1 /* $OpenBSD: session.c,v 1.258 2010/11/25 04:10:09 djm Exp $ */
2 /*
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
5 *
6 * As far as I am concerned, the code I have written for this software
7 * can be used freely for any purpose. Any derived versions of this
8 * software must be clearly marked as such, and if the derived work is
9 * incompatible with the protocol description in the RFC file, it must be
10 * called by a name other than "ssh" or "Secure Shell".
11 *
12 * SSH2 support by Markus Friedl.
13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 #include "includes.h"
37
38 #include <sys/types.h>
39 #include <sys/param.h>
40 #ifdef HAVE_SYS_STAT_H
41 # include <sys/stat.h>
42 #endif
43 #include <sys/socket.h>
44 #include <sys/un.h>
45 #include <sys/wait.h>
46
47 #include <arpa/inet.h>
48
49 #include <errno.h>
50 #include <fcntl.h>
51 #include <grp.h>
52 #ifdef HAVE_PATHS_H
53 #include <paths.h>
54 #endif
55 #include <pwd.h>
56 #include <signal.h>
57 #include <stdarg.h>
58 #include <stdio.h>
59 #include <stdlib.h>
60 #include <string.h>
61 #include <unistd.h>
62
63 #include "openbsd-compat/sys-queue.h"
64 #include "xmalloc.h"
65 #include "ssh.h"
66 #include "ssh1.h"
67 #include "ssh2.h"
68 #include "sshpty.h"
69 #include "packet.h"
70 #include "buffer.h"
71 #include "match.h"
72 #include "uidswap.h"
73 #include "compat.h"
74 #include "channels.h"
75 #include "key.h"
76 #include "cipher.h"
77 #ifdef GSSAPI
78 #include "ssh-gss.h"
79 #endif
80 #include "hostfile.h"
81 #include "auth.h"
82 #include "auth-options.h"
83 #include "pathnames.h"
84 #include "log.h"
85 #include "servconf.h"
86 #include "sshlogin.h"
87 #include "serverloop.h"
88 #include "canohost.h"
89 #include "misc.h"
90 #include "session.h"
91 #include "kex.h"
92 #include "monitor_wrap.h"
93 #include "sftp.h"
94
95 #if defined(KRB5) && defined(USE_AFS)
96 #include <kafs.h>
97 #endif
98
99 #ifdef WITH_SELINUX
100 #include <selinux/selinux.h>
101 #endif
102
103 #define IS_INTERNAL_SFTP(c) \
104 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \
105 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \
106 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \
107 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t'))
108
109 /* func */
110
111 Session *session_new(void);
112 void session_set_fds(Session *, int, int, int, int, int);
113 void session_pty_cleanup(Session *);
114 void session_proctitle(Session *);
115 int session_setup_x11fwd(Session *);
116 int do_exec_pty(Session *, const char *);
117 int do_exec_no_pty(Session *, const char *);
118 int do_exec(Session *, const char *);
119 void do_login(Session *, const char *);
120 #ifdef LOGIN_NEEDS_UTMPX
121 static void do_pre_login(Session *s);
122 #endif
123 void do_child(Session *, const char *);
124 void do_motd(void);
125 int check_quietlogin(Session *, const char *);
126
127 static void do_authenticated1(Authctxt *);
128 static void do_authenticated2(Authctxt *);
129
130 static int session_pty_req(Session *);
131
132 /* import */
133 extern ServerOptions options;
134 extern char *__progname;
135 extern int log_stderr;
136 extern int debug_flag;
137 extern u_int utmp_len;
138 extern int startup_pipe;
139 extern void destroy_sensitive_data(void);
140 extern Buffer loginmsg;
141
142 /* original command from peer. */
143 const char *original_command = NULL;
144
145 /* data */
146 static int sessions_first_unused = -1;
147 static int sessions_nalloc = 0;
148 static Session *sessions = NULL;
149
150 #define SUBSYSTEM_NONE 0
151 #define SUBSYSTEM_EXT 1
152 #define SUBSYSTEM_INT_SFTP 2
153 #define SUBSYSTEM_INT_SFTP_ERROR 3
154
155 #ifdef HAVE_LOGIN_CAP
156 login_cap_t *lc;
157 #endif
158
159 static int is_child = 0;
160
161 /* Name and directory of socket for authentication agent forwarding. */
162 static char *auth_sock_name = NULL;
163 static char *auth_sock_dir = NULL;
164
165 /* removes the agent forwarding socket */
166
167 static void
auth_sock_cleanup_proc(struct passwd * pw)168 auth_sock_cleanup_proc(struct passwd *pw)
169 {
170 if (auth_sock_name != NULL) {
171 temporarily_use_uid(pw);
172 unlink(auth_sock_name);
173 rmdir(auth_sock_dir);
174 auth_sock_name = NULL;
175 restore_uid();
176 }
177 }
178
179 static int
auth_input_request_forwarding(struct passwd * pw)180 auth_input_request_forwarding(struct passwd * pw)
181 {
182 Channel *nc;
183 int sock = -1;
184 struct sockaddr_un sunaddr;
185
186 if (auth_sock_name != NULL) {
187 error("authentication forwarding requested twice.");
188 return 0;
189 }
190
191 /* Temporarily drop privileged uid for mkdir/bind. */
192 temporarily_use_uid(pw);
193
194 /* Allocate a buffer for the socket name, and format the name. */
195 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX");
196
197 /* Create private directory for socket */
198 if (mkdtemp(auth_sock_dir) == NULL) {
199 packet_send_debug("Agent forwarding disabled: "
200 "mkdtemp() failed: %.100s", strerror(errno));
201 restore_uid();
202 xfree(auth_sock_dir);
203 auth_sock_dir = NULL;
204 goto authsock_err;
205 }
206
207 xasprintf(&auth_sock_name, "%s/agent.%ld",
208 auth_sock_dir, (long) getpid());
209
210 /* Create the socket. */
211 sock = socket(AF_UNIX, SOCK_STREAM, 0);
212 if (sock < 0) {
213 error("socket: %.100s", strerror(errno));
214 restore_uid();
215 goto authsock_err;
216 }
217
218 /* Bind it to the name. */
219 memset(&sunaddr, 0, sizeof(sunaddr));
220 sunaddr.sun_family = AF_UNIX;
221 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path));
222
223 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) {
224 error("bind: %.100s", strerror(errno));
225 restore_uid();
226 goto authsock_err;
227 }
228
229 /* Restore the privileged uid. */
230 restore_uid();
231
232 /* Start listening on the socket. */
233 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
234 error("listen: %.100s", strerror(errno));
235 goto authsock_err;
236 }
237
238 /* Allocate a channel for the authentication agent socket. */
239 nc = channel_new("auth socket",
240 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
241 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
242 0, "auth socket", 1);
243 nc->path = xstrdup(auth_sock_name);
244 return 1;
245
246 authsock_err:
247 if (auth_sock_name != NULL)
248 xfree(auth_sock_name);
249 if (auth_sock_dir != NULL) {
250 rmdir(auth_sock_dir);
251 xfree(auth_sock_dir);
252 }
253 if (sock != -1)
254 close(sock);
255 auth_sock_name = NULL;
256 auth_sock_dir = NULL;
257 return 0;
258 }
259
260 static void
display_loginmsg(void)261 display_loginmsg(void)
262 {
263 if (buffer_len(&loginmsg) > 0) {
264 buffer_append(&loginmsg, "\0", 1);
265 printf("%s", (char *)buffer_ptr(&loginmsg));
266 buffer_clear(&loginmsg);
267 }
268 }
269
270 void
do_authenticated(Authctxt * authctxt)271 do_authenticated(Authctxt *authctxt)
272 {
273 setproctitle("%s", authctxt->pw->pw_name);
274
275 /* setup the channel layer */
276 if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
277 channel_permit_all_opens();
278
279 auth_debug_send();
280
281 if (compat20)
282 do_authenticated2(authctxt);
283 else
284 do_authenticated1(authctxt);
285
286 do_cleanup(authctxt);
287 }
288
289 /*
290 * Prepares for an interactive session. This is called after the user has
291 * been successfully authenticated. During this message exchange, pseudo
292 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings
293 * are requested, etc.
294 */
295 static void
do_authenticated1(Authctxt * authctxt)296 do_authenticated1(Authctxt *authctxt)
297 {
298 Session *s;
299 char *command;
300 int success, type, screen_flag;
301 int enable_compression_after_reply = 0;
302 u_int proto_len, data_len, dlen, compression_level = 0;
303
304 s = session_new();
305 if (s == NULL) {
306 error("no more sessions");
307 return;
308 }
309 s->authctxt = authctxt;
310 s->pw = authctxt->pw;
311
312 /*
313 * We stay in this loop until the client requests to execute a shell
314 * or a command.
315 */
316 for (;;) {
317 success = 0;
318
319 /* Get a packet from the client. */
320 type = packet_read();
321
322 /* Process the packet. */
323 switch (type) {
324 case SSH_CMSG_REQUEST_COMPRESSION:
325 compression_level = packet_get_int();
326 packet_check_eom();
327 if (compression_level < 1 || compression_level > 9) {
328 packet_send_debug("Received invalid compression level %d.",
329 compression_level);
330 break;
331 }
332 if (options.compression == COMP_NONE) {
333 debug2("compression disabled");
334 break;
335 }
336 /* Enable compression after we have responded with SUCCESS. */
337 enable_compression_after_reply = 1;
338 success = 1;
339 break;
340
341 case SSH_CMSG_REQUEST_PTY:
342 success = session_pty_req(s);
343 break;
344
345 case SSH_CMSG_X11_REQUEST_FORWARDING:
346 s->auth_proto = packet_get_string(&proto_len);
347 s->auth_data = packet_get_string(&data_len);
348
349 screen_flag = packet_get_protocol_flags() &
350 SSH_PROTOFLAG_SCREEN_NUMBER;
351 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag);
352
353 if (packet_remaining() == 4) {
354 if (!screen_flag)
355 debug2("Buggy client: "
356 "X11 screen flag missing");
357 s->screen = packet_get_int();
358 } else {
359 s->screen = 0;
360 }
361 packet_check_eom();
362 success = session_setup_x11fwd(s);
363 if (!success) {
364 xfree(s->auth_proto);
365 xfree(s->auth_data);
366 s->auth_proto = NULL;
367 s->auth_data = NULL;
368 }
369 break;
370
371 case SSH_CMSG_AGENT_REQUEST_FORWARDING:
372 if (!options.allow_agent_forwarding ||
373 no_agent_forwarding_flag || compat13) {
374 debug("Authentication agent forwarding not permitted for this authentication.");
375 break;
376 }
377 debug("Received authentication agent forwarding request.");
378 success = auth_input_request_forwarding(s->pw);
379 break;
380
381 case SSH_CMSG_PORT_FORWARD_REQUEST:
382 if (no_port_forwarding_flag) {
383 debug("Port forwarding not permitted for this authentication.");
384 break;
385 }
386 if (!options.allow_tcp_forwarding) {
387 debug("Port forwarding not permitted.");
388 break;
389 }
390 debug("Received TCP/IP port forwarding request.");
391 if (channel_input_port_forward_request(s->pw->pw_uid == 0,
392 options.gateway_ports) < 0) {
393 debug("Port forwarding failed.");
394 break;
395 }
396 success = 1;
397 break;
398
399 case SSH_CMSG_MAX_PACKET_SIZE:
400 if (packet_set_maxsize(packet_get_int()) > 0)
401 success = 1;
402 break;
403
404 case SSH_CMSG_EXEC_SHELL:
405 case SSH_CMSG_EXEC_CMD:
406 if (type == SSH_CMSG_EXEC_CMD) {
407 command = packet_get_string(&dlen);
408 debug("Exec command '%.500s'", command);
409 if (do_exec(s, command) != 0)
410 packet_disconnect(
411 "command execution failed");
412 xfree(command);
413 } else {
414 if (do_exec(s, NULL) != 0)
415 packet_disconnect(
416 "shell execution failed");
417 }
418 packet_check_eom();
419 session_close(s);
420 return;
421
422 default:
423 /*
424 * Any unknown messages in this phase are ignored,
425 * and a failure message is returned.
