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8efc0c15 | 1 | /* |
2 | ||
3 | sshd.c | |
4 | ||
5 | Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | ||
7 | Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
8 | All rights reserved | |
9 | ||
10 | Created: Fri Mar 17 17:09:28 1995 ylo | |
11 | ||
12 | This program is the ssh daemon. It listens for connections from clients, and | |
13 | performs authentication, executes use commands or shell, and forwards | |
14 | information to/from the application to the user client over an encrypted | |
15 | connection. This can also handle forwarding of X11, TCP/IP, and authentication | |
16 | agent connections. | |
17 | ||
18 | */ | |
19 | ||
20 | #include "includes.h" | |
21 | RCSID("$Id$"); | |
22 | ||
23 | #include "xmalloc.h" | |
24 | #include "rsa.h" | |
25 | #include "ssh.h" | |
26 | #include "pty.h" | |
27 | #include "packet.h" | |
28 | #include "buffer.h" | |
29 | #include "cipher.h" | |
30 | #include "mpaux.h" | |
31 | #include "servconf.h" | |
32 | #include "uidswap.h" | |
33 | #include "compat.h" | |
34 | ||
35 | #ifdef LIBWRAP | |
36 | #include <tcpd.h> | |
37 | #include <syslog.h> | |
38 | int allow_severity = LOG_INFO; | |
39 | int deny_severity = LOG_WARNING; | |
40 | #endif /* LIBWRAP */ | |
41 | ||
42 | #ifndef O_NOCTTY | |
43 | #define O_NOCTTY 0 | |
44 | #endif | |
45 | ||
8efc0c15 | 46 | /* Local Xauthority file. */ |
6a17f9c2 | 47 | static char *xauthfile = NULL; |
8efc0c15 | 48 | |
49 | /* Server configuration options. */ | |
50 | ServerOptions options; | |
51 | ||
52 | /* Name of the server configuration file. */ | |
53 | char *config_file_name = SERVER_CONFIG_FILE; | |
54 | ||
55 | /* Debug mode flag. This can be set on the command line. If debug | |
56 | mode is enabled, extra debugging output will be sent to the system | |
57 | log, the daemon will not go to background, and will exit after processing | |
58 | the first connection. */ | |
59 | int debug_flag = 0; | |
60 | ||
61 | /* Flag indicating that the daemon is being started from inetd. */ | |
62 | int inetd_flag = 0; | |
63 | ||
6a17f9c2 | 64 | /* debug goes to stderr unless inetd_flag is set */ |
65 | int log_stderr = 0; | |
66 | ||
8efc0c15 | 67 | /* argv[0] without path. */ |
68 | char *av0; | |
69 | ||
70 | /* Saved arguments to main(). */ | |
71 | char **saved_argv; | |
72 | ||
73 | /* This is set to the socket that the server is listening; this is used in | |
74 | the SIGHUP signal handler. */ | |
75 | int listen_sock; | |
76 | ||
77 | /* Flags set in auth-rsa from authorized_keys flags. These are set in | |
78 | auth-rsa.c. */ | |
79 | int no_port_forwarding_flag = 0; | |
80 | int no_agent_forwarding_flag = 0; | |
81 | int no_x11_forwarding_flag = 0; | |
82 | int no_pty_flag = 0; | |
83 | char *forced_command = NULL; /* RSA authentication "command=" option. */ | |
84 | struct envstring *custom_environment = NULL; | |
85 | /* RSA authentication "environment=" options. */ | |
86 | ||
87 | /* Session id for the current session. */ | |
88 | unsigned char session_id[16]; | |
89 | ||
90 | /* Any really sensitive data in the application is contained in this structure. | |
91 | The idea is that this structure could be locked into memory so that the | |
92 | pages do not get written into swap. However, there are some problems. | |
93 | The private key contains BIGNUMs, and we do not (in principle) have | |
94 | access to the internals of them, and locking just the structure is not | |
95 | very useful. Currently, memory locking is not implemented. */ | |
96 | struct | |
97 | { | |
98 | /* Private part of server key. */ | |
99 | RSA *private_key; | |
100 | ||
101 | /* Private part of host key. */ | |
102 | RSA *host_key; | |
103 | } sensitive_data; | |
104 | ||
105 | /* Flag indicating whether the current session key has been used. This flag | |
106 | is set whenever the key is used, and cleared when the key is regenerated. */ | |
107 | int key_used = 0; | |
108 | ||
109 | /* This is set to true when SIGHUP is received. */ | |
110 | int received_sighup = 0; | |
111 | ||
112 | /* Public side of the server key. This value is regenerated regularly with | |
113 | the private key. */ | |
114 | RSA *public_key; | |
115 | ||
116 | /* Prototypes for various functions defined later in this file. */ | |
117 | void do_connection(int privileged_port); | |
118 | void do_authentication(char *user, int privileged_port); | |
0183ea1c | 119 | void eat_packets_and_disconnect(const char *user); |
8efc0c15 | 120 | void do_authenticated(struct passwd *pw); |
121 | void do_exec_pty(const char *command, int ptyfd, int ttyfd, | |
122 | const char *ttyname, struct passwd *pw, const char *term, | |
123 | const char *display, const char *auth_proto, | |
124 | const char *auth_data); | |
125 | void do_exec_no_pty(const char *command, struct passwd *pw, | |
126 | const char *display, const char *auth_proto, | |
127 | const char *auth_data); | |
128 | void do_child(const char *command, struct passwd *pw, const char *term, | |
129 | const char *display, const char *auth_proto, | |
130 | const char *auth_data, const char *ttyname); | |
5aecb327 | 131 | #ifdef HAVE_LIBPAM |
8efc0c15 | 132 | static int pamconv(int num_msg, const struct pam_message **msg, |
133 | struct pam_response **resp, void *appdata_ptr); | |
0183ea1c | 134 | void do_pam_account_and_session(const char *username, const char *password, |
d813bc69 | 135 | const char *remote_user, const char *remote_host); |
136 | void pam_cleanup_proc(void *context); | |
8efc0c15 | 137 | |
138 | static struct pam_conv conv = { | |
139 | pamconv, | |
140 | NULL | |
141 | }; | |
d813bc69 | 142 | struct pam_handle_t *pamh = NULL; |
143 | const char *pampasswd = NULL; | |
e1a9c08d | 144 | char *pamconv_msg = NULL; |
8efc0c15 | 145 | |
146 | static int pamconv(int num_msg, const struct pam_message **msg, | |
147 | struct pam_response **resp, void *appdata_ptr) | |
148 | { | |
149 | int count = 0; | |
8efc0c15 | 150 | struct pam_response *reply = NULL; |
8efc0c15 | 151 | |
d813bc69 | 152 | /* PAM will free this later */ |
153 | reply = malloc(num_msg * sizeof(*reply)); | |
154 | if (reply == NULL) | |
155 | return PAM_CONV_ERR; | |
156 | ||
8efc0c15 | 157 | for(count = 0; count < num_msg; count++) |
158 | { | |
159 | switch (msg[count]->msg_style) | |
160 | { | |
8efc0c15 | 161 | case PAM_PROMPT_ECHO_OFF: |
0183ea1c | 162 | if (pampasswd == NULL) |
d813bc69 | 163 | { |
8efc0c15 | 164 | free(reply); |
d813bc69 | 165 | return PAM_CONV_ERR; |
166 | } | |
167 | reply[count].resp_retcode = PAM_SUCCESS; | |
168 | reply[count].resp = xstrdup(pampasswd); | |
169 | break; | |
170 | ||
171 | case PAM_TEXT_INFO: | |
172 | reply[count].resp_retcode = PAM_SUCCESS; | |
173 | reply[count].resp = xstrdup(""); | |
e1a9c08d | 174 | |
175 | if (msg[count]->msg == NULL) break; | |
176 | debug("Adding PAM message: %s", msg[count]->msg); | |
177 | if (pamconv_msg == NULL) | |
178 | { | |
179 | pamconv_msg = malloc(strlen(msg[count]->msg) + 2); | |
180 | ||
181 | if (pamconv_msg == NULL) | |
182 | return PAM_CONV_ERR; | |
183 | ||
184 | strncpy(pamconv_msg, msg[count]->msg, strlen(msg[count]->msg)); | |
185 | pamconv_msg[strlen(msg[count]->msg)] = '\n'; | |
186 | pamconv_msg[strlen(msg[count]->msg) + 1] = '\0'; | |
187 | } else | |
188 | { | |
189 | pamconv_msg = realloc(pamconv_msg, strlen(pamconv_msg) + strlen(msg[count]->msg) + 2); | |
190 | strncat(pamconv_msg, msg[count]->msg, strlen(msg[count]->msg)); | |
191 | pamconv_msg[strlen(pamconv_msg)] = '\n'; | |
192 | pamconv_msg[strlen(pamconv_msg) + 1] = '\0'; | |
193 | } | |
d813bc69 | 194 | break; |
8efc0c15 | 195 | |
d813bc69 | 196 | case PAM_PROMPT_ECHO_ON: |
197 | case PAM_ERROR_MSG: | |
198 | default: | |
199 | free(reply); | |
200 | return PAM_CONV_ERR; | |
201 | } | |
8efc0c15 | 202 | } |
203 | ||
d813bc69 | 204 | *resp = reply; |
8efc0c15 | 205 | |
206 | return PAM_SUCCESS; | |
207 | } | |
208 | ||
209 | void pam_cleanup_proc(void *context) | |
210 | { | |
549b3eed | 211 | int pam_retval; |
d813bc69 | 212 | |
213 | if (pamh != NULL) | |
214 | { | |
549b3eed | 215 | pam_retval = pam_close_session((pam_handle_t *)pamh, 0); |
216 | if (pam_retval != PAM_SUCCESS) | |
217 | { | |
218 | log("Cannot close PAM session: %.200s", | |
219 | pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
220 | } | |
221 | ||
222 | pam_retval = pam_end((pam_handle_t *)pamh, pam_retval); | |
223 | if (pam_retval != PAM_SUCCESS) | |
224 | { | |
225 | log("Cannot release PAM authentication: %.200s", | |
226 | pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
227 | } | |
d813bc69 | 228 | } |
229 | } | |
230 | ||
0183ea1c | 231 | void do_pam_account_and_session(const char *username, const char *password, const char *remote_user, const char *remote_host) |
d813bc69 | 232 | { |
549b3eed | 233 | int pam_retval; |
234 | ||
235 | if (remote_host != NULL) | |
d813bc69 | 236 | { |
549b3eed | 237 | debug("PAM setting rhost to \"%.200s\"", remote_host); |
238 | pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RHOST, remote_host); | |
239 | if (pam_retval != PAM_SUCCESS) | |
240 | { | |
241 | log("PAM set rhost failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
242 | eat_packets_and_disconnect(username); | |
243 | } | |
0183ea1c | 244 | } |
549b3eed | 245 | |
246 | if (remote_user != NULL) | |
0183ea1c | 247 | { |
549b3eed | 248 | debug("PAM setting ruser to \"%.200s\"", remote_user); |
249 | pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RUSER, remote_user); | |
250 | if (pam_retval != PAM_SUCCESS) | |
251 | { | |
252 | log("PAM set ruser failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
253 | eat_packets_and_disconnect(username); | |
254 | } | |
0183ea1c | 255 | } |
549b3eed | 256 | |
257 | pam_retval = pam_acct_mgmt((pam_handle_t *)pamh, 0); | |
258 | if (pam_retval != PAM_SUCCESS) | |
0183ea1c | 259 | { |
549b3eed | 260 | log("PAM rejected by account configuration: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); |
0183ea1c | 261 | eat_packets_and_disconnect(username); |
262 | } | |
d813bc69 | 263 | |
549b3eed | 264 | pam_retval = pam_open_session((pam_handle_t *)pamh, 0); |
265 | if (pam_retval != PAM_SUCCESS) | |
d813bc69 | 266 | { |
549b3eed | 267 | log("PAM session setup failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); |
0183ea1c | 268 | eat_packets_and_disconnect(username); |
d813bc69 | 269 | } |
8efc0c15 | 270 | } |
5aecb327 | 271 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 272 | |
273 | /* Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
274 | the effect is to reread the configuration file (and to regenerate | |
275 | the server key). */ | |
276 | ||
277 | void sighup_handler(int sig) | |
278 | { | |
279 | received_sighup = 1; | |
280 | signal(SIGHUP, sighup_handler); | |
281 | } | |
282 | ||
283 | /* Called from the main program after receiving SIGHUP. Restarts the | |
284 | server. */ | |
285 | ||
286 | void sighup_restart() | |
287 | { | |
288 | log("Received SIGHUP; restarting."); | |
289 | close(listen_sock); | |
290 | execv(saved_argv[0], saved_argv); | |
291 | log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); | |
292 | exit(1); | |
293 | } | |
294 | ||
295 | /* Generic signal handler for terminating signals in the master daemon. | |
296 | These close the listen socket; not closing it seems to cause "Address | |
297 | already in use" problems on some machines, which is inconvenient. */ | |
298 | ||
299 | void sigterm_handler(int sig) | |
300 | { | |
301 | log("Received signal %d; terminating.", sig); | |
302 | close(listen_sock); | |
303 | exit(255); | |
304 | } | |
305 | ||
306 | /* SIGCHLD handler. This is called whenever a child dies. This will then | |
307 | reap any zombies left by exited c. */ | |
308 | ||
309 | void main_sigchld_handler(int sig) | |
310 | { | |
311 | int save_errno = errno; | |
312 | int status; | |
313 | wait(&status); | |
314 | signal(SIGCHLD, main_sigchld_handler); | |
315 | errno = save_errno; | |
316 | } | |
317 | ||
318 | /* Signal handler for the alarm after the login grace period has expired. */ | |
319 | ||
320 | void grace_alarm_handler(int sig) | |
321 | { | |
322 | /* Close the connection. */ | |
323 | packet_close(); | |
324 | ||
325 | /* Log error and exit. */ | |
326 | fatal("Timeout before authentication."); | |
327 | } | |
328 | ||
