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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Created: Fri Mar 17 17:09:28 1995 ylo | |
6 | * This program is the ssh daemon. It listens for connections from clients, and | |
7 | * performs authentication, executes use commands or shell, and forwards | |
8 | * information to/from the application to the user client over an encrypted | |
9 | * connection. This can also handle forwarding of X11, TCP/IP, and authentication | |
10 | * agent connections. | |
11 | */ | |
8efc0c15 | 12 | |
13 | #include "includes.h" | |
14 | RCSID("$Id$"); | |
15 | ||
16 | #include "xmalloc.h" | |
17 | #include "rsa.h" | |
18 | #include "ssh.h" | |
19 | #include "pty.h" | |
20 | #include "packet.h" | |
21 | #include "buffer.h" | |
22 | #include "cipher.h" | |
23 | #include "mpaux.h" | |
24 | #include "servconf.h" | |
25 | #include "uidswap.h" | |
26 | #include "compat.h" | |
27 | ||
28 | #ifdef LIBWRAP | |
29 | #include <tcpd.h> | |
30 | #include <syslog.h> | |
31 | int allow_severity = LOG_INFO; | |
32 | int deny_severity = LOG_WARNING; | |
33 | #endif /* LIBWRAP */ | |
34 | ||
35 | #ifndef O_NOCTTY | |
36 | #define O_NOCTTY 0 | |
37 | #endif | |
38 | ||
8efc0c15 | 39 | /* Local Xauthority file. */ |
6a17f9c2 | 40 | static char *xauthfile = NULL; |
8efc0c15 | 41 | |
42 | /* Server configuration options. */ | |
43 | ServerOptions options; | |
44 | ||
45 | /* Name of the server configuration file. */ | |
46 | char *config_file_name = SERVER_CONFIG_FILE; | |
47 | ||
5260325f | 48 | /* |
49 | * Debug mode flag. This can be set on the command line. If debug | |
50 | * mode is enabled, extra debugging output will be sent to the system | |
51 | * log, the daemon will not go to background, and will exit after processing | |
52 | * the first connection. | |
53 | */ | |
8efc0c15 | 54 | int debug_flag = 0; |
55 | ||
56 | /* Flag indicating that the daemon is being started from inetd. */ | |
57 | int inetd_flag = 0; | |
58 | ||
6a17f9c2 | 59 | /* debug goes to stderr unless inetd_flag is set */ |
60 | int log_stderr = 0; | |
61 | ||
8efc0c15 | 62 | /* argv[0] without path. */ |
63 | char *av0; | |
64 | ||
65 | /* Saved arguments to main(). */ | |
66 | char **saved_argv; | |
67 | ||
68 | /* This is set to the socket that the server is listening; this is used in | |
69 | the SIGHUP signal handler. */ | |
70 | int listen_sock; | |
71 | ||
5260325f | 72 | /* the client's version string, passed by sshd2 in compat mode. |
73 | if != NULL, sshd will skip the version-number exchange */ | |
74 | char *client_version_string = NULL; | |
75 | ||
76 | /* Flags set in auth-rsa from authorized_keys flags. These are set in auth-rsa.c. */ | |
8efc0c15 | 77 | int no_port_forwarding_flag = 0; |
78 | int no_agent_forwarding_flag = 0; | |
79 | int no_x11_forwarding_flag = 0; | |
80 | int no_pty_flag = 0; | |
5260325f | 81 | |
82 | /* RSA authentication "command=" option. */ | |
83 | char *forced_command = NULL; | |
84 | ||
85 | /* RSA authentication "environment=" options. */ | |
86 | struct envstring *custom_environment = NULL; | |
8efc0c15 | 87 | |
88 | /* Session id for the current session. */ | |
89 | unsigned char session_id[16]; | |
90 | ||
91 | /* Any really sensitive data in the application is contained in this structure. | |
92 | The idea is that this structure could be locked into memory so that the | |
93 | pages do not get written into swap. However, there are some problems. | |
94 | The private key contains BIGNUMs, and we do not (in principle) have | |
95 | access to the internals of them, and locking just the structure is not | |
96 | very useful. Currently, memory locking is not implemented. */ | |
5260325f | 97 | struct { |
98 | RSA *private_key; /* Private part of server key. */ | |
99 | RSA *host_key; /* Private part of host key. */ | |
8efc0c15 | 100 | } sensitive_data; |
101 | ||
102 | /* Flag indicating whether the current session key has been used. This flag | |
103 | is set whenever the key is used, and cleared when the key is regenerated. */ | |
104 | int key_used = 0; | |
105 | ||
106 | /* This is set to true when SIGHUP is received. */ | |
107 | int received_sighup = 0; | |
108 | ||
109 | /* Public side of the server key. This value is regenerated regularly with | |
110 | the private key. */ | |
111 | RSA *public_key; | |
112 | ||
113 | /* Prototypes for various functions defined later in this file. */ | |
e7c0f9d5 | 114 | void do_connection(); |
115 | void do_authentication(char *user); | |
5260325f | 116 | void do_authloop(struct passwd * pw); |
e7c0f9d5 | 117 | void do_fake_authloop(char *user); |
5260325f | 118 | void do_authenticated(struct passwd * pw); |
119 | void do_exec_pty(const char *command, int ptyfd, int ttyfd, | |
120 | const char *ttyname, struct passwd * pw, const char *term, | |
121 | const char *display, const char *auth_proto, | |
122 | const char *auth_data); | |
123 | void do_exec_no_pty(const char *command, struct passwd * pw, | |
124 | const char *display, const char *auth_proto, | |
125 | const char *auth_data); | |
126 | void do_child(const char *command, struct passwd * pw, const char *term, | |
8efc0c15 | 127 | const char *display, const char *auth_proto, |
128 | const char *auth_data, const char *ttyname); | |
e7c0f9d5 | 129 | |
5aecb327 | 130 | #ifdef HAVE_LIBPAM |
8efc0c15 | 131 | static int pamconv(int num_msg, const struct pam_message **msg, |
5260325f | 132 | struct pam_response **resp, void *appdata_ptr); |
c75a1a66 | 133 | void do_pam_account_and_session(char *username, char *remote_user, |
5260325f | 134 | const char *remote_host); |
d813bc69 | 135 | void pam_cleanup_proc(void *context); |
8efc0c15 | 136 | |
137 | static struct pam_conv conv = { | |
5260325f | 138 | pamconv, |
139 | NULL | |
8efc0c15 | 140 | }; |
d813bc69 | 141 | struct pam_handle_t *pamh = NULL; |
142 | const char *pampasswd = NULL; | |
e1a9c08d | 143 | char *pamconv_msg = NULL; |
8efc0c15 | 144 | |
145 | static int pamconv(int num_msg, const struct pam_message **msg, | |
8de3263e | 146 | struct pam_response **resp, void *appdata_ptr) |
8efc0c15 | 147 | { |
5260325f | 148 | struct pam_response *reply; |
149 | int count; | |
150 | size_t msg_len; | |
151 | char *p; | |
152 | ||
153 | /* PAM will free this later */ | |
154 | reply = malloc(num_msg * sizeof(*reply)); | |
155 | if (reply == NULL) | |
156 | return PAM_CONV_ERR; | |
157 | ||
158 | for(count = 0; count < num_msg; count++) { | |
159 | switch (msg[count]->msg_style) { | |
160 | case PAM_PROMPT_ECHO_OFF: | |
161 | if (pampasswd == NULL) { | |
162 | free(reply); | |
163 | return PAM_CONV_ERR; | |
164 | } | |
165 | reply[count].resp_retcode = PAM_SUCCESS; | |
166 | reply[count].resp = xstrdup(pampasswd); | |
167 | break; | |
168 | ||
169 | case PAM_TEXT_INFO: | |
170 | reply[count].resp_retcode = PAM_SUCCESS; | |
171 | reply[count].resp = xstrdup(""); | |
172 | ||
173 | if (msg[count]->msg == NULL) | |
174 | break; | |
175 | ||
176 | debug("Adding PAM message: %s", msg[count]->msg); | |
177 | ||
178 | msg_len = strlen(msg[count]->msg); | |
179 | if (pamconv_msg) { | |
180 | size_t n = strlen(pamconv_msg); | |
181 | pamconv_msg = xrealloc(pamconv_msg, n + msg_len + 2); | |
182 | p = pamconv_msg + n; | |
183 | } else { | |
184 | pamconv_msg = p = xmalloc(msg_len + 2); | |
185 | } | |
186 | memcpy(p, msg[count]->msg, msg_len); | |
187 | p[msg_len] = '\n'; | |
188 | p[msg_len + 1] = '\0'; | |
189 | break; | |
190 | ||
191 | case PAM_PROMPT_ECHO_ON: | |
192 | case PAM_ERROR_MSG: | |
193 | default: | |
194 | free(reply); | |
195 | return PAM_CONV_ERR; | |
196 | } | |
e1a9c08d | 197 | } |
5260325f | 198 | |
199 | *resp = reply; | |
200 | ||
201 | return PAM_SUCCESS; | |
8efc0c15 | 202 | } |
203 | ||
204 | void pam_cleanup_proc(void *context) | |
205 | { | |
5260325f | 206 | int pam_retval; |
207 | ||
208 | if (pamh != NULL) | |
209 | { | |
210 | pam_retval = pam_close_session((pam_handle_t *)pamh, 0); | |
211 | if (pam_retval != PAM_SUCCESS) { | |
212 | log("Cannot close PAM session: %.200s", | |
213 | PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); | |
214 | } | |
215 | ||
216 | pam_retval = pam_end((pam_handle_t *)pamh, pam_retval); | |
217 | if (pam_retval != PAM_SUCCESS) { | |
218 | log("Cannot release PAM authentication: %.200s", | |
219 | PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); | |
220 | } | |
221 | } | |
d813bc69 | 222 | } |
223 | ||
c75a1a66 | 224 | void do_pam_account_and_session(char *username, char *remote_user, |
5260325f | 225 | const char *remote_host) |
d813bc69 | 226 | { |
5260325f | 227 | int pam_retval; |
228 | ||
229 | if (remote_host != NULL) { | |
230 | debug("PAM setting rhost to \"%.200s\"", remote_host); | |
231 | pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RHOST, remote_host); | |
232 | if (pam_retval != PAM_SUCCESS) { | |
233 | log("PAM set rhost failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); | |
234 | do_fake_authloop(username); | |
235 | } | |
236 | } | |
237 | ||
238 | if (remote_user != NULL) { | |
239 | debug("PAM setting ruser to \"%.200s\"", remote_user); | |
240 | pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RUSER, remote_user); | |
241 | if (pam_retval != PAM_SUCCESS) { | |
242 | log("PAM set ruser failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); | |
243 | do_fake_authloop(username); | |
244 | } | |
245 | } | |
246 | ||
247 | pam_retval = pam_acct_mgmt((pam_handle_t *)pamh, 0); | |
248 | if (pam_retval != PAM_SUCCESS) { | |
249 | log("PAM rejected by account configuration: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); | |
250 | do_fake_authloop(username); | |
251 | } | |
252 | ||
253 | pam_retval = pam_open_session((pam_handle_t *)pamh, 0); | |
254 | if (pam_retval != PAM_SUCCESS) { | |
255 | log("PAM session setup failed: %.200s", PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); | |
256 | do_fake_authloop(username); | |
257 | } | |
8efc0c15 | 258 | } |
5aecb327 | 259 | #endif /* HAVE_LIBPAM */ |
8efc0c15 | 260 | |
5260325f | 261 | /* |
262 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
263 | * the effect is to reread the configuration file (and to regenerate | |
264 | * the server key). | |
265 | */ | |
266 | void | |
267 | sighup_handler(int sig) | |
8efc0c15 | 268 | { |
5260325f | 269 | received_sighup = 1; |
270 | signal(SIGHUP, sighup_handler); | |
8efc0c15 | 271 | } |
272 | ||
5260325f | 273 | /* |
274 | * Called from the main program after receiving SIGHUP. | |
275 | * Restarts the server. | |
276 | */ | |
277 | void | |
278 | sighup_restart() | |
8efc0c15 | 279 | { |
5260325f | 280 | log("Received SIGHUP; restarting."); |
281 | close(listen_sock); | |
282 | execv(saved_argv[0], saved_argv); | |
283 | log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); | |
284 | exit(1); | |
8efc0c15 | 285 | } |
286 | ||
5260325f | 287 | /* |
288 | * Generic signal handler for terminating signals in the master daemon. | |
289 | * These close the listen socket; not closing it seems to cause "Address | |
290 | * already in use" problems on some machines, which is inconvenient. | |
291 | */ | |
292 | void | |
293 | sigterm_handler(int sig) | |
8efc0c15 | 294 | { |
5260325f | 295 | log("Received signal %d; terminating.", sig); |
296 | close(listen_sock); | |
297 | exit(255); | |
8efc0c15 | 298 | } |
299 | ||
5260325f | 300 | /* |
301 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
302 | * reap any zombies left by exited c. | |
303 | */ | |
304 | void | |
305 | main_sigchld_handler(int sig) | |
8efc0c15 | 306 | { |
5260325f | 307 | int save_errno = errno; |
308 | int status; | |
5ad13cd7 | 309 | |
5260325f | 310 | while (waitpid(-1, &status, WNOHANG) > 0) |
311 | ; | |
5ad13cd7 | 312 | |
5260325f | 313 | signal(SIGCHLD, main_sigchld_handler); |
314 | errno = save_errno; | |
8efc0c15 | 315 | } |
316 | ||
5260325f | 317 | /* |
318 | * Signal handler for the alarm after the login grace period has expired. | |
319 | */ | |
320 | void | |
321 | grace_alarm_handler(int sig) | |
8efc0c15 | 322 | { |
5260325f | 323 | /* Close the connection. */ |
324 | packet_close(); | |
8efc0c15 | 325 | |
5260325f | 326 | /* Log error and exit. */ |
327 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
328 | } | |
8efc0c15 | 329 | |
5260325f | 330 | /* |
331 | * convert ssh auth msg type into description | |
332 | */ | |
333 | char * | |
334 | get_authname(int type) | |
8efc0c15 | 335 | { |
5260325f | 336 | switch (type) { |
337 | case SSH_CMSG_AUTH_PASSWORD: | |
