1 /* $OpenBSD: session.c,v 1.277 2015/01/16 06:40:12 deraadt 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 #include <netdb.h>
53 #ifdef HAVE_PATHS_H
54 #include <paths.h>
55 #endif
56 #include <pwd.h>
57 #include <signal.h>
58 #include <stdarg.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 #include <unistd.h>
63 #include <limits.h>
64
65 #include "openbsd-compat/sys-queue.h"
66 #include "xmalloc.h"
67 #include "ssh.h"
68 #include "ssh1.h"
69 #include "ssh2.h"
70 #include "sshpty.h"
71 #include "packet.h"
72 #include "buffer.h"
73 #include "match.h"
74 #include "uidswap.h"
75 #include "compat.h"
76 #include "channels.h"
77 #include "key.h"
78 #include "cipher.h"
79 #ifdef GSSAPI
80 #include "ssh-gss.h"
81 #endif
82 #include "hostfile.h"
83 #include "auth.h"
84 #include "auth-options.h"
85 #include "authfd.h"
86 #include "pathnames.h"
87 #include "log.h"
88 #include "misc.h"
89 #include "servconf.h"
90 #include "sshlogin.h"
91 #include "serverloop.h"
92 #include "canohost.h"
93 #include "session.h"
94 #include "kex.h"
95 #include "monitor_wrap.h"
96 #include "sftp.h"
97
98 #if defined(KRB5) && defined(USE_AFS)
99 #include <kafs.h>
100 #endif
101
102 #ifdef WITH_SELINUX
103 #include <selinux/selinux.h>
104 #endif
105
106 #define IS_INTERNAL_SFTP(c) \
107 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \
108 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \
109 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \
110 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t'))
111
112 /* func */
113
114 Session *session_new(void);
115 void session_set_fds(Session *, int, int, int, int, int);
116 void session_pty_cleanup(Session *);
117 void session_proctitle(Session *);
118 int session_setup_x11fwd(Session *);
119 int do_exec_pty(Session *, const char *);
120 int do_exec_no_pty(Session *, const char *);
121 int do_exec(Session *, const char *);
122 void do_login(Session *, const char *);
123 #ifdef LOGIN_NEEDS_UTMPX
124 static void do_pre_login(Session *s);
125 #endif
126 void do_child(Session *, const char *);
127 void do_motd(void);
128 int check_quietlogin(Session *, const char *);
129
130 static void do_authenticated1(Authctxt *);
131 static void do_authenticated2(Authctxt *);
132
133 static int session_pty_req(Session *);
134
135 /* import */
136 extern ServerOptions options;
137 extern char *__progname;
138 extern int log_stderr;
139 extern int debug_flag;
140 extern u_int utmp_len;
141 extern int startup_pipe;
142 extern void destroy_sensitive_data(void);
143 extern Buffer loginmsg;
144
145 /* original command from peer. */
146 const char *original_command = NULL;
147
148 /* data */
149 static int sessions_first_unused = -1;
150 static int sessions_nalloc = 0;
151 static Session *sessions = NULL;
152
153 #define SUBSYSTEM_NONE 0
154 #define SUBSYSTEM_EXT 1
155 #define SUBSYSTEM_INT_SFTP 2
156 #define SUBSYSTEM_INT_SFTP_ERROR 3
157
158 #ifdef HAVE_LOGIN_CAP
159 login_cap_t *lc;
160 #endif
161
162 static int is_child = 0;
163
164 /* Name and directory of socket for authentication agent forwarding. */
165 static char *auth_sock_name = NULL;
166 static char *auth_sock_dir = NULL;
167
168 /* removes the agent forwarding socket */
169
170 static void
auth_sock_cleanup_proc(struct passwd * pw)171 auth_sock_cleanup_proc(struct passwd *pw)
172 {
173 if (auth_sock_name != NULL) {
174 temporarily_use_uid(pw);
175 unlink(auth_sock_name);
176 rmdir(auth_sock_dir);
177 auth_sock_name = NULL;
178 restore_uid();
179 }
180 }
181
182 static int
auth_input_request_forwarding(struct passwd * pw)183 auth_input_request_forwarding(struct passwd * pw)
184 {
185 Channel *nc;
186 int sock = -1;
187
188 if (auth_sock_name != NULL) {
189 error("authentication forwarding requested twice.");
190 return 0;
191 }
192
193 /* Temporarily drop privileged uid for mkdir/bind. */
194 temporarily_use_uid(pw);
195
196 /* Allocate a buffer for the socket name, and format the name. */
197 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX");
198
199 /* Create private directory for socket */
200 if (mkdtemp(auth_sock_dir) == NULL) {
201 packet_send_debug("Agent forwarding disabled: "
202 "mkdtemp() failed: %.100s", strerror(errno));
203 restore_uid();
204 free(auth_sock_dir);
205 auth_sock_dir = NULL;
206 goto authsock_err;
207 }
208
209 xasprintf(&auth_sock_name, "%s/agent.%ld",
210 auth_sock_dir, (long) getpid());
211
212 /* Start a Unix listener on auth_sock_name. */
213 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0);
214
215 /* Restore the privileged uid. */
216 restore_uid();
217
218 /* Check for socket/bind/listen failure. */
219 if (sock < 0)
220 goto authsock_err;
221
222 /* Allocate a channel for the authentication agent socket. */
223 nc = channel_new("auth socket",
224 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
225 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
226 0, "auth socket", 1);
227 nc->path = xstrdup(auth_sock_name);
228 return 1;
229
230 authsock_err:
231 free(auth_sock_name);
232 if (auth_sock_dir != NULL) {
233 rmdir(auth_sock_dir);
234 free(auth_sock_dir);
235 }
236 if (sock != -1)
237 close(sock);
238 auth_sock_name = NULL;
239 auth_sock_dir = NULL;
240 return 0;
241 }
242
243 static void
display_loginmsg(void)244 display_loginmsg(void)
245 {
246 if (buffer_len(&loginmsg) > 0) {
247 buffer_append(&loginmsg, "\0", 1);
248 printf("%s", (char *)buffer_ptr(&loginmsg));
249 buffer_clear(&loginmsg);
250 }
251 }
252
253 void
do_authenticated(Authctxt * authctxt)254 do_authenticated(Authctxt *authctxt)
255 {
256 setproctitle("%s", authctxt->pw->pw_name);
257
258 /* setup the channel layer */
259 /* XXX - streamlocal? */
260 if (no_port_forwarding_flag ||
261 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0)
262 channel_disable_adm_local_opens();
263 else
264 channel_permit_all_opens();
265
266 auth_debug_send();
267
268 if (compat20)
269 do_authenticated2(authctxt);
270 else
271 do_authenticated1(authctxt);
272
273 do_cleanup(authctxt);
274 }
275
276 /*
277 * Prepares for an interactive session. This is called after the user has
278 * been successfully authenticated. During this message exchange, pseudo
279 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings
280 * are requested, etc.
281 */
282 static void
do_authenticated1(Authctxt * authctxt)283 do_authenticated1(Authctxt *authctxt)
284 {
285 Session *s;
286 char *command;
287 int success, type, screen_flag;
288 int enable_compression_after_reply = 0;
289 u_int proto_len, data_len, dlen, compression_level = 0;
290
291 s = session_new();
292 if (s == NULL) {
293 error("no more sessions");
294 return;
295 }
296 s->authctxt = authctxt;
297 s->pw = authctxt->pw;
298
299 /*
300 * We stay in this loop until the client requests to execute a shell
301 * or a command.
302 */
303 for (;;) {
304 success = 0;
305
306 /* Get a packet from the client. */
307 type = packet_read();
308
309 /* Process the packet. */
310 switch (type) {
311 case SSH_CMSG_REQUEST_COMPRESSION:
312 compression_level = packet_get_int();
313 packet_check_eom();
314 if (compression_level < 1 || compression_level > 9) {
315 packet_send_debug("Received invalid compression level %d.",
316 compression_level);
317 break;
318 }
319 if (options.compression == COMP_NONE) {
320 debug2("compression disabled");
321 break;
322 }
323 /* Enable compression after we have responded with SUCCESS. */
324 enable_compression_after_reply = 1;
325 success = 1;
326 break;
327
328 case SSH_CMSG_REQUEST_PTY:
329 success = session_pty_req(s);
330 break;
331
332 case SSH_CMSG_X11_REQUEST_FORWARDING:
333 s->auth_proto = packet_get_string(&proto_len);
334 s->auth_data = packet_get_string(&data_len);
335
336 screen_flag = packet_get_protocol_flags() &
337 SSH_PROTOFLAG_SCREEN_NUMBER;
338 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag);
339
340 if (packet_remaining() == 4) {
341 if (!screen_flag)
342 debug2("Buggy client: "
343 "X11 screen flag missing");
344 s->screen = packet_get_int();
345 } else {
346 s->screen = 0;
347 }
348 packet_check_eom();
349 success = session_setup_x11fwd(s);
350 if (!success) {
351 free(s->auth_proto);
352 free(s->auth_data);
353 s->auth_proto = NULL;
354 s->auth_data = NULL;
355 }
356 break;
357
358 case SSH_CMSG_AGENT_REQUEST_FORWARDING:
359 if (!options.allow_agent_forwarding ||
360 no_agent_forwarding_flag || compat13) {
361 debug("Authentication agent forwarding not permitted for this authentication.");
362 break;
363 }
364 debug("Received authentication agent forwarding request.");
365 success = auth_input_request_forwarding(s->pw);
366 break;
367
368 case SSH_CMSG_PORT_FORWARD_REQUEST:
369 if (no_port_forwarding_flag) {
370 debug("Port forwarding not permitted for this authentication.");
371 break;
372 }
373 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) {
374 debug("Port forwarding not permitted.");
375 break;
376 }
377 debug("Received TCP/IP port forwarding request.");
378 if (channel_input_port_forward_request(s->pw->pw_uid == 0,
379 &options.fwd_opts) < 0) {
380 debug("Port forwarding failed.");
381 break;
382 }
383 success = 1;
384 break;
385
386 case SSH_CMSG_MAX_PACKET_SIZE:
387 if (packet_set_maxsize(packet_get_int()) > 0)
388 success = 1;
389 break;
390
391 case SSH_CMSG_EXEC_SHELL:
392 case SSH_CMSG_EXEC_CMD:
393 if (type == SSH_CMSG_EXEC_CMD) {
394 command = packet_get_string(&dlen);
395 debug("Exec command '%.500s'", command);
396 if (do_exec(s, command) != 0)
397 packet_disconnect(
398 "command execution failed");
399 free(command);
400 } else {
401 if (do_exec(s, NULL) != 0)
402 packet_disconnect(
403 "shell execution failed");
404 }
405 packet_check_eom();
406 session_close(s);
407 return;
408
409 default:
410 /*
411 * Any unknown messages in this phase are ignored,
412 * and a failure message is returned.
