1 /* $OpenBSD: monitor.c,v 1.256 2026/05/31 11:30:50 djm Exp $ */
2 /*
3 * Copyright 2002 Niels Provos <provos@citi.umich.edu>
4 * Copyright 2002 Markus Friedl <markus@openbsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include "includes.h"
29
30 #include <sys/types.h>
31 #include <sys/wait.h>
32 #include <sys/socket.h>
33 #include <sys/tree.h>
34 #include <sys/queue.h>
35
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <limits.h>
39 #include <paths.h>
40 #include <poll.h>
41 #include <pwd.h>
42 #include <signal.h>
43 #include <stdarg.h>
44 #include <stdint.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <string.h>
48 #include <unistd.h>
49
50 #ifdef WITH_OPENSSL
51 #include <openssl/dh.h>
52 #endif
53
54 #include "openbsd-compat/openssl-compat.h"
55
56 #include "atomicio.h"
57 #include "xmalloc.h"
58 #include "ssh.h"
59 #include "sshkey.h"
60 #include "sshbuf.h"
61 #include "hostfile.h"
62 #include "auth.h"
63 #include "cipher.h"
64 #include "kex.h"
65 #include "dh.h"
66 #include "auth-pam.h"
67 #include "packet.h"
68 #include "auth-options.h"
69 #include "sshpty.h"
70 #include "channels.h"
71 #include "session.h"
72 #include "sshlogin.h"
73 #include "canohost.h"
74 #include "log.h"
75 #include "misc.h"
76 #include "servconf.h"
77 #include "monitor.h"
78 #include "blocklist_client.h"
79
80 #ifdef GSSAPI
81 #include "ssh-gss.h"
82 #endif
83 #include "monitor_wrap.h"
84 #include "monitor_fdpass.h"
85 #include "compat.h"
86 #include "ssh2.h"
87 #include "authfd.h"
88 #include "match.h"
89 #include "ssherr.h"
90 #include "sk-api.h"
91 #include "srclimit.h"
92
93 #ifdef GSSAPI
94 static Gssctxt *gsscontext = NULL;
95 #endif
96
97 /* Imports */
98 extern ServerOptions options;
99 extern u_int utmp_len;
100 extern struct sshbuf *cfg;
101 extern struct sshbuf *loginmsg;
102 extern struct include_list includes;
103 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */
104
105 /* State exported from the child */
106 static struct sshbuf *child_state;
107
108 /* Functions on the monitor that answer unprivileged requests */
109
110 int mm_answer_moduli(struct ssh *, int, struct sshbuf *);
111 int mm_answer_setcompat(struct ssh *, int, struct sshbuf *);
112 int mm_answer_sign(struct ssh *, int, struct sshbuf *);
113 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *);
114 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *);
115 int mm_answer_authserv(struct ssh *, int, struct sshbuf *);
116 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *);
117 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *);
118 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *);
119 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *);
120 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *);
121 int mm_answer_pty(struct ssh *, int, struct sshbuf *);
122 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *);
123 int mm_answer_term(struct ssh *, int, struct sshbuf *);
124 int mm_answer_state(struct ssh *, int, struct sshbuf *);
125
126 #ifdef USE_PAM
127 int mm_answer_pam_start(struct ssh *, int, struct sshbuf *);
128 int mm_answer_pam_account(struct ssh *, int, struct sshbuf *);
129 int mm_answer_pam_init_ctx(struct ssh *, int, struct sshbuf *);
130 int mm_answer_pam_query(struct ssh *, int, struct sshbuf *);
131 int mm_answer_pam_respond(struct ssh *, int, struct sshbuf *);
132 int mm_answer_pam_free_ctx(struct ssh *, int, struct sshbuf *);
133 #endif
134
135 #ifdef GSSAPI
136 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *);
137 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *);
138 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *);
139 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *);
140 #endif
141
142 #ifdef SSH_AUDIT_EVENTS
143 int mm_answer_audit_event(struct ssh *, int, struct sshbuf *);
144 int mm_answer_audit_command(struct ssh *, int, struct sshbuf *);
145 #endif
146
147 static Authctxt *authctxt;
148
149 /* local state for key verify */
150 static u_char *key_blob = NULL;
151 static size_t key_bloblen = 0;
152 static u_int key_blobtype = MM_NOKEY;
153 static struct sshauthopt *key_opts = NULL;
154 static char *hostbased_cuser = NULL;
155 static char *hostbased_chost = NULL;
156 static char *auth_method = "unknown";
157 static char *auth_submethod = NULL;
158 static u_int session_id2_len = 0;
159 static u_char *session_id2 = NULL;
160 static pid_t monitor_child_pid;
161 static int auth_attempted = 0;
162 static int invalid_user = 0;
163 static int compat_set = 0;
164
165 struct mon_table {
166 enum monitor_reqtype type;
167 int flags;
168 int (*f)(struct ssh *, int, struct sshbuf *);
169 };
170
171 #define MON_ISAUTH 0x0004 /* Required for Authentication */
172 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */
173 #define MON_ONCE 0x0010 /* Disable after calling */
174 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */
175
176 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE)
177
178 #define MON_PERMIT 0x1000 /* Request is permitted */
179
180 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *,
181 struct mon_table **);
182 static int monitor_read_log(struct monitor *);
183
184 struct mon_table mon_dispatch_proto20[] = {
185 {MONITOR_REQ_STATE, MON_ONCE, mm_answer_state},
186 #ifdef WITH_OPENSSL
187 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
188 #endif
189 {MONITOR_REQ_SETCOMPAT, MON_ONCE, mm_answer_setcompat},
190 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign},
191 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
192 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv},
193 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner},
194 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
195 #ifdef USE_PAM
196 {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start},
197 {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account},
198 {MONITOR_REQ_PAM_INIT_CTX, MON_ONCE, mm_answer_pam_init_ctx},
199 {MONITOR_REQ_PAM_QUERY, 0, mm_answer_pam_query},
200 {MONITOR_REQ_PAM_RESPOND, MON_ONCE, mm_answer_pam_respond},
201 {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx},
202 #endif
203 #ifdef SSH_AUDIT_EVENTS
204 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
205 #endif
206 #ifdef BSD_AUTH
207 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
208 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond},
209 #endif
210 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
211 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify},
212 #ifdef GSSAPI
213 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
214 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
215 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok},
216 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic},
217 #endif
218 {0, 0, NULL}
219 };
220
221 struct mon_table mon_dispatch_postauth20[] = {
222 {MONITOR_REQ_STATE, MON_ONCE, mm_answer_state},
223 #ifdef WITH_OPENSSL
224 {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
225 #endif
226 {MONITOR_REQ_SIGN, 0, mm_answer_sign},
227 {MONITOR_REQ_PTY, 0, mm_answer_pty},
228 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup},
229 {MONITOR_REQ_TERM, 0, mm_answer_term},
230 #ifdef SSH_AUDIT_EVENTS
231 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
232 {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command},
233 #endif
234 {0, 0, NULL}
235 };
236
237 struct mon_table *mon_dispatch;
238
239 /* Specifies if a certain message is allowed at the moment */
240 static void
monitor_permit(struct mon_table * ent,enum monitor_reqtype type,int permit)241 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
242 {
243 while (ent->f != NULL) {
244 if (ent->type == type) {
245 ent->flags &= ~MON_PERMIT;
246 ent->flags |= permit ? MON_PERMIT : 0;
247 return;
248 }
249 ent++;
250 }
251 }
252
253 static void
monitor_permit_authentications(int permit)254 monitor_permit_authentications(int permit)
255 {
256 struct mon_table *ent = mon_dispatch;
257
258 while (ent->f != NULL) {
259 if (ent->flags & MON_AUTH) {
260 ent->flags &= ~MON_PERMIT;
261 ent->flags |= permit ? MON_PERMIT : 0;
262 }
263 ent++;
264 }
265 }
266
267 void