426 */
427 logit("Unknown packet type received after authentication: %d", type);
428 }
429 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
430 packet_send();
431 packet_write_wait();
432
433 /* Enable compression now that we have replied if appropriate. */
434 if (enable_compression_after_reply) {
435 enable_compression_after_reply = 0;
436 packet_start_compression(compression_level);
437 }
438 }
439 }
440
441 #define USE_PIPES
442 /*
443 * This is called to fork and execute a command when we have no tty. This
444 * will call do_child from the child, and server_loop from the parent after
445 * setting up file descriptors and such.
446 */
447 int
do_exec_no_pty(Session * s,const char * command)448 do_exec_no_pty(Session *s, const char *command)
449 {
450 pid_t pid;
451
452 #ifdef USE_PIPES
453 int pin[2], pout[2], perr[2];
454
455 if (s == NULL)
456 fatal("do_exec_no_pty: no session");
457
458 /* Allocate pipes for communicating with the program. */
459 if (pipe(pin) < 0) {
460 error("%s: pipe in: %.100s", __func__, strerror(errno));
461 return -1;
462 }
463 if (pipe(pout) < 0) {
464 error("%s: pipe out: %.100s", __func__, strerror(errno));
465 close(pin[0]);
466 close(pin[1]);
467 return -1;
468 }
469 if (pipe(perr) < 0) {
470 error("%s: pipe err: %.100s", __func__,
471 strerror(errno));
472 close(pin[0]);
473 close(pin[1]);
474 close(pout[0]);
475 close(pout[1]);
476 return -1;
477 }
478 #else
479 int inout[2], err[2];
480
481 if (s == NULL)
482 fatal("do_exec_no_pty: no session");
483
484 /* Uses socket pairs to communicate with the program. */
485 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) {
486 error("%s: socketpair #1: %.100s", __func__, strerror(errno));
487 return -1;
488 }
489 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) {
490 error("%s: socketpair #2: %.100s", __func__,
491 strerror(errno));
492 close(inout[0]);
493 close(inout[1]);
494 return -1;
495 }
496 #endif
497
498 session_proctitle(s);
499
500 /* Fork the child. */
501 switch ((pid = fork())) {
502 case -1:
503 error("%s: fork: %.100s", __func__, strerror(errno));
504 #ifdef USE_PIPES
505 close(pin[0]);
506 close(pin[1]);
507 close(pout[0]);
508 close(pout[1]);
509 close(perr[0]);
510 close(perr[1]);
511 #else
512 close(inout[0]);
513 close(inout[1]);
514 close(err[0]);
515 close(err[1]);
516 #endif
517 return -1;
518 case 0:
519 is_child = 1;
520
521 /* Child. Reinitialize the log since the pid has changed. */
522 log_init(__progname, options.log_level,
523 options.log_facility, log_stderr);
524
525 /*
526 * Create a new session and process group since the 4.4BSD
527 * setlogin() affects the entire process group.
528 */
529 if (setsid() < 0)
530 error("setsid failed: %.100s", strerror(errno));
531
532 #ifdef USE_PIPES
533 /*
534 * Redirect stdin. We close the parent side of the socket
535 * pair, and make the child side the standard input.
536 */
537 close(pin[1]);
538 if (dup2(pin[0], 0) < 0)
539 perror("dup2 stdin");
540 close(pin[0]);
541
542 /* Redirect stdout. */
543 close(pout[0]);
544 if (dup2(pout[1], 1) < 0)
545 perror("dup2 stdout");
546 close(pout[1]);
547
548 /* Redirect stderr. */
549 close(perr[0]);
550 if (dup2(perr[1], 2) < 0)
551 perror("dup2 stderr");
552 close(perr[1]);
553 #else
554 /*
555 * Redirect stdin, stdout, and stderr. Stdin and stdout will
556 * use the same socket, as some programs (particularly rdist)
557 * seem to depend on it.
558 */
559 close(inout[1]);
560 close(err[1]);
561 if (dup2(inout[0], 0) < 0) /* stdin */
562 perror("dup2 stdin");
563 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */
564 perror("dup2 stdout");
565 close(inout[0]);
566 if (dup2(err[0], 2) < 0) /* stderr */
567 perror("dup2 stderr");
568 close(err[0]);
569 #endif
570
571
572 #ifdef _UNICOS
573 cray_init_job(s->pw); /* set up cray jid and tmpdir */
574 #endif
575
576 /* Do processing for the child (exec command etc). */
577 do_child(s, command);
578 /* NOTREACHED */
579 default:
580 break;
581 }
582
583 #ifdef _UNICOS
584 signal(WJSIGNAL, cray_job_termination_handler);
585 #endif /* _UNICOS */
586 #ifdef HAVE_CYGWIN
587 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
588 #endif
589
590 s->pid = pid;
591 /* Set interactive/non-interactive mode. */
592 packet_set_interactive(s->display != NULL,
593 options.ip_qos_interactive, options.ip_qos_bulk);
594
595 /*
596 * Clear loginmsg, since it's the child's responsibility to display
597 * it to the user, otherwise multiple sessions may accumulate
598 * multiple copies of the login messages.
599 */
600 buffer_clear(&loginmsg);
601
602 #ifdef USE_PIPES
603 /* We are the parent. Close the child sides of the pipes. */
604 close(pin[0]);
605 close(pout[1]);
606 close(perr[1]);
607
608 if (compat20) {
609 session_set_fds(s, pin[1], pout[0], perr[0],
610 s->is_subsystem, 0);
611 } else {
612 /* Enter the interactive session. */
613 server_loop(pid, pin[1], pout[0], perr[0]);
614 /* server_loop has closed pin[1], pout[0], and perr[0]. */
615 }
616 #else
617 /* We are the parent. Close the child sides of the socket pairs. */
618 close(inout[0]);
619 close(err[0]);
620
621 /*
622 * Enter the interactive session. Note: server_loop must be able to
623 * handle the case that fdin and fdout are the same.
624 */
625 if (compat20) {
626 session_set_fds(s, inout[1], inout[1], err[1],
627 s->is_subsystem, 0);
628 } else {
629 server_loop(pid, inout[1], inout[1], err[1]);
630 /* server_loop has closed inout[1] and err[1]. */
631 }
632 #endif
633 return 0;
634 }
635
636 /*
637 * This is called to fork and execute a command when we have a tty. This
638 * will call do_child from the child, and server_loop from the parent after
639 * setting up file descriptors, controlling tty, updating wtmp, utmp,
640 * lastlog, and other such operations.
641 */
642 int
do_exec_pty(Session * s,const char * command)643 do_exec_pty(Session *s, const char *command)
644 {
645 int fdout, ptyfd, ttyfd, ptymaster;
646 pid_t pid;
647
648 if (s == NULL)
649 fatal("do_exec_pty: no session");
650 ptyfd = s->ptyfd;
651 ttyfd = s->ttyfd;
652
653 /*
654 * Create another descriptor of the pty master side for use as the
655 * standard input. We could use the original descriptor, but this
656 * simplifies code in server_loop. The descriptor is bidirectional.
657 * Do this before forking (and cleanup in the child) so as to
658 * detect and gracefully fail out-of-fd conditions.
659 */
660 if ((fdout = dup(ptyfd)) < 0) {
661 error("%s: dup #1: %s", __func__, strerror(errno));
662 close(ttyfd);
663 close(ptyfd);
664 return -1;
665 }
666 /* we keep a reference to the pty master */
667 if ((ptymaster = dup(ptyfd)) < 0) {
668 error("%s: dup #2: %s", __func__, strerror(errno));
669 close(ttyfd);
670 close(ptyfd);
671 close(fdout);
672 return -1;
673 }
674
675 /* Fork the child. */
676 switch ((pid = fork())) {
677 case -1:
678 error("%s: fork: %.100s", __func__, strerror(errno));
679 close(fdout);
680 close(ptymaster);
681 close(ttyfd);
682 close(ptyfd);
683 return -1;
684 case 0:
685 is_child = 1;
686
687 close(fdout);
688 close(ptymaster);
689
690 /* Child. Reinitialize the log because the pid has changed. */
691 log_init(__progname, options.log_level,
692 options.log_facility, log_stderr);
693 /* Close the master side of the pseudo tty. */
694 close(ptyfd);
695
696 /* Make the pseudo tty our controlling tty. */
697 pty_make_controlling_tty(&ttyfd, s->tty);
698
699 /* Redirect stdin/stdout/stderr from the pseudo tty. */
700 if (dup2(ttyfd, 0) < 0)
701 error("dup2 stdin: %s", strerror(errno));
702 if (dup2(ttyfd, 1) < 0)
703 error("dup2 stdout: %s", strerror(errno));
704 if (dup2(ttyfd, 2) < 0)
705 error("dup2 stderr: %s", strerror(errno));
706
707 /* Close the extra descriptor for the pseudo tty. */
708 close(ttyfd);
709
710 /* record login, etc. similar to login(1) */
711 #ifndef HAVE_OSF_SIA
712 if (!(options.use_login && command == NULL)) {
713 #ifdef _UNICOS
714 cray_init_job(s->pw); /* set up cray jid and tmpdir */
715 #endif /* _UNICOS */
716 do_login(s, command);
717 }
718 # ifdef LOGIN_NEEDS_UTMPX
719 else
720 do_pre_login(s);
721 # endif
722 #endif
723 /*
724 * Do common processing for the child, such as execing
725 * the command.
