Adding upstream version 1:9.2p1.upstream/1%9.2p1upstream

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

1 files changed, 2725 insertions, 0 deletions

diff --git a/session.c b/session.c
new file mode 100644
index 0000000..f30d7ac
--- /dev/null
+++ b/session.c
@@ -0,0 +1,2725 @@
+/* $OpenBSD: session.c,v 1.333 2023/01/06 02:42:34 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>
+#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 <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <netdb.h>
+#ifdef HAVE_PATHS_H
+#include <paths.h>
+#endif
+#include <pwd.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <limits.h>
+
+#include "openbsd-compat/sys-queue.h"
+#include "xmalloc.h"
+#include "ssh.h"
+#include "ssh2.h"
+#include "sshpty.h"
+#include "packet.h"
+#include "sshbuf.h"
+#include "ssherr.h"
+#include "match.h"
+#include "uidswap.h"
+#include "compat.h"
+#include "channels.h"
+#include "sshkey.h"
+#include "cipher.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "hostfile.h"
+#include "auth.h"
+#include "auth-options.h"
+#include "authfd.h"
+#include "pathnames.h"
+#include "log.h"
+#include "misc.h"
+#include "servconf.h"
+#include "sshlogin.h"
+#include "serverloop.h"
+#include "canohost.h"
+#include "session.h"
+#include "kex.h"
+#include "monitor_wrap.h"
+#include "sftp.h"
+#include "atomicio.h"
+
+#if defined(KRB5) && defined(USE_AFS)
+#include <kafs.h>
+#endif
+
+#ifdef WITH_SELINUX
+#include <selinux/selinux.h>
+#endif
+
+#define IS_INTERNAL_SFTP(c) \
+	(!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \
+	 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \
+	  c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \
+	  c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t'))
+
+/* func */
+
+Session *session_new(void);
+void	session_set_fds(struct ssh *, Session *, int, int, int, int, int);
+void	session_pty_cleanup(Session *);
+void	session_proctitle(Session *);
+int	session_setup_x11fwd(struct ssh *, Session *);
+int	do_exec_pty(struct ssh *, Session *, const char *);
+int	do_exec_no_pty(struct ssh *, Session *, const char *);
+int	do_exec(struct ssh *, Session *, const char *);
+void	do_login(struct ssh *, Session *, const char *);
+void	do_child(struct ssh *, Session *, const char *);
+void	do_motd(void);
+int	check_quietlogin(Session *, const char *);
+
+static void do_authenticated2(struct ssh *, Authctxt *);
+
+static int session_pty_req(struct ssh *, Session *);
+
+/* import */
+extern ServerOptions options;
+extern char *__progname;
+extern int debug_flag;
+extern u_int utmp_len;
+extern int startup_pipe;
+extern void destroy_sensitive_data(void);
+extern struct sshbuf *loginmsg;
+extern struct sshauthopt *auth_opts;
+extern char *tun_fwd_ifnames; /* serverloop.c */
+
+/* original command from peer. */
+const char *original_command = NULL;
+
+/* data */
+static int sessions_first_unused = -1;
+static int sessions_nalloc = 0;
+static Session *sessions = NULL;
+
+#define SUBSYSTEM_NONE			0
+#define SUBSYSTEM_EXT			1
+#define SUBSYSTEM_INT_SFTP		2
+#define SUBSYSTEM_INT_SFTP_ERROR	3
+
+#ifdef HAVE_LOGIN_CAP
+login_cap_t *lc;
+#endif
+
+static int is_child = 0;
+static int in_chroot = 0;
+
+/* File containing userauth info, if ExposeAuthInfo set */
+static char *auth_info_file = NULL;
+
+/* 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 ssh *ssh, struct passwd * pw)
+{
+	Channel *nc;
+	int sock = -1;
+
+	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_dir = xstrdup("/tmp/ssh-XXXXXXXXXX");
+
+	/* Create private directory for socket */
+	if (mkdtemp(auth_sock_dir) == NULL) {
+		ssh_packet_send_debug(ssh, "Agent forwarding disabled: "
+		    "mkdtemp() failed: %.100s", strerror(errno));
+		restore_uid();
+		free(auth_sock_dir);
+		auth_sock_dir = NULL;
+		goto authsock_err;
+	}
+
+	xasprintf(&auth_sock_name, "%s/agent.%ld",
+	    auth_sock_dir, (long) getpid());
+
+	/* Start a Unix listener on auth_sock_name. */
+	sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0);
+
+	/* Restore the privileged uid. */
+	restore_uid();
+
+	/* Check for socket/bind/listen failure. */
+	if (sock < 0)
+		goto authsock_err;
+
+	/* Allocate a channel for the authentication agent socket. */
+	nc = channel_new(ssh, "auth-listener",
+	    SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
+	    CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
+	    0, "auth socket", 1);
+	nc->path = xstrdup(auth_sock_name);
+	return 1;
+
+ authsock_err:
+	free(auth_sock_name);
+	if (auth_sock_dir != NULL) {
+		temporarily_use_uid(pw);
+		rmdir(auth_sock_dir);
+		restore_uid();
+		free(auth_sock_dir);
+	}
+	if (sock != -1)
+		close(sock);
+	auth_sock_name = NULL;
+	auth_sock_dir = NULL;
+	return 0;
+}
+
+static void
+display_loginmsg(void)
+{
+	int r;
+
+	if (sshbuf_len(loginmsg) == 0)
+		return;
+	if ((r = sshbuf_put_u8(loginmsg, 0)) != 0)
+		fatal_fr(r, "sshbuf_put_u8");
+	printf("%s", (char *)sshbuf_ptr(loginmsg));
+	sshbuf_reset(loginmsg);
+}
+
+static void
+prepare_auth_info_file(struct passwd *pw, struct sshbuf *info)
+{
+	int fd = -1, success = 0;
+
+	if (!options.expose_userauth_info || info == NULL)
+		return;
+
+	temporarily_use_uid(pw);
+	auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX");
+	if ((fd = mkstemp(auth_info_file)) == -1) {
+		error_f("mkstemp: %s", strerror(errno));
+		goto out;
+	}
+	if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info),
+	    sshbuf_len(info)) != sshbuf_len(info)) {
+		error_f("write: %s", strerror(errno));
+		goto out;
+	}
+	if (close(fd) != 0) {
+		error_f("close: %s", strerror(errno));
+		goto out;
+	}
+	success = 1;
+ out:
+	if (!success) {
