X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/1d3c30dbe232d224145556c245d27d1be1e01a1e..c95add71a6006659751a44208b4ec0cedc82c0b0:/session.c

diff --git a/session.c b/session.c
index 13fe0187..fbdc419e 100644
--- a/session.c
+++ b/session.c
@@ -33,7 +33,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: session.c,v 1.67 2001/03/23 14:28:32 markus Exp $");
+RCSID("$OpenBSD: session.c,v 1.92 2001/06/19 15:40:45 markus Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -46,7 +46,6 @@ RCSID("$OpenBSD: session.c,v 1.67 2001/03/23 14:28:32 markus Exp $");
 #include "uidswap.h"
 #include "compat.h"
 #include "channels.h"
-#include "nchan.h"
 #include "bufaux.h"
 #include "auth.h"
 #include "auth-options.h"
@@ -122,12 +121,21 @@ struct Session {
 
 Session *session_new(void);
 void	session_set_fds(Session *s, int fdin, int fdout, int fderr);
-void	session_pty_cleanup(Session *s);
+void	session_pty_cleanup(void *session);
+int	session_pty_req(Session *s);
 void	session_proctitle(Session *s);
+int	session_setup_x11fwd(Session *s);
+void	session_close(Session *s);
 void	do_exec_pty(Session *s, const char *command);
 void	do_exec_no_pty(Session *s, const char *command);
+void	do_exec(Session *s, const char *command);
 void	do_login(Session *s, const char *command);
+#ifdef LOGIN_NEEDS_UTMPX
+void	do_pre_login(Session *s);
+#endif
 void	do_child(Session *s, const char *command);
+void	do_motd(void);
+int	check_quietlogin(Session *s, const char *command);
 
 void	do_authenticated1(Authctxt *authctxt);
 void	do_authenticated2(Authctxt *authctxt);
@@ -138,14 +146,11 @@ extern char *__progname;
 extern int log_stderr;
 extern int debug_flag;
 extern u_int utmp_len;
-
 extern int startup_pipe;
-
-/* Local Xauthority file. */
-static char *xauthfile;
+extern void destroy_sensitive_data(void);
 
 /* original command from peer. */
-char *original_command = NULL;
+const char *original_command = NULL;
 
 /* data */
 #define MAX_SESSIONS 10
@@ -177,6 +182,12 @@ do_authenticated(Authctxt *authctxt)
 		error("unable to get login class");
 		return;
 	}
+#ifdef BSD_AUTH
+	if (auth_approval(NULL, lc, authctxt->pw->pw_name, "ssh") <= 0) {
+		packet_disconnect("Approval failure for %s",
+		    authctxt->pw->pw_name);
+	}
+#endif
 #endif
 	/* setup the channel layer */
 	if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
@@ -186,48 +197,10 @@ do_authenticated(Authctxt *authctxt)
 		do_authenticated2(authctxt);
 	else
 		do_authenticated1(authctxt);
-}
 
-/*
- * Remove local Xauthority file.
- */
-void
-xauthfile_cleanup_proc(void *ignore)
-{
-	debug("xauthfile_cleanup_proc called");
-
-	if (xauthfile != NULL) {
-		char *p;
-		unlink(xauthfile);
-		p = strrchr(xauthfile, '/');
-		if (p != NULL) {
-			*p = '\0';
-			rmdir(xauthfile);
-		}
-		xfree(xauthfile);
-		xauthfile = NULL;
-	}
-}
-
-/*
- * Function to perform cleanup if we get aborted abnormally (e.g., due to a
- * dropped connection).
- */
-void
-pty_cleanup_proc(void *session)
-{
-	Session *s=session;
-	if (s == NULL)
-		fatal("pty_cleanup_proc: no session");
-	debug("pty_cleanup_proc: %s", s->tty);
-
-	if (s->pid != 0) {
-		/* Record that the user has logged out. */
-		record_logout(s->pid, s->tty);
-	}
-
-	/* Release the pseudo-tty. */
-	pty_release(s->tty);
+	/* remove agent socket */
+	if (auth_get_socket_name())
+		auth_sock_cleanup_proc(authctxt->pw);
 }
 