413 */
414 logit("Unknown packet type received after authentication: %d", type);
415 }
416 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
417 packet_send();
418 packet_write_wait();
419
420 /* Enable compression now that we have replied if appropriate. */
421 if (enable_compression_after_reply) {
422 enable_compression_after_reply = 0;
423 packet_start_compression(compression_level);
424 }
425 }
426 }
427
428 #define USE_PIPES 1
429 /*
430 * This is called to fork and execute a command when we have no tty. This
431 * will call do_child from the child, and server_loop from the parent after
432 * setting up file descriptors and such.
433 */
434 int
do_exec_no_pty(Session * s,const char * command)435 do_exec_no_pty(Session *s, const char *command)
436 {
437 pid_t pid;
438
439 #ifdef USE_PIPES
440 int pin[2], pout[2], perr[2];
441
442 if (s == NULL)
443 fatal("do_exec_no_pty: no session");
444
445 /* Allocate pipes for communicating with the program. */
446 if (pipe(pin) < 0) {
447 error("%s: pipe in: %.100s", __func__, strerror(errno));
448 return -1;
449 }
450 if (pipe(pout) < 0) {
451 error("%s: pipe out: %.100s", __func__, strerror(errno));
452 close(pin[0]);
453 close(pin[1]);
454 return -1;
455 }
456 if (pipe(perr) < 0) {
457 error("%s: pipe err: %.100s", __func__,
458 strerror(errno));
459 close(pin[0]);
460 close(pin[1]);
461 close(pout[0]);
462 close(pout[1]);
463 return -1;
464 }
465 #else
466 int inout[2], err[2];
467
468 if (s == NULL)
469 fatal("do_exec_no_pty: no session");
470
471 /* Uses socket pairs to communicate with the program. */
472 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) {
473 error("%s: socketpair #1: %.100s", __func__, strerror(errno));
474 return -1;
475 }
476 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) {
477 error("%s: socketpair #2: %.100s", __func__,
478 strerror(errno));
479 close(inout[0]);
480 close(inout[1]);
481 return -1;
482 }
483 #endif
484
485 session_proctitle(s);
486
487 /* Fork the child. */
488 switch ((pid = fork())) {
489 case -1:
490 error("%s: fork: %.100s", __func__, strerror(errno));
491 #ifdef USE_PIPES
492 close(pin[0]);
493 close(pin[1]);
494 close(pout[0]);
495 close(pout[1]);
496 close(perr[0]);
497 close(perr[1]);
498 #else
499 close(inout[0]);
500 close(inout[1]);
501 close(err[0]);
502 close(err[1]);
503 #endif
504 return -1;
505 case 0:
506 is_child = 1;
507
508 /* Child. Reinitialize the log since the pid has changed. */
509 log_init(__progname, options.log_level,
510 options.log_facility, log_stderr);
511
512 /*
513 * Create a new session and process group since the 4.4BSD
514 * setlogin() affects the entire process group.
515 */
516 if (setsid() < 0)
517 error("setsid failed: %.100s", strerror(errno));
518
519 #ifdef USE_PIPES
520 /*
521 * Redirect stdin. We close the parent side of the socket
522 * pair, and make the child side the standard input.
523 */
524 close(pin[1]);
525 if (dup2(pin[0], 0) < 0)
526 perror("dup2 stdin");
527 close(pin[0]);
528
529 /* Redirect stdout. */
530 close(pout[0]);
531 if (dup2(pout[1], 1) < 0)
532 perror("dup2 stdout");
533 close(pout[1]);
534
535 /* Redirect stderr. */
536 close(perr[0]);
537 if (dup2(perr[1], 2) < 0)
538 perror("dup2 stderr");
539 close(perr[1]);
540 #else
541 /*
542 * Redirect stdin, stdout, and stderr. Stdin and stdout will
543 * use the same socket, as some programs (particularly rdist)
544 * seem to depend on it.
545 */
546 close(inout[1]);
547 close(err[1]);
548 if (dup2(inout[0], 0) < 0) /* stdin */
549 perror("dup2 stdin");
550 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */
551 perror("dup2 stdout");
552 close(inout[0]);
553 if (dup2(err[0], 2) < 0) /* stderr */
554 perror("dup2 stderr");
555 close(err[0]);
556 #endif
557
558
559 #ifdef _UNICOS
560 cray_init_job(s->pw); /* set up cray jid and tmpdir */
561 #endif
562
563 /* Do processing for the child (exec command etc). */
564 do_child(s, command);
565 /* NOTREACHED */
566 default:
567 break;
568 }
569
570 #ifdef _UNICOS
571 signal(WJSIGNAL, cray_job_termination_handler);
572 #endif /* _UNICOS */
573 #ifdef HAVE_CYGWIN
574 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
575 #endif
576
577 s->pid = pid;
578 /* Set interactive/non-interactive mode. */
579 packet_set_interactive(s->display != NULL,
580 options.ip_qos_interactive, options.ip_qos_bulk);
581
582 /*
583 * Clear loginmsg, since it's the child's responsibility to display
584 * it to the user, otherwise multiple sessions may accumulate
585 * multiple copies of the login messages.
586 */
587 buffer_clear(&loginmsg);
588
589 #ifdef USE_PIPES
590 /* We are the parent. Close the child sides of the pipes. */
591 close(pin[0]);
592 close(pout[1]);
593 close(perr[1]);
594
595 if (compat20) {
596 session_set_fds(s, pin[1], pout[0], perr[0],
597 s->is_subsystem, 0);
598 } else {
599 /* Enter the interactive session. */
600 server_loop(pid, pin[1], pout[0], perr[0]);
601 /* server_loop has closed pin[1], pout[0], and perr[0]. */
602 }
603 #else
604 /* We are the parent. Close the child sides of the socket pairs. */
605 close(inout[0]);
606 close(err[0]);
607
608 /*
609 * Enter the interactive session. Note: server_loop must be able to
610 * handle the case that fdin and fdout are the same.
611 */
612 if (compat20) {
613 session_set_fds(s, inout[1], inout[1], err[1],
614 s->is_subsystem, 0);
615 } else {
616 server_loop(pid, inout[1], inout[1], err[1]);
617 /* server_loop has closed inout[1] and err[1]. */
618 }
619 #endif
620 return 0;
621 }
622
623 /*
624 * This is called to fork and execute a command when we have a tty. This
625 * will call do_child from the child, and server_loop from the parent after
626 * setting up file descriptors, controlling tty, updating wtmp, utmp,
627 * lastlog, and other such operations.
628 */
629 int
do_exec_pty(Session * s,const char * command)630 do_exec_pty(Session *s, const char *command)
631 {
632 int fdout, ptyfd, ttyfd, ptymaster;
633 pid_t pid;
634
635 if (s == NULL)
636 fatal("do_exec_pty: no session");
637 ptyfd = s->ptyfd;
638 ttyfd = s->ttyfd;
639
640 /*
641 * Create another descriptor of the pty master side for use as the
642 * standard input. We could use the original descriptor, but this
643 * simplifies code in server_loop. The descriptor is bidirectional.
644 * Do this before forking (and cleanup in the child) so as to
645 * detect and gracefully fail out-of-fd conditions.
646 */
647 if ((fdout = dup(ptyfd)) < 0) {
648 error("%s: dup #1: %s", __func__, strerror(errno));
649 close(ttyfd);
650 close(ptyfd);
651 return -1;
652 }
653 /* we keep a reference to the pty master */
654 if ((ptymaster = dup(ptyfd)) < 0) {
655 error("%s: dup #2: %s", __func__, strerror(errno));
656 close(ttyfd);
657 close(ptyfd);
658 close(fdout);
659 return -1;
660 }
661
662 /* Fork the child. */
663 switch ((pid = fork())) {
664 case -1:
665 error("%s: fork: %.100s", __func__, strerror(errno));
666 close(fdout);
667 close(ptymaster);
668 close(ttyfd);
669 close(ptyfd);
670 return -1;
671 case 0:
672 is_child = 1;
673
674 close(fdout);
675 close(ptymaster);
676
677 /* Child. Reinitialize the log because the pid has changed. */
678 log_init(__progname, options.log_level,
679 options.log_facility, log_stderr);
680 /* Close the master side of the pseudo tty. */
681 close(ptyfd);
682
683 /* Make the pseudo tty our controlling tty. */
684 pty_make_controlling_tty(&ttyfd, s->tty);
685
686 /* Redirect stdin/stdout/stderr from the pseudo tty. */
687 if (dup2(ttyfd, 0) < 0)
688 error("dup2 stdin: %s", strerror(errno));
689 if (dup2(ttyfd, 1) < 0)
690 error("dup2 stdout: %s", strerror(errno));
691 if (dup2(ttyfd, 2) < 0)
692 error("dup2 stderr: %s", strerror(errno));
693
694 /* Close the extra descriptor for the pseudo tty. */
695 close(ttyfd);
696
697 /* record login, etc. similar to login(1) */
698 #ifndef HAVE_OSF_SIA
699 if (!(options.use_login && command == NULL)) {
700 #ifdef _UNICOS
701 cray_init_job(s->pw); /* set up cray jid and tmpdir */
702 #endif /* _UNICOS */
703 do_login(s, command);
704 }
705 # ifdef LOGIN_NEEDS_UTMPX
706 else
707 do_pre_login(s);
708 # endif
709 #endif
710 /*
711 * Do common processing for the child, such as execing
712 * the command.
713 */
714 do_child(s, command);
715 /* NOTREACHED */
716 default:
717 break;
718 }
719
720 #ifdef _UNICOS
721 signal(WJSIGNAL, cray_job_termination_handler);
722 #endif /* _UNICOS */
723 #ifdef HAVE_CYGWIN
724 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
725 #endif
726
727 s->pid = pid;
728
729 /* Parent. Close the slave side of the pseudo tty. */
730 close(ttyfd);
731
732 /* Enter interactive session. */
733 s->ptymaster = ptymaster;
734 packet_set_interactive(1,
735 options.ip_qos_interactive, options.ip_qos_bulk);
736 if (compat20) {
737 session_set_fds(s, ptyfd, fdout, -1, 1, 1);
738 } else {
739 server_loop(pid, ptyfd, fdout, -1);
740 /* server_loop _has_ closed ptyfd and fdout. */
741 }
742 return 0;
743 }
744
745 #ifdef LOGIN_NEEDS_UTMPX
746 static void
do_pre_login(Session * s)747 do_pre_login(Session *s)
748 {
749 socklen_t fromlen;
750 struct sockaddr_storage from;
751 pid_t pid = getpid();
752
753 /*
754 * Get IP address of client. If the connection is not a socket, let
755 * the address be 0.0.0.0.
756 */
757 memset(&from, 0, sizeof(from));
758 fromlen = sizeof(from);
759 if (packet_connection_is_on_socket()) {
760 if (getpeername(packet_get_connection_in(),
761 (struct sockaddr *)&from, &fromlen) < 0) {
762 debug("getpeername: %.100s", strerror(errno));
763 cleanup_exit(255);
764 }
765 }
766
767 record_utmp_only(pid, s->tty, s->pw->pw_name,
768 get_remote_name_or_ip(utmp_len, options.use_dns),
769 (struct sockaddr *)&from, fromlen);
770 }
771 #endif
772
773 /*
774 * This is called to fork and execute a command. If another command is
775 * to be forced, execute that instead.
