Revert part of 180714 - the intent was to flatten dist, not to nuke it.

1 files changed, 2510 insertions, 0 deletions

diff --git a/crypto/openssh/session.c b/crypto/openssh/session.c
new file mode 100644
index 0000000..69153ad
--- /dev/null
+++ b/crypto/openssh/session.c
@@ -0,0 +1,2510 @@
+/* $OpenBSD: session.c,v 1.220 2006/10/09 23:36:11 djm Exp $ */
+/*
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ *
+ * SSH2 support by Markus Friedl.
+ * Copyright (c) 2000, 2001 Markus Friedl.  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/param.h>
+#ifdef HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/wait.h>
+
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <grp.h>
+#ifdef HAVE_PATHS_H
+#include <paths.h>
+#endif
+#include <pwd.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "ssh1.h"
+#include "ssh2.h"
+#include "sshpty.h"
+#include "packet.h"
+#include "buffer.h"
+#include "match.h"
+#include "uidswap.h"
+#include "compat.h"
+#include "channels.h"
+#include "key.h"
+#include "cipher.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "hostfile.h"
+#include "auth.h"
+#include "auth-options.h"
+#include "pathnames.h"
+#include "log.h"
+#include "servconf.h"
+#include "sshlogin.h"
+#include "serverloop.h"
+#include "canohost.h"
+#include "session.h"
+#include "kex.h"
+#include "monitor_wrap.h"
+
+#if defined(KRB5) && defined(USE_AFS)
+#include <kafs.h>
+#endif
+
+/* func */
+
+Session *session_new(void);
+void	session_set_fds(Session *, int, int, int);
+void	session_pty_cleanup(Session *);
+void	session_proctitle(Session *);
+int	session_setup_x11fwd(Session *);
+void	do_exec_pty(Session *, const char *);
+void	do_exec_no_pty(Session *, const char *);
+void	do_exec(Session *, const char *);
+void	do_login(Session *, const char *);
+#ifdef LOGIN_NEEDS_UTMPX
+static void	do_pre_login(Session *s);
+#endif
+void	do_child(Session *, const char *);
+void	do_motd(void);
+int	check_quietlogin(Session *, const char *);
+
+static void do_authenticated1(Authctxt *);
+static void do_authenticated2(Authctxt *);
+
+static int session_pty_req(Session *);
+
+/* import */
+extern ServerOptions options;
+extern char *__progname;
+extern int log_stderr;
+extern int debug_flag;
+extern u_int utmp_len;
+extern int startup_pipe;
+extern void destroy_sensitive_data(void);
+extern Buffer loginmsg;
+
+/* original command from peer. */
+const char *original_command = NULL;
+
+/* data */
+#define MAX_SESSIONS 10
+Session	sessions[MAX_SESSIONS];
+
+#ifdef HAVE_LOGIN_CAP
+login_cap_t *lc;
+#endif
+
+static int is_child = 0;
+
+/* Name and directory of socket for authentication agent forwarding. */
+static char *auth_sock_name = NULL;
+static char *auth_sock_dir = NULL;
+
+/* removes the agent forwarding socket */
+
+static void
+auth_sock_cleanup_proc(struct passwd *pw)
+{
+	if (auth_sock_name != NULL) {
+		temporarily_use_uid(pw);
+		unlink(auth_sock_name);
+		rmdir(auth_sock_dir);
+		auth_sock_name = NULL;
+		restore_uid();
+	}
+}
+
+static int
+auth_input_request_forwarding(struct passwd * pw)
+{
+	Channel *nc;
+	int sock;
+	struct sockaddr_un sunaddr;
+
+	if (auth_sock_name != NULL) {
+		error("authentication forwarding requested twice.");
+		return 0;
+	}
+
+	/* Temporarily drop privileged uid for mkdir/bind. */
+	temporarily_use_uid(pw);
+
+	/* Allocate a buffer for the socket name, and format the name. */
+	auth_sock_name = xmalloc(MAXPATHLEN);
+	auth_sock_dir = xmalloc(MAXPATHLEN);
+	strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
+
+	/* Create private directory for socket */
+	if (mkdtemp(auth_sock_dir) == NULL) {
+		packet_send_debug("Agent forwarding disabled: "
+		    "mkdtemp() failed: %.100s", strerror(errno));
+		restore_uid();
+		xfree(auth_sock_name);
+		xfree(auth_sock_dir);
+		auth_sock_name = NULL;
+		auth_sock_dir = NULL;
+		return 0;
+	}
+	snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld",
+		 auth_sock_dir, (long) getpid());
+
+	/* Create the socket. */
+	sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (sock < 0)
+		packet_disconnect("socket: %.100s", strerror(errno));
+
+	/* Bind it to the name. */
+	memset(&sunaddr, 0, sizeof(sunaddr));
+	sunaddr.sun_family = AF_UNIX;
+	strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path));
+
+	if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0)
+		packet_disconnect("bind: %.100s", strerror(errno));
+
+	/* Restore the privileged uid. */
+	restore_uid();
+
+	/* Start listening on the socket. */
+	if (listen(sock, SSH_LISTEN_BACKLOG) < 0)
+		packet_disconnect("listen: %.100s", strerror(errno));
+
+	/* Allocate a channel for the authentication agent socket. */
+	nc = channel_new("auth socket",
+	    SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
+	    CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
+	    0, "auth socket", 1);
+	strlcpy(nc->path, auth_sock_name, sizeof(nc->path));
+	return 1;
+}
+
+static void
+display_loginmsg(void)
+{
+	if (buffer_len(&loginmsg) > 0) {
+		buffer_append(&loginmsg, "\0", 1);
+		printf("%s", (char *)buffer_ptr(&loginmsg));
+		buffer_clear(&loginmsg);
+	}
+}
+
+void
+do_authenticated(Authctxt *authctxt)
+{
+	setproctitle("%s", authctxt->pw->pw_name);
+
+	/* setup the channel layer */
+	if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
+		channel_permit_all_opens();
+
+	if (compat20)
+		do_authenticated2(authctxt);
+	else
+		do_authenticated1(authctxt);
+
+	do_cleanup(authctxt);
+}
+
+/*
+ * Prepares for an interactive session.  This is called after the user has
+ * been successfully authenticated.  During this message exchange, pseudo
+ * terminals are allocated, X11, TCP/IP, and authentication agent forwardings
+ * are requested, etc.
+ */
+static void
+do_authenticated1(Authctxt *authctxt)
+{
+	Session *s;
+	char *command;
+	int success, type, screen_flag;
+	int enable_compression_after_reply = 0;
+	u_int proto_len, data_len, dlen, compression_level = 0;
+
+	s = session_new();
+	if (s == NULL) {
+		error("no more sessions");
+		return;
+	}
+	s->authctxt = authctxt;
+	s->pw = authctxt->pw;
+
+	/*
+	 * We stay in this loop until the client requests to execute a shell
+	 * or a command.
+	 */
+	for (;;) {
+		success = 0;
+
+		/* Get a packet from the client. */
+		type = packet_read();
+
+		/* Process the packet. */
+		switch (type) {
+		case SSH_CMSG_REQUEST_COMPRESSION:
+			compression_level = packet_get_int();
+			packet_check_eom();
+			if (compression_level < 1 || compression_level > 9) {
+				packet_send_debug("Received invalid compression level %d.",
+				    compression_level);
+				break;
+			}
+			if (options.compression == COMP_NONE) {
+				debug2("compression disabled");
+				break;
+			}
+			/* Enable compression after we have responded with SUCCESS. */
+			enable_compression_after_reply = 1;
+			success = 1;
+			break;
+
+		case SSH_CMSG_REQUEST_PTY:
+			success = session_pty_req(s);
+			break;
+
+		case SSH_CMSG_X11_REQUEST_FORWARDING:
+			s->auth_proto = packet_get_string(&proto_len);
+			s->auth_data = packet_get_string(&data_len);
+
+			screen_flag = packet_get_protocol_flags() &
+			    SSH_PROTOFLAG_SCREEN_NUMBER;
+			debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag);
+
+			if (packet_remaining() == 4) {
+				if (!screen_flag)
+					debug2("Buggy client: "
+					    "X11 screen flag missing");
+				s->screen = packet_get_int();
+			} else {
+				s->screen = 0;
+			}
+			packet_check_eom();
+			success = session_setup_x11fwd(s);
+			if (!success) {
+				xfree(s->auth_proto);
+				xfree(s->auth_data);
+				s->auth_proto = NULL;
+				s->auth_data = NULL;
+			}
+			break;
+
+		case SSH_CMSG_AGENT_REQUEST_FORWARDING:
+			if (no_agent_forwarding_flag || compat13) {
+				debug("Authentication agent forwarding not permitted for this authentication.");
+				break;
+			}
+			debug("Received authentication agent forwarding request.");
+			success = auth_input_request_forwarding(s->pw);
+			break;
+
+		case SSH_CMSG_PORT_FORWARD_REQUEST:
+			if (no_port_forwarding_flag) {
+				debug("Port forwarding not permitted for this authentication.");
+				break;
+			}
+			if (!options.allow_tcp_forwarding) {
+				debug("Port forwarding not permitted.");
+				break;
+			}
+			debug("Received TCP/IP port forwarding request.");
+			if (channel_input_port_forward_request(s->pw->pw_uid == 0,
+			    options.gateway_ports) < 0) {
+				debug("Port forwarding failed.");
+				break;
+			}
+			success = 1;
+			break;
+
+		case SSH_CMSG_MAX_PACKET_SIZE:
+			if (packet_set_maxsize(packet_get_int()) > 0)
+				success = 1;
+			break;
+
+		case SSH_CMSG_EXEC_SHELL:
+		case SSH_CMSG_EXEC_CMD:
+			if (type == SSH_CMSG_EXEC_CMD) {
+				command = packet_get_string(&dlen);
+				debug("Exec command '%.500s'", command);
+				do_exec(s, command);
+				xfree(command);
+			} else {
+				do_exec(s, NULL);
+			}
+			packet_check_eom();
+			session_close(s);
+			return;
+
+		default:
+			/*
+			 * Any unknown messages in this phase are ignored,
+			 * and a failure message is returned.
