Prepare for using the "official" PAM support.
authorJoerg Sonnenberger <joerg@dragonflybsd.org>
Thu, 14 Jul 2005 13:10:21 +0000 (13:10 +0000)
committerJoerg Sonnenberger <joerg@dragonflybsd.org>
Thu, 14 Jul 2005 13:10:21 +0000 (13:10 +0000)
crypto/openssh-4/auth-pam.c [new file with mode: 0644]

diff --git a/crypto/openssh-4/auth-pam.c b/crypto/openssh-4/auth-pam.c
new file mode 100644 (file)
index 0000000..a8d372a
--- /dev/null
@@ -0,0 +1,1154 @@
+/*-
+ * 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
+ * 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 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.
+ */
+/*
+ * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
+ * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
+#include "includes.h"
+RCSID("$Id: auth-pam.c,v 1.122 2005/05/25 06:18:10 dtucker Exp $");
+
+#ifdef USE_PAM
+#if defined(HAVE_SECURITY_PAM_APPL_H)
+#include <security/pam_appl.h>
+#elif defined (HAVE_PAM_PAM_APPL_H)
+#include <pam/pam_appl.h>
+#endif
+
+#include "auth.h"
+#include "auth-pam.h"
+#include "buffer.h"
+#include "bufaux.h"
+#include "canohost.h"
+#include "log.h"
+#include "monitor_wrap.h"
+#include "msg.h"
+#include "packet.h"
+#include "misc.h"
+#include "servconf.h"
+#include "ssh2.h"
+#include "xmalloc.h"
+#include "auth-options.h"
+
+extern ServerOptions options;
+extern Buffer loginmsg;
+extern int compat20;
+extern u_int utmp_len;
+
+/* so we don't silently change behaviour */
+#ifdef USE_POSIX_THREADS
+# error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
+#endif
+
+/*
+ * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
+ * and generally a bad idea.  Use at own risk and do not expect support if
+ * this breaks.
+ */
+#ifdef UNSUPPORTED_POSIX_THREADS_HACK
+#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
+typedef pid_t sp_pthread_t;
+#endif
+
+struct pam_ctxt {
+       sp_pthread_t     pam_thread;
+       int              pam_psock;
+       int              pam_csock;
+       int              pam_done;
+};
+
+static void sshpam_free_ctx(void *);
+static struct pam_ctxt *cleanup_ctxt;
+
+#ifndef UNSUPPORTED_POSIX_THREADS_HACK
+/*
+ * Simulate threads with processes.
+ */
+
+static int sshpam_thread_status = -1;
+static mysig_t sshpam_oldsig;
+
+static void 
+sshpam_sigchld_handler(int sig)
+{
+       signal(SIGCHLD, SIG_DFL);
+       if (cleanup_ctxt == NULL)
+               return; /* handler called after PAM cleanup, shouldn't happen */
+       if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
+            <= 0) {
+               /* PAM thread has not exitted, privsep slave must have */
+               kill(cleanup_ctxt->pam_thread, SIGTERM);
+               if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
+                   <= 0)
+                       return; /* could not wait */
+       }
+       if (WIFSIGNALED(sshpam_thread_status) &&
+           WTERMSIG(sshpam_thread_status) == SIGTERM)
+               return; /* terminated by pthread_cancel */
+       if (!WIFEXITED(sshpam_thread_status))
+               fatal("PAM: authentication thread exited unexpectedly");
+       if (WEXITSTATUS(sshpam_thread_status) != 0)
+               fatal("PAM: authentication thread exited uncleanly");
+}
+
+static void
+pthread_exit(void *value __unused)
+{
+       _exit(0);
+}
+
+static int
+pthread_create(sp_pthread_t *thread, const void *attr __unused,
+    void *(*thread_start)(void *), void *arg)
+{
+       pid_t pid;
+
+       sshpam_thread_status = -1;
+       switch ((pid = fork())) {
+       case -1:
+               error("fork(): %s", strerror(errno));
+               return (-1);
+       case 0:
+               thread_start(arg);
+               _exit(1);
+       default:
+               *thread = pid;
+               sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
+               return (0);
+       }
+}
+
+static int
+pthread_cancel(sp_pthread_t thread)
+{
+       signal(SIGCHLD, sshpam_oldsig);
+       return (kill(thread, SIGTERM));