776 */
777 int
do_exec(Session * s,const char * command)778 do_exec(Session *s, const char *command)
779 {
780 int ret;
781 const char *forced = NULL;
782 char session_type[1024], *tty = NULL;
783
784 if (options.adm_forced_command) {
785 original_command = command;
786 command = options.adm_forced_command;
787 forced = "(config)";
788 } else if (forced_command) {
789 original_command = command;
790 command = forced_command;
791 forced = "(key-option)";
792 }
793 if (forced != NULL) {
794 if (IS_INTERNAL_SFTP(command)) {
795 s->is_subsystem = s->is_subsystem ?
796 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR;
797 } else if (s->is_subsystem)
798 s->is_subsystem = SUBSYSTEM_EXT;
799 snprintf(session_type, sizeof(session_type),
800 "forced-command %s '%.900s'", forced, command);
801 } else if (s->is_subsystem) {
802 snprintf(session_type, sizeof(session_type),
803 "subsystem '%.900s'", s->subsys);
804 } else if (command == NULL) {
805 snprintf(session_type, sizeof(session_type), "shell");
806 } else {
807 /* NB. we don't log unforced commands to preserve privacy */
808 snprintf(session_type, sizeof(session_type), "command");
809 }
810
811 if (s->ttyfd != -1) {
812 tty = s->tty;
813 if (strncmp(tty, "/dev/", 5) == 0)
814 tty += 5;
815 }
816
817 verbose("Starting session: %s%s%s for %s from %.200s port %d",
818 session_type,
819 tty == NULL ? "" : " on ",
820 tty == NULL ? "" : tty,
821 s->pw->pw_name,
822 get_remote_ipaddr(),
823 get_remote_port());
824
825 #ifdef SSH_AUDIT_EVENTS
826 if (command != NULL)
827 PRIVSEP(audit_run_command(command));
828 else if (s->ttyfd == -1) {
829 char *shell = s->pw->pw_shell;
830
831 if (shell[0] == '\0') /* empty shell means /bin/sh */
832 shell =_PATH_BSHELL;
833 PRIVSEP(audit_run_command(shell));
834 }
835 #endif
836 if (s->ttyfd != -1)
837 ret = do_exec_pty(s, command);
838 else
839 ret = do_exec_no_pty(s, command);
840
841 original_command = NULL;
842
843 /*
844 * Clear loginmsg: it's the child's responsibility to display
845 * it to the user, otherwise multiple sessions may accumulate
846 * multiple copies of the login messages.
847 */
848 buffer_clear(&loginmsg);
849
850 return ret;
851 }
852
853 /* administrative, login(1)-like work */
854 void
do_login(Session * s,const char * command)855 do_login(Session *s, const char *command)
856 {
857 socklen_t fromlen;
858 struct sockaddr_storage from;
859 struct passwd * pw = s->pw;
860 pid_t pid = getpid();
861
862 /*
863 * Get IP address of client. If the connection is not a socket, let
864 * the address be 0.0.0.0.
865 */
866 memset(&from, 0, sizeof(from));
867 fromlen = sizeof(from);
868 if (packet_connection_is_on_socket()) {
869 if (getpeername(packet_get_connection_in(),
870 (struct sockaddr *)&from, &fromlen) < 0) {
871 debug("getpeername: %.100s", strerror(errno));
872 cleanup_exit(255);
873 }
874 }
875
876 /* Record that there was a login on that tty from the remote host. */
877 if (!use_privsep)
878 record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
879 get_remote_name_or_ip(utmp_len,
880 options.use_dns),
881 (struct sockaddr *)&from, fromlen);
882
883 #ifdef USE_PAM
884 /*
885 * If password change is needed, do it now.
886 * This needs to occur before the ~/.hushlogin check.
887 */
888 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) {
889 display_loginmsg();
890 do_pam_chauthtok();
891 s->authctxt->force_pwchange = 0;
892 /* XXX - signal [net] parent to enable forwardings */
893 }
894 #endif
895
896 if (check_quietlogin(s, command))
897 return;
898
899 display_loginmsg();
900
901 do_motd();
902 }
903
904 /*
905 * Display the message of the day.
906 */
907 void
do_motd(void)908 do_motd(void)
909 {
910 FILE *f;
911 char buf[256];
912
913 if (options.print_motd) {
914 #ifdef HAVE_LOGIN_CAP
915 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd",
916 "/etc/motd"), "r");
917 #else
918 f = fopen("/etc/motd", "r");
919 #endif
920 if (f) {
921 while (fgets(buf, sizeof(buf), f))
922 fputs(buf, stdout);
923 fclose(f);
924 }
925 }
926 }
927
928
929 /*
930 * Check for quiet login, either .hushlogin or command given.
931 */
932 int
check_quietlogin(Session * s,const char * command)933 check_quietlogin(Session *s, const char *command)
934 {
935 char buf[256];
936 struct passwd *pw = s->pw;
937 struct stat st;
938
939 /* Return 1 if .hushlogin exists or a command given. */
940 if (command != NULL)
941 return 1;
942 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
943 #ifdef HAVE_LOGIN_CAP
944 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
945 return 1;
946 #else
947 if (stat(buf, &st) >= 0)
948 return 1;
949 #endif
950 return 0;
951 }
952
953 /*
954 * Sets the value of the given variable in the environment. If the variable
955 * already exists, its value is overridden.
956 */
957 void
child_set_env(char *** envp,u_int * envsizep,const char * name,const char * value)958 child_set_env(char ***envp, u_int *envsizep, const char *name,
959 const char *value)
960 {
961 char **env;
962 u_int envsize;
963 u_int i, namelen;
964
965 if (strchr(name, '=') != NULL) {
966 error("Invalid environment variable \"%.100s\"", name);
967 return;
968 }
969
970 /*
971 * If we're passed an uninitialized list, allocate a single null
972 * entry before continuing.
973 */
974 if (*envp == NULL && *envsizep == 0) {
975 *envp = xmalloc(sizeof(char *));
976 *envp[0] = NULL;
977 *envsizep = 1;
978 }
979
980 /*
981 * Find the slot where the value should be stored. If the variable
982 * already exists, we reuse the slot; otherwise we append a new slot
983 * at the end of the array, expanding if necessary.
984 */
985 env = *envp;
986 namelen = strlen(name);
987 for (i = 0; env[i]; i++)
988 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
989 break;
990 if (env[i]) {
991 /* Reuse the slot. */
992 free(env[i]);
993 } else {
994 /* New variable. Expand if necessary. */
995 envsize = *envsizep;
996 if (i >= envsize - 1) {
997 if (envsize >= 1000)
998 fatal("child_set_env: too many env vars");
999 envsize += 50;
1000 env = (*envp) = xrealloc(env, envsize, sizeof(char *));
1001 *envsizep = envsize;
1002 }
1003 /* Need to set the NULL pointer at end of array beyond the new slot. */
1004 env[i + 1] = NULL;
1005 }
1006
1007 /* Allocate space and format the variable in the appropriate slot. */
1008 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
1009 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
1010 }
1011
1012 /*
1013 * Reads environment variables from the given file and adds/overrides them
1014 * into the environment. If the file does not exist, this does nothing.
1015 * Otherwise, it must consist of empty lines, comments (line starts with '#')
1016 * and assignments of the form name=value. No other forms are allowed.
1017 */
1018 static void
read_environment_file(char *** env,u_int * envsize,const char * filename)1019 read_environment_file(char ***env, u_int *envsize,
1020 const char *filename)
1021 {
1022 FILE *f;
1023 char buf[4096];
1024 char *cp, *value;
1025 u_int lineno = 0;
1026
1027 f = fopen(filename, "r");
1028 if (!f)
1029 return;
1030
1031 while (fgets(buf, sizeof(buf), f)) {
1032 if (++lineno > 1000)
1033 fatal("Too many lines in environment file %s", filename);
1034 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
1035 ;
1036 if (!*cp || *cp == '#' || *cp == '\n')
1037 continue;
1038
1039 cp[strcspn(cp, "\n")] = '\0';
1040
1041 value = strchr(cp, '=');
1042 if (value == NULL) {
1043 fprintf(stderr, "Bad line %u in %.100s\n", lineno,
1044 filename);
1045 continue;
1046 }
1047 /*
1048 * Replace the equals sign by nul, and advance value to
1049 * the value string.
1050 */
1051 *value = '\0';
1052 value++;
1053 child_set_env(env, envsize, cp, value);
1054 }
1055 fclose(f);
1056 }
1057
1058 #ifdef HAVE_ETC_DEFAULT_LOGIN
1059 /*
1060 * Return named variable from specified environment, or NULL if not present.
1061 */
1062 static char *
child_get_env(char ** env,const char * name)1063 child_get_env(char **env, const char *name)
1064 {
1065 int i;
1066 size_t len;
1067
1068 len = strlen(name);
1069 for (i=0; env[i] != NULL; i++)
1070 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=')
1071 return(env[i] + len + 1);
1072 return NULL;
1073 }
1074
1075 /*
1076 * Read /etc/default/login.
1077 * We pick up the PATH (or SUPATH for root) and UMASK.
1078 */
1079 static void
read_etc_default_login(char *** env,u_int * envsize,uid_t uid)1080 read_etc_default_login(char ***env, u_int *envsize, uid_t uid)
1081 {
1082 char **tmpenv = NULL, *var;
1083 u_int i, tmpenvsize = 0;
1084 u_long mask;
1085
1086 /*
1087 * We don't want to copy the whole file to the child's environment,
1088 * so we use a temporary environment and copy the variables we're
1089 * interested in.
1090 */
1091 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login");
1092
1093 if (tmpenv == NULL)
1094 return;
1095
1096 if (uid == 0)
1097 var = child_get_env(tmpenv, "SUPATH");
1098 else
1099 var = child_get_env(tmpenv, "PATH");
1100 if (var != NULL)
1101 child_set_env(env, envsize, "PATH", var);
1102
1103 if ((var = child_get_env(tmpenv, "UMASK")) != NULL)
1104 if (sscanf(var, "%5lo", &mask) == 1)
1105 umask((mode_t)mask);
1106
1107 for (i = 0; tmpenv[i] != NULL; i++)
1108 free(tmpenv[i]);
1109 free(tmpenv);
1110 }
1111 #endif /* HAVE_ETC_DEFAULT_LOGIN */
1112
1113 void
copy_environment(char ** source,char *** env,u_int * envsize)1114 copy_environment(char **source, char ***env, u_int *envsize)
1115 {
1116 char *var_name, *var_val;
1117 int i;
1118
1119 if (source == NULL)
1120 return;
1121
1122 for(i = 0; source[i] != NULL; i++) {
1123 var_name = xstrdup(source[i]);
1124 if ((var_val = strstr(var_name, "=")) == NULL) {
1125 free(var_name);
1126 continue;
1127 }
1128 *var_val++ = '\0';
1129
1130 debug3("Copy environment: %s=%s", var_name, var_val);
1131 child_set_env(env, envsize, var_name, var_val);
1132
1133 free(var_name);
1134 }
1135 }
1136
1137 static char **
do_setup_env(Session * s,const char * shell)1138 do_setup_env(Session *s, const char *shell)
1139 {
1140 char buf[256];
1141 u_int i, envsize;
1142 char **env, *laddr;
1143 struct passwd *pw = s->pw;
1144 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN)
1145 char *path = NULL;
1146 #endif
1147
1148 /* Initialize the environment. */
1149 envsize = 100;
1150 env = xcalloc(envsize, sizeof(char *));
1151 env[0] = NULL;
1152
1153 #ifdef HAVE_CYGWIN
1154 /*
1155 * The Windows environment contains some setting which are
1156 * important for a running system. They must not be dropped.