monitor_child_preauth(struct ssh * ssh,struct monitor * pmonitor)268 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
269 {
270 struct mon_table *ent;
271 int status, authenticated = 0, partial = 0;
272
273 debug3("preauth child monitor started");
274
275 if (pmonitor->m_recvfd >= 0)
276 close(pmonitor->m_recvfd);
277 if (pmonitor->m_log_sendfd >= 0)
278 close(pmonitor->m_log_sendfd);
279 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
280
281 authctxt = (Authctxt *)ssh->authctxt;
282 memset(authctxt, 0, sizeof(*authctxt));
283 ssh->authctxt = authctxt;
284
285 authctxt->loginmsg = loginmsg;
286
287 mon_dispatch = mon_dispatch_proto20;
288 /* Permit requests for state, moduli and signatures */
289 monitor_permit(mon_dispatch, MONITOR_REQ_STATE, 1);
290 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
291 monitor_permit(mon_dispatch, MONITOR_REQ_SETCOMPAT, 1);
292 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
293
294 /* The first few requests do not require asynchronous access */
295 while (!authenticated) {
296 partial = 0;
297 auth_method = "unknown";
298 auth_submethod = NULL;
299 auth2_authctxt_reset_info(authctxt);
300
301 authenticated = (monitor_read(ssh, pmonitor,
302 mon_dispatch, &ent) == 1);
303
304 /* Record that auth was attempted to set exit status later */
305 if ((ent->flags & MON_AUTH) != 0)
306 auth_attempted = 1;
307
308 /* Special handling for multiple required authentications */
309 if (options.num_auth_methods != 0) {
310 if (authenticated &&
311 !auth2_update_methods_lists(authctxt,
312 auth_method, auth_submethod)) {
313 debug3_f("method %s: partial", auth_method);
314 authenticated = 0;
315 partial = 1;
316 }
317 }
318
319 if (authenticated) {
320 if (!(ent->flags & MON_AUTHDECIDE))
321 fatal_f("unexpected authentication from %d",
322 ent->type);
323 if (authctxt->pw->pw_uid == 0 &&
324 !auth_root_allowed(ssh, auth_method))
325 authenticated = 0;
326 #ifdef USE_PAM
327 /* PAM needs to perform account checks after auth */
328 if (options.use_pam && authenticated) {
329 struct sshbuf *m;
330
331 if ((m = sshbuf_new()) == NULL)
332 fatal("%s: sshbuf_new failed",
333 __func__);
334 mm_request_receive_expect(pmonitor->m_sendfd,
335 MONITOR_REQ_PAM_ACCOUNT, m);
336 authenticated = mm_answer_pam_account(
337 ssh, pmonitor->m_sendfd, m);
338 sshbuf_free(m);
339 }
340 #endif
341 }
342 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
343 auth_log(ssh, authenticated, partial,
344 auth_method, auth_submethod);
345 if (!partial && !authenticated)
346 authctxt->failures++;
347 if (authenticated || partial) {
348 auth2_update_session_info(authctxt,
349 auth_method, auth_submethod);
350 }
351 }
352 if (authctxt->failures > options.max_authtries) {
353 BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_FAIL,
354 "Too many authentication attempts");
355 /* Shouldn't happen */
356 fatal_f("privsep child made too many authentication "
357 "attempts");
358 }
359 }
360
361 if (!authctxt->valid) {
362 BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_FAIL,
363 "Authenticated invalid user");
364 fatal_f("authenticated invalid user");
365 }
366 if (strcmp(auth_method, "unknown") == 0) {
367 BLOCKLIST_NOTIFY(ssh, BLOCKLIST_AUTH_FAIL,
368 "Authentication method name unknown");
369 fatal_f("authentication method name unknown");
370 }
371
372 debug_f("user %s authenticated by privileged process", authctxt->user);
373 auth_attempted = 0;
374 ssh->authctxt = NULL;
375 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
376
377 mm_get_keystate(ssh, pmonitor);
378
379 /* Drain any buffered messages from the child */
380 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
381 ;
382
383 /* Wait for the child's exit status */
384 while (waitpid(pmonitor->m_pid, &status, 0) == -1) {
385 if (errno == EINTR)
386 continue;
387 fatal_f("waitpid: %s", strerror(errno));
388 }
389 if (WIFEXITED(status)) {
390 if (WEXITSTATUS(status) != 0)
391 fatal_f("preauth child %ld exited with status %d",
392 (long)pmonitor->m_pid, WEXITSTATUS(status));
393 } else if (WIFSIGNALED(status)) {
394 fatal_f("preauth child %ld terminated by signal %d",
395 (long)pmonitor->m_pid, WTERMSIG(status));
396 }
397 debug3_f("preauth child %ld terminated successfully",
398 (long)pmonitor->m_pid);
399
400 if (pmonitor->m_recvfd >= 0)
401 close(pmonitor->m_recvfd);
402 if (pmonitor->m_log_sendfd >= 0)
403 close(pmonitor->m_log_sendfd);
404 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
405 pmonitor->m_pid = -1;
406 }
407
408 static void
monitor_set_child_handler(pid_t pid)409 monitor_set_child_handler(pid_t pid)
410 {
411 monitor_child_pid = pid;
412 }
413
414 static void
monitor_child_handler(int sig)415 monitor_child_handler(int sig)
416 {
417 kill(monitor_child_pid, sig);
418 }
419
420 void
monitor_child_postauth(struct ssh * ssh,struct monitor * pmonitor)421 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
422 {
423 close(pmonitor->m_recvfd);
424 pmonitor->m_recvfd = -1;
425
426 monitor_set_child_handler(pmonitor->m_pid);
427 ssh_signal(SIGHUP, &monitor_child_handler);
428 ssh_signal(SIGTERM, &monitor_child_handler);
429 ssh_signal(SIGINT, &monitor_child_handler);
430 #ifdef SIGXFSZ
431 ssh_signal(SIGXFSZ, SIG_IGN);
432 #endif
433
434 mon_dispatch = mon_dispatch_postauth20;
435
436 /* Permit requests for moduli and signatures */
437 monitor_permit(mon_dispatch, MONITOR_REQ_STATE, 1);
438 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
439 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
440 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
441
442 if (auth_opts->permit_pty_flag) {
443 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
444 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
445 }
446
447 for (;;)
448 monitor_read(ssh, pmonitor, mon_dispatch, NULL);
449 }
450
451 static int
monitor_read_log(struct monitor * pmonitor)452 monitor_read_log(struct monitor *pmonitor)
453 {
454 struct sshbuf *logmsg;
455 u_int len, level, forced;
456 char *msg;
457 u_char *p;
458 int r;
459
460 if ((logmsg = sshbuf_new()) == NULL)
461 fatal_f("sshbuf_new");
462
463 /* Read length */
464 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0)
465 fatal_fr(r, "reserve len");
466 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) {
467 if (errno == EPIPE) {
468 sshbuf_free(logmsg);
469 debug_f("child log fd closed");
470 close(pmonitor->m_log_recvfd);
471 pmonitor->m_log_recvfd = -1;
472 return -1;
473 }
474 fatal_f("log fd read: %s", strerror(errno));
475 }
476 if ((r = sshbuf_get_u32(logmsg, &len)) != 0)
477 fatal_fr(r, "parse len");
478 if (len <= 4 || len > 8192)
479 fatal_f("invalid log message length %u", len);
480
481 /* Read severity, message */
482 sshbuf_reset(logmsg);
483 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0)
484 fatal_fr(r, "reserve msg");
485 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len)
486 fatal_f("log fd read: %s", strerror(errno));
487 if ((r = sshbuf_get_u32(logmsg, &level)) != 0 ||
488 (r = sshbuf_get_u32(logmsg, &forced)) != 0 ||
489 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0)
490 fatal_fr(r, "parse");
491
492 /* Log it */
493 if (log_level_name(level) == NULL)
494 fatal_f("invalid log level %u (corrupted message?)", level);
495 sshlogdirect(level, forced, "%s [%s]", msg,
496 mon_dispatch == mon_dispatch_postauth20 ? "postauth" : "preauth");
497
498 sshbuf_free(logmsg);
499 free(msg);
500
501 return 0;
502 }
503
504 static int
monitor_read(struct ssh * ssh,struct monitor * pmonitor,struct mon_table * ent,struct mon_table ** pent)505 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent,
506 struct mon_table **pent)
507 {
508 struct sshbuf *m;
509 int r, ret;
510 u_char type;
511 struct pollfd pfd[2];
512
513 for (;;) {
514 memset(&pfd, 0, sizeof(pfd));
515 pfd[0].fd = pmonitor->m_sendfd;
516 pfd[0].events = POLLIN;
517 pfd[1].fd = pmonitor->m_log_recvfd;
518 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN;
519 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) {
520 if (errno == EINTR || errno == EAGAIN)
521 continue;
522 fatal_f("poll: %s", strerror(errno));
523 }
524 if (pfd[1].revents) {
525 /*
526 * Drain all log messages before processing next
527 * monitor request.