 /*
@@ -241,7 +214,7 @@ do_authenticated1(Authctxt *authctxt)
 {
 	Session *s;
 	char *command;
-	int success, type, fd, n_bytes, plen, screen_flag, have_pty = 0;
+	int success, type, plen, screen_flag;
 	int compression_level = 0, enable_compression_after_reply = 0;
 	u_int proto_len, data_len, dlen;
 
@@ -274,70 +247,10 @@ do_authenticated1(Authctxt *authctxt)
 			break;
 
 		case SSH_CMSG_REQUEST_PTY:
-			if (no_pty_flag) {
-				debug("Allocating a pty not permitted for this authentication.");
-				break;
-			}
-			if (have_pty)
-				packet_disconnect("Protocol error: you already have a pty.");
-
-			debug("Allocating pty.");
-
-			/* Allocate a pty and open it. */
-			if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty,
-			    sizeof(s->tty))) {
-				error("Failed to allocate pty.");
-				break;
-			}
-			fatal_add_cleanup(pty_cleanup_proc, (void *)s);
-			pty_setowner(s->pw, s->tty);
-
-			/* Get TERM from the packet.  Note that the value may be of arbitrary length. */
-			s->term = packet_get_string(&dlen);
-			packet_integrity_check(dlen, strlen(s->term), type);
-			/* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */
-			/* Remaining bytes */
-			n_bytes = plen - (4 + dlen + 4 * 4);
-
-			if (strcmp(s->term, "") == 0) {
-				xfree(s->term);
-				s->term = NULL;
-			}
-			/* Get window size from the packet. */
-			s->row = packet_get_int();
-			s->col = packet_get_int();
-			s->xpixel = packet_get_int();
-			s->ypixel = packet_get_int();
-			pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
-
-			/* Get tty modes from the packet. */
-			tty_parse_modes(s->ttyfd, &n_bytes);
-			packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type);
-
-			session_proctitle(s);
-
-			/* Indicate that we now have a pty. */
-			success = 1;
-			have_pty = 1;
+			success = session_pty_req(s);
 			break;
 
 		case SSH_CMSG_X11_REQUEST_FORWARDING:
-			if (!options.x11_forwarding) {
-				packet_send_debug("X11 forwarding disabled in server configuration file.");
-				break;
-			}
-			if (!options.xauth_location) {
-				packet_send_debug("No xauth program; cannot forward with spoofing.");
-				break;
-			}
-			if (no_x11_forwarding_flag) {
-				packet_send_debug("X11 forwarding not permitted for this authentication.");
-				break;
-			}
-			debug("Received request for X11 forwarding with auth spoofing.");
-			if (s->display != NULL)
-				packet_disconnect("Protocol error: X11 display already set.");
-
 			s->auth_proto = packet_get_string(&proto_len);
 			s->auth_data = packet_get_string(&data_len);
 
@@ -349,39 +262,18 @@ do_authenticated1(Authctxt *authctxt)
 				if (!screen_flag)
 					debug2("Buggy client: "
 					    "X11 screen flag missing");
-				packet_integrity_check(plen,
-				    4 + proto_len + 4 + data_len + 4, type);
 				s->screen = packet_get_int();
 			} else {
-				packet_integrity_check(plen,
-				    4 + proto_len + 4 + data_len, type);
 				s->screen = 0;
 			}
-			s->display = x11_create_display_inet(s->screen, options.x11_display_offset);
-
-			if (s->display == NULL)
-				break;
-
-			/* Setup to always have a local .Xauthority. */
-			xauthfile = xmalloc(MAXPATHLEN);
-			strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
-			temporarily_use_uid(s->pw->pw_uid);
-			if (mkdtemp(xauthfile) == NULL) {
-				restore_uid();
-				error("private X11 dir: mkdtemp %s failed: %s",
-				    xauthfile, strerror(errno));
-				xfree(xauthfile);
-				xauthfile = NULL;
-				/* XXXX remove listening channels */
-				break;
+			packet_done();
+			success = session_setup_x11fwd(s);
+			if (!success) {
+				xfree(s->auth_proto);
+				xfree(s->auth_data);
+				s->auth_proto = NULL;
+				s->auth_data = NULL;
 			}
-			strlcat(xauthfile, "/cookies", MAXPATHLEN);
-			fd = open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
-			if (fd >= 0)
-				close(fd);
-			restore_uid();
-			fatal_add_cleanup(xauthfile_cleanup_proc, NULL);
-			success = 1;
 			break;
 
