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Commit | Line | Data |
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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 | ||
f601d847 | 35 | #ifdef HAVE_MAILLOCK_H |
36 | # include <maillock.h> | |
37 | #endif | |
38 | ||
8efc0c15 | 39 | #ifdef LIBWRAP |
40 | #include <tcpd.h> | |
41 | #include <syslog.h> | |
42 | int allow_severity = LOG_INFO; | |
43 | int deny_severity = LOG_WARNING; | |
44 | #endif /* LIBWRAP */ | |
45 | ||
46 | #ifndef O_NOCTTY | |
47 | #define O_NOCTTY 0 | |
48 | #endif | |
49 | ||
8efc0c15 | 50 | /* Local Xauthority file. */ |
6a17f9c2 | 51 | static char *xauthfile = NULL; |
8efc0c15 | 52 | |
53 | /* Server configuration options. */ | |
54 | ServerOptions options; | |
55 | ||
56 | /* Name of the server configuration file. */ | |
57 | char *config_file_name = SERVER_CONFIG_FILE; | |
58 | ||
59 | /* Debug mode flag. This can be set on the command line. If debug | |
60 | mode is enabled, extra debugging output will be sent to the system | |
61 | log, the daemon will not go to background, and will exit after processing | |
62 | the first connection. */ | |
63 | int debug_flag = 0; | |
64 | ||
65 | /* Flag indicating that the daemon is being started from inetd. */ | |
66 | int inetd_flag = 0; | |
67 | ||
6a17f9c2 | 68 | /* debug goes to stderr unless inetd_flag is set */ |
69 | int log_stderr = 0; | |
70 | ||
8efc0c15 | 71 | /* argv[0] without path. */ |
72 | char *av0; | |
73 | ||
74 | /* Saved arguments to main(). */ | |
75 | char **saved_argv; | |
76 | ||
77 | /* This is set to the socket that the server is listening; this is used in | |
78 | the SIGHUP signal handler. */ | |
79 | int listen_sock; | |
80 | ||
81 | /* Flags set in auth-rsa from authorized_keys flags. These are set in | |
82 | auth-rsa.c. */ | |
83 | int no_port_forwarding_flag = 0; | |
84 | int no_agent_forwarding_flag = 0; | |
85 | int no_x11_forwarding_flag = 0; | |
86 | int no_pty_flag = 0; | |
87 | char *forced_command = NULL; /* RSA authentication "command=" option. */ | |
88 | struct envstring *custom_environment = NULL; | |
89 | /* RSA authentication "environment=" options. */ | |
90 | ||
91 | /* Session id for the current session. */ | |
92 | unsigned char session_id[16]; | |
93 | ||
94 | /* Any really sensitive data in the application is contained in this structure. | |
95 | The idea is that this structure could be locked into memory so that the | |
96 | pages do not get written into swap. However, there are some problems. | |
97 | The private key contains BIGNUMs, and we do not (in principle) have | |
98 | access to the internals of them, and locking just the structure is not | |
99 | very useful. Currently, memory locking is not implemented. */ | |
100 | struct | |
101 | { | |
102 | /* Private part of server key. */ | |
103 | RSA *private_key; | |
104 | ||
105 | /* Private part of host key. */ | |
106 | RSA *host_key; | |
107 | } sensitive_data; | |
108 | ||
109 | /* Flag indicating whether the current session key has been used. This flag | |
110 | is set whenever the key is used, and cleared when the key is regenerated. */ | |
111 | int key_used = 0; | |
112 | ||
113 | /* This is set to true when SIGHUP is received. */ | |
114 | int received_sighup = 0; | |
115 | ||
116 | /* Public side of the server key. This value is regenerated regularly with | |
117 | the private key. */ | |
118 | RSA *public_key; | |
119 | ||
120 | /* Prototypes for various functions defined later in this file. */ | |
e7c0f9d5 | 121 | void do_connection(); |
122 | void do_authentication(char *user); | |
123 | void do_authloop(struct passwd *pw); | |
124 | void do_fake_authloop(char *user); | |
8efc0c15 | 125 | void do_authenticated(struct passwd *pw); |
126 | void do_exec_pty(const char *command, int ptyfd, int ttyfd, | |
127 | const char *ttyname, struct passwd *pw, const char *term, | |
128 | const char *display, const char *auth_proto, | |
129 | const char *auth_data); | |
130 | void do_exec_no_pty(const char *command, struct passwd *pw, | |
131 | const char *display, const char *auth_proto, | |
132 | const char *auth_data); | |
133 | void do_child(const char *command, struct passwd *pw, const char *term, | |
134 | const char *display, const char *auth_proto, | |
135 | const char *auth_data, const char *ttyname); | |
e7c0f9d5 | 136 | |
5aecb327 | 137 | #ifdef HAVE_LIBPAM |
8efc0c15 | 138 | static int pamconv(int num_msg, const struct pam_message **msg, |
e7c0f9d5 | 139 | struct pam_response **resp, void *appdata_ptr); |
c75a1a66 | 140 | void do_pam_account_and_session(char *username, char *remote_user, |
141 | const char *remote_host); | |
d813bc69 | 142 | void pam_cleanup_proc(void *context); |
8efc0c15 | 143 | |
144 | static struct pam_conv conv = { | |
145 | pamconv, | |
146 | NULL | |
147 | }; | |
d813bc69 | 148 | struct pam_handle_t *pamh = NULL; |
149 | const char *pampasswd = NULL; | |
e1a9c08d | 150 | char *pamconv_msg = NULL; |
8efc0c15 | 151 | |
152 | static int pamconv(int num_msg, const struct pam_message **msg, | |
153 | struct pam_response **resp, void *appdata_ptr) | |
154 | { | |
155 | int count = 0; | |
8efc0c15 | 156 | struct pam_response *reply = NULL; |
8efc0c15 | 157 | |
d813bc69 | 158 | /* PAM will free this later */ |
159 | reply = malloc(num_msg * sizeof(*reply)); | |
160 | if (reply == NULL) | |
161 | return PAM_CONV_ERR; | |
162 | ||
8efc0c15 | 163 | for(count = 0; count < num_msg; count++) |
164 | { | |
165 | switch (msg[count]->msg_style) | |
166 | { | |
8efc0c15 | 167 | case PAM_PROMPT_ECHO_OFF: |
0183ea1c | 168 | if (pampasswd == NULL) |
d813bc69 | 169 | { |
8efc0c15 | 170 | free(reply); |
d813bc69 | 171 | return PAM_CONV_ERR; |
172 | } | |
173 | reply[count].resp_retcode = PAM_SUCCESS; | |
174 | reply[count].resp = xstrdup(pampasswd); | |
175 | break; | |
176 | ||
177 | case PAM_TEXT_INFO: | |
178 | reply[count].resp_retcode = PAM_SUCCESS; | |
179 | reply[count].resp = xstrdup(""); | |
e1a9c08d | 180 | |
181 | if (msg[count]->msg == NULL) break; | |
182 | debug("Adding PAM message: %s", msg[count]->msg); | |
183 | if (pamconv_msg == NULL) | |
184 | { | |
185 | pamconv_msg = malloc(strlen(msg[count]->msg) + 2); | |
186 | ||
187 | if (pamconv_msg == NULL) | |
188 | return PAM_CONV_ERR; | |
189 | ||
190 | strncpy(pamconv_msg, msg[count]->msg, strlen(msg[count]->msg)); | |
191 | pamconv_msg[strlen(msg[count]->msg)] = '\n'; | |
192 | pamconv_msg[strlen(msg[count]->msg) + 1] = '\0'; | |
193 | } else | |
194 | { | |
195 | pamconv_msg = realloc(pamconv_msg, strlen(pamconv_msg) + strlen(msg[count]->msg) + 2); | |
196 | strncat(pamconv_msg, msg[count]->msg, strlen(msg[count]->msg)); | |
197 | pamconv_msg[strlen(pamconv_msg)] = '\n'; | |
198 | pamconv_msg[strlen(pamconv_msg) + 1] = '\0'; | |
199 | } | |
d813bc69 | 200 | break; |
8efc0c15 | 201 | |
d813bc69 | 202 | case PAM_PROMPT_ECHO_ON: |
203 | case PAM_ERROR_MSG: | |
204 | default: | |
205 | free(reply); | |
206 | return PAM_CONV_ERR; | |
207 | } | |
8efc0c15 | 208 | } |
209 | ||
d813bc69 | 210 | *resp = reply; |
8efc0c15 | 211 | |
212 | return PAM_SUCCESS; | |
213 | } | |
214 | ||
215 | void pam_cleanup_proc(void *context) | |
216 | { | |
549b3eed | 217 | int pam_retval; |
d813bc69 | 218 | |
219 | if (pamh != NULL) | |
220 | { | |
549b3eed | 221 | pam_retval = pam_close_session((pam_handle_t *)pamh, 0); |
222 | if (pam_retval != PAM_SUCCESS) | |
223 | { | |
224 | log("Cannot close PAM session: %.200s", | |
225 | pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
226 | } | |
227 | ||
228 | pam_retval = pam_end((pam_handle_t *)pamh, pam_retval); | |
229 | if (pam_retval != PAM_SUCCESS) | |
230 | { | |
231 | log("Cannot release PAM authentication: %.200s", | |
232 | pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
233 | } | |
d813bc69 | 234 | } |
235 | } | |
236 | ||
c75a1a66 | 237 | void do_pam_account_and_session(char *username, char *remote_user, |
238 | const char *remote_host) | |
d813bc69 | 239 | { |
549b3eed | 240 | int pam_retval; |
241 | ||
242 | if (remote_host != NULL) | |
d813bc69 | 243 | { |
549b3eed | 244 | debug("PAM setting rhost to \"%.200s\"", remote_host); |
245 | pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RHOST, remote_host); | |
246 | if (pam_retval != PAM_SUCCESS) | |
247 | { | |
248 | log("PAM set rhost failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
e7c0f9d5 | 249 | do_fake_authloop(username); |
549b3eed | 250 | } |
0183ea1c | 251 | } |
549b3eed | 252 | |
253 | if (remote_user != NULL) | |
0183ea1c | 254 | { |
549b3eed | 255 | debug("PAM setting ruser to \"%.200s\"", remote_user); |
256 | pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RUSER, remote_user); | |
257 | if (pam_retval != PAM_SUCCESS) | |
258 | { | |
259 | log("PAM set ruser failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
e7c0f9d5 | 260 | do_fake_authloop(username); |
549b3eed | 261 | } |
0183ea1c | 262 | } |
549b3eed | 263 | |
264 | pam_retval = pam_acct_mgmt((pam_handle_t *)pamh, 0); | |
265 | if (pam_retval != PAM_SUCCESS) | |
0183ea1c | 266 | { |
549b3eed | 267 | log("PAM rejected by account configuration: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); |
e7c0f9d5 | 268 | do_fake_authloop(username); |
0183ea1c | 269 | } |
d813bc69 | 270 | |
549b3eed | 271 | pam_retval = pam_open_session((pam_handle_t *)pamh, 0); |
272 | if (pam_retval != PAM_SUCCESS) | |
d813bc69 | 273 | { |
549b3eed | 274 | log("PAM session setup failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); |
e7c0f9d5 | 275 | do_fake_authloop(username); |
d813bc69 | 276 | } |
8efc0c15 | 277 | } |
5aecb327 | 278 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 279 | |
280 | /* Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
281 | the effect is to reread the configuration file (and to regenerate | |
282 | the server key). */ | |
283 | ||
284 | void sighup_handler(int sig) | |
285 | { | |
286 | received_sighup = 1; | |
287 | signal(SIGHUP, sighup_handler); | |
288 | } | |
289 | ||
290 | /* Called from the main program after receiving SIGHUP. Restarts the | |
291 | server. */ | |
292 | ||
293 | void sighup_restart() | |
294 | { | |
295 | log("Received SIGHUP; restarting."); | |
296 | close(listen_sock); | |
297 | execv(saved_argv[0], saved_argv); | |
298 | log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); | |
299 | exit(1); | |
300 | } | |
301 | ||
302 | /* Generic signal handler for terminating signals in the master daemon. | |
303 | These close the listen socket; not closing it seems to cause "Address | |
304 | already in use" problems on some machines, which is inconvenient. */ | |
305 | ||
306 | void sigterm_handler(int sig) | |
307 | { | |
308 | log("Received signal %d; terminating.", sig); | |
309 | close(listen_sock); | |
310 | exit(255); | |
311 | } | |
312 | ||
313 | /* SIGCHLD handler. This is called whenever a child dies. This will then | |
314 | reap any zombies left by exited c. */ | |
315 | ||
316 | void main_sigchld_handler(int sig) | |
317 | { | |
318 | int save_errno = errno; | |
319 | int status; | |
320 | wait(&status); | |
321 | signal(SIGCHLD, main_sigchld_handler); | |
322 | errno = save_errno; | |
323 | } | |
324 | ||
325 | /* Signal handler for the alarm after the login grace period has expired. */ | |
326 | ||
327 | void grace_alarm_handler(int sig) | |
328 | { | |
329 | /* Close the connection. */ | |
330 | packet_close(); | |
331 | ||
332 | /* Log error and exit. */ | |
333 | fatal("Timeout before authentication."); | |
334 | } | |
335 | ||
336 | /* Signal handler for the key regeneration alarm. Note that this | |
337 | alarm only occurs in the daemon waiting for connections, and it does not | |
338 | do anything with the private key or random state before forking. Thus there | |
339 | should be no concurrency control/asynchronous execution problems. */ | |
340 | ||
341 | void key_regeneration_alarm(int sig) | |
342 | { | |
343 | int save_errno = errno; | |
344 | ||
345 | /* Check if we should generate a new key. */ | |
346 | if (key_used) | |
347 | { | |
348 | /* This should really be done in the background. */ | |