726 */
727 do_child(s, command);
728 /* NOTREACHED */
729 default:
730 break;
731 }
732
733 #ifdef _UNICOS
734 signal(WJSIGNAL, cray_job_termination_handler);
735 #endif /* _UNICOS */
736 #ifdef HAVE_CYGWIN
737 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
738 #endif
739
740 s->pid = pid;
741
742 /* Parent. Close the slave side of the pseudo tty. */
743 close(ttyfd);
744
745 /* Enter interactive session. */
746 s->ptymaster = ptymaster;
747 packet_set_interactive(1,
748 options.ip_qos_interactive, options.ip_qos_bulk);
749 if (compat20) {
750 session_set_fds(s, ptyfd, fdout, -1, 1, 1);
751 } else {
752 server_loop(pid, ptyfd, fdout, -1);
753 /* server_loop _has_ closed ptyfd and fdout. */
754 }
755 return 0;
756 }
757
758 #ifdef LOGIN_NEEDS_UTMPX
759 static void
do_pre_login(Session * s)760 do_pre_login(Session *s)
761 {
762 socklen_t fromlen;
763 struct sockaddr_storage from;
764 pid_t pid = getpid();
765
766 /*
767 * Get IP address of client. If the connection is not a socket, let
768 * the address be 0.0.0.0.
769 */
770 memset(&from, 0, sizeof(from));
771 fromlen = sizeof(from);
772 if (packet_connection_is_on_socket()) {
773 if (getpeername(packet_get_connection_in(),
774 (struct sockaddr *)&from, &fromlen) < 0) {
775 debug("getpeername: %.100s", strerror(errno));
776 cleanup_exit(255);
777 }
778 }
779
780 record_utmp_only(pid, s->tty, s->pw->pw_name,
781 get_remote_name_or_ip(utmp_len, options.use_dns),
782 (struct sockaddr *)&from, fromlen);
783 }
784 #endif
785
786 /*
787 * This is called to fork and execute a command. If another command is
788 * to be forced, execute that instead.
789 */
790 int
do_exec(Session * s,const char * command)791 do_exec(Session *s, const char *command)
792 {
793 int ret;
794
795 if (options.adm_forced_command) {
796 original_command = command;
797 command = options.adm_forced_command;
798 if (IS_INTERNAL_SFTP(command)) {
799 s->is_subsystem = s->is_subsystem ?
800 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR;
801 } else if (s->is_subsystem)
802 s->is_subsystem = SUBSYSTEM_EXT;
803 debug("Forced command (config) '%.900s'", command);
804 } else if (forced_command) {
805 original_command = command;
806 command = forced_command;
807 if (IS_INTERNAL_SFTP(command)) {
808 s->is_subsystem = s->is_subsystem ?
809 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR;
810 } else if (s->is_subsystem)
811 s->is_subsystem = SUBSYSTEM_EXT;
812 debug("Forced command (key option) '%.900s'", command);
813 }
814
815 #ifdef SSH_AUDIT_EVENTS
816 if (command != NULL)
817 PRIVSEP(audit_run_command(command));
818 else if (s->ttyfd == -1) {
819 char *shell = s->pw->pw_shell;
820
821 if (shell[0] == '\0') /* empty shell means /bin/sh */
822 shell =_PATH_BSHELL;
823 PRIVSEP(audit_run_command(shell));
824 }
825 #endif
826 if (s->ttyfd != -1)
827 ret = do_exec_pty(s, command);
828 else
829 ret = do_exec_no_pty(s, command);
830
831 original_command = NULL;
832
833 /*
834 * Clear loginmsg: it's the child's responsibility to display
835 * it to the user, otherwise multiple sessions may accumulate
836 * multiple copies of the login messages.
837 */
838 buffer_clear(&loginmsg);
839
840 return ret;
841 }
842
843 /* administrative, login(1)-like work */
844 void
do_login(Session * s,const char * command)845 do_login(Session *s, const char *command)
846 {
847 socklen_t fromlen;
848 struct sockaddr_storage from;
849 struct passwd * pw = s->pw;
850 pid_t pid = getpid();
851
852 /*
853 * Get IP address of client. If the connection is not a socket, let
854 * the address be 0.0.0.0.
855 */
856 memset(&from, 0, sizeof(from));
857 fromlen = sizeof(from);
858 if (packet_connection_is_on_socket()) {
859 if (getpeername(packet_get_connection_in(),
860 (struct sockaddr *)&from, &fromlen) < 0) {
861 debug("getpeername: %.100s", strerror(errno));
862 cleanup_exit(255);
863 }
864 }
865
866 /* Record that there was a login on that tty from the remote host. */
867 if (!use_privsep)
868 record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
869 get_remote_name_or_ip(utmp_len,
870 options.use_dns),
871 (struct sockaddr *)&from, fromlen);
872
873 #ifdef USE_PAM
874 /*
875 * If password change is needed, do it now.
876 * This needs to occur before the ~/.hushlogin check.
877 */
878 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) {
879 display_loginmsg();
880 do_pam_chauthtok();
881 s->authctxt->force_pwchange = 0;
882 /* XXX - signal [net] parent to enable forwardings */
883 }
884 #endif
885
886 if (check_quietlogin(s, command))
887 return;
888
889 display_loginmsg();
890
891 do_motd();
892 }
893
894 /*
895 * Display the message of the day.
896 */
897 void
do_motd(void)898 do_motd(void)
899 {
900 FILE *f;
901 char buf[256];
902
903 if (options.print_motd) {
904 #ifdef HAVE_LOGIN_CAP
905 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd",
906 "/etc/motd"), "r");
907 #else
908 f = fopen("/etc/motd", "r");
909 #endif
910 if (f) {
911 while (fgets(buf, sizeof(buf), f))
912 fputs(buf, stdout);
913 fclose(f);
914 }
915 }
916 }
917
918
919 /*
920 * Check for quiet login, either .hushlogin or command given.
921 */
922 int
check_quietlogin(Session * s,const char * command)923 check_quietlogin(Session *s, const char *command)
924 {
925 char buf[256];
926 struct passwd *pw = s->pw;
927 struct stat st;
928
929 /* Return 1 if .hushlogin exists or a command given. */
930 if (command != NULL)
931 return 1;
932 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
933 #ifdef HAVE_LOGIN_CAP
934 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
935 return 1;
936 #else
937 if (stat(buf, &st) >= 0)
938 return 1;
939 #endif
940 return 0;
941 }
942
943 /*
944 * Sets the value of the given variable in the environment. If the variable
945 * already exists, its value is overridden.
946 */
947 void
child_set_env(char *** envp,u_int * envsizep,const char * name,const char * value)948 child_set_env(char ***envp, u_int *envsizep, const char *name,
949 const char *value)
950 {
951 char **env;
952 u_int envsize;
953 u_int i, namelen;
954
955 /*
956 * If we're passed an uninitialized list, allocate a single null
957 * entry before continuing.
958 */
959 if (*envp == NULL && *envsizep == 0) {
960 *envp = xmalloc(sizeof(char *));
961 *envp[0] = NULL;
962 *envsizep = 1;
963 }
964
965 /*
966 * Find the slot where the value should be stored. If the variable
967 * already exists, we reuse the slot; otherwise we append a new slot
968 * at the end of the array, expanding if necessary.
969 */
970 env = *envp;
971 namelen = strlen(name);
972 for (i = 0; env[i]; i++)
973 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
974 break;
975 if (env[i]) {
976 /* Reuse the slot. */
977 xfree(env[i]);
978 } else {
979 /* New variable. Expand if necessary. */
980 envsize = *envsizep;
981 if (i >= envsize - 1) {
982 if (envsize >= 1000)
983 fatal("child_set_env: too many env vars");
984 envsize += 50;
985 env = (*envp) = xrealloc(env, envsize, sizeof(char *));
986 *envsizep = envsize;
987 }
988 /* Need to set the NULL pointer at end of array beyond the new slot. */
989 env[i + 1] = NULL;
990 }
991
992 /* Allocate space and format the variable in the appropriate slot. */
993 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
994 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
995 }
996
997 /*
998 * Reads environment variables from the given file and adds/overrides them
999 * into the environment. If the file does not exist, this does nothing.
1000 * Otherwise, it must consist of empty lines, comments (line starts with '#')
1001 * and assignments of the form name=value. No other forms are allowed.
1002 */
1003 static void
read_environment_file(char *** env,u_int * envsize,const char * filename)1004 read_environment_file(char ***env, u_int *envsize,
1005 const char *filename)
1006 {
1007 FILE *f;
1008 char buf[4096];
1009 char *cp, *value;
1010 u_int lineno = 0;
1011
1012 f = fopen(filename, "r");
1013 if (!f)
1014 return;
1015
1016 while (fgets(buf, sizeof(buf), f)) {
1017 if (++lineno > 1000)
1018 fatal("Too many lines in environment file %s", filename);
1019 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
1020 ;
1021 if (!*cp || *cp == '#' || *cp == '\n')
1022 continue;
1023
1024 cp[strcspn(cp, "\n")] = '\0';
1025
1026 value = strchr(cp, '=');
1027 if (value == NULL) {
1028 fprintf(stderr, "Bad line %u in %.100s\n", lineno,
1029 filename);
1030 continue;
1031 }
1032 /*
1033 * Replace the equals sign by nul, and advance value to
1034 * the value string.
1035 */
1036 *value = '\0';
1037 value++;
1038 child_set_env(env, envsize, cp, value);
1039 }
1040 fclose(f);
1041 }
1042
1043 #ifdef HAVE_ETC_DEFAULT_LOGIN
1044 /*
1045 * Return named variable from specified environment, or NULL if not present.
1046 */
1047 static char *
child_get_env(char ** env,const char * name)1048 child_get_env(char **env, const char *name)
1049 {
1050 int i;
1051 size_t len;
1052
1053 len = strlen(name);
1054 for (i=0; env[i] != NULL; i++)
1055 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=')
1056 return(env[i] + len + 1);
1057 return NULL;
1058 }
1059
1060 /*
1061 * Read /etc/default/login.
1062 * We pick up the PATH (or SUPATH for root) and UMASK.
1063 */
1064 static void
read_etc_default_login(char *** env,u_int * envsize,uid_t uid)1065 read_etc_default_login(char ***env, u_int *envsize, uid_t uid)
1066 {
1067 char **tmpenv = NULL, *var;
1068 u_int i, tmpenvsize = 0;
1069 u_long mask;
1070
1071 /*
1072 * We don't want to copy the whole file to the child's environment,
1073 * so we use a temporary environment and copy the variables we're
1074 * interested in.