528 */
529 monitor_read_log(pmonitor);
530 continue;
531 }
532 if (pfd[0].revents)
533 break; /* Continues below */
534 }
535
536 if ((m = sshbuf_new()) == NULL)
537 fatal_f("sshbuf_new");
538
539 mm_request_receive(pmonitor->m_sendfd, m);
540 if ((r = sshbuf_get_u8(m, &type)) != 0)
541 fatal_fr(r, "parse type");
542
543 debug3_f("checking request %d", type);
544
545 while (ent->f != NULL) {
546 if (ent->type == type)
547 break;
548 ent++;
549 }
550
551 if (ent->f != NULL) {
552 if (!(ent->flags & MON_PERMIT))
553 fatal_f("unpermitted request %d", type);
554 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m);
555 sshbuf_free(m);
556
557 /* The child may use this request only once, disable it */
558 if (ent->flags & MON_ONCE) {
559 debug2_f("%d used once, disabling now", type);
560 ent->flags &= ~MON_PERMIT;
561 }
562
563 if (pent != NULL)
564 *pent = ent;
565
566 return ret;
567 }
568
569 fatal_f("unsupported request: %d", type);
570
571 /* NOTREACHED */
572 return (-1);
573 }
574
575 /* allowed key state */
576 static int
monitor_allowed_key(const u_char * blob,u_int bloblen)577 monitor_allowed_key(const u_char *blob, u_int bloblen)
578 {
579 /* make sure key is allowed */
580 if (key_blob == NULL || key_bloblen != bloblen ||
581 timingsafe_bcmp(key_blob, blob, key_bloblen))
582 return (0);
583 return (1);
584 }
585
586 static void
monitor_reset_key_state(void)587 monitor_reset_key_state(void)
588 {
589 /* reset state */
590 free(key_blob);
591 free(hostbased_cuser);
592 free(hostbased_chost);
593 sshauthopt_free(key_opts);
594 key_blob = NULL;
595 key_bloblen = 0;
596 key_blobtype = MM_NOKEY;
597 key_opts = NULL;
598 hostbased_cuser = NULL;
599 hostbased_chost = NULL;
600 }
601
602 int
mm_answer_state(struct ssh * ssh,int sock,struct sshbuf * unused)603 mm_answer_state(struct ssh *ssh, int sock, struct sshbuf *unused)
604 {
605 struct sshbuf *m = NULL, *config = NULL, *hostkeys = NULL;
606 struct sshbuf *opts = NULL, *confdata = NULL;
607 int postauth;
608 int r;
609
610 debug_f("config len %zu", sshbuf_len(cfg));
611
612 if ((m = sshbuf_new()) == NULL ||
613 (config = sshbuf_new()) == NULL ||
614 (opts = sshbuf_new()) == NULL ||
615 (confdata = sshbuf_new()) == NULL)
616 fatal_f("sshbuf_new failed");
617
618 hostkeys = pack_hostkeys();
619 if ((r = serialise_server_options(&options, &config)) != 0)
620 fatal_fr(r, "serialise_server_options");
621
622 /*
623 * Protocol from monitor to unpriv privsep process:
624 * string configuration_blob
625 * uint64 timing_secret XXX move delays to monitor and remove
626 * string host_keys[] {
627 * string public_key
628 * string certificate
629 * }
630 * string server_banner
631 * string client_banner
632 * string configuration_data (postauth)
633 * string keystate (postauth)
634 * string authenticated_user (postauth)
635 * string session_info (postauth)
636 * string authopts (postauth)
637 */
638 if ((r = sshbuf_put_stringb(m, config)) != 0 ||
639 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 ||
640 (r = sshbuf_put_stringb(m, hostkeys)) != 0 ||
641 (r = sshbuf_put_stringb(m, ssh->kex->server_version)) != 0 ||
642 (r = sshbuf_put_stringb(m, ssh->kex->client_version)) != 0)
643 fatal_fr(r, "compose config");
644
645 postauth = (authctxt && authctxt->pw && authctxt->authenticated);
646 if (postauth) {
647 /* XXX shouldn't be reachable */
648 fatal_f("internal error: called in postauth");
649 }
650
651 sshbuf_free(config);
652 sshbuf_free(opts);
653 sshbuf_free(confdata);
654 sshbuf_free(hostkeys);
655
656 mm_request_send(sock, MONITOR_ANS_STATE, m);
657 sshbuf_free(m);
658 debug3_f("done");
659
660 return (0);
661 }
662
663 #ifdef WITH_OPENSSL
664 int
mm_answer_moduli(struct ssh * ssh,int sock,struct sshbuf * m)665 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m)
666 {
667 DH *dh;
668 const BIGNUM *dh_p, *dh_g;
669 int r;
670 u_int min, want, max;
671
672 if ((r = sshbuf_get_u32(m, &min)) != 0 ||
673 (r = sshbuf_get_u32(m, &want)) != 0 ||
674 (r = sshbuf_get_u32(m, &max)) != 0)
675 fatal_fr(r, "parse");
676
677 debug3_f("got parameters: %d %d %d", min, want, max);
678 /* We need to check here, too, in case the child got corrupted */
679 if (max < min || want < min || max < want)
680 fatal_f("bad parameters: %d %d %d", min, want, max);
681
682 sshbuf_reset(m);
683
684 dh = choose_dh(min, want, max);
685 if (dh == NULL) {
686 if ((r = sshbuf_put_u8(m, 0)) != 0)
687 fatal_fr(r, "assemble empty");
688 } else {
689 /* Send first bignum */
690 DH_get0_pqg(dh, &dh_p, NULL, &dh_g);
691 if ((r = sshbuf_put_u8(m, 1)) != 0 ||
692 (r = sshbuf_put_bignum2(m, dh_p)) != 0 ||
693 (r = sshbuf_put_bignum2(m, dh_g)) != 0)
694 fatal_fr(r, "assemble");
695
696 DH_free(dh);
697 }
698 mm_request_send(sock, MONITOR_ANS_MODULI, m);
699 return (0);
700 }
701 #endif
702
703 int
mm_answer_setcompat(struct ssh * ssh,int sock,struct sshbuf * m)704 mm_answer_setcompat(struct ssh *ssh, int sock, struct sshbuf *m)
705 {
706 int r;
707
708 debug3_f("entering");
709
710 if ((r = sshbuf_get_u32(m, &ssh->compat)) != 0)
711 fatal_fr(r, "parse");
712 compat_set = 1;
713
714 return (0);
715 }
716
717 int
mm_answer_sign(struct ssh * ssh,int sock,struct sshbuf * m)718 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
719 {
720 extern int auth_sock; /* XXX move to state struct? */
721 struct sshkey *pubkey, *key;
722 struct sshbuf *sigbuf = NULL;
723 u_char *p = NULL, *signature = NULL;
724 char *alg = NULL;
725 size_t datlen, siglen;
726 int r, is_proof = 0, keyid;
727 u_int compat;
728 const char proof_req[] = "hostkeys-prove-00@openssh.com";
729
730 debug3_f("entering");
731
732 /* Make sure the unpriv process sent the compat bits already */
733 if (!compat_set)
734 fatal_f("state error: setcompat never called");
735
736 if ((r = sshkey_froms(m, &pubkey)) != 0 ||
737 (r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
738 (r = sshbuf_get_cstring(m, &alg, NULL)) != 0 ||
739 (r = sshbuf_get_u32(m, &compat)) != 0)
740 fatal_fr(r, "parse");
741
742 if ((keyid = get_hostkey_index(pubkey, 1, ssh)) == -1)
743 fatal_f("unknown hostkey");
744 debug_f("hostkey %s index %d", sshkey_ssh_name(pubkey), keyid);
745 sshkey_free(pubkey);
746
747 /*
748 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),
749 * SHA384 (48 bytes) and SHA512 (64 bytes).
750 *
751 * Otherwise, verify the signature request is for a hostkey
752 * proof.
753 *
754 * XXX perform similar check for KEX signature requests too?
755 * it's not trivial, since what is signed is the hash, rather
756 * than the full kex structure...
757 */
758 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) {
759 /*
760 * Construct expected hostkey proof and compare it to what
761 * the client sent us.