349 | log("Generating new %d bit RSA key.", options.server_key_bits); | |
350 | ||
351 | if (sensitive_data.private_key != NULL) | |
352 | RSA_free(sensitive_data.private_key); | |
353 | sensitive_data.private_key = RSA_new(); | |
354 | ||
355 | if (public_key != NULL) | |
356 | RSA_free(public_key); | |
357 | public_key = RSA_new(); | |
358 | ||
359 | rsa_generate_key(sensitive_data.private_key, public_key, | |
360 | options.server_key_bits); | |
361 | arc4random_stir(); | |
362 | key_used = 0; | |
363 | log("RSA key generation complete."); | |
364 | } | |
365 | ||
366 | /* Reschedule the alarm. */ | |
367 | signal(SIGALRM, key_regeneration_alarm); | |
368 | alarm(options.key_regeneration_time); | |
369 | errno = save_errno; | |
370 | } | |
371 | ||
372 | /* Main program for the daemon. */ | |
373 | ||
374 | int | |
375 | main(int ac, char **av) | |
376 | { | |
377 | extern char *optarg; | |
378 | extern int optind; | |
379 | int opt, aux, sock_in, sock_out, newsock, i, pid, on = 1; | |
380 | int remote_major, remote_minor; | |
381 | int silentrsa = 0; | |
382 | struct sockaddr_in sin; | |
383 | char buf[100]; /* Must not be larger than remote_version. */ | |
384 | char remote_version[100]; /* Must be at least as big as buf. */ | |
e7c0f9d5 | 385 | int remote_port; |
8efc0c15 | 386 | char *comment; |
387 | FILE *f; | |
388 | struct linger linger; | |
389 | ||
390 | /* Save argv[0]. */ | |
391 | saved_argv = av; | |
392 | if (strchr(av[0], '/')) | |
393 | av0 = strrchr(av[0], '/') + 1; | |
394 | else | |
395 | av0 = av[0]; | |
396 | ||
397 | /* Initialize configuration options to their default values. */ | |
398 | initialize_server_options(&options); | |
399 | ||
400 | /* Parse command-line arguments. */ | |
401 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:diqQ")) != EOF) | |
402 | { | |
403 | switch (opt) | |
404 | { | |
405 | case 'f': | |
406 | config_file_name = optarg; | |
407 | break; | |
408 | case 'd': | |
409 | debug_flag = 1; | |
6a17f9c2 | 410 | options.log_level = SYSLOG_LEVEL_DEBUG; |
8efc0c15 | 411 | break; |
412 | case 'i': | |
413 | inetd_flag = 1; | |
414 | break; | |
415 | case 'Q': | |
416 | silentrsa = 1; | |
417 | break; | |
418 | case 'q': | |
6a17f9c2 | 419 | options.log_level = SYSLOG_LEVEL_QUIET; |
8efc0c15 | 420 | break; |
421 | case 'b': | |
422 | options.server_key_bits = atoi(optarg); | |
423 | break; | |
424 | case 'p': | |
425 | options.port = atoi(optarg); | |
426 | break; | |
427 | case 'g': | |
428 | options.login_grace_time = atoi(optarg); | |
429 | break; | |
430 | case 'k': | |
431 | options.key_regeneration_time = atoi(optarg); | |
432 | break; | |
433 | case 'h': | |
434 | options.host_key_file = optarg; | |
435 | break; | |
436 | case '?': | |
437 | default: | |
438 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
439 | fprintf(stderr, "Usage: %s [options]\n", av0); | |
440 | fprintf(stderr, "Options:\n"); | |
441 | fprintf(stderr, " -f file Configuration file (default %s/sshd_config)\n", ETCDIR); | |
442 | fprintf(stderr, " -d Debugging mode\n"); | |
443 | fprintf(stderr, " -i Started from inetd\n"); | |
444 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
445 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
446 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
447 | fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); | |
448 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
449 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
450 | HOST_KEY_FILE); | |
451 | exit(1); | |
452 | } | |
453 | } | |
454 | ||
455 | /* check if RSA support exists */ | |
456 | if (rsa_alive() == 0) { | |
457 | if (silentrsa == 0) | |
458 | printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n"); | |
459 | log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)"); | |
460 | exit(1); | |
461 | } | |
462 | ||
463 | /* Read server configuration options from the configuration file. */ | |
464 | read_server_config(&options, config_file_name); | |
465 | ||
466 | /* Fill in default values for those options not explicitly set. */ | |
467 | fill_default_server_options(&options); | |
468 | ||
469 | /* Check certain values for sanity. */ | |
470 | if (options.server_key_bits < 512 || | |
471 | options.server_key_bits > 32768) | |
472 | { | |
473 | fprintf(stderr, "Bad server key size.\n"); | |
474 | exit(1); | |
475 | } | |
476 | if (options.port < 1 || options.port > 65535) | |
477 | { | |
478 | fprintf(stderr, "Bad port number.\n"); | |
479 | exit(1); | |
480 | } | |
481 | ||
482 | /* Check that there are no remaining arguments. */ | |
483 | if (optind < ac) | |
484 | { | |
485 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
486 | exit(1); | |
487 | } | |
488 | ||
489 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
6a17f9c2 | 490 | |
491 | if (debug_flag && !inetd_flag) | |
492 | log_stderr = 1; | |
493 | ||
494 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
8efc0c15 | 495 | |
496 | debug("sshd version %.100s", SSH_VERSION); | |
497 | ||
498 | sensitive_data.host_key = RSA_new(); | |
499 | /* Load the host key. It must have empty passphrase. */ | |
500 | if (!load_private_key(options.host_key_file, "", | |
501 | sensitive_data.host_key, &comment)) | |
502 | { | |
503 | if (debug_flag) | |
504 | fprintf(stderr, "Could not load host key: %s: %s\n", | |
505 | options.host_key_file, strerror(errno)); | |
506 | else | |
507 | { | |
508 | int err = errno; | |
6a17f9c2 | 509 | /* force logging */ |
510 | log_init(av0, SYSLOG_LEVEL_DEBUG, options.log_facility, log_stderr); | |
8efc0c15 | 511 | error("Could not load host key: %.200s: %.100s", |
512 | options.host_key_file, strerror(err)); | |
513 | } | |
514 | exit(1); | |
515 | } | |
516 | xfree(comment); | |
517 | ||
518 | /* If not in debugging mode, and not started from inetd, disconnect from | |
519 | the controlling terminal, and fork. The original process exits. */ | |
520 | if (!debug_flag && !inetd_flag) | |
521 | { | |
522 | #ifdef TIOCNOTTY | |
523 | int fd; | |
524 | #endif /* TIOCNOTTY */ | |
525 | if (daemon(0, 0) < 0) | |
526 | fatal("daemon() failed: %.200s", strerror(errno)); | |
527 | ||
528 | /* Disconnect from the controlling tty. */ | |
529 | #ifdef TIOCNOTTY | |
530 | fd = open("/dev/tty", O_RDWR|O_NOCTTY); | |
531 | if (fd >= 0) | |
532 | { | |
533 | (void)ioctl(fd, TIOCNOTTY, NULL); | |
534 | close(fd); | |
535 | } | |
536 | #endif /* TIOCNOTTY */ | |
537 | } | |
538 | ||
539 | /* Reinitialize the log (because of the fork above). */ | |
6a17f9c2 | 540 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 541 | |
542 | /* Check that server and host key lengths differ sufficiently. This is | |
543 | necessary to make double encryption work with rsaref. Oh, I hate | |
544 | software patents. I dont know if this can go? Niels */ | |
545 | if (options.server_key_bits > | |
546 | BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED && | |
547 | options.server_key_bits < | |
548 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) | |
549 | { | |
550 | options.server_key_bits = | |
551 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED; | |
552 | debug("Forcing server key to %d bits to make it differ from host key.", | |
553 | options.server_key_bits); | |
554 | } | |
555 | ||
556 | /* Do not display messages to stdout in RSA code. */ | |
557 | rsa_set_verbose(0); | |
558 | ||
559 | /* Initialize the random number generator. */ | |
560 | arc4random_stir(); | |
561 | ||
562 | /* Chdir to the root directory so that the current disk can be unmounted | |
563 | if desired. */ | |
564 | chdir("/"); | |
565 | ||
566 | /* Close connection cleanly after attack. */ | |
567 | cipher_attack_detected = packet_disconnect; | |
568 | ||
569 | /* Start listening for a socket, unless started from inetd. */ | |
570 | if (inetd_flag) | |
571 | { | |
572 | int s1, s2; | |
573 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
574 | s2 = dup(s1); | |
575 | sock_in = dup(0); | |
576 | sock_out = dup(1); | |
577 | /* We intentionally do not close the descriptors 0, 1, and 2 as our | |
578 | code for setting the descriptors won\'t work if ttyfd happens to | |
579 | be one of those. */ | |
580 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
581 | ||
582 | public_key = RSA_new(); | |
583 | sensitive_data.private_key = RSA_new(); | |
584 | /* Generate an rsa key. */ | |
585 | log("Generating %d bit RSA key.", options.server_key_bits); | |
586 | rsa_generate_key(sensitive_data.private_key, public_key, | |
587 | options.server_key_bits); | |
588 | arc4random_stir(); | |
589 | log("RSA key generation complete."); | |
590 | } | |
591 | else | |
592 | { | |
593 | /* Create socket for listening. */ | |
594 | listen_sock = socket(AF_INET, SOCK_STREAM, 0); | |
595 | if (listen_sock < 0) | |
596 | fatal("socket: %.100s", strerror(errno)); | |
597 | ||
598 | /* Set socket options. We try to make the port reusable and have it | |
599 | close as fast as possible without waiting in unnecessary wait states | |
600 | on close. */ | |
601 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, | |
602 | sizeof(on)); | |
603 | linger.l_onoff = 1; | |
604 | linger.l_linger = 5; | |
605 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, (void *)&linger, | |
606 | sizeof(linger)); | |
607 | ||
608 | /* Initialize the socket address. */ | |
609 | memset(&sin, 0, sizeof(sin)); | |
610 | sin.sin_family = AF_INET; | |
611 | sin.sin_addr = options.listen_addr; | |
612 | sin.sin_port = htons(options.port); | |
613 | ||
614 | /* Bind the socket to the desired port. */ | |
615 | if (bind(listen_sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) | |
616 | { | |
617 | error("bind: %.100s", strerror(errno)); | |
618 | shutdown(listen_sock, SHUT_RDWR); | |
619 | close(listen_sock); | |
620 | fatal("Bind to port %d failed.", options.port); | |
621 | } | |
622 | ||
623 | if (!debug_flag) | |
624 | { | |
625 | /* Record our pid in /etc/sshd_pid to make it easier to kill the | |
626 | correct sshd. We don\'t want to do this before the bind above | |
627 | because the bind will fail if there already is a daemon, and this | |
628 | will overwrite any old pid in the file. */ | |
629 | f = fopen(SSH_DAEMON_PID_FILE, "w"); | |
630 | if (f) | |
631 | { | |
632 | fprintf(f, "%u\n", (unsigned int)getpid()); | |
633 | fclose(f); | |
634 | } | |
635 | } | |
636 | ||
637 | /* Start listening on the port. */ | |
638 | log("Server listening on port %d.", options.port); | |
639 | if (listen(listen_sock, 5) < 0) | |
640 | fatal("listen: %.100s", strerror(errno)); | |
641 | ||
642 | public_key = RSA_new(); | |
643 | sensitive_data.private_key = RSA_new(); | |
644 | /* Generate an rsa key. */ | |
645 | log("Generating %d bit RSA key.", options.server_key_bits); | |
646 | rsa_generate_key(sensitive_data.private_key, public_key, | |
647 | options.server_key_bits); | |
648 | arc4random_stir(); | |
649 | log("RSA key generation complete."); | |
650 | ||
651 | /* Schedule server key regeneration alarm. */ | |
652 | signal(SIGALRM, key_regeneration_alarm); | |
653 | alarm(options.key_regeneration_time); | |
654 | ||
655 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
656 | signal(SIGHUP, sighup_handler); | |
657 | signal(SIGTERM, sigterm_handler); | |
658 | signal(SIGQUIT, sigterm_handler); | |
659 | ||
660 | /* Arrange SIGCHLD to be caught. */ | |
661 | signal(SIGCHLD, main_sigchld_handler); | |
662 | ||
663 | /* Stay listening for connections until the system crashes or the | |
664 | daemon is killed with a signal. */ | |
665 | for (;;) | |
666 | { | |
667 | if (received_sighup) | |
668 | sighup_restart(); | |
669 | /* Wait in accept until there is a connection. */ | |
670 | aux = sizeof(sin); | |
671 | newsock = accept(listen_sock, (struct sockaddr *)&sin, &aux); | |
672 | if (received_sighup) | |
673 | sighup_restart(); | |
674 | if (newsock < 0) | |
675 | { | |
676 | if (errno == EINTR) | |
677 | continue; | |
678 | error("accept: %.100s", strerror(errno)); | |
679 | continue; | |
680 | } | |
681 | ||
682 | /* Got connection. Fork a child to handle it, unless we are in | |
683 | debugging mode. */ | |
684 | if (debug_flag) | |
