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-rw-r--r--session.c1153
1 files changed, 1153 insertions, 0 deletions
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1/*
2 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
3 * All rights reserved
4 */
5
6#include "includes.h"
7RCSID("$OpenBSD: session.c,v 1.1 2000/03/28 21:15:45 markus Exp $");
8
9#include "xmalloc.h"
10#include "ssh.h"
11#include "pty.h"
12#include "packet.h"
13#include "buffer.h"
14#include "cipher.h"
15#include "mpaux.h"
16#include "servconf.h"
17#include "uidswap.h"
18#include "compat.h"
19#include "channels.h"
20#include "nchan.h"
21
22/* types */
23
24#define TTYSZ 64
25typedef struct Session Session;
26struct Session {
27 int used;
28 int self;
29 struct passwd *pw;
30 pid_t pid;
31 /* tty */
32 char *term;
33 int ptyfd, ttyfd, ptymaster;
34 int row, col, xpixel, ypixel;
35 char tty[TTYSZ];
36 /* X11 */
37 char *display;
38 int screen;
39 char *auth_proto;
40 char *auth_data;
41 /* proto 2 */
42 int chanid;
43};
44
45/* func */
46
47Session *session_new(void);
48void session_set_fds(Session *s, int fdin, int fdout, int fderr);
49void session_pty_cleanup(Session *s);
50void do_exec_pty(Session *s, const char *command, struct passwd * pw);
51void do_exec_no_pty(Session *s, const char *command, struct passwd * pw);
52
53void
54do_child(const char *command, struct passwd * pw, const char *term,
55 const char *display, const char *auth_proto,
56 const char *auth_data, const char *ttyname);
57
58/* import */
59extern ServerOptions options;
60extern char *__progname;
61extern int log_stderr;
62extern int debug_flag;
63
64/* Local Xauthority file. */
65static char *xauthfile;
66
67/* data */
68#define MAX_SESSIONS 10
69Session sessions[MAX_SESSIONS];
70
71/* Flags set in auth-rsa from authorized_keys flags. These are set in auth-rsa.c. */
72int no_port_forwarding_flag = 0;
73int no_agent_forwarding_flag = 0;
74int no_x11_forwarding_flag = 0;
75int no_pty_flag = 0;
76
77/* RSA authentication "command=" option. */
78char *forced_command = NULL;
79
80/* RSA authentication "environment=" options. */
81struct envstring *custom_environment = NULL;
82
83/*
84 * Remove local Xauthority file.
85 */
86void
87xauthfile_cleanup_proc(void *ignore)
88{
89 debug("xauthfile_cleanup_proc called");
90
91 if (xauthfile != NULL) {
92 char *p;
93 unlink(xauthfile);
94 p = strrchr(xauthfile, '/');
95 if (p != NULL) {
96 *p = '\0';
97 rmdir(xauthfile);
98 }
99 xfree(xauthfile);
100 xauthfile = NULL;
101 }
102}
103
104/*
105 * Function to perform cleanup if we get aborted abnormally (e.g., due to a
106 * dropped connection).
107 */
108void
109pty_cleanup_proc(void *session)
110{
111 Session *s=session;
112 if (s == NULL)
113 fatal("pty_cleanup_proc: no session");
114 debug("pty_cleanup_proc: %s", s->tty);
115
116 if (s->pid != 0) {
117 /* Record that the user has logged out. */
118 record_logout(s->pid, s->tty);
119 }
120
121 /* Release the pseudo-tty. */
122 pty_release(s->tty);
123}
124
125/*
126 * Prepares for an interactive session. This is called after the user has
127 * been successfully authenticated. During this message exchange, pseudo
128 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings
129 * are requested, etc.
130 */
131void
132do_authenticated(struct passwd * pw)
133{
134 Session *s;
135 int type;
136 int compression_level = 0, enable_compression_after_reply = 0;
137 int have_pty = 0;
138 char *command;
139 int n_bytes;
140 int plen;
141 unsigned int proto_len, data_len, dlen;
142
143 /*
144 * Cancel the alarm we set to limit the time taken for
145 * authentication.
146 */
147 alarm(0);
148
149 /*
150 * Inform the channel mechanism that we are the server side and that
151 * the client may request to connect to any port at all. (The user
152 * could do it anyway, and we wouldn\'t know what is permitted except
153 * by the client telling us, so we can equally well trust the client
154 * not to request anything bogus.)
155 */
156 if (!no_port_forwarding_flag)
157 channel_permit_all_opens();
158
159 s = session_new();
160
161 /*
162 * We stay in this loop until the client requests to execute a shell
163 * or a command.