338 | return "password"; | |
339 | case SSH_CMSG_AUTH_RSA: | |
340 | return "rsa"; | |
341 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
342 | return "rhosts-rsa"; | |
343 | case SSH_CMSG_AUTH_RHOSTS: | |
344 | return "rhosts"; | |
345 | #ifdef KRB4 | |
346 | case SSH_CMSG_AUTH_KERBEROS: | |
347 | return "kerberos"; | |
348 | #endif | |
349 | #ifdef SKEY | |
350 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
351 | return "s/key"; | |
352 | #endif | |
353 | } | |
354 | fatal("get_authname: unknown auth %d: internal error", type); | |
355 | return NULL; | |
8efc0c15 | 356 | } |
357 | ||
5260325f | 358 | /* |
359 | * Signal handler for the key regeneration alarm. Note that this | |
360 | * alarm only occurs in the daemon waiting for connections, and it does not | |
361 | * do anything with the private key or random state before forking. | |
362 | * Thus there should be no concurrency control/asynchronous execution | |
363 | * problems. | |
364 | */ | |
365 | void | |
366 | key_regeneration_alarm(int sig) | |
367 | { | |
368 | int save_errno = errno; | |
369 | ||
370 | /* Check if we should generate a new key. */ | |
371 | if (key_used) { | |
372 | /* This should really be done in the background. */ | |
373 | log("Generating new %d bit RSA key.", options.server_key_bits); | |
374 | ||
375 | if (sensitive_data.private_key != NULL) | |
376 | RSA_free(sensitive_data.private_key); | |
377 | sensitive_data.private_key = RSA_new(); | |
378 | ||
379 | if (public_key != NULL) | |
380 | RSA_free(public_key); | |
381 | public_key = RSA_new(); | |
382 | ||
383 | rsa_generate_key(sensitive_data.private_key, public_key, | |
384 | options.server_key_bits); | |
385 | arc4random_stir(); | |
386 | key_used = 0; | |
387 | log("RSA key generation complete."); | |
388 | } | |
389 | /* Reschedule the alarm. */ | |
390 | signal(SIGALRM, key_regeneration_alarm); | |
391 | alarm(options.key_regeneration_time); | |
392 | errno = save_errno; | |
393 | } | |
8efc0c15 | 394 | |
5260325f | 395 | /* |
396 | * Main program for the daemon. | |
397 | */ | |
8efc0c15 | 398 | int |
399 | main(int ac, char **av) | |
400 | { | |
5260325f | 401 | extern char *optarg; |
402 | extern int optind; | |
403 | int opt, aux, sock_in, sock_out, newsock, i, pid, on = 1; | |
404 | int remote_major, remote_minor; | |
405 | int silentrsa = 0; | |
406 | struct sockaddr_in sin; | |
407 | char buf[100]; /* Must not be larger than remote_version. */ | |
408 | char remote_version[100]; /* Must be at least as big as buf. */ | |
409 | const char *remote_ip; | |
410 | int remote_port; | |
411 | char *comment; | |
412 | FILE *f; | |
413 | struct linger linger; | |
414 | ||
415 | /* Save argv[0]. */ | |
416 | saved_argv = av; | |
417 | if (strchr(av[0], '/')) | |
418 | av0 = strrchr(av[0], '/') + 1; | |
419 | else | |
420 | av0 = av[0]; | |
421 | ||
422 | /* Initialize configuration options to their default values. */ | |
423 | initialize_server_options(&options); | |
424 | ||
425 | /* Parse command-line arguments. */ | |
426 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:diqQ")) != EOF) { | |
427 | switch (opt) { | |
428 | case 'f': | |
429 | config_file_name = optarg; | |
430 | break; | |
431 | case 'd': | |
432 | debug_flag = 1; | |
433 | options.log_level = SYSLOG_LEVEL_DEBUG; | |
434 | break; | |
435 | case 'i': | |
436 | inetd_flag = 1; | |
437 | break; | |
438 | case 'Q': | |
439 | silentrsa = 1; | |
440 | break; | |
441 | case 'q': | |
442 | options.log_level = SYSLOG_LEVEL_QUIET; | |
443 | break; | |
444 | case 'b': | |
445 | options.server_key_bits = atoi(optarg); | |
446 | break; | |
447 | case 'p': | |
448 | options.port = atoi(optarg); | |
449 | break; | |
450 | case 'g': | |
451 | options.login_grace_time = atoi(optarg); | |
452 | break; | |
453 | case 'k': | |
454 | options.key_regeneration_time = atoi(optarg); | |
455 | break; | |
456 | case 'h': | |
457 | options.host_key_file = optarg; | |
458 | break; | |
459 | case 'V': | |
460 | client_version_string = optarg; | |
461 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
462 | inetd_flag = 1; | |
463 | break; | |
464 | case '?': | |
465 | default: | |
466 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
467 | fprintf(stderr, "Usage: %s [options]\n", av0); | |
468 | fprintf(stderr, "Options:\n"); | |
469 | fprintf(stderr, " -f file Configuration file (default %s/sshd_config)\n", ETCDIR); | |
470 | fprintf(stderr, " -d Debugging mode\n"); | |
471 | fprintf(stderr, " -i Started from inetd\n"); | |
472 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
473 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
474 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
475 | fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); | |
476 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
477 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
478 | HOST_KEY_FILE); | |
479 | exit(1); | |
480 | } | |
481 | } | |
482 | ||
483 | /* check if RSA support exists */ | |
484 | if (rsa_alive() == 0) { | |
485 | if (silentrsa == 0) | |
486 | printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n"); | |
487 | log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)"); | |
488 | exit(1); | |
489 | } | |
490 | /* Read server configuration options from the configuration file. */ | |
491 | read_server_config(&options, config_file_name); | |
492 | ||
493 | /* Fill in default values for those options not explicitly set. */ | |
494 | fill_default_server_options(&options); | |
495 | ||
496 | /* Check certain values for sanity. */ | |
497 | if (options.server_key_bits < 512 || | |
498 | options.server_key_bits > 32768) { | |
499 | fprintf(stderr, "Bad server key size.\n"); | |
500 | exit(1); | |
501 | } | |
502 | if (options.port < 1 || options.port > 65535) { | |
503 | fprintf(stderr, "Bad port number.\n"); | |
504 | exit(1); | |
505 | } | |
506 | /* Check that there are no remaining arguments. */ | |
507 | if (optind < ac) { | |
508 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
509 | exit(1); | |
8efc0c15 | 510 | } |
5260325f | 511 | /* Force logging to stderr while loading the private host key |
512 | unless started from inetd */ | |
513 | log_init(av0, options.log_level, options.log_facility, !inetd_flag); | |
514 | ||
515 | debug("sshd version %.100s", SSH_VERSION); | |
516 | ||
517 | sensitive_data.host_key = RSA_new(); | |
518 | errno = 0; | |
519 | /* Load the host key. It must have empty passphrase. */ | |
520 | if (!load_private_key(options.host_key_file, "", | |
521 | sensitive_data.host_key, &comment)) { | |
522 | error("Could not load host key: %.200s: %.100s", | |
523 | options.host_key_file, strerror(errno)); | |
524 | exit(1); | |
525 | } | |
526 | xfree(comment); | |
527 | ||
528 | /* Initialize the log (it is reinitialized below in case we | |
529 | forked). */ | |
530 | if (debug_flag && !inetd_flag) | |
531 | log_stderr = 1; | |
532 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
533 | ||
534 | /* If not in debugging mode, and not started from inetd, | |
535 | disconnect from the controlling terminal, and fork. The | |
536 | original process exits. */ | |
537 | if (!debug_flag && !inetd_flag) { | |
8efc0c15 | 538 | #ifdef TIOCNOTTY |
5260325f | 539 | int fd; |
8efc0c15 | 540 | #endif /* TIOCNOTTY */ |
5260325f | 541 | if (daemon(0, 0) < 0) |
542 | fatal("daemon() failed: %.200s", strerror(errno)); | |
543 | ||
544 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 545 | #ifdef TIOCNOTTY |
5260325f | 546 | fd = open("/dev/tty", O_RDWR | O_NOCTTY); |
547 | if (fd >= 0) { | |
548 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
549 | close(fd); | |
550 | } | |
8efc0c15 | 551 | #endif /* TIOCNOTTY */ |
8efc0c15 | 552 | } |
5260325f | 553 | /* Reinitialize the log (because of the fork above). */ |
554 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
555 | ||
556 | /* Check that server and host key lengths differ sufficiently. | |
557 | This is necessary to make double encryption work with rsaref. | |
558 | Oh, I hate software patents. I dont know if this can go? Niels */ | |
559 | if (options.server_key_bits > | |
560 | BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED && | |
561 | options.server_key_bits < | |
562 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
563 | options.server_key_bits = | |
564 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED; | |
565 | debug("Forcing server key to %d bits to make it differ from host key.", | |
566 | options.server_key_bits); | |
8efc0c15 | 567 | } |
5260325f | 568 | /* Do not display messages to stdout in RSA code. */ |
569 | rsa_set_verbose(0); | |
570 | ||
571 | /* Initialize the random number generator. */ | |
572 | arc4random_stir(); | |
573 | ||
574 | /* Chdir to the root directory so that the current disk can be | |
575 | unmounted if desired. */ | |
576 | chdir("/"); | |
577 | ||
578 | /* Close connection cleanly after attack. */ | |
579 | cipher_attack_detected = packet_disconnect; | |
580 | ||
581 | /* Start listening for a socket, unless started from inetd. */ | |
582 | if (inetd_flag) { | |
583 | int s1, s2; | |
584 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
585 | s2 = dup(s1); | |
586 | sock_in = dup(0); | |
587 | sock_out = dup(1); | |
588 | /* We intentionally do not close the descriptors 0, 1, and 2 | |
589 | as our code for setting the descriptors won\'t work | |
590 | if ttyfd happens to be one of those. */ | |
591 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
592 | ||
593 | public_key = RSA_new(); | |
594 | sensitive_data.private_key = RSA_new(); | |
595 | ||
596 | log("Generating %d bit RSA key.", options.server_key_bits); | |
597 | rsa_generate_key(sensitive_data.private_key, public_key, | |
598 | options.server_key_bits); | |
599 | arc4random_stir(); | |
600 | log("RSA key generation complete."); | |
601 | } else { | |
602 | /* Create socket for listening. */ | |
603 | listen_sock = socket(AF_INET, SOCK_STREAM, 0); | |
604 | if (listen_sock < 0) | |
605 | fatal("socket: %.100s", strerror(errno)); | |
606 | ||
607 | /* Set socket options. We try to make the port reusable | |
608 | and have it close as fast as possible without waiting | |
609 | in unnecessary wait states on close. */ | |
610 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, (void *) &on, | |
611 | sizeof(on)); | |
612 | linger.l_onoff = 1; | |
613 | linger.l_linger = 5; | |
614 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, (void *) &linger, | |
615 | sizeof(linger)); | |
616 | ||
617 | /* Initialize the socket address. */ | |
618 | memset(&sin, 0, sizeof(sin)); | |
619 | sin.sin_family = AF_INET; | |
620 | sin.sin_addr = options.listen_addr; | |
621 | sin.sin_port = htons(options.port); | |
622 | ||
623 | /* Bind the socket to the desired port. */ | |
624 | if (bind(listen_sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { | |
625 | error("bind: %.100s", strerror(errno)); | |
626 | shutdown(listen_sock, SHUT_RDWR); | |
627 | close(listen_sock); | |
628 | fatal("Bind to port %d failed.", options.port); | |
629 | } | |
630 | if (!debug_flag) { | |
631 | /* Record our pid in /etc/sshd_pid to make it | |
632 | easier to kill the correct sshd. We don\'t | |
633 | want to do this before the bind above because | |
634 | the bind will fail if there already is a | |
635 | daemon, and this will overwrite any old pid in | |
636 | the file. */ | |
637 | f = fopen(SSH_DAEMON_PID_FILE, "w"); | |
638 | if (f) { | |
639 | fprintf(f, "%u\n", (unsigned int) getpid()); | |
640 | fclose(f); | |
641 | } | |
8efc0c15 | 642 | } |
8efc0c15 | 643 | |
5260325f | 644 | log("Server listening on port %d.", options.port); |
645 | if (listen(listen_sock, 5) < 0) | |
646 | fatal("listen: %.100s", strerror(errno)); | |
647 | ||
648 | public_key = RSA_new(); | |
649 | sensitive_data.private_key = RSA_new(); | |
650 | ||
651 | log("Generating %d bit RSA key.", options.server_key_bits); | |
652 | rsa_generate_key(sensitive_data.private_key, public_key, | |
653 | options.server_key_bits); | |
654 | arc4random_stir(); | |
655 | log("RSA key generation complete."); | |
656 | ||
657 | /* Schedule server key regeneration alarm. */ | |
658 | signal(SIGALRM, key_regeneration_alarm); | |
659 | alarm(options.key_regeneration_time); | |
660 | ||
661 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
662 | signal(SIGHUP, sighup_handler); | |
663 | signal(SIGTERM, sigterm_handler); | |
664 | signal(SIGQUIT, sigterm_handler); | |