 		case SSH_CMSG_AGENT_REQUEST_FORWARDING:
@@ -417,26 +309,13 @@ do_authenticated1(Authctxt *authctxt)
 			if (type == SSH_CMSG_EXEC_CMD) {
 				command = packet_get_string(&dlen);
 				debug("Exec command '%.500s'", command);
-				packet_integrity_check(plen, 4 + dlen, type);
+				do_exec(s, command);
+				xfree(command);
 			} else {
-				command = NULL;
-				packet_integrity_check(plen, 0, type);
+				do_exec(s, NULL);
 			}
-			if (forced_command != NULL) {
-				original_command = command;
-				command = forced_command;
-				debug("Forced command '%.500s'", forced_command);
-			}
-			if (have_pty)
-				do_exec_pty(s, command);
-			else
-				do_exec_no_pty(s, command);
-
-			if (command != NULL)
-				xfree(command);
-			/* Cleanup user's local Xauthority file. */
-			if (xauthfile)
-				xauthfile_cleanup_proc(NULL);
+			packet_done();
+			session_close(s);
 			return;
 
 		default:
@@ -488,7 +367,7 @@ do_exec_no_pty(Session *s, const char *command)
 	session_proctitle(s);
 
 #if defined(USE_PAM)
-	do_pam_setcred();
+	do_pam_setcred(1);
 #endif /* USE_PAM */
 
 	/* Fork the child. */
@@ -496,8 +375,6 @@ do_exec_no_pty(Session *s, const char *command)
 		/* Child.  Reinitialize the log since the pid has changed. */
 		log_init(__progname, options.log_level, options.log_facility, log_stderr);
 
-		signal(SIGPIPE, SIG_DFL);
-
 		/*
 		 * Create a new session and process group since the 4.4BSD
 		 * setlogin() affects the entire process group.
@@ -605,7 +482,7 @@ do_exec_pty(Session *s, const char *command)
 
 #if defined(USE_PAM)
 	do_pam_session(s->pw->pw_name, s->tty);
-	do_pam_setcred();
+	do_pam_setcred(1);
 #endif
 
 	/* Fork the child. */
@@ -613,8 +490,6 @@ do_exec_pty(Session *s, const char *command)
 		/* Child.  Reinitialize the log because the pid has changed. */
 		log_init(__progname, options.log_level, options.log_facility, log_stderr);
 
-		signal(SIGPIPE, SIG_DFL);
-
 		/* Close the master side of the pseudo tty. */
 		close(ptyfd);
 
@@ -637,8 +512,14 @@ do_exec_pty(Session *s, const char *command)
 		close(ttyfd);
 
 		/* record login, etc. similar to login(1) */
+#ifndef HAVE_OSF_SIA
 		if (!(options.use_login && command == NULL))
 			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);
@@ -677,32 +558,68 @@ do_exec_pty(Session *s, const char *command)
 	} else {
 		server_loop(pid, ptyfd, fdout, -1);
 		/* server_loop _has_ closed ptyfd and fdout. */
-		session_pty_cleanup(s);
 	}
 }
 
-const char *
-get_remote_name_or_ip(void)
+#ifdef LOGIN_NEEDS_UTMPX
+void
+do_pre_login(Session *s)
 {
-	static const char *remote = "";
-	if (utmp_len > 0)
-		remote = get_canonical_hostname(options.reverse_mapping_check);
-	if (utmp_len == 0 || strlen(remote) > utmp_len)
-		remote = get_remote_ipaddr();
-	return remote;
+	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));
+	if (packet_connection_is_on_socket()) {
+		fromlen = sizeof(from);
+		if (getpeername(packet_get_connection_in(),
+		     (struct sockaddr *) & from, &fromlen) < 0) {
+			debug("getpeername: %.100s", strerror(errno));
+			fatal_cleanup();
+		}
+	}
+
+	record_utmp_only(pid, s->tty, s->pw->pw_name,
+	    get_remote_name_or_ip(utmp_len, options.reverse_mapping_check),
+	    (struct sockaddr *)&from);
+}
+#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 (forced_command) {
+		original_command = command;
+		command = forced_command;
+		forced_command = NULL;
+		debug("Forced command '%.900s'", command);
+	}
+
+	if (s->ttyfd != -1)
+		do_exec_pty(s, command);
+	else
+		do_exec_no_pty(s, command);
+
+	original_command = NULL;
 }
 