+}
+
+static int
+pthread_join(sp_pthread_t thread, void **value __unused)
+{
+       int status;
+
+       if (sshpam_thread_status != -1)
+               return (sshpam_thread_status);
+       signal(SIGCHLD, sshpam_oldsig);
+       waitpid(thread, &status, 0);
+       return (status);
+}
+#endif
+
+
+static pam_handle_t *sshpam_handle = NULL;
+static int sshpam_err = 0;
+static int sshpam_authenticated = 0;
+static int sshpam_session_open = 0;
+static int sshpam_cred_established = 0;
+static int sshpam_account_status = -1;
+static char **sshpam_env = NULL;
+static Authctxt *sshpam_authctxt = NULL;
+static const char *sshpam_password = NULL;
+static char badpw[] = "\b\n\r\177INCORRECT";
+
+/* Some PAM implementations don't implement this */
+#ifndef HAVE_PAM_GETENVLIST
+static char **
+pam_getenvlist(pam_handle_t *pamh)
+{
+       /*
+        * XXX - If necessary, we can still support envrionment passing
+        * for platforms without pam_getenvlist by searching for known
+        * env vars (e.g. KRB5CCNAME) from the PAM environment.
+        */
+        return NULL;
+}
+#endif
+
+/*
+ * Some platforms, notably Solaris, do not enforce password complexity
+ * rules during pam_chauthtok() if the real uid of the calling process
+ * is 0, on the assumption that it's being called by "passwd" run by root.
+ * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
+ * the right thing.
+ */
+#ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
+static int
+sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
+{
+       int result;
+
+       if (sshpam_authctxt == NULL)
+               fatal("PAM: sshpam_authctxt not initialized");
+       if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
+               fatal("%s: setreuid failed: %s", __func__, strerror(errno));
+       result = pam_chauthtok(pamh, flags);
+       if (setreuid(0, -1) == -1)
+               fatal("%s: setreuid failed: %s", __func__, strerror(errno));
+       return result;
+}
+# define pam_chauthtok(a,b)    (sshpam_chauthtok_ruid((a), (b)))
+#endif
+
+void
+sshpam_password_change_required(int reqd)
+{
+       debug3("%s %d", __func__, reqd);
+       if (sshpam_authctxt == NULL)
+               fatal("%s: PAM authctxt not initialized", __func__);
+       sshpam_authctxt->force_pwchange = reqd;
+       if (reqd) {
+               no_port_forwarding_flag |= 2;
+               no_agent_forwarding_flag |= 2;
+               no_x11_forwarding_flag |= 2;
+       } else {
+               no_port_forwarding_flag &= ~2;
+               no_agent_forwarding_flag &= ~2;
+               no_x11_forwarding_flag &= ~2;
+       }
+}
+
+/* Import regular and PAM environment from subprocess */
+static void
+import_environments(Buffer *b)
+{
+       char *env;
+       u_int i, num_env;
+       int err;
+
+       debug3("PAM: %s entering", __func__);
+
+#ifndef UNSUPPORTED_POSIX_THREADS_HACK
+       /* Import variables set by do_pam_account */
+       sshpam_account_status = buffer_get_int(b);
+       sshpam_password_change_required(buffer_get_int(b));
+
+       /* Import environment from subprocess */
+       num_env = buffer_get_int(b);
+       sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
+       debug3("PAM: num env strings %d", num_env);
+       for(i = 0; i < num_env; i++)
+               sshpam_env[i] = buffer_get_string(b, NULL);
+
+       sshpam_env[num_env] = NULL;
+
+       /* Import PAM environment from subprocess */
+       num_env = buffer_get_int(b);
+       debug("PAM: num PAM env strings %d", num_env);
+       for(i = 0; i < num_env; i++) {
+               env = buffer_get_string(b, NULL);
+
+#ifdef HAVE_PAM_PUTENV
+               /* Errors are not fatal here */
+               if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
+                       error("PAM: pam_putenv: %s",
+                           pam_strerror(sshpam_handle, sshpam_err));
+               }
+#endif
+       }
+#endif
+}
+
+/*
+ * Conversation function for authentication thread.