685 | { | |
686 | /* In debugging mode. Close the listening socket, and start | |
687 | processing the connection without forking. */ | |
688 | debug("Server will not fork when running in debugging mode."); | |
689 | close(listen_sock); | |
690 | sock_in = newsock; | |
691 | sock_out = newsock; | |
692 | pid = getpid(); | |
693 | break; | |
694 | } | |
695 | else | |
696 | { | |
697 | /* Normal production daemon. Fork, and have the child process | |
698 | the connection. The parent continues listening. */ | |
699 | if ((pid = fork()) == 0) | |
700 | { | |
701 | /* Child. Close the listening socket, and start using | |
702 | the accepted socket. Reinitialize logging (since our | |
703 | pid has changed). We break out of the loop to handle | |
704 | the connection. */ | |
705 | close(listen_sock); | |
706 | sock_in = newsock; | |
707 | sock_out = newsock; | |
6a17f9c2 | 708 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 709 | break; |
710 | } | |
711 | } | |
712 | ||
713 | /* Parent. Stay in the loop. */ | |
714 | if (pid < 0) | |
715 | error("fork: %.100s", strerror(errno)); | |
716 | else | |
717 | debug("Forked child %d.", pid); | |
718 | ||
719 | /* Mark that the key has been used (it was "given" to the child). */ | |
720 | key_used = 1; | |
721 | ||
722 | arc4random_stir(); | |
723 | ||
724 | /* Close the new socket (the child is now taking care of it). */ | |
725 | close(newsock); | |
726 | } | |
727 | } | |
728 | ||
729 | /* This is the child processing a new connection. */ | |
730 | ||
731 | /* Disable the key regeneration alarm. We will not regenerate the key | |
732 | since we are no longer in a position to give it to anyone. We will | |
733 | not restart on SIGHUP since it no longer makes sense. */ | |
734 | alarm(0); | |
735 | signal(SIGALRM, SIG_DFL); | |
736 | signal(SIGHUP, SIG_DFL); | |
737 | signal(SIGTERM, SIG_DFL); | |
738 | signal(SIGQUIT, SIG_DFL); | |
739 | signal(SIGCHLD, SIG_DFL); | |
740 | ||
741 | /* Set socket options for the connection. We want the socket to close | |
742 | as fast as possible without waiting for anything. If the connection | |
743 | is not a socket, these will do nothing. */ | |
744 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
745 | linger.l_onoff = 1; | |
746 | linger.l_linger = 5; | |
747 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); | |
748 | ||
749 | /* Register our connection. This turns encryption off because we do not | |
750 | have a key. */ | |
751 | packet_set_connection(sock_in, sock_out); | |
752 | ||
e7c0f9d5 | 753 | remote_port = get_remote_port(); |
754 | ||
8efc0c15 | 755 | /* Check whether logins are denied from this host. */ |
756 | #ifdef LIBWRAP | |
757 | { | |
758 | struct request_info req; | |
759 | ||
760 | request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); | |
761 | fromhost(&req); | |
762 | ||
763 | if (!hosts_access(&req)) { | |
764 | close(sock_in); | |
765 | close(sock_out); | |
766 | refuse(&req); | |
767 | } | |
e7c0f9d5 | 768 | log("Connection from %.500s port %d", eval_client(&req), remote_port); |
8efc0c15 | 769 | } |
770 | #else | |
771 | /* Log the connection. */ | |
e7c0f9d5 | 772 | log("Connection from %.100s port %d", get_remote_ipaddr(), remote_port); |
8efc0c15 | 773 | #endif /* LIBWRAP */ |
774 | ||
775 | /* We don\'t want to listen forever unless the other side successfully | |
776 | authenticates itself. So we set up an alarm which is cleared after | |
777 | successful authentication. A limit of zero indicates no limit. | |
778 | Note that we don\'t set the alarm in debugging mode; it is just annoying | |
779 | to have the server exit just when you are about to discover the bug. */ | |
780 | signal(SIGALRM, grace_alarm_handler); | |
781 | if (!debug_flag) | |
782 | alarm(options.login_grace_time); | |
783 | ||
784 | /* Send our protocol version identification. */ | |
785 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
786 | PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION); | |
787 | if (write(sock_out, buf, strlen(buf)) != strlen(buf)) | |
788 | fatal("Could not write ident string."); | |
789 | ||
790 | /* Read other side\'s version identification. */ | |
791 | for (i = 0; i < sizeof(buf) - 1; i++) | |
792 | { | |
793 | if (read(sock_in, &buf[i], 1) != 1) | |
794 | fatal("Did not receive ident string."); | |
795 | if (buf[i] == '\r') | |
796 | { | |
797 | buf[i] = '\n'; | |
798 | buf[i + 1] = 0; | |
799 | break; | |
800 | } | |
801 | if (buf[i] == '\n') | |
802 | { | |
803 | /* buf[i] == '\n' */ | |
804 | buf[i + 1] = 0; | |
805 | break; | |
806 | } | |
807 | } | |
808 | buf[sizeof(buf) - 1] = 0; | |
809 | ||
810 | /* Check that the versions match. In future this might accept several | |
811 | versions and set appropriate flags to handle them. */ | |
812 | if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, | |
813 | remote_version) != 3) | |
814 | { | |
815 | const char *s = "Protocol mismatch.\n"; | |
816 | (void) write(sock_out, s, strlen(s)); | |
817 | close(sock_in); | |
818 | close(sock_out); | |
819 | fatal("Bad protocol version identification: %.100s", buf); | |
820 | } | |
821 | debug("Client protocol version %d.%d; client software version %.100s", | |
822 | remote_major, remote_minor, remote_version); | |
823 | if (remote_major != PROTOCOL_MAJOR) | |
824 | { | |
825 | const char *s = "Protocol major versions differ.\n"; | |
826 | (void) write(sock_out, s, strlen(s)); | |
827 | close(sock_in); | |
828 | close(sock_out); | |
829 | fatal("Protocol major versions differ: %d vs. %d", | |
830 | PROTOCOL_MAJOR, remote_major); | |
831 | } | |
832 | ||
833 | /* Check that the client has sufficiently high software version. */ | |
834 | if (remote_major == 1 && remote_minor < 3) | |
835 | packet_disconnect("Your ssh version is too old and is no longer supported. Please install a newer version."); | |
836 | ||
837 | if (remote_major == 1 && remote_minor == 3) { | |
838 | enable_compat13(); | |
839 | if (strcmp(remote_version, "OpenSSH-1.1") != 0) { | |
840 | debug("Agent forwarding disabled, remote version is not compatible."); | |
841 | no_agent_forwarding_flag = 1; | |
842 | } | |
843 | } | |
844 | ||
e7c0f9d5 | 845 | /* Check that the connection comes from a privileged port. |
846 | Rhosts- and Rhosts-RSA-Authentication only make sense | |
847 | from priviledged programs. | |
848 | Of course, if the intruder has root access on his local machine, | |
849 | he can connect from any port. So do not use these authentication | |
850 | methods from machines that you do not trust. */ | |
851 | if (remote_port >= IPPORT_RESERVED || | |
852 | remote_port < IPPORT_RESERVED / 2) | |
853 | { | |
854 | options.rhosts_authentication = 0; | |
855 | options.rhosts_rsa_authentication = 0; | |
856 | } | |
857 | ||
8efc0c15 | 858 | packet_set_nonblocking(); |
859 | ||
e7c0f9d5 | 860 | /* Handle the connection. */ |
861 | do_connection(); | |
8efc0c15 | 862 | |
863 | #ifdef KRB4 | |
864 | /* Cleanup user's ticket cache file. */ | |
865 | if (options.kerberos_ticket_cleanup) | |
866 | (void) dest_tkt(); | |
867 | #endif /* KRB4 */ | |
868 | ||
869 | /* Cleanup user's local Xauthority file. */ | |
870 | if (xauthfile) unlink(xauthfile); | |
871 | ||
872 | /* The connection has been terminated. */ | |
873 | log("Closing connection to %.100s", inet_ntoa(sin.sin_addr)); | |
874 | ||
5aecb327 | 875 | #ifdef HAVE_LIBPAM |
d813bc69 | 876 | { |
877 | int retval; | |
878 | ||
879 | if (pamh != NULL) | |
880 | { | |
549b3eed | 881 | debug("Closing PAM session."); |
d813bc69 | 882 | retval = pam_close_session((pam_handle_t *)pamh, 0); |
8efc0c15 | 883 | |
549b3eed | 884 | debug("Terminating PAM library."); |
d813bc69 | 885 | if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS) |
886 | log("Cannot release PAM authentication."); | |
8efc0c15 | 887 | |
d813bc69 | 888 | fatal_remove_cleanup(&pam_cleanup_proc, NULL); |
889 | } | |
890 | } | |
5aecb327 | 891 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 892 | |
893 | packet_close(); | |
894 | ||
895 | exit(0); | |
896 | } | |
897 | ||
898 | /* Process an incoming connection. Protocol version identifiers have already | |
899 | been exchanged. This sends server key and performs the key exchange. | |
900 | Server and host keys will no longer be needed after this functions. */ | |
901 | ||
e7c0f9d5 | 902 | void |
903 | do_connection() | |
8efc0c15 | 904 | { |
a61d322f | 905 | int i, len; |
8efc0c15 | 906 | BIGNUM *session_key_int; |
907 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; | |
908 | unsigned char check_bytes[8]; | |
909 | char *user; | |
910 | unsigned int cipher_type, auth_mask, protocol_flags; | |
911 | int plen, slen; | |
912 | u_int32_t rand = 0; | |
913 | ||
914 | /* Generate check bytes that the client must send back in the user packet | |
915 | in order for it to be accepted; this is used to defy ip spoofing | |
916 | attacks. Note that this only works against somebody doing IP spoofing | |
917 | from a remote machine; any machine on the local network can still see | |
918 | outgoing packets and catch the random cookie. This only affects | |
919 | rhosts authentication, and this is one of the reasons why it is | |
920 | inherently insecure. */ | |
921 | for (i = 0; i < 8; i++) { | |
922 | if (i % 4 == 0) | |
923 | rand = arc4random(); | |
924 | check_bytes[i] = rand & 0xff; | |
925 | rand >>= 8; | |
926 | } | |
927 | ||
928 | /* Send our public key. We include in the packet 64 bits of random | |
929 | data that must be matched in the reply in order to prevent IP spoofing. */ | |
930 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
931 | for (i = 0; i < 8; i++) | |
932 | packet_put_char(check_bytes[i]); | |
933 | ||
934 | /* Store our public server RSA key. */ | |
935 | packet_put_int(BN_num_bits(public_key->n)); | |
936 | packet_put_bignum(public_key->e); | |
937 | packet_put_bignum(public_key->n); | |
938 | ||
939 | /* Store our public host RSA key. */ | |
940 | packet_put_int(BN_num_bits(sensitive_data.host_key->n)); | |
941 | packet_put_bignum(sensitive_data.host_key->e); | |
942 | packet_put_bignum(sensitive_data.host_key->n); | |
943 | ||
944 | /* Put protocol flags. */ | |
945 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
946 | ||
947 | /* Declare which ciphers we support. */ | |
948 | packet_put_int(cipher_mask()); | |
949 | ||
950 | /* Declare supported authentication types. */ | |
951 | auth_mask = 0; | |
952 | if (options.rhosts_authentication) | |
953 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
954 | if (options.rhosts_rsa_authentication) | |
955 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
956 | if (options.rsa_authentication) | |
957 | auth_mask |= 1 << SSH_AUTH_RSA; | |
958 | #ifdef KRB4 | |
959 | if (options.kerberos_authentication) | |
960 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
961 | #endif | |
962 | #ifdef AFS | |
963 | if (options.kerberos_tgt_passing) | |
964 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
965 | if (options.afs_token_passing) | |
966 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
967 | #endif | |
968 | if (options.password_authentication) | |
969 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
970 | packet_put_int(auth_mask); | |
971 | ||
972 | /* Send the packet and wait for it to be sent. */ | |
973 | packet_send(); | |
974 | packet_write_wait(); | |
975 | ||
976 | debug("Sent %d bit public key and %d bit host key.", | |
977 | BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n)); | |
978 | ||
979 | /* Read clients reply (cipher type and session key). */ | |
980 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
981 | ||
982 | /* Get cipher type. */ | |
983 | cipher_type = packet_get_char(); | |
984 | ||
985 | /* Get check bytes from the packet. These must match those we sent earlier | |
986 | with the public key packet. */ | |
987 | for (i = 0; i < 8; i++) | |
988 | if (check_bytes[i] != packet_get_char()) | |
989 | packet_disconnect("IP Spoofing check bytes do not match."); | |
990 | ||
991 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
992 | ||
993 | /* Get the encrypted integer. */ | |