+			 */
+			logit("Unknown packet type received after authentication: %d", type);
+		}
+		packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
+		packet_send();
+		packet_write_wait();
+
+		/* Enable compression now that we have replied if appropriate. */
+		if (enable_compression_after_reply) {
+			enable_compression_after_reply = 0;
+			packet_start_compression(compression_level);
+		}
+	}
+}
+
+/*
+ * This is called to fork and execute a command when we have no tty.  This
+ * will call do_child from the child, and server_loop from the parent after
+ * setting up file descriptors and such.
+ */
+void
+do_exec_no_pty(Session *s, const char *command)
+{
+	pid_t pid;
+
+#ifdef USE_PIPES
+	int pin[2], pout[2], perr[2];
+	/* Allocate pipes for communicating with the program. */
+	if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0)
+		packet_disconnect("Could not create pipes: %.100s",
+				  strerror(errno));
+#else /* USE_PIPES */
+	int inout[2], err[2];
+	/* Uses socket pairs to communicate with the program. */
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 ||
+	    socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0)
+		packet_disconnect("Could not create socket pairs: %.100s",
+				  strerror(errno));
+#endif /* USE_PIPES */
+	if (s == NULL)
+		fatal("do_exec_no_pty: no session");
+
+	session_proctitle(s);
+
+#if defined(USE_PAM)
+	if (options.use_pam && !use_privsep)
+		do_pam_setcred(1);
+#endif /* USE_PAM */
+
+	/* Fork the child. */
+	if ((pid = fork()) == 0) {
+		is_child = 1;
+
+		/* Child.  Reinitialize the log since the pid has changed. */
+		log_init(__progname, options.log_level, options.log_facility, log_stderr);
+
+		/*
+		 * Create a new session and process group since the 4.4BSD
+		 * setlogin() affects the entire process group.
+		 */
+		if (setsid() < 0)
+			error("setsid failed: %.100s", strerror(errno));
+
+#ifdef USE_PIPES
+		/*
+		 * Redirect stdin.  We close the parent side of the socket
+		 * pair, and make the child side the standard input.
+		 */
+		close(pin[1]);
+		if (dup2(pin[0], 0) < 0)
+			perror("dup2 stdin");
+		close(pin[0]);
+
+		/* Redirect stdout. */
+		close(pout[0]);
+		if (dup2(pout[1], 1) < 0)
+			perror("dup2 stdout");
+		close(pout[1]);
+
+		/* Redirect stderr. */
+		close(perr[0]);
+		if (dup2(perr[1], 2) < 0)
+			perror("dup2 stderr");
+		close(perr[1]);
+#else /* USE_PIPES */
+		/*
+		 * Redirect stdin, stdout, and stderr.  Stdin and stdout will
+		 * use the same socket, as some programs (particularly rdist)
+		 * seem to depend on it.
+		 */
+		close(inout[1]);
+		close(err[1]);
+		if (dup2(inout[0], 0) < 0)	/* stdin */
+			perror("dup2 stdin");
+		if (dup2(inout[0], 1) < 0)	/* stdout.  Note: same socket as stdin. */
+			perror("dup2 stdout");
+		if (dup2(err[0], 2) < 0)	/* stderr */
+			perror("dup2 stderr");
+#endif /* USE_PIPES */
+
+#ifdef _UNICOS
+		cray_init_job(s->pw); /* set up cray jid and tmpdir */
+#endif
+
+		/* Do processing for the child (exec command etc). */
+		do_child(s, command);
+		/* NOTREACHED */
+	}
+#ifdef _UNICOS
+	signal(WJSIGNAL, cray_job_termination_handler);
+#endif /* _UNICOS */
+#ifdef HAVE_CYGWIN
+	if (is_winnt)
+		cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
+#endif
+	if (pid < 0)
+		packet_disconnect("fork failed: %.100s", strerror(errno));
+	s->pid = pid;
+	/* Set interactive/non-interactive mode. */
+	packet_set_interactive(s->display != NULL);
+#ifdef USE_PIPES
+	/* We are the parent.  Close the child sides of the pipes. */
+	close(pin[0]);
+	close(pout[1]);
+	close(perr[1]);
+
+	if (compat20) {
+		if (s->is_subsystem) {
+			close(perr[0]);
+			perr[0] = -1;
+		}
+		session_set_fds(s, pin[1], pout[0], perr[0]);
+	} else {
+		/* Enter the interactive session. */
+		server_loop(pid, pin[1], pout[0], perr[0]);
+		/* server_loop has closed pin[1], pout[0], and perr[0]. */
+	}
+#else /* USE_PIPES */
+	/* We are the parent.  Close the child sides of the socket pairs. */
+	close(inout[0]);
+	close(err[0]);
+
+	/*
+	 * Clear loginmsg, since it's the child's responsibility to display
+	 * it to the user, otherwise multiple sessions may accumulate
+	 * multiple copies of the login messages.
+	 */
+	buffer_clear(&loginmsg);
+
+	/*
+	 * Enter the interactive session.  Note: server_loop must be able to
+	 * handle the case that fdin and fdout are the same.
+	 */
+	if (compat20) {
+		session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]);
+	} else {
+		server_loop(pid, inout[1], inout[1], err[1]);
+		/* server_loop has closed inout[1] and err[1]. */
+	}
+#endif /* USE_PIPES */
+}
+
+/*
+ * This is called to fork and execute a command when we have a tty.  This
+ * will call do_child from the child, and server_loop from the parent after
+ * setting up file descriptors, controlling tty, updating wtmp, utmp,
+ * lastlog, and other such operations.
+ */
+void
+do_exec_pty(Session *s, const char *command)
+{
+	int fdout, ptyfd, ttyfd, ptymaster;
+	pid_t pid;
+
+	if (s == NULL)
+		fatal("do_exec_pty: no session");
+	ptyfd = s->ptyfd;
+	ttyfd = s->ttyfd;
+
+#if defined(USE_PAM)
+	if (options.use_pam) {
+		do_pam_set_tty(s->tty);
+		if (!use_privsep)
+			do_pam_setcred(1);
+	}
+#endif
+
+	/* Fork the child. */
+	if ((pid = fork()) == 0) {
+		is_child = 1;
+
+		/* Child.  Reinitialize the log because the pid has changed. */
+		log_init(__progname, options.log_level, options.log_facility, log_stderr);
+		/* Close the master side of the pseudo tty. */
+		close(ptyfd);
+
+		/* Make the pseudo tty our controlling tty. */
+		pty_make_controlling_tty(&ttyfd, s->tty);
+
+		/* Redirect stdin/stdout/stderr from the pseudo tty. */
+		if (dup2(ttyfd, 0) < 0)
+			error("dup2 stdin: %s", strerror(errno));
+		if (dup2(ttyfd, 1) < 0)
+			error("dup2 stdout: %s", strerror(errno));
+		if (dup2(ttyfd, 2) < 0)
+			error("dup2 stderr: %s", strerror(errno));
+
+		/* Close the extra descriptor for the pseudo tty. */
+		close(ttyfd);
+
+		/* record login, etc. similar to login(1) */
+#ifndef HAVE_OSF_SIA
+		if (!(options.use_login && command == NULL)) {
+#ifdef _UNICOS
+			cray_init_job(s->pw); /* set up cray jid and tmpdir */
+#endif /* _UNICOS */
+			do_login(s, command);
+		}
+# ifdef LOGIN_NEEDS_UTMPX
+		else
+			do_pre_login(s);
+# endif
+#endif
+
+		/* Do common processing for the child, such as execing the command. */
+		do_child(s, command);
+		/* NOTREACHED */
+	}
+#ifdef _UNICOS
+	signal(WJSIGNAL, cray_job_termination_handler);
+#endif /* _UNICOS */
+#ifdef HAVE_CYGWIN
+	if (is_winnt)
+		cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
+#endif
+	if (pid < 0)
+		packet_disconnect("fork failed: %.100s", strerror(errno));
+	s->pid = pid;
+
+	/* Parent.  Close the slave side of the pseudo tty. */
+	close(ttyfd);
+
+	/*
+	 * Create another descriptor of the pty master side for use as the
+	 * standard input.  We could use the original descriptor, but this
+	 * simplifies code in server_loop.  The descriptor is bidirectional.
