1 /* $OpenBSD: monitor.c,v 1.244 2024/09/15 01:09:40 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/socket.h>
32 #include <sys/wait.h>
33
34 #include <errno.h>
35 #include <fcntl.h>
36 #include <limits.h>
37 #ifdef HAVE_PATHS_H
38 #include <paths.h>
39 #endif
40 #include <pwd.h>
41 #include <signal.h>
42 #ifdef HAVE_STDINT_H
43 # include <stdint.h>
44 #endif
45 #include <stdlib.h>
46 #include <string.h>
47 #include <stdarg.h>
48 #include <stdio.h>
49 #include <unistd.h>
50 #ifdef HAVE_POLL_H
51 #include <poll.h>
52 #else
53 # ifdef HAVE_SYS_POLL_H
54 # include <sys/poll.h>
55 # endif
56 #endif
57
58 #ifdef WITH_OPENSSL
59 #include <openssl/dh.h>
60 #endif
61
62 #include "openbsd-compat/sys-tree.h"
63 #include "openbsd-compat/sys-queue.h"
64 #include "openbsd-compat/openssl-compat.h"
65
66 #include "atomicio.h"
67 #include "xmalloc.h"
68 #include "ssh.h"
69 #include "sshkey.h"
70 #include "sshbuf.h"
71 #include "hostfile.h"
72 #include "auth.h"
73 #include "cipher.h"
74 #include "kex.h"
75 #include "dh.h"
76 #include "auth-pam.h"
77 #include "packet.h"
78 #include "auth-options.h"
79 #include "sshpty.h"
80 #include "channels.h"
81 #include "session.h"
82 #include "sshlogin.h"
83 #include "canohost.h"
84 #include "log.h"
85 #include "misc.h"
86 #include "servconf.h"
87 #include "monitor.h"
88 #ifdef GSSAPI
89 #include "ssh-gss.h"
90 #endif
91 #include "monitor_wrap.h"
92 #include "monitor_fdpass.h"
93 #include "compat.h"
94 #include "ssh2.h"
95 #include "authfd.h"
96 #include "match.h"
97 #include "ssherr.h"
98 #include "sk-api.h"
99 #include "srclimit.h"
100
101 #ifdef GSSAPI
102 static Gssctxt *gsscontext = NULL;
103 #endif
104
105 /* Imports */
106 extern ServerOptions options;
107 extern u_int utmp_len;
108 extern struct sshbuf *loginmsg;
109 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */
110
111 /* State exported from the child */
112 static struct sshbuf *child_state;
113
114 /* Functions on the monitor that answer unprivileged requests */
115
116 int mm_answer_moduli(struct ssh *, int, struct sshbuf *);
117 int mm_answer_sign(struct ssh *, int, struct sshbuf *);
118 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *);
119 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *);
120 int mm_answer_authserv(struct ssh *, int, struct sshbuf *);
121 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *);
122 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *);
123 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *);
124 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *);
125 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *);
126 int mm_answer_pty(struct ssh *, int, struct sshbuf *);
127 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *);
128 int mm_answer_term(struct ssh *, int, struct sshbuf *);
129
130 #ifdef USE_PAM
131 int mm_answer_pam_start(struct ssh *, int, struct sshbuf *);
132 int mm_answer_pam_account(struct ssh *, int, struct sshbuf *);
133 int mm_answer_pam_init_ctx(struct ssh *, int, struct sshbuf *);
134 int mm_answer_pam_query(struct ssh *, int, struct sshbuf *);
135 int mm_answer_pam_respond(struct ssh *, int, struct sshbuf *);
136 int mm_answer_pam_free_ctx(struct ssh *, int, struct sshbuf *);
137 #endif
138
139 #ifdef GSSAPI
140 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *);
141 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *);
142 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *);
143 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *);
144 #endif
145
146 #ifdef SSH_AUDIT_EVENTS
147 int mm_answer_audit_event(struct ssh *, int, struct sshbuf *);
148 int mm_answer_audit_command(struct ssh *, int, struct sshbuf *);
149 #endif
150
151 static Authctxt *authctxt;
152
153 /* local state for key verify */
154 static u_char *key_blob = NULL;
155 static size_t key_bloblen = 0;
156 static u_int key_blobtype = MM_NOKEY;
157 static struct sshauthopt *key_opts = NULL;
158 static char *hostbased_cuser = NULL;
159 static char *hostbased_chost = NULL;
160 static char *auth_method = "unknown";
161 static char *auth_submethod = NULL;
162 static u_int session_id2_len = 0;
163 static u_char *session_id2 = NULL;
164 static pid_t monitor_child_pid;
165 int auth_attempted = 0;
166
167 struct mon_table {
168 enum monitor_reqtype type;
169 int flags;
170 int (*f)(struct ssh *, int, struct sshbuf *);
171 };
172
173 #define MON_ISAUTH 0x0004 /* Required for Authentication */
174 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */
175 #define MON_ONCE 0x0010 /* Disable after calling */
176 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */
177
178 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE)
179
180 #define MON_PERMIT 0x1000 /* Request is permitted */
181
182 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *,
183 struct mon_table **);
184 static int monitor_read_log(struct monitor *);
185
186 struct mon_table mon_dispatch_proto20[] = {
187 #ifdef WITH_OPENSSL
188 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
189 #endif
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 #ifdef WITH_OPENSSL
223 {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
224 #endif
225 {MONITOR_REQ_SIGN, 0, mm_answer_sign},
226 {MONITOR_REQ_PTY, 0, mm_answer_pty},
227 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup},
228 {MONITOR_REQ_TERM, 0, mm_answer_term},
229 #ifdef SSH_AUDIT_EVENTS
230 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
231 {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command},
232 #endif
233 {0, 0, NULL}
234 };
235
236 struct mon_table *mon_dispatch;
237
238 /* Specifies if a certain message is allowed at the moment */
239 static void
monitor_permit(struct mon_table * ent,enum monitor_reqtype type,int permit)240 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
241 {
242 while (ent->f != NULL) {
243 if (ent->type == type) {
244 ent->flags &= ~MON_PERMIT;
245 ent->flags |= permit ? MON_PERMIT : 0;
246 return;
247 }
248 ent++;
249 }
250 }
251
252 static void
monitor_permit_authentications(int permit)253 monitor_permit_authentications(int permit)
254 {
255 struct mon_table *ent = mon_dispatch;
256
257 while (ent->f != NULL) {
258 if (ent->flags & MON_AUTH) {
259 ent->flags &= ~MON_PERMIT;
260 ent->flags |= permit ? MON_PERMIT : 0;
261 }
262 ent++;
263 }
264 }
265
266 void
monitor_child_preauth(struct ssh * ssh,struct monitor * pmonitor)267 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
268 {
269 struct mon_table *ent;
270 int authenticated = 0, partial = 0;
271
272 debug3("preauth child monitor started");
273
274 if (pmonitor->m_recvfd >= 0)
275 close(pmonitor->m_recvfd);
276 if (pmonitor->m_log_sendfd >= 0)
