1 /*
2 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
3 * All rights reserved
4 *
5 * As far as I am concerned, the code I have written for this software
6 * can be used freely for any purpose. Any derived versions of this
7 * software must be clearly marked as such, and if the derived work is
8 * incompatible with the protocol description in the RFC file, it must be
9 * called by a name other than "ssh" or "Secure Shell".
10 *
11 * SSH2 support by Markus Friedl.
12 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 */
34 /*
35 * Copyright 2010 Sun Microsystems, Inc. All rights reserved.
36 * Use is subject to license terms.
37 */
38 /*
39 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
40 */
41
42 #include "includes.h"
43 RCSID("$OpenBSD: session.c,v 1.150 2002/09/16 19:55:33 stevesk Exp $");
44
45 #ifdef HAVE_DEFOPEN
46 #include <deflt.h>
47 #include <ulimit.h>
48 #endif /* HAVE_DEFOPEN */
49
50 #ifdef HAVE_LIBGEN_H
51 #include <libgen.h>
52 #endif
53
54 #include <priv.h>
55
56 #include "ssh.h"
57 #include "ssh1.h"
58 #include "ssh2.h"
59 #include "xmalloc.h"
60 #include "sys-queue.h"
61 #include "sshpty.h"
62 #include "packet.h"
63 #include "buffer.h"
64 #include "mpaux.h"
65 #include "uidswap.h"
66 #include "compat.h"
67 #include "channels.h"
68 #include "bufaux.h"
69 #include "auth.h"
70 #include "auth-options.h"
71 #include "pathnames.h"
72 #include "log.h"
73 #include "servconf.h"
74 #include "sshlogin.h"
75 #include "serverloop.h"
76 #include "canohost.h"
77 #include "session.h"
78 #include "tildexpand.h"
79 #include "misc.h"
80 #include "sftp.h"
81
82 #ifdef USE_PAM
83 #include <security/pam_appl.h>
84 #endif /* USE_PAM */
85
86 #ifdef GSSAPI
87 #include "ssh-gss.h"
88 #endif
89
90 #ifdef ALTPRIVSEP
91 #include "altprivsep.h"
92 #endif /* ALTPRIVSEP */
93
94 #ifdef HAVE_CYGWIN
95 #include <windows.h>
96 #include <sys/cygwin.h>
97 #define is_winnt (GetVersion() < 0x80000000)
98 #endif
99
100 /* func */
101
102 Session *session_new(void);
103 void session_set_fds(Session *, int, int, int);
104 void session_pty_cleanup(void *);
105 void session_xauthfile_cleanup(void *s);
106 void session_proctitle(Session *);
107 int session_setup_x11fwd(Session *);
108 void do_exec_pty(Session *, const char *);
109 void do_exec_no_pty(Session *, const char *);
110 void do_exec(Session *, const char *);
111 void do_login(Session *, const char *);
112 void do_child(Session *, const char *);
113 void do_motd(void);
114 int check_quietlogin(Session *, const char *);
115
116 static void do_authenticated1(Authctxt *);
117 static void do_authenticated2(Authctxt *);
118
119 static int session_pty_req(Session *);
120 static int session_env_req(Session *s);
121 static void session_free_env(char ***envp);
122 static void safely_chroot(const char *path, uid_t uid);
123 static void drop_privs(uid_t uid);
124
125 #ifdef USE_PAM
126 static void session_do_pam(Session *, int);
127 #endif /* USE_PAM */
128
129 /* import */
130 extern ServerOptions options;
131 extern char *__progname;
132 extern int log_stderr;
133 extern int debug_flag;
134 extern u_int utmp_len;
135 extern void destroy_sensitive_data(void);
136
137 #ifdef GSSAPI
138 extern Gssctxt *xxx_gssctxt;
139 #endif /* GSSAPI */
140
141 /* original command from peer. */
142 const char *original_command = NULL;
143
144 /* data */
145 #define MAX_SESSIONS 10
146 static int sessions_next_id = 0;
147 static LIST_HEAD(sessions_head, Session) sessions =
148 LIST_HEAD_INITIALIZER(sessions);
149
150 #define SUBSYSTEM_NONE 0
151 #define SUBSYSTEM_EXT 1
152 #define SUBSYSTEM_INT_SFTP 2
153
154 #ifdef HAVE_LOGIN_CAP
155 login_cap_t *lc;
156 #endif
157
158 /* Name and directory of socket for authentication agent forwarding. */
159 static char *auth_sock_name = NULL;
160 static char *auth_sock_dir = NULL;
161
162 /* removes the agent forwarding socket */
163
164 static void
165 auth_sock_cleanup_proc(void *_pw)
166 {
167 struct passwd *pw = _pw;
168
169 if (auth_sock_name != NULL) {
170 temporarily_use_uid(pw);
171 unlink(auth_sock_name);
172 rmdir(auth_sock_dir);
173 auth_sock_name = NULL;
174 restore_uid();
175 }
176 }
177
178 static int
179 auth_input_request_forwarding(struct passwd * pw)
180 {
181 Channel *nc;
182 int sock;
183 struct sockaddr_un sunaddr;
184
185 if (auth_sock_name != NULL) {
186 error("authentication forwarding requested twice.");
187 return 0;
188 }
189
190 /* Temporarily drop privileged uid for mkdir/bind. */
191 temporarily_use_uid(pw);
192
193 /* Allocate a buffer for the socket name, and format the name. */
194 auth_sock_name = xmalloc(MAXPATHLEN);
195 auth_sock_dir = xmalloc(MAXPATHLEN);
196 strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
197
198 /* Create private directory for socket */
199 if (mkdtemp(auth_sock_dir) == NULL) {
200 packet_send_debug("Agent forwarding disabled: "
201 "mkdtemp() failed: %.100s", strerror(errno));
202 restore_uid();
203 xfree(auth_sock_name);
204 xfree(auth_sock_dir);
205 auth_sock_name = NULL;
206 auth_sock_dir = NULL;
207 return 0;
208 }
209 snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld",
210 auth_sock_dir, (long) getpid());
211
212 /* delete agent socket on fatal() */
213 fatal_add_cleanup(auth_sock_cleanup_proc, pw);
214
215 /* Create the socket. */
216 sock = socket(AF_UNIX, SOCK_STREAM, 0);
217 if (sock < 0)
218 packet_disconnect("socket: %.100s", strerror(errno));
219
220 /* Bind it to the name. */
221 memset(&sunaddr, 0, sizeof(sunaddr));
222 sunaddr.sun_family = AF_UNIX;
223 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path));
224
225 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
226 packet_disconnect("bind: %.100s", strerror(errno));
227
228 /* Restore the privileged uid. */
229 restore_uid();
230
231 /* Start listening on the socket. */
232 if (listen(sock, 5) < 0)
233 packet_disconnect("listen: %.100s", strerror(errno));
234
235 /* Allocate a channel for the authentication agent socket. */
236 nc = channel_new("auth socket",
237 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
238 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
239 0, xstrdup("auth socket"), 1);
240 strlcpy(nc->path, auth_sock_name, sizeof(nc->path));
241 return 1;
242 }
243
244
245 void
246 do_authenticated(Authctxt *authctxt)
247 {
248 /* setup the channel layer */
249 if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
250 channel_permit_all_opens();
251
252 if (compat20)
253 do_authenticated2(authctxt);
254 else
255 do_authenticated1(authctxt);
256
257 /* remove agent socket */
258 if (auth_sock_name != NULL)
259 auth_sock_cleanup_proc(authctxt->pw);
260 #ifdef KRB4
261 if (options.kerberos_ticket_cleanup)
262 krb4_cleanup_proc(authctxt);
263 #endif
264 #ifdef KRB5
265 if (options.kerberos_ticket_cleanup)
266 krb5_cleanup_proc(authctxt);
267 #endif
268 }
269
270 /*
271 * Prepares for an interactive session. This is called after the user has
272 * been successfully authenticated. During this message exchange, pseudo
273 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings
274 * are requested, etc.
275 */
276 static void
277 do_authenticated1(Authctxt *authctxt)
278 {
279 Session *s;
280 char *command;
281 int success, type, screen_flag;
282 int enable_compression_after_reply = 0;
283 u_int proto_len, data_len, dlen, compression_level = 0;
284
285 s = session_new();
286 s->authctxt = authctxt;
287 s->pw = authctxt->pw;
288
289 /*
290 * We stay in this loop until the client requests to execute a shell
291 * or a command.
292 */
293 for (;;) {
294 success = 0;
295
296 /* Get a packet from the client. */
297 type = packet_read();
298
299 /* Process the packet. */
300 switch (type) {
301 case SSH_CMSG_REQUEST_COMPRESSION:
302 compression_level = packet_get_int();
303 packet_check_eom();
304 if (compression_level < 1 || compression_level > 9) {
305 packet_send_debug("Received illegal compression level %d.",
306 compression_level);
307 break;
308 }
309 if (!options.compression) {
310 debug2("compression disabled");
311 break;
312 }
313 /* Enable compression after we have responded with SUCCESS. */
314 enable_compression_after_reply = 1;
315 success = 1;
316 break;
317
318 case SSH_CMSG_REQUEST_PTY:
319 success = session_pty_req(s);
320 break;
321
322 case SSH_CMSG_X11_REQUEST_FORWARDING:
323 s->auth_proto = packet_get_string(&proto_len);
324 s->auth_data = packet_get_string(&data_len);
325
326 screen_flag = packet_get_protocol_flags() &
327 SSH_PROTOFLAG_SCREEN_NUMBER;
328 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag);
329
330 if (packet_remaining() == 4) {
331 if (!screen_flag)
332 debug2("Buggy client: "
333 "X11 screen flag missing");
334 s->screen = packet_get_int();
335 } else {
336 s->screen = 0;
337 }
338 packet_check_eom();
339 success = session_setup_x11fwd(s);
340 if (!success) {
341 xfree(s->auth_proto);
342 xfree(s->auth_data);
343 s->auth_proto = NULL;
344 s->auth_data = NULL;
345 }
346 break;
347
348 case SSH_CMSG_AGENT_REQUEST_FORWARDING:
349 if (no_agent_forwarding_flag || compat13) {
350 debug("Authentication agent forwarding not permitted for this authentication.");
351 break;
352 }
353 debug("Received authentication agent forwarding request.");
354 success = auth_input_request_forwarding(s->pw);
355 break;
356
357 case SSH_CMSG_PORT_FORWARD_REQUEST:
358 if (no_port_forwarding_flag) {
359 debug("Port forwarding not permitted for this authentication.");
360 break;
361 }
362 if (!options.allow_tcp_forwarding) {
363 debug("Port forwarding not permitted.");
364 break;
365 }
366 debug("Received TCP/IP port forwarding request.");
367 channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports);
368 success = 1;
369 break;
370
371 case SSH_CMSG_MAX_PACKET_SIZE:
372 if (packet_set_maxsize(packet_get_int()) > 0)
373 success = 1;
374 break;
375
376 #if defined(AFS) || defined(KRB5)
377 case SSH_CMSG_HAVE_KERBEROS_TGT:
378 if (!options.kerberos_tgt_passing) {
379 verbose("Kerberos TGT passing disabled.");
380 } else {
381 char *kdata = packet_get_string(&dlen);
382 packet_check_eom();
383
384 /* XXX - 0x41, see creds_to_radix version */
385 if (kdata[0] != 0x41) {
386 #ifdef KRB5
387 krb5_data tgt;
388 tgt.data = kdata;
389 tgt.length = dlen;
390
391 if (auth_krb5_tgt(s->authctxt, &tgt))
392 success = 1;
393 else
394 verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user);
395 #endif /* KRB5 */
396 } else {
397 #ifdef AFS
398 if (auth_krb4_tgt(s->authctxt, kdata))
399 success = 1;
400 else
401 verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user);
402 #endif /* AFS */
403 }
404 xfree(kdata);
405 }
406 break;
407 #endif /* AFS || KRB5 */
408
409 #ifdef AFS
410 case SSH_CMSG_HAVE_AFS_TOKEN:
411 if (!options.afs_token_passing || !k_hasafs()) {
412 verbose("AFS token passing disabled.");
413 } else {
414 /* Accept AFS token. */
415 char *token = packet_get_string(&dlen);
416 packet_check_eom();
417
418 if (auth_afs_token(s->authctxt, token))
419 success = 1;
420 else
421 verbose("AFS token refused for %.100s",
422 s->authctxt->user);
423 xfree(token);
424 }
425 break;
426 #endif /* AFS */
427
428 case SSH_CMSG_EXEC_SHELL:
429 case SSH_CMSG_EXEC_CMD:
430 if (type == SSH_CMSG_EXEC_CMD) {
431 command = packet_get_string(&dlen);
432 debug("Exec command '%.500s'", command);
433 do_exec(s, command);
434 xfree(command);
435 } else {
436 do_exec(s, NULL);
437 }
438 packet_check_eom();
439 session_close(s);
440 return;
441
442 default:
443 /*
444 * Any unknown messages in this phase are ignored,
445 * and a failure message is returned.