+		if (fd != -1)
+			close(fd);
+		free(auth_info_file);
+		auth_info_file = NULL;
+	}
+	restore_uid();
+}
+
+static void
+set_fwdpermit_from_authopts(struct ssh *ssh, const struct sshauthopt *opts)
+{
+	char *tmp, *cp, *host;
+	int port;
+	size_t i;
+
+	if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) {
+		channel_clear_permission(ssh, FORWARD_USER, FORWARD_LOCAL);
+		for (i = 0; i < auth_opts->npermitopen; i++) {
+			tmp = cp = xstrdup(auth_opts->permitopen[i]);
+			/* This shouldn't fail as it has already been checked */
+			if ((host = hpdelim2(&cp, NULL)) == NULL)
+				fatal_f("internal error: hpdelim");
+			host = cleanhostname(host);
+			if (cp == NULL || (port = permitopen_port(cp)) < 0)
+				fatal_f("internal error: permitopen port");
+			channel_add_permission(ssh,
+			    FORWARD_USER, FORWARD_LOCAL, host, port);
+			free(tmp);
+		}
+	}
+	if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) {
+		channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE);
+		for (i = 0; i < auth_opts->npermitlisten; i++) {
+			tmp = cp = xstrdup(auth_opts->permitlisten[i]);
+			/* This shouldn't fail as it has already been checked */
+			if ((host = hpdelim(&cp)) == NULL)
+				fatal_f("internal error: hpdelim");
+			host = cleanhostname(host);
+			if (cp == NULL || (port = permitopen_port(cp)) < 0)
+				fatal_f("internal error: permitlisten port");
+			channel_add_permission(ssh,
+			    FORWARD_USER, FORWARD_REMOTE, host, port);
+			free(tmp);
+		}
+	}
+}
+
+void
+do_authenticated(struct ssh *ssh, Authctxt *authctxt)
+{
+	setproctitle("%s", authctxt->pw->pw_name);
+
+	auth_log_authopts("active", auth_opts, 0);
+
+	/* setup the channel layer */
+	/* XXX - streamlocal? */
+	set_fwdpermit_from_authopts(ssh, auth_opts);
+
+	if (!auth_opts->permit_port_forwarding_flag ||
+	    options.disable_forwarding) {
+		channel_disable_admin(ssh, FORWARD_LOCAL);
+		channel_disable_admin(ssh, FORWARD_REMOTE);
+	} else {
+		if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0)
+			channel_disable_admin(ssh, FORWARD_LOCAL);
+		else
+			channel_permit_all(ssh, FORWARD_LOCAL);
+		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0)
+			channel_disable_admin(ssh, FORWARD_REMOTE);
+		else
+			channel_permit_all(ssh, FORWARD_REMOTE);
+	}
+	auth_debug_send(ssh);
+
+	prepare_auth_info_file(authctxt->pw, authctxt->session_info);
+
+	do_authenticated2(ssh, authctxt);
+
+	do_cleanup(ssh, authctxt);
+}
+
+/* Check untrusted xauth strings for metacharacters */
+static int
+xauth_valid_string(const char *s)
+{
+	size_t i;
+
+	for (i = 0; s[i] != '\0'; i++) {
+		if (!isalnum((u_char)s[i]) &&
+		    s[i] != '.' && s[i] != ':' && s[i] != '/' &&
+		    s[i] != '-' && s[i] != '_')
+			return 0;
+	}
+	return 1;
+}
+
+#define USE_PIPES 1
+/*
+ * 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.
+ */
+int
+do_exec_no_pty(struct ssh *ssh, Session *s, const char *command)
+{
+	pid_t pid;
+#ifdef USE_PIPES
+	int pin[2], pout[2], perr[2];
+
+	if (s == NULL)
+		fatal("do_exec_no_pty: no session");
+
+	/* Allocate pipes for communicating with the program. */
+	if (pipe(pin) == -1) {
+		error_f("pipe in: %.100s", strerror(errno));
+		return -1;
+	}
+	if (pipe(pout) == -1) {
+		error_f("pipe out: %.100s", strerror(errno));
+		close(pin[0]);
+		close(pin[1]);
+		return -1;
+	}
+	if (pipe(perr) == -1) {
+		error_f("pipe err: %.100s", strerror(errno));
+		close(pin[0]);
+		close(pin[1]);
+		close(pout[0]);
+		close(pout[1]);
+		return -1;
+	}
+#else
+	int inout[2], err[2];
+
+	if (s == NULL)
+		fatal("do_exec_no_pty: no session");
+
+	/* Uses socket pairs to communicate with the program. */
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) == -1) {
+		error_f("socketpair #1: %.100s", strerror(errno));
+		return -1;
+	}
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) == -1) {
+		error_f("socketpair #2: %.100s", strerror(errno));
+		close(inout[0]);
+		close(inout[1]);
+		return -1;
+	}
+#endif
+
+	session_proctitle(s);
+
+	/* Fork the child. */
+	switch ((pid = fork())) {
+	case -1:
+		error_f("fork: %.100s", strerror(errno));
+#ifdef USE_PIPES
+		close(pin[0]);
+		close(pin[1]);
+		close(pout[0]);
+		close(pout[1]);
+		close(perr[0]);
+		close(perr[1]);
+#else
+		close(inout[0]);
+		close(inout[1]);
+		close(err[0]);
+		close(err[1]);
+#endif
+		return -1;
+	case 0:
+		is_child = 1;
+
+		/*
+		 * Create a new session and process group since the 4.4BSD
+		 * setlogin() affects the entire process group.
+		 */
+		if (setsid() == -1)
+			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) == -1)
+			perror("dup2 stdin");
+		close(pin[0]);
+
+		/* Redirect stdout. */
+		close(pout[0]);
+		if (dup2(pout[1], 1) == -1)
+			perror("dup2 stdout");
+		close(pout[1]);
+
+		/* Redirect stderr. */
+		close(perr[0]);
+		if (dup2(perr[1], 2) == -1)
+			perror("dup2 stderr");
+		close(perr[1]);
+#else
+		/*
+		 * 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) == -1)	/* stdin */
+			perror("dup2 stdin");
+		if (dup2(inout[0], 1) == -1)	/* stdout (same as stdin) */
+			perror("dup2 stdout");
+		close(inout[0]);
+		if (dup2(err[0], 2) == -1)	/* stderr */
+			perror("dup2 stderr");
+		close(err[0]);
+#endif
+
+		/* Do processing for the child (exec command etc). */
+		do_child(ssh, s, command);
+		/* NOTREACHED */
+	default:
+		break;
+	}
+
+#ifdef HAVE_CYGWIN
+	cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
+#endif
+
+	s->pid = pid;
+	/* Set interactive/non-interactive mode. */
+	ssh_packet_set_interactive(ssh, s->display != NULL,
+	    options.ip_qos_interactive, options.ip_qos_bulk);
+
+	/*
+	 * 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.