329 | /* Signal handler for the key regeneration alarm. Note that this | |
330 | alarm only occurs in the daemon waiting for connections, and it does not | |
331 | do anything with the private key or random state before forking. Thus there | |
332 | should be no concurrency control/asynchronous execution problems. */ | |
333 | ||
334 | void key_regeneration_alarm(int sig) | |
335 | { | |
336 | int save_errno = errno; | |
337 | ||
338 | /* Check if we should generate a new key. */ | |
339 | if (key_used) | |
340 | { | |
341 | /* This should really be done in the background. */ | |
342 | log("Generating new %d bit RSA key.", options.server_key_bits); | |
343 | ||
344 | if (sensitive_data.private_key != NULL) | |
345 | RSA_free(sensitive_data.private_key); | |
346 | sensitive_data.private_key = RSA_new(); | |
347 | ||
348 | if (public_key != NULL) | |
349 | RSA_free(public_key); | |
350 | public_key = RSA_new(); | |
351 | ||
352 | rsa_generate_key(sensitive_data.private_key, public_key, | |
353 | options.server_key_bits); | |
354 | arc4random_stir(); | |
355 | key_used = 0; | |
356 | log("RSA key generation complete."); | |
357 | } | |
358 | ||
359 | /* Reschedule the alarm. */ | |
360 | signal(SIGALRM, key_regeneration_alarm); | |
361 | alarm(options.key_regeneration_time); | |
362 | errno = save_errno; | |
363 | } | |
364 | ||
365 | /* Main program for the daemon. */ | |
366 | ||
367 | int | |
368 | main(int ac, char **av) | |
369 | { | |
370 | extern char *optarg; | |
371 | extern int optind; | |
372 | int opt, aux, sock_in, sock_out, newsock, i, pid, on = 1; | |
373 | int remote_major, remote_minor; | |
374 | int silentrsa = 0; | |
375 | struct sockaddr_in sin; | |
376 | char buf[100]; /* Must not be larger than remote_version. */ | |
377 | char remote_version[100]; /* Must be at least as big as buf. */ | |
378 | char *comment; | |
379 | FILE *f; | |
380 | struct linger linger; | |
381 | ||
382 | /* Save argv[0]. */ | |
383 | saved_argv = av; | |
384 | if (strchr(av[0], '/')) | |
385 | av0 = strrchr(av[0], '/') + 1; | |
386 | else | |
387 | av0 = av[0]; | |
388 | ||
389 | /* Initialize configuration options to their default values. */ | |
390 | initialize_server_options(&options); | |
391 | ||
392 | /* Parse command-line arguments. */ | |
393 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:diqQ")) != EOF) | |
394 | { | |
395 | switch (opt) | |
396 | { | |
397 | case 'f': | |
398 | config_file_name = optarg; | |
399 | break; | |
400 | case 'd': | |
401 | debug_flag = 1; | |
6a17f9c2 | 402 | options.log_level = SYSLOG_LEVEL_DEBUG; |
8efc0c15 | 403 | break; |
404 | case 'i': | |
405 | inetd_flag = 1; | |
406 | break; | |
407 | case 'Q': | |
408 | silentrsa = 1; | |
409 | break; | |
410 | case 'q': | |
6a17f9c2 | 411 | options.log_level = SYSLOG_LEVEL_QUIET; |
8efc0c15 | 412 | break; |
413 | case 'b': | |
414 | options.server_key_bits = atoi(optarg); | |
415 | break; | |
416 | case 'p': | |
417 | options.port = atoi(optarg); | |
418 | break; | |
419 | case 'g': | |
420 | options.login_grace_time = atoi(optarg); | |
421 | break; | |
422 | case 'k': | |
423 | options.key_regeneration_time = atoi(optarg); | |
424 | break; | |
425 | case 'h': | |
426 | options.host_key_file = optarg; | |
427 | break; | |
428 | case '?': | |
429 | default: | |
430 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
431 | fprintf(stderr, "Usage: %s [options]\n", av0); | |
432 | fprintf(stderr, "Options:\n"); | |
433 | fprintf(stderr, " -f file Configuration file (default %s/sshd_config)\n", ETCDIR); | |
434 | fprintf(stderr, " -d Debugging mode\n"); | |
435 | fprintf(stderr, " -i Started from inetd\n"); | |
436 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
437 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
438 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
439 | fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); | |
440 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
441 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
442 | HOST_KEY_FILE); | |
443 | exit(1); | |
444 | } | |
445 | } | |
446 | ||
447 | /* check if RSA support exists */ | |
448 | if (rsa_alive() == 0) { | |
449 | if (silentrsa == 0) | |
450 | printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n"); | |
451 | log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)"); | |
452 | exit(1); | |
453 | } | |
454 | ||
455 | /* Read server configuration options from the configuration file. */ | |
456 | read_server_config(&options, config_file_name); | |
457 | ||
458 | /* Fill in default values for those options not explicitly set. */ | |
459 | fill_default_server_options(&options); | |
460 | ||
461 | /* Check certain values for sanity. */ | |
462 | if (options.server_key_bits < 512 || | |
463 | options.server_key_bits > 32768) | |
464 | { | |
465 | fprintf(stderr, "Bad server key size.\n"); | |
466 | exit(1); | |
467 | } | |
468 | if (options.port < 1 || options.port > 65535) | |
469 | { | |
470 | fprintf(stderr, "Bad port number.\n"); | |
471 | exit(1); | |
472 | } | |
473 | ||
474 | /* Check that there are no remaining arguments. */ | |
475 | if (optind < ac) | |
476 | { | |
477 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
478 | exit(1); | |
479 | } | |
480 | ||
481 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
6a17f9c2 | 482 | |
483 | if (debug_flag && !inetd_flag) | |
484 | log_stderr = 1; | |
485 | ||
486 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
8efc0c15 | 487 | |
488 | debug("sshd version %.100s", SSH_VERSION); | |
489 | ||
490 | sensitive_data.host_key = RSA_new(); | |
491 | /* Load the host key. It must have empty passphrase. */ | |
492 | if (!load_private_key(options.host_key_file, "", | |
493 | sensitive_data.host_key, &comment)) | |
494 | { | |
495 | if (debug_flag) | |
496 | fprintf(stderr, "Could not load host key: %s: %s\n", | |
497 | options.host_key_file, strerror(errno)); | |
498 | else | |
499 | { | |
500 | int err = errno; | |
6a17f9c2 | 501 | /* force logging */ |
502 | log_init(av0, SYSLOG_LEVEL_DEBUG, options.log_facility, log_stderr); | |
8efc0c15 | 503 | error("Could not load host key: %.200s: %.100s", |
504 | options.host_key_file, strerror(err)); | |
505 | } | |
506 | exit(1); | |
507 | } | |
508 | xfree(comment); | |
509 | ||
510 | /* If not in debugging mode, and not started from inetd, disconnect from | |
511 | the controlling terminal, and fork. The original process exits. */ | |
512 | if (!debug_flag && !inetd_flag) | |
513 | { | |
514 | #ifdef TIOCNOTTY | |
515 | int fd; | |
516 | #endif /* TIOCNOTTY */ | |
517 | if (daemon(0, 0) < 0) | |
518 | fatal("daemon() failed: %.200s", strerror(errno)); | |
519 | ||
520 | /* Disconnect from the controlling tty. */ | |
521 | #ifdef TIOCNOTTY | |
522 | fd = open("/dev/tty", O_RDWR|O_NOCTTY); | |
523 | if (fd >= 0) | |
524 | { | |
525 | (void)ioctl(fd, TIOCNOTTY, NULL); | |
526 | close(fd); | |
527 | } | |
528 | #endif /* TIOCNOTTY */ | |
529 | } | |
530 | ||
531 | /* Reinitialize the log (because of the fork above). */ | |
6a17f9c2 | 532 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 533 | |
534 | /* Check that server and host key lengths differ sufficiently. This is | |
535 | necessary to make double encryption work with rsaref. Oh, I hate | |
536 | software patents. I dont know if this can go? Niels */ | |
537 | if (options.server_key_bits > | |
538 | BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED && | |
539 | options.server_key_bits < | |
540 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) | |
541 | { | |
542 | options.server_key_bits = | |
543 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED; | |
544 | debug("Forcing server key to %d bits to make it differ from host key.", | |
545 | options.server_key_bits); | |
546 | } | |
547 | ||
548 | /* Do not display messages to stdout in RSA code. */ | |
549 | rsa_set_verbose(0); | |
550 | ||
551 | /* Initialize the random number generator. */ | |
552 | arc4random_stir(); | |
553 | ||
554 | /* Chdir to the root directory so that the current disk can be unmounted | |
555 | if desired. */ | |
556 | chdir("/"); | |
557 | ||
558 | /* Close connection cleanly after attack. */ | |
559 | cipher_attack_detected = packet_disconnect; | |
560 | ||
561 | /* Start listening for a socket, unless started from inetd. */ | |
562 | if (inetd_flag) | |
563 | { | |
564 | int s1, s2; | |
565 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
566 | s2 = dup(s1); | |
567 | sock_in = dup(0); | |
568 | sock_out = dup(1); | |
569 | /* We intentionally do not close the descriptors 0, 1, and 2 as our | |
570 | code for setting the descriptors won\'t work if ttyfd happens to | |
571 | be one of those. */ | |
572 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
573 | ||
574 | public_key = RSA_new(); | |
575 | sensitive_data.private_key = RSA_new(); | |
576 | /* Generate an rsa key. */ | |
577 | log("Generating %d bit RSA key.", options.server_key_bits); | |
578 | rsa_generate_key(sensitive_data.private_key, public_key, | |
579 | options.server_key_bits); | |
580 | arc4random_stir(); | |
581 | log("RSA key generation complete."); | |
582 | } | |
583 | else | |
584 | { | |
585 | /* Create socket for listening. */ | |
586 | listen_sock = socket(AF_INET, SOCK_STREAM, 0); | |
587 | if (listen_sock < 0) | |
588 | fatal("socket: %.100s", strerror(errno)); | |
589 | ||
590 | /* Set socket options. We try to make the port reusable and have it | |
591 | close as fast as possible without waiting in unnecessary wait states | |
592 | on close. */ | |
593 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, | |
594 | sizeof(on)); | |
595 | linger.l_onoff = 1; | |
596 | linger.l_linger = 5; | |
597 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, (void *)&linger, | |
598 | sizeof(linger)); | |
599 | ||
600 | /* Initialize the socket address. */ | |
601 | memset(&sin, 0, sizeof(sin)); | |
602 | sin.sin_family = AF_INET; | |
603 | sin.sin_addr = options.listen_addr; | |
604 | sin.sin_port = htons(options.port); | |
605 | ||
606 | /* Bind the socket to the desired port. */ | |
607 | if (bind(listen_sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) | |
608 | { | |
609 | error("bind: %.100s", strerror(errno)); | |
610 | shutdown(listen_sock, SHUT_RDWR); | |
611 | close(listen_sock); | |
612 | fatal("Bind to port %d failed.", options.port); | |
613 | } | |
614 | ||
615 | if (!debug_flag) | |
616 | { | |
617 | /* Record our pid in /etc/sshd_pid to make it easier to kill the | |
618 | correct sshd. We don\'t want to do this before the bind above | |
619 | because the bind will fail if there already is a daemon, and this | |
620 | will overwrite any old pid in the file. */ | |
621 | f = fopen(SSH_DAEMON_PID_FILE, "w"); | |
622 | if (f) | |
623 | { | |
624 | fprintf(f, "%u\n", (unsigned int)getpid()); | |
625 | fclose(f); | |
626 | } | |
627 | } | |
628 | ||
629 | /* Start listening on the port. */ | |
630 | log("Server listening on port %d.", options.port); | |
631 | if (listen(listen_sock, 5) < 0) | |
632 | fatal("listen: %.100s", strerror(errno)); | |
633 | ||
634 | public_key = RSA_new(); | |
635 | sensitive_data.private_key = RSA_new(); | |
636 | /* Generate an rsa key. */ | |
637 | log("Generating %d bit RSA key.", options.server_key_bits); | |
638 | rsa_generate_key(sensitive_data.private_key, public_key, | |
639 | options.server_key_bits); | |
640 | arc4random_stir(); | |
641 | log("RSA key generation complete."); | |
642 | ||
643 | /* Schedule server key regeneration alarm. */ | |
644 | signal(SIGALRM, key_regeneration_alarm); | |
645 | alarm(options.key_regeneration_time); | |
646 | ||
647 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
648 | signal(SIGHUP, sighup_handler); | |
649 | signal(SIGTERM, sigterm_handler); | |
650 | signal(SIGQUIT, sigterm_handler); | |
651 | ||
652 | /* Arrange SIGCHLD to be caught. */ | |
653 | signal(SIGCHLD, main_sigchld_handler); | |
654 | ||
655 | /* Stay listening for connections until the system crashes or the | |
656 | daemon is killed with a signal. */ | |
657 | for (;;) | |
658 | { | |
659 | if (received_sighup) | |
660 | sighup_restart(); | |
661 | /* Wait in accept until there is a connection. */ | |
662 | aux = sizeof(sin); | |
663 | newsock = accept(listen_sock, (struct sockaddr *)&sin, &aux); | |
664 | if (received_sighup) | |