164 */
165 for (;;) {
166 int success = 0;
167
168 /* Get a packet from the client. */
169 type = packet_read(&plen);
170
171 /* Process the packet. */
172 switch (type) {
173 case SSH_CMSG_REQUEST_COMPRESSION:
174 packet_integrity_check(plen, 4, type);
175 compression_level = packet_get_int();
176 if (compression_level < 1 || compression_level > 9) {
177 packet_send_debug("Received illegal compression level %d.",
178 compression_level);
179 break;
180 }
181 /* Enable compression after we have responded with SUCCESS. */
182 enable_compression_after_reply = 1;
183 success = 1;
184 break;
185
186 case SSH_CMSG_REQUEST_PTY:
187 if (no_pty_flag) {
188 debug("Allocating a pty not permitted for this authentication.");
189 break;
190 }
191 if (have_pty)
192 packet_disconnect("Protocol error: you already have a pty.");
193
194 debug("Allocating pty.");
195
196 /* Allocate a pty and open it. */
197 if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty,
198 sizeof(s->tty))) {
199 error("Failed to allocate pty.");
200 break;
201 }
202 fatal_add_cleanup(pty_cleanup_proc, (void *)s);
203 pty_setowner(pw, s->tty);
204
205 /* Get TERM from the packet. Note that the value may be of arbitrary length. */
206 s->term = packet_get_string(&dlen);
207 packet_integrity_check(dlen, strlen(s->term), type);
208 /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */
209 /* Remaining bytes */
210 n_bytes = plen - (4 + dlen + 4 * 4);
211
212 if (strcmp(s->term, "") == 0) {
213 xfree(s->term);
214 s->term = NULL;
215 }
216 /* Get window size from the packet. */
217 s->row = packet_get_int();
218 s->col = packet_get_int();
219 s->xpixel = packet_get_int();
220 s->ypixel = packet_get_int();
221 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
222
223 /* Get tty modes from the packet. */
224 tty_parse_modes(s->ttyfd, &n_bytes);
225 packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type);
226
227 /* Indicate that we now have a pty. */
228 success = 1;
229 have_pty = 1;
230 break;
231
232 case SSH_CMSG_X11_REQUEST_FORWARDING:
233 if (!options.x11_forwarding) {
234 packet_send_debug("X11 forwarding disabled in server configuration file.");
235 break;
236 }
237#ifdef XAUTH_PATH
238 if (no_x11_forwarding_flag) {
239 packet_send_debug("X11 forwarding not permitted for this authentication.");
240 break;
241 }
242 debug("Received request for X11 forwarding with auth spoofing.");
243 if (s->display != NULL)
244 packet_disconnect("Protocol error: X11 display already set.");
245
246 s->auth_proto = packet_get_string(&proto_len);
247 s->auth_data = packet_get_string(&data_len);
248 packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type);
249
250 if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER)
251 s->screen = packet_get_int();
252 else
253 s->screen = 0;
254 s->display = x11_create_display_inet(s->screen, options.x11_display_offset);
255
256 if (s->display == NULL)
257 break;
258
259 /* Setup to always have a local .Xauthority. */
260 xauthfile = xmalloc(MAXPATHLEN);
261 strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
262 temporarily_use_uid(pw->pw_uid);
263 if (mkdtemp(xauthfile) == NULL) {
264 restore_uid();
265 error("private X11 dir: mkdtemp %s failed: %s",
266 xauthfile, strerror(errno));
267 xfree(xauthfile);
268 xauthfile = NULL;
269 break;
270 }
271 strlcat(xauthfile, "/cookies", MAXPATHLEN);
272 open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
273 restore_uid();
274 fatal_add_cleanup(xauthfile_cleanup_proc, NULL);
275 success = 1;
276 break;
277#else /* XAUTH_PATH */
278 packet_send_debug("No xauth program; cannot forward with spoofing.");
279 break;
280#endif /* XAUTH_PATH */
281
282 case SSH_CMSG_AGENT_REQUEST_FORWARDING:
283 if (no_agent_forwarding_flag || compat13) {
284 debug("Authentication agent forwarding not permitted for this authentication.");
285 break;
286 }
287 debug("Received authentication agent forwarding request.");
288 auth_input_request_forwarding(pw);
289 success = 1;
290 break;
291
292 case SSH_CMSG_PORT_FORWARD_REQUEST:
293 if (no_port_forwarding_flag) {
294 debug("Port forwarding not permitted for this authentication.");
295 break;
296 }
297 debug("Received TCP/IP port forwarding request.");
298 channel_input_port_forward_request(pw->pw_uid == 0);
299 success = 1;
300 break;
301
302 case SSH_CMSG_MAX_PACKET_SIZE:
303 if (packet_set_maxsize(packet_get_int()) > 0)
304 success = 1;
305 break;
306
307 case SSH_CMSG_EXEC_SHELL:
308 case SSH_CMSG_EXEC_CMD:
309 /* Set interactive/non-interactive mode. */
310 packet_set_interactive(have_pty || s->display != NULL,
311 options.keepalives);
312
313 if (type == SSH_CMSG_EXEC_CMD) {
314 command = packet_get_string(&dlen);
315 debug("Exec command '%.500s'", command);
316 packet_integrity_check(plen, 4 + dlen, type);
317 } else {
318 command = NULL;
319 packet_integrity_check(plen, 0, type);
320 }
321 if (forced_command != NULL) {
322 command = forced_command;
323 debug("Forced command '%.500s'", forced_command);
324 }
325 if (have_pty)
326 do_exec_pty(s, command, pw);
327 else
328 do_exec_no_pty(s, command, pw);
329
330 if (command != NULL)
331 xfree(command);
332 /* Cleanup user's local Xauthority file. */
333 if (xauthfile)
334 xauthfile_cleanup_proc(NULL);
335 return;
336
337 default:
338 /*
339 * Any unknown messages in this phase are ignored,
340 * and a failure message is returned.
