (1);
 }
 
-/* Set PAM credentials */
-void do_pam_setcred(int init)
+static void
+sshpam_free_ctx(void *ctxtp)
 {
-	int pam_retval;
-
-	if (__pamh == NULL)
-		return;
+	struct pam_ctxt *ctxt = ctxtp;
 
-	do_pam_set_conv(&conv);
-
-	debug("PAM establishing creds");
-	pam_retval = pam_setcred(__pamh, 
-	    init ? PAM_ESTABLISH_CRED : PAM_REINITIALIZE_CRED);
-	if (pam_retval != PAM_SUCCESS) {
-		if (was_authenticated)
-			fatal("PAM setcred failed[%d]: %.200s",
-			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-		else
-			debug("PAM setcred failed[%d]: %.200s",
-			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-	} else
-		creds_set = 1;
+	fatal_remove_cleanup(sshpam_thread_cleanup, ctxt);
+	sshpam_thread_cleanup(ctxtp);
+	xfree(ctxt);
+	/*
+	 * We don't call sshpam_cleanup() here because we may need the PAM
+	 * handle at a later stage, e.g. when setting up a session.  It's
+	 * still on the cleanup list, so pam_end() *will* be called before
+	 * the server process terminates.
+	 */
 }
 
-/* accessor function for file scope static variable */
-int is_pam_password_change_required(void)
-{
-	return password_change_required;
-}
+KbdintDevice sshpam_device = {
+	"pam",
+	sshpam_init_ctx,
+	sshpam_query,
+	sshpam_respond,
+	sshpam_free_ctx
+};
+
+KbdintDevice mm_sshpam_device = {
+	"pam",
+	mm_sshpam_init_ctx,
+	mm_sshpam_query,
+	mm_sshpam_respond,
+	mm_sshpam_free_ctx
+};
 
 /*
- * Have user change authentication token if pam_acct_mgmt() indicated
- * it was expired.  This needs to be called after an interactive
- * session is established and the user's pty is connected to
- * stdin/stdout/stderr.
+ * This replaces auth-pam.c
  */
-void do_pam_chauthtok(void)
+void
+start_pam(const char *user)
 {
-	int pam_retval;
-
-	do_pam_set_conv(&conv);
-
-	if (password_change_required) {
-		if (use_privsep)
-			fatal("Password changing is currently unsupported"
-			    " with privilege separation");
-		pamstate = OTHER;
-		pam_retval = pam_chauthtok(__pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
-		if (pam_retval != PAM_SUCCESS)
-			fatal("PAM pam_chauthtok failed[%d]: %.200s",
-			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-#if 0
-		/* XXX: This would need to be done in the parent process,
-		 * but there's currently no way to pass such request. */
-		no_port_forwarding_flag &= ~2;
-		no_agent_forwarding_flag &= ~2;
-		no_x11_forwarding_flag &= ~2;
-		if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
-			channel_permit_all_opens();
-#endif
-	}
+	if (sshpam_init(user) == -1)
+		fatal("PAM: initialisation failed");
 }
 
-/* Cleanly shutdown PAM */
-void finish_pam(void)
+void
+finish_pam(void)
 {
-	do_pam_cleanup_proc(NULL);
-	fatal_remove_cleanup(&do_pam_cleanup_proc, NULL);
+	fatal_remove_cleanup(sshpam_cleanup, NULL);
+	sshpam_cleanup(NULL);
 }
 
-/* Start PAM authentication for specified account */
-void start_pam(const char *user)
+int
+do_pam_account(const char *user, const char *ruser)
 {
-	int pam_retval;
-	extern ServerOptions options;
-	extern u_int utmp_len;
-	const char *rhost;
-
-	debug("Starting up PAM with username \"%.200s\"", user);
-
-	pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &__pamh);
-
-	if (pam_retval != PAM_SUCCESS)
-		fatal("PAM initialisation failed[%d]: %.200s",
-		    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-
-	rhost = get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping);
-	debug("PAM setting rhost to \"%.200s\"", rhost);
+	/* XXX */
+	return (1);
+}
 
-	pam_retval = pam_set_item(__pamh, PAM_RHOST, rhost);
-	if (pam_retval != PAM_SUCCESS)
-		fatal("PAM set rhost failed[%d]: %.200s", pam_retval,
-		    PAM_STRERROR(__pamh, pam_retval));
-#ifdef PAM_TTY_KLUDGE
-	/*
-	 * Some PAM modules (e.g. pam_time) require a TTY to operate,
-	 * and will fail in various stupid ways if they don't get one.
-	 * sshd doesn't set the tty until too late in the auth process and may
-	 * not even need one (for tty-less connections)
-	 * Kludge: Set a fake PAM_TTY
-	 */
-	pam_retval = pam_set_item(__pamh, PAM_TTY, "NODEVssh");
-	if (pam_retval != PAM_SUCCESS)
-		fatal("PAM set tty failed[%d]: %.200s",
-		    pam_retval, PAM_STRERROR(__pamh, pam_retval));
-#endif /* PAM_TTY_KLUDGE */
+void
+do_pam_session(const char *user, const char *tty)
+{
+	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 
+	    (const void *)&null_conv);
+	if (sshpam_err != PAM_SUCCESS)
+		fatal("PAM: failed to set PAM_CONV: %s",
+		    pam_strerror(sshpam_handle, sshpam_err));
+	debug("PAM: setting PAM_TTY to \"%s\"", tty);
+	sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
+	if (sshpam_err != PAM_SUCCESS)
+		fatal("PAM: failed to set PAM_TTY: %s",
+		    pam_strerror(sshpam_handle, sshpam_err));
+	sshpam_err = pam_open_session(sshpam_handle, 0);
+	if (sshpam_err != PAM_SUCCESS)
+		fatal("PAM: pam_open_session(): %s",
+		    pam_strerror(sshpam_handle, sshpam_err));
+	sshpam_session_open = 1;
+}
 
-	fatal_add_cleanup(&do_pam_cleanup_proc, NULL);
+void
+do_pam_setcred(int init)
+{
+	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+	    (const void *)&null_conv);
+	if (sshpam_err != PAM_SUCCESS)
+		fatal("PAM: failed to set PAM_CONV: %s",
+		    pam_strerror(sshpam_handle, sshpam_err));
+	if (init) {
+		debug("PAM: establishing credentials");
+		sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
+	} else {
+		debug("PAM: reinitializing credentials");
+		sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
+	}
+	if (sshpam_err == PAM_SUCCESS) {
+		sshpam_cred_established = 1;
+		return;
+	}
+	if (sshpam_authenticated)
+		fatal("PAM: pam_setcred(): %s",
+		    pam_strerror(sshpam_handle, sshpam_err));
+	else
+		debug("PAM: pam_setcred(): %s",
+		    pam_strerror(sshpam_handle, sshpam_err));
 }
 
-/* Return list of PAM environment strings */
-char **fetch_pam_environment(void)
+int
+is_pam_password_change_required(void)
 {
-#ifdef HAVE_PAM_GETENVLIST
-	return(pam_getenvlist(__pamh));
-#else /* HAVE_PAM_GETENVLIST */
-	return(NULL);
-#endif /* HAVE_PAM_GETENVLIST */
+	return (sshpam_new_authtok_reqd);
 }
 
-void free_pam_environment(char **env)
+static int
+pam_chauthtok_conv(int n,
+	 const struct pam_message **msg,
+	 struct pam_response **resp,
+	 void *data)
 {
+	char input[PAM_MAX_MSG_SIZE];
 	int i;
 
-	if (env != NULL) {
-		for (i = 0; env[i] != N