277 close(pmonitor->m_log_sendfd);
278 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
279
280 authctxt = (Authctxt *)ssh->authctxt;
281 memset(authctxt, 0, sizeof(*authctxt));
282 ssh->authctxt = authctxt;
283
284 authctxt->loginmsg = loginmsg;
285
286 mon_dispatch = mon_dispatch_proto20;
287 /* Permit requests for moduli and signatures */
288 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
289 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
290
291 /* The first few requests do not require asynchronous access */
292 while (!authenticated) {
293 partial = 0;
294 auth_method = "unknown";
295 auth_submethod = NULL;
296 auth2_authctxt_reset_info(authctxt);
297
298 authenticated = (monitor_read(ssh, pmonitor,
299 mon_dispatch, &ent) == 1);
300
301 /* Record that auth was attempted to set exit status later */
302 if ((ent->flags & MON_AUTH) != 0)
303 auth_attempted = 1;
304
305 /* Special handling for multiple required authentications */
306 if (options.num_auth_methods != 0) {
307 if (authenticated &&
308 !auth2_update_methods_lists(authctxt,
309 auth_method, auth_submethod)) {
310 debug3_f("method %s: partial", auth_method);
311 authenticated = 0;
312 partial = 1;
313 }
314 }
315
316 if (authenticated) {
317 if (!(ent->flags & MON_AUTHDECIDE))
318 fatal_f("unexpected authentication from %d",
319 ent->type);
320 if (authctxt->pw->pw_uid == 0 &&
321 !auth_root_allowed(ssh, auth_method))
322 authenticated = 0;
323 #ifdef USE_PAM
324 /* PAM needs to perform account checks after auth */
325 if (options.use_pam && authenticated) {
326 struct sshbuf *m;
327
328 if ((m = sshbuf_new()) == NULL)
329 fatal("%s: sshbuf_new failed",
330 __func__);
331 mm_request_receive_expect(pmonitor->m_sendfd,
332 MONITOR_REQ_PAM_ACCOUNT, m);
333 authenticated = mm_answer_pam_account(
334 ssh, pmonitor->m_sendfd, m);
335 sshbuf_free(m);
336 }
337 #endif
338 }
339 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
340 auth_log(ssh, authenticated, partial,
341 auth_method, auth_submethod);
342 if (!partial && !authenticated)
343 authctxt->failures++;
344 if (authenticated || partial) {
345 auth2_update_session_info(authctxt,
346 auth_method, auth_submethod);
347 }
348 }
349 if (authctxt->failures > options.max_authtries) {
350 /* Shouldn't happen */
351 fatal_f("privsep child made too many authentication "
352 "attempts");
353 }
354 }
355
356 if (!authctxt->valid)
357 fatal_f("authenticated invalid user");
358 if (strcmp(auth_method, "unknown") == 0)
359 fatal_f("authentication method name unknown");
360
361 debug_f("user %s authenticated by privileged process", authctxt->user);
362 auth_attempted = 0;
363 ssh->authctxt = NULL;
364 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
365
366 mm_get_keystate(ssh, pmonitor);
367
368 /* Drain any buffered messages from the child */
369 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
370 ;
371
372 if (pmonitor->m_recvfd >= 0)
373 close(pmonitor->m_recvfd);
374 if (pmonitor->m_log_sendfd >= 0)
375 close(pmonitor->m_log_sendfd);
376 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
377 }
378
379 static void
monitor_set_child_handler(pid_t pid)380 monitor_set_child_handler(pid_t pid)
381 {
382 monitor_child_pid = pid;
383 }
384
385 static void
monitor_child_handler(int sig)386 monitor_child_handler(int sig)
387 {
388 kill(monitor_child_pid, sig);
389 }
390
391 void
monitor_child_postauth(struct ssh * ssh,struct monitor * pmonitor)392 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
393 {
394 close(pmonitor->m_recvfd);
395 pmonitor->m_recvfd = -1;
396
397 monitor_set_child_handler(pmonitor->m_pid);
398 ssh_signal(SIGHUP, &monitor_child_handler);
399 ssh_signal(SIGTERM, &monitor_child_handler);
400 ssh_signal(SIGINT, &monitor_child_handler);
401 #ifdef SIGXFSZ
402 ssh_signal(SIGXFSZ, SIG_IGN);
403 #endif
404
405 mon_dispatch = mon_dispatch_postauth20;
406
407 /* Permit requests for moduli and signatures */
408 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
409 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
410 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
411
412 if (auth_opts->permit_pty_flag) {
413 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
414 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
415 }
416
417 for (;;)
418 monitor_read(ssh, pmonitor, mon_dispatch, NULL);
419 }
420
421 static int
monitor_read_log(struct monitor * pmonitor)422 monitor_read_log(struct monitor *pmonitor)
423 {
424 struct sshbuf *logmsg;
425 u_int len, level, forced;
426 char *msg;
427 u_char *p;
428 int r;
429
430 if ((logmsg = sshbuf_new()) == NULL)
431 fatal_f("sshbuf_new");
432
433 /* Read length */
434 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0)
435 fatal_fr(r, "reserve len");
436 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) {
437 if (errno == EPIPE) {
438 sshbuf_free(logmsg);
439 debug_f("child log fd closed");
440 close(pmonitor->m_log_recvfd);
441 pmonitor->m_log_recvfd = -1;
442 return -1;
443 }
444 fatal_f("log fd read: %s", strerror(errno));
445 }
446 if ((r = sshbuf_get_u32(logmsg, &len)) != 0)
447 fatal_fr(r, "parse len");
448 if (len <= 4 || len > 8192)
449 fatal_f("invalid log message length %u", len);
450
451 /* Read severity, message */
452 sshbuf_reset(logmsg);
453 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0)
454 fatal_fr(r, "reserve msg");
455 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len)
456 fatal_f("log fd read: %s", strerror(errno));
457 if ((r = sshbuf_get_u32(logmsg, &level)) != 0 ||
458 (r = sshbuf_get_u32(logmsg, &forced)) != 0 ||
459 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0)
460 fatal_fr(r, "parse");
461
462 /* Log it */
463 if (log_level_name(level) == NULL)
464 fatal_f("invalid log level %u (corrupted message?)", level);
465 sshlogdirect(level, forced, "%s [preauth]", msg);
466
467 sshbuf_free(logmsg);
468 free(msg);
469
470 return 0;
471 }
472
473 static int
monitor_read(struct ssh * ssh,struct monitor * pmonitor,struct mon_table * ent,struct mon_table ** pent)474 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent,
475 struct mon_table **pent)
476 {
477 struct sshbuf *m;
478 int r, ret;
479 u_char type;
480 struct pollfd pfd[2];
481
482 for (;;) {
483 memset(&pfd, 0, sizeof(pfd));
484 pfd[0].fd = pmonitor->m_sendfd;
485 pfd[0].events = POLLIN;
486 pfd[1].fd = pmonitor->m_log_recvfd;
487 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN;
488 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) {
489 if (errno == EINTR || errno == EAGAIN)
490 continue;
491 fatal_f("poll: %s", strerror(errno));
492 }
493 if (pfd[1].revents) {
494 /*
495 * Drain all log messages before processing next
496 * monitor request.