341 */
342 log("Unknown packet type received after authentication: %d", type);
343 }
344 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
345 packet_send();
346 packet_write_wait();
347
348 /* Enable compression now that we have replied if appropriate. */
349 if (enable_compression_after_reply) {
350 enable_compression_after_reply = 0;
351 packet_start_compression(compression_level);
352 }
353 }
354}
355
356/*
357 * This is called to fork and execute a command when we have no tty. This
358 * will call do_child from the child, and server_loop from the parent after
359 * setting up file descriptors and such.
360 */
361void
362do_exec_no_pty(Session *s, const char *command, struct passwd * pw)
363{
364 int pid;
365
366#ifdef USE_PIPES
367 int pin[2], pout[2], perr[2];
368 /* Allocate pipes for communicating with the program. */
369 if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0)
370 packet_disconnect("Could not create pipes: %.100s",
371 strerror(errno));
372#else /* USE_PIPES */
373 int inout[2], err[2];
374 /* Uses socket pairs to communicate with the program. */
375 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 ||
376 socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0)
377 packet_disconnect("Could not create socket pairs: %.100s",
378 strerror(errno));
379#endif /* USE_PIPES */
380 if (s == NULL)
381 fatal("do_exec_no_pty: no session");
382
383 setproctitle("%s@notty", pw->pw_name);
384
385#ifdef USE_PAM
386 do_pam_setcred();
387#endif /* USE_PAM */
388
389 /* Fork the child. */
390 if ((pid = fork()) == 0) {
391 /* Child. Reinitialize the log since the pid has changed. */
392 log_init(__progname, options.log_level, options.log_facility, log_stderr);
393
394 /*
395 * Create a new session and process group since the 4.4BSD
396 * setlogin() affects the entire process group.
397 */
398 if (setsid() < 0)
399 error("setsid failed: %.100s", strerror(errno));
400
401#ifdef USE_PIPES
402 /*
403 * Redirect stdin. We close the parent side of the socket
404 * pair, and make the child side the standard input.
405 */
406 close(pin[1]);
407 if (dup2(pin[0], 0) < 0)
408 perror("dup2 stdin");
409 close(pin[0]);
410
411 /* Redirect stdout. */
412 close(pout[0]);
413 if (dup2(pout[1], 1) < 0)
414 perror("dup2 stdout");
415 close(pout[1]);
416
417 /* Redirect stderr. */
418 close(perr[0]);
419 if (dup2(perr[1], 2) < 0)
420 perror("dup2 stderr");
421 close(perr[1]);
422#else /* USE_PIPES */
423 /*
424 * Redirect stdin, stdout, and stderr. Stdin and stdout will
425 * use the same socket, as some programs (particularly rdist)
426 * seem to depend on it.
427 */
428 close(inout[1]);
429 close(err[1]);
430 if (dup2(inout[0], 0) < 0) /* stdin */
431 perror("dup2 stdin");
432 if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */
433 perror("dup2 stdout");
434 if (dup2(err[0], 2) < 0) /* stderr */
435 perror("dup2 stderr");
436#endif /* USE_PIPES */
437
438 /* Do processing for the child (exec command etc). */
439 do_child(command, pw, NULL, s->display, s->auth_proto, s->auth_data, NULL);
440 /* NOTREACHED */
441 }
442 if (pid < 0)
443 packet_disconnect("fork failed: %.100s", strerror(errno));
444 s->pid = pid;
445#ifdef USE_PIPES
446 /* We are the parent. Close the child sides of the pipes. */
447 close(pin[0]);
448 close(pout[1]);
449 close(perr[1]);
450
451 /* Enter the interactive session. */
452 server_loop(pid, pin[1], pout[0], perr[0]);
453 /* server_loop has closed pin[1], pout[1], and perr[1]. */
454#else /* USE_PIPES */
455 /* We are the parent. Close the child sides of the socket pairs. */
456 close(inout[0]);
457 close(err[0]);
458
459 /*
460 * Enter the interactive session. Note: server_loop must be able to
461 * handle the case that fdin and fdout are the same.