+	 */
+	sshbuf_reset(loginmsg);
+
+#ifdef USE_PIPES
+	/* We are the parent.  Close the child sides of the pipes. */
+	close(pin[0]);
+	close(pout[1]);
+	close(perr[1]);
+
+	session_set_fds(ssh, s, pin[1], pout[0], perr[0],
+	    s->is_subsystem, 0);
+#else
+	/* We are the parent.  Close the child sides of the socket pairs. */
+	close(inout[0]);
+	close(err[0]);
+
+	/*
+	 * Enter the interactive session.  Note: server_loop must be able to
+	 * handle the case that fdin and fdout are the same.
+	 */
+	session_set_fds(ssh, s, inout[1], inout[1], err[1],
+	    s->is_subsystem, 0);
+#endif
+	return 0;
+}
+
+/*
+ * 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.
+ */
+int
+do_exec_pty(struct ssh *ssh, 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;
+
+	/*
+	 * 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.
+	 * Do this before forking (and cleanup in the child) so as to
+	 * detect and gracefully fail out-of-fd conditions.
+	 */
+	if ((fdout = dup(ptyfd)) == -1) {
+		error_f("dup #1: %s", strerror(errno));
+		close(ttyfd);
+		close(ptyfd);
+		return -1;
+	}
+	/* we keep a reference to the pty master */
+	if ((ptymaster = dup(ptyfd)) == -1) {
+		error_f("dup #2: %s", strerror(errno));
+		close(ttyfd);
+		close(ptyfd);
+		close(fdout);
+		return -1;
+	}
+
+	/* Fork the child. */
+	switch ((pid = fork())) {
+	case -1:
+		error_f("fork: %.100s", strerror(errno));
+		close(fdout);
+		close(ptymaster);
+		close(ttyfd);
+		close(ptyfd);
+		return -1;
+	case 0:
+		is_child = 1;
+
+		close(fdout);
+		close(ptymaster);
+
+		/* 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) == -1)
+			error("dup2 stdin: %s", strerror(errno));
+		if (dup2(ttyfd, 1) == -1)
+			error("dup2 stdout: %s", strerror(errno));
+		if (dup2(ttyfd, 2) == -1)
+			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
+		do_login(ssh, s, command);
+#endif
+		/*
+		 * Do common processing for the child, such as execing
+		 * the command.
+		 */
+		do_child(ssh, s, command);
+		/* NOTREACHED */
+	default:
+		break;
+	}
+
+#ifdef HAVE_CYGWIN
+	cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
+#endif
+
+	s->pid = pid;
+
+	/* Parent.  Close the slave side of the pseudo tty. */
+	close(ttyfd);
+
+	/* Enter interactive session. */
+	s->ptymaster = ptymaster;
+	ssh_packet_set_interactive(ssh, 1,
+	    options.ip_qos_interactive, options.ip_qos_bulk);
+	session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1);
+	return 0;
+}
+
+/*
+ * This is called to fork and execute a command.  If another command is
+ * to be forced, execute that instead.
+ */
+int
+do_exec(struct ssh *ssh, Session *s, const char *command)
+{
+	int ret;
+	const char *forced = NULL, *tty = NULL;
+	char session_type[1024];
+
+	if (options.adm_forced_command) {
+		original_command = command;
+		command = options.adm_forced_command;
+		forced = "(config)";
+	} else if (auth_opts->force_command != NULL) {
+		original_command = command;
+		command = auth_opts->force_command;
+		forced = "(key-option)";
+	}
+	s->forced = 0;
+	if (forced != NULL) {
+		s->forced = 1;
+		if (IS_INTERNAL_SFTP(command)) {
+			s->is_subsystem = s->is_subsystem ?
+			    SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR;
+		} else if (s->is_subsystem)
+			s->is_subsystem = SUBSYSTEM_EXT;
+		snprintf(session_type, sizeof(session_type),
+		    "forced-command %s '%.900s'", forced, command);
+	} else if (s->is_subsystem) {
+		snprintf(session_type, sizeof(session_type),
+		    "subsystem '%.900s'", s->subsys);
+	} else if (command == NULL) {
+		snprintf(session_type, sizeof(session_type), "shell");
+	} else {
+		/* NB. we don't log unforced commands to preserve privacy */
+		snprintf(session_type, sizeof(session_type), "command");
+	}
+
+	if (s->ttyfd != -1) {
+		tty = s->tty;
+		if (strncmp(tty, "/dev/", 5) == 0)
+			tty += 5;
+	}
+
+	verbose("Starting session: %s%s%s for %s from %.200s port %d id %d",
+	    session_type,
+	    tty == NULL ? "" : " on ",
+	    tty == NULL ? "" : tty,
+	    s->pw->pw_name,
+	    ssh_remote_ipaddr(ssh),
+	    ssh_remote_port(ssh),
+	    s->self);
+
+#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)
+		ret = do_exec_pty(ssh, s, command);
+	else
+		ret = do_exec_no_pty(ssh, 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.
+	 */
+	sshbuf_reset(loginmsg);
+
+	return ret;
+}
+
+/* administrative, login(1)-like work */
+void
+do_login(struct ssh *ssh, 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 (ssh_packet_connection_is_on_socket(ssh)) {
+		if (getpeername(ssh_packet_get_connection_in(ssh),
+		    (struct sockaddr *)&from, &fromlen) == -1) {
+			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,
+		    session_get_remote_name_or_ip(ssh, 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;
+}
+
+/*
+ * 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.
+ * If allowlist is not NULL, then it is interpreted as a pattern list and
+ * only variable names that match it will be accepted.