+ */
+static int
+sshpam_thread_conv(int n, struct pam_message **msg,
+    struct pam_response **resp, void *data)
+{
+       Buffer buffer;
+       struct pam_ctxt *ctxt;
+       struct pam_response *reply;
+       int i;
+
+       debug3("PAM: %s entering, %d messages", __func__, n);
+       *resp = NULL;
+
+       if (data == NULL) {
+               error("PAM: conversation function passed a null context");
+               return (PAM_CONV_ERR);
+       }
+       ctxt = data;
+       if (n <= 0 || n > PAM_MAX_NUM_MSG)
+               return (PAM_CONV_ERR);
+
+       if ((reply = malloc(n * sizeof(*reply))) == NULL)
+               return (PAM_CONV_ERR);
+       memset(reply, 0, n * sizeof(*reply));
+
+       buffer_init(&buffer);
+       for (i = 0; i < n; ++i) {
+               switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
+               case PAM_PROMPT_ECHO_OFF:
+                       buffer_put_cstring(&buffer,
+                           PAM_MSG_MEMBER(msg, i, msg));
+                       if (ssh_msg_send(ctxt->pam_csock,
+                           PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
+                               goto fail;
+                       if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
+                               goto fail;
+                       if (buffer_get_char(&buffer) != PAM_AUTHTOK)
+                               goto fail;
+                       reply[i].resp = buffer_get_string(&buffer, NULL);
+                       break;
+               case PAM_PROMPT_ECHO_ON:
+                       buffer_put_cstring(&buffer,
+                           PAM_MSG_MEMBER(msg, i, msg));
+                       if (ssh_msg_send(ctxt->pam_csock,
+                           PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
+                               goto fail;
+                       if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
+                               goto fail;
+                       if (buffer_get_char(&buffer) != PAM_AUTHTOK)
+                               goto fail;
+                       reply[i].resp = buffer_get_string(&buffer, NULL);
+                       break;
+               case PAM_ERROR_MSG:
+                       buffer_put_cstring(&buffer,
+                           PAM_MSG_MEMBER(msg, i, msg));
+                       if (ssh_msg_send(ctxt->pam_csock,
+                           PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
+                               goto fail;
+                       break;
+               case PAM_TEXT_INFO:
+                       buffer_put_cstring(&buffer,
+                           PAM_MSG_MEMBER(msg, i, msg));
+                       if (ssh_msg_send(ctxt->pam_csock,
+                           PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
+                               goto fail;
+                       break;
+               default:
+                       goto fail;
+               }
+               buffer_clear(&buffer);
+       }
+       buffer_free(&buffer);
+       *resp = reply;
+       return (PAM_SUCCESS);
+
+ fail:
+       for(i = 0; i < n; i++) {
+               if (reply[i].resp != NULL)
+                       xfree(reply[i].resp);
+       }
+       xfree(reply);
+       buffer_free(&buffer);
+       return (PAM_CONV_ERR);
+}
+
+/*
+ * Authentication thread.
+ */
+static void *
+sshpam_thread(void *ctxtp)
+{
+       struct pam_ctxt *ctxt = ctxtp;
+       Buffer buffer;
+       struct pam_conv sshpam_conv;
+       int flags = (options.permit_empty_passwd == 0 ?