+
 /* administrative, login(1)-like work */
 void
 do_login(Session *s, const char *command)
 {
-	FILE *f;
 	char *time_string;
-	char buf[256];
 	char hostname[MAXHOSTNAMELEN];
 	socklen_t fromlen;
 	struct sockaddr_storage from;
-	struct stat st;
 	time_t last_login_time;
 	struct passwd * pw = s->pw;
 	pid_t pid = getpid();
@@ -722,13 +639,16 @@ do_login(Session *s, const char *command)
 	}
 
 	/* Get the time and hostname when the user last logged in. */
-	hostname[0] = '\0';
-	last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name,
-	    hostname, sizeof(hostname));
+	if (options.print_lastlog) {
+		hostname[0] = '\0';
+		last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name,
+		    hostname, sizeof(hostname));
+	}
 
 	/* Record that there was a login on that tty from the remote host. */
 	record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
-	    get_remote_name_or_ip(), (struct sockaddr *)&from);
+	    get_remote_name_or_ip(utmp_len, options.reverse_mapping_check),
+	    (struct sockaddr *)&from);
 
 #ifdef USE_PAM
 	/*
@@ -741,15 +661,7 @@ do_login(Session *s, const char *command)
 	}
 #endif
 
-	/* Done if .hushlogin exists or a command given. */
-	if (command != NULL)
-		return;
-	snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
-#ifdef HAVE_LOGIN_CAP
-	if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
-#else
-	if (stat(buf, &st) >= 0)
-#endif
+	if (check_quietlogin(s, command))
 		return;
 
 #ifdef USE_PAM
@@ -761,7 +673,7 @@ do_login(Session *s, const char *command)
 		printf("%s\n", aixloginmsg);
 #endif /* WITH_AIXAUTHENTICATE */
 
-	if (last_login_time != 0) {
+	if (options.print_lastlog && last_login_time != 0) {
 		time_string = ctime(&last_login_time);
 		if (strchr(time_string, '\n'))
 			*strchr(time_string, '\n') = 0;
@@ -770,6 +682,19 @@ do_login(Session *s, const char *command)
 		else
 			printf("Last login: %s from %s\r\n", time_string, hostname);
 	}
+
+	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",
@@ -785,6 +710,31 @@ do_login(Session *s, const char *command)
 	}
 }
 
+
+/*
+ * 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.
@@ -1019,7 +969,7 @@ do_child(Session *s, const char *command)
 	extern char **environ;
 	struct stat st;
 	char *argv[10];
-	int do_xauth = s->auth_proto != NULL && s->auth_data != NULL;
+	int do_xauth;
 #ifdef WITH_IRIX_PROJECT
 	prid_t projid;
 #endif /* WITH_IRIX_PROJECT */
@@ -1031,11 +981,17 @@ do_child(Session *s, const char *command)
 #endif /* WITH_IRIX_ARRAY */
 #endif /* WITH_IRIX_JOBS */
 
+	do_xauth =
+	    s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
+
+	/* remove hostkey from the child's memory */
+	destroy_sensitive_data();
+
 	/* login(1) is only called if we execute the login shell */
 	if (options.use_login && command != NULL)
 		options.use_login = 0;
 
-#ifndef USE_PAM /* pam_nologin handles this */
+#if !defined(USE_PAM) && !defined(HAVE_OSF_SIA)
 	if (!options.use_login) {
 # ifdef HAVE_LOGIN_CAP
 		if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid)
@@ -1053,7 +1009,7 @@ do_child(Session *s, const char *command)
 			exit(254);
 		}
 	}
-#endif /* USE_PAM */
+#endif /* USE_PAM || HAVE_OSF_SIA */
 