762 */
763 if (session_id2_len == 0) /* hostkeys is never first */
764 fatal_f("bad data length: %zu", datlen);
765 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL)
766 fatal_f("no hostkey for index %d", keyid);
767 if ((sigbuf = sshbuf_new()) == NULL)
768 fatal_f("sshbuf_new");
769 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 ||
770 (r = sshbuf_put_string(sigbuf, session_id2,
771 session_id2_len)) != 0 ||
772 (r = sshkey_puts(key, sigbuf)) != 0)
773 fatal_fr(r, "assemble private key proof");
774 if (datlen != sshbuf_len(sigbuf) ||
775 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0)
776 fatal_f("bad data length: %zu, hostkey proof len %zu",
777 datlen, sshbuf_len(sigbuf));
778 sshbuf_free(sigbuf);
779 is_proof = 1;
780 }
781
782 /* save session id, it will be passed on the first call */
783 if (session_id2_len == 0) {
784 session_id2_len = datlen;
785 session_id2 = xmalloc(session_id2_len);
786 memcpy(session_id2, p, session_id2_len);
787 }
788
789 if ((key = get_hostkey_by_index(keyid)) != NULL) {
790 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
791 options.sk_provider, NULL, compat)) != 0)
792 fatal_fr(r, "sign");
793 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
794 auth_sock > 0) {
795 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen,
796 p, datlen, alg, compat)) != 0)
797 fatal_fr(r, "agent sign");
798 } else
799 fatal_f("no hostkey from index %d", keyid);
800
801 debug3_f("%s %s signature len=%zu", alg,
802 is_proof ? "hostkey proof" : "KEX", siglen);
803
804 sshbuf_reset(m);
805 if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
806 fatal_fr(r, "assemble");
807
808 free(alg);
809 free(p);
810 free(signature);
811
812 mm_request_send(sock, MONITOR_ANS_SIGN, m);
813
814 /* Turn on permissions for getpwnam */
815 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
816
817 return (0);
818 }
819
820 #define PUTPW(b, id) \
821 do { \
822 if ((r = sshbuf_put_string(b, \
823 &pwent->id, sizeof(pwent->id))) != 0) \
824 fatal_fr(r, "assemble %s", #id); \
825 } while (0)
826
827 void
mm_encode_server_options(struct sshbuf * m)828 mm_encode_server_options(struct sshbuf *m)
829 {
830 int r;
831 struct sshbuf *config;
832
833 if ((config = sshbuf_new()) == NULL)
834 fatal_f("sshbuf_new failed");
835 if ((r = serialise_server_options(&options, &config)) != 0)
836 fatal_fr(r, "serialise_server_options");
837 if ((r = sshbuf_put_stringb(m, config)) != 0)
838 fatal_fr(r, "assemble options");
839 sshbuf_free(config);
840 }
841
842 /* Retrieves the password entry and also checks if the user is permitted */
843 int
mm_answer_pwnamallow(struct ssh * ssh,int sock,struct sshbuf * m)844 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m)
845 {
846 struct passwd *pwent;
847 int r, allowed = 0;
848
849 debug3_f("entering");
850
851 /* Make sure the unpriv process sent the compat bits already */
852 if (!compat_set)
853 fatal_f("state error: setcompat never called");
854
855 if (authctxt->attempt++ != 0)
856 fatal_f("multiple attempts for getpwnam");
857
858 if ((r = sshbuf_get_cstring(m, &authctxt->user, NULL)) != 0)
859 fatal_fr(r, "parse");
860
861 pwent = getpwnamallow(ssh, authctxt->user);
862
863 setproctitle("%s [priv]", pwent ? authctxt->user : "unknown");
864
865 sshbuf_reset(m);
866
867 if (pwent == NULL) {
868 invalid_user = 1;
869 if ((r = sshbuf_put_u8(m, 0)) != 0)
870 fatal_fr(r, "assemble fakepw");
871 authctxt->pw = fakepw();
872 goto out;
873 }
874
875 allowed = 1;
876 authctxt->pw = pwent;
877 authctxt->valid = 1;
878
879 /* XXX send fake class/dir/shell, etc. */
880 if ((r = sshbuf_put_u8(m, 1)) != 0)
881 fatal_fr(r, "assemble ok");
882 PUTPW(m, pw_uid);
883 PUTPW(m, pw_gid);
884 #ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
885 PUTPW(m, pw_change);
886 #endif
887 #ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
888 PUTPW(m, pw_expire);
889 #endif
890 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
891 (r = sshbuf_put_cstring(m, "*")) != 0 ||
892 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
893 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 ||
894 #endif
895 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
896 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 ||
897 #endif
898 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 ||
899 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0)
900 fatal_fr(r, "assemble pw");
901
902 out:
903 ssh_packet_set_log_preamble(ssh, "%suser %s",
904 authctxt->valid ? "authenticating" : "invalid ", authctxt->user);
905
906 if (options.refuse_connection) {
907 logit("administratively prohibited connection for "
908 "%s%s from %.128s port %d",
909 authctxt->valid ? "" : "invalid user ",
910 authctxt->user, ssh_remote_ipaddr(ssh),
911 ssh_remote_port(ssh));
912 cleanup_exit(EXIT_CONFIG_REFUSED);
913 }
914
915 /* Send active options to unpriv */
916 mm_encode_server_options(m);
917
918 /* Create valid auth method lists */
919 if (auth2_setup_methods_lists(authctxt) != 0) {
920 /*
921 * The monitor will continue long enough to let the child
922 * run to its packet_disconnect(), but it must not allow any
923 * authentication to succeed.
924 */
925 debug_f("no valid authentication method lists");
926 }
927
928 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed);
929 mm_request_send(sock, MONITOR_ANS_PWNAM, m);
930
931 /* Allow service/style information on the auth context */
932 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
933 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1);
934
935 #ifdef USE_PAM
936 if (options.use_pam)
937 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
938 #endif
939
940 return (0);
941 }
942
mm_answer_auth2_read_banner(struct ssh * ssh,int sock,struct sshbuf * m)943 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m)
944 {
945 char *banner;
946 int r;
947
948 sshbuf_reset(m);
949 banner = auth2_read_banner();
950 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0)
951 fatal_fr(r, "assemble");
952 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
953 free(banner);
954
955 return (0);
956 }
957
958 int
mm_answer_authserv(struct ssh * ssh,int sock,struct sshbuf * m)959 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m)
960 {
961 int r;
962
963 monitor_permit_authentications(1);
964
965 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 ||
966 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0)
967 fatal_fr(r, "parse");
968 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style);
969
970 if (strlen(authctxt->style) == 0) {
971 free(authctxt->style);
972 authctxt->style = NULL;
973 }
974
975 return (0);
976 }
977
978 /*
979 * Check that the key type appears in the supplied pattern list, ignoring
980 * mismatches in the signature algorithm. (Signature algorithm checks are
981 * performed in the unprivileged authentication code).
982 * Returns 1 on success, 0 otherwise.
983 */
984 static int
key_base_type_match(const char * method,const struct sshkey * key,const char * list)985 key_base_type_match(const char *method, const struct sshkey *key,
986 const char *list)
987 {
988 char *s, *l, *ol = xstrdup(list);
989 int found = 0;
990
991 l = ol;
992 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) {
993 if (sshkey_type_from_name(s) == key->type) {
994 found = 1;
995 break;
996 }
997 }
998 if (!found) {
999 error("%s key type %s is not in permitted list %s", method,
1000 sshkey_ssh_name(key), list);
1001 }
1002
1003 free(ol);
1004 return found;
1005 }
1006
1007 int
mm_answer_authpassword(struct ssh * ssh,int sock,struct sshbuf * m)1008 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m)
1009 {
1010 static int call_count;
1011 char *passwd;
1012 int r, authenticated;
1013 size_t plen;
1014
1015 if (!options.password_authentication)