665 | ||
666 | /* Arrange SIGCHLD to be caught. */ | |
667 | signal(SIGCHLD, main_sigchld_handler); | |
668 | ||
669 | /* Stay listening for connections until the system crashes | |
670 | or the daemon is killed with a signal. */ | |
671 | for (;;) { | |
672 | if (received_sighup) | |
673 | sighup_restart(); | |
674 | /* Wait in accept until there is a connection. */ | |
675 | aux = sizeof(sin); | |
676 | newsock = accept(listen_sock, (struct sockaddr *) & sin, &aux); | |
677 | if (received_sighup) | |
678 | sighup_restart(); | |
679 | if (newsock < 0) { | |
680 | if (errno == EINTR) | |
681 | continue; | |
682 | error("accept: %.100s", strerror(errno)); | |
683 | continue; | |
684 | } | |
685 | /* Got connection. Fork a child to handle it, | |
686 | unless we are in debugging mode. */ | |
687 | if (debug_flag) { | |
688 | /* In debugging mode. Close the listening | |
689 | socket, and start processing the | |
690 | connection without forking. */ | |
691 | debug("Server will not fork when running in debugging mode."); | |
692 | close(listen_sock); | |
693 | sock_in = newsock; | |
694 | sock_out = newsock; | |
695 | pid = getpid(); | |
696 | break; | |
697 | } else { | |
698 | /* Normal production daemon. Fork, and | |
699 | have the child process the connection. | |
700 | The parent continues listening. */ | |
701 | if ((pid = fork()) == 0) { | |
702 | /* Child. Close the listening | |
703 | socket, and start using the | |
704 | accepted socket. Reinitialize | |
705 | logging (since our pid has | |
706 | changed). We break out of the | |
707 | loop to handle the connection. */ | |
708 | close(listen_sock); | |
709 | sock_in = newsock; | |
710 | sock_out = newsock; | |
711 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
712 | break; | |
713 | } | |
714 | } | |
715 | ||
716 | /* Parent. Stay in the loop. */ | |
717 | if (pid < 0) | |
718 | error("fork: %.100s", strerror(errno)); | |
719 | else | |
720 | debug("Forked child %d.", pid); | |
721 | ||
722 | /* Mark that the key has been used (it was "given" to the child). */ | |
723 | key_used = 1; | |
724 | ||
725 | arc4random_stir(); | |
726 | ||
727 | /* Close the new socket (the child is now taking care of it). */ | |
728 | close(newsock); | |
729 | } | |
730 | } | |
8efc0c15 | 731 | |
5260325f | 732 | /* This is the child processing a new connection. */ |
733 | ||
734 | /* Disable the key regeneration alarm. We will not regenerate the | |
735 | key since we are no longer in a position to give it to anyone. | |
736 | We will not restart on SIGHUP since it no longer makes sense. */ | |
737 | alarm(0); | |
738 | signal(SIGALRM, SIG_DFL); | |
739 | signal(SIGHUP, SIG_DFL); | |
740 | signal(SIGTERM, SIG_DFL); | |
741 | signal(SIGQUIT, SIG_DFL); | |
742 | signal(SIGCHLD, SIG_DFL); | |
743 | ||
744 | /* Set socket options for the connection. We want the socket to | |
745 | close as fast as possible without waiting for anything. If the | |
746 | connection is not a socket, these will do nothing. */ | |
747 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, | |
748 | sizeof(on)); */ | |
749 | linger.l_onoff = 1; | |
750 | linger.l_linger = 5; | |
751 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
752 | ||
753 | /* Register our connection. This turns encryption off because we | |
754 | do not have a key. */ | |
755 | packet_set_connection(sock_in, sock_out); | |
756 | ||
757 | remote_port = get_remote_port(); | |
758 | remote_ip = get_remote_ipaddr(); | |
759 | ||
760 | /* Check whether logins are denied from this host. */ | |
761 | #ifdef LIBWRAP | |
762 | { | |
763 | struct request_info req; | |
8efc0c15 | 764 | |
5260325f | 765 | request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); |
766 | fromhost(&req); | |
8efc0c15 | 767 | |
5260325f | 768 | if (!hosts_access(&req)) { |
769 | close(sock_in); | |
770 | close(sock_out); | |
771 | refuse(&req); | |
772 | } | |
773 | verbose("Connection from %.500s port %d", eval_client(&req), remote_port); | |
8efc0c15 | 774 | } |
8efc0c15 | 775 | #else |
5260325f | 776 | /* Log the connection. */ |
777 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 778 | #endif /* LIBWRAP */ |
779 | ||
5260325f | 780 | /* We don\'t want to listen forever unless the other side |
781 | successfully authenticates itself. So we set up an alarm which | |
782 | is cleared after successful authentication. A limit of zero | |
783 | indicates no limit. Note that we don\'t set the alarm in | |
784 | debugging mode; it is just annoying to have the server exit | |
785 | just when you are about to discover the bug. */ | |
786 | signal(SIGALRM, grace_alarm_handler); | |
787 | if (!debug_flag) | |
788 | alarm(options.login_grace_time); | |
789 | ||
790 | if (client_version_string != NULL) { | |
791 | /* we are exec'ed by sshd2, so skip exchange of protocol version */ | |
792 | strlcpy(buf, client_version_string, sizeof(buf)); | |
793 | } else { | |
794 | /* Send our protocol version identification. */ | |
795 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
796 | PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION); | |
797 | if (write(sock_out, buf, strlen(buf)) != strlen(buf)) | |
798 | fatal("Could not write ident string to %s.", get_remote_ipaddr()); | |
799 | ||
800 | /* Read other side\'s version identification. */ | |
801 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
802 | if (read(sock_in, &buf[i], 1) != 1) | |
803 | fatal("Did not receive ident string from %s.", get_remote_ipaddr()); | |
804 | if (buf[i] == '\r') { | |
805 | buf[i] = '\n'; | |
806 | buf[i + 1] = 0; | |
807 | break; | |
808 | } | |
809 | if (buf[i] == '\n') { | |
810 | /* buf[i] == '\n' */ | |
811 | buf[i + 1] = 0; | |
812 | break; | |
813 | } | |
814 | } | |
815 | buf[sizeof(buf) - 1] = 0; | |
8efc0c15 | 816 | } |
5260325f | 817 | |
818 | /* Check that the versions match. In future this might accept | |
819 | several versions and set appropriate flags to handle them. */ | |
820 | if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, | |
821 | remote_version) != 3) { | |
822 | const char *s = "Protocol mismatch.\n"; | |
823 | (void) write(sock_out, s, strlen(s)); | |
824 | close(sock_in); | |
825 | close(sock_out); | |
826 | fatal("Bad protocol version identification '%.100s' from %s", | |
827 | buf, get_remote_ipaddr()); | |
828 | } | |
829 | debug("Client protocol version %d.%d; client software version %.100s", | |
830 | remote_major, remote_minor, remote_version); | |
831 | if (remote_major != PROTOCOL_MAJOR) { | |
832 | const char *s = "Protocol major versions differ.\n"; | |
833 | (void) write(sock_out, s, strlen(s)); | |
834 | close(sock_in); | |
835 | close(sock_out); | |
836 | fatal("Protocol major versions differ for %s: %d vs. %d", | |
837 | get_remote_ipaddr(), | |
838 | PROTOCOL_MAJOR, remote_major); | |
8efc0c15 | 839 | } |
5260325f | 840 | /* Check that the client has sufficiently high software version. */ |
841 | if (remote_major == 1 && remote_minor < 3) | |
842 | packet_disconnect("Your ssh version is too old and is no longer supported. Please install a newer version."); | |
843 | ||
844 | if (remote_major == 1 && remote_minor == 3) { | |
845 | enable_compat13(); | |
846 | if (strcmp(remote_version, "OpenSSH-1.1") != 0) { | |
847 | debug("Agent forwarding disabled, remote version is not compatible."); | |
848 | no_agent_forwarding_flag = 1; | |
849 | } | |
850 | } | |
851 | /* Check that the connection comes from a privileged port. Rhosts- | |
852 | and Rhosts-RSA-Authentication only make sense from priviledged | |
853 | programs. Of course, if the intruder has root access on his | |
854 | local machine, he can connect from any port. So do not use | |
855 | these authentication methods from machines that you do not trust. */ | |
856 | if (remote_port >= IPPORT_RESERVED || | |
857 | remote_port < IPPORT_RESERVED / 2) { | |
858 | options.rhosts_authentication = 0; | |
859 | options.rhosts_rsa_authentication = 0; | |
860 | } | |
861 | packet_set_nonblocking(); | |
862 | ||
863 | /* Handle the connection. */ | |
864 | do_connection(); | |
8efc0c15 | 865 | |
866 | #ifdef KRB4 | |
5260325f | 867 | /* Cleanup user's ticket cache file. */ |
868 | if (options.kerberos_ticket_cleanup) | |
869 | (void) dest_tkt(); | |
8efc0c15 | 870 | #endif /* KRB4 */ |
871 | ||
5260325f | 872 | /* Cleanup user's local Xauthority file. */ |
873 | if (xauthfile) | |
874 | unlink(xauthfile); | |
8efc0c15 | 875 | |
5260325f | 876 | /* The connection has been terminated. */ |
877 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 878 | |
5aecb327 | 879 | #ifdef HAVE_LIBPAM |
5260325f | 880 | { |
881 | int retval; | |
8efc0c15 | 882 | |
5260325f | 883 | if (pamh != NULL) { |
884 | debug("Closing PAM session."); | |
885 | retval = pam_close_session((pam_handle_t *)pamh, 0); | |
8efc0c15 | 886 | |
5260325f | 887 | debug("Terminating PAM library."); |
888 | if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS) | |
889 | log("Cannot release PAM authentication."); | |
890 | ||
891 | fatal_remove_cleanup(&pam_cleanup_proc, NULL); | |
892 | } | |
893 | } | |
894 | #endif /* HAVE_LIBPAM */ | |
8efc0c15 | 895 | |
5260325f | 896 | packet_close(); |
897 | exit(0); | |
898 | } | |
8efc0c15 | 899 | |
5260325f | 900 | /* |
901 | * Process an incoming connection. Protocol version identifiers have already | |
902 | * been exchanged. This sends server key and performs the key exchange. | |
903 | * Server and host keys will no longer be needed after this functions. | |
904 | */ | |
e7c0f9d5 | 905 | void |
906 | do_connection() | |
8efc0c15 | 907 | { |
5260325f | 908 | int i, len; |
909 | BIGNUM *session_key_int; | |
910 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; | |
911 | unsigned char check_bytes[8]; | |
912 | char *user; | |
913 | unsigned int cipher_type, auth_mask, protocol_flags; | |
914 | int plen, slen; | |
915 | u_int32_t rand = 0; | |
916 | ||
917 | /* Generate check bytes that the client must send back in the user | |
918 | packet in order for it to be accepted; this is used to defy ip | |
919 | spoofing attacks. Note that this only works against somebody | |
920 | doing IP spoofing from a remote machine; any machine on the | |
921 | local network can still see outgoing packets and catch the | |
922 | random cookie. This only affects rhosts authentication, and | |
923 | this is one of the reasons why it is inherently insecure. */ | |
924 | for (i = 0; i < 8; i++) { | |
925 | if (i % 4 == 0) | |
926 | rand = arc4random(); | |
927 | check_bytes[i] = rand & 0xff; | |
928 | rand >>= 8; | |
929 | } | |
930 | ||
931 | /* Send our public key. We include in the packet 64 bits of | |
932 | random data that must be matched in the reply in order to | |
933 | prevent IP spoofing. */ | |
934 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
935 | for (i = 0; i < 8; i++) | |
936 | packet_put_char(check_bytes[i]); | |
937 | ||
938 | /* Store our public server RSA key. */ | |
939 | packet_put_int(BN_num_bits(public_key->n)); | |
940 | packet_put_bignum(public_key->e); | |
941 | packet_put_bignum(public_key->n); | |
942 | ||
943 | /* Store our public host RSA key. */ | |
944 | packet_put_int(BN_num_bits(sensitive_data.host_key->n)); | |
945 | packet_put_bignum(sensitive_data.host_key->e); | |
946 | packet_put_bignum(sensitive_data.host_key->n); | |
947 | ||
948 | /* Put protocol flags. */ | |
949 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
950 | ||
951 | /* Declare which ciphers we support. */ | |
952 | packet_put_int(cipher_mask()); | |
953 | ||
954 | /* Declare supported authentication types. */ | |
955 | auth_mask = 0; | |
956 | if (options.rhosts_authentication) | |
957 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
958 | if (options.rhosts_rsa_authentication) | |
959 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
960 | if (options.rsa_authentication) | |
961 | auth_mask |= 1 << SSH_AUTH_RSA; | |
8efc0c15 | 962 | #ifdef KRB4 |
5260325f | 963 | if (options.kerberos_authentication) |
964 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 965 | #endif |
966 | #ifdef AFS | |
5260325f | 967 | if (options.kerberos_tgt_passing) |
968 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
969 | if (options.afs_token_passing) | |
970 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 971 | #endif |
5260325f | 972 | #ifdef SKEY |
973 | if (options.skey_authentication == 1) | |
974 | auth_mask |= 1 << SSH_AUTH_TIS; | |
975 | #endif | |