+ */
+static void
+read_environment_file(char ***env, u_int *envsize,
+	const char *filename, const char *allowlist)
+{
+	FILE *f;
+	char *line = NULL, *cp, *value;
+	size_t linesize = 0;
+	u_int lineno = 0;
+
+	f = fopen(filename, "r");
+	if (!f)
+		return;
+
+	while (getline(&line, &linesize, f) != -1) {
+		if (++lineno > 1000)
+			fatal("Too many lines in environment file %s", filename);
+		for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
+			;
+		if (!*cp || *cp == '#' || *cp == '\n')
+			continue;
+
+		cp[strcspn(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++;
+		if (allowlist != NULL &&
+		    match_pattern_list(cp, allowlist, 0) != 1)
+			continue;
+		child_set_env(env, envsize, cp, value);
+	}
+	free(line);
+	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",
+	    options.permit_user_env_allowlist);
+
+	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++)
+		free(tmpenv[i]);
+	free(tmpenv);
+}
+#endif /* HAVE_ETC_DEFAULT_LOGIN */
+
+#if defined(USE_PAM) || defined(HAVE_CYGWIN)
+static void
+copy_environment_denylist(char **source, char ***env, u_int *envsize,
+    const char *denylist)
+{
+	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) {
+			free(var_name);
+			continue;
+		}
+		*var_val++ = '\0';
+
+		if (denylist == NULL ||
+		    match_pattern_list(var_name, denylist, 0) != 1) {
+			debug3("Copy environment: %s=%s", var_name, var_val);
+			child_set_env(env, envsize, var_name, var_val);
+		}
+
+		free(var_name);
+	}
+}
+#endif /* defined(USE_PAM) || defined(HAVE_CYGWIN) */
+
+#ifdef HAVE_CYGWIN
+static void
+copy_environment(char **source, char ***env, u_int *envsize)
+{
+	copy_environment_denylist(source, env, envsize, NULL);
+}
+#endif
+
+static char **
+do_setup_env(struct ssh *ssh, Session *s, const char *shell)
+{
+	char buf[256];
+	size_t n;
+	u_int i, envsize;
+	char *ocp, *cp, *value, **env, *laddr;
+	struct passwd *pw = s->pw;
+#if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN)
+	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 child's environment as they see fit
+	 */
+	ssh_gssapi_do_child(&env, &envsize);
+#endif
+
+	/* 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 */
+
+	if (!options.use_pam) {
+		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"));
+	if (s->term)
+		child_set_env(&env, &envsize, "TERM", s->term);
+	if (s->display)
+		child_set_env(&env, &envsize, "DISPLAY", s->display);
+
+	/*
+	 * 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",
+		    options.permit_user_env_allowlist);
+	}
+#endif
+#ifdef KRB5
+	if (s->authctxt->krb5_ccname)
+		child_set_env(&env, &envsize, "KRB5CCNAME",
+		    s->authctxt->krb5_ccname);
+#endif
+	if (auth_sock_name != NULL)
+		child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
+		    auth_sock_name);
+
+
+	/* Set custom environment options from pubkey authentication. */
+	if (options.permit_user_env) {
+		for (n = 0 ; n < auth_opts->nenv; n++) {
+			ocp = xstrdup(auth_opts->env[n]);
+			cp = strchr(ocp, '=');
+			if (cp != NULL) {
+				*cp = '\0';
+				/* Apply PermitUserEnvironment allowlist */
+				if (options.permit_user_env_allowlist == NULL ||
+				    match_pattern_list(ocp,
+				    options.permit_user_env_allowlist, 0) == 1)
+					child_set_env(&env, &envsize,
+					    ocp, cp + 1);
+			}
+			free(ocp);
+		}
+	}
+
+	/* read $HOME/.ssh/environment. */
+	if (options.permit_user_env) {
+		snprintf(buf, sizeof buf, "%.200s/%s/environment",
+		    pw->pw_dir, _PATH_SSH_USER_DIR);
+		read_environment_file(&env, &envsize, buf,
+		    options.permit_user_env_allowlist);
+	}
+
+#ifdef USE_PAM
+	/*
+	 * Pull in any environment variables that may have
+	 * been set by PAM.
+	 */
+	if (options.use_pam) {
+		char **p;
+
+		/*
+		 * Don't allow PAM-internal env vars to leak
+		 * back into the session environment.
+		 */
+#define PAM_ENV_DENYLIST  "SSH_AUTH_INFO*,SSH_CONNECTION*"
+		p = fetch_pam_child_environment();
+		copy_environment_denylist(p, &env, &envsize,
+		    PAM_ENV_DENYLIST);
+		free_pam_environment(p);
+
+		p = fetch_pam_environment();
+		copy_environment_denylist(p, &env, &envsize,
+		    PAM_ENV_DENYLIST);
+		free_pam_environment(p);
+	}
+#endif /* USE_PAM */
+
+	/* Environment specified by admin */
+	for (i = 0; i < options.num_setenv; i++) {
+		cp = xstrdup(options.setenv[i]);
+		if ((value = strchr(cp, '=')) == NULL) {
+			/* shouldn't happen; vars are checked in servconf.c */
+			fatal("Invalid config SetEnv: %s", options.setenv[i]);
+		}
+		*value++ = '\0';
+		child_set_env(&env, &envsize, cp, value);
+	}
+
+	/* SSH_CLIENT deprecated */
+	snprintf(buf, sizeof buf, "%.50s %d %d",
+	    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+	    ssh_local_port(ssh));
+	child_set_env(&env, &envsize, "SSH_CLIENT", buf);
+
+	laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh));
+	snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
+	    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+	    laddr, ssh_local_port(ssh));
+	free(laddr);
+	child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
+
+	if (tun_fwd_ifnames != NULL)
+		child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames);
+	if (auth_info_file != NULL)
+		child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file);
+	if (s->ttyfd != -1)
+		child_set_env(&env, &envsize, "SSH_TTY", s->tty);
+	if (original_command)
+		child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
+		    original_command);
+
+	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(struct ssh *ssh, Session *s, const char *shell)
+{
+	FILE *f = NULL;
+	char *cmd = NULL, *user_rc = NULL;
+	int do_xauth;
+	struct stat st;
+
+	do_xauth =
+	    s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
+	xasprintf(&user_rc, "%s/%s", s->pw->pw_dir, _PATH_SSH_USER_RC);
+
+	/* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */
+	if (!s->is_subsystem && options.adm_forced_command == NULL &&
+	    auth_opts->permit_user_rc && options.permit_user_rc &&
+	    stat(user_rc, &st) >= 0) {
+		if (xasprintf(&cmd, "%s -c '%s %s'", shell, _PATH_BSHELL,
+		    user_rc) == -1)
+			fatal_f("xasprintf: %s", strerror(errno));
+		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",
+			    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);
+		}
+		if (xasprintf(&cmd, "%s -q -", options.xauth_location) == -1)
+			fatal_f("xasprintf: %s", strerror(errno));
+		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);
+		}
+	}
+	free(cmd);
+	free(user_rc);
+}
+
+static void
+do_nologin(struct passwd *pw)
+{
+	FILE *f = NULL;
+	char buf[1024], *nl, *def_nl = _PATH_NOLOGIN;
+	struct stat sb;
+
+#ifdef HAVE_LOGIN_CAP
+	if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0)
+		return;
+	nl = login_getcapstr(lc, "nologin", def_nl, def_nl);
+#else
+	if (pw->pw_uid == 0)
+		return;
+	nl = def_nl;
+#endif
+	if (stat(nl, &sb) == -1)
+		return;
+
+	/* /etc/nologin exists.  Print its contents if we can and exit. */
+	logit("User %.100s not allowed because %s exists", pw->pw_name, nl);
+	if ((f = fopen(nl, "r")) != NULL) {
+		while (fgets(buf, sizeof(buf), f))
+			fputs(buf, stderr);
+		fclose(f);
+	}
+	exit(254);
+}
+
+/*
+ * Chroot into a directory after checking it for safety: all path components
+ * must be root-owned directories with strict permissions.