446 */
447 log("Unknown packet type received after authentication: %d", type);
448 }
449 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
450 packet_send();
451 packet_write_wait();
452
453 /* Enable compression now that we have replied if appropriate. */
454 if (enable_compression_after_reply) {
455 enable_compression_after_reply = 0;
456 packet_start_compression(compression_level);
457 }
458 }
459 }
460
461 /*
462 * This is called to fork and execute a command when we have no tty. This
463 * will call do_child from the child, and server_loop from the parent after
464 * setting up file descriptors and such.
465 */
466 void
467 do_exec_no_pty(Session *s, const char *command)
468 {
469 pid_t pid;
470
471 int inout[2], err[2];
472 /* Uses socket pairs to communicate with the program. */
473 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 ||
474 socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0)
475 packet_disconnect("Could not create socket pairs: %.100s",
476 strerror(errno));
477 if (s == NULL)
478 fatal("do_exec_no_pty: no session");
479
480 session_proctitle(s);
481
482 /* Fork the child. */
483 if ((pid = fork()) == 0) {
484 fatal_remove_all_cleanups();
485
486 /* Child. Reinitialize the log since the pid has changed. */
487 log_init(__progname, options.log_level, options.log_facility, log_stderr);
488
489 /*
490 * Create a new session and process group since the 4.4BSD
491 * setlogin() affects the entire process group.
492 */
493 if (setsid() < 0)
494 error("setsid failed: %.100s", strerror(errno));
495
496 /*
497 * Redirect stdin, stdout, and stderr. Stdin and stdout will
498 * use the same socket, as some programs (particularly rdist)
499 * seem to depend on it.
500 */
501 close(inout[1]);
502 close(err[1]);
503 if (dup2(inout[0], 0) < 0) /* stdin */
504 perror("dup2 stdin");
505 if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */
506 perror("dup2 stdout");
507 if (s->is_subsystem) {
508 /*
509 * Redirect the subsystem's stderr to /dev/null. We might send it
510 * over to the other side but changing that might break existing
511 * SSH clients.
512 */
513 close(err[0]);
514 if ((err[0] = open(_PATH_DEVNULL, O_WRONLY)) == -1)
515 fatal("Cannot open /dev/null: %.100s", strerror(errno));
516 }
517 if (dup2(err[0], 2) < 0) /* stderr */
518 perror("dup2 stderr");
519
520 #ifdef _UNICOS
521 cray_init_job(s->pw); /* set up cray jid and tmpdir */
522 #endif
523
524 /* Do processing for the child (exec command etc). */
525 do_child(s, command);
526 /* NOTREACHED */
527 }
528 #ifdef _UNICOS
529 signal(WJSIGNAL, cray_job_termination_handler);
530 #endif /* _UNICOS */
531 #ifdef HAVE_CYGWIN
532 if (is_winnt)
533 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
534 #endif
535 if (pid < 0)
536 packet_disconnect("fork failed: %.100s", strerror(errno));
537
538 s->pid = pid;
539 /* Set interactive/non-interactive mode. */
540 packet_set_interactive(s->display != NULL);
541
542 /* We are the parent. Close the child sides of the socket pairs. */
543 close(inout[0]);
544 close(err[0]);
545
546 /*
547 * Enter the interactive session. Note: server_loop must be able to
548 * handle the case that fdin and fdout are the same.
549 */
550 if (compat20) {
551 session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]);
552 if (s->is_subsystem)
553 close(err[1]);
554 /* Don't close channel before sending exit-status! */
555 channel_set_wait_for_exit(s->chanid, 1);
556 } else {
557 server_loop(pid, inout[1], inout[1], err[1]);
558 /* server_loop has closed inout[1] and err[1]. */
559 }
560 }
561
562 /*
563 * This is called to fork and execute a command when we have a tty. This
564 * will call do_child from the child, and server_loop from the parent after
565 * setting up file descriptors, controlling tty, updating wtmp, utmp,
566 * lastlog, and other such operations.
567 */
568 void
569 do_exec_pty(Session *s, const char *command)
570 {
571 int fdout, ptyfd, ttyfd, ptymaster, pipe_fds[2];
572 pid_t pid;
573
574 if (s == NULL)
575 fatal("do_exec_pty: no session");
576 ptyfd = s->ptyfd;
577 ttyfd = s->ttyfd;
578
579 #ifdef USE_PAM
580 session_do_pam(s, 1); /* pam_open_session() */
581 #endif /* USE_PAM */
582
583 /*
584 * This pipe lets sshd wait for child to exec or exit. This is
585 * particularly important for ALTPRIVSEP because the child is
586 * the one to call the monitor to request a record_login() and
587 * we don't want the child and the parent to compete for the
588 * monitor's attention. But this is generic code and doesn't
589 * hurt to have here even if ALTPRIVSEP is not used.
590 */
591 if (pipe(pipe_fds) != 0)
592 packet_disconnect("pipe failed: %.100s", strerror(errno));
593
594 (void) fcntl(pipe_fds[0], F_SETFD, FD_CLOEXEC);
595 (void) fcntl(pipe_fds[1], F_SETFD, FD_CLOEXEC);
596
597 /* Fork the child. */
598 if ((pid = fork()) == 0) {
599 (void) close(pipe_fds[0]);
600
601 fatal_remove_all_cleanups();
602
603 /* Child. Reinitialize the log because the pid has changed. */
604 log_init(__progname, options.log_level, options.log_facility, log_stderr);
605 /* Close the master side of the pseudo tty. */
606 close(ptyfd);
607
608 /* Make the pseudo tty our controlling tty. */
609 pty_make_controlling_tty(&ttyfd, s->tty);
610
611 /* Redirect stdin/stdout/stderr from the pseudo tty. */
612 if (dup2(ttyfd, 0) < 0)
613 error("dup2 stdin: %s", strerror(errno));
614 if (dup2(ttyfd, 1) < 0)
615 error("dup2 stdout: %s", strerror(errno));
616 if (dup2(ttyfd, 2) < 0)
617 error("dup2 stderr: %s", strerror(errno));
618
619 /* Close the extra descriptor for the pseudo tty. */
620 close(ttyfd);
621
622 /* record login, etc. similar to login(1) */
623 do_login(s, command);
624
625 /*
626 * Close the pipe to the parent so it can re-enter its event
627 * loop and service the ptm; if enough debug messages get
628 * written to the pty before this happens there will be a
629 * deadlock.
630 */
631 close(pipe_fds[1]);
632
633 /*
634 * do_motd() was called originally in do_login(). However,
635 * when the /etc/motd file is large, a deadlock would happen,
636 * because
637 * - The child is blocked at fputs() to pty, when pty buffer
638 * is full.
639 * - The parent can not consume the pty buffer, because it is
640 * still blocked at read(pipe_fds[0]).
641 *
642 * To resolve the deadlock issue, we defer do_motd() after
643 * close(pipe_fds[1]).
644 */
645 do_motd();
646
647 /* Do common processing for the child, such as execing the command. */
648 do_child(s, command);
649 /* NOTREACHED */
650 }
651
652 /* Wait for child to exec() or exit() */
653 (void) close(pipe_fds[1]);
654 (void) read(pipe_fds[0], &pipe_fds[1], sizeof(int));
655
656 #ifdef _UNICOS
657 signal(WJSIGNAL, cray_job_termination_handler);
658 #endif /* _UNICOS */
659 #ifdef HAVE_CYGWIN
660 if (is_winnt)
661 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
662 #endif
663 if (pid < 0)
664 packet_disconnect("fork failed: %.100s", strerror(errno));
665 s->pid = pid;
666
667 /* Parent. Close the slave side of the pseudo tty. */
668 close(ttyfd);
669
670 /*
671 * Create another descriptor of the pty master side for use as the
672 * standard input. We could use the original descriptor, but this
673 * simplifies code in server_loop. The descriptor is bidirectional.
674 */
675 fdout = dup(ptyfd);
676 if (fdout < 0)
677 packet_disconnect("dup #1 failed: %.100s", strerror(errno));
678
679 /* we keep a reference to the pty master */
680 ptymaster = dup(ptyfd);
681 if (ptymaster < 0)
682 packet_disconnect("dup #2 failed: %.100s", strerror(errno));
683 s->ptymaster = ptymaster;
684
685 /* Enter interactive session. */
686 packet_set_interactive(1);
687 if (compat20) {
688 session_set_fds(s, ptyfd, fdout, -1);
689 /* Don't close channel before sending exit-status! */
690 channel_set_wait_for_exit(s->chanid, 1);
691 } else {
692 server_loop(pid, ptyfd, fdout, -1);
693 /* server_loop _has_ closed ptyfd and fdout. */
694 }
695 }
696
697 /*
698 * This is called to fork and execute a command. If another command is
699 * to be forced, execute that instead.