497 */
498 monitor_read_log(pmonitor);
499 continue;
500 }
501 if (pfd[0].revents)
502 break; /* Continues below */
503 }
504
505 if ((m = sshbuf_new()) == NULL)
506 fatal_f("sshbuf_new");
507
508 mm_request_receive(pmonitor->m_sendfd, m);
509 if ((r = sshbuf_get_u8(m, &type)) != 0)
510 fatal_fr(r, "parse type");
511
512 debug3_f("checking request %d", type);
513
514 while (ent->f != NULL) {
515 if (ent->type == type)
516 break;
517 ent++;
518 }
519
520 if (ent->f != NULL) {
521 if (!(ent->flags & MON_PERMIT))
522 fatal_f("unpermitted request %d", type);
523 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m);
524 sshbuf_free(m);
525
526 /* The child may use this request only once, disable it */
527 if (ent->flags & MON_ONCE) {
528 debug2_f("%d used once, disabling now", type);
529 ent->flags &= ~MON_PERMIT;
530 }
531
532 if (pent != NULL)
533 *pent = ent;
534
535 return ret;
536 }
537
538 fatal_f("unsupported request: %d", type);
539
540 /* NOTREACHED */
541 return (-1);
542 }
543
544 /* allowed key state */
545 static int
monitor_allowed_key(const u_char * blob,u_int bloblen)546 monitor_allowed_key(const u_char *blob, u_int bloblen)
547 {
548 /* make sure key is allowed */
549 if (key_blob == NULL || key_bloblen != bloblen ||
550 timingsafe_bcmp(key_blob, blob, key_bloblen))
551 return (0);
552 return (1);
553 }
554
555 static void
monitor_reset_key_state(void)556 monitor_reset_key_state(void)
557 {
558 /* reset state */
559 free(key_blob);
560 free(hostbased_cuser);
561 free(hostbased_chost);
562 sshauthopt_free(key_opts);
563 key_blob = NULL;
564 key_bloblen = 0;
565 key_blobtype = MM_NOKEY;
566 key_opts = NULL;
567 hostbased_cuser = NULL;
568 hostbased_chost = NULL;
569 }
570
571 #ifdef WITH_OPENSSL
572 int
mm_answer_moduli(struct ssh * ssh,int sock,struct sshbuf * m)573 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m)
574 {
575 DH *dh;
576 const BIGNUM *dh_p, *dh_g;
577 int r;
578 u_int min, want, max;
579
580 if ((r = sshbuf_get_u32(m, &min)) != 0 ||
581 (r = sshbuf_get_u32(m, &want)) != 0 ||
582 (r = sshbuf_get_u32(m, &max)) != 0)
583 fatal_fr(r, "parse");
584
585 debug3_f("got parameters: %d %d %d", min, want, max);
586 /* We need to check here, too, in case the child got corrupted */
587 if (max < min || want < min || max < want)
588 fatal_f("bad parameters: %d %d %d", min, want, max);
589
590 sshbuf_reset(m);
591
592 dh = choose_dh(min, want, max);
593 if (dh == NULL) {
594 if ((r = sshbuf_put_u8(m, 0)) != 0)
595 fatal_fr(r, "assemble empty");
596 return (0);
597 } else {
598 /* Send first bignum */
599 DH_get0_pqg(dh, &dh_p, NULL, &dh_g);
600 if ((r = sshbuf_put_u8(m, 1)) != 0 ||
601 (r = sshbuf_put_bignum2(m, dh_p)) != 0 ||
602 (r = sshbuf_put_bignum2(m, dh_g)) != 0)
603 fatal_fr(r, "assemble");
604
605 DH_free(dh);
606 }
607 mm_request_send(sock, MONITOR_ANS_MODULI, m);
608 return (0);
609 }
610 #endif
611
612 int
mm_answer_sign(struct ssh * ssh,int sock,struct sshbuf * m)613 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
614 {
615 extern int auth_sock; /* XXX move to state struct? */
616 struct sshkey *key;
617 struct sshbuf *sigbuf = NULL;
618 u_char *p = NULL, *signature = NULL;
619 char *alg = NULL;
620 size_t datlen, siglen, alglen;
621 int r, is_proof = 0;
622 u_int keyid, compat;
623 const char proof_req[] = "hostkeys-prove-00@openssh.com";
624
625 debug3_f("entering");
626
627 if ((r = sshbuf_get_u32(m, &keyid)) != 0 ||
628 (r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
629 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 ||
630 (r = sshbuf_get_u32(m, &compat)) != 0)
631 fatal_fr(r, "parse");
632 if (keyid > INT_MAX)
633 fatal_f("invalid key ID");
634
635 /*
636 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),
637 * SHA384 (48 bytes) and SHA512 (64 bytes).
638 *
639 * Otherwise, verify the signature request is for a hostkey
640 * proof.
641 *
642 * XXX perform similar check for KEX signature requests too?
643 * it's not trivial, since what is signed is the hash, rather
644 * than the full kex structure...
645 */
646 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) {
647 /*
648 * Construct expected hostkey proof and compare it to what
649 * the client sent us.
650 */
651 if (session_id2_len == 0) /* hostkeys is never first */
652 fatal_f("bad data length: %zu", datlen);
653 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL)
654 fatal_f("no hostkey for index %d", keyid);
655 if ((sigbuf = sshbuf_new()) == NULL)
656 fatal_f("sshbuf_new");
657 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 ||
658 (r = sshbuf_put_string(sigbuf, session_id2,
659 session_id2_len)) != 0 ||
660 (r = sshkey_puts(key, sigbuf)) != 0)
661 fatal_fr(r, "assemble private key proof");
662 if (datlen != sshbuf_len(sigbuf) ||
663 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0)
664 fatal_f("bad data length: %zu, hostkey proof len %zu",
665 datlen, sshbuf_len(sigbuf));
666 sshbuf_free(sigbuf);
667 is_proof = 1;
668 }
669
670 /* save session id, it will be passed on the first call */
671 if (session_id2_len == 0) {
672 session_id2_len = datlen;
673 session_id2 = xmalloc(session_id2_len);
674 memcpy(session_id2, p, session_id2_len);
675 }
676
677 if ((key = get_hostkey_by_index(keyid)) != NULL) {
678 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
679 options.sk_provider, NULL, compat)) != 0)
680 fatal_fr(r, "sign");
681 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
682 auth_sock > 0) {
683 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen,
684 p, datlen, alg, compat)) != 0)
685 fatal_fr(r, "agent sign");
686 } else
687 fatal_f("no hostkey from index %d", keyid);
688
689 debug3_f("%s %s signature len=%zu", alg,
690 is_proof ? "hostkey proof" : "KEX", siglen);
691
692 sshbuf_reset(m);
693 if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
694 fatal_fr(r, "assemble");
695
696 free(alg);
697 free(p);
698 free(signature);
699
700 mm_request_send(sock, MONITOR_ANS_SIGN, m);
701
702 /* Turn on permissions for getpwnam */
703 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
704
705 return (0);
706 }
707
708 #define PUTPW(b, id) \
709 do { \
710 if ((r = sshbuf_put_string(b, \
711 &pwent->id, sizeof(pwent->id))) != 0) \
712 fatal_fr(r, "assemble %s", #id); \
713 } while (0)
714
715 void
mm_encode_server_options(struct sshbuf * m)716 mm_encode_server_options(struct sshbuf *m)
717 {
718 int r;
719 u_int i;
720
721 /* XXX this leaks raw pointers to the unpriv child processes */
722 if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0)
723 fatal_fr(r, "assemble options");
724
725 #define M_CP_STROPT(x) do { \
726 if (options.x != NULL && \
727 (r = sshbuf_put_cstring(m, options.x)) != 0) \
728 fatal_fr(r, "assemble %s", #x); \
729 } while (0)
730 #define M_CP_STRARRAYOPT(x, nx) do { \
731 for (i = 0; i < options.nx; i++) { \
732 if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \
733 fatal_fr(r, "assemble %s", #x); \
734 } \
735 } while (0)
736 /* See comment in servconf.h */
737 COPY_MATCH_STRING_OPTS();
738 #undef M_CP_STROPT
739 #undef M_CP_STRARRAYOPT
740 }
741
742 /* Retrieves the password entry and also checks if the user is permitted */
743 int
mm_answer_pwnamallow(struct ssh * ssh,int sock,struct sshbuf * m)744 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m)
745 {
746 struct passwd *pwent;
747 int r, allowed = 0;
748
749 debug3_f("entering");
750
751 if (authctxt->attempt++ != 0)
752 fatal_f("multiple attempts for getpwnam");
753
754 if ((r = sshbuf_get_cstring(m, &authctxt->user, NULL)) != 0)
755 fatal_fr(r, "parse");
756
757 pwent = getpwnamallow(ssh, authctxt->user);
758
759 setproctitle("%s [priv]", pwent ? authctxt->user : "unknown");
760
761 sshbuf_reset(m);
762
763 if (pwent == NULL) {
764 if ((r = sshbuf_put_u8(m, 0)) != 0)
765 fatal_fr(r, "assemble fakepw");
766 authctxt->pw = fakepw();
767 goto out;
768 }
769
770 allowed = 1;
771 authctxt->pw = pwent;
772 authctxt->valid = 1;
773
774 /* XXX send fake class/dir/shell, etc. */
775 if ((r = sshbuf_put_u8(m, 1)) != 0)
776 fatal_fr(r, "assemble ok");
777 PUTPW(m, pw_uid);
778 PUTPW(m, pw_gid);
779 #ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
780 PUTPW(m, pw_change);
781 #endif
782 #ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
783 PUTPW(m, pw_expire);
784 #endif
785 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
786 (r = sshbuf_put_cstring(m, "*")) != 0 ||
787 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
788 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 ||
789 #endif
790 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
791 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 ||
792 #endif
793 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 ||
794 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0)
795 fatal_fr(r, "assemble pw");
796
797 out:
798 ssh_packet_set_log_preamble(ssh, "%suser %s",
799 authctxt->valid ? "authenticating" : "invalid ", authctxt->user);
800
801 if (options.refuse_connection) {
802 logit("administratively prohibited connection for "
803 "%s%s from %.128s port %d",
804 authctxt->valid ? "" : "invalid user ",
805 authctxt->user, ssh_remote_ipaddr(ssh),
806 ssh_remote_port(ssh));
807 cleanup_exit(EXIT_CONFIG_REFUSED);
808 }
809
810 /* Send active options to unpriv */
811 mm_encode_server_options(m);
812
813 /* Create valid auth method lists */
814 if (auth2_setup_methods_lists(authctxt) != 0) {
815 /*
816 * The monitor will continue long enough to let the child
817 * run to its packet_disconnect(), but it must not allow any
818 * authentication to succeed.