994 | session_key_int = BN_new(); | |
995 | packet_get_bignum(session_key_int, &slen); | |
996 | ||
997 | /* Get protocol flags. */ | |
998 | protocol_flags = packet_get_int(); | |
999 | packet_set_protocol_flags(protocol_flags); | |
1000 | ||
1001 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1002 | ||
1003 | /* Decrypt it using our private server key and private host key (key with | |
1004 | larger modulus first). */ | |
1005 | if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) | |
1006 | { | |
1007 | /* Private key has bigger modulus. */ | |
e1a9c08d | 1008 | if (BN_num_bits(sensitive_data.private_key->n) < |
1009 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
1010 | fatal("do_connection: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1011 | BN_num_bits(sensitive_data.private_key->n), | |
1012 | BN_num_bits(sensitive_data.host_key->n), | |
1013 | SSH_KEY_BITS_RESERVED); | |
1014 | } | |
1015 | ||
8efc0c15 | 1016 | rsa_private_decrypt(session_key_int, session_key_int, |
1017 | sensitive_data.private_key); | |
1018 | rsa_private_decrypt(session_key_int, session_key_int, | |
1019 | sensitive_data.host_key); | |
1020 | } | |
1021 | else | |
1022 | { | |
1023 | /* Host key has bigger modulus (or they are equal). */ | |
e1a9c08d | 1024 | if (BN_num_bits(sensitive_data.host_key->n) < |
1025 | BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) { | |
1026 | fatal("do_connection: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d", | |
1027 | BN_num_bits(sensitive_data.host_key->n), | |
1028 | BN_num_bits(sensitive_data.private_key->n), | |
1029 | SSH_KEY_BITS_RESERVED); | |
1030 | } | |
8efc0c15 | 1031 | rsa_private_decrypt(session_key_int, session_key_int, |
1032 | sensitive_data.host_key); | |
1033 | rsa_private_decrypt(session_key_int, session_key_int, | |
1034 | sensitive_data.private_key); | |
1035 | } | |
1036 | ||
1037 | /* Compute session id for this session. */ | |
1038 | compute_session_id(session_id, check_bytes, | |
8efc0c15 | 1039 | sensitive_data.host_key->n, |
8efc0c15 | 1040 | sensitive_data.private_key->n); |
1041 | ||
1042 | /* Extract session key from the decrypted integer. The key is in the | |
1043 | least significant 256 bits of the integer; the first byte of the | |
1044 | key is in the highest bits. */ | |
1045 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
a61d322f | 1046 | len = BN_num_bytes(session_key_int); |
e35c1dc2 | 1047 | if (len < 0 || len > sizeof(session_key)) |
a61d322f | 1048 | fatal("do_connection: bad len: session_key_int %d > sizeof(session_key) %d", |
1049 | len, sizeof(session_key)); | |
1050 | memset(session_key, 0, sizeof(session_key)); | |
1051 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
8efc0c15 | 1052 | |
1053 | /* Xor the first 16 bytes of the session key with the session id. */ | |
1054 | for (i = 0; i < 16; i++) | |
1055 | session_key[i] ^= session_id[i]; | |
1056 | ||
1057 | /* Destroy the decrypted integer. It is no longer needed. */ | |
1058 | BN_clear_free(session_key_int); | |
1059 | ||
1060 | /* Set the session key. From this on all communications will be | |
1061 | encrypted. */ | |
4d195447 | 1062 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); |
8efc0c15 | 1063 | |
1064 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1065 | memset(session_key, 0, sizeof(session_key)); | |
1066 | ||
1067 | debug("Received session key; encryption turned on."); | |
1068 | ||
1069 | /* Send an acknowledgement packet. Note that this packet is sent | |
1070 | encrypted. */ | |
1071 | packet_start(SSH_SMSG_SUCCESS); | |
1072 | packet_send(); | |
1073 | packet_write_wait(); | |
1074 | ||
1075 | /* Get the name of the user that we wish to log in as. */ | |
1076 | packet_read_expect(&plen, SSH_CMSG_USER); | |
1077 | ||
1078 | /* Get the user name. */ | |
1079 | { | |
1080 | int ulen; | |
1081 | user = packet_get_string(&ulen); | |
1082 | packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); | |
1083 | } | |
1084 | ||
1085 | /* Destroy the private and public keys. They will no longer be needed. */ | |
1086 | RSA_free(public_key); | |
1087 | RSA_free(sensitive_data.private_key); | |
1088 | RSA_free(sensitive_data.host_key); | |
1089 | ||
1090 | setproctitle("%s", user); | |
1091 | /* Do the authentication. */ | |
e7c0f9d5 | 1092 | do_authentication(user); |
8efc0c15 | 1093 | } |
1094 | ||
1095 | /* Check if the user is allowed to log in via ssh. If user is listed in | |
1096 | DenyUsers or user's primary group is listed in DenyGroups, false will | |
1097 | be returned. If AllowUsers isn't empty and user isn't listed there, or | |
1098 | if AllowGroups isn't empty and user isn't listed there, false will be | |
1099 | returned. Otherwise true is returned. | |
1100 | XXX This function should also check if user has a valid shell */ | |
1101 | ||
1102 | static int | |
1103 | allowed_user(struct passwd *pw) | |
1104 | { | |
1105 | struct group *grp; | |
1106 | int i; | |
1107 | ||
1108 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ | |
1109 | if (!pw) | |
1110 | return 0; | |
1111 | ||
1112 | /* XXX Should check for valid login shell */ | |
1113 | ||
1114 | /* Return false if user is listed in DenyUsers */ | |
1115 | if (options.num_deny_users > 0) | |
1116 | { | |
1117 | if (!pw->pw_name) | |
1118 | return 0; | |
1119 | for (i = 0; i < options.num_deny_users; i++) | |
1120 | if (match_pattern(pw->pw_name, options.deny_users[i])) | |
1121 | return 0; | |
1122 | } | |
1123 | ||
1124 | /* Return false if AllowUsers isn't empty and user isn't listed there */ | |
1125 | if (options.num_allow_users > 0) | |
1126 | { | |
1127 | if (!pw->pw_name) | |
1128 | return 0; | |
1129 | for (i = 0; i < options.num_allow_users; i++) | |
1130 | if (match_pattern(pw->pw_name, options.allow_users[i])) | |
1131 | break; | |
1132 | /* i < options.num_allow_users iff we break for loop */ | |
1133 | if (i >= options.num_allow_users) | |
1134 | return 0; | |
1135 | } | |
1136 | ||
1137 | /* Get the primary group name if we need it. Return false if it fails */ | |
1138 | if (options.num_deny_groups > 0 || options.num_allow_groups > 0 ) | |
1139 | { | |
1140 | grp = getgrgid(pw->pw_gid); | |
1141 | if (!grp) | |
1142 | return 0; | |
1143 | ||
1144 | /* Return false if user's group is listed in DenyGroups */ | |
1145 | if (options.num_deny_groups > 0) | |
1146 | { | |
1147 | if (!grp->gr_name) | |
1148 | return 0; | |
1149 | for (i = 0; i < options.num_deny_groups; i++) | |
1150 | if (match_pattern(grp->gr_name, options.deny_groups[i])) | |
1151 | return 0; | |
1152 | } | |
1153 | ||
1154 | /* Return false if AllowGroups isn't empty and user's group isn't | |
1155 | listed there */ | |
1156 | if (options.num_allow_groups > 0) | |
1157 | { | |
1158 | if (!grp->gr_name) | |
1159 | return 0; | |
1160 | for (i = 0; i < options.num_allow_groups; i++) | |
1161 | if (match_pattern(grp->gr_name, options.allow_groups[i])) | |
1162 | break; | |
1163 | /* i < options.num_allow_groups iff we break for loop */ | |
1164 | if (i >= options.num_allow_groups) | |
1165 | return 0; | |
1166 | } | |
1167 | } | |
1168 | ||
1169 | /* We found no reason not to let this user try to log on... */ | |
1170 | return 1; | |
1171 | } | |
1172 | ||
1173 | /* Performs authentication of an incoming connection. Session key has already | |
1174 | been exchanged and encryption is enabled. User is the user name to log | |
e7c0f9d5 | 1175 | in as (received from the client). */ |
8efc0c15 | 1176 | |
1177 | void | |
e7c0f9d5 | 1178 | do_authentication(char *user) |
8efc0c15 | 1179 | { |
8efc0c15 | 1180 | struct passwd *pw, pwcopy; |
e7c0f9d5 | 1181 | |
8efc0c15 | 1182 | #ifdef AFS |
1183 | /* If machine has AFS, set process authentication group. */ | |
1184 | if (k_hasafs()) { | |
1185 | k_setpag(); | |
1186 | k_unlog(); | |
1187 | } | |
1188 | #endif /* AFS */ | |
1189 | ||
1190 | /* Verify that the user is a valid user. */ | |
1191 | pw = getpwnam(user); | |
8efc0c15 | 1192 | if (!pw || !allowed_user(pw)) |
e7c0f9d5 | 1193 | do_fake_authloop(user); |
1194 | ||
8efc0c15 | 1195 | /* Take a copy of the returned structure. */ |
1196 | memset(&pwcopy, 0, sizeof(pwcopy)); | |
1197 | pwcopy.pw_name = xstrdup(pw->pw_name); | |
1198 | pwcopy.pw_passwd = xstrdup(pw->pw_passwd); | |
1199 | pwcopy.pw_uid = pw->pw_uid; | |
1200 | pwcopy.pw_gid = pw->pw_gid; | |
1201 | pwcopy.pw_dir = xstrdup(pw->pw_dir); | |
1202 | pwcopy.pw_shell = xstrdup(pw->pw_shell); | |
1203 | pw = &pwcopy; | |
1204 | ||
5aecb327 | 1205 | #ifdef HAVE_LIBPAM |
c75a1a66 | 1206 | { |
1207 | int pam_retval; | |
1208 | ||
1209 | debug("Starting up PAM with username \"%.200s\"", pw->pw_name); | |
e7c0f9d5 | 1210 | |
c75a1a66 | 1211 | pam_retval = pam_start("sshd", pw->pw_name, &conv, (pam_handle_t**)&pamh); |
1212 | if (pam_retval != PAM_SUCCESS) | |
1213 | fatal("PAM initialisation failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
e7c0f9d5 | 1214 | |
c75a1a66 | 1215 | fatal_add_cleanup(&pam_cleanup_proc, NULL); |
1216 | } | |
5aecb327 | 1217 | #endif |
0183ea1c | 1218 | |
8efc0c15 | 1219 | /* If we are not running as root, the user must have the same uid as the |
1220 | server. */ | |
1221 | if (getuid() != 0 && pw->pw_uid != getuid()) | |
1222 | packet_disconnect("Cannot change user when server not running as root."); | |
1223 | ||
1224 | debug("Attempting authentication for %.100s.", user); | |
1225 | ||
1226 | /* If the user has no password, accept authentication immediately. */ | |
1227 | if (options.password_authentication && | |
1228 | #ifdef KRB4 | |
1229 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && | |
1230 | #endif /* KRB4 */ | |
1231 | auth_password(pw, "")) | |
1232 | { | |
1233 | /* Authentication with empty password succeeded. */ | |
1234 | debug("Login for user %.100s accepted without authentication.", user); | |
e7c0f9d5 | 1235 | } else { |
1236 | /* Loop until the user has been authenticated or the connection is closed, | |
1237 | do_authloop() returns only if authentication is successfull */ | |
1238 | do_authloop(pw); | |
8efc0c15 | 1239 | } |
e7c0f9d5 | 1240 | |
1241 | /* XXX log unified auth message */ | |
1242 | ||
1243 | /* Check if the user is logging in as root and root logins are disallowed. */ | |
1244 | if (pw->pw_uid == 0 && !options.permit_root_login) | |
8efc0c15 | 1245 | { |
e7c0f9d5 | 1246 | if (forced_command) |
1247 | log("Root login accepted for forced command."); | |
1248 | else | |
1249 | packet_disconnect("ROOT LOGIN REFUSED FROM %.200s", | |
1250 | get_canonical_hostname()); | |
8efc0c15 | 1251 | } |
1252 | ||
e7c0f9d5 | 1253 | /* The user has been authenticated and accepted. */ |
1254 | packet_start(SSH_SMSG_SUCCESS); | |
1255 | packet_send(); | |
1256 | packet_write_wait(); | |
8efc0c15 | 1257 | |
e7c0f9d5 | 1258 | /* Perform session preparation. */ |
1259 | do_authenticated(pw); | |
1260 | } | |
8efc0c15 | 1261 | |
e7c0f9d5 | 1262 | #define MAX_AUTH_FAILURES 5 |
1263 | ||
1264 | /* read packets and try to authenticate local user *pw. | |
1265 | return if authentication is successfull */ | |
1266 | void | |
1267 | do_authloop(struct passwd *pw) | |
1268 | { | |
1269 | int authentication_failures = 0; | |
4d195447 | 1270 | unsigned int bits; |
e7c0f9d5 | 1271 | BIGNUM *client_host_key_e, *client_host_key_n; |
1272 | BIGNUM *n; | |
c75a1a66 | 1273 | char *client_user = NULL, *password = NULL; |
e7c0f9d5 | 1274 | int plen, dlen, nlen, ulen, elen; |
c75a1a66 | 1275 | #ifdef HAVE_LIBPAM |
1276 | int pam_retval; | |
1277 | #endif /* HAVE_LIBPAM */ | |
e7c0f9d5 | 1278 | |
1279 | /* Indicate that authentication is needed. */ | |
1280 | packet_start(SSH_SMSG_FAILURE); | |
1281 | packet_send(); | |
1282 | packet_write_wait(); | |
1283 | ||
1284 | for (;;) { | |
1285 | int authenticated = 0; | |
1286 | ||
1287 | /* Get a packet from the client. */ | |
1288 | int type = packet_read(&plen); | |
1289 | ||
1290 | /* Process the packet. */ | |
1291 | switch (type) | |
1292 | { | |
1293 | #ifdef AFS | |
1294 | case SSH_CMSG_HAVE_KERBEROS_TGT: | |
1295 | if (!options.kerberos_tgt_passing) | |
1296 | { | |
8efc0c15 | 1297 | /* packet_get_all(); */ |