665 | sighup_restart(); | |
666 | if (newsock < 0) | |
667 | { | |
668 | if (errno == EINTR) | |
669 | continue; | |
670 | error("accept: %.100s", strerror(errno)); | |
671 | continue; | |
672 | } | |
673 | ||
674 | /* Got connection. Fork a child to handle it, unless we are in | |
675 | debugging mode. */ | |
676 | if (debug_flag) | |
677 | { | |
678 | /* In debugging mode. Close the listening socket, and start | |
679 | processing the connection without forking. */ | |
680 | debug("Server will not fork when running in debugging mode."); | |
681 | close(listen_sock); | |
682 | sock_in = newsock; | |
683 | sock_out = newsock; | |
684 | pid = getpid(); | |
685 | break; | |
686 | } | |
687 | else | |
688 | { | |
689 | /* Normal production daemon. Fork, and have the child process | |
690 | the connection. The parent continues listening. */ | |
691 | if ((pid = fork()) == 0) | |
692 | { | |
693 | /* Child. Close the listening socket, and start using | |
694 | the accepted socket. Reinitialize logging (since our | |
695 | pid has changed). We break out of the loop to handle | |
696 | the connection. */ | |
697 | close(listen_sock); | |
698 | sock_in = newsock; | |
699 | sock_out = newsock; | |
6a17f9c2 | 700 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 701 | break; |
702 | } | |
703 | } | |
704 | ||
705 | /* Parent. Stay in the loop. */ | |
706 | if (pid < 0) | |
707 | error("fork: %.100s", strerror(errno)); | |
708 | else | |
709 | debug("Forked child %d.", pid); | |
710 | ||
711 | /* Mark that the key has been used (it was "given" to the child). */ | |
712 | key_used = 1; | |
713 | ||
714 | arc4random_stir(); | |
715 | ||
716 | /* Close the new socket (the child is now taking care of it). */ | |
717 | close(newsock); | |
718 | } | |
719 | } | |
720 | ||
721 | /* This is the child processing a new connection. */ | |
722 | ||
723 | /* Disable the key regeneration alarm. We will not regenerate the key | |
724 | since we are no longer in a position to give it to anyone. We will | |
725 | not restart on SIGHUP since it no longer makes sense. */ | |
726 | alarm(0); | |
727 | signal(SIGALRM, SIG_DFL); | |
728 | signal(SIGHUP, SIG_DFL); | |
729 | signal(SIGTERM, SIG_DFL); | |
730 | signal(SIGQUIT, SIG_DFL); | |
731 | signal(SIGCHLD, SIG_DFL); | |
732 | ||
733 | /* Set socket options for the connection. We want the socket to close | |
734 | as fast as possible without waiting for anything. If the connection | |
735 | is not a socket, these will do nothing. */ | |
736 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
737 | linger.l_onoff = 1; | |
738 | linger.l_linger = 5; | |
739 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); | |
740 | ||
741 | /* Register our connection. This turns encryption off because we do not | |
742 | have a key. */ | |
743 | packet_set_connection(sock_in, sock_out); | |
744 | ||
745 | /* Check whether logins are denied from this host. */ | |
746 | #ifdef LIBWRAP | |
747 | { | |
748 | struct request_info req; | |
749 | ||
750 | request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); | |
751 | fromhost(&req); | |
752 | ||
753 | if (!hosts_access(&req)) { | |
754 | close(sock_in); | |
755 | close(sock_out); | |
756 | refuse(&req); | |
757 | } | |
758 | log("Connection from %.500s port %d", | |
759 | eval_client(&req), get_remote_port()); | |
760 | } | |
761 | #else | |
762 | /* Log the connection. */ | |
763 | log("Connection from %.100s port %d", | |
764 | get_remote_ipaddr(), get_remote_port()); | |
765 | #endif /* LIBWRAP */ | |
766 | ||
767 | /* We don\'t want to listen forever unless the other side successfully | |
768 | authenticates itself. So we set up an alarm which is cleared after | |
769 | successful authentication. A limit of zero indicates no limit. | |
770 | Note that we don\'t set the alarm in debugging mode; it is just annoying | |
771 | to have the server exit just when you are about to discover the bug. */ | |
772 | signal(SIGALRM, grace_alarm_handler); | |
773 | if (!debug_flag) | |
774 | alarm(options.login_grace_time); | |
775 | ||
776 | /* Send our protocol version identification. */ | |
777 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
778 | PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION); | |
779 | if (write(sock_out, buf, strlen(buf)) != strlen(buf)) | |
780 | fatal("Could not write ident string."); | |
781 | ||
782 | /* Read other side\'s version identification. */ | |
783 | for (i = 0; i < sizeof(buf) - 1; i++) | |
784 | { | |
785 | if (read(sock_in, &buf[i], 1) != 1) | |
786 | fatal("Did not receive ident string."); | |
787 | if (buf[i] == '\r') | |
788 | { | |
789 | buf[i] = '\n'; | |
790 | buf[i + 1] = 0; | |
791 | break; | |
792 | } | |
793 | if (buf[i] == '\n') | |
794 | { | |
795 | /* buf[i] == '\n' */ | |
796 | buf[i + 1] = 0; | |
797 | break; | |
798 | } | |
799 | } | |
800 | buf[sizeof(buf) - 1] = 0; | |
801 | ||
802 | /* Check that the versions match. In future this might accept several | |
803 | versions and set appropriate flags to handle them. */ | |
804 | if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, | |
805 | remote_version) != 3) | |
806 | { | |
807 | const char *s = "Protocol mismatch.\n"; | |
808 | (void) write(sock_out, s, strlen(s)); | |
809 | close(sock_in); | |
810 | close(sock_out); | |
811 | fatal("Bad protocol version identification: %.100s", buf); | |
812 | } | |
813 | debug("Client protocol version %d.%d; client software version %.100s", | |
814 | remote_major, remote_minor, remote_version); | |
815 | if (remote_major != PROTOCOL_MAJOR) | |
816 | { | |
817 | const char *s = "Protocol major versions differ.\n"; | |
818 | (void) write(sock_out, s, strlen(s)); | |
819 | close(sock_in); | |
820 | close(sock_out); | |
821 | fatal("Protocol major versions differ: %d vs. %d", | |
822 | PROTOCOL_MAJOR, remote_major); | |
823 | } | |
824 | ||
825 | /* Check that the client has sufficiently high software version. */ | |
826 | if (remote_major == 1 && remote_minor < 3) | |
827 | packet_disconnect("Your ssh version is too old and is no longer supported. Please install a newer version."); | |
828 | ||
829 | if (remote_major == 1 && remote_minor == 3) { | |
830 | enable_compat13(); | |
831 | if (strcmp(remote_version, "OpenSSH-1.1") != 0) { | |
832 | debug("Agent forwarding disabled, remote version is not compatible."); | |
833 | no_agent_forwarding_flag = 1; | |
834 | } | |
835 | } | |
836 | ||
837 | packet_set_nonblocking(); | |
838 | ||
839 | /* Handle the connection. We pass as argument whether the connection | |
840 | came from a privileged port. */ | |
841 | do_connection(get_remote_port() < IPPORT_RESERVED); | |
842 | ||
843 | #ifdef KRB4 | |
844 | /* Cleanup user's ticket cache file. */ | |
845 | if (options.kerberos_ticket_cleanup) | |
846 | (void) dest_tkt(); | |
847 | #endif /* KRB4 */ | |
848 | ||
849 | /* Cleanup user's local Xauthority file. */ | |
850 | if (xauthfile) unlink(xauthfile); | |
851 | ||
852 | /* The connection has been terminated. */ | |
853 | log("Closing connection to %.100s", inet_ntoa(sin.sin_addr)); | |
854 | ||
5aecb327 | 855 | #ifdef HAVE_LIBPAM |
d813bc69 | 856 | { |
857 | int retval; | |
858 | ||
859 | if (pamh != NULL) | |
860 | { | |
549b3eed | 861 | debug("Closing PAM session."); |
d813bc69 | 862 | retval = pam_close_session((pam_handle_t *)pamh, 0); |
8efc0c15 | 863 | |
549b3eed | 864 | debug("Terminating PAM library."); |
d813bc69 | 865 | if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS) |
866 | log("Cannot release PAM authentication."); | |
8efc0c15 | 867 | |
d813bc69 | 868 | fatal_remove_cleanup(&pam_cleanup_proc, NULL); |
869 | } | |
870 | } | |
5aecb327 | 871 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 872 | |
873 | packet_close(); | |
874 | ||
875 | exit(0); | |
876 | } | |
877 | ||
878 | /* Process an incoming connection. Protocol version identifiers have already | |
879 | been exchanged. This sends server key and performs the key exchange. | |
880 | Server and host keys will no longer be needed after this functions. */ | |
881 | ||
882 | void do_connection(int privileged_port) | |
883 | { | |
a61d322f | 884 | int i, len; |
8efc0c15 | 885 | BIGNUM *session_key_int; |
886 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; | |
887 | unsigned char check_bytes[8]; | |
888 | char *user; | |
889 | unsigned int cipher_type, auth_mask, protocol_flags; | |
890 | int plen, slen; | |
891 | u_int32_t rand = 0; | |
892 | ||
893 | /* Generate check bytes that the client must send back in the user packet | |
894 | in order for it to be accepted; this is used to defy ip spoofing | |
895 | attacks. Note that this only works against somebody doing IP spoofing | |
896 | from a remote machine; any machine on the local network can still see | |
897 | outgoing packets and catch the random cookie. This only affects | |
898 | rhosts authentication, and this is one of the reasons why it is | |
899 | inherently insecure. */ | |
900 | for (i = 0; i < 8; i++) { | |
901 | if (i % 4 == 0) | |
902 | rand = arc4random(); | |
903 | check_bytes[i] = rand & 0xff; | |
904 | rand >>= 8; | |
905 | } | |
906 | ||
907 | /* Send our public key. We include in the packet 64 bits of random | |
908 | data that must be matched in the reply in order to prevent IP spoofing. */ | |
909 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
910 | for (i = 0; i < 8; i++) | |
911 | packet_put_char(check_bytes[i]); | |
912 | ||
913 | /* Store our public server RSA key. */ | |
914 | packet_put_int(BN_num_bits(public_key->n)); | |
915 | packet_put_bignum(public_key->e); | |
916 | packet_put_bignum(public_key->n); | |
917 | ||
918 | /* Store our public host RSA key. */ | |
919 | packet_put_int(BN_num_bits(sensitive_data.host_key->n)); | |
920 | packet_put_bignum(sensitive_data.host_key->e); | |
921 | packet_put_bignum(sensitive_data.host_key->n); | |
922 | ||
923 | /* Put protocol flags. */ | |
924 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
925 | ||
926 | /* Declare which ciphers we support. */ | |
927 | packet_put_int(cipher_mask()); | |
928 | ||
929 | /* Declare supported authentication types. */ | |
930 | auth_mask = 0; | |
931 | if (options.rhosts_authentication) | |
932 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
933 | if (options.rhosts_rsa_authentication) | |
934 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
935 | if (options.rsa_authentication) | |
936 | auth_mask |= 1 << SSH_AUTH_RSA; | |
937 | #ifdef KRB4 | |
938 | if (options.kerberos_authentication) | |
939 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
940 | #endif | |
941 | #ifdef AFS | |
942 | if (options.kerberos_tgt_passing) | |
943 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
944 | if (options.afs_token_passing) | |
945 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
946 | #endif | |
947 | if (options.password_authentication) | |
948 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
949 | packet_put_int(auth_mask); | |
950 | ||
951 | /* Send the packet and wait for it to be sent. */ | |
952 | packet_send(); | |
953 | packet_write_wait(); | |
954 | ||
955 | debug("Sent %d bit public key and %d bit host key.", | |
956 | BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n)); | |
957 | ||
958 | /* Read clients reply (cipher type and session key). */ | |
959 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
960 | ||
961 | /* Get cipher type. */ | |
962 | cipher_type = packet_get_char(); | |
963 | ||
964 | /* Get check bytes from the packet. These must match those we sent earlier | |
965 | with the public key packet. */ | |
966 | for (i = 0; i < 8; i++) | |
967 | if (check_bytes[i] != packet_get_char()) | |
968 | packet_disconnect("IP Spoofing check bytes do not match."); | |
969 | ||
970 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
971 | ||
972 | /* Get the encrypted integer. */ | |
973 | session_key_int = BN_new(); | |
974 | packet_get_bignum(session_key_int, &slen); | |
975 | ||
976 | /* Get protocol flags. */ | |
977 | protocol_flags = packet_get_int(); | |
978 | packet_set_protocol_flags(protocol_flags); | |
979 | ||
980 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
981 | ||
982 | /* Decrypt it using our private server key and private host key (key with | |
983 | larger modulus first). */ | |
984 | if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) | |