819 */
820 debug_f("no valid authentication method lists");
821 }
822
823 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed);
824 mm_request_send(sock, MONITOR_ANS_PWNAM, m);
825
826 /* Allow service/style information on the auth context */
827 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
828 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1);
829
830 #ifdef USE_PAM
831 if (options.use_pam)
832 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
833 #endif
834
835 return (0);
836 }
837
mm_answer_auth2_read_banner(struct ssh * ssh,int sock,struct sshbuf * m)838 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m)
839 {
840 char *banner;
841 int r;
842
843 sshbuf_reset(m);
844 banner = auth2_read_banner();
845 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0)
846 fatal_fr(r, "assemble");
847 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
848 free(banner);
849
850 return (0);
851 }
852
853 int
mm_answer_authserv(struct ssh * ssh,int sock,struct sshbuf * m)854 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m)
855 {
856 int r;
857
858 monitor_permit_authentications(1);
859
860 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 ||
861 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0)
862 fatal_fr(r, "parse");
863 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style);
864
865 if (strlen(authctxt->style) == 0) {
866 free(authctxt->style);
867 authctxt->style = NULL;
868 }
869
870 return (0);
871 }
872
873 /*
874 * Check that the key type appears in the supplied pattern list, ignoring
875 * mismatches in the signature algorithm. (Signature algorithm checks are
876 * performed in the unprivileged authentication code).
877 * Returns 1 on success, 0 otherwise.
878 */
879 static int
key_base_type_match(const char * method,const struct sshkey * key,const char * list)880 key_base_type_match(const char *method, const struct sshkey *key,
881 const char *list)
882 {
883 char *s, *l, *ol = xstrdup(list);
884 int found = 0;
885
886 l = ol;
887 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) {
888 if (sshkey_type_from_name(s) == key->type) {
889 found = 1;
890 break;
891 }
892 }
893 if (!found) {
894 error("%s key type %s is not in permitted list %s", method,
895 sshkey_ssh_name(key), list);
896 }
897
898 free(ol);
899 return found;
900 }
901
902 int
mm_answer_authpassword(struct ssh * ssh,int sock,struct sshbuf * m)903 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m)
904 {
905 static int call_count;
906 char *passwd;
907 int r, authenticated;
908 size_t plen;
909
910 if (!options.password_authentication)
911 fatal_f("password authentication not enabled");
912 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0)
913 fatal_fr(r, "parse");
914 /* Only authenticate if the context is valid */
915 authenticated = options.password_authentication &&
916 auth_password(ssh, passwd);
917 freezero(passwd, plen);
918
919 sshbuf_reset(m);
920 if ((r = sshbuf_put_u32(m, authenticated)) != 0)
921 fatal_fr(r, "assemble");
922 #ifdef USE_PAM
923 if ((r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0)
924 fatal_fr(r, "assemble PAM");
925 #endif
926
927 debug3("%s: sending result %d", __func__, authenticated);
928 debug3_f("sending result %d", authenticated);
929 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m);
930
931 call_count++;
932 if (plen == 0 && call_count == 1)
933 auth_method = "none";
934 else
935 auth_method = "password";
936
937 /* Causes monitor loop to terminate if authenticated */
938 return (authenticated);
939 }
940
941 #ifdef BSD_AUTH
942 int
mm_answer_bsdauthquery(struct ssh * ssh,int sock,struct sshbuf * m)943 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m)
944 {
945 char *name, *infotxt;
946 u_int numprompts, *echo_on, success;
947 char **prompts;
948 int r;
949
950 if (!options.kbd_interactive_authentication)
951 fatal_f("kbd-int authentication not enabled");
952 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
953 &prompts, &echo_on) < 0 ? 0 : 1;
954
955 sshbuf_reset(m);
956 if ((r = sshbuf_put_u32(m, success)) != 0)
957 fatal_fr(r, "assemble");
958 if (success) {
959 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0)
960 fatal_fr(r, "assemble prompt");
961 }
962
963 debug3_f("sending challenge success: %u", success);
964 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);
965
966 if (success) {
967 free(name);
968 free(infotxt);
969 free(prompts);
970 free(echo_on);
971 }
972
973 return (0);
974 }
975
976 int
mm_answer_bsdauthrespond(struct ssh * ssh,int sock,struct sshbuf * m)977 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m)
978 {
979 char *response;
980 int r, authok;
981
982 if (!options.kbd_interactive_authentication)
983 fatal_f("kbd-int authentication not enabled");
984 if (authctxt->as == NULL)
985 fatal_f("no bsd auth session");
986
987 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0)
988 fatal_fr(r, "parse");
989 authok = options.kbd_interactive_authentication &&
990 auth_userresponse(authctxt->as, response, 0);
991 authctxt->as = NULL;
992 debug3_f("<%s> = <%d>", response, authok);
993 free(response);
994
995 sshbuf_reset(m);
996 if ((r = sshbuf_put_u32(m, authok)) != 0)
997 fatal_fr(r, "assemble");
998
999 debug3_f("sending authenticated: %d", authok);
1000 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
1001
1002 auth_method = "keyboard-interactive";
1003 auth_submethod = "bsdauth";
1004
1005 return (authok != 0);
1006 }
1007 #endif
1008
1009 #ifdef USE_PAM
1010 int
mm_answer_pam_start(struct ssh * ssh,int sock,struct sshbuf * m)1011 mm_answer_pam_start(struct ssh *ssh, int sock, struct sshbuf *m)
1012 {
1013 if (!options.use_pam)
1014 fatal("UsePAM not set, but ended up in %s anyway", __func__);
1015
1016 start_pam(ssh);
1017
1018 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
1019 if (options.kbd_interactive_authentication)
1020 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1021
1022 return (0);
1023 }
1024
1025 int
mm_answer_pam_account(struct ssh * ssh,int sock,struct sshbuf * m)1026 mm_answer_pam_account(struct ssh *ssh, int sock, struct sshbuf *m)
1027 {
1028 u_int ret;
1029 int r;
1030
1031 if (!options.use_pam)
1032 fatal("%s: PAM not enabled", __func__);
1033
1034 ret = do_pam_account();
1035
1036 if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1037 (r = sshbuf_put_stringb(m, loginmsg)) != 0)
1038 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1039
1040 mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m);
1041
1042 return (ret);
1043 }
1044
1045 static void *sshpam_ctxt, *sshpam_authok;
1046 extern KbdintDevice sshpam_device;
1047
1048 int
mm_answer_pam_init_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1049 mm_answer_pam_init_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1050 {
1051 u_int ok = 0;
1052 int r;
1053
1054 debug3("%s", __func__);
1055 if (!options.kbd_interactive_authentication)
1056 fatal("%s: kbd-int authentication not enabled", __func__);
1057 if (sshpam_ctxt != NULL)
1058 fatal("%s: already called", __func__);
1059 sshpam_ctxt = (sshpam_device.init_ctx)(authctxt);
1060 sshpam_authok = NULL;
1061 sshbuf_reset(m);
1062 if (sshpam_ctxt != NULL) {
1063 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1);
1064 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1);
1065 ok = 1;
1066 }
1067 if ((r = sshbuf_put_u32(m, ok)) != 0)
1068 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1069 mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m);
1070 return (0);
1071 }
1072
1073 int
mm_answer_pam_query(struct ssh * ssh,int sock,struct sshbuf * m)1074 mm_answer_pam_query(struct ssh *ssh, int sock, struct sshbuf *m)
1075 {
1076 char *name = NULL, *info = NULL, **prompts = NULL;
1077 u_int i, num = 0, *echo_on = 0;
1078 int r, ret;
1079
1080 debug3("%s", __func__);
1081 sshpam_authok = NULL;
1082 if (sshpam_ctxt == NULL)
1083 fatal("%s: no context", __func__);
1084 ret = (sshpam_device.query)(sshpam_ctxt, &name, &info,
1085 &num, &prompts, &echo_on);
1086 if (ret == 0 && num == 0)
1087 sshpam_authok = sshpam_ctxt;
1088 if (num > 1 || name == NULL || info == NULL)
1089 fatal("sshpam_device.query failed");