e7c0f9d5 | 1298 | log("Kerberos tgt passing disabled."); |
8efc0c15 | 1299 | break; |
1300 | } | |
e7c0f9d5 | 1301 | else { |
1302 | /* Accept Kerberos tgt. */ | |
1303 | char *tgt = packet_get_string(&dlen); | |
1304 | packet_integrity_check(plen, 4 + dlen, type); | |
1305 | if (!auth_kerberos_tgt(pw, tgt)) | |
1306 | debug("Kerberos tgt REFUSED for %s", pw->pw_name); | |
1307 | xfree(tgt); | |
1308 | } | |
1309 | continue; | |
1310 | ||
1311 | case SSH_CMSG_HAVE_AFS_TOKEN: | |
1312 | if (!options.afs_token_passing || !k_hasafs()) { | |
1313 | /* packet_get_all(); */ | |
1314 | log("AFS token passing disabled."); | |
1315 | break; | |
1316 | } | |
1317 | else { | |
1318 | /* Accept AFS token. */ | |
1319 | char *token_string = packet_get_string(&dlen); | |
1320 | packet_integrity_check(plen, 4 + dlen, type); | |
1321 | if (!auth_afs_token(pw, token_string)) | |
1322 | debug("AFS token REFUSED for %s", pw->pw_name); | |
1323 | xfree(token_string); | |
1324 | } | |
1325 | continue; | |
8efc0c15 | 1326 | #endif /* AFS */ |
8efc0c15 | 1327 | |
e7c0f9d5 | 1328 | #ifdef KRB4 |
1329 | case SSH_CMSG_AUTH_KERBEROS: | |
1330 | if (!options.kerberos_authentication) | |
1331 | { | |
1332 | /* packet_get_all(); */ | |
1333 | log("Kerberos authentication disabled."); | |
1334 | break; | |
8efc0c15 | 1335 | } |
e7c0f9d5 | 1336 | else { |
1337 | /* Try Kerberos v4 authentication. */ | |
1338 | KTEXT_ST auth; | |
1339 | char *tkt_user = NULL; | |
1340 | char *kdata = packet_get_string((unsigned int *)&auth.length); | |
1341 | packet_integrity_check(plen, 4 + auth.length, type); | |
1342 | ||
1343 | if (auth.length < MAX_KTXT_LEN) | |
1344 | memcpy(auth.dat, kdata, auth.length); | |
1345 | xfree(kdata); | |
8efc0c15 | 1346 | |
e7c0f9d5 | 1347 | authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user); |
1348 | ||
1349 | log("Kerberos authentication %s%s for account %s from %s", | |
1350 | authenticated ? "accepted " : "failed", | |
1351 | tkt_user != NULL ? tkt_user : "", | |
1352 | pw->pw_name, get_canonical_hostname()); | |
1353 | if (authenticated) | |
1354 | xfree(tkt_user); | |
1355 | } | |
1356 | break; | |
1357 | #endif /* KRB4 */ | |
1358 | ||
1359 | case SSH_CMSG_AUTH_RHOSTS: | |
1360 | if (!options.rhosts_authentication) | |
8efc0c15 | 1361 | { |
e7c0f9d5 | 1362 | log("Rhosts authentication disabled."); |
1363 | break; | |
8efc0c15 | 1364 | } |
e7c0f9d5 | 1365 | |
1366 | /* Get client user name. Note that we just have to trust the client; | |
1367 | this is one reason why rhosts authentication is insecure. | |
1368 | (Another is IP-spoofing on a local network.) */ | |
1369 | client_user = packet_get_string(&dlen); | |
1370 | packet_integrity_check(plen, 4 + dlen, type); | |
1371 | ||
1372 | /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ | |
1373 | authenticated = auth_rhosts(pw, client_user); | |
8efc0c15 | 1374 | |
e7c0f9d5 | 1375 | log("Rhosts authentication %s for %.100s, remote %.100s on %.700s.", |
1376 | authenticated ? "accepted" : "failed", | |
1377 | pw->pw_name, client_user, get_canonical_hostname()); | |
5aecb327 | 1378 | #ifndef HAVE_LIBPAM |
e7c0f9d5 | 1379 | xfree(client_user); |
5aecb327 | 1380 | #endif /* HAVE_LIBPAM */ |
e7c0f9d5 | 1381 | break; |
1382 | ||
1383 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
1384 | if (!options.rhosts_rsa_authentication) | |
8efc0c15 | 1385 | { |
e7c0f9d5 | 1386 | log("Rhosts with RSA authentication disabled."); |
1387 | break; | |
8efc0c15 | 1388 | } |
e7c0f9d5 | 1389 | |
1390 | /* Get client user name. Note that we just have to trust | |
1391 | the client; root on the client machine can claim to be | |
1392 | any user. */ | |
1393 | client_user = packet_get_string(&ulen); | |
1394 | ||
1395 | /* Get the client host key. */ | |
1396 | client_host_key_e = BN_new(); | |
1397 | client_host_key_n = BN_new(); | |
4d195447 | 1398 | bits = packet_get_int(); |
e7c0f9d5 | 1399 | packet_get_bignum(client_host_key_e, &elen); |
1400 | packet_get_bignum(client_host_key_n, &nlen); | |
4d195447 | 1401 | |
1402 | if (bits != BN_num_bits(client_host_key_n)) | |
1403 | error("Warning: keysize mismatch for client_host_key: " | |
1404 | "actual %d, announced %s", BN_num_bits(client_host_key_n), bits); | |
e7c0f9d5 | 1405 | |
1406 | packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); | |
1407 | ||
4d195447 | 1408 | authenticated = auth_rhosts_rsa(pw, client_user, |
e7c0f9d5 | 1409 | client_host_key_e, client_host_key_n); |
1410 | log("Rhosts authentication %s for %.100s, remote %.100s.", | |
1411 | authenticated ? "accepted" : "failed", | |
1412 | pw->pw_name, client_user); | |
5aecb327 | 1413 | #ifndef HAVE_LIBPAM |
e7c0f9d5 | 1414 | xfree(client_user); |
5aecb327 | 1415 | #endif /* HAVE_LIBPAM */ |
e7c0f9d5 | 1416 | BN_clear_free(client_host_key_e); |
1417 | BN_clear_free(client_host_key_n); | |
1418 | break; | |
1419 | ||
1420 | case SSH_CMSG_AUTH_RSA: | |
1421 | if (!options.rsa_authentication) | |
8efc0c15 | 1422 | { |
e7c0f9d5 | 1423 | log("RSA authentication disabled."); |
1424 | break; | |
8efc0c15 | 1425 | } |
e7c0f9d5 | 1426 | |
1427 | /* RSA authentication requested. */ | |
1428 | n = BN_new(); | |
1429 | packet_get_bignum(n, &nlen); | |
1430 | packet_integrity_check(plen, nlen, type); | |
1431 | authenticated = auth_rsa(pw, n); | |
1432 | BN_clear_free(n); | |
1433 | log("RSA authentication %s for %.100s.", | |
1434 | authenticated ? "accepted" : "failed", | |
1435 | pw->pw_name); | |
1436 | break; | |
1437 | ||
1438 | case SSH_CMSG_AUTH_PASSWORD: | |
1439 | if (!options.password_authentication) | |
8efc0c15 | 1440 | { |
e7c0f9d5 | 1441 | log("Password authentication disabled."); |
1442 | break; | |
8efc0c15 | 1443 | } |
e7c0f9d5 | 1444 | |
1445 | /* Read user password. It is in plain text, but was transmitted | |
1446 | over the encrypted channel so it is not visible to an outside | |
1447 | observer. */ | |
1448 | password = packet_get_string(&dlen); | |
1449 | packet_integrity_check(plen, 4 + dlen, type); | |
1450 | ||
5aecb327 | 1451 | #ifdef HAVE_LIBPAM |
c75a1a66 | 1452 | /* Do PAM auth with password */ |
e7c0f9d5 | 1453 | pampasswd = password; |
c75a1a66 | 1454 | pam_retval = pam_authenticate((pam_handle_t *)pamh, 0); |
e7c0f9d5 | 1455 | if (pam_retval == PAM_SUCCESS) |
1456 | { | |
c75a1a66 | 1457 | log("PAM Password authentication accepted for user \"%.100s\"", pw->pw_name); |
e7c0f9d5 | 1458 | authenticated = 1; |
1459 | break; | |
1460 | } | |
c75a1a66 | 1461 | |
1462 | log("PAM Password authentication for \"%.100s\" failed: %s", | |
1463 | pw->pw_name, pam_strerror((pam_handle_t *)pamh, pam_retval)); | |
e7c0f9d5 | 1464 | break; |
5aecb327 | 1465 | #else /* HAVE_LIBPAM */ |
e7c0f9d5 | 1466 | /* Try authentication with the password. */ |
1467 | authenticated = auth_password(pw, password); | |
8efc0c15 | 1468 | |
e7c0f9d5 | 1469 | memset(password, 0, strlen(password)); |
1470 | xfree(password); | |
8efc0c15 | 1471 | break; |
e7c0f9d5 | 1472 | #endif /* HAVE_LIBPAM */ |
1473 | ||
1474 | case SSH_CMSG_AUTH_TIS: | |
1475 | /* TIS Authentication is unsupported */ | |
1476 | log("TIS authentication disabled."); | |
1477 | break; | |
1478 | ||
1479 | default: | |
1480 | /* Any unknown messages will be ignored (and failure returned) | |
1481 | during authentication. */ | |
1482 | log("Unknown message during authentication: type %d", type); | |
1483 | break; /* Respond with a failure message. */ | |
8efc0c15 | 1484 | } |
e35c1dc2 | 1485 | |
e7c0f9d5 | 1486 | if (authenticated) |
1487 | break; | |
1488 | if (++authentication_failures >= MAX_AUTH_FAILURES) | |
1489 | packet_disconnect("Too many authentication failures for %.100s from %.200s", | |
1490 | pw->pw_name, get_canonical_hostname()); | |
1491 | /* Send a message indicating that the authentication attempt failed. */ | |
1492 | packet_start(SSH_SMSG_FAILURE); | |
1493 | packet_send(); | |
1494 | packet_write_wait(); | |
1495 | } | |
8efc0c15 | 1496 | |
5aecb327 | 1497 | #ifdef HAVE_LIBPAM |
e7c0f9d5 | 1498 | do_pam_account_and_session(pw->pw_name, client_user, get_canonical_hostname()); |
d813bc69 | 1499 | |
1500 | /* Clean up */ | |
1501 | if (client_user != NULL) | |
1502 | xfree(client_user); | |
1503 | ||
1504 | if (password != NULL) | |
1505 | { | |
1506 | memset(password, 0, strlen(password)); | |
1507 | xfree(password); | |
1508 | } | |
5aecb327 | 1509 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 1510 | } |
1511 | ||
e7c0f9d5 | 1512 | /* The user does not exist or access is denied, |
1513 | but fake indication that authentication is needed. */ | |
1514 | void | |
1515 | do_fake_authloop(char *user) | |
0183ea1c | 1516 | { |
1517 | int authentication_failures = 0; | |
e7c0f9d5 | 1518 | |
1519 | /* Indicate that authentication is needed. */ | |
0183ea1c | 1520 | packet_start(SSH_SMSG_FAILURE); |
1521 | packet_send(); | |
1522 | packet_write_wait(); | |
1523 | ||
1524 | /* Keep reading packets, and always respond with a failure. This is to | |
1525 | avoid disclosing whether such a user really exists. */ | |
e7c0f9d5 | 1526 | for (;;) |
0183ea1c | 1527 | { |
e7c0f9d5 | 1528 | /* Read a packet. This will not return if the client disconnects. */ |
1529 | int plen; | |
1530 | int type = packet_read(&plen); | |
1531 | #ifdef SKEY | |
1532 | int passw_len; | |
1533 | char *password, *skeyinfo; | |
1534 | if (options.password_authentication && | |
1535 | options.skey_authentication == 1 && | |
1536 | type == SSH_CMSG_AUTH_PASSWORD && | |
1537 | (password = packet_get_string(&passw_len)) != NULL && | |
1538 | passw_len == 5 && | |
1539 | strncasecmp(password, "s/key", 5) == 0 && | |
1540 | (skeyinfo = skey_fake_keyinfo(user)) != NULL ){ | |
1541 | /* Send a fake s/key challenge. */ | |
1542 | packet_send_debug(skeyinfo); | |
1543 | } | |
1544 | #endif | |
1545 | if (++authentication_failures >= MAX_AUTH_FAILURES) | |
1546 | packet_disconnect("Too many authentication failures for %.100s from %.200s", | |
1547 | user, get_canonical_hostname()); | |
1548 | /* Send failure. This should be indistinguishable from a failed | |
1549 | authentication. */ | |
1550 | packet_start(SSH_SMSG_FAILURE); | |
1551 | packet_send(); | |
1552 | packet_write_wait(); | |
0183ea1c | 1553 | } |
0183ea1c | 1554 | /*NOTREACHED*/ |
1555 | abort(); | |
1556 | } | |
1557 | ||
e7c0f9d5 | 1558 | |
6a17f9c2 | 1559 | /* Remove local Xauthority file. */ |
1560 | static void | |
1561 | xauthfile_cleanup_proc(void *ignore) | |
1562 | { | |
1563 | debug("xauthfile_cleanup_proc called"); | |
1564 | ||
1565 | if (xauthfile != NULL) { | |
1566 | unlink(xauthfile); | |
1567 | xfree(xauthfile); | |
1568 | xauthfile = NULL; | |
1569 | } | |
1570 | } | |
1571 | ||
8efc0c15 | 1572 | /* Prepares for an interactive session. This is called after the user has |
1573 | been successfully authenticated. During this message exchange, pseudo | |
1574 | terminals are allocated, X11, TCP/IP, and authentication agent forwardings | |
1575 | are requested, etc. */ | |
1576 | ||
1577 | void do_authenticated(struct passwd *pw) | |
1578 | { | |
1579 | int type; | |
1580 | int compression_level = 0, enable_compression_after_reply = 0; | |
1581 | int have_pty = 0, ptyfd = -1, ttyfd = -1, xauthfd = -1; | |
1582 | int row, col, xpixel, ypixel, screen; | |
1583 | char ttyname[64]; | |
1584 | char *command, *term = NULL, *display = NULL, *proto = NULL, *data = NULL; | |
1585 | struct group *grp; | |
1586 | gid_t tty_gid; | |
1587 | mode_t tty_mode; | |
1588 | int n_bytes; | |
1589 | ||
1590 | /* Cancel the alarm we set to limit the time taken for authentication. */ | |
1591 | alarm(0); | |
1592 | ||
1593 | /* Inform the channel mechanism that we are the server side and that | |
1594 | the client may request to connect to any port at all. (The user could | |
1595 | do it anyway, and we wouldn\'t know what is permitted except by the | |
1596 | client telling us, so we can equally well trust the client not to request | |
1597 | anything bogus.) */ | |
1598 | channel_permit_all_opens(); | |
1599 | ||
1600 | /* We stay in this loop until the client requests to execute a shell or a | |
1601 | command. */ | |
1602 | while (1) | |