700 */
701 void
702 do_exec(Session *s, const char *command)
703 {
704 if (command)
705 s->command = xstrdup(command);
706
707 if (forced_command) {
708 original_command = command;
709 command = forced_command;
710 debug("Forced command '%.900s'", command);
711 }
712
713 if (s->ttyfd != -1)
714 do_exec_pty(s, command);
715 else
716 do_exec_no_pty(s, command);
717
718 original_command = NULL;
719 }
720
721
722 /* administrative, login(1)-like work */
723 void
724 do_login(Session *s, const char *command)
725 {
726 char *time_string;
727 #ifndef ALTPRIVSEP
728 struct passwd * pw = s->pw;
729 #endif /* ALTPRIVSEP*/
730 pid_t pid = getpid();
731
732 /* Record that there was a login on that tty from the remote host. */
733 #ifdef ALTPRIVSEP
734 debug3("Recording SSHv2 channel login in utmpx/wtmpx");
735 altprivsep_record_login(pid, s->tty);
736 #endif /* ALTPRIVSEP*/
737
738 if (check_quietlogin(s, command))
739 return;
740
741 #ifdef USE_PAM
742 print_pam_messages();
743 #endif /* USE_PAM */
744 #ifdef WITH_AIXAUTHENTICATE
745 if (aixloginmsg && *aixloginmsg)
746 printf("%s\n", aixloginmsg);
747 #endif /* WITH_AIXAUTHENTICATE */
748
749 #ifndef NO_SSH_LASTLOG
750 if (options.print_lastlog && s->last_login_time != 0) {
751 time_string = ctime(&s->last_login_time);
752 if (strchr(time_string, '\n'))
753 *strchr(time_string, '\n') = 0;
754 if (strcmp(s->hostname, "") == 0)
755 printf("Last login: %s\r\n", time_string);
756 else
757 printf("Last login: %s from %s\r\n", time_string,
758 s->hostname);
759 }
760 #endif /* NO_SSH_LASTLOG */
761
762 }
763
764 /*
765 * Display the message of the day.
766 */
767 void
768 do_motd(void)
769 {
770 FILE *f;
771 char buf[256];
772
773 if (options.print_motd) {
774 #ifdef HAVE_LOGIN_CAP
775 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd",
776 "/etc/motd"), "r");
777 #else
778 f = fopen("/etc/motd", "r");
779 #endif
780 if (f) {
781 while (fgets(buf, sizeof(buf), f))
782 fputs(buf, stdout);
783 fclose(f);
784 }
785 }
786 }
787
788
789 /*
790 * Check for quiet login, either .hushlogin or command given.
791 */
792 int
793 check_quietlogin(Session *s, const char *command)
794 {
795 char buf[256];
796 struct passwd *pw = s->pw;
797 struct stat st;
798
799 /* Return 1 if .hushlogin exists or a command given. */
800 if (command != NULL)
801 return 1;
802 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
803 #ifdef HAVE_LOGIN_CAP
804 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
805 return 1;
806 #else
807 if (stat(buf, &st) >= 0)
808 return 1;
809 #endif
810 return 0;
811 }
812
813 /*
814 * Sets the value of the given variable in the environment. If the variable
815 * already exists, its value is overriden.
816 */
817 void
818 child_set_env(char ***envp, u_int *envsizep, const char *name,
819 const char *value)
820 {
821 debug3("child_set_env(%s, %s)", name, value);
822 child_set_env_silent(envp, envsizep, name, value);
823 }
824
825
826 void
827 child_set_env_silent(char ***envp, u_int *envsizep, const char *name,
828 const char *value)
829 {
830 u_int i, namelen;
831 char **env;
832
833 /*
834 * Find the slot where the value should be stored. If the variable
835 * already exists, we reuse the slot; otherwise we append a new slot
836 * at the end of the array, expanding if necessary.
837 */
838 env = *envp;
839 namelen = strlen(name);
840 for (i = 0; env[i]; i++)
841 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
842 break;
843 if (env[i]) {
844 /* Reuse the slot. */
845 xfree(env[i]);
846 } else {
847 /* New variable. Expand if necessary. */
848 if (i >= (*envsizep) - 1) {
849 if (*envsizep >= 1000)
850 fatal("child_set_env: too many env vars,"
851 " skipping: %.100s", name);
852 (*envsizep) += 50;
853 env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *));
854 }
855 /* Need to set the NULL pointer at end of array beyond the new slot. */
856 env[i + 1] = NULL;
857 }
858
859 /* Allocate space and format the variable in the appropriate slot. */
860 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
861 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
862 }
863
864 /*
865 * Reads environment variables from the given file and adds/overrides them
866 * into the environment. If the file does not exist, this does nothing.
867 * Otherwise, it must consist of empty lines, comments (line starts with '#')
868 * and assignments of the form name=value. No other forms are allowed.
869 */
870 static void
871 read_environment_file(char ***env, u_int *envsize,
872 const char *filename)
873 {
874 FILE *f;
875 char buf[4096];
876 char *cp, *value;
877 u_int lineno = 0;
878
879 f = fopen(filename, "r");
880 if (!f)
881 return;
882
883 while (fgets(buf, sizeof(buf), f)) {
884 if (++lineno > 1000)
885 fatal("Too many lines in environment file %s", filename);
886 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
887 ;
888 if (!*cp || *cp == '#' || *cp == '\n')
889 continue;
890 if (strchr(cp, '\n'))
891 *strchr(cp, '\n') = '\0';
892 value = strchr(cp, '=');
893 if (value == NULL) {
894 fprintf(stderr, gettext("Bad line %u in %.100s\n"),
895 lineno, filename);
896 continue;
897 }
898 /*
899 * Replace the equals sign by nul, and advance value to
900 * the value string.
901 */
902 *value = '\0';
903 value++;
904 child_set_env(env, envsize, cp, value);
905 }
906 fclose(f);
907 }
908
909 void copy_environment(char **source, char ***env, u_int *envsize)
910 {
911 char *var_name, *var_val;
912 int i;
913
914 if (source == NULL)
915 return;
916
917 for(i = 0; source[i] != NULL; i++) {
918 var_name = xstrdup(source[i]);
919 if ((var_val = strstr(var_name, "=")) == NULL) {
920 xfree(var_name);
921 continue;
922 }
923 *var_val++ = '\0';
924
925 debug3("Copy environment: %s=%s", var_name, var_val);
926 child_set_env(env, envsize, var_name, var_val);
927
928 xfree(var_name);
929 }
930 }
931
932 #ifdef HAVE_DEFOPEN
933 static
934 void
935 deflt_do_setup_env(Session *s, const char *shell, char ***env, u_int *envsize)
936 {
937 int flags;
938 char *ptr;
939 mode_t Umask = 022;
940
941 if (defopen(_PATH_DEFAULT_LOGIN))
942 return;
943
944 /* Ignore case */
945 flags = defcntl(DC_GETFLAGS, 0);
946 TURNOFF(flags, DC_CASE);
947 (void) defcntl(DC_SETFLAGS, flags);
948
949 /* TZ & HZ */
950 if ((ptr = defread("TIMEZONE=")) != NULL)
951 child_set_env(env, envsize, "TZ", ptr);
952 if ((ptr = defread("HZ=")) != NULL)
953 child_set_env(env, envsize, "HZ", ptr);
954
955 /* PATH */
956 if (s->pw->pw_uid != 0 && (ptr = defread("PATH=")) != NULL)
957 child_set_env(env, envsize, "PATH", ptr);
958 if (s->pw->pw_uid == 0 && (ptr = defread("SUPATH=")) != NULL)
959 child_set_env(env, envsize, "PATH", ptr);
960
961 /* SHELL */
962 if ((ptr = defread("ALTSHELL=")) != NULL) {
963 if (strcasecmp("YES", ptr) == 0)
964 child_set_env(env, envsize, "SHELL", shell);
965 else
966 child_set_env(env, envsize, "SHELL", "");
967 }
968
969 /* UMASK */
970 if ((ptr = defread("UMASK=")) != NULL &&
971 sscanf(ptr, "%lo", &Umask) == 1 &&
972 Umask <= (mode_t)0777)
973 (void) umask(Umask);
974 else
975 (void) umask(022);
976
977 /* ULIMIT */
978 if ((ptr = defread("ULIMIT=")) != NULL && atol(ptr) > 0L &&
979 ulimit(UL_SETFSIZE, atol(ptr)) < 0L)
980 error("Could not set ULIMIT to %ld from %s\n", atol(ptr),
981 _PATH_DEFAULT_LOGIN);
982
983 (void) defopen(NULL);
984 }
985 #endif /* HAVE_DEFOPEN */
986
987 static char **
988 do_setup_env(Session *s, const char *shell)
989 {
990 char buf[256];
991 char path_maildir[] = _PATH_MAILDIR;
992 u_int i, envsize, pm_len;
993 char **env;
994 struct passwd *pw = s->pw;
995
996 /* Initialize the environment. */
997 envsize = 100;
998 env = xmalloc(envsize * sizeof(char *));
999 env[0] = NULL;
1000
1001 #ifdef HAVE_CYGWIN
1002 /*
1003 * The Windows environment contains some setting which are
1004 * important for a running system. They must not be dropped.
1005 */
1006 copy_environment(environ, &env, &envsize);
1007 #endif
1008
1009 #ifdef GSSAPI
1010 /* Allow any GSSAPI methods that we've used to alter
1011 * the childs environment as they see fit
1012 */
1013 ssh_gssapi_do_child(xxx_gssctxt, &env,&envsize);
1014 #endif
1015
1016 /* Set basic environment. */
1017 child_set_env(&env, &envsize, "USER", pw->pw_name);
1018 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
1019 child_set_env(&env, &envsize, "HOME", pw->pw_dir);
1020 #ifdef HAVE_LOGIN_CAP
1021 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0)
1022 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
1023 else
1024 child_set_env(&env, &envsize, "PATH", getenv("PATH"));
1025 #else /* HAVE_LOGIN_CAP */
1026 # ifndef HAVE_CYGWIN
1027 /*
1028 * There's no standard path on Windows. The path contains
1029 * important components pointing to the system directories,
1030 * needed for loading shared libraries. So the path better
1031 * remains intact here.