985 | { | |
986 | /* Private key has bigger modulus. */ | |
e1a9c08d | 987 | if (BN_num_bits(sensitive_data.private_key->n) < |
988 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
989 | fatal("do_connection: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
990 | BN_num_bits(sensitive_data.private_key->n), | |
991 | BN_num_bits(sensitive_data.host_key->n), | |
992 | SSH_KEY_BITS_RESERVED); | |
993 | } | |
994 | ||
8efc0c15 | 995 | rsa_private_decrypt(session_key_int, session_key_int, |
996 | sensitive_data.private_key); | |
997 | rsa_private_decrypt(session_key_int, session_key_int, | |
998 | sensitive_data.host_key); | |
999 | } | |
1000 | else | |
1001 | { | |
1002 | /* Host key has bigger modulus (or they are equal). */ | |
e1a9c08d | 1003 | if (BN_num_bits(sensitive_data.host_key->n) < |
1004 | BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) { | |
1005 | fatal("do_connection: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d", | |
1006 | BN_num_bits(sensitive_data.host_key->n), | |
1007 | BN_num_bits(sensitive_data.private_key->n), | |
1008 | SSH_KEY_BITS_RESERVED); | |
1009 | } | |
8efc0c15 | 1010 | rsa_private_decrypt(session_key_int, session_key_int, |
1011 | sensitive_data.host_key); | |
1012 | rsa_private_decrypt(session_key_int, session_key_int, | |
1013 | sensitive_data.private_key); | |
1014 | } | |
1015 | ||
1016 | /* Compute session id for this session. */ | |
1017 | compute_session_id(session_id, check_bytes, | |
1018 | BN_num_bits(sensitive_data.host_key->n), | |
1019 | sensitive_data.host_key->n, | |
1020 | BN_num_bits(sensitive_data.private_key->n), | |
1021 | sensitive_data.private_key->n); | |
1022 | ||
1023 | /* Extract session key from the decrypted integer. The key is in the | |
1024 | least significant 256 bits of the integer; the first byte of the | |
1025 | key is in the highest bits. */ | |
1026 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
a61d322f | 1027 | len = BN_num_bytes(session_key_int); |
e35c1dc2 | 1028 | if (len < 0 || len > sizeof(session_key)) |
a61d322f | 1029 | fatal("do_connection: bad len: session_key_int %d > sizeof(session_key) %d", |
1030 | len, sizeof(session_key)); | |
1031 | memset(session_key, 0, sizeof(session_key)); | |
1032 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
8efc0c15 | 1033 | |
1034 | /* Xor the first 16 bytes of the session key with the session id. */ | |
1035 | for (i = 0; i < 16; i++) | |
1036 | session_key[i] ^= session_id[i]; | |
1037 | ||
1038 | /* Destroy the decrypted integer. It is no longer needed. */ | |
1039 | BN_clear_free(session_key_int); | |
1040 | ||
1041 | /* Set the session key. From this on all communications will be | |
1042 | encrypted. */ | |
1043 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, | |
1044 | cipher_type, 0); | |
1045 | ||
1046 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1047 | memset(session_key, 0, sizeof(session_key)); | |
1048 | ||
1049 | debug("Received session key; encryption turned on."); | |
1050 | ||
1051 | /* Send an acknowledgement packet. Note that this packet is sent | |
1052 | encrypted. */ | |
1053 | packet_start(SSH_SMSG_SUCCESS); | |
1054 | packet_send(); | |
1055 | packet_write_wait(); | |
1056 | ||
1057 | /* Get the name of the user that we wish to log in as. */ | |
1058 | packet_read_expect(&plen, SSH_CMSG_USER); | |
1059 | ||
1060 | /* Get the user name. */ | |
1061 | { | |
1062 | int ulen; | |
1063 | user = packet_get_string(&ulen); | |
1064 | packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); | |
1065 | } | |
1066 | ||
1067 | /* Destroy the private and public keys. They will no longer be needed. */ | |
1068 | RSA_free(public_key); | |
1069 | RSA_free(sensitive_data.private_key); | |
1070 | RSA_free(sensitive_data.host_key); | |
1071 | ||
1072 | setproctitle("%s", user); | |
1073 | /* Do the authentication. */ | |
1074 | do_authentication(user, privileged_port); | |
1075 | } | |
1076 | ||
1077 | /* Check if the user is allowed to log in via ssh. If user is listed in | |
1078 | DenyUsers or user's primary group is listed in DenyGroups, false will | |
1079 | be returned. If AllowUsers isn't empty and user isn't listed there, or | |
1080 | if AllowGroups isn't empty and user isn't listed there, false will be | |
1081 | returned. Otherwise true is returned. | |
1082 | XXX This function should also check if user has a valid shell */ | |
1083 | ||
1084 | static int | |
1085 | allowed_user(struct passwd *pw) | |
1086 | { | |
1087 | struct group *grp; | |
1088 | int i; | |
1089 | ||
1090 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ | |
1091 | if (!pw) | |
1092 | return 0; | |
1093 | ||
1094 | /* XXX Should check for valid login shell */ | |
1095 | ||
1096 | /* Return false if user is listed in DenyUsers */ | |
1097 | if (options.num_deny_users > 0) | |
1098 | { | |
1099 | if (!pw->pw_name) | |
1100 | return 0; | |
1101 | for (i = 0; i < options.num_deny_users; i++) | |
1102 | if (match_pattern(pw->pw_name, options.deny_users[i])) | |
1103 | return 0; | |
1104 | } | |
1105 | ||
1106 | /* Return false if AllowUsers isn't empty and user isn't listed there */ | |
1107 | if (options.num_allow_users > 0) | |
1108 | { | |
1109 | if (!pw->pw_name) | |
1110 | return 0; | |
1111 | for (i = 0; i < options.num_allow_users; i++) | |
1112 | if (match_pattern(pw->pw_name, options.allow_users[i])) | |
1113 | break; | |
1114 | /* i < options.num_allow_users iff we break for loop */ | |
1115 | if (i >= options.num_allow_users) | |
1116 | return 0; | |
1117 | } | |
1118 | ||
1119 | /* Get the primary group name if we need it. Return false if it fails */ | |
1120 | if (options.num_deny_groups > 0 || options.num_allow_groups > 0 ) | |
1121 | { | |
1122 | grp = getgrgid(pw->pw_gid); | |
1123 | if (!grp) | |
1124 | return 0; | |
1125 | ||
1126 | /* Return false if user's group is listed in DenyGroups */ | |
1127 | if (options.num_deny_groups > 0) | |
1128 | { | |
1129 | if (!grp->gr_name) | |
1130 | return 0; | |
1131 | for (i = 0; i < options.num_deny_groups; i++) | |
1132 | if (match_pattern(grp->gr_name, options.deny_groups[i])) | |
1133 | return 0; | |
1134 | } | |
1135 | ||
1136 | /* Return false if AllowGroups isn't empty and user's group isn't | |
1137 | listed there */ | |
1138 | if (options.num_allow_groups > 0) | |
1139 | { | |
1140 | if (!grp->gr_name) | |
1141 | return 0; | |
1142 | for (i = 0; i < options.num_allow_groups; i++) | |
1143 | if (match_pattern(grp->gr_name, options.allow_groups[i])) | |
1144 | break; | |
1145 | /* i < options.num_allow_groups iff we break for loop */ | |
1146 | if (i >= options.num_allow_groups) | |
1147 | return 0; | |
1148 | } | |
1149 | } | |
1150 | ||
1151 | /* We found no reason not to let this user try to log on... */ | |
1152 | return 1; | |
1153 | } | |
1154 | ||
1155 | /* Performs authentication of an incoming connection. Session key has already | |
1156 | been exchanged and encryption is enabled. User is the user name to log | |
1157 | in as (received from the clinet). Privileged_port is true if the | |
1158 | connection comes from a privileged port (used for .rhosts authentication).*/ | |
1159 | ||
1160 | #define MAX_AUTH_FAILURES 5 | |
1161 | ||
1162 | void | |
1163 | do_authentication(char *user, int privileged_port) | |
1164 | { | |
1165 | int type; | |
1166 | int authenticated = 0; | |
1167 | int authentication_failures = 0; | |
d813bc69 | 1168 | char *password = NULL; |
8efc0c15 | 1169 | struct passwd *pw, pwcopy; |
d813bc69 | 1170 | char *client_user = NULL; |
8efc0c15 | 1171 | unsigned int client_host_key_bits; |
1172 | BIGNUM *client_host_key_e, *client_host_key_n; | |
549b3eed | 1173 | #ifdef HAVE_LIBPAM |
1174 | int pam_retval; | |
1175 | #endif /* HAVE_LIBPAM */ | |
1176 | ||
8efc0c15 | 1177 | #ifdef AFS |
1178 | /* If machine has AFS, set process authentication group. */ | |
1179 | if (k_hasafs()) { | |
1180 | k_setpag(); | |
1181 | k_unlog(); | |
1182 | } | |
1183 | #endif /* AFS */ | |
1184 | ||
1185 | /* Verify that the user is a valid user. */ | |
1186 | pw = getpwnam(user); | |
8efc0c15 | 1187 | if (!pw || !allowed_user(pw)) |
0183ea1c | 1188 | eat_packets_and_disconnect(user); |
1189 | ||
8efc0c15 | 1190 | /* Take a copy of the returned structure. */ |
1191 | memset(&pwcopy, 0, sizeof(pwcopy)); | |
1192 | pwcopy.pw_name = xstrdup(pw->pw_name); | |
1193 | pwcopy.pw_passwd = xstrdup(pw->pw_passwd); | |
1194 | pwcopy.pw_uid = pw->pw_uid; | |
1195 | pwcopy.pw_gid = pw->pw_gid; | |
1196 | pwcopy.pw_dir = xstrdup(pw->pw_dir); | |
1197 | pwcopy.pw_shell = xstrdup(pw->pw_shell); | |
1198 | pw = &pwcopy; | |
1199 | ||
5aecb327 | 1200 | #ifdef HAVE_LIBPAM |
549b3eed | 1201 | debug("Starting up PAM with username \"%.200s\"", pw->pw_name); |
1202 | pam_retval = pam_start("sshd", pw->pw_name, &conv, (pam_handle_t**)&pamh); | |
1203 | if (pam_retval != PAM_SUCCESS) | |
0183ea1c | 1204 | { |
549b3eed | 1205 | log("PAM initialisation failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); |
1206 | eat_packets_and_disconnect(user); | |
0183ea1c | 1207 | } |
549b3eed | 1208 | fatal_add_cleanup(&pam_cleanup_proc, NULL); |
5aecb327 | 1209 | #endif |
0183ea1c | 1210 | |
8efc0c15 | 1211 | /* If we are not running as root, the user must have the same uid as the |
1212 | server. */ | |
1213 | if (getuid() != 0 && pw->pw_uid != getuid()) | |
1214 | packet_disconnect("Cannot change user when server not running as root."); | |
1215 | ||
1216 | debug("Attempting authentication for %.100s.", user); | |
1217 | ||
1218 | /* If the user has no password, accept authentication immediately. */ | |
1219 | if (options.password_authentication && | |
1220 | #ifdef KRB4 | |
1221 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && | |
1222 | #endif /* KRB4 */ | |
1223 | auth_password(pw, "")) | |
1224 | { | |
1225 | /* Authentication with empty password succeeded. */ | |
1226 | debug("Login for user %.100s accepted without authentication.", user); | |
1227 | /* authentication_type = SSH_AUTH_PASSWORD; */ | |
1228 | authenticated = 1; | |
1229 | /* Success packet will be sent after loop below. */ | |
1230 | } | |
1231 | else | |
1232 | { | |
1233 | /* Indicate that authentication is needed. */ | |
1234 | packet_start(SSH_SMSG_FAILURE); | |
1235 | packet_send(); | |
1236 | packet_write_wait(); | |
1237 | } | |
1238 | ||
1239 | /* Loop until the user has been authenticated or the connection is closed. */ | |
1240 | while (!authenticated) | |
1241 | { | |
1242 | int plen; | |
1243 | /* Get a packet from the client. */ | |
1244 | type = packet_read(&plen); | |
1245 | ||
1246 | /* Process the packet. */ | |
1247 | switch (type) | |
1248 | { | |
1249 | ||
1250 | #ifdef AFS | |
1251 | case SSH_CMSG_HAVE_KERBEROS_TGT: | |
1252 | if (!options.kerberos_tgt_passing) | |
1253 | { | |
1254 | /* packet_get_all(); */ | |
1255 | log("Kerberos tgt passing disabled."); | |
1256 | break; | |
1257 | } | |
1258 | else { | |
1259 | /* Accept Kerberos tgt. */ | |
1260 | int dlen; | |
1261 | char *tgt = packet_get_string(&dlen); | |
1262 | packet_integrity_check(plen, 4 + dlen, type); | |
1263 | if (!auth_kerberos_tgt(pw, tgt)) | |
1264 | debug("Kerberos tgt REFUSED for %s", user); | |
1265 | xfree(tgt); | |
1266 | } | |
1267 | continue; | |
1268 | ||
1269 | case SSH_CMSG_HAVE_AFS_TOKEN: | |
1270 | if (!options.afs_token_passing || !k_hasafs()) { | |
1271 | /* packet_get_all(); */ | |
1272 | log("AFS token passing disabled."); | |
1273 | break; | |
1274 | } | |
1275 | else { | |
1276 | /* Accept AFS token. */ | |
1277 | int dlen; | |
1278 | char *token_string = packet_get_string(&dlen); | |
1279 | packet_integrity_check(plen, 4 + dlen, type); | |
e1a9c08d | 1280 | if (!auth_afs_token(pw, token_string)) |
8efc0c15 | 1281 | debug("AFS token REFUSED for %s", user); |
1282 | xfree(token_string); | |
1283 | continue; | |
1284 | } | |
1285 | #endif /* AFS */ | |
1286 | ||
1287 | #ifdef KRB4 | |
1288 | case SSH_CMSG_AUTH_KERBEROS: | |
1289 | if (!options.kerberos_authentication) | |
1290 | { | |
1291 | /* packet_get_all(); */ | |
1292 | log("Kerberos authentication disabled."); | |
1293 | break; | |
1294 | } | |
1295 | else { | |
1296 | /* Try Kerberos v4 authentication. */ | |
1297 | KTEXT_ST auth; | |
1298 | char *tkt_user = NULL; | |
1299 | char *kdata = packet_get_string((unsigned int *)&auth.length); | |