1075 */
1076 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login");
1077
1078 if (tmpenv == NULL)
1079 return;
1080
1081 if (uid == 0)
1082 var = child_get_env(tmpenv, "SUPATH");
1083 else
1084 var = child_get_env(tmpenv, "PATH");
1085 if (var != NULL)
1086 child_set_env(env, envsize, "PATH", var);
1087
1088 if ((var = child_get_env(tmpenv, "UMASK")) != NULL)
1089 if (sscanf(var, "%5lo", &mask) == 1)
1090 umask((mode_t)mask);
1091
1092 for (i = 0; tmpenv[i] != NULL; i++)
1093 xfree(tmpenv[i]);
1094 xfree(tmpenv);
1095 }
1096 #endif /* HAVE_ETC_DEFAULT_LOGIN */
1097
1098 void
copy_environment(char ** source,char *** env,u_int * envsize)1099 copy_environment(char **source, char ***env, u_int *envsize)
1100 {
1101 char *var_name, *var_val;
1102 int i;
1103
1104 if (source == NULL)
1105 return;
1106
1107 for(i = 0; source[i] != NULL; i++) {
1108 var_name = xstrdup(source[i]);
1109 if ((var_val = strstr(var_name, "=")) == NULL) {
1110 xfree(var_name);
1111 continue;
1112 }
1113 *var_val++ = '\0';
1114
1115 debug3("Copy environment: %s=%s", var_name, var_val);
1116 child_set_env(env, envsize, var_name, var_val);
1117
1118 xfree(var_name);
1119 }
1120 }
1121
1122 static char **
do_setup_env(Session * s,const char * shell)1123 do_setup_env(Session *s, const char *shell)
1124 {
1125 char buf[256];
1126 u_int i, envsize;
1127 char **env, *laddr;
1128 struct passwd *pw = s->pw;
1129 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN)
1130 char *path = NULL;
1131 #endif
1132
1133 /* Initialize the environment. */
1134 envsize = 100;
1135 env = xcalloc(envsize, sizeof(char *));
1136 env[0] = NULL;
1137
1138 #ifdef HAVE_CYGWIN
1139 /*
1140 * The Windows environment contains some setting which are
1141 * important for a running system. They must not be dropped.
1142 */
1143 {
1144 char **p;
1145
1146 p = fetch_windows_environment();
1147 copy_environment(p, &env, &envsize);
1148 free_windows_environment(p);
1149 }
1150 #endif
1151
1152 #ifdef GSSAPI
1153 /* Allow any GSSAPI methods that we've used to alter
1154 * the childs environment as they see fit
1155 */
1156 ssh_gssapi_do_child(&env, &envsize);
1157 #endif
1158
1159 if (!options.use_login) {
1160 /* Set basic environment. */
1161 for (i = 0; i < s->num_env; i++)
1162 child_set_env(&env, &envsize, s->env[i].name,
1163 s->env[i].val);
1164
1165 child_set_env(&env, &envsize, "USER", pw->pw_name);
1166 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
1167 #ifdef _AIX
1168 child_set_env(&env, &envsize, "LOGIN", pw->pw_name);
1169 #endif
1170 child_set_env(&env, &envsize, "HOME", pw->pw_dir);
1171 #ifdef HAVE_LOGIN_CAP
1172 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0)
1173 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
1174 else
1175 child_set_env(&env, &envsize, "PATH", getenv("PATH"));
1176 #else /* HAVE_LOGIN_CAP */
1177 # ifndef HAVE_CYGWIN
1178 /*
1179 * There's no standard path on Windows. The path contains
1180 * important components pointing to the system directories,
1181 * needed for loading shared libraries. So the path better
1182 * remains intact here.
1183 */
1184 # ifdef HAVE_ETC_DEFAULT_LOGIN
1185 read_etc_default_login(&env, &envsize, pw->pw_uid);
1186 path = child_get_env(env, "PATH");
1187 # endif /* HAVE_ETC_DEFAULT_LOGIN */
1188 if (path == NULL || *path == '\0') {
1189 child_set_env(&env, &envsize, "PATH",
1190 s->pw->pw_uid == 0 ?
1191 SUPERUSER_PATH : _PATH_STDPATH);
1192 }
1193 # endif /* HAVE_CYGWIN */
1194 #endif /* HAVE_LOGIN_CAP */
1195
1196 snprintf(buf, sizeof buf, "%.200s/%.50s",
1197 _PATH_MAILDIR, pw->pw_name);
1198 child_set_env(&env, &envsize, "MAIL", buf);
1199
1200 /* Normal systems set SHELL by default. */
1201 child_set_env(&env, &envsize, "SHELL", shell);
1202 }
1203 if (getenv("TZ"))
1204 child_set_env(&env, &envsize, "TZ", getenv("TZ"));
1205
1206 /* Set custom environment options from RSA authentication. */
1207 if (!options.use_login) {
1208 while (custom_environment) {
1209 struct envstring *ce = custom_environment;
1210 char *str = ce->s;
1211
1212 for (i = 0; str[i] != '=' && str[i]; i++)
1213 ;
1214 if (str[i] == '=') {
1215 str[i] = 0;
1216 child_set_env(&env, &envsize, str, str + i + 1);
1217 }
1218 custom_environment = ce->next;
1219 xfree(ce->s);
1220 xfree(ce);
1221 }
1222 }
1223
1224 /* SSH_CLIENT deprecated */
1225 snprintf(buf, sizeof buf, "%.50s %d %d",
1226 get_remote_ipaddr(), get_remote_port(), get_local_port());
1227 child_set_env(&env, &envsize, "SSH_CLIENT", buf);
1228
1229 laddr = get_local_ipaddr(packet_get_connection_in());
1230 snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
1231 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port());
1232 xfree(laddr);
1233 child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
1234
1235 if (s->ttyfd != -1)
1236 child_set_env(&env, &envsize, "SSH_TTY", s->tty);
1237 if (s->term)
1238 child_set_env(&env, &envsize, "TERM", s->term);
1239 if (s->display)
1240 child_set_env(&env, &envsize, "DISPLAY", s->display);
1241 if (original_command)
1242 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
1243 original_command);
1244
1245 #ifdef _UNICOS
1246 if (cray_tmpdir[0] != '\0')
1247 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir);
1248 #endif /* _UNICOS */
1249
1250 /*
1251 * Since we clear KRB5CCNAME at startup, if it's set now then it
1252 * must have been set by a native authentication method (eg AIX or
1253 * SIA), so copy it to the child.
1254 */
1255 {
1256 char *cp;
1257
1258 if ((cp = getenv("KRB5CCNAME")) != NULL)
1259 child_set_env(&env, &envsize, "KRB5CCNAME", cp);
1260 }
1261
1262 #ifdef _AIX
1263 {
1264 char *cp;
1265
1266 if ((cp = getenv("AUTHSTATE")) != NULL)
1267 child_set_env(&env, &envsize, "AUTHSTATE", cp);
1268 read_environment_file(&env, &envsize, "/etc/environment");
1269 }
1270 #endif
1271 #ifdef KRB5
1272 if (s->authctxt->krb5_ccname)
1273 child_set_env(&env, &envsize, "KRB5CCNAME",
1274 s->authctxt->krb5_ccname);
1275 #endif
1276 #ifdef USE_PAM
1277 /*
1278 * Pull in any environment variables that may have
1279 * been set by PAM.
1280 */
1281 if (options.use_pam) {
1282 char **p;
1283
1284 p = fetch_pam_child_environment();
1285 copy_environment(p, &env, &envsize);
1286 free_pam_environment(p);
1287
1288 p = fetch_pam_environment();
1289 copy_environment(p, &env, &envsize);
1290 free_pam_environment(p);
1291 }
1292 #endif /* USE_PAM */
1293
1294 if (auth_sock_name != NULL)
1295 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
1296 auth_sock_name);
1297
1298 /* read $HOME/.ssh/environment. */
1299 if (options.permit_user_env && !options.use_login) {
1300 snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
1301 strcmp(pw->pw_dir, "/") ? pw->pw_dir : "");
1302 read_environment_file(&env, &envsize, buf);
1303 }
1304 if (debug_flag) {
1305 /* dump the environment */
1306 fprintf(stderr, "Environment:\n");
1307 for (i = 0; env[i]; i++)
1308 fprintf(stderr, " %.200s\n", env[i]);
1309 }
1310 return env;
1311 }
1312
1313 /*
1314 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found
1315 * first in this order).
1316 */
1317 static void
do_rc_files(Session * s,const char * shell)1318 do_rc_files(Session *s, const char *shell)
1319 {
1320 FILE *f = NULL;
1321 char cmd[1024];
1322 int do_xauth;
1323 struct stat st;
1324
1325 do_xauth =
1326 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
1327
1328 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */
1329 if (!s->is_subsystem && options.adm_forced_command == NULL &&
1330 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) {
1331 snprintf(cmd, sizeof cmd, "%s -c '%s %s'",
1332 shell, _PATH_BSHELL, _PATH_SSH_USER_RC);
1333 if (debug_flag)
1334 fprintf(stderr, "Running %s\n", cmd);
1335 f = popen(cmd, "w");
1336 if (f) {
1337 if (do_xauth)
1338 fprintf(f, "%s %s\n", s->auth_proto,
1339 s->auth_data);
1340 pclose(f);
1341 } else
1342 fprintf(stderr, "Could not run %s\n",
1343 _PATH_SSH_USER_RC);
1344 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) {
1345 if (debug_flag)
1346 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
1347 _PATH_SSH_SYSTEM_RC);
1348 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w");
1349 if (f) {
1350 if (do_xauth)
1351 fprintf(f, "%s %s\n", s->auth_proto,
1352 s->auth_data);
1353 pclose(f);
1354 } else
1355 fprintf(stderr, "Could not run %s\n",
1356 _PATH_SSH_SYSTEM_RC);
1357 } else if (do_xauth && options.xauth_location != NULL) {
1358 /* Add authority data to .Xauthority if appropriate. */
1359 if (debug_flag) {
1360 fprintf(stderr,
1361 "Running %.500s remove %.100s\n",
1362 options.xauth_location, s->auth_display);
1363 fprintf(stderr,
1364 "%.500s add %.100s %.100s %.100s\n",
1365 options.xauth_location, s->auth_display,
1366 s->auth_proto, s->auth_data);
1367 }
1368 snprintf(cmd, sizeof cmd, "%s -q -",
1369 options.xauth_location);
1370 f = popen(cmd, "w");
1371 if (f) {
1372 fprintf(f, "remove %s\n",
1373 s->auth_display);
1374 fprintf(f, "add %s %s %s\n",
1375 s->auth_display, s->auth_proto,
1376 s->auth_data);
1377 pclose(f);
1378 } else {
1379 fprintf(stderr, "Could not run %s\n",
1380 cmd);
1381 }
1382 }
1383 }
1384
1385 static void
do_nologin(struct passwd * pw)1386 do_nologin(struct passwd *pw)
1387 {
1388 FILE *f = NULL;
1389 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN;
1390 struct stat sb;
1391
1392 #ifdef HAVE_LOGIN_CAP
1393 if (login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid)
1394 return;
1395 nl = login_getcapstr(lc, "nologin", def_nl, def_nl);
1396 #else
1397 if (pw->pw_uid == 0)
1398 return;
1399 nl = def_nl;
1400 #endif
1401 if (stat(nl, &sb) == -1) {
1402 if (nl != def_nl)
1403 xfree(nl);
1404 return;
1405 }
1406
1407 /* /etc/nologin exists. Print its contents if we can and exit. */
1408 logit("User %.100s not allowed because %s exists", pw->pw_name, nl);
1409 if ((f = fopen(nl, "r")) != NULL) {
1410 while (fgets(buf, sizeof(buf), f))
1411 fputs(buf, stderr);
1412 fclose(f);
1413 }
1414 exit(254);
1415 }
1416
1417 /*
1418 * Chroot into a directory after checking it for safety: all path components
1419 * must be root-owned directories with strict permissions.