1032 */
1033 # ifdef SUPERUSER_PATH
1034 child_set_env(&env, &envsize, "PATH",
1035 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH);
1036 # else
1037 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
1038 # endif /* SUPERUSER_PATH */
1039 # endif /* HAVE_CYGWIN */
1040 #endif /* HAVE_LOGIN_CAP */
1041
1042 pm_len = strlen(path_maildir);
1043 if (path_maildir[pm_len - 1] == '/' && pm_len > 1)
1044 path_maildir[pm_len - 1] = NULL;
1045 snprintf(buf, sizeof buf, "%.200s/%.50s",
1046 path_maildir, pw->pw_name);
1047 child_set_env(&env, &envsize, "MAIL", buf);
1048
1049 /* Normal systems set SHELL by default. */
1050 child_set_env(&env, &envsize, "SHELL", shell);
1051
1052 #ifdef HAVE_DEFOPEN
1053 deflt_do_setup_env(s, shell, &env, &envsize);
1054 #endif /* HAVE_DEFOPEN */
1055
1056 #define PASS_ENV(x) \
1057 if (getenv(x)) \
1058 child_set_env(&env, &envsize, x, getenv(x));
1059
1060 if (getenv("TZ"))
1061 child_set_env(&env, &envsize, "TZ", getenv("TZ"));
1062
1063 if (s->auth_file != NULL)
1064 child_set_env(&env, &envsize, "XAUTHORITY", s->auth_file);
1065
1066 PASS_ENV("LANG")
1067 PASS_ENV("LC_ALL")
1068 PASS_ENV("LC_CTYPE")
1069 PASS_ENV("LC_COLLATE")
1070 PASS_ENV("LC_TIME")
1071 PASS_ENV("LC_NUMERIC")
1072 PASS_ENV("LC_MONETARY")
1073 PASS_ENV("LC_MESSAGES")
1074
1075 #undef PASS_ENV
1076
1077 if (s->env != NULL)
1078 copy_environment(s->env, &env, &envsize);
1079
1080 /* Set custom environment options from RSA authentication. */
1081 while (custom_environment) {
1082 struct envstring *ce = custom_environment;
1083 char *str = ce->s;
1084
1085 for (i = 0; str[i] != '=' && str[i]; i++)
1086 ;
1087 if (str[i] == '=') {
1088 str[i] = 0;
1089 child_set_env(&env, &envsize, str, str + i + 1);
1090 }
1091 custom_environment = ce->next;
1092 xfree(ce->s);
1093 xfree(ce);
1094 }
1095
1096 /* SSH_CLIENT deprecated */
1097 snprintf(buf, sizeof buf, "%.50s %d %d",
1098 get_remote_ipaddr(), get_remote_port(), get_local_port());
1099 child_set_env(&env, &envsize, "SSH_CLIENT", buf);
1100
1101 snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
1102 get_remote_ipaddr(), get_remote_port(),
1103 get_local_ipaddr(packet_get_connection_in()), get_local_port());
1104 child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
1105
1106 if (s->ttyfd != -1)
1107 child_set_env(&env, &envsize, "SSH_TTY", s->tty);
1108 if (s->term)
1109 child_set_env(&env, &envsize, "TERM", s->term);
1110 if (s->display)
1111 child_set_env(&env, &envsize, "DISPLAY", s->display);
1112 if (original_command)
1113 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
1114 original_command);
1115
1116 #ifdef _UNICOS
1117 if (cray_tmpdir[0] != '\0')
1118 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir);
1119 #endif /* _UNICOS */
1120
1121 #ifdef _AIX
1122 {
1123 char *cp;
1124
1125 if ((cp = getenv("AUTHSTATE")) != NULL)
1126 child_set_env(&env, &envsize, "AUTHSTATE", cp);
1127 if ((cp = getenv("KRB5CCNAME")) != NULL)
1128 child_set_env(&env, &envsize, "KRB5CCNAME", cp);
1129 read_environment_file(&env, &envsize, "/etc/environment");
1130 }
1131 #endif
1132 #ifdef KRB4
1133 if (s->authctxt->krb4_ticket_file)
1134 child_set_env(&env, &envsize, "KRBTKFILE",
1135 s->authctxt->krb4_ticket_file);
1136 #endif
1137 #ifdef KRB5
1138 if (s->authctxt->krb5_ticket_file)
1139 child_set_env(&env, &envsize, "KRB5CCNAME",
1140 s->authctxt->krb5_ticket_file);
1141 #endif
1142 #ifdef USE_PAM
1143 /*
1144 * Pull in any environment variables that may have
1145 * been set by PAM.
1146 */
1147 {
1148 char **p;
1149
1150 p = fetch_pam_environment(s->authctxt);
1151 copy_environment(p, &env, &envsize);
1152 free_pam_environment(p);
1153 }
1154 #endif /* USE_PAM */
1155
1156 if (auth_sock_name != NULL)
1157 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
1158 auth_sock_name);
1159
1160 /* read $HOME/.ssh/environment. */
1161 if (options.permit_user_env) {
1162 snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
1163 strcmp(pw->pw_dir, "/") ? pw->pw_dir : "");
1164 read_environment_file(&env, &envsize, buf);
1165 }
1166 if (debug_flag) {
1167 /* dump the environment */
1168 fprintf(stderr, gettext("Environment:\n"));
1169 for (i = 0; env[i]; i++)
1170 fprintf(stderr, " %.200s\n", env[i]);
1171 }
1172 return env;
1173 }
1174
1175 /*
1176 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found
1177 * first in this order).
1178 */
1179 static void
1180 do_rc_files(Session *s, const char *shell)
1181 {
1182 FILE *f = NULL;
1183 char cmd[1024];
1184 int do_xauth;
1185 struct stat st;
1186
1187 do_xauth =
1188 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
1189
1190 /* ignore _PATH_SSH_USER_RC for subsystems */
1191 if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) {
1192 snprintf(cmd, sizeof cmd, "%s -c '%s %s'",
1193 shell, _PATH_BSHELL, _PATH_SSH_USER_RC);
1194 if (debug_flag)
1195 fprintf(stderr, "Running %s\n", cmd);
1196 f = popen(cmd, "w");
1197 if (f) {
1198 if (do_xauth)
1199 fprintf(f, "%s %s\n", s->auth_proto,
1200 s->auth_data);
1201 pclose(f);
1202 } else
1203 fprintf(stderr, "Could not run %s\n",
1204 _PATH_SSH_USER_RC);
1205 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) {
1206 if (debug_flag)
1207 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
1208 _PATH_SSH_SYSTEM_RC);
1209 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w");
1210 if (f) {
1211 if (do_xauth)
1212 fprintf(f, "%s %s\n", s->auth_proto,
1213 s->auth_data);
1214 pclose(f);
1215 } else
1216 fprintf(stderr, "Could not run %s\n",
1217 _PATH_SSH_SYSTEM_RC);
1218 } else if (do_xauth && options.xauth_location != NULL) {
1219 /* Add authority data to .Xauthority if appropriate. */
1220 if (debug_flag) {
1221 fprintf(stderr,
1222 "Running %.500s add "
1223 "%.100s %.100s %.100s\n",
1224 options.xauth_location, s->auth_display,
1225 s->auth_proto, s->auth_data);
1226 }
1227 snprintf(cmd, sizeof cmd, "%s -q -",
1228 options.xauth_location);
1229 f = popen(cmd, "w");
1230 if (f) {
1231 fprintf(f, "add %s %s %s\n",
1232 s->auth_display, s->auth_proto,
1233 s->auth_data);
1234 pclose(f);
1235 } else {
1236 fprintf(stderr, "Could not run %s\n",
1237 cmd);
1238 }
1239 }
1240 }
1241
1242 /* Disallow logins if /etc/nologin exists. This does not apply to root. */
1243 static void
1244 do_nologin(struct passwd *pw)
1245 {
1246 FILE *f = NULL;
1247 char buf[1024];
1248 struct stat sb;
1249
1250 if (pw->pw_uid == 0)
1251 return;
1252
1253 if (stat(_PATH_NOLOGIN, &sb) == -1)
1254 return;
1255
1256 /* /etc/nologin exists. Print its contents if we can and exit. */
1257 log("User %.100s not allowed because %s exists.", pw->pw_name,
1258 _PATH_NOLOGIN);
1259 if ((f = fopen(_PATH_NOLOGIN, "r")) != NULL) {
1260 while (fgets(buf, sizeof(buf), f))
1261 fputs(buf, stderr);
1262 fclose(f);
1263 }
1264 exit(254);
1265 }
1266
1267 /* Chroot into ChrootDirectory if the option is set. */
1268 void
1269 chroot_if_needed(struct passwd *pw)
1270 {
1271 char *chroot_path, *tmp;
1272
1273 if (chroot_requested(options.chroot_directory)) {
1274 tmp = tilde_expand_filename(options.chroot_directory,
1275 pw->pw_uid);
1276 chroot_path = percent_expand(tmp, "h", pw->pw_dir,
1277 "u", pw->pw_name, (char *)NULL);
1278 safely_chroot(chroot_path, pw->pw_uid);
1279 free(tmp);
1280 free(chroot_path);
1281 }
1282 }
1283
1284 /*
1285 * Chroot into a directory after checking it for safety: all path components
1286 * must be root-owned directories with strict permissions.
1287 */
1288 static void
1289 safely_chroot(const char *path, uid_t uid)
1290 {
1291 const char *cp;
1292 char component[MAXPATHLEN];
1293 struct stat st;
1294
1295 if (*path != '/')
1296 fatal("chroot path does not begin at root");
1297 if (strlen(path) >= sizeof(component))
1298 fatal("chroot path too long");
1299
1300 /*
1301 * Descend the path, checking that each component is a
1302 * root-owned directory with strict permissions.
1303 */
1304 for (cp = path; cp != NULL;) {
1305 if ((cp = strchr(cp, '/')) == NULL)
1306 strlcpy(component, path, sizeof(component));
1307 else {
1308 cp++;
1309 memcpy(component, path, cp - path);
1310 component[cp - path] = '\0';
1311 }
1312
1313 debug3("%s: checking '%s'", __func__, component);
1314
1315 if (stat(component, &st) != 0)
1316 fatal("%s: stat(\"%s\"): %s", __func__,
1317 component, strerror(errno));
1318 if (st.st_uid != 0 || (st.st_mode & 022) != 0)
1319 fatal("bad ownership or modes for chroot "
1320 "directory %s\"%s\"",
1321 cp == NULL ? "" : "component ", component);
1322 if (!S_ISDIR(st.st_mode))
1323 fatal("chroot path %s\"%s\" is not a directory",
1324 cp == NULL ? "" : "component ", component);
1325 }
1326
1327 if (chdir(path) == -1)
1328 fatal("Unable to chdir to chroot path \"%s\": "
1329 "%s", path, strerror(errno));
1330 if (chroot(path) == -1)
1331 fatal("chroot(\"%s\"): %s", path, strerror(errno));
1332 if (chdir("/") == -1)
1333 fatal("%s: chdir(/) after chroot: %s",
1334 __func__, strerror(errno));
1335 verbose("Changed root directory to \"%s\"", path);
1336 }
1337
1338 static void
1339 launch_login(struct passwd *pw, const char *hostname)
1340 {
1341 /* Launch login(1). */
1342
1343 execl(LOGIN_PROGRAM, "login", "-h", hostname,
1344 #ifdef xxxLOGIN_NEEDS_TERM
1345 (s->term ? s->term : "unknown"),
1346 #endif /* LOGIN_NEEDS_TERM */
1347 #ifdef LOGIN_NO_ENDOPT
1348 "-p", "-f", pw->pw_name, (char *)NULL);
1349 #else
1350 "-p", "-f", "--", pw->pw_name, (char *)NULL);
1351 #endif
1352
1353 /* Login couldn't be executed, die. */
1354
1355 perror("login");
1356 exit(1);
1357 }
1358
1359 /*
1360 * Performs common processing for the child, such as setting up the
1361 * environment, closing extra file descriptors, setting the user and group
1362 * ids, and executing the command or shell.