1300 | packet_integrity_check(plen, 4 + auth.length, type); | |
1301 | ||
1302 | if (auth.length < MAX_KTXT_LEN) | |
1303 | memcpy(auth.dat, kdata, auth.length); | |
1304 | xfree(kdata); | |
1305 | ||
1306 | if (auth_krb4(user, &auth, &tkt_user)) { | |
1307 | /* Client has successfully authenticated to us. */ | |
1308 | log("Kerberos authentication accepted %s for account " | |
1309 | "%s from %s", tkt_user, user, get_canonical_hostname()); | |
1310 | /* authentication_type = SSH_AUTH_KERBEROS; */ | |
1311 | authenticated = 1; | |
1312 | xfree(tkt_user); | |
1313 | } | |
1314 | else { | |
1315 | log("Kerberos authentication failed for account " | |
1316 | "%s from %s", user, get_canonical_hostname()); | |
1317 | } | |
1318 | } | |
1319 | break; | |
1320 | #endif /* KRB4 */ | |
1321 | ||
1322 | case SSH_CMSG_AUTH_RHOSTS: | |
1323 | if (!options.rhosts_authentication) | |
1324 | { | |
1325 | log("Rhosts authentication disabled."); | |
1326 | break; | |
1327 | } | |
1328 | ||
1329 | /* Rhosts authentication (also uses /etc/hosts.equiv). */ | |
1330 | if (!privileged_port) | |
1331 | { | |
1332 | log("Rhosts authentication not available for connections from unprivileged port."); | |
1333 | break; | |
1334 | } | |
1335 | ||
1336 | /* Get client user name. Note that we just have to trust the client; | |
1337 | this is one reason why rhosts authentication is insecure. | |
1338 | (Another is IP-spoofing on a local network.) */ | |
1339 | { | |
1340 | int dlen; | |
1341 | client_user = packet_get_string(&dlen); | |
1342 | packet_integrity_check(plen, 4 + dlen, type); | |
1343 | } | |
1344 | ||
1345 | /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ | |
1346 | if (auth_rhosts(pw, client_user, options.ignore_rhosts, | |
1347 | options.strict_modes)) | |
1348 | { | |
1349 | /* Authentication accepted. */ | |
1350 | log("Rhosts authentication accepted for %.100s, remote %.100s on %.700s.", | |
1351 | user, client_user, get_canonical_hostname()); | |
1352 | authenticated = 1; | |
5aecb327 | 1353 | #ifndef HAVE_LIBPAM |
8efc0c15 | 1354 | xfree(client_user); |
5aecb327 | 1355 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 1356 | break; |
1357 | } | |
1358 | log("Rhosts authentication failed for %.100s, remote %.100s.", | |
1359 | user, client_user); | |
5aecb327 | 1360 | #ifndef HAVE_LIBPAM |
8efc0c15 | 1361 | xfree(client_user); |
5aecb327 | 1362 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 1363 | break; |
1364 | ||
1365 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
1366 | if (!options.rhosts_rsa_authentication) | |
1367 | { | |
1368 | log("Rhosts with RSA authentication disabled."); | |
1369 | break; | |
1370 | } | |
1371 | ||
1372 | /* Rhosts authentication (also uses /etc/hosts.equiv) with RSA | |
1373 | host authentication. */ | |
1374 | if (!privileged_port) | |
1375 | { | |
1376 | log("Rhosts authentication not available for connections from unprivileged port."); | |
1377 | break; | |
1378 | } | |
1379 | ||
1380 | { | |
1381 | int ulen, elen, nlen; | |
1382 | /* Get client user name. Note that we just have to trust | |
1383 | the client; root on the client machine can claim to be | |
1384 | any user. */ | |
1385 | client_user = packet_get_string(&ulen); | |
1386 | ||
1387 | /* Get the client host key. */ | |
1388 | client_host_key_e = BN_new(); | |
1389 | client_host_key_n = BN_new(); | |
1390 | client_host_key_bits = packet_get_int(); | |
1391 | packet_get_bignum(client_host_key_e, &elen); | |
1392 | packet_get_bignum(client_host_key_n, &nlen); | |
1393 | ||
1394 | packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); | |
1395 | } | |
1396 | ||
8efc0c15 | 1397 | if (auth_rhosts_rsa(pw, client_user, |
b4748e2f | 1398 | client_host_key_bits, client_host_key_e, client_host_key_n)) |
8efc0c15 | 1399 | { |
1400 | /* Authentication accepted. */ | |
1401 | authenticated = 1; | |
5aecb327 | 1402 | #ifndef HAVE_LIBPAM |
8efc0c15 | 1403 | xfree(client_user); |
5aecb327 | 1404 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 1405 | BN_clear_free(client_host_key_e); |
1406 | BN_clear_free(client_host_key_n); | |
1407 | break; | |
1408 | } | |
1409 | log("Rhosts authentication failed for %.100s, remote %.100s.", | |
1410 | user, client_user); | |
5aecb327 | 1411 | #ifndef HAVE_LIBPAM |
d813bc69 | 1412 | xfree(client_user); |
5aecb327 | 1413 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 1414 | BN_clear_free(client_host_key_e); |
1415 | BN_clear_free(client_host_key_n); | |
1416 | break; | |
1417 | ||
1418 | case SSH_CMSG_AUTH_RSA: | |
1419 | if (!options.rsa_authentication) | |
1420 | { | |
1421 | log("RSA authentication disabled."); | |
1422 | break; | |
1423 | } | |
1424 | ||
1425 | /* RSA authentication requested. */ | |
1426 | { | |
1427 | int nlen; | |
1428 | BIGNUM *n; | |
1429 | n = BN_new(); | |
1430 | packet_get_bignum(n, &nlen); | |
1431 | ||
1432 | packet_integrity_check(plen, nlen, type); | |
1433 | ||
1434 | if (auth_rsa(pw, n, options.strict_modes)) | |
1435 | { | |
1436 | /* Successful authentication. */ | |
1437 | BN_clear_free(n); | |
1438 | log("RSA authentication for %.100s accepted.", user); | |
1439 | authenticated = 1; | |
1440 | break; | |
1441 | } | |
1442 | BN_clear_free(n); | |
1443 | log("RSA authentication for %.100s failed.", user); | |
1444 | } | |
1445 | break; | |
1446 | ||
1447 | case SSH_CMSG_AUTH_PASSWORD: | |
1448 | if (!options.password_authentication) | |
1449 | { | |
1450 | log("Password authentication disabled."); | |
1451 | break; | |
1452 | } | |
1453 | ||
1454 | /* Password authentication requested. */ | |
1455 | /* Read user password. It is in plain text, but was transmitted | |
1456 | over the encrypted channel so it is not visible to an outside | |
1457 | observer. */ | |
1458 | { | |
1459 | int passw_len; | |
1460 | password = packet_get_string(&passw_len); | |
1461 | packet_integrity_check(plen, 4 + passw_len, type); | |
1462 | } | |
1463 | ||
5aecb327 | 1464 | #ifdef HAVE_LIBPAM |
0183ea1c | 1465 | pampasswd = password; |
549b3eed | 1466 | |
1467 | pam_retval = pam_authenticate((pam_handle_t *)pamh, 0); | |
1468 | if (pam_retval == PAM_SUCCESS) | |
0183ea1c | 1469 | { |
549b3eed | 1470 | log("PAM Password authentication accepted for \"%.100s\"", user); |
0183ea1c | 1471 | authenticated = 1; |
1472 | break; | |
1473 | } else | |
1474 | { | |
549b3eed | 1475 | log("PAM Password authentication for \"%.100s\" failed: %s", |
1476 | user, pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
0183ea1c | 1477 | break; |
1478 | } | |
5aecb327 | 1479 | #else /* HAVE_LIBPAM */ |
8efc0c15 | 1480 | /* Try authentication with the password. */ |
1481 | if (auth_password(pw, password)) | |
1482 | { | |
1483 | /* Successful authentication. */ | |
1484 | /* Clear the password from memory. */ | |
1485 | memset(password, 0, strlen(password)); | |
1486 | xfree(password); | |
1487 | log("Password authentication for %.100s accepted.", user); | |
1488 | authenticated = 1; | |
1489 | break; | |
1490 | } | |
1491 | log("Password authentication for %.100s failed.", user); | |
1492 | memset(password, 0, strlen(password)); | |
1493 | xfree(password); | |
1494 | break; | |
5aecb327 | 1495 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 1496 | |
1497 | case SSH_CMSG_AUTH_TIS: | |
1498 | /* TIS Authentication is unsupported */ | |
1499 | log("TIS authentication disabled."); | |
1500 | break; | |
1501 | ||
1502 | default: | |
1503 | /* Any unknown messages will be ignored (and failure returned) | |
1504 | during authentication. */ | |
1505 | log("Unknown message during authentication: type %d", type); | |
1506 | break; /* Respond with a failure message. */ | |
1507 | } | |
1508 | /* If successfully authenticated, break out of loop. */ | |
1509 | if (authenticated) | |
1510 | break; | |
1511 | ||
8efc0c15 | 1512 | if (++authentication_failures >= MAX_AUTH_FAILURES) { |
1513 | packet_disconnect("Too many authentication failures for %.100s from %.200s", | |
1514 | pw->pw_name, get_canonical_hostname()); | |
1515 | } | |
e1a9c08d | 1516 | /* Send a message indicating that the authentication attempt failed. */ |
1517 | packet_start(SSH_SMSG_FAILURE); | |
1518 | packet_send(); | |
1519 | packet_write_wait(); | |
e35c1dc2 | 1520 | |
8efc0c15 | 1521 | } |
1522 | ||
1523 | /* Check if the user is logging in as root and root logins are disallowed. */ | |
1524 | if (pw->pw_uid == 0 && !options.permit_root_login) | |
1525 | { | |
1526 | if (forced_command) | |
3028328e | 1527 | log("Root login accepted for forced command."); |
8efc0c15 | 1528 | else |
1529 | packet_disconnect("ROOT LOGIN REFUSED FROM %.200s", | |
1530 | get_canonical_hostname()); | |
1531 | } | |
1532 | ||
5aecb327 | 1533 | #ifdef HAVE_LIBPAM |
0183ea1c | 1534 | do_pam_account_and_session(pw->pw_name, password, client_user, get_canonical_hostname()); |
d813bc69 | 1535 | |
1536 | /* Clean up */ | |
1537 | if (client_user != NULL) | |
1538 | xfree(client_user); | |
1539 | ||
1540 | if (password != NULL) | |
1541 | { | |
1542 | memset(password, 0, strlen(password)); | |
1543 | xfree(password); | |
1544 | } | |
5aecb327 | 1545 | #endif /* HAVE_LIBPAM */ |
d813bc69 | 1546 | |
8efc0c15 | 1547 | /* The user has been authenticated and accepted. */ |
1548 | packet_start(SSH_SMSG_SUCCESS); | |
1549 | packet_send(); | |
1550 | packet_write_wait(); | |
1551 | ||
1552 | /* Perform session preparation. */ | |
1553 | do_authenticated(pw); | |
1554 | } | |
1555 | ||
0183ea1c | 1556 | /* Read authentication messages, but return only failures until */ |
1557 | /* max auth attempts exceeded, then disconnect */ | |
1558 | void eat_packets_and_disconnect(const char *user) | |
1559 | { | |
1560 | int authentication_failures = 0; | |
1561 | ||
1562 | packet_start(SSH_SMSG_FAILURE); | |
1563 | packet_send(); | |
1564 | packet_write_wait(); | |
1565 | ||
1566 | /* Keep reading packets, and always respond with a failure. This is to | |
1567 | avoid disclosing whether such a user really exists. */ | |
1568 | while(1) | |
1569 | { | |
1570 | /* Read a packet. This will not return if the client disconnects. */ | |
1571 | int plen; | |
1572 | #ifndef SKEY | |
1573 | (void) packet_read(&plen); | |
1574 | #else /* SKEY */ | |
1575 | int type = packet_read(&plen); | |
1576 | int passw_len; | |
1577 | char *password, *skeyinfo; | |
1578 | if (options.password_authentication && | |
1579 | options.skey_authentication == 1 && | |
1580 | type == SSH_CMSG_AUTH_PASSWORD && | |
1581 | (password = packet_get_string(&passw_len)) != NULL && | |
1582 | passw_len == 5 && | |
1583 | strncasecmp(password, "s/key", 5) == 0 && | |
1584 | (skeyinfo = skey_fake_keyinfo(user)) != NULL ) | |
1585 | { | |
1586 | /* Send a fake s/key challenge. */ | |
1587 | packet_send_debug(skeyinfo); | |
1588 | } | |
1589 | #endif /* SKEY */ | |
0183ea1c | 1590 | if (++authentication_failures >= MAX_AUTH_FAILURES) |
1591 | { | |
1592 | packet_disconnect("Too many authentication failures for %.100s from %.200s", | |
1593 | user, get_canonical_hostname()); | |
1594 | } | |
e1a9c08d | 1595 | /* Send failure. This should be indistinguishable from a failed |
1596 | authentication. */ | |
1597 | packet_start(SSH_SMSG_FAILURE); | |
1598 | packet_send(); | |
1599 | packet_write_wait(); | |
0183ea1c | 1600 | } |
1601 | /*NOTREACHED*/ | |
1602 | abort(); | |
1603 | } | |
1604 | ||
6a17f9c2 | 1605 | /* Remove local Xauthority file. */ |
1606 | static void | |
1607 | xauthfile_cleanup_proc(void *ignore) | |
1608 | { | |
1609 | debug("xauthfile_cleanup_proc called"); | |
1610 | ||
1611 | if (xauthfile != NULL) { | |
1612 | unlink(xauthfile); | |
1613 | xfree(xauthfile); | |
1614 | xauthfile = NULL; | |
1615 | } | |
1616 | } | |
1617 | ||
8efc0c15 | 1618 | /* Prepares for an interactive session. This is called after the user has |
1619 | been successfully authenticated. During this message exchange, pseudo | |
1620 | terminals are allocated, X11, TCP/IP, and authentication agent forwardings | |
1621 | are requested, etc. */ | |
1622 | ||
1623 | void do_authenticated(struct passwd *pw) | |
1624 | { | |
1625 | int type; | |
1626 | int compression_level = 0, enable_compression_after_reply = 0; | |
1627 | int have_pty = 0, ptyfd = -1, ttyfd = -1, xauthfd = -1; | |
1628 | int row, col, xpixel, ypixel, screen; | |
1629 | char ttyname[64]; | |
1630 | char *command, *term = NULL, *display = NULL, *proto = NULL, *data = NULL; | |