976 | if (options.password_authentication) | |
977 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
978 | packet_put_int(auth_mask); | |
979 | ||
980 | /* Send the packet and wait for it to be sent. */ | |
981 | packet_send(); | |
982 | packet_write_wait(); | |
983 | ||
984 | debug("Sent %d bit public key and %d bit host key.", | |
985 | BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n)); | |
986 | ||
987 | /* Read clients reply (cipher type and session key). */ | |
988 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
989 | ||
990 | /* Get cipher type. */ | |
991 | cipher_type = packet_get_char(); | |
992 | ||
993 | /* Get check bytes from the packet. These must match those we | |
994 | sent earlier with the public key packet. */ | |
995 | for (i = 0; i < 8; i++) | |
996 | if (check_bytes[i] != packet_get_char()) | |
997 | packet_disconnect("IP Spoofing check bytes do not match."); | |
998 | ||
999 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1000 | ||
1001 | /* Get the encrypted integer. */ | |
1002 | session_key_int = BN_new(); | |
1003 | packet_get_bignum(session_key_int, &slen); | |
1004 | ||
1005 | /* Get protocol flags. */ | |
1006 | protocol_flags = packet_get_int(); | |
1007 | packet_set_protocol_flags(protocol_flags); | |
1008 | ||
1009 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1010 | ||
1011 | /* Decrypt it using our private server key and private host key | |
1012 | (key with larger modulus first). */ | |
1013 | if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) { | |
1014 | /* Private key has bigger modulus. */ | |
1015 | if (BN_num_bits(sensitive_data.private_key->n) < | |
1016 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
1017 | fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1018 | get_remote_ipaddr(), | |
1019 | BN_num_bits(sensitive_data.private_key->n), | |
1020 | BN_num_bits(sensitive_data.host_key->n), | |
1021 | SSH_KEY_BITS_RESERVED); | |
1022 | } | |
1023 | rsa_private_decrypt(session_key_int, session_key_int, | |
1024 | sensitive_data.private_key); | |
1025 | rsa_private_decrypt(session_key_int, session_key_int, | |
1026 | sensitive_data.host_key); | |
1027 | } else { | |
1028 | /* Host key has bigger modulus (or they are equal). */ | |
1029 | if (BN_num_bits(sensitive_data.host_key->n) < | |
1030 | BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) { | |
1031 | fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d", | |
1032 | get_remote_ipaddr(), | |
1033 | BN_num_bits(sensitive_data.host_key->n), | |
1034 | BN_num_bits(sensitive_data.private_key->n), | |
1035 | SSH_KEY_BITS_RESERVED); | |
1036 | } | |
1037 | rsa_private_decrypt(session_key_int, session_key_int, | |
1038 | sensitive_data.host_key); | |
1039 | rsa_private_decrypt(session_key_int, session_key_int, | |
1040 | sensitive_data.private_key); | |
1041 | } | |
1042 | ||
1043 | /* Compute session id for this session. */ | |
1044 | compute_session_id(session_id, check_bytes, | |
1045 | sensitive_data.host_key->n, | |
1046 | sensitive_data.private_key->n); | |
1047 | ||
1048 | /* Extract session key from the decrypted integer. The key is in | |
1049 | the least significant 256 bits of the integer; the first byte | |
1050 | of the key is in the highest bits. */ | |
1051 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1052 | len = BN_num_bytes(session_key_int); | |
1053 | if (len < 0 || len > sizeof(session_key)) | |
1054 | fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d", | |
1055 | get_remote_ipaddr(), | |
1056 | len, sizeof(session_key)); | |
1057 | memset(session_key, 0, sizeof(session_key)); | |
1058 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
1059 | ||
1060 | /* Xor the first 16 bytes of the session key with the session id. */ | |
1061 | for (i = 0; i < 16; i++) | |
1062 | session_key[i] ^= session_id[i]; | |
1063 | ||
1064 | /* Destroy the decrypted integer. It is no longer needed. */ | |
1065 | BN_clear_free(session_key_int); | |
1066 | ||
1067 | /* Set the session key. From this on all communications will be encrypted. */ | |
1068 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1069 | ||
1070 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1071 | memset(session_key, 0, sizeof(session_key)); | |
1072 | ||
1073 | debug("Received session key; encryption turned on."); | |
1074 | ||
1075 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1076 | packet_start(SSH_SMSG_SUCCESS); | |
1077 | packet_send(); | |
1078 | packet_write_wait(); | |
1079 | ||
1080 | /* Get the name of the user that we wish to log in as. */ | |
1081 | packet_read_expect(&plen, SSH_CMSG_USER); | |
1082 | ||
1083 | /* Get the user name. */ | |
1084 | { | |
1085 | int ulen; | |
1086 | user = packet_get_string(&ulen); | |
1087 | packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); | |
1088 | } | |
1089 | ||
1090 | /* Destroy the private and public keys. They will no longer be needed. */ | |
1091 | RSA_free(public_key); | |
1092 | RSA_free(sensitive_data.private_key); | |
1093 | RSA_free(sensitive_data.host_key); | |
8efc0c15 | 1094 | |
5260325f | 1095 | setproctitle("%s", user); |
1096 | /* Do the authentication. */ | |
1097 | do_authentication(user); | |
1098 | } | |
8efc0c15 | 1099 | |
5260325f | 1100 | /* |
1101 | * Check if the user is allowed to log in via ssh. If user is listed in | |
1102 | * DenyUsers or user's primary group is listed in DenyGroups, false will | |
1103 | * be returned. If AllowUsers isn't empty and user isn't listed there, or | |
1104 | * if AllowGroups isn't empty and user isn't listed there, false will be | |
1105 | * returned. Otherwise true is returned. | |
1106 | * XXX This function should also check if user has a valid shell | |
1107 | */ | |
8efc0c15 | 1108 | static int |
5260325f | 1109 | allowed_user(struct passwd * pw) |
8efc0c15 | 1110 | { |
5260325f | 1111 | struct group *grp; |
1112 | int i; | |
1113 | ||
1114 | /* Shouldn't be called if pw is NULL, but better safe than sorry... */ | |
1115 | if (!pw) | |
1116 | return 0; | |
1117 | ||
1118 | /* XXX Should check for valid login shell */ | |
1119 | ||
1120 | /* Return false if user is listed in DenyUsers */ | |
1121 | if (options.num_deny_users > 0) { | |
1122 | if (!pw->pw_name) | |
1123 | return 0; | |
1124 | for (i = 0; i < options.num_deny_users; i++) | |
1125 | if (match_pattern(pw->pw_name, options.deny_users[i])) | |
1126 | return 0; | |
1127 | } | |
1128 | /* Return false if AllowUsers isn't empty and user isn't listed | |
1129 | there */ | |
1130 | if (options.num_allow_users > 0) { | |
1131 | if (!pw->pw_name) | |
1132 | return 0; | |
1133 | for (i = 0; i < options.num_allow_users; i++) | |
1134 | if (match_pattern(pw->pw_name, options.allow_users[i])) | |
1135 | break; | |
1136 | /* i < options.num_allow_users iff we break for loop */ | |
1137 | if (i >= options.num_allow_users) | |
1138 | return 0; | |
1139 | } | |
1140 | /* Get the primary group name if we need it. Return false if it fails */ | |
1141 | if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { | |
1142 | grp = getgrgid(pw->pw_gid); | |
1143 | if (!grp) | |
1144 | return 0; | |
1145 | ||
1146 | /* Return false if user's group is listed in DenyGroups */ | |
1147 | if (options.num_deny_groups > 0) { | |
1148 | if (!grp->gr_name) | |
1149 | return 0; | |
1150 | for (i = 0; i < options.num_deny_groups; i++) | |
1151 | if (match_pattern(grp->gr_name, options.deny_groups[i])) | |
1152 | return 0; | |
1153 | } | |
1154 | /* Return false if AllowGroups isn't empty and user's | |
1155 | group isn't listed there */ | |
1156 | if (options.num_allow_groups > 0) { | |
1157 | if (!grp->gr_name) | |
1158 | return 0; | |
1159 | for (i = 0; i < options.num_allow_groups; i++) | |
1160 | if (match_pattern(grp->gr_name, options.allow_groups[i])) | |
1161 | break; | |
1162 | /* i < options.num_allow_groups iff we break for | |
1163 | loop */ | |
1164 | if (i >= options.num_allow_groups) | |
1165 | return 0; | |
1166 | } | |
1167 | } | |
1168 | /* We found no reason not to let this user try to log on... */ | |
1169 | return 1; | |
8efc0c15 | 1170 | } |
1171 | ||
5260325f | 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 | |
1175 | * in as (received from the client). | |
1176 | */ | |
8efc0c15 | 1177 | void |
e7c0f9d5 | 1178 | do_authentication(char *user) |
8efc0c15 | 1179 | { |
5260325f | 1180 | struct passwd *pw, pwcopy; |
e7c0f9d5 | 1181 | |
8efc0c15 | 1182 | #ifdef AFS |
5260325f | 1183 | /* If machine has AFS, set process authentication group. */ |
1184 | if (k_hasafs()) { | |
1185 | k_setpag(); | |
1186 | k_unlog(); | |
1187 | } | |
8efc0c15 | 1188 | #endif /* AFS */ |
5260325f | 1189 | |
1190 | /* Verify that the user is a valid user. */ | |
1191 | pw = getpwnam(user); | |
1192 | if (!pw || !allowed_user(pw)) | |
1193 | do_fake_authloop(user); | |
1194 | ||
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; | |
8efc0c15 | 1204 | |
5aecb327 | 1205 | #ifdef HAVE_LIBPAM |
5260325f | 1206 | { |
1207 | int pam_retval; | |
1208 | ||
1209 | debug("Starting up PAM with username \"%.200s\"", pw->pw_name); | |
e7c0f9d5 | 1210 | |
5260325f | 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 | |
5260325f | 1215 | fatal_add_cleanup(&pam_cleanup_proc, NULL); |
1216 | } | |
5aecb327 | 1217 | #endif |
0183ea1c | 1218 | |
5260325f | 1219 | /* If we are not running as root, the user must have the same uid |
1220 | as the server. */ | |
1221 | if (getuid() != 0 && pw->pw_uid != getuid()) | |
1222 | packet_disconnect("Cannot change user when server not running as root."); | |
8efc0c15 | 1223 | |
5260325f | 1224 | debug("Attempting authentication for %.100s.", user); |
8efc0c15 | 1225 | |
5260325f | 1226 | /* If the user has no password, accept authentication immediately. */ |
1227 | if (options.password_authentication && | |
8efc0c15 | 1228 | #ifdef KRB4 |
5260325f | 1229 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && |
8efc0c15 | 1230 | #endif /* KRB4 */ |
5260325f | 1231 | auth_password(pw, "")) { |
1232 | /* Authentication with empty password succeeded. */ | |
1233 | log("Login for user %s from %.100s, accepted without authentication.", | |
1234 | pw->pw_name, get_remote_ipaddr()); | |
1235 | } else { | |
1236 | /* Loop until the user has been authenticated or the | |
1237 | connection is closed, do_authloop() returns only if | |
1238 | authentication is successfull */ | |
1239 | do_authloop(pw); | |
1240 | } | |
1241 | ||
1242 | /* Check if the user is logging in as root and root logins are disallowed. */ | |
1243 | if (pw->pw_uid == 0 && !options.permit_root_login) { | |
1244 | if (forced_command) | |
1245 | log("Root login accepted for forced command."); | |
1246 | else | |
1247 | packet_disconnect("ROOT LOGIN REFUSED FROM %.200s", | |
1248 | get_canonical_hostname()); | |
1249 | } | |
1250 | /* The user has been authenticated and accepted. */ | |
1251 | packet_start(SSH_SMSG_SUCCESS); | |
1252 | packet_send(); | |
1253 | packet_write_wait(); | |
1254 | ||
1255 | /* Perform session preparation. */ | |
1256 | do_authenticated(pw); | |
e7c0f9d5 | 1257 | } |
8efc0c15 | 1258 | |
5260325f | 1259 | #define AUTH_FAIL_MAX 6 |
1260 | #define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2) | |
1261 | #define AUTH_FAIL_MSG "Too many authentication failures for %.100s" | |
e7c0f9d5 | 1262 | |
5260325f | 1263 | /* |
1264 | * read packets and try to authenticate local user *pw. | |
1265 | * return if authentication is successfull | |
1266 | */ | |
e7c0f9d5 | 1267 | void |
5260325f | 1268 | do_authloop(struct passwd * pw) |
e7c0f9d5 | 1269 | { |
5260325f | 1270 | int attempt = 0; |
1271 | unsigned int bits; | |
1272 | BIGNUM *client_host_key_e, *client_host_key_n; | |
1273 | BIGNUM *n; | |
1274 | char *client_user = NULL, *password = NULL; | |
1275 | char user[1024]; | |
1276 | int plen, dlen, nlen, ulen, elen; | |
1277 | int type = 0; | |
1278 | void (*authlog) (const char *fmt,...) = verbose; | |
c75a1a66 | 1279 | #ifdef HAVE_LIBPAM |
5260325f | 1280 | int pam_retval; |
c75a1a66 | 1281 | #endif /* HAVE_LIBPAM */ |
e7c0f9d5 | 1282 | |
5260325f | 1283 | /* Indicate that authentication is needed. */ |
1284 | packet_start(SSH_SMSG_FAILURE); | |
1285 | packet_send(); | |
1286 | packet_write_wait(); | |
e7c0f9d5 | 1287 | |
5260325f | 1288 | for (attempt = 1;; attempt++) { |
1289 | int authenticated = 0; | |
1290 | strlcpy(user, "", sizeof user); | |
e7c0f9d5 | 1291 | |
5260325f | 1292 | /* Get a packet from the client. */ |
1293 | type = packet_read(&plen); | |