+	 */
+	fdout = dup(ptyfd);
+	if (fdout < 0)
+		packet_disconnect("dup #1 failed: %.100s", strerror(errno));
+
+	/* we keep a reference to the pty master */
+	ptymaster = dup(ptyfd);
+	if (ptymaster < 0)
+		packet_disconnect("dup #2 failed: %.100s", strerror(errno));
+	s->ptymaster = ptymaster;
+
+	/* Enter interactive session. */
+	packet_set_interactive(1);
+	if (compat20) {
+		session_set_fds(s, ptyfd, fdout, -1);
+	} else {
+		server_loop(pid, ptyfd, fdout, -1);
+		/* server_loop _has_ closed ptyfd and fdout. */
+	}
+}
+
+#ifdef LOGIN_NEEDS_UTMPX
+static void
+do_pre_login(Session *s)
+{
+	socklen_t fromlen;
+	struct sockaddr_storage from;
+	pid_t pid = getpid();
+
+	/*
+	 * 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_utmp_only(pid, s->tty, s->pw->pw_name,
+	    get_remote_name_or_ip(utmp_len, options.use_dns),
+	    (struct sockaddr *)&from, fromlen);
+}
+#endif
+
+/*
+ * This is called to fork and execute a command.  If another command is
+ * to be forced, execute that instead.
+ */
+void
+do_exec(Session *s, const char *command)
+{
+	if (options.adm_forced_command) {
+		original_command = command;
+		command = options.adm_forced_command;
+		debug("Forced command (config) '%.900s'", command);
+	} else if (forced_command) {
+		original_command = command;
+		command = forced_command;
+		debug("Forced command (key option) '%.900s'", command);
+	}
+
+#ifdef SSH_AUDIT_EVENTS
+	if (command != NULL)
+		PRIVSEP(audit_run_command(command));
+	else if (s->ttyfd == -1) {
+		char *shell = s->pw->pw_shell;
+
+		if (shell[0] == '\0')	/* empty shell means /bin/sh */
+			shell =_PATH_BSHELL;
+		PRIVSEP(audit_run_command(shell));
+	}
+#endif
+
+	if (s->ttyfd != -1)
+		do_exec_pty(s, command);
+	else
+		do_exec_no_pty(s, command);
+
+	original_command = NULL;
+
+	/*
+	 * Clear loginmsg: it's the child's responsibility to display
+	 * it to the user, otherwise multiple sessions may accumulate
+	 * multiple copies of the login messages.
+	 */
+	buffer_clear(&loginmsg);
+}
+
+/* administrative, login(1)-like work */
+void
+do_login(Session *s, const char *command)
+{
+	socklen_t fromlen;
+	struct sockaddr_storage from;
+	struct passwd * pw = s->pw;
+	pid_t pid = getpid();
+
+	/*
+	 * 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. */
+	if (!use_privsep)
+		record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
+		    get_remote_name_or_ip(utmp_len,
+		    options.use_dns),
+		    (struct sockaddr *)&from, fromlen);
+
+#ifdef USE_PAM
+	/*
+	 * If password change is needed, do it now.
+	 * This needs to occur before the ~/.hushlogin check.
+	 */
+	if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) {
+		display_loginmsg();
+		do_pam_chauthtok();
+		s->authctxt->force_pwchange = 0;
+		/* XXX - signal [net] parent to enable forwardings */
+	}
+#endif
+
+	if (check_quietlogin(s, command))
+		return;
+
+	display_loginmsg();
+
+	do_motd();
+}
+
+/*
+ * Display the message of the day.
+ */
+void
+do_motd(void)
+{
+	FILE *f;
+	char buf[256];
+
+	if (options.print_motd) {
+#ifdef HAVE_LOGIN_CAP
+		f = fopen(login_getcapstr(lc, "welcome", "/etc/motd",
+		    "/etc/motd"), "r");
+#else
+		f = fopen("/etc/motd", "r");
+#endif
+		if (f) {
+			while (fgets(buf, sizeof(buf), f))
+				fputs(buf, stdout);
+			fclose(f);
+		}
+	}
+}
+
+
+/*
+ * Check for quiet login, either .hushlogin or command given.
+ */
+int
+check_quietlogin(Session *s, const char *command)
+{
+	char buf[256];
+	struct passwd *pw = s->pw;
+	struct stat st;
+
+	/* Return 1 if .hushlogin exists or a command given. */
+	if (command != NULL)
+		return 1;
+	snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
+#ifdef HAVE_LOGIN_CAP
+	if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
+		return 1;
+#else
+	if (stat(buf, &st) >= 0)
+		return 1;
+#endif
+	return 0;
+}
+
+/*
+ * Sets the value of the given variable in the environment.  If the variable
+ * already exists, its value is overriden.
+ */
+void
+child_set_env(char ***envp, u_int *envsizep, const char *name,
+	const char *value)
+{
+	char **env;
+	u_int envsize;
+	u_int i, namelen;
+
+	/*
+	 * If we're passed an uninitialized list, allocate a single null
+	 * entry before continuing.
+	 */
+	if (*envp == NULL && *envsizep == 0) {
+		*envp = xmalloc(sizeof(char *));
+		*envp[0] = NULL;
+		*envsizep = 1;
+	}
+
+	/*
+	 * Find the slot where the value should be stored.  If the variable
+	 * already exists, we reuse the slot; otherwise we append a new slot
+	 * at the end of the array, expanding if necessary.
+	 */
+	env = *envp;
+	namelen = strlen(name);
+	for (i = 0; env[i]; i++)
+		if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
+			break;
+	if (env[i]) {
+		/* Reuse the slot. */
+		xfree(env[i]);
+	} else {
+		/* New variable.  Expand if necessary. */
+		envsize = *envsizep;
+		if (i >= envsize - 1) {
+			if (envsize >= 1000)
+				fatal("child_set_env: too many env vars");
+			envsize += 50;
+			env = (*envp) = xrealloc(env, envsize, sizeof(char *));
+			*envsizep = envsize;
+		}
+		/* Need to set the NULL pointer at end of array beyond the new slot. */
+		env[i + 1] = NULL;
+	}
+
+	/* Allocate space and format the variable in the appropriate slot. */
+	env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
+	snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
+}
+
+/*
+ * Reads environment variables from the given file and adds/overrides them
+ * into the environment.  If the file does not exist, this does nothing.
+ * Otherwise, it must consist of empty lines, comments (line starts with '#')
+ * and assignments of the form name=value.  No other forms are allowed.
+ */
+static void
+read_environment_file(char ***env, u_int *envsize,
+	const char *filename)
+{
+	FILE *f;
+	char buf[4096];
+	char *cp, *value;
+	u_int lineno = 0;
+
+	f = fopen(filename, "r");
+	if (!f)
+		return;
+
+	while (fgets(buf, sizeof(buf), f)) {
+		if (++lineno > 1000)
+			fatal("Too many lines in environment file %s", filename);
+		for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
+			;
+		if (!*cp || *cp == '#' || *cp == '\n')
+			continue;
+		if (strchr(cp, '\n'))
+			*strchr(cp, '\n') = '\0';
+		value = strchr(cp, '=');
+		if (value == NULL) {
+			fprintf(stderr, "Bad line %u in %.100s\n", lineno,
+			    filename);
+			continue;
+		}
+		/*
+		 * Replace the equals sign by nul, and advance value to
+		 * the value string.
+		 */
+		*value = '\0';
+		value++;
+		child_set_env(env, envsize, cp, value);
+	}
+	fclose(f);
+}
+
+#ifdef HAVE_ETC_DEFAULT_LOGIN
+/*
+ * Return named variable from specified environment, or NULL if not present.
+ */
+static char *
+child_get_env(char **env, const char *name)
+{
+	int i;
+	size_t len;
+
+	len = strlen(name);
+	for (i=0; env[i] != NULL; i++)
+		if (strncmp(name, env[i], len) == 0 && env[i][len] == '=')
+			return(env[i] + len + 1);
+	return NULL;
+}
+
+/*
+ * Read /etc/default/login.
+ * We pick up the PATH (or SUPATH for root) and UMASK.
+ */
+static void
+read_etc_default_login(char ***env, u_int *envsize, uid_t uid)
+{
+	char **tmpenv = NULL, *var;
+	u_int i, tmpenvsize = 0;
+	u_long mask;
+
+	/*
+	 * We don't want to copy the whole file to the child's environment,
+	 * so we use a temporary environment and copy the variables we're
+	 * interested in.