1363 */
1364 #define ARGV_MAX 10
1365 void
1366 do_child(Session *s, const char *command)
1367 {
1368 extern char **environ;
1369 char **env;
1370 char *argv[ARGV_MAX];
1371 const char *shell, *shell0;
1372 struct passwd *pw = s->pw;
1373
1374 /* remove hostkey from the child's memory */
1375 destroy_sensitive_data();
1376
1377 do_nologin(pw);
1378 chroot_if_needed(pw);
1379
1380 /*
1381 * Get the shell from the password data. An empty shell field is
1382 * legal, and means /bin/sh.
1383 */
1384 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
1385 #ifdef HAVE_LOGIN_CAP
1386 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
1387 #endif
1388
1389 env = do_setup_env(s, shell);
1390
1391 /*
1392 * Close the connection descriptors; note that this is the child, and
1393 * the server will still have the socket open, and it is important
1394 * that we do not shutdown it. Note that the descriptors cannot be
1395 * closed before building the environment, as we call
1396 * get_remote_ipaddr there.
1397 */
1398 if (packet_get_connection_in() == packet_get_connection_out())
1399 close(packet_get_connection_in());
1400 else {
1401 close(packet_get_connection_in());
1402 close(packet_get_connection_out());
1403 }
1404 /*
1405 * Close all descriptors related to channels. They will still remain
1406 * open in the parent.
1407 */
1408 /* XXX better use close-on-exec? -markus */
1409 channel_close_all();
1410
1411 /*
1412 * Close any extra file descriptors. Note that there may still be
1413 * descriptors left by system functions. They will be closed later.
1414 */
1415 endpwent();
1416
1417 /*
1418 * Must switch to the new environment variables so that .ssh/rc,
1419 * /etc/ssh/sshrc, and xauth are run in the proper environment.
1420 */
1421 environ = env;
1422
1423 /*
1424 * New environment has been installed. We need to update locale
1425 * so that error messages beyond this point have the proper
1426 * character encoding.
1427 */
1428 (void) setlocale(LC_ALL, "");
1429
1430 /*
1431 * Close any extra open file descriptors so that we don\'t have them
1432 * hanging around in clients. Note that we want to do this after
1433 * initgroups, because at least on Solaris 2.3 it leaves file
1434 * descriptors open.
1435 */
1436 closefrom(STDERR_FILENO + 1);
1437
1438 #ifdef AFS
1439 /* Try to get AFS tokens for the local cell. */
1440 if (k_hasafs()) {
1441 char cell[64];
1442
1443 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
1444 krb_afslog(cell, 0);
1445
1446 krb_afslog(0, 0);
1447 }
1448 #endif /* AFS */
1449
1450 /* Change current directory to the user's home directory. */
1451 if (chdir(pw->pw_dir) < 0) {
1452 /* Suppress missing homedir warning for chroot case */
1453 if (!chroot_requested(options.chroot_directory))
1454 fprintf(stderr, "Could not chdir to home "
1455 "directory %s: %s\n", pw->pw_dir,
1456 strerror(errno));
1457 }
1458
1459 do_rc_files(s, shell);
1460
1461 /* restore SIGPIPE for child */
1462 signal(SIGPIPE, SIG_DFL);
1463
1464 if (s->is_subsystem == SUBSYSTEM_INT_SFTP) {
1465 int i;
1466 char *p, *args;
1467 extern int optind, optreset;
1468
1469 /* This will set the E/P sets here, simulating exec(2). */
1470 drop_privs(pw->pw_uid);
1471
1472 setproctitle("%s@internal-sftp-server", s->pw->pw_name);
1473 args = xstrdup(command ? command : "sftp-server");
1474
1475 i = 0;
1476 for ((p = strtok(args, " ")); p != NULL; (p = strtok(NULL, " "))) {
1477 if (i < ARGV_MAX - 1)
1478 argv[i++] = p;
1479 }
1480
1481 argv[i] = NULL;
1482 optind = optreset = 1;
1483 __progname = argv[0];
1484 exit(sftp_server_main(i, argv, s->pw));
1485 }
1486
1487 /* Get the last component of the shell name. */
1488 if ((shell0 = strrchr(shell, '/')) != NULL)
1489 shell0++;
1490 else
1491 shell0 = shell;
1492
1493 /*
1494 * If we have no command, execute the shell. In this case, the shell
1495 * name to be passed in argv[0] is preceded by '-' to indicate that
1496 * this is a login shell.
1497 */
1498 if (!command) {
1499 char argv0[256];
1500
1501 /* Start the shell. Set initial character to '-'. */
1502 argv0[0] = '-';
1503
1504 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1)
1505 >= sizeof(argv0) - 1) {
1506 errno = EINVAL;
1507 perror(shell);
1508 exit(1);
1509 }
1510
1511 /* Execute the shell. */
1512 argv[0] = argv0;
1513 argv[1] = NULL;
1514 execve(shell, argv, env);
1515
1516 /* Executing the shell failed. */
1517 perror(shell);
1518 exit(1);
1519 }
1520 /*
1521 * Execute the command using the user's shell. This uses the -c
1522 * option to execute the command.
1523 */
1524 argv[0] = (char *) shell0;
1525 argv[1] = "-c";
1526 argv[2] = (char *) command;
1527 argv[3] = NULL;
1528 execve(shell, argv, env);
1529 perror(shell);
1530 exit(1);
1531 }
1532
1533 Session *
1534 session_new(void)
1535 {
1536 Session *s;
1537
1538 debug("session_new: init");
1539
1540 s = xmalloc(sizeof (*s));
1541 memset(s, 0, sizeof(*s));
1542 s->chanid = -1;
1543 s->ptyfd = -1;
1544 s->ttyfd = -1;
1545 s->self = sessions_next_id++;
1546 s->env = NULL;
1547 LIST_INSERT_HEAD(&sessions, s, list_entry);
1548
1549 debug("session_new: session %d", s->self);
1550
1551 return (s);
1552 }
1553
1554 static void
1555 session_dump(void)
1556 {
1557 Session *s;
1558 LIST_FOREACH(s, &sessions, list_entry) {
1559 debug("dump: session %d %p channel %d pid %ld",
1560 s->self,
1561 s,
1562 s->chanid,
1563 (long)s->pid);
1564 }
1565 }
1566
1567 int
1568 session_open(Authctxt *authctxt, int chanid)
1569 {
1570 Session *s = session_new();
1571 debug("session_open: channel %d", chanid);
1572 if (s == NULL) {
1573 error("no more sessions");
1574 return 0;
1575 }
1576 s->authctxt = authctxt;
1577 s->pw = authctxt->pw;
1578 if (s->pw == NULL)
1579 fatal("no user for session %d", s->self);
1580 debug("session_open: session %d: link with channel %d", s->self, chanid);
1581 s->chanid = chanid;
1582 return 1;
1583 }
1584
1585 #ifndef lint
1586 Session *
1587 session_by_tty(char *tty)
1588 {
1589 Session *s;
1590 LIST_FOREACH(s, &sessions, list_entry) {
1591 if (s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
1592 debug("session_by_tty: session %d tty %s", s->self, tty);
1593 return s;
1594 }
1595 }
1596 debug("session_by_tty: unknown tty %.100s", tty);
1597 session_dump();
1598 return NULL;
1599 }
1600 #endif /* lint */
1601
1602 static Session *
1603 session_by_channel(int id)
1604 {
1605 Session *s;
1606 LIST_FOREACH(s, &sessions, list_entry) {
1607 if (s->chanid == id) {
1608 debug("session_by_channel: session %d channel %d", s->self, id);
1609 return s;
1610 }
1611 }
1612 debug("session_by_channel: unknown channel %d", id);
1613 session_dump();
1614 return NULL;
1615 }
1616
1617 static Session *
1618 session_by_pid(pid_t pid)
1619 {
1620 Session *s;
1621 debug("session_by_pid: pid %ld", (long)pid);
1622 LIST_FOREACH(s, &sessions, list_entry) {
1623 if (s->pid == pid)
1624 return s;
1625 }
1626 error("session_by_pid: unknown pid %ld", (long)pid);
1627 session_dump();
1628 return NULL;
1629 }
1630
1631 static int
1632 session_window_change_req(Session *s)
1633 {
1634 s->col = packet_get_int();
1635 s->row = packet_get_int();
1636 s->xpixel = packet_get_int();
1637 s->ypixel = packet_get_int();
1638 packet_check_eom();
1639 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
1640 return 1;
1641 }
1642
1643 static int
1644 session_pty_req(Session *s)
1645 {
1646 u_int len;
1647 int n_bytes;
1648
1649 if (no_pty_flag) {
1650 debug("Allocating a pty not permitted for this authentication.");
1651 return 0;
1652 }
1653 if (s->ttyfd != -1) {
1654 packet_disconnect("Protocol error: you already have a pty.");
1655 return 0;
1656 }
1657 /* Get the time and hostname when the user last logged in. */
1658 if (options.print_lastlog) {
1659 s->hostname[0] = '\0';
1660 s->last_login_time = get_last_login_time(s->pw->pw_uid,
1661 s->pw->pw_name, s->hostname, sizeof(s->hostname));
1662
1663 /*
1664 * PAM may update the last login date.
1665 *
1666 * Ideally PAM would also show the last login date as a
1667 * PAM_TEXT_INFO conversation message, and then we could just
1668 * always force the use of keyboard-interactive just so we can
1669 * pass any such PAM prompts and messages from the account and
1670 * session stacks, but skip pam_authenticate() if other userauth
1671 * has succeeded and the user's password isn't expired.
1672 *
1673 * Unfortunately this depends on support for keyboard-
1674 * interactive in the client, and support for lastlog messages
1675 * in some PAM module.
1676 *
1677 * As it is Solaris updates the lastlog in PAM, but does
1678 * not show the lastlog date in PAM. If and when this state of
1679 * affairs changes this hack can be reconsidered, and, maybe,
1680 * removed.