+ */
+static void
+safely_chroot(const char *path, uid_t uid)
+{
+	const char *cp;
+	char component[PATH_MAX];
+	struct stat st;
+
+	if (!path_absolute(path))
+		fatal("chroot path does not begin at root");
+	if (strlen(path) >= sizeof(component))
+		fatal("chroot path too long");
+
+	/*
+	 * Descend the path, checking that each component is a
+	 * root-owned directory with strict permissions.
+	 */
+	for (cp = path; cp != NULL;) {
+		if ((cp = strchr(cp, '/')) == NULL)
+			strlcpy(component, path, sizeof(component));
+		else {
+			cp++;
+			memcpy(component, path, cp - path);
+			component[cp - path] = '\0';
+		}
+	
+		debug3_f("checking '%s'", component);
+
+		if (stat(component, &st) != 0)
+			fatal_f("stat(\"%s\"): %s",
+			    component, strerror(errno));
+		if (st.st_uid != 0 || (st.st_mode & 022) != 0)
+			fatal("bad ownership or modes for chroot "
+			    "directory %s\"%s\"",
+			    cp == NULL ? "" : "component ", component);
+		if (!S_ISDIR(st.st_mode))
+			fatal("chroot path %s\"%s\" is not a directory",
+			    cp == NULL ? "" : "component ", component);
+
+	}
+
+	if (chdir(path) == -1)
+		fatal("Unable to chdir to chroot path \"%s\": "
+		    "%s", path, strerror(errno));
+	if (chroot(path) == -1)
+		fatal("chroot(\"%s\"): %s", path, strerror(errno));
+	if (chdir("/") == -1)
+		fatal_f("chdir(/) after chroot: %s", strerror(errno));
+	verbose("Changed root directory to \"%s\"", path);
+}
+
+/* Set login name, uid, gid, and groups. */
+void
+do_setusercontext(struct passwd *pw)
+{
+	char uidstr[32], *chroot_path, *tmp;
+
+	platform_setusercontext(pw);
+
+	if (platform_privileged_uidswap()) {
+#ifdef HAVE_LOGIN_CAP
+		if (setusercontext(lc, pw, pw->pw_uid,
+		    (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) {
+			perror("unable to set user context");
+			exit(1);
+		}
+#else
+		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();
+#endif
+
+		platform_setusercontext_post_groups(pw);
+
+		if (!in_chroot && options.chroot_directory != NULL &&
+		    strcasecmp(options.chroot_directory, "none") != 0) {
+			tmp = tilde_expand_filename(options.chroot_directory,
+			    pw->pw_uid);
+			snprintf(uidstr, sizeof(uidstr), "%llu",
+			    (unsigned long long)pw->pw_uid);
+			chroot_path = percent_expand(tmp, "h", pw->pw_dir,
+			    "u", pw->pw_name, "U", uidstr, (char *)NULL);
+			safely_chroot(chroot_path, pw->pw_uid);
+			free(tmp);
+			free(chroot_path);
+			/* Make sure we don't attempt to chroot again */
+			free(options.chroot_directory);
+			options.chroot_directory = NULL;
+			in_chroot = 1;
+		}
+
+#ifdef HAVE_LOGIN_CAP
+		if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) {
+			perror("unable to set user context (setuser)");
+			exit(1);
+		}
+		/* 
+		 * FreeBSD's setusercontext() will not apply the user's
+		 * own umask setting unless running with the user's UID.
+		 */
+		(void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK);
+#else
+# ifdef USE_LIBIAF
+		/*
+		 * In a chroot environment, the set_id() will always fail;
+		 * typically because of the lack of necessary authentication
+		 * services and runtime such as ./usr/lib/libiaf.so,
+		 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the
+		 * internal sftp chroot case.  We'll lose auditing and ACLs but
+		 * permanently_set_uid will take care of the rest.
+		 */
+		if (!in_chroot && set_id(pw->pw_name) != 0)
+			fatal("set_id(%s) Failed", pw->pw_name);
+# endif /* USE_LIBIAF */
+		/* Permanently switch to the desired uid. */
+		permanently_set_uid(pw);
+#endif
+	} else if (options.chroot_directory != NULL &&
+	    strcasecmp(options.chroot_directory, "none") != 0) {
+		fatal("server lacks privileges to chroot to ChrootDirectory");
+	}
+
+	if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
+		fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
+}
+
+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 WITH_SELINUX
+		setexeccon(NULL);
+#endif
+#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
+child_close_fds(struct ssh *ssh)
+{
+	extern int auth_sock;
+
+	if (auth_sock != -1) {
+		close(auth_sock);
+		auth_sock = -1;
+	}
+
+	if (ssh_packet_get_connection_in(ssh) ==
+	    ssh_packet_get_connection_out(ssh))
+		close(ssh_packet_get_connection_in(ssh));
+	else {
+		close(ssh_packet_get_connection_in(ssh));
+		close(ssh_packet_get_connection_out(ssh));
+	}
+	/*
+	 * Close all descriptors related to channels.  They will still remain
+	 * open in the parent.
+	 */
+	/* XXX better use close-on-exec? -markus */
+	channel_close_all(ssh);
+
+	/*
+	 * Close any extra file descriptors.  Note that there may still be
+	 * descriptors left by system functions.  They will be closed later.
+	 */
+	endpwent();
+
+	/* Stop directing logs to a high-numbered fd before we close it */
+	log_redirect_stderr_to(NULL);
+
+	/*
+	 * 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.
+	 */
+	closefrom(STDERR_FILENO + 1);
+}
+
+/*
+ * 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.
+ */
+#define ARGV_MAX 10
+void
+do_child(struct ssh *ssh, Session *s, const char *command)
+{
+	extern char **environ;
+	char **env, *argv[ARGV_MAX], remote_id[512];
+	const char *shell, *shell0;
+	struct passwd *pw = s->pw;
+	int r = 0;
+
+	sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
+
+	/* remove hostkey from the child's memory */
+	destroy_sensitive_data();
+	ssh_packet_clear_keys(ssh);
+
+	/* Force a password change */
+	if (s->authctxt->force_pwchange) {
+		do_setusercontext(pw);
+		child_close_fds(ssh);
+		do_pwchange(s);
+		exit(1);
+	}
+
+	/*
+	 * Login(1) does this as well, and it needs uid 0 for the "-h"
+	 * switch, so we let login(1) to this for us.
+	 */
+#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 && !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(ssh, s, shell);
+
+#ifdef HAVE_LOGIN_CAP
+	shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
+#endif
+
+	/*
+	 * 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
+	 * ssh_remote_ipaddr there.