1090 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1);
1091 sshbuf_reset(m);
1092 if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1093 (r = sshbuf_put_cstring(m, name)) != 0 ||
1094 (r = sshbuf_put_cstring(m, info)) != 0 ||
1095 (r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0 ||
1096 (r = sshbuf_put_u32(m, num)) != 0)
1097 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1098 free(name);
1099 free(info);
1100 for (i = 0; i < num; ++i) {
1101 if ((r = sshbuf_put_cstring(m, prompts[i])) != 0 ||
1102 (r = sshbuf_put_u32(m, echo_on[i])) != 0)
1103 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1104 free(prompts[i]);
1105 }
1106 free(prompts);
1107 free(echo_on);
1108 auth_method = "keyboard-interactive";
1109 auth_submethod = "pam";
1110 mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m);
1111 return (0);
1112 }
1113
1114 int
mm_answer_pam_respond(struct ssh * ssh,int sock,struct sshbuf * m)1115 mm_answer_pam_respond(struct ssh *ssh, int sock, struct sshbuf *m)
1116 {
1117 char **resp;
1118 u_int i, num;
1119 int r, ret;
1120
1121 debug3("%s", __func__);
1122 if (sshpam_ctxt == NULL)
1123 fatal("%s: no context", __func__);
1124 sshpam_authok = NULL;
1125 if ((r = sshbuf_get_u32(m, &num)) != 0)
1126 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1127 if (num > PAM_MAX_NUM_MSG) {
1128 fatal_f("Too many PAM messages, got %u, expected <= %u",
1129 num, (unsigned)PAM_MAX_NUM_MSG);
1130 }
1131 if (num > 0) {
1132 resp = xcalloc(num, sizeof(char *));
1133 for (i = 0; i < num; ++i) {
1134 if ((r = sshbuf_get_cstring(m, &(resp[i]), NULL)) != 0)
1135 fatal("%s: buffer error: %s",
1136 __func__, ssh_err(r));
1137 }
1138 ret = (sshpam_device.respond)(sshpam_ctxt, num, resp);
1139 for (i = 0; i < num; ++i)
1140 free(resp[i]);
1141 free(resp);
1142 } else {
1143 ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL);
1144 }
1145 sshbuf_reset(m);
1146 if ((r = sshbuf_put_u32(m, ret)) != 0)
1147 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1148 mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m);
1149 auth_method = "keyboard-interactive";
1150 auth_submethod = "pam";
1151 if (ret == 0)
1152 sshpam_authok = sshpam_ctxt;
1153 return (0);
1154 }
1155
1156 int
mm_answer_pam_free_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1157 mm_answer_pam_free_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1158 {
1159 int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt;
1160
1161 debug3("%s", __func__);
1162 if (sshpam_ctxt == NULL)
1163 fatal("%s: no context", __func__);
1164 (sshpam_device.free_ctx)(sshpam_ctxt);
1165 sshpam_ctxt = sshpam_authok = NULL;
1166 sshbuf_reset(m);
1167 mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m);
1168 /* Allow another attempt */
1169 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1170 auth_method = "keyboard-interactive";
1171 auth_submethod = "pam";
1172 return r;
1173 }
1174 #endif
1175
1176 int
mm_answer_keyallowed(struct ssh * ssh,int sock,struct sshbuf * m)1177 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m)
1178 {
1179 struct sshkey *key = NULL;
1180 char *cuser, *chost;
1181 u_int pubkey_auth_attempt;
1182 u_int type = 0;
1183 int r, allowed = 0;
1184 struct sshauthopt *opts = NULL;
1185
1186 debug3_f("entering");
1187 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1188 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 ||
1189 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
1190 (r = sshkey_froms(m, &key)) != 0 ||
1191 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0)
1192 fatal_fr(r, "parse");
1193
1194 if (key != NULL && authctxt->valid) {
1195 switch (type) {
1196 case MM_USERKEY:
1197 auth_method = "publickey";
1198 if (!options.pubkey_authentication)
1199 break;
1200 if (auth2_key_already_used(authctxt, key))
1201 break;
1202 if (!key_base_type_match(auth_method, key,
1203 options.pubkey_accepted_algos))
1204 break;
1205 allowed = user_key_allowed(ssh, authctxt->pw, key,
1206 pubkey_auth_attempt, &opts);
1207 break;
1208 case MM_HOSTKEY:
1209 auth_method = "hostbased";
1210 if (!options.hostbased_authentication)
1211 break;
1212 if (auth2_key_already_used(authctxt, key))
1213 break;
1214 if (!key_base_type_match(auth_method, key,
1215 options.hostbased_accepted_algos))
1216 break;
1217 allowed = hostbased_key_allowed(ssh, authctxt->pw,
1218 cuser, chost, key);
1219 auth2_record_info(authctxt,
1220 "client user \"%.100s\", client host \"%.100s\"",
1221 cuser, chost);
1222 break;
1223 default:
1224 fatal_f("unknown key type %u", type);
1225 break;
1226 }
1227 }
1228
1229 debug3_f("%s authentication%s: %s key is %s", auth_method,
1230 pubkey_auth_attempt ? "" : " test",
1231 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key),
1232 allowed ? "allowed" : "not allowed");
1233
1234 auth2_record_key(authctxt, 0, key);
1235
1236 /* clear temporarily storage (used by verify) */
1237 monitor_reset_key_state();
1238
1239 if (allowed) {
1240 /* Save temporarily for comparison in verify */
1241 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0)
1242 fatal_fr(r, "sshkey_to_blob");
1243 key_blobtype = type;
1244 key_opts = opts;
1245 hostbased_cuser = cuser;
1246 hostbased_chost = chost;
1247 } else {
1248 /* Log failed attempt */
1249 auth_log(ssh, 0, 0, auth_method, NULL);
1250 free(cuser);
1251 free(chost);
1252 }
1253 sshkey_free(key);
1254
1255 sshbuf_reset(m);
1256 if ((r = sshbuf_put_u32(m, allowed)) != 0)
1257 fatal_fr(r, "assemble");
1258 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0)
1259 fatal_fr(r, "sshauthopt_serialise");
1260 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);
1261
1262 if (!allowed)
1263 sshauthopt_free(opts);
1264
1265 return (0);
1266 }
1267
1268 static int
monitor_valid_userblob(struct ssh * ssh,const u_char * data,u_int datalen)1269 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen)
1270 {
1271 struct sshbuf *b;
1272 struct sshkey *hostkey = NULL;
1273 const u_char *p;
1274 char *userstyle, *cp;
1275 size_t len;
1276 u_char type;
1277 int hostbound = 0, r, fail = 0;
1278
1279 if ((b = sshbuf_from(data, datalen)) == NULL)
1280 fatal_f("sshbuf_from");
1281
1282 if (ssh->compat & SSH_OLD_SESSIONID) {
1283 p = sshbuf_ptr(b);
1284 len = sshbuf_len(b);
1285 if ((session_id2 == NULL) ||
1286 (len < session_id2_len) ||
1287 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1288 fail++;
1289 if ((r = sshbuf_consume(b, session_id2_len)) != 0)
1290 fatal_fr(r, "consume");
1291 } else {
1292 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1293 fatal_fr(r, "parse sessionid");
1294 if ((session_id2 == NULL) ||
1295 (len != session_id2_len) ||
1296 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1297 fail++;
1298 }
1299 if ((r = sshbuf_get_u8(b, &type)) != 0)
1300 fatal_fr(r, "parse type");
1301 if (type != SSH2_MSG_USERAUTH_REQUEST)
1302 fail++;
1303 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1304 fatal_fr(r, "parse userstyle");
1305 xasprintf(&userstyle, "%s%s%s", authctxt->user,
1306 authctxt->style ? ":" : "",
1307 authctxt->style ? authctxt->style : "");
1308 if (strcmp(userstyle, cp) != 0) {
1309 logit("wrong user name passed to monitor: "
1310 "expected %s != %.100s", userstyle, cp);
1311 fail++;
1312 }
1313 free(userstyle);
1314 free(cp);
1315 if ((r = sshbuf_skip_string(b)) != 0 || /* service */
1316 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1317 fatal_fr(r, "parse method");
1318 if (strcmp("publickey", cp) != 0) {
1319 if (strcmp("publickey-hostbound-v00@openssh.com", cp) == 0)
1320 hostbound = 1;
1321 else
1322 fail++;
1323 }
1324 free(cp);
1325 if ((r = sshbuf_get_u8(b, &type)) != 0)
1326 fatal_fr(r, "parse pktype");
1327 if (type == 0)
1328 fail++;
1329 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
1330 (r = sshbuf_skip_string(b)) != 0 || /* pkblob */
1331 (hostbound && (r = sshkey_froms(b, &hostkey)) != 0))
1332 fatal_fr(r, "parse pk");
1333 if (sshbuf_len(b) != 0)
1334 fail++;
1335 sshbuf_free(b);
1336 if (hostkey != NULL) {
1337 /*
1338 * Ensure this is actually one of our hostkeys; unfortunately
1339 * can't check ssh->kex->initial_hostkey directly at this point
1340 * as packet state has not yet been exported to monitor.