1681 *
1682 * So we're stuck with a crude hack: get the lastlog
1683 * time before calling pam_open_session() and store it
1684 * in the Authctxt and then use it here once. After
1685 * that, if the client opens any more pty sessions we'll
1686 * show the last lastlog entry since userauth.
1687 */
1688 if (s->authctxt != NULL && s->authctxt->last_login_time > 0) {
1689 s->last_login_time = s->authctxt->last_login_time;
1690 (void) strlcpy(s->hostname,
1691 s->authctxt->last_login_host,
1692 sizeof(s->hostname));
1693 s->authctxt->last_login_time = 0;
1694 s->authctxt->last_login_host[0] = '\0';
1695 }
1696 }
1697
1698 s->term = packet_get_string(&len);
1699
1700 if (compat20) {
1701 s->col = packet_get_int();
1702 s->row = packet_get_int();
1703 } else {
1704 s->row = packet_get_int();
1705 s->col = packet_get_int();
1706 }
1707 s->xpixel = packet_get_int();
1708 s->ypixel = packet_get_int();
1709
1710 if (strcmp(s->term, "") == 0) {
1711 xfree(s->term);
1712 s->term = NULL;
1713 }
1714
1715 /* Allocate a pty and open it. */
1716 debug("Allocating pty.");
1717 if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) {
1718 if (s->term)
1719 xfree(s->term);
1720 s->term = NULL;
1721 s->ptyfd = -1;
1722 s->ttyfd = -1;
1723 error("session_pty_req: session %d alloc failed", s->self);
1724 return 0;
1725 }
1726 debug("session_pty_req: session %d alloc %s", s->self, s->tty);
1727
1728 /* for SSH1 the tty modes length is not given */
1729 if (!compat20)
1730 n_bytes = packet_remaining();
1731 tty_parse_modes(s->ttyfd, &n_bytes);
1732
1733 /*
1734 * Add a cleanup function to clear the utmp entry and record logout
1735 * time in case we call fatal() (e.g., the connection gets closed).
1736 */
1737 fatal_add_cleanup(session_pty_cleanup, (void *)s);
1738 pty_setowner(s->pw, s->tty);
1739
1740 /* Set window size from the packet. */
1741 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
1742
1743 packet_check_eom();
1744 session_proctitle(s);
1745 return 1;
1746 }
1747
1748 static int
1749 session_subsystem_req(Session *s)
1750 {
1751 struct stat st;
1752 u_int len;
1753 int success = 0;
1754 char *prog, *cmd, *subsys = packet_get_string(&len);
1755 u_int i;
1756
1757 packet_check_eom();
1758 log("subsystem request for %.100s", subsys);
1759
1760 for (i = 0; i < options.num_subsystems; i++) {
1761 if (strcmp(subsys, options.subsystem_name[i]) == 0) {
1762 prog = options.subsystem_command[i];
1763 cmd = options.subsystem_args[i];
1764 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) {
1765 s->is_subsystem = SUBSYSTEM_INT_SFTP;
1766 /*
1767 * We must stat(2) the subsystem before we chroot in
1768 * order to be able to send a proper error message.
1769 */
1770 } else if (chroot_requested(options.chroot_directory)) {
1771 char chdirsub[MAXPATHLEN];
1772
1773 strlcpy(chdirsub, options.chroot_directory,
1774 sizeof (chdirsub));
1775 strlcat(chdirsub, "/", sizeof (chdirsub));
1776 strlcat(chdirsub, prog, sizeof (chdirsub));
1777 if (stat(chdirsub, &st) < 0) {
1778 error("subsystem: cannot stat %s under "
1779 "chroot directory %s: %s", prog,
1780 options.chroot_directory,
1781 strerror(errno));
1782 if (strcmp(subsys, "sftp") == 0)
1783 error("subsystem: please see "
1784 "the Subsystem option in "
1785 "sshd_config(4) for an "
1786 "explanation of '%s'.",
1787 INTERNAL_SFTP_NAME);
1788 break;
1789 }
1790 } else if (stat(prog, &st) < 0) {
1791 error("subsystem: cannot stat %s: %s", prog,
1792 strerror(errno));
1793 break;
1794 } else {
1795 s->is_subsystem = SUBSYSTEM_EXT;
1796 }
1797 debug("subsystem: exec() %s", cmd);
1798 do_exec(s, cmd);
1799 success = 1;
1800 break;
1801 }
1802 }
1803
1804 if (!success)
1805 log("subsystem request for %.100s failed, subsystem not found",
1806 subsys);
1807
1808 xfree(subsys);
1809 return success;
1810 }
1811
1812 /*
1813 * Serve "x11-req" channel request for X11 forwarding for the current session
1814 * channel.
1815 */
1816 static int
1817 session_x11_req(Session *s)
1818 {
1819 int success, fd;
1820 char xauthdir[] = "/tmp/ssh-xauth-XXXXXX";
1821
1822 s->single_connection = packet_get_char();
1823 s->auth_proto = packet_get_string(NULL);
1824 s->auth_data = packet_get_string(NULL);
1825 s->screen = packet_get_int();
1826 packet_check_eom();
1827
1828 success = session_setup_x11fwd(s);
1829 if (!success) {
1830 xfree(s->auth_proto);
1831 xfree(s->auth_data);
1832 s->auth_proto = NULL;
1833 s->auth_data = NULL;
1834 return (success);
1835 }
1836
1837 /*
1838 * Create per session X authority file so that different sessions
1839 * don't contend for one common file. The reason for this is that
1840 * xauth(1) locking doesn't work too well over network filesystems.
1841 *
1842 * If mkdtemp() or open() fails then s->auth_file remains NULL which
1843 * means that we won't set XAUTHORITY variable in child's environment
1844 * and xauth(1) will use the default location for the authority file.
1845 */
1846 if (mkdtemp(xauthdir) != NULL) {
1847 s->auth_file = xmalloc(MAXPATHLEN);
1848 snprintf(s->auth_file, MAXPATHLEN, "%s/xauthfile",
1849 xauthdir);
1850 /*
1851 * we don't want that "creating new authority file" message to
1852 * be printed by xauth(1) so we must create that file
1853 * beforehand.
1854 */
1855 if ((fd = open(s->auth_file, O_CREAT | O_EXCL | O_RDONLY,
1856 S_IRUSR | S_IWUSR)) == -1) {
1857 error("failed to create the temporary X authority "
1858 "file %s: %.100s; will use the default one",
1859 s->auth_file, strerror(errno));
1860 xfree(s->auth_file);
1861 s->auth_file = NULL;
1862 if (rmdir(xauthdir) == -1) {
1863 error("cannot remove xauth directory %s: %.100s",
1864 xauthdir, strerror(errno));
1865 }
1866 } else {
1867 close(fd);
1868 debug("temporary X authority file %s created",
1869 s->auth_file);
1870
1871 /*
1872 * add a cleanup function to remove the temporary
1873 * xauth file in case we call fatal() (e.g., the
1874 * connection gets closed).
1875 */
1876 fatal_add_cleanup(session_xauthfile_cleanup, (void *)s);
1877 }
1878 }
1879 else {
1880 error("failed to create a directory for the temporary X "
1881 "authority file: %.100s; will use the default xauth file",
1882 strerror(errno));
1883 }
1884
1885 return (success);
1886 }
1887
1888 static int
1889 session_shell_req(Session *s)
1890 {
1891 packet_check_eom();
1892 do_exec(s, NULL);
1893 return 1;
1894 }
1895
1896 static int
1897 session_exec_req(Session *s)
1898 {
1899 u_int len;
1900 char *command = packet_get_string(&len);
1901 packet_check_eom();
1902 do_exec(s, command);
1903 xfree(command);
1904 return 1;
1905 }
1906
1907 static int
1908 session_auth_agent_req(Session *s)
1909 {
1910 static int called = 0;
1911 packet_check_eom();
1912 if (no_agent_forwarding_flag) {
1913 debug("session_auth_agent_req: no_agent_forwarding_flag");
1914 return 0;
1915 }
1916 if (called) {
1917 return 0;
1918 } else {
1919 called = 1;
1920 return auth_input_request_forwarding(s->pw);
1921 }
1922 }
1923
1924 static int
1925 session_loc_env_check(char *var, char *val)
1926 {
1927 char *current;
1928 int cat, ret;
1929
1930 if (strcmp(var, "LANG") == 0)
1931 cat = LC_ALL;
1932 else if (strcmp(var, "LC_ALL") == 0)
1933 cat = LC_ALL;
1934 else if (strcmp(var, "LC_CTYPE") == 0)
1935 cat = LC_CTYPE;
1936 else if (strcmp(var, "LC_COLLATE") == 0)
1937 cat = LC_COLLATE;
1938 else if (strcmp(var, "LC_TIME") == 0)
1939 cat = LC_TIME;
1940 else if (strcmp(var, "LC_NUMERIC") == 0)
1941 cat = LC_NUMERIC;
1942 else if (strcmp(var, "LC_MONETARY") == 0)
1943 cat = LC_MONETARY;
1944 else if (strcmp(var, "LC_MESSAGES") == 0)
1945 cat = LC_MESSAGES;
1946
1947 current = setlocale(cat, NULL);
1948
1949 ret = (setlocale(cat, val) != NULL);
1950 (void) setlocale(cat, current);
1951 return (ret);
1952 }
1953
1954 static int
1955 session_env_req(Session *s)
1956 {
1957 Channel *c;
1958 char *var, *val, *e;
1959 char **p;
1960 size_t len;
1961 int ret = 0;
1962
1963 /* Get var/val from the rest of this packet */
1964 var = packet_get_string(NULL);
1965 val = packet_get_string(NULL);
1966
1967 /*
1968 * We'll need the channel ID for the packet_send_debug messages,
1969 * so get it now.
1970 */
1971 if ((c = channel_lookup(s->chanid)) == NULL)
1972 goto done; /* shouldn't happen! */
1973
1974 debug2("Received request for environment variable %s=%s", var, val);
1975
1976 /* For now allow only LANG and LC_* */
1977 if (strcmp(var, "LANG") != 0 && strncmp(var, "LC_", 3) != 0) {
1978 debug2("Rejecting request for environment variable %s", var);
1979 goto done;
1980 }
1981
1982 if (!session_loc_env_check(var, val)) {
1983 packet_send_debug(gettext("Missing locale support for %s=%s"),
1984 var, val);
1985 goto done;
1986 }
1987
1988 packet_send_debug(gettext("Channel %d set: %s=%s"), c->remote_id,
1989 var, val);
1990
1991 /*
1992 * Always append new environment variables without regard to old
1993 * ones being overriden. The way these are actually added to
1994 * the environment of the session process later settings
1995 * override earlier ones; see copy_environment().