+	 */
+	read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login");
+
+	if (tmpenv == NULL)
+		return;
+
+	if (uid == 0)
+		var = child_get_env(tmpenv, "SUPATH");
+	else
+		var = child_get_env(tmpenv, "PATH");
+	if (var != NULL)
+		child_set_env(env, envsize, "PATH", var);
+
+	if ((var = child_get_env(tmpenv, "UMASK")) != NULL)
+		if (sscanf(var, "%5lo", &mask) == 1)
+			umask((mode_t)mask);
+
+	for (i = 0; tmpenv[i] != NULL; i++)
+		xfree(tmpenv[i]);
+	xfree(tmpenv);
+}
+#endif /* HAVE_ETC_DEFAULT_LOGIN */
+
+void
+copy_environment(char **source, char ***env, u_int *envsize)
+{
+	char *var_name, *var_val;
+	int i;
+
+	if (source == NULL)
+		return;
+
+	for(i = 0; source[i] != NULL; i++) {
+		var_name = xstrdup(source[i]);
+		if ((var_val = strstr(var_name, "=")) == NULL) {
+			xfree(var_name);
+			continue;
+		}
+		*var_val++ = '\0';
+
+		debug3("Copy environment: %s=%s", var_name, var_val);
+		child_set_env(env, envsize, var_name, var_val);
+
+		xfree(var_name);
+	}
+}
+
+static char **
+do_setup_env(Session *s, const char *shell)
+{
+	char buf[256];
+	u_int i, envsize;
+	char **env, *laddr;
+	struct passwd *pw = s->pw;
+#ifndef HAVE_LOGIN_CAP
+	char *path = NULL;
+#endif
+
+	/* Initialize the environment. */
+	envsize = 100;
+	env = xcalloc(envsize, sizeof(char *));
+	env[0] = NULL;
+
+#ifdef HAVE_CYGWIN
+	/*
+	 * The Windows environment contains some setting which are
+	 * important for a running system. They must not be dropped.
+	 */
+	{
+		char **p;
+
+		p = fetch_windows_environment();
+		copy_environment(p, &env, &envsize);
+		free_windows_environment(p);
+	}
+#endif
+
+#ifdef GSSAPI
+	/* Allow any GSSAPI methods that we've used to alter
+	 * the childs environment as they see fit
+	 */
+	ssh_gssapi_do_child(&env, &envsize);
+#endif
+
+	if (!options.use_login) {
+		/* Set basic environment. */
+		for (i = 0; i < s->num_env; i++)
+			child_set_env(&env, &envsize, s->env[i].name,
+			    s->env[i].val);
+
+		child_set_env(&env, &envsize, "USER", pw->pw_name);
+		child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
+#ifdef _AIX
+		child_set_env(&env, &envsize, "LOGIN", pw->pw_name);
+#endif
+		child_set_env(&env, &envsize, "HOME", pw->pw_dir);
+#ifdef HAVE_LOGIN_CAP
+		if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0)
+			child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
+		else
+			child_set_env(&env, &envsize, "PATH", getenv("PATH"));
+#else /* HAVE_LOGIN_CAP */
+# ifndef HAVE_CYGWIN
+		/*
+		 * There's no standard path on Windows. The path contains
+		 * important components pointing to the system directories,
+		 * needed for loading shared libraries. So the path better
+		 * remains intact here.
+		 */
+#  ifdef HAVE_ETC_DEFAULT_LOGIN
+		read_etc_default_login(&env, &envsize, pw->pw_uid);
+		path = child_get_env(env, "PATH");
+#  endif /* HAVE_ETC_DEFAULT_LOGIN */
+		if (path == NULL || *path == '\0') {
+			child_set_env(&env, &envsize, "PATH",
+			    s->pw->pw_uid == 0 ?
+				SUPERUSER_PATH : _PATH_STDPATH);
+		}
+# endif /* HAVE_CYGWIN */
+#endif /* HAVE_LOGIN_CAP */
+
+		snprintf(buf, sizeof buf, "%.200s/%.50s",
+			 _PATH_MAILDIR, pw->pw_name);
+		child_set_env(&env, &envsize, "MAIL", buf);
+
+		/* Normal systems set SHELL by default. */
+		child_set_env(&env, &envsize, "SHELL", shell);
+	}
+	if (getenv("TZ"))
+		child_set_env(&env, &envsize, "TZ", getenv("TZ"));
+
+	/* Set custom environment options from RSA authentication. */
+	if (!options.use_login) {
+		while (custom_environment) {
+			struct envstring *ce = custom_environment;
+			char *str = ce->s;
+
+			for (i = 0; str[i] != '=' && str[i]; i++)
+				;
+			if (str[i] == '=') {
+				str[i] = 0;
+				child_set_env(&env, &envsize, str, str + i + 1);
+			}
+			custom_environment = ce->next;
+			xfree(ce->s);
+			xfree(ce);
+		}
+	}
+
+	/* SSH_CLIENT deprecated */
+	snprintf(buf, sizeof buf, "%.50s %d %d",
+	    get_remote_ipaddr(), get_remote_port(), get_local_port());
+	child_set_env(&env, &envsize, "SSH_CLIENT", buf);
+
+	laddr = get_local_ipaddr(packet_get_connection_in());
+	snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
+	    get_remote_ipaddr(), get_remote_port(), laddr, get_local_port());
+	xfree(laddr);
+	child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
+
+	if (s->ttyfd != -1)
+		child_set_env(&env, &envsize, "SSH_TTY", s->tty);
+	if (s->term)
+		child_set_env(&env, &envsize, "TERM", s->term);
+	if (s->display)
+		child_set_env(&env, &envsize, "DISPLAY", s->display);
+	if (original_command)
+		child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
+		    original_command);
+
+#ifdef _UNICOS
+	if (cray_tmpdir[0] != '\0')
+		child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir);
+#endif /* _UNICOS */
+
+	/*
+	 * Since we clear KRB5CCNAME at startup, if it's set now then it
+	 * must have been set by a native authentication method (eg AIX or
+	 * SIA), so copy it to the child.
+	 */
+	{
+		char *cp;
+
+		if ((cp = getenv("KRB5CCNAME")) != NULL)
+			child_set_env(&env, &envsize, "KRB5CCNAME", cp);
+	}
+
+#ifdef _AIX
+	{
+		char *cp;
+
+		if ((cp = getenv("AUTHSTATE")) != NULL)
+			child_set_env(&env, &envsize, "AUTHSTATE", cp);
+		read_environment_file(&env, &envsize, "/etc/environment");
+	}
+#endif
+#ifdef KRB5
+	if (s->authctxt->krb5_ccname)
+		child_set_env(&env, &envsize, "KRB5CCNAME",
+		    s->authctxt->krb5_ccname);
+#endif
+#ifdef USE_PAM
+	/*
+	 * Pull in any environment variables that may have
+	 * been set by PAM.
+	 */
+	if (options.use_pam) {
+		char **p;
+
+		p = fetch_pam_child_environment();
+		copy_environment(p, &env, &envsize);
+		free_pam_environment(p);
+
+		p = fetch_pam_environment();
+		copy_environment(p, &env, &envsize);
+		free_pam_environment(p);
+	}
+#endif /* USE_PAM */
+
+	if (auth_sock_name != NULL)
+		child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
+		    auth_sock_name);
+
+	/* read $HOME/.ssh/environment. */
+	if (options.permit_user_env && !options.use_login) {
+		snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
+		    strcmp(pw->pw_dir, "/") ? pw->pw_dir : "");
+		read_environment_file(&env, &envsize, buf);
+	}
+	if (debug_flag) {
+		/* dump the environment */
+		fprintf(stderr, "Environment:\n");
+		for (i = 0; env[i]; i++)
+			fprintf(stderr, "  %.200s\n", env[i]);
+	}
+	return env;
+}
+
+/*
+ * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found
+ * first in this order).