1341 */
1342 if (get_hostkey_index(hostkey, 1, ssh) == -1)
1343 fatal_f("hostbound hostkey does not match");
1344 sshkey_free(hostkey);
1345 }
1346 return (fail == 0);
1347 }
1348
1349 static int
monitor_valid_hostbasedblob(const u_char * data,u_int datalen,const char * cuser,const char * chost)1350 monitor_valid_hostbasedblob(const u_char *data, u_int datalen,
1351 const char *cuser, const char *chost)
1352 {
1353 struct sshbuf *b;
1354 const u_char *p;
1355 char *cp, *userstyle;
1356 size_t len;
1357 int r, fail = 0;
1358 u_char type;
1359
1360 if ((b = sshbuf_from(data, datalen)) == NULL)
1361 fatal_f("sshbuf_new");
1362 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1363 fatal_fr(r, "parse sessionid");
1364
1365 if ((session_id2 == NULL) ||
1366 (len != session_id2_len) ||
1367 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1368 fail++;
1369
1370 if ((r = sshbuf_get_u8(b, &type)) != 0)
1371 fatal_fr(r, "parse type");
1372 if (type != SSH2_MSG_USERAUTH_REQUEST)
1373 fail++;
1374 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1375 fatal_fr(r, "parse userstyle");
1376 xasprintf(&userstyle, "%s%s%s", authctxt->user,
1377 authctxt->style ? ":" : "",
1378 authctxt->style ? authctxt->style : "");
1379 if (strcmp(userstyle, cp) != 0) {
1380 logit("wrong user name passed to monitor: "
1381 "expected %s != %.100s", userstyle, cp);
1382 fail++;
1383 }
1384 free(userstyle);
1385 free(cp);
1386 if ((r = sshbuf_skip_string(b)) != 0 || /* service */
1387 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1388 fatal_fr(r, "parse method");
1389 if (strcmp(cp, "hostbased") != 0)
1390 fail++;
1391 free(cp);
1392 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
1393 (r = sshbuf_skip_string(b)) != 0) /* pkblob */
1394 fatal_fr(r, "parse pk");
1395
1396 /* verify client host, strip trailing dot if necessary */
1397 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1398 fatal_fr(r, "parse host");
1399 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.')
1400 cp[len - 1] = '\0';
1401 if (strcmp(cp, chost) != 0)
1402 fail++;
1403 free(cp);
1404
1405 /* verify client user */
1406 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1407 fatal_fr(r, "parse ruser");
1408 if (strcmp(cp, cuser) != 0)
1409 fail++;
1410 free(cp);
1411
1412 if (sshbuf_len(b) != 0)
1413 fail++;
1414 sshbuf_free(b);
1415 return (fail == 0);
1416 }
1417
1418 int
mm_answer_keyverify(struct ssh * ssh,int sock,struct sshbuf * m)1419 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m)
1420 {
1421 struct sshkey *key;
1422 const u_char *signature, *data, *blob;
1423 char *sigalg = NULL, *fp = NULL;
1424 size_t signaturelen, datalen, bloblen;
1425 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0;
1426 int encoded_ret;
1427 struct sshkey_sig_details *sig_details = NULL;
1428
1429 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 ||
1430 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 ||
1431 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 ||
1432 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0)
1433 fatal_fr(r, "parse");
1434
1435 if (hostbased_cuser == NULL || hostbased_chost == NULL ||
1436 !monitor_allowed_key(blob, bloblen))
1437 fatal_f("bad key, not previously allowed");
1438
1439 /* Empty signature algorithm means NULL. */
1440 if (*sigalg == '\0') {
1441 free(sigalg);
1442 sigalg = NULL;
1443 }
1444
1445 /* XXX use sshkey_froms here; need to change key_blob, etc. */
1446 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
1447 fatal_fr(r, "parse key");
1448
1449 switch (key_blobtype) {
1450 case MM_USERKEY:
1451 valid_data = monitor_valid_userblob(ssh, data, datalen);
1452 auth_method = "publickey";
1453 break;
1454 case MM_HOSTKEY:
1455 valid_data = monitor_valid_hostbasedblob(data, datalen,
1456 hostbased_cuser, hostbased_chost);
1457 auth_method = "hostbased";
1458 break;
1459 default:
1460 valid_data = 0;
1461 break;
1462 }
1463 if (!valid_data)
1464 fatal_f("bad %s signature data blob",
1465 key_blobtype == MM_USERKEY ? "userkey" :
1466 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown"));
1467
1468 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
1469 SSH_FP_DEFAULT)) == NULL)
1470 fatal_f("sshkey_fingerprint failed");
1471
1472 ret = sshkey_verify(key, signature, signaturelen, data, datalen,
1473 sigalg, ssh->compat, &sig_details);
1474 debug3_f("%s %s signature using %s %s%s%s", auth_method,
1475 sshkey_type(key), sigalg == NULL ? "default" : sigalg,
1476 (ret == 0) ? "verified" : "unverified",
1477 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : "");
1478
1479 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) {
1480 req_presence = (options.pubkey_auth_options &
1481 PUBKEYAUTH_TOUCH_REQUIRED) ||
1482 !key_opts->no_require_user_presence;
1483 if (req_presence &&
1484 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) {
1485 error("public key %s %s signature for %s%s from %.128s "
1486 "port %d rejected: user presence "
1487 "(authenticator touch) requirement not met ",
1488 sshkey_type(key), fp,
1489 authctxt->valid ? "" : "invalid user ",
1490 authctxt->user, ssh_remote_ipaddr(ssh),
1491 ssh_remote_port(ssh));
1492 ret = SSH_ERR_SIGNATURE_INVALID;
1493 }
1494 req_verify = (options.pubkey_auth_options &
1495 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify;
1496 if (req_verify &&
1497 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) {
1498 error("public key %s %s signature for %s%s from %.128s "
1499 "port %d rejected: user verification requirement "
1500 "not met ", sshkey_type(key), fp,
1501 authctxt->valid ? "" : "invalid user ",
1502 authctxt->user, ssh_remote_ipaddr(ssh),
1503 ssh_remote_port(ssh));
1504 ret = SSH_ERR_SIGNATURE_INVALID;
1505 }
1506 }
1507 auth2_record_key(authctxt, ret == 0, key);
1508
1509 if (key_blobtype == MM_USERKEY && ret == 0)
1510 auth_activate_options(ssh, key_opts);
1511 monitor_reset_key_state();
1512
1513 sshbuf_reset(m);
1514
1515 /* encode ret != 0 as positive integer, since we're sending u32 */
1516 encoded_ret = (ret != 0);
1517 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 ||
1518 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0)
1519 fatal_fr(r, "assemble");
1520 if (sig_details != NULL) {
1521 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 ||
1522 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0)
1523 fatal_fr(r, "assemble sk");
1524 }
1525 sshkey_sig_details_free(sig_details);
1526 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
1527
1528 free(sigalg);
1529 free(fp);
1530 sshkey_free(key);
1531
1532 return ret == 0;
1533 }
1534
1535 static void
mm_record_login(struct ssh * ssh,Session * s,struct passwd * pw)1536 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw)
1537 {
1538 socklen_t fromlen;
1539 struct sockaddr_storage from;
1540
1541 /*
1542 * Get IP address of client. If the connection is not a socket, let
1543 * the address be 0.0.0.0.