 	/* Set login name, uid, gid, and groups. */
 	/* Login(1) does this as well, and it needs uid 0 for the "-h"
@@ -1061,6 +1017,8 @@ do_child(Session *s, const char *command)
 	if (!options.use_login) {
 #ifdef HAVE_OSF_SIA
 		session_setup_sia(pw->pw_name, s->ttyfd == -1 ? NULL : s->tty);
+		if (!check_quietlogin(s, command))
+			do_motd();
 #else /* HAVE_OSF_SIA */
 #ifdef HAVE_CYGWIN
 		if (is_winnt) {
@@ -1076,13 +1034,6 @@ do_child(Session *s, const char *command)
 				perror("unable to set user context");
 				exit(1);
 			}
-#ifdef BSD_AUTH
-			if (auth_approval(NULL, lc, pw->pw_name, "ssh") <= 0) {
-				error("approval failure for %s", pw->pw_name);
-				fprintf(stderr, "Approval failure");
-				exit(1);
-			}
-#endif
 # else /* HAVE_LOGIN_CAP */
 #if defined(HAVE_GETLUID) && defined(HAVE_SETLUID)
 			/* Sets login uid for accounting */
@@ -1102,6 +1053,15 @@ do_child(Session *s, const char *command)
 				exit(1);
 			}
 			endgrent();
+#  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.
+			 */
+			do_pam_setcred(0);
+#  endif /* USE_PAM */
 #  ifdef WITH_IRIX_JOBS
 			jid = jlimit_startjob(pw->pw_name, pw->pw_uid, "interactive");
 			if (jid == -1) {
@@ -1155,7 +1115,7 @@ do_child(Session *s, const char *command)
 #endif
 
 			/* Permanently switch to the desired uid. */
-			permanently_set_uid(pw->pw_uid);
+			permanently_set_uid(pw);
 # endif /* HAVE_LOGIN_CAP */
 		}
 #endif /* HAVE_OSF_SIA */
@@ -1281,8 +1241,6 @@ do_child(Session *s, const char *command)
 	do_pam_environment(&env, &envsize);
 #endif /* USE_PAM */
 
-	if (xauthfile)
-		child_set_env(&env, &envsize, "XAUTHORITY", xauthfile);
 	if (auth_get_socket_name() != NULL)
 		child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
 			      auth_get_socket_name());
@@ -1301,7 +1259,8 @@ do_child(Session *s, const char *command)
 	}
 	/* we have to stash the hostname before we close our socket. */
 	if (options.use_login)
-		hostname = get_remote_name_or_ip();
+		hostname = get_remote_name_or_ip(utmp_len,
+		    options.reverse_mapping_check);
 	/*
 	 * Close the connection descriptors; note that this is the child, and
 	 * the server will still have the socket open, and it is important
@@ -1358,24 +1317,25 @@ do_child(Session *s, const char *command)
 	 * in this order).
 	 */
 	if (!options.use_login) {
-		if (stat(_PATH_SSH_USER_RC, &st) >= 0) {
+		/* 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 %s\n", _PATH_BSHELL,
-				    _PATH_SSH_USER_RC);
-			f = popen(_PATH_BSHELL " " _PATH_SSH_USER_RC, "w");
+				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", 
+				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)
@@ -1477,6 +1437,9 @@ do_child(Session *s, const char *command)
 			/* Launch login(1). */
 
 			execl(LOGIN_PROGRAM, "login", "-h", hostname,
+#ifdef LOGIN_NEEDS_TERM
+			     s->term? s->term : "unknown",
+#endif
 			     "-p", "-f", "--", pw->pw_name, NULL);
 