1157 */
1158 {
1159 char **p;
1160
1161 p = fetch_windows_environment();
1162 copy_environment(p, &env, &envsize);
1163 free_windows_environment(p);
1164 }
1165 #endif
1166
1167 #ifdef GSSAPI
1168 /* Allow any GSSAPI methods that we've used to alter
1169 * the childs environment as they see fit
1170 */
1171 ssh_gssapi_do_child(&env, &envsize);
1172 #endif
1173
1174 if (!options.use_login) {
1175 /* Set basic environment. */
1176 for (i = 0; i < s->num_env; i++)
1177 child_set_env(&env, &envsize, s->env[i].name,
1178 s->env[i].val);
1179
1180 child_set_env(&env, &envsize, "USER", pw->pw_name);
1181 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
1182 #ifdef _AIX
1183 child_set_env(&env, &envsize, "LOGIN", pw->pw_name);
1184 #endif
1185 child_set_env(&env, &envsize, "HOME", pw->pw_dir);
1186 #ifdef HAVE_LOGIN_CAP
1187 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0)
1188 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
1189 else
1190 child_set_env(&env, &envsize, "PATH", getenv("PATH"));
1191 #else /* HAVE_LOGIN_CAP */
1192 # ifndef HAVE_CYGWIN
1193 /*
1194 * There's no standard path on Windows. The path contains
1195 * important components pointing to the system directories,
1196 * needed for loading shared libraries. So the path better
1197 * remains intact here.
1198 */
1199 # ifdef HAVE_ETC_DEFAULT_LOGIN
1200 read_etc_default_login(&env, &envsize, pw->pw_uid);
1201 path = child_get_env(env, "PATH");
1202 # endif /* HAVE_ETC_DEFAULT_LOGIN */
1203 if (path == NULL || *path == '\0') {
1204 child_set_env(&env, &envsize, "PATH",
1205 s->pw->pw_uid == 0 ?
1206 SUPERUSER_PATH : _PATH_STDPATH);
1207 }
1208 # endif /* HAVE_CYGWIN */
1209 #endif /* HAVE_LOGIN_CAP */
1210
1211 #ifndef ANDROID
1212 snprintf(buf, sizeof buf, "%.200s/%.50s",
1213 _PATH_MAILDIR, pw->pw_name);
1214 child_set_env(&env, &envsize, "MAIL", buf);
1215 #endif
1216
1217 /* Normal systems set SHELL by default. */
1218 child_set_env(&env, &envsize, "SHELL", shell);
1219 }
1220 if (getenv("TZ"))
1221 child_set_env(&env, &envsize, "TZ", getenv("TZ"));
1222
1223 /* Set custom environment options from RSA authentication. */
1224 if (!options.use_login) {
1225 while (custom_environment) {
1226 struct envstring *ce = custom_environment;
1227 char *str = ce->s;
1228
1229 for (i = 0; str[i] != '=' && str[i]; i++)
1230 ;
1231 if (str[i] == '=') {
1232 str[i] = 0;
1233 child_set_env(&env, &envsize, str, str + i + 1);
1234 }
1235 custom_environment = ce->next;
1236 free(ce->s);
1237 free(ce);
1238 }
1239 }
1240
1241 /* SSH_CLIENT deprecated */
1242 snprintf(buf, sizeof buf, "%.50s %d %d",
1243 get_remote_ipaddr(), get_remote_port(), get_local_port());
1244 child_set_env(&env, &envsize, "SSH_CLIENT", buf);
1245
1246 laddr = get_local_ipaddr(packet_get_connection_in());
1247 snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
1248 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port());
1249 free(laddr);
1250 child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
1251
1252 if (s->ttyfd != -1)
1253 child_set_env(&env, &envsize, "SSH_TTY", s->tty);
1254 if (s->term)
1255 child_set_env(&env, &envsize, "TERM", s->term);
1256 if (s->display)
1257 child_set_env(&env, &envsize, "DISPLAY", s->display);
1258 if (original_command)
1259 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
1260 original_command);
1261
1262 #ifdef _UNICOS
1263 if (cray_tmpdir[0] != '\0')
1264 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir);
1265 #endif /* _UNICOS */
1266
1267 /*
1268 * Since we clear KRB5CCNAME at startup, if it's set now then it
1269 * must have been set by a native authentication method (eg AIX or
1270 * SIA), so copy it to the child.
1271 */
1272 {
1273 char *cp;
1274
1275 if ((cp = getenv("KRB5CCNAME")) != NULL)
1276 child_set_env(&env, &envsize, "KRB5CCNAME", cp);
1277 }
1278
1279 #ifdef _AIX
1280 {
1281 char *cp;
1282
1283 if ((cp = getenv("AUTHSTATE")) != NULL)
1284 child_set_env(&env, &envsize, "AUTHSTATE", cp);
1285 read_environment_file(&env, &envsize, "/etc/environment");
1286 }
1287 #endif
1288 #ifdef KRB5
1289 if (s->authctxt->krb5_ccname)
1290 child_set_env(&env, &envsize, "KRB5CCNAME",
1291 s->authctxt->krb5_ccname);
1292 #endif
1293 #ifdef USE_PAM
1294 /*
1295 * Pull in any environment variables that may have
1296 * been set by PAM.
1297 */
1298 if (options.use_pam) {
1299 char **p;
1300
1301 p = fetch_pam_child_environment();
1302 copy_environment(p, &env, &envsize);
1303 free_pam_environment(p);
1304
1305 p = fetch_pam_environment();
1306 copy_environment(p, &env, &envsize);
1307 free_pam_environment(p);
1308 }
1309 #endif /* USE_PAM */
1310
1311 if (auth_sock_name != NULL)
1312 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
1313 auth_sock_name);
1314
1315 /* read $HOME/.ssh/environment. */
1316 if (options.permit_user_env && !options.use_login) {
1317 snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
1318 strcmp(pw->pw_dir, "/") ? pw->pw_dir : "");
1319 read_environment_file(&env, &envsize, buf);
1320 }
1321 if (debug_flag) {
1322 /* dump the environment */
1323 fprintf(stderr, "Environment:\n");
1324 for (i = 0; env[i]; i++)
1325 fprintf(stderr, " %.200s\n", env[i]);
1326 }
1327 return env;
1328 }
1329
1330 /*
1331 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found
1332 * first in this order).
1333 */
1334 static void
do_rc_files(Session * s,const char * shell)1335 do_rc_files(Session *s, const char *shell)
1336 {
1337 FILE *f = NULL;
1338 char cmd[1024];
1339 int do_xauth;
1340 struct stat st;
1341
1342 do_xauth =
1343 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
1344
1345 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */
1346 if (!s->is_subsystem && options.adm_forced_command == NULL &&
1347 !no_user_rc && options.permit_user_rc &&
1348 stat(_PATH_SSH_USER_RC, &st) >= 0) {
1349 snprintf(cmd, sizeof cmd, "%s -c '%s %s'",
1350 shell, _PATH_BSHELL, _PATH_SSH_USER_RC);
1351 if (debug_flag)
1352 fprintf(stderr, "Running %s\n", cmd);
1353 f = popen(cmd, "w");
1354 if (f) {
1355 if (do_xauth)
1356 fprintf(f, "%s %s\n", s->auth_proto,
1357 s->auth_data);
1358 pclose(f);
1359 } else
1360 fprintf(stderr, "Could not run %s\n",
1361 _PATH_SSH_USER_RC);
1362 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) {
1363 if (debug_flag)
1364 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
1365 _PATH_SSH_SYSTEM_RC);
1366 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w");
1367 if (f) {
1368 if (do_xauth)
1369 fprintf(f, "%s %s\n", s->auth_proto,
1370 s->auth_data);
1371 pclose(f);
1372 } else
1373 fprintf(stderr, "Could not run %s\n",
1374 _PATH_SSH_SYSTEM_RC);
1375 } else if (do_xauth && options.xauth_location != NULL) {
1376 /* Add authority data to .Xauthority if appropriate. */
1377 if (debug_flag) {
1378 fprintf(stderr,
1379 "Running %.500s remove %.100s\n",
1380 options.xauth_location, s->auth_display);
1381 fprintf(stderr,
1382 "%.500s add %.100s %.100s %.100s\n",
1383 options.xauth_location, s->auth_display,
1384 s->auth_proto, s->auth_data);
1385 }
1386 snprintf(cmd, sizeof cmd, "%s -q -",
1387 options.xauth_location);
1388 f = popen(cmd, "w");
1389 if (f) {
1390 fprintf(f, "remove %s\n",
1391 s->auth_display);
1392 fprintf(f, "add %s %s %s\n",
1393 s->auth_display, s->auth_proto,
1394 s->auth_data);
1395 pclose(f);
1396 } else {
1397 fprintf(stderr, "Could not run %s\n",
1398 cmd);
1399 }
1400 }
1401 }
1402
1403 static void
do_nologin(struct passwd * pw)1404 do_nologin(struct passwd *pw)
1405 {
1406 FILE *f = NULL;
1407 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN;
1408 struct stat sb;
1409
1410 #ifdef HAVE_LOGIN_CAP
1411 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0)
1412 return;
1413 nl = login_getcapstr(lc, "nologin", def_nl, def_nl);
1414 #else
1415 if (pw->pw_uid == 0)
1416 return;
1417 nl = def_nl;
1418 #endif
1419 if (stat(nl, &sb) == -1) {
1420 if (nl != def_nl)
1421 free(nl);
1422 return;
1423 }
1424
1425 /* /etc/nologin exists. Print its contents if we can and exit. */
1426 logit("User %.100s not allowed because %s exists", pw->pw_name, nl);
1427 if ((f = fopen(nl, "r")) != NULL) {
1428 while (fgets(buf, sizeof(buf), f))
1429 fputs(buf, stderr);
1430 fclose(f);
1431 }
1432 exit(254);
1433 }
1434
1435 /*
1436 * Chroot into a directory after checking it for safety: all path components
1437 * must be root-owned directories with strict permissions.
1438 */
1439 static void
safely_chroot(const char * path,uid_t uid)1440 safely_chroot(const char *path, uid_t uid)
1441 {
1442 const char *cp;
1443 char component[PATH_MAX];
1444 struct stat st;
1445
1446 if (*path != '/')
1447 fatal("chroot path does not begin at root");
1448 if (strlen(path) >= sizeof(component))
1449 fatal("chroot path too long");
1450
1451 /*
1452 * Descend the path, checking that each component is a
1453 * root-owned directory with strict permissions.