1544 */
1545 memset(&from, 0, sizeof(from));
1546 fromlen = sizeof(from);
1547 if (ssh_packet_connection_is_on_socket(ssh)) {
1548 if (getpeername(ssh_packet_get_connection_in(ssh),
1549 (struct sockaddr *)&from, &fromlen) == -1) {
1550 debug("getpeername: %.100s", strerror(errno));
1551 cleanup_exit(255);
1552 }
1553 }
1554 /* Record that there was a login on that tty from the remote host. */
1555 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid,
1556 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns),
1557 (struct sockaddr *)&from, fromlen);
1558 }
1559
1560 static void
mm_session_close(Session * s)1561 mm_session_close(Session *s)
1562 {
1563 debug3_f("session %d pid %ld", s->self, (long)s->pid);
1564 if (s->ttyfd != -1) {
1565 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd);
1566 session_pty_cleanup2(s);
1567 }
1568 session_unused(s->self);
1569 }
1570
1571 int
mm_answer_pty(struct ssh * ssh,int sock,struct sshbuf * m)1572 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m)
1573 {
1574 extern struct monitor *pmonitor;
1575 Session *s;
1576 int r, res, fd0;
1577
1578 debug3_f("entering");
1579
1580 sshbuf_reset(m);
1581 s = session_new();
1582 if (s == NULL)
1583 goto error;
1584 s->authctxt = authctxt;
1585 s->pw = authctxt->pw;
1586 s->pid = pmonitor->m_pid;
1587 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
1588 if (res == 0)
1589 goto error;
1590 pty_setowner(authctxt->pw, s->tty);
1591
1592 if ((r = sshbuf_put_u32(m, 1)) != 0 ||
1593 (r = sshbuf_put_cstring(m, s->tty)) != 0)
1594 fatal_fr(r, "assemble");
1595
1596 /* We need to trick ttyslot */
1597 if (dup2(s->ttyfd, 0) == -1)
1598 fatal_f("dup2");
1599
1600 mm_record_login(ssh, s, authctxt->pw);
1601
1602 /* Now we can close the file descriptor again */
1603 close(0);
1604
1605 /* send messages generated by record_login */
1606 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0)
1607 fatal_fr(r, "assemble loginmsg");
1608 sshbuf_reset(loginmsg);
1609
1610 mm_request_send(sock, MONITOR_ANS_PTY, m);
1611
1612 if (mm_send_fd(sock, s->ptyfd) == -1 ||
1613 mm_send_fd(sock, s->ttyfd) == -1)
1614 fatal_f("send fds failed");
1615
1616 /* make sure nothing uses fd 0 */
1617 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1618 fatal_f("open(/dev/null): %s", strerror(errno));
1619 if (fd0 != 0)
1620 error_f("fd0 %d != 0", fd0);
1621
1622 /* slave side of pty is not needed */
1623 close(s->ttyfd);
1624 s->ttyfd = s->ptyfd;
1625 /* no need to dup() because nobody closes ptyfd */
1626 s->ptymaster = s->ptyfd;
1627
1628 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd);
1629
1630 return (0);
1631
1632 error:
1633 if (s != NULL)
1634 mm_session_close(s);
1635 if ((r = sshbuf_put_u32(m, 0)) != 0)
1636 fatal_fr(r, "assemble 0");
1637 mm_request_send(sock, MONITOR_ANS_PTY, m);
1638 return (0);
1639 }
1640
1641 int
mm_answer_pty_cleanup(struct ssh * ssh,int sock,struct sshbuf * m)1642 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m)
1643 {
1644 Session *s;
1645 char *tty;
1646 int r;
1647
1648 debug3_f("entering");
1649
1650 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0)
1651 fatal_fr(r, "parse tty");
1652 if ((s = session_by_tty(tty)) != NULL)
1653 mm_session_close(s);
1654 sshbuf_reset(m);
1655 free(tty);
1656 return (0);
1657 }
1658
1659 int
mm_answer_term(struct ssh * ssh,int sock,struct sshbuf * req)1660 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req)
1661 {
1662 extern struct monitor *pmonitor;
1663 int res, status;
1664
1665 debug3_f("tearing down sessions");
1666
1667 /* The child is terminating */
1668 session_destroy_all(ssh, &mm_session_close);
1669
1670 #ifdef USE_PAM
1671 if (options.use_pam)
1672 sshpam_cleanup();
1673 #endif
1674
1675 while (waitpid(pmonitor->m_pid, &status, 0) == -1)
1676 if (errno != EINTR)
1677 exit(1);
1678
1679 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
1680
1681 /* Terminate process */
1682 exit(res);
1683 }
1684
1685 #ifdef SSH_AUDIT_EVENTS
1686 /* Report that an audit event occurred */
1687 int
mm_answer_audit_event(struct ssh * ssh,int socket,struct sshbuf * m)1688 mm_answer_audit_event(struct ssh *ssh, int socket, struct sshbuf *m)
1689 {
1690 u_int n;
1691 ssh_audit_event_t event;
1692 int r;
1693
1694 debug3("%s entering", __func__);
1695
1696 if ((r = sshbuf_get_u32(m, &n)) != 0)
1697 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1698 event = (ssh_audit_event_t)n;
1699 switch (event) {
1700 case SSH_AUTH_FAIL_PUBKEY:
1701 case SSH_AUTH_FAIL_HOSTBASED:
1702 case SSH_AUTH_FAIL_GSSAPI:
1703 case SSH_LOGIN_EXCEED_MAXTRIES:
1704 case SSH_LOGIN_ROOT_DENIED:
1705 case SSH_CONNECTION_CLOSE:
1706 case SSH_INVALID_USER:
1707 audit_event(ssh, event);
1708 break;
1709 default:
1710 fatal("Audit event type %d not permitted", event);
1711 }
1712
1713 return (0);
1714 }
1715
1716 int
mm_answer_audit_command(struct ssh * ssh,int socket,struct sshbuf * m)1717 mm_answer_audit_command(struct ssh *ssh, int socket, struct sshbuf *m)
1718 {
1719 char *cmd;
1720 int r;
1721
1722 debug3("%s entering", __func__);
1723 if ((r = sshbuf_get_cstring(m, &cmd, NULL)) != 0)
1724 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1725 /* sanity check command, if so how? */
1726 audit_run_command(cmd);
1727 free(cmd);
1728 return (0);
1729 }
1730 #endif /* SSH_AUDIT_EVENTS */
1731
1732 void
monitor_clear_keystate(struct ssh * ssh,struct monitor * pmonitor)1733 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor)
1734 {
1735 ssh_clear_newkeys(ssh, MODE_IN);
1736 ssh_clear_newkeys(ssh, MODE_OUT);
1737 sshbuf_free(child_state);
1738 child_state = NULL;
1739 }
1740
1741 void
monitor_apply_keystate(struct ssh * ssh,struct monitor * pmonitor)1742 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor)
1743 {
1744 struct kex *kex;
1745 int r;
1746
1747 debug3_f("packet_set_state");
1748 if ((r = ssh_packet_set_state(ssh, child_state)) != 0)
1749 fatal_fr(r, "packet_set_state");
1750 sshbuf_free(child_state);
1751 child_state = NULL;
1752 if ((kex = ssh->kex) == NULL)
1753 fatal_f("internal error: ssh->kex == NULL");
1754 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) {
1755 fatal_f("incorrect session id length %zu (expected %u)",
1756 sshbuf_len(ssh->kex->session_id), session_id2_len);
1757 }
1758 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2,
1759 session_id2_len) != 0)
1760 fatal_f("session ID mismatch");
1761 /* XXX set callbacks */
1762 #ifdef WITH_OPENSSL
1763 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
1764 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
1765 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