1016 fatal_f("password authentication not enabled");
1017 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0)
1018 fatal_fr(r, "parse");
1019 /* Only authenticate if the context is valid */
1020 authenticated = options.password_authentication &&
1021 auth_password(ssh, passwd);
1022 freezero(passwd, plen);
1023
1024 sshbuf_reset(m);
1025 if ((r = sshbuf_put_u32(m, authenticated)) != 0)
1026 fatal_fr(r, "assemble");
1027 #ifdef USE_PAM
1028 if ((r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0)
1029 fatal_fr(r, "assemble PAM");
1030 #endif
1031
1032 debug3_f("sending result %d", authenticated);
1033 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m);
1034
1035 call_count++;
1036 if (plen == 0 && call_count == 1)
1037 auth_method = "none";
1038 else
1039 auth_method = "password";
1040
1041 /* Causes monitor loop to terminate if authenticated */
1042 return (authenticated);
1043 }
1044
1045 #ifdef BSD_AUTH
1046 int
mm_answer_bsdauthquery(struct ssh * ssh,int sock,struct sshbuf * m)1047 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m)
1048 {
1049 char *name, *infotxt;
1050 u_int numprompts, *echo_on, success;
1051 char **prompts;
1052 int r;
1053
1054 if (!options.kbd_interactive_authentication)
1055 fatal_f("kbd-int authentication not enabled");
1056 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
1057 &prompts, &echo_on) < 0 ? 0 : 1;
1058
1059 sshbuf_reset(m);
1060 if ((r = sshbuf_put_u32(m, success)) != 0)
1061 fatal_fr(r, "assemble");
1062 if (success) {
1063 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0)
1064 fatal_fr(r, "assemble prompt");
1065 }
1066
1067 debug3_f("sending challenge success: %u", success);
1068 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);
1069
1070 if (success) {
1071 free(name);
1072 free(infotxt);
1073 free(prompts);
1074 free(echo_on);
1075 }
1076
1077 return (0);
1078 }
1079
1080 int
mm_answer_bsdauthrespond(struct ssh * ssh,int sock,struct sshbuf * m)1081 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m)
1082 {
1083 char *response;
1084 int r, authok;
1085
1086 if (!options.kbd_interactive_authentication)
1087 fatal_f("kbd-int authentication not enabled");
1088 if (authctxt->as == NULL)
1089 fatal_f("no bsd auth session");
1090
1091 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0)
1092 fatal_fr(r, "parse");
1093 authok = options.kbd_interactive_authentication &&
1094 auth_userresponse(authctxt->as, response, 0);
1095 authctxt->as = NULL;
1096 debug3_f("<%s> = <%d>", response, authok);
1097 free(response);
1098
1099 sshbuf_reset(m);
1100 if ((r = sshbuf_put_u32(m, authok)) != 0)
1101 fatal_fr(r, "assemble");
1102
1103 debug3_f("sending authenticated: %d", authok);
1104 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
1105
1106 auth_method = "keyboard-interactive";
1107 auth_submethod = "bsdauth";
1108
1109 return (authok != 0);
1110 }
1111 #endif
1112
1113 #ifdef USE_PAM
1114 int
mm_answer_pam_start(struct ssh * ssh,int sock,struct sshbuf * m)1115 mm_answer_pam_start(struct ssh *ssh, int sock, struct sshbuf *m)
1116 {
1117 if (!options.use_pam)
1118 fatal_f("UsePAM not set, but ended up in %s anyway", __func__);
1119
1120 start_pam(ssh);
1121
1122 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
1123 if (options.kbd_interactive_authentication)
1124 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1125
1126 return (0);
1127 }
1128
1129 int
mm_answer_pam_account(struct ssh * ssh,int sock,struct sshbuf * m)1130 mm_answer_pam_account(struct ssh *ssh, int sock, struct sshbuf *m)
1131 {
1132 u_int ret;
1133 int r;
1134
1135 if (!options.use_pam)
1136 fatal_f("PAM not enabled");
1137
1138 ret = do_pam_account();
1139
1140 if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1141 (r = sshbuf_put_stringb(m, loginmsg)) != 0)
1142 fatal_fr(r, "buffer error");
1143 sshbuf_reset(loginmsg);
1144
1145 mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m);
1146
1147 return (ret);
1148 }
1149
1150 static void *sshpam_ctxt, *sshpam_authok;
1151 extern KbdintDevice sshpam_device;
1152
1153 int
mm_answer_pam_init_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1154 mm_answer_pam_init_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1155 {
1156 u_int ok = 0;
1157 int r;
1158
1159 debug3_f("entering");
1160 if (!options.kbd_interactive_authentication)
1161 fatal_f("kbd-int authentication not enabled");
1162 if (sshpam_ctxt != NULL)
1163 fatal_f("already called");
1164 sshpam_ctxt = (sshpam_device.init_ctx)(authctxt);
1165 sshpam_authok = NULL;
1166 sshbuf_reset(m);
1167 if (sshpam_ctxt != NULL) {
1168 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1);
1169 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1);
1170 ok = 1;
1171 }
1172 if ((r = sshbuf_put_u32(m, ok)) != 0)
1173 fatal_fr(r, "buffer error");
1174 mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m);
1175 return (0);
1176 }
1177
1178 int
mm_answer_pam_query(struct ssh * ssh,int sock,struct sshbuf * m)1179 mm_answer_pam_query(struct ssh *ssh, int sock, struct sshbuf *m)
1180 {
1181 char *name = NULL, *info = NULL, **prompts = NULL;
1182 u_int i, num = 0, *echo_on = 0;
1183 int r, ret;
1184
1185 debug3_f("entering");
1186 sshpam_authok = NULL;
1187 if (sshpam_ctxt == NULL)
1188 fatal_f("no context");
1189 ret = (sshpam_device.query)(sshpam_ctxt, &name, &info,
1190 &num, &prompts, &echo_on);
1191 if (ret == 0 && num == 0 && sshpam_priv_kbdint_authdone(sshpam_ctxt))
1192 sshpam_authok = sshpam_ctxt;
1193 if (num > 1 || name == NULL || info == NULL)
1194 fatal("sshpam_device.query failed");
1195 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1);
1196 sshbuf_reset(m);
1197 if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1198 (r = sshbuf_put_cstring(m, name)) != 0 ||
1199 (r = sshbuf_put_cstring(m, info)) != 0 ||
1200 (r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0 ||
1201 (r = sshbuf_put_u32(m, num)) != 0)
1202 fatal_fr(r, "buffer error");
1203 free(name);
1204 free(info);
1205 for (i = 0; i < num; ++i) {
1206 if ((r = sshbuf_put_cstring(m, prompts[i])) != 0 ||
1207 (r = sshbuf_put_u32(m, echo_on[i])) != 0)
1208 fatal_fr(r, "buffer error");
1209 free(prompts[i]);
1210 }
1211 free(prompts);
1212 free(echo_on);
1213 auth_method = "keyboard-interactive";
1214 auth_submethod = "pam";
1215 mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m);
1216 return (0);
1217 }
1218
1219 int
mm_answer_pam_respond(struct ssh * ssh,int sock,struct sshbuf * m)1220 mm_answer_pam_respond(struct ssh *ssh, int sock, struct sshbuf *m)
1221 {
1222 char **resp;
1223 u_int i, num;
1224 int r, ret;
1225
1226 debug3_f("entering");
1227 if (sshpam_ctxt == NULL)
1228 fatal_f("no context");
1229 sshpam_authok = NULL;
1230 if ((r = sshbuf_get_u32(m, &num)) != 0)
1231 fatal_fr(r, "buffer error");
1232 if (num > PAM_MAX_NUM_MSG) {
1233 fatal_f("Too many PAM messages, got %u, expected <= %u",
1234 num, (unsigned)PAM_MAX_NUM_MSG);
1235 }
1236 if (num > 0) {
1237 resp = xcalloc(num, sizeof(char *));
1238 for (i = 0; i < num; ++i) {
1239 if ((r = sshbuf_get_cstring(m, &(resp[i]), NULL)) != 0)
1240 fatal("%s: buffer error: %s",
1241 __func__, ssh_err(r));
1242 }
1243 ret = (sshpam_device.respond)(sshpam_ctxt, num, resp);
1244 for (i = 0; i < num; ++i)
1245 free(resp[i]);
1246 free(resp);
1247 } else {
1248 ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL);
1249 }
1250 sshbuf_reset(m);
1251 if ((r = sshbuf_put_u32(m, ret)) != 0)
1252 fatal_fr(r, "buffer error");
1253 mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m);
1254 auth_method = "keyboard-interactive";
1255 auth_submethod = "pam";
1256 if (ret == 0)
1257 sshpam_authok = sshpam_ctxt;
1258 return (0);
1259 }
1260
1261 int
mm_answer_pam_free_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1262 mm_answer_pam_free_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1263 {