1294 | ||
1295 | /* Process the packet. */ | |
1296 | switch (type) { | |
e7c0f9d5 | 1297 | #ifdef AFS |
5260325f | 1298 | case SSH_CMSG_HAVE_KERBEROS_TGT: |
1299 | if (!options.kerberos_tgt_passing) { | |
1300 | /* packet_get_all(); */ | |
1301 | verbose("Kerberos tgt passing disabled."); | |
1302 | break; | |
1303 | } else { | |
1304 | /* Accept Kerberos tgt. */ | |
1305 | char *tgt = packet_get_string(&dlen); | |
1306 | packet_integrity_check(plen, 4 + dlen, type); | |
1307 | if (!auth_kerberos_tgt(pw, tgt)) | |
1308 | verbose("Kerberos tgt REFUSED for %s", pw->pw_name); | |
1309 | xfree(tgt); | |
1310 | } | |
1311 | continue; | |
1312 | ||
1313 | case SSH_CMSG_HAVE_AFS_TOKEN: | |
1314 | if (!options.afs_token_passing || !k_hasafs()) { | |
1315 | /* packet_get_all(); */ | |
1316 | verbose("AFS token passing disabled."); | |
1317 | break; | |
1318 | } else { | |
1319 | /* Accept AFS token. */ | |
1320 | char *token_string = packet_get_string(&dlen); | |
1321 | packet_integrity_check(plen, 4 + dlen, type); | |
1322 | if (!auth_afs_token(pw, token_string)) | |
1323 | verbose("AFS token REFUSED for %s", pw->pw_name); | |
1324 | xfree(token_string); | |
1325 | } | |
1326 | continue; | |
8efc0c15 | 1327 | #endif /* AFS */ |
e7c0f9d5 | 1328 | #ifdef KRB4 |
5260325f | 1329 | case SSH_CMSG_AUTH_KERBEROS: |
1330 | if (!options.kerberos_authentication) { | |
1331 | /* packet_get_all(); */ | |
1332 | verbose("Kerberos authentication disabled."); | |
1333 | break; | |
1334 | } else { | |
1335 | /* Try Kerberos v4 authentication. */ | |
1336 | KTEXT_ST auth; | |
1337 | char *tkt_user = NULL; | |
1338 | char *kdata = packet_get_string((unsigned int *) &auth.length); | |
1339 | packet_integrity_check(plen, 4 + auth.length, type); | |
1340 | ||
1341 | if (auth.length < MAX_KTXT_LEN) | |
1342 | memcpy(auth.dat, kdata, auth.length); | |
1343 | xfree(kdata); | |
1344 | ||
1345 | authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user); | |
1346 | ||
1347 | if (authenticated) { | |
1348 | snprintf(user, sizeof user, " tktuser %s", tkt_user); | |
1349 | xfree(tkt_user); | |
1350 | } | |
1351 | } | |
1352 | break; | |
e7c0f9d5 | 1353 | #endif /* KRB4 */ |
5260325f | 1354 | |
1355 | case SSH_CMSG_AUTH_RHOSTS: | |
1356 | if (!options.rhosts_authentication) { | |
1357 | verbose("Rhosts authentication disabled."); | |
1358 | break; | |
1359 | } | |
1360 | /* Get client user name. Note that we just have | |
1361 | to trust the client; this is one reason why | |
1362 | rhosts authentication is insecure. (Another is | |
1363 | IP-spoofing on a local network.) */ | |
1364 | client_user = packet_get_string(&ulen); | |
1365 | packet_integrity_check(plen, 4 + ulen, type); | |
1366 | ||
1367 | /* Try to authenticate using /etc/hosts.equiv and | |
1368 | .rhosts. */ | |
1369 | authenticated = auth_rhosts(pw, client_user); | |
1370 | ||
1371 | snprintf(user, sizeof user, " ruser %s", client_user); | |
5aecb327 | 1372 | #ifndef HAVE_LIBPAM |
5260325f | 1373 | xfree(client_user); |
5aecb327 | 1374 | #endif /* HAVE_LIBPAM */ |
5260325f | 1375 | break; |
1376 | ||
1377 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
1378 | if (!options.rhosts_rsa_authentication) { | |
1379 | verbose("Rhosts with RSA authentication disabled."); | |
1380 | break; | |
1381 | } | |
1382 | /* Get client user name. Note that we just have | |
1383 | to trust the client; root on the client machine | |
1384 | can claim to be any user. */ | |
1385 | client_user = packet_get_string(&ulen); | |
1386 | ||
1387 | /* Get the client host key. */ | |
1388 | client_host_key_e = BN_new(); | |
1389 | client_host_key_n = BN_new(); | |
1390 | bits = packet_get_int(); | |
1391 | packet_get_bignum(client_host_key_e, &elen); | |
1392 | packet_get_bignum(client_host_key_n, &nlen); | |
1393 | ||
1394 | if (bits != BN_num_bits(client_host_key_n)) | |
1395 | error("Warning: keysize mismatch for client_host_key: " | |
1396 | "actual %d, announced %d", BN_num_bits(client_host_key_n), bits); | |
1397 | packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); | |
1398 | ||
1399 | authenticated = auth_rhosts_rsa(pw, client_user, | |
1400 | client_host_key_e, client_host_key_n); | |
1401 | BN_clear_free(client_host_key_e); | |
1402 | BN_clear_free(client_host_key_n); | |
1403 | ||
1404 | snprintf(user, sizeof user, " ruser %s", client_user); | |
5aecb327 | 1405 | #ifndef HAVE_LIBPAM |
5260325f | 1406 | xfree(client_user); |
5aecb327 | 1407 | #endif /* HAVE_LIBPAM */ |
5260325f | 1408 | break; |
1409 | ||
1410 | case SSH_CMSG_AUTH_RSA: | |
1411 | if (!options.rsa_authentication) { | |
1412 | verbose("RSA authentication disabled."); | |
1413 | break; | |
1414 | } | |
1415 | /* RSA authentication requested. */ | |
1416 | n = BN_new(); | |
1417 | packet_get_bignum(n, &nlen); | |
1418 | packet_integrity_check(plen, nlen, type); | |
1419 | authenticated = auth_rsa(pw, n); | |
1420 | BN_clear_free(n); | |
1421 | break; | |
1422 | ||
1423 | case SSH_CMSG_AUTH_PASSWORD: | |
1424 | if (!options.password_authentication) { | |
1425 | verbose("Password authentication disabled."); | |
1426 | break; | |
1427 | } | |
1428 | /* Read user password. It is in plain text, but | |
1429 | was transmitted over the encrypted channel so | |
1430 | it is not visible to an outside observer. */ | |
1431 | password = packet_get_string(&dlen); | |
1432 | packet_integrity_check(plen, 4 + dlen, type); | |
1433 | ||
5aecb327 | 1434 | #ifdef HAVE_LIBPAM |
5260325f | 1435 | /* Do PAM auth with password */ |
1436 | pampasswd = password; | |
1437 | pam_retval = pam_authenticate((pam_handle_t *)pamh, 0); | |
1438 | if (pam_retval == PAM_SUCCESS) { | |
1439 | log("PAM Password authentication accepted for user \"%.100s\"", pw->pw_name); | |
1440 | authenticated = 1; | |
1441 | break; | |
1442 | } | |
1443 | ||
1444 | log("PAM Password authentication for \"%.100s\" failed: %s", | |
1445 | pw->pw_name, PAM_STRERROR((pam_handle_t *)pamh, pam_retval)); | |
1446 | break; | |
5aecb327 | 1447 | #else /* HAVE_LIBPAM */ |
5260325f | 1448 | /* Try authentication with the password. */ |
1449 | authenticated = auth_password(pw, password); | |
1450 | ||
1451 | memset(password, 0, strlen(password)); | |
1452 | xfree(password); | |
1453 | break; | |
e7c0f9d5 | 1454 | #endif /* HAVE_LIBPAM */ |
5260325f | 1455 | |
1456 | #ifdef SKEY | |
1457 | case SSH_CMSG_AUTH_TIS: | |
1458 | debug("rcvd SSH_CMSG_AUTH_TIS"); | |
1459 | if (options.skey_authentication == 1) { | |
1460 | char *skeyinfo = skey_keyinfo(pw->pw_name); | |
1461 | if (skeyinfo == NULL) { | |
1462 | debug("generating fake skeyinfo for %.100s.", pw->pw_name); | |
1463 | skeyinfo = skey_fake_keyinfo(pw->pw_name); | |
1464 | } | |
1465 | if (skeyinfo != NULL) { | |
1466 | /* we send our s/key- in | |
1467 | tis-challenge messages */ | |
1468 | debug("sending challenge '%s'", skeyinfo); | |
1469 | packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); | |
1470 | packet_put_string(skeyinfo, strlen(skeyinfo)); | |
1471 | packet_send(); | |
1472 | packet_write_wait(); | |
1473 | continue; | |
1474 | } | |
1475 | } | |
1476 | break; | |
1477 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
1478 | debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); | |
1479 | if (options.skey_authentication == 1) { | |
1480 | char *response = packet_get_string(&dlen); | |
1481 | debug("skey response == '%s'", response); | |
1482 | packet_integrity_check(plen, 4 + dlen, type); | |
1483 | authenticated = (skey_haskey(pw->pw_name) == 0 && | |
1484 | skey_passcheck(pw->pw_name, response) != -1); | |
1485 | xfree(response); | |
1486 | } | |
1487 | break; | |
1488 | #else | |
1489 | case SSH_CMSG_AUTH_TIS: | |
1490 | /* TIS Authentication is unsupported */ | |
1491 | log("TIS authentication unsupported."); | |
1492 | break; | |
1493 | #endif | |
1494 | ||
1495 | default: | |
1496 | /* Any unknown messages will be ignored (and | |
1497 | failure returned) during authentication. */ | |
1498 | log("Unknown message during authentication: type %d", type); | |
1499 | break; | |
1500 | } | |
1501 | ||
1502 | /* Raise logging level */ | |
1503 | if (authenticated || | |
1504 | attempt == AUTH_FAIL_LOG || | |
1505 | type == SSH_CMSG_AUTH_PASSWORD) | |
1506 | authlog = log; | |
1507 | ||
1508 | authlog("%s %s for %.200s from %.200s port %d%s", | |
1509 | authenticated ? "Accepted" : "Failed", | |
1510 | get_authname(type), | |
1511 | pw->pw_uid == 0 ? "ROOT" : pw->pw_name, | |
1512 | get_remote_ipaddr(), | |
1513 | get_remote_port(), | |
1514 | user); | |
8efc0c15 | 1515 | |
5aecb327 | 1516 | #ifdef HAVE_LIBPAM |
5260325f | 1517 | do_pam_account_and_session(pw->pw_name, client_user, |
1518 | get_canonical_hostname()); | |
d813bc69 | 1519 | |
5260325f | 1520 | /* Clean up */ |
1521 | if (client_user != NULL) | |
1522 | xfree(client_user); | |
d813bc69 | 1523 | |
5260325f | 1524 | if (password != NULL) { |
1525 | memset(password, 0, strlen(password)); | |
1526 | xfree(password); | |
1527 | } | |
5aecb327 | 1528 | #endif /* HAVE_LIBPAM */ |
5260325f | 1529 | |
1530 | if (authenticated) | |
1531 | return; | |
1532 | ||
1533 | if (attempt > AUTH_FAIL_MAX) | |
1534 | packet_disconnect(AUTH_FAIL_MSG, pw->pw_name); | |
1535 | ||
1536 | /* Send a message indicating that the authentication attempt failed. */ | |
1537 | packet_start(SSH_SMSG_FAILURE); | |
1538 | packet_send(); | |
1539 | packet_write_wait(); | |
1540 | } | |
8efc0c15 | 1541 | } |
1542 | ||
5260325f | 1543 | /* |
1544 | * The user does not exist or access is denied, | |
1545 | * but fake indication that authentication is needed. | |
1546 | */ | |
e7c0f9d5 | 1547 | void |
1548 | do_fake_authloop(char *user) | |
0183ea1c | 1549 | { |
5260325f | 1550 | int attempt = 0; |
1551 | ||
1552 | log("Faking authloop for illegal user %.200s from %.200s port %d", | |
1553 | user, | |
1554 | get_remote_ipaddr(), | |
1555 | get_remote_port()); | |
1556 | ||
1557 | /* Indicate that authentication is needed. */ | |
1558 | packet_start(SSH_SMSG_FAILURE); | |
1559 | packet_send(); | |
1560 | packet_write_wait(); | |
1561 | ||
1562 | /* Keep reading packets, and always respond with a failure. This | |
1563 | is to avoid disclosing whether such a user really exists. */ | |
1564 | for (attempt = 1;; attempt++) { | |
1565 | /* Read a packet. This will not return if the client | |
1566 | disconnects. */ | |
1567 | int plen; | |
1568 | int type = packet_read(&plen); | |
e7c0f9d5 | 1569 | #ifdef SKEY |
5260325f | 1570 | int dlen; |
1571 | char *password, *skeyinfo; | |
1572 | if (options.password_authentication && | |
1573 | options.skey_authentication == 1 && | |
1574 | type == SSH_CMSG_AUTH_PASSWORD && | |
1575 | (password = packet_get_string(&dlen)) != NULL && | |
1576 | dlen == 5 && | |
1577 | strncasecmp(password, "s/key", 5) == 0 && | |
1578 | (skeyinfo = skey_fake_keyinfo(user)) != NULL) { | |
1579 | /* Send a fake s/key challenge. */ | |
1580 | packet_send_debug(skeyinfo); | |
1581 | } | |
e7c0f9d5 | 1582 | #endif |
5260325f | 1583 | if (attempt > AUTH_FAIL_MAX) |
1584 | packet_disconnect(AUTH_FAIL_MSG, user); | |
1585 | ||
1586 | /* Send failure. This should be indistinguishable from a | |
1587 | failed authentication. */ | |
1588 | packet_start(SSH_SMSG_FAILURE); | |
1589 | packet_send(); | |
1590 | packet_write_wait(); | |
1591 | } | |
1592 | /* NOTREACHED */ | |
1593 | abort(); | |
0183ea1c | 1594 | } |
1595 | ||
e7c0f9d5 | 1596 | |
5260325f | 1597 | /* |
1598 | * Remove local Xauthority file. | |
1599 | */ | |
6a17f9c2 | 1600 | static void |
1601 | xauthfile_cleanup_proc(void *ignore) | |
1602 | { | |
5260325f | 1603 | debug("xauthfile_cleanup_proc called"); |
6a17f9c2 | 1604 | |
5260325f | 1605 | if (xauthfile != NULL) { |
1606 | unlink(xauthfile); | |
1607 | xfree(xauthfile); | |
1608 | xauthfile = NULL; | |
1609 | } | |
6a17f9c2 | 1610 | } |
1611 | ||
5260325f | 1612 | /* |
1613 | * Prepares for an interactive session. This is called after the user has | |
1614 | * been successfully authenticated. During this message exchange, pseudo | |
1615 | * terminals are allocated, X11, TCP/IP, and authentication agent forwardings | |
1616 | * are requested, etc. | |
1617 | */ | |
1618 | void | |
1619 | do_authenticated(struct passwd * pw) | |
8efc0c15 | 1620 | { |
5260325f | 1621 | int type; |
1622 | int compression_level = 0, enable_compression_after_reply = 0; | |
1623 | int have_pty = 0, ptyfd = -1, ttyfd = -1, xauthfd = -1; | |
1624 | int row, col, xpixel, ypixel, screen; | |