+	 */
+	child_close_fds(ssh);
+
+	/*
+	 * 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) == -1) {
+		/* Suppress missing homedir warning for chroot case */
+#ifdef HAVE_LOGIN_CAP
+		r = login_getcapbool(lc, "requirehome", 0);
+#endif
+		if (r || !in_chroot) {
+			fprintf(stderr, "Could not chdir to home "
+			    "directory %s: %s\n", pw->pw_dir,
+			    strerror(errno));
+		}
+		if (r)
+			exit(1);
+	}
+
+	closefrom(STDERR_FILENO + 1);
+
+	do_rc_files(ssh, s, shell);
+
+	/* restore SIGPIPE for child */
+	ssh_signal(SIGPIPE, SIG_DFL);
+
+	if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) {
+		error("Connection from %s: refusing non-sftp session",
+		    remote_id);
+		printf("This service allows sftp connections only.\n");
+		fflush(NULL);
+		exit(1);
+	} else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) {
+		extern int optind, optreset;
+		int i;
+		char *p, *args;
+
+		setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME);
+		args = xstrdup(command ? command : "sftp-server");
+		for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " ")))
+			if (i < ARGV_MAX - 1)
+				argv[i++] = p;
+		argv[i] = NULL;
+		optind = optreset = 1;
+		__progname = argv[0];
+#ifdef WITH_SELINUX
+		ssh_selinux_change_context("sftpd_t");
+#endif
+		exit(sftp_server_main(i, argv, s->pw));
+	}
+
+	fflush(NULL);
+
+	/* 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);
+}
+
+void
+session_unused(int id)
+{
+	debug3_f("session id %d unused", id);
+	if (id >= options.max_sessions ||
+	    id >= sessions_nalloc) {
+		fatal_f("insane session id %d (max %d nalloc %d)",
+		    id, options.max_sessions, sessions_nalloc);
+	}
+	memset(&sessions[id], 0, sizeof(*sessions));
+	sessions[id].self = id;
+	sessions[id].used = 0;
+	sessions[id].chanid = -1;
+	sessions[id].ptyfd = -1;
+	sessions[id].ttyfd = -1;
+	sessions[id].ptymaster = -1;
+	sessions[id].x11_chanids = NULL;
+	sessions[id].next_unused = sessions_first_unused;
+	sessions_first_unused = id;
+}
+
+Session *
+session_new(void)
+{
+	Session *s, *tmp;
+
+	if (sessions_first_unused == -1) {
+		if (sessions_nalloc >= options.max_sessions)
+			return NULL;
+		debug2_f("allocate (allocated %d max %d)",
+		    sessions_nalloc, options.max_sessions);
+		tmp = xrecallocarray(sessions, sessions_nalloc,
+		    sessions_nalloc + 1, sizeof(*sessions));
+		if (tmp == NULL) {
+			error_f("cannot allocate %d sessions",
+			    sessions_nalloc + 1);
+			return NULL;
+		}
+		sessions = tmp;
+		session_unused(sessions_nalloc++);
+	}
+
+	if (sessions_first_unused >= sessions_nalloc ||
+	    sessions_first_unused < 0) {
+		fatal_f("insane first_unused %d max %d nalloc %d",
+		    sessions_first_unused, options.max_sessions,
+		    sessions_nalloc);
+	}
+
+	s = &sessions[sessions_first_unused];
+	if (s->used)
+		fatal_f("session %d already used", sessions_first_unused);
+	sessions_first_unused = s->next_unused;
+	s->used = 1;
+	s->next_unused = -1;
+	debug("session_new: session %d", s->self);
+
+	return s;
+}
+
+static void
+session_dump(void)
+{
+	int i;
+	for (i = 0; i < sessions_nalloc; i++) {
+		Session *s = &sessions[i];
+
+		debug("dump: used %d next_unused %d session %d "
+		    "channel %d pid %ld",
+		    s->used,
+		    s->next_unused,
+		    s->self,
+		    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 < sessions_nalloc; 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 < sessions_nalloc; 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 < sessions_nalloc; 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 < sessions_nalloc; 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(struct ssh *ssh, Session *s)
+{
+	int r;
+
+	if ((r = sshpkt_get_u32(ssh, &s->col)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->row)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
+	return 1;
+}
+
+static int
+session_pty_req(struct ssh *ssh, Session *s)
+{
+	int r;
+
+	if (!auth_opts->permit_pty_flag || !options.permit_tty) {
+		debug("Allocating a pty not permitted for this connection.");
+		return 0;
+	}
+	if (s->ttyfd != -1) {
+		ssh_packet_disconnect(ssh, "Protocol error: you already have a pty.");
+		return 0;
+	}
+
+	if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->col)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->row)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	if (strcmp(s->term, "") == 0) {
+		free(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)))) {
+		free(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);
+
+	ssh_tty_parse_modes(ssh, s->ttyfd);
+
+	if ((r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	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);
+
+	session_proctitle(s);
+	return 1;
+}
+
+static int
+session_subsystem_req(struct ssh *ssh, Session *s)
+{
+	struct stat st;
+	int r, success = 0;
+	char *prog, *cmd, *type;
+	u_int i;
+
+	if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	debug2("subsystem request for %.100s by user %s", s->subsys,
+	    s->pw->pw_name);
+
+	for (i = 0; i < options.num_subsystems; i++) {
+		if (strcmp(s->subsys, options.subsystem_name[i]) == 0) {
+			prog = options.subsystem_command[i];
+			cmd = options.subsystem_args[i];
+			if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) {
+				s->is_subsystem = SUBSYSTEM_INT_SFTP;
+				debug("subsystem: %s", prog);
+			} else {
+				if (stat(prog, &st) == -1)
+					debug("subsystem: cannot stat %s: %s",
+					    prog, strerror(errno));
+				s->is_subsystem = SUBSYSTEM_EXT;
+				debug("subsystem: exec() %s", cmd);
+			}
+			xasprintf(&type, "session:subsystem:%s",
+			    options.subsystem_name[i]);
+			channel_set_xtype(ssh, s->chanid, type);
+			free(type);
+			success = do_exec(ssh, s, cmd) == 0;
+			break;
+		}
+	}
+
+	if (!success)
+		logit("subsystem request for %.100s by user %s failed, "
+		    "subsystem not found", s->subsys, s->pw->pw_name);
+
+	return success;
+}
+
+static int
+session_x11_req(struct ssh *ssh, Session *s)
+{
+	int r, success;
+	u_char single_connection = 0;
+
+	if (s->auth_proto != NULL || s->auth_data != NULL) {
+		error("session_x11_req: session %d: "
+		    "x11 forwarding already active", s->self);
+		return 0;
+	}
+	if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &s->screen)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	s->single_connection = single_connection;
+
+	if (xauth_valid_string(s->auth_proto) &&
+	    xauth_valid_string(s->auth_data))
+		success = session_setup_x11fwd(ssh, s);
+	else {
+		success = 0;
+		error("Invalid X11 forwarding data");
+	}
+	if (!success) {
+		free(s->auth_proto);
+		free(s->auth_data);
+		s->auth_proto = NULL;
+		s->auth_data = NULL;
+	}
+	return success;
+}
+
+static int
+session_shell_req(struct ssh *ssh, Session *s)
+{
+	int r;
+
+	if ((r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	channel_set_xtype(ssh, s->chanid, "session:shell");
+
+	return do_exec(ssh, s, NULL) == 0;
+}
+
+static int
+session_exec_req(struct ssh *ssh, Session *s)
+{
+	u_int success;
+	int r;
+	char *command = NULL;
+
+	if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	channel_set_xtype(ssh, s->chanid, "session:command");
+
+	success = do_exec(ssh, s, command) == 0;
+	free(command);
+	return success;
+}
+
+static int
+session_break_req(struct ssh *ssh, Session *s)
+{
+	int r;
+
+	if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) == -1)
+		return 0;
+	return 1;
+}
+
+static int
+session_env_req(struct ssh *ssh, Session *s)
+{
+	char *name, *val;
+	u_int i;
+	int r;
+
+	if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+	/* 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 = xrecallocarray(s->env, s->num_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:
+	free(name);
+	free(val);
+	return (0);
+}
+
+/*
+ * Conversion of signals from ssh channel request names.
+ * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as
+ * local extension.
+ */
+static int
+name2sig(char *name)
+{
+#define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x
+	SSH_SIG(HUP);
+	SSH_SIG(INT);
+	SSH_SIG(KILL);
+	SSH_SIG(QUIT);
+	SSH_SIG(TERM);
+	SSH_SIG(USR1);
+	SSH_SIG(USR2);
+#undef	SSH_SIG
+#ifdef SIGINFO
+	if (strcmp(name, "INFO@openssh.com") == 0)
+		return SIGINFO;
+#endif
+	return -1;
+}
+
+static int
+session_signal_req(struct ssh *ssh, Session *s)
+{
+	char *signame = NULL;
+	int r, sig, success = 0;
+
+	if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0) {
+		error_fr(r, "parse");
+		goto out;
+	}
+	if ((sig = name2sig(signame)) == -1) {
+		error_f("unsupported signal \"%s\"", signame);
+		goto out;
+	}
+	if (s->pid <= 0) {
+		error_f("no pid for session %d", s->self);
+		goto out;
+	}
+	if (s->forced || s->is_subsystem) {
+		error_f("refusing to send signal %s to %s session",
+		    signame, s->forced ? "forced-command" : "subsystem");
+		goto out;
+	}
+	if (!use_privsep || mm_is_monitor()) {
+		error_f("session signalling requires privilege separation");
+		goto out;
+	}
+
+	debug_f("signal %s, killpg(%ld, %d)", signame, (long)s->pid, sig);
+	temporarily_use_uid(s->pw);
+	r = killpg(s->pid, sig);
+	restore_uid();
+	if (r != 0) {
+		error_f("killpg(%ld, %d): %s", (long)s->pid,
+		    sig, strerror(errno));
+		goto out;
+	}
+
+	/* success */
+	success = 1;
+ out:
+	free(signame);
+	return success;
+}
+
+static int
+session_auth_agent_req(struct ssh *ssh, Session *s)
+{
+	static int called = 0;
+	int r;
+
+	if ((r = sshpkt_get_end(ssh)) != 0)
+		sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+	if (!auth_opts->permit_agent_forwarding_flag ||
+	    !options.allow_agent_forwarding) {
+		debug_f("agent forwarding disabled");
+		return 0;
+	}
+	if (called) {
+		return 0;
+	} else {
+		called = 1;
+		return auth_input_request_forwarding(ssh, s->pw);
+	}
+}
+
+int
+session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype)
+{
+	int success = 0;
+	Session *s;
+
+	if ((s = session_by_channel(c->self)) == NULL) {
+		logit_f("no session %d req %.100s", c->self, rtype);
+		return 0;
+	}
+	debug_f("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(ssh, s);
+		} else if (strcmp(rtype, "exec") == 0) {
+			success = session_exec_req(ssh, s);
+		} else if (strcmp(rtype, "pty-req") == 0) {
+			success = session_pty_req(ssh, s);
+		} else if (strcmp(rtype, "x11-req") == 0) {
+			success = session_x11_req(ssh, s);
+		} else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
+			success = session_auth_agent_req(ssh, s);
+		} else if (strcmp(rtype, "subsystem") == 0) {
+			success = session_subsystem_req(ssh, s);
+		} else if (strcmp(rtype, "env") == 0) {
+			success = session_env_req(ssh, s);
+		}
+	}
+	if (strcmp(rtype, "window-change") == 0) {
+		success = session_window_change_req(ssh, s);
+	} else if (strcmp(rtype, "break") == 0) {
+		success = session_break_req(ssh, s);
+	} else if (strcmp(rtype, "signal") == 0) {
+		success = session_signal_req(ssh, s);
+	}
+
+	return success;
+}
+
+void
+session_set_fds(struct ssh *ssh, Session *s,
+    int fdin, int fdout, int fderr, int ignore_fderr, int is_tty)
+{
+	/*
+	 * 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(ssh, s->chanid,
+	    fdout, fdin, fderr,
+	    ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
+	    1, is_tty, 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_f("no session");
+		return;
+	}
+	if (s->ttyfd == -1)
+		return;
+
+	debug_f("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 (s->ptymaster != -1 && close(s->ptymaster) == -1)
+		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(struct ssh *ssh, int id)
+{
+	Channel *c;
+
+	if ((c = channel_by_id(ssh, id)) == NULL) {
+		debug_f("x11 channel %d missing", id);
+	} else {
+		/* Detach X11 listener */
+		debug_f("detach x11 channel %d", id);
+		channel_cancel_cleanup(ssh, id);
+		if (c->ostate != CHAN_OUTPUT_CLOSED)
+			chan_mark_dead(ssh, c);
+	}
+}
+
+static void
+session_close_single_x11(struct ssh *ssh, int id, int force, void *arg)
+{
+	Session *s;
+	u_int i;
+
+	debug3_f("channel %d", id);
+	channel_cancel_cleanup(ssh, id);
+	if ((s = session_by_x11_channel(id)) == NULL)
+		fatal_f("no x11 channel %d", id);
+	for (i = 0; s->x11_chanids[i] != -1; i++) {
+		debug_f("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(ssh, s->x11_chanids[i]);
+	}
+	free(s->x11_chanids);
+	s->x11_chanids = NULL;
+	free(s->display);
+	s->display = NULL;
+	free(s->auth_proto);
+	s->auth_proto = NULL;
+	free(s->auth_data);
+	s->auth_data = NULL;
+	free(s->auth_display);
+	s->auth_display = NULL;
+}
+
+static void
+session_exit_message(struct ssh *ssh, Session *s, int status)
+{
+	Channel *c;
+	int r;
+
+	if ((c = channel_lookup(ssh, s->chanid)) == NULL)
+		fatal_f("session %d: no channel %d", s->self, s->chanid);
+	debug_f("session %d channel %d pid %ld",
+	    s->self, s->chanid, (long)s->pid);
+
+	if (WIFEXITED(status)) {
+		channel_request_start(ssh, s->chanid, "exit-status", 0);
+		if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: exit reply", __func__);
+	} else if (WIFSIGNALED(status)) {
+		channel_request_start(ssh, s->chanid, "exit-signal", 0);
+#ifndef WCOREDUMP
+# define WCOREDUMP(x) (0)
+#endif
+		if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 ||
+		    (r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			sshpkt_fatal(ssh, r, "%s: exit reply", __func__);
+	} else {
+		/* Some weird exit cause.  Just exit. */
+		ssh_packet_disconnect(ssh, "wait returned status %04x.", status);
+	}
+
+	/* disconnect channel */
+	debug_f("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 child sessions close their fds.