1264 int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt;
1265
1266 debug3_f("entering");
1267 if (sshpam_ctxt == NULL)
1268 fatal_f("no context");
1269 (sshpam_device.free_ctx)(sshpam_ctxt);
1270 sshpam_ctxt = sshpam_authok = NULL;
1271 sshbuf_reset(m);
1272 mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m);
1273 /* Allow another attempt */
1274 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1275 auth_method = "keyboard-interactive";
1276 auth_submethod = "pam";
1277 return r;
1278 }
1279 #endif
1280
1281 int
mm_answer_keyallowed(struct ssh * ssh,int sock,struct sshbuf * m)1282 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m)
1283 {
1284 struct sshkey *key = NULL;
1285 char *cuser, *chost;
1286 u_int pubkey_auth_attempt;
1287 u_int type = 0;
1288 int r, allowed = 0;
1289 struct sshauthopt *opts = NULL;
1290
1291 debug3_f("entering");
1292 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1293 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 ||
1294 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
1295 (r = sshkey_froms(m, &key)) != 0 ||
1296 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0)
1297 fatal_fr(r, "parse");
1298
1299 if (key != NULL && authctxt->valid) {
1300 switch (type) {
1301 case MM_USERKEY:
1302 auth_method = "publickey";
1303 if (!options.pubkey_authentication)
1304 break;
1305 if (auth2_key_already_used(authctxt, key))
1306 break;
1307 if (!key_base_type_match(auth_method, key,
1308 options.pubkey_accepted_algos))
1309 break;
1310 allowed = user_key_allowed(ssh, authctxt->pw, key,
1311 pubkey_auth_attempt, &opts);
1312 break;
1313 case MM_HOSTKEY:
1314 auth_method = "hostbased";
1315 if (!options.hostbased_authentication)
1316 break;
1317 if (auth2_key_already_used(authctxt, key))
1318 break;
1319 if (!key_base_type_match(auth_method, key,
1320 options.hostbased_accepted_algos))
1321 break;
1322 allowed = hostbased_key_allowed(ssh, authctxt->pw,
1323 cuser, chost, key);
1324 auth2_record_info(authctxt,
1325 "client user \"%.100s\", client host \"%.100s\"",
1326 cuser, chost);
1327 break;
1328 default:
1329 fatal_f("unknown key type %u", type);
1330 break;
1331 }
1332 }
1333
1334 debug3_f("%s authentication%s: %s key is %s", auth_method,
1335 pubkey_auth_attempt ? "" : " test",
1336 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key),
1337 allowed ? "allowed" : "not allowed");
1338
1339 auth2_record_key(authctxt, 0, key);
1340
1341 /* clear temporarily storage (used by verify) */
1342 monitor_reset_key_state();
1343
1344 if (allowed) {
1345 /* Save temporarily for comparison in verify */
1346 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0)
1347 fatal_fr(r, "sshkey_to_blob");
1348 key_blobtype = type;
1349 key_opts = opts;
1350 hostbased_cuser = cuser;
1351 hostbased_chost = chost;
1352 } else {
1353 /* Log failed attempt */
1354 auth_log(ssh, 0, 0, auth_method, NULL);
1355 free(cuser);
1356 free(chost);
1357 }
1358 sshkey_free(key);
1359
1360 sshbuf_reset(m);
1361 if ((r = sshbuf_put_u32(m, allowed)) != 0)
1362 fatal_fr(r, "assemble");
1363 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0)
1364 fatal_fr(r, "sshauthopt_serialise");
1365 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);
1366
1367 if (!allowed)
1368 sshauthopt_free(opts);
1369
1370 return (0);
1371 }
1372
1373 static int
monitor_valid_userblob(struct ssh * ssh,const u_char * data,u_int datalen)1374 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen)
1375 {
1376 struct sshbuf *b;
1377 struct sshkey *hostkey = NULL;
1378 const u_char *p;
1379 char *userstyle, *cp;
1380 size_t len;
1381 u_char type;
1382 int hostbound = 0, r, fail = 0;
1383
1384 if ((b = sshbuf_from(data, datalen)) == NULL)
1385 fatal_f("sshbuf_from");
1386
1387 if (ssh->compat & SSH_OLD_SESSIONID) {
1388 p = sshbuf_ptr(b);
1389 len = sshbuf_len(b);
1390 if ((session_id2 == NULL) ||
1391 (len < session_id2_len) ||
1392 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1393 fail++;
1394 if ((r = sshbuf_consume(b, session_id2_len)) != 0)
1395 fatal_fr(r, "consume");
1396 } else {
1397 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1398 fatal_fr(r, "parse sessionid");
1399 if ((session_id2 == NULL) ||
1400 (len != session_id2_len) ||
1401 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1402 fail++;
1403 }
1404 if ((r = sshbuf_get_u8(b, &type)) != 0)
1405 fatal_fr(r, "parse type");
1406 if (type != SSH2_MSG_USERAUTH_REQUEST)
1407 fail++;
1408 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1409 fatal_fr(r, "parse userstyle");
1410 xasprintf(&userstyle, "%s%s%s", authctxt->user,
1411 authctxt->style ? ":" : "",
1412 authctxt->style ? authctxt->style : "");
1413 if (strcmp(userstyle, cp) != 0) {
1414 logit("wrong user name passed to monitor: "
1415 "expected %s != %.100s", userstyle, cp);
1416 fail++;
1417 }
1418 free(userstyle);
1419 free(cp);
1420 if ((r = sshbuf_skip_string(b)) != 0 || /* service */
1421 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1422 fatal_fr(r, "parse method");
1423 if (strcmp("publickey", cp) != 0) {
1424 if (strcmp("publickey-hostbound-v00@openssh.com", cp) == 0)
1425 hostbound = 1;
1426 else
1427 fail++;
1428 }
1429 free(cp);
1430 if ((r = sshbuf_get_u8(b, &type)) != 0)
1431 fatal_fr(r, "parse pktype");
1432 if (type == 0)
1433 fail++;
1434 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
1435 (r = sshbuf_skip_string(b)) != 0 || /* pkblob */
1436 (hostbound && (r = sshkey_froms(b, &hostkey)) != 0))
1437 fatal_fr(r, "parse pk");
1438 if (sshbuf_len(b) != 0)
1439 fail++;
1440 sshbuf_free(b);
1441 if (hostkey != NULL) {
1442 /*
1443 * Ensure this is actually one of our hostkeys; unfortunately
1444 * can't check ssh->kex->initial_hostkey directly at this point
1445 * as packet state has not yet been exported to monitor.
1446 */
1447 if (get_hostkey_index(hostkey, 1, ssh) == -1)
1448 fatal_f("hostbound hostkey does not match");
1449 sshkey_free(hostkey);
1450 }
1451 return (fail == 0);
1452 }
1453
1454 static int
monitor_valid_hostbasedblob(const u_char * data,u_int datalen,const char * cuser,const char * chost)1455 monitor_valid_hostbasedblob(const u_char *data, u_int datalen,
1456 const char *cuser, const char *chost)
1457 {
1458 struct sshbuf *b;
1459 const u_char *p;
1460 char *cp, *userstyle;
1461 size_t len;
1462 int r, fail = 0;
1463 u_char type;
1464
1465 if ((b = sshbuf_from(data, datalen)) == NULL)
1466 fatal_f("sshbuf_new");
1467 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1468 fatal_fr(r, "parse sessionid");
1469
1470 if ((session_id2 == NULL) ||
1471 (len != session_id2_len) ||
1472 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1473 fail++;
1474
1475 if ((r = sshbuf_get_u8(b, &type)) != 0)
1476 fatal_fr(r, "parse type");
1477 if (type != SSH2_MSG_USERAUTH_REQUEST)
1478 fail++;
1479 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1480 fatal_fr(r, "parse userstyle");
1481 xasprintf(&userstyle, "%s%s%s", authctxt->user,
1482 authctxt->style ? ":" : "",
1483 authctxt->style ? authctxt->style : "");
1484 if (strcmp(userstyle, cp) != 0) {
1485 logit("wrong user name passed to monitor: "
1486 "expected %s != %.100s", userstyle, cp);
1487 fail++;
1488 }
1489 free(userstyle);
1490 free(cp);
1491 if ((r = sshbuf_skip_string(b)) != 0 || /* service */
1492 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1493 fatal_fr(r, "parse method");
1494 if (strcmp(cp, "hostbased") != 0)
1495 fail++;
1496 free(cp);
1497 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
1498 (r = sshbuf_skip_string(b)) != 0) /* pkblob */
1499 fatal_fr(r, "parse pk");
1500
1501 /* verify client host, strip trailing dot if necessary */
1502 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1503 fatal_fr(r, "parse host");
1504 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.')