1625 | char ttyname[64]; | |
1626 | char *command, *term = NULL, *display = NULL, *proto = NULL, | |
1627 | *data = NULL; | |
1628 | struct group *grp; | |
1629 | gid_t tty_gid; | |
1630 | mode_t tty_mode; | |
1631 | int n_bytes; | |
1632 | ||
1633 | /* Cancel the alarm we set to limit the time taken for | |
1634 | authentication. */ | |
1635 | alarm(0); | |
1636 | ||
1637 | /* Inform the channel mechanism that we are the server side and | |
1638 | that the client may request to connect to any port at all. | |
1639 | (The user could do it anyway, and we wouldn\'t know what is | |
1640 | permitted except by the client telling us, so we can equally | |
1641 | well trust the client not to request anything bogus.) */ | |
1642 | channel_permit_all_opens(); | |
1643 | ||
1644 | /* We stay in this loop until the client requests to execute a | |
1645 | shell or a command. */ | |
1646 | while (1) { | |
1647 | int plen, dlen; | |
1648 | ||
1649 | /* Get a packet from the client. */ | |
1650 | type = packet_read(&plen); | |
1651 | ||
1652 | /* Process the packet. */ | |
1653 | switch (type) { | |
1654 | case SSH_CMSG_REQUEST_COMPRESSION: | |
1655 | packet_integrity_check(plen, 4, type); | |
1656 | compression_level = packet_get_int(); | |
1657 | if (compression_level < 1 || compression_level > 9) { | |
1658 | packet_send_debug("Received illegal compression level %d.", | |
1659 | compression_level); | |
1660 | goto fail; | |
1661 | } | |
1662 | /* Enable compression after we have responded with SUCCESS. */ | |
1663 | enable_compression_after_reply = 1; | |
1664 | break; | |
1665 | ||
1666 | case SSH_CMSG_REQUEST_PTY: | |
1667 | if (no_pty_flag) { | |
1668 | debug("Allocating a pty not permitted for this authentication."); | |
1669 | goto fail; | |
1670 | } | |
1671 | if (have_pty) | |
1672 | packet_disconnect("Protocol error: you already have a pty."); | |
1673 | ||
1674 | debug("Allocating pty."); | |
1675 | ||
1676 | /* Allocate a pty and open it. */ | |
1677 | if (!pty_allocate(&ptyfd, &ttyfd, ttyname)) { | |
1678 | error("Failed to allocate pty."); | |
1679 | goto fail; | |
1680 | } | |
1681 | /* Determine the group to make the owner of the tty. */ | |
1682 | grp = getgrnam("tty"); | |
1683 | if (grp) { | |
1684 | tty_gid = grp->gr_gid; | |
1685 | tty_mode = S_IRUSR | S_IWUSR | S_IWGRP; | |
1686 | } else { | |
1687 | tty_gid = pw->pw_gid; | |
1688 | tty_mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; | |
1689 | } | |
1690 | ||
1691 | /* Change ownership of the tty. */ | |
1692 | if (chown(ttyname, pw->pw_uid, tty_gid) < 0) | |
1693 | fatal("chown(%.100s, %d, %d) failed: %.100s", | |
1694 | ttyname, pw->pw_uid, tty_gid, strerror(errno)); | |
1695 | if (chmod(ttyname, tty_mode) < 0) | |
1696 | fatal("chmod(%.100s, 0%o) failed: %.100s", | |
1697 | ttyname, tty_mode, strerror(errno)); | |
1698 | ||
1699 | /* Get TERM from the packet. Note that the value may be of arbitrary length. */ | |
1700 | term = packet_get_string(&dlen); | |
1701 | packet_integrity_check(dlen, strlen(term), type); | |
1702 | /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */ | |
1703 | /* Remaining bytes */ | |
1704 | n_bytes = plen - (4 + dlen + 4 * 4); | |
1705 | ||
1706 | if (strcmp(term, "") == 0) | |
1707 | term = NULL; | |
1708 | ||
1709 | /* Get window size from the packet. */ | |
1710 | row = packet_get_int(); | |
1711 | col = packet_get_int(); | |
1712 | xpixel = packet_get_int(); | |
1713 | ypixel = packet_get_int(); | |
1714 | pty_change_window_size(ptyfd, row, col, xpixel, ypixel); | |
1715 | ||
1716 | /* Get tty modes from the packet. */ | |
1717 | tty_parse_modes(ttyfd, &n_bytes); | |
1718 | packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type); | |
1719 | ||
1720 | /* Indicate that we now have a pty. */ | |
1721 | have_pty = 1; | |
1722 | break; | |
1723 | ||
1724 | case SSH_CMSG_X11_REQUEST_FORWARDING: | |
1725 | if (!options.x11_forwarding) { | |
1726 | packet_send_debug("X11 forwarding disabled in server configuration file."); | |
1727 | goto fail; | |
1728 | } | |
8efc0c15 | 1729 | #ifdef XAUTH_PATH |
5260325f | 1730 | if (no_x11_forwarding_flag) { |
1731 | packet_send_debug("X11 forwarding not permitted for this authentication."); | |
1732 | goto fail; | |
1733 | } | |
1734 | debug("Received request for X11 forwarding with auth spoofing."); | |
1735 | if (display) | |
1736 | packet_disconnect("Protocol error: X11 display already set."); | |
1737 | { | |
1738 | int proto_len, data_len; | |
1739 | proto = packet_get_string(&proto_len); | |
1740 | data = packet_get_string(&data_len); | |
1741 | packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type); | |
1742 | } | |
1743 | if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER) | |
1744 | screen = packet_get_int(); | |
1745 | else | |
1746 | screen = 0; | |
1747 | display = x11_create_display_inet(screen); | |
1748 | if (!display) | |
1749 | goto fail; | |
1750 | ||
1751 | /* Setup to always have a local .Xauthority. */ | |
1752 | xauthfile = xmalloc(MAXPATHLEN); | |
1753 | snprintf(xauthfile, MAXPATHLEN, "/tmp/XauthXXXXXX"); | |
1754 | ||
1755 | if ((xauthfd = mkstemp(xauthfile)) != -1) { | |
1756 | fchown(xauthfd, pw->pw_uid, pw->pw_gid); | |
1757 | close(xauthfd); | |
1758 | fatal_add_cleanup(xauthfile_cleanup_proc, NULL); | |
1759 | } else { | |
1760 | xfree(xauthfile); | |
1761 | xauthfile = NULL; | |
1762 | } | |
1763 | break; | |
8efc0c15 | 1764 | #else /* XAUTH_PATH */ |
5260325f | 1765 | packet_send_debug("No xauth program; cannot forward with spoofing."); |
1766 | goto fail; | |
8efc0c15 | 1767 | #endif /* XAUTH_PATH */ |
1768 | ||
5260325f | 1769 | case SSH_CMSG_AGENT_REQUEST_FORWARDING: |
1770 | if (no_agent_forwarding_flag) { | |
1771 | debug("Authentication agent forwarding not permitted for this authentication."); | |
1772 | goto fail; | |
1773 | } | |
1774 | debug("Received authentication agent forwarding request."); | |
1775 | auth_input_request_forwarding(pw); | |
1776 | break; | |
1777 | ||
1778 | case SSH_CMSG_PORT_FORWARD_REQUEST: | |
1779 | if (no_port_forwarding_flag) { | |
1780 | debug("Port forwarding not permitted for this authentication."); | |
1781 | goto fail; | |
1782 | } | |
1783 | debug("Received TCP/IP port forwarding request."); | |
1784 | channel_input_port_forward_request(pw->pw_uid == 0); | |
1785 | break; | |
1786 | ||
1787 | case SSH_CMSG_MAX_PACKET_SIZE: | |
1788 | if (packet_set_maxsize(packet_get_int()) < 0) | |
1789 | goto fail; | |
1790 | break; | |
1791 | ||
1792 | case SSH_CMSG_EXEC_SHELL: | |
1793 | /* Set interactive/non-interactive mode. */ | |
1794 | packet_set_interactive(have_pty || display != NULL, | |
1795 | options.keepalives); | |
1796 | ||
1797 | if (forced_command != NULL) | |
1798 | goto do_forced_command; | |
1799 | debug("Forking shell."); | |
1800 | packet_integrity_check(plen, 0, type); | |
1801 | if (have_pty) | |
1802 | do_exec_pty(NULL, ptyfd, ttyfd, ttyname, pw, term, display, proto, data); | |
1803 | else | |
1804 | do_exec_no_pty(NULL, pw, display, proto, data); | |
1805 | return; | |
1806 | ||
1807 | case SSH_CMSG_EXEC_CMD: | |
1808 | /* Set interactive/non-interactive mode. */ | |
1809 | packet_set_interactive(have_pty || display != NULL, | |
1810 | options.keepalives); | |
1811 | ||
1812 | if (forced_command != NULL) | |
1813 | goto do_forced_command; | |
1814 | /* Get command from the packet. */ | |
1815 | { | |
1816 | int dlen; | |
1817 | command = packet_get_string(&dlen); | |
1818 | debug("Executing command '%.500s'", command); | |
1819 | packet_integrity_check(plen, 4 + dlen, type); | |
1820 | } | |
1821 | if (have_pty) | |
1822 | do_exec_pty(command, ptyfd, ttyfd, ttyname, pw, term, display, proto, data); | |
1823 | else | |
1824 | do_exec_no_pty(command, pw, display, proto, data); | |
1825 | xfree(command); | |
1826 | return; | |
1827 | ||
1828 | default: | |
1829 | /* Any unknown messages in this phase are ignored, | |
1830 | and a failure message is returned. */ | |
1831 | log("Unknown packet type received after authentication: %d", type); | |
1832 | goto fail; | |
1833 | } | |
8efc0c15 | 1834 | |
5260325f | 1835 | /* The request was successfully processed. */ |
1836 | packet_start(SSH_SMSG_SUCCESS); | |
1837 | packet_send(); | |
1838 | packet_write_wait(); | |
8efc0c15 | 1839 | |
5260325f | 1840 | /* Enable compression now that we have replied if appropriate. */ |
1841 | if (enable_compression_after_reply) { | |
1842 | enable_compression_after_reply = 0; | |
1843 | packet_start_compression(compression_level); | |
1844 | } | |
1845 | continue; | |
8efc0c15 | 1846 | |
5260325f | 1847 | fail: |
1848 | /* The request failed. */ | |
1849 | packet_start(SSH_SMSG_FAILURE); | |
1850 | packet_send(); | |
1851 | packet_write_wait(); | |
1852 | continue; | |
8efc0c15 | 1853 | |
5260325f | 1854 | do_forced_command: |
1855 | /* There is a forced command specified for this login. | |
1856 | Execute it. */ | |
1857 | debug("Executing forced command: %.900s", forced_command); | |
1858 | if (have_pty) | |
1859 | do_exec_pty(forced_command, ptyfd, ttyfd, ttyname, pw, term, display, proto, data); | |
1860 | else | |
1861 | do_exec_no_pty(forced_command, pw, display, proto, data); | |
1862 | return; | |
1863 | } | |
1864 | } | |
8efc0c15 | 1865 | |
5260325f | 1866 | /* |
1867 | * This is called to fork and execute a command when we have no tty. This | |
1868 | * will call do_child from the child, and server_loop from the parent after | |
1869 | * setting up file descriptors and such. | |
1870 | */ | |
1871 | void | |
1872 | do_exec_no_pty(const char *command, struct passwd * pw, | |
1873 | const char *display, const char *auth_proto, | |
1874 | const char *auth_data) | |
1875 | { | |
1876 | int pid; | |
8efc0c15 | 1877 | |
1878 | #ifdef USE_PIPES | |
5260325f | 1879 | int pin[2], pout[2], perr[2]; |
1880 | /* Allocate pipes for communicating with the program. */ | |
1881 | if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) | |
1882 | packet_disconnect("Could not create pipes: %.100s", | |
1883 | strerror(errno)); | |
8efc0c15 | 1884 | #else /* USE_PIPES */ |
5260325f | 1885 | int inout[2], err[2]; |
1886 | /* Uses socket pairs to communicate with the program. */ | |
1887 | if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || | |
1888 | socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) | |
1889 | packet_disconnect("Could not create socket pairs: %.100s", | |
1890 | strerror(errno)); | |
8efc0c15 | 1891 | #endif /* USE_PIPES */ |
8efc0c15 | 1892 | |
5260325f | 1893 | setproctitle("%s@notty", pw->pw_name); |
8efc0c15 | 1894 | |
5260325f | 1895 | /* Fork the child. */ |
1896 | if ((pid = fork()) == 0) { | |
1897 | /* Child. Reinitialize the log since the pid has changed. */ | |
1898 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
1899 | ||
1900 | /* Create a new session and process group since the 4.4BSD | |
1901 | setlogin() affects the entire process group. */ | |
1902 | if (setsid() < 0) | |
1903 | error("setsid failed: %.100s", strerror(errno)); | |
8efc0c15 | 1904 | |
1905 | #ifdef USE_PIPES | |
5260325f | 1906 | /* Redirect stdin. We close the parent side of the socket |
1907 | pair, and make the child side the standard input. */ | |
1908 | close(pin[1]); | |
1909 | if (dup2(pin[0], 0) < 0) | |
1910 | perror("dup2 stdin"); | |
1911 | close(pin[0]); | |
1912 | ||
1913 | /* Redirect stdout. */ | |
1914 | close(pout[0]); | |
1915 | if (dup2(pout[1], 1) < 0) | |
1916 | perror("dup2 stdout"); | |
1917 | close(pout[1]); | |
1918 | ||
1919 | /* Redirect stderr. */ | |
1920 | close(perr[0]); | |
1921 | if (dup2(perr[1], 2) < 0) | |
1922 | perror("dup2 stderr"); | |
1923 | close(perr[1]); | |
8efc0c15 | 1924 | #else /* USE_PIPES */ |
5260325f | 1925 | /* Redirect stdin, stdout, and stderr. Stdin and stdout |
1926 | will use the same socket, as some programs | |
1927 | (particularly rdist) seem to depend on it. */ | |
1928 | close(inout[1]); | |
1929 | close(err[1]); | |
1930 | if (dup2(inout[0], 0) < 0) /* stdin */ | |
1931 | perror("dup2 stdin"); | |
1932 | if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ | |
1933 | perror("dup2 stdout"); | |
1934 | if (dup2(err[0], 2) < 0) /* stderr */ | |
1935 | perror("dup2 stderr"); | |
8efc0c15 | 1936 | #endif /* USE_PIPES */ |
1937 | ||
5260325f | 1938 | /* Do processing for the child (exec command etc). */ |
1939 | do_child(command, pw, NULL, display, auth_proto, auth_data, NULL); | |
1940 | /* NOTREACHED */ | |
1941 | } | |
1942 | if (pid < 0) | |