1631 | struct group *grp; | |
1632 | gid_t tty_gid; | |
1633 | mode_t tty_mode; | |
1634 | int n_bytes; | |
1635 | ||
1636 | /* Cancel the alarm we set to limit the time taken for authentication. */ | |
1637 | alarm(0); | |
1638 | ||
1639 | /* Inform the channel mechanism that we are the server side and that | |
1640 | the client may request to connect to any port at all. (The user could | |
1641 | do it anyway, and we wouldn\'t know what is permitted except by the | |
1642 | client telling us, so we can equally well trust the client not to request | |
1643 | anything bogus.) */ | |
1644 | channel_permit_all_opens(); | |
1645 | ||
1646 | /* We stay in this loop until the client requests to execute a shell or a | |
1647 | command. */ | |
1648 | while (1) | |
1649 | { | |
1650 | int plen, dlen; | |
1651 | ||
1652 | /* Get a packet from the client. */ | |
1653 | type = packet_read(&plen); | |
1654 | ||
1655 | /* Process the packet. */ | |
1656 | switch (type) | |
1657 | { | |
1658 | case SSH_CMSG_REQUEST_COMPRESSION: | |
1659 | packet_integrity_check(plen, 4, type); | |
1660 | compression_level = packet_get_int(); | |
1661 | if (compression_level < 1 || compression_level > 9) | |
1662 | { | |
1663 | packet_send_debug("Received illegal compression level %d.", | |
1664 | compression_level); | |
1665 | goto fail; | |
1666 | } | |
1667 | /* Enable compression after we have responded with SUCCESS. */ | |
1668 | enable_compression_after_reply = 1; | |
1669 | break; | |
1670 | ||
1671 | case SSH_CMSG_REQUEST_PTY: | |
1672 | if (no_pty_flag) | |
1673 | { | |
1674 | debug("Allocating a pty not permitted for this authentication."); | |
1675 | goto fail; | |
1676 | } | |
1677 | if (have_pty) | |
1678 | packet_disconnect("Protocol error: you already have a pty."); | |
1679 | ||
1680 | debug("Allocating pty."); | |
1681 | ||
1682 | /* Allocate a pty and open it. */ | |
1683 | if (!pty_allocate(&ptyfd, &ttyfd, ttyname)) | |
1684 | { | |
1685 | error("Failed to allocate pty."); | |
1686 | goto fail; | |
1687 | } | |
1688 | ||
1689 | /* Determine the group to make the owner of the tty. */ | |
1690 | grp = getgrnam("tty"); | |
1691 | if (grp) | |
1692 | { | |
1693 | tty_gid = grp->gr_gid; | |
1694 | tty_mode = S_IRUSR|S_IWUSR|S_IWGRP; | |
1695 | } | |
1696 | else | |
1697 | { | |
1698 | tty_gid = pw->pw_gid; | |
1699 | tty_mode = S_IRUSR|S_IWUSR|S_IWGRP|S_IWOTH; | |
1700 | } | |
1701 | ||
1702 | /* Change ownership of the tty. */ | |
1703 | if (chown(ttyname, pw->pw_uid, tty_gid) < 0) | |
1704 | fatal("chown(%.100s, %d, %d) failed: %.100s", | |
1705 | ttyname, pw->pw_uid, tty_gid, strerror(errno)); | |
1706 | if (chmod(ttyname, tty_mode) < 0) | |
1707 | fatal("chmod(%.100s, 0%o) failed: %.100s", | |
1708 | ttyname, tty_mode, strerror(errno)); | |
1709 | ||
1710 | /* Get TERM from the packet. Note that the value may be of arbitrary | |
1711 | length. */ | |
1712 | ||
1713 | term = packet_get_string(&dlen); | |
1714 | packet_integrity_check(dlen, strlen(term), type); | |
1715 | /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */ | |
1716 | /* Remaining bytes */ | |
1717 | n_bytes = plen - (4 + dlen + 4*4); | |
1718 | ||
1719 | if (strcmp(term, "") == 0) | |
1720 | term = NULL; | |
1721 | ||
1722 | /* Get window size from the packet. */ | |
1723 | row = packet_get_int(); | |
1724 | col = packet_get_int(); | |
1725 | xpixel = packet_get_int(); | |
1726 | ypixel = packet_get_int(); | |
1727 | pty_change_window_size(ptyfd, row, col, xpixel, ypixel); | |
1728 | ||
1729 | /* Get tty modes from the packet. */ | |
1730 | tty_parse_modes(ttyfd, &n_bytes); | |
1731 | packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); | |
1732 | ||
1733 | /* Indicate that we now have a pty. */ | |
1734 | have_pty = 1; | |
1735 | break; | |
1736 | ||
1737 | case SSH_CMSG_X11_REQUEST_FORWARDING: | |
1738 | if (!options.x11_forwarding) | |
1739 | { | |
1740 | packet_send_debug("X11 forwarding disabled in server configuration file."); | |
1741 | goto fail; | |
1742 | } | |
1743 | #ifdef XAUTH_PATH | |
1744 | if (no_x11_forwarding_flag) | |
1745 | { | |
1746 | packet_send_debug("X11 forwarding not permitted for this authentication."); | |
1747 | goto fail; | |
1748 | } | |
1749 | debug("Received request for X11 forwarding with auth spoofing."); | |
1750 | if (display) | |
1751 | packet_disconnect("Protocol error: X11 display already set."); | |
1752 | { | |
1753 | int proto_len, data_len; | |
1754 | proto = packet_get_string(&proto_len); | |
1755 | data = packet_get_string(&data_len); | |
1756 | packet_integrity_check(plen, 4+proto_len + 4+data_len + 4, type); | |
1757 | } | |
1758 | if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER) | |
1759 | screen = packet_get_int(); | |
1760 | else | |
1761 | screen = 0; | |
1762 | display = x11_create_display_inet(screen); | |
1763 | if (!display) | |
1764 | goto fail; | |
1765 | ||
1766 | /* Setup to always have a local .Xauthority. */ | |
1767 | xauthfile = xmalloc(MAXPATHLEN); | |
1768 | snprintf(xauthfile, MAXPATHLEN, "/tmp/XauthXXXXXX"); | |
1769 | ||
1770 | if ((xauthfd = mkstemp(xauthfile)) != -1) { | |
1771 | fchown(xauthfd, pw->pw_uid, pw->pw_gid); | |
1772 | close(xauthfd); | |
6a17f9c2 | 1773 | fatal_add_cleanup(xauthfile_cleanup_proc, NULL); |
8efc0c15 | 1774 | } |
1775 | else { | |
1776 | xfree(xauthfile); | |
1777 | xauthfile = NULL; | |
1778 | } | |
1779 | break; | |
1780 | #else /* XAUTH_PATH */ | |
1781 | /* No xauth program; we won't accept forwarding with spoofing. */ | |
1782 | packet_send_debug("No xauth program; cannot forward with spoofing."); | |
1783 | goto fail; | |
1784 | #endif /* XAUTH_PATH */ | |
1785 | ||
1786 | case SSH_CMSG_AGENT_REQUEST_FORWARDING: | |
1787 | if (no_agent_forwarding_flag) | |
1788 | { | |
1789 | debug("Authentication agent forwarding not permitted for this authentication."); | |
1790 | goto fail; | |
1791 | } | |
1792 | debug("Received authentication agent forwarding request."); | |
1793 | auth_input_request_forwarding(pw); | |
1794 | break; | |
1795 | ||
1796 | case SSH_CMSG_PORT_FORWARD_REQUEST: | |
1797 | if (no_port_forwarding_flag) | |
1798 | { | |
1799 | debug("Port forwarding not permitted for this authentication."); | |
1800 | goto fail; | |
1801 | } | |
1802 | debug("Received TCP/IP port forwarding request."); | |
1803 | channel_input_port_forward_request(pw->pw_uid == 0); | |
1804 | break; | |
1805 | ||
1806 | case SSH_CMSG_EXEC_SHELL: | |
1807 | /* Set interactive/non-interactive mode. */ | |
1808 | packet_set_interactive(have_pty || display != NULL, | |
1809 | options.keepalives); | |
1810 | ||
1811 | if (forced_command != NULL) | |
1812 | goto do_forced_command; | |
1813 | debug("Forking shell."); | |
1814 | packet_integrity_check(plen, 0, type); | |
1815 | if (have_pty) | |
1816 | do_exec_pty(NULL, ptyfd, ttyfd, ttyname, pw, term, display, proto, | |
1817 | data); | |
1818 | else | |
1819 | do_exec_no_pty(NULL, pw, display, proto, data); | |
1820 | return; | |
1821 | ||
1822 | case SSH_CMSG_EXEC_CMD: | |
1823 | /* Set interactive/non-interactive mode. */ | |
1824 | packet_set_interactive(have_pty || display != NULL, | |
1825 | options.keepalives); | |
1826 | ||
1827 | if (forced_command != NULL) | |
1828 | goto do_forced_command; | |
1829 | /* Get command from the packet. */ | |
1830 | { | |
1831 | int dlen; | |
1832 | command = packet_get_string(&dlen); | |
1833 | debug("Executing command '%.500s'", command); | |
1834 | packet_integrity_check(plen, 4 + dlen, type); | |
1835 | } | |
1836 | if (have_pty) | |
1837 | do_exec_pty(command, ptyfd, ttyfd, ttyname, pw, term, display, | |
1838 | proto, data); | |
1839 | else | |
1840 | do_exec_no_pty(command, pw, display, proto, data); | |
1841 | xfree(command); | |
1842 | return; | |
1843 | ||
1844 | case SSH_CMSG_MAX_PACKET_SIZE: | |
1845 | debug("The server does not support limiting packet size."); | |
1846 | goto fail; | |
1847 | ||
1848 | default: | |
1849 | /* Any unknown messages in this phase are ignored, and a failure | |
1850 | message is returned. */ | |
1851 | log("Unknown packet type received after authentication: %d", type); | |
1852 | goto fail; | |
1853 | } | |
1854 | ||
1855 | /* The request was successfully processed. */ | |
1856 | packet_start(SSH_SMSG_SUCCESS); | |
1857 | packet_send(); | |
1858 | packet_write_wait(); | |
1859 | ||
1860 | /* Enable compression now that we have replied if appropriate. */ | |
1861 | if (enable_compression_after_reply) | |
1862 | { | |
1863 | enable_compression_after_reply = 0; | |
1864 | packet_start_compression(compression_level); | |
1865 | } | |
1866 | ||
1867 | continue; | |
1868 | ||
1869 | fail: | |
1870 | /* The request failed. */ | |
1871 | packet_start(SSH_SMSG_FAILURE); | |
1872 | packet_send(); | |
1873 | packet_write_wait(); | |
1874 | continue; | |
1875 | ||
1876 | do_forced_command: | |
1877 | /* There is a forced command specified for this login. Execute it. */ | |
1878 | debug("Executing forced command: %.900s", forced_command); | |
1879 | if (have_pty) | |
1880 | do_exec_pty(forced_command, ptyfd, ttyfd, ttyname, pw, term, display, | |
1881 | proto, data); | |
1882 | else | |
1883 | do_exec_no_pty(forced_command, pw, display, proto, data); | |
1884 | return; | |
1885 | } | |
1886 | } | |
1887 | ||
1888 | /* This is called to fork and execute a command when we have no tty. This | |
1889 | will call do_child from the child, and server_loop from the parent after | |
1890 | setting up file descriptors and such. */ | |
1891 | ||
1892 | void do_exec_no_pty(const char *command, struct passwd *pw, | |
1893 | const char *display, const char *auth_proto, | |
1894 | const char *auth_data) | |
1895 | { | |
1896 | int pid; | |
1897 | ||
1898 | #ifdef USE_PIPES | |
1899 | int pin[2], pout[2], perr[2]; | |
1900 | /* Allocate pipes for communicating with the program. */ | |
1901 | if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) | |
1902 | packet_disconnect("Could not create pipes: %.100s", | |
1903 | strerror(errno)); | |
1904 | #else /* USE_PIPES */ | |
1905 | int inout[2], err[2]; | |
1906 | /* Uses socket pairs to communicate with the program. */ | |
1907 | if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || | |
1908 | socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) | |
1909 | packet_disconnect("Could not create socket pairs: %.100s", | |
1910 | strerror(errno)); | |
1911 | #endif /* USE_PIPES */ | |
1912 | ||
1913 | setproctitle("%s@notty", pw->pw_name); | |
1914 | ||
1915 | /* Fork the child. */ | |
1916 | if ((pid = fork()) == 0) | |
1917 | { | |
1918 | /* Child. Reinitialize the log since the pid has changed. */ | |
6a17f9c2 | 1919 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 1920 | |
1921 | /* Create a new session and process group since the 4.4BSD setlogin() | |
1922 | affects the entire process group. */ | |
1923 | if (setsid() < 0) | |
1924 | error("setsid failed: %.100s", strerror(errno)); | |
1925 | ||
1926 | #ifdef USE_PIPES | |
1927 | /* Redirect stdin. We close the parent side of the socket pair, | |
1928 | and make the child side the standard input. */ | |
1929 | close(pin[1]); | |
1930 | if (dup2(pin[0], 0) < 0) | |
1931 | perror("dup2 stdin"); | |
1932 | close(pin[0]); | |
1933 | ||
1934 | /* Redirect stdout. */ | |
1935 | close(pout[0]); | |
1936 | if (dup2(pout[1], 1) < 0) | |
1937 | perror("dup2 stdout"); | |
1938 | close(pout[1]); | |
1939 | ||
1940 | /* Redirect stderr. */ | |
1941 | close(perr[0]); | |
1942 | if (dup2(perr[1], 2) < 0) | |
1943 | perror("dup2 stderr"); | |
1944 | close(perr[1]); | |
1945 | #else /* USE_PIPES */ | |
1946 | /* Redirect stdin, stdout, and stderr. Stdin and stdout will use the | |
1947 | same socket, as some programs (particularly rdist) seem to depend | |
1948 | on it. */ | |
1949 | close(inout[1]); | |
1950 | close(err[1]); | |
1951 | if (dup2(inout[0], 0) < 0) /* stdin */ | |
1952 | perror("dup2 stdin"); | |
1953 | if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ | |
1954 | perror("dup2 stdout"); | |
1955 | if (dup2(err[0], 2) < 0) /* stderr */ | |
1956 | perror("dup2 stderr"); | |
1957 | #endif /* USE_PIPES */ | |
1958 | ||
1959 | /* Do processing for the child (exec command etc). */ | |
1960 | do_child(command, pw, NULL, display, auth_proto, auth_data, NULL); | |
1961 | /*NOTREACHED*/ | |
1962 | } | |
1963 | if (pid < 0) | |