462 */
463 server_loop(pid, inout[1], inout[1], err[1]);
464 /* server_loop has closed inout[1] and err[1]. */
465#endif /* USE_PIPES */
466}
467
468/*
469 * This is called to fork and execute a command when we have a tty. This
470 * will call do_child from the child, and server_loop from the parent after
471 * setting up file descriptors, controlling tty, updating wtmp, utmp,
472 * lastlog, and other such operations.
473 */
474void
475do_exec_pty(Session *s, const char *command, struct passwd * pw)
476{
477 FILE *f;
478 char buf[100], *time_string;
479 char line[256];
480 const char *hostname;
481 int fdout, ptyfd, ttyfd, ptymaster;
482 int quiet_login;
483 pid_t pid;
484 socklen_t fromlen;
485 struct sockaddr_storage from;
486 struct stat st;
487 time_t last_login_time;
488
489 if (s == NULL)
490 fatal("do_exec_pty: no session");
491 ptyfd = s->ptyfd;
492 ttyfd = s->ttyfd;
493
494 /* Get remote host name. */
495 hostname = get_canonical_hostname();
496
497 /*
498 * Get the time when the user last logged in. Buf will be set to
499 * contain the hostname the last login was from.
500 */
501 if (!options.use_login) {
502 last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name,
503 buf, sizeof(buf));
504 }
505 setproctitle("%s@%s", pw->pw_name, strrchr(s->tty, '/') + 1);
506
507#ifdef USE_PAM
508 do_pam_session(pw->pw_name, s->tty);
509 do_pam_setcred();
510#endif /* USE_PAM */
511
512 /* Fork the child. */
513 if ((pid = fork()) == 0) {
514 pid = getpid();
515
516 /* Child. Reinitialize the log because the pid has
517 changed. */
518 log_init(__progname, options.log_level, options.log_facility, log_stderr);
519
520 /* Close the master side of the pseudo tty. */
521 close(ptyfd);
522
523 /* Make the pseudo tty our controlling tty. */
524 pty_make_controlling_tty(&ttyfd, s->tty);
525
526 /* Redirect stdin from the pseudo tty. */
527 if (dup2(ttyfd, fileno(stdin)) < 0)
528 error("dup2 stdin failed: %.100s", strerror(errno));
529
530 /* Redirect stdout to the pseudo tty. */
531 if (dup2(ttyfd, fileno(stdout)) < 0)
532 error("dup2 stdin failed: %.100s", strerror(errno));
533
534 /* Redirect stderr to the pseudo tty. */
535 if (dup2(ttyfd, fileno(stderr)) < 0)
536 error("dup2 stdin failed: %.100s", strerror(errno));
537
538 /* Close the extra descriptor for the pseudo tty. */
539 close(ttyfd);
540
541///XXXX ? move to do_child() ??
542 /*
543 * Get IP address of client. This is needed because we want
544 * to record where the user logged in from. If the
545 * connection is not a socket, let the ip address be 0.0.0.0.
546 */
547 memset(&from, 0, sizeof(from));
548 if (packet_connection_is_on_socket()) {
549 fromlen = sizeof(from);
550 if (getpeername(packet_get_connection_in(),
551 (struct sockaddr *) & from, &fromlen) < 0) {
552 debug("getpeername: %.100s", strerror(errno));
553 fatal_cleanup();
554 }
555 }
556 /* Record that there was a login on that terminal. */
557 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, hostname,
558 (struct sockaddr *)&from);
559
560 /* Check if .hushlogin exists. */
561 snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir);
562 quiet_login = stat(line, &st) >= 0;
563
564#ifdef USE_PAM
565 if (!quiet_login)
566 print_pam_messages();
567#endif /* USE_PAM */
568
569 /*
570 * If the user has logged in before, display the time of last
571 * login. However, don't display anything extra if a command
572 * has been specified (so that ssh can be used to execute
573 * commands on a remote machine without users knowing they
574 * are going to another machine). Login(1) will do this for
575 * us as well, so check if login(1) is used
576 */
577 if (command == NULL && last_login_time != 0 && !quiet_login &&
578 !options.use_login) {
579 /* Convert the date to a string. */
580 time_string = ctime(&last_login_time);
581 /* Remove the trailing newline. */
582 if (strchr(time_string, '\n'))
583 *strchr(time_string, '\n') = 0;
584 /* Display the last login time. Host if displayed
585 if known. */
586 if (strcmp(buf, "") == 0)
587 printf("Last login: %s\r\n", time_string);
588 else
589 printf("Last login: %s from %s\r\n", time_string, buf);
590 }
591 /*
592 * Print /etc/motd unless a command was specified or printing
593 * it was disabled in server options or login(1) will be
594 * used. Note that some machines appear to print it in
595 * /etc/profile or similar.