1943 | packet_disconnect("fork failed: %.100s", strerror(errno)); | |
8efc0c15 | 1944 | #ifdef USE_PIPES |
5260325f | 1945 | /* We are the parent. Close the child sides of the pipes. */ |
1946 | close(pin[0]); | |
1947 | close(pout[1]); | |
1948 | close(perr[1]); | |
1949 | ||
1950 | /* Enter the interactive session. */ | |
1951 | server_loop(pid, pin[1], pout[0], perr[0]); | |
1952 | /* server_loop has closed pin[1], pout[1], and perr[1]. */ | |
8efc0c15 | 1953 | #else /* USE_PIPES */ |
5260325f | 1954 | /* We are the parent. Close the child sides of the socket pairs. */ |
1955 | close(inout[0]); | |
1956 | close(err[0]); | |
1957 | ||
1958 | /* Enter the interactive session. Note: server_loop must be able | |
1959 | to handle the case that fdin and fdout are the same. */ | |
1960 | server_loop(pid, inout[1], inout[1], err[1]); | |
1961 | /* server_loop has closed inout[1] and err[1]. */ | |
8efc0c15 | 1962 | #endif /* USE_PIPES */ |
1963 | } | |
1964 | ||
5260325f | 1965 | struct pty_cleanup_context { |
1966 | const char *ttyname; | |
1967 | int pid; | |
8efc0c15 | 1968 | }; |
1969 | ||
5260325f | 1970 | /* |
1971 | * Function to perform cleanup if we get aborted abnormally (e.g., due to a | |
1972 | * dropped connection). | |
1973 | */ | |
1974 | void | |
1975 | pty_cleanup_proc(void *context) | |
8efc0c15 | 1976 | { |
5260325f | 1977 | struct pty_cleanup_context *cu = context; |
8efc0c15 | 1978 | |
5260325f | 1979 | debug("pty_cleanup_proc called"); |
8efc0c15 | 1980 | |
5260325f | 1981 | /* Record that the user has logged out. */ |
1982 | record_logout(cu->pid, cu->ttyname); | |
8efc0c15 | 1983 | |
5260325f | 1984 | /* Release the pseudo-tty. */ |
1985 | pty_release(cu->ttyname); | |
8efc0c15 | 1986 | } |
1987 | ||
5260325f | 1988 | /* |
1989 | * This is called to fork and execute a command when we have a tty. This | |
1990 | * will call do_child from the child, and server_loop from the parent after | |
1991 | * setting up file descriptors, controlling tty, updating wtmp, utmp, | |
1992 | * lastlog, and other such operations. | |
1993 | */ | |
1994 | void | |
1995 | do_exec_pty(const char *command, int ptyfd, int ttyfd, | |
1996 | const char *ttyname, struct passwd * pw, const char *term, | |
1997 | const char *display, const char *auth_proto, | |
1998 | const char *auth_data) | |
8efc0c15 | 1999 | { |
5260325f | 2000 | int pid, fdout; |
2001 | const char *hostname; | |
2002 | time_t last_login_time; | |
2003 | char buf[100], *time_string; | |
2004 | FILE *f; | |
2005 | char line[256]; | |
2006 | struct stat st; | |
2007 | int quiet_login; | |
2008 | struct sockaddr_in from; | |
2009 | int fromlen; | |
2010 | struct pty_cleanup_context cleanup_context; | |
2011 | ||
2012 | /* Get remote host name. */ | |
2013 | hostname = get_canonical_hostname(); | |
2014 | ||
2015 | /* Get the time when the user last logged in. Buf will be set to | |
2016 | contain the hostname the last login was from. */ | |
2017 | if (!options.use_login) { | |
2018 | last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name, | |
2019 | buf, sizeof(buf)); | |
8efc0c15 | 2020 | } |
5260325f | 2021 | setproctitle("%s@%s", pw->pw_name, strrchr(ttyname, '/') + 1); |
2022 | ||
2023 | /* Fork the child. */ | |
2024 | if ((pid = fork()) == 0) { | |
2025 | pid = getpid(); | |
2026 | ||
2027 | /* Child. Reinitialize the log because the pid has | |
2028 | changed. */ | |
2029 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
2030 | ||
2031 | /* Close the master side of the pseudo tty. */ | |
2032 | close(ptyfd); | |
2033 | ||
2034 | /* Make the pseudo tty our controlling tty. */ | |
2035 | pty_make_controlling_tty(&ttyfd, ttyname); | |
2036 | ||
2037 | /* Redirect stdin from the pseudo tty. */ | |
2038 | if (dup2(ttyfd, fileno(stdin)) < 0) | |
2039 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2040 | ||
2041 | /* Redirect stdout to the pseudo tty. */ | |
2042 | if (dup2(ttyfd, fileno(stdout)) < 0) | |
2043 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2044 | ||
2045 | /* Redirect stderr to the pseudo tty. */ | |
2046 | if (dup2(ttyfd, fileno(stderr)) < 0) | |
2047 | error("dup2 stdin failed: %.100s", strerror(errno)); | |
2048 | ||
2049 | /* Close the extra descriptor for the pseudo tty. */ | |
2050 | close(ttyfd); | |
2051 | ||
2052 | /* Get IP address of client. This is needed because we | |
2053 | want to record where the user logged in from. If the | |
2054 | connection is not a socket, let the ip address be 0.0.0.0. */ | |
2055 | memset(&from, 0, sizeof(from)); | |
2056 | if (packet_get_connection_in() == packet_get_connection_out()) { | |
2057 | fromlen = sizeof(from); | |
2058 | if (getpeername(packet_get_connection_in(), | |
2059 | (struct sockaddr *) & from, &fromlen) < 0) { | |
2060 | debug("getpeername: %.100s", strerror(errno)); | |
2061 | fatal_cleanup(); | |
2062 | } | |
2063 | } | |
2064 | /* Record that there was a login on that terminal. */ | |
2065 | record_login(pid, ttyname, pw->pw_name, pw->pw_uid, hostname, | |
2066 | &from); | |
8efc0c15 | 2067 | |
5260325f | 2068 | /* Check if .hushlogin exists. */ |
2069 | snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir); | |
2070 | quiet_login = stat(line, &st) >= 0; | |
e1a9c08d | 2071 | |
2072 | #ifdef HAVE_LIBPAM | |
5260325f | 2073 | /* output the results of the pamconv() */ |
2074 | if (!quiet_login && pamconv_msg != NULL) | |
2075 | fprintf(stderr, pamconv_msg); | |
e1a9c08d | 2076 | #endif |
8efc0c15 | 2077 | |
5260325f | 2078 | /* If the user has logged in before, display the time of |
2079 | last login. However, don't display anything extra if a | |
2080 | command has been specified (so that ssh can be used to | |
2081 | execute commands on a remote machine without users | |
2082 | knowing they are going to another machine). Login(1) | |
2083 | will do this for us as well, so check if login(1) is used */ | |
2084 | if (command == NULL && last_login_time != 0 && !quiet_login && | |
2085 | !options.use_login) { | |
2086 | /* Convert the date to a string. */ | |
2087 | time_string = ctime(&last_login_time); | |
2088 | /* Remove the trailing newline. */ | |
2089 | if (strchr(time_string, '\n')) | |
2090 | *strchr(time_string, '\n') = 0; | |
2091 | /* Display the last login time. Host if displayed | |
2092 | if known. */ | |
2093 | if (strcmp(buf, "") == 0) | |
2094 | printf("Last login: %s\r\n", time_string); | |
2095 | else | |
2096 | printf("Last login: %s from %s\r\n", time_string, buf); | |
2097 | } | |
2098 | /* Print /etc/motd unless a command was specified or | |
2099 | printing it was disabled in server options or login(1) | |
2100 | will be used. Note that some machines appear to print | |
2101 | it in /etc/profile or similar. */ | |
2102 | if (command == NULL && options.print_motd && !quiet_login && | |
2103 | !options.use_login) { | |
2104 | /* Print /etc/motd if it exists. */ | |
2105 | f = fopen("/etc/motd", "r"); | |
2106 | if (f) { | |
2107 | while (fgets(line, sizeof(line), f)) | |
2108 | fputs(line, stdout); | |
2109 | fclose(f); | |
2110 | } | |
2111 | } | |
2112 | /* Do common processing for the child, such as execing the command. */ | |
2113 | do_child(command, pw, term, display, auth_proto, auth_data, ttyname); | |
2114 | /* NOTREACHED */ | |
8efc0c15 | 2115 | } |
5260325f | 2116 | if (pid < 0) |
2117 | packet_disconnect("fork failed: %.100s", strerror(errno)); | |
2118 | /* Parent. Close the slave side of the pseudo tty. */ | |
2119 | close(ttyfd); | |
2120 | ||
2121 | /* Create another descriptor of the pty master side for use as the | |
2122 | standard input. We could use the original descriptor, but this | |
2123 | simplifies code in server_loop. The descriptor is bidirectional. */ | |
2124 | fdout = dup(ptyfd); | |
2125 | if (fdout < 0) | |
2126 | packet_disconnect("dup failed: %.100s", strerror(errno)); | |
2127 | ||
2128 | /* Add a cleanup function to clear the utmp entry and record logout | |
2129 | time in case we call fatal() (e.g., the connection gets closed). */ | |
2130 | cleanup_context.pid = pid; | |
2131 | cleanup_context.ttyname = ttyname; | |
2132 | fatal_add_cleanup(pty_cleanup_proc, (void *) &cleanup_context); | |
2133 | ||
2134 | /* Enter interactive session. */ | |
2135 | server_loop(pid, ptyfd, fdout, -1); | |
2136 | /* server_loop has not closed ptyfd and fdout. */ | |
2137 | ||
2138 | /* Cancel the cleanup function. */ | |
2139 | fatal_remove_cleanup(pty_cleanup_proc, (void *) &cleanup_context); | |
2140 | ||
2141 | /* Record that the user has logged out. */ | |
2142 | record_logout(pid, ttyname); | |
2143 | ||
2144 | /* Release the pseudo-tty. */ | |
2145 | pty_release(ttyname); | |
2146 | ||
2147 | /* Close the server side of the socket pairs. We must do this | |
2148 | after the pty cleanup, so that another process doesn't get this | |
2149 | pty while we're still cleaning up. */ | |
2150 | close(ptyfd); | |
2151 | close(fdout); | |
8efc0c15 | 2152 | } |
2153 | ||
5260325f | 2154 | /* |
2155 | * Sets the value of the given variable in the environment. If the variable | |
2156 | * already exists, its value is overriden. | |
2157 | */ | |
2158 | void | |
2159 | child_set_env(char ***envp, unsigned int *envsizep, const char *name, | |
2160 | const char *value) | |
8efc0c15 | 2161 | { |
5260325f | 2162 | unsigned int i, namelen; |
2163 | char **env; | |
2164 | ||
2165 | /* Find the slot where the value should be stored. If the | |
2166 | variable already exists, we reuse the slot; otherwise we append | |
2167 | a new slot at the end of the array, expanding if necessary. */ | |
2168 | env = *envp; | |
2169 | namelen = strlen(name); | |
2170 | for (i = 0; env[i]; i++) | |
2171 | if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') | |
2172 | break; | |
2173 | if (env[i]) { | |
2174 | /* Name already exists. Reuse the slot. */ | |
2175 | xfree(env[i]); | |
2176 | } else { | |
2177 | /* New variable. Expand the array if necessary. */ | |
2178 | if (i >= (*envsizep) - 1) { | |
2179 | (*envsizep) += 50; | |
2180 | env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); | |
2181 | } | |
2182 | /* Need to set the NULL pointer at end of array beyond the new slot. */ | |
2183 | env[i + 1] = NULL; | |
8efc0c15 | 2184 | } |
2185 | ||
5260325f | 2186 | /* Allocate space and format the variable in the appropriate slot. */ |
2187 | env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); | |
2188 | snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); | |
8efc0c15 | 2189 | } |
2190 | ||
5260325f | 2191 | /* |
2192 | * Reads environment variables from the given file and adds/overrides them | |
2193 | * into the environment. If the file does not exist, this does nothing. | |
2194 | * Otherwise, it must consist of empty lines, comments (line starts with '#') | |
2195 | * and assignments of the form name=value. No other forms are allowed. | |
2196 | */ | |
2197 | void | |
2198 | read_environment_file(char ***env, unsigned int *envsize, | |
2199 | const char *filename) | |
8efc0c15 | 2200 | { |
5260325f | 2201 | FILE *f; |
2202 | char buf[4096]; | |
2203 | char *cp, *value; | |
2204 | ||
2205 | /* Open the environment file. */ | |
2206 | f = fopen(filename, "r"); | |
2207 | if (!f) | |
2208 | return; | |
2209 | ||
2210 | /* Process each line. */ | |
2211 | while (fgets(buf, sizeof(buf), f)) { | |
2212 | /* Skip leading whitespace. */ | |
2213 | for (cp = buf; *cp == ' ' || *cp == '\t'; cp++); | |
2214 | ||
2215 | /* Ignore empty and comment lines. */ | |
2216 | if (!*cp || *cp == '#' || *cp == '\n') | |
2217 | continue; | |
2218 | ||
2219 | /* Remove newline. */ | |
2220 | if (strchr(cp, '\n')) | |
2221 | *strchr(cp, '\n') = '\0'; | |
2222 | ||
2223 | /* Find the equals sign. Its lack indicates badly | |
2224 | formatted line. */ | |
2225 | value = strchr(cp, '='); | |
2226 | if (value == NULL) { | |
2227 | fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf); | |
2228 | continue; | |
2229 | } | |
2230 | /* Replace the equals sign by nul, and advance value to | |
2231 | the value string. */ | |
2232 | *value = '\0'; | |
2233 | value++; | |
8efc0c15 | 2234 | |
5260325f | 2235 | /* Set the value in environment. */ |
2236 | child_set_env(env, envsize, cp, value); | |
2237 | } | |
8efc0c15 | 2238 | |
5260325f | 2239 | fclose(f); |
8efc0c15 | 2240 | } |
2241 | ||
5260325f | 2242 | /* |
2243 | * Performs common processing for the child, such as setting up the | |
2244 | * environment, closing extra file descriptors, setting the user and group | |