1964 | packet_disconnect("fork failed: %.100s", strerror(errno)); | |
1965 | #ifdef USE_PIPES | |
1966 | /* We are the parent. Close the child sides of the pipes. */ | |
1967 | close(pin[0]); | |
1968 | close(pout[1]); | |
1969 | close(perr[1]); | |
1970 | ||
1971 | /* Enter the interactive session. */ | |
1972 | server_loop(pid, pin[1], pout[0], perr[0]); | |
1973 | /* server_loop has closed pin[1], pout[1], and perr[1]. */ | |
1974 | #else /* USE_PIPES */ | |
1975 | /* We are the parent. Close the child sides of the socket pairs. */ | |
1976 | close(inout[0]); | |
1977 | close(err[0]); | |
1978 | ||
1979 | /* Enter the interactive session. Note: server_loop must be able to handle | |
1980 | the case that fdin and fdout are the same. */ | |
1981 | server_loop(pid, inout[1], inout[1], err[1]); | |
1982 | /* server_loop has closed inout[1] and err[1]. */ | |
1983 | #endif /* USE_PIPES */ | |
1984 | } | |
1985 | ||
1986 | struct pty_cleanup_context | |
1987 | { | |
1988 | const char *ttyname; | |
1989 | int pid; | |
1990 | }; | |
1991 | ||
1992 | /* Function to perform cleanup if we get aborted abnormally (e.g., due to a | |
1993 | dropped connection). */ | |
1994 | ||
1995 | void pty_cleanup_proc(void *context) | |
1996 | { | |
1997 | struct pty_cleanup_context *cu = context; | |
1998 | ||
1999 | debug("pty_cleanup_proc called"); | |
2000 | ||
8efc0c15 | 2001 | /* Record that the user has logged out. */ |
2002 | record_logout(cu->pid, cu->ttyname); | |
2003 | ||
2004 | /* Release the pseudo-tty. */ | |
2005 | pty_release(cu->ttyname); | |
2006 | } | |
2007 | ||
2008 | /* This is called to fork and execute a command when we have a tty. This | |
2009 | will call do_child from the child, and server_loop from the parent after | |
2010 | setting up file descriptors, controlling tty, updating wtmp, utmp, | |
2011 | lastlog, and other such operations. */ | |
2012 | ||
2013 | void do_exec_pty(const char *command, int ptyfd, int ttyfd, | |
2014 | const char *ttyname, struct passwd *pw, const char *term, | |
2015 | const char *display, const char *auth_proto, | |
2016 | const char *auth_data) | |
2017 | { | |
2018 | int pid, fdout; | |
2019 | const char *hostname; | |
2020 | time_t last_login_time; | |
2021 | char buf[100], *time_string; | |
2022 | FILE *f; | |
2023 | char line[256]; | |
2024 | struct stat st; | |
2025 | int quiet_login; | |
2026 | struct sockaddr_in from; | |
2027 | int fromlen; | |
2028 | struct pty_cleanup_context cleanup_context; | |
2029 | ||
2030 | /* Get remote host name. */ | |
2031 | hostname = get_canonical_hostname(); | |
2032 | ||
2033 | /* Get the time when the user last logged in. Buf will be set to contain | |
2034 | the hostname the last login was from. */ | |
2035 | if(!options.use_login) { | |
2036 | last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name, | |
2037 | buf, sizeof(buf)); | |
2038 | } | |
2039 | ||
2040 | setproctitle("%s@%s", pw->pw_name, strrchr(ttyname, '/') + 1); | |
2041 | ||
2042 | /* Fork the child. */ | |
2043 | if ((pid = fork()) == 0) | |
2044 | { | |
2045 | pid = getpid(); | |
2046 | ||
2047 | /* Child. Reinitialize the log because the pid has changed. */ | |
6a17f9c2 | 2048 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 2049 | |
2050 | /* Close the master side of the pseudo tty. */ | |
2051 | close(ptyfd); | |
2052 | ||
2053 | /* Make the pseudo tty our controlling tty. */ | |
2054 | pty_make_controlling_tty(&ttyfd, ttyname); | |
2055 | ||
2056 | /* Redirect stdin from the pseudo tty. */ | |
2057 | if (dup2(ttyfd, fileno(stdin)) < 0) | |
2058 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2059 | ||
2060 | /* Redirect stdout to the pseudo tty. */ | |
2061 | if (dup2(ttyfd, fileno(stdout)) < 0) | |
2062 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2063 | ||
2064 | /* Redirect stderr to the pseudo tty. */ | |
2065 | if (dup2(ttyfd, fileno(stderr)) < 0) | |
2066 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2067 | ||
2068 | /* Close the extra descriptor for the pseudo tty. */ | |
2069 | close(ttyfd); | |
2070 | ||
2071 | /* Get IP address of client. This is needed because we want to record | |
2072 | where the user logged in from. If the connection is not a socket, | |
2073 | let the ip address be 0.0.0.0. */ | |
2074 | memset(&from, 0, sizeof(from)); | |
2075 | if (packet_get_connection_in() == packet_get_connection_out()) | |
2076 | { | |
2077 | fromlen = sizeof(from); | |
2078 | if (getpeername(packet_get_connection_in(), | |
2079 | (struct sockaddr *)&from, &fromlen) < 0) | |
2080 | fatal("getpeername: %.100s", strerror(errno)); | |
2081 | } | |
2082 | ||
2083 | /* Record that there was a login on that terminal. */ | |
2084 | record_login(pid, ttyname, pw->pw_name, pw->pw_uid, hostname, | |
2085 | &from); | |
2086 | ||
2087 | /* Check if .hushlogin exists. */ | |
2088 | snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir); | |
2089 | quiet_login = stat(line, &st) >= 0; | |
e1a9c08d | 2090 | |
2091 | #ifdef HAVE_LIBPAM | |
2092 | /* output the results of the pamconv() */ | |
2093 | if (!quiet_login && pamconv_msg != NULL) | |
2094 | fprintf(stderr, pamconv_msg); | |
2095 | #endif | |
2096 | ||
8efc0c15 | 2097 | /* If the user has logged in before, display the time of last login. |
2098 | However, don't display anything extra if a command has been | |
2099 | specified (so that ssh can be used to execute commands on a remote | |
2100 | machine without users knowing they are going to another machine). | |
2101 | Login(1) will do this for us as well, so check if login(1) is used */ | |
2102 | if (command == NULL && last_login_time != 0 && !quiet_login && | |
2103 | !options.use_login) | |
2104 | { | |
2105 | /* Convert the date to a string. */ | |
2106 | time_string = ctime(&last_login_time); | |
2107 | /* Remove the trailing newline. */ | |
2108 | if (strchr(time_string, '\n')) | |
2109 | *strchr(time_string, '\n') = 0; | |
2110 | /* Display the last login time. Host if displayed if known. */ | |
2111 | if (strcmp(buf, "") == 0) | |
2112 | printf("Last login: %s\r\n", time_string); | |
2113 | else | |
2114 | printf("Last login: %s from %s\r\n", time_string, buf); | |
2115 | } | |
2116 | ||
2117 | /* Print /etc/motd unless a command was specified or printing it was | |
2118 | disabled in server options or login(1) will be used. Note that | |
2119 | some machines appear to print it in /etc/profile or similar. */ | |
2120 | if (command == NULL && options.print_motd && !quiet_login && | |
2121 | !options.use_login) | |
2122 | { | |
2123 | /* Print /etc/motd if it exists. */ | |
2124 | f = fopen("/etc/motd", "r"); | |
2125 | if (f) | |
2126 | { | |
2127 | while (fgets(line, sizeof(line), f)) | |
2128 | fputs(line, stdout); | |
2129 | fclose(f); | |
2130 | } | |
2131 | } | |
2132 | ||
2133 | /* Do common processing for the child, such as execing the command. */ | |
2134 | do_child(command, pw, term, display, auth_proto, auth_data, ttyname); | |
2135 | /*NOTREACHED*/ | |
2136 | } | |
2137 | if (pid < 0) | |
2138 | packet_disconnect("fork failed: %.100s", strerror(errno)); | |
2139 | /* Parent. Close the slave side of the pseudo tty. */ | |
2140 | close(ttyfd); | |
2141 | ||
2142 | /* Create another descriptor of the pty master side for use as the standard | |
2143 | input. We could use the original descriptor, but this simplifies code | |
2144 | in server_loop. The descriptor is bidirectional. */ | |
2145 | fdout = dup(ptyfd); | |
2146 | if (fdout < 0) | |
2147 | packet_disconnect("dup failed: %.100s", strerror(errno)); | |
2148 | ||
2149 | /* Add a cleanup function to clear the utmp entry and record logout time | |
2150 | in case we call fatal() (e.g., the connection gets closed). */ | |
2151 | cleanup_context.pid = pid; | |
2152 | cleanup_context.ttyname = ttyname; | |
2153 | fatal_add_cleanup(pty_cleanup_proc, (void *)&cleanup_context); | |
2154 | ||
2155 | /* Enter interactive session. */ | |
2156 | server_loop(pid, ptyfd, fdout, -1); | |
2157 | /* server_loop has not closed ptyfd and fdout. */ | |
2158 | ||
2159 | /* Cancel the cleanup function. */ | |
2160 | fatal_remove_cleanup(pty_cleanup_proc, (void *)&cleanup_context); | |
2161 | ||
2162 | /* Record that the user has logged out. */ | |
2163 | record_logout(pid, ttyname); | |
2164 | ||
2165 | /* Release the pseudo-tty. */ | |
2166 | pty_release(ttyname); | |
2167 | ||
2168 | /* Close the server side of the socket pairs. We must do this after the | |
2169 | pty cleanup, so that another process doesn't get this pty while we're | |
2170 | still cleaning up. */ | |
2171 | close(ptyfd); | |
2172 | close(fdout); | |
2173 | } | |
2174 | ||
2175 | /* Sets the value of the given variable in the environment. If the variable | |
2176 | already exists, its value is overriden. */ | |
2177 | ||
2178 | void child_set_env(char ***envp, unsigned int *envsizep, const char *name, | |
2179 | const char *value) | |
2180 | { | |
2181 | unsigned int i, namelen; | |
2182 | char **env; | |
2183 | ||
2184 | /* Find the slot where the value should be stored. If the variable already | |
2185 | exists, we reuse the slot; otherwise we append a new slot at the end | |
2186 | of the array, expanding if necessary. */ | |
2187 | env = *envp; | |
2188 | namelen = strlen(name); | |
2189 | for (i = 0; env[i]; i++) | |
2190 | if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') | |
2191 | break; | |
2192 | if (env[i]) | |
2193 | { | |
2194 | /* Name already exists. Reuse the slot. */ | |
2195 | xfree(env[i]); | |
2196 | } | |
2197 | else | |
2198 | { | |
2199 | /* New variable. Expand the array if necessary. */ | |
2200 | if (i >= (*envsizep) - 1) | |
2201 | { | |
2202 | (*envsizep) += 50; | |
2203 | env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); | |
2204 | } | |
2205 | ||
2206 | /* Need to set the NULL pointer at end of array beyond the new | |
2207 | slot. */ | |
2208 | env[i + 1] = NULL; | |
2209 | } | |
2210 | ||
2211 | /* Allocate space and format the variable in the appropriate slot. */ | |
2212 | env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); | |
2213 | snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); | |
2214 | } | |
2215 | ||
2216 | /* Reads environment variables from the given file and adds/overrides them | |
2217 | into the environment. If the file does not exist, this does nothing. | |
2218 | Otherwise, it must consist of empty lines, comments (line starts with '#') | |
2219 | and assignments of the form name=value. No other forms are allowed. */ | |
2220 | ||
2221 | void read_environment_file(char ***env, unsigned int *envsize, | |
2222 | const char *filename) | |
2223 | { | |
2224 | FILE *f; | |
2225 | char buf[4096]; | |
2226 | char *cp, *value; | |
2227 | ||
2228 | /* Open the environment file. */ | |
2229 | f = fopen(filename, "r"); | |
2230 | if (!f) | |
2231 | return; /* Not found. */ | |
2232 | ||
2233 | /* Process each line. */ | |
2234 | while (fgets(buf, sizeof(buf), f)) | |
2235 | { | |
2236 | /* Skip leading whitespace. */ | |
2237 | for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) | |
2238 | ; | |
2239 | ||
2240 | /* Ignore empty and comment lines. */ | |
2241 | if (!*cp || *cp == '#' || *cp == '\n') | |
2242 | continue; | |
2243 | ||
2244 | /* Remove newline. */ | |
2245 | if (strchr(cp, '\n')) | |
2246 | *strchr(cp, '\n') = '\0'; | |
2247 | ||
2248 | /* Find the equals sign. Its lack indicates badly formatted line. */ | |
2249 | value = strchr(cp, '='); | |
2250 | if (value == NULL) | |
2251 | { | |
2252 | fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf); | |
2253 | continue; | |
2254 | } | |
2255 | ||
2256 | /* Replace the equals sign by nul, and advance value to the value | |
2257 | string. */ | |
2258 | *value = '\0'; | |
2259 | value++; | |
2260 | ||
2261 | /* Set the value in environment. */ | |
2262 | child_set_env(env, envsize, cp, value); | |
2263 | } | |
2264 | ||
2265 | fclose(f); | |
2266 | } | |
2267 | ||
2268 | /* Performs common processing for the child, such as setting up the | |
2269 | environment, closing extra file descriptors, setting the user and group | |
2270 | ids, and executing the command or shell. */ | |
2271 | ||
2272 | void do_child(const char *command, struct passwd *pw, const char *term, | |
2273 | const char *display, const char *auth_proto, | |
2274 | const char *auth_data, const char *ttyname) | |
2275 | { | |