596 */
597 if (command == NULL && options.print_motd && !quiet_login &&
598 !options.use_login) {
599 /* Print /etc/motd if it exists. */
600 f = fopen("/etc/motd", "r");
601 if (f) {
602 while (fgets(line, sizeof(line), f))
603 fputs(line, stdout);
604 fclose(f);
605 }
606 }
607 /* Do common processing for the child, such as execing the command. */
608 do_child(command, pw, s->term, s->display, s->auth_proto, s->auth_data, s->tty);
609 /* NOTREACHED */
610 }
611 if (pid < 0)
612 packet_disconnect("fork failed: %.100s", strerror(errno));
613 s->pid = pid;
614
615 /* Parent. Close the slave side of the pseudo tty. */
616 close(ttyfd);
617
618 /*
619 * Create another descriptor of the pty master side for use as the
620 * standard input. We could use the original descriptor, but this
621 * simplifies code in server_loop. The descriptor is bidirectional.
622 */
623 fdout = dup(ptyfd);
624 if (fdout < 0)
625 packet_disconnect("dup #1 failed: %.100s", strerror(errno));
626
627 /* we keep a reference to the pty master */
628 ptymaster = dup(ptyfd);
629 if (ptymaster < 0)
630 packet_disconnect("dup #2 failed: %.100s", strerror(errno));
631 s->ptymaster = ptymaster;
632
633 /* Enter interactive session. */
634 server_loop(pid, ptyfd, fdout, -1);
635 /* server_loop _has_ closed ptyfd and fdout. */
636 session_pty_cleanup(s);
637}
638
639/*
640 * Sets the value of the given variable in the environment. If the variable
641 * already exists, its value is overriden.
642 */
643void
644child_set_env(char ***envp, unsigned int *envsizep, const char *name,
645 const char *value)
646{
647 unsigned int i, namelen;
648 char **env;
649
650 /*
651 * Find the slot where the value should be stored. If the variable
652 * already exists, we reuse the slot; otherwise we append a new slot
653 * at the end of the array, expanding if necessary.
654 */
655 env = *envp;
656 namelen = strlen(name);
657 for (i = 0; env[i]; i++)
658 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
659 break;
660 if (env[i]) {
661 /* Reuse the slot. */
662 xfree(env[i]);
663 } else {
664 /* New variable. Expand if necessary. */
665 if (i >= (*envsizep) - 1) {
666 (*envsizep) += 50;
667 env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *));
668 }
669 /* Need to set the NULL pointer at end of array beyond the new slot. */
670 env[i + 1] = NULL;
671 }
672
673 /* Allocate space and format the variable in the appropriate slot. */
674 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
675 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
676}
677
678/*
679 * Reads environment variables from the given file and adds/overrides them
680 * into the environment. If the file does not exist, this does nothing.
681 * Otherwise, it must consist of empty lines, comments (line starts with '#')
682 * and assignments of the form name=value. No other forms are allowed.