1454 */
1455 for (cp = path; cp != NULL;) {
1456 if ((cp = strchr(cp, '/')) == NULL)
1457 strlcpy(component, path, sizeof(component));
1458 else {
1459 cp++;
1460 memcpy(component, path, cp - path);
1461 component[cp - path] = '\0';
1462 }
1463
1464 debug3("%s: checking '%s'", __func__, component);
1465
1466 if (stat(component, &st) != 0)
1467 fatal("%s: stat(\"%s\"): %s", __func__,
1468 component, strerror(errno));
1469 if (st.st_uid != 0 || (st.st_mode & 022) != 0)
1470 fatal("bad ownership or modes for chroot "
1471 "directory %s\"%s\"",
1472 cp == NULL ? "" : "component ", component);
1473 if (!S_ISDIR(st.st_mode))
1474 fatal("chroot path %s\"%s\" is not a directory",
1475 cp == NULL ? "" : "component ", component);
1476
1477 }
1478
1479 if (chdir(path) == -1)
1480 fatal("Unable to chdir to chroot path \"%s\": "
1481 "%s", path, strerror(errno));
1482 if (chroot(path) == -1)
1483 fatal("chroot(\"%s\"): %s", path, strerror(errno));
1484 if (chdir("/") == -1)
1485 fatal("%s: chdir(/) after chroot: %s",
1486 __func__, strerror(errno));
1487 verbose("Changed root directory to \"%s\"", path);
1488 }
1489
1490 /* Set login name, uid, gid, and groups. */
1491 void
do_setusercontext(struct passwd * pw)1492 do_setusercontext(struct passwd *pw)
1493 {
1494 char *chroot_path, *tmp;
1495 #ifdef USE_LIBIAF
1496 int doing_chroot = 0;
1497 #endif
1498
1499 platform_setusercontext(pw);
1500
1501 if (platform_privileged_uidswap()) {
1502 #ifdef HAVE_LOGIN_CAP
1503 if (setusercontext(lc, pw, pw->pw_uid,
1504 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) {
1505 perror("unable to set user context");
1506 exit(1);
1507 }
1508 #else
1509 if (setlogin(pw->pw_name) < 0)
1510 error("setlogin failed: %s", strerror(errno));
1511 if (setgid(pw->pw_gid) < 0) {
1512 perror("setgid");
1513 exit(1);
1514 }
1515 /* Initialize the group list. */
1516 if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
1517 perror("initgroups");
1518 exit(1);
1519 }
1520 #if !defined(ANDROID)
1521 endgrent();
1522 #endif
1523 #endif
1524
1525 platform_setusercontext_post_groups(pw);
1526
1527 if (options.chroot_directory != NULL &&
1528 strcasecmp(options.chroot_directory, "none") != 0) {
1529 tmp = tilde_expand_filename(options.chroot_directory,
1530 pw->pw_uid);
1531 chroot_path = percent_expand(tmp, "h", pw->pw_dir,
1532 "u", pw->pw_name, (char *)NULL);
1533 safely_chroot(chroot_path, pw->pw_uid);
1534 free(tmp);
1535 free(chroot_path);
1536 /* Make sure we don't attempt to chroot again */
1537 free(options.chroot_directory);
1538 options.chroot_directory = NULL;
1539 #ifdef USE_LIBIAF
1540 doing_chroot = 1;
1541 #endif
1542 }
1543
1544 #ifdef HAVE_LOGIN_CAP
1545 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) {
1546 perror("unable to set user context (setuser)");
1547 exit(1);
1548 }
1549 /*
1550 * FreeBSD's setusercontext() will not apply the user's
1551 * own umask setting unless running with the user's UID.
1552 */
1553 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK);
1554 #else
1555 # ifdef USE_LIBIAF
1556 /* In a chroot environment, the set_id() will always fail; typically
1557 * because of the lack of necessary authentication services and runtime
1558 * such as ./usr/lib/libiaf.so, ./usr/lib/libpam.so.1, and ./etc/passwd
1559 * We skip it in the internal sftp chroot case.
1560 * We'll lose auditing and ACLs but permanently_set_uid will
1561 * take care of the rest.
1562 */
1563 if ((doing_chroot == 0) && set_id(pw->pw_name) != 0) {
1564 fatal("set_id(%s) Failed", pw->pw_name);
1565 }
1566 # endif /* USE_LIBIAF */
1567 /* Permanently switch to the desired uid. */
1568 permanently_set_uid(pw);
1569 #endif
1570 } else if (options.chroot_directory != NULL &&
1571 strcasecmp(options.chroot_directory, "none") != 0) {
1572 fatal("server lacks privileges to chroot to ChrootDirectory");
1573 }
1574
1575 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
1576 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
1577 }
1578
1579 static void
do_pwchange(Session * s)1580 do_pwchange(Session *s)
1581 {
1582 fflush(NULL);
1583 fprintf(stderr, "WARNING: Your password has expired.\n");
1584 if (s->ttyfd != -1) {
1585 fprintf(stderr,
1586 "You must change your password now and login again!\n");
1587 #ifdef WITH_SELINUX
1588 setexeccon(NULL);
1589 #endif
1590 #ifdef PASSWD_NEEDS_USERNAME
1591 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name,
1592 (char *)NULL);
1593 #else
1594 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL);
1595 #endif
1596 perror("passwd");
1597 } else {
1598 fprintf(stderr,
1599 "Password change required but no TTY available.\n");
1600 }
1601 exit(1);
1602 }
1603
1604 static void
launch_login(struct passwd * pw,const char * hostname)1605 launch_login(struct passwd *pw, const char *hostname)
1606 {
1607 /* Launch login(1). */
1608
1609 execl(LOGIN_PROGRAM, "login", "-h", hostname,
1610 #ifdef xxxLOGIN_NEEDS_TERM
1611 (s->term ? s->term : "unknown"),
1612 #endif /* LOGIN_NEEDS_TERM */
1613 #ifdef LOGIN_NO_ENDOPT
1614 "-p", "-f", pw->pw_name, (char *)NULL);
1615 #else
1616 "-p", "-f", "--", pw->pw_name, (char *)NULL);
1617 #endif
1618
1619 /* Login couldn't be executed, die. */
1620
1621 perror("login");
1622 exit(1);
1623 }
1624
1625 static void
child_close_fds(void)1626 child_close_fds(void)
1627 {
1628 extern int auth_sock;
1629
1630 if (auth_sock != -1) {
1631 close(auth_sock);
1632 auth_sock = -1;
1633 }
1634
1635 if (packet_get_connection_in() == packet_get_connection_out())
1636 close(packet_get_connection_in());
1637 else {
1638 close(packet_get_connection_in());
1639 close(packet_get_connection_out());
1640 }
1641 /*
1642 * Close all descriptors related to channels. They will still remain
1643 * open in the parent.
1644 */
1645 /* XXX better use close-on-exec? -markus */
1646 channel_close_all();
1647
1648 #if !defined(ANDROID)
1649 /*
1650 * Close any extra file descriptors. Note that there may still be
1651 * descriptors left by system functions. They will be closed later.
1652 */
1653 endpwent();
1654 #endif
1655
1656 /*
1657 * Close any extra open file descriptors so that we don't have them
1658 * hanging around in clients. Note that we want to do this after
1659 * initgroups, because at least on Solaris 2.3 it leaves file
1660 * descriptors open.
1661 */
1662 closefrom(STDERR_FILENO + 1);
1663 }
1664
1665 /*
1666 * Performs common processing for the child, such as setting up the
1667 * environment, closing extra file descriptors, setting the user and group
1668 * ids, and executing the command or shell.
1669 */
1670 #define ARGV_MAX 10
1671 void
do_child(Session * s,const char * command)1672 do_child(Session *s, const char *command)
1673 {
1674 extern char **environ;
1675 char **env;
1676 char *argv[ARGV_MAX];
1677 const char *shell, *shell0, *hostname = NULL;
1678 struct passwd *pw = s->pw;
1679 int r = 0;
1680
1681 /* remove hostkey from the child's memory */
1682 destroy_sensitive_data();
1683
1684 /* Force a password change */
1685 if (s->authctxt->force_pwchange) {
1686 do_setusercontext(pw);
1687 child_close_fds();
1688 do_pwchange(s);
1689 exit(1);
1690 }
1691
1692 /* login(1) is only called if we execute the login shell */
1693 if (options.use_login && command != NULL)
1694 options.use_login = 0;
1695
1696 #ifdef _UNICOS
1697 cray_setup(pw->pw_uid, pw->pw_name, command);
1698 #endif /* _UNICOS */
1699
1700 /*
1701 * Login(1) does this as well, and it needs uid 0 for the "-h"
1702 * switch, so we let login(1) to this for us.
1703 */
1704 if (!options.use_login) {
1705 #ifdef HAVE_OSF_SIA
1706 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty);
1707 if (!check_quietlogin(s, command))
1708 do_motd();
1709 #else /* HAVE_OSF_SIA */
1710 /* When PAM is enabled we rely on it to do the nologin check */
1711 if (!options.use_pam)
1712 do_nologin(pw);
1713 do_setusercontext(pw);
1714 /*
1715 * PAM session modules in do_setusercontext may have
1716 * generated messages, so if this in an interactive
1717 * login then display them too.
1718 */
1719 if (!check_quietlogin(s, command))
1720 display_loginmsg();
1721 #endif /* HAVE_OSF_SIA */
1722 }
1723
1724 #ifdef USE_PAM
1725 if (options.use_pam && !options.use_login && !is_pam_session_open()) {
1726 debug3("PAM session not opened, exiting");
1727 display_loginmsg();
1728 exit(254);
1729 }
1730 #endif
1731
1732 /*
1733 * Get the shell from the password data. An empty shell field is
1734 * legal, and means /bin/sh.
1735 */
1736 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
1737
1738 /*
1739 * Make sure $SHELL points to the shell from the password file,
1740 * even if shell is overridden from login.conf
1741 */
1742 env = do_setup_env(s, shell);
1743
1744 #ifdef HAVE_LOGIN_CAP
1745 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
1746 #endif
1747
1748 /* we have to stash the hostname before we close our socket. */
1749 if (options.use_login)
1750 hostname = get_remote_name_or_ip(utmp_len,
1751 options.use_dns);
1752 /*
1753 * Close the connection descriptors; note that this is the child, and
1754 * the server will still have the socket open, and it is important
1755 * that we do not shutdown it. Note that the descriptors cannot be
1756 * closed before building the environment, as we call
1757 * get_remote_ipaddr there.
1758 */
1759 child_close_fds();
1760
1761 /*
1762 * Must take new environment into use so that .ssh/rc,
1763 * /etc/ssh/sshrc and xauth are run in the proper environment.