+           PAM_DISALLOW_NULL_AUTHTOK : 0);
+#ifndef UNSUPPORTED_POSIX_THREADS_HACK
+       extern char **environ;
+       char **env_from_pam;
+       u_int i;
+       const char *pam_user;
+
+       pam_get_item(sshpam_handle, PAM_USER, (void **)&pam_user);
+       environ[0] = NULL;
+
+       if (sshpam_authctxt != NULL) {
+               setproctitle("%s [pam]",
+                   sshpam_authctxt->valid ? pam_user : "unknown");
+       }
+#endif
+
+       sshpam_conv.conv = sshpam_thread_conv;
+       sshpam_conv.appdata_ptr = ctxt;
+
+       if (sshpam_authctxt == NULL)
+               fatal("%s: PAM authctxt not initialized", __func__);
+
+       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, flags);
+       if (sshpam_err != PAM_SUCCESS)
+               goto auth_fail;
+
+       if (compat20) {
+               if (!do_pam_account())
+                       goto auth_fail;
+               if (sshpam_authctxt->force_pwchange) {
+                       sshpam_err = pam_chauthtok(sshpam_handle,
+                           PAM_CHANGE_EXPIRED_AUTHTOK);
+                       if (sshpam_err != PAM_SUCCESS)
+                               goto auth_fail;
+                       sshpam_password_change_required(0);
+               }
+       }
+
+       buffer_put_cstring(&buffer, "OK");
+
+#ifndef UNSUPPORTED_POSIX_THREADS_HACK
+       /* Export variables set by do_pam_account */
+       buffer_put_int(&buffer, sshpam_account_status);
+       buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
+
+       /* Export any environment strings set in child */
+       for(i = 0; environ[i] != NULL; i++)
+               ; /* Count */
+       buffer_put_int(&buffer, i);
+       for(i = 0; environ[i] != NULL; i++)
+               buffer_put_cstring(&buffer, environ[i]);
+
+       /* Export any environment strings set by PAM in child */
+       env_from_pam = pam_getenvlist(sshpam_handle);
+       for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
+               ; /* Count */
+       buffer_put_int(&buffer, i);
+       for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
+               buffer_put_cstring(&buffer, env_from_pam[i]);
+#endif /* UNSUPPORTED_POSIX_THREADS_HACK */
+
+       /* XXX - can't do much about an error here */
+       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));
+       /* XXX - can't do much about an error here */
+       ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
+       buffer_free(&buffer);
+       pthread_exit(NULL);
+
+       return (NULL); /* Avoid warning for non-pthread case */
+}
+
+void
+sshpam_thread_cleanup(void)
+{
+       struct pam_ctxt *ctxt = cleanup_ctxt;
+
+       debug3("PAM: %s entering", __func__);
+       if (ctxt != NULL && ctxt->pam_thread != 0) {
+               pthread_cancel(ctxt->pam_thread);
+               pthread_join(ctxt->pam_thread, NULL);
+               close(ctxt->pam_psock);
+               close(ctxt->pam_csock);
+               memset(ctxt, 0, sizeof(*ctxt));
+               cleanup_ctxt = NULL;
+       }
+}
+
+static int
+sshpam_null_conv(int n, struct pam_message **msg,
+    struct pam_response **resp, void *data)
+{
+       debug3("PAM: %s entering, %d messages", __func__, n);
+       return (PAM_CONV_ERR);
+}
+
+static struct pam_conv null_conv = { sshpam_null_conv, NULL };
+
+static int
+sshpam_store_conv(int n, struct pam_message **msg,
+    struct pam_response **resp, void *data)
+{
+       struct pam_response *reply;
+       int i;
+       size_t len;
+
+       debug3("PAM: %s called with %d messages", __func__, n);
+       *resp = NULL;
+
+       if (n <= 0 || n > PAM_MAX_NUM_MSG)
+               return (PAM_CONV_ERR);
+
+       if ((reply = malloc(n * sizeof(*reply))) == NULL)
+               return (PAM_CONV_ERR);
+       memset(reply, 0, n * sizeof(*reply));