+	 */
+	channel_register_cleanup(ssh, 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(ssh, c);
+}
+
+void
+session_close(struct ssh *ssh, Session *s)
+{
+	u_int i;
+
+	verbose("Close session: user %s from %.200s port %d id %d",
+	    s->pw->pw_name,
+	    ssh_remote_ipaddr(ssh),
+	    ssh_remote_port(ssh),
+	    s->self);
+
+	if (s->ttyfd != -1)
+		session_pty_cleanup(s);
+	free(s->term);
+	free(s->display);
+	free(s->x11_chanids);
+	free(s->auth_display);
+	free(s->auth_data);
+	free(s->auth_proto);
+	free(s->subsys);
+	if (s->env != NULL) {
+		for (i = 0; i < s->num_env; i++) {
+			free(s->env[i].name);
+			free(s->env[i].val);
+		}
+		free(s->env);
+	}
+	session_proctitle(s);
+	session_unused(s->self);
+}
+
+void
+session_close_by_pid(struct ssh *ssh, pid_t pid, int status)
+{
+	Session *s = session_by_pid(pid);
+	if (s == NULL) {
+		debug_f("no session for pid %ld", (long)pid);
+		return;
+	}
+	if (s->chanid != -1)
+		session_exit_message(ssh, 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(struct ssh *ssh, int id, int force, void *arg)
+{
+	Session *s = session_by_channel(id);
+	u_int i;
+
+	if (s == NULL) {
+		debug_f("no session for id %d", id);
+		return;
+	}
+	debug_f("channel %d child %ld", id, (long)s->pid);
+	if (s->pid != 0) {
+		debug_f("channel %d: has child, ttyfd %d", id, s->ttyfd);
+		/*
+		 * delay detach of session (unless this is a forced close),
+		 * but release pty, since the fd's to the child are already
+		 * closed
+		 */
+		if (s->ttyfd != -1)
+			session_pty_cleanup(s);
+		if (!force)
+			return;
+	}
+	/* detach by removing callback */
+	channel_cancel_cleanup(ssh, 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(ssh, s->x11_chanids[i]);
+			s->x11_chanids[i] = -1;
+		}
+	}
+
+	s->chanid = -1;
+	session_close(ssh, s);
+}
+
+void
+session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *))
+{
+	int i;
+	for (i = 0; i < sessions_nalloc; i++) {
+		Session *s = &sessions[i];
+		if (s->used) {
+			if (closefunc != NULL)
+				closefunc(s);
+			else
+				session_close(ssh, s);
+		}
+	}
+}
+
+static char *
+session_tty_list(void)
+{
+	static char buf[1024];
+	int i;
+	char *cp;
+
+	buf[0] = '\0';
+	for (i = 0; i < sessions_nalloc; 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(struct ssh *ssh, Session *s)
+{
+	struct stat st;
+	char display[512], auth_display[512];
+	char hostname[NI_MAXHOST];
+	u_int i;
+
+	if (!auth_opts->permit_x11_forwarding_flag) {
+		ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options.");
+		return 0;
+	}
+	if (!options.x11_forwarding) {
+		debug("X11 forwarding disabled in server configuration file.");
+		return 0;
+	}
+	if (options.xauth_location == NULL ||
+	    (stat(options.xauth_location, &st) == -1)) {
+		ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11.");
+		return 0;
+	}
+	if (s->display != NULL) {
+		debug("X11 display already set.");
+		return 0;
+	}
+	if (x11_create_display_inet(ssh, 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(ssh, s->x11_chanids[i],
+		    session_close_single_x11, 0);
+	}
+
+	/* Set up a suitable value for the DISPLAY variable. */
+	if (gethostname(hostname, sizeof(hostname)) == -1)
+		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.");
+			ssh_packet_send_debug(ssh, "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(struct ssh *ssh, Authctxt *authctxt)
+{
+	server_loop2(ssh, authctxt);
+}
+
+void
+do_cleanup(struct ssh *ssh, 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)
+		return;
+
+#ifdef USE_PAM
+	if (options.use_pam) {
+		sshpam_cleanup();
+		sshpam_thread_cleanup();
+	}
+#endif
+
+	if (!authctxt->authenticated)
+		return;
+
+#ifdef KRB5
+	if (options.kerberos_ticket_cleanup &&
+	    authctxt->krb5_ctx)
+		krb5_cleanup_proc(authctxt);
+#endif
+
+#ifdef GSSAPI
+	if (options.gss_cleanup_creds)
+		ssh_gssapi_cleanup_creds();
+#endif
+
+	/* remove agent socket */
+	auth_sock_cleanup_proc(authctxt->pw);
+
+	/* remove userauth info */
+	if (auth_info_file != NULL) {
+		temporarily_use_uid(authctxt->pw);
+		unlink(auth_info_file);
+		restore_uid();
+		free(auth_info_file);
+		auth_info_file = NULL;
+	}
+
+	/*
+	 * Cleanup ptys/utmp only if privsep is disabled,
+	 * or if running in monitor.
+	 */
+	if (!use_privsep || mm_is_monitor())
+		session_destroy_all(ssh, session_pty_cleanup2);
+}
+
+/* Return a name for the remote host that fits inside utmp_size */
+
+const char *
+session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns)
+{
+	const char *remote = "";
+
+	if (utmp_size > 0)
+		remote = auth_get_canonical_hostname(ssh, use_dns);
+	if (utmp_size == 0 || strlen(remote) > utmp_size)
+		remote = ssh_remote_ipaddr(ssh);
+	return remote;
+}
+