683 */
684void
685read_environment_file(char ***env, unsigned int *envsize,
686 const char *filename)
687{
688 FILE *f;
689 char buf[4096];
690 char *cp, *value;
691
692 f = fopen(filename, "r");
693 if (!f)
694 return;
695
696 while (fgets(buf, sizeof(buf), f)) {
697 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
698 ;
699 if (!*cp || *cp == '#' || *cp == '\n')
700 continue;
701 if (strchr(cp, '\n'))
702 *strchr(cp, '\n') = '\0';
703 value = strchr(cp, '=');
704 if (value == NULL) {
705 fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf);
706 continue;
707 }
708 /* Replace the equals sign by nul, and advance value to the value string. */
709 *value = '\0';
710 value++;
711 child_set_env(env, envsize, cp, value);
712 }
713 fclose(f);
714}
715
716#ifdef USE_PAM
717/*
718 * Sets any environment variables which have been specified by PAM
719 */
720void do_pam_environment(char ***env, int *envsize)
721{
722 char *equals, var_name[512], var_val[512];
723 char **pam_env;
724 int i;
725
726 if ((pam_env = fetch_pam_environment()) == NULL)
727 return;
728
729 for(i = 0; pam_env[i] != NULL; i++) {
730 if ((equals = strstr(pam_env[i], "=")) == NULL)
731 continue;
732
733 if (strlen(pam_env[i]) < (sizeof(var_name) - 1)) {
734 memset(var_name, '\0', sizeof(var_name));
735 memset(var_val, '\0', sizeof(var_val));
736
737 strncpy(var_name, pam_env[i], equals - pam_env[i]);
738 strcpy(var_val, equals + 1);
739
740 debug("PAM environment: %s=%s", var_name, var_val);
741
742 child_set_env(env, envsize, var_name, var_val);
743 }
744 }
745}
746#endif /* USE_PAM */
747
748/*
749 * Performs common processing for the child, such as setting up the
750 * environment, closing extra file descriptors, setting the user and group
751 * ids, and executing the command or shell.
752 */
753void
754do_child(const char *command, struct passwd * pw, const char *term,
755 const char *display, const char *auth_proto,
756 const char *auth_data, const char *ttyname)
757{
758 const char *shell, *cp = NULL;
759 char buf[256];
760 FILE *f;
761 unsigned int envsize, i;
762 char **env;
763 extern char **environ;
764 struct stat st;
765 char *argv[10];
766
767#ifndef USE_PAM /* pam_nologin handles this */
768 f = fopen("/etc/nologin", "r");
769 if (f) {
770 /* /etc/nologin exists. Print its contents and exit. */
771 while (fgets(buf, sizeof(buf), f))
772 fputs(buf, stderr);
773 fclose(f);
774 if (pw->pw_uid != 0)
775 exit(254);
776 }
777#endif /* USE_PAM */
778
779 /* Set login name in the kernel. */
780 if (setlogin(pw->pw_name) < 0)
781 error("setlogin failed: %s", strerror(errno));
782
783 /* Set uid, gid, and groups. */
784 /* Login(1) does this as well, and it needs uid 0 for the "-h"
785 switch, so we let login(1) to this for us. */
786 if (!options.use_login) {
787 if (getuid() == 0 || geteuid() == 0) {
788 if (setgid(pw->pw_gid) < 0) {
789 perror("setgid");
790 exit(1);
791 }
792 /* Initialize the group list. */
793 if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
794 perror("initgroups");
795 exit(1);
796 }
797 endgrent();
798
799 /* Permanently switch to the desired uid. */
800 permanently_set_uid(pw->pw_uid);
801 }
802 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
803 fatal("Failed to set uids to %d.", (int) pw->pw_uid);
804 }
805 /*
806 * Get the shell from the password data. An empty shell field is
807 * legal, and means /bin/sh.
808 */
809 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
810
811#ifdef AFS
812 /* Try to get AFS tokens for the local cell. */
813 if (k_hasafs()) {
814 char cell[64];
815
816 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
817 krb_afslog(cell, 0);
818
819 krb_afslog(0, 0);
820 }
821#endif /* AFS */
822
823 /* Initialize the environment. */
824 envsize = 100;
825 env = xmalloc(envsize * sizeof(char *));
826 env[0] = NULL;
827
828 if (!options.use_login) {
829 /* Set basic environment. */
830 child_set_env(&env, &envsize, "USER", pw->pw_name);
831 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
832 child_set_env(&env, &envsize, "HOME", pw->pw_dir);
833 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
834
835 snprintf(buf, sizeof buf, "%.200s/%.50s",
836 _PATH_MAILDIR, pw->pw_name);
837 child_set_env(&env, &envsize, "MAIL", buf);
838
839 /* Normal systems set SHELL by default. */
840 child_set_env(&env, &envsize, "SHELL", shell);
841 }
842 if (getenv("TZ"))
843 child_set_env(&env, &envsize, "TZ", getenv("TZ"));
844
845 /* Set custom environment options from RSA authentication. */
846 while (custom_environment) {
847 struct envstring *ce = custom_environment;
848 char *s = ce->s;
849 int i;
850 for (i = 0; s[i] != '=' && s[i]; i++);
851 if (s[i] == '=') {
852 s[i] = 0;
853 child_set_env(&env, &envsize, s, s + i + 1);
854 }
855 custom_environment = ce->next;
856 xfree(ce->s);
857 xfree(ce);
858 }
859