1996 */
1997 if (s->env == NULL) {
1998 char **env;
1999
2000 env = xmalloc(sizeof (char **) * 2);
2001 memset(env, 0, sizeof (char **) * 2);
2002
2003 s->env = env;
2004 p = env;
2005 } else {
2006 for (p = s->env; *p != NULL ; p++);
2007
2008 s->env = xrealloc(s->env, (p - s->env + 2) * sizeof (char **));
2009
2010 for (p = s->env; *p != NULL ; p++);
2011 }
2012
2013 len = snprintf(NULL, 0, "%s=%s", var, val);
2014 e = xmalloc(len + 1);
2015 (void) snprintf(e, len + 1, "%s=%s", var, val);
2016
2017 (*p++) = e;
2018 *p = NULL;
2019
2020 ret = 1;
2021
2022 done:
2023 xfree(var);
2024 xfree(val);
2025
2026 return (ret);
2027 }
2028
2029 static void
2030 session_free_env(char ***envp)
2031 {
2032 char **env, **p;
2033
2034 if (envp == NULL || *envp == NULL)
2035 return;
2036
2037 env = *envp;
2038
2039 *envp = NULL;
2040
2041 for (p = env; *p != NULL; p++)
2042 xfree(*p);
2043
2044 xfree(env);
2045 }
2046
2047 int
2048 session_input_channel_req(Channel *c, const char *rtype)
2049 {
2050 int success = 0;
2051 Session *s;
2052
2053 if ((s = session_by_channel(c->self)) == NULL) {
2054 log("session_input_channel_req: no session %d req %.100s",
2055 c->self, rtype);
2056 return 0;
2057 }
2058 debug("session_input_channel_req: session %d req %s", s->self, rtype);
2059
2060 /*
2061 * a session is in LARVAL state until a shell, a command
2062 * or a subsystem is executed
2063 */
2064 if (c->type == SSH_CHANNEL_LARVAL) {
2065 if (strcmp(rtype, "shell") == 0) {
2066 success = session_shell_req(s);
2067 } else if (strcmp(rtype, "exec") == 0) {
2068 success = session_exec_req(s);
2069 } else if (strcmp(rtype, "pty-req") == 0) {
2070 success = session_pty_req(s);
2071 } else if (strcmp(rtype, "x11-req") == 0) {
2072 success = session_x11_req(s);
2073 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
2074 success = session_auth_agent_req(s);
2075 } else if (strcmp(rtype, "subsystem") == 0) {
2076 success = session_subsystem_req(s);
2077 } else if (strcmp(rtype, "env") == 0) {
2078 success = session_env_req(s);
2079 }
2080 }
2081 if (strcmp(rtype, "window-change") == 0) {
2082 success = session_window_change_req(s);
2083 }
2084 return success;
2085 }
2086
2087 void
2088 session_set_fds(Session *s, int fdin, int fdout, int fderr)
2089 {
2090 if (!compat20)
2091 fatal("session_set_fds: called for proto != 2.0");
2092 /*
2093 * now that have a child and a pipe to the child,
2094 * we can activate our channel and register the fd's
2095 */
2096 if (s->chanid == -1)
2097 fatal("no channel for session %d", s->self);
2098 channel_set_fds(s->chanid,
2099 fdout, fdin, fderr,
2100 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
2101 1,
2102 CHAN_SES_WINDOW_DEFAULT);
2103 }
2104
2105 /*
2106 * Function to perform pty cleanup. Also called if we get aborted abnormally
2107 * (e.g., due to a dropped connection).
2108 */
2109 void
2110 session_pty_cleanup2(void *session)
2111 {
2112 Session *s = session;
2113
2114 if (s == NULL) {
2115 error("session_pty_cleanup: no session");
2116 return;
2117 }
2118 if (s->ttyfd == -1)
2119 return;
2120
2121 debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
2122
2123 #ifdef USE_PAM
2124 session_do_pam(s, 0);
2125 #endif /* USE_PAM */
2126
2127 /* Record that the user has logged out. */
2128 if (s->pid != 0) {
2129 debug3("Recording SSHv2 channel logout in utmpx/wtmpx");
2130 #ifdef ALTPRIVSEP
2131 altprivsep_record_logout(s->pid);
2132 #endif /* ALTPRIVSEP */
2133 }
2134
2135 /* Release the pseudo-tty. */
2136 if (getuid() == 0)
2137 pty_release(s->tty);
2138
2139 /*
2140 * Close the server side of the socket pairs. We must do this after
2141 * the pty cleanup, so that another process doesn't get this pty
2142 * while we're still cleaning up.
2143 */
2144 if (close(s->ptymaster) < 0)
2145 error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno));
2146
2147 /* unlink pty from session */
2148 s->ttyfd = -1;
2149 }
2150
2151 void
2152 session_pty_cleanup(void *session)
2153 {
2154 session_pty_cleanup2(session);
2155 }
2156
2157 /*
2158 * We use a different temporary X authority file per every session so we
2159 * should remove those files when fatal() is called.
2160 */
2161 void
2162 session_xauthfile_cleanup(void *session)
2163 {
2164 Session *s = session;
2165
2166 if (s == NULL) {
2167 error("session_xauthfile_cleanup: no session");
2168 return;
2169 }
2170
2171 debug("session_xauthfile_cleanup: session %d removing %s", s->self,
2172 s->auth_file);
2173
2174 if (unlink(s->auth_file) == -1) {
2175 error("session_xauthfile_cleanup: cannot remove xauth file: "
2176 "%.100s", strerror(errno));
2177 return;
2178 }
2179
2180 /* dirname() will modify s->auth_file but that's ok */
2181 if (rmdir(dirname(s->auth_file)) == -1) {
2182 error("session_xauthfile_cleanup: "
2183 "cannot remove xauth directory: %.100s", strerror(errno));
2184 return;
2185 }
2186 }
2187
2188 static char *
2189 sig2name(int sig)
2190 {
2191 #define SSH_SIG(x) if (sig == SIG ## x) return #x
2192 SSH_SIG(ABRT);
2193 SSH_SIG(ALRM);
2194 SSH_SIG(FPE);
2195 SSH_SIG(HUP);
2196 SSH_SIG(ILL);
2197 SSH_SIG(INT);
2198 SSH_SIG(KILL);
2199 SSH_SIG(PIPE);
2200 SSH_SIG(QUIT);
2201 SSH_SIG(SEGV);
2202 SSH_SIG(TERM);
2203 SSH_SIG(USR1);
2204 SSH_SIG(USR2);
2205 #undef SSH_SIG
2206 return "SIG@openssh.com";
2207 }
2208
2209 static void
2210 session_exit_message(Session *s, int status)
2211 {
2212 Channel *c;
2213
2214 if ((c = channel_lookup(s->chanid)) == NULL)
2215 fatal("session_exit_message: session %d: no channel %d",
2216 s->self, s->chanid);
2217 debug("session_exit_message: session %d channel %d pid %ld",
2218 s->self, s->chanid, (long)s->pid);
2219
2220 if (WIFEXITED(status)) {
2221 channel_request_start(s->chanid, "exit-status", 0);
2222 packet_put_int(WEXITSTATUS(status));
2223 packet_send();
2224 } else if (WIFSIGNALED(status)) {
2225 channel_request_start(s->chanid, "exit-signal", 0);
2226 packet_put_cstring(sig2name(WTERMSIG(status)));
2227 #ifdef WCOREDUMP
2228 packet_put_char(WCOREDUMP(status));
2229 #else /* WCOREDUMP */
2230 packet_put_char(0);
2231 #endif /* WCOREDUMP */
2232 packet_put_cstring("");
2233 packet_put_cstring("");
2234 packet_send();
2235 } else {
2236 /* Some weird exit cause. Just exit. */
2237 packet_disconnect("wait returned status %04x.", status);
2238 }
2239
2240 /* Ok to close channel now */
2241 channel_set_wait_for_exit(s->chanid, 0);
2242
2243 /* disconnect channel */
2244 debug("session_exit_message: release channel %d", s->chanid);
2245 channel_cancel_cleanup(s->chanid);
2246 /*
2247 * emulate a write failure with 'chan_write_failed', nobody will be
2248 * interested in data we write.
2249 * Note that we must not call 'chan_read_failed', since there could
2250 * be some more data waiting in the pipe.
2251 */
2252 if (c->ostate != CHAN_OUTPUT_CLOSED)
2253 chan_write_failed(c);
2254 s->chanid = -1;
2255 }
2256
2257 void
2258 session_close(Session *s)
2259 {
2260 debug("session_close: session %d pid %ld", s->self, (long)s->pid);
2261 if (s->ttyfd != -1) {
2262 fatal_remove_cleanup(session_pty_cleanup, (void *)s);
2263 session_pty_cleanup(s);
2264 }
2265 if (s->auth_file != NULL) {
2266 fatal_remove_cleanup(session_xauthfile_cleanup, (void *)s);
2267 session_xauthfile_cleanup(s);
2268 xfree(s->auth_file);
2269 }
2270 if (s->term)
2271 xfree(s->term);
2272 if (s->display)
2273 xfree(s->display);
2274 if (s->auth_display)
2275 xfree(s->auth_display);
2276 if (s->auth_data)
2277 xfree(s->auth_data);
2278 if (s->auth_proto)
2279 xfree(s->auth_proto);
2280 if (s->command)
2281 xfree(s->command);
2282 session_free_env(&s->env);
2283
2284 LIST_REMOVE(s, list_entry);
2285 session_proctitle(s);
2286 xfree(s);
2287 }
2288
2289 void
2290 session_close_by_pid(pid_t pid, int status)
2291 {
2292 Session *s = session_by_pid(pid);
2293 if (s == NULL) {
2294 debug("session_close_by_pid: no session for pid %ld",
2295 (long)pid);
2296 return;
2297 }
2298 if (s->chanid != -1)
2299 session_exit_message(s, status);
2300 session_close(s);
2301 }
2302
2303 /*
2304 * This is called when a channel dies before the session 'child' itself dies.
2305 * It can happen for example if we exit from an interactive shell before we
2306 * exit from forwarded X11 applications.