1420 */
1421 static void
safely_chroot(const char * path,uid_t uid)1422 safely_chroot(const char *path, uid_t uid)
1423 {
1424 const char *cp;
1425 char component[MAXPATHLEN];
1426 struct stat st;
1427
1428 if (*path != '/')
1429 fatal("chroot path does not begin at root");
1430 if (strlen(path) >= sizeof(component))
1431 fatal("chroot path too long");
1432
1433 /*
1434 * Descend the path, checking that each component is a
1435 * root-owned directory with strict permissions.
1436 */
1437 for (cp = path; cp != NULL;) {
1438 if ((cp = strchr(cp, '/')) == NULL)
1439 strlcpy(component, path, sizeof(component));
1440 else {
1441 cp++;
1442 memcpy(component, path, cp - path);
1443 component[cp - path] = '\0';
1444 }
1445
1446 debug3("%s: checking '%s'", __func__, component);
1447
1448 if (stat(component, &st) != 0)
1449 fatal("%s: stat(\"%s\"): %s", __func__,
1450 component, strerror(errno));
1451 if (st.st_uid != 0 || (st.st_mode & 022) != 0)
1452 fatal("bad ownership or modes for chroot "
1453 "directory %s\"%s\"",
1454 cp == NULL ? "" : "component ", component);
1455 if (!S_ISDIR(st.st_mode))
1456 fatal("chroot path %s\"%s\" is not a directory",
1457 cp == NULL ? "" : "component ", component);
1458
1459 }
1460
1461 if (chdir(path) == -1)
1462 fatal("Unable to chdir to chroot path \"%s\": "
1463 "%s", path, strerror(errno));
1464 if (chroot(path) == -1)
1465 fatal("chroot(\"%s\"): %s", path, strerror(errno));
1466 if (chdir("/") == -1)
1467 fatal("%s: chdir(/) after chroot: %s",
1468 __func__, strerror(errno));
1469 verbose("Changed root directory to \"%s\"", path);
1470 }
1471
1472 /* Set login name, uid, gid, and groups. */
1473 void
do_setusercontext(struct passwd * pw)1474 do_setusercontext(struct passwd *pw)
1475 {
1476 char *chroot_path, *tmp;
1477
1478 platform_setusercontext(pw);
1479
1480 if (platform_privileged_uidswap()) {
1481 #ifdef HAVE_LOGIN_CAP
1482 if (setusercontext(lc, pw, pw->pw_uid,
1483 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) {
1484 perror("unable to set user context");
1485 exit(1);
1486 }
1487 #else
1488 if (setlogin(pw->pw_name) < 0)
1489 error("setlogin failed: %s", strerror(errno));
1490 if (setgid(pw->pw_gid) < 0) {
1491 perror("setgid");
1492 exit(1);
1493 }
1494 /* Initialize the group list. */
1495 if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
1496 perror("initgroups");
1497 exit(1);
1498 }
1499 #ifndef ANDROID
1500 /* FIXME - Android doesn't have this */
1501 endgrent();
1502 #endif
1503 #endif
1504
1505 platform_setusercontext_post_groups(pw);
1506
1507 if (options.chroot_directory != NULL &&
1508 strcasecmp(options.chroot_directory, "none") != 0) {
1509 tmp = tilde_expand_filename(options.chroot_directory,
1510 pw->pw_uid);
1511 chroot_path = percent_expand(tmp, "h", pw->pw_dir,
1512 "u", pw->pw_name, (char *)NULL);
1513 safely_chroot(chroot_path, pw->pw_uid);
1514 free(tmp);
1515 free(chroot_path);
1516 }
1517
1518 #ifdef HAVE_LOGIN_CAP
1519 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) {
1520 perror("unable to set user context (setuser)");
1521 exit(1);
1522 }
1523 #else
1524 /* Permanently switch to the desired uid. */
1525 permanently_set_uid(pw);
1526 #endif
1527 }
1528
1529 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
1530 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
1531 }
1532
1533 static void
do_pwchange(Session * s)1534 do_pwchange(Session *s)
1535 {
1536 fflush(NULL);
1537 fprintf(stderr, "WARNING: Your password has expired.\n");
1538 if (s->ttyfd != -1) {
1539 fprintf(stderr,
1540 "You must change your password now and login again!\n");
1541 #ifdef WITH_SELINUX
1542 setexeccon(NULL);
1543 #endif
1544 #ifdef PASSWD_NEEDS_USERNAME
1545 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name,
1546 (char *)NULL);
1547 #else
1548 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL);
1549 #endif
1550 perror("passwd");
1551 } else {
1552 fprintf(stderr,
1553 "Password change required but no TTY available.\n");
1554 }
1555 exit(1);
1556 }
1557
1558 static void
launch_login(struct passwd * pw,const char * hostname)1559 launch_login(struct passwd *pw, const char *hostname)
1560 {
1561 /* Launch login(1). */
1562
1563 execl(LOGIN_PROGRAM, "login", "-h", hostname,
1564 #ifdef xxxLOGIN_NEEDS_TERM
1565 (s->term ? s->term : "unknown"),
1566 #endif /* LOGIN_NEEDS_TERM */
1567 #ifdef LOGIN_NO_ENDOPT
1568 "-p", "-f", pw->pw_name, (char *)NULL);
1569 #else
1570 "-p", "-f", "--", pw->pw_name, (char *)NULL);
1571 #endif
1572
1573 /* Login couldn't be executed, die. */
1574
1575 perror("login");
1576 exit(1);
1577 }
1578
1579 static void
child_close_fds(void)1580 child_close_fds(void)
1581 {
1582 if (packet_get_connection_in() == packet_get_connection_out())
1583 close(packet_get_connection_in());
1584 else {
1585 close(packet_get_connection_in());
1586 close(packet_get_connection_out());
1587 }
1588 /*
1589 * Close all descriptors related to channels. They will still remain
1590 * open in the parent.
1591 */
1592 /* XXX better use close-on-exec? -markus */
1593 channel_close_all();
1594
1595 /*
1596 * Close any extra file descriptors. Note that there may still be
1597 * descriptors left by system functions. They will be closed later.
1598 */
1599 endpwent();
1600
1601 /*
1602 * Close any extra open file descriptors so that we don't have them
1603 * hanging around in clients. Note that we want to do this after
1604 * initgroups, because at least on Solaris 2.3 it leaves file
1605 * descriptors open.
1606 */
1607 closefrom(STDERR_FILENO + 1);
1608 }
1609
1610 /*
1611 * Performs common processing for the child, such as setting up the
1612 * environment, closing extra file descriptors, setting the user and group
1613 * ids, and executing the command or shell.
1614 */
1615 #define ARGV_MAX 10
1616 void
do_child(Session * s,const char * command)1617 do_child(Session *s, const char *command)
1618 {
1619 extern char **environ;
1620 char **env;
1621 char *argv[ARGV_MAX];
1622 const char *shell, *shell0, *hostname = NULL;
1623 struct passwd *pw = s->pw;
1624 int r = 0;
1625
1626 /* remove hostkey from the child's memory */
1627 destroy_sensitive_data();
1628
1629 /* Force a password change */
1630 if (s->authctxt->force_pwchange) {
1631 do_setusercontext(pw);
1632 child_close_fds();
1633 do_pwchange(s);
1634 exit(1);
1635 }
1636
1637 /* login(1) is only called if we execute the login shell */
1638 if (options.use_login && command != NULL)
1639 options.use_login = 0;
1640
1641 #ifdef _UNICOS
1642 cray_setup(pw->pw_uid, pw->pw_name, command);
1643 #endif /* _UNICOS */
1644
1645 /*
1646 * Login(1) does this as well, and it needs uid 0 for the "-h"
1647 * switch, so we let login(1) to this for us.
1648 */
1649 if (!options.use_login) {
1650 #ifdef HAVE_OSF_SIA
1651 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty);
1652 if (!check_quietlogin(s, command))
1653 do_motd();
1654 #else /* HAVE_OSF_SIA */
1655 /* When PAM is enabled we rely on it to do the nologin check */
1656 if (!options.use_pam)
1657 do_nologin(pw);
1658 do_setusercontext(pw);
1659 /*
1660 * PAM session modules in do_setusercontext may have
1661 * generated messages, so if this in an interactive
1662 * login then display them too.
1663 */
1664 if (!check_quietlogin(s, command))
1665 display_loginmsg();
1666 #endif /* HAVE_OSF_SIA */
1667 }
1668
1669 #ifdef USE_PAM
1670 if (options.use_pam && !options.use_login && !is_pam_session_open()) {
1671 debug3("PAM session not opened, exiting");
1672 display_loginmsg();
1673 exit(254);
1674 }
1675 #endif
1676
1677 /*
1678 * Get the shell from the password data. An empty shell field is
1679 * legal, and means /bin/sh.
1680 */
1681 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
1682
1683 /*
1684 * Make sure $SHELL points to the shell from the password file,
1685 * even if shell is overridden from login.conf
1686 */
1687 env = do_setup_env(s, shell);
1688
1689 #ifdef HAVE_LOGIN_CAP
1690 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
1691 #endif
1692
1693 /* we have to stash the hostname before we close our socket. */
1694 if (options.use_login)
1695 hostname = get_remote_name_or_ip(utmp_len,
1696 options.use_dns);
1697 /*
1698 * Close the connection descriptors; note that this is the child, and
1699 * the server will still have the socket open, and it is important
1700 * that we do not shutdown it. Note that the descriptors cannot be
1701 * closed before building the environment, as we call
1702 * get_remote_ipaddr there.
1703 */
1704 child_close_fds();
1705
1706 /*
1707 * Must take new environment into use so that .ssh/rc,
1708 * /etc/ssh/sshrc and xauth are run in the proper environment.
1709 */
1710 environ = env;
1711
1712 #if defined(KRB5) && defined(USE_AFS)
1713 /*
1714 * At this point, we check to see if AFS is active and if we have
1715 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see
1716 * if we can (and need to) extend the ticket into an AFS token. If
1717 * we don't do this, we run into potential problems if the user's
1718 * home directory is in AFS and it's not world-readable.