860 snprintf(buf, sizeof buf, "%.50s %d %d",
861 get_remote_ipaddr(), get_remote_port(), get_local_port());
862 child_set_env(&env, &envsize, "SSH_CLIENT", buf);
863
864 if (ttyname)
865 child_set_env(&env, &envsize, "SSH_TTY", ttyname);
866 if (term)
867 child_set_env(&env, &envsize, "TERM", term);
868 if (display)
869 child_set_env(&env, &envsize, "DISPLAY", display);
870
871#ifdef _AIX
872 {
873 char *authstate,*krb5cc;
874
875 if ((authstate = getenv("AUTHSTATE")) != NULL)
876 child_set_env(&env,&envsize,"AUTHSTATE",authstate);
877
878 if ((krb5cc = getenv("KRB5CCNAME")) != NULL)
879 child_set_env(&env,&envsize,"KRB5CCNAME",krb5cc);
880 }
881#endif
882
883#ifdef KRB4
884 {
885 extern char *ticket;
886
887 if (ticket)
888 child_set_env(&env, &envsize, "KRBTKFILE", ticket);
889 }
890#endif /* KRB4 */
891
892#ifdef USE_PAM
893 /* Pull in any environment variables that may have been set by PAM. */
894 do_pam_environment(&env, &envsize);
895#endif /* USE_PAM */
896
897 read_environment_file(&env,&envsize,"/etc/environment");
898
899 if (xauthfile)
900 child_set_env(&env, &envsize, "XAUTHORITY", xauthfile);
901 if (auth_get_socket_name() != NULL)
902 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
903 auth_get_socket_name());
904
905 /* read $HOME/.ssh/environment. */
906 if (!options.use_login) {
907 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir);
908 read_environment_file(&env, &envsize, buf);
909 }
910 if (debug_flag) {
911 /* dump the environment */
912 fprintf(stderr, "Environment:\n");
913 for (i = 0; env[i]; i++)
914 fprintf(stderr, " %.200s\n", env[i]);
915 }
916 /*
917 * Close the connection descriptors; note that this is the child, and
918 * the server will still have the socket open, and it is important
919 * that we do not shutdown it. Note that the descriptors cannot be
920 * closed before building the environment, as we call
921 * get_remote_ipaddr there.
922 */
923 if (packet_get_connection_in() == packet_get_connection_out())
924 close(packet_get_connection_in());
925 else {
926 close(packet_get_connection_in());
927 close(packet_get_connection_out());
928 }
929 /*
930 * Close all descriptors related to channels. They will still remain
931 * open in the parent.
932 */
933 /* XXX better use close-on-exec? -markus */
934 channel_close_all();
935
936 /*
937 * Close any extra file descriptors. Note that there may still be
938 * descriptors left by system functions. They will be closed later.
939 */
940 endpwent();
941
942 /*
943 * Close any extra open file descriptors so that we don\'t have them
944 * hanging around in clients. Note that we want to do this after
945 * initgroups, because at least on Solaris 2.3 it leaves file
946 * descriptors open.
947 */
948 for (i = 3; i < 64; i++)
949 close(i);
950
951 /* Change current directory to the user\'s home directory. */
952 if (chdir(pw->pw_dir) < 0)
953 fprintf(stderr, "Could not chdir to home directory %s: %s\n",
954 pw->pw_dir, strerror(errno));
955
956 /*
957 * Must take new environment into use so that .ssh/rc, /etc/sshrc and
958 * xauth are run in the proper environment.
959 */
960 environ = env;
961
962 /*
963 * Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first
964 * in this order).
965 */
966 if (!options.use_login) {
967 if (stat(SSH_USER_RC, &st) >= 0) {
968 if (debug_flag)
969 fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC);
970
971 f = popen("/bin/sh " SSH_USER_RC, "w");
972 if (f) {
973 if (auth_proto != NULL && auth_data != NULL)
974 fprintf(f, "%s %s\n", auth_proto, auth_data);
975 pclose(f);
976 } else
977 fprintf(stderr, "Could not run %s\n", SSH_USER_RC);
978 } else if (stat(SSH_SYSTEM_RC, &st) >= 0) {
979 if (debug_flag)
980 fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC);
981
982 f = popen("/bin/sh " SSH_SYSTEM_RC, "w");
983 if (f) {
984 if (auth_proto != NULL && auth_data != NULL)
985 fprintf(f, "%s %s\n", auth_proto, auth_data);
986 pclose(f);
987 } else
988 fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC);
989 }
990#ifdef XAUTH_PATH
991 else {
992 /* Add authority data to .Xauthority if appropriate. */
993 if (auth_proto != NULL && auth_data != NULL) {
994 if (debug_flag)
995 fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n",
996 XAUTH_PATH, display, auth_proto, auth_data);
997
998 f = popen(XAUTH_PATH " -q -", "w");
999 if (f) {
1000 fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data);
1001 pclose(f);
1002 } else
1003 fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH);
1004 }
1005 }
1006#endif /* XAUTH_PATH */
1007
1008 /* Get the last component of the shell name. */
1009 cp = strrchr(shell, '/');
1010 if (cp)
1011 cp++;
1012 else
1013 cp = shell;
1014 }
1015 /*
1016 * If we have no command, execute the shell. In this case, the shell
1017 * name to be passed in argv[0] is preceded by '-' to indicate that
1018 * this is a login shell.