+
+       for (i = 0; i < n; ++i) {
+               switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
+               case PAM_ERROR_MSG:
+               case PAM_TEXT_INFO:
+                       len = strlen(PAM_MSG_MEMBER(msg, i, msg));
+                       buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
+                       buffer_append(&loginmsg, "\n", 1 );
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               default:
+                       goto fail;
+               }
+       }
+       *resp = reply;
+       return (PAM_SUCCESS);
+
+ fail:
+       for(i = 0; i < n; i++) {
+               if (reply[i].resp != NULL)
+                       xfree(reply[i].resp);
+       }
+       xfree(reply);
+       return (PAM_CONV_ERR);
+}
+
+static struct pam_conv store_conv = { sshpam_store_conv, NULL };
+
+void
+sshpam_cleanup(void)
+{
+       debug("PAM: cleanup");
+       if (sshpam_handle == NULL)
+               return;
+       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 = 0;
+       pam_end(sshpam_handle, sshpam_err);
+       sshpam_handle = NULL;
+}
+
+static int
+sshpam_init(Authctxt *authctxt)
+{
+       extern char *__progname;
+       const char *pam_rhost, *pam_user, *user = authctxt->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, (void **)&pam_user);
+               if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
+                       return (0);
+               pam_end(sshpam_handle, sshpam_err);
+               sshpam_handle = NULL;
+       }
+       debug("PAM: initializing for \"%s\"", user);
+       sshpam_err =
+           pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
+       sshpam_authctxt = authctxt;
+
+       if (sshpam_err != PAM_SUCCESS) {
+               pam_end(sshpam_handle, sshpam_err);
+               sshpam_handle = NULL;
+               return (-1);
+       }
+       pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
+       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);
+       }
+#ifdef PAM_TTY_KLUDGE
+       /*
+        * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
+        * sshd doesn't set the tty until too late in the auth process and
+        * may not even set one (for tty-less connections)
+        */
+       debug("PAM: setting PAM_TTY to \"ssh\"");
+       sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
+       if (sshpam_err != PAM_SUCCESS) {
+               pam_end(sshpam_handle, sshpam_err);
+               sshpam_handle = NULL;
+               return (-1);
+       }
+#endif
+       return (0);
+}
+
+static void *
+sshpam_init_ctx(Authctxt *authctxt)
+{
+       struct pam_ctxt *ctxt;
+       int socks[2];
+
+       debug3("PAM: %s entering", __func__);
+       /* Refuse to start if we don't have PAM enabled */
+       if (!options.use_pam)
+               return NULL;
+
+       /* Initialize PAM */
+       if (sshpam_init(authctxt) == -1) {
+               error("PAM: initialization failed");
+               return (NULL);
+       }
+
+       ctxt = xmalloc(sizeof *ctxt);
+       memset(ctxt, 0, sizeof(*ctxt));
+
+       /* 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);
+       }
+       cleanup_ctxt = ctxt;
+       return (ctxt);
+}
+
+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;
+       size_t len, mlen;
+
+       debug3("PAM: %s entering", __func__);
+       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);
+               mlen = strlen(msg);
+               switch (type) {
+               case PAM_PROMPT_ECHO_ON:
+               case PAM_PROMPT_ECHO_OFF:
+                       *num = 1;
+                       len = plen + mlen + 1;
+                       **prompts = xrealloc(**prompts, len);
+                       strlcpy(**prompts + plen, msg, len - plen);
+                       plen += mlen;