1719 */
1720
1721 if (options.kerberos_get_afs_token && k_hasafs() &&
1722 (s->authctxt->krb5_ctx != NULL)) {
1723 char cell[64];
1724
1725 debug("Getting AFS token");
1726
1727 k_setpag();
1728
1729 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
1730 krb5_afslog(s->authctxt->krb5_ctx,
1731 s->authctxt->krb5_fwd_ccache, cell, NULL);
1732
1733 krb5_afslog_home(s->authctxt->krb5_ctx,
1734 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir);
1735 }
1736 #endif
1737
1738 /* Change current directory to the user's home directory. */
1739 if (chdir(pw->pw_dir) < 0) {
1740 /* Suppress missing homedir warning for chroot case */
1741 #ifdef HAVE_LOGIN_CAP
1742 r = login_getcapbool(lc, "requirehome", 0);
1743 #endif
1744 if (r || options.chroot_directory == NULL ||
1745 strcasecmp(options.chroot_directory, "none") == 0)
1746 fprintf(stderr, "Could not chdir to home "
1747 "directory %s: %s\n", pw->pw_dir,
1748 strerror(errno));
1749 if (r)
1750 exit(1);
1751 }
1752
1753 closefrom(STDERR_FILENO + 1);
1754
1755 if (!options.use_login)
1756 do_rc_files(s, shell);
1757
1758 /* restore SIGPIPE for child */
1759 signal(SIGPIPE, SIG_DFL);
1760
1761 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) {
1762 printf("This service allows sftp connections only.\n");
1763 fflush(NULL);
1764 exit(1);
1765 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) {
1766 extern int optind, optreset;
1767 int i;
1768 char *p, *args;
1769
1770 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME);
1771 args = xstrdup(command ? command : "sftp-server");
1772 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " ")))
1773 if (i < ARGV_MAX - 1)
1774 argv[i++] = p;
1775 argv[i] = NULL;
1776 optind = optreset = 1;
1777 __progname = argv[0];
1778 #ifdef WITH_SELINUX
1779 ssh_selinux_change_context("sftpd_t");
1780 #endif
1781 exit(sftp_server_main(i, argv, s->pw));
1782 }
1783
1784 fflush(NULL);
1785
1786 if (options.use_login) {
1787 launch_login(pw, hostname);
1788 /* NEVERREACHED */
1789 }
1790
1791 /* Get the last component of the shell name. */
1792 if ((shell0 = strrchr(shell, '/')) != NULL)
1793 shell0++;
1794 else
1795 shell0 = shell;
1796
1797 /*
1798 * If we have no command, execute the shell. In this case, the shell
1799 * name to be passed in argv[0] is preceded by '-' to indicate that
1800 * this is a login shell.
1801 */
1802 if (!command) {
1803 char argv0[256];
1804
1805 /* Start the shell. Set initial character to '-'. */
1806 argv0[0] = '-';
1807
1808 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1)
1809 >= sizeof(argv0) - 1) {
1810 errno = EINVAL;
1811 perror(shell);
1812 exit(1);
1813 }
1814
1815 /* Execute the shell. */
1816 argv[0] = argv0;
1817 argv[1] = NULL;
1818 execve(shell, argv, env);
1819
1820 /* Executing the shell failed. */
1821 perror(shell);
1822 exit(1);
1823 }
1824 /*
1825 * Execute the command using the user's shell. This uses the -c
1826 * option to execute the command.
1827 */
1828 argv[0] = (char *) shell0;
1829 argv[1] = "-c";
1830 argv[2] = (char *) command;
1831 argv[3] = NULL;
1832 execve(shell, argv, env);
1833 perror(shell);
1834 exit(1);
1835 }
1836
1837 void
session_unused(int id)1838 session_unused(int id)
1839 {
1840 debug3("%s: session id %d unused", __func__, id);
1841 if (id >= options.max_sessions ||
1842 id >= sessions_nalloc) {
1843 fatal("%s: insane session id %d (max %d nalloc %d)",
1844 __func__, id, options.max_sessions, sessions_nalloc);
1845 }
1846 bzero(&sessions[id], sizeof(*sessions));
1847 sessions[id].self = id;
1848 sessions[id].used = 0;
1849 sessions[id].chanid = -1;
1850 sessions[id].ptyfd = -1;
1851 sessions[id].ttyfd = -1;
1852 sessions[id].ptymaster = -1;
1853 sessions[id].x11_chanids = NULL;
1854 sessions[id].next_unused = sessions_first_unused;
1855 sessions_first_unused = id;
1856 }
1857
1858 Session *
session_new(void)1859 session_new(void)
1860 {
1861 Session *s, *tmp;
1862
1863 if (sessions_first_unused == -1) {
1864 if (sessions_nalloc >= options.max_sessions)
1865 return NULL;
1866 debug2("%s: allocate (allocated %d max %d)",
1867 __func__, sessions_nalloc, options.max_sessions);
1868 tmp = xrealloc(sessions, sessions_nalloc + 1,
1869 sizeof(*sessions));
1870 if (tmp == NULL) {
1871 error("%s: cannot allocate %d sessions",
1872 __func__, sessions_nalloc + 1);
1873 return NULL;
1874 }
1875 sessions = tmp;
1876 session_unused(sessions_nalloc++);
1877 }
1878
1879 if (sessions_first_unused >= sessions_nalloc ||
1880 sessions_first_unused < 0) {
1881 fatal("%s: insane first_unused %d max %d nalloc %d",
1882 __func__, sessions_first_unused, options.max_sessions,
1883 sessions_nalloc);
1884 }
1885
1886 s = &sessions[sessions_first_unused];
1887 if (s->used) {
1888 fatal("%s: session %d already used",
1889 __func__, sessions_first_unused);
1890 }
1891 sessions_first_unused = s->next_unused;
1892 s->used = 1;
1893 s->next_unused = -1;
1894 debug("session_new: session %d", s->self);
1895
1896 return s;
1897 }
1898
1899 static void
session_dump(void)1900 session_dump(void)
1901 {
1902 int i;
1903 for (i = 0; i < sessions_nalloc; i++) {
1904 Session *s = &sessions[i];
1905
1906 debug("dump: used %d next_unused %d session %d %p "
1907 "channel %d pid %ld",
1908 s->used,
1909 s->next_unused,
1910 s->self,
1911 s,
1912 s->chanid,
1913 (long)s->pid);
1914 }
1915 }
1916
1917 int
session_open(Authctxt * authctxt,int chanid)1918 session_open(Authctxt *authctxt, int chanid)
1919 {
1920 Session *s = session_new();
1921 debug("session_open: channel %d", chanid);
1922 if (s == NULL) {
1923 error("no more sessions");
1924 return 0;
1925 }
1926 s->authctxt = authctxt;
1927 s->pw = authctxt->pw;
1928 if (s->pw == NULL || !authctxt->valid)
1929 fatal("no user for session %d", s->self);
1930 debug("session_open: session %d: link with channel %d", s->self, chanid);
1931 s->chanid = chanid;
1932 return 1;
1933 }
1934
1935 Session *
session_by_tty(char * tty)1936 session_by_tty(char *tty)
1937 {
1938 int i;
1939 for (i = 0; i < sessions_nalloc; i++) {
1940 Session *s = &sessions[i];
1941 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
1942 debug("session_by_tty: session %d tty %s", i, tty);
1943 return s;
1944 }
1945 }
1946 debug("session_by_tty: unknown tty %.100s", tty);
1947 session_dump();
1948 return NULL;
1949 }
1950
1951 static Session *
session_by_channel(int id)1952 session_by_channel(int id)
1953 {
1954 int i;
1955 for (i = 0; i < sessions_nalloc; i++) {
1956 Session *s = &sessions[i];
1957 if (s->used && s->chanid == id) {
1958 debug("session_by_channel: session %d channel %d",
1959 i, id);
1960 return s;
1961 }
1962 }
1963 debug("session_by_channel: unknown channel %d", id);
1964 session_dump();
1965 return NULL;
1966 }
1967
1968 static Session *
session_by_x11_channel(int id)1969 session_by_x11_channel(int id)
1970 {
1971 int i, j;
1972
1973 for (i = 0; i < sessions_nalloc; i++) {
1974 Session *s = &sessions[i];
1975
1976 if (s->x11_chanids == NULL || !s->used)
1977 continue;
1978 for (j = 0; s->x11_chanids[j] != -1; j++) {
1979 if (s->x11_chanids[j] == id) {
1980 debug("session_by_x11_channel: session %d "
1981 "channel %d", s->self, id);
1982 return s;
1983 }
1984 }
1985 }
1986 debug("session_by_x11_channel: unknown channel %d", id);
1987 session_dump();
1988 return NULL;
1989 }
1990
1991 static Session *
session_by_pid(pid_t pid)1992 session_by_pid(pid_t pid)
1993 {
1994 int i;
1995 debug("session_by_pid: pid %ld", (long)pid);
1996 for (i = 0; i < sessions_nalloc; i++) {
1997 Session *s = &sessions[i];
1998 if (s->used && s->pid == pid)
1999 return s;
2000 }
2001 error("session_by_pid: unknown pid %ld", (long)pid);
2002 session_dump();
2003 return NULL;
2004 }
2005
2006 static int
session_window_change_req(Session * s)2007 session_window_change_req(Session *s)
2008 {
2009 s->col = packet_get_int();
2010 s->row = packet_get_int();
2011 s->xpixel = packet_get_int();
2012 s->ypixel = packet_get_int();
2013 packet_check_eom();
2014 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
2015 return 1;
2016 }
2017
2018 static int
session_pty_req(Session * s)2019 session_pty_req(Session *s)
2020 {
2021 u_int len;
2022 int n_bytes;
2023
2024 if (no_pty_flag) {
2025 debug("Allocating a pty not permitted for this authentication.");
2026 return 0;
2027 }
2028 if (s->ttyfd != -1) {
2029 packet_disconnect("Protocol error: you already have a pty.");
2030 return 0;
2031 }
2032
2033 s->term = packet_get_string(&len);
2034
2035 if (compat20) {
2036 s->col = packet_get_int();
2037 s->row = packet_get_int();
2038 } else {
2039 s->row = packet_get_int();
2040 s->col = packet_get_int();
2041 }
2042 s->xpixel = packet_get_int();
2043 s->ypixel = packet_get_int();
2044
2045 if (strcmp(s->term, "") == 0) {
2046 xfree(s->term);
2047 s->term = NULL;
2048 }
2049
2050 /* Allocate a pty and open it. */
2051 debug("Allocating pty.");
2052 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty,
2053 sizeof(s->tty)))) {
2054 if (s->term)
2055 xfree(s->term);
2056 s->term = NULL;
2057 s->ptyfd = -1;
2058 s->ttyfd = -1;
2059 error("session_pty_req: session %d alloc failed", s->self);