1505 cp[len - 1] = '\0';
1506 if (strcmp(cp, chost) != 0)
1507 fail++;
1508 free(cp);
1509
1510 /* verify client user */
1511 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1512 fatal_fr(r, "parse ruser");
1513 if (strcmp(cp, cuser) != 0)
1514 fail++;
1515 free(cp);
1516
1517 if (sshbuf_len(b) != 0)
1518 fail++;
1519 sshbuf_free(b);
1520 return (fail == 0);
1521 }
1522
1523 int
mm_answer_keyverify(struct ssh * ssh,int sock,struct sshbuf * m)1524 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m)
1525 {
1526 struct sshkey *key;
1527 const u_char *signature, *data, *blob;
1528 char *sigalg = NULL, *fp = NULL;
1529 size_t signaturelen, datalen, bloblen;
1530 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0;
1531 int encoded_ret;
1532 struct sshkey_sig_details *sig_details = NULL;
1533
1534 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 ||
1535 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 ||
1536 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 ||
1537 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0)
1538 fatal_fr(r, "parse");
1539
1540 if (hostbased_cuser == NULL || hostbased_chost == NULL ||
1541 !monitor_allowed_key(blob, bloblen))
1542 fatal_f("bad key, not previously allowed");
1543
1544 /* Empty signature algorithm means NULL. */
1545 if (*sigalg == '\0') {
1546 free(sigalg);
1547 sigalg = NULL;
1548 }
1549
1550 /* XXX use sshkey_froms here; need to change key_blob, etc. */
1551 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
1552 fatal_fr(r, "parse key");
1553
1554 switch (key_blobtype) {
1555 case MM_USERKEY:
1556 valid_data = monitor_valid_userblob(ssh, data, datalen);
1557 auth_method = "publickey";
1558 break;
1559 case MM_HOSTKEY:
1560 valid_data = monitor_valid_hostbasedblob(data, datalen,
1561 hostbased_cuser, hostbased_chost);
1562 auth_method = "hostbased";
1563 break;
1564 default:
1565 valid_data = 0;
1566 break;
1567 }
1568 if (!valid_data)
1569 fatal_f("bad %s signature data blob",
1570 key_blobtype == MM_USERKEY ? "userkey" :
1571 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown"));
1572
1573 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
1574 SSH_FP_DEFAULT)) == NULL)
1575 fatal_f("sshkey_fingerprint failed");
1576
1577 ret = sshkey_verify(key, signature, signaturelen, data, datalen,
1578 sigalg, ssh->compat, &sig_details);
1579 debug3_f("%s %s signature using %s %s%s%s", auth_method,
1580 sshkey_type(key), sigalg == NULL ? "default" : sigalg,
1581 (ret == 0) ? "verified" : "unverified",
1582 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : "");
1583
1584 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) {
1585 req_presence = (options.pubkey_auth_options &
1586 PUBKEYAUTH_TOUCH_REQUIRED) ||
1587 !key_opts->no_require_user_presence;
1588 if (req_presence &&
1589 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) {
1590 error("public key %s %s signature for %s%s from %.128s "
1591 "port %d rejected: user presence "
1592 "(authenticator touch) requirement not met ",
1593 sshkey_type(key), fp,
1594 authctxt->valid ? "" : "invalid user ",
1595 authctxt->user, ssh_remote_ipaddr(ssh),
1596 ssh_remote_port(ssh));
1597 ret = SSH_ERR_SIGNATURE_INVALID;
1598 }
1599 req_verify = (options.pubkey_auth_options &
1600 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify;
1601 if (req_verify &&
1602 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) {
1603 error("public key %s %s signature for %s%s from %.128s "
1604 "port %d rejected: user verification requirement "
1605 "not met ", sshkey_type(key), fp,
1606 authctxt->valid ? "" : "invalid user ",
1607 authctxt->user, ssh_remote_ipaddr(ssh),
1608 ssh_remote_port(ssh));
1609 ret = SSH_ERR_SIGNATURE_INVALID;
1610 }
1611 }
1612 auth2_record_key(authctxt, ret == 0, key);
1613
1614 if (key_blobtype == MM_USERKEY && ret == 0)
1615 auth_activate_options(ssh, key_opts);
1616 monitor_reset_key_state();
1617
1618 sshbuf_reset(m);
1619
1620 /* encode ret != 0 as positive integer, since we're sending u32 */
1621 encoded_ret = (ret != 0);
1622 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 ||
1623 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0)
1624 fatal_fr(r, "assemble");
1625 if (sig_details != NULL) {
1626 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 ||
1627 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0)
1628 fatal_fr(r, "assemble sk");
1629 }
1630 sshkey_sig_details_free(sig_details);
1631 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
1632
1633 free(sigalg);
1634 free(fp);
1635 sshkey_free(key);
1636
1637 return ret == 0;
1638 }
1639
1640 static void
mm_record_login(struct ssh * ssh,Session * s,struct passwd * pw)1641 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw)
1642 {
1643 socklen_t fromlen;
1644 struct sockaddr_storage from;
1645
1646 /*
1647 * Get IP address of client. If the connection is not a socket, let
1648 * the address be 0.0.0.0.
1649 */
1650 memset(&from, 0, sizeof(from));
1651 fromlen = sizeof(from);
1652 if (ssh_packet_connection_is_on_socket(ssh)) {
1653 if (getpeername(ssh_packet_get_connection_in(ssh),
1654 (struct sockaddr *)&from, &fromlen) == -1) {
1655 debug("getpeername: %.100s", strerror(errno));
1656 cleanup_exit(255);
1657 }
1658 }
1659 /* Record that there was a login on that tty from the remote host. */
1660 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid,
1661 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns),
1662 (struct sockaddr *)&from, fromlen);
1663 }
1664
1665 static void
mm_session_close(Session * s)1666 mm_session_close(Session *s)
1667 {
1668 debug3_f("session %d pid %ld", s->self, (long)s->pid);
1669 if (s->ttyfd != -1) {
1670 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd);
1671 session_pty_cleanup2(s);
1672 }
1673 session_unused(s->self);
1674 }
1675
1676 int
mm_answer_pty(struct ssh * ssh,int sock,struct sshbuf * m)1677 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m)
1678 {
1679 extern struct monitor *pmonitor;
1680 Session *s;
1681 int r, res, fd0;
1682
1683 debug3_f("entering");
1684
1685 sshbuf_reset(m);
1686 s = session_new();
1687 if (s == NULL)
1688 goto error;
1689 s->authctxt = authctxt;
1690 s->pw = authctxt->pw;
1691 s->pid = pmonitor->m_pid;
1692 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
1693 if (res == 0)
1694 goto error;
1695 pty_setowner(authctxt->pw, s->tty);
1696
1697 if ((r = sshbuf_put_u32(m, 1)) != 0 ||
1698 (r = sshbuf_put_cstring(m, s->tty)) != 0)
1699 fatal_fr(r, "assemble");
1700
1701 /* We need to trick ttyslot */
1702 if (dup2(s->ttyfd, 0) == -1)
1703 fatal_f("dup2");
1704
1705 mm_record_login(ssh, s, authctxt->pw);
1706
1707 /* Now we can close the file descriptor again */
1708 close(0);
1709
1710 /* send messages generated by record_login */
1711 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0)
1712 fatal_fr(r, "assemble loginmsg");
1713 sshbuf_reset(loginmsg);
1714
1715 mm_request_send(sock, MONITOR_ANS_PTY, m);
1716
1717 if (mm_send_fd(sock, s->ptyfd) == -1 ||
1718 mm_send_fd(sock, s->ttyfd) == -1)
1719 fatal_f("send fds failed");
1720
1721 /* make sure nothing uses fd 0 */
1722 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1723 fatal_f("open(/dev/null): %s", strerror(errno));
1724 if (fd0 != 0)
1725 error_f("fd0 %d != 0", fd0);
1726
1727 /* slave side of pty is not needed */
1728 close(s->ttyfd);
1729 s->ttyfd = s->ptyfd;
1730 /* no need to dup() because nobody closes ptyfd */
1731 s->ptymaster = s->ptyfd;
1732
1733 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd);
1734
1735 return (0);
1736
1737 error:
1738 if (s != NULL)
1739 mm_session_close(s);
1740 if ((r = sshbuf_put_u32(m, 0)) != 0)
1741 fatal_fr(r, "assemble 0");
1742 mm_request_send(sock, MONITOR_ANS_PTY, m);
1743 return (0);
1744 }
1745
1746 int
mm_answer_pty_cleanup(struct ssh * ssh,int sock,struct sshbuf * m)1747 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m)
1748 {
1749 Session *s;
1750 char *tty;
1751 int r;
1752
1753 debug3_f("entering");
1754
1755 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0)
1756 fatal_fr(r, "parse tty");
1757 if ((s = session_by_tty(tty)) != NULL)
1758 mm_session_close(s);
1759 sshbuf_reset(m);
1760 free(tty);
1761 return (0);
1762 }
1763
1764 int
mm_answer_term(struct ssh * ssh,int sock,struct sshbuf * req)1765 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req)
1766 {
1767 extern struct monitor *pmonitor;
1768 int res, status;
1769
1770 debug3_f("tearing down sessions");
1771
1772 /* The child is terminating */
1773 session_destroy_all(ssh, &mm_session_close);
1774
1775 #ifdef USE_PAM
1776 if (options.use_pam)
1777 sshpam_cleanup();
1778 #endif
1779
1780 while (waitpid(pmonitor->m_pid, &status, 0) == -1)
1781 if (errno != EINTR)
1782 exit(1);
1783
1784 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
1785
1786 /* Terminate process */
1787 exit(res);
1788 }
1789
1790 #ifdef SSH_AUDIT_EVENTS
1791 /* Report that an audit event occurred */
1792 int
mm_answer_audit_event(struct ssh * ssh,int socket,struct sshbuf * m)1793 mm_answer_audit_event(struct ssh *ssh, int socket, struct sshbuf *m)