1764 */
1765 environ = env;
1766
1767 #if defined(KRB5) && defined(USE_AFS)
1768 /*
1769 * At this point, we check to see if AFS is active and if we have
1770 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see
1771 * if we can (and need to) extend the ticket into an AFS token. If
1772 * we don't do this, we run into potential problems if the user's
1773 * home directory is in AFS and it's not world-readable.
1774 */
1775
1776 if (options.kerberos_get_afs_token && k_hasafs() &&
1777 (s->authctxt->krb5_ctx != NULL)) {
1778 char cell[64];
1779
1780 debug("Getting AFS token");
1781
1782 k_setpag();
1783
1784 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
1785 krb5_afslog(s->authctxt->krb5_ctx,
1786 s->authctxt->krb5_fwd_ccache, cell, NULL);
1787
1788 krb5_afslog_home(s->authctxt->krb5_ctx,
1789 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir);
1790 }
1791 #endif
1792
1793 /* Change current directory to the user's home directory. */
1794 if (chdir(pw->pw_dir) < 0) {
1795 /* Suppress missing homedir warning for chroot case */
1796 #ifdef HAVE_LOGIN_CAP
1797 r = login_getcapbool(lc, "requirehome", 0);
1798 #endif
1799 if (r || options.chroot_directory == NULL ||
1800 strcasecmp(options.chroot_directory, "none") == 0)
1801 fprintf(stderr, "Could not chdir to home "
1802 "directory %s: %s\n", pw->pw_dir,
1803 strerror(errno));
1804 if (r)
1805 exit(1);
1806 }
1807
1808 closefrom(STDERR_FILENO + 1);
1809
1810 if (!options.use_login)
1811 do_rc_files(s, shell);
1812
1813 /* restore SIGPIPE for child */
1814 signal(SIGPIPE, SIG_DFL);
1815
1816 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) {
1817 printf("This service allows sftp connections only.\n");
1818 fflush(NULL);
1819 exit(1);
1820 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) {
1821 extern int optind, optreset;
1822 int i;
1823 char *p, *args;
1824
1825 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME);
1826 args = xstrdup(command ? command : "sftp-server");
1827 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " ")))
1828 if (i < ARGV_MAX - 1)
1829 argv[i++] = p;
1830 argv[i] = NULL;
1831 optind = optreset = 1;
1832 __progname = argv[0];
1833 #ifdef WITH_SELINUX
1834 ssh_selinux_change_context("sftpd_t");
1835 #endif
1836 exit(sftp_server_main(i, argv, s->pw));
1837 }
1838
1839 fflush(NULL);
1840
1841 if (options.use_login) {
1842 launch_login(pw, hostname);
1843 /* NEVERREACHED */
1844 }
1845
1846 /* Get the last component of the shell name. */
1847 if ((shell0 = strrchr(shell, '/')) != NULL)
1848 shell0++;
1849 else
1850 shell0 = shell;
1851
1852 /*
1853 * If we have no command, execute the shell. In this case, the shell
1854 * name to be passed in argv[0] is preceded by '-' to indicate that
1855 * this is a login shell.
1856 */
1857 if (!command) {
1858 char argv0[256];
1859
1860 /* Start the shell. Set initial character to '-'. */
1861 argv0[0] = '-';
1862
1863 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1)
1864 >= sizeof(argv0) - 1) {
1865 errno = EINVAL;
1866 perror(shell);
1867 exit(1);
1868 }
1869
1870 /* Execute the shell. */
1871 argv[0] = argv0;
1872 argv[1] = NULL;
1873 execve(shell, argv, env);
1874
1875 /* Executing the shell failed. */
1876 perror(shell);
1877 exit(1);
1878 }
1879 /*
1880 * Execute the command using the user's shell. This uses the -c
1881 * option to execute the command.
1882 */
1883 argv[0] = (char *) shell0;
1884 argv[1] = "-c";
1885 argv[2] = (char *) command;
1886 argv[3] = NULL;
1887 execve(shell, argv, env);
1888 perror(shell);
1889 exit(1);
1890 }
1891
1892 void
session_unused(int id)1893 session_unused(int id)
1894 {
1895 debug3("%s: session id %d unused", __func__, id);
1896 if (id >= options.max_sessions ||
1897 id >= sessions_nalloc) {
1898 fatal("%s: insane session id %d (max %d nalloc %d)",
1899 __func__, id, options.max_sessions, sessions_nalloc);
1900 }
1901 memset(&sessions[id], 0, sizeof(*sessions));
1902 sessions[id].self = id;
1903 sessions[id].used = 0;
1904 sessions[id].chanid = -1;
1905 sessions[id].ptyfd = -1;
1906 sessions[id].ttyfd = -1;
1907 sessions[id].ptymaster = -1;
1908 sessions[id].x11_chanids = NULL;
1909 sessions[id].next_unused = sessions_first_unused;
1910 sessions_first_unused = id;
1911 }
1912
1913 Session *
session_new(void)1914 session_new(void)
1915 {
1916 Session *s, *tmp;
1917
1918 if (sessions_first_unused == -1) {
1919 if (sessions_nalloc >= options.max_sessions)
1920 return NULL;
1921 debug2("%s: allocate (allocated %d max %d)",
1922 __func__, sessions_nalloc, options.max_sessions);
1923 tmp = xrealloc(sessions, sessions_nalloc + 1,
1924 sizeof(*sessions));
1925 if (tmp == NULL) {
1926 error("%s: cannot allocate %d sessions",
1927 __func__, sessions_nalloc + 1);
1928 return NULL;
1929 }
1930 sessions = tmp;
1931 session_unused(sessions_nalloc++);
1932 }
1933
1934 if (sessions_first_unused >= sessions_nalloc ||
1935 sessions_first_unused < 0) {
1936 fatal("%s: insane first_unused %d max %d nalloc %d",
1937 __func__, sessions_first_unused, options.max_sessions,
1938 sessions_nalloc);
1939 }
1940
1941 s = &sessions[sessions_first_unused];
1942 if (s->used) {
1943 fatal("%s: session %d already used",
1944 __func__, sessions_first_unused);
1945 }
1946 sessions_first_unused = s->next_unused;
1947 s->used = 1;
1948 s->next_unused = -1;
1949 debug("session_new: session %d", s->self);
1950
1951 return s;
1952 }
1953
1954 static void
session_dump(void)1955 session_dump(void)
1956 {
1957 int i;
1958 for (i = 0; i < sessions_nalloc; i++) {
1959 Session *s = &sessions[i];
1960
1961 debug("dump: used %d next_unused %d session %d %p "
1962 "channel %d pid %ld",
1963 s->used,
1964 s->next_unused,
1965 s->self,
1966 s,
1967 s->chanid,
1968 (long)s->pid);
1969 }
1970 }
1971
1972 int
session_open(Authctxt * authctxt,int chanid)1973 session_open(Authctxt *authctxt, int chanid)
1974 {
1975 Session *s = session_new();
1976 debug("session_open: channel %d", chanid);
1977 if (s == NULL) {
1978 error("no more sessions");
1979 return 0;
1980 }
1981 s->authctxt = authctxt;
1982 s->pw = authctxt->pw;
1983 if (s->pw == NULL || !authctxt->valid)
1984 fatal("no user for session %d", s->self);
1985 debug("session_open: session %d: link with channel %d", s->self, chanid);
1986 s->chanid = chanid;
1987 return 1;
1988 }
1989
1990 Session *
session_by_tty(char * tty)1991 session_by_tty(char *tty)
1992 {
1993 int i;
1994 for (i = 0; i < sessions_nalloc; i++) {
1995 Session *s = &sessions[i];
1996 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
1997 debug("session_by_tty: session %d tty %s", i, tty);
1998 return s;
1999 }
2000 }
2001 debug("session_by_tty: unknown tty %.100s", tty);
2002 session_dump();
2003 return NULL;
2004 }
2005
2006 static Session *
session_by_channel(int id)2007 session_by_channel(int id)
2008 {
2009 int i;
2010 for (i = 0; i < sessions_nalloc; i++) {
2011 Session *s = &sessions[i];
2012 if (s->used && s->chanid == id) {
2013 debug("session_by_channel: session %d channel %d",
2014 i, id);
2015 return s;
2016 }
2017 }
2018 debug("session_by_channel: unknown channel %d", id);
2019 session_dump();
2020 return NULL;
2021 }
2022
2023 static Session *
session_by_x11_channel(int id)2024 session_by_x11_channel(int id)
2025 {
2026 int i, j;
2027
2028 for (i = 0; i < sessions_nalloc; i++) {
2029 Session *s = &sessions[i];
2030
2031 if (s->x11_chanids == NULL || !s->used)
2032 continue;
2033 for (j = 0; s->x11_chanids[j] != -1; j++) {
2034 if (s->x11_chanids[j] == id) {
2035 debug("session_by_x11_channel: session %d "
2036 "channel %d", s->self, id);
2037 return s;
2038 }
2039 }
2040 }
2041 debug("session_by_x11_channel: unknown channel %d", id);
2042 session_dump();
2043 return NULL;
2044 }
2045
2046 static Session *
session_by_pid(pid_t pid)2047 session_by_pid(pid_t pid)
2048 {
2049 int i;
2050 debug("session_by_pid: pid %ld", (long)pid);
2051 for (i = 0; i < sessions_nalloc; i++) {
2052 Session *s = &sessions[i];
2053 if (s->used && s->pid == pid)
2054 return s;
2055 }
2056 error("session_by_pid: unknown pid %ld", (long)pid);
2057 session_dump();
2058 return NULL;
2059 }
2060
2061 static int
session_window_change_req(Session * s)2062 session_window_change_req(Session *s)
2063 {
2064 s->col = packet_get_int();
2065 s->row = packet_get_int();
2066 s->xpixel = packet_get_int();
2067 s->ypixel = packet_get_int();
2068 packet_check_eom();
2069 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
2070 return 1;
2071 }
2072
2073 static int
session_pty_req(Session * s)2074 session_pty_req(Session *s)
2075 {
2076 u_int len;
2077 int n_bytes;
2078
2079 if (no_pty_flag || !options.permit_tty) {
2080 debug("Allocating a pty not permitted for this authentication.");
2081 return 0;
2082 }
2083 if (s->ttyfd != -1) {
2084 packet_disconnect("Protocol error: you already have a pty.");
2085 return 0;
2086 }
2087
2088 s->term = packet_get_string(&len);
2089
2090 if (compat20) {
2091 s->col = packet_get_int();
2092 s->row = packet_get_int();
2093 } else {
2094 s->row = packet_get_int();
2095 s->col = packet_get_int();
2096 }
2097 s->xpixel = packet_get_int();
2098 s->ypixel = packet_get_int();
2099
2100 if (strcmp(s->term, "") == 0) {
2101 free(s->term);
2102 s->term = NULL;
2103 }
2104
2105 /* Allocate a pty and open it. */
2106 debug("Allocating pty.");