1603 | { | |
1604 | int plen, dlen; | |
1605 | ||
1606 | /* Get a packet from the client. */ | |
1607 | type = packet_read(&plen); | |
1608 | ||
1609 | /* Process the packet. */ | |
1610 | switch (type) | |
1611 | { | |
1612 | case SSH_CMSG_REQUEST_COMPRESSION: | |
1613 | packet_integrity_check(plen, 4, type); | |
1614 | compression_level = packet_get_int(); | |
1615 | if (compression_level < 1 || compression_level > 9) | |
1616 | { | |
1617 | packet_send_debug("Received illegal compression level %d.", | |
1618 | compression_level); | |
1619 | goto fail; | |
1620 | } | |
1621 | /* Enable compression after we have responded with SUCCESS. */ | |
1622 | enable_compression_after_reply = 1; | |
1623 | break; | |
1624 | ||
1625 | case SSH_CMSG_REQUEST_PTY: | |
1626 | if (no_pty_flag) | |
1627 | { | |
1628 | debug("Allocating a pty not permitted for this authentication."); | |
1629 | goto fail; | |
1630 | } | |
1631 | if (have_pty) | |
1632 | packet_disconnect("Protocol error: you already have a pty."); | |
1633 | ||
1634 | debug("Allocating pty."); | |
1635 | ||
1636 | /* Allocate a pty and open it. */ | |
1637 | if (!pty_allocate(&ptyfd, &ttyfd, ttyname)) | |
1638 | { | |
1639 | error("Failed to allocate pty."); | |
1640 | goto fail; | |
1641 | } | |
1642 | ||
1643 | /* Determine the group to make the owner of the tty. */ | |
1644 | grp = getgrnam("tty"); | |
1645 | if (grp) | |
1646 | { | |
1647 | tty_gid = grp->gr_gid; | |
1648 | tty_mode = S_IRUSR|S_IWUSR|S_IWGRP; | |
1649 | } | |
1650 | else | |
1651 | { | |
1652 | tty_gid = pw->pw_gid; | |
1653 | tty_mode = S_IRUSR|S_IWUSR|S_IWGRP|S_IWOTH; | |
1654 | } | |
1655 | ||
1656 | /* Change ownership of the tty. */ | |
1657 | if (chown(ttyname, pw->pw_uid, tty_gid) < 0) | |
1658 | fatal("chown(%.100s, %d, %d) failed: %.100s", | |
1659 | ttyname, pw->pw_uid, tty_gid, strerror(errno)); | |
1660 | if (chmod(ttyname, tty_mode) < 0) | |
1661 | fatal("chmod(%.100s, 0%o) failed: %.100s", | |
1662 | ttyname, tty_mode, strerror(errno)); | |
1663 | ||
1664 | /* Get TERM from the packet. Note that the value may be of arbitrary | |
1665 | length. */ | |
1666 | ||
1667 | term = packet_get_string(&dlen); | |
1668 | packet_integrity_check(dlen, strlen(term), type); | |
1669 | /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */ | |
1670 | /* Remaining bytes */ | |
1671 | n_bytes = plen - (4 + dlen + 4*4); | |
1672 | ||
1673 | if (strcmp(term, "") == 0) | |
1674 | term = NULL; | |
1675 | ||
1676 | /* Get window size from the packet. */ | |
1677 | row = packet_get_int(); | |
1678 | col = packet_get_int(); | |
1679 | xpixel = packet_get_int(); | |
1680 | ypixel = packet_get_int(); | |
1681 | pty_change_window_size(ptyfd, row, col, xpixel, ypixel); | |
1682 | ||
1683 | /* Get tty modes from the packet. */ | |
1684 | tty_parse_modes(ttyfd, &n_bytes); | |
1685 | packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); | |
1686 | ||
1687 | /* Indicate that we now have a pty. */ | |
1688 | have_pty = 1; | |
1689 | break; | |
1690 | ||
1691 | case SSH_CMSG_X11_REQUEST_FORWARDING: | |
1692 | if (!options.x11_forwarding) | |
1693 | { | |
1694 | packet_send_debug("X11 forwarding disabled in server configuration file."); | |
1695 | goto fail; | |
1696 | } | |
1697 | #ifdef XAUTH_PATH | |
1698 | if (no_x11_forwarding_flag) | |
1699 | { | |
1700 | packet_send_debug("X11 forwarding not permitted for this authentication."); | |
1701 | goto fail; | |
1702 | } | |
1703 | debug("Received request for X11 forwarding with auth spoofing."); | |
1704 | if (display) | |
1705 | packet_disconnect("Protocol error: X11 display already set."); | |
1706 | { | |
1707 | int proto_len, data_len; | |
1708 | proto = packet_get_string(&proto_len); | |
1709 | data = packet_get_string(&data_len); | |
1710 | packet_integrity_check(plen, 4+proto_len + 4+data_len + 4, type); | |
1711 | } | |
1712 | if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER) | |
1713 | screen = packet_get_int(); | |
1714 | else | |
1715 | screen = 0; | |
1716 | display = x11_create_display_inet(screen); | |
1717 | if (!display) | |
1718 | goto fail; | |
1719 | ||
1720 | /* Setup to always have a local .Xauthority. */ | |
1721 | xauthfile = xmalloc(MAXPATHLEN); | |
1722 | snprintf(xauthfile, MAXPATHLEN, "/tmp/XauthXXXXXX"); | |
1723 | ||
1724 | if ((xauthfd = mkstemp(xauthfile)) != -1) { | |
1725 | fchown(xauthfd, pw->pw_uid, pw->pw_gid); | |
1726 | close(xauthfd); | |
6a17f9c2 | 1727 | fatal_add_cleanup(xauthfile_cleanup_proc, NULL); |
8efc0c15 | 1728 | } |
1729 | else { | |
1730 | xfree(xauthfile); | |
1731 | xauthfile = NULL; | |
1732 | } | |
1733 | break; | |
1734 | #else /* XAUTH_PATH */ | |
1735 | /* No xauth program; we won't accept forwarding with spoofing. */ | |
1736 | packet_send_debug("No xauth program; cannot forward with spoofing."); | |
1737 | goto fail; | |
1738 | #endif /* XAUTH_PATH */ | |
1739 | ||
1740 | case SSH_CMSG_AGENT_REQUEST_FORWARDING: | |
1741 | if (no_agent_forwarding_flag) | |
1742 | { | |
1743 | debug("Authentication agent forwarding not permitted for this authentication."); | |
1744 | goto fail; | |
1745 | } | |
1746 | debug("Received authentication agent forwarding request."); | |
1747 | auth_input_request_forwarding(pw); | |
1748 | break; | |
1749 | ||
1750 | case SSH_CMSG_PORT_FORWARD_REQUEST: | |
1751 | if (no_port_forwarding_flag) | |
1752 | { | |
1753 | debug("Port forwarding not permitted for this authentication."); | |
1754 | goto fail; | |
1755 | } | |
1756 | debug("Received TCP/IP port forwarding request."); | |
1757 | channel_input_port_forward_request(pw->pw_uid == 0); | |
1758 | break; | |
1759 | ||
1760 | case SSH_CMSG_EXEC_SHELL: | |
1761 | /* Set interactive/non-interactive mode. */ | |
1762 | packet_set_interactive(have_pty || display != NULL, | |
1763 | options.keepalives); | |
1764 | ||
1765 | if (forced_command != NULL) | |
1766 | goto do_forced_command; | |
1767 | debug("Forking shell."); | |
1768 | packet_integrity_check(plen, 0, type); | |
1769 | if (have_pty) | |
1770 | do_exec_pty(NULL, ptyfd, ttyfd, ttyname, pw, term, display, proto, | |
1771 | data); | |
1772 | else | |
1773 | do_exec_no_pty(NULL, pw, display, proto, data); | |
1774 | return; | |
1775 | ||
1776 | case SSH_CMSG_EXEC_CMD: | |
1777 | /* Set interactive/non-interactive mode. */ | |
1778 | packet_set_interactive(have_pty || display != NULL, | |
1779 | options.keepalives); | |
1780 | ||
1781 | if (forced_command != NULL) | |
1782 | goto do_forced_command; | |
1783 | /* Get command from the packet. */ | |
1784 | { | |
1785 | int dlen; | |
1786 | command = packet_get_string(&dlen); | |
1787 | debug("Executing command '%.500s'", command); | |
1788 | packet_integrity_check(plen, 4 + dlen, type); | |
1789 | } | |
1790 | if (have_pty) | |
1791 | do_exec_pty(command, ptyfd, ttyfd, ttyname, pw, term, display, | |
1792 | proto, data); | |
1793 | else | |
1794 | do_exec_no_pty(command, pw, display, proto, data); | |
1795 | xfree(command); | |
1796 | return; | |
1797 | ||
1798 | case SSH_CMSG_MAX_PACKET_SIZE: | |
1799 | debug("The server does not support limiting packet size."); | |
1800 | goto fail; | |
1801 | ||
1802 | default: | |
1803 | /* Any unknown messages in this phase are ignored, and a failure | |
1804 | message is returned. */ | |
1805 | log("Unknown packet type received after authentication: %d", type); | |
1806 | goto fail; | |
1807 | } | |
1808 | ||
1809 | /* The request was successfully processed. */ | |
1810 | packet_start(SSH_SMSG_SUCCESS); | |
1811 | packet_send(); | |
1812 | packet_write_wait(); | |
1813 | ||
1814 | /* Enable compression now that we have replied if appropriate. */ | |
1815 | if (enable_compression_after_reply) | |
1816 | { | |
1817 | enable_compression_after_reply = 0; | |
1818 | packet_start_compression(compression_level); | |
1819 | } | |
1820 | ||
1821 | continue; | |
1822 | ||
1823 | fail: | |
1824 | /* The request failed. */ | |
1825 | packet_start(SSH_SMSG_FAILURE); | |
1826 | packet_send(); | |
1827 | packet_write_wait(); | |
1828 | continue; | |
1829 | ||
1830 | do_forced_command: | |
1831 | /* There is a forced command specified for this login. Execute it. */ | |
1832 | debug("Executing forced command: %.900s", forced_command); | |
1833 | if (have_pty) | |
1834 | do_exec_pty(forced_command, ptyfd, ttyfd, ttyname, pw, term, display, | |
1835 | proto, data); | |
1836 | else | |
1837 | do_exec_no_pty(forced_command, pw, display, proto, data); | |
1838 | return; | |
1839 | } | |
1840 | } | |
1841 | ||
1842 | /* This is called to fork and execute a command when we have no tty. This | |
1843 | will call do_child from the child, and server_loop from the parent after | |
1844 | setting up file descriptors and such. */ | |
1845 | ||
1846 | void do_exec_no_pty(const char *command, struct passwd *pw, | |
1847 | const char *display, const char *auth_proto, | |
1848 | const char *auth_data) | |
1849 | { | |
1850 | int pid; | |
1851 | ||
1852 | #ifdef USE_PIPES | |
1853 | int pin[2], pout[2], perr[2]; | |
1854 | /* Allocate pipes for communicating with the program. */ | |
1855 | if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) | |
1856 | packet_disconnect("Could not create pipes: %.100s", | |
1857 | strerror(errno)); | |
1858 | #else /* USE_PIPES */ | |
1859 | int inout[2], err[2]; | |
1860 | /* Uses socket pairs to communicate with the program. */ | |
1861 | if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || | |
1862 | socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) | |
1863 | packet_disconnect("Could not create socket pairs: %.100s", | |
1864 | strerror(errno)); | |
1865 | #endif /* USE_PIPES */ | |
1866 | ||
1867 | setproctitle("%s@notty", pw->pw_name); | |
1868 | ||
1869 | /* Fork the child. */ | |
1870 | if ((pid = fork()) == 0) | |
1871 | { | |
1872 | /* Child. Reinitialize the log since the pid has changed. */ | |
6a17f9c2 | 1873 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 1874 | |
1875 | /* Create a new session and process group since the 4.4BSD setlogin() | |
1876 | affects the entire process group. */ | |
1877 | if (setsid() < 0) | |
1878 | error("setsid failed: %.100s", strerror(errno)); | |
1879 | ||
1880 | #ifdef USE_PIPES | |
1881 | /* Redirect stdin. We close the parent side of the socket pair, | |
1882 | and make the child side the standard input. */ | |
1883 | close(pin[1]); | |
1884 | if (dup2(pin[0], 0) < 0) | |
1885 | perror("dup2 stdin"); | |
1886 | close(pin[0]); | |
1887 | ||
1888 | /* Redirect stdout. */ | |
1889 | close(pout[0]); | |
1890 | if (dup2(pout[1], 1) < 0) | |
1891 | perror("dup2 stdout"); | |
1892 | close(pout[1]); | |
1893 | ||
1894 | /* Redirect stderr. */ | |
1895 | close(perr[0]); | |
1896 | if (dup2(perr[1], 2) < 0) | |
1897 | perror("dup2 stderr"); | |
1898 | close(perr[1]); | |
1899 | #else /* USE_PIPES */ | |
1900 | /* Redirect stdin, stdout, and stderr. Stdin and stdout will use the | |
1901 | same socket, as some programs (particularly rdist) seem to depend | |
1902 | on it. */ | |
1903 | close(inout[1]); | |
1904 | close(err[1]); | |
1905 | if (dup2(inout[0], 0) < 0) /* stdin */ | |
1906 | perror("dup2 stdin"); | |
1907 | if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ | |
1908 | perror("dup2 stdout"); | |
1909 | if (dup2(err[0], 2) < 0) /* stderr */ | |
1910 | perror("dup2 stderr"); | |
1911 | #endif /* USE_PIPES */ | |
1912 | ||
1913 | /* Do processing for the child (exec command etc). */ | |
1914 | do_child(command, pw, NULL, display, auth_proto, auth_data, NULL); | |
1915 | /*NOTREACHED*/ | |
1916 | } | |
1917 | if (pid < 0) | |
1918 | packet_disconnect("fork failed: %.100s", strerror(errno)); | |
1919 | #ifdef USE_PIPES | |
1920 | /* We are the parent. Close the child sides of the pipes. */ | |
1921 | close(pin[0]); | |
1922 | close(pout[1]); | |
1923 | close(perr[1]); | |
1924 | ||
1925 | /* Enter the interactive session. */ | |
1926 | server_loop(pid, pin[1], pout[0], perr[0]); | |
1927 | /* server_loop has closed pin[1], pout[1], and perr[1]. */ | |
1928 | #else /* USE_PIPES */ | |
1929 | /* We are the parent. Close the child sides of the socket pairs. */ | |
1930 | close(inout[0]); | |