1766 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
1767 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
1768 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1769 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1770 # ifdef OPENSSL_HAS_ECC
1771 kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
1772 # endif
1773 #endif /* WITH_OPENSSL */
1774 kex->kex[KEX_C25519_SHA256] = kex_gen_server;
1775 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
1776 kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server;
1777 kex->load_host_public_key=&get_hostkey_public_by_type;
1778 kex->load_host_private_key=&get_hostkey_private_by_type;
1779 kex->host_key_index=&get_hostkey_index;
1780 kex->sign = sshd_hostkey_sign;
1781 }
1782
1783 /* This function requires careful sanity checking */
1784
1785 void
mm_get_keystate(struct ssh * ssh,struct monitor * pmonitor)1786 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor)
1787 {
1788 debug3_f("Waiting for new keys");
1789
1790 if ((child_state = sshbuf_new()) == NULL)
1791 fatal_f("sshbuf_new failed");
1792 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT,
1793 child_state);
1794 debug3_f("GOT new keys");
1795 }
1796
1797
1798 /* XXX */
1799
1800 #define FD_CLOSEONEXEC(x) do { \
1801 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \
1802 fatal("fcntl(%d, F_SETFD)", x); \
1803 } while (0)
1804
1805 static void
monitor_openfds(struct monitor * mon,int do_logfds)1806 monitor_openfds(struct monitor *mon, int do_logfds)
1807 {
1808 int pair[2];
1809 #ifdef SO_ZEROIZE
1810 int on = 1;
1811 #endif
1812
1813 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
1814 fatal_f("socketpair: %s", strerror(errno));
1815 #ifdef SO_ZEROIZE
1816 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1817 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno));
1818 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1819 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno));
1820 #endif
1821 FD_CLOSEONEXEC(pair[0]);
1822 FD_CLOSEONEXEC(pair[1]);
1823 mon->m_recvfd = pair[0];
1824 mon->m_sendfd = pair[1];
1825
1826 if (do_logfds) {
1827 if (pipe(pair) == -1)
1828 fatal_f("pipe: %s", strerror(errno));
1829 FD_CLOSEONEXEC(pair[0]);
1830 FD_CLOSEONEXEC(pair[1]);
1831 mon->m_log_recvfd = pair[0];
1832 mon->m_log_sendfd = pair[1];
1833 } else
1834 mon->m_log_recvfd = mon->m_log_sendfd = -1;
1835 }
1836
1837 #define MM_MEMSIZE 65536
1838
1839 struct monitor *
monitor_init(void)1840 monitor_init(void)
1841 {
1842 struct monitor *mon;
1843
1844 mon = xcalloc(1, sizeof(*mon));
1845 monitor_openfds(mon, 1);
1846
1847 return mon;
1848 }
1849
1850 void
monitor_reinit(struct monitor * mon)1851 monitor_reinit(struct monitor *mon)
1852 {
1853 monitor_openfds(mon, 0);
1854 }
1855
1856 #ifdef GSSAPI
1857 int
mm_answer_gss_setup_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1858 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1859 {
1860 gss_OID_desc goid;
1861 OM_uint32 major;
1862 size_t len;
1863 u_char *p;
1864 int r;
1865
1866 if (!options.gss_authentication)
1867 fatal_f("GSSAPI authentication not enabled");
1868
1869 if ((r = sshbuf_get_string(m, &p, &len)) != 0)
1870 fatal_fr(r, "parse");
1871 goid.elements = p;
1872 goid.length = len;
1873
1874 major = ssh_gssapi_server_ctx(&gsscontext, &goid);
1875
1876 free(goid.elements);
1877
1878 sshbuf_reset(m);
1879 if ((r = sshbuf_put_u32(m, major)) != 0)
1880 fatal_fr(r, "assemble");
1881
1882 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m);
1883
1884 /* Now we have a context, enable the step */
1885 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1);
1886
1887 return (0);
1888 }
1889
1890 int
mm_answer_gss_accept_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1891 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1892 {
1893 gss_buffer_desc in;
1894 gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
1895 OM_uint32 major, minor;
1896 OM_uint32 flags = 0; /* GSI needs this */
1897 int r;
1898
1899 if (!options.gss_authentication)
1900 fatal_f("GSSAPI authentication not enabled");
1901
1902 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
1903 fatal_fr(r, "ssh_gssapi_get_buffer_desc");
1904 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
1905 free(in.value);
1906
1907 sshbuf_reset(m);
1908 if ((r = sshbuf_put_u32(m, major)) != 0 ||
1909 (r = sshbuf_put_string(m, out.value, out.length)) != 0 ||
1910 (r = sshbuf_put_u32(m, flags)) != 0)
1911 fatal_fr(r, "assemble");
1912 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m);
1913
1914 gss_release_buffer(&minor, &out);
1915
1916 if (major == GSS_S_COMPLETE) {
1917 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
1918 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1919 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
1920 }
1921 return (0);
1922 }
1923
1924 int
mm_answer_gss_checkmic(struct ssh * ssh,int sock,struct sshbuf * m)1925 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
1926 {
1927 gss_buffer_desc gssbuf, mic;
1928 OM_uint32 ret;
1929 int r;
1930
1931 if (!options.gss_authentication)
1932 fatal_f("GSSAPI authentication not enabled");
1933
1934 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
1935 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
1936 fatal_fr(r, "ssh_gssapi_get_buffer_desc");
1937
1938 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
1939
1940 free(gssbuf.value);
1941 free(mic.value);
1942
1943 sshbuf_reset(m);
1944 if ((r = sshbuf_put_u32(m, ret)) != 0)
1945 fatal_fr(r, "assemble");
1946
1947 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m);
1948
1949 if (!GSS_ERROR(ret))
1950 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1951
1952 return (0);
1953 }
1954
1955 int
mm_answer_gss_userok(struct ssh * ssh,int sock,struct sshbuf * m)1956 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
1957 {
1958 int r, authenticated;
1959 const char *displayname;
1960
1961 if (!options.gss_authentication)
1962 fatal_f("GSSAPI authentication not enabled");
1963
1964 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
1965
1966 sshbuf_reset(m);
1967 if ((r = sshbuf_put_u32(m, authenticated)) != 0)
1968 fatal_fr(r, "assemble");
1969
1970 debug3_f("sending result %d", authenticated);
1971 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
1972
1973 auth_method = "gssapi-with-mic";
1974
1975 if ((displayname = ssh_gssapi_displayname()) != NULL)
1976 auth2_record_info(authctxt, "%s", displayname);
1977
1978 /* Monitor loop will terminate if authenticated */
1979 return (authenticated);
1980 }
1981 #endif /* GSSAPI */
1982
1983