+ */
+static void
+do_rc_files(Session *s, const char *shell)
+{
+	FILE *f = NULL;
+	char cmd[1024];
+	int do_xauth;
+	struct stat st;
+
+	do_xauth =
+	    s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
+
+	/* ignore _PATH_SSH_USER_RC for subsystems */
+	if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) {
+		snprintf(cmd, sizeof cmd, "%s -c '%s %s'",
+		    shell, _PATH_BSHELL, _PATH_SSH_USER_RC);
+		if (debug_flag)
+			fprintf(stderr, "Running %s\n", cmd);
+		f = popen(cmd, "w");
+		if (f) {
+			if (do_xauth)
+				fprintf(f, "%s %s\n", s->auth_proto,
+				    s->auth_data);
+			pclose(f);
+		} else
+			fprintf(stderr, "Could not run %s\n",
+			    _PATH_SSH_USER_RC);
+	} else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) {
+		if (debug_flag)
+			fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
+			    _PATH_SSH_SYSTEM_RC);
+		f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w");
+		if (f) {
+			if (do_xauth)
+				fprintf(f, "%s %s\n", s->auth_proto,
+				    s->auth_data);
+			pclose(f);
+		} else
+			fprintf(stderr, "Could not run %s\n",
+			    _PATH_SSH_SYSTEM_RC);
+	} else if (do_xauth && options.xauth_location != NULL) {
+		/* Add authority data to .Xauthority if appropriate. */
+		if (debug_flag) {
+			fprintf(stderr,
+			    "Running %.500s remove %.100s\n",
+			    options.xauth_location, s->auth_display);
+			fprintf(stderr,
+			    "%.500s add %.100s %.100s %.100s\n",
+			    options.xauth_location, s->auth_display,
+			    s->auth_proto, s->auth_data);
+		}
+		snprintf(cmd, sizeof cmd, "%s -q -",
+		    options.xauth_location);
+		f = popen(cmd, "w");
+		if (f) {
+			fprintf(f, "remove %s\n",
+			    s->auth_display);
+			fprintf(f, "add %s %s %s\n",
+			    s->auth_display, s->auth_proto,
+			    s->auth_data);
+			pclose(f);
+		} else {
+			fprintf(stderr, "Could not run %s\n",
+			    cmd);
+		}
+	}
+}
+
+static void
+do_nologin(struct passwd *pw)
+{
+	FILE *f = NULL;
+	char buf[1024];
+
+#ifdef HAVE_LOGIN_CAP
+	if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid)
+		f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN,
+		    _PATH_NOLOGIN), "r");
+#else
+	if (pw->pw_uid)
+		f = fopen(_PATH_NOLOGIN, "r");
+#endif
+	if (f) {
+		/* /etc/nologin exists.  Print its contents and exit. */
+		logit("User %.100s not allowed because %s exists",
+		    pw->pw_name, _PATH_NOLOGIN);
+		while (fgets(buf, sizeof(buf), f))
+			fputs(buf, stderr);
+		fclose(f);
+		fflush(NULL);
+		exit(254);
+	}
+}
+
+/* Set login name, uid, gid, and groups. */
+void
+do_setusercontext(struct passwd *pw)
+{
+#ifndef HAVE_CYGWIN
+	if (getuid() == 0 || geteuid() == 0)
+#endif /* HAVE_CYGWIN */
+	{
+
+#ifdef HAVE_SETPCRED
+		if (setpcred(pw->pw_name, (char **)NULL) == -1)
+			fatal("Failed to set process credentials");
+#endif /* HAVE_SETPCRED */
+#ifdef HAVE_LOGIN_CAP
+# ifdef __bsdi__
+		setpgid(0, 0);
+# endif
+#ifdef GSSAPI
+		if (options.gss_authentication) {
+			temporarily_use_uid(pw);
+			ssh_gssapi_storecreds();
+			restore_uid();
+		}
+#endif
+# ifdef USE_PAM
+		if (options.use_pam) {
+			do_pam_session();
+			do_pam_setcred(0);
+		}
+# endif /* USE_PAM */
+		if (setusercontext(lc, pw, pw->pw_uid,
+		    (LOGIN_SETALL & ~LOGIN_SETPATH)) < 0) {
+			perror("unable to set user context");
+			exit(1);
+		}
+#else
+# if defined(HAVE_GETLUID) && defined(HAVE_SETLUID)
+		/* Sets login uid for accounting */
+		if (getluid() == -1 && setluid(pw->pw_uid) == -1)
+			error("setluid: %s", strerror(errno));
+# endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */
+
+		if (setlogin(pw->pw_name) < 0)
+			error("setlogin failed: %s", strerror(errno));
+		if (setgid(pw->pw_gid) < 0) {
+			perror("setgid");
+			exit(1);
+		}
+		/* Initialize the group list. */
+		if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
+			perror("initgroups");
+			exit(1);
+		}
+		endgrent();
+#ifdef GSSAPI
+		if (options.gss_authentication) {
+			temporarily_use_uid(pw);
+			ssh_gssapi_storecreds();
+			restore_uid();
+		}
+#endif
+# ifdef USE_PAM
+		/*
+		 * PAM credentials may take the form of supplementary groups.
+		 * These will have been wiped by the above initgroups() call.
+		 * Reestablish them here.
+		 */
+		if (options.use_pam) {
+			do_pam_session();
+			do_pam_setcred(0);
+		}
+# endif /* USE_PAM */
+# if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY)
+		irix_setusercontext(pw);
+#  endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */
+# ifdef _AIX
+		aix_usrinfo(pw);
+# endif /* _AIX */
+#if defined(HAVE_LIBIAF)  &&  !defined(BROKEN_LIBIAF)
+		if (set_id(pw->pw_name) != 0) {
+			exit(1);
+		}
+#endif /* HAVE_LIBIAF  && !BROKEN_LIBIAF */
+		/* Permanently switch to the desired uid. */
+		permanently_set_uid(pw);
+#endif
+	}
+
+#ifdef HAVE_CYGWIN
+	if (is_winnt)
+#endif
+	if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
+		fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
+
+#ifdef WITH_SELINUX
+	ssh_selinux_setup_exec_context(pw->pw_name);
+#endif
+}
+
+static void
+do_pwchange(Session *s)
+{
+	fflush(NULL);
+	fprintf(stderr, "WARNING: Your password has expired.\n");
+	if (s->ttyfd != -1) {
+		fprintf(stderr,
+		    "You must change your password now and login again!\n");
+#ifdef PASSWD_NEEDS_USERNAME
+		execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name,
+		    (char *)NULL);
+#else
+		execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL);
+#endif
+		perror("passwd");
+	} else {
+		fprintf(stderr,
+		    "Password change required but no TTY available.\n");
+	}
+	exit(1);
+}
+
+static void
+launch_login(struct passwd *pw, const char *hostname)
+{
+	/* Launch login(1). */
+
+	execl(LOGIN_PROGRAM, "login", "-h", hostname,
+#ifdef xxxLOGIN_NEEDS_TERM
+		    (s->term ? s->term : "unknown"),
+#endif /* LOGIN_NEEDS_TERM */
+#ifdef LOGIN_NO_ENDOPT
+	    "-p", "-f", pw->pw_name, (char *)NULL);
+#else
+	    "-p", "-f", "--", pw->pw_name, (char *)NULL);
+#endif
+
+	/* Login couldn't be executed, die. */
+
+	perror("login");
+	exit(1);
+}
+
+static void
+child_close_fds(void)
+{
+	int i;
+
+	if (packet_get_connection_in() == packet_get_connection_out())
+		close(packet_get_connection_in());
+	else {
+		close(packet_get_connection_in());
+		close(packet_get_connection_out());
+	}
+	/*
+	 * Close all descriptors related to channels.  They will still remain
+	 * open in the parent.
+	 */
+	/* XXX better use close-on-exec? -markus */
+	channel_close_all();
+
+	/*
+	 * Close any extra file descriptors.  Note that there may still be
+	 * descriptors left by system functions.  They will be closed later.
+	 */
+	endpwent();
+
+	/*
+	 * Close any extra open file descriptors so that we don't have them
+	 * hanging around in clients.  Note that we want to do this after
+	 * initgroups, because at least on Solaris 2.3 it leaves file
+	 * descriptors open.
+	 */
+	for (i = 3; i < 64; i++)
+		close(i);
+}
+
+/*
+ * Performs common processing for the child, such as setting up the
+ * environment, closing extra file descriptors, setting the user and group
+ * ids, and executing the command or shell.
+ */
+void
+do_child(Session *s, const char *command)
+{
+	extern char **environ;
+	char **env;
+	char *argv[10];
+	const char *shell, *shell0, *hostname = NULL;
+	struct passwd *pw = s->pw;
+
+	/* remove hostkey from the child's memory */
+	destroy_sensitive_data();
+
+	/* Force a password change */
+	if (s->authctxt->force_pwchange) {
+		do_setusercontext(pw);
+		child_close_fds();
+		do_pwchange(s);
+		exit(1);
+	}
+
+	/* login(1) is only called if we execute the login shell */
+	if (options.use_login && command != NULL)
+		options.use_login = 0;
+
+#ifdef _UNICOS
+	cray_setup(pw->pw_uid, pw->pw_name, command);
+#endif /* _UNICOS */
+
+	/*
+	 * Login(1) does this as well, and it needs uid 0 for the "-h"
+	 * switch, so we let login(1) to this for us.
+	 */
+	if (!options.use_login) {
+#ifdef HAVE_OSF_SIA
+		session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty);
+		if (!check_quietlogin(s, command))
+			do_motd();
+#else /* HAVE_OSF_SIA */
+		/* When PAM is enabled we rely on it to do the nologin check */
+		if (!options.use_pam)
+			do_nologin(pw);
+		do_setusercontext(pw);
+		/*
+		 * PAM session modules in do_setusercontext may have
+		 * generated messages, so if this in an interactive
+		 * login then display them too.
+		 */
+		if (!check_quietlogin(s, command))
+			display_loginmsg();
+#endif /* HAVE_OSF_SIA */
+	}
+
+#ifdef USE_PAM
+	if (options.use_pam && !options.use_login && !is_pam_session_open()) {
+		debug3("PAM session not opened, exiting");
+		display_loginmsg();
+		exit(254);
+	}
+#endif
+
+	/*
+	 * Get the shell from the password data.  An empty shell field is
+	 * legal, and means /bin/sh.