2276 | const char *shell, *cp = NULL; | |
2277 | char buf[256]; | |
2278 | FILE *f; | |
2279 | unsigned int envsize, i; | |
2280 | char **env; | |
2281 | extern char **environ; | |
2282 | struct stat st; | |
2283 | char *argv[10]; | |
2284 | ||
e1a9c08d | 2285 | #ifndef HAVE_LIBPAM /* pam_nologin handles this */ |
8efc0c15 | 2286 | /* Check /etc/nologin. */ |
2287 | f = fopen("/etc/nologin", "r"); | |
2288 | if (f) | |
2289 | { /* /etc/nologin exists. Print its contents and exit. */ | |
2290 | while (fgets(buf, sizeof(buf), f)) | |
2291 | fputs(buf, stderr); | |
2292 | fclose(f); | |
2293 | if (pw->pw_uid != 0) | |
2294 | exit(254); | |
2295 | } | |
e35c1dc2 | 2296 | #endif /* HAVE_LIBPAM */ |
2297 | ||
2298 | #ifdef HAVE_SETLOGIN | |
2299 | /* Set login name in the kernel. */ | |
2300 | if (setlogin(pw->pw_name) < 0) | |
2301 | error("setlogin failed: %s", strerror(errno)); | |
2302 | #endif /* HAVE_SETLOGIN */ | |
8efc0c15 | 2303 | |
8efc0c15 | 2304 | /* Set uid, gid, and groups. */ |
2305 | /* Login(1) does this as well, and it needs uid 0 for the "-h" switch, | |
2306 | so we let login(1) to this for us. */ | |
2307 | if(!options.use_login) { | |
2308 | if (getuid() == 0 || geteuid() == 0) | |
2309 | { | |
2310 | if (setgid(pw->pw_gid) < 0) | |
2311 | { | |
2312 | perror("setgid"); | |
2313 | exit(1); | |
2314 | } | |
2315 | /* Initialize the group list. */ | |
2316 | if (initgroups(pw->pw_name, pw->pw_gid) < 0) | |
2317 | { | |
2318 | perror("initgroups"); | |
2319 | exit(1); | |
2320 | } | |
2321 | endgrent(); | |
2322 | ||
2323 | /* Permanently switch to the desired uid. */ | |
2324 | permanently_set_uid(pw->pw_uid); | |
2325 | } | |
2326 | ||
2327 | if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) | |
2328 | fatal("Failed to set uids to %d.", (int)pw->pw_uid); | |
2329 | } | |
2330 | ||
2331 | /* Get the shell from the password data. An empty shell field is legal, | |
2332 | and means /bin/sh. */ | |
2333 | shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; | |
2334 | ||
2335 | #ifdef AFS | |
2336 | /* Try to get AFS tokens for the local cell. */ | |
2337 | if (k_hasafs()) { | |
2338 | char cell[64]; | |
2339 | ||
2340 | if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) | |
2341 | krb_afslog(cell, 0); | |
2342 | ||
2343 | krb_afslog(0, 0); | |
2344 | } | |
2345 | #endif /* AFS */ | |
2346 | ||
2347 | /* Initialize the environment. In the first part we allocate space for | |
2348 | all environment variables. */ | |
2349 | envsize = 100; | |
2350 | env = xmalloc(envsize * sizeof(char *)); | |
2351 | env[0] = NULL; | |
2352 | ||
2353 | if(!options.use_login) { | |
2354 | /* Set basic environment. */ | |
2355 | child_set_env(&env, &envsize, "USER", pw->pw_name); | |
2356 | child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); | |
2357 | child_set_env(&env, &envsize, "HOME", pw->pw_dir); | |
2358 | child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); | |
2359 | ||
2360 | snprintf(buf, sizeof buf, "%.200s/%.50s", | |
2361 | _PATH_MAILDIR, pw->pw_name); | |
2362 | child_set_env(&env, &envsize, "MAIL", buf); | |
2363 | ||
2364 | /* Normal systems set SHELL by default. */ | |
2365 | child_set_env(&env, &envsize, "SHELL", shell); | |
2366 | } | |
2367 | ||
2368 | /* Let it inherit timezone if we have one. */ | |
2369 | if (getenv("TZ")) | |
2370 | child_set_env(&env, &envsize, "TZ", getenv("TZ")); | |
2371 | ||
2372 | /* Set custom environment options from RSA authentication. */ | |
2373 | while (custom_environment) | |
2374 | { | |
2375 | struct envstring *ce = custom_environment; | |
2376 | char *s = ce->s; | |
2377 | int i; | |
2378 | for (i = 0; s[i] != '=' && s[i]; i++) | |
2379 | ; | |
2380 | if (s[i] == '=') | |
2381 | { | |
2382 | s[i] = 0; | |
2383 | child_set_env(&env, &envsize, s, s + i + 1); | |
2384 | } | |
2385 | custom_environment = ce->next; | |
2386 | xfree(ce->s); | |
2387 | xfree(ce); | |
2388 | } | |
2389 | ||
2390 | /* Set SSH_CLIENT. */ | |
2391 | snprintf(buf, sizeof buf, "%.50s %d %d", | |
2392 | get_remote_ipaddr(), get_remote_port(), options.port); | |
2393 | child_set_env(&env, &envsize, "SSH_CLIENT", buf); | |
2394 | ||
2395 | /* Set SSH_TTY if we have a pty. */ | |
2396 | if (ttyname) | |
2397 | child_set_env(&env, &envsize, "SSH_TTY", ttyname); | |
2398 | ||
2399 | /* Set TERM if we have a pty. */ | |
2400 | if (term) | |
2401 | child_set_env(&env, &envsize, "TERM", term); | |
2402 | ||
2403 | /* Set DISPLAY if we have one. */ | |
2404 | if (display) | |
2405 | child_set_env(&env, &envsize, "DISPLAY", display); | |
2406 | ||
2407 | #ifdef KRB4 | |
6a17f9c2 | 2408 | { |
e35c1dc2 | 2409 | extern char *ticket; |
2410 | ||
2411 | if (ticket) | |
2412 | child_set_env(&env, &envsize, "KRBTKFILE", ticket); | |
6a17f9c2 | 2413 | } |
8efc0c15 | 2414 | #endif /* KRB4 */ |
2415 | ||
bb0dd7f6 | 2416 | #ifdef HAVE_LIBPAM |
2417 | /* Pull in any environment variables that may have been set by PAM. */ | |
2418 | { | |
2419 | char *equal_sign, var_name[256], var_val[256]; | |
2420 | long this_var; | |
50da1126 | 2421 | char **pam_env = pam_getenvlist((pam_handle_t *)pamh); |
bb0dd7f6 | 2422 | for(this_var = 0; pam_env && pam_env[this_var]; this_var++) |
2423 | { | |
242588e6 | 2424 | if(strlen(pam_env[this_var]) < (sizeof(var_name) - 1)) |
bb0dd7f6 | 2425 | if((equal_sign = strstr(pam_env[this_var], "=")) != NULL) |
2426 | { | |
2427 | memset(var_name, 0, sizeof(var_name)); | |
2428 | memset(var_val, 0, sizeof(var_val)); | |
2429 | strncpy(var_name, pam_env[this_var], | |
2430 | equal_sign - pam_env[this_var]); | |
2431 | strcpy(var_val, equal_sign + 1); | |
2432 | child_set_env(&env, &envsize, var_name, var_val); | |
2433 | } | |
2434 | } | |
2435 | } | |
2436 | #endif /* HAVE_LIBPAM */ | |
2437 | ||
8efc0c15 | 2438 | /* Set XAUTHORITY to always be a local file. */ |
2439 | if (xauthfile) | |
2440 | child_set_env(&env, &envsize, "XAUTHORITY", xauthfile); | |
2441 | ||
2442 | /* Set variable for forwarded authentication connection, if we have one. */ | |
2443 | if (auth_get_socket_name() != NULL) | |
2444 | child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, | |
2445 | auth_get_socket_name()); | |
e35c1dc2 | 2446 | |
8efc0c15 | 2447 | /* Read $HOME/.ssh/environment. */ |
2448 | if(!options.use_login) { | |
2449 | snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir); | |
2450 | read_environment_file(&env, &envsize, buf); | |
2451 | } | |
2452 | ||
2453 | /* If debugging, dump the environment to stderr. */ | |
2454 | if (debug_flag) | |
2455 | { | |
2456 | fprintf(stderr, "Environment:\n"); | |
2457 | for (i = 0; env[i]; i++) | |
2458 | fprintf(stderr, " %.200s\n", env[i]); | |
2459 | } | |
2460 | ||
2461 | /* Close the connection descriptors; note that this is the child, and the | |
2462 | server will still have the socket open, and it is important that we | |
2463 | do not shutdown it. Note that the descriptors cannot be closed before | |
2464 | building the environment, as we call get_remote_ipaddr there. */ | |
2465 | if (packet_get_connection_in() == packet_get_connection_out()) | |
2466 | close(packet_get_connection_in()); | |
2467 | else | |
2468 | { | |
2469 | close(packet_get_connection_in()); | |
2470 | close(packet_get_connection_out()); | |
2471 | } | |
2472 | /* Close all descriptors related to channels. They will still remain | |
2473 | open in the parent. */ | |
2474 | channel_close_all(); | |
2475 | ||
2476 | /* Close any extra file descriptors. Note that there may still be | |
2477 | descriptors left by system functions. They will be closed later. */ | |
2478 | endpwent(); | |
2479 | endhostent(); | |
2480 | ||
2481 | /* Close any extra open file descriptors so that we don\'t have them | |
2482 | hanging around in clients. Note that we want to do this after | |
2483 | initgroups, because at least on Solaris 2.3 it leaves file descriptors | |
2484 | open. */ | |
2485 | for (i = 3; i < 64; i++) | |
2486 | close(i); | |
2487 | ||
2488 | /* Change current directory to the user\'s home directory. */ | |
2489 | if (chdir(pw->pw_dir) < 0) | |
2490 | fprintf(stderr, "Could not chdir to home directory %s: %s\n", | |
2491 | pw->pw_dir, strerror(errno)); | |
2492 | ||
2493 | /* Must take new environment into use so that .ssh/rc, /etc/sshrc and | |
2494 | xauth are run in the proper environment. */ | |
2495 | environ = env; | |
2496 | ||
2497 | /* Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first | |
2498 | in this order). */ | |
2499 | if(!options.use_login) { | |
2500 | if (stat(SSH_USER_RC, &st) >= 0) | |
2501 | { | |
2502 | if (debug_flag) | |
2503 | fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC); | |
2504 | ||
2505 | f = popen("/bin/sh " SSH_USER_RC, "w"); | |
2506 | if (f) | |
2507 | { | |
2508 | if (auth_proto != NULL && auth_data != NULL) | |
2509 | fprintf(f, "%s %s\n", auth_proto, auth_data); | |
2510 | pclose(f); | |
2511 | } | |
2512 | else | |
2513 | fprintf(stderr, "Could not run %s\n", SSH_USER_RC); | |
2514 | } | |
2515 | else | |
2516 | if (stat(SSH_SYSTEM_RC, &st) >= 0) | |
2517 | { | |
2518 | if (debug_flag) | |
2519 | fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC); | |
2520 | ||
2521 | f = popen("/bin/sh " SSH_SYSTEM_RC, "w"); | |
2522 | if (f) | |
2523 | { | |
2524 | if (auth_proto != NULL && auth_data != NULL) | |
2525 | fprintf(f, "%s %s\n", auth_proto, auth_data); | |
2526 | pclose(f); | |
2527 | } | |
2528 | else | |
2529 | fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC); | |
2530 | } | |
2531 | #ifdef XAUTH_PATH | |
2532 | else | |
2533 | { | |
2534 | /* Add authority data to .Xauthority if appropriate. */ | |
2535 | if (auth_proto != NULL && auth_data != NULL) | |
2536 | { | |
2537 | if (debug_flag) | |
2538 | fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n", | |
2539 | XAUTH_PATH, display, auth_proto, auth_data); | |
2540 | ||
2541 | f = popen(XAUTH_PATH " -q -", "w"); | |
2542 | if (f) | |
2543 | { | |
2544 | fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data); | |
2545 | fclose(f); | |
2546 | } | |
2547 | else | |
2548 | fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH); | |
2549 | } | |
2550 | } | |
2551 | #endif /* XAUTH_PATH */ | |
2552 | ||
2553 | /* Get the last component of the shell name. */ | |
2554 | cp = strrchr(shell, '/'); | |
2555 | if (cp) | |
2556 | cp++; | |
2557 | else | |
2558 | cp = shell; | |
2559 | } | |
2560 | ||
2561 | /* If we have no command, execute the shell. In this case, the shell name | |
2562 | to be passed in argv[0] is preceded by '-' to indicate that this is | |
2563 | a login shell. */ | |
2564 | if (!command) | |
2565 | { | |
2566 | if(!options.use_login) { | |
2567 | char buf[256]; | |
2568 | ||
2569 | /* Check for mail if we have a tty and it was enabled in server options. */ | |
2570 | if (ttyname && options.check_mail) { | |
2571 | char *mailbox; | |
2572 | struct stat mailstat; | |
2573 | mailbox = getenv("MAIL"); | |
2574 | if(mailbox != NULL) { | |
2575 | if(stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0) { | |
2576 | printf("No mail.\n"); | |
2577 | } else if(mailstat.st_mtime < mailstat.st_atime) { | |
2578 | printf("You have mail.\n"); | |
2579 | } else { | |
2580 | printf("You have new mail.\n"); | |
2581 | } | |
2582 | } | |
2583 | } | |
2584 | /* Start the shell. Set initial character to '-'. */ | |
2585 | buf[0] = '-'; | |
2586 | strncpy(buf + 1, cp, sizeof(buf) - 1); | |
2587 | buf[sizeof(buf) - 1] = 0; | |
2588 | /* Execute the shell. */ | |
2589 | argv[0] = buf; | |
2590 | argv[1] = NULL; | |
2591 | execve(shell, argv, env); | |
2592 | /* Executing the shell failed. */ | |
2593 | perror(shell); | |
2594 | exit(1); | |
2595 | ||
2596 | } else { | |
2597 | /* Launch login(1). */ | |
2598 | ||
e1a9c08d | 2599 | execl(LOGIN_PROGRAM, "login", "-h", get_remote_ipaddr(), "-p", "-f", "--", pw->pw_name, NULL); |
8efc0c15 | 2600 | |
2601 | /* Login couldn't be executed, die. */ | |
2602 | ||
2603 | perror("login"); | |
2604 | exit(1); | |
2605 | } | |
2606 | } | |
2607 | ||
2608 | /* Execute the command using the user's shell. This uses the -c option | |
2609 | to execute the command. */ | |
2610 | argv[0] = (char *)cp; | |
2611 | argv[1] = "-c"; | |
2612 | argv[2] = (char *)command; | |
2613 | argv[3] = NULL; | |
2614 | execve(shell, argv, env); | |
2615 | perror(shell); | |
2616 | exit(1); | |
2617 | } |