2107 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty,
2108 sizeof(s->tty)))) {
2109 free(s->term);
2110 s->term = NULL;
2111 s->ptyfd = -1;
2112 s->ttyfd = -1;
2113 error("session_pty_req: session %d alloc failed", s->self);
2114 return 0;
2115 }
2116 debug("session_pty_req: session %d alloc %s", s->self, s->tty);
2117
2118 /* for SSH1 the tty modes length is not given */
2119 if (!compat20)
2120 n_bytes = packet_remaining();
2121 tty_parse_modes(s->ttyfd, &n_bytes);
2122
2123 if (!use_privsep)
2124 pty_setowner(s->pw, s->tty);
2125
2126 /* Set window size from the packet. */
2127 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
2128
2129 packet_check_eom();
2130 session_proctitle(s);
2131 return 1;
2132 }
2133
2134 static int
session_subsystem_req(Session * s)2135 session_subsystem_req(Session *s)
2136 {
2137 struct stat st;
2138 u_int len;
2139 int success = 0;
2140 char *prog, *cmd;
2141 u_int i;
2142
2143 s->subsys = packet_get_string(&len);
2144 packet_check_eom();
2145 debug2("subsystem request for %.100s by user %s", s->subsys,
2146 s->pw->pw_name);
2147
2148 for (i = 0; i < options.num_subsystems; i++) {
2149 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) {
2150 prog = options.subsystem_command[i];
2151 cmd = options.subsystem_args[i];
2152 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) {
2153 s->is_subsystem = SUBSYSTEM_INT_SFTP;
2154 debug("subsystem: %s", prog);
2155 } else {
2156 if (stat(prog, &st) < 0)
2157 debug("subsystem: cannot stat %s: %s",
2158 prog, strerror(errno));
2159 s->is_subsystem = SUBSYSTEM_EXT;
2160 debug("subsystem: exec() %s", cmd);
2161 }
2162 success = do_exec(s, cmd) == 0;
2163 break;
2164 }
2165 }
2166
2167 if (!success)
2168 logit("subsystem request for %.100s by user %s failed, "
2169 "subsystem not found", s->subsys, s->pw->pw_name);
2170
2171 return success;
2172 }
2173
2174 static int
session_x11_req(Session * s)2175 session_x11_req(Session *s)
2176 {
2177 int success;
2178
2179 if (s->auth_proto != NULL || s->auth_data != NULL) {
2180 error("session_x11_req: session %d: "
2181 "x11 forwarding already active", s->self);
2182 return 0;
2183 }
2184 s->single_connection = packet_get_char();
2185 s->auth_proto = packet_get_string(NULL);
2186 s->auth_data = packet_get_string(NULL);
2187 s->screen = packet_get_int();
2188 packet_check_eom();
2189
2190 success = session_setup_x11fwd(s);
2191 if (!success) {
2192 free(s->auth_proto);
2193 free(s->auth_data);
2194 s->auth_proto = NULL;
2195 s->auth_data = NULL;
2196 }
2197 return success;
2198 }
2199
2200 static int
session_shell_req(Session * s)2201 session_shell_req(Session *s)
2202 {
2203 packet_check_eom();
2204 return do_exec(s, NULL) == 0;
2205 }
2206
2207 static int
session_exec_req(Session * s)2208 session_exec_req(Session *s)
2209 {
2210 u_int len, success;
2211
2212 char *command = packet_get_string(&len);
2213 packet_check_eom();
2214 success = do_exec(s, command) == 0;
2215 free(command);
2216 return success;
2217 }
2218
2219 static int
session_break_req(Session * s)2220 session_break_req(Session *s)
2221 {
2222
2223 packet_get_int(); /* ignored */
2224 packet_check_eom();
2225
2226 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0)
2227 return 0;
2228 return 1;
2229 }
2230
2231 static int
session_env_req(Session * s)2232 session_env_req(Session *s)
2233 {
2234 char *name, *val;
2235 u_int name_len, val_len, i;
2236
2237 name = packet_get_cstring(&name_len);
2238 val = packet_get_cstring(&val_len);
2239 packet_check_eom();
2240
2241 /* Don't set too many environment variables */
2242 if (s->num_env > 128) {
2243 debug2("Ignoring env request %s: too many env vars", name);
2244 goto fail;
2245 }
2246
2247 for (i = 0; i < options.num_accept_env; i++) {
2248 if (match_pattern(name, options.accept_env[i])) {
2249 debug2("Setting env %d: %s=%s", s->num_env, name, val);
2250 s->env = xrealloc(s->env, s->num_env + 1,
2251 sizeof(*s->env));
2252 s->env[s->num_env].name = name;
2253 s->env[s->num_env].val = val;
2254 s->num_env++;
2255 return (1);
2256 }
2257 }
2258 debug2("Ignoring env request %s: disallowed name", name);
2259
2260 fail:
2261 free(name);
2262 free(val);
2263 return (0);
2264 }
2265
2266 static int
session_auth_agent_req(Session * s)2267 session_auth_agent_req(Session *s)
2268 {
2269 static int called = 0;
2270 packet_check_eom();
2271 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) {
2272 debug("session_auth_agent_req: no_agent_forwarding_flag");
2273 return 0;
2274 }
2275 if (called) {
2276 return 0;
2277 } else {
2278 called = 1;
2279 return auth_input_request_forwarding(s->pw);
2280 }
2281 }
2282
2283 int
session_input_channel_req(Channel * c,const char * rtype)2284 session_input_channel_req(Channel *c, const char *rtype)
2285 {
2286 int success = 0;
2287 Session *s;
2288
2289 if ((s = session_by_channel(c->self)) == NULL) {
2290 logit("session_input_channel_req: no session %d req %.100s",
2291 c->self, rtype);
2292 return 0;
2293 }
2294 debug("session_input_channel_req: session %d req %s", s->self, rtype);
2295
2296 /*
2297 * a session is in LARVAL state until a shell, a command
2298 * or a subsystem is executed
2299 */
2300 if (c->type == SSH_CHANNEL_LARVAL) {
2301 if (strcmp(rtype, "shell") == 0) {
2302 success = session_shell_req(s);
2303 } else if (strcmp(rtype, "exec") == 0) {
2304 success = session_exec_req(s);
2305 } else if (strcmp(rtype, "pty-req") == 0) {
2306 success = session_pty_req(s);
2307 } else if (strcmp(rtype, "x11-req") == 0) {
2308 success = session_x11_req(s);
2309 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
2310 success = session_auth_agent_req(s);
2311 } else if (strcmp(rtype, "subsystem") == 0) {
2312 success = session_subsystem_req(s);
2313 } else if (strcmp(rtype, "env") == 0) {
2314 success = session_env_req(s);
2315 }
2316 }
2317 if (strcmp(rtype, "window-change") == 0) {
2318 success = session_window_change_req(s);
2319 } else if (strcmp(rtype, "break") == 0) {
2320 success = session_break_req(s);
2321 }
2322
2323 return success;
2324 }
2325
2326 void
session_set_fds(Session * s,int fdin,int fdout,int fderr,int ignore_fderr,int is_tty)2327 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr,
2328 int is_tty)
2329 {
2330 if (!compat20)
2331 fatal("session_set_fds: called for proto != 2.0");
2332 /*
2333 * now that have a child and a pipe to the child,
2334 * we can activate our channel and register the fd's
2335 */
2336 if (s->chanid == -1)
2337 fatal("no channel for session %d", s->self);
2338 channel_set_fds(s->chanid,
2339 fdout, fdin, fderr,
2340 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
2341 1, is_tty, CHAN_SES_WINDOW_DEFAULT);
2342 }
2343
2344 /*
2345 * Function to perform pty cleanup. Also called if we get aborted abnormally
2346 * (e.g., due to a dropped connection).
2347 */
2348 void
session_pty_cleanup2(Session * s)2349 session_pty_cleanup2(Session *s)
2350 {
2351 if (s == NULL) {
2352 error("session_pty_cleanup: no session");
2353 return;
2354 }
2355 if (s->ttyfd == -1)
2356 return;
2357
2358 debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
2359
2360 /* Record that the user has logged out. */
2361 if (s->pid != 0)
2362 record_logout(s->pid, s->tty, s->pw->pw_name);
2363
2364 /* Release the pseudo-tty. */
2365 if (getuid() == 0)
2366 pty_release(s->tty);
2367
2368 /*
2369 * Close the server side of the socket pairs. We must do this after
2370 * the pty cleanup, so that another process doesn't get this pty
2371 * while we're still cleaning up.
2372 */
2373 if (s->ptymaster != -1 && close(s->ptymaster) < 0)
2374 error("close(s->ptymaster/%d): %s",
2375 s->ptymaster, strerror(errno));
2376
2377 /* unlink pty from session */
2378 s->ttyfd = -1;
2379 }
2380
2381 void
session_pty_cleanup(Session * s)2382 session_pty_cleanup(Session *s)
2383 {
2384 PRIVSEP(session_pty_cleanup2(s));
2385 }
2386
2387 static char *
sig2name(int sig)2388 sig2name(int sig)
2389 {
2390 #define SSH_SIG(x) if (sig == SIG ## x) return #x
2391 SSH_SIG(ABRT);
2392 SSH_SIG(ALRM);
2393 SSH_SIG(FPE);
2394 SSH_SIG(HUP);
2395 SSH_SIG(ILL);
2396 SSH_SIG(INT);
2397 SSH_SIG(KILL);
2398 SSH_SIG(PIPE);
2399 SSH_SIG(QUIT);
2400 SSH_SIG(SEGV);
2401 SSH_SIG(TERM);
2402 SSH_SIG(USR1);
2403 SSH_SIG(USR2);
2404 #undef SSH_SIG
2405 return "SIG@openssh.com";
2406 }
2407
2408 static void
session_close_x11(int id)2409 session_close_x11(int id)
2410 {
2411 Channel *c;
2412
2413 if ((c = channel_by_id(id)) == NULL) {
2414 debug("session_close_x11: x11 channel %d missing", id);
2415 } else {
2416 /* Detach X11 listener */
2417 debug("session_close_x11: detach x11 channel %d", id);
2418 channel_cancel_cleanup(id);
2419 if (c->ostate != CHAN_OUTPUT_CLOSED)
2420 chan_mark_dead(c);
2421 }
2422 }
2423
2424 static void
session_close_single_x11(int id,void * arg)2425 session_close_single_x11(int id, void *arg)
2426 {
2427 Session *s;
2428 u_int i;
2429
2430 debug3("session_close_single_x11: channel %d", id);
2431 channel_cancel_cleanup(id);
2432 if ((s = session_by_x11_channel(id)) == NULL)
2433 fatal("session_close_single_x11: no x11 channel %d", id);
2434 for (i = 0; s->x11_chanids[i] != -1; i++) {
2435 debug("session_close_single_x11: session %d: "
2436 "closing channel %d", s->self, s->x11_chanids[i]);
2437 /*
2438 * The channel "id" is already closing, but make sure we
2439 * close all of its siblings.