2307 */
2308 void
2309 session_close_by_channel(int id, void *arg)
2310 {
2311 Session *s = session_by_channel(id);
2312 if (s == NULL) {
2313 debug("session_close_by_channel: no session for id %d", id);
2314 return;
2315 }
2316 debug("session_close_by_channel: channel %d child %ld",
2317 id, (long)s->pid);
2318 if (s->pid != 0) {
2319 debug("session_close_by_channel: channel %d: has child", id);
2320 /*
2321 * delay detach of session, but release pty, since
2322 * the fd's to the child are already closed
2323 */
2324 if (s->ttyfd != -1) {
2325 fatal_remove_cleanup(session_pty_cleanup, (void *)s);
2326 session_pty_cleanup(s);
2327 }
2328 return;
2329 }
2330 /* detach by removing callback */
2331 channel_cancel_cleanup(s->chanid);
2332 s->chanid = -1;
2333 session_close(s);
2334 }
2335
2336 void
2337 session_destroy_all(void (*closefunc)(Session *))
2338 {
2339 Session *s;
2340 LIST_FOREACH(s, &sessions, list_entry) {
2341 if (closefunc != NULL)
2342 closefunc(s);
2343 else
2344 session_close(s);
2345 }
2346 }
2347
2348 static char *
2349 session_tty_list(void)
2350 {
2351 Session *s;
2352 static char buf[1024];
2353 buf[0] = '\0';
2354 LIST_FOREACH(s, &sessions, list_entry) {
2355 if (s->ttyfd != -1) {
2356 if (buf[0] != '\0')
2357 strlcat(buf, ",", sizeof buf);
2358 strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf);
2359 }
2360 }
2361 if (buf[0] == '\0')
2362 strlcpy(buf, "notty", sizeof buf);
2363 return buf;
2364 }
2365
2366 void
2367 session_proctitle(Session *s)
2368 {
2369 if (s->pw == NULL)
2370 error("no user for session %d", s->self);
2371 else
2372 setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
2373 }
2374
2375 int
2376 session_setup_x11fwd(Session *s)
2377 {
2378 struct stat st;
2379 char display[512], auth_display[512];
2380 char hostname[MAXHOSTNAMELEN];
2381
2382 if (no_x11_forwarding_flag) {
2383 packet_send_debug("X11 forwarding disabled in user configuration file.");
2384 return 0;
2385 }
2386 if (!options.x11_forwarding) {
2387 debug("X11 forwarding disabled in server configuration file.");
2388 return 0;
2389 }
2390 if (!options.xauth_location ||
2391 (stat(options.xauth_location, &st) == -1)) {
2392 packet_send_debug("No xauth program; cannot forward with spoofing.");
2393 return 0;
2394 }
2395 if (s->display != NULL) {
2396 debug("X11 display already set.");
2397 return 0;
2398 }
2399 if (x11_create_display_inet(options.x11_display_offset,
2400 options.x11_use_localhost, s->single_connection,
2401 &s->display_number) == -1) {
2402 debug("x11_create_display_inet failed.");
2403 return 0;
2404 }
2405
2406 /* Set up a suitable value for the DISPLAY variable. */
2407 if (gethostname(hostname, sizeof(hostname)) < 0)
2408 fatal("gethostname: %.100s", strerror(errno));
2409 /*
2410 * auth_display must be used as the displayname when the
2411 * authorization entry is added with xauth(1). This will be
2412 * different than the DISPLAY string for localhost displays.
2413 */
2414 if (options.x11_use_localhost) {
2415 snprintf(display, sizeof display, "localhost:%u.%u",
2416 s->display_number, s->screen);
2417 snprintf(auth_display, sizeof auth_display, "unix:%u.%u",
2418 s->display_number, s->screen);
2419 s->display = xstrdup(display);
2420 s->auth_display = xstrdup(auth_display);
2421 } else {
2422 #ifdef IPADDR_IN_DISPLAY
2423 struct hostent *he;
2424 struct in_addr my_addr;
2425
2426 he = gethostbyname(hostname);
2427 if (he == NULL) {
2428 error("Can't get IP address for X11 DISPLAY.");
2429 packet_send_debug("Can't get IP address for X11 DISPLAY.");
2430 return 0;
2431 }
2432 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
2433 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr),
2434 s->display_number, s->screen);
2435 #else
2436 snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
2437 s->display_number, s->screen);
2438 #endif
2439 s->display = xstrdup(display);
2440 s->auth_display = xstrdup(display);
2441 }
2442
2443 return 1;
2444 }
2445
2446 #ifdef USE_PAM
2447 int session_do_pam_conv(int, struct pam_message **,
2448 struct pam_response **, void *);
2449
2450 static struct pam_conv session_pam_conv = {
2451 session_do_pam_conv,
2452 NULL
2453 };
2454
2455 static void
2456 session_do_pam(Session *s, int do_open)
2457 {
2458 int pam_retval;
2459 char *where, *old_tty, *old_tty_copy = NULL;
2460 struct pam_conv old_conv, *old_conv_ptr;
2461
2462 if (!s || !s->authctxt || !s->authctxt->pam || !s->authctxt->pam->h)
2463 return;
2464
2465 /* Save current PAM item values */
2466 where = "getting PAM_CONV";
2467 pam_retval = pam_get_item(s->authctxt->pam->h, PAM_CONV,
2468 (void **) &old_conv_ptr);
2469 if (pam_retval != PAM_SUCCESS)
2470 goto done;
2471 old_conv = *old_conv_ptr;
2472
2473 where = "getting PAM_TTY";
2474 pam_retval = pam_get_item(s->authctxt->pam->h, PAM_TTY,
2475 (void **) &old_tty);
2476 if (pam_retval != PAM_SUCCESS)
2477 goto done;
2478 old_tty_copy = xstrdup(old_tty);
2479
2480 /* Change PAM_TTY and PAM_CONV items */
2481 where = "setting PAM_TTY";
2482 pam_retval = pam_set_item(s->authctxt->pam->h, PAM_TTY, s->tty);
2483 if (pam_retval != PAM_SUCCESS)
2484 goto done;
2485
2486 where = "setting PAM_CONV";
2487 session_pam_conv.appdata_ptr = s;
2488 pam_retval = pam_set_item(s->authctxt->pam->h,
2489 PAM_CONV, &session_pam_conv);
2490 if (pam_retval != PAM_SUCCESS)
2491 goto done;
2492
2493 /* Call pam_open/close_session() */
2494 if (do_open) {
2495 where = "calling pam_open_session()";
2496 pam_retval = pam_open_session(s->authctxt->pam->h, 0);
2497 }
2498 else {
2499 where = "calling pam_close_session()";
2500 pam_retval = pam_close_session(s->authctxt->pam->h, 0);
2501 }
2502
2503 /* Reset PAM_TTY and PAM_CONV items to previous values */
2504 where = "setting PAM_TTY";
2505 pam_retval = pam_set_item(s->authctxt->pam->h, PAM_TTY, old_tty_copy);
2506 if (pam_retval != PAM_SUCCESS)
2507 goto done;
2508
2509 where = "setting PAM_CONV";
2510 pam_retval = pam_set_item(s->authctxt->pam->h, PAM_CONV, &old_conv);
2511 if (pam_retval != PAM_SUCCESS)
2512 goto done;
2513
2514 session_pam_conv.appdata_ptr = NULL;
2515
2516 done:
2517 if (old_tty_copy)
2518 xfree(old_tty_copy);
2519
2520 if (pam_retval == PAM_SUCCESS)
2521 return;
2522
2523 /* fatal()? probably not... */
2524 log("PAM failed[%d] while %s: %s", pam_retval, where,
2525 PAM_STRERROR(s->authctxt->pam->h, pam_retval));
2526 }
2527
2528 int
2529 session_do_pam_conv(int num_prompts,
2530 struct pam_message **prompts,
2531 struct pam_response **resp,
2532 void *app_data)
2533 {
2534 Session *s = (Session *) app_data;
2535
2536 struct pam_response *reply;
2537 int count;
2538 char *prompt;
2539
2540 if (channel_lookup(s->chanid) == NULL)
2541 return PAM_CONV_ERR;
2542
2543 /* PAM will free this later */
2544 reply = xmalloc(num_prompts * sizeof(*reply));
2545
2546 (void) memset(reply, 0, num_prompts * sizeof(*reply));
2547 for (count = 0; count < num_prompts; count++) {
2548 switch(PAM_MSG_MEMBER(prompts, count, msg_style)) {
2549 case PAM_TEXT_INFO:
2550 /* Write to stdout of channel */
2551 prompt = PAM_MSG_MEMBER(prompts, count, msg);
2552 if (prompt != NULL && s->ttyfd != -1) {
2553 debug2("session_do_pam_conv: text info "
2554 "prompt: %s", prompt);
2555 (void) write(s->ttyfd, prompt, strlen(prompt));
2556 (void) write(s->ttyfd, "\n", 1);
2557 }
2558 reply[count].resp = xstrdup("");
2559 reply[count].resp_retcode = PAM_SUCCESS;
2560 break;
2561 case PAM_ERROR_MSG:
2562 /* Write to stderr of channel */
2563 prompt = PAM_MSG_MEMBER(prompts, count, msg);
2564 if (prompt != NULL && s->ttyfd != -1) {
2565 debug2("session_do_pam_conv: error "
2566 "prompt: %s", prompt);
2567 (void) write(s->ttyfd, prompt, strlen(prompt));
2568 (void) write(s->ttyfd, "\n", 1);
2569 }
2570 reply[count].resp = xstrdup("");
2571 reply[count].resp_retcode = PAM_SUCCESS;
2572 break;
2573 case PAM_PROMPT_ECHO_ON:
2574 case PAM_PROMPT_ECHO_OFF:
2575 /*
2576 * XXX Someday add support for echo on/off prompts
2577 * here on sessions with ttys.
2578 */
2579 default:
2580 xfree(reply);
2581 return PAM_CONV_ERR;
2582 }
2583 }
2584
2585 *resp = reply;
2586
2587 return PAM_SUCCESS;
2588 }
2589 #endif /* USE_PAM */
2590
2591 static void
2592 do_authenticated2(Authctxt *authctxt)
2593 {
2594 server_loop2(authctxt);
2595 }
2596
2597 /*
2598 * Drop the privileges. We need this for the in-process SFTP server only. For
2599 * the shell and the external subsystem the exec(2) call will do the P = E = I
2600 * assignment itself. Never change the privileges if the connecting user is
2601 * root. See privileges(5) if the terminology used here is not known to you.
2602 */
2603 static void
2604 drop_privs(uid_t uid)
2605 {
2606 priv_set_t *priv_inherit;
2607
2608 /* If root is connecting we are done. */
2609 if (uid == 0)
2610 return;
2611
2612 if ((priv_inherit = priv_allocset()) == NULL)
2613 fatal("priv_allocset: %s", strerror(errno));
2614 if (getppriv(PRIV_INHERITABLE, priv_inherit) != 0)
2615 fatal("getppriv: %s", strerror(errno));
2616
2617 /*
2618 * This will limit E as well. Note that before this P was a
2619 * superset of I, see permanently_set_uid().
2620 */
2621 if (setppriv(PRIV_SET, PRIV_PERMITTED, priv_inherit) == -1)
2622 fatal("setppriv: %s", strerror(errno));
2623
2624 priv_freeset(priv_inherit);
2625
2626 /*
2627 * By manipulating the P set above we entered a PA mode which we
2628 * do not need to retain in.
2629 */
2630 if (setpflags(PRIV_AWARE, 0) == -1)
2631 fatal("setpflags: %s", strerror(errno));
2632 }