+	 */
+	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
+
+	/*
+	 * Make sure $SHELL points to the shell from the password file,
+	 * even if shell is overridden from login.conf
+	 */
+	env = do_setup_env(s, shell);
+
+#ifdef HAVE_LOGIN_CAP
+	shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
+#endif
+
+	/* we have to stash the hostname before we close our socket. */
+	if (options.use_login)
+		hostname = get_remote_name_or_ip(utmp_len,
+		    options.use_dns);
+	/*
+	 * Close the connection descriptors; note that this is the child, and
+	 * the server will still have the socket open, and it is important
+	 * that we do not shutdown it.  Note that the descriptors cannot be
+	 * closed before building the environment, as we call
+	 * get_remote_ipaddr there.
+	 */
+	child_close_fds();
+
+	/*
+	 * Must take new environment into use so that .ssh/rc,
+	 * /etc/ssh/sshrc and xauth are run in the proper environment.
+	 */
+	environ = env;
+
+#if defined(KRB5) && defined(USE_AFS)
+	/*
+	 * At this point, we check to see if AFS is active and if we have
+	 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see
+	 * if we can (and need to) extend the ticket into an AFS token. If
+	 * we don't do this, we run into potential problems if the user's
+	 * home directory is in AFS and it's not world-readable.
+	 */
+
+	if (options.kerberos_get_afs_token && k_hasafs() &&
+	    (s->authctxt->krb5_ctx != NULL)) {
+		char cell[64];
+
+		debug("Getting AFS token");
+
+		k_setpag();
+
+		if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
+			krb5_afslog(s->authctxt->krb5_ctx,
+			    s->authctxt->krb5_fwd_ccache, cell, NULL);
+
+		krb5_afslog_home(s->authctxt->krb5_ctx,
+		    s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir);
+	}
+#endif
+
+	/* Change current directory to the user's home directory. */
+	if (chdir(pw->pw_dir) < 0) {
+		fprintf(stderr, "Could not chdir to home directory %s: %s\n",
+		    pw->pw_dir, strerror(errno));
+#ifdef HAVE_LOGIN_CAP
+		if (login_getcapbool(lc, "requirehome", 0))
+			exit(1);
+#endif
+	}
+
+	if (!options.use_login)
+		do_rc_files(s, shell);
+
+	/* restore SIGPIPE for child */
+	signal(SIGPIPE, SIG_DFL);
+
+	if (options.use_login) {
+		launch_login(pw, hostname);
+		/* NEVERREACHED */
+	}
+
+	/* Get the last component of the shell name. */
+	if ((shell0 = strrchr(shell, '/')) != NULL)
+		shell0++;
+	else
+		shell0 = shell;
+
+	/*
+	 * If we have no command, execute the shell.  In this case, the shell
+	 * name to be passed in argv[0] is preceded by '-' to indicate that
+	 * this is a login shell.
+	 */
+	if (!command) {
+		char argv0[256];
+
+		/* Start the shell.  Set initial character to '-'. */
+		argv0[0] = '-';
+
+		if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1)
+		    >= sizeof(argv0) - 1) {
+			errno = EINVAL;
+			perror(shell);
+			exit(1);
+		}
+
+		/* Execute the shell. */
+		argv[0] = argv0;
+		argv[1] = NULL;
+		execve(shell, argv, env);
+
+		/* Executing the shell failed. */
+		perror(shell);
+		exit(1);
+	}
+	/*
+	 * Execute the command using the user's shell.  This uses the -c
+	 * option to execute the command.
+	 */
+	argv[0] = (char *) shell0;
+	argv[1] = "-c";
+	argv[2] = (char *) command;
+	argv[3] = NULL;
+	execve(shell, argv, env);
+	perror(shell);
+	exit(1);
+}
+
+Session *
+session_new(void)
+{
+	int i;
+	static int did_init = 0;
+	if (!did_init) {
+		debug("session_new: init");
+		for (i = 0; i < MAX_SESSIONS; i++) {
+			sessions[i].used = 0;
+		}
+		did_init = 1;
+	}
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		if (! s->used) {
+			memset(s, 0, sizeof(*s));
+			s->chanid = -1;
+			s->ptyfd = -1;
+			s->ttyfd = -1;
+			s->used = 1;
+			s->self = i;
+			s->x11_chanids = NULL;
+			debug("session_new: session %d", i);
+			return s;
+		}
+	}
+	return NULL;
+}
+
+static void
+session_dump(void)
+{
+	int i;
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		debug("dump: used %d session %d %p channel %d pid %ld",
+		    s->used,
+		    s->self,
+		    s,
+		    s->chanid,
+		    (long)s->pid);
+	}
+}
+
+int
+session_open(Authctxt *authctxt, int chanid)
+{
+	Session *s = session_new();
+	debug("session_open: channel %d", chanid);
+	if (s == NULL) {
+		error("no more sessions");
+		return 0;
+	}
+	s->authctxt = authctxt;
+	s->pw = authctxt->pw;
+	if (s->pw == NULL || !authctxt->valid)
+		fatal("no user for session %d", s->self);
+	debug("session_open: session %d: link with channel %d", s->self, chanid);
+	s->chanid = chanid;
+	return 1;
+}
+
+Session *
+session_by_tty(char *tty)
+{
+	int i;
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
+			debug("session_by_tty: session %d tty %s", i, tty);
+			return s;
+		}
+	}
+	debug("session_by_tty: unknown tty %.100s", tty);
+	session_dump();
+	return NULL;
+}
+
+static Session *
+session_by_channel(int id)
+{
+	int i;
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		if (s->used && s->chanid == id) {
+			debug("session_by_channel: session %d channel %d", i, id);
+			return s;
+		}
+	}
+	debug("session_by_channel: unknown channel %d", id);
+	session_dump();
+	return NULL;
+}
+
+static Session *
+session_by_x11_channel(int id)
+{
+	int i, j;
+
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+
+		if (s->x11_chanids == NULL || !s->used)
+			continue;
+		for (j = 0; s->x11_chanids[j] != -1; j++) {
+			if (s->x11_chanids[j] == id) {
+				debug("session_by_x11_channel: session %d "
+				    "channel %d", s->self, id);
+				return s;
+			}
+		}
+	}
+	debug("session_by_x11_channel: unknown channel %d", id);
+	session_dump();
+	return NULL;
+}
+
+static Session *
+session_by_pid(pid_t pid)
+{
+	int i;
+	debug("session_by_pid: pid %ld", (long)pid);
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		if (s->used && s->pid == pid)
+			return s;
+	}
+	error("session_by_pid: unknown pid %ld", (long)pid);
+	session_dump();
+	return NULL;
+}
+
+static int
+session_window_change_req(Session *s)
+{
+	s->col = packet_get_int();
+	s->row = packet_get_int();
+	s->xpixel = packet_get_int();
+	s->ypixel = packet_get_int();
+	packet_check_eom();
+	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
+	return 1;
+}
+
+static int
+session_pty_req(Session *s)
+{
+	u_int len;
+	int n_bytes;
+
+	if (no_pty_flag) {
+		debug("Allocating a pty not permitted for this authentication.");
+		return 0;
+	}
+	if (s->ttyfd != -1) {
+		packet_disconnect("Protocol error: you already have a pty.");
+		return 0;
+	}
+
+	s->term = packet_get_string(&len);
+
+	if (compat20) {
+		s->col = packet_get_int();
+		s->row = packet_get_int();
+	} else {
+		s->row = packet_get_int();
+		s->col = packet_get_int();
+	}
+	s->xpixel = packet_get_int();
+	s->ypixel = packet_get_int();
+
+	if (strcmp(s->term, "") == 0) {
+		xfree(s->term);
+		s->term = NULL;
+	}
+
+	/* Allocate a pty and open it. */
+	debug("Allocating pty.");
+	if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) {
+		if (s->term)
+			xfree(s->term);
+		s->term = NULL;
+		s->ptyfd = -1;
+		s->ttyfd = -1;
+		error("session_pty_req: session %d alloc failed", s->self);
+		return 0;
+	}
+	debug("session_pty_req: session %d alloc %s", s->self, s->tty);
+
+	/* for SSH1 the tty modes length is not given */
+	if (!compat20)
+		n_bytes = packet_remaining();
+	tty_parse_modes(s->ttyfd, &n_bytes);
+
+	if (!use_privsep)
+		pty_setowner(s->pw, s->tty);
+
+	/* Set window size from the packet. */
+	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
+
+	packet_check_eom();
+	session_proctitle(s);
+	return 1;
+}
+
+static int
+session_subsystem_req(Session *s)
+{
+	struct stat st;
+	u_int len;
+	int success = 0;
+	char *prog, *cmd, *subsys = packet_get_string(&len);
+	u_int i;
+
+	packet_check_eom();
+	logit("subsystem request for %.100s", subsys);
+
+	for (i = 0; i < options.num_subsystems; i++) {
+		if (strcmp(subsys, options.subsystem_name[i]) == 0) {
+			prog = options.subsystem_command[i];
+			cmd = options.subsystem_args[i];
+			if (stat(prog, &st) < 0) {
+				error("subsystem: cannot stat %s: %s", prog,
+				    strerror(errno));
+				break;
+			}
+			debug("subsystem: exec() %s", cmd);