+                       **echo_on = (type == PAM_PROMPT_ECHO_ON);
+                       xfree(msg);
+                       return (0);
+               case PAM_ERROR_MSG:
+               case PAM_TEXT_INFO:
+                       /* accumulate messages */
+                       len = plen + mlen + 2;
+                       **prompts = xrealloc(**prompts, len);
+                       strlcpy(**prompts + plen, msg, len - plen);
+                       plen += mlen;
+                       strlcat(**prompts + plen, "\n", len - plen);
+                       plen++;
+                       xfree(msg);
+                       break;
+               case PAM_SUCCESS:
+               case PAM_AUTH_ERR:
+                       if (**prompts != NULL) {
+                               /* drain any accumulated messages */
+                               debug("PAM: %s", **prompts);
+                               buffer_append(&loginmsg, **prompts,
+                                   strlen(**prompts));
+                               xfree(**prompts);
+                               **prompts = NULL;
+                       }
+                       if (type == PAM_SUCCESS) {
+                               if (!sshpam_authctxt->valid ||
+                                   (sshpam_authctxt->pw->pw_uid == 0 &&
+                                   options.permit_root_login != PERMIT_YES))
+                                       fatal("Internal error: PAM auth "
+                                           "succeeded when it should have "
+                                           "failed");
+                               import_environments(&buffer);
+                               *num = 0;
+                               **echo_on = 0;
+                               ctxt->pam_done = 1;
+                               xfree(msg);
+                               return (0);
+                       }
+                       error("PAM: %s for %s%.100s from %.100s", msg,
+                           sshpam_authctxt->valid ? "" : "illegal user ",
+                           sshpam_authctxt->user,
+                           get_remote_name_or_ip(utmp_len, options.use_dns));
+                       /* FALLTHROUGH */
+               default:
+                       *num = 0;
+                       **echo_on = 0;
+                       xfree(msg);
+                       ctxt->pam_done = -1;
+                       return (-1);
+               }
+       }
+       return (-1);
+}
+
+/* XXX - see also comment in auth-chall.c:verify_response */
+static int
+sshpam_respond(void *ctx, u_int num, char **resp)
+{
+       Buffer buffer;
+       struct pam_ctxt *ctxt = ctx;
+
+       debug2("PAM: %s entering, %d responses", __func__, num);
+       switch (ctxt->pam_done) {
+       case 1:
+               sshpam_authenticated = 1;
+               return (0);
+       case 0:
+               break;
+       default:
+               return (-1);
+       }
+       if (num != 1) {
+               error("PAM: expected one response, got %u", num);
+               return (-1);
+       }
+       buffer_init(&buffer);
+       if (sshpam_authctxt->valid &&
+           (sshpam_authctxt->pw->pw_uid != 0 ||
+            options.permit_root_login == PERMIT_YES))
+               buffer_put_cstring(&buffer, *resp);
+       else
+               buffer_put_cstring(&buffer, badpw);
+       if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
+               buffer_free(&buffer);
+               return (-1);
+       }
+       buffer_free(&buffer);
+       return (1);
+}
+
+static void
+sshpam_free_ctx(void *ctxtp)
+{
+       struct pam_ctxt *ctxt = ctxtp;
+
+       debug3("PAM: %s entering", __func__);
+       sshpam_thread_cleanup();
+       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.