1931 | close(err[0]); | |
1932 | ||
1933 | /* Enter the interactive session. Note: server_loop must be able to handle | |
1934 | the case that fdin and fdout are the same. */ | |
1935 | server_loop(pid, inout[1], inout[1], err[1]); | |
1936 | /* server_loop has closed inout[1] and err[1]. */ | |
1937 | #endif /* USE_PIPES */ | |
1938 | } | |
1939 | ||
1940 | struct pty_cleanup_context | |
1941 | { | |
1942 | const char *ttyname; | |
1943 | int pid; | |
1944 | }; | |
1945 | ||
1946 | /* Function to perform cleanup if we get aborted abnormally (e.g., due to a | |
1947 | dropped connection). */ | |
1948 | ||
1949 | void pty_cleanup_proc(void *context) | |
1950 | { | |
1951 | struct pty_cleanup_context *cu = context; | |
1952 | ||
1953 | debug("pty_cleanup_proc called"); | |
1954 | ||
8efc0c15 | 1955 | /* Record that the user has logged out. */ |
1956 | record_logout(cu->pid, cu->ttyname); | |
1957 | ||
1958 | /* Release the pseudo-tty. */ | |
1959 | pty_release(cu->ttyname); | |
1960 | } | |
1961 | ||
1962 | /* This is called to fork and execute a command when we have a tty. This | |
1963 | will call do_child from the child, and server_loop from the parent after | |
1964 | setting up file descriptors, controlling tty, updating wtmp, utmp, | |
1965 | lastlog, and other such operations. */ | |
1966 | ||
1967 | void do_exec_pty(const char *command, int ptyfd, int ttyfd, | |
1968 | const char *ttyname, struct passwd *pw, const char *term, | |
1969 | const char *display, const char *auth_proto, | |
1970 | const char *auth_data) | |
1971 | { | |
1972 | int pid, fdout; | |
1973 | const char *hostname; | |
1974 | time_t last_login_time; | |
1975 | char buf[100], *time_string; | |
1976 | FILE *f; | |
1977 | char line[256]; | |
1978 | struct stat st; | |
1979 | int quiet_login; | |
1980 | struct sockaddr_in from; | |
1981 | int fromlen; | |
1982 | struct pty_cleanup_context cleanup_context; | |
1983 | ||
1984 | /* Get remote host name. */ | |
1985 | hostname = get_canonical_hostname(); | |
1986 | ||
1987 | /* Get the time when the user last logged in. Buf will be set to contain | |
1988 | the hostname the last login was from. */ | |
1989 | if(!options.use_login) { | |
1990 | last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name, | |
1991 | buf, sizeof(buf)); | |
1992 | } | |
1993 | ||
1994 | setproctitle("%s@%s", pw->pw_name, strrchr(ttyname, '/') + 1); | |
1995 | ||
1996 | /* Fork the child. */ | |
1997 | if ((pid = fork()) == 0) | |
1998 | { | |
1999 | pid = getpid(); | |
2000 | ||
2001 | /* Child. Reinitialize the log because the pid has changed. */ | |
6a17f9c2 | 2002 | log_init(av0, options.log_level, options.log_facility, log_stderr); |
8efc0c15 | 2003 | |
2004 | /* Close the master side of the pseudo tty. */ | |
2005 | close(ptyfd); | |
2006 | ||
2007 | /* Make the pseudo tty our controlling tty. */ | |
2008 | pty_make_controlling_tty(&ttyfd, ttyname); | |
2009 | ||
2010 | /* Redirect stdin from the pseudo tty. */ | |
2011 | if (dup2(ttyfd, fileno(stdin)) < 0) | |
2012 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2013 | ||
2014 | /* Redirect stdout to the pseudo tty. */ | |
2015 | if (dup2(ttyfd, fileno(stdout)) < 0) | |
2016 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2017 | ||
2018 | /* Redirect stderr to the pseudo tty. */ | |
2019 | if (dup2(ttyfd, fileno(stderr)) < 0) | |
2020 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2021 | ||
2022 | /* Close the extra descriptor for the pseudo tty. */ | |
2023 | close(ttyfd); | |
2024 | ||
2025 | /* Get IP address of client. This is needed because we want to record | |
2026 | where the user logged in from. If the connection is not a socket, | |
2027 | let the ip address be 0.0.0.0. */ | |
2028 | memset(&from, 0, sizeof(from)); | |
2029 | if (packet_get_connection_in() == packet_get_connection_out()) | |
2030 | { | |
2031 | fromlen = sizeof(from); | |
2032 | if (getpeername(packet_get_connection_in(), | |
e7c0f9d5 | 2033 | (struct sockaddr *)&from, &fromlen) < 0) { |
2034 | debug("getpeername: %.100s", strerror(errno)); | |
2035 | fatal_cleanup(); | |
2036 | } | |
8efc0c15 | 2037 | } |
2038 | ||
2039 | /* Record that there was a login on that terminal. */ | |
2040 | record_login(pid, ttyname, pw->pw_name, pw->pw_uid, hostname, | |
2041 | &from); | |
2042 | ||
2043 | /* Check if .hushlogin exists. */ | |
2044 | snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir); | |
2045 | quiet_login = stat(line, &st) >= 0; | |
e1a9c08d | 2046 | |
2047 | #ifdef HAVE_LIBPAM | |
2048 | /* output the results of the pamconv() */ | |
2049 | if (!quiet_login && pamconv_msg != NULL) | |
2050 | fprintf(stderr, pamconv_msg); | |
2051 | #endif | |
2052 | ||
8efc0c15 | 2053 | /* If the user has logged in before, display the time of last login. |
2054 | However, don't display anything extra if a command has been | |
2055 | specified (so that ssh can be used to execute commands on a remote | |
2056 | machine without users knowing they are going to another machine). | |
2057 | Login(1) will do this for us as well, so check if login(1) is used */ | |
2058 | if (command == NULL && last_login_time != 0 && !quiet_login && | |
2059 | !options.use_login) | |
2060 | { | |
2061 | /* Convert the date to a string. */ | |
2062 | time_string = ctime(&last_login_time); | |
2063 | /* Remove the trailing newline. */ | |
2064 | if (strchr(time_string, '\n')) | |
2065 | *strchr(time_string, '\n') = 0; | |
2066 | /* Display the last login time. Host if displayed if known. */ | |
2067 | if (strcmp(buf, "") == 0) | |
2068 | printf("Last login: %s\r\n", time_string); | |
2069 | else | |
2070 | printf("Last login: %s from %s\r\n", time_string, buf); | |
2071 | } | |
2072 | ||
2073 | /* Print /etc/motd unless a command was specified or printing it was | |
2074 | disabled in server options or login(1) will be used. Note that | |
2075 | some machines appear to print it in /etc/profile or similar. */ | |
2076 | if (command == NULL && options.print_motd && !quiet_login && | |
2077 | !options.use_login) | |
2078 | { | |
2079 | /* Print /etc/motd if it exists. */ | |
2080 | f = fopen("/etc/motd", "r"); | |
2081 | if (f) | |
2082 | { | |
2083 | while (fgets(line, sizeof(line), f)) | |
2084 | fputs(line, stdout); | |
2085 | fclose(f); | |
2086 | } | |
2087 | } | |
2088 | ||
2089 | /* Do common processing for the child, such as execing the command. */ | |
2090 | do_child(command, pw, term, display, auth_proto, auth_data, ttyname); | |
2091 | /*NOTREACHED*/ | |
2092 | } | |
2093 | if (pid < 0) | |
2094 | packet_disconnect("fork failed: %.100s", strerror(errno)); | |
2095 | /* Parent. Close the slave side of the pseudo tty. */ | |
2096 | close(ttyfd); | |
2097 | ||
2098 | /* Create another descriptor of the pty master side for use as the standard | |
2099 | input. We could use the original descriptor, but this simplifies code | |
2100 | in server_loop. The descriptor is bidirectional. */ | |
2101 | fdout = dup(ptyfd); | |
2102 | if (fdout < 0) | |
2103 | packet_disconnect("dup failed: %.100s", strerror(errno)); | |
2104 | ||
2105 | /* Add a cleanup function to clear the utmp entry and record logout time | |
2106 | in case we call fatal() (e.g., the connection gets closed). */ | |
2107 | cleanup_context.pid = pid; | |
2108 | cleanup_context.ttyname = ttyname; | |
2109 | fatal_add_cleanup(pty_cleanup_proc, (void *)&cleanup_context); | |
2110 | ||
2111 | /* Enter interactive session. */ | |
2112 | server_loop(pid, ptyfd, fdout, -1); | |
2113 | /* server_loop has not closed ptyfd and fdout. */ | |
2114 | ||
2115 | /* Cancel the cleanup function. */ | |
2116 | fatal_remove_cleanup(pty_cleanup_proc, (void *)&cleanup_context); | |
2117 | ||
2118 | /* Record that the user has logged out. */ | |
2119 | record_logout(pid, ttyname); | |
2120 | ||
2121 | /* Release the pseudo-tty. */ | |
2122 | pty_release(ttyname); | |
2123 | ||
2124 | /* Close the server side of the socket pairs. We must do this after the | |
2125 | pty cleanup, so that another process doesn't get this pty while we're | |
2126 | still cleaning up. */ | |
2127 | close(ptyfd); | |
2128 | close(fdout); | |
2129 | } | |
2130 | ||
2131 | /* Sets the value of the given variable in the environment. If the variable | |
2132 | already exists, its value is overriden. */ | |
2133 | ||
2134 | void child_set_env(char ***envp, unsigned int *envsizep, const char *name, | |
2135 | const char *value) | |
2136 | { | |
2137 | unsigned int i, namelen; | |
2138 | char **env; | |
2139 | ||
2140 | /* Find the slot where the value should be stored. If the variable already | |
2141 | exists, we reuse the slot; otherwise we append a new slot at the end | |
2142 | of the array, expanding if necessary. */ | |
2143 | env = *envp; | |
2144 | namelen = strlen(name); | |
2145 | for (i = 0; env[i]; i++) | |
2146 | if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') | |
2147 | break; | |
2148 | if (env[i]) | |
2149 | { | |
2150 | /* Name already exists. Reuse the slot. */ | |
2151 | xfree(env[i]); | |
2152 | } | |
2153 | else | |
2154 | { | |
2155 | /* New variable. Expand the array if necessary. */ | |
2156 | if (i >= (*envsizep) - 1) | |
2157 | { | |
2158 | (*envsizep) += 50; | |
2159 | env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); | |
2160 | } | |
2161 | ||
2162 | /* Need to set the NULL pointer at end of array beyond the new | |
2163 | slot. */ | |
2164 | env[i + 1] = NULL; | |
2165 | } | |
2166 | ||
2167 | /* Allocate space and format the variable in the appropriate slot. */ | |
2168 | env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); | |
2169 | snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); | |
2170 | } | |
2171 | ||
2172 | /* Reads environment variables from the given file and adds/overrides them | |
2173 | into the environment. If the file does not exist, this does nothing. | |
2174 | Otherwise, it must consist of empty lines, comments (line starts with '#') | |
2175 | and assignments of the form name=value. No other forms are allowed. */ | |
2176 | ||
2177 | void read_environment_file(char ***env, unsigned int *envsize, | |
2178 | const char *filename) | |
2179 | { | |
2180 | FILE *f; | |
2181 | char buf[4096]; | |
2182 | char *cp, *value; | |
2183 | ||
2184 | /* Open the environment file. */ | |
2185 | f = fopen(filename, "r"); | |
2186 | if (!f) | |
2187 | return; /* Not found. */ | |
2188 | ||
2189 | /* Process each line. */ | |
2190 | while (fgets(buf, sizeof(buf), f)) | |
2191 | { | |
2192 | /* Skip leading whitespace. */ | |
2193 | for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) | |
2194 | ; | |
2195 | ||
2196 | /* Ignore empty and comment lines. */ | |
2197 | if (!*cp || *cp == '#' || *cp == '\n') | |
2198 | continue; | |
2199 | ||
2200 | /* Remove newline. */ | |
2201 | if (strchr(cp, '\n')) | |
2202 | *strchr(cp, '\n') = '\0'; | |
2203 | ||
2204 | /* Find the equals sign. Its lack indicates badly formatted line. */ | |
2205 | value = strchr(cp, '='); | |
2206 | if (value == NULL) | |
2207 | { | |
2208 | fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf); | |
2209 | continue; | |
2210 | } | |
2211 | ||
2212 | /* Replace the equals sign by nul, and advance value to the value | |
2213 | string. */ | |
2214 | *value = '\0'; | |
2215 | value++; | |
2216 | ||
2217 | /* Set the value in environment. */ | |
2218 | child_set_env(env, envsize, cp, value); | |
2219 | } | |
2220 | ||
2221 | fclose(f); | |
2222 | } | |
2223 | ||
2224 | /* Performs common processing for the child, such as setting up the | |
2225 | environment, closing extra file descriptors, setting the user and group | |
2226 | ids, and executing the command or shell. */ | |
2227 | ||
2228 | void do_child(const char *command, struct passwd *pw, const char *term, | |
2229 | const char *display, const char *auth_proto, | |
2230 | const char *auth_data, const char *ttyname) | |
2231 | { | |
2232 | const char *shell, *cp = NULL; | |
2233 | char buf[256]; | |
2234 | FILE *f; | |
2235 | unsigned int envsize, i; | |
2236 | char **env; | |
2237 | extern char **environ; | |
2238 | struct stat st; | |
2239 | char *argv[10]; | |