+			s->is_subsystem = 1;
+			do_exec(s, cmd);
+			success = 1;
+			break;
+		}
+	}
+
+	if (!success)
+		logit("subsystem request for %.100s failed, subsystem not found",
+		    subsys);
+
+	xfree(subsys);
+	return success;
+}
+
+static int
+session_x11_req(Session *s)
+{
+	int success;
+
+	if (s->auth_proto != NULL || s->auth_data != NULL) {
+		error("session_x11_req: session %d: "
+		    "x11 forwarding already active", s->self);
+		return 0;
+	}
+	s->single_connection = packet_get_char();
+	s->auth_proto = packet_get_string(NULL);
+	s->auth_data = packet_get_string(NULL);
+	s->screen = packet_get_int();
+	packet_check_eom();
+
+	success = session_setup_x11fwd(s);
+	if (!success) {
+		xfree(s->auth_proto);
+		xfree(s->auth_data);
+		s->auth_proto = NULL;
+		s->auth_data = NULL;
+	}
+	return success;
+}
+
+static int
+session_shell_req(Session *s)
+{
+	packet_check_eom();
+	do_exec(s, NULL);
+	return 1;
+}
+
+static int
+session_exec_req(Session *s)
+{
+	u_int len;
+	char *command = packet_get_string(&len);
+	packet_check_eom();
+	do_exec(s, command);
+	xfree(command);
+	return 1;
+}
+
+static int
+session_break_req(Session *s)
+{
+
+	packet_get_int();	/* ignored */
+	packet_check_eom();
+
+	if (s->ttyfd == -1 ||
+	    tcsendbreak(s->ttyfd, 0) < 0)
+		return 0;
+	return 1;
+}
+
+static int
+session_env_req(Session *s)
+{
+	char *name, *val;
+	u_int name_len, val_len, i;
+
+	name = packet_get_string(&name_len);
+	val = packet_get_string(&val_len);
+	packet_check_eom();
+
+	/* Don't set too many environment variables */
+	if (s->num_env > 128) {
+		debug2("Ignoring env request %s: too many env vars", name);
+		goto fail;
+	}
+
+	for (i = 0; i < options.num_accept_env; i++) {
+		if (match_pattern(name, options.accept_env[i])) {
+			debug2("Setting env %d: %s=%s", s->num_env, name, val);
+			s->env = xrealloc(s->env, s->num_env + 1,
+			    sizeof(*s->env));
+			s->env[s->num_env].name = name;
+			s->env[s->num_env].val = val;
+			s->num_env++;
+			return (1);
+		}
+	}
+	debug2("Ignoring env request %s: disallowed name", name);
+
+ fail:
+	xfree(name);
+	xfree(val);
+	return (0);
+}
+
+static int
+session_auth_agent_req(Session *s)
+{
+	static int called = 0;
+	packet_check_eom();
+	if (no_agent_forwarding_flag) {
+		debug("session_auth_agent_req: no_agent_forwarding_flag");
+		return 0;
+	}
+	if (called) {
+		return 0;
+	} else {
+		called = 1;
+		return auth_input_request_forwarding(s->pw);
+	}
+}
+
+int
+session_input_channel_req(Channel *c, const char *rtype)
+{
+	int success = 0;
+	Session *s;
+
+	if ((s = session_by_channel(c->self)) == NULL) {
+		logit("session_input_channel_req: no session %d req %.100s",
+		    c->self, rtype);
+		return 0;
+	}
+	debug("session_input_channel_req: session %d req %s", s->self, rtype);
+
+	/*
+	 * a session is in LARVAL state until a shell, a command
+	 * or a subsystem is executed
+	 */
+	if (c->type == SSH_CHANNEL_LARVAL) {
+		if (strcmp(rtype, "shell") == 0) {
+			success = session_shell_req(s);
+		} else if (strcmp(rtype, "exec") == 0) {
+			success = session_exec_req(s);
+		} else if (strcmp(rtype, "pty-req") == 0) {
+			success =  session_pty_req(s);
+		} else if (strcmp(rtype, "x11-req") == 0) {
+			success = session_x11_req(s);
+		} else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
+			success = session_auth_agent_req(s);
+		} else if (strcmp(rtype, "subsystem") == 0) {
+			success = session_subsystem_req(s);
+		} else if (strcmp(rtype, "env") == 0) {
+			success = session_env_req(s);
+		}
+	}
+	if (strcmp(rtype, "window-change") == 0) {
+		success = session_window_change_req(s);
+	} else if (strcmp(rtype, "break") == 0) {
+		success = session_break_req(s);
+	}
+
+	return success;
+}
+
+void
+session_set_fds(Session *s, int fdin, int fdout, int fderr)
+{
+	if (!compat20)
+		fatal("session_set_fds: called for proto != 2.0");
+	/*
+	 * now that have a child and a pipe to the child,
+	 * we can activate our channel and register the fd's
+	 */
+	if (s->chanid == -1)
+		fatal("no channel for session %d", s->self);
+	channel_set_fds(s->chanid,
+	    fdout, fdin, fderr,
+	    fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
+	    1,
+	    CHAN_SES_WINDOW_DEFAULT);
+}
+
+/*
+ * Function to perform pty cleanup. Also called if we get aborted abnormally
+ * (e.g., due to a dropped connection).
+ */
+void
+session_pty_cleanup2(Session *s)
+{
+	if (s == NULL) {
+		error("session_pty_cleanup: no session");
+		return;
+	}
+	if (s->ttyfd == -1)
+		return;
+
+	debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
+
+	/* Record that the user has logged out. */
+	if (s->pid != 0)
+		record_logout(s->pid, s->tty, s->pw->pw_name);
+
+	/* Release the pseudo-tty. */
+	if (getuid() == 0)
+		pty_release(s->tty);
+
+	/*
+	 * Close the server side of the socket pairs.  We must do this after
+	 * the pty cleanup, so that another process doesn't get this pty
+	 * while we're still cleaning up.
+	 */
+	if (close(s->ptymaster) < 0)
+		error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno));
+
+	/* unlink pty from session */
+	s->ttyfd = -1;
+}
+
+void
+session_pty_cleanup(Session *s)
+{
+	PRIVSEP(session_pty_cleanup2(s));
+}
+
+static char *
+sig2name(int sig)
+{
+#define SSH_SIG(x) if (sig == SIG ## x) return #x
+	SSH_SIG(ABRT);
+	SSH_SIG(ALRM);
+	SSH_SIG(FPE);
+	SSH_SIG(HUP);
+	SSH_SIG(ILL);
+	SSH_SIG(INT);
+	SSH_SIG(KILL);
+	SSH_SIG(PIPE);
+	SSH_SIG(QUIT);
+	SSH_SIG(SEGV);
+	SSH_SIG(TERM);
+	SSH_SIG(USR1);
+	SSH_SIG(USR2);
+#undef	SSH_SIG
+	return "SIG@openssh.com";
+}
+
+static void
+session_close_x11(int id)
+{
+	Channel *c;
+
+	if ((c = channel_by_id(id)) == NULL) {
+		debug("session_close_x11: x11 channel %d missing", id);
+	} else {
+		/* Detach X11 listener */
+		debug("session_close_x11: detach x11 channel %d", id);
+		channel_cancel_cleanup(id);
+		if (c->ostate != CHAN_OUTPUT_CLOSED)
+			chan_mark_dead(c);
+	}
+}
+
+static void
+session_close_single_x11(int id, void *arg)
+{
+	Session *s;
+	u_int i;
+
+	debug3("session_close_single_x11: channel %d", id);
+	channel_cancel_cleanup(id);
+	if ((s  = session_by_x11_channel(id)) == NULL)
+		fatal("session_close_single_x11: no x11 channel %d", id);
+	for (i = 0; s->x11_chanids[i] != -1; i++) {
+		debug("session_close_single_x11: session %d: "
+		    "closing channel %d", s->self, s->x11_chanids[i]);
+		/*
+		 * The channel "id" is already closing, but make sure we
+		 * close all of its siblings.
+		 */
+		if (s->x11_chanids[i] != id)
+			session_close_x11(s->x11_chanids[i]);
+	}
+	xfree(s->x11_chanids);
+	s->x11_chanids = NULL;
+	if (s->display) {
+		xfree(s->display);
+		s->display = NULL;
+	}
+	if (s->auth_proto) {
+		xfree(s->auth_proto);
+		s->auth_proto = NULL;
+	}
+	if (s->auth_data) {
+		xfree(s->auth_data);
+		s->auth_data = NULL;
+	}
+	if (s->auth_display) {
+		xfree(s->auth_display);
+		s->auth_display = NULL;
+	}
+}
+
+static void
+session_exit_message(Session *s, int status)
+{
+	Channel *c;
+
+	if ((c = channel_lookup(s->chanid)) == NULL)
+		fatal("session_exit_message: session %d: no channel %d",
+		    s->self, s->chanid);
+	debug("session_exit_message: session %d channel %d pid %ld",
+	    s->self, s->chanid, (long)s->pid);
+
+	if (WIFEXITED(status)) {
+		channel_request_start(s->chanid, "exit-status", 0);
+		packet_put_int(WEXITSTATUS(status));
+		packet_send();
+	} else if (WIFSIGNALED(status)) {
+		channel_request_start(s->chanid, "exit-signal", 0);
+		packet_put_cstring(sig2name(WTERMSIG(status)));
+#ifdef WCOREDUMP
+		packet_put_char(WCOREDUMP(status));
+#else /* WCOREDUMP */
+		packet_put_char(0);
+#endif /* WCOREDUMP */
+		packet_put_cstring("");
+		packet_put_cstring("");
+		packet_send();
+	} else {
+		/* Some weird exit cause.  Just exit. */
+		packet_disconnect("wait returned status %04x.", status);
+	}
+
+	/* disconnect channel */
+	debug("session_exit_message: release channel %d", s->chanid);
+
+	/*
+	 * Adjust cleanup callback attachment to send close messages when
+	 * the channel gets EOF. The session will be then be closed
+	 * by session_close_by_channel when the childs close their fds.