+        */
+}
+
+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
+};
+
+/*
+ * This replaces auth-pam.c
+ */
+void
+start_pam(Authctxt *authctxt)
+{
+       if (!options.use_pam)
+               fatal("PAM: initialisation requested when UsePAM=no");
+
+       if (sshpam_init(authctxt) == -1)
+               fatal("PAM: initialisation failed");
+}
+
+void
+finish_pam(void)
+{
+       sshpam_cleanup();
+}
+
+u_int
+do_pam_account(void)
+{
+       debug("%s: called", __func__);
+       if (sshpam_account_status != -1)
+               return (sshpam_account_status);
+
+       sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
+       debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
+           pam_strerror(sshpam_handle, sshpam_err));
+       
+       if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
+               sshpam_account_status = 0;
+               return (sshpam_account_status);
+       }
+
+       if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
+               sshpam_password_change_required(1);
+
+       sshpam_account_status = 1;
+       return (sshpam_account_status);
+}
+
+void
+do_pam_set_tty(const char *tty)
+{
+       if (tty != NULL) {
+               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));
+       }
+}
+
+void
+do_pam_setcred(int init)
+{
+       sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+           (const void *)&store_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));
+}
+
+static int
+sshpam_tty_conv(int n, struct pam_message **msg,
+    struct pam_response **resp, void *data)
+{
+       char input[PAM_MAX_MSG_SIZE];
+       struct pam_response *reply;
+       int i;
+
+       debug3("PAM: %s called with %d messages", __func__, n);
+
+       *resp = NULL;
+
+       if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
+               return (PAM_CONV_ERR);
+
+       if ((reply = malloc(n * sizeof(*reply))) == NULL)
+               return (PAM_CONV_ERR);
+       memset(reply, 0, n * sizeof(*reply));
+
+       for (i = 0; i < n; ++i) {
+               switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
+               case PAM_PROMPT_ECHO_OFF:
+                       reply[i].resp =
+                           read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
+                           RP_ALLOW_STDIN);
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               case PAM_PROMPT_ECHO_ON:
+                       fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
+                       fgets(input, sizeof input, stdin);
+                       if ((reply[i].resp = strdup(input)) == NULL)
+                               goto fail;
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               case PAM_ERROR_MSG:
+               case PAM_TEXT_INFO:
+                       fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               default:
+                       goto fail;
+               }
+       }
+       *resp = reply;
+       return (PAM_SUCCESS);
+
+ fail:
+       for(i = 0; i < n; i++) {
+               if (reply[i].resp != NULL)
+                       xfree(reply[i].resp);
+       }
+       xfree(reply);
+       return (PAM_CONV_ERR);
+}
+
+static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
+
+/*
+ * XXX this should be done in the authentication phase, but ssh1 doesn't
+ * support that
+ */
+void
+do_pam_chauthtok(void)
+{
+       if (use_privsep)
+               fatal("Password expired (unable to change with privsep)");
+       sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+           (const void *)&tty_conv);
+       if (sshpam_err != PAM_SUCCESS)
+               fatal("PAM: failed to set PAM_CONV: %s",
+                   pam_strerror(sshpam_handle, sshpam_err));
+       debug("PAM: changing password");
+       sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
+       if (sshpam_err != PAM_SUCCESS)
+               fatal("PAM: pam_chauthtok(): %s",
+                   pam_strerror(sshpam_handle, sshpam_err));
+}
+
+void
+do_pam_session(void)
+{
+       debug3("PAM: opening session");
+       sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+           (const void *)&store_conv);
+       if (sshpam_err != PAM_SUCCESS)
+               fatal("PAM: failed to set PAM_CONV: %s",
+                   pam_strerror(sshpam_handle, sshpam_err));
+       sshpam_err = pam_open_session(sshpam_handle, 0);
+       if (sshpam_err == PAM_SUCCESS)
+               sshpam_session_open = 1;
+       else {
+               sshpam_session_open = 0;
+               disable_forwarding();
+               error("PAM: pam_open_session(): %s",
+                   pam_strerror(sshpam_handle, sshpam_err));
+       }
+
+}
+
+int
+is_pam_session_open(void)
+{
+       return sshpam_session_open;
+}
+
+/*
+ * Set a PAM environment string. We need to do this so that the session
+ * modules can handle things like Kerberos/GSI credentials that appear
+ * during the ssh authentication process.