2245 | * ids, and executing the command or shell. | |
2246 | */ | |
2247 | void | |
2248 | do_child(const char *command, struct passwd * pw, const char *term, | |
2249 | const char *display, const char *auth_proto, | |
2250 | const char *auth_data, const char *ttyname) | |
8efc0c15 | 2251 | { |
5260325f | 2252 | const char *shell, *cp = NULL; |
2253 | char buf[256]; | |
2254 | FILE *f; | |
2255 | unsigned int envsize, i; | |
2256 | char **env; | |
2257 | extern char **environ; | |
2258 | struct stat st; | |
2259 | char *argv[10]; | |
8efc0c15 | 2260 | |
e1a9c08d | 2261 | #ifndef HAVE_LIBPAM /* pam_nologin handles this */ |
5260325f | 2262 | /* Check /etc/nologin. */ |
2263 | f = fopen("/etc/nologin", "r"); | |
2264 | if (f) { | |
2265 | /* /etc/nologin exists. Print its contents and exit. */ | |
2266 | while (fgets(buf, sizeof(buf), f)) | |
2267 | fputs(buf, stderr); | |
2268 | fclose(f); | |
2269 | if (pw->pw_uid != 0) | |
2270 | exit(254); | |
2271 | } | |
e35c1dc2 | 2272 | #endif /* HAVE_LIBPAM */ |
2273 | ||
2274 | #ifdef HAVE_SETLOGIN | |
5260325f | 2275 | /* Set login name in the kernel. */ |
2276 | if (setlogin(pw->pw_name) < 0) | |
2277 | error("setlogin failed: %s", strerror(errno)); | |
e35c1dc2 | 2278 | #endif /* HAVE_SETLOGIN */ |
8efc0c15 | 2279 | |
5260325f | 2280 | /* Set uid, gid, and groups. */ |
2281 | /* Login(1) does this as well, and it needs uid 0 for the "-h" | |
2282 | switch, so we let login(1) to this for us. */ | |
2283 | if (!options.use_login) { | |
2284 | if (getuid() == 0 || geteuid() == 0) { | |
2285 | if (setgid(pw->pw_gid) < 0) { | |
2286 | perror("setgid"); | |
2287 | exit(1); | |
2288 | } | |
2289 | /* Initialize the group list. */ | |
2290 | if (initgroups(pw->pw_name, pw->pw_gid) < 0) { | |
2291 | perror("initgroups"); | |
2292 | exit(1); | |
2293 | } | |
2294 | endgrent(); | |
2295 | ||
2296 | /* Permanently switch to the desired uid. */ | |
2297 | permanently_set_uid(pw->pw_uid); | |
2298 | } | |
2299 | if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) | |
2300 | fatal("Failed to set uids to %d.", (int) pw->pw_uid); | |
2301 | } | |
2302 | /* Get the shell from the password data. An empty shell field is | |
2303 | legal, and means /bin/sh. */ | |
2304 | shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; | |
8efc0c15 | 2305 | |
2306 | #ifdef AFS | |
5260325f | 2307 | /* Try to get AFS tokens for the local cell. */ |
2308 | if (k_hasafs()) { | |
2309 | char cell[64]; | |
2310 | ||
2311 | if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) | |
2312 | krb_afslog(cell, 0); | |
2313 | ||
2314 | krb_afslog(0, 0); | |
2315 | } | |
8efc0c15 | 2316 | #endif /* AFS */ |
5260325f | 2317 | |
2318 | /* Initialize the environment. In the first part we allocate | |
2319 | space for all environment variables. */ | |
2320 | envsize = 100; | |
2321 | env = xmalloc(envsize * sizeof(char *)); | |
2322 | env[0] = NULL; | |
2323 | ||
2324 | if (!options.use_login) { | |
2325 | /* Set basic environment. */ | |
2326 | child_set_env(&env, &envsize, "USER", pw->pw_name); | |
2327 | child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); | |
2328 | child_set_env(&env, &envsize, "HOME", pw->pw_dir); | |
2329 | child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); | |
2330 | ||
2331 | snprintf(buf, sizeof buf, "%.200s/%.50s", | |
2332 | _PATH_MAILDIR, pw->pw_name); | |
2333 | child_set_env(&env, &envsize, "MAIL", buf); | |
2334 | ||
2335 | /* Normal systems set SHELL by default. */ | |
2336 | child_set_env(&env, &envsize, "SHELL", shell); | |
2337 | } | |
2338 | /* Let it inherit timezone if we have one. */ | |
2339 | if (getenv("TZ")) | |
2340 | child_set_env(&env, &envsize, "TZ", getenv("TZ")); | |
2341 | ||
2342 | /* Set custom environment options from RSA authentication. */ | |
2343 | while (custom_environment) { | |
2344 | struct envstring *ce = custom_environment; | |
2345 | char *s = ce->s; | |
2346 | int i; | |
2347 | for (i = 0; s[i] != '=' && s[i]; i++); | |
2348 | if (s[i] == '=') { | |
2349 | s[i] = 0; | |
2350 | child_set_env(&env, &envsize, s, s + i + 1); | |
2351 | } | |
2352 | custom_environment = ce->next; | |
2353 | xfree(ce->s); | |
2354 | xfree(ce); | |
8efc0c15 | 2355 | } |
8efc0c15 | 2356 | |
5260325f | 2357 | /* Set SSH_CLIENT. */ |
2358 | snprintf(buf, sizeof buf, "%.50s %d %d", | |
2359 | get_remote_ipaddr(), get_remote_port(), options.port); | |
2360 | child_set_env(&env, &envsize, "SSH_CLIENT", buf); | |
8efc0c15 | 2361 | |
5260325f | 2362 | /* Set SSH_TTY if we have a pty. */ |
2363 | if (ttyname) | |
2364 | child_set_env(&env, &envsize, "SSH_TTY", ttyname); | |
8efc0c15 | 2365 | |
5260325f | 2366 | /* Set TERM if we have a pty. */ |
2367 | if (term) | |
2368 | child_set_env(&env, &envsize, "TERM", term); | |
8efc0c15 | 2369 | |
5260325f | 2370 | /* Set DISPLAY if we have one. */ |
2371 | if (display) | |
2372 | child_set_env(&env, &envsize, "DISPLAY", display); | |
8efc0c15 | 2373 | |
2374 | #ifdef KRB4 | |
5260325f | 2375 | { |
2376 | extern char *ticket; | |
2377 | ||
2378 | if (ticket) | |
2379 | child_set_env(&env, &envsize, "KRBTKFILE", ticket); | |
2380 | } | |
8efc0c15 | 2381 | #endif /* KRB4 */ |
2382 | ||
bb0dd7f6 | 2383 | #ifdef HAVE_LIBPAM |
5260325f | 2384 | /* Pull in any environment variables that may have been set by PAM. */ |
2385 | { | |
2386 | char *equals, var_name[512], var_val[512]; | |
2387 | char **pam_env = pam_getenvlist((pam_handle_t *)pamh); | |
2388 | int i; | |
2389 | for(i = 0; pam_env && pam_env[i]; i++) { | |
2390 | equals = strstr(pam_env[i], "="); | |
2391 | if ((strlen(pam_env[i]) < (sizeof(var_name) - 1)) && (equals != NULL)) | |
2392 | { | |
2393 | memset(var_name, '\0', sizeof(var_name)); | |
2394 | memset(var_val, '\0', sizeof(var_val)); | |
2395 | strncpy(var_name, pam_env[i], equals - pam_env[i]); | |
2396 | strcpy(var_val, equals + 1); | |
2397 | child_set_env(&env, &envsize, var_name, var_val); | |
2398 | } | |
2399 | } | |
2400 | } | |
bb0dd7f6 | 2401 | #endif /* HAVE_LIBPAM */ |
2402 | ||
5260325f | 2403 | /* Set XAUTHORITY to always be a local file. */ |
2404 | if (xauthfile) | |
2405 | child_set_env(&env, &envsize, "XAUTHORITY", xauthfile); | |
2406 | ||
2407 | /* Set variable for forwarded authentication connection, if we | |
2408 | have one. */ | |
2409 | if (auth_get_socket_name() != NULL) | |
2410 | child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, | |
2411 | auth_get_socket_name()); | |
2412 | ||
2413 | /* Read $HOME/.ssh/environment. */ | |
2414 | if (!options.use_login) { | |
2415 | snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir); | |
2416 | read_environment_file(&env, &envsize, buf); | |
2417 | } | |
2418 | /* If debugging, dump the environment to stderr. */ | |
2419 | if (debug_flag) { | |
2420 | fprintf(stderr, "Environment:\n"); | |
2421 | for (i = 0; env[i]; i++) | |
2422 | fprintf(stderr, " %.200s\n", env[i]); | |
2423 | } | |
2424 | /* Close the connection descriptors; note that this is the child, | |
2425 | and the server will still have the socket open, and it is | |
2426 | important that we do not shutdown it. Note that the | |
2427 | descriptors cannot be closed before building the environment, | |
2428 | as we call get_remote_ipaddr there. */ | |
2429 | if (packet_get_connection_in() == packet_get_connection_out()) | |
2430 | close(packet_get_connection_in()); | |
2431 | else { | |
2432 | close(packet_get_connection_in()); | |
2433 | close(packet_get_connection_out()); | |
2434 | } | |
2435 | /* Close all descriptors related to channels. They will still | |
2436 | remain open in the parent. */ | |
2437 | channel_close_all(); | |
2438 | ||
2439 | /* Close any extra file descriptors. Note that there may still be | |
2440 | descriptors left by system functions. They will be closed | |
2441 | later. */ | |
2442 | endpwent(); | |
2443 | endhostent(); | |
2444 | ||
2445 | /* Close any extra open file descriptors so that we don\'t have | |
2446 | them hanging around in clients. Note that we want to do this | |
2447 | after initgroups, because at least on Solaris 2.3 it leaves | |
2448 | file descriptors open. */ | |
2449 | for (i = 3; i < 64; i++) | |
2450 | close(i); | |
2451 | ||
2452 | /* Change current directory to the user\'s home directory. */ | |
2453 | if (chdir(pw->pw_dir) < 0) | |
2454 | fprintf(stderr, "Could not chdir to home directory %s: %s\n", | |
2455 | pw->pw_dir, strerror(errno)); | |
2456 | ||
2457 | /* Must take new environment into use so that .ssh/rc, /etc/sshrc | |
2458 | and xauth are run in the proper environment. */ | |
2459 | environ = env; | |
2460 | ||
2461 | /* Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found | |
2462 | first in this order). */ | |
2463 | if (!options.use_login) { | |
2464 | if (stat(SSH_USER_RC, &st) >= 0) { | |
2465 | if (debug_flag) | |
2466 | fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC); | |
2467 | ||
2468 | f = popen("/bin/sh " SSH_USER_RC, "w"); | |
2469 | if (f) { | |
2470 | if (auth_proto != NULL && auth_data != NULL) | |
2471 | fprintf(f, "%s %s\n", auth_proto, auth_data); | |
2472 | pclose(f); | |
2473 | } else | |
2474 | fprintf(stderr, "Could not run %s\n", SSH_USER_RC); | |
2475 | } else if (stat(SSH_SYSTEM_RC, &st) >= 0) { | |
2476 | if (debug_flag) | |
2477 | fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC); | |
2478 | ||
2479 | f = popen("/bin/sh " SSH_SYSTEM_RC, "w"); | |
2480 | if (f) { | |
2481 | if (auth_proto != NULL && auth_data != NULL) | |
2482 | fprintf(f, "%s %s\n", auth_proto, auth_data); | |
2483 | pclose(f); | |
2484 | } else | |
2485 | fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC); | |
2486 | } | |
8efc0c15 | 2487 | #ifdef XAUTH_PATH |
5260325f | 2488 | else { |
2489 | /* Add authority data to .Xauthority if | |
2490 | appropriate. */ | |
2491 | if (auth_proto != NULL && auth_data != NULL) { | |
2492 | if (debug_flag) | |
2493 | fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n", | |
2494 | XAUTH_PATH, display, auth_proto, auth_data); | |
2495 | ||
2496 | f = popen(XAUTH_PATH " -q -", "w"); | |
2497 | if (f) { | |
2498 | fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data); | |
2499 | fclose(f); | |
2500 | } else | |
2501 | fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH); | |
2502 | } | |
2503 | } | |
8efc0c15 | 2504 | #endif /* XAUTH_PATH */ |
2505 | ||
5260325f | 2506 | /* Get the last component of the shell name. */ |
2507 | cp = strrchr(shell, '/'); | |
2508 | if (cp) | |
2509 | cp++; | |
2510 | else | |
2511 | cp = shell; | |
2512 | } | |
2513 | /* If we have no command, execute the shell. In this case, the | |
2514 | shell name to be passed in argv[0] is preceded by '-' to | |
2515 | indicate that this is a login shell. */ | |
2516 | if (!command) { | |
2517 | if (!options.use_login) { | |
2518 | char buf[256]; | |
2519 | ||
2520 | /* Check for mail if we have a tty and it was | |
2521 | enabled in server options. */ | |
2522 | if (ttyname && options.check_mail) { | |
2523 | char *mailbox; | |
2524 | struct stat mailstat; | |
2525 | mailbox = getenv("MAIL"); | |
2526 | if (mailbox != NULL) { | |
2527 | if (stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0) | |
2528 | printf("No mail.\n"); | |
2529 | else if (mailstat.st_mtime < mailstat.st_atime) | |
2530 | printf("You have mail.\n"); | |
2531 | else | |
2532 | printf("You have new mail.\n"); | |
2533 | } | |
2534 | } | |
2535 | /* Start the shell. Set initial character to '-'. */ | |
2536 | buf[0] = '-'; | |
2537 | strncpy(buf + 1, cp, sizeof(buf) - 1); | |
2538 | buf[sizeof(buf) - 1] = 0; | |
2539 | ||
2540 | /* Execute the shell. */ | |
2541 | argv[0] = buf; | |
2542 | argv[1] = NULL; | |
2543 | execve(shell, argv, env); | |
2544 | ||
2545 | /* Executing the shell failed. */ | |
2546 | perror(shell); | |
2547 | exit(1); | |
2548 | ||
2549 | } else { | |
2550 | /* Launch login(1). */ | |
2551 | ||
2552 | execl(LOGIN_PROGRAM, "login", "-h", get_remote_ipaddr(), | |
2553 | "-p", "-f", "--", pw->pw_name, NULL); | |
2554 | ||
2555 | /* Login couldn't be executed, die. */ | |
2556 | ||
2557 | perror("login"); | |
2558 | exit(1); | |
2559 | } | |
2560 | } | |
2561 | /* Execute the command using the user's shell. This uses the -c | |
2562 | option to execute the command. */ | |
2563 | argv[0] = (char *) cp; | |
2564 | argv[1] = "-c"; | |
2565 | argv[2] = (char *) command; | |
2566 | argv[3] = NULL; | |
2567 | execve(shell, argv, env); | |
2568 | perror(shell); | |
2569 | exit(1); | |
8efc0c15 | 2570 | } |