1794 {
1795 u_int n;
1796 ssh_audit_event_t event;
1797 int r;
1798
1799 debug3_f("entering");
1800
1801 if ((r = sshbuf_get_u32(m, &n)) != 0)
1802 fatal_fr(r, "buffer error");
1803 event = (ssh_audit_event_t)n;
1804 switch (event) {
1805 case SSH_AUTH_FAIL_PUBKEY:
1806 case SSH_AUTH_FAIL_HOSTBASED:
1807 case SSH_AUTH_FAIL_GSSAPI:
1808 case SSH_LOGIN_EXCEED_MAXTRIES:
1809 case SSH_LOGIN_ROOT_DENIED:
1810 case SSH_CONNECTION_CLOSE:
1811 case SSH_INVALID_USER:
1812 audit_event(ssh, event);
1813 break;
1814 default:
1815 fatal("Audit event type %d not permitted", event);
1816 }
1817
1818 return (0);
1819 }
1820
1821 int
mm_answer_audit_command(struct ssh * ssh,int socket,struct sshbuf * m)1822 mm_answer_audit_command(struct ssh *ssh, int socket, struct sshbuf *m)
1823 {
1824 char *cmd;
1825 int r;
1826
1827 debug3_f("entering");
1828 if ((r = sshbuf_get_cstring(m, &cmd, NULL)) != 0)
1829 fatal_fr(r, "buffer error");
1830 /* sanity check command, if so how? */
1831 audit_run_command(cmd);
1832 free(cmd);
1833 return (0);
1834 }
1835 #endif /* SSH_AUDIT_EVENTS */
1836
1837 void
monitor_clear_keystate(struct ssh * ssh,struct monitor * pmonitor)1838 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor)
1839 {
1840 ssh_clear_newkeys(ssh, MODE_IN);
1841 ssh_clear_newkeys(ssh, MODE_OUT);
1842 sshbuf_free(child_state);
1843 child_state = NULL;
1844 }
1845
1846 void
monitor_apply_keystate(struct ssh * ssh,struct monitor * pmonitor)1847 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor)
1848 {
1849 struct kex *kex;
1850 int r;
1851
1852 debug3_f("packet_set_state");
1853 if ((r = ssh_packet_set_state(ssh, child_state)) != 0)
1854 fatal_fr(r, "packet_set_state");
1855 sshbuf_free(child_state);
1856 child_state = NULL;
1857 if ((kex = ssh->kex) == NULL)
1858 fatal_f("internal error: ssh->kex == NULL");
1859 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) {
1860 fatal_f("incorrect session id length %zu (expected %u)",
1861 sshbuf_len(ssh->kex->session_id), session_id2_len);
1862 }
1863 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2,
1864 session_id2_len) != 0)
1865 fatal_f("session ID mismatch");
1866 /* XXX set callbacks */
1867 #ifdef WITH_OPENSSL
1868 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
1869 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
1870 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
1871 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
1872 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
1873 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1874 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1875 # ifdef OPENSSL_HAS_ECC
1876 kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
1877 # endif
1878 #endif /* WITH_OPENSSL */
1879 kex->kex[KEX_C25519_SHA256] = kex_gen_server;
1880 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
1881 kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server;
1882 kex->load_host_public_key=&get_hostkey_public_by_type;
1883 kex->load_host_private_key=&get_hostkey_private_by_type;
1884 kex->host_key_index=&get_hostkey_index;
1885 kex->sign = sshd_hostkey_sign;
1886 }
1887
1888 /* This function requires careful sanity checking */
1889
1890 void
mm_get_keystate(struct ssh * ssh,struct monitor * pmonitor)1891 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor)
1892 {
1893 debug3_f("Waiting for new keys");
1894
1895 if ((child_state = sshbuf_new()) == NULL)
1896 fatal_f("sshbuf_new failed");
1897 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT,
1898 child_state);
1899 debug3_f("GOT new keys");
1900 }
1901
1902
1903 /* XXX */
1904
1905 static void
monitor_openfds(struct monitor * mon,int do_logfds)1906 monitor_openfds(struct monitor *mon, int do_logfds)
1907 {
1908 int pair[2];
1909 #ifdef SO_ZEROIZE
1910 int on = 1;
1911 #endif
1912
1913 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
1914 fatal_f("socketpair: %s", strerror(errno));
1915 #ifdef SO_ZEROIZE
1916 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1917 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno));
1918 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1919 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno));
1920 #endif
1921 FD_CLOSEONEXEC(pair[0]);
1922 FD_CLOSEONEXEC(pair[1]);
1923 mon->m_recvfd = pair[0];
1924 mon->m_sendfd = pair[1];
1925
1926 if (do_logfds) {
1927 if (pipe(pair) == -1)
1928 fatal_f("pipe: %s", strerror(errno));
1929 FD_CLOSEONEXEC(pair[0]);
1930 FD_CLOSEONEXEC(pair[1]);
1931 mon->m_log_recvfd = pair[0];
1932 mon->m_log_sendfd = pair[1];
1933 } else
1934 mon->m_log_recvfd = mon->m_log_sendfd = -1;
1935 }
1936
1937 struct monitor *
monitor_init(void)1938 monitor_init(void)
1939 {
1940 struct monitor *mon;
1941
1942 mon = xcalloc(1, sizeof(*mon));
1943 monitor_openfds(mon, 1);
1944
1945 return mon;
1946 }
1947
1948 void
monitor_reinit(struct monitor * mon)1949 monitor_reinit(struct monitor *mon)
1950 {
1951 monitor_openfds(mon, 0);
1952 }
1953
1954 int
monitor_auth_attempted(void)1955 monitor_auth_attempted(void)
1956 {
1957 return auth_attempted;
1958 }
1959
1960 int
monitor_invalid_user(void)1961 monitor_invalid_user(void)
1962 {
1963 return invalid_user;
1964 }
1965
1966 #ifdef GSSAPI
1967 int
mm_answer_gss_setup_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1968 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1969 {
1970 gss_OID_desc goid;
1971 OM_uint32 major;
1972 size_t len;
1973 u_char *p;
1974 int r;
1975
1976 if (!options.gss_authentication)
1977 fatal_f("GSSAPI authentication not enabled");
1978
1979 if ((r = sshbuf_get_string(m, &p, &len)) != 0)
1980 fatal_fr(r, "parse");
1981 goid.elements = p;
1982 goid.length = len;
1983
1984 major = ssh_gssapi_server_ctx(&gsscontext, &goid);
1985
1986 free(goid.elements);
1987
1988 sshbuf_reset(m);
1989 if ((r = sshbuf_put_u32(m, major)) != 0)
1990 fatal_fr(r, "assemble");
1991
1992 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m);
1993
1994 /* Now we have a context, enable the step */
1995 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1);
1996
1997 return (0);
1998 }
1999
2000 int
mm_answer_gss_accept_ctx(struct ssh * ssh,int sock,struct sshbuf * m)2001 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
2002 {
2003 gss_buffer_desc in;
2004 gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
2005 OM_uint32 major, minor;
2006 OM_uint32 flags = 0; /* GSI needs this */
2007 int r;
2008
2009 if (!options.gss_authentication)
2010 fatal_f("GSSAPI authentication not enabled");
2011
2012 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
2013 fatal_fr(r, "ssh_gssapi_get_buffer_desc");
2014 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
2015 free(in.value);
2016
2017 sshbuf_reset(m);
2018 if ((r = sshbuf_put_u32(m, major)) != 0 ||
2019 (r = sshbuf_put_string(m, out.value, out.length)) != 0 ||
2020 (r = sshbuf_put_u32(m, flags)) != 0)
2021 fatal_fr(r, "assemble");
2022 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m);
2023
2024 gss_release_buffer(&minor, &out);
2025
2026 if (major == GSS_S_COMPLETE) {
2027 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
2028 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
2029 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
2030 }
2031 return (0);
2032 }
2033
2034 int
mm_answer_gss_checkmic(struct ssh * ssh,int sock,struct sshbuf * m)2035 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
2036 {
2037 gss_buffer_desc gssbuf, mic;
2038 OM_uint32 ret;
2039 int r;
2040
2041 if (!options.gss_authentication)
2042 fatal_f("GSSAPI authentication not enabled");
2043
2044 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
2045 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
2046 fatal_fr(r, "ssh_gssapi_get_buffer_desc");
2047
2048 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
2049
2050 free(gssbuf.value);
2051 free(mic.value);
2052
2053 sshbuf_reset(m);
2054 if ((r = sshbuf_put_u32(m, ret)) != 0)
2055 fatal_fr(r, "assemble");
2056
2057 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m);
2058
2059 if (!GSS_ERROR(ret))
2060 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
2061
2062 return (0);
2063 }
2064
2065 int
mm_answer_gss_userok(struct ssh * ssh,int sock,struct sshbuf * m)2066 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
2067 {
2068 int r, authenticated;
2069 const char *displayname;
2070
2071 if (!options.gss_authentication)
2072 fatal_f("GSSAPI authentication not enabled");
2073
2074 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
2075
2076 sshbuf_reset(m);
2077 if ((r = sshbuf_put_u32(m, authenticated)) != 0)
2078 fatal_fr(r, "assemble");
2079
2080 debug3_f("sending result %d", authenticated);
2081 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
2082
2083 auth_method = "gssapi-with-mic";
2084
2085 if ((displayname = ssh_gssapi_displayname()) != NULL)
2086 auth2_record_info(authctxt, "%s", displayname);
2087
2088 /* Monitor loop will terminate if authenticated */
2089 return (authenticated);
2090 }
2091 #endif /* GSSAPI */
2092
2093