+	 */
+	channel_register_cleanup(c->self, session_close_by_channel, 1);
+
+	/*
+	 * emulate a write failure with 'chan_write_failed', nobody will be
+	 * interested in data we write.
+	 * Note that we must not call 'chan_read_failed', since there could
+	 * be some more data waiting in the pipe.
+	 */
+	if (c->ostate != CHAN_OUTPUT_CLOSED)
+		chan_write_failed(c);
+}
+
+void
+session_close(Session *s)
+{
+	u_int i;
+
+	debug("session_close: session %d pid %ld", s->self, (long)s->pid);
+	if (s->ttyfd != -1)
+		session_pty_cleanup(s);
+	if (s->term)
+		xfree(s->term);
+	if (s->display)
+		xfree(s->display);
+	if (s->x11_chanids)
+		xfree(s->x11_chanids);
+	if (s->auth_display)
+		xfree(s->auth_display);
+	if (s->auth_data)
+		xfree(s->auth_data);
+	if (s->auth_proto)
+		xfree(s->auth_proto);
+	s->used = 0;
+	if (s->env != NULL) {
+		for (i = 0; i < s->num_env; i++) {
+			xfree(s->env[i].name);
+			xfree(s->env[i].val);
+		}
+		xfree(s->env);
+	}
+	session_proctitle(s);
+}
+
+void
+session_close_by_pid(pid_t pid, int status)
+{
+	Session *s = session_by_pid(pid);
+	if (s == NULL) {
+		debug("session_close_by_pid: no session for pid %ld",
+		    (long)pid);
+		return;
+	}
+	if (s->chanid != -1)
+		session_exit_message(s, status);
+	if (s->ttyfd != -1)
+		session_pty_cleanup(s);
+	s->pid = 0;
+}
+
+/*
+ * this is called when a channel dies before
+ * the session 'child' itself dies
+ */
+void
+session_close_by_channel(int id, void *arg)
+{
+	Session *s = session_by_channel(id);
+	u_int i;
+
+	if (s == NULL) {
+		debug("session_close_by_channel: no session for id %d", id);
+		return;
+	}
+	debug("session_close_by_channel: channel %d child %ld",
+	    id, (long)s->pid);
+	if (s->pid != 0) {
+		debug("session_close_by_channel: channel %d: has child", id);
+		/*
+		 * delay detach of session, but release pty, since
+		 * the fd's to the child are already closed
+		 */
+		if (s->ttyfd != -1)
+			session_pty_cleanup(s);
+		return;
+	}
+	/* detach by removing callback */
+	channel_cancel_cleanup(s->chanid);
+
+	/* Close any X11 listeners associated with this session */
+	if (s->x11_chanids != NULL) {
+		for (i = 0; s->x11_chanids[i] != -1; i++) {
+			session_close_x11(s->x11_chanids[i]);
+			s->x11_chanids[i] = -1;
+		}
+	}
+
+	s->chanid = -1;
+	session_close(s);
+}
+
+void
+session_destroy_all(void (*closefunc)(Session *))
+{
+	int i;
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		if (s->used) {
+			if (closefunc != NULL)
+				closefunc(s);
+			else
+				session_close(s);
+		}
+	}
+}
+
+static char *
+session_tty_list(void)
+{
+	static char buf[1024];
+	int i;
+	char *cp;
+
+	buf[0] = '\0';
+	for (i = 0; i < MAX_SESSIONS; i++) {
+		Session *s = &sessions[i];
+		if (s->used && s->ttyfd != -1) {
+
+			if (strncmp(s->tty, "/dev/", 5) != 0) {
+				cp = strrchr(s->tty, '/');
+				cp = (cp == NULL) ? s->tty : cp + 1;
+			} else
+				cp = s->tty + 5;
+
+			if (buf[0] != '\0')
+				strlcat(buf, ",", sizeof buf);
+			strlcat(buf, cp, sizeof buf);
+		}
+	}
+	if (buf[0] == '\0')
+		strlcpy(buf, "notty", sizeof buf);
+	return buf;
+}
+
+void
+session_proctitle(Session *s)
+{
+	if (s->pw == NULL)
+		error("no user for session %d", s->self);
+	else
+		setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
+}
+
+int
+session_setup_x11fwd(Session *s)
+{
+	struct stat st;
+	char display[512], auth_display[512];
+	char hostname[MAXHOSTNAMELEN];
+	u_int i;
+
+	if (no_x11_forwarding_flag) {
+		packet_send_debug("X11 forwarding disabled in user configuration file.");
+		return 0;
+	}
+	if (!options.x11_forwarding) {
+		debug("X11 forwarding disabled in server configuration file.");
+		return 0;
+	}
+	if (!options.xauth_location ||
+	    (stat(options.xauth_location, &st) == -1)) {
+		packet_send_debug("No xauth program; cannot forward with spoofing.");
+		return 0;
+	}
+	if (options.use_login) {
+		packet_send_debug("X11 forwarding disabled; "
+		    "not compatible with UseLogin=yes.");
+		return 0;
+	}
+	if (s->display != NULL) {
+		debug("X11 display already set.");
+		return 0;
+	}
+	if (x11_create_display_inet(options.x11_display_offset,
+	    options.x11_use_localhost, s->single_connection,
+	    &s->display_number, &s->x11_chanids) == -1) {
+		debug("x11_create_display_inet failed.");
+		return 0;
+	}
+	for (i = 0; s->x11_chanids[i] != -1; i++) {
+		channel_register_cleanup(s->x11_chanids[i],
+		    session_close_single_x11, 0);
+	}
+
+	/* Set up a suitable value for the DISPLAY variable. */
+	if (gethostname(hostname, sizeof(hostname)) < 0)
+		fatal("gethostname: %.100s", strerror(errno));
+	/*
+	 * auth_display must be used as the displayname when the
+	 * authorization entry is added with xauth(1).  This will be
+	 * different than the DISPLAY string for localhost displays.
+	 */
+	if (options.x11_use_localhost) {
+		snprintf(display, sizeof display, "localhost:%u.%u",
+		    s->display_number, s->screen);
+		snprintf(auth_display, sizeof auth_display, "unix:%u.%u",
+		    s->display_number, s->screen);
+		s->display = xstrdup(display);
+		s->auth_display = xstrdup(auth_display);
+	} else {
+#ifdef IPADDR_IN_DISPLAY
+		struct hostent *he;
+		struct in_addr my_addr;
+
+		he = gethostbyname(hostname);
+		if (he == NULL) {
+			error("Can't get IP address for X11 DISPLAY.");
+			packet_send_debug("Can't get IP address for X11 DISPLAY.");
+			return 0;
+		}
+		memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
+		snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr),
+		    s->display_number, s->screen);
+#else
+		snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
+		    s->display_number, s->screen);
+#endif
+		s->display = xstrdup(display);
+		s->auth_display = xstrdup(display);
+	}
+
+	return 1;
+}
+
+static void
+do_authenticated2(Authctxt *authctxt)
+{
+	server_loop2(authctxt);
+}
+
+void
+do_cleanup(Authctxt *authctxt)
+{
+	static int called = 0;
+
+	debug("do_cleanup");
+
+	/* no cleanup if we're in the child for login shell */
+	if (is_child)
+		return;
+
+	/* avoid double cleanup */
+	if (called)
+		return;
+	called = 1;
+
+	if (authctxt == NULL || !authctxt->authenticated)
+		return;
+#ifdef KRB5
+	if (options.kerberos_ticket_cleanup &&
+	    authctxt->krb5_ctx)
+		krb5_cleanup_proc(authctxt);
+#endif
+
+#ifdef GSSAPI
+	if (compat20 && options.gss_cleanup_creds)
+		ssh_gssapi_cleanup_creds();
+#endif
+
+#ifdef USE_PAM
+	if (options.use_pam) {
+		sshpam_cleanup();
+		sshpam_thread_cleanup();
+	}
+#endif
+
+	/* remove agent socket */
+	auth_sock_cleanup_proc(authctxt->pw);
+
+	/*
+	 * Cleanup ptys/utmp only if privsep is disabled,
+	 * or if running in monitor.
+	 */
+	if (!use_privsep || mm_is_monitor())
+		session_destroy_all(session_pty_cleanup2);
+}