+ */
+int
+do_pam_putenv(char *name, char *value)
+{
+       int ret = 1;
+#ifdef HAVE_PAM_PUTENV
+       char *compound;
+       size_t len;
+
+       len = strlen(name) + strlen(value) + 2;
+       compound = xmalloc(len);
+
+       snprintf(compound, len, "%s=%s", name, value);
+       ret = pam_putenv(sshpam_handle, compound);
+       xfree(compound);
+#endif
+
+       return (ret);
+}
+
+char **
+fetch_pam_child_environment(void)
+{
+       return sshpam_env;
+}
+
+char **
+fetch_pam_environment(void)
+{
+       return (pam_getenvlist(sshpam_handle));
+}
+
+void
+free_pam_environment(char **env)
+{
+       char **envp;
+
+       if (env == NULL)
+               return;
+
+       for (envp = env; *envp; envp++)
+               xfree(*envp);
+       xfree(env);
+}
+
+/*
+ * "Blind" conversation function for password authentication.  Assumes that
+ * echo-off prompts are for the password and stores messages for later
+ * display.
+ */
+static int
+sshpam_passwd_conv(int n, struct pam_message **msg,
+    struct pam_response **resp, void *data)
+{
+       struct pam_response *reply;
+       int i;
+       size_t len;
+
+       debug3("PAM: %s called with %d messages", __func__, n);
+
+       *resp = NULL;
+
+       if (n <= 0 || n > PAM_MAX_NUM_MSG)
+               return (PAM_CONV_ERR);
+
+       if ((reply = malloc(n * sizeof(*reply))) == NULL)
+               return (PAM_CONV_ERR);
+       memset(reply, 0, n * sizeof(*reply));
+
+       for (i = 0; i < n; ++i) {
+               switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
+               case PAM_PROMPT_ECHO_OFF:
+                       if (sshpam_password == NULL)
+                               goto fail;
+                       if ((reply[i].resp = strdup(sshpam_password)) == NULL)
+                               goto fail;
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               case PAM_ERROR_MSG:
+               case PAM_TEXT_INFO:
+                       len = strlen(PAM_MSG_MEMBER(msg, i, msg));
+                       if (len > 0) {
+                               buffer_append(&loginmsg,
+                                   PAM_MSG_MEMBER(msg, i, msg), len);
+                               buffer_append(&loginmsg, "\n", 1);
+                       }
+                       if ((reply[i].resp = strdup("")) == NULL)
+                               goto fail;
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               default:
+                       goto fail;
+               }
+       }
+       *resp = reply;
+       return (PAM_SUCCESS);
+
+ fail: 
+       for(i = 0; i < n; i++) {
+               if (reply[i].resp != NULL)
+                       xfree(reply[i].resp);
+       }
+       xfree(reply);
+       return (PAM_CONV_ERR);
+}
+
+static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
+
+/*
+ * Attempt password authentication via PAM
+ */
+int
+sshpam_auth_passwd(Authctxt *authctxt, const char *password)
+{
+       int flags = (options.permit_empty_passwd == 0 ?
+           PAM_DISALLOW_NULL_AUTHTOK : 0);
+
+       if (!options.use_pam || sshpam_handle == NULL)
+               fatal("PAM: %s called when PAM disabled or failed to "
+                   "initialise.", __func__);
+
+       sshpam_password = password;
+       sshpam_authctxt = authctxt;
+
+       /*
+        * If the user logging in is invalid, or is root but is not permitted
+        * by PermitRootLogin, use an invalid password to prevent leaking
+        * information via timing (eg if the PAM config has a delay on fail).
+        */
+       if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
+            options.permit_root_login != PERMIT_YES))
+               sshpam_password = badpw;
+
+       sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+           (const void *)&passwd_conv);
+       if (sshpam_err != PAM_SUCCESS)
+               fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
+                   pam_strerror(sshpam_handle, sshpam_err));
+
+       sshpam_err = pam_authenticate(sshpam_handle, flags);
+       sshpam_password = NULL;
+       if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
+               debug("PAM: password authentication accepted for %.100s",
+                   authctxt->user);
+               return 1;
+       } else {
+               debug("PAM: password authentication failed for %.100s: %s",
+                   authctxt->valid ? authctxt->user : "an illegal user",
+                   pam_strerror(sshpam_handle, sshpam_err));
+               return 0;
+       }
+}
+#endif /* USE_PAM */