1019 */
1020 if (!command) {
1021 if (!options.use_login) {
1022 char buf[256];
1023
1024 /*
1025 * Check for mail if we have a tty and it was enabled
1026 * in server options.
1027 */
1028 if (ttyname && options.check_mail) {
1029 char *mailbox;
1030 struct stat mailstat;
1031 mailbox = getenv("MAIL");
1032 if (mailbox != NULL) {
1033 if (stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0)
1034 printf("No mail.\n");
1035 else if (mailstat.st_mtime < mailstat.st_atime)
1036 printf("You have mail.\n");
1037 else
1038 printf("You have new mail.\n");
1039 }
1040 }
1041 /* Start the shell. Set initial character to '-'. */
1042 buf[0] = '-';
1043 strncpy(buf + 1, cp, sizeof(buf) - 1);
1044 buf[sizeof(buf) - 1] = 0;
1045
1046 /* Execute the shell. */
1047 argv[0] = buf;
1048 argv[1] = NULL;
1049 execve(shell, argv, env);
1050
1051 /* Executing the shell failed. */
1052 perror(shell);
1053 exit(1);
1054
1055 } else {
1056 /* Launch login(1). */
1057
1058 execl("/usr/bin/login", "login", "-h", get_remote_ipaddr(),
1059 "-p", "-f", "--", pw->pw_name, NULL);
1060
1061 /* Login couldn't be executed, die. */
1062
1063 perror("login");
1064 exit(1);
1065 }
1066 }
1067 /*
1068 * Execute the command using the user's shell. This uses the -c
1069 * option to execute the command.
1070 */
1071 argv[0] = (char *) cp;
1072 argv[1] = "-c";
1073 argv[2] = (char *) command;
1074 argv[3] = NULL;
1075 execve(shell, argv, env);
1076 perror(shell);
1077 exit(1);
1078}
1079
1080Session *
1081session_new(void)
1082{
1083 int i;
1084 static int did_init = 0;
1085 if (!did_init) {
1086 debug("session_new: init");
1087 for(i = 0; i < MAX_SESSIONS; i++) {
1088 sessions[i].used = 0;
1089 sessions[i].self = i;
1090 }
1091 did_init = 1;
1092 }
1093 for(i = 0; i < MAX_SESSIONS; i++) {
1094 Session *s = &sessions[i];
1095 if (! s->used) {
1096 s->pid = 0;
1097 s->chanid = -1;
1098 s->ptyfd = -1;
1099 s->ttyfd = -1;
1100 s->term = NULL;
1101 s->pw = NULL;
1102 s->display = NULL;
1103 s->screen = 0;
1104 s->auth_data = NULL;
1105 s->auth_proto = NULL;
1106 s->used = 1;
1107 debug("session_new: session %d", i);
1108 return s;
1109 }
1110 }
1111 return NULL;
1112}
1113
1114void
1115session_dump(void)
1116{
1117 int i;
1118 for(i = 0; i < MAX_SESSIONS; i++) {
1119 Session *s = &sessions[i];
1120 debug("dump: used %d session %d %p channel %d pid %d",
1121 s->used,
1122 s->self,
1123 s,
1124 s->chanid,
1125 s->pid);
1126 }
1127}
1128
1129void
1130session_pty_cleanup(Session *s)
1131{
1132 if (s == NULL || s->ttyfd == -1)
1133 return;
1134
1135 debug("session_pty_cleanup: session %i release %s", s->self, s->tty);
1136
1137 /* Cancel the cleanup function. */
1138 fatal_remove_cleanup(pty_cleanup_proc, (void *)s);
1139
1140 /* Record that the user has logged out. */
1141 record_logout(s->pid, s->tty);
1142
1143 /* Release the pseudo-tty. */
1144 pty_release(s->tty);
1145
1146 /*
1147 * Close the server side of the socket pairs. We must do this after
1148 * the pty cleanup, so that another process doesn't get this pty
1149 * while we're still cleaning up.
1150 */
1151 if (close(s->ptymaster) < 0)
1152 error("close(s->ptymaster): %s", strerror(errno));
1153}