2240 | ||
e1a9c08d | 2241 | #ifndef HAVE_LIBPAM /* pam_nologin handles this */ |
8efc0c15 | 2242 | /* Check /etc/nologin. */ |
2243 | f = fopen("/etc/nologin", "r"); | |
2244 | if (f) | |
2245 | { /* /etc/nologin exists. Print its contents and exit. */ | |
2246 | while (fgets(buf, sizeof(buf), f)) | |
2247 | fputs(buf, stderr); | |
2248 | fclose(f); | |
2249 | if (pw->pw_uid != 0) | |
2250 | exit(254); | |
2251 | } | |
e35c1dc2 | 2252 | #endif /* HAVE_LIBPAM */ |
2253 | ||
2254 | #ifdef HAVE_SETLOGIN | |
2255 | /* Set login name in the kernel. */ | |
2256 | if (setlogin(pw->pw_name) < 0) | |
2257 | error("setlogin failed: %s", strerror(errno)); | |
2258 | #endif /* HAVE_SETLOGIN */ | |
8efc0c15 | 2259 | |
8efc0c15 | 2260 | /* Set uid, gid, and groups. */ |
2261 | /* Login(1) does this as well, and it needs uid 0 for the "-h" switch, | |
2262 | so we let login(1) to this for us. */ | |
2263 | if(!options.use_login) { | |
2264 | if (getuid() == 0 || geteuid() == 0) | |
2265 | { | |
2266 | if (setgid(pw->pw_gid) < 0) | |
2267 | { | |
2268 | perror("setgid"); | |
2269 | exit(1); | |
2270 | } | |
2271 | /* Initialize the group list. */ | |
2272 | if (initgroups(pw->pw_name, pw->pw_gid) < 0) | |
2273 | { | |
2274 | perror("initgroups"); | |
2275 | exit(1); | |
2276 | } | |
2277 | endgrent(); | |
2278 | ||
2279 | /* Permanently switch to the desired uid. */ | |
2280 | permanently_set_uid(pw->pw_uid); | |
2281 | } | |
2282 | ||
2283 | if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) | |
2284 | fatal("Failed to set uids to %d.", (int)pw->pw_uid); | |
2285 | } | |
2286 | ||
2287 | /* Get the shell from the password data. An empty shell field is legal, | |
2288 | and means /bin/sh. */ | |
2289 | shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; | |
2290 | ||
2291 | #ifdef AFS | |
2292 | /* Try to get AFS tokens for the local cell. */ | |
2293 | if (k_hasafs()) { | |
2294 | char cell[64]; | |
2295 | ||
2296 | if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) | |
2297 | krb_afslog(cell, 0); | |
2298 | ||
2299 | krb_afslog(0, 0); | |
2300 | } | |
2301 | #endif /* AFS */ | |
2302 | ||
2303 | /* Initialize the environment. In the first part we allocate space for | |
2304 | all environment variables. */ | |
2305 | envsize = 100; | |
2306 | env = xmalloc(envsize * sizeof(char *)); | |
2307 | env[0] = NULL; | |
2308 | ||
2309 | if(!options.use_login) { | |
2310 | /* Set basic environment. */ | |
2311 | child_set_env(&env, &envsize, "USER", pw->pw_name); | |
2312 | child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); | |
2313 | child_set_env(&env, &envsize, "HOME", pw->pw_dir); | |
2314 | child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); | |
2315 | ||
2316 | snprintf(buf, sizeof buf, "%.200s/%.50s", | |
2317 | _PATH_MAILDIR, pw->pw_name); | |
2318 | child_set_env(&env, &envsize, "MAIL", buf); | |
2319 | ||
2320 | /* Normal systems set SHELL by default. */ | |
2321 | child_set_env(&env, &envsize, "SHELL", shell); | |
2322 | } | |
2323 | ||
2324 | /* Let it inherit timezone if we have one. */ | |
2325 | if (getenv("TZ")) | |
2326 | child_set_env(&env, &envsize, "TZ", getenv("TZ")); | |
2327 | ||
2328 | /* Set custom environment options from RSA authentication. */ | |
2329 | while (custom_environment) | |
2330 | { | |
2331 | struct envstring *ce = custom_environment; | |
2332 | char *s = ce->s; | |
2333 | int i; | |
2334 | for (i = 0; s[i] != '=' && s[i]; i++) | |
2335 | ; | |
2336 | if (s[i] == '=') | |
2337 | { | |
2338 | s[i] = 0; | |
2339 | child_set_env(&env, &envsize, s, s + i + 1); | |
2340 | } | |
2341 | custom_environment = ce->next; | |
2342 | xfree(ce->s); | |
2343 | xfree(ce); | |
2344 | } | |
2345 | ||
2346 | /* Set SSH_CLIENT. */ | |
2347 | snprintf(buf, sizeof buf, "%.50s %d %d", | |
2348 | get_remote_ipaddr(), get_remote_port(), options.port); | |
2349 | child_set_env(&env, &envsize, "SSH_CLIENT", buf); | |
2350 | ||
2351 | /* Set SSH_TTY if we have a pty. */ | |
2352 | if (ttyname) | |
2353 | child_set_env(&env, &envsize, "SSH_TTY", ttyname); | |
2354 | ||
2355 | /* Set TERM if we have a pty. */ | |
2356 | if (term) | |
2357 | child_set_env(&env, &envsize, "TERM", term); | |
2358 | ||
2359 | /* Set DISPLAY if we have one. */ | |
2360 | if (display) | |
2361 | child_set_env(&env, &envsize, "DISPLAY", display); | |
2362 | ||
2363 | #ifdef KRB4 | |
6a17f9c2 | 2364 | { |
e35c1dc2 | 2365 | extern char *ticket; |
2366 | ||
2367 | if (ticket) | |
2368 | child_set_env(&env, &envsize, "KRBTKFILE", ticket); | |
6a17f9c2 | 2369 | } |
8efc0c15 | 2370 | #endif /* KRB4 */ |
2371 | ||
bb0dd7f6 | 2372 | #ifdef HAVE_LIBPAM |
2373 | /* Pull in any environment variables that may have been set by PAM. */ | |
2374 | { | |
2375 | char *equal_sign, var_name[256], var_val[256]; | |
2376 | long this_var; | |
50da1126 | 2377 | char **pam_env = pam_getenvlist((pam_handle_t *)pamh); |
bb0dd7f6 | 2378 | for(this_var = 0; pam_env && pam_env[this_var]; this_var++) |
2379 | { | |
242588e6 | 2380 | if(strlen(pam_env[this_var]) < (sizeof(var_name) - 1)) |
bb0dd7f6 | 2381 | if((equal_sign = strstr(pam_env[this_var], "=")) != NULL) |
2382 | { | |
2383 | memset(var_name, 0, sizeof(var_name)); | |
2384 | memset(var_val, 0, sizeof(var_val)); | |
2385 | strncpy(var_name, pam_env[this_var], | |
2386 | equal_sign - pam_env[this_var]); | |
2387 | strcpy(var_val, equal_sign + 1); | |
2388 | child_set_env(&env, &envsize, var_name, var_val); | |
2389 | } | |
2390 | } | |
2391 | } | |
2392 | #endif /* HAVE_LIBPAM */ | |
2393 | ||
8efc0c15 | 2394 | /* Set XAUTHORITY to always be a local file. */ |
2395 | if (xauthfile) | |
2396 | child_set_env(&env, &envsize, "XAUTHORITY", xauthfile); | |
2397 | ||
2398 | /* Set variable for forwarded authentication connection, if we have one. */ | |
2399 | if (auth_get_socket_name() != NULL) | |
2400 | child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, | |
2401 | auth_get_socket_name()); | |
e35c1dc2 | 2402 | |
8efc0c15 | 2403 | /* Read $HOME/.ssh/environment. */ |
2404 | if(!options.use_login) { | |
2405 | snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir); | |
2406 | read_environment_file(&env, &envsize, buf); | |
2407 | } | |
2408 | ||
2409 | /* If debugging, dump the environment to stderr. */ | |
2410 | if (debug_flag) | |
2411 | { | |
2412 | fprintf(stderr, "Environment:\n"); | |
2413 | for (i = 0; env[i]; i++) | |
2414 | fprintf(stderr, " %.200s\n", env[i]); | |
2415 | } | |
2416 | ||
2417 | /* Close the connection descriptors; note that this is the child, and the | |
2418 | server will still have the socket open, and it is important that we | |
2419 | do not shutdown it. Note that the descriptors cannot be closed before | |
2420 | building the environment, as we call get_remote_ipaddr there. */ | |
2421 | if (packet_get_connection_in() == packet_get_connection_out()) | |
2422 | close(packet_get_connection_in()); | |
2423 | else | |
2424 | { | |
2425 | close(packet_get_connection_in()); | |
2426 | close(packet_get_connection_out()); | |
2427 | } | |
2428 | /* Close all descriptors related to channels. They will still remain | |
2429 | open in the parent. */ | |
2430 | channel_close_all(); | |
2431 | ||
2432 | /* Close any extra file descriptors. Note that there may still be | |
2433 | descriptors left by system functions. They will be closed later. */ | |
2434 | endpwent(); | |
2435 | endhostent(); | |
2436 | ||
2437 | /* Close any extra open file descriptors so that we don\'t have them | |
2438 | hanging around in clients. Note that we want to do this after | |
2439 | initgroups, because at least on Solaris 2.3 it leaves file descriptors | |
2440 | open. */ | |
2441 | for (i = 3; i < 64; i++) | |
2442 | close(i); | |
2443 | ||
2444 | /* Change current directory to the user\'s home directory. */ | |
2445 | if (chdir(pw->pw_dir) < 0) | |
2446 | fprintf(stderr, "Could not chdir to home directory %s: %s\n", | |
2447 | pw->pw_dir, strerror(errno)); | |
2448 | ||
2449 | /* Must take new environment into use so that .ssh/rc, /etc/sshrc and | |
2450 | xauth are run in the proper environment. */ | |
2451 | environ = env; | |
2452 | ||
2453 | /* Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first | |
2454 | in this order). */ | |
2455 | if(!options.use_login) { | |
2456 | if (stat(SSH_USER_RC, &st) >= 0) | |
2457 | { | |
2458 | if (debug_flag) | |
2459 | fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC); | |
2460 | ||
2461 | f = popen("/bin/sh " SSH_USER_RC, "w"); | |
2462 | if (f) | |
2463 | { | |
2464 | if (auth_proto != NULL && auth_data != NULL) | |
2465 | fprintf(f, "%s %s\n", auth_proto, auth_data); | |
2466 | pclose(f); | |
2467 | } | |
2468 | else | |
2469 | fprintf(stderr, "Could not run %s\n", SSH_USER_RC); | |
2470 | } | |
2471 | else | |
2472 | if (stat(SSH_SYSTEM_RC, &st) >= 0) | |
2473 | { | |
2474 | if (debug_flag) | |
2475 | fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC); | |
2476 | ||
2477 | f = popen("/bin/sh " SSH_SYSTEM_RC, "w"); | |
2478 | if (f) | |
2479 | { | |
2480 | if (auth_proto != NULL && auth_data != NULL) | |
2481 | fprintf(f, "%s %s\n", auth_proto, auth_data); | |
2482 | pclose(f); | |
2483 | } | |
2484 | else | |
2485 | fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC); | |
2486 | } | |
2487 | #ifdef XAUTH_PATH | |
2488 | else | |
2489 | { | |
2490 | /* Add authority data to .Xauthority if appropriate. */ | |
2491 | if (auth_proto != NULL && auth_data != NULL) | |
2492 | { | |
2493 | if (debug_flag) | |
2494 | fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n", | |
2495 | XAUTH_PATH, display, auth_proto, auth_data); | |
2496 | ||
2497 | f = popen(XAUTH_PATH " -q -", "w"); | |
2498 | if (f) | |
2499 | { | |
2500 | fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data); | |
2501 | fclose(f); | |
2502 | } | |
2503 | else | |
2504 | fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH); | |
2505 | } | |
2506 | } | |
2507 | #endif /* XAUTH_PATH */ | |
2508 | ||
2509 | /* Get the last component of the shell name. */ | |
2510 | cp = strrchr(shell, '/'); | |
2511 | if (cp) | |
2512 | cp++; | |
2513 | else | |
2514 | cp = shell; | |
2515 | } | |
2516 | ||
2517 | /* If we have no command, execute the shell. In this case, the shell name | |
2518 | to be passed in argv[0] is preceded by '-' to indicate that this is | |
2519 | a login shell. */ | |
2520 | if (!command) | |
2521 | { | |
2522 | if(!options.use_login) { | |
2523 | char buf[256]; | |
2524 | ||
2525 | /* Check for mail if we have a tty and it was enabled in server options. */ | |
2526 | if (ttyname && options.check_mail) { | |
2527 | char *mailbox; | |
2528 | struct stat mailstat; | |
2529 | mailbox = getenv("MAIL"); | |
2530 | if(mailbox != NULL) { | |
2531 | if(stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0) { | |
2532 | printf("No mail.\n"); | |
2533 | } else if(mailstat.st_mtime < mailstat.st_atime) { | |
2534 | printf("You have mail.\n"); | |
2535 | } else { | |
2536 | printf("You have new mail.\n"); | |
2537 | } | |
2538 | } | |
2539 | } | |
2540 | /* Start the shell. Set initial character to '-'. */ | |
2541 | buf[0] = '-'; | |
2542 | strncpy(buf + 1, cp, sizeof(buf) - 1); | |
2543 | buf[sizeof(buf) - 1] = 0; | |
2544 | /* Execute the shell. */ | |
2545 | argv[0] = buf; | |
2546 | argv[1] = NULL; | |
2547 | execve(shell, argv, env); | |
2548 | /* Executing the shell failed. */ | |
2549 | perror(shell); | |
2550 | exit(1); | |
2551 | ||
2552 | } else { | |
2553 | /* Launch login(1). */ | |
2554 | ||
e1a9c08d | 2555 | execl(LOGIN_PROGRAM, "login", "-h", get_remote_ipaddr(), "-p", "-f", "--", pw->pw_name, NULL); |
8efc0c15 | 2556 | |
2557 | /* Login couldn't be executed, die. */ | |
2558 | ||
2559 | perror("login"); | |
2560 | exit(1); | |
2561 | } | |
2562 | } | |
2563 | ||
2564 | /* Execute the command using the user's shell. This uses the -c option | |
2565 | to execute the command. */ | |
2566 | argv[0] = (char *)cp; | |
2567 | argv[1] = "-c"; | |
2568 | argv[2] = (char *)command; | |
2569 | argv[3] = NULL; | |
2570 | execve(shell, argv, env); | |
2571 | perror(shell); | |
2572 | exit(1); | |
2573 | } |