 			/* Login couldn't be executed, die. */
@@ -1507,27 +1470,18 @@ session_new(void)
 		debug("session_new: init");
 		for(i = 0; i < MAX_SESSIONS; i++) {
 			sessions[i].used = 0;
-			sessions[i].self = i;
 		}
 		did_init = 1;
 	}
 	for(i = 0; i < MAX_SESSIONS; i++) {
 		Session *s = &sessions[i];
 		if (! s->used) {
-			s->pid = 0;
-			s->is_subsystem = 0;
+			memset(s, 0, sizeof(*s));
 			s->chanid = -1;
 			s->ptyfd = -1;
 			s->ttyfd = -1;
-			s->tty[0] = '\0';                                                       
-			s->term = NULL;
-			s->pw = NULL;
-			s->display = NULL;
-			s->screen = 0;
-			s->auth_data = NULL;
-			s->auth_proto = NULL;
 			s->used = 1;
-			s->pw = NULL;
+			s->self = i;
 			debug("session_new: session %d", i);
 			return s;
 		}
@@ -1614,48 +1568,64 @@ int
 session_pty_req(Session *s)
 {
 	u_int len;
-	char *term_modes;	/* encoded terminal modes */
+	int n_bytes;
 
-	if (no_pty_flag)
+	if (no_pty_flag) {
+		debug("Allocating a pty not permitted for this authentication.");
 		return 0;
-	if (s->ttyfd != -1)
+	}
+	if (s->ttyfd != -1) {
+		packet_disconnect("Protocol error: you already have a pty.");
 		return 0;
+	}
+
 	s->term = packet_get_string(&len);
-	s->col = packet_get_int();
-	s->row = packet_get_int();
+
+	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();
-	term_modes = packet_get_string(&len);
-	packet_done();
 
 	if (strcmp(s->term, "") == 0) {
 		xfree(s->term);
 		s->term = NULL;
 	}
+
 	/* Allocate a pty and open it. */
+	debug("Allocating pty.");
 	if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) {
-		xfree(s->term);
+		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);
-		xfree(term_modes);
 		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);
+
 	/*
 	 * Add a cleanup function to clear the utmp entry and record logout
 	 * time in case we call fatal() (e.g., the connection gets closed).
 	 */
-	fatal_add_cleanup(pty_cleanup_proc, (void *)s);
+	fatal_add_cleanup(session_pty_cleanup, (void *)s);
 	pty_setowner(s->pw, s->tty);
-	/* Get window size from the packet. */
+
+	/* Set window size from the packet. */
 	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
 
+	packet_done();
 	session_proctitle(s);
-
-	/* XXX parse and set terminal modes */
-	xfree(term_modes);
 	return 1;
 }
 
@@ -1689,23 +1659,7 @@ session_subsystem_req(Session *s)
 int
 session_x11_req(Session *s)
 {
-	int fd;
-	if (no_x11_forwarding_flag) {
-		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 (xauthfile != NULL) {
-		debug("X11 fwd already started.");
-		return 0;
-	}
-
-	debug("Received request for X11 forwarding with auth spoofing.");
-	if (s->display != NULL)
-		packet_disconnect("Protocol error: X11 display already set.");
+	int success;
 
 	s->single_connection = packet_get_char();
 	s->auth_proto = packet_get_string(NULL);
@@ -1713,45 +1667,21 @@ session_x11_req(Session *s)
 	s->screen = packet_get_int();
 	packet_done();
 
-	s->display = x11_create_display_inet(s->screen, options.x11_display_offset);
-	if (s->display == NULL) {
-		xfree(s->auth_proto);
-		xfree(s->auth_data);
-		return 0;
-	}
-	xauthfile = xmalloc(MAXPATHLEN);
-	strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
-	temporarily_use_uid(s->pw->pw_uid);
-	if (mkdtemp(xauthfile) == NULL) {
-		restore_uid();
-		error("private X11 dir: mkdtemp %s failed: %s",
-		    xauthfile, strerror(errno));
-		xfree(xauthfile);
-		xauthfile = NULL;
+	success = session_setup_x11fwd(s);
+	if (!success) {
 		xfree(s->auth_proto);
 		xfree(s->auth_data);
-		/* XXXX remove listening channels */
-		return 0;
+		s->auth_proto = NULL;
+		s->auth_data = NULL;
 	}
-	strlcat(xauthfile, "/cookies", MAXPATHLEN);
-	fd = open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
-	if (fd >= 0)
-		close(fd);
-	restore_uid();
-	fatal_add_cleanup(xauthfile_cleanup_proc, s);
-	return 1;
+	return success;
 }
 
 int
 session_shell_req(Session *s)
 {
-	/* if forced_command == NULL, the shell is execed */
-	char *shell = forced_command;
 	packet_done();
-	if (s->ttyfd == -1)
-		do_exec_no_pty(s, shell);
-	else
-		do_exec_pty(s, shell);
+	do_exec(s, NULL);
 	return 1;
 }
 