2440 */
2441 if (s->x11_chanids[i] != id)
2442 session_close_x11(s->x11_chanids[i]);
2443 }
2444 free(s->x11_chanids);
2445 s->x11_chanids = NULL;
2446 free(s->display);
2447 s->display = NULL;
2448 free(s->auth_proto);
2449 s->auth_proto = NULL;
2450 free(s->auth_data);
2451 s->auth_data = NULL;
2452 free(s->auth_display);
2453 s->auth_display = NULL;
2454 }
2455
2456 static void
session_exit_message(Session * s,int status)2457 session_exit_message(Session *s, int status)
2458 {
2459 Channel *c;
2460
2461 if ((c = channel_lookup(s->chanid)) == NULL)
2462 fatal("session_exit_message: session %d: no channel %d",
2463 s->self, s->chanid);
2464 debug("session_exit_message: session %d channel %d pid %ld",
2465 s->self, s->chanid, (long)s->pid);
2466
2467 if (WIFEXITED(status)) {
2468 channel_request_start(s->chanid, "exit-status", 0);
2469 packet_put_int(WEXITSTATUS(status));
2470 packet_send();
2471 } else if (WIFSIGNALED(status)) {
2472 channel_request_start(s->chanid, "exit-signal", 0);
2473 packet_put_cstring(sig2name(WTERMSIG(status)));
2474 #ifdef WCOREDUMP
2475 packet_put_char(WCOREDUMP(status)? 1 : 0);
2476 #else /* WCOREDUMP */
2477 packet_put_char(0);
2478 #endif /* WCOREDUMP */
2479 packet_put_cstring("");
2480 packet_put_cstring("");
2481 packet_send();
2482 } else {
2483 /* Some weird exit cause. Just exit. */
2484 packet_disconnect("wait returned status %04x.", status);
2485 }
2486
2487 /* disconnect channel */
2488 debug("session_exit_message: release channel %d", s->chanid);
2489
2490 /*
2491 * Adjust cleanup callback attachment to send close messages when
2492 * the channel gets EOF. The session will be then be closed
2493 * by session_close_by_channel when the childs close their fds.
2494 */
2495 channel_register_cleanup(c->self, session_close_by_channel, 1);
2496
2497 /*
2498 * emulate a write failure with 'chan_write_failed', nobody will be
2499 * interested in data we write.
2500 * Note that we must not call 'chan_read_failed', since there could
2501 * be some more data waiting in the pipe.
2502 */
2503 if (c->ostate != CHAN_OUTPUT_CLOSED)
2504 chan_write_failed(c);
2505 }
2506
2507 void
session_close(Session * s)2508 session_close(Session *s)
2509 {
2510 u_int i;
2511
2512 debug("session_close: session %d pid %ld", s->self, (long)s->pid);
2513 if (s->ttyfd != -1)
2514 session_pty_cleanup(s);
2515 free(s->term);
2516 free(s->display);
2517 free(s->x11_chanids);
2518 free(s->auth_display);
2519 free(s->auth_data);
2520 free(s->auth_proto);
2521 free(s->subsys);
2522 if (s->env != NULL) {
2523 for (i = 0; i < s->num_env; i++) {
2524 free(s->env[i].name);
2525 free(s->env[i].val);
2526 }
2527 free(s->env);
2528 }
2529 session_proctitle(s);
2530 session_unused(s->self);
2531 }
2532
2533 void
session_close_by_pid(pid_t pid,int status)2534 session_close_by_pid(pid_t pid, int status)
2535 {
2536 Session *s = session_by_pid(pid);
2537 if (s == NULL) {
2538 debug("session_close_by_pid: no session for pid %ld",
2539 (long)pid);
2540 return;
2541 }
2542 if (s->chanid != -1)
2543 session_exit_message(s, status);
2544 if (s->ttyfd != -1)
2545 session_pty_cleanup(s);
2546 s->pid = 0;
2547 }
2548
2549 /*
2550 * this is called when a channel dies before
2551 * the session 'child' itself dies
2552 */
2553 void
session_close_by_channel(int id,void * arg)2554 session_close_by_channel(int id, void *arg)
2555 {
2556 Session *s = session_by_channel(id);
2557 u_int i;
2558
2559 if (s == NULL) {
2560 debug("session_close_by_channel: no session for id %d", id);
2561 return;
2562 }
2563 debug("session_close_by_channel: channel %d child %ld",
2564 id, (long)s->pid);
2565 if (s->pid != 0) {
2566 debug("session_close_by_channel: channel %d: has child", id);
2567 /*
2568 * delay detach of session, but release pty, since
2569 * the fd's to the child are already closed
2570 */
2571 if (s->ttyfd != -1)
2572 session_pty_cleanup(s);
2573 return;
2574 }
2575 /* detach by removing callback */
2576 channel_cancel_cleanup(s->chanid);
2577
2578 /* Close any X11 listeners associated with this session */
2579 if (s->x11_chanids != NULL) {
2580 for (i = 0; s->x11_chanids[i] != -1; i++) {
2581 session_close_x11(s->x11_chanids[i]);
2582 s->x11_chanids[i] = -1;
2583 }
2584 }
2585
2586 s->chanid = -1;
2587 session_close(s);
2588 }
2589
2590 void
session_destroy_all(void (* closefunc)(Session *))2591 session_destroy_all(void (*closefunc)(Session *))
2592 {
2593 int i;
2594 for (i = 0; i < sessions_nalloc; i++) {
2595 Session *s = &sessions[i];
2596 if (s->used) {
2597 if (closefunc != NULL)
2598 closefunc(s);
2599 else
2600 session_close(s);
2601 }
2602 }
2603 }
2604
2605 static char *
session_tty_list(void)2606 session_tty_list(void)
2607 {
2608 static char buf[1024];
2609 int i;
2610 char *cp;
2611
2612 buf[0] = '\0';
2613 for (i = 0; i < sessions_nalloc; i++) {
2614 Session *s = &sessions[i];
2615 if (s->used && s->ttyfd != -1) {
2616
2617 if (strncmp(s->tty, "/dev/", 5) != 0) {
2618 cp = strrchr(s->tty, '/');
2619 cp = (cp == NULL) ? s->tty : cp + 1;
2620 } else
2621 cp = s->tty + 5;
2622
2623 if (buf[0] != '\0')
2624 strlcat(buf, ",", sizeof buf);
2625 strlcat(buf, cp, sizeof buf);
2626 }
2627 }
2628 if (buf[0] == '\0')
2629 strlcpy(buf, "notty", sizeof buf);
2630 return buf;
2631 }
2632
2633 void
session_proctitle(Session * s)2634 session_proctitle(Session *s)
2635 {
2636 if (s->pw == NULL)
2637 error("no user for session %d", s->self);
2638 else
2639 setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
2640 }
2641
2642 int
session_setup_x11fwd(Session * s)2643 session_setup_x11fwd(Session *s)
2644 {
2645 struct stat st;
2646 char display[512], auth_display[512];
2647 char hostname[NI_MAXHOST];
2648 u_int i;
2649
2650 if (no_x11_forwarding_flag) {
2651 packet_send_debug("X11 forwarding disabled in user configuration file.");
2652 return 0;
2653 }
2654 if (!options.x11_forwarding) {
2655 debug("X11 forwarding disabled in server configuration file.");
2656 return 0;
2657 }
2658 if (options.xauth_location == NULL ||
2659 (stat(options.xauth_location, &st) == -1)) {
2660 packet_send_debug("No xauth program; cannot forward with spoofing.");
2661 return 0;
2662 }
2663 if (options.use_login) {
2664 packet_send_debug("X11 forwarding disabled; "
2665 "not compatible with UseLogin=yes.");
2666 return 0;
2667 }
2668 if (s->display != NULL) {
2669 debug("X11 display already set.");
2670 return 0;
2671 }
2672 if (x11_create_display_inet(options.x11_display_offset,
2673 options.x11_use_localhost, s->single_connection,
2674 &s->display_number, &s->x11_chanids) == -1) {
2675 debug("x11_create_display_inet failed.");
2676 return 0;
2677 }
2678 for (i = 0; s->x11_chanids[i] != -1; i++) {
2679 channel_register_cleanup(s->x11_chanids[i],
2680 session_close_single_x11, 0);
2681 }
2682
2683 /* Set up a suitable value for the DISPLAY variable. */
2684 if (gethostname(hostname, sizeof(hostname)) < 0)
2685 fatal("gethostname: %.100s", strerror(errno));
2686 /*
2687 * auth_display must be used as the displayname when the
2688 * authorization entry is added with xauth(1). This will be
2689 * different than the DISPLAY string for localhost displays.
2690 */
2691 if (options.x11_use_localhost) {
2692 snprintf(display, sizeof display, "localhost:%u.%u",
2693 s->display_number, s->screen);
2694 snprintf(auth_display, sizeof auth_display, "unix:%u.%u",
2695 s->display_number, s->screen);
2696 s->display = xstrdup(display);
2697 s->auth_display = xstrdup(auth_display);
2698 } else {
2699 #ifdef IPADDR_IN_DISPLAY
2700 struct hostent *he;
2701 struct in_addr my_addr;
2702
2703 he = gethostbyname(hostname);
2704 if (he == NULL) {
2705 error("Can't get IP address for X11 DISPLAY.");
2706 packet_send_debug("Can't get IP address for X11 DISPLAY.");
2707 return 0;
2708 }
2709 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
2710 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr),
2711 s->display_number, s->screen);
2712 #else
2713 snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
2714 s->display_number, s->screen);
2715 #endif
2716 s->display = xstrdup(display);
2717 s->auth_display = xstrdup(display);
2718 }
2719
2720 return 1;
2721 }
2722
2723 static void
do_authenticated2(Authctxt * authctxt)2724 do_authenticated2(Authctxt *authctxt)
2725 {
2726 server_loop2(authctxt);
2727 }
2728
2729 void
do_cleanup(Authctxt * authctxt)2730 do_cleanup(Authctxt *authctxt)
2731 {
2732 static int called = 0;
2733
2734 debug("do_cleanup");
2735
2736 /* no cleanup if we're in the child for login shell */
2737 if (is_child)
2738 return;
2739
2740 /* avoid double cleanup */
2741 if (called)
2742 return;
2743 called = 1;
2744
2745 if (authctxt == NULL)
2746 return;
2747
2748 #ifdef USE_PAM
2749 if (options.use_pam) {
2750 sshpam_cleanup();
2751 sshpam_thread_cleanup();
2752 }
2753 #endif
2754
2755 if (!authctxt->authenticated)
2756 return;
2757
2758 #ifdef KRB5
2759 if (options.kerberos_ticket_cleanup &&
2760 authctxt->krb5_ctx)
2761 krb5_cleanup_proc(authctxt);
2762 #endif
2763
2764 #ifdef GSSAPI
2765 if (compat20 && options.gss_cleanup_creds)
2766 ssh_gssapi_cleanup_creds();
2767 #endif
2768
2769 /* remove agent socket */
2770 auth_sock_cleanup_proc(authctxt->pw);
2771
2772 /*
2773 * Cleanup ptys/utmp only if privsep is disabled,
2774 * or if running in monitor.
2775 */
2776 if (!use_privsep || mm_is_monitor())
2777 session_destroy_all(session_pty_cleanup2);
2778 }
2779