2060 return 0;
2061 }
2062 debug("session_pty_req: session %d alloc %s", s->self, s->tty);
2063
2064 /* for SSH1 the tty modes length is not given */
2065 if (!compat20)
2066 n_bytes = packet_remaining();
2067 tty_parse_modes(s->ttyfd, &n_bytes);
2068
2069 if (!use_privsep)
2070 pty_setowner(s->pw, s->tty);
2071
2072 /* Set window size from the packet. */
2073 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
2074
2075 packet_check_eom();
2076 session_proctitle(s);
2077 return 1;
2078 }
2079
2080 static int
session_subsystem_req(Session * s)2081 session_subsystem_req(Session *s)
2082 {
2083 struct stat st;
2084 u_int len;
2085 int success = 0;
2086 char *prog, *cmd, *subsys = packet_get_string(&len);
2087 u_int i;
2088
2089 packet_check_eom();
2090 logit("subsystem request for %.100s by user %s", subsys,
2091 s->pw->pw_name);
2092
2093 for (i = 0; i < options.num_subsystems; i++) {
2094 if (strcmp(subsys, options.subsystem_name[i]) == 0) {
2095 prog = options.subsystem_command[i];
2096 cmd = options.subsystem_args[i];
2097 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) {
2098 s->is_subsystem = SUBSYSTEM_INT_SFTP;
2099 debug("subsystem: %s", prog);
2100 } else {
2101 if (stat(prog, &st) < 0)
2102 debug("subsystem: cannot stat %s: %s",
2103 prog, strerror(errno));
2104 s->is_subsystem = SUBSYSTEM_EXT;
2105 debug("subsystem: exec() %s", cmd);
2106 }
2107 success = do_exec(s, cmd) == 0;
2108 break;
2109 }
2110 }
2111
2112 if (!success)
2113 logit("subsystem request for %.100s failed, subsystem not found",
2114 subsys);
2115
2116 xfree(subsys);
2117 return success;
2118 }
2119
2120 static int
session_x11_req(Session * s)2121 session_x11_req(Session *s)
2122 {
2123 int success;
2124
2125 if (s->auth_proto != NULL || s->auth_data != NULL) {
2126 error("session_x11_req: session %d: "
2127 "x11 forwarding already active", s->self);
2128 return 0;
2129 }
2130 s->single_connection = packet_get_char();
2131 s->auth_proto = packet_get_string(NULL);
2132 s->auth_data = packet_get_string(NULL);
2133 s->screen = packet_get_int();
2134 packet_check_eom();
2135
2136 success = session_setup_x11fwd(s);
2137 if (!success) {
2138 xfree(s->auth_proto);
2139 xfree(s->auth_data);
2140 s->auth_proto = NULL;
2141 s->auth_data = NULL;
2142 }
2143 return success;
2144 }
2145
2146 static int
session_shell_req(Session * s)2147 session_shell_req(Session *s)
2148 {
2149 packet_check_eom();
2150 return do_exec(s, NULL) == 0;
2151 }
2152
2153 static int
session_exec_req(Session * s)2154 session_exec_req(Session *s)
2155 {
2156 u_int len, success;
2157
2158 char *command = packet_get_string(&len);
2159 packet_check_eom();
2160 success = do_exec(s, command) == 0;
2161 xfree(command);
2162 return success;
2163 }
2164
2165 static int
session_break_req(Session * s)2166 session_break_req(Session *s)
2167 {
2168
2169 packet_get_int(); /* ignored */
2170 packet_check_eom();
2171
2172 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0)
2173 return 0;
2174 return 1;
2175 }
2176
2177 static int
session_env_req(Session * s)2178 session_env_req(Session *s)
2179 {
2180 char *name, *val;
2181 u_int name_len, val_len, i;
2182
2183 name = packet_get_string(&name_len);
2184 val = packet_get_string(&val_len);
2185 packet_check_eom();
2186
2187 /* Don't set too many environment variables */
2188 if (s->num_env > 128) {
2189 debug2("Ignoring env request %s: too many env vars", name);
2190 goto fail;
2191 }
2192
2193 for (i = 0; i < options.num_accept_env; i++) {
2194 if (match_pattern(name, options.accept_env[i])) {
2195 debug2("Setting env %d: %s=%s", s->num_env, name, val);
2196 s->env = xrealloc(s->env, s->num_env + 1,
2197 sizeof(*s->env));
2198 s->env[s->num_env].name = name;
2199 s->env[s->num_env].val = val;
2200 s->num_env++;
2201 return (1);
2202 }
2203 }
2204 debug2("Ignoring env request %s: disallowed name", name);
2205
2206 fail:
2207 xfree(name);
2208 xfree(val);
2209 return (0);
2210 }
2211
2212 static int
session_auth_agent_req(Session * s)2213 session_auth_agent_req(Session *s)
2214 {
2215 static int called = 0;
2216 packet_check_eom();
2217 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) {
2218 debug("session_auth_agent_req: no_agent_forwarding_flag");
2219 return 0;
2220 }
2221 if (called) {
2222 return 0;
2223 } else {
2224 called = 1;
2225 return auth_input_request_forwarding(s->pw);
2226 }
2227 }
2228
2229 int
session_input_channel_req(Channel * c,const char * rtype)2230 session_input_channel_req(Channel *c, const char *rtype)
2231 {
2232 int success = 0;
2233 Session *s;
2234
2235 if ((s = session_by_channel(c->self)) == NULL) {
2236 logit("session_input_channel_req: no session %d req %.100s",
2237 c->self, rtype);
2238 return 0;
2239 }
2240 debug("session_input_channel_req: session %d req %s", s->self, rtype);
2241
2242 /*
2243 * a session is in LARVAL state until a shell, a command
2244 * or a subsystem is executed
2245 */
2246 if (c->type == SSH_CHANNEL_LARVAL) {
2247 if (strcmp(rtype, "shell") == 0) {
2248 success = session_shell_req(s);
2249 } else if (strcmp(rtype, "exec") == 0) {
2250 success = session_exec_req(s);
2251 } else if (strcmp(rtype, "pty-req") == 0) {
2252 success = session_pty_req(s);
2253 } else if (strcmp(rtype, "x11-req") == 0) {
2254 success = session_x11_req(s);
2255 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
2256 success = session_auth_agent_req(s);
2257 } else if (strcmp(rtype, "subsystem") == 0) {
2258 success = session_subsystem_req(s);
2259 } else if (strcmp(rtype, "env") == 0) {
2260 success = session_env_req(s);
2261 }
2262 }
2263 if (strcmp(rtype, "window-change") == 0) {
2264 success = session_window_change_req(s);
2265 } else if (strcmp(rtype, "break") == 0) {
2266 success = session_break_req(s);
2267 }
2268
2269 return success;
2270 }
2271
2272 void
session_set_fds(Session * s,int fdin,int fdout,int fderr,int ignore_fderr,int is_tty)2273 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr,
2274 int is_tty)
2275 {
2276 if (!compat20)
2277 fatal("session_set_fds: called for proto != 2.0");
2278 /*
2279 * now that have a child and a pipe to the child,
2280 * we can activate our channel and register the fd's
2281 */
2282 if (s->chanid == -1)
2283 fatal("no channel for session %d", s->self);
2284 channel_set_fds(s->chanid,
2285 fdout, fdin, fderr,
2286 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
2287 1, is_tty, CHAN_SES_WINDOW_DEFAULT);
2288 }
2289
2290 /*
2291 * Function to perform pty cleanup. Also called if we get aborted abnormally
2292 * (e.g., due to a dropped connection).
2293 */
2294 void
session_pty_cleanup2(Session * s)2295 session_pty_cleanup2(Session *s)
2296 {
2297 if (s == NULL) {
2298 error("session_pty_cleanup: no session");
2299 return;
2300 }
2301 if (s->ttyfd == -1)
2302 return;
2303
2304 debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
2305
2306 /* Record that the user has logged out. */
2307 if (s->pid != 0)
2308 record_logout(s->pid, s->tty, s->pw->pw_name);
2309
2310 /* Release the pseudo-tty. */
2311 if (getuid() == 0)
2312 pty_release(s->tty);
2313
2314 /*
2315 * Close the server side of the socket pairs. We must do this after
2316 * the pty cleanup, so that another process doesn't get this pty
2317 * while we're still cleaning up.
2318 */
2319 if (s->ptymaster != -1 && close(s->ptymaster) < 0)
2320 error("close(s->ptymaster/%d): %s",
2321 s->ptymaster, strerror(errno));
2322
2323 /* unlink pty from session */
2324 s->ttyfd = -1;
2325 }
2326
2327 void
session_pty_cleanup(Session * s)2328 session_pty_cleanup(Session *s)
2329 {
2330 PRIVSEP(session_pty_cleanup2(s));
2331 }
2332
2333 static char *
sig2name(int sig)2334 sig2name(int sig)
2335 {
2336 #define SSH_SIG(x) if (sig == SIG ## x) return #x
2337 SSH_SIG(ABRT);
2338 SSH_SIG(ALRM);
2339 SSH_SIG(FPE);
2340 SSH_SIG(HUP);
2341 SSH_SIG(ILL);
2342 SSH_SIG(INT);
2343 SSH_SIG(KILL);
2344 SSH_SIG(PIPE);
2345 SSH_SIG(QUIT);
2346 SSH_SIG(SEGV);
2347 SSH_SIG(TERM);
2348 SSH_SIG(USR1);
2349 SSH_SIG(USR2);
2350 #undef SSH_SIG
2351 return "SIG@openssh.com";
2352 }
2353
2354 static void
session_close_x11(int id)2355 session_close_x11(int id)
2356 {
2357 Channel *c;
2358
2359 if ((c = channel_by_id(id)) == NULL) {
2360 debug("session_close_x11: x11 channel %d missing", id);
2361 } else {
2362 /* Detach X11 listener */
2363 debug("session_close_x11: detach x11 channel %d", id);
2364 channel_cancel_cleanup(id);
2365 if (c->ostate != CHAN_OUTPUT_CLOSED)
2366 chan_mark_dead(c);
2367 }
2368 }
2369
2370 static void
session_close_single_x11(int id,void * arg)2371 session_close_single_x11(int id, void *arg)
2372 {
2373 Session *s;
2374 u_int i;
2375
2376 debug3("session_close_single_x11: channel %d", id);
2377 channel_cancel_cleanup(id);
2378 if ((s = session_by_x11_channel(id)) == NULL)
2379 fatal("session_close_single_x11: no x11 channel %d", id);
2380 for (i = 0; s->x11_chanids[i] != -1; i++) {
2381 debug("session_close_single_x11: session %d: "
2382 "closing channel %d", s->self, s->x11_chanids[i]);
2383 /*
2384 * The channel "id" is already closing, but make sure we
2385 * close all of its siblings.