@@ -1761,17 +1691,8 @@ session_exec_req(Session *s)
 	u_int len;
 	char *command = packet_get_string(&len);
 	packet_done();
-	if (forced_command) {
-		original_command = command;
-		command = forced_command;
-		debug("Forced command '%.500s'", forced_command);
-	}
-	if (s->ttyfd == -1)
-		do_exec_no_pty(s, command);
-	else
-		do_exec_pty(s, command);
-	if (forced_command == NULL)
-		xfree(command);
+	do_exec(s, command);
+	xfree(command);
 	return 1;
 }
 
@@ -1864,19 +1785,27 @@ session_set_fds(Session *s, int fdin, int fdout, int fderr)
 	    1);
 }
 
+/*
+ * Function to perform pty cleanup. Also called if we get aborted abnormally
+ * (e.g., due to a dropped connection).
+ */
 void
-session_pty_cleanup(Session *s)
+session_pty_cleanup(void *session)
 {
-	if (s == NULL || s->ttyfd == -1)
+	Session *s = session;
+
+	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);
 
-	/* Cancel the cleanup function. */
-	fatal_remove_cleanup(pty_cleanup_proc, (void *)s);
-
 	/* Record that the user has logged out. */
-	record_logout(s->pid, s->tty);
+	if (s->pid != 0)
+		record_logout(s->pid, s->tty);
 
 	/* Release the pseudo-tty. */
 	pty_release(s->tty);
@@ -1898,7 +1827,7 @@ session_exit_message(Session *s, int status)
 		fatal("session_close: no session");
 	c = channel_lookup(s->chanid);
 	if (c == NULL)
-		fatal("session_close: session %d: no channel %d",
+		fatal("session_exit_message: session %d: no channel %d",
 		    s->self, s->chanid);
 	debug("session_exit_message: session %d channel %d pid %d",
 	    s->self, s->chanid, s->pid);
@@ -1940,9 +1869,13 @@ session_exit_message(Session *s, int status)
 }
 
 void
-session_free(Session *s)
+session_close(Session *s)
 {
-	debug("session_free: session %d pid %d", s->self, s->pid);
+	debug("session_close: session %d pid %d", s->self, s->pid);
+	if (s->ttyfd != -1) {
+		fatal_remove_cleanup(session_pty_cleanup, (void *)s);
+		session_pty_cleanup(s);
+	}
 	if (s->term)
 		xfree(s->term);
 	if (s->display)
@@ -1952,13 +1885,6 @@ session_free(Session *s)
 	if (s->auth_proto)
 		xfree(s->auth_proto);
 	s->used = 0;
-}
-
-void
-session_close(Session *s)
-{
-	session_pty_cleanup(s);
-	session_free(s);
 	session_proctitle(s);
 }
 
@@ -1967,7 +1893,7 @@ 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 %d", s->pid);
+		debug("session_close_by_pid: no session for pid %d", pid);
 		return;
 	}
 	if (s->chanid != -1)
@@ -2031,11 +1957,43 @@ session_proctitle(Session *s)
 		setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
 }
 
+int
+session_setup_x11fwd(Session *s)
+{
+	struct stat st;
+
+	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;
+	}
+	s->display = x11_create_display_inet(s->screen, options.x11_display_offset);
+	if (s->display == NULL) {
+		debug("x11_create_display_inet failed.");
+		return 0;
+	}
+	return 1;
+}
+
 void
 do_authenticated2(Authctxt *authctxt)
 {
-
 	server_loop2();
-	if (xauthfile)
-		xauthfile_cleanup_proc(NULL);
 }