2386 */
2387 if (s->x11_chanids[i] != id)
2388 session_close_x11(s->x11_chanids[i]);
2389 }
2390 xfree(s->x11_chanids);
2391 s->x11_chanids = NULL;
2392 if (s->display) {
2393 xfree(s->display);
2394 s->display = NULL;
2395 }
2396 if (s->auth_proto) {
2397 xfree(s->auth_proto);
2398 s->auth_proto = NULL;
2399 }
2400 if (s->auth_data) {
2401 xfree(s->auth_data);
2402 s->auth_data = NULL;
2403 }
2404 if (s->auth_display) {
2405 xfree(s->auth_display);
2406 s->auth_display = NULL;
2407 }
2408 }
2409
2410 static void
session_exit_message(Session * s,int status)2411 session_exit_message(Session *s, int status)
2412 {
2413 Channel *c;
2414
2415 if ((c = channel_lookup(s->chanid)) == NULL)
2416 fatal("session_exit_message: session %d: no channel %d",
2417 s->self, s->chanid);
2418 debug("session_exit_message: session %d channel %d pid %ld",
2419 s->self, s->chanid, (long)s->pid);
2420
2421 if (WIFEXITED(status)) {
2422 channel_request_start(s->chanid, "exit-status", 0);
2423 packet_put_int(WEXITSTATUS(status));
2424 packet_send();
2425 } else if (WIFSIGNALED(status)) {
2426 channel_request_start(s->chanid, "exit-signal", 0);
2427 packet_put_cstring(sig2name(WTERMSIG(status)));
2428 #ifdef WCOREDUMP
2429 packet_put_char(WCOREDUMP(status)? 1 : 0);
2430 #else /* WCOREDUMP */
2431 packet_put_char(0);
2432 #endif /* WCOREDUMP */
2433 packet_put_cstring("");
2434 packet_put_cstring("");
2435 packet_send();
2436 } else {
2437 /* Some weird exit cause. Just exit. */
2438 packet_disconnect("wait returned status %04x.", status);
2439 }
2440
2441 /* disconnect channel */
2442 debug("session_exit_message: release channel %d", s->chanid);
2443
2444 /*
2445 * Adjust cleanup callback attachment to send close messages when
2446 * the channel gets EOF. The session will be then be closed
2447 * by session_close_by_channel when the childs close their fds.
2448 */
2449 channel_register_cleanup(c->self, session_close_by_channel, 1);
2450
2451 /*
2452 * emulate a write failure with 'chan_write_failed', nobody will be
2453 * interested in data we write.
2454 * Note that we must not call 'chan_read_failed', since there could
2455 * be some more data waiting in the pipe.
2456 */
2457 if (c->ostate != CHAN_OUTPUT_CLOSED)
2458 chan_write_failed(c);
2459 }
2460
2461 void
session_close(Session * s)2462 session_close(Session *s)
2463 {
2464 u_int i;
2465
2466 debug("session_close: session %d pid %ld", s->self, (long)s->pid);
2467 if (s->ttyfd != -1)
2468 session_pty_cleanup(s);
2469 if (s->term)
2470 xfree(s->term);
2471 if (s->display)
2472 xfree(s->display);
2473 if (s->x11_chanids)
2474 xfree(s->x11_chanids);
2475 if (s->auth_display)
2476 xfree(s->auth_display);
2477 if (s->auth_data)
2478 xfree(s->auth_data);
2479 if (s->auth_proto)
2480 xfree(s->auth_proto);
2481 if (s->env != NULL) {
2482 for (i = 0; i < s->num_env; i++) {
2483 xfree(s->env[i].name);
2484 xfree(s->env[i].val);
2485 }
2486 xfree(s->env);
2487 }
2488 session_proctitle(s);
2489 session_unused(s->self);
2490 }
2491
2492 void
session_close_by_pid(pid_t pid,int status)2493 session_close_by_pid(pid_t pid, int status)
2494 {
2495 Session *s = session_by_pid(pid);
2496 if (s == NULL) {
2497 debug("session_close_by_pid: no session for pid %ld",
2498 (long)pid);
2499 return;
2500 }
2501 if (s->chanid != -1)
2502 session_exit_message(s, status);
2503 if (s->ttyfd != -1)
2504 session_pty_cleanup(s);
2505 s->pid = 0;
2506 }
2507
2508 /*
2509 * this is called when a channel dies before
2510 * the session 'child' itself dies
2511 */
2512 void
session_close_by_channel(int id,void * arg)2513 session_close_by_channel(int id, void *arg)
2514 {
2515 Session *s = session_by_channel(id);
2516 u_int i;
2517
2518 if (s == NULL) {
2519 debug("session_close_by_channel: no session for id %d", id);
2520 return;
2521 }
2522 debug("session_close_by_channel: channel %d child %ld",
2523 id, (long)s->pid);
2524 if (s->pid != 0) {
2525 debug("session_close_by_channel: channel %d: has child", id);
2526 /*
2527 * delay detach of session, but release pty, since
2528 * the fd's to the child are already closed
2529 */
2530 if (s->ttyfd != -1)
2531 session_pty_cleanup(s);
2532 return;
2533 }
2534 /* detach by removing callback */
2535 channel_cancel_cleanup(s->chanid);
2536
2537 /* Close any X11 listeners associated with this session */
2538 if (s->x11_chanids != NULL) {
2539 for (i = 0; s->x11_chanids[i] != -1; i++) {
2540 session_close_x11(s->x11_chanids[i]);
2541 s->x11_chanids[i] = -1;
2542 }
2543 }
2544
2545 s->chanid = -1;
2546 session_close(s);
2547 }
2548
2549 void
session_destroy_all(void (* closefunc)(Session *))2550 session_destroy_all(void (*closefunc)(Session *))
2551 {
2552 int i;
2553 for (i = 0; i < sessions_nalloc; i++) {
2554 Session *s = &sessions[i];
2555 if (s->used) {
2556 if (closefunc != NULL)
2557 closefunc(s);
2558 else
2559 session_close(s);
2560 }
2561 }
2562 }
2563
2564 static char *
session_tty_list(void)2565 session_tty_list(void)
2566 {
2567 static char buf[1024];
2568 int i;
2569 char *cp;
2570
2571 buf[0] = '\0';
2572 for (i = 0; i < sessions_nalloc; i++) {
2573 Session *s = &sessions[i];
2574 if (s->used && s->ttyfd != -1) {
2575
2576 if (strncmp(s->tty, "/dev/", 5) != 0) {
2577 cp = strrchr(s->tty, '/');
2578 cp = (cp == NULL) ? s->tty : cp + 1;
2579 } else
2580 cp = s->tty + 5;
2581
2582 if (buf[0] != '\0')
2583 strlcat(buf, ",", sizeof buf);
2584 strlcat(buf, cp, sizeof buf);
2585 }
2586 }
2587 if (buf[0] == '\0')
2588 strlcpy(buf, "notty", sizeof buf);
2589 return buf;
2590 }
2591
2592 void
session_proctitle(Session * s)2593 session_proctitle(Session *s)
2594 {
2595 if (s->pw == NULL)
2596 error("no user for session %d", s->self);
2597 else
2598 setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
2599 }
2600
2601 int
session_setup_x11fwd(Session * s)2602 session_setup_x11fwd(Session *s)
2603 {
2604 struct stat st;
2605 char display[512], auth_display[512];
2606 char hostname[MAXHOSTNAMELEN];
2607 u_int i;
2608
2609 if (no_x11_forwarding_flag) {
2610 packet_send_debug("X11 forwarding disabled in user configuration file.");
2611 return 0;
2612 }
2613 if (!options.x11_forwarding) {
2614 debug("X11 forwarding disabled in server configuration file.");
2615 return 0;
2616 }
2617 if (!options.xauth_location ||
2618 (stat(options.xauth_location, &st) == -1)) {
2619 packet_send_debug("No xauth program; cannot forward with spoofing.");
2620 return 0;
2621 }
2622 if (options.use_login) {
2623 packet_send_debug("X11 forwarding disabled; "
2624 "not compatible with UseLogin=yes.");
2625 return 0;
2626 }
2627 if (s->display != NULL) {
2628 debug("X11 display already set.");
2629 return 0;
2630 }
2631 if (x11_create_display_inet(options.x11_display_offset,
2632 options.x11_use_localhost, s->single_connection,
2633 &s->display_number, &s->x11_chanids) == -1) {
2634 debug("x11_create_display_inet failed.");
2635 return 0;
2636 }
2637 for (i = 0; s->x11_chanids[i] != -1; i++) {
2638 channel_register_cleanup(s->x11_chanids[i],
2639 session_close_single_x11, 0);
2640 }
2641
2642 /* Set up a suitable value for the DISPLAY variable. */
2643 if (gethostname(hostname, sizeof(hostname)) < 0)
2644 fatal("gethostname: %.100s", strerror(errno));
2645 /*
2646 * auth_display must be used as the displayname when the
2647 * authorization entry is added with xauth(1). This will be
2648 * different than the DISPLAY string for localhost displays.
2649 */
2650 if (options.x11_use_localhost) {
2651 snprintf(display, sizeof display, "localhost:%u.%u",
2652 s->display_number, s->screen);
2653 snprintf(auth_display, sizeof auth_display, "unix:%u.%u",
2654 s->display_number, s->screen);
2655 s->display = xstrdup(display);
2656 s->auth_display = xstrdup(auth_display);
2657 } else {
2658 #ifdef IPADDR_IN_DISPLAY
2659 struct hostent *he;
2660 struct in_addr my_addr;
2661
2662 he = gethostbyname(hostname);
2663 if (he == NULL) {
2664 error("Can't get IP address for X11 DISPLAY.");
2665 packet_send_debug("Can't get IP address for X11 DISPLAY.");
2666 return 0;
2667 }
2668 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
2669 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr),
2670 s->display_number, s->screen);
2671 #else
2672 snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
2673 s->display_number, s->screen);
2674 #endif
2675 s->display = xstrdup(display);
2676 s->auth_display = xstrdup(display);
2677 }
2678
2679 return 1;
2680 }
2681
2682 static void
do_authenticated2(Authctxt * authctxt)2683 do_authenticated2(Authctxt *authctxt)
2684 {
2685 server_loop2(authctxt);
2686 }
2687
2688 void
do_cleanup(Authctxt * authctxt)2689 do_cleanup(Authctxt *authctxt)
2690 {
2691 static int called = 0;
2692
2693 debug("do_cleanup");
2694
2695 /* no cleanup if we're in the child for login shell */
2696 if (is_child)
2697 return;
2698
2699 /* avoid double cleanup */
2700 if (called)
2701 return;
2702 called = 1;
2703
2704 if (authctxt == NULL)
2705 return;
2706
2707 #ifdef USE_PAM
2708 if (options.use_pam) {
2709 sshpam_cleanup();
2710 sshpam_thread_cleanup();
2711 }
2712 #endif
2713
2714 if (!authctxt->authenticated)
2715 return;
2716
2717 #ifdef KRB5
2718 if (options.kerberos_ticket_cleanup &&
2719 authctxt->krb5_ctx)
2720 krb5_cleanup_proc(authctxt);
2721 #endif
2722
2723 #ifdef GSSAPI
2724 if (compat20 && options.gss_cleanup_creds)
2725 ssh_gssapi_cleanup_creds();
2726 #endif
2727
2728 /* remove agent socket */
2729 auth_sock_cleanup_proc(authctxt->pw);
2730
2731 /*
2732 * Cleanup ptys/utmp only if privsep is disabled,
2733 * or if running in monitor.
2734 */
2735 if (!use_privsep || mm_is_monitor())
2736 session_destroy_all(session_pty_cleanup2);
2737 }
2738